Sensors

28 pages, 946 KiB

Open AccessArticle

ROSA: Resource-Oriented Service Management Schemes for Web of Things in a Smart Home

by Chun-Feng Liao^1,2,*,†

and Peng-Yu Chen³

¹ Department of Computer Science, National Chengchi University, Taipei 11605, Taiwan

² Program in Digital Content and Technologies, National Chengchi University, Taipei 11605, Taiwan

³ StarVedia Corporation Inc., Zhubei 302, Taiwan

^† Current address: Department of Computer Science, National Chengchi University, NO.64, Section 2, ZhiNan Rd., Wenshan District, Taipei 11605, Taiwan.

Sensors 2017, 17(10), 2159; https://doi.org/10.3390/s17102159 - 21 Sep 2017

Cited by 42 | Viewed by 6470

Abstract

A Pervasive-computing-enriched smart home environment, which contains many embedded and tiny intelligent devices and sensors coordinated by service management mechanisms, is capable of anticipating intentions of occupants and providing appropriate services accordingly. Although there are a wealth of research achievements in recent years, [...] Read more.

A Pervasive-computing-enriched smart home environment, which contains many embedded and tiny intelligent devices and sensors coordinated by service management mechanisms, is capable of anticipating intentions of occupants and providing appropriate services accordingly. Although there are a wealth of research achievements in recent years, the degree of market acceptance is still low. The main reason is that most of the devices and services in such environments depend on particular platform or technology, making it hard to develop an application by composing the devices or services. Meanwhile, the concept of Web of Things (WoT) is becoming popular recently. Based on WoT, the developers can build applications based on popular web tools or technologies. Consequently, the objective of this paper is to propose a set of novel WoT-driven plug-and-play service management schemes for a smart home called Resource-Oriented Service Administration (ROSA). We have implemented an application prototype, and experiments are performed to show the effectiveness of the proposed approach. The results of this research can be a foundation for realizing the vision of “end user programmable smart environments”. Full article

(This article belongs to the Special Issue Advances in Sensors for Sustainable Smart Cities and Smart Buildings)

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17 pages, 1298 KiB

Open AccessArticle

Spatial Copula Model for Imputing Traffic Flow Data from Remote Microwave Sensors

by Xiaolei Ma^1,2, Sen Luan¹

, Bowen Du^3,* and Bin Yu¹

¹ School of Transportation Science and Engineering, Beijing Key Laboratory for Cooperative Vehicle Infrastructure System and Safety Control, Beihang University, Beijing 100191, China

² Key Laboratory of Road & Traffic Engineering of the Ministry of Education, Tongji University, 4800 Cao’an Road, Shanghai 201804, China

³ School of Computer Science and Engineering, the State Key Laboratory of Software Development Environment, Beihang University, Beijing 100191, China

Sensors 2017, 17(10), 2160; https://doi.org/10.3390/s17102160 - 21 Sep 2017

Cited by 19 | Viewed by 5234

Abstract

Issues of missing data have become increasingly serious with the rapid increase in usage of traffic sensors. Analyses of the Beijing ring expressway have showed that up to 50% of microwave sensors pose missing values. The imputation of missing traffic data must be [...] Read more.

Issues of missing data have become increasingly serious with the rapid increase in usage of traffic sensors. Analyses of the Beijing ring expressway have showed that up to 50% of microwave sensors pose missing values. The imputation of missing traffic data must be urgently solved although a precise solution that cannot be easily achieved due to the significant number of missing portions. In this study, copula-based models are proposed for the spatial interpolation of traffic flow from remote traffic microwave sensors. Most existing interpolation methods only rely on covariance functions to depict spatial correlation and are unsuitable for coping with anomalies due to Gaussian consumption. Copula theory overcomes this issue and provides a connection between the correlation function and the marginal distribution function of traffic flow. To validate copula-based models, a comparison with three kriging methods is conducted. Results indicate that copula-based models outperform kriging methods, especially on roads with irregular traffic patterns. Copula-based models demonstrate significant potential to impute missing data in large-scale transportation networks. Full article

(This article belongs to the Special Issue Sensor Networks for Smart Roads)

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24 pages, 5048 KiB

Open AccessReview

Graphene-Based Materials for Biosensors: A Review

by Phitsini Suvarnaphaet and Suejit Pechprasarn^*

Faculty of Biomedical Engineering, Rangsit University, Pathum Thani 12000, Thailand

Sensors 2017, 17(10), 2161; https://doi.org/10.3390/s17102161 - 21 Sep 2017

Cited by 360 | Viewed by 26738

Abstract

The advantages conferred by the physical, optical and electrochemical properties of graphene-based nanomaterials have contributed to the current variety of ultrasensitive and selective biosensor devices. In this review, we present the points of view on the intrinsic properties of graphene and its surface [...] Read more.

The advantages conferred by the physical, optical and electrochemical properties of graphene-based nanomaterials have contributed to the current variety of ultrasensitive and selective biosensor devices. In this review, we present the points of view on the intrinsic properties of graphene and its surface engineering concerned with the transduction mechanisms in biosensing applications. We explain practical synthesis techniques along with prospective properties of the graphene-based materials, which include the pristine graphene and functionalized graphene (i.e., graphene oxide (GO), reduced graphene oxide (RGO) and graphene quantum dot (GQD). The biosensing mechanisms based on the utilization of the charge interactions with biomolecules and/or nanoparticle interactions and sensing platforms are also discussed, and the importance of surface functionalization in recent up-to-date biosensors for biological and medical applications. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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15 pages, 6891 KiB

Open AccessArticle

An Architecture for On-Line Measurement of the Tip Clearance and Time of Arrival of a Bladed Disk of an Aircraft Engine

by José Miguel Gil-García^1,*

, Alejandro Solís², Gerardo Aranguren² and Joseba Zubia³

¹ Department of Electronic Technology, University of the Basque Country, Nieves Cano 12, 01006 Vitoria-Gasteiz, Spain

² Department of Electronic Technology, University of the Basque Country, Alda. Urquijo s/n, 48013 Bilbao, Spain

³ Department of Communications Engineering, University of the Basque Country, Alda. Urquijo s/n, 48013 Bilbao, Spain

Sensors 2017, 17(10), 2162; https://doi.org/10.3390/s17102162 - 21 Sep 2017

Cited by 29 | Viewed by 7005

Abstract

Safety and performance of the turbo-engine in an aircraft is directly affected by the health of its blades. In recent years, several improvements to the sensors have taken place to monitor the blades in a non-intrusive way. The parameters that are usually measured [...] Read more.

Safety and performance of the turbo-engine in an aircraft is directly affected by the health of its blades. In recent years, several improvements to the sensors have taken place to monitor the blades in a non-intrusive way. The parameters that are usually measured are the distance between the blade tip and the casing, and the passing time at a given point. Simultaneously, several techniques have been developed that allow for the inference—from those parameters and under certain conditions—of the amplitude and frequency of the blade vibration. These measurements are carried out on engines set on a rig, before being installed in an airplane. In order to incorporate these methods during the regular operation of the engine, signal processing that allows for the monitoring of those parameters at all times should be developed. This article introduces an architecture, based on a trifurcated optic sensor and a hardware processor, that fulfills this need. The proposed architecture is scalable and allows several sensors to be simultaneously monitored at different points around a bladed disk. Furthermore, the results obtained by the electronic system will be compared with the results obtained by the validation of the optic sensor. Full article

(This article belongs to the Special Issue Novel Methodologies to Interpret Non-Destructive Testing and Structural Health Monitoring Data)

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11 pages, 3132 KiB

Open AccessArticle

Microwave Deposition of Palladium Catalysts on Graphite Spheres and Reduced Graphene Oxide Sheets for Electrochemical Glucose Sensing

by Jian-De Xie^*, Siyong Gu

and Houan Zhang

Fujian Provincial Key Laboratory of Functional Materials and Applications, School of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024, China

Sensors 2017, 17(10), 2163; https://doi.org/10.3390/s17102163 - 21 Sep 2017

Cited by 7 | Viewed by 5652

Abstract

This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd) nanocrystals on a graphite sphere (GS) and reduced graphene oxide (rGO) supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR). The pulse microwave approach takes a short period [...] Read more.

This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd) nanocrystals on a graphite sphere (GS) and reduced graphene oxide (rGO) supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR). The pulse microwave approach takes a short period (i.e., 10 min) to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR. The enhanced performance is mainly attributed to the synergetic effect that combines small crystalline size and two-dimensional conductive support, imparting high accessibility to non-enzymatic GOR. The rGO sheets serve as a conductive scaffold, capable of fast conducting electron. The linear plot of current response versus glucose concentration exhibits good correlations within the range of 1–12 mM. The sensitivity of the Pd-rGO catalyst is significantly enhanced by 3.7 times, as compared to the Pd-GS catalyst. Accordingly, the Pd-rGO catalyst electrode can be considered as a potential candidate for non-enzymatic glucose biosensor. Full article

(This article belongs to the Special Issue Advanced Sensors Based on Carbon Electrodes)

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22 pages, 4441 KiB

Open AccessArticle

Pose Estimation of a Mobile Robot Based on Fusion of IMU Data and Vision Data Using an Extended Kalman Filter

by Mary B. Alatise^1,* and Gerhard P. Hancke^1,2

¹ Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria 0028, South Africa

² Department of Computer Science, City University of Hong Kong, Hong Kong, China

Sensors 2017, 17(10), 2164; https://doi.org/10.3390/s17102164 - 21 Sep 2017

Cited by 171 | Viewed by 21451

Abstract

Using a single sensor to determine the pose estimation of a device cannot give accurate results. This paper presents a fusion of an inertial sensor of six degrees of freedom (6-DoF) which comprises the 3-axis of an accelerometer and the 3-axis of a [...] Read more.

Using a single sensor to determine the pose estimation of a device cannot give accurate results. This paper presents a fusion of an inertial sensor of six degrees of freedom (6-DoF) which comprises the 3-axis of an accelerometer and the 3-axis of a gyroscope, and a vision to determine a low-cost and accurate position for an autonomous mobile robot. For vision, a monocular vision-based object detection algorithm speeded-up robust feature (SURF) and random sample consensus (RANSAC) algorithms were integrated and used to recognize a sample object in several images taken. As against the conventional method that depend on point-tracking, RANSAC uses an iterative method to estimate the parameters of a mathematical model from a set of captured data which contains outliers. With SURF and RANSAC, improved accuracy is certain; this is because of their ability to find interest points (features) under different viewing conditions using a Hessain matrix. This approach is proposed because of its simple implementation, low cost, and improved accuracy. With an extended Kalman filter (EKF), data from inertial sensors and a camera were fused to estimate the position and orientation of the mobile robot. All these sensors were mounted on the mobile robot to obtain an accurate localization. An indoor experiment was carried out to validate and evaluate the performance. Experimental results show that the proposed method is fast in computation, reliable and robust, and can be considered for practical applications. The performance of the experiments was verified by the ground truth data and root mean square errors (RMSEs). Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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28 pages, 11916 KiB

Open AccessArticle

ZY3-02 Laser Altimeter Footprint Geolocation Prediction

by Junfeng Xie^1,2,3, Xinming Tang^1,2,4, Fan Mo^1,*, Guoyuan Li¹, Guangbin Zhu^1,2, Zhenming Wang¹, Xingke Fu^1,2, Xiaoming Gao^1,2 and Xianhui Dou¹

¹ Satellite Surveying and Mapping Application Center, NASG, Beijing 100048, China

² Key Laboratory of Satellite Surveying and Mapping Technology and Application, NASG, Beijing 100048, China

³ School of Surveying and Geographical Science, Liaoning Technology University, Fuxin 123000, China

⁴ School of Earth Science and Engineering, Hohai University, Nanjing 211100, China

Sensors 2017, 17(10), 2165; https://doi.org/10.3390/s17102165 - 21 Sep 2017

Cited by 20 | Viewed by 6203

Abstract

Successfully launched on 30 May 2016, ZY3-02 is the first Chinese surveying and mapping satellite equipped with a lightweight laser altimeter. Calibration is necessary before the laser altimeter becomes operational. Laser footprint location prediction is the first step in calibration that is based [...] Read more.

Successfully launched on 30 May 2016, ZY3-02 is the first Chinese surveying and mapping satellite equipped with a lightweight laser altimeter. Calibration is necessary before the laser altimeter becomes operational. Laser footprint location prediction is the first step in calibration that is based on ground infrared detectors, and it is difficult because the sample frequency of the ZY3-02 laser altimeter is 2 Hz, and the distance between two adjacent laser footprints is about 3.5 km. In this paper, we build an on-orbit rigorous geometric prediction model referenced to the rigorous geometric model of optical remote sensing satellites. The model includes three kinds of data that must be predicted: pointing angle, orbit parameters, and attitude angles. The proposed method is verified by a ZY3-02 laser altimeter on-orbit geometric calibration test. Five laser footprint prediction experiments are conducted based on the model, and the laser footprint prediction accuracy is better than 150 m on the ground. The effectiveness and accuracy of the on-orbit rigorous geometric prediction model are confirmed by the test results. The geolocation is predicted precisely by the proposed method, and this will give a reference to the geolocation prediction of future land laser detectors in other laser altimeter calibration test. Full article

(This article belongs to the Section Physical Sensors)

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29 pages, 3741 KiB

Open AccessArticle

Design and Analysis of an Efficient Energy Algorithm in Wireless Social Sensor Networks

by Naixue Xiong^1,2

, Longzhen Zhang¹, Wei Zhang^3,*, Athanasios V. Vasilakos⁴ and Muhammad Imran⁵

¹ School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China

² Department of Mathematics and Computer Science, Northeastern State University, Tahlequah, OK 74464, USA

³ Department of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou 310037, China

⁴ Department of Computer Science, Electrical and Space Engineering, Lulea University of Technology, 97187 Lulea, Sweden

⁵ College of Computer and Information Sciences, Almuzahmiyah, King Saud University, Riyadh 11451, Saudi Arabia

Sensors 2017, 17(10), 2166; https://doi.org/10.3390/s17102166 - 21 Sep 2017

Cited by 3 | Viewed by 4164

Abstract

Because mobile ad hoc networks have characteristics such as lack of center nodes, multi-hop routing and changeable topology, the existing checkpoint technologies for normal mobile networks cannot be applied well to mobile ad hoc networks. Considering the multi-frequency hierarchy structure of ad hoc [...] Read more.

Because mobile ad hoc networks have characteristics such as lack of center nodes, multi-hop routing and changeable topology, the existing checkpoint technologies for normal mobile networks cannot be applied well to mobile ad hoc networks. Considering the multi-frequency hierarchy structure of ad hoc networks, this paper proposes a hybrid checkpointing strategy which combines the techniques of synchronous checkpointing with asynchronous checkpointing, namely the checkpoints of mobile terminals in the same cluster remain synchronous, and the checkpoints in different clusters remain asynchronous. This strategy could not only avoid cascading rollback among the processes in the same cluster, but also avoid too many message transmissions among the processes in different clusters. What is more, it can reduce the communication delay. In order to assure the consistency of the global states, this paper discusses the correctness criteria of hybrid checkpointing, which includes the criteria of checkpoint taking, rollback recovery and indelibility. Based on the designed Intra-Cluster Checkpoint Dependence Graph and Inter-Cluster Checkpoint Dependence Graph, the elimination rules for different kinds of checkpoints are discussed, and the algorithms for the same cluster checkpoints, different cluster checkpoints, and rollback recovery are also given. Experimental results demonstrate the proposed hybrid checkpointing strategy is a preferable trade-off method, which not only synthetically takes all kinds of resource constraints of Ad hoc networks into account, but also outperforms the existing schemes in terms of the dependence to cluster heads, the recovery time compared to the pure synchronous, and the pure asynchronous checkpoint advantage. Full article

(This article belongs to the Special Issue Sensor Intelligent Data Analysis for Social Networks: Theory and Applications)

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22 pages, 12348 KiB

Open AccessArticle

Mobile-Based Analysis of Malaria-Infected Thin Blood Smears: Automated Species and Life Cycle Stage Determination

by Luís Rosado^1,*

, José M. Correia Da Costa², Dirk Elias¹ and Jaime S. Cardoso³

¹ Fraunhofer Portugal AICOS, Rua Alfredo Allen 455/461, 4200-135 Porto, Portugal

² Instituto Nacional de Saúde Dr. Ricardo Jorge, Rua Alexandre Herculano 321, 4000-055 Porto, Portugal

³ INESC TEC (Institute for Systems and Computer Engineering, Technology and Science) and Department of Electrical and Computer Engineering of the Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

Sensors 2017, 17(10), 2167; https://doi.org/10.3390/s17102167 - 21 Sep 2017

Cited by 37 | Viewed by 18896

Abstract

Microscopy examination has been the pillar of malaria diagnosis, being the recommended procedure when its quality can be maintained. However, the need for trained personnel and adequate equipment limits its availability and accessibility in malaria-endemic areas. Rapid, accurate, accessible diagnostic tools are increasingly [...] Read more.

Microscopy examination has been the pillar of malaria diagnosis, being the recommended procedure when its quality can be maintained. However, the need for trained personnel and adequate equipment limits its availability and accessibility in malaria-endemic areas. Rapid, accurate, accessible diagnostic tools are increasingly required, as malaria control programs extend parasite-based diagnosis and the prevalence decreases. This paper presents an image processing and analysis methodology using supervised classification to assess the presence of malaria parasites and determine the species and life cycle stage in Giemsa-stained thin blood smears. The main differentiation factor is the usage of microscopic images exclusively acquired with low cost and accessible tools such as smartphones, a dataset of 566 images manually annotated by an experienced parasilogist being used. Eight different species-stage combinations were considered in this work, with an automatic detection performance ranging from 73.9% to 96.2% in terms of sensitivity and from 92.6% to 99.3% in terms of specificity. These promising results attest to the potential of using this approach as a valid alternative to conventional microscopy examination, with comparable detection performances and acceptable computational times. Full article

(This article belongs to the Special Issue Smart Sensor Networks and Technology for Healthcare Monitoring and Decision Making)

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15 pages, 1737 KiB

Open AccessArticle

A Multi-Objective Partition Method for Marine Sensor Networks Based on Degree of Event Correlation

by Dongmei Huang, Chenyixuan Xu

, Danfeng Zhao^*, Wei Song

and Qi He

College of Information Technology, Shanghai Ocean University, Shanghai 201306, China

Sensors 2017, 17(10), 2168; https://doi.org/10.3390/s17102168 - 21 Sep 2017

Cited by 3 | Viewed by 4531

Abstract

Existing marine sensor networks acquire data from sea areas that are geographically divided, and store the data independently in their affiliated sea area data centers. In the case of marine events across multiple sea areas, the current network structure needs to retrieve data [...] Read more.

Existing marine sensor networks acquire data from sea areas that are geographically divided, and store the data independently in their affiliated sea area data centers. In the case of marine events across multiple sea areas, the current network structure needs to retrieve data from multiple data centers, and thus severely affects real-time decision making. In this study, in order to provide a fast data retrieval service for a marine sensor network, we use all the marine sensors as the vertices, establish the edge based on marine events, and abstract the marine sensor network as a graph. Then, we construct a multi-objective balanced partition method to partition the abstract graph into multiple regions and store them in the cloud computing platform. This method effectively increases the correlation of the sensors and decreases the retrieval cost. On this basis, an incremental optimization strategy is designed to dynamically optimize existing partitions when new sensors are added into the network. Experimental results show that the proposed method can achieve the optimal layout for distributed storage in the process of disaster data retrieval in the China Sea area, and effectively optimize the result of partitions when new buoys are deployed, which eventually will provide efficient data access service for marine events. Full article

(This article belongs to the Special Issue Marine Sensing)

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22 pages, 1323 KiB

Open AccessArticle

Exploiting the Capture Effect to Enhance RACH Performance in Cellular-Based M2M Communications

by Jonghun Kim

and Jaiyong Lee^*

Ubiquitous Network Laboratory, School of Electrical and Electronic Engineering, Yonsei university, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea

Sensors 2017, 17(10), 2169; https://doi.org/10.3390/s17102169 - 21 Sep 2017

Cited by 4 | Viewed by 4593

Abstract

Cellular-based machine-to-machine (M2M) communication is expected to facilitate services for the Internet of Things (IoT). However, because cellular networks are designed for human users, they have some limitations. Random access channel (RACH) congestion caused by massive access from M2M devices is one of [...] Read more.

Cellular-based machine-to-machine (M2M) communication is expected to facilitate services for the Internet of Things (IoT). However, because cellular networks are designed for human users, they have some limitations. Random access channel (RACH) congestion caused by massive access from M2M devices is one of the biggest factors hindering cellular-based M2M services because the RACH congestion causes random access (RA) throughput degradation and connection failures to the devices. In this paper, we show the possibility exploiting the capture effects, which have been known to have a positive impact on the wireless network system, on RA procedure for improving the RA performance of M2M devices. For this purpose, we analyze an RA procedure using a capture model. Through this analysis, we examine the effects of capture on RA performance and propose an Msg3 power-ramping (Msg3 PR) scheme to increase the capture probability (thereby increasing the RA success probability) even when severe RACH congestion problem occurs. The proposed analysis models are validated using simulations. The results show that the proposed scheme, with proper parameters, further improves the RA throughput and reduces the connection failure probability, by slightly increasing the energy consumption. Finally, we demonstrate the effects of coexistence with other RA-related schemes through simulation results. Full article

(This article belongs to the Special Issue Green Wireless Networks in 5G-inspired Applications)

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14 pages, 2469 KiB

Open AccessArticle

An Authentication and Key Management Mechanism for Resource Constrained Devices in IEEE 802.11-based IoT Access Networks

by Ki-Wook Kim¹

, Youn-Hee Han² and Sung-Gi Min^3,*

¹ Department of Computer and Radio Communication Engineering, Korea University, Seoul 136-713, Korea

² School of Computer Science and Engineering, Korea University of Technology and Education, CheonAn 330-708, Korea

³ Department of Computer Science and Engineering, Korea University, Seoul 136-713, Korea

Sensors 2017, 17(10), 2170; https://doi.org/10.3390/s17102170 - 21 Sep 2017

Cited by 21 | Viewed by 9327

Abstract

Many Internet of Things (IoT) services utilize an IoT access network to connect small devices with remote servers. They can share an access network with standard communication technology, such as IEEE 802.11ah. However, an authentication and key management (AKM) mechanism for resource constrained [...] Read more.

Many Internet of Things (IoT) services utilize an IoT access network to connect small devices with remote servers. They can share an access network with standard communication technology, such as IEEE 802.11ah. However, an authentication and key management (AKM) mechanism for resource constrained IoT devices using IEEE 802.11ah has not been proposed as yet. We therefore propose a new AKM mechanism for an IoT access network, which is based on IEEE 802.11 key management with the IEEE 802.1X authentication mechanism. The proposed AKM mechanism does not require any pre-configured security information between the access network domain and the IoT service domain. It considers the resource constraints of IoT devices, allowing IoT devices to delegate the burden of AKM processes to a powerful agent. The agent has sufficient power to support various authentication methods for the access point, and it performs cryptographic functions for the IoT devices. Performance analysis shows that the proposed mechanism greatly reduces computation costs, network costs, and memory usage of the resource-constrained IoT device as compared to the existing IEEE 802.11 Key Management with the IEEE 802.1X authentication mechanism. Full article

(This article belongs to the Special Issue Next Generation Wireless Technologies for Internet of Things)

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28 pages, 5382 KiB

Open AccessArticle

Complete Systematic Error Model of SSR for Sensor Registration in ATC Surveillance Networks

by Ángel J. Jarama^*

, Jaime López-Araquistain

, Gonzalo de Miguel

and Juan A. Besada

Signals, Systems and Radiocommunications Department, Universidad Politécnica de Madrid, Madrid 28040, Spain

Sensors 2017, 17(10), 2171; https://doi.org/10.3390/s17102171 - 21 Sep 2017

Cited by 9 | Viewed by 6086

Abstract

In this paper, a complete and rigorous mathematical model for secondary surveillance radar systematic errors (biases) is developed. The model takes into account the physical effects systematically affecting the measurement processes. The azimuth biases are calculated from the physical error of the antenna [...] Read more.

In this paper, a complete and rigorous mathematical model for secondary surveillance radar systematic errors (biases) is developed. The model takes into account the physical effects systematically affecting the measurement processes. The azimuth biases are calculated from the physical error of the antenna calibration and the errors of the angle determination dispositive. Distance bias is calculated from the delay of the signal produced by the refractivity index of the atmosphere, and from clock errors, while the altitude bias is calculated taking into account the atmosphere conditions (pressure and temperature). It will be shown, using simulated and real data, that adapting a classical bias estimation process to use the complete parametrized model results in improved accuracy in the bias estimation. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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17 pages, 2957 KiB

Open AccessArticle

A Parameter Communication Optimization Strategy for Distributed Machine Learning in Sensors

by Jilin Zhang^{1,2,3,4,5,†}, Hangdi Tu^1,2,†, Yongjian Ren^1,2,*, Jian Wan^1,2,4,5, Li Zhou^1,2, Mingwei Li^1,2, Jue Wang⁶, Lifeng Yu^7,8, Chang Zhao^1,2 and Lei Zhang⁹

¹ School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou 310018, China

² Key Laboratory of Complex Systems Modeling and Simulation, Ministry of Education, Hangzhou 310018, China

³ College of Electrical Engineering, Zhejiang University, Hangzhou 310058, China

⁴ School of Information and Electronic engineering, Zhejiang University of Science & Technology, Hangzhou 310023, China

⁵ Zhejiang Provincial Engineering Center on Media Data Cloud Processing and Analysis, Hangzhou 310018, China

⁶ Supercomputing Center of Computer Network Information Center, Chinese Academy of Sciences, Beijing 100190, China

⁷ Hithink RoyalFlush Information Network Co., Ltd., Hangzhou 310023, Zhejiang, China

⁸ Financial Information Engineering Technology Research Center of Zhejiang Province, Hangzhou 310023, China

⁹ Computer Science Department, Beijing University of Civil Engineering and Architecture, Beijing 100044, China

^† The two authors Jilin Zhang and Hangdi Tu contribute equally to this paper, and they are co-first authors.

Sensors 2017, 17(10), 2172; https://doi.org/10.3390/s17102172 - 21 Sep 2017

Cited by 10 | Viewed by 5843

Abstract

In order to utilize the distributed characteristic of sensors, distributed machine learning has become the mainstream approach, but the different computing capability of sensors and network delays greatly influence the accuracy and the convergence rate of the machine learning model. Our paper describes [...] Read more.

In order to utilize the distributed characteristic of sensors, distributed machine learning has become the mainstream approach, but the different computing capability of sensors and network delays greatly influence the accuracy and the convergence rate of the machine learning model. Our paper describes a reasonable parameter communication optimization strategy to balance the training overhead and the communication overhead. We extend the fault tolerance of iterative-convergent machine learning algorithms and propose the Dynamic Finite Fault Tolerance (DFFT). Based on the DFFT, we implement a parameter communication optimization strategy for distributed machine learning, named Dynamic Synchronous Parallel Strategy (DSP), which uses the performance monitoring model to dynamically adjust the parameter synchronization strategy between worker nodes and the Parameter Server (PS). This strategy makes full use of the computing power of each sensor, ensures the accuracy of the machine learning model, and avoids the situation that the model training is disturbed by any tasks unrelated to the sensors. Full article

(This article belongs to the Special Issue Models, Systems and Applications for Sensors in Cyber Physical Systems)

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23 pages, 4979 KiB

Open AccessArticle

Uncooled Thermal Camera Calibration and Optimization of the Photogrammetry Process for UAV Applications in Agriculture

by Krishna Ribeiro-Gomes¹

, David Hernández-López²

, José F. Ortega¹

, Rocío Ballesteros¹

, Tomás Poblete³

and Miguel A. Moreno^1,*

¹ Regional Centre of Water Research, University of Castilla-La Mancha, 02071 Albacete, Spain

² Institute of Regional Development, University of Castilla-La Mancha, 02071 Albacete, Spain

³ Centro de Investigación y Transferencia en Riegoy Agroclimatología, Universidad de Talca, Talca 3460000, Chile

Sensors 2017, 17(10), 2173; https://doi.org/10.3390/s17102173 - 23 Sep 2017

Cited by 132 | Viewed by 12717

Abstract

The acquisition, processing, and interpretation of thermal images from unmanned aerial vehicles (UAVs) is becoming a useful source of information for agronomic applications because of the higher temporal and spatial resolution of these products compared with those obtained from satellites. However, due to [...] Read more.

The acquisition, processing, and interpretation of thermal images from unmanned aerial vehicles (UAVs) is becoming a useful source of information for agronomic applications because of the higher temporal and spatial resolution of these products compared with those obtained from satellites. However, due to the low load capacity of the UAV they need to mount light, uncooled thermal cameras, where the microbolometer is not stabilized to a constant temperature. This makes the camera precision low for many applications. Additionally, the low contrast of the thermal images makes the photogrammetry process inaccurate, which result in large errors in the generation of orthoimages. In this research, we propose the use of new calibration algorithms, based on neural networks, which consider the sensor temperature and the digital response of the microbolometer as input data. In addition, we evaluate the use of the Wallis filter for improving the quality of the photogrammetry process using structure from motion software. With the proposed calibration algorithm, the measurement accuracy increased from 3.55 °C with the original camera configuration to 1.37 °C. The implementation of the Wallis filter increases the number of tie-point from 58,000 to 110,000 and decreases the total positing error from 7.1 m to 1.3 m. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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13 pages, 5504 KiB

Open AccessArticle

A Compact Multiple Notched Ultra-Wide Band Antenna with an Analysis of the CSRR-TO-CSRR Coupling for Portable UWB Applications

by MuhibUr Rahman¹

, Dong-Sik Ko² and Jung-Dong Park^1,*

¹ Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea

² Poongsan Corporation Ltd., Daejeon 34027, Korea

Sensors 2017, 17(10), 2174; https://doi.org/10.3390/s17102174 - 25 Sep 2017

Cited by 56 | Viewed by 6889

Abstract

We present a compact ultra-wideband (UWB) antenna integrated with sharp notches with a detailed analysis of the mutual coupling of the multiple notch resonators. By utilizing complementary split ring resonators (CSRR) on the radiating semi-circular patch, we achieve the sharp notch-filtering of various [...] Read more.

We present a compact ultra-wideband (UWB) antenna integrated with sharp notches with a detailed analysis of the mutual coupling of the multiple notch resonators. By utilizing complementary split ring resonators (CSRR) on the radiating semi-circular patch, we achieve the sharp notch-filtering of various bands within the UWB band without increasing the antenna size. The notched frequency bands include WiMAX, INSAT, and lower and upper WLAN. In order to estimate the frequency shifts of the notch due to the coupling of the nearby CSRRs, an analysis of the coupling among the multiple notch resonators is carried out and we construct the lumped-circuit equivalent model. The time domain analysis of the proposed antenna is performed to show its validity on the UWB application. The measured frequency response of the input port corresponds quite well with the calculations and simulations. The radiation pattern of the implemented quad-notched UWB antenna is nearly omnidirectional in the passband. Full article

(This article belongs to the Section Remote Sensors)

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16 pages, 18228 KiB

Open AccessArticle

Robust Dehaze Algorithm for Degraded Image of CMOS Image Sensors

by Chen Qu^1,2,*

, Du-Yan Bi¹, Ping Sui³, Ai-Nong Chao¹ and Yun-Fei Wang¹

¹ College of Aeronautics and Astronautics Engineering, Air Force Engineering University, Xi’an 710038, China

² Foundation Department, Air Force Engineering University, Xi’an 710051, China

³ Information and Navigation College, Air Force Engineering University, Xi’an 710077, China

Sensors 2017, 17(10), 2175; https://doi.org/10.3390/s17102175 - 22 Sep 2017

Cited by 19 | Viewed by 5279

Abstract

The CMOS (Complementary Metal-Oxide-Semiconductor) is a new type of solid image sensor device widely used in object tracking, object recognition, intelligent navigation fields, and so on. However, images captured by outdoor CMOS sensor devices are usually affected by suspended atmospheric particles (such as [...] Read more.

The CMOS (Complementary Metal-Oxide-Semiconductor) is a new type of solid image sensor device widely used in object tracking, object recognition, intelligent navigation fields, and so on. However, images captured by outdoor CMOS sensor devices are usually affected by suspended atmospheric particles (such as haze), causing a reduction in image contrast, color distortion problems, and so on. In view of this, we propose a novel dehazing approach based on a local consistent Markov random field (MRF) framework. The neighboring clique in traditional MRF is extended to the non-neighboring clique, which is defined on local consistent blocks based on two clues, where both the atmospheric light and transmission map satisfy the character of local consistency. In this framework, our model can strengthen the restriction of the whole image while incorporating more sophisticated statistical priors, resulting in more expressive power of modeling, thus, solving inadequate detail recovery effectively and alleviating color distortion. Moreover, the local consistent MRF framework can obtain details while maintaining better results for dehazing, which effectively improves the image quality captured by the CMOS image sensor. Experimental results verified that the method proposed has the combined advantages of detail recovery and color preservation. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 5078 KiB

Open AccessArticle

American Sign Language Alphabet Recognition Using a Neuromorphic Sensor and an Artificial Neural Network

by Miguel Rivera-Acosta¹, Susana Ortega-Cisneros^1,*

, Jorge Rivera²

and Federico Sandoval-Ibarra¹

¹ Advanced Studies and Research Center (CINVESTAV), National Polytechnic Institute (IPN), Zapopan 45019, Mexico

² CONACYT-Advanced Studies and Research Center (CINVESTAV), National Polytechnic Institute (IPN), Zapopan 45019, Mexico

Sensors 2017, 17(10), 2176; https://doi.org/10.3390/s17102176 - 22 Sep 2017

Cited by 28 | Viewed by 10873

Abstract

This paper reports the design and analysis of an American Sign Language (ASL) alphabet translation system implemented in hardware using a Field-Programmable Gate Array. The system process consists of three stages, the first being the communication with the neuromorphic camera (also called Dynamic [...] Read more.

This paper reports the design and analysis of an American Sign Language (ASL) alphabet translation system implemented in hardware using a Field-Programmable Gate Array. The system process consists of three stages, the first being the communication with the neuromorphic camera (also called Dynamic Vision Sensor, DVS) sensor using the Universal Serial Bus protocol. The feature extraction of the events generated by the DVS is the second part of the process, consisting of a presentation of the digital image processing algorithms developed in software, which aim to reduce redundant information and prepare the data for the third stage. The last stage of the system process is the classification of the ASL alphabet, achieved with a single artificial neural network implemented in digital hardware for higher speed. The overall result is the development of a classification system using the ASL signs contour, fully implemented in a reconfigurable device. The experimental results consist of a comparative analysis of the recognition rate among the alphabet signs using the neuromorphic camera in order to prove the proper operation of the digital image processing algorithms. In the experiments performed with 720 samples of 24 signs, a recognition accuracy of 79.58% was obtained. Full article

(This article belongs to the Special Issue Video Analysis and Tracking Using State-of-the-Art Sensors)

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47 pages, 7377 KiB

Open AccessArticle

A Methodology for the Design of Application-Specific Cyber-Physical Social Sensing Co-Simulators

by Borja Bordel Sánchez^1,*

, Ramón Alcarria²

, Álvaro Sánchez-Picot¹ and Diego Sánchez-de-Rivera¹

¹ Department of Telematics Systems Engineering, Universidad Politécnica de Madrid, Avenida Complutense n° 30, 28040 Madrid (España), Spain

² Department of Topographic Engineering and Cartography, Universidad Politécnica de Madrid, Campus Sur, 28031 Madrid (España), Spain

Sensors 2017, 17(10), 2177; https://doi.org/10.3390/s17102177 - 22 Sep 2017

Cited by 16 | Viewed by 5323

Abstract

Cyber-Physical Social Sensing (CPSS) is a new trend in the context of pervasive sensing. In these new systems, various domains coexist in time, evolve together and influence each other. Thus, application-specific tools are necessary for specifying and validating designs and simulating systems. However, [...] Read more.

Cyber-Physical Social Sensing (CPSS) is a new trend in the context of pervasive sensing. In these new systems, various domains coexist in time, evolve together and influence each other. Thus, application-specific tools are necessary for specifying and validating designs and simulating systems. However, nowadays, different tools are employed to simulate each domain independently. Mainly, the cause of the lack of co-simulation instruments to simulate all domains together is the extreme difficulty of combining and synchronizing various tools. In order to reduce that difficulty, an adequate architecture for the final co-simulator must be selected. Therefore, in this paper the authors investigate and propose a methodology for the design of CPSS co-simulation tools. The paper describes the four steps that software architects should follow in order to design the most adequate co-simulator for a certain application, considering the final users’ needs and requirements and various additional factors such as the development team’s experience. Moreover, the first practical use case of the proposed methodology is provided. An experimental validation is also included in order to evaluate the performing of the proposed co-simulator and to determine the correctness of the proposal. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 5626 KiB

Open AccessArticle

Bioelectrochemical Detection of Mycobacterium tuberculosis ESAT-6 in an Antibody-Based Biomicrosystem

by Danna Sepulveda¹

, Miguel A. Aroca¹

, Andres Varela², Patricia Del Portillo² and Johann F. Osma^1,*

¹ CMUA, Department of Electrical and Electronics Engineering, Universidad de los Andes, 111711 Bogota, Colombia

² CorpoGen, Carrera 5 No. 66A-34, 110231 Bogota, Colombia

Sensors 2017, 17(10), 2178; https://doi.org/10.3390/s17102178 - 22 Sep 2017

Cited by 15 | Viewed by 6614

Abstract

Bioelectrochemical sensing of Mycobacterium tuberculosis through electro-immunosensors is a promising technique to detect relevant analytes. In general, immunosensors require the formation of organic assemblies by the adsorption of molecular constituents. Moreover, they depend on the correct immobilization of the bio-recognition element in the [...] Read more.

Bioelectrochemical sensing of Mycobacterium tuberculosis through electro-immunosensors is a promising technique to detect relevant analytes. In general, immunosensors require the formation of organic assemblies by the adsorption of molecular constituents. Moreover, they depend on the correct immobilization of the bio-recognition element in the biosensor. These procedures cannot be easily monitored without the use of invasive methods. In this work, an impedance analysis technique was used, as a non-invasive method, to measure and differentiate the manufacturing stages of the sensors. Biomicrosystems were fabricated through physical vapor deposition (PVD) of 80 nm Au nanolayers on 35 µm copper surfaces. Later, the surface was modified through thiolation methods generating a self-assembled-monolayer (SAM) with 20 mM 4-aminothiophenol (4-ATP) on which a polyclonal antibody (pAb) was covalently attached. Using impedance analysis, every step of the electro-immunosensor fabrication protocol was characterized using 40 independent replicas. Results showed that, compared to the negative controls, distilled water, and 0.5 µg/mL HSA, a maximum variation of 171% between each replica was achieved when compared to samples containing 0.5 µg/mL of ESAT-6 M. tuberculosis immunodominant protein. Therefore, this development validates a non-invasive method to electrically monitor the assembly process of electro-immunosensors and a tool for its further measure for detection of relevant antigens. Full article

(This article belongs to the Special Issue Sensors for Toxic and Pathogen Detection)

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22 pages, 637 KiB

Open AccessArticle

A Low Power Consumption Algorithm for Efficient Energy Consumption in ZigBee Motes

by Daniel Vaquerizo-Hdez^*, Pablo Muñoz, María D. R-Moreno and David F. Barrero

Intelligent Systems Group, Computer Engineering Department, Universidad de Alcalá, 28805 Alcalá de Henares, Spain

Sensors 2017, 17(10), 2179; https://doi.org/10.3390/s17102179 - 22 Sep 2017

Cited by 19 | Viewed by 7687

Abstract

Wireless Sensor Networks (WSNs) are becoming increasingly popular since they can gather information from different locations without wires. This advantage is exploited in applications such as robotic systems, telecare, domotic or smart cities, among others. To gain independence from the electricity grid, WSNs [...] Read more.

Wireless Sensor Networks (WSNs) are becoming increasingly popular since they can gather information from different locations without wires. This advantage is exploited in applications such as robotic systems, telecare, domotic or smart cities, among others. To gain independence from the electricity grid, WSNs devices are equipped with batteries, therefore their operational time is determined by the time that the batteries can power on the device. As a consequence, engineers must consider low energy consumption as a critical objective to design WSNs. Several approaches can be taken to make efficient use of energy in WSNs, for instance low-duty-cycling sensor networks (LDC-WSN). Based on the LDC-WSNs, we present LOKA, a LOw power Konsumption Algorithm to minimize WSNs energy consumption using different power modes in a sensor mote. The contribution of the work is a novel algorithm called LOKA that implements two duty-cycling mechanisms using the end-device of the ZigBee protocol (of the Application Support Sublayer) and an external microcontroller (Cortex M0+) in order to minimize the energy consumption of a delay tolerant networking. Experiments show that using LOKA, the energy required by the sensor device is reduced to half with respect to the same sensor device without using LOKA. Full article

(This article belongs to the Special Issue Energy Harvesting Sensors for Long Term Applications in the IoT Era)

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21 pages, 5668 KiB

Open AccessArticle

Logistic Model to Support Service Modularity for the Promotion of Reusability in a Web Objects-Enabled IoT Environment

by Muhammad Golam Kibria

, Sajjad Ali

, Muhammad Aslam Jarwar

, Sunil Kumar

and Ilyoung Chong^*

Department of CICE, Hankuk University of Foreign Studies, 02450 Seoul, Korea

Sensors 2017, 17(10), 2180; https://doi.org/10.3390/s17102180 - 22 Sep 2017

Cited by 14 | Viewed by 5146

Abstract

Due to a very large number of connected virtual objects in the surrounding environment, intelligent service features in the Internet of Things requires the reuse of existing virtual objects and composite virtual objects. If a new virtual object is created for each new [...] Read more.

Due to a very large number of connected virtual objects in the surrounding environment, intelligent service features in the Internet of Things requires the reuse of existing virtual objects and composite virtual objects. If a new virtual object is created for each new service request, then the number of virtual object would increase exponentially. The Web of Objects applies the principle of service modularity in terms of virtual objects and composite virtual objects. Service modularity is a key concept in the Web Objects-Enabled Internet of Things (IoT) environment which allows for the reuse of existing virtual objects and composite virtual objects in heterogeneous ontologies. In the case of similar service requests occurring at the same, or different locations, the already-instantiated virtual objects and their composites that exist in the same, or different ontologies can be reused. In this case, similar types of virtual objects and composite virtual objects are searched and matched. Their reuse avoids duplication under similar circumstances, and reduces the time it takes to search and instantiate them from their repositories, where similar functionalities are provided by similar types of virtual objects and their composites. Controlling and maintaining a virtual object means controlling and maintaining a real-world object in the real world. Even though the functional costs of virtual objects are just a fraction of those for deploying and maintaining real-world objects, this article focuses on reusing virtual objects and composite virtual objects, as well as discusses similarity matching of virtual objects and composite virtual objects. This article proposes a logistic model that supports service modularity for the promotion of reusability in the Web Objects-enabled IoT environment. Necessary functional components and a flowchart of an algorithm for reusing composite virtual objects are discussed. Also, to realize the service modularity, a use case scenario is studied and implemented. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 1001 KiB

Open AccessArticle

A New Proxy Measurement Algorithm with Application to the Estimation of Vertical Ground Reaction Forces Using Wearable Sensors

by Yuzhu Guo^1,2,3

, Fabio Storm^2,4

, Yifan Zhao⁵, Stephen A. Billings^1,2, Aleksandar Pavic^2,6

, Claudia Mazzà^2,4,*

and Ling-Zhong Guo^1,2,*

¹ Department of Automatic Control and Systems Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UK

² INSIGNEO Institute for in Silico Medicine, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UK

³ School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China

⁴ Department of Mechanical Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, UK

⁵ The EPSRC Centre for Innovative Manufacturing in Through-life Engineering Services, Cranfield University, Cranfield MK43 0AL, UK

⁶ Vibration Engineering Section, College of Engineering, Mathematics and Physical Sciences, University of Exeter, North Park Road, Exeter EX4 4QF, UK

Sensors 2017, 17(10), 2181; https://doi.org/10.3390/s17102181 - 22 Sep 2017

Cited by 45 | Viewed by 8341

Abstract

Measurement of the ground reaction forces (GRF) during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component [...] Read more.

Measurement of the ground reaction forces (GRF) during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF) from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR) is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0%) using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra). Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in UK)

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16 pages, 4230 KiB

Open AccessArticle

Tip Pressure on Semicircular Specimens in Tapping Mode Atomic Force Microscopy in Viscous Fluid Environments

by Hua-Ju Shih¹, Ching-Liang Dai² and Po-Jen Shih^3,*

¹ Institute of Applied Mechanics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan

² Department of Mechanical Engineering, National Chung Hsing University, No. 145, Xingda Rd. South Dist., Taichung 40227, Taiwan

³ Department of Civil and Environmental Engineering, National University of Kaohsiung, No. 700, Kaohsiung University Rd., Nanzih District, Kaohsiung 81148, Taiwan

Sensors 2017, 17(10), 2182; https://doi.org/10.3390/s17102182 - 22 Sep 2017

Cited by 1 | Viewed by 3830

Abstract

Tapping mode (TM) atomic force microscopy (AFM) in a liquid environment is widely used to measure the contours of biological specimens. The TM triggers the AFM probe approximately at the resonant frequencies and controls the tip such that it periodically touches the specimen [...] Read more.

Tapping mode (TM) atomic force microscopy (AFM) in a liquid environment is widely used to measure the contours of biological specimens. The TM triggers the AFM probe approximately at the resonant frequencies and controls the tip such that it periodically touches the specimen along the scanning path. The AFM probe and its tip produce a hydrodynamic pressure on the probe itself and press the specimen. The tip to specimen size ratio is known to affect the measurement accuracy of AFM, however, few studies have focused on the hydrodynamic pressure caused by the effects of specimen size. Such pressure affects the contour distortion of the biological specimen. In this study, a semi-analytical method is employed for a semicircular specimen to analyze the vorticity and pressure distributions for specimens of various sizes and at various tip locations. Changes in pressure distribution, fluid spin motion, and specimen deformation are identified as the tip approaches the specimen. The results indicate the following: the specimen surface experiences the highest pressure when the specimen diameter equals the tip width; the vorticity between tip and specimen is complex when the tip is close to the specimen center line; and the specimen inflates when the tip is aligned with the specimen center line. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 3166 KiB

Open AccessArticle

SFOL Pulse: A High Accuracy DME Pulse for Alternative Aircraft Position and Navigation

by Euiho Kim^1,* and Jiwon Seo^2,3,*

¹ Department of Mechanical & System Design Engineering, Hongik University, 94, Wausan-ro, Mapo-gu, Seoul 04066, Korea

² School of Integrated Technology, Yonsei University, 85 Songdogwahak-ro, Incheon 21983, Korea

³ Yonsei Institute of Convergence Technology, Yonsei University, 85 Songdogwahak-ro, Incheon 21983, Korea

Sensors 2017, 17(10), 2183; https://doi.org/10.3390/s17102183 - 22 Sep 2017

Cited by 35 | Viewed by 7049

Abstract

In the Federal Aviation Administration’s (FAA) performance based navigation strategy announced in 2016, the FAA stated that it would retain and expand the Distance Measuring Equipment (DME) infrastructure to ensure resilient aircraft navigation capability during the event of a Global Navigation Satellite System [...] Read more.

In the Federal Aviation Administration’s (FAA) performance based navigation strategy announced in 2016, the FAA stated that it would retain and expand the Distance Measuring Equipment (DME) infrastructure to ensure resilient aircraft navigation capability during the event of a Global Navigation Satellite System (GNSS) outage. However, the main drawback of the DME as a GNSS back up system is that it requires a significant expansion of the current DME ground infrastructure due to its poor distance measuring accuracy over 100 m. The paper introduces a method to improve DME distance measuring accuracy by using a new DME pulse shape. The proposed pulse shape was developed by using Genetic Algorithms and is less susceptible to multipath effects so that the ranging error reduces by 36.0–77.3% when compared to the Gaussian and Smoothed Concave Polygon DME pulses, depending on noise environment. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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19 pages, 1628 KiB

Open AccessArticle

Tracking of Maneuvering Complex Extended Object with Coupled Motion Kinematics and Extension Dynamics Using Range Extent Measurements

by Lifan Sun^1,2, Baofeng Ji^1,3, Jian Lan^4,*, Zishu He² and Jiexin Pu¹

¹ School of Information Engineering, Henan University of Science and Technology, Luoyang 471023, China

² School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

³ Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China

⁴ Center for Information Engineering Science Research (CIESR), School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(10), 2184; https://doi.org/10.3390/s17102184 - 22 Sep 2017

Cited by 2 | Viewed by 4458

Abstract

The key to successful maneuvering complex extended object tracking (MCEOT) using range extent measurements provided by high resolution sensors lies in accurate and effective modeling of both the extension dynamics and the centroid kinematics. During object maneuvers, the extension dynamics of an object [...] Read more.

The key to successful maneuvering complex extended object tracking (MCEOT) using range extent measurements provided by high resolution sensors lies in accurate and effective modeling of both the extension dynamics and the centroid kinematics. During object maneuvers, the extension dynamics of an object with a complex shape is highly coupled with the centroid kinematics. However, this difficult but important problem is rarely considered and solved explicitly. In view of this, this paper proposes a general approach to modeling a maneuvering complex extended object based on Minkowski sum, so that the coupled turn maneuvers in both the centroid states and extensions can be described accurately. The new model has a concise and unified form, in which the complex extension dynamics can be simply and jointly characterized by multiple simple sub-objects’ extension dynamics based on Minkowski sum. The proposed maneuvering model fits range extent measurements very well due to its favorable properties. Based on this model, an MCEOT algorithm dealing with motion and extension maneuvers is also derived. Two different cases of the turn maneuvers with known/unknown turn rates are specifically considered. The proposed algorithm which jointly estimates the kinematic state and the object extension can also be easily implemented. Simulation results demonstrate the effectiveness of the proposed modeling and tracking approaches. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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24 pages, 1041 KiB

Open AccessArticle

Design and Analysis of a Low Latency Deterministic Network MAC for Wireless Sensor Networks

by Prasan Kumar Sahoo^1,2

, Sudhir Ranjan Pattanaik³ and Shih-Lin Wu^1,2,4,*

¹ Department of Computer Science and Information Engineering, Chang Gung University, Taoyuan 33302, Taiwan

² Department of Cardiology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan

³ Department of Electrical Engineering, Chang Gung University, Taoyuan 33302, Taiwan

⁴ Department of Electrical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan

Sensors 2017, 17(10), 2185; https://doi.org/10.3390/s17102185 - 22 Sep 2017

Cited by 15 | Viewed by 4943

Abstract

The IEEE 802.15.4e standard has four different superframe structures for different applications. Use of a low latency deterministic network (LLDN) superframe for the wireless sensor network is one of them, which can operate in a star topology. In this paper, a new channel [...] Read more.

The IEEE 802.15.4e standard has four different superframe structures for different applications. Use of a low latency deterministic network (LLDN) superframe for the wireless sensor network is one of them, which can operate in a star topology. In this paper, a new channel access mechanism for IEEE 802.15.4e-based LLDN shared slots is proposed, and analytical models are designed based on this channel access mechanism. A prediction model is designed to estimate the possible number of retransmission slots based on the number of failed transmissions. Performance analysis in terms of data transmission reliability, delay, throughput and energy consumption are provided based on our proposed designs. Our designs are validated for simulation and analytical results, and it is observed that the simulation results well match with the analytical ones. Besides, our designs are compared with the IEEE 802.15.4 MAC mechanism, and it is shown that ours outperforms in terms of throughput, energy consumption, delay and reliability. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 2970 KiB

Open AccessArticle

Measurement of Non-Stationary Characteristics of a Landfall Typhoon at the Jiangyin Bridge Site

by Xuhui He¹

, Hongxi Qin¹, Tianyou Tao^2,*, Wenshuo Liu^1,* and Hao Wang²

¹ School of Civil Engineering, Central South University, Changsha 410006, China

² School of Civil Engineering, Southeast University, Nanjing 211189, China

Sensors 2017, 17(10), 2186; https://doi.org/10.3390/s17102186 - 22 Sep 2017

Cited by 18 | Viewed by 5175

Abstract

The wind-sensitive long-span suspension bridge is a vital element in land transportation. Understanding the wind characteristics at the bridge site is thus of great significance to the wind- resistant analysis of such a flexible structure. In this study, a strong wind event from [...] Read more.

The wind-sensitive long-span suspension bridge is a vital element in land transportation. Understanding the wind characteristics at the bridge site is thus of great significance to the wind- resistant analysis of such a flexible structure. In this study, a strong wind event from a landfall typhoon called Soudelor recorded at the Jiangyin Bridge site with the anemometer is taken as the research object. As inherent time-varying trends are frequently captured in typhoon events, the wind characteristics of Soudelor are analyzed in a non-stationary perspective. The time-varying mean is first extracted with the wavelet-based self-adaptive method. Then, the non-stationary turbulent wind characteristics, e.g.; turbulence intensity, gust factor, turbulence integral scale, and power spectral density, are investigated and compared with the results from the stationary analysis. The comparison highlights the importance of non-stationary considerations of typhoon events, and a transition from stationarity to non-stationarity for the analysis of wind effects. The analytical results could help enrich the database of non-stationary wind characteristics, and are expected to provide references for the wind-resistant analysis of engineering structures in similar areas. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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12 pages, 3475 KiB

Open AccessArticle

SAW-Based Phononic Crystal Microfluidic Sensor—Microscale Realization of Velocimetry Approaches for Integrated Analytical Platform Applications

by Aleksandr Oseev^1,*

, Ralf Lucklum¹, Mikhail Zubtsov¹, Marc-Peter Schmidt¹, Nikolay V. Mukhin^1,2 and Soeren Hirsch³

¹ Institute of Micro and Sensor Systems (IMOS), Otto-von-Guericke-University, 39106 Magdeburg, Germany

² Department of Electronics, Saint Petersburg Electrotechnical University “LETI”, Saint Petersburg 197376, Russia

³ Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg, Germany

Sensors 2017, 17(10), 2187; https://doi.org/10.3390/s17102187 - 23 Sep 2017

Cited by 22 | Viewed by 5464

Abstract

The current work demonstrates a novel surface acoustic wave (SAW) based phononic crystal sensor approach that allows the integration of a velocimetry-based sensor concept into single chip integrated solutions, such as Lab-on-a-Chip devices. The introduced sensor platform merges advantages of ultrasonic velocimetry analytic [...] Read more.

The current work demonstrates a novel surface acoustic wave (SAW) based phononic crystal sensor approach that allows the integration of a velocimetry-based sensor concept into single chip integrated solutions, such as Lab-on-a-Chip devices. The introduced sensor platform merges advantages of ultrasonic velocimetry analytic systems and a microacoustic sensor approach. It is based on the analysis of structural resonances in a periodic composite arrangement of microfluidic channels confined within a liquid analyte. Completed theoretical and experimental investigations show the ability to utilize periodic structure localized modes for the detection of volumetric properties of liquids and prove the efficacy of the proposed sensor concept. Full article

(This article belongs to the Special Issue Surface Acoustic Wave and Bulk Acoustic Wave Sensors)

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11 pages, 941 KiB

Open AccessArticle

Raman Hyperspectral Imaging for Detection of Watermelon Seeds Infected with Acidovorax citrulli

by Hoonsoo Lee^1,2, Moon S. Kim¹, Jianwei Qin¹, Eunsoo Park², Yu-Rim Song³, Chang-Sik Oh³ and Byoung-Kwan Cho^2,*

¹ Environmental Microbial and Food Safety Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Powder Mill Rd. Bldg. 303, BARC-East, Beltsville, MD 20705, USA

² Department of Biosystems Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Korea

³ Department of Horticultural Biotechnology and Institute of Life Science and Resources, Kyung Hee University, Yongin 441-701, Korea

Sensors 2017, 17(10), 2188; https://doi.org/10.3390/s17102188 - 23 Sep 2017

Cited by 35 | Viewed by 8627

Abstract

The bacterial infection of seeds is one of the most important quality factors affecting yield. Conventional detection methods for bacteria-infected seeds, such as biological, serological, and molecular tests, are not feasible since they require expensive equipment, and furthermore, the testing processes are also [...] Read more.

The bacterial infection of seeds is one of the most important quality factors affecting yield. Conventional detection methods for bacteria-infected seeds, such as biological, serological, and molecular tests, are not feasible since they require expensive equipment, and furthermore, the testing processes are also time-consuming. In this study, we use the Raman hyperspectral imaging technique to distinguish bacteria-infected seeds from healthy seeds as a rapid, accurate, and non-destructive detection tool. We utilize Raman hyperspectral imaging data in the spectral range of 400–1800 cm⁻¹ to determine the optimal band-ratio for the discrimination of watermelon seeds infected by the bacteria Acidovorax citrulli using ANOVA. Two bands at 1076.8 cm⁻¹ and 437 cm⁻¹ are selected as the optimal Raman peaks for the detection of bacteria-infected seeds. The results demonstrate that the Raman hyperspectral imaging technique has a good potential for the detection of bacteria-infected watermelon seeds and that it could form a suitable alternative to conventional methods. Full article

(This article belongs to the Section Biosensors)

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19 pages, 8257 KiB

Open AccessArticle

Monaural Sound Localization Based on Reflective Structure and Homomorphic Deconvolution

by Yeonseok Park¹, Anthony Choi² and Keonwook Kim^1,*

¹ Division of Electronics & Electrical Engineering, Dongguk University-Seoul, Seoul 04620, Korea

² Department of Electrical & Computer Engineering, Mercer University, 1501 Mercer University Drive, Macon, GA 31207, USA

Sensors 2017, 17(10), 2189; https://doi.org/10.3390/s17102189 - 23 Sep 2017

Cited by 7 | Viewed by 4838

Abstract

The asymmetric structure around the receiver provides a particular time delay for the specific incoming propagation. This paper designs a monaural sound localization system based on the reflective structure around the microphone. The reflective plates are placed to present the direction-wise time delay, [...] Read more.

The asymmetric structure around the receiver provides a particular time delay for the specific incoming propagation. This paper designs a monaural sound localization system based on the reflective structure around the microphone. The reflective plates are placed to present the direction-wise time delay, which is naturally processed by convolutional operation with a sound source. The received signal is separated for estimating the dominant time delay by using homomorphic deconvolution, which utilizes the real cepstrum and inverse cepstrum sequentially to derive the propagation response’s autocorrelation. Once the localization system accurately estimates the information, the time delay model computes the corresponding reflection for localization. Because of the structure limitation, two stages of the localization process perform the estimation procedure as range and angle. The software toolchain from propagation physics and algorithm simulation realizes the optimal 3D-printed structure. The acoustic experiments in the anechoic chamber denote that 79.0% of the study range data from the isotropic signal is properly detected by the response value, and 87.5% of the specific direction data from the study range signal is properly estimated by the response time. The product of both rates shows the overall hit rate to be 69.1%. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2650 KiB

Open AccessCommunication

Autonomous Microsystems for Downhole Applications: Design Challenges, Current State, and Initial Test Results

by Myungjoon Choi, Yu Sui, In Hee Lee, Ryan Meredith, Yushu Ma, Gyouho Kim, David Blaauw, Yogesh B. Gianchandani and Tao Li^*

Center for Wireless Integrated MicroSensing and Systems (WIMS²), University of Michigan, Ann Arbor, MI 48109, USA

Sensors 2017, 17(10), 2190; https://doi.org/10.3390/s17102190 - 23 Sep 2017

Cited by 16 | Viewed by 7372

Abstract

This paper describes two platforms for autonomous sensing microsystems that are intended for deployment in chemically corrosive environments at elevated temperatures and pressures. Following the deployment period, the microsystems are retrieved, recharged, and interrogated wirelessly at close proximity. The first platform is the [...] Read more.

This paper describes two platforms for autonomous sensing microsystems that are intended for deployment in chemically corrosive environments at elevated temperatures and pressures. Following the deployment period, the microsystems are retrieved, recharged, and interrogated wirelessly at close proximity. The first platform is the Michigan Micro Mote for High Temperature (M³HT), a chip stack 2.9 × 1.1 × 1.5 mm³ in size. It uses RF communications to support pre-deployment and post-retrieval functions, and it uses customized electronics to achieve ultralow power consumption, permitting the use of a chip-scale battery. The second platform is the Environmental Logging Microsystem (ELM). This system, which is 6.5 × 6.3 × 4.5 mm³ in size, uses the smallest suitable off-the-shelf electronic and battery components that are compatible with assembly on a flexible printed circuit board. Data are stored in non-volatile memory, permitting retrieval even after total power loss. Pre-deployment and post-retrieval functions are supported by optical communication. Two types of encapsulation methods are used to withstand high pressure and corrosive environments: an epoxy filled volume is used for the M³HT, and a hollow stainless-steel shell with a sapphire lid is used for both the M³HT and ELM. The encapsulated systems were successfully tested at temperature and pressure reaching 150 °C and 10,000 psi, in environments of concentrated brine, oil, and cement slurry. At elevated temperatures, the limited lifetimes of available batteries constrain the active deployment period to several hours. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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17 pages, 1086 KiB

Open AccessArticle

Secure and Lightweight Cloud-Assisted Video Reporting Protocol over 5G-Enabled Vehicular Networks

by Lewis Nkenyereye

, Joonho Kwon

and Yoon-Ho Choi^*

School of Computer Science and Engineering, Pusan National University, Busan 46241, Korea

Sensors 2017, 17(10), 2191; https://doi.org/10.3390/s17102191 - 23 Sep 2017

Cited by 9 | Viewed by 4678

Abstract

In the vehicular networks, the real-time video reporting service is used to send the recorded videos in the vehicle to the cloud. However, when facilitating the real-time video reporting service in the vehicular networks, the usage of the fourth generation (4G) long term [...] Read more.

In the vehicular networks, the real-time video reporting service is used to send the recorded videos in the vehicle to the cloud. However, when facilitating the real-time video reporting service in the vehicular networks, the usage of the fourth generation (4G) long term evolution (LTE) was proved to suffer from latency while the IEEE 802.11p standard does not offer sufficient scalability for a such congested environment. To overcome those drawbacks, the fifth-generation (5G)-enabled vehicular network is considered as a promising technology for empowering the real-time video reporting service. In this paper, we note that security and privacy related issues should also be carefully addressed to boost the early adoption of 5G-enabled vehicular networks. There exist a few research works for secure video reporting service in 5G-enabled vehicular networks. However, their usage is limited because of public key certificates and expensive pairing operations. Thus, we propose a secure and lightweight protocol for cloud-assisted video reporting service in 5G-enabled vehicular networks. Compared to the conventional public key certificates, the proposed protocol achieves entities’ authorization through anonymous credential. Also, by using lightweight security primitives instead of expensive bilinear pairing operations, the proposed protocol minimizes the computational overhead. From the evaluation results, we show that the proposed protocol takes the smaller computation and communication time for the cryptographic primitives than that of the well-known Eiza-Ni-Shi protocol. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 1943 KiB

Open AccessArticle

Drawing Sensors with Ball-Milled Blends of Metal-Organic Frameworks and Graphite

by Michael Ko, Aylin Aykanat, Merry K. Smith and Katherine A. Mirica^*

Department of Chemistry—Burke Laboratory, Dartmouth College, Hanover, NH 03755, USA

Sensors 2017, 17(10), 2192; https://doi.org/10.3390/s17102192 - 23 Sep 2017

Cited by 98 | Viewed by 14709

Abstract

The synthetically tunable properties and intrinsic porosity of conductive metal-organic frameworks (MOFs) make them promising materials for transducing selective interactions with gaseous analytes in an electrically addressable platform. Consequently, conductive MOFs are valuable functional materials with high potential utility in chemical detection. The [...] Read more.

The synthetically tunable properties and intrinsic porosity of conductive metal-organic frameworks (MOFs) make them promising materials for transducing selective interactions with gaseous analytes in an electrically addressable platform. Consequently, conductive MOFs are valuable functional materials with high potential utility in chemical detection. The implementation of these materials, however, is limited by the available methods for device incorporation due to their poor solubility and moderate electrical conductivity. This manuscript describes a straightforward method for the integration of moderately conductive MOFs into chemiresistive sensors by mechanical abrasion. To improve electrical contacts, blends of MOFs with graphite were generated using a solvent-free ball-milling procedure. While most bulk powders of pure conductive MOFs were difficult to integrate into devices directly via mechanical abrasion, the compressed solid-state MOF/graphite blends were easily abraded onto the surface of paper substrates equipped with gold electrodes to generate functional sensors. This method was used to prepare an array of chemiresistors, from four conductive MOFs, capable of detecting and differentiating NH₃, H₂S and NO at parts-per-million concentrations. Full article

(This article belongs to the Special Issue Chemiresistive Sensors: Status and the Future)

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14 pages, 14417 KiB

Open AccessArticle

On-Board Detection of Pedestrian Intentions

by Zhijie Fang^1,2,*, David Vázquez² and Antonio M. López^1,2

¹ Computer Science Department, Universitat Autònoma Barcelona (UAB), 08193 Barcelona, Spain

² Computer Vision Center (CVC), Universitat Autònoma Barcelona (UAB), 08193 Barcelona, Spain

Sensors 2017, 17(10), 2193; https://doi.org/10.3390/s17102193 - 23 Sep 2017

Cited by 64 | Viewed by 9630

Abstract

Avoiding vehicle-to-pedestrian crashes is a critical requirement for nowadays advanced driver assistant systems (ADAS) and future self-driving vehicles. Accordingly, detecting pedestrians from raw sensor data has a history of more than 15 years of research, with vision playing a central role. During the [...] Read more.

Avoiding vehicle-to-pedestrian crashes is a critical requirement for nowadays advanced driver assistant systems (ADAS) and future self-driving vehicles. Accordingly, detecting pedestrians from raw sensor data has a history of more than 15 years of research, with vision playing a central role. During the last years, deep learning has boosted the accuracy of image-based pedestrian detectors. However, detection is just the first step towards answering the core question, namely is the vehicle going to crash with a pedestrian provided preventive actions are not taken? Therefore, knowing as soon as possible if a detected pedestrian has the intention of crossing the road ahead of the vehicle is essential for performing safe and comfortable maneuvers that prevent a crash. However, compared to pedestrian detection, there is relatively little literature on detecting pedestrian intentions. This paper aims to contribute along this line by presenting a new vision-based approach which analyzes the pose of a pedestrian along several frames to determine if he or she is going to enter the road or not. We present experiments showing 750 ms of anticipation for pedestrians crossing the road, which at a typical urban driving speed of 50 km/h can provide 15 additional meters (compared to a pure pedestrian detector) for vehicle automatic reactions or to warn the driver. Moreover, in contrast with state-of-the-art methods, our approach is monocular, neither requiring stereo nor optical flow information. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2539 KiB

Open AccessCommunication

A Multi-Fluorescent DNA/Graphene Oxide Conjugate Sensor for Signature-Based Protein Discrimination

by Shunsuke Tomita^1,*

, Sayaka Ishihara¹ and Ryoji Kurita^1,2,*

¹ Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, and DAILAB, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan

² Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan

Sensors 2017, 17(10), 2194; https://doi.org/10.3390/s17102194 - 23 Sep 2017

Cited by 23 | Viewed by 8274

Abstract

Signature-based protein sensing has recently emerged as a promising prospective alternative to conventional lock-and-key methods. However, most of the current examples require the measurement of optical signals from spatially-separated materials for the generation of signatures. Herein, we present a new approach for the [...] Read more.

Signature-based protein sensing has recently emerged as a promising prospective alternative to conventional lock-and-key methods. However, most of the current examples require the measurement of optical signals from spatially-separated materials for the generation of signatures. Herein, we present a new approach for the construction of multi-fluorescent sensing systems with high accessibility and tunability, which allows generating protein fluorescent signatures from a single microplate well. This approach is based on conjugates between nano-graphene oxide (nGO) and three single-stranded DNAs (ssDNAs) that exhibit different sequences and fluorophores. Initially, the three fluorophore-modified ssDNAs were quenched simultaneously by binding to nGO. Subsequent addition of analyte proteins caused a partial recovery in fluorescent intensity of the individual ssDNAs. Based on this scheme, we have succeeded in acquiring fluorescence signatures unique to (i) ten proteins that differ with respect to pI and molecular weight and (ii) biochemical marker proteins in the presence of interferent human serum. Pattern-recognition methods demonstrated high levels of discrimination for this system. The high discriminatory power and simple format of this sensor system should enable an easy and fast evaluation of proteins and protein mixtures. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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25 pages, 7976 KiB

Open AccessArticle

Towards Robot-Assisted Retinal Vein Cannulation: A Motorized Force-Sensing Microneedle Integrated with a Handheld Micromanipulator ^†

by Berk Gonenc^1,*, Jeremy Chae², Peter Gehlbach², Russell H. Taylor¹ and Iulian Iordachita¹

¹ Computer Integrated Surgical Systems and Technology Engineering Research Center (CISST ERC), Johns Hopkins University, Baltimore, MD 21218, USA

² Wilmer Eye Institute, The Johns Hopkins School of Medicine, Baltimore, MD 21287, USA

Sensors 2017, 17(10), 2195; https://doi.org/10.3390/s17102195 - 23 Sep 2017

Cited by 38 | Viewed by 8865

Abstract

Retinal vein cannulation is a technically demanding surgical procedure where therapeutic agents are injected into the retinal veins to treat occlusions. The clinical feasibility of this approach has been largely limited by the technical challenges associated with performing the procedure. Among the challenges [...] Read more.

Retinal vein cannulation is a technically demanding surgical procedure where therapeutic agents are injected into the retinal veins to treat occlusions. The clinical feasibility of this approach has been largely limited by the technical challenges associated with performing the procedure. Among the challenges to successful vein cannulation are identifying the moment of venous puncture, achieving cannulation of the micro-vessel, and maintaining cannulation throughout drug delivery. Recent advances in medical robotics and sensing of tool-tissue interaction forces have the potential to address each of these challenges as well as to prevent tissue trauma, minimize complications, diminish surgeon effort, and ultimately promote successful retinal vein cannulation. In this paper, we develop an assistive system combining a handheld micromanipulator, called “Micron”, with a force-sensing microneedle. Using this system, we examine two distinct methods of precisely detecting the instant of venous puncture. This is based on measured tool-tissue interaction forces and also the tracked position of the needle tip. In addition to the existing tremor canceling function of Micron, a new control method is implemented to actively compensate unintended movements of the operator, and to keep the cannulation device securely inside the vein following cannulation. To demonstrate the capabilities and performance of our uniquely upgraded system, we present a multi-user artificial phantom study with subjects from three different surgical skill levels. Results show that our puncture detection algorithm, when combined with the active positive holding feature enables sustained cannulation which is most evident in smaller veins. Notable is that the active holding function significantly attenuates tool motion in the vein, thereby reduces the trauma during cannulation. Full article

(This article belongs to the Special Issue Force and Pressure Based Sensing Medical Application)

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15 pages, 9466 KiB

Open AccessArticle

Towards the Automatic Detection of Pre-Existing Termite Mounds through UAS and Hyperspectral Imagery

by Juan Sandino^*,†,‡

, Adam Wooler^†,‡ and Felipe Gonzalez^†,‡

¹ Robotics and autonomous systems, Queensland University of Technology (QUT), Brisbane City QLD 4000, Australia

^† Current address: 2 George Street, Brisbane City, QLD, 4000, Australia.

^‡ These authors contributed equally to this work.

Sensors 2017, 17(10), 2196; https://doi.org/10.3390/s17102196 - 24 Sep 2017

Cited by 8 | Viewed by 5663

Abstract

The increased technological developments in Unmanned Aerial Vehicles (UAVs) combined with artificial intelligence and Machine Learning (ML) approaches have opened the possibility of remote sensing of extensive areas of arid lands. In this paper, a novel approach towards the detection of termite mounds [...] Read more.

The increased technological developments in Unmanned Aerial Vehicles (UAVs) combined with artificial intelligence and Machine Learning (ML) approaches have opened the possibility of remote sensing of extensive areas of arid lands. In this paper, a novel approach towards the detection of termite mounds with the use of a UAV, hyperspectral imagery, ML and digital image processing is intended. A new pipeline process is proposed to detect termite mounds automatically and to reduce, consequently, detection times. For the classification stage, several ML classification algorithms’ outcomes were studied, selecting support vector machines as the best approach for their role in image classification of pre-existing termite mounds. Various test conditions were applied to the proposed algorithm, obtaining an overall accuracy of 68%. Images with satisfactory mound detection proved that the method is “resolution-dependent”. These mounds were detected regardless of their rotation and position in the aerial image. However, image distortion reduced the number of detected mounds due to the inclusion of a shape analysis method in the object detection phase, and image resolution is still determinant to obtain accurate results. Hyperspectral imagery demonstrated better capabilities to classify a huge set of materials than implementing traditional segmentation methods on RGB images only. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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18 pages, 5024 KiB

Open AccessArticle

Hardware in the Loop Performance Assessment of LIDAR-Based Spacecraft Pose Determination

by Roberto Opromolla^*

, Giancarmine Fasano

, Giancarlo Rufino

and Michele Grassi

Department of Industrial Engineering, University of Naples “Federico II”, P.le Tecchio 80, 80125 Naples, Italy

Sensors 2017, 17(10), 2197; https://doi.org/10.3390/s17102197 - 24 Sep 2017

Cited by 5 | Viewed by 4988

Abstract

In this paper an original, easy to reproduce, semi-analytic calibration approach is developed for hardware-in-the-loop performance assessment of pose determination algorithms processing point cloud data, collected by imaging a non-cooperative target with LIDARs. The laboratory setup includes a scanning LIDAR, a monocular camera, [...] Read more.

In this paper an original, easy to reproduce, semi-analytic calibration approach is developed for hardware-in-the-loop performance assessment of pose determination algorithms processing point cloud data, collected by imaging a non-cooperative target with LIDARs. The laboratory setup includes a scanning LIDAR, a monocular camera, a scaled-replica of a satellite-like target, and a set of calibration tools. The point clouds are processed by uncooperative model-based algorithms to estimate the target relative position and attitude with respect to the LIDAR. Target images, acquired by a monocular camera operated simultaneously with the LIDAR, are processed applying standard solutions to the Perspective-n-Points problem to get high-accuracy pose estimates which can be used as a benchmark to evaluate the accuracy attained by the LIDAR-based techniques. To this aim, a precise knowledge of the extrinsic relative calibration between the camera and the LIDAR is essential, and it is obtained by implementing an original calibration approach which does not need ad-hoc homologous targets (e.g., retro-reflectors) easily recognizable by the two sensors. The pose determination techniques investigated by this work are of interest to space applications involving close-proximity maneuvers between non-cooperative platforms, e.g., on-orbit servicing and active debris removal. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 3997 KiB

Open AccessArticle

Copper Oxide Chitosan Nanocomposite: Characterization and Application in Non-Enzymatic Hydrogen Peroxide Sensing

by Antonella Arena^*, Graziella Scandurra

and Carmine Ciofi

Department of Engineering, Messina University, Messina 98166, Italy

Sensors 2017, 17(10), 2198; https://doi.org/10.3390/s17102198 - 24 Sep 2017

Cited by 21 | Viewed by 5194

Abstract

Electrochemical dissolution of metallic copper into slightly acidic aqueous solutions of chitosan yields a clear and stable dispersion of Copper Oxide nanoparticles into the organic polymer host. The electrochemically synthesized chitosan:CuOx nanocomposite is characterized by means of spectrophotometry, frequency domain electrical measurements and [...] Read more.

Electrochemical dissolution of metallic copper into slightly acidic aqueous solutions of chitosan yields a clear and stable dispersion of Copper Oxide nanoparticles into the organic polymer host. The electrochemically synthesized chitosan:CuOx nanocomposite is characterized by means of spectrophotometry, frequency domain electrical measurements and morphological analysis. Solid state electrochemical cells having pure chitosan as the electrolyte and using chitosan:CuOx as the electrode, are developed and characterized by means of electrical measurements performed in the ±1 V voltage window. The current-voltage loops of the cells, measured in deionized water, are found to reversibly change in response to hydrogen peroxide added to the water in 0.2 μM subsequent steps. Such changes, clearly distinguishable from changes recorded in response to other analytes, can be exploited in order to develop a hydrogen peroxide sensor able to work without the need for any supporting electrolyte. Full article

(This article belongs to the Section Chemical Sensors)

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18 pages, 9373 KiB

Open AccessArticle

Improving Night Time Driving Safety Using Vision-Based Classification Techniques

by Jong-Chih Chien¹, Yong-Sheng Chen² and Jiann-Der Lee^2,3,4,*

¹ Degree Program of Digital Space and Product Design, Kainan University, Taoyuan City 338, Taiwan

² Department of Electrical Engineering, Chang-Gung University, Taoyuan City 333, Taiwan

³ Department of Neurosurgery, Chang Gung Memorial Hospital, LinKou, Taoyuan City 333, Taiwan

⁴ Department of Electrical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan

Sensors 2017, 17(10), 2199; https://doi.org/10.3390/s17102199 - 24 Sep 2017

Cited by 11 | Viewed by 5680

Abstract

The risks involved in nighttime driving include drowsy drivers and dangerous vehicles. Prominent among the more dangerous vehicles around at night are the larger vehicles which are usually moving faster at night on a highway. In addition, the risk level of driving around [...] Read more.

The risks involved in nighttime driving include drowsy drivers and dangerous vehicles. Prominent among the more dangerous vehicles around at night are the larger vehicles which are usually moving faster at night on a highway. In addition, the risk level of driving around larger vehicles rises significantly when the driver’s attention becomes distracted, even for a short period of time. For the purpose of alerting the driver and elevating his or her safety, in this paper we propose two components for any modern vision-based Advanced Drivers Assistance System (ADAS). These two components work separately for the single purpose of alerting the driver in dangerous situations. The purpose of the first component is to ascertain that the driver would be in a sufficiently wakeful state to receive and process warnings; this is the driver drowsiness detection component. The driver drowsiness detection component uses infrared images of the driver to analyze his eyes’ movements using a MSR plus a simple heuristic. This component issues alerts to the driver when the driver’s eyes show distraction and are closed for a longer than usual duration. Experimental results show that this component can detect closed eyes with an accuracy of 94.26% on average, which is comparable to previous results using more sophisticated methods. The purpose of the second component is to alert the driver when the driver’s vehicle is moving around larger vehicles at dusk or night time. The large vehicle detection component accepts images from a regular video driving recorder as input. A bi-level system of classifiers, which included a novel MSR-enhanced KAZE-base Bag-of-Features classifier, is proposed to avoid false negatives. In both components, we propose an improved version of the Multi-Scale Retinex (MSR) algorithm to augment the contrast of the input. Several experiments were performed to test the effects of the MSR and each classifier, and the results are presented in experimental results section of this paper. Full article

(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)

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21 pages, 2563 KiB

Open AccessArticle

Secure Utilization of Beacons and UAVs in Emergency Response Systems for Building Fire Hazard

by Seung-Hyun Seo^*, Jung-In Choi and Jinseok Song

The Division of Electrical Engineering, Hanyang University, ERICA Campus, Gyeonggi-do, Ansan 15588, Korea

Sensors 2017, 17(10), 2200; https://doi.org/10.3390/s17102200 - 25 Sep 2017

Cited by 27 | Viewed by 8644

Abstract

An intelligent emergency system for hazard monitoring and building evacuation is a very important application area in Internet of Things (IoT) technology. Through the use of smart sensors, such a system can provide more vital and reliable information to first-responders and also reduce [...] Read more.

An intelligent emergency system for hazard monitoring and building evacuation is a very important application area in Internet of Things (IoT) technology. Through the use of smart sensors, such a system can provide more vital and reliable information to first-responders and also reduce the incidents of false alarms. Several smart monitoring and warning systems do already exist, though they exhibit key weaknesses such as a limited monitoring coverage and security, which have not yet been sufficiently addressed. In this paper, we propose a monitoring and emergency response method for buildings by utilizing beacons and Unmanned Aerial Vehicles (UAVs) on an IoT security platform. In order to demonstrate the practicability of our method, we also implement a proof of concept prototype, which we call the UAV-EMOR (UAV-assisted Emergency Monitoring and Response) system. Our UAV-EMOR system provides the following novel features: (1) secure communications between UAVs, smart sensors, the control server and a smartphone app for security managers; (2) enhanced coordination between smart sensors and indoor/outdoor UAVs to expand real-time monitoring coverage; and (3) beacon-aided rescue and building evacuation. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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42 pages, 2875 KiB

Open AccessArticle

DISPAQ: Distributed Profitable-Area Query from Big Taxi Trip Data

by Fadhilah Kurnia Putri¹, Giltae Song², Joonho Kwon^2,*

and Praveen Rao³

¹ Department of Big Data, Pusan National University, Busan 46241, Korea

² School of Computer Science and Engineering, Pusan National University; Busan 46241, Korea

³ Department of Computer Science & Electrical Engineering, University of Missouri-Kansas City, Kansas City, MO 64110, USA

Sensors 2017, 17(10), 2201; https://doi.org/10.3390/s17102201 - 25 Sep 2017

Cited by 8 | Viewed by 6606

Abstract

One of the crucial problems for taxi drivers is to efficiently locate passengers in order to increase profits. The rapid advancement and ubiquitous penetration of Internet of Things (IoT) technology into transportation industries enables us to provide taxi drivers with locations that have [...] Read more.

One of the crucial problems for taxi drivers is to efficiently locate passengers in order to increase profits. The rapid advancement and ubiquitous penetration of Internet of Things (IoT) technology into transportation industries enables us to provide taxi drivers with locations that have more potential passengers (more profitable areas) by analyzing and querying taxi trip data. In this paper, we propose a query processing system, called Distributed Profitable-Area Query (DISPAQ) which efficiently identifies profitable areas by exploiting the Apache Software Foundation’s Spark framework and a MongoDB database. DISPAQ first maintains a profitable-area query index (PQ-index) by extracting area summaries and route summaries from raw taxi trip data. It then identifies candidate profitable areas by searching the PQ-index during query processing. Then, it exploits a Z-Skyline algorithm, which is an extension of skyline processing with a Z-order space filling curve, to quickly refine the candidate profitable areas. To improve the performance of distributed query processing, we also propose local Z-Skyline optimization, which reduces the number of dominant tests by distributing killer profitable areas to each cluster node. Through extensive evaluation with real datasets, we demonstrate that our DISPAQ system provides a scalable and efficient solution for processing profitable-area queries from huge amounts of big taxi trip data. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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19 pages, 1203 KiB

Open AccessArticle

Avionic Air Data Sensors Fault Detection and Isolation by means of Singular Perturbation and Geometric Approach

by Paolo Castaldi¹

, Nicola Mimmo^1,*

and Silvio Simani²

¹ Department of Electrical, Electronic and Information Engineering, University of Bologna, Faculty of Aerospace Engineering, Via Fontanelle 40, 47121 Forlí, Italy

² Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara, Italy

Sensors 2017, 17(10), 2202; https://doi.org/10.3390/s17102202 - 25 Sep 2017

Cited by 16 | Viewed by 7097

Abstract

Singular Perturbations represent an advantageous theory to deal with systems characterized by a two-time scale separation, such as the longitudinal dynamics of aircraft which are called phugoid and short period. In this work, the combination of the NonLinear Geometric Approach and the [...] Read more.

Singular Perturbations represent an advantageous theory to deal with systems characterized by a two-time scale separation, such as the longitudinal dynamics of aircraft which are called phugoid and short period. In this work, the combination of the NonLinear Geometric Approach and the Singular Perturbations leads to an innovative Fault Detection and Isolation system dedicated to the isolation of faults affecting the air data system of a general aviation aircraft. The isolation capabilities, obtained by means of the approach proposed in this work, allow for the solution of a fault isolation problem otherwise not solvable by means of standard geometric techniques. Extensive Monte-Carlo simulations, exploiting a high fidelity aircraft simulator, show the effectiveness of the proposed Fault Detection and Isolation system. Full article

(This article belongs to the Special Issue Models, Systems and Applications for Sensors in Cyber Physical Systems)

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13 pages, 784 KiB

Open AccessArticle

Comparison of Methods Study between a Photonic Crystal Biosensor and Certified ELISA to Measure Biomarkers of Iron Deficiency in Chronic Kidney Disease Patients

by Ross D. Peterson¹, Kenneth R. Wilund^2,3, Brian T. Cunningham^4,5 and Juan E. Andrade^1,3,*

¹ Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

² Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

³ Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

⁴ Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

⁵ Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

Sensors 2017, 17(10), 2203; https://doi.org/10.3390/s17102203 - 25 Sep 2017

Cited by 6 | Viewed by 6189

Abstract

The total analytical error of a photonic crystal (PC) biosensor in the determination of ferritin and soluble transferrin receptor (sTfR) as biomarkers of iron deficiency anemia in chronic kidney disease (CKD) patients was evaluated against certified ELISAs. Antigens were extracted from sera of [...] Read more.

The total analytical error of a photonic crystal (PC) biosensor in the determination of ferritin and soluble transferrin receptor (sTfR) as biomarkers of iron deficiency anemia in chronic kidney disease (CKD) patients was evaluated against certified ELISAs. Antigens were extracted from sera of CKD patients using functionalized iron-oxide nanoparticles (fAb-IONs) followed by magnetic separation. Immuno-complexes were recognized by complementary detection Ab affixed to the PC biosensor surface, and their signals were followed using the BIND instrument. Quantification was conducted against actual protein standards. Total calculated error (TEcalc) was estimated based on systematic (SE) and random error (RE) and compared against total allowed error (TEa) based on established quality specifications. Both detection platforms showed adequate linearity, specificity, and sensitivity for biomarkers. Means, SD, and CV were similar between biomarkers for both detection platforms. Compared to ELISA, inherent imprecision was higher on the PC biosensor for ferritin, but not for sTfR. High SE or RE in the PC biosensor when measuring either biomarker resulted in TEcalc higher than the TEa. This did not influence the diagnostic ability of the PC biosensor to discriminate CKD patients with low iron stores. The performance of the PC biosensor is similar to certified ELISAs; however, optimization is required to reduce TEcalc. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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15 pages, 989 KiB

Open AccessArticle

Application of CMOS Technology to Silicon Photomultiplier Sensors

by Nicola D’Ascenzo^*,†, Xi Zhang^† and Qingguo Xie^*,†

¹ School of life science and technology, Huazhong University of Science and Technology, Wuhan 430073, China

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2204; https://doi.org/10.3390/s17102204 - 25 Sep 2017

Cited by 14 | Viewed by 6139

Abstract

We use the 180 nm GLOBALFOUNDRIES (GF) BCDLite CMOS process for the production of a silicon photomultiplier prototype. We study the main characteristics of the developed sensor in comparison with commercial SiPMs obtained in custom technologies and other SiPMs developed with CMOS-compatible processes. [...] Read more.

We use the 180 nm GLOBALFOUNDRIES (GF) BCDLite CMOS process for the production of a silicon photomultiplier prototype. We study the main characteristics of the developed sensor in comparison with commercial SiPMs obtained in custom technologies and other SiPMs developed with CMOS-compatible processes. We support our discussion with a transient modeling of the detection process of the silicon photomultiplier as well as with a series of static and dynamic experimental measurements in dark and illuminated environments. Full article

(This article belongs to the Special Issue Silicon Technologies for Photonic Sensors)

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15 pages, 2862 KiB

Open AccessArticle

Study of GNSS Loss of Lock Characteristics under Ionosphere Scintillation with GNSS Data at Weipa (Australia) During Solar Maximum Phase

by Yang Liu^1,2,3,*, Lianjie Fu¹, Jinling Wang⁴ and Chunxi Zhang¹

¹ School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing 100191, China

² Abdus Salam International Centre for Theoretical Physics, Telecommunications/ICT for Development Laboratory, Trieste 34151, Italy

³ Collaborative Innovation Center of Geospatial Technology, Wuhan 430000, China

⁴ School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia

Sensors 2017, 17(10), 2205; https://doi.org/10.3390/s17102205 - 25 Sep 2017

Cited by 19 | Viewed by 4999

Abstract

One of the adverse impacts of scintillation on GNSS signals is the loss of lock status, which can lead to GNSS geometry and visibility reductions that compromise the accuracy and integrity of navigation performance. In this paper the loss of lock based on [...] Read more.

One of the adverse impacts of scintillation on GNSS signals is the loss of lock status, which can lead to GNSS geometry and visibility reductions that compromise the accuracy and integrity of navigation performance. In this paper the loss of lock based on ionosphere scintillation in this solar maximum phase has been well investigated with respect to both temporal and spatial behaviors, based on GNSS observatory data collected at Weipa (Australia; geographic: 12.45° S, 130.95° E; geomagnetic: 21.79° S, 214.41° E) from 2011 to 2015. Experiments demonstrate that the percentage of occurrence of loss of lock events under ionosphere scintillation is closely related with solar activity and seasonal shifts. Loss of lock behaviors under ionosphere scintillation related to elevation and azimuth angles are statistically analyzed, with some distinct characteristics found. The influences of daytime scintillation and geomagnetic storms on loss of lock have also been discussed in details. The proposed work is valuable for a deeper understanding of theoretical mechanisms of—loss of lock under ionosphere scintillation in global regions, and provides a reference for GNSS applications in certain regions at Australian low latitudes. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 338 KiB

Open AccessArticle

Average Throughput Performance of Myopic Policy in Energy Harvesting Wireless Sensor Networks

by Omer Melih Gul^*

and Mubeccel Demirekler

Department of Electrical and Electronics Engineering, Middle East Technical University (METU), 06531 Cankaya, Ankara, Turkey

Sensors 2017, 17(10), 2206; https://doi.org/10.3390/s17102206 - 26 Sep 2017

Cited by 13 | Viewed by 4642

Abstract

This paper considers a single-hop wireless sensor network where a fusion center collects data from M energy harvesting wireless sensors. The harvested energy is stored losslessly in an infinite-capacity battery at each sensor. In each time slot, the fusion center schedules K sensors [...] Read more.

This paper considers a single-hop wireless sensor network where a fusion center collects data from M energy harvesting wireless sensors. The harvested energy is stored losslessly in an infinite-capacity battery at each sensor. In each time slot, the fusion center schedules K sensors for data transmission over K orthogonal channels. The fusion center does not have direct knowledge on the battery states of sensors, or the statistics of their energy harvesting processes. The fusion center only has information of the outcomes of previous transmission attempts. It is assumed that the sensors are data backlogged, there is no battery leakage and the communication is error-free. An energy harvesting sensor can transmit data to the fusion center whenever being scheduled only if it has enough energy for data transmission. We investigate average throughput of Round-Robin type myopic policy both analytically and numerically under an average reward (throughput) criterion. We show that Round-Robin type myopic policy achieves optimality for some class of energy harvesting processes although it is suboptimal for a broad class of energy harvesting processes. Full article

(This article belongs to the Special Issue Energy Harvesting Sensors for Long Term Applications in the IoT Era)

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24 pages, 13659 KiB

Open AccessArticle

ePave: A Self-Powered Wireless Sensor for Smart and Autonomous Pavement

by Jian Xiao^1,*, Xiang Zou¹ and Wenyao Xu²

¹ Road Traffic Intelligent Detection and Equipment Engineering Technology Research Centre, Chang’an University, Xi’an 710064, China

² Department of Computer Science and Engineering, University at Buffalo, SUNY, Buffalo, NY 14260, USA

Sensors 2017, 17(10), 2207; https://doi.org/10.3390/s17102207 - 26 Sep 2017

Cited by 34 | Viewed by 12972

Abstract

“Smart Pavement” is an emerging infrastructure for various on-road applications in transportation and road engineering. However, existing road monitoring solutions demand a certain periodic maintenance effort due to battery life limits in the sensor systems. To this end, we present an end-to-end self-powered [...] Read more.

“Smart Pavement” is an emerging infrastructure for various on-road applications in transportation and road engineering. However, existing road monitoring solutions demand a certain periodic maintenance effort due to battery life limits in the sensor systems. To this end, we present an end-to-end self-powered wireless sensor—ePave—to facilitate smart and autonomous pavements. The ePave system includes a self-power module, an ultra-low-power sensor system, a wireless transmission module and a built-in power management module. First, we performed an empirical study to characterize the piezoelectric module in order to optimize energy-harvesting efficiency. Second, we developed an integrated sensor system with the optimized energy harvester. An adaptive power knob is designated to adjust the power consumption according to energy budgeting. Finally, we intensively evaluated the ePave system in real-world applications to examine the system’s performance and explore the trade-off. Full article

(This article belongs to the Special Issue Wireless Rechargeable Sensor Networks)

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25 pages, 15820 KiB

Open AccessArticle

Pulsed Eddy Current Sensing for Critical Pipe Condition Assessment

by Nalika Ulapane^*

, Alen Alempijevic

, Teresa Vidal Calleja

and Jaime Valls Miro

Centre for Autonomous Systems (CB 11.09.300), Faculty of Engineering and Information Technology, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia

Sensors 2017, 17(10), 2208; https://doi.org/10.3390/s17102208 - 26 Sep 2017

Cited by 47 | Viewed by 9943

Abstract

Pulsed Eddy Current (PEC) sensing is used for Non-Destructive Evaluation (NDE) of the structural integrity of metallic structures in the aircraft, railway, oil and gas sectors. Urban water utilities also have extensive large ferromagnetic structures in the form of critical pressure pipe systems [...] Read more.

Pulsed Eddy Current (PEC) sensing is used for Non-Destructive Evaluation (NDE) of the structural integrity of metallic structures in the aircraft, railway, oil and gas sectors. Urban water utilities also have extensive large ferromagnetic structures in the form of critical pressure pipe systems made of grey cast iron, ductile cast iron and mild steel. The associated material properties render NDE of these pipes by means of electromagnetic sensing a necessity. In recent years PEC sensing has established itself as a state-of-the-art NDE technique in the critical water pipe sector. This paper presents advancements to PEC inspection in view of the specific information demanded from water utilities along with the challenges encountered in this sector. Operating principles of the sensor architecture suitable for application on critical pipes are presented with the associated sensor design and calibration strategy. A Gaussian process-based approach is applied to model a functional relationship between a PEC signal feature and critical pipe wall thickness. A case study demonstrates the sensor’s behaviour on a grey cast iron pipe and discusses the implications of the observed results and challenges relating to this application. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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13 pages, 6393 KiB

Open AccessArticle

A Fast Terahertz Imaging Method Using Sparse Rotating Array

by Yanwen Jiang^*, Bin Deng, Yuliang Qin, Hongqiang Wang

and Kang Liu

College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China

Sensors 2017, 17(10), 2209; https://doi.org/10.3390/s17102209 - 26 Sep 2017

Cited by 9 | Viewed by 4856

Abstract

For fast and standoff personal screening, a novel terahertz imaging scheme using a sparse rotating array is developed in this paper. A linearly sparse array is designed to move along a circular path with respect to an axis perpendicular to the imaging scenario. [...] Read more.

For fast and standoff personal screening, a novel terahertz imaging scheme using a sparse rotating array is developed in this paper. A linearly sparse array is designed to move along a circular path with respect to an axis perpendicular to the imaging scenario. For this new scheme, a modified imaging algorithm is proposed based on the frequency-domain reconstruction method in circular synthetic aperture radar. To achieve better imaging performance, an optimization method of the sparse array is also proposed, according to the distribution of the spectral support. Theoretical and numerical analysis of the point spread function (PSF) is provided to demonstrate the high-resolution imaging ability of the proposed scheme. Comprehensive simulations are carried out to validate the feasibility and effectiveness of the array optimization method. Finally, the imaging results of a human-scattering model are also obtained to further demonstrate the good performance of this new imaging scheme and the effectiveness of the array optimization approach. This work can facilitate the design and practice of terahertz imaging systems for security inspection. Full article

(This article belongs to the Special Issue Synthetic Aperture Radar (SAR) Technology: New Perspectives Offered by New-Generation and Forthcoming SAR Sensors)

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22 pages, 3773 KiB

Open AccessArticle

Towards a Transferable UAV-Based Framework for River Hydromorphological Characterization

by Mónica Rivas Casado^1,*

, Rocío Ballesteros González²

, José Fernando Ortega²

, Paul Leinster¹ and Ros Wright³

¹ School of Water, Energy and Environment, Cranfield University, Cranfield, Bedfordshire MK430AL, UK

² Regional Centre of Water Research, Universidad de Castilla-La Mancha, Carretera de las Peñas km 3.2, 02071 Albacete, Spain

³ National Fisheries Services, Environment Agency, Threshelfords Business Park, Inworth Road, Feering, Essex CO61UD, UK

Sensors 2017, 17(10), 2210; https://doi.org/10.3390/s17102210 - 26 Sep 2017

Cited by 15 | Viewed by 5897

Abstract

The multiple protocols that have been developed to characterize river hydromorphology, partly in response to legislative drivers such as the European Union Water Framework Directive (EU WFD), make the comparison of results obtained in different countries challenging. Recent studies have analyzed the comparability [...] Read more.

The multiple protocols that have been developed to characterize river hydromorphology, partly in response to legislative drivers such as the European Union Water Framework Directive (EU WFD), make the comparison of results obtained in different countries challenging. Recent studies have analyzed the comparability of existing methods, with remote sensing based approaches being proposed as a potential means of harmonizing hydromorphological characterization protocols. However, the resolution achieved by remote sensing products may not be sufficient to assess some of the key hydromorphological features that are required to allow an accurate characterization. Methodologies based on high resolution aerial photography taken from Unmanned Aerial Vehicles (UAVs) have been proposed by several authors as potential approaches to overcome these limitations. Here, we explore the applicability of an existing UAV based framework for hydromorphological characterization to three different fluvial settings representing some of the distinct ecoregions defined by the WFD geographical intercalibration groups (GIGs). The framework is based on the automated recognition of hydromorphological features via tested and validated Artificial Neural Networks (ANNs). Results show that the framework is transferable to the Central-Baltic and Mediterranean GIGs with accuracies in feature identification above 70%. Accuracies of 50% are achieved when the framework is implemented in the Very Large Rivers GIG. The framework successfully identified vegetation, deep water, shallow water, riffles, side bars and shadows for the majority of the reaches. However, further algorithm development is required to ensure a wider range of features (e.g., chutes, structures and erosion) are accurately identified. This study also highlights the need to develop an objective and fit for purpose hydromorphological characterization framework to be adopted within all EU member states to facilitate comparison of results. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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17 pages, 5263 KiB

Open AccessArticle

Energy Neutral Wireless Bolt for Safety Critical Fastening

by Biruk B. Seyoum^*, Maurizio Rossi^*

and Davide Brunelli^*

Department of Industrial Engineering, University of Trento, Via Sommarive, 9, 38123 Trento, Italy

Sensors 2017, 17(10), 2211; https://doi.org/10.3390/s17102211 - 26 Sep 2017

Cited by 5 | Viewed by 5314

Abstract

Thermoelectric generators (TEGs) are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius) temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized [...] Read more.

Thermoelectric generators (TEGs) are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius) temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized battery-free sensor modules powered by TEGs. In this article, we present the design of an ambient-powered wireless bolt for high-end electro-mechanical systems. The bolt is equipped with a temperature sensor and a low power RF chip powered from a TEG. A DC-DC converter interfacing the TEG with the RF chip is used to step-up the low TEG voltage. The work includes the characterizations of different TEGs and DC-DC converters to determine the optimal design based on the amount of power that can be generated from a TEG under different loads and at temperature gradients typical of industrial environments. A prototype system was implemented and the power consumption of this system under different conditions was also measured. Results demonstrate that the power generated by the TEG at very low temperature gradients is sufficient to guarantee continuous wireless monitoring of the critical fasteners in critical systems such as avionics, motorsport and aerospace. Full article

(This article belongs to the Special Issue Energy Harvesting Sensors for Long Term Applications in the IoT Era)

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25 pages, 1459 KiB

Open AccessArticle

EDOVE: Energy and Depth Variance-Based Opportunistic Void Avoidance Scheme for Underwater Acoustic Sensor Networks

by Safdar Hussain Bouk^1,*, Syed Hassan Ahmed²

, Kyung-Joon Park¹

and Yongsoon Eun¹

¹ Department of Information and Communication Engineering, DGIST, Daegu 42988, Korea

² School of Computer Science and Engineering, Kyungpook National University, Daegu 41566, Korea

Sensors 2017, 17(10), 2212; https://doi.org/10.3390/s17102212 - 26 Sep 2017

Cited by 28 | Viewed by 5877

Abstract

Underwater Acoustic Sensor Network (UASN) comes with intrinsic constraints because it is deployed in the aquatic environment and uses the acoustic signals to communicate. The examples of those constraints are long propagation delay, very limited bandwidth, high energy cost for transmission, very high [...] Read more.

Underwater Acoustic Sensor Network (UASN) comes with intrinsic constraints because it is deployed in the aquatic environment and uses the acoustic signals to communicate. The examples of those constraints are long propagation delay, very limited bandwidth, high energy cost for transmission, very high signal attenuation, costly deployment and battery replacement, and so forth. Therefore, the routing schemes for UASN must take into account those characteristics to achieve energy fairness, avoid energy holes, and improve the network lifetime. The depth based forwarding schemes in literature use node’s depth information to forward data towards the sink. They minimize the data packet duplication by employing the holding time strategy. However, to avoid void holes in the network, they use two hop node proximity information. In this paper, we propose the Energy and Depth variance-based Opportunistic Void avoidance (EDOVE) scheme to gain energy balancing and void avoidance in the network. EDOVE considers not only the depth parameter, but also the normalized residual energy of the one-hop nodes and the normalized depth variance of the second hop neighbors. Hence, it avoids the void regions as well as balances the network energy and increases the network lifetime. The simulation results show that the EDOVE gains more than

15 %

packet delivery ratio, propagates

50 %

less copies of data packet, consumes less energy, and has more lifetime than the state of the art forwarding schemes. Full article

(This article belongs to the Special Issue Advances and Challenges in Underwater Sensor Networks)

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20 pages, 6606 KiB

Open AccessArticle

Variation of River Islands around a Large City along the Yangtze River from Satellite Remote Sensing Images

by Haiyun Shi¹, Chao Gao², Changming Dong^1,3,*, Changshui Xia^4,5 and Guanglai Xu⁶

¹ School of Marine Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China

² Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo 315211, China

³ Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA

⁴ Key Lab of Marine Science and Numerical Modeling, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China

⁵ Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China

⁶ College of Territorial Resources and Tourism, Anhui Normal University, Wuhu 241000, China

Sensors 2017, 17(10), 2213; https://doi.org/10.3390/s17102213 - 27 Sep 2017

Cited by 15 | Viewed by 5218

Abstract

River islands are sandbars formed by scouring and silting. Their evolution is affected by several factors, among which are runoff and sediment discharge. The spatial-temporal evolution of seven river islands in the Nanjing Section of the Yangtze River of China was examined using [...] Read more.

River islands are sandbars formed by scouring and silting. Their evolution is affected by several factors, among which are runoff and sediment discharge. The spatial-temporal evolution of seven river islands in the Nanjing Section of the Yangtze River of China was examined using TM (Thematic Mapper) and ETM (Enhanced Thematic Mapper)+ images from 1985 to 2015 at five year intervals. The following approaches were applied in this study: the threshold value method, binarization model, image registration, image cropping, convolution and cluster analysis. Annual runoff and sediment discharge data as measured at the Datong hydrological station upstream of Nanjing section were also used to determine the roles and impacts of various factors. The results indicated that: (1) TM/ETM+ images met the criteria of information extraction of river islands; (2) generally, the total area of these islands in this section and their changing rate decreased over time; (3) sediment and river discharge were the most significant factors in island evolution. They directly affect river islands through silting or erosion. Additionally, anthropocentric influences could play increasingly important roles. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 10087 KiB

Open AccessArticle

Doping Ag in ZnO Nanorods to Improve the Performance of Related Enzymatic Glucose Sensors

by Fan Zhou

, Weixuan Jing^*, Pengcheng Liu, Dejun Han, Zhuangde Jiang and Zhengying Wei

State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(10), 2214; https://doi.org/10.3390/s17102214 - 27 Sep 2017

Cited by 33 | Viewed by 6439

Abstract

In this paper, the performance of a zinc oxide (ZnO) nanorod-based enzymatic glucose sensor was enhanced with silver (Ag)-doped ZnO (ZnO-Ag) nanorods. The effect of the doped Ag on the surface morphologies, wettability, and electron transfer capability of the ZnO-Ag nanorods, as well [...] Read more.

In this paper, the performance of a zinc oxide (ZnO) nanorod-based enzymatic glucose sensor was enhanced with silver (Ag)-doped ZnO (ZnO-Ag) nanorods. The effect of the doped Ag on the surface morphologies, wettability, and electron transfer capability of the ZnO-Ag nanorods, as well as the catalytic character of glucose oxidase (GOx) and the performance of the glucose sensor was investigated. The results indicate that the doped Ag slightly weakens the surface roughness and hydrophilicity of the ZnO-Ag nanorods, but remarkably increases their electron transfer ability and enhances the catalytic character of GOx. Consequently, the combined effects of the above influencing factors lead to a notable improvement of the performance of the glucose sensor, that is, the sensitivity increases and the detection limit decreases. The optimal amount of the doped Ag is determined to be 2 mM, and the corresponding glucose sensor exhibits a sensitivity of 3.85 μA/(mM·cm²), detection limit of 1.5 μM, linear range of 1.5 × 10⁻³–6.5 mM, and Michaelis-Menten constant of 3.87 mM. Moreover, the glucose sensor shows excellent selectivity to urea, ascorbic acid, and uric acid, in addition to displaying good storage stability. These results demonstrate that ZnO-Ag nanorods are promising matrix materials for the construction of other enzymatic biosensors. Full article

(This article belongs to the Special Issue Semiconductor Materials on Biosensors Application)

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19 pages, 485 KiB

Open AccessArticle

Cluster Cooperation in Wireless-Powered Sensor Networks: Modeling and Performance Analysis

by Chao Zhang^*,†

, Pengcheng Zhang^† and Weizhan Zhang^†

¹ School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2215; https://doi.org/10.3390/s17102215 - 27 Sep 2017

Cited by 6 | Viewed by 4075

Abstract

A wireless-powered sensor network (WPSN) consisting of one hybrid access point (HAP), a near cluster and the corresponding far cluster is investigated in this paper. These sensors are wireless-powered and they transmit information by consuming the harvested energy from signal ejected by the [...] Read more.

A wireless-powered sensor network (WPSN) consisting of one hybrid access point (HAP), a near cluster and the corresponding far cluster is investigated in this paper. These sensors are wireless-powered and they transmit information by consuming the harvested energy from signal ejected by the HAP. Sensors are able to harvest energy as well as store the harvested energy. We propose that if sensors in near cluster do not have their own information to transmit, acting as relays, they can help the sensors in a far cluster to forward information to the HAP in an amplify-and-forward (AF) manner. We use a finite Markov chain to model the dynamic variation process of the relay battery, and give a general analyzing model for WPSN with cluster cooperation. Though the model, we deduce the closed-form expression for the outage probability as the metric of this network. Finally, simulation results validate the start point of designing this paper and correctness of theoretical analysis and show how parameters have an effect on system performance. Moreover, it is also known that the outage probability of sensors in far cluster can be drastically reduced without sacrificing the performance of sensors in near cluster if the transmit power of HAP is fairly high. Furthermore, in the aspect of outage performance of far cluster, the proposed scheme significantly outperforms the direct transmission scheme without cooperation. Full article

(This article belongs to the Special Issue Energy Harvesting Sensors for Long Term Applications in the IoT Era)

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13 pages, 10861 KiB

Open AccessFeature PaperArticle

Co₃O₄ as p-Type Material for CO Sensing in Humid Air

by Svetlana Vladimirova¹, Valeriy Krivetskiy¹, Marina Rumyantseva^1,*

, Alexander Gaskov¹, Natalia Mordvinova^1,2, Oleg Lebedev², Mikhail Martyshov³

and Pavel Forsh^3,4

¹ Faculty of Chemistry, Moscow State University, Moscow 119991, Russia

² Laboratoire CRISMAT, ENSICAEN-CNRS UMR6508, Caen 14050, France

³ Faculty of Physics, Moscow State University, Moscow 119991, Russia

⁴ National Research Center “Kurchatov Institute”, Moscow 123182, Russia

Sensors 2017, 17(10), 2216; https://doi.org/10.3390/s17102216 - 27 Sep 2017

Cited by 60 | Viewed by 8103

Abstract

Nanocrystalline cobalt oxide Co₃O₄ has been prepared by precipitation and subsequent thermal decomposition of a carbonate precursor, and has been characterized in detail using XRD, transmission electron microscopy, and FTIR spectroscopy. The sensory characteristics of the material towards carbon monoxide [...] Read more.

Nanocrystalline cobalt oxide Co₃O₄ has been prepared by precipitation and subsequent thermal decomposition of a carbonate precursor, and has been characterized in detail using XRD, transmission electron microscopy, and FTIR spectroscopy. The sensory characteristics of the material towards carbon monoxide in the concentration range 6.7–20 ppm have been examined in both dry and humid air. A sensor signal is achieved in dry air at sufficiently low temperatures T = 80–120 °C, but the increase in relative humidity results in the disappearance of sensor signal in this temperature range. At temperatures above 200 °C the inversion of the sensor signal in dry air was observed. In the temperature interval 180–200 °C the sensor signal toward CO is nearly the same at 0, 20 and 60% r.h. The obtained results are discussed in relation with the specific features of the adsorption of CO, oxygen, and water molecules on the surface of Co₃O₄. The independence of the sensor signal from the air humidity combined with a sufficiently short response time at a moderate operating temperature makes Co₃O₄ a very promising material for CO detection in conditions of variable humidity. Full article

(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)

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23 pages, 965 KiB

Open AccessArticle

Smart Bandwidth Assignation in an Underlay Cellular Network for Internet of Vehicles

by Idoia De la Iglesia^1,2,*, Unai Hernandez-Jayo^1,2, Eneko Osaba^1,2

and Roberto Carballedo^1,2

¹ DeustoTech-Fundacion Deusto, Deusto Foundation, Av. Universidades, 24, 48007 Bilbao, Spain

² Facultad Ingeniería, Universidad de Deusto, Avda. Universidades, 24, 48007 Bilbao, Spain

Sensors 2017, 17(10), 2217; https://doi.org/10.3390/s17102217 - 27 Sep 2017

Cited by 14 | Viewed by 5176

Abstract

The evolution of the IoT (Internet of Things) paradigm applied to new scenarios as VANETs (Vehicular Ad Hoc Networks) has gained momentum in recent years. Both academia and industry have triggered advanced studies in the IoV (Internet of Vehicles), which is understood as [...] Read more.

The evolution of the IoT (Internet of Things) paradigm applied to new scenarios as VANETs (Vehicular Ad Hoc Networks) has gained momentum in recent years. Both academia and industry have triggered advanced studies in the IoV (Internet of Vehicles), which is understood as an ecosystem where different types of users (vehicles, elements of the infrastructure, pedestrians) are connected. How to efficiently share the available radio resources among the different types of eligible users is one of the important issues to be addressed. This paper briefly analyzes various concepts presented hitherto in the literature and it proposes an enhanced algorithm for ensuring a robust co-existence of the aforementioned system users. Therefore, this paper introduces an underlay RRM (Radio Resource Management) methodology which is capable of (1) improving cellular spectral efficiency while making a minimal impact on cellular communications and (2) ensuring the different QoS (Quality of Service) requirements of ITS (Intelligent Transportation Systems) applications. Simulation results, where we compare the proposed algorithm to the other two RRM, show the promising spectral efficiency performance of the proposed RRM methodology. Full article

(This article belongs to the Special Issue Next Generation Wireless Technologies for Internet of Things)

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17 pages, 3733 KiB

Open AccessArticle

Clustered Multi-Task Learning for Automatic Radar Target Recognition

by Cong Li, Weimin Bao, Luping Xu^* and Hua Zhang

School of Aerospace Science and Technology, Xidian University, Xi’an 710126, China

Sensors 2017, 17(10), 2218; https://doi.org/10.3390/s17102218 - 27 Sep 2017

Cited by 7 | Viewed by 5746

Abstract

Model training is a key technique for radar target recognition. Traditional model training algorithms in the framework of single task leaning ignore the relationships among multiple tasks, which degrades the recognition performance. In this paper, we propose a clustered multi-task learning, which can [...] Read more.

Model training is a key technique for radar target recognition. Traditional model training algorithms in the framework of single task leaning ignore the relationships among multiple tasks, which degrades the recognition performance. In this paper, we propose a clustered multi-task learning, which can reveal and share the multi-task relationships for radar target recognition. To further make full use of these relationships, the latent multi-task relationships in the projection space are taken into consideration. Specifically, a constraint term in the projection space is proposed, the main idea of which is that multiple tasks within a close cluster should be close to each other in the projection space. In the proposed method, the cluster structures and multi-task relationships can be autonomously learned and utilized in both of the original and projected space. In view of the nonlinear characteristics of radar targets, the proposed method is extended to a non-linear kernel version and the corresponding non-linear multi-task solving method is proposed. Comprehensive experimental studies on simulated high-resolution range profile dataset and MSTAR SAR public database verify the superiority of the proposed method to some related algorithms. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 3534 KiB

Open AccessArticle

Analyzing Sensor-Based Time Series Data to Track Changes in Physical Activity during Inpatient Rehabilitation

by Gina Sprint^1,*

, Diane Cook²

, Douglas Weeks³, Jordana Dahmen⁴ and Alyssa La Fleur⁵

¹ Department of Computer Science, Gonzaga University, Spokane, WA 99202, USA

² School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99163, USA

³ St. Luke’s Rehabilitation Institute, Spokane, WA 99202, USA

⁴ School of Biological Sciences, Washington State University, Pullman, WA 99163, USA

⁵ Department of Mathematics and Computer Science, Whitworth University, Spokane, WA 99251, USA

Sensors 2017, 17(10), 2219; https://doi.org/10.3390/s17102219 - 27 Sep 2017

Cited by 24 | Viewed by 7401

Abstract

Time series data collected from sensors can be analyzed to monitor changes in physical activity as an individual makes a substantial lifestyle change, such as recovering from an injury or illness. In an inpatient rehabilitation setting, approaches to detect and explain changes in [...] Read more.

Time series data collected from sensors can be analyzed to monitor changes in physical activity as an individual makes a substantial lifestyle change, such as recovering from an injury or illness. In an inpatient rehabilitation setting, approaches to detect and explain changes in longitudinal physical activity data collected from wearable sensors can provide value as a monitoring, research, and motivating tool. We adapt and expand our Physical Activity Change Detection (PACD) approach to analyze changes in patient activity in such a setting. We use Fitbit Charge Heart Rate devices with two separate populations to continuously record data to evaluate PACD, nine participants in a hospitalized inpatient rehabilitation group and eight in a healthy control group. We apply PACD to minute-by-minute Fitbit data to quantify changes within and between the groups. The inpatient rehabilitation group exhibited greater variability in change throughout inpatient rehabilitation for both step count and heart rate, with the greatest change occurring at the end of the inpatient hospital stay, which exceeded day-to-day changes of the control group. Our additions to PACD support effective change analysis of wearable sensor data collected in an inpatient rehabilitation setting and provide insight to patients, clinicians, and researchers. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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9 pages, 4158 KiB

Open AccessArticle

Ag-Modified In₂O₃ Nanoparticles for Highly Sensitive and Selective Ethanol Alarming

by Jinxiao Wang^1,2, Zheng Xie¹, Yuan Si³, Xinyi Liu³, Xinyuan Zhou¹, Jianfeng Yang⁴, Peng Hu¹, Ning Han^1,*

, Jun Yang^2,* and Yunfa Chen¹

¹ State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

² School of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China

³ Beijing ChenJingLun High School, Beijing 100101, China

⁴ State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(10), 2220; https://doi.org/10.3390/s17102220 - 27 Sep 2017

Cited by 20 | Viewed by 5517

Abstract

Pure In₂O₃ nanoparticles are prepared by a facile precipitation method and are further modified by Ag. The synthesized samples are characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and UV-Vis spectra. The results [...] Read more.

Pure In₂O₃ nanoparticles are prepared by a facile precipitation method and are further modified by Ag. The synthesized samples are characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and UV-Vis spectra. The results show the successful heterojunction formation between Ag and In₂O₃. Gas sensing property measurements show that the 5 mol % Ag-modified In₂O₃ sensor has the response of 67 to 50 ppm ethanol, and fast response and recovery time of 22.3 and 11.7 s. The response is over one magnitude higher than that of pure In₂O₃, which can be attributed to the enhanced catalytic activity of Ag-modified In₂O₃ as compared with the pure one. The mechanism of the gas sensor can be explained by the spillover effect of Ag, which enhances the oxygen adsorption onto the surface of In₂O₃ and thus give rise to the higher activity and larger surface barrier height. Full article

(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)

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14 pages, 4125 KiB

Open AccessArticle

Development and Measurements of a Mid-Infrared Multi-Gas Sensor System for CO, CO₂ and CH₄ Detection

by Ming Dong¹, Chuantao Zheng^1,*, Shuzhuo Miao¹, Yu Zhang¹, Qiaoling Du¹, Yiding Wang¹ and Frank K. Tittel²

¹ State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China

² Electrical and Computer Engineering Department, Rice University, 6100 Main Street, Houston, TX 77005, USA

Sensors 2017, 17(10), 2221; https://doi.org/10.3390/s17102221 - 27 Sep 2017

Cited by 100 | Viewed by 11515

Abstract

A multi-gas sensor system was developed that uses a single broadband light source and multiple carbon monoxide (CO), carbon dioxide (CO₂) and methane (CH₄) pyroelectric detectors by use of the time division multiplexing (TDM) technique. A stepper motor-based rotating [...] Read more.

A multi-gas sensor system was developed that uses a single broadband light source and multiple carbon monoxide (CO), carbon dioxide (CO₂) and methane (CH₄) pyroelectric detectors by use of the time division multiplexing (TDM) technique. A stepper motor-based rotating system and a single-reflection spherical optical mirror were designed and adopted to realize and enhance multi-gas detection. Detailed measurements under static detection mode (without rotation) and dynamic mode (with rotation) were performed to study the performance of the sensor system for the three gas species. Effects of the motor rotating period on sensor performances were also investigated and a rotation speed of 0.4π rad/s was required to obtain a stable sensing performance, corresponding to a detection period of ~10 s to realize one round of detection. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 2.96, 4.54 and 2.84 parts per million in volume (ppmv) for CO, CO₂ and CH₄, respectively and the 1σ detection limits under dynamic operations are 8.83, 8.69 and 10.29 ppmv for the three gas species, respectively. The reported sensor has potential applications in various fields requiring CO, CO₂ and CH₄ detection such as in coal mines. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 1512 KiB

Open AccessArticle

A Weighted Measurement Fusion Particle Filter for Nonlinear Multisensory Systems Based on Gauss–Hermite Approximation

by Yun Li^1,2, Shu Li Sun^1,*

and Gang Hao¹

¹ School of Electronic Engineering, Heilongjiang University, Harbin 150080, China

² School of Computer and Information Engineering, Harbin University of Commerce, Harbin 150001, China

Sensors 2017, 17(10), 2222; https://doi.org/10.3390/s17102222 - 28 Sep 2017

Cited by 14 | Viewed by 4272

Abstract

We addressed the fusion estimation problem for nonlinear multisensory systems. Based on the Gauss–Hermite approximation and weighted least square criterion, an augmented high-dimension measurement from all sensors was compressed into a lower dimension. By combining the low-dimension measurement function with the particle filter [...] Read more.

We addressed the fusion estimation problem for nonlinear multisensory systems. Based on the Gauss–Hermite approximation and weighted least square criterion, an augmented high-dimension measurement from all sensors was compressed into a lower dimension. By combining the low-dimension measurement function with the particle filter (PF), a weighted measurement fusion PF (WMF-PF) is presented. The accuracy of WMF-PF appears good and has a lower computational cost when compared to centralized fusion PF (CF-PF). An example is given to show the effectiveness of the proposed algorithms. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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23 pages, 5873 KiB

Open AccessArticle

Adaptation of Dubins Paths for UAV Ground Obstacle Avoidance When Using a Low Cost On-Board GNSS Sensor

by Ramūnas Kikutis, Jonas Stankūnas, Darius Rudinskas and Tadas Masiulionis^*

Department of Avionics, Vilnius Gediminas Technical University, 02187 Vilnius, Lithuania

Sensors 2017, 17(10), 2223; https://doi.org/10.3390/s17102223 - 28 Sep 2017

Cited by 21 | Viewed by 5611

Abstract

Current research on Unmanned Aerial Vehicles (UAVs) shows a lot of interest in autonomous UAV navigation. This interest is mainly driven by the necessity to meet the rules and restrictions for small UAV flights that are issued by various international and national legal [...] Read more.

Current research on Unmanned Aerial Vehicles (UAVs) shows a lot of interest in autonomous UAV navigation. This interest is mainly driven by the necessity to meet the rules and restrictions for small UAV flights that are issued by various international and national legal organizations. In order to lower these restrictions, new levels of automation and flight safety must be reached. In this paper, a new method for ground obstacle avoidance derived by using UAV navigation based on the Dubins paths algorithm is presented. The accuracy of the proposed method has been tested, and research results have been obtained by using Software-in-the-Loop (SITL) simulation and real UAV flights, with the measurements done with a low cost Global Navigation Satellite System (GNSS) sensor. All tests were carried out in a three-dimensional space, but the height accuracy was not assessed. The GNSS navigation data for the ground obstacle avoidance algorithm is evaluated statistically. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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17 pages, 13741 KiB

Open AccessArticle

An Acoustic Signal Enhancement Method Based on Independent Vector Analysis for Moving Target Classification in the Wild

by Qin Zhao^1,2,†, Feng Guo^1,2,†, Xingshui Zu^1,2,†

, Yuchao Chang^1,2,†, Baoqing Li^1,*,†

and Xiaobing Yuan^1,†

¹ Science and Technology on Microsystem Laboratory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 201800, China

² University of Chinese Academy of Sciences, Beijing 100049, China

^† Current address: Science and Technology on Microsystem Laboratory, Building A, Xinwei Mansion, 1455 Pingcheng Road, JiaDing District, Shanghai 201821, China.

Sensors 2017, 17(10), 2224; https://doi.org/10.3390/s17102224 - 28 Sep 2017

Cited by 5 | Viewed by 4524

Abstract

In this paper, we study how to improve the performance of moving target classification by using an acoustic signal enhancement method based on independent vector analysis (IVA) in the unattended ground sensor (UGS) system. Inspired by the IVA algorithm, we propose an improved [...] Read more.

In this paper, we study how to improve the performance of moving target classification by using an acoustic signal enhancement method based on independent vector analysis (IVA) in the unattended ground sensor (UGS) system. Inspired by the IVA algorithm, we propose an improved IVA method based on a microphone array for acoustic signal enhancement in the wild, which adopts a particular multivariate generalized Gaussian distribution as the source prior, an adaptive variable step strategy for the learning algorithm and discrete cosine transform (DCT) to convert the time domain observed signals to the frequency domain. We term the proposed method as DCT-G-IVA. Moreover, we design a target classification system using the improved IVA method for signal enhancement in the UGS system. Different experiments are conducted to evaluate the proposed method for acoustic signal enhancement by comparing with the baseline methods in our classification system under different wild environments. The experimental results validate the superiority of the DCT-G-IVA enhancement method in the classification system for moving targets in the presence of dynamic wind noise. Full article

(This article belongs to the Special Issue Sensor Intelligence Assisted by Data Analytics and Cognitive Computing)

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16 pages, 3612 KiB

Open AccessArticle

A Machine Learning Approach to Argo Data Analysis in a Thermocline

by Yu Jiang^*, Yu Gou, Tong Zhang, Kai Wang and Chengquan Hu^*

College of Computer Science and Technology, Jilin University, Changchun 130012, China

Sensors 2017, 17(10), 2225; https://doi.org/10.3390/s17102225 - 28 Sep 2017

Cited by 28 | Viewed by 6701

Abstract

With the rapid development of sensor networks, big marine data arises. To efficiently use these data to predict thermoclines, we propose a machine learning approach. We firstly focus on analyzing how temperature, salinity, and geographic location features affect the formation of thermocline. Then, [...] Read more.

With the rapid development of sensor networks, big marine data arises. To efficiently use these data to predict thermoclines, we propose a machine learning approach. We firstly focus on analyzing how temperature, salinity, and geographic location features affect the formation of thermocline. Then, an improved model based on entropy value method for the thermocline selection is demonstrated. The experiments adopt BOA Argo data sets and the experimental results show that our novel model can predict thermoclines and related data effectively. Full article

(This article belongs to the Special Issue Models, Systems and Applications for Sensors in Cyber Physical Systems)

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28 pages, 2125 KiB

Open AccessArticle

A Clustering-Oriented Closeness Measure Based on Neighborhood Chain and Its Application in the Clustering Ensemble Framework Based on the Fusion of Different Closeness Measures

by Shaoyi Liang and Deqiang Han^*

MOE KLINNS Lab, Institute of Integrated Automation, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(10), 2226; https://doi.org/10.3390/s17102226 - 28 Sep 2017

Cited by 1 | Viewed by 4276

Abstract

Closeness measures are crucial to clustering methods. In most traditional clustering methods, the closeness between data points or clusters is measured by the geometric distance alone. These metrics quantify the closeness only based on the concerned data points’ positions in the feature space, [...] Read more.

Closeness measures are crucial to clustering methods. In most traditional clustering methods, the closeness between data points or clusters is measured by the geometric distance alone. These metrics quantify the closeness only based on the concerned data points’ positions in the feature space, and they might cause problems when dealing with clustering tasks having arbitrary clusters shapes and different clusters densities. In this paper, we first propose a novel Closeness Measure between data points based on the Neighborhood Chain

(CMNC). Instead of using geometric distances alone,

CMNC measures the closeness between data points by quantifying the difficulty for one data point to reach another through a chain of neighbors. Furthermore, based on

CMNC, we also propose a clustering ensemble framework that combines

CMNC and geometric-distance-based closeness measures together in order to utilize both of their advantages. In this framework, the “bad data points” that are hard to cluster correctly are identified; then different closeness measures are applied to different types of data points to get the unified clustering results. With the fusion of different closeness measures, the framework can get not only better clustering results in complicated clustering tasks, but also higher efficiency. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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24 pages, 1495 KiB

Open AccessArticle

Analytical Modeling Tool for Design of Hydrocarbon Sensitive Optical Fibers

by Khalil Al Handawi^†

, Nader Vahdati^*, Oleg Shiryayev

and Lydia Lawand^†

¹ Department of Mechanical Engineering, Khalifa University of Science and Technology, Petroleum Institute, P.O. Box 2533 Abu Dhabi, UAE

^† Department of Mechanical Engineering, 817 Sherbrooke Street, Room 270, McGill University, Montreal, QC H3A 0C3, Canada.

Sensors 2017, 17(10), 2227; https://doi.org/10.3390/s17102227 - 28 Sep 2017

Cited by 4 | Viewed by 6280

Abstract

Pipelines are the main transportation means for oil and gas products across large distances. Due to the severe conditions they operate in, they are regularly inspected using conventional Pipeline Inspection Gages (PIGs) for corrosion damage. The motivation for researching a real-time distributed monitoring [...] Read more.

Pipelines are the main transportation means for oil and gas products across large distances. Due to the severe conditions they operate in, they are regularly inspected using conventional Pipeline Inspection Gages (PIGs) for corrosion damage. The motivation for researching a real-time distributed monitoring solution arose to mitigate costs and provide a proactive indication of potential failures. Fiber optic sensors with polymer claddings provide a means of detecting contact with hydrocarbons. By coating the fibers with a layer of metal similar in composition to that of the parent pipeline, corrosion of this coating may be detected when the polymer cladding underneath is exposed to the surrounding hydrocarbons contained within the pipeline. A Refractive Index (RI) change occurs in the polymer cladding causing a loss in intensity of a traveling light pulse due to a reduction in the fiber’s modal capacity. Intensity losses may be detected using Optical Time Domain Reflectometry (OTDR) while pinpointing the spatial location of the contact via time delay calculations of the back-scattered pulses. This work presents a theoretical model for the above sensing solution to provide a design tool for the fiber optic cable in the context of hydrocarbon sensing following corrosion of an external metal coating. Results are verified against the experimental data published in the literature. Full article

(This article belongs to the Special Issue Sensors for Oil Applications)

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14 pages, 3234 KiB

Open AccessArticle

Towards a Continuous Biometric System Based on ECG Signals Acquired on the Steering Wheel

by João Ribeiro Pinto^1,*

, Jaime S. Cardoso^1,2

, André Lourenço^3,4 and Carlos Carreiras³

¹ Faculdade de Engenharia, Universidade do Porto; R. Dr. Roberto Frias, 4200-465 Porto, Portugal

² INESC-TEC; R. Dr. Roberto Frias, 4200-465 Porto, Portugal

³ CardioID Technologies Lda.; R. Adriano Correia de Oliveira 4A F1, 1600-312 Lisboa, Portugal

⁴ Instituto Superior de Engenharia de Lisboa; R. Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal

Sensors 2017, 17(10), 2228; https://doi.org/10.3390/s17102228 - 28 Sep 2017

Cited by 106 | Viewed by 8255

Abstract

Electrocardiogram signals acquired through a steering wheel could be the key to seamless, highly comfortable, and continuous human recognition in driving settings. This paper focuses on the enhancement of the unprecedented lesser quality of such signals, through the combination of Savitzky-Golay and moving [...] Read more.

Electrocardiogram signals acquired through a steering wheel could be the key to seamless, highly comfortable, and continuous human recognition in driving settings. This paper focuses on the enhancement of the unprecedented lesser quality of such signals, through the combination of Savitzky-Golay and moving average filters, followed by outlier detection and removal based on normalised cross-correlation and clustering, which was able to render ensemble heartbeats of significantly higher quality. Discrete Cosine Transform (DCT) and Haar transform features were extracted and fed to decision methods based on Support Vector Machines (SVM), k-Nearest Neighbours (kNN), Multilayer Perceptrons (MLP), and Gaussian Mixture Models - Universal Background Models (GMM-UBM) classifiers, for both identification and authentication tasks. Additional techniques of user-tuned authentication and past score weighting were also studied. The method’s performance was comparable to some of the best recent state-of-the-art methods (94.9% identification rate (IDR) and 2.66% authentication equal error rate (EER)), despite lesser results with scarce train data (70.9% IDR and 11.8% EER). It was concluded that the method was suitable for biometric recognition with driving electrocardiogram signals, and could, with future developments, be used on a continuous system in seamless and highly noisy settings. Full article

(This article belongs to the Section Biosensors)

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21 pages, 12176 KiB

Open AccessArticle

Eddy Current Testing with Giant Magnetoresistance (GMR) Sensors and a Pipe-Encircling Excitation for Evaluation of Corrosion under Insulation

by Joseph Bailey^*, Nicholas Long

and Arvid Hunze^*

Robinson Research Institute, Victoria University of Wellington, Lower Hutt 5010, New Zealand

Sensors 2017, 17(10), 2229; https://doi.org/10.3390/s17102229 - 28 Sep 2017

Cited by 36 | Viewed by 8024

Abstract

This work investigates an eddy current-based non-destructive testing (NDT) method to characterize corrosion of pipes under thermal insulation, one of the leading failure mechanisms for insulated pipe infrastructure. Artificial defects were machined into the pipe surface to simulate the effect of corrosion wall [...] Read more.

This work investigates an eddy current-based non-destructive testing (NDT) method to characterize corrosion of pipes under thermal insulation, one of the leading failure mechanisms for insulated pipe infrastructure. Artificial defects were machined into the pipe surface to simulate the effect of corrosion wall loss. We show that by using a giant magnetoresistance (GMR) sensor array and a high current (300 A), single sinusoidal low frequency (5–200 Hz) pipe-encircling excitation scheme it is possible to quantify wall loss defects without removing the insulation or weather shield. An analysis of the magnetic field distribution and induced currents was undertaken using the finite element method (FEM) and analytical calculations. Simple algorithms to remove spurious measured field variations not associated with defects were developed and applied. The influence of an aluminium weather shield with discontinuities and dents was ascertained and found to be small for excitation frequency values below 40 Hz. The signal dependence on the defect dimensions was analysed in detail. The excitation frequency at which the maximum field amplitude change occurred increased linearly with the depth of the defect by about 3 Hz/mm defect depth. The change in magnetic field amplitude due to defects for sensors aligned in the azimuthal and radial directions were measured and found to be linearly dependent on the defect volume between 4400–30,800 mm³ with 1.2 × 10⁻³−1.6 × 10⁻³ µT/mm³. The results show that our approach is well suited for measuring wall loss defects similar to the defects from corrosion under insulation. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 1384 KiB

Open AccessReview

Microbial Fuels Cell-Based Biosensor for Toxicity Detection: A Review

by Tuoyu Zhou^1,†, Huawen Han^1,†, Pu Liu², Jian Xiong³, Fake Tian³ and Xiangkai Li^1,*

¹ Ministry of Education, Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, China

² Department of Development Biology Sciences, School of Life Science, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, China

³ Wuhan Optics Valley Bluefire New Energy Co., Ltd., Three Hubei Road, Wuhan East Lake Development Zone #29, Wuhan 430205, China

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2230; https://doi.org/10.3390/s17102230 - 28 Sep 2017

Cited by 97 | Viewed by 11772

Abstract

With the unprecedented deterioration of environmental quality, rapid recognition of toxic compounds is paramount for performing in situ real-time monitoring. Although several analytical techniques based on electrochemistry or biosensors have been developed for the detection of toxic compounds, most of them are time-consuming, [...] Read more.

With the unprecedented deterioration of environmental quality, rapid recognition of toxic compounds is paramount for performing in situ real-time monitoring. Although several analytical techniques based on electrochemistry or biosensors have been developed for the detection of toxic compounds, most of them are time-consuming, inaccurate, or cumbersome for practical applications. More recently, microbial fuel cell (MFC)-based biosensors have drawn increasing interest due to their sustainability and cost-effectiveness, with applications ranging from the monitoring of anaerobic digestion process parameters (VFA) to water quality detection (e.g., COD, BOD). When a MFC runs under correct conditions, the voltage generated is correlated with the amount of a given substrate. Based on this linear relationship, several studies have demonstrated that MFC-based biosensors could detect heavy metals such as copper, chromium, or zinc, as well as organic compounds, including p-nitrophenol (PNP), formaldehyde and levofloxacin. Both bacterial consortia and single strains can be used to develop MFC-based biosensors. Biosensors with single strains show several advantages over systems integrating bacterial consortia, such as selectivity and stability. One of the limitations of such sensors is that the detection range usually exceeds the actual pollution level. Therefore, improving their sensitivity is the most important for widespread application. Nonetheless, MFC-based biosensors represent a promising approach towards single pollutant detection. Full article

(This article belongs to the Special Issue Sensors for Toxic and Pathogen Detection)

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18 pages, 3726 KiB

Open AccessArticle

Link Scheduling Algorithm with Interference Prediction for Multiple Mobile WBANs

by Thien T. T. Le and Sangman Moh^*

Department of Computer Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea

Sensors 2017, 17(10), 2231; https://doi.org/10.3390/s17102231 - 28 Sep 2017

Cited by 14 | Viewed by 3412

Abstract

As wireless body area networks (WBANs) become a key element in electronic healthcare (e-healthcare) systems, the coexistence of multiple mobile WBANs is becoming an issue. The network performance is negatively affected by the unpredictable movement of the human body. In such an environment, [...] Read more.

As wireless body area networks (WBANs) become a key element in electronic healthcare (e-healthcare) systems, the coexistence of multiple mobile WBANs is becoming an issue. The network performance is negatively affected by the unpredictable movement of the human body. In such an environment, inter-WBAN interference can be caused by the overlapping transmission range of nearby WBANs. We propose a link scheduling algorithm with interference prediction (LSIP) for multiple mobile WBANs, which allows multiple mobile WBANs to transmit at the same time without causing inter-WBAN interference. In the LSIP, a superframe includes the contention access phase using carrier sense multiple access with collision avoidance (CSMA/CA) and the scheduled phase using time division multiple access (TDMA) for non-interfering nodes and interfering nodes, respectively. For interference prediction, we define a parameter called interference duration as the duration during which disparate WBANs interfere with each other. The Bayesian model is used to estimate and classify the interference using a signal to interference plus noise ratio (SINR) and the number of neighboring WBANs. The simulation results show that the proposed LSIP algorithm improves the packet delivery ratio and throughput significantly with acceptable delay. Full article

(This article belongs to the Section Sensor Networks)

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19 pages, 8013 KiB

Open AccessArticle

An Efficient Hardware Circuit for Spike Sorting Based on Competitive Learning Networks

by Huan-Yuan Chen^†, Chih-Chang Chen^† and Wen-Jyi Hwang^*,†

¹ Department of Computer Science and Information Engineering, National Taiwan Normal University, Taipei 116, Taiwan

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2232; https://doi.org/10.3390/s17102232 - 28 Sep 2017

Cited by 6 | Viewed by 6064

Abstract

This study aims to present an effective VLSI circuit for multi-channel spike sorting. The circuit supports the spike detection, feature extraction and classification operations. The detection circuit is implemented in accordance with the nonlinear energy operator algorithm. Both the peak detection and area [...] Read more.

This study aims to present an effective VLSI circuit for multi-channel spike sorting. The circuit supports the spike detection, feature extraction and classification operations. The detection circuit is implemented in accordance with the nonlinear energy operator algorithm. Both the peak detection and area computation operations are adopted for the realization of the hardware architecture for feature extraction. The resulting feature vectors are classified by a circuit for competitive learning (CL) neural networks. The CL circuit supports both online training and classification. In the proposed architecture, all the channels share the same detection, feature extraction, learning and classification circuits for a low area cost hardware implementation. The clock-gating technique is also employed for reducing the power dissipation. To evaluate the performance of the architecture, an application-specific integrated circuit (ASIC) implementation is presented. Experimental results demonstrate that the proposed circuit exhibits the advantages of a low chip area, a low power dissipation and a high classification success rate for spike sorting. Full article

(This article belongs to the Special Issue Advanced Electronic Devices, Circuits, and Signal Processing for Biomedical Sensors Application)

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19 pages, 5281 KiB

Open AccessArticle

A Nonlinearity Mitigation Method for a Broadband RF Front-End in a Sensor Based on Best Delay Searching

by Wen Zhao¹, Hong Ma¹, Hua Zhang^1,*, Jiang Jin¹, Gang Dai² and Lin Hu¹

¹ School of Electronic Information and Communications, Huazhong University of Science & Technology, 1037 Luoyu Road, Wuhan 430074, China

² Hubei Province Radio Monitoring Station, 15 Fayuan Road,Wuhan 430061, China

Sensors 2017, 17(10), 2233; https://doi.org/10.3390/s17102233 - 28 Sep 2017

Cited by 3 | Viewed by 4470

Abstract

The cognitive radio wireless sensor network (CR-WSN) is experiencing more and more attention for its capacity to automatically extract broadband instantaneous radio environment information. Obtaining sufficient linearity and spurious-free dynamic range (SFDR) is a significant premise of guaranteeing sensing performance which, however, usually [...] Read more.

The cognitive radio wireless sensor network (CR-WSN) is experiencing more and more attention for its capacity to automatically extract broadband instantaneous radio environment information. Obtaining sufficient linearity and spurious-free dynamic range (SFDR) is a significant premise of guaranteeing sensing performance which, however, usually suffers from the nonlinear distortion coming from the broadband radio frequency (RF) front-end in the sensor node. Moreover, unlike other existing methods, the joint effect of non-constant group delay distortion and nonlinear distortion is discussed, and its corresponding solution is provided in this paper. After that, the nonlinearity mitigation architecture based on best delay searching is proposed. Finally, verification experiments, both on simulation signals and signals from real-world measurement, are conducted and discussed. The achieved results demonstrate that with best delay searching, nonlinear distortion can be alleviated significantly and, in this way, spectrum sensing performance is more reliable and accurate. Full article

(This article belongs to the Special Issue Recent Advances in Front-End Designs for Sensors and Wireless Networks)

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22 pages, 3853 KiB

Open AccessArticle

Detection of Nuclear Sources by UAV Teleoperation Using a Visuo-Haptic Augmented Reality Interface

by Jacopo Aleotti¹, Giorgio Micconi¹, Stefano Caselli¹, Giacomo Benassi², Nicola Zambelli², Manuele Bettelli³ and Andrea Zappettini^3,*

¹ Department of Engineering and Architecture, University of Parma, 43124 Parma, Italy

² due2lab s.r.l., 43121 Parma, Italy

³ IMEM-CNR, 43124 Parma, Italy

Sensors 2017, 17(10), 2234; https://doi.org/10.3390/s17102234 - 29 Sep 2017

Cited by 68 | Viewed by 8044

Abstract

A visuo-haptic augmented reality (VHAR) interface is presented enabling an operator to teleoperate an unmanned aerial vehicle (UAV) equipped with a custom CdZnTe-based spectroscopic gamma-ray detector in outdoor environments. The task is to localize nuclear radiation sources, whose location is unknown to the [...] Read more.

A visuo-haptic augmented reality (VHAR) interface is presented enabling an operator to teleoperate an unmanned aerial vehicle (UAV) equipped with a custom CdZnTe-based spectroscopic gamma-ray detector in outdoor environments. The task is to localize nuclear radiation sources, whose location is unknown to the user, without the close exposure of the operator. The developed detector also enables identification of the localized nuclear sources. The aim of the VHAR interface is to increase the situation awareness of the operator. The user teleoperates the UAV using a 3DOF haptic device that provides an attractive force feedback around the location of the most intense detected radiation source. Moreover, a fixed camera on the ground observes the environment where the UAV is flying. A 3D augmented reality scene is displayed on a computer screen accessible to the operator. Multiple types of graphical overlays are shown, including sensor data acquired by the nuclear radiation detector, a virtual cursor that tracks the UAV and geographical information, such as buildings. Experiments performed in a real environment are reported using an intense nuclear source. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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16 pages, 5474 KiB

Open AccessArticle

Object Classification in Semi Structured Enviroment Using Forward-Looking Sonar

by Matheus Dos Santos^1,*, Pedro Otávio Ribeiro¹

, Pedro Núñez², Paulo Drews-Jr¹ and Silvia Botelho¹

¹ NAUTEC-Intelligent Robotics and Automation Group-Center for Computer Science, Universidade Federal do Rio Grande, Rio Grande 96203-900, Brazil

² ROBOLAB - Robotics Laboratory, Department of Computer and Communication Technology, Universidad de Extremadura, Cáceres, Extremadura 1003, Spain

Sensors 2017, 17(10), 2235; https://doi.org/10.3390/s17102235 - 29 Sep 2017

Cited by 26 | Viewed by 6526

Abstract

The submarine exploration using robots has been increasing in recent years. The automation of tasks such as monitoring, inspection, and underwater maintenance requires the understanding of the robot’s environment. The object recognition in the scene is becoming a critical issue for these systems. [...] Read more.

The submarine exploration using robots has been increasing in recent years. The automation of tasks such as monitoring, inspection, and underwater maintenance requires the understanding of the robot’s environment. The object recognition in the scene is becoming a critical issue for these systems. On this work, an underwater object classification pipeline applied in acoustic images acquired by Forward-Looking Sonar (FLS) are studied. The object segmentation combines thresholding, connected pixels searching and peak of intensity analyzing techniques. The object descriptor extract intensity and geometric features of the detected objects. A comparison between the Support Vector Machine, K-Nearest Neighbors, and Random Trees classifiers are presented. An open-source tool was developed to annotate and classify the objects and evaluate their classification performance. The proposed method efficiently segments and classifies the structures in the scene using a real dataset acquired by an underwater vehicle in a harbor area. Experimental results demonstrate the robustness and accuracy of the method described in this paper. Full article

(This article belongs to the Special Issue Advances and Challenges in Underwater Sensor Networks)

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16 pages, 16009 KiB

Open AccessArticle

Evaluating Degradation at Railway Crossings Using Axle Box Acceleration Measurements

by Zilong Wei, Alfredo Núñez

, Zili Li^* and Rolf Dollevoet

Section of Railway Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CD Delft, The Netherlands

Sensors 2017, 17(10), 2236; https://doi.org/10.3390/s17102236 - 29 Sep 2017

Cited by 58 | Viewed by 9455

Abstract

In this paper, we investigate the capability of an axle box acceleration (ABA) system to evaluate the degradation at railway crossings. For this purpose, information from multiple sensors, namely, ABA signals, 3D rail profiles, Global Positioning System (GPS) and tachometer recordings, was collected [...] Read more.

In this paper, we investigate the capability of an axle box acceleration (ABA) system to evaluate the degradation at railway crossings. For this purpose, information from multiple sensors, namely, ABA signals, 3D rail profiles, Global Positioning System (GPS) and tachometer recordings, was collected from both nominal and degraded crossings. By proper correlation of the gathered data, an algorithm was proposed to distinguish the characteristic ABA related to the degradation and then to evaluate the health condition of crossings. The algorithm was then demonstrated on a crossing with an unknown degradation status, and its capability was verified via a 3D profile measurement. The results indicate that the ABA system is effective at monitoring two types of degradations. The first type is uneven deformation between the wing rail and crossing nose, corresponding to characteristic ABA frequencies of 230–350 and 460–650 Hz. The second type is local irregularity in the longitudinal slope of the crossing nose, corresponding to characteristic ABA frequencies of 460–650 Hz. The types and severity of the degradation can be evaluated by the spatial distribution and energy concentration of the characteristic frequencies of the ABA signals. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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21 pages, 7105 KiB

Open AccessArticle

Improving the Accuracy of Direct Geo-referencing of Smartphone-Based Mobile Mapping Systems Using Relative Orientation and Scene Geometric Constraints

by Naif M. Alsubaie^*, Ahmed A. Youssef and Naser El-Sheimy

Geomatics Engineering Department, University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(10), 2237; https://doi.org/10.3390/s17102237 - 30 Sep 2017

Cited by 25 | Viewed by 5833

Abstract

This paper introduces a new method which facilitate the use of smartphones as a handheld low-cost mobile mapping system (MMS). Smartphones are becoming more sophisticated and smarter and are quickly closing the gap between computers and portable tablet devices. The current generation of [...] Read more.

This paper introduces a new method which facilitate the use of smartphones as a handheld low-cost mobile mapping system (MMS). Smartphones are becoming more sophisticated and smarter and are quickly closing the gap between computers and portable tablet devices. The current generation of smartphones are equipped with low-cost GPS receivers, high-resolution digital cameras, and micro-electro mechanical systems (MEMS)-based navigation sensors (e.g., accelerometers, gyroscopes, magnetic compasses, and barometers). These sensors are in fact the essential components for a MMS. However, smartphone navigation sensors suffer from the poor accuracy of global navigation satellite System (GNSS), accumulated drift, and high signal noise. These issues affect the accuracy of the initial Exterior Orientation Parameters (EOPs) that are inputted into the bundle adjustment algorithm, which then produces inaccurate 3D mapping solutions. This paper proposes new methodologies for increasing the accuracy of direct geo-referencing of smartphones using relative orientation and smartphone motion sensor measurements as well as integrating geometric scene constraints into free network bundle adjustment. The new methodologies incorporate fusing the relative orientations of the captured images and their corresponding motion sensor measurements to improve the initial EOPs. Then, the geometric features (e.g., horizontal and vertical linear lines) visible in each image are extracted and used as constraints in the bundle adjustment procedure which correct the relative position and orientation of the 3D mapping solution. Full article

(This article belongs to the Special Issue Multi-Sensor Integration and Fusion)

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20 pages, 12290 KiB

Open AccessArticle

Error Modeling and Experimental Study of a Flexible Joint 6-UPUR Parallel Six-Axis Force Sensor

by Yanzhi Zhao^1,2,*, Yachao Cao^1,2, Caifeng Zhang^1,2, Dan Zhang³ and Jie Zhang⁴

¹ Key Laboratory of Parallel Robot and Mechatronic System of Hebei Province, Yanshan University, Qinhuangdao 066004, China

² Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education of China, Yanshan University, Qinhuangdao 066004, China

³ Department of Mechanical Engineering, Lassonde School of Engineering, York University, 4700 Keele Street, Toronto, ON M3J1P3, Canada

⁴ Department of Basic Teaching, LiRen College of Yanshan University, Qinhuangdao 066004, Hebei, China

Sensors 2017, 17(10), 2238; https://doi.org/10.3390/s17102238 - 29 Sep 2017

Cited by 12 | Viewed by 5253

Abstract

By combining a parallel mechanism with integrated flexible joints, a large measurement range and high accuracy sensor is realized. However, the main errors of the sensor involve not only assembly errors, but also deformation errors of its flexible leg. Based on a flexible [...] Read more.

By combining a parallel mechanism with integrated flexible joints, a large measurement range and high accuracy sensor is realized. However, the main errors of the sensor involve not only assembly errors, but also deformation errors of its flexible leg. Based on a flexible joint 6-UPUR (a kind of mechanism configuration where U-universal joint, P-prismatic joint, R-revolute joint) parallel six-axis force sensor developed during the prephase, assembly and deformation error modeling and analysis of the resulting sensors with a large measurement range and high accuracy are made in this paper. First, an assembly error model is established based on the imaginary kinematic joint method and the Denavit-Hartenberg (D-H) method. Next, a stiffness model is built to solve the stiffness matrix. The deformation error model of the sensor is obtained. Then, the first order kinematic influence coefficient matrix when the synthetic error is taken into account is solved. Finally, measurement and calibration experiments of the sensor composed of the hardware and software system are performed. Forced deformation of the force-measuring platform is detected by using laser interferometry and analyzed to verify the correctness of the synthetic error model. In addition, the first order kinematic influence coefficient matrix in actual circumstances is calculated. By comparing the condition numbers and square norms of the coefficient matrices, the conclusion is drawn theoretically that it is very important to take into account the synthetic error for design stage of the sensor and helpful to improve performance of the sensor in order to meet needs of actual working environments. Full article

(This article belongs to the Special Issue Flexible Electronics and Sensors)

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14 pages, 6804 KiB

Open AccessArticle

Finite Element Analysis of Grouting Compactness Monitoring in a Post-Tensioning Tendon Duct Using Piezoceramic Transducers

by Tianyong Jiang¹

, Junbo Zheng¹

, Linsheng Huo²

and Gangbing Song^2,3,*

¹ School of Civil Engineering, Changsha University of Science and Technology, Changsha 410114, China

² School of Civil Engineering, Dalian University of Technology, Dalian 116024, China

³ Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA

Sensors 2017, 17(10), 2239; https://doi.org/10.3390/s17102239 - 29 Sep 2017

Cited by 25 | Viewed by 4860

Abstract

With the development of the post-tensioning technique, prestressed concrete structures have been widely used in civil engineering. To ensure the long-term effectiveness of the prestressed tendon, the grouting quality of the tendon duct is one of the important factors. However, it is still [...] Read more.

With the development of the post-tensioning technique, prestressed concrete structures have been widely used in civil engineering. To ensure the long-term effectiveness of the prestressed tendon, the grouting quality of the tendon duct is one of the important factors. However, it is still a challenge to monitor the grouting quality of post-tensioning tendon ducts, due to the invisibility of the grouting. The authors’ previous work proposed a real-time method that employed a stress wave-based active sensing approach with piezoceramic transducers to monitor the grouting compactness of a Post-Tensioning Tendon Duct (PTTD). To further understand the piezoceramic induced stress wave propagation in the PTTD with different grouting levels, this paper develops a two-dimensional finite element model for monitoring the grouting compactness of the tendon duct with a piezoceramic transducer. A smart aggregate (SA) developed to utilize one Lead Zirconate Titanate (PZT) transducer with marble protection is installed in the center location of the tendon duct as an actuator. Two PZT patches are bonded on the bottom and top surface of the tendon duct as the sensors. The analysis results show that the finite element analysis results are in good agreement with the experimental results, which demonstrates that the finite element analysis is feasible and reliable. For the top half of the specimen, not much stress wave could be detected before the full grouting level, except for negligible signals that may propagate through the walls of the tendon duct. When the tendon duct grouting is at 100%, the stress wave propagates to the top of the specimen, and the displacements are symmetric in both left-right and top-bottom directions before the stress waves reach the boundary. The proposed two-dimensional finite element model has the potential to be implemented to simulate the stress wave propagation principle for monitoring grouting compaction of the post-tensioning tendon duct. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 1200 KiB

Open AccessArticle

Improved Numerical Calculation of the Single-Mode-No-Core-Single-Mode Fiber Structure Using the Fields Far from Cutoff Approximation

by Wei Xu^1,2,3,†

, Jia Shi^1,2,†

, Xianchao Yang^1,2, Degang Xu^1,2

, Feng Rong³, Junfa Zhao³ and Jianquan Yao^1,2,*

¹ Institute of Laser and Optoelectronics, College of Precision Instrument and Optoelectronic Engineering, Tianjin University, Tianjin 300072, China

² Key Laboratory of Optoelectronic Information Science and Technology (Ministry of Education), Tianjin University, Tianjin 300072, China

³ Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin Polytechnic University, Tianjin 300387, China

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2240; https://doi.org/10.3390/s17102240 - 29 Sep 2017

Cited by 25 | Viewed by 4422

Abstract

Multimode interferometers based on the single-mode-no-core-single-mode fiber (SNCS) structure have been widely investigated as functional devices and sensors. However, the theoretical support for the sensing mechanism is still imperfect, especially for the cladding refractive index response. In this paper, a modified model of [...] Read more.

Multimode interferometers based on the single-mode-no-core-single-mode fiber (SNCS) structure have been widely investigated as functional devices and sensors. However, the theoretical support for the sensing mechanism is still imperfect, especially for the cladding refractive index response. In this paper, a modified model of no-core fiber (NCF) based on far from cut-off approximation is proposed to investigate the spectrum characteristic and sensing mechanism of the SNCS structure. Guided-mode propagation analysis (MPA) is used to analyze the self-image effect and spectrum response to the cladding refractive index and temperature. Verified by experiments, the performance of the SNCS structure can be estimated specifically and easily by the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 2524 KiB

Open AccessArticle

Real-Valued 2D MUSIC Algorithm Based on Modified Forward/Backward Averaging Using an Arbitrary Centrosymmetric Polarization Sensitive Array

by Weijian Si¹, Yan Wang¹, Changbo Hou^1,* and Hong Wang²

¹ College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China

² Beijing Institute of Computer Technology and Application, Beijing 100854, China

Sensors 2017, 17(10), 2241; https://doi.org/10.3390/s17102241 - 29 Sep 2017

Cited by 12 | Viewed by 4687

Abstract

Two-dimensional multiple signal classification (MUSIC) algorithm based on polarization sensitive array (PSA) has excellent performance. However, it suffers a high computational complexity due to a multitude of complex operations. In this paper, we propose a real-valued two-dimensional MUSIC algorithm based on conjugate centrosymmetric [...] Read more.

Two-dimensional multiple signal classification (MUSIC) algorithm based on polarization sensitive array (PSA) has excellent performance. However, it suffers a high computational complexity due to a multitude of complex operations. In this paper, we propose a real-valued two-dimensional MUSIC algorithm based on conjugate centrosymmetric signal model, which is applicable to arbitrary centrosymmetric polarization sensitive array. The modified forward/backward averaging, which can be applied to the PSA, is presented. Hence, the eigen-decomposition analysis process and spectrum function computation are converted into real domain, prominently reducing the computational complexity. Then, the direction-of-arrival (DOA) estimation is decoupled from the polarization parameter estimation so that the four-dimensional spectral peak search process is avoided. The theoretical computational complexity is discussed and the Cramer-Rao bound (CRB) of DOA estimation is derived in this paper. The simulation results indicate that the proposed algorithm achieves superior accuracy in DOA estimation and has low computational complexity. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 896 KiB

Open AccessArticle

Robust Small Target Co-Detection from Airborne Infrared Image Sequences

by Jingli Gao^1,3

, Chenglin Wen^2,* and Meiqin Liu¹

¹ College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China

² School of Automation, Hangzhou Dianzi University, Hangzhou 310018, China

³ College of Software Engineering, Pingdingshan University, Pingdingshan 467000, China

Sensors 2017, 17(10), 2242; https://doi.org/10.3390/s17102242 - 29 Sep 2017

Cited by 23 | Viewed by 5257

Abstract

In this paper, a novel infrared target co-detection model combining the self-correlation features of backgrounds and the commonality features of targets in the spatio-temporal domain is proposed to detect small targets in a sequence of infrared images with complex backgrounds. Firstly, a dense [...] Read more.

In this paper, a novel infrared target co-detection model combining the self-correlation features of backgrounds and the commonality features of targets in the spatio-temporal domain is proposed to detect small targets in a sequence of infrared images with complex backgrounds. Firstly, a dense target extraction model based on nonlinear weights is proposed, which can better suppress background of images and enhance small targets than weights of singular values. Secondly, a sparse target extraction model based on entry-wise weighted robust principal component analysis is proposed. The entry-wise weight adaptively incorporates structural prior in terms of local weighted entropy, thus, it can extract real targets accurately and suppress background clutters efficiently. Finally, the commonality of targets in the spatio-temporal domain are used to construct target refinement model for false alarms suppression and target confirmation. Since real targets could appear in both of the dense and sparse reconstruction maps of a single frame, and form trajectories after tracklet association of consecutive frames, the location correlation of the dense and sparse reconstruction maps for a single frame and tracklet association of the location correlation maps for successive frames have strong ability to discriminate between small targets and background clutters. Experimental results demonstrate that the proposed small target co-detection method can not only suppress background clutters effectively, but also detect targets accurately even if with target-like interference. Full article

(This article belongs to the Special Issue Video Analysis and Tracking Using State-of-the-Art Sensors)

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12 pages, 1874 KiB

Open AccessArticle

A Novel Online Data-Driven Algorithm for Detecting UAV Navigation Sensor Faults

by Rui Sun^1,*

, Qi Cheng¹, Guanyu Wang¹ and Washington Yotto Ochieng^1,2

¹ College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China

² Centre for Transport Studies, Imperial College London, London SW7 2AZ, UK

Sensors 2017, 17(10), 2243; https://doi.org/10.3390/s17102243 - 29 Sep 2017

Cited by 81 | Viewed by 6651

Abstract

The use of Unmanned Aerial Vehicles (UAVs) has increased significantly in recent years. On-board integrated navigation sensors are a key component of UAVs’ flight control systems and are essential for flight safety. In order to ensure flight safety, timely and effective navigation sensor [...] Read more.

The use of Unmanned Aerial Vehicles (UAVs) has increased significantly in recent years. On-board integrated navigation sensors are a key component of UAVs’ flight control systems and are essential for flight safety. In order to ensure flight safety, timely and effective navigation sensor fault detection capability is required. In this paper, a novel data-driven Adaptive Neuron Fuzzy Inference System (ANFIS)-based approach is presented for the detection of on-board navigation sensor faults in UAVs. Contrary to the classic UAV sensor fault detection algorithms, based on predefined or modelled faults, the proposed algorithm combines an online data training mechanism with the ANFIS-based decision system. The main advantages of this algorithm are that it allows real-time model-free residual analysis from Kalman Filter (KF) estimates and the ANFIS to build a reliable fault detection system. In addition, it allows fast and accurate detection of faults, which makes it suitable for real-time applications. Experimental results have demonstrated the effectiveness of the proposed fault detection method in terms of accuracy and misdetection rate. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 8514 KiB

Open AccessArticle

3D Power Line Extraction from Multiple Aerial Images

by Jaehong Oh¹

and Changno Lee^2,*

¹ Department of Civil Engineering, Chonnam National University, Gwangju 61186, Korea

² Department of Civil Engineering, Seoul National University of Science and Technology, Seoul 01811, Korea

Sensors 2017, 17(10), 2244; https://doi.org/10.3390/s17102244 - 29 Sep 2017

Cited by 23 | Viewed by 5932

Abstract

Power lines are cables that carry electrical power from a power plant to an electrical substation. They must be connected between the tower structures in such a way that ensures minimum tension and sufficient clearance from the ground. Power lines can stretch and [...] Read more.

Power lines are cables that carry electrical power from a power plant to an electrical substation. They must be connected between the tower structures in such a way that ensures minimum tension and sufficient clearance from the ground. Power lines can stretch and sag with the changing weather, eventually exceeding the planned tolerances. The excessive sags can then cause serious accidents, while hindering the durability of the power lines. We used photogrammetric techniques with a low-cost drone to achieve efficient 3D mapping of power lines that are often difficult to approach. Unlike the conventional image-to-object space approach, we used the object-to-image space approach using cubic grid points. We processed four strips of aerial images to automatically extract the power line points in the object space. Experimental results showed that the approach could successfully extract the positions of the power line points for power line generation and sag measurement with the elevation accuracy of a few centimeters. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 1696 KiB

Open AccessArticle

Ultrathin Tungsten Oxide Nanowires/Reduced Graphene Oxide Composites for Toluene Sensing

by Muhammad Hassan¹, Zhi-Hua Wang¹, Wei-Ran Huang¹, Min-Qiang Li², Jian-Wei Liu^1,*

and Jia-Fu Chen^1,*

¹ Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, 230026 Hefei, China

² Nanomaterials & Environment Detection Laboratory, Institute of Intelligent Machines, Chinese Academy of Sciences, 230031 Hefei, China

Sensors 2017, 17(10), 2245; https://doi.org/10.3390/s17102245 - 29 Sep 2017

Cited by 19 | Viewed by 6550

Abstract

Graphene-based composites have gained great attention in the field of gas sensor fabrication due to their higher surface area with additional functional groups. Decorating one-dimensional (1D) semiconductor nanomaterials on graphene also show potential benefits in gas sensing applications. Here we demonstrate the one-pot [...] Read more.

Graphene-based composites have gained great attention in the field of gas sensor fabrication due to their higher surface area with additional functional groups. Decorating one-dimensional (1D) semiconductor nanomaterials on graphene also show potential benefits in gas sensing applications. Here we demonstrate the one-pot and low cost synthesis of W₁₈O₄₉ NWs/rGO composites with different amount of reduced graphene oxide (rGO) which show excellent gas-sensing properties towards toluene and strong dependence on their chemical composition. As compared to pure W₁₈O₄₉ NWs, an improved gas sensing response (2.8 times higher) was achieved in case of W₁₈O₄₉ NWs composite with 0.5 wt. % rGO. Promisingly, this strategy can be extended to prepare other nanowire based composites with excellent gas-sensing performance. Full article

(This article belongs to the Special Issue Advanced Sensors Based on Carbon Electrodes)

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11 pages, 3796 KiB

Open AccessArticle

A Light-Up Probe for Detection of Adenosine in Urine Samples by a Combination of an AIE Molecule and an Aptamer

by Yingying Hu^1,†, Jingjing Liu^1,†, Xiangyu You¹, Can Wang², Zhen Li² and Weihong Xie^1,*

¹ Department of Food and Pharmaceutical Engineering, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China

² Department of Chemistry, Wuhan University, Wuhan 430072, China

^† Yingying Hu and Jingjing Liu contributed equally to this work.

Sensors 2017, 17(10), 2246; https://doi.org/10.3390/s17102246 - 29 Sep 2017

Cited by 11 | Viewed by 5549

Abstract

A light-up fluorescent probe for the detection of adenosine was constructed with an AIE (aggregation-induced emission) molecule and a DNA aptamer. The AIE molecule was used as a signal generator, and the DNA aptamer was used as a recognition element for adenosine. The [...] Read more.

A light-up fluorescent probe for the detection of adenosine was constructed with an AIE (aggregation-induced emission) molecule and a DNA aptamer. The AIE molecule was used as a signal generator, and the DNA aptamer was used as a recognition element for adenosine. The emission of the AIE molecule was due to its intramolecular rotation restriction induced by the aptamer upon binding of adenosine. The optimal component ratio of the probe was AIE molecule / DNA aptamer = 100 (μM/μM). The calibration curve of adenosine detection showed a linear range of 10 pM to 0.5 μM with an R² of 0.996, and the detection limit of the probe was 10 pM. The probe exhibited a good selectivity to adenosine against its analogs (uridine, guanosine, and cytidine). The probe was used to detect adenosine in urine samples, a recovery from 86.8% to 90.0% for the spiked concentrations of adenosine (0.01, 0.05, 0.1 μM). The relative standard deviation from 1.2% to 2.0% was obtained. The intra-day and inter-day tests also showed good precisions, with measurement RSD values of 2.3% and 2.1%, respectively. Full article

(This article belongs to the Special Issue Fluorescent Probes and Sensors)

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15 pages, 5821 KiB

Open AccessArticle

The Development of an RFID Solution to Facilitate the Traceability of Patient and Pharmaceutical Data

by María Martínez Pérez^1,*

, Guillermo Vázquez González² and Carlos Dafonte¹

¹ Department of Information and Communications Technologies, Faculty of Computer Science, Campus Elviña S/N, University of A Coruña, E-15071 A Coruña, Spain

² Complejo Hospitalario Universitario de A Coruña (CHUAC), 15006 A Coruña, Spain

Sensors 2017, 17(10), 2247; https://doi.org/10.3390/s17102247 - 29 Sep 2017

Cited by 16 | Viewed by 6679

Abstract

One of the principal objectives of hospitals is to increase the quality of care of the patient. This is even more of a priority in Day Hospitals where certain medication requires special attention, from its preparation in the Pharmacy service to its delivery [...] Read more.

One of the principal objectives of hospitals is to increase the quality of care of the patient. This is even more of a priority in Day Hospitals where certain medication requires special attention, from its preparation in the Pharmacy service to its delivery to the patient in the Day Hospital. In the case of expensive medicines, nursing staff have to comply with very detailed instructions in their administration to the patient (name of medicine, route, dosage, schedule, previous medication, conditions of conservation, etc.). This work focuses on the development of a multi-faceted hub application to facilitate the traceability of mixed intravenous medication from the beginning to the end of the process of prescription–validation–dosing–preparation–administration (PVD-PA) and be available to all health professionals involved: doctors, pharmacists, and the nursing staff of the Hospital Pharmacy and Day Hospital. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI 2016)

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23 pages, 21762 KiB

Open AccessArticle

Testing of the 4SM Method in the Gulf of California Suggests Field Data Are not Needed to Derive Satellite Bathymetry

by Fabio Favoretto^1,5

, Yann Morel², Andrew Waddington³, Jorge Lopez-Calderon⁴, Marco Cadena-Roa⁵ and Anidia Blanco-Jarvio^5,*

¹ Posgrado en Ciencias Marinas y Costeras (CIMACO), Universidad Autónoma de Baja California Sur, 23060 La Paz, Baja California Sur, Mexico

² Retired, BP 2862 98703 Puanaauia, French Polynesia

³ AW Hydrographic, 35 Burge Meadow, Cotford St. Luke, Taunton Somerset TA4 1QN, UK

⁴ Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, , Carretera Tijuana-Ensenada 2917, Col. Playitas, C.P. 22860 Ensenada B.C., Mexico

⁵ Programa de Bioingeniería y Ciencias Ambientales, Departamento Académico de Ingeniería en Pesquerías, Universidad Autónoma de Baja California Sur, Unidad Pichilingue, 23060 La Paz, Baja California Sur, Mexico

Sensors 2017, 17(10), 2248; https://doi.org/10.3390/s17102248 - 30 Sep 2017

Cited by 10 | Viewed by 6961

Abstract

Satellite-derived bathymetry methods over coastal areas were developed to deliver basic and useful bathymetry information. However, the process is not straightforward, the main limitation being the need for field data. The Self-calibrated Spectral Supervised Shallow-water Modeler (4SM) method was tested to obtain coastal [...] Read more.

Satellite-derived bathymetry methods over coastal areas were developed to deliver basic and useful bathymetry information. However, the process is not straightforward, the main limitation being the need for field data. The Self-calibrated Spectral Supervised Shallow-water Modeler (4SM) method was tested to obtain coastal bathymetry without the use of any field data. Using Landsat-8 multispectral images from 2013 to 2016, a bathymetric time series was produced. Groundtruthed depths and an alternative method, Stumpf’s Band Ratio Algorithm, were used to verify the results. Retrieved (4SM) vs groundtruthed depths scored an average r² (0.90), and a low error (RMSE = 1.47 m). 4SM also showed, over the whole time series, the same average accuracy of the control method (40%). Advantages, limitations and operability under complex atmosphere and water column conditions, and high and low-albedo bottom processing capabilities of 4SM are discussed. In conclusion, the findings suggest that 4SM is as accurate as the commonly used Stumpf’s method, the only difference being the independence of 4SM from previous field data, and the potential to deliver bottom spectral characteristics for further modeling. 4SM thus represents a significant advance in coastal remote sensing potential to obtain bathymetry and optical properties of the marine bottom. Full article

(This article belongs to the Section Physical Sensors)

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8 pages, 1077 KiB

Open AccessFeature PaperCommunication

Rational Design of Peptide-Functionalized Surface Plasmon Resonance Sensor for Specific Detection of TNT Explosive

by Jin Wang^1,*, Masaki Muto², Rui Yatabe¹, Takeshi Onodera³, Masayoshi Tanaka²

, Mina Okochi² and Kiyoshi Toko^1,3

¹ Research and Development Center for Taste and Odor Sensing, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan

² Department of Chemical Science and Engineering, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552, Japan

³ Department of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan

Sensors 2017, 17(10), 2249; https://doi.org/10.3390/s17102249 - 30 Sep 2017

Cited by 19 | Viewed by 6589

Abstract

In this study, a rationally-designed 2,4,6-trinitrotoluene (TNT) binding peptide derived from an amino acid sequence of the complementarity-determining region (CDR) of an anti-TNT monoclonal antibody was used for TNT detection based on a maleimide-functionalized surface plasmon resonance (SPR) sensor. By antigen-docking simulation and [...] Read more.

In this study, a rationally-designed 2,4,6-trinitrotoluene (TNT) binding peptide derived from an amino acid sequence of the complementarity-determining region (CDR) of an anti-TNT monoclonal antibody was used for TNT detection based on a maleimide-functionalized surface plasmon resonance (SPR) sensor. By antigen-docking simulation and screening, the TNT binding candidate peptides were obtained as TNTHCDR1 derived from the heavy chain of CDR1, TNTHCDR2 derived from CDR2, and TNTHCDR3 from CDR3 of an anti-TNT antibody. The binding events between candidate peptides and TNT were evaluated using the SPR sensor by direct determination based on the 3-aminopropyltriethoxysilane (APTES) surface. The TNT binding peptide was directly immobilized on the maleimide-functionalized sensor chip surface from N-γ-maleimidobutyryl-oxysuccinimide ester (GMBS). The results demonstrated that peptide TNTHCDR3 was identified and selected as a TNT binding peptide among the other two candidate peptides. Five kinds of TNT analogues were also investigated to testify the selectivity of TNT binding peptide TNTHCDR3. Furthermore, the results indicated that the APTES-GMBS-based SPR sensor chip procedure featured a great potential application for the direct detection of TNT. Full article

(This article belongs to the Special Issue Electronic Tongues and Electronic Noses)

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10 pages, 2199 KiB

Open AccessArticle

Experimental and Numerical Investigations in Shallow Cut Grinding by Workpiece Integrated Infrared Thermopile Array

by Marcel Reimers^†, Walter Lang^† and Gerrit Dumstorff^*,†

¹ Institute for Microsensors, -Actuators and -Systems (IMSAS), Microsystems Center Bremen (MCB), University of Bremen, 28359 Bremen, Germany

^† Current address: Otto-Hahn-Allee 1, 28359 Bremen, Germany.

Sensors 2017, 17(10), 2250; https://doi.org/10.3390/s17102250 - 30 Sep 2017

Cited by 3 | Viewed by 4144

Abstract

The purpose of our study is to investigate the heat distribution and the occurring temperatures during grinding. Therefore, we did both experimental and numerical investigations. In the first part, we present the integration of an infrared thermopile array in a steel workpiece. Experiments [...] Read more.

The purpose of our study is to investigate the heat distribution and the occurring temperatures during grinding. Therefore, we did both experimental and numerical investigations. In the first part, we present the integration of an infrared thermopile array in a steel workpiece. Experiments are done by acquiring data from the thermopile array during grinding of a groove in a workpiece made of steel. In the second part, we present numerical investigations in the grinding process to further understand the thermal characteristic during grinding. Finally, we conclude our work. Increasing the feed speed leads to two things: higher heat flux densities in the workpiece and higher temperature gradients in the material. Full article

(This article belongs to the Section Physical Sensors)

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30 pages, 764 KiB

Open AccessArticle

An Energy Scaled and Expanded Vector-Based Forwarding Scheme for Industrial Underwater Acoustic Sensor Networks with Sink Mobility

by Zahid Wadud^1,2, Sajjad Hussain³, Nadeem Javaid^4,*

, Safdar Hussain Bouk⁵, Nabil Alrajeh^6,*, Mohamad Souheil Alabed⁶ and Nadra Guizani⁷

¹ Capital University of Science and Technology, Islamabad 44000, Pakistan

² University of Engineering and Technology, Peshawar 25000, Pakistan

³ School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK

⁴ COMSATS Institute of Information Technology, Islamabad 44000, Pakistan

⁵ Department of Information and Communication Engineering, DGIST 42988, Korea

⁶ Biomedical Technology Department College of Applied Medical Sciences, King Saud University, Riyadh 11633, Saudi Arabia

⁷ Department of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA

Sensors 2017, 17(10), 2251; https://doi.org/10.3390/s17102251 - 30 Sep 2017

Cited by 12 | Viewed by 6257

Abstract

Industrial Underwater Acoustic Sensor Networks (IUASNs) come with intrinsic challenges like long propagation delay, small bandwidth, large energy consumption, three-dimensional deployment, and high deployment and battery replacement cost. Any routing strategy proposed for IUASN must take into account these constraints. The vector based [...] Read more.

Industrial Underwater Acoustic Sensor Networks (IUASNs) come with intrinsic challenges like long propagation delay, small bandwidth, large energy consumption, three-dimensional deployment, and high deployment and battery replacement cost. Any routing strategy proposed for IUASN must take into account these constraints. The vector based forwarding schemes in literature forward data packets to sink using holding time and location information of the sender, forwarder, and sink nodes. Holding time suppresses data broadcasts; however, it fails to keep energy and delay fairness in the network. To achieve this, we propose an Energy Scaled and Expanded Vector-Based Forwarding (ESEVBF) scheme. ESEVBF uses the residual energy of the node to scale and vector pipeline distance ratio to expand the holding time. Resulting scaled and expanded holding time of all forwarding nodes has a significant difference to avoid multiple forwarding, which reduces energy consumption and energy balancing in the network. If a node has a minimum holding time among its neighbors, it shrinks the holding time and quickly forwards the data packets upstream. The performance of ESEVBF is analyzed through in network scenario with and without node mobility to ensure its effectiveness. Simulation results show that ESEVBF has low energy consumption, reduces forwarded data copies, and less end-to-end delay. Full article

(This article belongs to the Collection Smart Industrial Wireless Sensor Networks)

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14 pages, 6766 KiB

Open AccessArticle

Hyperspectral Imaging Analysis for the Classification of Soil Types and the Determination of Soil Total Nitrogen

by Shengyao Jia¹, Hongyang Li^1,2, Yanjie Wang¹, Renyuan Tong¹ and Qing Li^1,*

¹ College of Mechanical and Electrical Engineering, China Jiliang University, Hangzhou 310018, China

² College of Computer Science and Technology, Zhejiang University of Technology, Hangzhou 310014, China

Sensors 2017, 17(10), 2252; https://doi.org/10.3390/s17102252 - 30 Sep 2017

Cited by 51 | Viewed by 8071

Abstract

Soil is an important environment for crop growth. Quick and accurately access to soil nutrient content information is a prerequisite for scientific fertilization. In this work, hyperspectral imaging (HSI) technology was applied for the classification of soil types and the measurement of soil [...] Read more.

Soil is an important environment for crop growth. Quick and accurately access to soil nutrient content information is a prerequisite for scientific fertilization. In this work, hyperspectral imaging (HSI) technology was applied for the classification of soil types and the measurement of soil total nitrogen (TN) content. A total of 183 soil samples collected from Shangyu City (People’s Republic of China), were scanned by a near-infrared hyperspectral imaging system with a wavelength range of 874–1734 nm. The soil samples belonged to three major soil types typical of this area, including paddy soil, red soil and seashore saline soil. The successive projections algorithm (SPA) method was utilized to select effective wavelengths from the full spectrum. Pattern texture features (energy, contrast, homogeneity and entropy) were extracted from the gray-scale images at the effective wavelengths. The support vector machines (SVM) and partial least squares regression (PLSR) methods were used to establish classification and prediction models, respectively. The results showed that by using the combined data sets of effective wavelengths and texture features for modelling an optimal correct classification rate of 91.8%. could be achieved. The soil samples were first classified, then the local models were established for soil TN according to soil types, which achieved better prediction results than the general models. The overall results indicated that hyperspectral imaging technology could be used for soil type classification and soil TN determination, and data fusion combining spectral and image texture information showed advantages for the classification of soil types. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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18 pages, 7024 KiB

Open AccessArticle

PSpice Modeling of a Sandwich Piezoelectric Ceramic Ultrasonic Transducer in Longitudinal Vibration

by Xiaoyuan Wei, Yuan Yang^*, Wenqing Yao and Lei Zhang

Department of Electronic Engineering, Xi’an University of Technology, Xi’an 710048, Shaanxi, China

Sensors 2017, 17(10), 2253; https://doi.org/10.3390/s17102253 - 30 Sep 2017

Cited by 34 | Viewed by 11009

Abstract

Sandwiched piezoelectric transducers are widely used, especially in high power applications. For more convenient analysis and design, a PSpice lossy model of sandwiched piezoelectric ultrasonic transducers in longitudinal vibration is proposed by means of the one-dimensional wave and transmission line theories. With the [...] Read more.

Sandwiched piezoelectric transducers are widely used, especially in high power applications. For more convenient analysis and design, a PSpice lossy model of sandwiched piezoelectric ultrasonic transducers in longitudinal vibration is proposed by means of the one-dimensional wave and transmission line theories. With the proposed model, the resonance and antiresonance frequencies are obtained, and it is shown that the simulations and measurements have good consistency. For the purpose of further verification the accuracy and application of the PSpice model, a pitch-catch setup and an experimental platform are built. They include two sandwiched piezoelectric ultrasonic transducers and two aluminum cylinders whose lengths are 20 mm and 100 mm respectively. Based on this pitch-catch setup, the impedance and transient analysis are performed. Compared with the measured results, it is shown that the simulated results have good consistency. In addition, the conclusion can be drawn that the optimal excitation frequency for the pitch-catch setup is not necessarily the resonance frequency of ultrasonic transducers, because the resonance frequency is obtained under no load. The proposed PSpice model of the sandwiched piezoelectric transducer is more conveniently applied to combine with other circuits such as driving circuits, filters, amplifiers, and so on. Full article

(This article belongs to the Section Physical Sensors)

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30 pages, 7319 KiB

Open AccessArticle

An Extended ADOP for Performance Evaluation of Single-Frequency Single-Epoch Positioning by BDS/GPS in Asia-Pacific Region

by Xin Liu, Shubi Zhang, Qiuzhao Zhang^* and Wei Yang

School of Environment Science and Spatial Informatics, China University of Mining and Technology, No. 1 Daxue Road, Xuzhou 221116, China

Sensors 2017, 17(10), 2254; https://doi.org/10.3390/s17102254 - 30 Sep 2017

Cited by 10 | Viewed by 4245

Abstract

Single-Frequency Single-Epoch (SFSE) high-precision positioning has always been the hot spot of Global Navigation Satellite System (GNSS), and ambiguity dilution of precision (ADOP) is a well-known scalar measure for success rate of ambiguity resolution. Traditional ADOP expression is complicated, thus the SFSE extended [...] Read more.

Single-Frequency Single-Epoch (SFSE) high-precision positioning has always been the hot spot of Global Navigation Satellite System (GNSS), and ambiguity dilution of precision (ADOP) is a well-known scalar measure for success rate of ambiguity resolution. Traditional ADOP expression is complicated, thus the SFSE extended ADOP (E-ADOP), with the newly defined Summation-Multiplication Ratio of Weight (SMRW) and two theorems for short baseline, was developed. This simplifies the ADOP expression; gives a clearer insight into the influences of SMRW and number of satellites on E-ADOP; and makes theoretical analysis of E-ADOP more convenient than that of ADOP, and through that the E-ADOP value can be predicted more accurately than through the ADOP expression for ADOP value. E-ADOP reveals that number of satellites and SMRW or high-elevation satellite are important for ADOP and, through E-ADOP, we studied which factor is dominant to control ADOP in different conditions and make ADOP different between BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), and BDS/GPS. Based on experimental results of SFSE positioning with different baselines, some conclusions are made: (1) ADOP decreases when new satellites are added mainly because the number of satellites becomes larger; (2) when the number of satellites is constant, ADOP is mainly affected by SMRW; (3) in contrast to systems where the satellites with low-elevation are the majority or where low- and high-elevation satellites are equally distributed, in systems where the high-elevation satellites are the majority, the SMRW mainly makes ADOP smaller, even if there are fewer satellites than in the two previous cases, and the difference in numbers of satellites can be expanded as the proportion of high-elevation satellites becomes larger; and (4) ADOP of BDS is smaller than ADOP of GPS mainly because of its SMRW. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 7714 KiB

Open AccessArticle

An Algorithm Based Wavelet Entropy for Shadowing Effect of Human Detection Using Ultra-Wideband Bio-Radar

by Huijun Xue^1,†

, Miao Liu^1,†, Yang Zhang², Fulai Liang¹, Fugui Qi¹, Fuming Chen³

, Hao Lv^1,*, Jianqi Wang^1,* and Yang Zhang¹

¹ Department of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China

² Center for Disease Control and Prevention of Guangzhou Military Region, Guangzhou 510507, China

³ Department of Medical Engineering, Lanzhou General Hospital of Lanzhou Military Area Command of PLA, Lanzhou 730050, China

^† These authors contributed equally to this work and should be regarded as co-first author.

Sensors 2017, 17(10), 2255; https://doi.org/10.3390/s17102255 - 30 Sep 2017

Cited by 11 | Viewed by 5701

Abstract

Ultra-wide band (UWB) radar for short-range human target detection is widely used to find and locate survivors in some rescue missions after a disaster. The results of the application of bistatic UWB radar for detecting multi-stationary human targets have shown that human targets [...] Read more.

Ultra-wide band (UWB) radar for short-range human target detection is widely used to find and locate survivors in some rescue missions after a disaster. The results of the application of bistatic UWB radar for detecting multi-stationary human targets have shown that human targets close to the radar antennas are very often visible, while those farther from radar antennas are detected with less reliability. In this paper, on account of the significant difference of frequency content between the echo signal of the human target and that of noise in the shadowing region, an algorithm based on wavelet entropy is proposed to detect multiple targets. Our findings indicate that the entropy value of human targets was much lower than that of noise. Compared with the method of adaptive filtering and the energy spectrum, wavelet entropy can accurately detect the person farther from the radar antennas, and it can be employed as a useful tool in detecting multiple targets by bistatic UWB radar. Full article

(This article belongs to the Section Remote Sensors)

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8 pages, 1866 KiB

Open AccessArticle

Optical Spring Effect in Micro-Bubble Resonators and Its Application for the Effective Mass Measurement of Optomechanical Resonant Mode

by Zhenmin Chen¹, Xiang Wu¹, Liying Liu¹ and Lei Xu^1,2,*

¹ Key Lab for Micro and Nanophotonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Engineering, Fudan University, Shanghai 200433, China

² Department of Physics, Fudan University, Shanghai 200433, China

Sensors 2017, 17(10), 2256; https://doi.org/10.3390/s17102256 - 30 Sep 2017

Cited by 8 | Viewed by 5806

Abstract

In this work, we present a novel approach for obtaining the effective mass of mechanical vibration mode in micro-bubble resonators (MBRs). To be specific, the effective mass is deduced from the measurement of optical spring effect (OSE) in MBRs. This approach is demonstrated [...] Read more.

In this work, we present a novel approach for obtaining the effective mass of mechanical vibration mode in micro-bubble resonators (MBRs). To be specific, the effective mass is deduced from the measurement of optical spring effect (OSE) in MBRs. This approach is demonstrated and applied to analyze the effective mass of hollow MBRs and liquid-filled MBRs, respectively. It is found that the liquid-filled MBRs has significantly stronger OSE and a less effective mass than hollow MBRs, both of the extraordinary behaviors can be beneficial for applications such as mass sensing. Larger OSE from higher order harmonics of the mechanical modes is also observed. Our work paves a way towards the developing of OSE-based high sensitive mass sensor in MBRs. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2017)

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17 pages, 16058 KiB

Open AccessArticle

A Novel Position Compensation Scheme for Cable-Pulley Mechanisms Used in Laparoscopic Surgical Robots

by Yunlei Liang, Zhijiang Du, Weidong Wang^*

and Lining Sun

State Key Laboratory of Robotics and System, Harbin Institute of Technology, 2 Yikuang Street, Harbin 150080, China

Sensors 2017, 17(10), 2257; https://doi.org/10.3390/s17102257 - 30 Sep 2017

Cited by 24 | Viewed by 8983

Abstract

The tendon driven mechanism using a cable and pulley to transmit power is adopted by many surgical robots. However, backlash hysteresis objectively exists in cable-pulley mechanisms, and this nonlinear problem is a great challenge in precise position control during the surgical procedure. Previous [...] Read more.

The tendon driven mechanism using a cable and pulley to transmit power is adopted by many surgical robots. However, backlash hysteresis objectively exists in cable-pulley mechanisms, and this nonlinear problem is a great challenge in precise position control during the surgical procedure. Previous studies mainly focused on the transmission characteristics of the cable-driven system and constructed transmission models under particular assumptions to solve nonlinear problems. However, these approaches are limited because the modeling process is complex and the transmission models lack general applicability. This paper presents a novel position compensation control scheme to reduce the impact of backlash hysteresis on the positioning accuracy of surgical robots’ end-effectors. In this paper, a position compensation scheme using a support vector machine based on feedforward control is presented to reduce the position tracking error. To validate the proposed approach, experimental validations are conducted on our cable-pulley system and comparative experiments are carried out. The results show remarkable improvements in the performance of reducing the positioning error for the use of the proposed scheme. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 15507 KiB

Open AccessArticle

Classification of Fusarium-Infected Korean Hulled Barley Using Near-Infrared Reflectance Spectroscopy and Partial Least Squares Discriminant Analysis

by Jongguk Lim¹

, Giyoung Kim¹, Changyeun Mo^1,*, Kyoungmin Oh¹, Hyeonchae Yoo¹, Hyeonheui Ham² and Moon S. Kim³

¹ Department of Agricultural Engineering, National Institute of Agricultural Sciences, Rural Development Administration, 310 Nongsaengmyeng-ro, Wansan-gu, Jeonju 54875, Korea

² Microbial Safety Team, National Institute of Agricultural Sciences, Rural Development Administration, 166 Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun 55365, Korea

³ Environmental Microbial and Food Safety Laboratory, Agricultural Research Service, US Department of Agriculture, 10300 Baltimore Avenue, Beltsville, MD 20705, USA

Sensors 2017, 17(10), 2258; https://doi.org/10.3390/s17102258 - 30 Sep 2017

Cited by 14 | Viewed by 4891

Abstract

The purpose of this study is to use near-infrared reflectance (NIR) spectroscopy equipment to nondestructively and rapidly discriminate Fusarium-infected hulled barley. Both normal hulled barley and Fusarium-infected hulled barley were scanned by using a NIR spectrometer with a wavelength range of [...] Read more.

The purpose of this study is to use near-infrared reflectance (NIR) spectroscopy equipment to nondestructively and rapidly discriminate Fusarium-infected hulled barley. Both normal hulled barley and Fusarium-infected hulled barley were scanned by using a NIR spectrometer with a wavelength range of 1175 to 2170 nm. Multiple mathematical pretreatments were applied to the reflectance spectra obtained for Fusarium discrimination and the multivariate analysis method of partial least squares discriminant analysis (PLS-DA) was used for discriminant prediction. The PLS-DA prediction model developed by applying the second-order derivative pretreatment to the reflectance spectra obtained from the side of hulled barley without crease achieved 100% accuracy in discriminating the normal hulled barley and the Fusarium-infected hulled barley. These results demonstrated the feasibility of rapid discrimination of the Fusarium-infected hulled barley by combining multivariate analysis with the NIR spectroscopic technique, which is utilized as a nondestructive detection method. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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9 pages, 3071 KiB

Open AccessArticle

A Novel Fiber Optic Surface Plasmon Resonance Biosensors with Special Boronic Acid Derivative to Detect Glycoprotein

by Yang Zhang, Fang Wang, Siyu Qian, Zexu Liu, Qiao Wang, Yiying Gu, Zhenlin Wu, Zhenguo Jing, Changsen Sun and Wei Peng^*

School of Physics and Optoelectronic Technology, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian 116024, China

Sensors 2017, 17(10), 2259; https://doi.org/10.3390/s17102259 - 1 Oct 2017

Cited by 44 | Viewed by 7192

Abstract

We proposed and demonstrated a novel tilted fiber Bragg grating (TFBG)-based surface plasmon resonance (SPR) label-free biosensor via a special boronic acid derivative to detect glycoprotein with high sensitivity and selectivity. TFBG, as an effective sensing element for optical sensing in near-infrared wavelengths, [...] Read more.

We proposed and demonstrated a novel tilted fiber Bragg grating (TFBG)-based surface plasmon resonance (SPR) label-free biosensor via a special boronic acid derivative to detect glycoprotein with high sensitivity and selectivity. TFBG, as an effective sensing element for optical sensing in near-infrared wavelengths, possess the unique capability of easily exciting the SPR effect on fiber surface which coated with a nano-scale metal layer. SPR properties can be accurately detected by measuring the variation of transmitted spectra at optical communication wavelengths. In our experiment, a 10° TFBG coated with a 50 nm gold film was manufactured to stimulate SPR on a sensor surface. To detect glycoprotein selectively, the sensor was immobilized using designed phenylboronic acid as the recognition molecule, which can covalently bond with 1,2- or 1,3-diols to form five- or six-membered cyclic complexes for attaching diol-containing biomolecules and proteins. The phenylboronic acid was synthetized with long alkyl groups offering more flexible space, which was able to improve the capability of binding glycoprotein. The proposed TFBG-SPR sensors exhibit good selectivity and repeatability with a protein concentration sensitivity up to 2.867 dB/ (mg/mL) and a limit of detection (LOD) of 15.56 nM. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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21 pages, 9364 KiB

Open AccessArticle

CuFusion: Accurate Real-Time Camera Tracking and Volumetric Scene Reconstruction with a Cuboid

by Chen Zhang^*

and Yu Hu

College of Computer Science and Technology, Zhejiang University, Hangzhou 310027, China

Sensors 2017, 17(10), 2260; https://doi.org/10.3390/s17102260 - 1 Oct 2017

Cited by 8 | Viewed by 6083

Abstract

Given a stream of depth images with a known cuboid reference object present in the scene, we propose a novel approach for accurate camera tracking and volumetric surface reconstruction in real-time. Our contribution in this paper is threefold: (a) utilizing a priori knowledge [...] Read more.

Given a stream of depth images with a known cuboid reference object present in the scene, we propose a novel approach for accurate camera tracking and volumetric surface reconstruction in real-time. Our contribution in this paper is threefold: (a) utilizing a priori knowledge of the precisely manufactured cuboid reference object, we keep drift-free camera tracking without explicit global optimization; (b) we improve the fineness of the volumetric surface representation by proposing a prediction-corrected data fusion strategy rather than a simple moving average, which enables accurate reconstruction of high-frequency details such as the sharp edges of objects and geometries of high curvature; (c) we introduce a benchmark dataset CU3D that contains both synthetic and real-world scanning sequences with ground-truth camera trajectories and surface models for the quantitative evaluation of 3D reconstruction algorithms. We test our algorithm on our dataset and demonstrate its accuracy compared with other state-of-the-art algorithms. We release both our dataset and code as open-source (https://github.com/zhangxaochen/CuFusion) for other researchers to reproduce and verify our results. Full article

(This article belongs to the Special Issue Imaging Depth Sensors—Sensors, Algorithms and Applications)

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34 pages, 4391 KiB

Open AccessArticle

Spoof Detection for Finger-Vein Recognition System Using NIR Camera

by Dat Tien Nguyen, Hyo Sik Yoon, Tuyen Danh Pham and Kang Ryoung Park^*

Division of Electronics and Electrical Engineering, Dongguk University, 30 Pildong-ro 1-gil, Jung-gu, Seoul 100-715, Korea

Sensors 2017, 17(10), 2261; https://doi.org/10.3390/s17102261 - 1 Oct 2017

Cited by 39 | Viewed by 9220

Abstract

Finger-vein recognition, a new and advanced biometrics recognition method, is attracting the attention of researchers because of its advantages such as high recognition performance and lesser likelihood of theft and inaccuracies occurring on account of skin condition defects. However, as reported by previous [...] Read more.

Finger-vein recognition, a new and advanced biometrics recognition method, is attracting the attention of researchers because of its advantages such as high recognition performance and lesser likelihood of theft and inaccuracies occurring on account of skin condition defects. However, as reported by previous researchers, it is possible to attack a finger-vein recognition system by using presentation attack (fake) finger-vein images. As a result, spoof detection, named as presentation attack detection (PAD), is necessary in such recognition systems. Previous attempts to establish PAD methods primarily focused on designing feature extractors by hand (handcrafted feature extractor) based on the observations of the researchers about the difference between real (live) and presentation attack finger-vein images. Therefore, the detection performance was limited. Recently, the deep learning framework has been successfully applied in computer vision and delivered superior results compared to traditional handcrafted methods on various computer vision applications such as image-based face recognition, gender recognition and image classification. In this paper, we propose a PAD method for near-infrared (NIR) camera-based finger-vein recognition system using convolutional neural network (CNN) to enhance the detection ability of previous handcrafted methods. Using the CNN method, we can derive a more suitable feature extractor for PAD than the other handcrafted methods using a training procedure. We further process the extracted image features to enhance the presentation attack finger-vein image detection ability of the CNN method using principal component analysis method (PCA) for dimensionality reduction of feature space and support vector machine (SVM) for classification. Through extensive experimental results, we confirm that our proposed method is adequate for presentation attack finger-vein image detection and it can deliver superior detection results compared to CNN-based methods and other previous handcrafted methods. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 11332 KiB

Open AccessArticle

A Method for Automatic Surface Inspection Using a Model-Based 3D Descriptor

by Carlos A. Madrigal^1,*

, John W. Branch²

, Alejandro Restrepo²

and Domingo Mery³

¹ Departamento de Ingeniería Electrónica, Instituto Tecnológico Metropolitano, Medellín 050013, Colombia

² Facultad de Minas, Universidad Nacional de Colombia, Medellín 050041, Colombia

³ Departamento de Ciencias de la Computación, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile

Sensors 2017, 17(10), 2262; https://doi.org/10.3390/s17102262 - 2 Oct 2017

Cited by 39 | Viewed by 6483

Abstract

Automatic visual inspection allows for the identification of surface defects in manufactured parts. Nevertheless, when defects are on a sub-millimeter scale, detection and recognition are a challenge. This is particularly true when the defect generates topological deformations that are not shown with strong [...] Read more.

Automatic visual inspection allows for the identification of surface defects in manufactured parts. Nevertheless, when defects are on a sub-millimeter scale, detection and recognition are a challenge. This is particularly true when the defect generates topological deformations that are not shown with strong contrast in the 2D image. In this paper, we present a method for recognizing surface defects in 3D point clouds. Firstly, we propose a novel 3D local descriptor called the Model Point Feature Histogram (MPFH) for defect detection. Our descriptor is inspired from earlier descriptors such as the Point Feature Histogram (PFH). To construct the MPFH descriptor, the models that best fit the local surface and their normal vectors are estimated. For each surface model, its contribution weight to the formation of the surface region is calculated and from the relative difference between models of the same region a histogram is generated representing the underlying surface changes. Secondly, through a classification stage, the points on the surface are labeled according to five types of primitives and the defect is detected. Thirdly, the connected components of primitives are projected to a plane, forming a 2D image. Finally, 2D geometrical features are extracted and by a support vector machine, the defects are recognized. The database used is composed of 3D simulated surfaces and 3D reconstructions of defects in welding, artificial teeth, indentations in materials, ceramics and 3D models of defects. The quantitative and qualitative results showed that the proposed method of description is robust to noise and the scale factor, and it is sufficiently discriminative for detecting some surface defects. The performance evaluation of the proposed method was performed for a classification task of the 3D point cloud in primitives, reporting an accuracy of 95%, which is higher than for other state-of-art descriptors. The rate of recognition of defects was close to 94%. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 637 KiB

Open AccessArticle

Wireless Distributed Environmental Sensor Networks for Air Pollution Measurement—The Promise and the Current Reality

by David M. Broday^*

and The Citi-Sense Project Collaborators^†

¹ Faculty of Civil and Environmental Engineering, Technion IIT, 32000 Haifa, Israel

^† Alexander Arpaci (UBIMET GmbH, Vienna, Austria); Alena Bartonova (Norwegian Institute for Air Research (NILU), Kjeller, Norway); Nuría Castell-Balaguer (Norwegian Institute for Air Research (NILU), Kjeller, Norway); Tom Cole-Hunter (ISGlobal, Centre for Research in Environmental Epidemiology, Barcelona, Spain); Franck R. Dauge (Norwegian Institute for Air Research (NILU), Kjeller, Norway); Barak, Fishbain (CEE, Technion, Haifa, Israel); Rod L. Jones (University of Cambridge, Cambridge, England, UK); Karen Galea (Institute of Occupational Medicine (IOM), Edinburgh, Scotland, UK); Milena Jovasevic-Stojanovic (VINČA Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia); David Kocman (Jožef Stefan Institute, Ljubljana, Slovenia); Tania Martinez-Iñiguez (ISGlobal, Centre for Research in Environmental Epidemiology, Barcelona, Spain); Mark Nieuwenhuijsen (ISGlobal, Centre for Research in Environmental Epidemiology, Barcelona, Spain); Johanna Robinson (Jožef Stefan Institute, Ljubljana, Slovenia); Vlasta Svecova (Institute of Experimental Medicine, Prague, Czech Republic); Phong Thai (Queensland University of Technology, Brisbane, Australia).

Sensors 2017, 17(10), 2263; https://doi.org/10.3390/s17102263 - 2 Oct 2017

Cited by 46 | Viewed by 7856

Abstract

The evaluation of the effects of air pollution on public health and human-wellbeing requires reliable data. Standard air quality monitoring stations provide accurate measurements of airborne pollutant levels, but, due to their sparse distribution, they cannot capture accurately the spatial variability of air [...] Read more.

The evaluation of the effects of air pollution on public health and human-wellbeing requires reliable data. Standard air quality monitoring stations provide accurate measurements of airborne pollutant levels, but, due to their sparse distribution, they cannot capture accurately the spatial variability of air pollutant concentrations within cities. Dedicated in-depth field campaigns have dense spatial coverage of the measurements but are held for relatively short time periods. Hence, their representativeness is limited. Moreover, the oftentimes integrated measurements represent time-averaged records. Recent advances in communication and sensor technologies enable the deployment of dense grids of Wireless Distributed Environmental Sensor Networks for air quality monitoring, yet their capability to capture urban-scale spatiotemporal pollutant patterns has not been thoroughly examined to date. Here, we summarize our studies on the practicalities of using data streams from sensor nodes for air quality measurement and the required methods to tune the results to different stakeholders and applications. We summarize the results from eight cities across Europe, five sensor technologies-three stationary (with one tested also while moving) and two personal sensor platforms, and eight ambient pollutants. Overall, few sensors showed an exceptional and consistent performance, which can shed light on the fine spatiotemporal urban variability of pollutant concentrations. Stationary sensor nodes were more reliable than personal nodes. In general, the sensor measurements tend to suffer from the interference of various environmental factors and require frequent calibrations. This calls for the development of suitable field calibration procedures, and several such in situ field calibrations are presented. Full article

(This article belongs to the Special Issue Air Pollution Sensors: A New Class of Tools to Measure Air Quality)

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16 pages, 6559 KiB

Open AccessArticle

A 4 mm² Double Differential Torsional MEMS Accelerometer Based on a Double-Beam Configuration

by Tongqiao Miao, Dingbang Xiao^*, Qingsong Li, Zhanqiang Hou and Xuezhong Wu^*

College of Mechatronics Engineering and Automation, National University of DefenseTechnology, Changsha 410073, China

Sensors 2017, 17(10), 2264; https://doi.org/10.3390/s17102264 - 2 Oct 2017

Cited by 10 | Viewed by 6907

Abstract

This paper reports the design and simulation of a 4 mm² double differential torsional MEMS accelerometer based on a double-beam configuration. Based on the structure of conventional torsional accelerometers, normally composed of one pair of proof masses and one torsional beam, this [...] Read more.

This paper reports the design and simulation of a 4 mm² double differential torsional MEMS accelerometer based on a double-beam configuration. Based on the structure of conventional torsional accelerometers, normally composed of one pair of proof masses and one torsional beam, this work explores the double differential configuration: a torsional accelerometer with two pairs of unbalanced proof masses rotating in reverse. Also, the torsional beam is designed as a double-beam structure, which is a symmetrical structure formed by two torsional beams separated by a certain distance. The device area of the novel accelerometer is more than 50 times smaller than that of a traditional double differential torsional MEMS accelerometer. The FEM simulation results demonstrate that the smaller device does not sacrifice other specifications, such as mechanical sensitivity, nonlinearity and temperature robustness. The mechanical sensitivity and nonlinearity of a ±15 g measuring range is 59.4 fF/g and 0.88%, respectively. Compared with traditional single-beam silicon structures, the novel structure can achieve lower maximum principle stress in critical regions and reduce the possibility of failure when high-g acceleration loading is applied along all three axes. The mechanical noise equivalent acceleration is about

0.13 mg / \sqrt{Hz}

in the theoretical calculations and the offset temperature coefficient is 0.25 mg/

℃

in the full temperature range of

- 40 ℃

to

60 ℃

. Full article

(This article belongs to the Collection Modeling, Testing and Reliability Issues in MEMS Engineering)

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3 pages, 635 KiB

Open AccessCorrection

Correction: Domingues Franceschini, M.H.; et al. Intercomparison of Unmanned Aerial Vehicle and Ground-Based Narrow Band Spectrometers Applied to Crop Trait Monitoring in Organic Potato Production. Sensors 2017, 17, 1428

by Marston Héracles Domingues Franceschini^1,*

, Harm Bartholomeus¹, Dirk Van Apeldoorn², Juha Suomalainen^1,3

and Lammert Kooistra¹

¹ Laboratory of Geo-Information Science and Remote Sensing, Wageningen University and Research, P.O. Box 47, 6700 AA Wageningen, The Netherlands

² Farming Systems Ecology group, Wageningen University and Research, P.O. Box 430, 6700 AK Wageningen, The Netherlands

³ Finnish Geospatial Research Institute, National Land Survey of Finland, Geodeetinrinne 1, 02430 Masala, Finland

Sensors 2017, 17(10), 2265; https://doi.org/10.3390/s17102265 - 2 Oct 2017

Cited by 3 | Viewed by 3740

Abstract

The authors would like to correct Figure 13 and Table A2, as well as the text related to the data presented in both of them, as indicated below, considering that an error in the calculations involving Equation (2), described in the Section 2.8 [...] Read more.

The authors would like to correct Figure 13 and Table A2, as well as the text related to the data presented in both of them, as indicated below, considering that an error in the calculations involving Equation (2), described in the Section 2.8 of the Materials and Methods Section, resulted in the communication of incorrect values [...]
Full article

(This article belongs to the Section Remote Sensors)

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Figure 13

14 pages, 3909 KiB

Open AccessArticle

Brillouin Optical Correlation Domain Analysis in Composite Material Beams

by Yonatan Stern¹, Yosef London¹, Eyal Preter¹, Yair Antman¹, Hilel Hagai Diamandi¹, Maayan Silbiger², Gadi Adler², Eyal Levenberg³

, Doron Shalev⁴ and Avi Zadok^1,*

¹ Faculty of Engineering and Institute for Nano-Technology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan 5290002, Israel

² Xenom Ltd., 4 Gluska st., Rishon LeTzion 7565004, Israel

³ Department of Civil Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark

⁴ Doron Shalev Engineering Ltd., 23 Bar-Kochba st., Bnei-Brak 5126002, Israel

Sensors 2017, 17(10), 2266; https://doi.org/10.3390/s17102266 - 2 Oct 2017

Cited by 5 | Viewed by 4779

Abstract

Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both), however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained with optical [...] Read more.

Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both), however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained with optical fiber sensors. In this work, we report high-resolution distributed Brillouin sensing over standard fibers that are embedded in composite structures. A phase-coded, Brillouin optical correlation domain analysis (B-OCDA) protocol was employed, with spatial resolution of 2 cm and sensitivity of 1 °K or 20 micro-strain. A portable measurement setup was designed and assembled on the premises of a composite structures manufacturer. The setup was successfully utilized in several structural health monitoring scenarios: (a) monitoring the production and curing of a composite beam over 60 h; (b) estimating the stiffness and Young’s modulus of a composite beam; and (c) distributed strain measurements across the surfaces of a model wing of an unmanned aerial vehicle. The measurements are supported by the predictions of structural analysis calculations. The results illustrate the potential added values of high-resolution, distributed Brillouin sensing in the structural health monitoring of composites. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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12 pages, 6205 KiB

Open AccessArticle

Carbon Black-Modified Electrodes Screen-Printed onto Paper Towel, Waxed Paper and Parafilm M^®

by Stefano Cinti^1,*, Vincenzo Mazzaracchio¹, Ilaria Cacciotti², Danila Moscone¹ and Fabiana Arduini^1,*

¹ Department of Chemical Science and Technology, University of Rome “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Rome, Italy

² Department of Engineering, University of Rome Niccolò Cusano, Via Don Carlo Gnocchi 3, 00166 Rome, Italy

Sensors 2017, 17(10), 2267; https://doi.org/10.3390/s17102267 - 3 Oct 2017

Cited by 61 | Viewed by 9178

Abstract

Herein, we evaluated the use of paper towel, waxed paper, and Parafilm M^® (Heathrow Scientific, Vernon Hills, IL, USA) as alternative substrates for screen-printed sensor manufacturing. Morphological study was performed to evaluate the adhesion of the ink on these uncommon substrates, as [...] Read more.

Herein, we evaluated the use of paper towel, waxed paper, and Parafilm M^® (Heathrow Scientific, Vernon Hills, IL, USA) as alternative substrates for screen-printed sensor manufacturing. Morphological study was performed to evaluate the adhesion of the ink on these uncommon substrates, as well as the morphology of the working electrode. The electrochemical characterization was carried out using ferricyanide/ferrocyanide as redox couple. To enhance the electrochemical properties of the developed sensors, the nanomaterial carbon black was used as nanomodifier. The modification by drop casting of the working electrode surface, using a stable dispersion of carbon black, allows to obtain a sensor with improved electrochemical behavior in terms of peak-to-peak separation, current intensity, and the resistance of charge transfer. The results achieved confirm the possibility of printing the electrode on several cost-effective paper-based materials and the improvement of the electrochemical behavior by using carbon black as sustainable nanomaterial. Full article

(This article belongs to the Special Issue Advanced Sensors Based on Carbon Electrodes)

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12 pages, 3544 KiB

Open AccessArticle

Passive Sensors for Long Duration Internet of Things Networks

by Felisberto Pereira^*, Ricardo Correia and Nuno Borges Carvalho

Instituto de Telecomunicações, Departamento de Electrónica Telecomunicações e Informática, Universidade de Aveiro, Aveiro 3810-193, Portugal

Sensors 2017, 17(10), 2268; https://doi.org/10.3390/s17102268 - 3 Oct 2017

Cited by 13 | Viewed by 5771

Abstract

In this work, three different concepts are used to develop a fully passive sensor that is capable of measuring different types of data. The sensor was supplied by Wireless Power Transmission (WPT). Communication between the sensor and reader is established by a backscatter, [...] Read more.

In this work, three different concepts are used to develop a fully passive sensor that is capable of measuring different types of data. The sensor was supplied by Wireless Power Transmission (WPT). Communication between the sensor and reader is established by a backscatter, and to ensure minimum energy consumption, low power techniques are used. In a simplistic way, the process starts by the transmission of two different waves by the reader to the sensor, one of which is used in power transmission and the other of which is used to communicate. Once the sensor is powered, the monitoring process starts. From the monitoring state, results from after processing are used to modulate the incoming wave, which is the information that is sent back from the reader to the tag. This new combination of technologies enables the possibility of using sensors without any cables or batteries to operate 340 cm from the reader. The developed prototype measures acceleration and temperature. However, it is scalable. This system enables a new generation of passive Internet of Things (IoT) devices. Full article

(This article belongs to the Special Issue New Generation Sensors Enabling and Fostering IoT)

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19 pages, 1357 KiB

Open AccessArticle

Activity Level Assessment Using a Smart Cushion for People with a Sedentary Lifestyle

by Congcong Ma¹

, Wenfeng Li^1,*, Raffaele Gravina², Jingjing Cao¹, Qimeng Li² and Giancarlo Fortino²

¹ School of Logistics Engineering, Wuhan University of Technology, Wuhan 430070, China

² Department of Informatics, Modeling, Electronics and Systems, University of Calabria, 87036 Rende, Italy

Sensors 2017, 17(10), 2269; https://doi.org/10.3390/s17102269 - 3 Oct 2017

Cited by 36 | Viewed by 7030

Abstract

As a sedentary lifestyle leads to numerous health problems, it is important to keep constant motivation for a more active lifestyle. A large majority of the worldwide population, such as office workers, long journey vehicle drivers and wheelchair users, spends several hours every [...] Read more.

As a sedentary lifestyle leads to numerous health problems, it is important to keep constant motivation for a more active lifestyle. A large majority of the worldwide population, such as office workers, long journey vehicle drivers and wheelchair users, spends several hours every day in sedentary activities. The postures that sedentary lifestyle users assume during daily activities hide valuable information that can reveal their wellness and general health condition. Aiming at mining such underlying information, we developed a cushion-based system to assess their activity levels and recognize the activity from the information hidden in sitting postures. By placing the smart cushion on the chair, we can monitor users’ postures and body swings, using the sensors deployed in the cushion. Specifically, we construct a body posture analysis model to recognize sitting behaviors. In addition, we provided a smart cushion that effectively combine pressure and inertial sensors. Finally, we propose a method to assess the activity levels based on the evaluation of the activity assessment index (AAI) in time sliding windows. Activity level assessment can be used to provide statistical results in a defined period and deliver recommendation exercise to the users. For practical implications and actual significance of results, we selected wheelchair users among the participants to our experiments. Features in terms of standard deviation and approximate entropy were compared to recognize the activities and activity levels. The results showed that, using the novel designed smart cushion and the standard deviation features, we are able to achieve an accuracy of (>89%) for activity recognition and (>98%) for activity level recognition. Full article

(This article belongs to the Special Issue Sensor Intelligence Assisted by Data Analytics and Cognitive Computing)

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12 pages, 2794 KiB

Open AccessArticle

A Novel Differential Time-of-Arrival Estimation Technique for Impact Localization on Carbon Fiber Laminate Sheets

by Eugenio Marino Merlo

, Andrea Bulletti

, Pietro Giannelli

, Marco Calzolai and Lorenzo Capineri^*

Department of Information Engineering, University of Florence, Via S. Marta 3, 50139 Firenze, Italy

Sensors 2017, 17(10), 2270; https://doi.org/10.3390/s17102270 - 3 Oct 2017

Cited by 21 | Viewed by 5486

Abstract

Composite material structures are commonly used in many industrial sectors (aerospace, automotive, transportation), and can operate in harsh environments where impacts with other parts or debris may cause critical safety and functionality issues. This work presents a method for improving the accuracy of [...] Read more.

Composite material structures are commonly used in many industrial sectors (aerospace, automotive, transportation), and can operate in harsh environments where impacts with other parts or debris may cause critical safety and functionality issues. This work presents a method for improving the accuracy of impact position determination using acoustic source triangulation schemes based on the data collected by piezoelectric sensors attached to the structure. A novel approach is used to estimate the Differential Time-of-Arrival (DToA) between the impact response signals collected by a triplet of sensors, overcoming the limitations of classical methods that rely on amplitude thresholds calibrated for a specific sensor type. An experimental evaluation of the proposed technique was performed with specially made circular piezopolymer (PVDF) sensors designed for Structural Health Monitoring (SHM) applications, and compared with commercial piezoelectric SHM sensors of similar dimensions. Test impacts at low energies from 35 mJ to 600 mJ were generated in a laboratory by free-falling metal spheres on a 500 mm × 500 mm × 1.25 mm quasi-isotropic Carbon Fiber Reinforced Polymer (CFRP) laminate plate. From the analysis of many impact signals, the resulting localization error was improved for all types of sensors and, in particular, for the circular PVDF sensor an average error of 20.3 mm and a standard deviation of 8.9 mm was obtained. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2017)

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11 pages, 2334 KiB

Open AccessArticle

Reconfigurable Microfluidic Magnetic Valve Arrays: Towards a Radiotherapy-Compatible Spheroid Culture Platform for the Combinatorial Screening of Cancer Therapies

by Alexandre R. Brunet^1,2,3

, Frédérique Labelle⁴, Philip Wong^2,3,5 and Thomas Gervais^1,2,3,4,*

¹ Biomedical Engineering Institute, École Polytechnique de Montréal, Montreal, H3T 1J4, Canada

² Institut du Cancer de Montréal, Université de Montréal, Montréal, H3T 1J4, Canada

³ Centre de Recherche du Centre Hospitalier de l’Université de Montréal, H2X 0A9, Montréal, Canada

⁴ Department of Engineering Physics, École Polytechnique de Montréal, Montreal, H3T 1J4, Canada

⁵ Department of Radiation Oncology, Centre Hospitalier de l’Université de Montréal, Montréal, H2X 0A9, Canada

Sensors 2017, 17(10), 2271; https://doi.org/10.3390/s17102271 - 4 Oct 2017

Cited by 7 | Viewed by 5203

Abstract

We introduce here a microfluidic cell culture platform or spheroid culture chamber array (SCCA) that can synthesize, culture, and enable fluorescence imaging of 3D cell aggregates (typically spheroids) directly on-chip while specifying the flow of reagents in each chamber via the use of [...] Read more.

We introduce here a microfluidic cell culture platform or spheroid culture chamber array (SCCA) that can synthesize, culture, and enable fluorescence imaging of 3D cell aggregates (typically spheroids) directly on-chip while specifying the flow of reagents in each chamber via the use of an array of passive magnetic valves. The SCCA valves demonstrated sufficient resistance to burst (above 100 mBar), including after receiving radiotherapy (RT) doses of up to 8 Gy combined with standard 37 °C incubation for up to 7 days, enabling the simultaneous synthesis of multiple spheroids from different cell lines on the same array. Our results suggest that SCCA would be an asset in drug discovery processes, seeking to identify combinatorial treatments. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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9 pages, 1901 KiB

Open AccessArticle

Automated Dielectrophoretic Tweezers-Based Force Spectroscopy System in a Microfluidic Device

by Min Hyung Kim^1,†, Jeongjick Lee^1,†, Kihwan Nam^2,†, In Soo Park¹, Myeonggu Son¹, Hyunchul Ko¹, Sangyoup Lee^2,3, Dae Sung Yoon⁴, Woo-Jin Chang⁵

, Sei Young Lee¹, Young Ro Yoon^1,* and Sang Woo Lee^1,*

¹ Department of Biomedical Engineering, Yonsei University, Wonju 220-710, Korea

² Biomedical Research Institute, Korea Institute of Science and Technology, Seoul 136-791, Korea

³ Department of Biomedical Engineering, University of Science and Technology, Daejeon 305-350, Korea

⁴ Department of Bio-Convergence, Korea University, Seoul 136-701, Korea

⁵ Mechanical Engineering Department, University of Wisconsin-Milwaukee, 3200 N Cramer St., Milwaukee, WI 53211, USA

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2272; https://doi.org/10.3390/s17102272 - 4 Oct 2017

Cited by 8 | Viewed by 4993

Abstract

We reported an automated dielectrophoretic (DEP) tweezers-based force spectroscopy system to examine intermolecular weak binding interactions, which consists of three components: (1) interdigitated electrodes and micro-sized polystyrene particles used as DEP tweezers and probes inside a microfluidic device, along with an arbitrary function [...] Read more.

We reported an automated dielectrophoretic (DEP) tweezers-based force spectroscopy system to examine intermolecular weak binding interactions, which consists of three components: (1) interdigitated electrodes and micro-sized polystyrene particles used as DEP tweezers and probes inside a microfluidic device, along with an arbitrary function generator connected to a high voltage amplifier; (2) microscopy hooked up to a high-speed charge coupled device (CCD) camera with an image acquisition device; and (3) a computer aid control system based on the LabVIEW program. Using this automated system, we verified the measurement reliability by measuring intermolecular weak binding interactions, such as hydrogen bonds and Van der Waals interactions. In addition, we also observed the linearity of the force loading rates, which is applied to the probes by the DEP tweezers, by varying the number of voltage increment steps and thus affecting the linearity of the force loading rates. This system provides a simple and low-cost platform to investigate intermolecular weak binding interactions. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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22 pages, 6261 KiB

Open AccessArticle

Empowerment of Patients with Hypertension through BPM, IoT and Remote Sensing

by Daniel Ruiz-Fernández^*

, Diego Marcos-Jorquera

, Virgilio Gilart-Iglesias

, Víctor Vives-Boix

and Javier Ramírez-Navarro

Department of Computer Technology, University of Alicante, 03690 Alicante, Spain

Sensors 2017, 17(10), 2273; https://doi.org/10.3390/s17102273 - 4 Oct 2017

Cited by 41 | Viewed by 8118

Abstract

Hypertension affects one in five adults worldwide. Healthcare processes require interdisciplinary cooperation and coordination between medical teams, clinical processes, and patients. The lack of patients’ empowerment and adherence to treatment makes necessary to integrate patients, data collecting devices and clinical processes. For this [...] Read more.

Hypertension affects one in five adults worldwide. Healthcare processes require interdisciplinary cooperation and coordination between medical teams, clinical processes, and patients. The lack of patients’ empowerment and adherence to treatment makes necessary to integrate patients, data collecting devices and clinical processes. For this reason, in this paper we propose a model based on Business Process Management paradigm, together with a group of technologies, techniques and IT principles which increase the benefits of the paradigm. To achieve the proposed model, the clinical process of the hypertension is analyzed with the objective of detecting weaknesses and improving the process. Once the process is analyzed, an architecture that joins health devices and environmental sensors, together with an information system, has been developed. To test the architecture, a web system connected with health monitors and environment sensors, and with a mobile app have been implemented. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI 2016)

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13 pages, 2169 KiB

Open AccessArticle

Detecting Steps Walking at very Low Speeds Combining Outlier Detection, Transition Matrices and Autoencoders from Acceleration Patterns

by Mario Muñoz-Organero^1,2,*

and Ramona Ruiz-Blázquez¹

¹ Telematics Engineering Department, Carlos III University of Madrid, 28903 Getafe, Spain

² UC3M-BS Institute of Financial Big Data, Carlos III University of Madrid, 28903 Getafe, Spain

Sensors 2017, 17(10), 2274; https://doi.org/10.3390/s17102274 - 5 Oct 2017

Cited by 4 | Viewed by 5632

Abstract

In this paper, we develop and validate a new algorithm to detect steps while walking at speeds between 30 and 40 steps per minute based on the data sensed from a single tri-axial accelerometer. The algorithm concatenates three consecutive phases. First, an outlier [...] Read more.

In this paper, we develop and validate a new algorithm to detect steps while walking at speeds between 30 and 40 steps per minute based on the data sensed from a single tri-axial accelerometer. The algorithm concatenates three consecutive phases. First, an outlier detection is performed on the sensed data based on the Mahalanobis distance to pre-detect candidate points in the acceleration time series that may contain a ground contact segment of data while walking. Second, the acceleration segment around the pre-detected point is used to calculate the transition matrix in order to capture the time dependencies. Finally, autoencoders, trained with data segments containing ground contact transition matrices from acceleration series from labeled steps are used to reconstruct the computed transition matrices at each pre-detected point. A similarity index is used to assess if the pre-selected point contains a true step in the 30–40 steps per minute speed range. Our experimental results, based on a database from three different participants performing similar activities to the target one, are able to achieve a recall = 0.88 with precision = 0.50 improving the results when directly applying the autoencoders to acceleration patterns (recall = 0.77 with precision = 0.50). Full article

(This article belongs to the Special Issue Sensors for Gait, Posture, and Health Monitoring)

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22 pages, 936 KiB

Open AccessArticle

Robust Weighted Sum Harvested Energy Maximization for SWIPT Cognitive Radio Networks Based on Particle Swarm Optimization

by Pham Viet Tuan^1,2 and Insoo Koo^1,*

¹ School of Electrical and Computer Engineering, University of Ulsan, Ulsan 680-749, Korea

² Faculty of Physics, University of Education, Hue University, 34 Le Loi Str., Hue City 530000, Vietnam

Sensors 2017, 17(10), 2275; https://doi.org/10.3390/s17102275 - 6 Oct 2017

Cited by 18 | Viewed by 4616

Abstract

In this paper, we consider multiuser simultaneous wireless information and power transfer (SWIPT) for cognitive radio systems where a secondary transmitter (ST) with an antenna array provides information and energy to multiple single-antenna secondary receivers (SRs) equipped with a power splitting (PS) receiving [...] Read more.

In this paper, we consider multiuser simultaneous wireless information and power transfer (SWIPT) for cognitive radio systems where a secondary transmitter (ST) with an antenna array provides information and energy to multiple single-antenna secondary receivers (SRs) equipped with a power splitting (PS) receiving scheme when multiple primary users (PUs) exist. The main objective of the paper is to maximize weighted sum harvested energy for SRs while satisfying their minimum required signal-to-interference-plus-noise ratio (SINR), the limited transmission power at the ST, and the interference threshold of each PU. For the perfect channel state information (CSI), the optimal beamforming vectors and PS ratios are achieved by the proposed PSO-SDR in which semidefinite relaxation (SDR) and particle swarm optimization (PSO) methods are jointly combined. We prove that SDR always has a rank-1 solution, and is indeed tight. For the imperfect CSI with bounded channel vector errors, the upper bound of weighted sum harvested energy (WSHE) is also obtained through the S-Procedure. Finally, simulation results demonstrate that the proposed PSO-SDR has fast convergence and better performance as compared to the other baseline schemes. Full article

(This article belongs to the Special Issue Cognitive Radio Sensing and Sensor Networks)

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24 pages, 9442 KiB

Open AccessArticle

Defect Detection and Segmentation Framework for Remote Field Eddy Current Sensor Data

by Raphael Falque^*

, Teresa Vidal-Calleja

and Jaime Valls Miro

Centre for Autonomous Systems (CB 11.09.300), Faculty of Engineering and Information Technology, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia

Sensors 2017, 17(10), 2276; https://doi.org/10.3390/s17102276 - 6 Oct 2017

Cited by 15 | Viewed by 6483

Abstract

Remote-Field Eddy-Current (RFEC) technology is often used as a Non-Destructive Evaluation (NDE) method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth [...] Read more.

Remote-Field Eddy-Current (RFEC) technology is often used as a Non-Destructive Evaluation (NDE) method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth and shape. For large sections of pipelines, this can be extremely time-consuming if performed manually. Automated approaches are therefore well motivated. In this article, we propose an automated framework to locate and segment defects in individual pipe segments, starting from raw RFEC measurements taken over large pipelines. The framework relies on a novel feature to robustly detect these defects and a segmentation algorithm applied to the deconvolved RFEC signal. The framework is evaluated using both simulated and real datasets, demonstrating its ability to efficiently segment the shape of corrosion defects. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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16 pages, 2481 KiB

Open AccessArticle

Binding Affinity of a Highly Sensitive Au/Ag/Au/Chitosan-Graphene Oxide Sensor Based on Direct Detection of Pb²⁺ and Hg²⁺ Ions

by Nur Hasiba Kamaruddin¹, Ahmad Ashrif A. Bakar^1,*, Nadhratun Naiim Mobarak², Mohd Saiful Dzulkefly Zan¹ and Norhana Arsad¹

¹ Department of Electric, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

² School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Sensors 2017, 17(10), 2277; https://doi.org/10.3390/s17102277 - 6 Oct 2017

Cited by 61 | Viewed by 7322

Abstract

The study of binding affinity is essential in surface plasmon resonance (SPR) sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, [...] Read more.

The study of binding affinity is essential in surface plasmon resonance (SPR) sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, K, for Pb²⁺ and Hg²⁺ ions according to their SPR response using a gold/silver/gold/chitosan–graphene oxide (Au/Ag/Au/CS–GO) sensor for the concentration range of 0.1–5 ppm. The higher affinity of Pb²⁺ to binding with the CS–GO sensor explains the outstanding sensitivity of 2.05 °ppm⁻¹ against 1.66 °ppm⁻¹ of Hg²⁺. The maximum signal-to-noise ratio (SNR) upon detection of Pb²⁺ is 1.53, and exceeds the suggested logical criterion of an SNR. The Au/Ag/Au/CS–GO SPR sensor also exhibits excellent repeatability in Pb²⁺ due to the strong bond between its functional groups and this cation. The adsorption data of Pb²⁺ and Hg²⁺ on the CS–GO sensor fits well with the Langmuir isotherm model where the affinity constant, K, of Pb²⁺ and Hg²⁺ ions is computed. The affinity of Pb²⁺ ions to the Au/Ag/Au/CS–GO sensor is significantly higher than that of Hg²⁺ based on the value of K, 7 × 10⁵ M⁻¹ and 4 × 10⁵ M⁻¹, respectively. The higher shift in SPR angles due to Pb²⁺ and Hg²⁺ compared to Cr³⁺, Cu²⁺ and Zn²⁺ ions also reveals the greater affinity of the CS–GO SPR sensor to them, thus supporting the rationale for obtaining K for these two heavy metals. This study provides a better understanding on the sensing performance of such sensors in detecting heavy metal ions. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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9 pages, 1275 KiB

Open AccessCommunication

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy

by Maciej Andrzej Popenda¹

, Hanna Izabela Stawska¹

, Leszek Mateusz Mazur², Konrad Jakubowski²

, Alexey Kosolapov³, Anton Kolyadin³ and Elżbieta Bereś-Pawlik^1,*

¹ Department of Telecommunications and Teleinformatics, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland

² Advanced Materials Engineering and Modelling Group, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland

³ Fiber Optics Research Center of Russian Academy of Sciences, Moscow 119333, Russia

Sensors 2017, 17(10), 2278; https://doi.org/10.3390/s17102278 - 6 Oct 2017

Cited by 13 | Viewed by 5233

Abstract

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of [...] Read more.

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680–750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author’s best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments. Full article

(This article belongs to the Special Issue Intelligent Sensing Technologies for Nondestructive Evaluation)

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16 pages, 2778 KiB

Open AccessArticle

Self-Taught Learning Based on Sparse Autoencoder for E-Nose in Wound Infection Detection

by Peilin He, Pengfei Jia^*, Siqi Qiao and Shukai Duan

College of Electronic and Information Engineering, Southwest University, Chongqing 400715, China

Sensors 2017, 17(10), 2279; https://doi.org/10.3390/s17102279 - 7 Oct 2017

Cited by 24 | Viewed by 5209

Abstract

For an electronic nose (E-nose) in wound infection distinguishing, traditional learning methods have always needed large quantities of labeled wound infection samples, which are both limited and expensive; thus, we introduce self-taught learning combined with sparse autoencoder and radial basis function (RBF) into [...] Read more.

For an electronic nose (E-nose) in wound infection distinguishing, traditional learning methods have always needed large quantities of labeled wound infection samples, which are both limited and expensive; thus, we introduce self-taught learning combined with sparse autoencoder and radial basis function (RBF) into the field. Self-taught learning is a kind of transfer learning that can transfer knowledge from other fields to target fields, can solve such problems that labeled data (target fields) and unlabeled data (other fields) do not share the same class labels, even if they are from entirely different distribution. In our paper, we obtain numerous cheap unlabeled pollutant gas samples (benzene, formaldehyde, acetone and ethylalcohol); however, labeled wound infection samples are hard to gain. Thus, we pose self-taught learning to utilize these gas samples, obtaining a basis vector θ. Then, using the basis vector θ, we reconstruct the new representation of wound infection samples under sparsity constraint, which is the input of classifiers. We compare RBF with partial least squares discriminant analysis (PLSDA), and reach a conclusion that the performance of RBF is superior to others. We also change the dimension of our data set and the quantity of unlabeled data to search the input matrix that produces the highest accuracy. Full article

(This article belongs to the Special Issue Electronic Tongues and Electronic Noses)

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10 pages, 8812 KiB

Open AccessArticle

A Method for Enhancing the Sensing Distance of a Fingerprint Sensor

by Kyung-Hoon Song^1,2, Jaehuk Choi¹ and Jung-Hoon Chun^1,*

¹ College of Information and Communication Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea

² Advanced Component Technology Group, Mobile Communication Division, Samsung Electronics Ltd., 129 Samsung-ro, Yeongtong-gu, Suwon, Gyeonggi-do 16677, Korea

Sensors 2017, 17(10), 2280; https://doi.org/10.3390/s17102280 - 7 Oct 2017

Cited by 18 | Viewed by 6172

Abstract

In this paper, we describe a method for improving the quality of fingerprint images at long sensing distances by reducing the fringe capacitance formed between a pixel and surrounding fingerprint patterns. Air-walls were applied to the glass attached to a fingerprint sensor for [...] Read more.

In this paper, we describe a method for improving the quality of fingerprint images at long sensing distances by reducing the fringe capacitance formed between a pixel and surrounding fingerprint patterns. Air-walls were applied to the glass attached to a fingerprint sensor for reducing the edge capacitance. Fingerprints and air-wall structures were modeled using a three-dimensional capacitance analysis tool. A prototype was fabricated by stacking glass layers with air-walls with a depth of 50 μm and a pitch of 50 μm on a silicon-type capacitive sensor. Using the results of simulations and prototype experiments, we confirmed that the proposed air-wall structure achieved high enough resolution to distinguish 2.5-lp/mm fingerprint patterns at a sensing distance of 300 μm or longer, and its contrast improved from 0.59 to 0.98. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 654 KiB

Open AccessArticle

Novel Semi-Parametric Algorithm for Interference-Immune Tunable Absorption Spectroscopy Gas Sensing

by Umberto Michelucci^1,† and Francesca Venturini^2,*,†

¹ https://udata.science, Dübendorf 8600, Switzerland

² Institute of Applied Mathematics and Physics, Zurich University of Applied Sciences, Winterthur 8401, Switzerland

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2281; https://doi.org/10.3390/s17102281 - 7 Oct 2017

Cited by 4 | Viewed by 4218

Abstract

One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance [...] Read more.

One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance and alignment of the optical elements, they are affected by temperature changes and mechanical disturbances, giving rise to a drift of the signal. In this work, we present a novel semi-parametric algorithm that allows the extraction of a signal, like the spectroscopic absorption line of a gas molecule, from a background containing arbitrary disturbances, without having to make any assumption on the functional form of these disturbances. The algorithm is applied first to simulated data and then to oxygen absorption measurements in the presence of strong fringes.To the best of the authors’ knowledge, the algorithm enables an unprecedented accuracy particularly if the fringes have a free spectral range and amplitude comparable to those of the signal to be detected. The described method presents the advantage of being based purely on post processing, and to be of extremely straightforward implementation if the functional form of the Fourier transform of the signal is known. Therefore, it has the potential to enable interference-immune absorption spectroscopy. Finally, its relevance goes beyond absorption spectroscopy for gas sensing, since it can be applied to any kind of spectroscopic data. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 30634 KiB

Open AccessArticle

Improving the Accuracy and Training Speed of Motor Imagery Brain–Computer Interfaces Using Wavelet-Based Combined Feature Vectors and Gaussian Mixture Model-Supervectors

by David Lee

, Sang-Hoon Park

and Sang-Goog Lee^*

Department of Media Engineering, Catholic University of Korea, 43-1, Yeoggok 2-dong, Wonmmi-gu, Bucheon-si, Gyeonggi-do 14662, Korea

Sensors 2017, 17(10), 2282; https://doi.org/10.3390/s17102282 - 7 Oct 2017

Cited by 17 | Viewed by 5808

Abstract

In this paper, we propose a set of wavelet-based combined feature vectors and a Gaussian mixture model (GMM)-supervector to enhance training speed and classification accuracy in motor imagery brain–computer interfaces. The proposed method is configured as follows: first, wavelet transforms are applied to [...] Read more.

In this paper, we propose a set of wavelet-based combined feature vectors and a Gaussian mixture model (GMM)-supervector to enhance training speed and classification accuracy in motor imagery brain–computer interfaces. The proposed method is configured as follows: first, wavelet transforms are applied to extract the feature vectors for identification of motor imagery electroencephalography (EEG) and principal component analyses are used to reduce the dimensionality of the feature vectors and linearly combine them. Subsequently, the GMM universal background model is trained by the expectation–maximization (EM) algorithm to purify the training data and reduce its size. Finally, a purified and reduced GMM-supervector is used to train the support vector machine classifier. The performance of the proposed method was evaluated for three different motor imagery datasets in terms of accuracy, kappa, mutual information, and computation time, and compared with the state-of-the-art algorithms. The results from the study indicate that the proposed method achieves high accuracy with a small amount of training data compared with the state-of-the-art algorithms in motor imagery EEG classification. Full article

(This article belongs to the Special Issue Novel Sensors for Bioimaging)

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11 pages, 5309 KiB

Open AccessArticle

A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas

by Nayyer Abbas Zaidi^1,2,*, Muhammad Waseem Tahir^1,2

, Michael J. Vellekoop² and Walter Lang^1,2

¹ International Graduate School for Dynamics in Logistics (IGS), University of Bremen, 28359 Bremen, Germany

² Institute for Microsensors, -Actuators and -Systems (IMSAS), University of Bremen, 28334 Bremen, Germany

Sensors 2017, 17(10), 2283; https://doi.org/10.3390/s17102283 - 7 Oct 2017

Cited by 31 | Viewed by 7742

Abstract

Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented [...] Read more.

Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system. Full article

(This article belongs to the Section Chemical Sensors)

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22 pages, 3702 KiB

Open AccessReview

Gyroscope Technology and Applications: A Review in the Industrial Perspective

by Vittorio M. N. Passaro^1,*, Antonello Cuccovillo², Lorenzo Vaiani², Martino De Carlo¹ and Carlo Edoardo Campanella^1,2

¹ Photonics Research Group, Dipartimento di Ingegneria Elettrica e dell’Informazione, Politecnico di Bari, via E. Orabona n. 4, 70125 Bari, Italy

² QOpSyS SRL, Via Matteotti 23, Gioia del Colle, 70023 Bari, Italy

Sensors 2017, 17(10), 2284; https://doi.org/10.3390/s17102284 - 7 Oct 2017

Cited by 383 | Viewed by 38715

Abstract

This paper is an overview of current gyroscopes and their roles based on their applications. The considered gyroscopes include mechanical gyroscopes and optical gyroscopes at macro- and micro-scale. Particularly, gyroscope technologies commercially available, such as Mechanical Gyroscopes, silicon MEMS Gyroscopes, Ring Laser Gyroscopes [...] Read more.

This paper is an overview of current gyroscopes and their roles based on their applications. The considered gyroscopes include mechanical gyroscopes and optical gyroscopes at macro- and micro-scale. Particularly, gyroscope technologies commercially available, such as Mechanical Gyroscopes, silicon MEMS Gyroscopes, Ring Laser Gyroscopes (RLGs) and Fiber-Optic Gyroscopes (FOGs), are discussed. The main features of these gyroscopes and their technologies are linked to their performance. Full article

(This article belongs to the Special Issue Integrated Photonic Technologies for Sensing Applications)

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18 pages, 5427 KiB

Open AccessArticle

High-Accuracy Decoupling Estimation of the Systematic Coordinate Errors of an INS and Intensified High Dynamic Star Tracker Based on the Constrained Least Squares Method

by Jie Jiang, Wenbo Yu^* and Guangjun Zhang

Key Laboratory of Precision Opto-Mechatronics Technology, Ministry of Education, School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, No. 37 Xueyuan Road, Haidian District, Beijing 100191, China

Sensors 2017, 17(10), 2285; https://doi.org/10.3390/s17102285 - 7 Oct 2017

Cited by 9 | Viewed by 4964

Abstract

Navigation accuracy is one of the key performance indicators of an inertial navigation system (INS). Requirements for an accuracy assessment of an INS in a real work environment are exceedingly urgent because of enormous differences between real work and laboratory test environments. An [...] Read more.

Navigation accuracy is one of the key performance indicators of an inertial navigation system (INS). Requirements for an accuracy assessment of an INS in a real work environment are exceedingly urgent because of enormous differences between real work and laboratory test environments. An attitude accuracy assessment of an INS based on the intensified high dynamic star tracker (IHDST) is particularly suitable for a real complex dynamic environment. However, the coupled systematic coordinate errors of an INS and the IHDST severely decrease the attitude assessment accuracy of an INS. Given that, a high-accuracy decoupling estimation method of the above systematic coordinate errors based on the constrained least squares (CLS) method is proposed in this paper. The reference frame of the IHDST is firstly converted to be consistent with that of the INS because their reference frames are completely different. Thereafter, the decoupling estimation model of the systematic coordinate errors is established and the CLS-based optimization method is utilized to estimate errors accurately. After compensating for error, the attitude accuracy of an INS can be assessed based on IHDST accurately. Both simulated experiments and real flight experiments of aircraft are conducted, and the experimental results demonstrate that the proposed method is effective and shows excellent performance for the attitude accuracy assessment of an INS in a real work environment. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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16 pages, 2912 KiB

Open AccessArticle

Cooperative Localization for Multi-AUVs Based on GM-PHD Filters and Information Entropy Theory

by Lichuan Zhang, Tonghao Wang^*, Feihu Zhang^*

and Demin Xu

School of Marine Science and Technology, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an 710072, China

Sensors 2017, 17(10), 2286; https://doi.org/10.3390/s17102286 - 8 Oct 2017

Cited by 16 | Viewed by 4605

Abstract

Cooperative localization (CL) is considered a promising method for underwater localization with respect to multiple autonomous underwater vehicles (multi-AUVs). In this paper, we proposed a CL algorithm based on information entropy theory and the probability hypothesis density (PHD) filter, aiming to enhance the [...] Read more.

Cooperative localization (CL) is considered a promising method for underwater localization with respect to multiple autonomous underwater vehicles (multi-AUVs). In this paper, we proposed a CL algorithm based on information entropy theory and the probability hypothesis density (PHD) filter, aiming to enhance the global localization accuracy of the follower. In the proposed framework, the follower carries lower cost navigation systems, whereas the leaders carry better ones. Meanwhile, the leaders acquire the followers’ observations, including both measurements and clutter. Then, the PHD filters are utilized on the leaders and the results are communicated to the followers. The followers then perform weighted summation based on all received messages and obtain a final positioning result. Based on the information entropy theory and the PHD filter, the follower is able to acquire a precise knowledge of its position. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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14 pages, 2351 KiB

Open AccessArticle

In-Season Yield Prediction of Cabbage with a Hand-Held Active Canopy Sensor

by Rongting Ji^1,2, Ju Min¹, Yuan Wang¹, Hu Cheng^1,2, Hailin Zhang³

and Weiming Shi^1,*

¹ State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China

² University of Chinese Academy of Sciences, Beijing 100049, China

³ Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078-6028, USA

Sensors 2017, 17(10), 2287; https://doi.org/10.3390/s17102287 - 8 Oct 2017

Cited by 23 | Viewed by 5388

Abstract

Efficient and precise yield prediction is critical to optimize cabbage yields and guide fertilizer application. A two-year field experiment was conducted to establish a yield prediction model for cabbage by using the Greenseeker hand-held optical sensor. Two cabbage cultivars (Jianbao and Pingbao) were [...] Read more.

Efficient and precise yield prediction is critical to optimize cabbage yields and guide fertilizer application. A two-year field experiment was conducted to establish a yield prediction model for cabbage by using the Greenseeker hand-held optical sensor. Two cabbage cultivars (Jianbao and Pingbao) were used and Jianbao cultivar was grown for 2 consecutive seasons but Pingbao was only grown in the second season. Four chemical nitrogen application rates were implemented: 0, 80, 140, and 200 kg·N·ha⁻¹. Normalized difference vegetation index (NDVI) was collected 20, 50, 70, 80, 90, 100, 110, 120, 130, and 140 days after transplanting (DAT). Pearson correlation analysis and regression analysis were performed to identify the relationship between the NDVI measurements and harvested yields of cabbage. NDVI measurements obtained at 110 DAT were significantly correlated to yield and explained 87–89% and 75–82% of the cabbage yield variation of Jianbao cultivar over the two-year experiment and 77–81% of the yield variability of Pingbao cultivar. Adjusting the yield prediction models with CGDD (cumulative growing degree days) could make remarkable improvement to the accuracy of the prediction model and increase the determination coefficient to 0.82, while the modification with DFP (days from transplanting when GDD > 0) values did not. The integrated exponential yield prediction equation was better than linear or quadratic functions and could accurately make in-season estimation of cabbage yields with different cultivars between years. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 2175 KiB

Open AccessArticle

Adaptive Integration of the Compressed Algorithm of CS and NPC for the ECG Signal Compressed Algorithm in VLSI Implementation

by Yun-Hua Tseng^1,2, Yuan-Ho Chen^2,3,*

and Chih-Wen Lu^1,*

¹ Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan

² Department of Electronic Engineering, Chang Gung University, Taoyuan 333, Taiwan

³ Department of Radiation Oncology, Chang Gung Memorial Hospital-Linkou, Taoyuan 333, Taiwan

Sensors 2017, 17(10), 2288; https://doi.org/10.3390/s17102288 - 9 Oct 2017

Cited by 16 | Viewed by 5145

Abstract

Compressed sensing (CS) is a promising approach to the compression and reconstruction of electrocardiogram (ECG) signals. It has been shown that following reconstruction, most of the changes between the original and reconstructed signals are distributed in the Q, R, and S waves (QRS) [...] Read more.

Compressed sensing (CS) is a promising approach to the compression and reconstruction of electrocardiogram (ECG) signals. It has been shown that following reconstruction, most of the changes between the original and reconstructed signals are distributed in the Q, R, and S waves (QRS) region. Furthermore, any increase in the compression ratio tends to increase the magnitude of the change. This paper presents a novel approach integrating the near-precise compressed (NPC) and CS algorithms. The simulation results presented notable improvements in signal-to-noise ratio (SNR) and compression ratio (CR). The efficacy of this approach was verified by fabricating a highly efficient low-cost chip using the Taiwan Semiconductor Manufacturing Company’s (TSMC) 0.18-μm Complementary Metal-Oxide-Semiconductor (CMOS) technology. The proposed core has an operating frequency of 60 MHz and gate counts of 2.69 K. Full article

(This article belongs to the Special Issue Advanced Electronic Devices, Circuits, and Signal Processing for Biomedical Sensors Application)

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15 pages, 6596 KiB

Open AccessReview

Wireless Biological Electronic Sensors

by Yue Cui

College of Engineering, Peking University, Beijing 100871, China

Sensors 2017, 17(10), 2289; https://doi.org/10.3390/s17102289 - 9 Oct 2017

Cited by 18 | Viewed by 7152

Abstract

The development of wireless biological electronic sensors could open up significant advances for both fundamental studies and practical applications in a variety of areas, including medical diagnosis, environmental monitoring, and defense applications. One of the major challenges in the development of wireless bioelectronic [...] Read more.

The development of wireless biological electronic sensors could open up significant advances for both fundamental studies and practical applications in a variety of areas, including medical diagnosis, environmental monitoring, and defense applications. One of the major challenges in the development of wireless bioelectronic sensors is the successful integration of biosensing units and wireless signal transducers. In recent years, there are a few types of wireless communication systems that have been integrated with biosensing systems to construct wireless bioelectronic sensors. To successfully construct wireless biological electronic sensors, there are several interesting questions: What types of biosensing transducers can be used in wireless bioelectronic sensors? What types of wireless systems can be integrated with biosensing transducers to construct wireless bioelectronic sensors? How are the electrical sensing signals generated and transmitted? This review will highlight the early attempts to address these questions in the development of wireless biological electronic sensors. Full article

(This article belongs to the Section Biosensors)

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17 pages, 511 KiB

Open AccessArticle

Joint Power Charging and Routing in Wireless Rechargeable Sensor Networks

by Jie Jia^1,2, Jian Chen^1,2,*, Yansha Deng³, Xingwei Wang^1,2 and Abdol-Hamid Aghvami³

¹ Key Laboratory of Medical Image Computing of Northeastern University, Ministry of Education, Shenyang 110819, China

² School of Computer Science and Engineering, Northeastern University, Shenyang 110819, China

³ Department of Informatics, King’s College London, London WC2R 2LS, UK

Sensors 2017, 17(10), 2290; https://doi.org/10.3390/s17102290 - 9 Oct 2017

Cited by 22 | Viewed by 5736

Abstract

The development of wireless power transfer (WPT) technology has inspired the transition from traditional battery-based wireless sensor networks (WSNs) towards wireless rechargeable sensor networks (WRSNs). While extensive efforts have been made to improve charging efficiency, little has been done for routing optimization. In [...] Read more.

The development of wireless power transfer (WPT) technology has inspired the transition from traditional battery-based wireless sensor networks (WSNs) towards wireless rechargeable sensor networks (WRSNs). While extensive efforts have been made to improve charging efficiency, little has been done for routing optimization. In this work, we present a joint optimization model to maximize both charging efficiency and routing structure. By analyzing the structure of the optimization model, we first decompose the problem and propose a heuristic algorithm to find the optimal charging efficiency for the predefined routing tree. Furthermore, by coding the many-to-one communication topology as an individual, we further propose to apply a genetic algorithm (GA) for the joint optimization of both routing and charging. The genetic operations, including tree-based recombination and mutation, are proposed to obtain a fast convergence. Our simulation results show that the heuristic algorithm reduces the number of resident locations and the total moving distance. We also show that our proposed algorithm achieves a higher charging efficiency compared with existing algorithms. Full article

(This article belongs to the Special Issue Wireless Rechargeable Sensor Networks)

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10 pages, 1822 KiB

Open AccessArticle

Determination of Cadmium in Brown Rice Samples by Fluorescence Spectroscopy Using a Fluoroionophore after Purification of Cadmium by Anion Exchange Resin

by Akira Hafuka¹, Akiyoshi Takitani², Hiroko Suzuki³, Takuya Iwabuchi³, Masahiro Takahashi², Satoshi Okabe² and Hisashi Satoh^2,*

¹ Department of Integrated Science and Engineering for Sustainable Society, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan

² Division of Environmental Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan

³ Department of Research and Development, Metallogenics Co., Ltd., Chiba 260-0856, Japan

Sensors 2017, 17(10), 2291; https://doi.org/10.3390/s17102291 - 9 Oct 2017

Cited by 20 | Viewed by 4931

Abstract

Simple analytical methods are needed for determining the cadmium (Cd) content of brown rice samples. In the present study, we developed a new analytical procedure consisting of the digestion of rice using HCl, Cd purification using anion exchange resin, and then determining the [...] Read more.

Simple analytical methods are needed for determining the cadmium (Cd) content of brown rice samples. In the present study, we developed a new analytical procedure consisting of the digestion of rice using HCl, Cd purification using anion exchange resin, and then determining the Cd content using fluorescence spectroscopy. Digestion with 0.1 M HCl for 10 min at room temperature was sufficient to extract Cd from the ground rice samples. The Cd in the extract was successfully purified in preference to other metals using Dowex 1X8 chloride form resin. Low concentrations of Cd in the eluate could be determined using fluorescence spectroscopy with a fluoroionophore. Overall, the actual limit of quantification value for the Cd content in rice was about 0.1 mg-Cd/kg-rice, which was sufficiently low compared with the regulatory value (0.4 mg-Cd/kg-rice) given by the Codex Alimentarius Commission. We analyzed authentic brown rice samples using our new analytical procedure and the results agreed well with those determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Since the fluoroionophore recognized Zn²⁺ and Hg²⁺ as well as Cd²⁺, a sample containing high concentration of Zn²⁺ or Hg²⁺ might cause a false positive result. Full article

(This article belongs to the Special Issue Fluorescent Probes and Sensors)

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15 pages, 2460 KiB

Open AccessArticle

Polymethacrylate Coated Electrospun PHB Fibers as a Functionalized Platform for Bio-Diagnostics: Confirmation Analysis on the Presence of Immobilized IgG Antibodies against Dengue Virus

by Samira Hosseini¹, Pedram Azari^2,3

, Martín F. Jiménez-Moreno¹, Aida Rodriguez-Garcia⁴, Belinda Pingguan-Murphy^2,*, Marc J. Madou^5,6 and Sergio O. Martínez-Chapa^1,*

¹ Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey 64849, NL, Mexico

² Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia

³ Centre for Applied Biomechanics, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia

⁴ Instituto de Biotecnologia, Facultad de Ciencias Biologicas, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza 66455, Nuevo Leon, Mexico

⁵ Department of Biomedical Engineering, University of California, Irvine, CA 92697, USA

⁶ Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA 92697, USA

Sensors 2017, 17(10), 2292; https://doi.org/10.3390/s17102292 - 9 Oct 2017

Cited by 14 | Viewed by 5532

Abstract

In this article, a combination of far field electrospinning (FFES) and free-radical polymerization has been used to create a unique platform for protein immobilization via the physical attachment of biomolecules to the surface of the fiber mats. The large specific surface area of [...] Read more.

In this article, a combination of far field electrospinning (FFES) and free-radical polymerization has been used to create a unique platform for protein immobilization via the physical attachment of biomolecules to the surface of the fiber mats. The large specific surface area of the fibers with its tailored chemistry provides a desirable platform for effective analyte-surface interaction. The detailed analysis of protein immobilization on a newly developed bio-receptive surface plays a vital role to gauge its advantages in bio-diagnostic applications. We relied on scanning electron microscopy (SEM), diameter range analysis, and X-ray photoelectron spectroscopy (XPS), along with thermal gravimetric analysis (TGA), water-in-air contact angle analysis (WCA), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) to study our developed platforms and to provide valuable information regarding the presence of biomolecular entities on the surface. Detailed analyses of the fiber mats before and after antibody immobilization have shown obvious changes on the surface of the bioreceptive surface including: (i) an additional peak corresponding to the presence of an antibody in TGA analysis; (ii) extra FTIR peaks corresponding to the presence of antibodies on the coated fiber platforms; and (iii) a clear alteration in surface roughness recorded by AFM analysis. Confirmation analyses on protein immobilization are of great importance as they underlay substantial grounds for various biosensing applications. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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28 pages, 1060 KiB

Open AccessArticle

An Efficient and QoS Supported Multichannel MAC Protocol for Vehicular Ad Hoc Networks

by Caixia Song^1,2,*

, Guozhen Tan¹ and Chao Yu¹

¹ College of Computer Science and Technology, Dalian University of Technology, Dalian 116024, China

² College of Science and Information, Qingdao Agricultural University, Qingdao 266109, China

Sensors 2017, 17(10), 2293; https://doi.org/10.3390/s17102293 - 9 Oct 2017

Cited by 19 | Viewed by 4378

Abstract

Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety (transport efficiency and infotainment) applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. Different types of applications require different levels Quality-of-Service (QoS) support. Recently, transport efficiency and [...] Read more.

Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety (transport efficiency and infotainment) applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. Different types of applications require different levels Quality-of-Service (QoS) support. Recently, transport efficiency and infotainment applications (e.g., electronic map download and Internet access) have received more and more attention, and this kind of applications is expected to become a big market driver in a near future. In this paper, we propose an Efficient and QoS supported Multichannel Medium Access Control (EQM-MAC) protocol for VANETs in a highway environment. The EQM-MAC protocol utilizes the service channel resources for non-safety message transmissions during the whole synchronization interval, and it dynamically adjusts minimum contention window size for different non-safety services according to the traffic conditions. Theoretical model analysis and extensive simulation results show that the EQM-MAC protocol can support QoS services, while ensuring the high saturation throughput and low transmission delay for non-safety applications. Full article

(This article belongs to the Special Issue Smart Vehicular Mobile Sensing)

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21 pages, 3091 KiB

Open AccessArticle

Augmented Reality as a Telemedicine Platform for Remote Procedural Training

by Shiyao Wang^1,*, Michael Parsons^2,*, Jordan Stone-McLean², Peter Rogers², Sarah Boyd², Kristopher Hoover³, Oscar Meruvia-Pastor^1,*, Minglun Gong^1,* and Andrew Smith^2,*

¹ Department of Computer Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, Canada

² Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1B 3V6, Canada

³ Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John’s, NL A1B 3X5, Canada

Sensors 2017, 17(10), 2294; https://doi.org/10.3390/s17102294 - 10 Oct 2017

Cited by 165 | Viewed by 14313

Abstract

Traditionally, rural areas in many countries are limited by a lack of access to health care due to the inherent challenges associated with recruitment and retention of healthcare professionals. Telemedicine, which uses communication technology to deliver medical services over distance, is an economical [...] Read more.

Traditionally, rural areas in many countries are limited by a lack of access to health care due to the inherent challenges associated with recruitment and retention of healthcare professionals. Telemedicine, which uses communication technology to deliver medical services over distance, is an economical and potentially effective way to address this problem. In this research, we develop a new telepresence application using an Augmented Reality (AR) system. We explore the use of the Microsoft HoloLens to facilitate and enhance remote medical training. Intrinsic advantages of AR systems enable remote learners to perform complex medical procedures such as Point of Care Ultrasound (PoCUS) without visual interference. This research uses the HoloLens to capture the first-person view of a simulated rural emergency room (ER) through mixed reality capture (MRC) and serves as a novel telemedicine platform with remote pointing capabilities. The mentor’s hand gestures are captured using a Leap Motion and virtually displayed in the AR space of the HoloLens. To explore the feasibility of the developed platform, twelve novice medical trainees were guided by a mentor through a simulated ultrasound exploration in a trauma scenario, as part of a pilot user study. The study explores the utility of the system from the trainees, mentor, and objective observers’ perspectives and compares the findings to that of a more traditional multi-camera telemedicine solution. The results obtained provide valuable insight and guidance for the development of an AR-supported telemedicine platform. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Canada 2017)

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20 pages, 3775 KiB

Open AccessArticle

Sparse Aperture InISAR Imaging via Sequential Multiple Sparse Bayesian Learning

by Shuanghui Zhang^*, Yongxiang Liu and Xiang Li

School of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China

Sensors 2017, 17(10), 2295; https://doi.org/10.3390/s17102295 - 10 Oct 2017

Cited by 7 | Viewed by 3844

Abstract

Interferometric inverse synthetic aperture radar (InISAR) imaging for sparse-aperture (SA) data is still a challenge, because the similarity and matched degree between ISAR images from different channels are destroyed by the SA data. To deal with this problem, this paper proposes a novel [...] Read more.

Interferometric inverse synthetic aperture radar (InISAR) imaging for sparse-aperture (SA) data is still a challenge, because the similarity and matched degree between ISAR images from different channels are destroyed by the SA data. To deal with this problem, this paper proposes a novel SA–InISAR imaging method, which jointly reconstructs 2-dimensional (2-D) ISAR images from different channels through multiple response sparse Bayesian learning (M-SBL), a modification of sparse Bayesian learning (SBL), to achieve sparse recovery for multiple measurement vectors (MMV). We note that M-SBL suffers a heavy computational burden because it involves large matrix inversion. A computationally efficient M-SBL is proposed, which, proceeding in a sequential manner to avoid the time-consuming large matrix inversion, is denoted as sequential multiple sparse Bayesian learning (SM-SBL). Thereafter, SM-SBL is introduced to InISAR imaging to simultaneously reconstruct the ISAR images from different channels. Numerous experimental results validate that the proposed SM-SBL-based InISAR imaging algorithm performs superiorly against the traditional single-channel sparse-signal recovery (SSR)-based InISAR imaging methods in terms of noise suppression, outlier reduction and 3-dimensional (3-D) geometry estimation. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 1214 KiB

Open AccessArticle

An IoT-Based Solution for Monitoring a Fleet of Educational Buildings Focusing on Energy Efficiency

by Dimitrios Amaxilatis^1,*,†, Orestis Akrivopoulos^2,†, Georgios Mylonas^1,†

and Ioannis Chatzigiannakis^3,†

¹ Computer Technology Institute and Press “Diophantus”, Patras 26504, Greece

² Sparkworks Ltd., Altrincham WA14 1RP, UK

³ Department of Computer, Control and Informatics Engineering, La Sapienza University, Rome 00185, Italy

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2296; https://doi.org/10.3390/s17102296 - 10 Oct 2017

Cited by 68 | Viewed by 10743

Abstract

Raising awareness among young people and changing their behaviour and habits concerning energy usage is key to achieving sustained energy saving. Additionally, young people are very sensitive to environmental protection so raising awareness among children is much easier than with any other group [...] Read more.

Raising awareness among young people and changing their behaviour and habits concerning energy usage is key to achieving sustained energy saving. Additionally, young people are very sensitive to environmental protection so raising awareness among children is much easier than with any other group of citizens. This work examines ways to create an innovative Information & Communication Technologies (ICT) ecosystem (including web-based, mobile, social and sensing elements) tailored specifically for school environments, taking into account both the users (faculty, staff, students, parents) and school buildings, thus motivating and supporting young citizens’ behavioural change to achieve greater energy efficiency. A mixture of open-source IoT hardware and proprietary platforms on the infrastructure level, are currently being utilized for monitoring a fleet of 18 educational buildings across 3 countries, comprising over 700 IoT monitoring points. Hereon presented is the system’s high-level architecture, as well as several aspects of its implementation, related to the application domain of educational building monitoring and energy efficiency. The system is developed based on open-source technologies and services in order to make it capable of providing open IT-infrastructure and support from different commercial hardware/sensor vendors as well as open-source solutions. The system presented can be used to develop and offer new app-based solutions that can be used either for educational purposes or for managing the energy efficiency of the building. The system is replicable and adaptable to settings that may be different than the scenarios envisioned here (e.g., targeting different climate zones), different IT infrastructures and can be easily extended to accommodate integration with other systems. The overall performance of the system is evaluated in real-world environment in terms of scalability, responsiveness and simplicity. Full article

(This article belongs to the Special Issue Advances in Sensors for Sustainable Smart Cities and Smart Buildings)

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21 pages, 12474 KiB

Open AccessArticle

New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Polymer Complex

by Ivona Jerkovic^1,*, Vladan Koncar² and Ana Marija Grancaric¹

¹ Department of Textile Chemistry and Ecology, University of Zagreb Faculty of Textile Technology, 10000 Zagreb, Croatia

² Ecole Nationale Supérieure des Arts et Industries Textiles, GEMTEX Laboratory, 59056 Roubaix, France

Sensors 2017, 17(10), 2297; https://doi.org/10.3390/s17102297 - 10 Oct 2017

Cited by 26 | Viewed by 5649

Abstract

Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart [...] Read more.

Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart textile structures seems to be a very promising solution for in situ structural health monitoring of composite parts. In order to optimize composites’ quality and their lifetime all the production steps have to be monitored in real time. Textile sensors embedded in the composite reinforcement and having the same mechanical properties as the yarns used to make the reinforcement exhibit actuating and sensing capabilities. This paper presents a new generation of textile fibrous sensors based on the conductive polymer complex poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) developed by an original roll to roll coating method. Conductive coating for yarn treatment was defined according to the preliminary study of percolation threshold of this polymer complex. The percolation threshold determination was based on conductive dry films’ electrical properties analysis, in order to develop highly sensitive sensors. A novel laboratory equipment was designed and produced for yarn coating to ensure effective and equally distributed coating of electroconductive polymer without distortion of textile properties. The electromechanical properties of the textile fibrous sensors confirmed their suitability for in situ structural damages detection of textile reinforced thermoplastic composites in real time. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 19968 KiB

Open AccessArticle

Efficient Usage of Dense GNSS Networks in Central Europe for the Visualization and Investigation of Ionospheric TEC Variations

by Grzegorz Nykiel^1,*

, Yevgen M. Zanimonskiy², Yuri M. Yampolski² and Mariusz Figurski¹

¹ Faculty of Civil and Environmental Engineering, Gdansk University of Technology, 80-233 Gdańsk, Poland

² Institute of Radio Astronomy, National Academy of Sciences of Ukraine, 61002 Kharkiv, Ukraine

Sensors 2017, 17(10), 2298; https://doi.org/10.3390/s17102298 - 10 Oct 2017

Cited by 35 | Viewed by 6319

Abstract

The technique of the orthogonal projection of ionosphere electronic content variations for mapping total electron content (TEC) allows us to visualize ionospheric irregularities. For the reconstruction of global ionospheric characteristics, numerous global navigation satellite system (GNSS) receivers located in different regions of the [...] Read more.

The technique of the orthogonal projection of ionosphere electronic content variations for mapping total electron content (TEC) allows us to visualize ionospheric irregularities. For the reconstruction of global ionospheric characteristics, numerous global navigation satellite system (GNSS) receivers located in different regions of the Earth are used as sensors. We used dense GNSS networks in central Europe to detect and investigate a special type of plasma inhomogeneities, called travelling ionospheric disturbances (TID). Such use of GNSS sensors allows us to reconstruct the main TID parameters, such as spatial dimensions, velocities, and directions of their movement. The paper gives examples of the restoration of dynamic characteristics of ionospheric irregularities for quiet and disturbed geophysical conditions. Special attention is paid to the dynamics of ionospheric disturbances stimulated by the magnetic storms of two St. Patrick’s Days (17 March 2013 and 2015). Additional opportunities for the remote sensing of the ionosphere with the use of dense regional networks of GNSS receiving sensors have been noted too. Full article

(This article belongs to the Section Remote Sensors)

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19 pages, 1072 KiB

Open AccessArticle

A Straight Skeleton Based Connectivity Restoration Strategy in the Presence of Obstacles for WSNs

by Xiaoding Wang^1,2, Li Xu^1,* and Shuming Zhou¹

¹ School of Mathematics and Computer Science, Fujian Normal University, Fuzhou 350007, China

² School of Online and Continuing Education, Fujian University of Technology, Fuzhou 350118, China

Sensors 2017, 17(10), 2299; https://doi.org/10.3390/s17102299 - 10 Oct 2017

Cited by 7 | Viewed by 3442

Abstract

Connectivity has significance in both of data collection and aggregation for Wireless Sensor Networks (WSNs). Once the connectivity is lost, relay nodes are deployed to build a Steiner Minimal Tree (SMT) such that the inter-component connection is reestablished. In recent years, there has [...] Read more.

Connectivity has significance in both of data collection and aggregation for Wireless Sensor Networks (WSNs). Once the connectivity is lost, relay nodes are deployed to build a Steiner Minimal Tree (SMT) such that the inter-component connection is reestablished. In recent years, there has been a growing interest in connectivity restoration problems. In previous works, the deployment area of a WSN is assumed to be flat without obstacles. However, such an assumption is not realistic. In addition, most of the existing strategies chose the representative of each component, which serves as the starting point of relay node deployment during the connectivity restoration, either in a random way or in the shortest-distance based manner. In fact, both ways of representative selection could potentially increase the length of the SMT such that more relay nodes are required. In this paper, a novel connectivity restoration strategy is proposed—Obstacle–Avoid connectivity restoration strategy based on Straight Skeletons (OASS), which employs both the polygon based representative selection with the presence of obstacles and the straight skeleton based SMT establishment. The OASS is proved to be a 3-

o p t

approximation algorithm with the complexity of

O (n log n)

, and the approximation ratio can reduce to

\frac{3 \sqrt{3}}{2}

while it satisfies a certain condition. The theoretical analysis and simulations show that the performance of the OASS is better than other strategies in terms of the relay count and the quality of the established topology (i.e., distances between components, delivery latency and balanced traffic load) as well. Full article

(This article belongs to the Section Sensor Networks)

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36 pages, 9559 KiB

Open AccessReview

Biosensing Using Magnetic Particle Detection Techniques

by Yi-Ting Chen, Arati G. Kolhatkar, Oussama Zenasni, Shoujun Xu^* and T. Randall Lee^*

Department of Chemistry and the Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA

Sensors 2017, 17(10), 2300; https://doi.org/10.3390/s17102300 - 10 Oct 2017

Cited by 151 | Viewed by 16818

Abstract

Magnetic particles are widely used as signal labels in a variety of biological sensing applications, such as molecular detection and related strategies that rely on ligand-receptor binding. In this review, we explore the fundamental concepts involved in designing magnetic particles for biosensing applications [...] Read more.

Magnetic particles are widely used as signal labels in a variety of biological sensing applications, such as molecular detection and related strategies that rely on ligand-receptor binding. In this review, we explore the fundamental concepts involved in designing magnetic particles for biosensing applications and the techniques used to detect them. First, we briefly describe the magnetic properties that are important for bio-sensing applications and highlight the associated key parameters (such as the starting materials, size, functionalization methods, and bio-conjugation strategies). Subsequently, we focus on magnetic sensing applications that utilize several types of magnetic detection techniques: spintronic sensors, nuclear magnetic resonance (NMR) sensors, superconducting quantum interference devices (SQUIDs), sensors based on the atomic magnetometer (AM), and others. From the studies reported, we note that the size of the MPs is one of the most important factors in choosing a sensing technique. Full article

(This article belongs to the Special Issue GMR and TMR Sensors)

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12 pages, 2085 KiB

Open AccessArticle

Validation of Foot Placement Locations from Ankle Data of a Kinect v2 Sensor

by Daphne Geerse^1,2,*, Bert Coolen¹, Detmar Kolijn¹ and Melvyn Roerdink¹

¹ Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands

² Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands

Sensors 2017, 17(10), 2301; https://doi.org/10.3390/s17102301 - 10 Oct 2017

Cited by 18 | Viewed by 5236

Abstract

The Kinect v2 sensor may be a cheap and easy to use sensor to quantify gait in clinical settings, especially when applied in set-ups integrating multiple Kinect sensors to increase the measurement volume. Reliable estimates of foot placement locations are required to quantify [...] Read more.

The Kinect v2 sensor may be a cheap and easy to use sensor to quantify gait in clinical settings, especially when applied in set-ups integrating multiple Kinect sensors to increase the measurement volume. Reliable estimates of foot placement locations are required to quantify spatial gait parameters. This study aimed to systematically evaluate the effects of distance from the sensor, side and step length on estimates of foot placement locations based on Kinect’s ankle body points. Subjects (n = 12) performed stepping trials at imposed foot placement locations distanced 2 m or 3 m from the Kinect sensor (distance), for left and right foot placement locations (side), and for five imposed step lengths. Body points’ time series of the lower extremities were recorded with a Kinect v2 sensor, placed frontoparallelly on the left side, and a gold-standard motion-registration system. Foot placement locations, step lengths, and stepping accuracies were compared between systems using repeated-measures ANOVAs, agreement statistics and two one-sided t-tests to test equivalence. For the right side at the 2 m distance from the sensor we found significant between-systems differences in foot placement locations and step lengths, and evidence for nonequivalence. This distance by side effect was likely caused by differences in body orientation relative to the Kinect sensor. It can be reduced by using Kinect’s higher-dimensional depth data to estimate foot placement locations directly from the foot’s point cloud and/or by using smaller inter-sensor distances in the case of a multi-Kinect v2 set-up to estimate foot placement locations at greater distances from the sensor. Full article

(This article belongs to the Section Physical Sensors)

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25 pages, 3945 KiB

Open AccessArticle

An IoT-Based Computational Framework for Healthcare Monitoring in Mobile Environments

by Higinio Mora^1,*

, David Gil¹

, Rafael Muñoz Terol²

, Jorge Azorín¹

and Julian Szymanski³

¹ Department of Computer Science Technology and Computation, University of Alicante, 03690 Alicante, Spain

² Department of Software and Computing Systems, University of Alicante, 03690 Alicante, Spain

³ Department of Computer Systems Architecture, Gdansk University of Technology, 80-233 Gdansk, Poland

Sensors 2017, 17(10), 2302; https://doi.org/10.3390/s17102302 - 10 Oct 2017

Cited by 147 | Viewed by 16636

Abstract

The new Internet of Things paradigm allows for small devices with sensing, processing and communication capabilities to be designed, which enable the development of sensors, embedded devices and other ‘things’ ready to understand the environment. In this paper, a distributed framework based on [...] Read more.

The new Internet of Things paradigm allows for small devices with sensing, processing and communication capabilities to be designed, which enable the development of sensors, embedded devices and other ‘things’ ready to understand the environment. In this paper, a distributed framework based on the internet of things paradigm is proposed for monitoring human biomedical signals in activities involving physical exertion. The main advantages and novelties of the proposed system is the flexibility in computing the health application by using resources from available devices inside the body area network of the user. This proposed framework can be applied to other mobile environments, especially those where intensive data acquisition and high processing needs take place. Finally, we present a case study in order to validate our proposal that consists in monitoring footballers’ heart rates during a football match. The real-time data acquired by these devices presents a clear social objective of being able to predict not only situations of sudden death but also possible injuries. Full article

(This article belongs to the Special Issue Smart Sensor Networks and Technology for Healthcare Monitoring and Decision Making)

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17 pages, 7840 KiB

Open AccessArticle

A Reliable and Real-Time Tracking Method with Color Distribution

by Zishu Zhao^1,†, Yuqi Han^2,†, Tingfa Xu^1,3,*, Xiangmin Li¹, Haiping Song⁴ and Jiqiang Luo¹

¹ School of Optoelectronics, Image Engineering & Video Technology Lab, Beijing Institute of Technology, Beijing 100081, China

² Beijing Key Laboratory of Embedded Real-Time Information Processing Technique, School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China

³ Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Beijing 100081, China

⁴ China North Vehicle Research Institute, Beijing 100081 China

^† These authors contributed equally.

Sensors 2017, 17(10), 2303; https://doi.org/10.3390/s17102303 - 10 Oct 2017

Cited by 17 | Viewed by 3862

Abstract

Occlusion is a challenging problem in visual tracking. Therefore, in recent years, many trackers have been explored to solve this problem, but most of them cannot track the target in real time because of the heavy computational cost. A spatio-temporal context (STC) tracker [...] Read more.

Occlusion is a challenging problem in visual tracking. Therefore, in recent years, many trackers have been explored to solve this problem, but most of them cannot track the target in real time because of the heavy computational cost. A spatio-temporal context (STC) tracker was proposed to accelerate the task by calculating context information in the Fourier domain, alleviating the performance in handling occlusion. In this paper, we take advantage of the high efficiency of the STC tracker and employ salient prior model information based on color distribution to improve the robustness. Furthermore, we exploit a scale pyramid for accurate scale estimation. In particular, a new high-confidence update strategy and a re-searching mechanism are used to avoid the model corruption and handle occlusion. Extensive experimental results demonstrate our algorithm outperforms several state-of-the-art algorithms on the OTB2015 dataset. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 493 KiB

Open AccessArticle

On Efficient Deployment of Wireless Sensors for Coverage and Connectivity in Constrained 3D Space

by Chase Q. Wu^1,*

and Li Wang²

¹ Department of Computer Science, New Jersey Institute of Technology, Newark, NJ 07102, USA

² College of Engineering, Xi’an International University, Xi’an 710077, Shaanxi, China

Sensors 2017, 17(10), 2304; https://doi.org/10.3390/s17102304 - 10 Oct 2017

Cited by 13 | Viewed by 4583

Abstract

Sensor networks have been used in a rapidly increasing number of applications in many fields. This work generalizes a sensor deployment problem to place a minimum set of wireless sensors at candidate locations in constrained 3D space to k-cover a given set [...] Read more.

Sensor networks have been used in a rapidly increasing number of applications in many fields. This work generalizes a sensor deployment problem to place a minimum set of wireless sensors at candidate locations in constrained 3D space to k-cover a given set of target objects. By exhausting the combinations of discreteness/continuousness constraints on either sensor locations or target objects, we formulate four classes of sensor deployment problems in 3D space: deploy sensors at Discrete/Continuous Locations (D/CL) to cover Discrete/Continuous Targets (D/CT). We begin with the design of an approximate algorithm for DLDT and then reduce DLCT, CLDT, and CLCT to DLDT by discretizing continuous sensor locations or target objects into a set of divisions without sacrificing sensing precision. Furthermore, we consider a connected version of each problem where the deployed sensors must form a connected network, and design an approximation algorithm to minimize the number of deployed sensors with connectivity guarantee. For performance comparison, we design and implement an optimal solution and a genetic algorithm (GA)-based approach. Extensive simulation results show that the proposed deployment algorithms consistently outperform the GA-based heuristic and achieve a close-to-optimal performance in small-scale problem instances and a significantly superior overall performance than the theoretical upper bound. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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20 pages, 10505 KiB

Open AccessTechnical Note

Some Hardware and Instrumentation Aspects of the Development of an Automation System for Jar Tests in Drinking Water Treatment

by Antonio José Calderón

and Isaías González^*

Department of Electrical Engineering, Electronics and Automation, University of Extremadura, Avenida de Elvas, s/n, 06006 Badajoz, Spain

Sensors 2017, 17(10), 2305; https://doi.org/10.3390/s17102305 - 11 Oct 2017

Cited by 4 | Viewed by 7078

Abstract

The so-called Jar Test (JT) plays a vital role in the drinking water and wastewater treatments for establishing the dosage of flocculants and coagulant. This test is a well-proved laboratory instrumental procedure performed by trained personnel. In this work, a completely novel system [...] Read more.

The so-called Jar Test (JT) plays a vital role in the drinking water and wastewater treatments for establishing the dosage of flocculants and coagulant. This test is a well-proved laboratory instrumental procedure performed by trained personnel. In this work, a completely novel system for the automation and monitoring of a JT devoted to drinking water treatment is presented. It has been implemented using an industrial programmable controller and sensors and instruments specifically selected for this purpose. Once the parameters of the test have been entered, the stages that compose the JT (stirring, coagulant addition, etc.) are sequentially performed without human intervention. Moreover, all the involved measurements from sensors are collected and made accessible for continuous monitoring of the process. By means of the proposed system, the JT procedure is conducted fully automatically and can be locally and remotely monitored in real-time. Furthermore, the developed system constitutes a portable laboratory that offers advantageous features like scalability and transportability. The proposed system is described focusing on hardware and instrumentation aspects, and successful results are reported. Full article

(This article belongs to the Section Chemical Sensors)

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21 pages, 32829 KiB

Open AccessArticle

Mechanical and Electrical Noise in Sense Channel of MEMS Vibratory Gyroscopes

by Xukai Ding^1,2

, Jia Jia^1,2, Yang Gao^1,2 and Hongsheng Li^1,2,*

¹ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

² Key Laboratory of Micro-Inertial Instruments and Advanced Navigation Technology, Ministry of Education, Nanjing 210096, China

Sensors 2017, 17(10), 2306; https://doi.org/10.3390/s17102306 - 11 Oct 2017

Cited by 19 | Viewed by 6641

Abstract

This paper presents a theoretical analysis of mechanical and electrical noise in the sense channel of micro-electromechanical systems (MEMS) vibratory gyroscopes. Closed-form expressions for the power spectral density (PSD) of the noise equivalent rate (NER) of gyroscopes in the open-loop and the force-rebalance [...] Read more.

This paper presents a theoretical analysis of mechanical and electrical noise in the sense channel of micro-electromechanical systems (MEMS) vibratory gyroscopes. Closed-form expressions for the power spectral density (PSD) of the noise equivalent rate (NER) of gyroscopes in the open-loop and the force-rebalance operations are derived by using an averaged PSD model and an equivalent transfer function. The obtained expressions are verified through numerical simulations, demonstrating close agreements between the analytic and the numerical models. Based on the derived expressions for the PSD of the NER, the impacts of the modal frequency split, quality factor, and the gain of the feedback forcer, as well as the gain of the signal conditioning circuit, on the gyroscope noise characteristics are theoretically analyzed. In addition, the angle random walk (ARW) and the standard deviation of the NER are also discussed through the PSD models. Finally, the effects of the loop closing, the mode matching, and the gain of the feedback forcer on the PSD of the NER were verified via a MEMS vibratory gyroscope with a tunable modal frequency split. Full article

(This article belongs to the Special Issue MEMS Resonators)

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9 pages, 2840 KiB

Open AccessFeature PaperArticle

Application of Multilayer Perceptron with Automatic Relevance Determination on Weed Mapping Using UAV Multispectral Imagery

by Afroditi A. Tamouridou^1,2, Thomas K. Alexandridis²

, Xanthoula E. Pantazi¹, Anastasia L. Lagopodi³

, Javid Kashefi⁴, Dimitris Kasampalis²

, Georgios Kontouris² and Dimitrios Moshou^1,*

¹ Agricultural Engineering Laboratory, Faculty of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

² Laboratory of Remote Sensing and GIS, Faculty of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

³ Plant Pathology Laboratory, Faculty of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

⁴ USDA-ARS-European Biological Control Laboratory, 54623 Thessaloniki, Greece

Sensors 2017, 17(10), 2307; https://doi.org/10.3390/s17102307 - 11 Oct 2017

Cited by 26 | Viewed by 5106

Abstract

Remote sensing techniques are routinely used in plant species discrimination and of weed mapping. In the presented work, successful Silybum marianum detection and mapping using multilayer neural networks is demonstrated. A multispectral camera (green-red-near infrared) attached on a fixed wing unmanned aerial vehicle [...] Read more.

Remote sensing techniques are routinely used in plant species discrimination and of weed mapping. In the presented work, successful Silybum marianum detection and mapping using multilayer neural networks is demonstrated. A multispectral camera (green-red-near infrared) attached on a fixed wing unmanned aerial vehicle (UAV) was utilized for the acquisition of high-resolution images (0.1 m resolution). The Multilayer Perceptron with Automatic Relevance Determination (MLP-ARD) was used to identify the S. marianum among other vegetation, mostly Avena sterilis L. The three spectral bands of Red, Green, Near Infrared (NIR) and the texture layer resulting from local variance were used as input. The S. marianum identification rates using MLP-ARD reached an accuracy of 99.54%. Τhe study had an one year duration, meaning that the results are specific, although the accuracy shows the interesting potential of S. marianum mapping with MLP-ARD on multispectral UAV imagery. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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17 pages, 5162 KiB

Open AccessArticle

Creating Affording Situations: Coaching through Animate Objects

by Chris Baber^1,*

, Ahmad Khattab¹, Martin Russell¹, Joachim Hermsdörfer² and Alan Wing³

¹ School of Engineering, University of Birmingham, Birmingham B15 2TT, UK

² Department of Sport and Health Sciences, Technische Universität Munchen, 80992 Munchen, Germany

³ School of Psychology, University of Birmingham, Birmingham B15 2TT, UK

Sensors 2017, 17(10), 2308; https://doi.org/10.3390/s17102308 - 11 Oct 2017

Cited by 8 | Viewed by 4615

Abstract

We explore the ways in which animate objects can be used to cue actions as part of coaching in Activities of Daily Living (ADL). In this case, changing the appearance or behavior of a physical object is intended to cue actions which are [...] Read more.

We explore the ways in which animate objects can be used to cue actions as part of coaching in Activities of Daily Living (ADL). In this case, changing the appearance or behavior of a physical object is intended to cue actions which are appropriate for a given context. The context is defined by the intention of the users, the state of the objects and the tasks for which these objects can be used. We present initial design prototypes and simple user trials which explore the impact of different cues on activity. It is shown that raising the handle of a jug, for example, not only cues the act of picking up the jug but also encourages use of the hand adjacent to the handle; that combinations of lights (on the objects) and auditory cues influence activity through reducing uncertainty; and that cueing can challenge pre-learned action sequences. We interpret these results in terms of the idea that the animate objects can be used to create affording situations, and discuss implications of this work to support relearning of ADL following brain damage or injury, such as might arise following a stroke. Full article

(This article belongs to the Special Issue Smart Sensing Technologies for Personalised Coaching)

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14 pages, 6422 KiB

Open AccessArticle

The Modular Optical Underwater Survey System

by Ruhul Amin^1,*, Benjamin L. Richards¹, William F. X. E. Misa², Jeremy C. Taylor³, Dianna R. Miller³, Audrey K. Rollo³, Christopher Demarke³, Hanumant Singh⁴

, Grace C. Young⁵

, Jeremy Childress⁶

, Justin E. Ossolinski³, Russell T. Reardon³ and Kyle H. Koyanagi³

¹ NOAA Pacific Islands Fisheries Science Center, Honolulu, HI 96818, USA

² Lynker Technologies LLC, Leesburg, VA 20175, USA

³ Joint Institute for Marine and Atmospheric Research, University of Hawaii, Honolulu, HI 96822, USA

⁴ Department of Engineering Sciences, University of Oxford, Oxford OX1 2JD, UK

⁵ SeaBed Technologies Inc., Falmouth, MA 02540, USA

⁶ The Sexton Corporation, Salem, OR 97302, USA

Sensors 2017, 17(10), 2309; https://doi.org/10.3390/s17102309 - 11 Oct 2017

Cited by 10 | Viewed by 8201

Abstract

The Pacific Islands Fisheries Science Center deploys the Modular Optical Underwater Survey System (MOUSS) to estimate the species-specific, size-structured abundance of commercially-important fish species in Hawaii and the Pacific Islands. The MOUSS is an autonomous stereo-video camera system designed for the in situ [...] Read more.

The Pacific Islands Fisheries Science Center deploys the Modular Optical Underwater Survey System (MOUSS) to estimate the species-specific, size-structured abundance of commercially-important fish species in Hawaii and the Pacific Islands. The MOUSS is an autonomous stereo-video camera system designed for the in situ visual sampling of fish assemblages. This system is rated to 500 m and its low-light, stereo-video cameras enable identification, counting, and sizing of individuals at a range of 0.5–10 m. The modular nature of MOUSS allows for the efficient and cost-effective use of various imaging sensors, power systems, and deployment platforms. The MOUSS is in use for surveys in Hawaii, the Gulf of Mexico, and Southern California. In Hawaiian waters, the system can effectively identify individuals to a depth of 250 m using only ambient light. In this paper, we describe the MOUSS’s application in fisheries research, including the design, calibration, analysis techniques, and deployment mechanism. Full article

(This article belongs to the Special Issue Mechatronic Systems for Automatic Vehicles)

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21 pages, 2056 KiB

Open AccessArticle

Distributed State Estimation Using a Modified Partitioned Moving Horizon Strategy for Power Systems

by Tengpeng Chen^*

, Yi Shyh Eddy Foo

, K.V. Ling

and Xuebing Chen

School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

Sensors 2017, 17(10), 2310; https://doi.org/10.3390/s17102310 - 11 Oct 2017

Cited by 14 | Viewed by 3808

Abstract

In this paper, a distributed state estimation method based on moving horizon estimation (MHE) is proposed for the large-scale power system state estimation. The proposed method partitions the power systems into several local areas with non-overlapping states. Unlike the centralized approach where all [...] Read more.

In this paper, a distributed state estimation method based on moving horizon estimation (MHE) is proposed for the large-scale power system state estimation. The proposed method partitions the power systems into several local areas with non-overlapping states. Unlike the centralized approach where all measurements are sent to a processing center, the proposed method distributes the state estimation task to the local processing centers where local measurements are collected. Inspired by the partitioned moving horizon estimation (PMHE) algorithm, each local area solves a smaller optimization problem to estimate its own local states by using local measurements and estimated results from its neighboring areas. In contrast with PMHE, the error from the process model is ignored in our method. The proposed modified PMHE (mPMHE) approach can also take constraints on states into account during the optimization process such that the influence of the outliers can be further mitigated. Simulation results on the IEEE 14-bus and 118-bus systems verify that our method achieves comparable state estimation accuracy but with a significant reduction in the overall computation load. Full article

(This article belongs to the Section Physical Sensors)

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29 pages, 14076 KiB

Open AccessArticle

Building IoT Services for Aging in Place Using Standard-Based IoT Platforms and Heterogeneous IoT Products

by Sheik Mohammad Mostakim Fattah¹, Nak-Myoung Sung¹, Il-Yeup Ahn¹, Minwoo Ryu² and Jaeseok Yun^3,*

¹ IoT Platform Research Center, Korea Electronics Technology Institute, Seongnam 13509, Korea

² Service Laboratory, Institute of Convergence Technology, KT R&D Center, Seoul 06763, Korea

³ Department of Internet of Things, SCH Media Labs, Soonchunhyang University, Asan 31538, Korea

Sensors 2017, 17(10), 2311; https://doi.org/10.3390/s17102311 - 11 Oct 2017

Cited by 43 | Viewed by 9700

Abstract

An aging population and human longevity is a global trend. Many developed countries are struggling with the yearly increasing healthcare cost that dominantly affects their economy. At the same time, people living with old adults suffering from a progressive brain disorder such as [...] Read more.

An aging population and human longevity is a global trend. Many developed countries are struggling with the yearly increasing healthcare cost that dominantly affects their economy. At the same time, people living with old adults suffering from a progressive brain disorder such as Alzheimer’s disease are enduring even more stress and depression than those patients while caring for them. Accordingly, seniors’ ability to live independently and comfortably in their current home for as long as possible has been crucial to reduce the societal cost for caregiving and thus give family members peace of mind, called ‘aging in place’ (AIP). In this paper we present a way of building AIP services using standard-based IoT platforms and heterogeneous IoT products. An AIP service platform is designed and created by combining previous standard-based IoT platforms in a collaborative way. A service composition tool is also created that allows people to create AIP services in an efficient way. To show practical usability of our proposed system, we choose a service scenario for medication compliance and implement a prototype service which could give old adults medication reminder appropriately at the right time (i.e., when it is time to need to take pills) through light and speaker at home but also wrist band and smartphone even outside the home. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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38 pages, 19592 KiB

Open AccessReview

Micro and Nanostructured Materials for the Development of Optical Fibre Sensors

by Cesar Elosua^1,2,*

, Francisco Javier Arregui^1,2

, Ignacio Del Villar^1,2, Carlos Ruiz-Zamarreño^1,2

, Jesus M. Corres^1,2

, Candido Bariain^1,2, Javier Goicoechea^1,2, Miguel Hernaez^1,2, Pedro J. Rivero^1,2, Abian B. Socorro^1,2, Aitor Urrutia^1,2, Pedro Sanchez¹, Pablo Zubiate¹, Diego Lopez-Torres¹, Nerea De Acha¹, Joaquin Ascorbe¹, Aritz Ozcariz¹

and Ignacio R. Matias^1,2

¹ Department of Electric and Electronic Engineering, Public University of Navarre, E-31006 Pamplona, Spain

² Institute of Smart Cities (ISC), Public University of Navarre, E-31006 Pamplona, Spain

Sensors 2017, 17(10), 2312; https://doi.org/10.3390/s17102312 - 11 Oct 2017

Cited by 54 | Viewed by 9167

Abstract

The measurement of chemical and biomedical parameters can take advantage of the features exclusively offered by optical fibre: passive nature, electromagnetic immunity and chemical stability are some of the most relevant ones. The small dimensions of the fibre generally require that the sensing [...] Read more.

The measurement of chemical and biomedical parameters can take advantage of the features exclusively offered by optical fibre: passive nature, electromagnetic immunity and chemical stability are some of the most relevant ones. The small dimensions of the fibre generally require that the sensing material be loaded into a supporting matrix whose morphology is adjusted at a nanometric scale. Thanks to the advances in nanotechnology new deposition methods have been developed: they allow reagents from different chemical nature to be embedded into films with a thickness always below a few microns that also show a relevant aspect ratio to ensure a high transduction interface. This review reveals some of the main techniques that are currently been employed to develop this kind of sensors, describing in detail both the resulting supporting matrices as well as the sensing materials used. The main objective is to offer a general view of the state of the art to expose the main challenges and chances that this technology is facing currently. Full article

(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)

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23 pages, 9129 KiB

Open AccessArticle

Assessment of Ionospheric Gradient Impacts on Ground-Based Augmentation System (GBAS) Data in Guangdong Province, China

by Zhipeng Wang, Shujing Wang, Yanbo Zhu^* and Pumin Xin

National Key Laboratory of CNS/ATM, School of Electronic and Information Engineering, Beihang University, Beijing 100191,China

Sensors 2017, 17(10), 2313; https://doi.org/10.3390/s17102313 - 11 Oct 2017

Cited by 22 | Viewed by 5620

Abstract

Ionospheric delay is one of the largest and most variable sources of error for Ground-Based Augmentation System (GBAS) users because inospheric activity is unpredictable. Under normal conditions, GBAS eliminates ionospheric delays, but during extreme ionospheric storms, GBAS users and GBAS ground facilities may [...] Read more.

Ionospheric delay is one of the largest and most variable sources of error for Ground-Based Augmentation System (GBAS) users because inospheric activity is unpredictable. Under normal conditions, GBAS eliminates ionospheric delays, but during extreme ionospheric storms, GBAS users and GBAS ground facilities may experience different ionospheric delays, leading to considerable differential errors and threatening the safety of users. Therefore, ionospheric monitoring and assessment are important parts of GBAS integrity monitoring. To study the effects of the ionosphere on the GBAS of Guangdong Province, China, GPS data collected from 65 reference stations were processed using the improved “Simple Truth” algorithm. In addition, the ionospheric characteristics of Guangdong Province were calculated and an ionospheric threat model was established. Finally, we evaluated the influence of the standard deviation and maximum ionospheric gradient on GBAS. The results show that, under normal ionospheric conditions, the vertical protection level of GBAS was increased by 0.8 m for the largest over bound

σ_{v i g}

(sigma of vertical ionospheric gradient), and in the case of the maximum ionospheric gradient conditions, the differential correction error may reach 5 m. From an airworthiness perspective, when the satellite is at a low elevation, this interference does not cause airworthiness risks, but when the satellite is at a high elevation, this interference can cause airworthiness risks. Full article

(This article belongs to the Section Remote Sensors)

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25 pages, 9928 KiB

Open AccessArticle

Soft Smart Garments for Lower Limb Joint Position Analysis

by Massimo Totaro^1,*, Tommaso Poliero², Alessio Mondini¹, Chiara Lucarotti¹, Giovanni Cairoli², Jesùs Ortiz²

and Lucia Beccai^1,*

¹ Center for Micro-BioRobotics, Istituto Italiano di Tecnologia, Viale Rinaldo Piaggio, 34, 56025 Pontedera, Italy

² Department of Advanced Robotics, Istituto Italiano di Tecnologia, Via Morego, 30, 16163 Genova, Italy

Sensors 2017, 17(10), 2314; https://doi.org/10.3390/s17102314 - 12 Oct 2017

Cited by 88 | Viewed by 9149

Abstract

Revealing human movement requires lightweight, flexible systems capable of detecting mechanical parameters (like strain and pressure) while being worn comfortably by the user, and not interfering with his/her activity. In this work we address such multifaceted challenge with the development of smart garments [...] Read more.

Revealing human movement requires lightweight, flexible systems capable of detecting mechanical parameters (like strain and pressure) while being worn comfortably by the user, and not interfering with his/her activity. In this work we address such multifaceted challenge with the development of smart garments for lower limb motion detection, like a textile kneepad and anklet in which soft sensors and readout electronics are embedded for retrieving movement of the specific joint. Stretchable capacitive sensors with a three-electrode configuration are built combining conductive textiles and elastomeric layers, and distributed around knee and ankle. Results show an excellent behavior in the ~30% strain range, hence the correlation between sensors’ responses and the optically tracked Euler angles is allowed for basic lower limb movements. Bending during knee flexion/extension is detected, and it is discriminated from any external contact by implementing in real time a low computational algorithm. The smart anklet is designed to address joint motion detection in and off the sagittal plane. Ankle dorsi/plantar flexion, adduction/abduction, and rotation are retrieved. Both knee and ankle smart garments show a high accuracy in movement detection, with a RMSE less than 4° in the worst case. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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24 pages, 1234 KiB

Open AccessArticle

Feature Weight Driven Interactive Mutual Information Modeling for Heterogeneous Bio-Signal Fusion to Estimate Mental Workload

by Pengbo Zhang, Xue Wang^*, Junfeng Chen and Wei You

State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(10), 2315; https://doi.org/10.3390/s17102315 - 12 Oct 2017

Cited by 22 | Viewed by 4821

Abstract

Many people suffer from high mental workload which may threaten human health and cause serious accidents. Mental workload estimation is especially important for particular people such as pilots, soldiers, crew and surgeons to guarantee the safety and security. Different physiological signals have been [...] Read more.

Many people suffer from high mental workload which may threaten human health and cause serious accidents. Mental workload estimation is especially important for particular people such as pilots, soldiers, crew and surgeons to guarantee the safety and security. Different physiological signals have been used to estimate mental workload based on the n-back task which is capable of inducing different mental workload levels. This paper explores a feature weight driven signal fusion method and proposes interactive mutual information modeling (IMIM) to increase the mental workload classification accuracy. We used EEG and ECG signals to validate the effectiveness of the proposed method for heterogeneous bio-signal fusion. The experiment of mental workload estimation consisted of signal recording, artifact removal, feature extraction, feature weight calculation, and classification. Ten subjects were invited to take part in easy, medium and hard tasks for the collection of EEG and ECG signals in different mental workload levels. Therefore, heterogeneous physiological signals of different mental workload states were available for classification. Experiments reveal that ECG can be utilized as a supplement of EEG to optimize the fusion model and improve mental workload estimation. Classification results show that the proposed bio-signal fusion method IMIM can increase the classification accuracy in both feature level and classifier level fusion. This study indicates that multi-modal signal fusion is promising to identify the mental workload levels and the fusion strategy has potential application of mental workload estimation in cognitive activities during daily life. Full article

(This article belongs to the Special Issue Novel Sensors for Bioimaging)

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21 pages, 3151 KiB

Open AccessReview

Recent Advances in Nanoparticle Concentration and Their Application in Viral Detection Using Integrated Sensors

by Brian M. Dincau¹, Yongkuk Lee², Jong-Hoon Kim^1,*

and Woon-Hong Yeo^2,3,*

¹ School of Engineering and Computer Science, Washington State University, Vancouver, WA 98686, USA

² George W. Woodruff School of Mechanical Engineering, College of Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA

³ Bioengineering Program, Petit Institute for Bioengineering and Bioscience, Center for Flexible Electronics, Institute for Engineering and Nanotechnology, Institute for Bioengineering & Bioscience, Neural Engineering Center, Georgia Institute of Technology, Atlanta, GA 30332, USA

Sensors 2017, 17(10), 2316; https://doi.org/10.3390/s17102316 - 11 Oct 2017

Cited by 14 | Viewed by 5288

Abstract

Early disease diagnostics require rapid, sensitive, and selective detection methods for target analytes. Specifically, early viral detection in a point-of-care setting is critical in preventing epidemics and the spread of disease. However, conventional methods such as enzyme-linked immunosorbent assays or cell cultures are [...] Read more.

Early disease diagnostics require rapid, sensitive, and selective detection methods for target analytes. Specifically, early viral detection in a point-of-care setting is critical in preventing epidemics and the spread of disease. However, conventional methods such as enzyme-linked immunosorbent assays or cell cultures are cumbersome and difficult for field use due to the requirements of extensive lab equipment and highly trained personnel, as well as limited sensitivity. Recent advances in nanoparticle concentration have given rise to many novel detection methodologies, which address the shortcomings in modern clinical assays. Here, we review the primary, well-characterized methods for nanoparticle concentration in the context of viral detection via diffusion, centrifugation and microfiltration, electric and magnetic fields, and nano-microfluidics. Details of the concentration mechanisms and examples of related applications provide valuable information to design portable, integrated sensors. This study reviews a wide range of concentration techniques and compares their advantages and disadvantages with respect to viral particle detection. We conclude by highlighting selected concentration methods and devices for next-generation biosensing systems. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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16 pages, 6405 KiB

Open AccessArticle

Computer Vision-Based Structural Displacement Measurement Robust to Light-Induced Image Degradation for In-Service Bridges

by Junhwa Lee¹, Kyoung-Chan Lee², Soojin Cho^3,* and Sung-Han Sim^1,*

¹ School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea

² Korea Railroad Research Institute, Uiwang 16105, Korea

³ Department of Civil and Environmental Engineering, University of Seoul, Seoul 02504, Korea

Sensors 2017, 17(10), 2317; https://doi.org/10.3390/s17102317 - 11 Oct 2017

Cited by 93 | Viewed by 11354

Abstract

The displacement responses of a civil engineering structure can provide important information regarding structural behaviors that help in assessing safety and serviceability. A displacement measurement using conventional devices, such as the linear variable differential transformer (LVDT), is challenging owing to issues related to [...] Read more.

The displacement responses of a civil engineering structure can provide important information regarding structural behaviors that help in assessing safety and serviceability. A displacement measurement using conventional devices, such as the linear variable differential transformer (LVDT), is challenging owing to issues related to inconvenient sensor installation that often requires additional temporary structures. A promising alternative is offered by computer vision, which typically provides a low-cost and non-contact displacement measurement that converts the movement of an object, mostly an attached marker, in the captured images into structural displacement. However, there is limited research on addressing light-induced measurement error caused by the inevitable sunlight in field-testing conditions. This study presents a computer vision-based displacement measurement approach tailored to a field-testing environment with enhanced robustness to strong sunlight. An image-processing algorithm with an adaptive region-of-interest (ROI) is proposed to reliably determine a marker’s location even when the marker is indistinct due to unfavorable light. The performance of the proposed system is experimentally validated in both laboratory-scale and field experiments. Full article

(This article belongs to the Special Issue Novel Methodologies to Interpret Non-Destructive Testing and Structural Health Monitoring Data)

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20 pages, 26035 KiB

Open AccessArticle

A LQR-Based Controller with Estimation of Road Bank for Improving Vehicle Lateral and Rollover Stability via Active Suspension

by Andres Riofrio^*

, Susana Sanz^†, Maria Jesus L. Boada^†

and Beatriz L. Boada^†

¹ Mechanical Engineering Department, Institute for Automotive Vehicle Safety (ISVA), Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Madrid, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2318; https://doi.org/10.3390/s17102318 - 13 Oct 2017

Cited by 34 | Viewed by 8566

Abstract

In this article, a Linear Quadratic Regulator (LQR) lateral stability and rollover controller has been developed including as the main novelty taking into account the road bank angle and using exclusively active suspension for both lateral stability and rollover control. The main problem [...] Read more.

In this article, a Linear Quadratic Regulator (LQR) lateral stability and rollover controller has been developed including as the main novelty taking into account the road bank angle and using exclusively active suspension for both lateral stability and rollover control. The main problem regarding the road bank is that it cannot be measured by means of on-board sensors. The solution proposed in this article is performing an estimation of this variable using a Kalman filter. In this way, it is possible to distinguish between the road disturbance component and the vehicle’s roll angle. The controller’s effectiveness has been tested by means of simulations carried out in TruckSim, using an experimentally-validated vehicle model. Lateral load transfer, roll angle, yaw rate and sideslip angle have been analyzed in order to quantify the improvements achieved on the behavior of the vehicle. For that purpose, these variables have been compared with the results obtained from both a vehicle that uses passive suspension and a vehicle using a fuzzy logic controller. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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10 pages, 1660 KiB

Open AccessArticle

Self-Evaluation of PANDA-FBG Based Sensing System for Dynamic Distributed Strain and Temperature Measurement

by Mengshi Zhu^1,*,†

, Hideaki Murayama² and Daichi Wada³

¹ Graduate School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan

² Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan

³ Japan Aerospace Exploration Agency, Mitaka, Tokyo 181-0015, Japan

^† Current address: 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.

Sensors 2017, 17(10), 2319; https://doi.org/10.3390/s17102319 - 12 Oct 2017

Cited by 7 | Viewed by 5214

Abstract

A novel method is introduced in this work for effectively evaluating the performance of the PANDA type polarization-maintaining fiber Bragg grating (PANDA-FBG) distributed dynamic strain and temperature sensing system. Conventionally, the errors during the measurement are unknown or evaluated by using other sensors [...] Read more.

A novel method is introduced in this work for effectively evaluating the performance of the PANDA type polarization-maintaining fiber Bragg grating (PANDA-FBG) distributed dynamic strain and temperature sensing system. Conventionally, the errors during the measurement are unknown or evaluated by using other sensors such as strain gauge and thermocouples. This will make the sensing system complicated and decrease the efficiency since more than one kind of sensor is applied for the same measurand. In this study, we used the approximately constant ratio of primary errors in strain and temperature measurement and realized the self-evaluation of the sensing system, which can significantly enhance the applicability, as well as the reliability in strategy making. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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23 pages, 9311 KiB

Open AccessArticle

AAL Platform with a “De Facto” Standard Communication Interface (TICO): Training in Home Control in Special Education

by Miguel A. Guillomía San Bartolomé¹, Jorge L. Falcó Boudet^1,*

, José Ignacio Artigas Maestre¹ and Ana Sánchez Agustín²

¹ Ingeniería Electrónica y Comunicaciones, Universidad de Zaragoza, María de Luna 1, 50018 Zaragoza, Spain

² Alborada Special Education School, Andador Pilar Cuartero sn, 50018 Zaragoza, Spain

Sensors 2017, 17(10), 2320; https://doi.org/10.3390/s17102320 - 12 Oct 2017

Cited by 2 | Viewed by 12788

Abstract

Framed within a long-term cooperation between university and special education teachers, training in alternative communication skills and home control was realized using the “TICO” interface, a communication panel editor extensively used in special education schools. From a technological view we follow AAL technology [...] Read more.

Framed within a long-term cooperation between university and special education teachers, training in alternative communication skills and home control was realized using the “TICO” interface, a communication panel editor extensively used in special education schools. From a technological view we follow AAL technology trends by integrating a successful interface in a heterogeneous services AAL platform, focusing on a functional view. Educationally, a very flexible interface in line with communication training allows dynamic adjustment of complexity, enhanced by an accessible mindset and virtual elements significance already in use, offers specific interaction feedback, adapts to the evolving needs and capacities and improves the personal autonomy and self-confidence of children at school and home. TICO-home-control was installed during the last school year in the library of a special education school to study adaptations and training strategies to enhance the autonomy opportunities of its pupils. The methodology involved a case study and structured and semi-structured observations. Five children, considered unable to use commercial home control systems were trained obtaining good results in enabling them to use an open home control system. Moreover this AAL platform has proved efficient in training children in previous cognitive steps like virtual representation and cause-effect interaction. Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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18 pages, 5403 KiB

Open AccessArticle

Design of a Low-Cost Air Levitation System for Teaching Control Engineering

by Jesus Chacon^1,*, Jacobo Saenz¹, Luis De la Torre¹, Jose Manuel Diaz¹ and Francisco Esquembre²

¹ Departamento de Informática y Automática, ETSI Informatica, UNED, Juan del Rosal 16, 28015 Madrid, Spain

² Departamento de Matemáticas, University of Murcia, 30100 Murcia, Spain

Sensors 2017, 17(10), 2321; https://doi.org/10.3390/s17102321 - 12 Oct 2017

Cited by 41 | Viewed by 7227

Abstract

Air levitation is the process by which an object is lifted without mechanical support in a stable position, by providing an upward force that counteracts the gravitational force exerted on the object. This work presents a low-cost lab implementation of an air levitation [...] Read more.

Air levitation is the process by which an object is lifted without mechanical support in a stable position, by providing an upward force that counteracts the gravitational force exerted on the object. This work presents a low-cost lab implementation of an air levitation system, based on open solutions. The rapid dynamics makes it especially suitable for a control remote lab. Due to the system’s nature, the design can be optimized and, with some precision trade-off, kept affordable both in cost and construction effort. It was designed to be easily adopted to be used as both a remote lab and as a hands-on lab. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 7488 KiB

Open AccessArticle

Implementation of High Time Delay Accuracy of Ultrasonic Phased Array Based on Interpolation CIC Filter

by Peilu Liu, Xinghua Li^*, Haopeng Li, Zhikun Su and Hongxu Zhang

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(10), 2322; https://doi.org/10.3390/s17102322 - 12 Oct 2017

Cited by 5 | Viewed by 4995

Abstract

In order to improve the accuracy of ultrasonic phased array focusing time delay, analyzing the original interpolation Cascade-Integrator-Comb (CIC) filter, an 8× interpolation CIC filter parallel algorithm was proposed, so that interpolation and multichannel decomposition can simultaneously process. Moreover, we summarized the general [...] Read more.

In order to improve the accuracy of ultrasonic phased array focusing time delay, analyzing the original interpolation Cascade-Integrator-Comb (CIC) filter, an 8× interpolation CIC filter parallel algorithm was proposed, so that interpolation and multichannel decomposition can simultaneously process. Moreover, we summarized the general formula of arbitrary multiple interpolation CIC filter parallel algorithm and established an ultrasonic phased array focusing time delay system based on 8× interpolation CIC filter parallel algorithm. Improving the algorithmic structure, 12.5% of addition and 29.2% of multiplication was reduced, meanwhile the speed of computation is still very fast. Considering the existing problems of the CIC filter, we compensated the CIC filter; the compensated CIC filter’s pass band is flatter, the transition band becomes steep, and the stop band attenuation increases. Finally, we verified the feasibility of this algorithm on Field Programming Gate Array (FPGA). In the case of system clock is 125 MHz, after 8× interpolation filtering and decomposition, time delay accuracy of the defect echo becomes 1 ns. Simulation and experimental results both show that the algorithm we proposed has strong feasibility. Because of the fast calculation, small computational amount and high resolution, this algorithm is especially suitable for applications with high time delay accuracy and fast detection. Full article

(This article belongs to the Section Physical Sensors)

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25 pages, 805 KiB

Open AccessArticle

An Anomalous Noise Events Detector for Dynamic Road Traffic Noise Mapping in Real-Life Urban and Suburban Environments

by Joan Claudi Socoró^*

, Francesc Alías

and Rosa Ma Alsina-Pagès

GTM—Grup de recerca en Tecnologies Mèdia, La Salle, Universitat Ramon Llull, Quatre Camins, 30, 08022 Barcelona, Spain

Sensors 2017, 17(10), 2323; https://doi.org/10.3390/s17102323 - 12 Oct 2017

Cited by 68 | Viewed by 8181

Abstract

One of the main aspects affecting the quality of life of people living in urban and suburban areas is their continued exposure to high Road Traffic Noise (RTN) levels. Until now, noise measurements in cities have been performed by professionals, recording data in [...] Read more.

One of the main aspects affecting the quality of life of people living in urban and suburban areas is their continued exposure to high Road Traffic Noise (RTN) levels. Until now, noise measurements in cities have been performed by professionals, recording data in certain locations to build a noise map afterwards. However, the deployment of Wireless Acoustic Sensor Networks (WASN) has enabled automatic noise mapping in smart cities. In order to obtain a reliable picture of the RTN levels affecting citizens, Anomalous Noise Events (ANE) unrelated to road traffic should be removed from the noise map computation. To this aim, this paper introduces an Anomalous Noise Event Detector (ANED) designed to differentiate between RTN and ANE in real time within a predefined interval running on the distributed low-cost acoustic sensors of a WASN. The proposed ANED follows a two-class audio event detection and classification approach, instead of multi-class or one-class classification schemes, taking advantage of the collection of representative acoustic data in real-life environments. The experiments conducted within the DYNAMAP project, implemented on ARM-based acoustic sensors, show the feasibility of the proposal both in terms of computational cost and classification performance using standard Mel cepstral coefficients and Gaussian Mixture Models (GMM). The two-class GMM core classifier relatively improves the baseline universal GMM one-class classifier F1 measure by 18.7% and 31.8% for suburban and urban environments, respectively, within the 1-s integration interval. Nevertheless, according to the results, the classification performance of the current ANED implementation still has room for improvement. Full article

(This article belongs to the Special Issue Sensor Networks for Smart Roads)

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14 pages, 1925 KiB

Open AccessArticle

Electrodermal Activity Sensor for Classification of Calm/Distress Condition

by Roberto Zangróniz^1,*

, Arturo Martínez-Rodrigo¹

, José Manuel Pastor¹

, María T. López²

and Antonio Fernández-Caballero²

¹ Instituto de Tecnologías Audiovisuales, Universidad de Castilla-La Mancha, 16071 Cuenca, Spain

² Instituto de Investigación en Informática, Universidad de Castilla-La Mancha, 02071 Albacete, Spain

Sensors 2017, 17(10), 2324; https://doi.org/10.3390/s17102324 - 12 Oct 2017

Cited by 137 | Viewed by 16365

Abstract

This article introduces a new and unobtrusive wearable monitoring device based on electrodermal activity (EDA) to be used in health-related computing systems. This paper introduces the description of the wearable device capable of acquiring the EDA of a subject in order to detect [...] Read more.

This article introduces a new and unobtrusive wearable monitoring device based on electrodermal activity (EDA) to be used in health-related computing systems. This paper introduces the description of the wearable device capable of acquiring the EDA of a subject in order to detect his/her calm/distress condition from the acquired physiological signals. The lightweight wearable device is placed in the wrist of the subject to allow continuous physiological measurements. With the aim of validating the correct operation of the wearable EDA device, pictures from the International Affective Picture System are used in a control experiment involving fifty participants. The collected signals are processed, features are extracted and a statistical analysis is performed on the calm/distress condition classification. The results show that the wearable device solely based on EDA signal processing reports around 89% accuracy when distinguishing calm condition from distress condition. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 3326 KiB

Open AccessArticle

A High Stability Time Difference Readout Technique of RTD-Fluxgate Sensors

by Na Pang^1,2, Defu Cheng^1,* and Yanzhang Wang¹

¹ College of Instrumentation & Electrical Engineering, Jilin University, No. 938 Ximinzhu Street, Changchun 130026, China

² College of Information Technology and Media, Beihua University, No. 3999 East Binjiang Road, Jilin 132013, China

Sensors 2017, 17(10), 2325; https://doi.org/10.3390/s17102325 - 12 Oct 2017

Cited by 6 | Viewed by 4736

Abstract

The performance of Residence Times Difference (RTD)-fluxgate sensors is closely related to the time difference readout technique. The noise of the induction signal affects the quality of the output signal of the following circuit and the time difference detection, so the stability of [...] Read more.

The performance of Residence Times Difference (RTD)-fluxgate sensors is closely related to the time difference readout technique. The noise of the induction signal affects the quality of the output signal of the following circuit and the time difference detection, so the stability of the sensor is limited. Based on the analysis of the uncertainty of the RTD-fluxgate using the Bidirectional Magnetic Saturation Time Difference (BMSTD) readout scheme, the relationship between the saturation state of the magnetic core and the target (DC) magnetic field is studied in this article. It is proposed that combining the excitation and induction signals can provide the Negative Magnetic Saturation Time (NMST), which is a detection quantity used to measure the target magnetic field. Also, a mathematical model of output response between NMST and the target magnetic field is established, which analyzes the output NMST and sensitivity of the RTD-fluxgate sensor under different excitation conditions and is compared to the BMSTD readout scheme. The experiment results indicate that this technique can effectively reduce the noise influence. The fluctuation of time difference is less than ±0.1 μs in a target magnetic field range of ±5 × 10⁴ nT. The accuracy and stability of the sensor are improved, so the RTD-fluxgate using the readout technique of high stability time difference is suitable for detecting weak magnetic fields. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 4032 KiB

Open AccessArticle

Fabrication and Characterization of a Stabilized Thin Film Ag/AgCl Reference Electrode Modified with Self-Assembled Monolayer of Alkane Thiol Chains for Rapid Biosensing Applications

by Tanzilur Rahman¹ and Takanori Ichiki^2,*

¹ Department of Electrical and Computer Engineering, North South University, Dhaka 1229, Bangladesh

² Department of Materials Engineering, The University of Tokyo, 113-8656 Tokyo, Japan

Sensors 2017, 17(10), 2326; https://doi.org/10.3390/s17102326 - 13 Oct 2017

Cited by 12 | Viewed by 8235

Abstract

The fabrication of miniaturized electrical biosensing devices can enable the rapid on-chip detection of biomarkers such as miRNA molecules, which is highly important in early-stage cancer detection. The challenge in realizing such devices remains in the miniaturization of the reference electrodes, which is [...] Read more.

The fabrication of miniaturized electrical biosensing devices can enable the rapid on-chip detection of biomarkers such as miRNA molecules, which is highly important in early-stage cancer detection. The challenge in realizing such devices remains in the miniaturization of the reference electrodes, which is an integral part of electrical detection. Here, we report on a novel thin film Ag/AgCl reference electrode (RE) that has been fabricated on top of a Au-sputtered glass surface, which was coated with a self-assembled monolayer (SAM) of 6-mercepto-1-hexanol (MCH). The electrode showed very little measurement deviation (−1.5 mv) from a commercial Ag/AgCl reference electrode and exhibited a potential drift of only ± 0.2 mV/h. In addition, the integration of this SAM-modified microfabricated thin film RE enabled the rapid detection (<30 min) of miRNA (let-7a). The electrode can be integrated seamlessly into a microfluidic device, allowing the highly stable and fast measurement of surface potential and is expected to be very useful for the development of miniature electrical biosensors. Full article

(This article belongs to the Special Issue Potentiometric Sensors)

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28 pages, 18229 KiB

Open AccessArticle

Comparing the Performance of Indoor Localization Systems through the EvAAL Framework

by Francesco Potortì^1,*

, Sangjoon Park², Antonio Ramón Jiménez Ruiz³

, Paolo Barsocchi¹

, Michele Girolami¹, Antonino Crivello¹

, So Yeon Lee², Jae Hyun Lim², Joaquín Torres-Sospedra⁴

, Fernando Seco³

, Raul Montoliu⁴

, Germán Martin Mendoza-Silva⁴

, Maria Del Carmen Pérez Rubio⁵

, Cristina Losada-Gutiérrez⁵

, Felipe Espinosa⁵

and Javier Macias-Guarasa⁵

¹ ISTI Institute of CNR, Pisa 56124, Italy

² Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea

³ Centre for Automation and Robotics, CSIC-UPM, Arganda del Rey 28500, Spain

⁴ Institute of New Imaging Technologies, Universitat Jaume I, Castellón de la Plana 12071, Spain

⁵ University of Alcalá, Department of Electronics, Alcalá de Henares 28871, Spain

Sensors 2017, 17(10), 2327; https://doi.org/10.3390/s17102327 - 13 Oct 2017

Cited by 76 | Viewed by 10359

Abstract

In recent years, indoor localization systems have been the object of significant research activity and of growing interest for their great expected social impact and their impressive business potential. Application areas include tracking and navigation, activity monitoring, personalized advertising, Active and Assisted Living [...] Read more.

In recent years, indoor localization systems have been the object of significant research activity and of growing interest for their great expected social impact and their impressive business potential. Application areas include tracking and navigation, activity monitoring, personalized advertising, Active and Assisted Living (AAL), traceability, Internet of Things (IoT) networks, and Home-land Security. In spite of the numerous research advances and the great industrial interest, no canned solutions have yet been defined. The diversity and heterogeneity of applications, scenarios, sensor and user requirements, make it difficult to create uniform solutions. From that diverse reality, a main problem is derived that consists in the lack of a consensus both in terms of the metrics and the procedures used to measure the performance of the different indoor localization and navigation proposals. This paper introduces the general lines of the EvAAL benchmarking framework, which is aimed at a fair comparison of indoor positioning systems through a challenging competition under complex, realistic conditions. To evaluate the framework capabilities, we show how it was used in the 2016 Indoor Positioning and Indoor Navigation (IPIN) Competition. The 2016 IPIN competition considered three different scenario dimensions, with a variety of use cases: (1) pedestrian versus robotic navigation, (2) smartphones versus custom hardware usage and (3) real-time positioning versus off-line post-processing. A total of four competition tracks were evaluated under the same EvAAL benchmark framework in order to validate its potential to become a standard for evaluating indoor localization solutions. The experience gained during the competition and feedback from track organizers and competitors showed that the EvAAL framework is flexible enough to successfully fit the very different tracks and appears adequate to compare indoor positioning systems. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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16 pages, 1572 KiB

Open AccessArticle

Smart Annotation of Cyclic Data Using Hierarchical Hidden Markov Models

by Christine F. Martindale^1,*

, Florian Hoenig², Christina Strohrmann³ and Bjoern M. Eskofier¹

¹ Machine Learning and Data Analytics Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany

² Speech Group, Department of Computer Science, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany

³ Bosch Sensortec GmbH, Gerhard-Kindler-Strasse 9, 72770 Reutlingen, Germany

Sensors 2017, 17(10), 2328; https://doi.org/10.3390/s17102328 - 13 Oct 2017

Cited by 14 | Viewed by 6612

Abstract

Cyclic signals are an intrinsic part of daily life, such as human motion and heart activity. The detailed analysis of them is important for clinical applications such as pathological gait analysis and for sports applications such as performance analysis. Labeled training data for [...] Read more.

Cyclic signals are an intrinsic part of daily life, such as human motion and heart activity. The detailed analysis of them is important for clinical applications such as pathological gait analysis and for sports applications such as performance analysis. Labeled training data for algorithms that analyze these cyclic data come at a high annotation cost due to only limited annotations available under laboratory conditions or requiring manual segmentation of the data under less restricted conditions. This paper presents a smart annotation method that reduces this cost of labeling for sensor-based data, which is applicable to data collected outside of strict laboratory conditions. The method uses semi-supervised learning of sections of cyclic data with a known cycle number. A hierarchical hidden Markov model (hHMM) is used, achieving a mean absolute error of 0.041 ± 0.020 s relative to a manually-annotated reference. The resulting model was also used to simultaneously segment and classify continuous, ‘in the wild’ data, demonstrating the applicability of using hHMM, trained on limited data sections, to label a complete dataset. This technique achieved comparable results to its fully-supervised equivalent. Our semi-supervised method has the significant advantage of reduced annotation cost. Furthermore, it reduces the opportunity for human error in the labeling process normally required for training of segmentation algorithms. It also lowers the annotation cost of training a model capable of continuous monitoring of cycle characteristics such as those employed to analyze the progress of movement disorders or analysis of running technique. Full article

(This article belongs to the Special Issue Annotation of User Data for Sensor-Based Systems)

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14 pages, 1703 KiB

Open AccessArticle

Outlier Detection for Sensor Systems (ODSS): A MATLAB Macro for Evaluating Microphone Sensor Data Quality

by Robert Vasta¹, Ian Crandell², Anthony Millican³, Leanna House² and Eric Smith^2,*

¹ Department of Mathematics, Virginia Tech, Blacksburg, VA 24061, USA

² Department of Statistics, Virginia Tech, Blacksburg, VA 24061, USA

³ Department of Aerospace and Ocean Engineering, Virginia Tech, Blacksburg, VA 24061, USA

Sensors 2017, 17(10), 2329; https://doi.org/10.3390/s17102329 - 13 Oct 2017

Cited by 4 | Viewed by 5677

Abstract

Microphone sensor systems provide information that may be used for a variety of applications. Such systems generate large amounts of data. One concern is with microphone failure and unusual values that may be generated as part of the information collection process. This paper [...] Read more.

Microphone sensor systems provide information that may be used for a variety of applications. Such systems generate large amounts of data. One concern is with microphone failure and unusual values that may be generated as part of the information collection process. This paper describes methods and a MATLAB graphical interface that provides rapid evaluation of microphone performance and identifies irregularities. The approach and interface are described. An application to a microphone array used in a wind tunnel is used to illustrate the methodology. Full article

(This article belongs to the Special Issue Innovative Smart Sensors for Control Systems)

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10 pages, 4265 KiB

Open AccessArticle

The Detection of Water Flow in Rectangular Microchannels by Terahertz Time Domain Spectroscopy

by Yan Song^1,2, Kun Zhao^1,2,*, Jian Zuo³, Cuicui Wang³, Yizhang Li^1,2, Xinyang Miao^1,2 and Xiaojing Zhao³

¹ State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China

² Beijing Key Laboratory of Optical Detection Technology for Oil and Gas, China University of Petroleum, Beijing 102249, China

³ Department of Physics, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Capital Normal University, Beijing 100048, China

Sensors 2017, 17(10), 2330; https://doi.org/10.3390/s17102330 - 13 Oct 2017

Cited by 11 | Viewed by 5269

Abstract

Flow characteristics of water were tested in a rectangular microchannel for Reynolds number (Re) between 0 and 446 by terahertz time domain spectroscopy (THz-TDS). Output THz peak trough intensities and the calculated absorbances of the flow were analyzed theoretically. The results [...] Read more.

Flow characteristics of water were tested in a rectangular microchannel for Reynolds number (Re) between 0 and 446 by terahertz time domain spectroscopy (THz-TDS). Output THz peak trough intensities and the calculated absorbances of the flow were analyzed theoretically. The results show a rapid change for Re < 250 and a slow change as Re increases, which is caused by the early transition from laminar to transition flow beginning nearly at Re = 250. Then this finding is confirmed in the plot of the flow resistant. Our results demonstrate that the THz-TDS could be a valuable tool to monitor and character the flow performance in microscale structures. Full article

(This article belongs to the Special Issue Sensing in Flow Analysis 2017)

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17 pages, 7354 KiB

Open AccessArticle

3D Defect Localization on Exothermic Faults within Multi-Layered Structures Using Lock-In Thermography: An Experimental and Numerical Approach

by Ji Yong Bae¹, Kye-Sung Lee¹, Hwan Hur¹, Ki-Hwan Nam¹, Suk-Ju Hong², Ah-Yeong Lee², Ki Soo Chang¹, Geon-Hee Kim¹ and Ghiseok Kim^2,*

¹ Optical Instrumentation Development Team, Korea Basic Science Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Korea

² Department of Biosystems and Biomaterials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea

Sensors 2017, 17(10), 2331; https://doi.org/10.3390/s17102331 - 13 Oct 2017

Cited by 8 | Viewed by 6003

Abstract

Micro-electronic devices are increasingly incorporating miniature multi-layered integrated architectures. However, the localization of faults in three-dimensional structure remains challenging. This study involved the experimental and numerical estimation of the depth of a thermally active heating source buried in multi-layered silicon wafer architecture by [...] Read more.

Micro-electronic devices are increasingly incorporating miniature multi-layered integrated architectures. However, the localization of faults in three-dimensional structure remains challenging. This study involved the experimental and numerical estimation of the depth of a thermally active heating source buried in multi-layered silicon wafer architecture by using both phase information from an infrared microscopy and finite element simulation. Infrared images were acquired and real-time processed by a lock-in method. It is well known that the lock-in method can increasingly improve detection performance by enhancing the spatial and thermal resolution of measurements. Operational principle of the lock-in method is discussed, and it is represented that phase shift of the thermal emission from a silicon wafer stacked heat source chip (SSHSC) specimen can provide good metrics for the depth of the heat source buried in SSHSCs. Depth was also estimated by analyzing the transient thermal responses using the coupled electro-thermal simulations. Furthermore, the effects of the volumetric heat source configuration mimicking the 3D through silicon via integration package were investigated. Both the infrared microscopic imaging with the lock-in method and FE simulation were potentially useful for 3D isolation of exothermic faults and their depth estimation for multi-layered structures, especially in packaged semiconductors. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 3435 KiB

Open AccessReview

Plasmonic Nanomaterial-Based Optical Biosensing Platforms for Virus Detection

by Jaewook Lee¹

, Kenshin Takemura² and Enoch Y. Park^1,2,*

¹ Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya Suruga-ku, Shizuoka 422-8529, Japan

² Department of Applied Biological Chemistry, College of Agriculture, Graduate School of Integrated Science & Technology, Shizuoka University, 836 Ohya Suruga-ku, Shizuoka 422-8529, Japan

Sensors 2017, 17(10), 2332; https://doi.org/10.3390/s17102332 - 13 Oct 2017

Cited by 41 | Viewed by 8334

Abstract

Plasmonic nanomaterials (P-NM) are receiving attention due to their excellent properties, which include surface-enhanced Raman scattering (SERS), localized surface plasmon resonance (LSPR) effects, plasmonic resonance energy transfer (PRET), and magneto optical (MO) effects. To obtain such plasmonic properties, many nanomaterials have been developed, [...] Read more.

Plasmonic nanomaterials (P-NM) are receiving attention due to their excellent properties, which include surface-enhanced Raman scattering (SERS), localized surface plasmon resonance (LSPR) effects, plasmonic resonance energy transfer (PRET), and magneto optical (MO) effects. To obtain such plasmonic properties, many nanomaterials have been developed, including metal nanoparticles (MNP), bimetallic nanoparticles (bMNP), MNP-decorated carbon nanotubes, (MNP-CNT), and MNP-modified graphene (MNP-GRP). These P-NMs may eventually be applied to optical biosensing systems due to their unique properties. Here, probe biomolecules, such as antibodies (Ab), probe DNA, and probe aptamers, were modified on the surface of plasmonic materials by chemical conjugation and thiol chemistry. The optical property change in the plasmonic nanomaterials was monitored based on the interaction between the probe biomolecules and target virus. After bioconjugation, several optical properties, including fluorescence, plasmonic absorbance, and diffraction angle, were changed to detect the target biomolecules. This review describes several P-NMs as potential candidates of optical sensing platforms and introduces various applications in the optical biosensing field. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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18 pages, 10231 KiB

Open AccessArticle

Control Design and Digital Implementation of a Fast 2-Degree-of-Freedom Translational Optical Image Stabilizer for Image Sensors in Mobile Camera Phones

by Jeremy H. -S. Wang, Kang-Fu Qiu and Paul C. -P. Chao^*

Institute of Electrical and Control Engineering, National Chaio Tung University, Hsinchu City 300, Taiwan

Sensors 2017, 17(10), 2333; https://doi.org/10.3390/s17102333 - 13 Oct 2017

Cited by 8 | Viewed by 6470

Abstract

This study presents design, digital implementation and performance validation of a lead-lag controller for a 2-degree-of-freedom (DOF) translational optical image stabilizer (OIS) installed with a digital image sensor in mobile camera phones. Nowadays, OIS is an important feature of modern commercial mobile camera [...] Read more.

This study presents design, digital implementation and performance validation of a lead-lag controller for a 2-degree-of-freedom (DOF) translational optical image stabilizer (OIS) installed with a digital image sensor in mobile camera phones. Nowadays, OIS is an important feature of modern commercial mobile camera phones, which aims to mechanically reduce the image blur caused by hand shaking while shooting photos. The OIS developed in this study is able to move the imaging lens by actuating its voice coil motors (VCMs) at the required speed to the position that significantly compensates for imaging blurs by hand shaking. The compensation proposed is made possible by first establishing the exact, nonlinear equations of motion (EOMs) for the OIS, which is followed by designing a simple lead-lag controller based on established nonlinear EOMs for simple digital computation via a field-programmable gate array (FPGA) board in order to achieve fast response. Finally, experimental validation is conducted to show the favorable performance of the designed OIS; i.e., it is able to stabilize the lens holder to the desired position within 0.02 s, which is much less than previously reported times of around 0.1 s. Also, the resulting residual vibration is less than 2.2–2.5 μm, which is commensurate to the very small pixel size found in most of commercial image sensors; thus, significantly minimizing image blur caused by hand shaking. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 4851 KiB

Open AccessArticle

The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm²

by Lin-Yue Liu^1,2, Ling Wang³, Peng Jin², Jin-Liang Liu², Xian-Peng Zhang², Liang Chen², Jiang-Fu Zhang², Xiao-Ping Ouyang^1,2,4,*, Ao Liu³, Run-Hua Huang³ and Song Bai^3,*

¹ School of Nuclear Science and Technology, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049, China

² State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi’an 710024, China

³ State Key Laboratory of Wide-Bandgap Semiconductor Power Electronic Devices, Nanjing Electronic Devices Institute, No. 524 East Zhongshan Road, Nanjing 210016, China

⁴ Shaanxi Engineering Research Center for Pulse-Neutron Source and its Application, Xijing University, Xi’an 710123, China

Sensors 2017, 17(10), 2334; https://doi.org/10.3390/s17102334 - 13 Oct 2017

Cited by 23 | Viewed by 7131

Abstract

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1–4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response [...] Read more.

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1–4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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15 pages, 4626 KiB

Open AccessArticle

Modeling and Compensation of Random Drift of MEMS Gyroscopes Based on Least Squares Support Vector Machine Optimized by Chaotic Particle Swarm Optimization

by Haifeng Xing

, Bo Hou, Zhihui Lin and Meifeng Guo^*

Engineering Research Center for Navigation Technology, Department of Precision Instruments, Tsinghua University, Beijing100084, China

Sensors 2017, 17(10), 2335; https://doi.org/10.3390/s17102335 - 13 Oct 2017

Cited by 60 | Viewed by 6291

Abstract

MEMS (Micro Electro Mechanical System) gyroscopes have been widely applied to various fields, but MEMS gyroscope random drift has nonlinear and non-stationary characteristics. It has attracted much attention to model and compensate the random drift because it can improve the precision of inertial [...] Read more.

MEMS (Micro Electro Mechanical System) gyroscopes have been widely applied to various fields, but MEMS gyroscope random drift has nonlinear and non-stationary characteristics. It has attracted much attention to model and compensate the random drift because it can improve the precision of inertial devices. This paper has proposed to use wavelet filtering to reduce noise in the original data of MEMS gyroscopes, then reconstruct the random drift data with PSR (phase space reconstruction), and establish the model for the reconstructed data by LSSVM (least squares support vector machine), of which the parameters were optimized using CPSO (chaotic particle swarm optimization). Comparing the effect of modeling the MEMS gyroscope random drift with BP-ANN (back propagation artificial neural network) and the proposed method, the results showed that the latter had a better prediction accuracy. Using the compensation of three groups of MEMS gyroscope random drift data, the standard deviation of three groups of experimental data dropped from 0.00354°/s, 0.00412°/s, and 0.00328°/s to 0.00065°/s, 0.00072°/s and 0.00061°/s, respectively, which demonstrated that the proposed method can reduce the influence of MEMS gyroscope random drift and verified the effectiveness of this method for modeling MEMS gyroscope random drift. Full article

(This article belongs to the Special Issue MEMS Resonators)

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13 pages, 3019 KiB

Open AccessArticle

Etched Polymer Fibre Bragg Gratings and Their Biomedical Sensing Applications

by Ginu Rajan^1,*, Kishore Bhowmik², Jiangtao Xi¹ and Gang-Ding Peng³

¹ School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, Wollongong 2522, Australia

² HFC Network Assurance, HFC Operations, NBN, Sydney 2060, Australia

³ School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney 2052, Australia

Sensors 2017, 17(10), 2336; https://doi.org/10.3390/s17102336 - 13 Oct 2017

Cited by 11 | Viewed by 3919

Abstract

Bragg gratings in etched polymer fibres and their unique properties and characteristics are discussed in this paper. Due to the change in material and mechanical properties of the polymer fibre through etching, Bragg gratings inscribed in such fibres show high reflectivity and enhanced [...] Read more.

Bragg gratings in etched polymer fibres and their unique properties and characteristics are discussed in this paper. Due to the change in material and mechanical properties of the polymer fibre through etching, Bragg gratings inscribed in such fibres show high reflectivity and enhanced intrinsic sensitivity towards strain, temperature, and pressure. The short-term and long-term stability of the gratings and the effect of hysteresis on the dynamic characteristics are also discussed. The unique properties and enhanced intrinsic sensitivity of etched polymer fibre Bragg grating are ideal for the development of high-sensitivity sensors for biomedical applications. To demonstrate their biomedical sensing capabilities, a high-sensitivity pressure transducer that operates in the blood pressure range, and a breathing rate monitoring device are developed and presented. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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13 pages, 1512 KiB

Open AccessArticle

Fingertip Fiber Optical Tactile Array with Two-Level Spring Structure

by Jelizaveta Konstantinova^1,*

, Agostino Stilli² and Kaspar Althoefer¹

¹ Advanced Robotics @ Queen Mary (ARQ), Faculty of Science and Engineering, Queen Mary University of London, London E1 4NS, UK

² Centre for Medical Imaging Computing, University College of London, Gower Street, London WC1E 6BT, UK

Sensors 2017, 17(10), 2337; https://doi.org/10.3390/s17102337 - 13 Oct 2017

Cited by 26 | Viewed by 7890

Abstract

Tactile perception is a feature benefiting reliable grasping and manipulation. This paper presents the design of an integrated fingertip force sensor employing an optical fiber based approach where applied forces modulate light intensity. The proposed sensor system is developed to support grasping of [...] Read more.

Tactile perception is a feature benefiting reliable grasping and manipulation. This paper presents the design of an integrated fingertip force sensor employing an optical fiber based approach where applied forces modulate light intensity. The proposed sensor system is developed to support grasping of a broad range of objects, including those that are hard as well those that are soft. The sensor system is comprised of four sensing elements forming a tactile array integrated with the tip of a finger. We investigate the design configuration of a separate force sensing element with the aim to improve its measurement range. The force measurement of a single tactile element is based on a two-level displacement that is achieved thanks to a hybrid sensing structure made up of a stiff linear and flexible ortho-planar spring. An important outcome of this paper is a miniature tactile fingertip sensor that is capable of perceiving light contact, typically occurring during the initial stages of a grasp, as well as measuring higher forces, commonly present during tight grasps. Full article

(This article belongs to the Special Issue Tactile Sensors and Sensing)

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12 pages, 361 KiB

Open AccessArticle

Automated Epileptic Seizure Detection Based on Wearable ECG and PPG in a Hospital Environment

by Kaat Vandecasteele^1,2,*

, Thomas De Cooman^1,2

, Ying Gu^1,2, Evy Cleeren³, Kasper Claes⁴

, Wim Van Paesschen³

, Sabine Van Huffel^1,2

and Borbála Hunyadi^1,2

¹ KU Leuven, Department of Electrical Engineering (ESAT), STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Leuven 3001, Belgium

² imec, Leuven 3001, Belgium

³ KU Leuven, University Hospital, Department of Neurosciences, Leuven 3000, Belgium

⁴ UCB, Brussels 1070, Belgium

Sensors 2017, 17(10), 2338; https://doi.org/10.3390/s17102338 - 13 Oct 2017

Cited by 150 | Viewed by 15442

Abstract

Electrocardiography has added value to automatically detect seizures in temporal lobe epilepsy (TLE) patients. The wired hospital system is not suited for a long-term seizure detection system at home. To address this need, the performance of two wearable devices, based on electrocardiography (ECG) [...] Read more.

Electrocardiography has added value to automatically detect seizures in temporal lobe epilepsy (TLE) patients. The wired hospital system is not suited for a long-term seizure detection system at home. To address this need, the performance of two wearable devices, based on electrocardiography (ECG) and photoplethysmography (PPG), are compared with hospital ECG using an existing seizure detection algorithm. This algorithm classifies the seizures on the basis of heart rate features, extracted from the heart rate increase. The algorithm was applied to recordings of 11 patients in a hospital setting with 701 h capturing 47 (fronto-)temporal lobe seizures. The sensitivities of the hospital system, the wearable ECG device and the wearable PPG device were respectively 57%, 70% and 32%, with corresponding false alarms per hour of 1.92, 2.11 and 1.80. Whereas seizure detection performance using the wrist-worn PPG device was considerably lower, the performance using the wearable ECG is proven to be similar to that of the hospital ECG. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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18 pages, 11904 KiB

Open AccessArticle

Robust Stereo Visual Odometry Using Improved RANSAC-Based Methods for Mobile Robot Localization

by Yanqing Liu^1,2, Yuzhang Gu^1,2, Jiamao Li^1,2 and Xiaolin Zhang^1,2,*

¹ Bio-Vision System Laboratory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Sensors 2017, 17(10), 2339; https://doi.org/10.3390/s17102339 - 13 Oct 2017

Cited by 18 | Viewed by 5947

Abstract

In this paper, we present a novel approach for stereo visual odometry with robust motion estimation that is faster and more accurate than standard RANSAC (Random Sample Consensus). Our method makes improvements in RANSAC in three aspects: first, the hypotheses are preferentially generated [...] Read more.

In this paper, we present a novel approach for stereo visual odometry with robust motion estimation that is faster and more accurate than standard RANSAC (Random Sample Consensus). Our method makes improvements in RANSAC in three aspects: first, the hypotheses are preferentially generated by sampling the input feature points on the order of ages and similarities of the features; second, the evaluation of hypotheses is performed based on the SPRT (Sequential Probability Ratio Test) that makes bad hypotheses discarded very fast without verifying all the data points; third, we aggregate the three best hypotheses to get the final estimation instead of only selecting the best hypothesis. The first two aspects improve the speed of RANSAC by generating good hypotheses and discarding bad hypotheses in advance, respectively. The last aspect improves the accuracy of motion estimation. Our method was evaluated in the KITTI (Karlsruhe Institute of Technology and Toyota Technological Institute) and the New Tsukuba dataset. Experimental results show that the proposed method achieves better results for both speed and accuracy than RANSAC. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 1589 KiB

Open AccessArticle

Assessing White Wine Viscosity Variation Using Polarized Laser Speckle: A Promising Alternative to Wine Sensory Analysis

by Christelle Abou Nader^1,*, Hadi Loutfi¹, Fabrice Pellen², Bernard Le Jeune², Guy Le Brun^2,*, Roger Lteif³ and Marie Abboud^1,*

¹ Physics Department, UR TVA, Faculty of Science, Saint Joseph University, B.P. 11-514-Riad El Solh, Beirut 1107 2050, Lebanon

² Laboratoire OPTIMAG (EA 938), Université de Bretagne Occidentale, 29238 Brest CEDEX 3, France

³ Chemistry Department, UR TVA, Faculty of Science, Saint Joseph University, B.P. 11-514-Riad El Solh, Beirut 1107 2050, Lebanon

Sensors 2017, 17(10), 2340; https://doi.org/10.3390/s17102340 - 13 Oct 2017

Cited by 5 | Viewed by 5446

Abstract

In this paper, we report measurements of wine viscosity, correlated to polarized laser speckle results. Experiments were performed on white wine samples produced with a single grape variety. Effects of the wine making cellar, the grape variety, and the vintage on wine Brix [...] Read more.

In this paper, we report measurements of wine viscosity, correlated to polarized laser speckle results. Experiments were performed on white wine samples produced with a single grape variety. Effects of the wine making cellar, the grape variety, and the vintage on wine Brix degree, alcohol content, viscosity, and speckle parameters are considered. We show that speckle parameters, namely, spatial contrast and speckle decorrelation time, as well as the inertia moment extracted from the temporal history speckle pattern, are mainly affected by the alcohol and sugar content and hence the wine viscosity. Principal component analysis revealed a high correlation between laser speckle results on the one hand and viscosity and Brix degree values on the other. As speckle analysis proved to be an efficient method of measuring the variation of the viscosity of white mono-variety wine, one can therefore consider it as an alternative method to wine sensory analysis. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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9 pages, 816 KiB

Open AccessArticle

Verification of a Method for Measuring Parkinson’s Disease Related Temporal Irregularity in Spiral Drawings

by Somayeh Aghanavesi^1,*

, Mevludin Memedi², Mark Dougherty¹, Dag Nyholm³

and Jerker Westin¹

¹ School of Technology and Business Studies, Computer Engineering, Dalarna University, 791 88 Falun, Sweden

² Informatics, Business School, Örebro University, 702 81 Örebro, Sweden

³ Department of Neuroscience, Neurology, Uppsala University, 751 85 Uppsala, Sweden

Sensors 2017, 17(10), 2341; https://doi.org/10.3390/s17102341 - 13 Oct 2017

Cited by 18 | Viewed by 4885

Abstract

Parkinson’s disease (PD) is a progressive movement disorder caused by the death of dopamine-producing cells in the midbrain. There is a need for frequent symptom assessment, since the treatment needs to be individualized as the disease progresses. The aim of this paper was [...] Read more.

Parkinson’s disease (PD) is a progressive movement disorder caused by the death of dopamine-producing cells in the midbrain. There is a need for frequent symptom assessment, since the treatment needs to be individualized as the disease progresses. The aim of this paper was to verify and further investigate the clinimetric properties of an entropy-based method for measuring PD-related upper limb temporal irregularities during spiral drawing tasks. More specifically, properties of a temporal irregularity score (TIS) for patients at different stages of PD, and medication time points were investigated. Nineteen PD patients and 22 healthy controls performed repeated spiral drawing tasks on a smartphone. Patients performed the tests before a single levodopa dose and at specific time intervals after the dose was given. Three movement disorder specialists rated videos of the patients based on the unified PD rating scale (UPDRS) and the Dyskinesia scale. Differences in mean TIS between the groups of patients and healthy subjects were assessed. Test-retest reliability of the TIS was measured. The ability of TIS to detect changes from baseline (before medication) to later time points was investigated. Correlations between TIS and clinical rating scores were assessed. The mean TIS was significantly different between healthy subjects and patients in advanced groups (p-value = 0.02). Test-retest reliability of TIS was good with Intra-class Correlation Coefficient of 0.81. When assessing changes in relation to treatment, TIS contained some information to capture changes from Off to On and wearing off effects. However, the correlations between TIS and clinical scores (UPDRS and Dyskinesia) were weak. TIS was able to differentiate spiral drawings drawn by patients in an advanced stage from those drawn by healthy subjects, and TIS had good test-retest reliability. TIS was somewhat responsive to single-dose levodopa treatment. Since TIS is an upper limb high-frequency-based measure, it cannot be detected during clinical assessment. Full article

(This article belongs to the Section Physical Sensors)

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28 pages, 11655 KiB

Open AccessArticle

Model-Based Real-Time Non-Rigid Tracking

by Sebastián Bronte, Luis M. Bergasa^*

, Daniel Pizarro and Rafael Barea

Electronics Department, University of Alcalá, Campus Universitario, 28805 Alcalá de Henares, Spain

Sensors 2017, 17(10), 2342; https://doi.org/10.3390/s17102342 - 14 Oct 2017

Cited by 3 | Viewed by 5459

Abstract

This paper presents a sequential non-rigid reconstruction method that recovers the 3D shape and the camera pose of a deforming object from a video sequence and a previous shape model of the object. We take PTAM (Parallel Mapping and Tracking), a state-of-the-art sequential [...] Read more.

This paper presents a sequential non-rigid reconstruction method that recovers the 3D shape and the camera pose of a deforming object from a video sequence and a previous shape model of the object. We take PTAM (Parallel Mapping and Tracking), a state-of-the-art sequential real-time SfM (Structure-from-Motion) engine, and we upgrade it to solve non-rigid reconstruction. Our method provides a good trade-off between processing time and reconstruction error without the need for specific processing hardware, such as GPUs. We improve the original PTAM matching by using descriptor-based features, as well as smoothness priors to better constrain the 3D error. This paper works with perspective projection and deals with outliers and missing data. We evaluate the tracking algorithm performance through different tests over several datasets of non-rigid deforming objects. Our method achieves state-of-the-art accuracy and can be used as a real-time method suitable for being embedded in portable devices. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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25 pages, 3147 KiB

Open AccessArticle

Evaluating Oilseed Biofuel Production Feasibility in California’s San Joaquin Valley Using Geophysical and Remote Sensing Techniques

by Dennis L. Corwin^1,*, Kevin Yemoto², Wes Clary³, Gary Banuelos⁴, Todd H. Skaggs¹, Scott M. Lesch⁵ and Elia Scudiero¹

¹ USDA-ARS, U.S. Salinity Laboratory, 450 West Big Springs Road, Riverside, CA 92507, USA

² USDA-ARS, Water Management Systems Research, 2150 Center Ave., NRRC Building D, Fort Collins, CO 80526, USA

³ Department of Earth and Planetary Sciences, Northrop Hall, 221 Yale Blvd. NE, University of New Mexico, Albuquerque, NM 87131, USA

⁴ USDA-ARS, Water Management Research Unit, San Joaquin Valley Agricultural Sciences Center, 9611 South Riverbend Ave., Parlier, CA 93648, USA

⁵ Riverside Public Utilities—Resources Division, 3435 14th St., Riverside, CA 92501, USA

Sensors 2017, 17(10), 2343; https://doi.org/10.3390/s17102343 - 14 Oct 2017

Cited by 3 | Viewed by 4863

Abstract

Though more costly than petroleum-based fuels and a minor component of overall military fuel sources, biofuels are nonetheless strategically valuable to the military because of intentional reliance on multiple, reliable, secure fuel sources. Significant reduction in oilseed biofuel cost occurs when grown on [...] Read more.

Though more costly than petroleum-based fuels and a minor component of overall military fuel sources, biofuels are nonetheless strategically valuable to the military because of intentional reliance on multiple, reliable, secure fuel sources. Significant reduction in oilseed biofuel cost occurs when grown on marginally productive saline-sodic soils plentiful in California’s San Joaquin Valley (SJV). The objective is to evaluate the feasibility of oilseed production on marginal soils in the SJV to support a 115 ML yr⁻¹ biofuel conversion facility. The feasibility evaluation involves: (1) development of an Ida Gold mustard oilseed yield model for marginal soils; (2) identification of marginally productive soils; (3) development of a spatial database of edaphic factors influencing oilseed yield and (4) performance of Monte Carlo simulations showing potential biofuel production on marginally productive SJV soils. The model indicates oilseed yield is related to boron, salinity, leaching fraction, and water content at field capacity. Monte Carlo simulations for the entire SJV fit a shifted gamma probability density function: Q = 68.986 + gamma (6.134,5.285), where Q is biofuel production in ML yr⁻¹. The shifted gamma cumulative density function indicates a 0.15–0.17 probability of meeting the target biofuel-production level of 115 ML yr⁻¹, making adequate biofuel production unlikely. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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24 pages, 4655 KiB

Open AccessArticle

Bio-Inspired Distributed Transmission Power Control Considering QoS Fairness in Wireless Body Area Sensor Networks

by Chan-Jae Lee, Ji-Young Jung

and Jung-Ryun Lee^*

School of Electrical and Electronics Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Korea

Sensors 2017, 17(10), 2344; https://doi.org/10.3390/s17102344 - 14 Oct 2017

Cited by 7 | Viewed by 4265

Abstract

Recently, the development of wireless body area sensor network (WBASN) has accelerated due to the rapid development of wireless technology. In the WBASN environment, many WBASNs coexist where communication ranges overlap with each other, resulting in the possibility of interference. Although nodes in [...] Read more.

Recently, the development of wireless body area sensor network (WBASN) has accelerated due to the rapid development of wireless technology. In the WBASN environment, many WBASNs coexist where communication ranges overlap with each other, resulting in the possibility of interference. Although nodes in a WBASN typically operate at a low power level, to avoid adversely affecting the human body, high transmission rates may be required to support some applications. In addition to this, since many varieties of applications exist in the WBASN environment, each prospective user may have different quality of service (QoS) requirements. Hence, the following issues should be considered in the WBASN environment: (1) interference between adjacent WBASNs, which influences the performance of a specific system, and (2) the degree of satisfaction on the QoS of each user, i.e., the required QoS such as user throughput should be considered to ensure that all users in the network are provided with a fair QoS satisfaction. Thus, in this paper, we propose a transmission power adjustment algorithm that addresses interference problems and guarantees QoS fairness between users. First, we use a new utility function to measure the degree of the satisfaction on the QoS for each user. Then, the transmission power of each sensor node is calculated using the Cucker–Smale model, and the QoS satisfaction of each user is synchronized dispersively. The results of simulations show that the proposed algorithm performs better than existing algorithms, with respect to QoS fairness and energy efficiency. Full article

(This article belongs to the Collection Smart Communication Protocols and Algorithms for Sensor Networks)

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9 pages, 1851 KiB

Open AccessArticle

Low Cost Lab on Chip for the Colorimetric Detection of Nitrate in Mineral Water Products

by Mohammad F. Khanfar¹, Wisam Al-Faqheri² and Ala’aldeen Al-Halhouli^2,*

¹ Department of Pharmaceutical and Chemical Engineering, School of Applied Medical Sciences, German Jordanian University, P.O. Box 35247, Amman 11180, Jordan

² NanoLab, School of Applied Technical Sciences, German Jordanian University, P.O. Box 35247, Amman 11180, Jordan

Sensors 2017, 17(10), 2345; https://doi.org/10.3390/s17102345 - 14 Oct 2017

Cited by 44 | Viewed by 8608

Abstract

The diagnostics of health status and the quality of drinking water are among the most important United Nations sustainable development goals. However, in certain areas, wars and instability have left millions of people setting in refugee camps and dangerous regions where infrastructures are [...] Read more.

The diagnostics of health status and the quality of drinking water are among the most important United Nations sustainable development goals. However, in certain areas, wars and instability have left millions of people setting in refugee camps and dangerous regions where infrastructures are lacking and rapid diagnostics of water quality and medical status are critical. In this work, microfluidic testing chips and photometric setups are developed in cheap and portable way to detect nitrate concentrations in water. The performed test is designed to work according to the Griess procedure. Moreover, to make it simple and usable in areas of low resource settings, commercially available Arduino mega and liquid crystal display (LCD) shield are utilized to process and display results, respectively. For evaluation purposes, different local products of tap water, bottled drinking water, and home-filter treated water samples were tested using the developed setup. A calibration curve with coefficient of determination (R²) of 0.98 was obtained when absorbance of the prepared standard solutions was measured as a function of the concentrations. In conclusion, this is the first step towards a compact, portable, and reliable system for nitrate detection in water for point-of-care applications. Full article

(This article belongs to the Special Issue Fluorescent Probes and Sensors)

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24 pages, 6470 KiB

Open AccessArticle

Extrinsic Calibration of Camera and 2D Laser Sensors without Overlap

by Khalil M. Ahmad Yousef^1,*,†

, Bassam J. Mohd¹, Khalid Al-Widyan² and Thaier Hayajneh³

¹ Department of Computer Engineering, the Hashemite University, Zarqa 13115, Jordan

² Department of Mechatronics Engineering, the Hashemite University, Zarqa 13115, Jordan

³ Department of Computer and Information Sciences, Fordham University, New York, NY 10023, USA

^† Current address: Department of Computer Engineering, the Hashemite University, Zarqa 13115, Jordan.

Sensors 2017, 17(10), 2346; https://doi.org/10.3390/s17102346 - 14 Oct 2017

Cited by 24 | Viewed by 11091

Abstract

Extrinsic calibration of a camera and a 2D laser range finder (lidar) sensors is crucial in sensor data fusion applications; for example SLAM algorithms used in mobile robot platforms. The fundamental challenge of extrinsic calibration is when the camera-lidar sensors do not overlap [...] Read more.

Extrinsic calibration of a camera and a 2D laser range finder (lidar) sensors is crucial in sensor data fusion applications; for example SLAM algorithms used in mobile robot platforms. The fundamental challenge of extrinsic calibration is when the camera-lidar sensors do not overlap or share the same field of view. In this paper we propose a novel and flexible approach for the extrinsic calibration of a camera-lidar system without overlap, which can be used for robotic platform self-calibration. The approach is based on the robot–world hand–eye calibration (RWHE) problem; proven to have efficient and accurate solutions. First, the system was mapped to the RWHE calibration problem modeled as the linear relationship

AX = ZB

, where

X

and

Z

are unknown calibration matrices. Then, we computed the transformation matrix

B

, which was the main challenge in the above mapping. The computation is based on reasonable assumptions about geometric structure in the calibration environment. The reliability and accuracy of the proposed approach is compared to a state-of-the-art method in extrinsic 2D lidar to camera calibration. Experimental results from real datasets indicate that the proposed approach provides better results with an L2 norm translational and rotational deviations of 314 mm and

{0.12}^{\circ}

respectively. Full article

(This article belongs to the Special Issue Imaging Depth Sensors—Sensors, Algorithms and Applications)

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14 pages, 3406 KiB

Open AccessFeature PaperArticle

Remote Sensing-Based Quantification of the Impact of Flash Flooding on the Rice Production: A Case Study over Northeastern Bangladesh

by M. Razu Ahmed

, Khan Rubayet Rahaman

, Aaron Kok and Quazi K. Hassan^*

Department of Geomatics Engineering, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(10), 2347; https://doi.org/10.3390/s17102347 - 14 Oct 2017

Cited by 55 | Viewed by 7738

Abstract

The northeastern region of Bangladesh often experiences flash flooding during the pre-harvesting period of the boro rice crop, which is the major cereal crop in the country. In this study, our objective was to delineate the impact of the 2017 flash flood (that [...] Read more.

The northeastern region of Bangladesh often experiences flash flooding during the pre-harvesting period of the boro rice crop, which is the major cereal crop in the country. In this study, our objective was to delineate the impact of the 2017 flash flood (that initiated on 27 March 2017) on boro rice using multi-temporal Landsat-8 OLI and MODIS data. Initially, we opted to use Landsat-8 OLI data for mapping the damages; however, during and after the flooding event the acquisition of cloud free images were challenging. Thus, we used this data to map the cultivated boro rice acreage considering the planting to mature stages of the crop. Also, in order to map the extent of the damaged boro area, we utilized MODIS data as their 16-day composites provided cloud free information. Our results indicated that both the cultivated and damaged boro area estimates based on satellite data had strong relationships while compared to the ground-based estimates (i.e., r² values approximately 0.92 for both cases, and RMSE of 18,374 and 9380 ha for cultivated and damaged areas, respectively). Finally, we believe that our study would be critical for planning and ensuring food security for the country. Full article

(This article belongs to the Special Issue Remote Sensing and GIS for Geo-Hazards and Disasters)

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19 pages, 3744 KiB

Open AccessArticle

Toward a Robust Security Paradigm for Bluetooth Low Energy-Based Smart Objects in the Internet-of-Things

by Shi-Cho Cha¹, Kuo-Hui Yeh^2,*

and Jyun-Fu Chen¹

¹ Department of Information Management, National Taiwan University of Science and Technology, Taipei 10607, Taiwan

² Department of Information Management, National Dong Hwa University, Hualien 97401, Taiwan

Sensors 2017, 17(10), 2348; https://doi.org/10.3390/s17102348 - 14 Oct 2017

Cited by 5 | Viewed by 5728

Abstract

Bluetooth Low Energy (BLE) has emerged as one of the most promising technologies to enable the Internet-of-Things (IoT) paradigm. In BLE-based IoT applications, e.g., wearables-oriented service applications, the Bluetooth MAC addresses of devices will be swapped for device pairings. The random address technique [...] Read more.

Bluetooth Low Energy (BLE) has emerged as one of the most promising technologies to enable the Internet-of-Things (IoT) paradigm. In BLE-based IoT applications, e.g., wearables-oriented service applications, the Bluetooth MAC addresses of devices will be swapped for device pairings. The random address technique is adopted to prevent malicious users from tracking the victim’s devices with stationary Bluetooth MAC addresses and accordingly the device privacy can be preserved. However, there exists a tradeoff between privacy and security in the random address technique. That is, when device pairing is launched and one device cannot actually identify another one with addresses, it provides an opportunity for malicious users to break the system security via impersonation attacks. Hence, using random addresses may lead to higher security risks. In this study, we point out the potential risk of using random address technique and then present critical security requirements for BLE-based IoT applications. To fulfill the claimed requirements, we present a privacy-aware mechanism, which is based on elliptic curve cryptography, for secure communication and access-control among BLE-based IoT objects. Moreover, to ensure the security of smartphone application associated with BLE-based IoT objects, we construct a Smart Contract-based Investigation Report Management framework (SCIRM) which enables smartphone application users to obtain security inspection reports of BLE-based applications of interest with smart contracts. Full article

(This article belongs to the Special Issue Mobile Sensing Applications)

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15 pages, 10923 KiB

Open AccessArticle

Adaptive Enhancement of X-Band Marine Radar Imagery to Detect Oil Spill Segments

by Peng Liu, Ying Li^*, Jin Xu and Xueyuan Zhu

Environmental Information Institute of Navigation College, Dalian Maritime University, Dalian 116026, China

Sensors 2017, 17(10), 2349; https://doi.org/10.3390/s17102349 - 14 Oct 2017

Cited by 20 | Viewed by 4826

Abstract

Oil spills generate a large cost in environmental and economic terms. Their identification plays an important role in oil-spill response. We propose an oil spill detection method with improved adaptive enhancement on X-band marine radar systems. The radar images used in this paper [...] Read more.

Oil spills generate a large cost in environmental and economic terms. Their identification plays an important role in oil-spill response. We propose an oil spill detection method with improved adaptive enhancement on X-band marine radar systems. The radar images used in this paper were acquired on 21 July 2010, from the teaching-training ship “YUKUN” of the Dalian Maritime University. According to the shape characteristic of co-channel interference, two convolutional filters are used to detect the location of the interference, followed by a mean filter to erase the interference. Small objects, such as bright speckles, are taken as a mask in the radar image and improved by the Fields-of-Experts model. The region marked by strong reflected signals from the sea’s surface is selected to identify oil spills. The selected region is subject to improved adaptive enhancement designed based on features of radar images. With the proposed adaptive enhancement technique, calculated oil spill detection is comparable to visual interpretation in accuracy. Full article

(This article belongs to the Special Issue Sensors for Oil Applications)

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23 pages, 6737 KiB

Open AccessArticle

Evaluation of Sensible Heat Flux and Evapotranspiration Estimates Using a Surface Layer Scintillometer and a Large Weighing Lysimeter

by Jerry E. Moorhead^1,*, Gary W. Marek¹, Paul D. Colaizzi¹, Prasanna H. Gowda², Steven R. Evett¹, David K. Brauer¹, Thomas H. Marek³ and Dana O. Porter⁴

¹ USDA-ARS Conservation and Production Research Laboratory, PO Drawer 10, Bushland, TX 79012, USA

² USDA-ARS Grazinglands Research Laboratory, 7207 West Cheyenne St., El Reno, OK 73036, USA

³ Texas A&M AgriLife Research, 6500 Amarillo Blvd W, Amarillo, TX 79106, USA

⁴ Texas A&M AgriLife Extension Service, 1102 E FM 1294, Lubbock, TX 79403, USA

Sensors 2017, 17(10), 2350; https://doi.org/10.3390/s17102350 - 14 Oct 2017

Cited by 32 | Viewed by 5351

Abstract

Accurate estimates of actual crop evapotranspiration (ET) are important for optimal irrigation water management, especially in arid and semi-arid regions. Common ET sensing methods include Bowen Ratio, Eddy Covariance (EC), and scintillometers. Large weighing lysimeters are considered the ultimate standard for measurement of [...] Read more.

Accurate estimates of actual crop evapotranspiration (ET) are important for optimal irrigation water management, especially in arid and semi-arid regions. Common ET sensing methods include Bowen Ratio, Eddy Covariance (EC), and scintillometers. Large weighing lysimeters are considered the ultimate standard for measurement of ET, however, they are expensive to install and maintain. Although EC and scintillometers are less costly and relatively portable, EC has known energy balance closure discrepancies. Previous scintillometer studies used EC for ground-truthing, but no studies considered weighing lysimeters. In this study, a Surface Layer Scintillometer (SLS) was evaluated for accuracy in determining ET as well as sensible and latent heat fluxes, as compared to a large weighing lysimeter in Bushland, TX. The SLS was installed over irrigated grain sorghum (Sorghum bicolor (L.) Moench) for the period 29 July–17 August 2015 and over grain corn (Zea mays L.) for the period 23 June–2 October 2016. Results showed poor correlation for sensible heat flux, but much better correlation with ET, with r² values of 0.83 and 0.87 for hourly and daily ET, respectively. The accuracy of the SLS was comparable to other ET sensing instruments with an RMSE of 0.13 mm·h⁻¹ (31%) for hourly ET; however, summing hourly values to a daily time step reduced the ET error to 14% (0.75 mm·d⁻¹). This level of accuracy indicates that potential exists for the SLS to be used in some water management applications. As few studies have been conducted to evaluate the SLS for ET estimation, or in combination with lysimetric data, further evaluations would be beneficial to investigate the applicability of the SLS in water resources management. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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17 pages, 7331 KiB

Open AccessArticle

Highly Sensitive and Selective Hydrogen Gas Sensor Using the Mesoporous SnO₂ Modified Layers

by Niuzi Xue¹, Qinyi Zhang^1,*, Shunping Zhang², Pan Zong¹ and Feng Yang¹

¹ School of Material Science and Engineering, Wuhan University of Technology, Wuhan 430070, China

² Department of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

Sensors 2017, 17(10), 2351; https://doi.org/10.3390/s17102351 - 14 Oct 2017

Cited by 47 | Viewed by 7840

Abstract

It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS) gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO₂ (m-SnO₂) [...] Read more.

It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS) gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO₂ (m-SnO₂) powders were prepared by sol-gel method, and the morphology and structure were characterized by X-ray diffraction analysis (XRD), transmission electron microscope (TEM) and Brunauer–Emmett–Teller (BET). The gas sensors were fabricated using m-SnO₂ as the modified layers on the surface of commercial SnO₂ (c-SnO₂) by screen printing technology, and tested for gas sensing towards ethanol, benzene and hydrogen with operating temperatures ranging from 200 °C to 400 °C. Higher sensitivity was achieved by using the modified m-SnO₂ layers on the c-SnO₂ gas sensor, and it was found that the S(c/m2) sensor exhibited the highest response (Ra/Rg = 22.2) to 1000 ppm hydrogen at 400 °C. In this paper, the mechanism of the sensitivity and selectivity improvement of the gas sensors is also discussed. Full article

(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)

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16 pages, 6170 KiB

Open AccessArticle

Automatic Hotspot and Sun Glint Detection in UAV Multispectral Images

by Damian Ortega-Terol¹, David Hernandez-Lopez²

, Rocio Ballesteros³

and Diego Gonzalez-Aguilera^1,*

¹ Higher Polytechnic School of Ávila, University of Salamanca, 05003 Ávila, Spain

² Institute for Regional Development (IDR), University of Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain

³ Regional Centre of Water Research (CREA), University of Castilla-La Mancha, Carretera de las Peñas km 3.2, 02071 Albacete, Spain

Sensors 2017, 17(10), 2352; https://doi.org/10.3390/s17102352 - 15 Oct 2017

Cited by 34 | Viewed by 8995

Abstract

Last advances in sensors, photogrammetry and computer vision have led to high-automation levels of 3D reconstruction processes for generating dense models and multispectral orthoimages from Unmanned Aerial Vehicle (UAV) images. However, these cartographic products are sometimes blurred and degraded due to sun reflection [...] Read more.

Last advances in sensors, photogrammetry and computer vision have led to high-automation levels of 3D reconstruction processes for generating dense models and multispectral orthoimages from Unmanned Aerial Vehicle (UAV) images. However, these cartographic products are sometimes blurred and degraded due to sun reflection effects which reduce the image contrast and colour fidelity in photogrammetry and the quality of radiometric values in remote sensing applications. This paper proposes an automatic approach for detecting sun reflections problems (hotspot and sun glint) in multispectral images acquired with an Unmanned Aerial Vehicle (UAV), based on a photogrammetric strategy included in a flight planning and control software developed by the authors. In particular, two main consequences are derived from the approach developed: (i) different areas of the images can be excluded since they contain sun reflection problems; (ii) the cartographic products obtained (e.g., digital terrain model, orthoimages) and the agronomical parameters computed (e.g., normalized vegetation index-NVDI) are improved since radiometric defects in pixels are not considered. Finally, an accuracy assessment was performed in order to analyse the error in the detection process, getting errors around 10 pixels for a ground sample distance (GSD) of 5 cm which is perfectly valid for agricultural applications. This error confirms that the precision in the detection of sun reflections can be guaranteed using this approach and the current low-cost UAV technology. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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9 pages, 1475 KiB

Open AccessArticle

Relative Humidity Sensor Based on No-Core Fiber Coated by Agarose-Gel Film

by Wei Xu^1,2,3,†

, Jia Shi^1,2,†

, Xianchao Yang^1,2, Degang Xu^1,2

, Feng Rong³, Junfa Zhao³ and Jianquan Yao^1,2,*

¹ Institute of Laser and Optoelectronics, College of Precision Instrument and Optoelectronic Engineering, Tianjin University, Tianjin 300072, China

² Key Laboratory of Optoelectronic Information Science and Technology (Ministry of Education), Tianjin University, Tianjin 300072, China

³ Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems, Tianjin Polytechnic University, Tianjin 300387, China

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2353; https://doi.org/10.3390/s17102353 - 16 Oct 2017

Cited by 34 | Viewed by 5410

Abstract

A relative humidity (RH) sensor based on single-mode–no-core–single-mode fiber (SNCS) structure is proposed and experimentally demonstrated. The agarose gel is coated on the no-core fiber (NCF) as the cladding, and multimode interference (MMI) occurs in the SNCS structure. The transmission spectrum of the [...] Read more.

A relative humidity (RH) sensor based on single-mode–no-core–single-mode fiber (SNCS) structure is proposed and experimentally demonstrated. The agarose gel is coated on the no-core fiber (NCF) as the cladding, and multimode interference (MMI) occurs in the SNCS structure. The transmission spectrum of the sensor is modulated at different ambient relative humidities due to the tunable refractive index property of the agarose gel film. The relative humidity can be measured by the wavelength shift and intensity variation of the dip in the transmission spectra. The humidity response of the sensors, coated with different concentrations and coating numbers of the agarose solution, were experimentally investigated. The wavelength and intensity sensitivity is obtained as −149 pm/%RH and −0.075 dB/%RH in the range of 30% RH to 75% RH, respectively. The rise and fall time is tested to be 4.8 s and 7.1 s, respectively. The proposed sensor has a great potential in real-time RH monitoring. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 6412 KiB

Open AccessArticle

Nighttime Foreground Pedestrian Detection Based on Three-Dimensional Voxel Surface Model

by Jing Li^1,*, Fangbing Zhang¹, Lisong Wei¹, Tao Yang^2,*

and Zhaoyang Lu¹

¹ School of Telecommunications Engineering, Xidian University, Xi’an 710071, China

² School of Computer Science, Northwestern Polytechnical University, Xi’an 710129, China

Sensors 2017, 17(10), 2354; https://doi.org/10.3390/s17102354 - 16 Oct 2017

Cited by 15 | Viewed by 6857

Abstract

Pedestrian detection is among the most frequently-used preprocessing tasks in many surveillance application fields, from low-level people counting to high-level scene understanding. Even though many approaches perform well in the daytime with sufficient illumination, pedestrian detection at night is still a critical and [...] Read more.

Pedestrian detection is among the most frequently-used preprocessing tasks in many surveillance application fields, from low-level people counting to high-level scene understanding. Even though many approaches perform well in the daytime with sufficient illumination, pedestrian detection at night is still a critical and challenging problem for video surveillance systems. To respond to this need, in this paper, we provide an affordable solution with a near-infrared stereo network camera, as well as a novel three-dimensional foreground pedestrian detection model. Specifically, instead of using an expensive thermal camera, we build a near-infrared stereo vision system with two calibrated network cameras and near-infrared lamps. The core of the system is a novel voxel surface model, which is able to estimate the dynamic changes of three-dimensional geometric information of the surveillance scene and to segment and locate foreground pedestrians in real time. A free update policy for unknown points is designed for model updating, and the extracted shadow of the pedestrian is adopted to remove foreground false alarms. To evaluate the performance of the proposed model, the system is deployed in several nighttime surveillance scenes. Experimental results demonstrate that our method is capable of nighttime pedestrian segmentation and detection in real time under heavy occlusion. In addition, the qualitative and quantitative comparison results show that our work outperforms classical background subtraction approaches and a recent RGB-D method, as well as achieving comparable performance with the state-of-the-art deep learning pedestrian detection method even with a much lower hardware cost. Full article

(This article belongs to the Special Issue Imaging Depth Sensors—Sensors, Algorithms and Applications)

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14 pages, 6092 KiB

Open AccessArticle

An Improved Scheduling Algorithm for Data Transmission in Ultrasonic Phased Arrays with Multi-Group Ultrasonic Sensors

by Wenming Tang¹, Guixiong Liu^1,*, Yuzhong Li¹ and Daji Tan²

¹ School of Mechanical & Automotive Engineering, South China University of Technology, Guangzhou 510641, China

² Guangzhou Doppler Electronic Technologies Co., Ltd., Guangzhou 510663, China

Sensors 2017, 17(10), 2355; https://doi.org/10.3390/s17102355 - 16 Oct 2017

Cited by 4 | Viewed by 4241

Abstract

High data transmission efficiency is a key requirement for an ultrasonic phased array with multi-group ultrasonic sensors. Here, a novel FIFOs scheduling algorithm was proposed and the data transmission efficiency with hardware technology was improved. This algorithm includes FIFOs as caches for the [...] Read more.

High data transmission efficiency is a key requirement for an ultrasonic phased array with multi-group ultrasonic sensors. Here, a novel FIFOs scheduling algorithm was proposed and the data transmission efficiency with hardware technology was improved. This algorithm includes FIFOs as caches for the ultrasonic scanning data obtained from the sensors with the output data in a bandwidth-sharing way, on the basis of which an optimal length ratio of all the FIFOs is achieved, allowing the reading operations to be switched among all the FIFOs without time slot waiting. Therefore, this algorithm enhances the utilization ratio of the reading bandwidth resources so as to obtain higher efficiency than the traditional scheduling algorithms. The reliability and validity of the algorithm are substantiated after its implementation in the field programmable gate array (FPGA) technology, and the bandwidth utilization ratio and the real-time performance of the ultrasonic phased array are enhanced. Full article

(This article belongs to the Special Issue Intelligent Sensing Technologies for Nondestructive Evaluation)

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13 pages, 2932 KiB

Open AccessArticle

Selectivity Enhancement in Electronic Nose Based on an Optimized DQN

by Yu Wang

, Jianguo Xing^* and Shu Qian

School of Computer Science & Information Engineering, Zhejiang Gongshang University, Hangzhou 310018, China

Sensors 2017, 17(10), 2356; https://doi.org/10.3390/s17102356 - 16 Oct 2017

Cited by 21 | Viewed by 5456

Abstract

In order to enhance the selectivity of metal oxide gas sensors, we use a flow modulation method to exploit transient sensor information. The method is based on modulating the flow of the carrier gas that brings the species to be measured into the [...] Read more.

In order to enhance the selectivity of metal oxide gas sensors, we use a flow modulation method to exploit transient sensor information. The method is based on modulating the flow of the carrier gas that brings the species to be measured into the sensor chamber. We present an active perception strategy by using a DQN which can optimize the flow modulation online. The advantage of DQN is not only that the classification accuracy is higher than traditional methods such as PCA, but also that it has a good adaptability under small samples and labeled data. From observed values of the sensors array and its past experiences, the DQN learns an action policy to change the flow speed dynamically that maximizes the total rewards (or minimizes the classification error). Meanwhile, a CNN is trained to predict sample class and reward according to current actions and observation of sensors. We demonstrate our proposed methods on a gases classification problem in a real time environment. The results show that the DQN learns to modulate flow to classify different gas and the correct rates of gases are: sesame oil 100%, lactic acid 80%, acetaldehyde 80%, acetic acid 80%, and ethyl acetate 100%, the average correct rate is 88%. Compared with the traditional method, the results of PCA are: sesame oil 100%, acetic acid 24%, acetaldehyde 100%, lactic acid 56%, ethyl acetate 68%, the average accuracy rate is 69.6%. DQN uses fewer steps to achieve higher recognition accuracy and improve the recognition speed, and to reduce the training and testing costs. Full article

(This article belongs to the Special Issue Electronic Tongues and Electronic Noses)

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18 pages, 6373 KiB

Open AccessArticle

Water Quality Sensing and Spatio-Temporal Monitoring Structure with Autocorrelation Kernel Methods

by Iván P. Vizcaíno^1,*, Enrique V. Carrera¹

, Sergio Muñoz-Romero^2,3, Luis H. Cumbal⁴ and José Luis Rojo-Álvarez^2,3

¹ Departamento de Eléctrica y Electrónica, Universidad de las Fuerzas Armadas ESPE, Av. General Rumiñahui s/n, Sangolquí 171-5-231B, Ecuador

² Departamento de Teoría de la Señal y Comunicaciones y Sistemas Telemáticos y de Computación, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Spain

³ Center for Computational Simulation, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Spain

⁴ Centro de Nanociencia y Nanotecnología, Universidad de las Fuerzas Armadas ESPE, Av. General Rumiñahui s/n, Sangolquí 171-5-231B, Ecuador

Sensors 2017, 17(10), 2357; https://doi.org/10.3390/s17102357 - 16 Oct 2017

Cited by 5 | Viewed by 4781

Abstract

Pollution on water resources is usually analyzed with monitoring campaigns, which consist of programmed sampling, measurement, and recording of the most representative water quality parameters. These campaign measurements yields a non-uniform spatio-temporal sampled data structure to characterize complex dynamics phenomena. In this work, [...] Read more.

Pollution on water resources is usually analyzed with monitoring campaigns, which consist of programmed sampling, measurement, and recording of the most representative water quality parameters. These campaign measurements yields a non-uniform spatio-temporal sampled data structure to characterize complex dynamics phenomena. In this work, we propose an enhanced statistical interpolation method to provide water quality managers with statistically interpolated representations of spatial-temporal dynamics. Specifically, our proposal makes efficient use of the a priori available information of the quality parameter measurements through Support Vector Regression (SVR) based on Mercer’s kernels. The methods are benchmarked against previously proposed methods in three segments of the Machángara River and one segment of the San Pedro River in Ecuador, and their different dynamics are shown by statistically interpolated spatial-temporal maps. The best interpolation performance in terms of mean absolute error was the SVR with Mercer’s kernel given by either the Mahalanobis spatial-temporal covariance matrix or by the bivariate estimated autocorrelation function. In particular, the autocorrelation kernel provides with significant improvement of the estimation quality, consistently for all the six water quality variables, which points out the relevance of including a priori knowledge of the problem. Full article

(This article belongs to the Special Issue Spatial Analysis and Remote Sensing)

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13 pages, 9210 KiB

Open AccessArticle

A Wireless Monitoring System Using a Tunneling Sensor Array in a Smart Oral Appliance for Sleep Apnea Treatment

by Kun-Ying Yeh^1,*, Chao-Chi Yeh², Chun-Chang Wu¹

, Kuan Tang¹, Jyun-Yi Wu¹, Yun-Ting Chen², Ming-Xin Xu², Yunn-Jy Chen³, Yao-Joe Yang² and Shey-Shi Lu¹

¹ Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan

² Graduate Institute of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan

³ Department of Dentistry, National Taiwan University Hospital, Taipei 10617, Taiwan

Sensors 2017, 17(10), 2358; https://doi.org/10.3390/s17102358 - 16 Oct 2017

Cited by 7 | Viewed by 5370

Abstract

Sleep apnea is a serious sleep disorder, and the most common type is obstructive sleep apnea (OSA). Untreated OSA will cause lots of potential health problems. Oral appliance therapy is an effective and popular approach for OSA treatment, but making a perfect fit [...] Read more.

Sleep apnea is a serious sleep disorder, and the most common type is obstructive sleep apnea (OSA). Untreated OSA will cause lots of potential health problems. Oral appliance therapy is an effective and popular approach for OSA treatment, but making a perfect fit for each patient is time-consuming and decreases its efficiency considerably. This paper proposes a System-on-a-Chip (SoC) enabled sleep monitoring system in a smart oral appliance, which is capable of intelligently collecting the physiological data about tongue movement through the whole therapy. A tunneling sensor array with an ultra-high sensitivity is incorporated to accurately detect the subtle pressure from the tongue. When the device is placed on the wireless platform, the temporary stored data will be retrieved and wirelessly transmitted to personal computers and cloud storages. The battery will be recharged by harvesting external RF power from the platform. A compact prototype module, whose size is 4.5 × 2.5 × 0.9 cm³, is implemented and embedded inside the oral appliance to demonstrate the tongue movement detection in continuous time frames. The functions of this design are verified by the presented measurement results. This design aims to increase efficiency and make it a total solution for OSA treatment. Full article

(This article belongs to the Special Issue Advanced Physiological Sensing)

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33 pages, 3165 KiB

Open AccessArticle

A Low Cost Sensors Approach for Accurate Vehicle Localization and Autonomous Driving Application

by Rafael Vivacqua^1,*

, Raquel Vassallo² and Felipe Martins³

¹ Federal Institute of Education, Science and Technology of Espirito Santo, Serra ES 29173-087, Brazil

² Department of Electrical Engineering, Federal University of Espirito Santo, Vitória ES 29075-910, Brazil

³ Institute of Engineering, Hanze University of Applied Sciences, Assen 9403AB, The Netherlands

Sensors 2017, 17(10), 2359; https://doi.org/10.3390/s17102359 - 16 Oct 2017

Cited by 49 | Viewed by 11719

Abstract

Autonomous driving in public roads requires precise localization within the range of few centimeters. Even the best current precise localization system based on the Global Navigation Satellite System (GNSS) can not always reach this level of precision, especially in an urban environment, where [...] Read more.

Autonomous driving in public roads requires precise localization within the range of few centimeters. Even the best current precise localization system based on the Global Navigation Satellite System (GNSS) can not always reach this level of precision, especially in an urban environment, where the signal is disturbed by surrounding buildings and artifacts. Laser range finder and stereo vision have been successfully used for obstacle detection, mapping and localization to solve the autonomous driving problem. Unfortunately, Light Detection and Ranging (LIDARs) are very expensive sensors and stereo vision requires powerful dedicated hardware to process the cameras information. In this context, this article presents a low-cost architecture of sensors and data fusion algorithm capable of autonomous driving in narrow two-way roads. Our approach exploits a combination of a short-range visual lane marking detector and a dead reckoning system to build a long and precise perception of the lane markings in the vehicle’s backwards. This information is used to localize the vehicle in a map, that also contains the reference trajectory for autonomous driving. Experimental results show the successful application of the proposed system on a real autonomous driving situation. Full article

(This article belongs to the Special Issue Mechatronic Systems for Automatic Vehicles)

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16 pages, 2846 KiB

Open AccessArticle

Asymmetric Dual-Band Tracking Technique for Optimal Joint Processing of BDS B1I and B1C Signals

by Chuhan Wang, Xiaowei Cui^*, Tianyi Ma, Sihao Zhao

and Mingquan Lu

Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(10), 2360; https://doi.org/10.3390/s17102360 - 16 Oct 2017

Cited by 18 | Viewed by 4322

Abstract

Along with the rapid development of the Global Navigation Satellite System (GNSS), satellite navigation signals have become more diversified, complex, and agile in adapting to increasing market demands. Various techniques have been developed for processing multiple navigation signals to achieve better performance in [...] Read more.

Along with the rapid development of the Global Navigation Satellite System (GNSS), satellite navigation signals have become more diversified, complex, and agile in adapting to increasing market demands. Various techniques have been developed for processing multiple navigation signals to achieve better performance in terms of accuracy, sensitivity, and robustness. This paper focuses on a technique for processing two signals with separate but adjacent center frequencies, such as B1I and B1C signals in the BeiDou global system. The two signals may differ in modulation scheme, power, and initial phase relation and can be processed independently by user receivers; however, the propagation delays of the two signals from a satellite are nearly identical as they are modulated on adjacent frequencies, share the same reference clock, and undergo nearly identical propagation paths to the receiver, resulting in strong coherence between the two signals. Joint processing of these signals can achieve optimal measurement performance due to the increased Gabor bandwidth and power. In this paper, we propose a universal scheme of asymmetric dual-band tracking (ASYM-DBT) to take advantage of the strong coherence, the increased Gabor bandwidth, and power of the two signals in achieving much-reduced thermal noise and more accurate ranging results when compared with the traditional single-band algorithm. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4371 KiB

Open AccessArticle

Camera Calibration Robust to Defocus Using Phase-Shifting Patterns

by Bolin Cai¹

, Yuwei Wang¹, Keyi Wang^1,*, Mengchao Ma²

and Xiangcheng Chen^3,*

¹ Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China

² Department of Instrument Science and Opto-Electronics Engineering, Hefei University of Technology, Hefei 230088, China

³ School of Automation, Wuhan University of Technology, Wuhan 430070, China

Sensors 2017, 17(10), 2361; https://doi.org/10.3390/s17102361 - 16 Oct 2017

Cited by 22 | Viewed by 6218

Abstract

Camera parameters can’t be estimated accurately using traditional calibration methods if the camera is substantially defocused. To tackle this problem, an improved approach based on three phase-shifting circular grating (PCG) arrays is proposed in this paper. Rather than encoding the feature points into [...] Read more.

Camera parameters can’t be estimated accurately using traditional calibration methods if the camera is substantially defocused. To tackle this problem, an improved approach based on three phase-shifting circular grating (PCG) arrays is proposed in this paper. Rather than encoding the feature points into the intensity, the proposed method encodes the feature points into the phase distribution, which can be recovered precisely using phase-shifting methods. The PCG centers are extracted as feature points, which can be located accurately even if the images are severely blurred. Unlike the previous method which just uses a single circle, the proposed method uses a concentric circle to estimate the PCG center, such that the center can be located precisely. This paper also presents a sorting algorithm for the detected feature points automatically. Experiments with both synthetic and real images were carried out to validate the performance of the method. And the results show that the superiority of PCG arrays compared with the concentric circle array even under severe defocus. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 1568 KiB

Open AccessArticle

Research on the Fusion of Dependent Evidence Based on Rank Correlation Coefficient

by Fengjian Shi

, Xiaoyan Su^*, Hong Qian, Ning Yang and Wenhua Han

School of Automation Engineering, Shanghai University of Electric Power, Shanghai 200090, China

Sensors 2017, 17(10), 2362; https://doi.org/10.3390/s17102362 - 16 Oct 2017

Cited by 15 | Viewed by 4001

Abstract

In order to meet the higher accuracy and system reliability requirements, the information fusion for multi-sensor systems is an increasing concern. Dempster–Shafer evidence theory (D–S theory) has been investigated for many applications in multi-sensor information fusion due to its flexibility in uncertainty modeling. [...] Read more.

In order to meet the higher accuracy and system reliability requirements, the information fusion for multi-sensor systems is an increasing concern. Dempster–Shafer evidence theory (D–S theory) has been investigated for many applications in multi-sensor information fusion due to its flexibility in uncertainty modeling. However, classical evidence theory assumes that the evidence is independent of each other, which is often unrealistic. Ignoring the relationship between the evidence may lead to unreasonable fusion results, and even lead to wrong decisions. This assumption severely prevents D–S evidence theory from practical application and further development. In this paper, an innovative evidence fusion model to deal with dependent evidence based on rank correlation coefficient is proposed. The model first uses rank correlation coefficient to measure the dependence degree between different evidence. Then, total discount coefficient is obtained based on the dependence degree, which also considers the impact of the reliability of evidence. Finally, the discount evidence fusion model is presented. An example is illustrated to show the use and effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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9 pages, 1615 KiB

Open AccessArticle

A Phase-Intensity Surface Plasmon Resonance Biosensor for Avian Influenza A (H5N1) Detection

by Chi Lok Wong, Marissa Chua, Heather Mittman, Li Xian Choo, Hann Qian Lim and Malini Olivo^*

Bio-Optical Imaging Group, Singapore Bioimaging Consortium, Helios #01-02, 11 Biopolis Way, Singapore 138667, Singapore

Sensors 2017, 17(10), 2363; https://doi.org/10.3390/s17102363 - 16 Oct 2017

Cited by 38 | Viewed by 6446

Abstract

In this paper, we present a phase-intensity surface plasmon resonance (SPR) biosensor and demonstrate its use for avian influenza A (H5N1) antibody biomarker detection. The sensor probes the intensity variation produced by the steep phase response at surface plasmon excitation. The prism sensor [...] Read more.

In this paper, we present a phase-intensity surface plasmon resonance (SPR) biosensor and demonstrate its use for avian influenza A (H5N1) antibody biomarker detection. The sensor probes the intensity variation produced by the steep phase response at surface plasmon excitation. The prism sensor head is fixed between a pair of polarizers with a perpendicular orientation angle and a forbidden transmission path. At SPR, a steep phase change is introduced between the p- and s-polarized light, and this rotates the polarization ellipse of the transmission beam. This allows the light at resonance to be transmitted and a corresponding intensity change to be detected. Neither time-consuming interference fringe analysis nor a phase extraction process is required. In refractive index sensing experiments, the sensor resolution was determined to be 6.3 × 10⁻⁶ refractive index values (RIU). The sensor has been further applied for H5N1 antibody biomarker detection, and the sensor resolution was determined to be 193.3 ng mL⁻¹, compared to 1 μg mL⁻¹ and 0.5 μg mL⁻¹, as reported in literature for influenza antibody detection using commercial Biacore systems. It represents a 517.3% and 258.7% improvement in detection limit, respectively. With the unique features of label-free, real-time, and sensitive detection, the phase-intensity SPR biosensor has promising potential applications in influenza detection. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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30 pages, 6718 KiB

Open AccessArticle

Modeling the Energy Performance of LoRaWAN

by Lluís Casals

, Bernat Mir

, Rafael Vidal

and Carles Gomez^*

Department of Network Engineering, Universitat Politècnica de Catalunya/Fundació i2Cat, C/Esteve Terradas, 7, 08860 Castelldefels, Spain

Sensors 2017, 17(10), 2364; https://doi.org/10.3390/s17102364 - 16 Oct 2017

Cited by 241 | Viewed by 17538

Abstract

LoRaWAN is a flagship Low-Power Wide Area Network (LPWAN) technology that has highly attracted much attention from the community in recent years. Many LoRaWAN end-devices, such as sensors or actuators, are expected not to be powered by the electricity grid; therefore, it is [...] Read more.

LoRaWAN is a flagship Low-Power Wide Area Network (LPWAN) technology that has highly attracted much attention from the community in recent years. Many LoRaWAN end-devices, such as sensors or actuators, are expected not to be powered by the electricity grid; therefore, it is crucial to investigate the energy consumption of LoRaWAN. However, published works have only focused on this topic to a limited extent. In this paper, we present analytical models that allow the characterization of LoRaWAN end-device current consumption, lifetime and energy cost of data delivery. The models, which have been derived based on measurements on a currently prevalent LoRaWAN hardware platform, allow us to quantify the impact of relevant physical and Medium Access Control (MAC) layer LoRaWAN parameters and mechanisms, as well as Bit Error Rate (BER) and collisions, on energy performance. Among others, evaluation results show that an appropriately configured LoRaWAN end-device platform powered by a battery of 2400 mAh can achieve a 1-year lifetime while sending one message every 5 min, and an asymptotic theoretical lifetime of 6 years for infrequent communication. Full article

(This article belongs to the Section Sensor Networks)

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18 pages, 5055 KiB

Open AccessArticle

Air-Coupled Ultrasonic Receivers with High Electromechanical Coupling PMN-32%PT Strip-Like Piezoelectric Elements

by Rymantas J. Kazys, Reimondas Sliteris and Justina Sestoke^*

Ultrasound Institute of Kaunas University of Technology, LT-51423 Kaunas, Lithuania

Sensors 2017, 17(10), 2365; https://doi.org/10.3390/s17102365 - 16 Oct 2017

Cited by 6 | Viewed by 4822

Abstract

For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is [...] Read more.

For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is more than 0.9. Operation of ultrasonic transducers with such piezoelectric elements in transmitting and receiving modes is rather different. Therefore, for transmission and reception of ultrasonic signals, separate piezoelectric elements with different dimensions must be used. The objective of this research was development of novel air-coupled ultrasonic receivers with PMN-32%PT strip-like piezoelectric elements vibrating in a transverse-extension mode with electromechanically controlled operation and suitable for applications in ultrasonic arrays. Performance of piezoelectric receivers made of the PMN-32%PT strip-like elements vibrating in this mode may be efficiently controlled by selecting geometry of the electrodes covering side surfaces of the piezoelectric element. It is equivalent to introduction of electromechanical damping which does not require any additional backing element. For this purpose; we have proposed the continuous electrodes to divide into two pairs of electrodes. The one pair is used to pick up the electric signal; another one is exploited for electromechanical damping. Two types of electrodes may be used—rectangular or non-rectangular—with a gap between them directed at some angle, usually 45°. The frequency bandwidth is wider (up to 9 kHz) in the case of non-rectangular electrodes. The strip-like acoustic matching element bonded to the tip of the PMN-32%PT crystal may significantly enhance the performance of the ultrasonic receiver. It was proposed to use for this purpose AIREX T10.110 rigid polymer foam, the acoustic impedance of which is close to the optimal value necessary for matching with air. It was found that in order to get a wide bandwidth the length of the matching strip should be selected not a quarter wavelength λ/4 at the antiresonance frequency but at lower frequency. It allowed achieving the frequency bandwidth (14–18)% with respect to the central frequency at −3 dB level. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 4006 KiB

Open AccessArticle

Effects of Moisture and Particle Size on Quantitative Determination of Total Organic Carbon (TOC) in Soils Using Near-Infrared Spectroscopy

by Elena Tamburini^1,*

, Fabio Vincenzi¹, Stefania Costa¹

, Paolo Mantovi², Paola Pedrini¹ and Giuseppe Castaldelli¹

¹ Department of Life Science and Biotechnology, University of Ferrara, Via L. Borsari, 46, 44121 Ferrara, Italy

² Research Centre on Animal Production, CRPA, Viale Timavo, 43/2, 42121 Reggio Emilia, Italy

Sensors 2017, 17(10), 2366; https://doi.org/10.3390/s17102366 - 17 Oct 2017

Cited by 28 | Viewed by 6289

Abstract

Near-Infrared Spectroscopy is a cost-effective and environmentally friendly technique that could represent an alternative to conventional soil analysis methods, including total organic carbon (TOC). Soil fertility and quality are usually measured by traditional methods that involve the use of hazardous and strong chemicals. [...] Read more.

Near-Infrared Spectroscopy is a cost-effective and environmentally friendly technique that could represent an alternative to conventional soil analysis methods, including total organic carbon (TOC). Soil fertility and quality are usually measured by traditional methods that involve the use of hazardous and strong chemicals. The effects of physical soil characteristics, such as moisture content and particle size, on spectral signals could be of great interest in order to understand and optimize prediction capability and set up a robust and reliable calibration model, with the future perspective of being applied in the field. Spectra of 46 soil samples were collected. Soil samples were divided into three data sets: unprocessed, only dried and dried, ground and sieved, in order to evaluate the effects of moisture and particle size on spectral signals. Both separate and combined normalization methods including standard normal variate (SNV), multiplicative scatter correction (MSC) and normalization by closure (NCL), as well as smoothing using first and second derivatives (DV1 and DV2), were applied to a total of seven cases. Pretreatments for model optimization were designed and compared for each data set. The best combination of pretreatments was achieved by applying SNV and DV2 on partial least squares (PLS) modelling. There were no significant differences between the predictions using the three different data sets (p < 0.05). Finally, a unique database including all three data sets was built to include all the sources of sample variability that were tested and used for final prediction. External validation of TOC was carried out on 16 unknown soil samples to evaluate the predictive ability of the final combined calibration model. Hence, we demonstrate that sample preprocessing has minor influence on the quality of near infrared spectroscopy (NIR) predictions, laying the ground for a direct and fast in situ application of the method. Data can be acquired outside the laboratory since the method is simple and does not need more than a simple band ratio of the spectra. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 4589 KiB

Open AccessArticle

Vibration Noise Modeling for Measurement While Drilling System Based on FOGs

by Chunxi Zhang, Lu Wang, Shuang Gao^*, Tie Lin and Xianmu Li

Key Laboratory of Inertial Technology, Institute of Opto-electronics Technology, School of Instrument Science and Opto-electronics Engineering, Beihang University, Beijing 100191, China

Sensors 2017, 17(10), 2367; https://doi.org/10.3390/s17102367 - 17 Oct 2017

Cited by 9 | Viewed by 5186

Abstract

Aiming to improve survey accuracy of Measurement While Drilling (MWD) based on Fiber Optic Gyroscopes (FOGs) in the long period, the external aiding sources are fused into the inertial navigation by the Kalman filter (KF) method. The KF method needs to model the [...] Read more.

Aiming to improve survey accuracy of Measurement While Drilling (MWD) based on Fiber Optic Gyroscopes (FOGs) in the long period, the external aiding sources are fused into the inertial navigation by the Kalman filter (KF) method. The KF method needs to model the inertial sensors’ noise as the system noise model. The system noise is modeled as white Gaussian noise conventionally. However, because of the vibration while drilling, the noise in gyros isn’t white Gaussian noise any more. Moreover, an incorrect noise model will degrade the accuracy of KF. This paper developed a new approach for noise modeling on the basis of dynamic Allan variance (DAVAR). In contrast to conventional white noise models, the new noise model contains both the white noise and the color noise. With this new noise model, the KF for the MWD was designed. Finally, two vibration experiments have been performed. Experimental results showed that the proposed vibration noise modeling approach significantly improved the estimated accuracies of the inertial sensor drifts. Compared the navigation results based on different noise model, with the DAVAR noise model, the position error and the toolface angle error are reduced more than 90%. The velocity error is reduced more than 65%. The azimuth error is reduced more than 50%. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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35 pages, 6525 KiB

Open AccessReview

Review and Analysis of Peak Tracking Techniques for Fiber Bragg Grating Sensors

by Daniele Tosi^1,2

¹ School of Engineering, Nazarbayev University, Astana 010000, Kazakhstan

² Laboratory of Biosensors and Bioinstruments, National Laboratory Astana, Nazarbayev University, Astana 010000, Kazakhstan

Sensors 2017, 17(10), 2368; https://doi.org/10.3390/s17102368 - 17 Oct 2017

Cited by 232 | Viewed by 12034

Abstract

Fiber Bragg Grating (FBG) sensors are among the most popular elements for fiber optic sensor networks used for the direct measurement of temperature and strain. Modern FBG interrogation setups measure the FBG spectrum in real-time, and determine the shift of the Bragg wavelength [...] Read more.

Fiber Bragg Grating (FBG) sensors are among the most popular elements for fiber optic sensor networks used for the direct measurement of temperature and strain. Modern FBG interrogation setups measure the FBG spectrum in real-time, and determine the shift of the Bragg wavelength of the FBG in order to estimate the physical parameters. The problem of determining the peak wavelength of the FBG from a spectral measurement limited in resolution and noise, is referred as the peak-tracking problem. In this work, the several peak-tracking approaches are reviewed and classified, outlining their algorithmic implementations: the methods based on direct estimation, interpolation, correlation, resampling, transforms, and optimization are discussed in all their proposed implementations. Then, a simulation based on coupled-mode theory compares the performance of the main peak-tracking methods, in terms of accuracy and signal to noise ratio resilience. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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20 pages, 4833 KiB

Open AccessArticle

Influence of Time-Pickoff Circuit Parameters on LiDAR Range Precision

by Xiaolu Li^1,2,*

, Hongming Wang^1,2, Bingwei Yang^1,2, Jiayue Huyan^1,2 and Lijun Xu^1,2

¹ School of Instrument Science and Opto-Electronic Engineering, Beihang University, Beijing 100191, China

² State Key Laboratory of Inertial Science and Technology, School of Instrumentation Science and Opto-electronic Engineering, Beihang University, Beijing 100191, China

Sensors 2017, 17(10), 2369; https://doi.org/10.3390/s17102369 - 17 Oct 2017

Cited by 20 | Viewed by 7025

Abstract

A pulsed time-of-flight (TOF) measurement-based Light Detection and Ranging (LiDAR) system is more effective for medium-long range distances. As a key ranging unit, a time-pickoff circuit based on automatic gain control (AGC) and constant fraction discriminator (CFD) is designed to reduce the walk [...] Read more.

A pulsed time-of-flight (TOF) measurement-based Light Detection and Ranging (LiDAR) system is more effective for medium-long range distances. As a key ranging unit, a time-pickoff circuit based on automatic gain control (AGC) and constant fraction discriminator (CFD) is designed to reduce the walk error and the timing jitter for obtaining the accurate time interval. Compared with Cramer–Rao lower bound (CRLB) and the estimation of the timing jitter, four parameters-based Monte Carlo simulations are established to show how the range precision is influenced by the parameters, including pulse amplitude, pulse width, attenuation fraction and delay time of the CFD. Experiments were carried out to verify the relationship between the range precision and three of the parameters, exclusing pulse width. It can be concluded that two parameters of the ranging circuit (attenuation fraction and delay time) were selected according to the ranging performance of the minimum pulse amplitude. The attenuation fraction should be selected in the range from 0.2 to 0.6 to achieve high range precision. The selection criterion of the time-pickoff circuit parameters is helpful for the ranging circuit design of TOF LiDAR system. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 3106 KiB

Open AccessArticle

Alternative Opportunistic Alert Diffusion to Support Infrastructure Failure during Disasters

by Farouk Mezghani^*

and Nathalie Mitton

Inria Lille—Nord Europe, 40 Avenue Halley, 59650 Villeneuve d’Ascq, France

Sensors 2017, 17(10), 2370; https://doi.org/10.3390/s17102370 - 17 Oct 2017

Cited by 4 | Viewed by 3666

Abstract

Opportunistic communications present a promising solution for disaster network recovery in emergency situations such as hurricanes, earthquakes, and floods, where infrastructure might be destroyed. Some recent works in the literature have proposed opportunistic-based disaster recovery solutions, but they have omitted the consideration of [...] Read more.

Opportunistic communications present a promising solution for disaster network recovery in emergency situations such as hurricanes, earthquakes, and floods, where infrastructure might be destroyed. Some recent works in the literature have proposed opportunistic-based disaster recovery solutions, but they have omitted the consideration of mobile devices that come with different network technologies and various initial energy levels. This work presents COPE, an energy-aware Cooperative OPportunistic alErt diffusion scheme for trapped survivors to use during disaster scenarios to report their position and ease their rescue operation. It aims to maintain mobile devices functional for as long as possible for maximum network coverage until reaching proximate rescuers. COPE deals with mobile devices that come with an assortment of networks and aims to perform systematic network interface selection. Furthermore, it considers mobile devices with various energy levels and allows low-energy nodes to hold their charge for longer time with the support of high-energy nodes. A proof-of-concept implementation has been performed to study the doability and efficiency of COPE, and to highlight the lessons learned. Full article

(This article belongs to the Special Issue Sensor Intelligent Data Analysis for Social Networks: Theory and Applications)

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16 pages, 10145 KiB

Open AccessArticle

Comparing RIEGL RiCOPTER UAV LiDAR Derived Canopy Height and DBH with Terrestrial LiDAR

by Benjamin Brede^1,*

, Alvaro Lau^1,2

, Harm M. Bartholomeus¹ and Lammert Kooistra¹

¹ Laboratory of Geo-Information Science and Remote Sensing, Wageningen University & Research, Droevendaalsesteeg, 36708 PB Wageningen, The Netherlands

² Center for International Forestry Research (CIFOR), Situ Gede, Sindang Barang, Bogor 16680, Indonesia

Sensors 2017, 17(10), 2371; https://doi.org/10.3390/s17102371 - 17 Oct 2017

Cited by 204 | Viewed by 24010

Abstract

In recent years, LIght Detection And Ranging (LiDAR) and especially Terrestrial Laser Scanning (TLS) systems have shown the potential to revolutionise forest structural characterisation by providing unprecedented 3D data. However, manned Airborne Laser Scanning (ALS) requires costly campaigns and produces relatively low point [...] Read more.

In recent years, LIght Detection And Ranging (LiDAR) and especially Terrestrial Laser Scanning (TLS) systems have shown the potential to revolutionise forest structural characterisation by providing unprecedented 3D data. However, manned Airborne Laser Scanning (ALS) requires costly campaigns and produces relatively low point density, while TLS is labour intense and time demanding. Unmanned Aerial Vehicle (UAV)-borne laser scanning can be the way in between. In this study, we present first results and experiences with the RIEGL RiCOPTER with VUX

^{®}

-1UAV ALS system and compare it with the well tested RIEGL VZ-400 TLS system. We scanned the same forest plots with both systems over the course of two days. We derived Digital Terrain Model (DTMs), Digital Surface Model (DSMs) and finally Canopy Height Model (CHMs) from the resulting point clouds. ALS CHMs were on average 11.5

c m

higher in five plots with different canopy conditions. This showed that TLS could not always detect the top of canopy. Moreover, we extracted trunk segments of 58 trees for ALS and TLS simultaneously, of which 39 could be used to model Diameter at Breast Height (DBH). ALS DBH showed a high agreement with TLS DBH with a correlation coefficient of 0.98 and root mean square error of 4.24

c m

. We conclude that RiCOPTER has the potential to perform comparable to TLS for estimating forest canopy height and DBH under the studied forest conditions. Further research should be directed to testing UAV-borne LiDAR for explicit 3D modelling of whole trees to estimate tree volume and subsequently Above-Ground Biomass (AGB). Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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13 pages, 11555 KiB

Open AccessArticle

MEMS Tunable Diffraction Grating for Spaceborne Imaging Spectroscopic Applications

by Sanathanan S. Muttikulangara^1,*

, Maciej Baranski¹, Shakil Rehman², Liangxing Hu¹ and Jianmin Miao¹

¹ School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

² Singapore-MIT Alliance for Research and Technology (SMART), 1 CREATE Way, Singapore 138602, Singapore

Sensors 2017, 17(10), 2372; https://doi.org/10.3390/s17102372 - 17 Oct 2017

Cited by 15 | Viewed by 11140

Abstract

Diffraction gratings are among the most commonly used optical elements in applications ranging from spectroscopy and metrology to lasers. Numerous methods have been adopted for the fabrication of gratings, including microelectromechanical system (MEMS) fabrication which is by now mature and presents opportunities for [...] Read more.

Diffraction gratings are among the most commonly used optical elements in applications ranging from spectroscopy and metrology to lasers. Numerous methods have been adopted for the fabrication of gratings, including microelectromechanical system (MEMS) fabrication which is by now mature and presents opportunities for tunable gratings through inclusion of an actuation mechanism. We have designed, modeled, fabricated and tested a silicon based pitch tunable diffraction grating (PTG) with relatively large resolving power that could be deployed in a spaceborne imaging spectrometer, for example in a picosatellite. We have carried out a detailed analytical modeling of PTG, based on a mass spring system. The device has an effective fill factor of 52% and resolving power of 84. Tuning provided by electrostatic actuation results in a displacement of 2.7

μ m

at 40

V

. Further, we have carried out vibration testing of the fabricated structure to evaluate its feasibility for spaceborne instruments. Full article

(This article belongs to the Special Issue MEMS Resonators)

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17 pages, 4307 KiB

Open AccessArticle

Design of a Wireless Sensor System with the Algorithms of Heart Rate and Agility Index for Athlete Evaluation

by Meina Li^1,* and Youn Tae Kim^2,*

¹ College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130061, China

² Department of IT Fusion Technology, Graduate School, Chosun University, Gwangju 61452, Korea

Sensors 2017, 17(10), 2373; https://doi.org/10.3390/s17102373 - 17 Oct 2017

Cited by 14 | Viewed by 7204

Abstract

Athlete evaluation systems can effectively monitor daily training and boost performance to reduce injuries. Conventional heart-rate measurement systems can be easily affected by artifact movement, especially in the case of athletes. Significant noise can be generated owing to high-intensity activities. To improve the [...] Read more.

Athlete evaluation systems can effectively monitor daily training and boost performance to reduce injuries. Conventional heart-rate measurement systems can be easily affected by artifact movement, especially in the case of athletes. Significant noise can be generated owing to high-intensity activities. To improve the comfort for athletes and the accuracy of monitoring, we have proposed to combine robust heart rate and agility index monitoring algorithms into a small, light, and single node. A band-pass-filter-based R-wave detection algorithm was developed. The agility index was calculated by preprocessing with band-pass filtering and employing the zero-crossing detection method. The evaluation was conducted under both laboratory and field environments to verify the accuracy and reliability of the algorithm. The heart rate and agility index measurements can be wirelessly transmitted to a personal computer in real time by the ZigBee telecommunication system. The results show that the error rate of measurement of the heart rate is within 2%, which is comparable with that of the traditional wired measurement method. The sensitivity of the agility index, which could be distinguished as the activity speed, changed slightly. Thus, we confirmed that the developed algorithm could be used in an effective and safe exercise-evaluation system for athletes. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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23 pages, 2210 KiB

Open AccessArticle

Data Access Based on a Guide Map of the Underwater Wireless Sensor Network

by Zhengxian Wei^1,2, Min Song³, Guisheng Yin¹, Houbing Song⁴, Hongbin Wang¹

, Xuefei Ma^5,6,*

and Albert M. K. Cheng⁷

¹ College of Computer Science and Technology, Harbin Engineering University, Harbin 150001, China

² System Engineering Innovation Center, Systems Engineering Research Institute, Beijing 100094, China

³ Information Technology Centre, Beijing Foreign Studies University, Beijing 100089, China

⁴ Department of Electrical, Computer, Software, and Systems Engineering, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA

⁵ College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China

⁶ National Key Laboratory of Underwater Acoustic Science and Technology, Harbin Engineering University, Harbin 150001, China

⁷ Department of Computer Science, University of Houston, Houston, TX 77204, USA

Sensors 2017, 17(10), 2374; https://doi.org/10.3390/s17102374 - 17 Oct 2017

Cited by 4 | Viewed by 3955

Abstract

Underwater wireless sensor networks (UWSNs) represent an area of increasing research interest, as data storage, discovery, and query of UWSNs are always challenging issues. In this paper, a data access based on a guide map (DAGM) method is proposed for UWSNs. In DAGM, [...] Read more.

Underwater wireless sensor networks (UWSNs) represent an area of increasing research interest, as data storage, discovery, and query of UWSNs are always challenging issues. In this paper, a data access based on a guide map (DAGM) method is proposed for UWSNs. In DAGM, the metadata describes the abstracts of data content and the storage location. The center ring is composed of nodes according to the shortest average data query path in the network in order to store the metadata, and the data guide map organizes, diffuses and synchronizes the metadata in the center ring, providing the most time-saving and energy-efficient data query service for the user. For this method, firstly the data is stored in the UWSN. The storage node is determined, the data is transmitted from the sensor node (data generation source) to the storage node, and the metadata is generated for it. Then, the metadata is sent to the center ring node that is the nearest to the storage node and the data guide map organizes the metadata, diffusing and synchronizing it to the other center ring nodes. Finally, when there is query data in any user node, the data guide map will select a center ring node nearest to the user to process the query sentence, and based on the shortest transmission delay and lowest energy consumption, data transmission routing is generated according to the storage location abstract in the metadata. Hence, specific application data transmission from the storage node to the user is completed. The simulation results demonstrate that DAGM has advantages with respect to data access time and network energy consumption. Full article

(This article belongs to the Section Sensor Networks)

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30 pages, 5633 KiB

Open AccessReview

Disease-Related Detection with Electrochemical Biosensors: A Review

by Ying Huang¹, Jin Xu¹, Junjie Liu¹, Xiangyang Wang³ and Bin Chen^1,2,*

¹ Chongqing Key Laboratory of Non-linear Circuit and Intelligent Information Processing, College of Electronic and Information Engineering, Southwest University, Chongqing 400715, China

² Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University) Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China

³ CET-College of Engineering and Technology, Southwest University, Chongqing 400715, China

Sensors 2017, 17(10), 2375; https://doi.org/10.3390/s17102375 - 17 Oct 2017

Cited by 136 | Viewed by 13290

Abstract

Rapid diagnosis of diseases at their initial stage is critical for effective clinical outcomes and promotes general public health. Classical in vitro diagnostics require centralized laboratories, tedious work and large, expensive devices. In recent years, numerous electrochemical biosensors have been developed and proposed [...] Read more.

Rapid diagnosis of diseases at their initial stage is critical for effective clinical outcomes and promotes general public health. Classical in vitro diagnostics require centralized laboratories, tedious work and large, expensive devices. In recent years, numerous electrochemical biosensors have been developed and proposed for detection of various diseases based on specific biomarkers taking advantage of their features, including sensitivity, selectivity, low cost and rapid response. This article reviews research trends in disease-related detection with electrochemical biosensors. Focus has been placed on the immobilization mechanism of electrochemical biosensors, and the techniques and materials used for the fabrication of biosensors are introduced in details. Various biomolecules used for different diseases have been listed. Besides, the advances and challenges of using electrochemical biosensors for disease-related applications are discussed. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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10 pages, 465 KiB

Open AccessArticle

Classification of Data from Electronic Nose Using Gradient Tree Boosting Algorithm

by Yuan Luo^1,2, Wenbin Ye^1,*, Xiaojin Zhao¹

, Xiaofang Pan³ and Yuan Cao¹

¹ School of Electronic Science and Technology, Shenzhen University, Shenzhen 518060, China

² Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

³ School of Information Engineering, Shenzhen University, Shenzhen 518060, China

Sensors 2017, 17(10), 2376; https://doi.org/10.3390/s17102376 - 18 Oct 2017

Cited by 29 | Viewed by 5330

Abstract

In this paper, an approach that can fast classify the data from the electronic nose is presented. In this approach the gradient tree boosting algorithm is used to classify the gas data and the experiment results show that the proposed gradient tree boosting [...] Read more.

In this paper, an approach that can fast classify the data from the electronic nose is presented. In this approach the gradient tree boosting algorithm is used to classify the gas data and the experiment results show that the proposed gradient tree boosting algorithm achieved high performance on this classification problem, outperforming other algorithms as comparison. In addition, electronic nose we used only requires a few seconds of data after the gas reaction begins. Therefore, the proposed approach can realize a fast recognition of gas, as it does not need to wait for the gas reaction to reach steady state. Full article

(This article belongs to the Special Issue Artificial Olfaction and Taste)

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21 pages, 1304 KiB

Open AccessArticle

Sensor-Data Fusion for Multi-Person Indoor Location Estimation

by Parisa Mohebbi^*

, Eleni Stroulia^*

and Ioanis Nikolaidis^*

Department of Computing Science, University of Alberta, Edmonton, AB T6G 2R3, Canada

Sensors 2017, 17(10), 2377; https://doi.org/10.3390/s17102377 - 18 Oct 2017

Cited by 17 | Viewed by 5636

Abstract

We consider the problem of estimating the location of people as they move and work in indoor environments. More specifically, we focus on the scenario where one of the persons of interest is unable or unwilling to carry a smartphone, or any other [...] Read more.

We consider the problem of estimating the location of people as they move and work in indoor environments. More specifically, we focus on the scenario where one of the persons of interest is unable or unwilling to carry a smartphone, or any other “wearable” device, which frequently arises in caregiver/cared-for situations. We consider the case of indoor spaces populated with anonymous binary sensors (Passive Infrared motion sensors) and eponymous wearable sensors (smartphones interacting with Estimote beacons), and we propose a solution to the resulting sensor-fusion problem. Using a data set with sensor readings collected from one-person and two-person sessions engaged in a variety of activities of daily living, we investigate the relative merits of relying solely on anonymous sensors, solely on eponymous sensors, or on their combination. We examine how the lack of synchronization across different sensing sources impacts the quality of location estimates, and discuss how it could be mitigated without resorting to device-level mechanisms. Finally, we examine the trade-off between the sensors’ coverage of the monitored space and the quality of the location estimates. Full article

(This article belongs to the Special Issue Next Generation Wireless Technologies for Internet of Things)

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22 pages, 18426 KiB

Open AccessArticle

Time Series UAV Image-Based Point Clouds for Landslide Progression Evaluation Applications

by Abdulla Al-Rawabdeh^1,2,*

, Adel Moussa^2,3, Marzieh Foroutan⁴

, Naser El-Sheimy² and Ayman Habib⁵

¹ Department of Earth and Environmental Science, Yarmouk University, Irbid 21163, Jordan

² Department of Geomatics Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

³ Department of Electrical Engineering, Port-Said University, Port Said 42523, Egypt

⁴ Department of Geography, University of Calgary, Calgary, AB T2N 1N4, Canada

⁵ Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA

Sensors 2017, 17(10), 2378; https://doi.org/10.3390/s17102378 - 18 Oct 2017

Cited by 40 | Viewed by 7207

Abstract

Landslides are major and constantly changing threats to urban landscapes and infrastructure. It is essential to detect and capture landslide changes regularly. Traditional methods for monitoring landslides are time-consuming, costly, dangerous, and the quality and quantity of the data is sometimes unable to [...] Read more.

Landslides are major and constantly changing threats to urban landscapes and infrastructure. It is essential to detect and capture landslide changes regularly. Traditional methods for monitoring landslides are time-consuming, costly, dangerous, and the quality and quantity of the data is sometimes unable to meet the necessary requirements of geotechnical projects. This motivates the development of more automatic and efficient remote sensing approaches for landslide progression evaluation. Automatic change detection involving low-altitude unmanned aerial vehicle image-based point clouds, although proven, is relatively unexplored, and little research has been done in terms of accounting for volumetric changes. In this study, a methodology for automatically deriving change displacement rates, in a horizontal direction based on comparisons between extracted landslide scarps from multiple time periods, has been developed. Compared with the iterative closest projected point (ICPP) registration method, the developed method takes full advantage of automated geometric measuring, leading to fast processing. The proposed approach easily processes a large number of images from different epochs and enables the creation of registered image-based point clouds without the use of extensive ground control point information or further processing such as interpretation and image correlation. The produced results are promising for use in the field of landslide research. Full article

(This article belongs to the Special Issue Remote Sensing and GIS for Geo-Hazards and Disasters)

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24 pages, 1109 KiB

Open AccessArticle

Performance Analysis for Joint Target Parameter Estimation in UMTS-Based Passive Multistatic Radar with Antenna Arrays Using Modified Cramér-Rao Lower Bounds

by Chenguang Shi^1,†

, Fei Wang^1,*,†, Sana Salous^2,† and Jianjiang Zhou^1,†

¹ Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

² School of Engineering and Computing Sciences, Durham University, Durham DH1 3DE, UK

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2379; https://doi.org/10.3390/s17102379 - 18 Oct 2017

Cited by 6 | Viewed by 4435

Abstract

In this study, the modified Cramér-Rao lower bounds (MCRLBs) on the joint estimation of target position and velocity is investigated for a universal mobile telecommunication system (UMTS)-based passive multistatic radar system with antenna arrays. First, we analyze the log-likelihood redfunction of the received [...] Read more.

In this study, the modified Cramér-Rao lower bounds (MCRLBs) on the joint estimation of target position and velocity is investigated for a universal mobile telecommunication system (UMTS)-based passive multistatic radar system with antenna arrays. First, we analyze the log-likelihood redfunction of the received signal for a complex Gaussian extended target. Then, due to the non-deterministic transmitted data symbols, the analytically closed-form expressions of the MCRLBs on the Cartesian coordinates of target position and velocity are derived for a multistatic radar system with

N_{t}

UMTS-based transmit station of

L_{t}

antenna elements and

N_{r}

receive stations of

L_{r}

antenna elements. With the aid of numerical simulations, it is shown that increasing the number of receiving elements in each receive station can reduce the estimation errors. In addition, it is demonstrated that the MCRLB is not only a function of signal-to-noise ratio (SNR), the number of receiving antenna elements and the properties of the transmitted UMTS signals, but also a function of the relative geometric configuration between the target and the multistatic radar system.The analytical expressions for MCRLB will open up a new dimension for passive multistatic radar system by aiding the optimal placement of receive stations to improve the target parameter estimation performance. Full article

(This article belongs to the Special Issue Recent Advances in Array Signal Processing and Its Applications in IoT Security)

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18 pages, 6896 KiB

Open AccessArticle

Determination of Odour Interactions of Three-Component Gas Mixtures Using an Electronic Nose

by Bartosz Szulczyński¹, Jacek Namieśnik²

and Jacek Gębicki^1,*

¹ Department of Chemical and Process Engineering, Faculty of Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza Str., 80233 Gdańsk, Poland

² Department of Analytical Chemistry, Faculty of Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza Str., 80233 Gdańsk, Poland

Sensors 2017, 17(10), 2380; https://doi.org/10.3390/s17102380 - 18 Oct 2017

Cited by 50 | Viewed by 5612

Abstract

The paper presents an application of an electronic nose prototype comprised of six TGS-type sensors and one PID-type sensor to identify odour interaction phenomena in odorous three-component mixtures. The investigation encompassed eight odorous mixtures—toluene-acetone-triethylamine and formaldehyde-butyric acid-pinene—characterized by different odour intensity and hedonic [...] Read more.

The paper presents an application of an electronic nose prototype comprised of six TGS-type sensors and one PID-type sensor to identify odour interaction phenomena in odorous three-component mixtures. The investigation encompassed eight odorous mixtures—toluene-acetone-triethylamine and formaldehyde-butyric acid-pinene—characterized by different odour intensity and hedonic tone. A principal component regression (PCR) calibration model was used for evaluation of predicted odour intensity and hedonic tone. Correctness of identification of odour interactions in the odorous three-component mixtures was determined based on the results obtained with the electronic nose. The results indicated a level of 75–80% for odour intensity and 57–73% for hedonic tone. The average root mean square error of prediction amounted to 0.03–0.06 for odour intensity determination and 0.07–0.34 for hedonic tone evaluation of the odorous three-component mixtures. Full article

(This article belongs to the Special Issue Artificial Olfaction and Taste)

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12 pages, 1650 KiB

Open AccessArticle

Optical Sensing of Weed Infestations at Harvest

by Judit Barroso^1,*, John McCallum² and Dan Long²

¹ Columbia Basin Agricultural Research Center, Oregon State University, Adams, OR 97810, USA

² Soil and Water Conservation Research Unit, Agricultural Research Service (USDA-ARS), Adams, OR 97810, USA

Sensors 2017, 17(10), 2381; https://doi.org/10.3390/s17102381 - 19 Oct 2017

Cited by 4 | Viewed by 4935

Abstract

Kochia (Kochia scoparia L.), Russian thistle (Salsola tragus L.), and prickly lettuce (Lactuca serriola L.) are economically important weeds infesting dryland wheat (Triticum aestivum L.) production systems in the western United States. Those weeds produce most of their seeds [...] Read more.

Kochia (Kochia scoparia L.), Russian thistle (Salsola tragus L.), and prickly lettuce (Lactuca serriola L.) are economically important weeds infesting dryland wheat (Triticum aestivum L.) production systems in the western United States. Those weeds produce most of their seeds post-harvest. The objectives of this study were to determine the ability of an optical sensor, installed for on-the-go measurement of grain protein concentration, to detect the presence of green plant matter in flowing grain and assess the potential usefulness of this information for mapping weeds at harvest. Spectra of the grain stream were recorded continuously at a rate of 0.33 Hz during harvest of two spring wheat fields of 1.9 and 5.4 ha. All readings were georeferenced using a Global Positioning System (GPS) receiver with 1 m positional accuracy. Chlorophyll of green plant matter was detectable in the red (638–710 nm) waveband. Maps of the chlorophyll signal from both fields showed an overall agreement of 78.1% with reference maps, one constructed prior to harvest and the other at harvest time, both based on visual evaluations of the three green weed species conducted by experts. Information on weed distributions at harvest may be useful for controlling post-harvest using variable rate technology for herbicide applications. Full article

(This article belongs to the Special Issue Sensors in Agriculture and Forestry)

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16 pages, 7974 KiB

Open AccessArticle

by Guokai Shi¹, Tingfa Xu^1,2,*, Jiqiang Luo¹, Jie Guo¹

and Zishu Zhao¹

¹ School of Optoelectronics, Image Engineering & Video Technology Lab, Beijing Institute of Technology, Beijing 100081, China

² Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Beijing 100081, China

Sensors 2017, 17(10), 2382; https://doi.org/10.3390/s17102382 - 19 Oct 2017

Viewed by 3535

Abstract

Correlation Filter (CF) based trackers have demonstrated superior performance to many complex scenes in smart and autonomous systems, but similar object interference is still a challenge. When the target is occluded by a similar object, they not only have similar appearance feature but [...] Read more.

Correlation Filter (CF) based trackers have demonstrated superior performance to many complex scenes in smart and autonomous systems, but similar object interference is still a challenge. When the target is occluded by a similar object, they not only have similar appearance feature but also are in same surrounding context. Existing CF tracking models only consider the target’s appearance information and its surrounding context, and have insufficient discrimination to address the problem. We propose an approach that integrates interference-target spatial structure (ITSS) constraints into existing CF model to alleviate similar object interference. Our approach manages a dynamic graph of ITSS online, and jointly learns the target appearance model, similar object appearance model and the spatial structure between them to improve the discrimination between the target and a similar object. Experimental results on large benchmark datasets OTB-2013 and OTB-2015 show that the proposed approach achieves state-of-the-art performance. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 12931 KiB

Open AccessArticle

Modified Gray-Level Coding Method for Absolute Phase Retrieval

by Xiangcheng Chen¹, Shunping Chen², Jie Luo¹, Mengchao Ma³

, Yuwei Wang^2,*, Yajun Wang^4,* and Lei Chen⁵

¹ School of Automation, Wuhan University of Technology, Wuhan 430070, China

² Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China

³ Department of Instrument Science and Opto-Electronics Engineering, Hefei University of Technology, Hefei 230088, China

⁴ State Key Laboratory of Information Engineering in Surveying, Mapping, and Remote Sensing, Wuhan University, Wuhan 430079, China

⁵ School of Mechanical and Electrical Engineering, Wuhan University of Technology, Wuhan 430070, China

Sensors 2017, 17(10), 2383; https://doi.org/10.3390/s17102383 - 19 Oct 2017

Cited by 20 | Viewed by 4767

Abstract

Fringe projection systems have been widely applied in three-dimensional (3D) shape measurements. One of the important issues is how to retrieve the absolute phase. This paper presents a modified gray-level coding method for absolute phase retrieval. Specifically, two groups of fringe patterns are [...] Read more.

Fringe projection systems have been widely applied in three-dimensional (3D) shape measurements. One of the important issues is how to retrieve the absolute phase. This paper presents a modified gray-level coding method for absolute phase retrieval. Specifically, two groups of fringe patterns are projected onto the measured objects, including three phase-shift patterns for the wrapped phase, and three n-ary gray-level (nGL) patterns for the fringe order. Compared with the binary gray-level (bGL) method which just uses two intensity values, the nGL method can generate many more unique codewords with multiple intensity values. With assistance from the average intensity and modulation of phase-shift patterns, the intensities of nGL patterns are normalized to deal with ambient light and surface contrast. To reduce the codeword detection errors caused by camera/projector defocus, nGL patterns are designed as n-ary gray-code (nGC) patterns to ensure that at most, one code changes at each point. Experiments verify the robustness and effectiveness of the proposed method to measure isolated objects with complex surfaces. Full article

(This article belongs to the Special Issue Imaging Depth Sensors—Sensors, Algorithms and Applications)

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32 pages, 6694 KiB

Open AccessReview

Downhole Applications of Magnetic Sensors

by Chinthaka P. Gooneratne^*, Bodong Li and Timothy E. Moellendick

Drilling Technology Team, Exploration and Petroleum Engineering Center—Advanced Research Center (EXPEC-ARC), Dhahran 31311, Saudi Arabia

Sensors 2017, 17(10), 2384; https://doi.org/10.3390/s17102384 - 19 Oct 2017

Cited by 46 | Viewed by 16404

Abstract

In this paper we present a review of the application of two types of magnetic sensors—fluxgate magnetometers and nuclear magnetic resonance (NMR) sensors—in the oil/gas industry. These magnetic sensors play a critical role in drilling wells safely, accurately and efficiently into a target [...] Read more.

In this paper we present a review of the application of two types of magnetic sensors—fluxgate magnetometers and nuclear magnetic resonance (NMR) sensors—in the oil/gas industry. These magnetic sensors play a critical role in drilling wells safely, accurately and efficiently into a target reservoir zone by providing directional data of the well and acquiring information about the surrounding geological formations. Research into magnetic sensors for oil/gas drilling has not been explored by researchers to the same extent as other applications, such as biomedical, magnetic storage and automotive/aerospace applications. Therefore, this paper aims to serve as an opportunity for researchers to truly understand how magnetic sensors can be used in a downhole environment and to provide fertile ground for research and development in this area. A look ahead, discussing other magnetic sensor technologies that can potentially be used in the oil/gas industry is presented, and what is still needed in order deploy them in the field is also addressed. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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18 pages, 9914 KiB

Open AccessArticle

Photoplethysmography Signal Analysis for Optimal Region-of-Interest Determination in Video Imaging on a Built-In Smartphone under Different Conditions

by Yunyoung Nam¹

and Yun-Cheol Nam^2,*

¹ Department of Computer Science and Engineering, Soonchunhyang University, Asan 31538, Korea

² Department of Architecture, Joongbu University, Goyang 10279, Korea

Sensors 2017, 17(10), 2385; https://doi.org/10.3390/s17102385 - 19 Oct 2017

Cited by 8 | Viewed by 7815

Abstract

Smartphones and tablets are widely used in medical fields, which can improve healthcare and reduce healthcare costs. Many medical applications for smartphones and tablets have already been developed and widely used by both health professionals and patients. Specifically, video recordings of fingertips made [...] Read more.

Smartphones and tablets are widely used in medical fields, which can improve healthcare and reduce healthcare costs. Many medical applications for smartphones and tablets have already been developed and widely used by both health professionals and patients. Specifically, video recordings of fingertips made using a smartphone camera contain a pulsatile component caused by the cardiac pulse equivalent to that present in a photoplethysmographic signal. By performing peak detection on the pulsatile signal, it is possible to estimate a continuous heart rate and a respiratory rate. To estimate the heart rate and respiratory rate accurately, which pixel regions of the color bands give the most optimal signal quality should be investigated. In this paper, we investigate signal quality to determine the best signal quality by the largest amplitude values for three different smartphones under different conditions. We conducted several experiments to obtain reliable PPG signals and compared the PPG signal strength in the three color bands when the flashlight was both on and off. We also evaluated the intensity changes of PPG signals obtained from the smartphones with motion artifacts and fingertip pressure force. Furthermore, we have compared the PSNR of PPG signals of the full-size images with that of the region of interests (ROIs). Full article

(This article belongs to the Special Issue Advanced Physiological Sensing)

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13 pages, 15054 KiB

Open AccessArticle

A Research on Low Modulus Distributed Fiber Optical Sensor for Pavement Material Strain Monitoring

by Lingjian Meng, Linbing Wang^*, Yue Hou and Guannan Yan

National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083,China

Sensors 2017, 17(10), 2386; https://doi.org/10.3390/s17102386 - 19 Oct 2017

Cited by 45 | Viewed by 5652

Abstract

The accumulated irreversible deformation in pavement under repeated vehicle loadings will cause fatigue failure of asphalt concrete. It is necessary to monitor the mechanical response of pavement under load by using sensors. Previous studies have limitations in modulus accommodation between the sensor and [...] Read more.

The accumulated irreversible deformation in pavement under repeated vehicle loadings will cause fatigue failure of asphalt concrete. It is necessary to monitor the mechanical response of pavement under load by using sensors. Previous studies have limitations in modulus accommodation between the sensor and asphalt pavement, and it is difficult to achieve the distributed monitoring goal. To solve these problems, a new type of low modulus distributed optical fiber sensor (DOFS) for asphalt pavement strain monitoring is fabricated. Laboratory experiments have proved the applicability and accuracy of the newly-designed sensor. This paper presents the results of the development. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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23 pages, 11955 KiB

Open AccessArticle

Terahertz Spectroscopy for Proximal Soil Sensing: An Approach to Particle Size Analysis

by Volker Dworak^*, Benjamin Mahns, Jörn Selbeck, Robin Gebbers

and Cornelia Weltzien

Department Engineering for Crop Production, Leibniz-Institute for Agricultural Engineering and Bioeconomy (ATB), Max-Eyth-Allee 100, 14469 Potsdam, Germany

Sensors 2017, 17(10), 2387; https://doi.org/10.3390/s17102387 - 19 Oct 2017

Cited by 12 | Viewed by 5682

Abstract

Spatially resolved soil parameters are some of the most important pieces of information for precision agriculture. These parameters, especially the particle size distribution (texture), are costly to measure by conventional laboratory methods, and thus, in situ assessment has become the focus of a [...] Read more.

Spatially resolved soil parameters are some of the most important pieces of information for precision agriculture. These parameters, especially the particle size distribution (texture), are costly to measure by conventional laboratory methods, and thus, in situ assessment has become the focus of a new discipline called proximal soil sensing. Terahertz (THz) radiation is a promising method for nondestructive in situ measurements. The THz frequency range from 258 gigahertz (GHz) to 350 GHz provides a good compromise between soil penetration and the interaction of the electromagnetic waves with soil compounds. In particular, soil physical parameters influence THz measurements. This paper presents investigations of the spectral transmission signals from samples of different particle size fractions relevant for soil characterization. The sample thickness ranged from 5 to 17 mm. The transmission of THz waves was affected by the main mineral particle fractions, sand, silt and clay. The resulting signal changes systematically according to particle sizes larger than half the wavelength. It can be concluded that THz spectroscopic measurements provide information about soil texture and penetrate samples with thicknesses in the cm range. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 6592 KiB

Open AccessArticle

Time Multiplexed Active Neural Probe with 1356 Parallel Recording Sites

by Bogdan C. Raducanu^1,2,*, Refet F. Yazicioglu¹, Carolina M. Lopez¹, Marco Ballini¹

, Jan Putzeys¹, Shiwei Wang¹

, Alexandru Andrei¹, Veronique Rochus¹, Marleen Welkenhuysen¹, Nick van Helleputte¹, Silke Musa¹, Robert Puers^1,2, Fabian Kloosterman^3,4,5, Chris van Hoof^1,2, Richárd Fiáth^6,7

, István Ulbert^6,7

and Srinjoy Mitra⁸

¹ Imec, 3001 Leuven, Belgium

² Electrical Engineering Department-ESAT, KU Leuven, 3001 Leuven, Belgium

³ Faculty of Psychology and Educational Sciences, KU Leuven, 3000 Leuven, Belgium

⁴ Neuro-electronics Research Flanders, 3001 Leuven, Belgium

⁵ VIB, 3000 Leuven, Belgium

⁶ Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary

⁷ Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, H-1083 Budapest, Hungary

⁸ School of Engineering, University of Glasgow, Glasgow G10 8QQ, UK

Sensors 2017, 17(10), 2388; https://doi.org/10.3390/s17102388 - 19 Oct 2017

Cited by 134 | Viewed by 13453

Abstract

We present a high electrode density and high channel count CMOS (complementary metal-oxide-semiconductor) active neural probe containing 1344 neuron sized recording pixels (20 µm × 20 µm) and 12 reference pixels (20 µm × 80 µm), densely packed on a 50 µm thick, [...] Read more.

We present a high electrode density and high channel count CMOS (complementary metal-oxide-semiconductor) active neural probe containing 1344 neuron sized recording pixels (20 µm × 20 µm) and 12 reference pixels (20 µm × 80 µm), densely packed on a 50 µm thick, 100 µm wide, and 8 mm long shank. The active electrodes or pixels consist of dedicated in-situ circuits for signal source amplification, which are directly located under each electrode. The probe supports the simultaneous recording of all 1356 electrodes with sufficient signal to noise ratio for typical neuroscience applications. For enhanced performance, further noise reduction can be achieved while using half of the electrodes (678). Both of these numbers considerably surpass the state-of-the art active neural probes in both electrode count and number of recording channels. The measured input referred noise in the action potential band is 12.4 µVrms, while using 678 electrodes, with just 3 µW power dissipation per pixel and 45 µW per read-out channel (including data transmission). Full article

(This article belongs to the Section Biosensors)

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14 pages, 7221 KiB

Open AccessArticle

Optimal Deployment of Sensor Nodes Based on Performance Surface of Underwater Acoustic Communication

by Sunhyo Kim

and Jee Woong Choi^*

Department of Marine Science and Convergence Engineering, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Korea

Sensors 2017, 17(10), 2389; https://doi.org/10.3390/s17102389 - 20 Oct 2017

Cited by 13 | Viewed by 5468

Abstract

The underwater acoustic sensor network (UWASN) is a system that exchanges data between numerous sensor nodes deployed in the sea. The UWASN uses an underwater acoustic communication technique to exchange data. Therefore, it is important to design a robust system that will function [...] Read more.

The underwater acoustic sensor network (UWASN) is a system that exchanges data between numerous sensor nodes deployed in the sea. The UWASN uses an underwater acoustic communication technique to exchange data. Therefore, it is important to design a robust system that will function even in severely fluctuating underwater communication conditions, along with variations in the ocean environment. In this paper, a new algorithm to find the optimal deployment positions of underwater sensor nodes is proposed. The algorithm uses the communication performance surface, which is a map showing the underwater acoustic communication performance of a targeted area. A virtual force-particle swarm optimization algorithm is then used as an optimization technique to find the optimal deployment positions of the sensor nodes, using the performance surface information to estimate the communication radii of the sensor nodes in each generation. The algorithm is evaluated by comparing simulation results between two different seasons (summer and winter) for an area located off the eastern coast of Korea as the selected targeted area. Full article

(This article belongs to the Special Issue Advances and Challenges in Underwater Sensor Networks)

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11 pages, 5478 KiB

Open AccessArticle

Monitoring Bridge Dynamic Responses Using Fiber Bragg Grating Tiltmeters

by Feng Xiao¹

, Gang S. Chen^2,* and J. Leroy Hulsey¹

¹ Department of Civil and Environmental Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA

² College of Information Technology and Engineering, Marshall University, Huntington, WV 25755, USA

Sensors 2017, 17(10), 2390; https://doi.org/10.3390/s17102390 - 20 Oct 2017

Cited by 38 | Viewed by 8137

Abstract

In bridge health monitoring, tiltmeters have been used for measuring rotation and curvature; however, their application in dynamic parameter identification has been lacking. This study installed fiber Bragg grating (FBG) tiltmeters on the bearings of a bridge and monitored the dynamic rotational angle. [...] Read more.

In bridge health monitoring, tiltmeters have been used for measuring rotation and curvature; however, their application in dynamic parameter identification has been lacking. This study installed fiber Bragg grating (FBG) tiltmeters on the bearings of a bridge and monitored the dynamic rotational angle. The dynamic features, including natural frequencies and mode shapes, have been identified successfully. The innovation presented in this paper is the first-time use of FBG tiltmeter readings to identify the natural frequencies of a long-span steel girder bridge. The identified results have been verified using a bridge finite element model. This paper introduces a new method for the dynamic monitoring of a bridge using FBG tiltmeters. Limitations and future research directions are also discussed in the conclusion. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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15 pages, 7280 KiB

Open AccessArticle

An Improved Indoor Positioning System Using RGB-D Cameras and Wireless Networks for Use in Complex Environments

by Jaime Duque Domingo^1,*

, Carlos Cerrada¹

, Enrique Valero²

and Jose A. Cerrada¹

¹ Departamento de Ingeniería de Software y Sistemas Informáticos, ETSI Informática, UNED, C/Juan del Rosal, 16, 28040 Madrid, Spain

² School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, UK

Sensors 2017, 17(10), 2391; https://doi.org/10.3390/s17102391 - 20 Oct 2017

Cited by 25 | Viewed by 13922

Abstract

This work presents an Indoor Positioning System to estimate the location of people navigating in complex indoor environments. The developed technique combines WiFi Positioning Systems and depth maps, delivering promising results in complex inhabited environments, consisting of various connected rooms, where people [...] Read more.

This work presents an Indoor Positioning System to estimate the location of people navigating in complex indoor environments. The developed technique combines WiFi Positioning Systems and depth maps, delivering promising results in complex inhabited environments, consisting of various connected rooms, where people are freely moving. This is a non-intrusive system in which personal information about subjects is not needed and, although RGB-D cameras are installed in the sensing area, users are only required to carry their smart-phones. In this article, the methods developed to combine the above-mentioned technologies and the experiments performed to test the system are detailed. The obtained results show a significant improvement in terms of accuracy and performance with respect to previous WiFi-based solutions as well as an extension in the range of operation. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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7 pages, 3848 KiB

Open AccessArticle

Fabrication of Ordered SnO₂ Nanostructures with Enhanced Humidity Sensing Performance

by Wei Li^1,2,*, Juyan Liu¹, Chao Ding¹, Gang Bai¹, Jie Xu¹, Qingying Ren¹ and Jinze Li¹

¹ College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

² State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China

Sensors 2017, 17(10), 2392; https://doi.org/10.3390/s17102392 - 20 Oct 2017

Cited by 39 | Viewed by 4922

Abstract

Ordered SnO₂ nanostructures were prepared as humidity sensors by nanosphere lithography with the magnetron sputtering technique. The X-ray diffraction patterns of SnO₂ nanostructures show that all intense diffraction peaks correspond to the crystallographic planes of SnO₂. The Atomic Force [...] Read more.

Ordered SnO₂ nanostructures were prepared as humidity sensors by nanosphere lithography with the magnetron sputtering technique. The X-ray diffraction patterns of SnO₂ nanostructures show that all intense diffraction peaks correspond to the crystallographic planes of SnO₂. The Atomic Force Microscope (AFM) mage shows that these SnO₂ nanostructures exhibited a classic honeycomb structure. The resistance of this sensor was measured to show that the resistance of the sensor decreases with an increase from lower relative humidity (RH) to higher RH. Additionally, the longest response/recovery time was 32 s/42 s for 11–96% RH. The hysteresis for the SnO₂ nanostructure sensor was <5%. Full article

(This article belongs to the Section Chemical Sensors)

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10 pages, 2830 KiB

Open AccessArticle

Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis

by Luis A. Herrera-Piad¹, Joseph W. Haus²

, Daniel Jauregui-Vazquez^1,*, Juan M. Sierra-Hernandez¹, Julian M. Estudillo-Ayala¹

, Yanelis Lopez-Dieguez¹ and Roberto Rojas-Laguna¹

¹ Departamento de Ingeniería Electrónica, División de Ingenierías, Universidad de Guanajuato, Carretera, Salamanca-Valle de Santiago km 3.5 + 1.8, Comunidad de Palo Blanco, Salamanca Gto. C.P. 36885, Mexico

² Department of Electro-Optics and Photonics, University of Dayton, Dayton, OH 45469, USA

Sensors 2017, 17(10), 2393; https://doi.org/10.3390/s17102393 - 20 Oct 2017

Cited by 10 | Viewed by 6299

Abstract

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data [...] Read more.

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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17 pages, 7626 KiB

Open AccessArticle

Crack Monitoring Method for an FRP-Strengthened Steel Structure Based on an Antenna Sensor

by Zhiping Liu¹

, Kai Chen^1,*

, Zongchen Li² and Xiaoli Jiang²

¹ Laboratory of Intelligent Manufacture and Control, Wuhan University of Technology, Wuhan 430063, China

² Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, 2628 Delft CD, The Netherlands

Sensors 2017, 17(10), 2394; https://doi.org/10.3390/s17102394 - 20 Oct 2017

Cited by 28 | Viewed by 7533

Abstract

Fiber-reinforced polymer (FRP) has been increasingly applied to steel structures for structural strengthening or crack repair, given its high strength-to-weight ratio and high stiffness-to-weight ratio. Cracks in steel structures are the dominant hidden threats to structural safety. However, it is difficult to monitor [...] Read more.

Fiber-reinforced polymer (FRP) has been increasingly applied to steel structures for structural strengthening or crack repair, given its high strength-to-weight ratio and high stiffness-to-weight ratio. Cracks in steel structures are the dominant hidden threats to structural safety. However, it is difficult to monitor structural cracks under FRP coverage and there is little related research. In this paper, a crack monitoring method for an FRP-strengthened steel structure deploying a microstrip antenna sensor is presented. A theoretical model of the dual-substrate antenna sensor with FRP is established and the sensitivity of crack monitoring is studied. The effects of the weak conductivity of carbon fiber reinforced polymers (CFRPs) on the performance of crack monitoring are analyzed via contrast experiments. The effects of FRP thickness on the performance of the antenna sensor are studied. The influence of structural strain on crack detection coupling is studied through strain–crack coupling experiments. The results indicate that the antenna sensor can detect cracks in steel structures covered by FRP (including CFRP). FRP thickness affects the antenna sensor’s performance significantly, while the effects of strain can be ignored. The results provide a new approach for crack monitoring of FRP-strengthened steel structures with extensive application prospects. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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8 pages, 3409 KiB

Open AccessArticle

Real-Time Monitoring of Water Content in Sandy Soil Using Shear Mode Piezoceramic Transducers and Active Sensing—A Feasibility Study

by Qingzhao Kong^1,†

, Hongli Chen^2,†, Yi-lung Mo³ and Gangbing Song^1,*

¹ Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA

² College of Mechanical Engineering and Automation, Zhengjiang SCI-TECH University, Hangzhou 310018, China

³ Department of Civil and Environmental Engineering, University of Houston, Houston, TX 77204, USA

^† These authors contributes equally to this work.

Sensors 2017, 17(10), 2395; https://doi.org/10.3390/s17102395 - 20 Oct 2017

Cited by 47 | Viewed by 4680

Abstract

A quantitative understanding of soil water content or soil water status is of great importance to many applications, such as landslide monitoring, rockfill dam health monitoring, precision agriculture, etc. In this paper, a feasibility study was conducted to monitor the soil water content [...] Read more.

A quantitative understanding of soil water content or soil water status is of great importance to many applications, such as landslide monitoring, rockfill dam health monitoring, precision agriculture, etc. In this paper, a feasibility study was conducted to monitor the soil water content in real time using permanent embedded piezoceramic-based transducers called smart aggregates (SAs). An active sensing approach using a customized swept acoustic wave with a frequency range between 100 Hz and 300 kHz was used to study the wave attenuation in the soil in correlation to soil moisture levels. Two sandy soil specimens, each embedded with a pair of SAs, were made in the laboratory, and the water percentage of the soil specimens was incrementally decreased from 15% to 3% during the tests. Due to the change of the soil water status, the damping property of the soil correspondingly changes. The change of the damping property results in the variation of the acoustic wave attenuation ratios. A wavelet packet-based energy index was adopted to compute the energy of the signal captured by the SA sensor. Experimental results show a parabolic growth curve of the received signal energy vs. the water percentage of the soil. The feasibility, sensitivity, and reliability of the proposed method for in-situ monitoring of soil water status were discussed. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 4327 KiB

Open AccessArticle

Silicon Nanocrystals with pH-Sensitive Tunable Light Emission from Violet to Blue-Green

by Jing Wang^1,2,3,*, Junhong Guo^1,2 and Jing Chen^1,2,3

¹ Department of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

² National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China

³ Jiangsu Provincial Engineering Laboratory for RF Integration and Micropackaging, Xinmofan Street 66, Nanjing 210003, China

Sensors 2017, 17(10), 2396; https://doi.org/10.3390/s17102396 - 20 Oct 2017

Cited by 9 | Viewed by 5267

Abstract

We fabricated a silicon nanocrystal (NC) suspension with visible, continuous, tunable light emission with pH sensitivity from violet to blue-green. Transmission electron microscopy (TEM) images and X-ray diffraction (XRD) pattern analysis exhibit the highly crystalline nanoparticles of silicon. Photoluminescence (PL) spectra and photoluminescence [...] Read more.

We fabricated a silicon nanocrystal (NC) suspension with visible, continuous, tunable light emission with pH sensitivity from violet to blue-green. Transmission electron microscopy (TEM) images and X-ray diffraction (XRD) pattern analysis exhibit the highly crystalline nanoparticles of silicon. Photoluminescence (PL) spectra and photoluminescence excitation (PLE) spectra at different pH values, such as 1, 3, 5, 7, 9, and 11, reveal the origins of light emission from the silicon NC suspension, which includes both the quantum confinement effect and surface bonding. The quantum confinement effect dominates the PL origins of silicon NCs, especially determining the tunability and the emission range of PL, while the surface bonding regulates the maximum peak center, full width at half maximum (FWHM), and offsets of PL peaks in response to the changing pH value. The peak fitting of PLE curves reveals one of the divided PLE peaks shifts towards a shorter wavelength when the pH value increases, which implies correspondence with the surface bonding between silicon NCs and hydrogen atoms or hydroxyl groups. The consequent detailed analysis of the PL spectra indicates that the surface bonding results in the transforming of the PL curves towards longer wavelengths with the increasing pH values, which is defined as the pH sensitivity of PL. These results suggest that the present silicon NCs with pH-sensitive tunable light emission could find promising potential applications as optical sources, bio-sensors, etc. Full article

(This article belongs to the Special Issue Solid-State pH Sensors)

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19 pages, 1470 KiB

Open AccessArticle

The Light Node Communication Framework: A New Way to Communicate Inside Smart Homes

by Valère Plantevin^*

, Abdenour Bouzouane and Sebastien Gaboury

Département d’Informatique et de Mathématiques, Université du Québec à Chicoutimi, Saguenay, QC G7H 2B1, Canada

Sensors 2017, 17(10), 2397; https://doi.org/10.3390/s17102397 - 20 Oct 2017

Cited by 9 | Viewed by 4837

Abstract

The Internet of things has profoundly changed the way we imagine information science and architecture, and smart homes are an important part of this domain. Created a decade ago, the few existing prototypes use technologies of the day, forcing designers to create centralized [...] Read more.

The Internet of things has profoundly changed the way we imagine information science and architecture, and smart homes are an important part of this domain. Created a decade ago, the few existing prototypes use technologies of the day, forcing designers to create centralized and costly architectures that raise some issues concerning reliability, scalability, and ease of access which cannot be tolerated in the context of assistance. In this paper, we briefly introduce a new kind of architecture where the focus is placed on distribution. More specifically, we respond to the first issue we encountered by proposing a lightweight and portable messaging protocol. After running several tests, we observed a maximized bandwidth, whereby no packets were lost and good encryption was obtained. These results tend to prove that our innovation may be employed in a real context of distribution with small entities. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 3480 KiB

Open AccessArticle

An Objective Balance Error Scoring System for Sideline Concussion Evaluation Using Duplex Kinect Sensors

by Mengqi Zhu, Zhonghua Huang, Chao Ma and Yinlin Li^*

School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China

Sensors 2017, 17(10), 2398; https://doi.org/10.3390/s17102398 - 20 Oct 2017

Cited by 9 | Viewed by 8205

Abstract

Sports-related concussion is a common sports injury that might induce potential long-term consequences without early diagnosis and intervention in the field. However, there are few options of such sensor systems available. The aim of the study is to propose and validate an automated [...] Read more.

Sports-related concussion is a common sports injury that might induce potential long-term consequences without early diagnosis and intervention in the field. However, there are few options of such sensor systems available. The aim of the study is to propose and validate an automated concussion administration and scoring approach, which is objective, affordable and capable of detecting all balance errors required by the balance error scoring system (BESS) protocol in the field condition. Our approach is first to capture human body skeleton positions using two Microsoft Kinect sensors in the proposed configuration and merge the data by a custom-made algorithm to remove the self-occlusion of limbs. The standing balance errors according to BESS protocol were further measured and accessed automatically by the proposed algorithm. Simultaneously, the BESS test was filmed for scoring by an experienced rater. Two results were compared using Pearson coefficient r, obtaining an excellent consistency (r = 0.93, p < 0.05). In addition, BESS test–retest was performed after seven days and compared using intraclass correlation coefficients (ICC), showing a good test–retest reliability (ICC = 0.81, p < 0.01). The proposed approach could be an alternative of objective tools to assess postural stability for sideline sports concussion diagnosis. Full article

(This article belongs to the Special Issue Optical Methods in Sensing and Imaging for Medical and Biological Applications)

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18 pages, 7041 KiB

Open AccessArticle

Flexible Sensors for Pressure Therapy: Effect of Substrate Curvature and Stiffness on Sensor Performance

by Iryna Khodasevych, Suresh Parmar and Olga Troynikov^*

School of Fashion and Textiles, Royal Melbourne Institute of Technology, Melbourne 3056, Australia

Sensors 2017, 17(10), 2399; https://doi.org/10.3390/s17102399 - 20 Oct 2017

Cited by 33 | Viewed by 5963

Abstract

Flexible pressure sensors are increasingly being used in medical and non-medical applications, and particularly in innovative health monitoring. Their efficacy in medical applications such as compression therapy depends on the accuracy and repeatability of their output, which in turn depend on factors such [...] Read more.

Flexible pressure sensors are increasingly being used in medical and non-medical applications, and particularly in innovative health monitoring. Their efficacy in medical applications such as compression therapy depends on the accuracy and repeatability of their output, which in turn depend on factors such as sensor type, shape, pressure range, and conformability of the sensor to the body surface. Numerous researchers have examined the effects of sensor type and shape, but little information is available on the effect of human body parameters such as support surfaces’ curvature and the stiffness of soft tissues on pressure sensing performance. We investigated the effects of body parameters on the performance of pressure sensors using a custom-made human-leg-like test setup. Pressure sensing parameters such as accuracy, drift and repeatability were determined in both static (eight hours continuous pressure) and dynamic (10 cycles of pressure application of 30 s duration) testing conditions. The testing was performed with a focus on compression therapy application for venous leg ulcer treatments, and was conducted in a low-pressure range of 20–70 mmHg. Commercially available sensors manufactured by Peratech and Sensitronics were used under various loading conditions to determine the influence of stiffness and curvature. Flat rigid, flat soft silicone and three cylindrical silicone surfaces of radii of curvature of 3.5 cm, 5.5 cm and 6.5 cm were used as substrates under the sensors. The Peratech sensor averaged 94% accuracy for both static and dynamic measurements on all substrates; the Sensitronics sensor averaged 88% accuracy. The Peratech sensor displayed moderate variations and the Sensitronics sensor large variations in output pressure readings depending on the underlying test surface, both of which were reduced markedly by individual pressure calibration for surface type. Sensor choice and need for calibration to surface type are important considerations for their application in healthcare monitoring. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 3222 KiB

Open AccessArticle

The Multi-Parameter Wireless Sensing System (MPwise): Its Description and Application to Earthquake Risk Mitigation

by Tobias Boxberger^1,*, Kevin Fleming¹, Massimiliano Pittore¹, Stefano Parolai^1,2, Marco Pilz¹ and Stefan Mikulla¹

¹ Helmholtz Center Potsdam—GFZ German Research Centre for Geosciences, Helmholtzstrasse 7, 14467 Potsdam, Germany

² Istituto Nazionale di Oceanografia e di Geofisica Sperimentale—OGS, Borgo Grotta Gigante 42/C—34010—Sgonico (TS ), Italy

Sensors 2017, 17(10), 2400; https://doi.org/10.3390/s17102400 - 20 Oct 2017

Cited by 21 | Viewed by 4881

Abstract

The Multi-Parameter Wireless Sensing (MPwise) system is an innovative instrumental design that allows different sensor types to be combined with relatively high-performance computing and communications components. These units, which incorporate off-the-shelf components, can undertake complex information integration and processing tasks at the individual [...] Read more.

The Multi-Parameter Wireless Sensing (MPwise) system is an innovative instrumental design that allows different sensor types to be combined with relatively high-performance computing and communications components. These units, which incorporate off-the-shelf components, can undertake complex information integration and processing tasks at the individual unit or node level (when used in a network), allowing the establishment of networks that are linked by advanced, robust and rapid communications routing and network topologies. The system (and its predecessors) was originally designed for earthquake risk mitigation, including earthquake early warning (EEW), rapid response actions, structural health monitoring, and site-effect characterization. For EEW, MPwise units are capable of on-site, decentralized, independent analysis of the recorded ground motion and based on this, may issue an appropriate warning, either by the unit itself or transmitted throughout a network by dedicated alarming procedures. The multi-sensor capabilities of the system allow it to be instrumented with standard strong- and weak-motion sensors, broadband sensors, MEMS (namely accelerometers), cameras, temperature and humidity sensors, and GNSS receivers. In this work, the MPwise hardware, software and communications schema are described, as well as an overview of its possible applications. While focusing on earthquake risk mitigation actions, the aim in the future is to expand its capabilities towards a more multi-hazard and risk mitigation role. Overall, MPwise offers considerable flexibility and has great potential in contributing to natural hazard risk mitigation. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 3996 KiB

Open AccessArticle

Lab-on-Chip, Surface-Enhanced Raman Analysis by Aerosol Jet Printing and Roll-to-Roll Hot Embossing

by Anne Habermehl^1,*

, Noah Strobel^1,2, Ralph Eckstein^1,2, Nico Bolse¹

, Adrian Mertens¹, Gerardo Hernandez-Sosa^1,2, Carsten Eschenbaum^1,2,3 and Uli Lemmer^1,2,3

¹ Light Technology Institute, Karlsruhe Institute of Technology (KIT), Engesserstraße 13, 76131 Karlsruhe, Germany

² InnovationLab GmbH, Speyerer Straße 4, 69115 Heidelberg, Germany

³ Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Sensors 2017, 17(10), 2401; https://doi.org/10.3390/s17102401 - 20 Oct 2017

Cited by 19 | Viewed by 7603

Abstract

Surface-enhanced Raman spectroscopy (SERS) combines the high speciﬁcity of Raman scattering with high sensitivity due to an enhancement of the electromagnetic ﬁeld by metallic nanostructures. However, the tyical fabrication methods of SERS substrates suffer from low throughput and therefore high costs. Furthermore, point-of-care [...] Read more.

Surface-enhanced Raman spectroscopy (SERS) combines the high speciﬁcity of Raman scattering with high sensitivity due to an enhancement of the electromagnetic ﬁeld by metallic nanostructures. However, the tyical fabrication methods of SERS substrates suffer from low throughput and therefore high costs. Furthermore, point-of-care applications require the investigation of liquid solutions and thus the integration of the SERS substrate in a microfluidic chip. We present a roll-to-roll fabrication approach for microfluidics with integrated, highly efficient, surface-enhanced Raman scattering structures. Microfluidic channels are formed using roll-to-roll hot embossing in polystyrene foil. Aerosol jet printing of a gold nanoparticle ink is utilized to manufacture highly efficient, homogeneous, and reproducible SERS structures. The modified channels are sealed with a solvent-free, roll-to-roll, thermal bonding process. In continuous flow measurements, these chips overcome time-consuming incubation protocols and the poor reproducibility of SERS experiments often caused by inhomogeneous drying of the analyte. In the present study, we explore the influence of the printing process on the homogeneity and the enhancement of the SERS structures. The feasibility of aerosol-jet-modified microfluidic channels for highly sensitive SERS detection is demonstrated by using solutions with different concentrations of Rhodamine 6G and adenosine. The printed areas provide homogeneous enhancement factors of ~4 × 10⁶. Our work shows a way towards the low-cost production of tailor-made, SERS-enabled, label-free, lab-on- chip systems for bioanalysis. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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20 pages, 2136 KiB

Open AccessArticle

Transfer-Efficient Face Routing Using the Planar Graphs of Neighbors in High Density WSNs

by Eun-Seok Cho^1,†,‡

, Yongbin Yim²

and Sang-Ha Kim^2,*

¹ Information Technology Management Division, Agency for Defense Development, Daejeon 305-150, Korea

² Department of Computer Engineering, Chungnam National University, Daejeon 301-747, Korea

^† Current address: P.O.Box 35, Yuseong, Daejeon 34186, Korea

^‡ These authors contributed equally to this work.

Sensors 2017, 17(10), 2402; https://doi.org/10.3390/s17102402 - 20 Oct 2017

Cited by 3 | Viewed by 3658

Abstract

Face routing has been adopted in wireless sensor networks (WSNs) where topological changes occur frequently or maintaining full network information is difficult. For message forwarding in networks, a planar graph is used to prevent looping, and because long edges are removed by planarization [...] Read more.

Face routing has been adopted in wireless sensor networks (WSNs) where topological changes occur frequently or maintaining full network information is difficult. For message forwarding in networks, a planar graph is used to prevent looping, and because long edges are removed by planarization and the resulting planar graph is composed of short edges, and messages are forwarded along multiple nodes connected by them even though they can be forwarded directly. To solve this, face routing using information on all nodes within 2-hop range was adopted to forward messages directly to the farthest node within radio range. However, as the density of the nodes increases, network performance plunges because message transfer nodes receive and process increased node information. To deal with this problem, we propose a new face routing using the planar graphs of neighboring nodes to improve transfer efficiency. It forwards a message directly to the farthest neighbor and reduces loads and processing time by distributing network graph construction and planarization to the neighbors. It also decreases the amount of location information to be transmitted by sending information on the planar graph nodes rather than on all neighboring nodes. Simulation results show that it significantly improves transfer efficiency. Full article

(This article belongs to the Section Sensor Networks)

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8 pages, 1474 KiB

Open AccessArticle

Investigation of Temperature Sensitivity of a Polymer-Overlaid Microfiber Mach-Zehnder Interferometer

by Young-Geun Han

Department of Physics and the Research Institute for Natural Sciences, Hanyang University, Seoul 133–791, Korea

Sensors 2017, 17(10), 2403; https://doi.org/10.3390/s17102403 - 21 Oct 2017

Cited by 8 | Viewed by 4966

Abstract

The temperature sensitivity of the free spectral range (FSR) for a polymer-overlaid microfiber Mach-Zehnder interferometer (MZI) is investigated both theoretically and experimentally. The waist diameter of the optical microfiber can be controlled to alter the thermal expansion and optic properties of the polymer-coated [...] Read more.

The temperature sensitivity of the free spectral range (FSR) for a polymer-overlaid microfiber Mach-Zehnder interferometer (MZI) is investigated both theoretically and experimentally. The waist diameter of the optical microfiber can be controlled to alter the thermal expansion and optic properties of the polymer-coated MZI. Inserting an optical microfiber with a strong evanescent field into the MZI, a low index polymer with high thermal characteristics is deposited on the surface of the microfibers to realize a polymer-overlaid microfiber MZI. It was found that the thermal expansion factor in the proposed MZI plays an important role in the temperature sensitivity of the FSR. The temperature sensitivity of the polymer-overlaid microfiber MZI is improved, which is measured to be −8.29 nm/°C at 25 °C. The optical transmission spectrum of the polymer-overlaid microfiber MZI is converted to the spatial frequency spectrum via fast Fourier transform. The temperature sensitivity of the spatial frequency in the proposed polymer-overlaid MZI is estimated to be 18.31 pm⁻¹ °C⁻¹, which is 17 times higher than that of the microfiber MZI without polymer coating (1.04 pm⁻¹ °C⁻¹). Full article

(This article belongs to the Special Issue Optical Sensors based on Micro/Nanofibres)

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15 pages, 1914 KiB

Open AccessArticle

Estimation of the Driving Style Based on the Users’ Activity and Environment Influence

by Mikhail Sysoev, Andrej Kos, Jože Guna^*

and Matevž Pogačnik

Laboratory for Telecommunications, Faculty of Electrical Engineering, University of Ljubljana, Tržaška cesta 25, Ljubljana 1000, Slovenia

Sensors 2017, 17(10), 2404; https://doi.org/10.3390/s17102404 - 21 Oct 2017

Cited by 28 | Viewed by 5067

Abstract

New models and methods have been designed to predict the influence of the user’s environment and activity information to the driving style in standard automotive environments. For these purposes, an experiment was conducted providing two types of analysis: (i) the evaluation of a [...] Read more.

New models and methods have been designed to predict the influence of the user’s environment and activity information to the driving style in standard automotive environments. For these purposes, an experiment was conducted providing two types of analysis: (i) the evaluation of a self-assessment of the driving style; (ii) the prediction of aggressive driving style based on drivers’ activity and environment parameters. Sixty seven h of driving data from 10 drivers were collected for analysis in this study. The new parameters used in the experiment are the car door opening and closing manner, which were applied to improve the prediction accuracy. An Android application called Sensoric was developed to collect low-level smartphone data about the users’ activity. The driving style was predicted from the user’s environment and activity data collected before driving. The prediction was tested against the actual driving style, calculated from objective driving data. The prediction has shown encouraging results, with precision values ranging from 0.727 up to 0.909 for aggressive driving recognition rate. The obtained results lend support to the hypothesis that user’s environment and activity data could be used for the prediction of the aggressive driving style in advance, before the driving starts. Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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33 pages, 1384 KiB

Open AccessArticle

Reasoning and Knowledge Acquisition Framework for 5G Network Analytics

by Marco Antonio Sotelo Monge^†

, Jorge Maestre Vidal^†

and Luis Javier García Villalba^*,†

¹ Group of Analysis, Security and Systems (GASS), Department of Software Engineering and Artificial Intelligence (DISIA), Faculty of Computer Science and Engineering, Office 431, Universidad Complutense de Madrid (UCM), Calle Profesor José García Santesmases 9, Ciudad Universitaria, 28040 Madrid, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2405; https://doi.org/10.3390/s17102405 - 21 Oct 2017

Cited by 12 | Viewed by 6220

Abstract

Autonomic self-management is a key challenge for next-generation networks. This paper proposes an automated analysis framework to infer knowledge in 5G networks with the aim to understand the network status and to predict potential situations that might disrupt the network operability. The framework [...] Read more.

Autonomic self-management is a key challenge for next-generation networks. This paper proposes an automated analysis framework to infer knowledge in 5G networks with the aim to understand the network status and to predict potential situations that might disrupt the network operability. The framework is based on the Endsley situational awareness model, and integrates automated capabilities for metrics discovery, pattern recognition, prediction techniques and rule-based reasoning to infer anomalous situations in the current operational context. Those situations should then be mitigated, either proactive or reactively, by a more complex decision-making process. The framework is driven by a use case methodology, where the network administrator is able to customize the knowledge inference rules and operational parameters. The proposal has also been instantiated to prove its adaptability to a real use case. To this end, a reference network traffic dataset was used to identify suspicious patterns and to predict the behavior of the monitored data volume. The preliminary results suggest a good level of accuracy on the inference of anomalous traffic volumes based on a simple configuration. Full article

(This article belongs to the Special Issue Advances on Resources Management for Multi-Platform Infrastructures)

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14 pages, 1849 KiB

Open AccessArticle

A Wearable Magneto-Inertial System for Gait Analysis (H-Gait): Validation on Normal Weight and Overweight/Obese Young Healthy Adults

by Valentina Agostini^1,*

, Laura Gastaldi²

, Valeria Rosso², Marco Knaflitz¹ and Shigeru Tadano³

¹ Department of Electronics and Telecommunications, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy

² Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Italy, Corso Duca degli Abruzzi 24, 10129 Torino, Italy

³ Division of Human Mechanical Systems and Design, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan

Sensors 2017, 17(10), 2406; https://doi.org/10.3390/s17102406 - 21 Oct 2017

Cited by 50 | Viewed by 7752

Abstract

Background: Wearable magneto-inertial sensors are being increasingly used to obtain human motion measurements out of the lab, although their performance in applications requiring high accuracy, such as gait analysis, are still a subject of debate. The aim of this work was to [...] Read more.

Background: Wearable magneto-inertial sensors are being increasingly used to obtain human motion measurements out of the lab, although their performance in applications requiring high accuracy, such as gait analysis, are still a subject of debate. The aim of this work was to validate a gait analysis system (H-Gait) based on magneto-inertial sensors, both in normal weight (NW) and overweight/obese (OW) subjects. The validation is performed against a reference multichannel recording system (STEP32), providing direct measurements of gait timings (through foot-switches) and joint angles in the sagittal plane (through electrogoniometers). Methods: Twenty-two young male subjects were recruited for the study (12 NW, 10 OW). After positioning body-fixed sensors of both systems, each subject was asked to walk, at a self-selected speed, over a 14-m straight path for 12 trials. Gait signals were recorded, at the same time, with the two systems. Spatio-temporal parameters, ankle, knee, and hip joint kinematics were extracted analyzing an average of 89 ± 13 gait cycles from each lower limb. Intraclass correlation coefficient and Bland-Altmann plots were used to compare H-Gait and STEP32 measurements. Changes in gait parameters and joint kinematics of OW with respect NW were also evaluated. Results: The two systems were highly consistent for cadence, while a lower agreement was found for the other spatio-temporal parameters. Ankle and knee joint kinematics is overall comparable. Joint ROMs values were slightly lower for H-Gait with respect to STEP32 for the ankle (by 1.9° for NW, and 1.6° for OW) and for the knee (by 4.1° for NW, and 1.8° for OW). More evident differences were found for hip joint, with ROMs values higher for H-Gait (by 6.8° for NW, and 9.5° for OW). NW and OW showed significant differences considering STEP32 (p = 0.0004), but not H-Gait (p = 0.06). In particular, overweight/obese subjects showed a higher cadence (55.0 vs. 52.3 strides/min) and a lower hip ROM (23.0° vs. 27.3°) than normal weight subjects. Conclusions: The two systems can be considered interchangeable for what concerns joint kinematics, except for the hip, where discrepancies were evidenced. Differences between normal and overweight/obese subjects were statistically significant using STEP32. The same tendency was observed using H-Gait. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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12 pages, 2666 KiB

Open AccessArticle

Nitrogen-Rich Polyacrylonitrile-Based Graphitic Carbons for Hydrogen Peroxide Sensing

by Brandon Pollack^1,†, Sunshine Holmberg^1,†, Derosh George¹

, Ich Tran², Marc Madou¹ and Maziar Ghazinejad^1,3,*

¹ Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA 92697, USA

² Irvine Materials Research Institute (IMRI), University of California, Irvine, CA 92697, USA

³ Department of Mechanical Engineering, California State University, Fresno, CA 93740, USA

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2407; https://doi.org/10.3390/s17102407 - 21 Oct 2017

Cited by 28 | Viewed by 7203

Abstract

Catalytic substrate, which is devoid of expensive noble metals and enzymes for hydrogen peroxide (H₂O₂), reduction reactions can be obtained via nitrogen doping of graphite. Here, we report a facile fabrication method for obtaining such nitrogen doped graphitized carbon [...] Read more.

Catalytic substrate, which is devoid of expensive noble metals and enzymes for hydrogen peroxide (H₂O₂), reduction reactions can be obtained via nitrogen doping of graphite. Here, we report a facile fabrication method for obtaining such nitrogen doped graphitized carbon using polyacrylonitrile (PAN) mats and its use in H₂O₂ sensing. A high degree of graphitization was obtained with a mechanical treatment of the PAN fibers embedded with carbon nanotubes (CNT) prior to the pyrolysis step. The electrochemical testing showed a limit of detection (LOD) 0.609 µM and sensitivity of 2.54 µA cm⁻² mM⁻¹. The promising sensing performance of the developed carbon electrodes can be attributed to the presence of high content of pyridinic and graphitic nitrogens in the pyrolytic carbons, as confirmed by X-ray photoelectron spectroscopy. The reported results suggest that, despite their simple fabrication, the hydrogen peroxide sensors developed from pyrolytic carbon nanofibers are comparable with their sophisticated nitrogen-doped graphene counterparts. Full article

(This article belongs to the Special Issue Advanced Sensors Based on Carbon Electrodes)

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23 pages, 1851 KiB

Open AccessArticle

Command Disaggregation Attack and Mitigation in Industrial Internet of Things

by Peng Xun²

, Pei-Dong Zhu^1,*, Yi-Fan Hu², Peng-Shuai Cui² and Yan Zhang³

¹ Department of Electronic Information and Electrical Engineering, Changsha University, Changsha 410022, China

² College of Computer, National University of Defense Technology, Changsha 410073, China

³ Department of Informatics, University of Oslo, Oslo 0316, Norway

Sensors 2017, 17(10), 2408; https://doi.org/10.3390/s17102408 - 21 Oct 2017

Cited by 12 | Viewed by 5221

Abstract

A cyber-physical attack in the industrial Internet of Things can cause severe damage to physical system. In this paper, we focus on the command disaggregation attack, wherein attackers modify disaggregated commands by intruding command aggregators like programmable logic controllers, and then maliciously manipulate [...] Read more.

A cyber-physical attack in the industrial Internet of Things can cause severe damage to physical system. In this paper, we focus on the command disaggregation attack, wherein attackers modify disaggregated commands by intruding command aggregators like programmable logic controllers, and then maliciously manipulate the physical process. It is necessary to investigate these attacks, analyze their impact on the physical process, and seek effective detection mechanisms. We depict two different types of command disaggregation attack modes: (1) the command sequence is disordered and (2) disaggregated sub-commands are allocated to wrong actuators. We describe three attack models to implement these modes with going undetected by existing detection methods. A novel and effective framework is provided to detect command disaggregation attacks. The framework utilizes the correlations among two-tier command sequences, including commands from the output of central controller and sub-commands from the input of actuators, to detect attacks before disruptions occur. We have designed components of the framework and explain how to mine and use these correlations to detect attacks. We present two case studies to validate different levels of impact from various attack models and the effectiveness of the detection framework. Finally, we discuss how to enhance the detection framework. Full article

(This article belongs to the Special Issue Internet of Things and Ubiquitous Sensing)

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16 pages, 2471 KiB

Open AccessArticle

Adaptive Microwave Staring Correlated Imaging for Targets Appearing in Discrete Clusters

by Chao Tian^*

, Zheng Jiang, Weidong Chen and Dongjin Wang

Key Laboratory of Electromagnetic Space Information, Chinese Academy of Sciences, University of Science and Technology of China, Hefei 230027, China

Sensors 2017, 17(10), 2409; https://doi.org/10.3390/s17102409 - 21 Oct 2017

Cited by 9 | Viewed by 3743

Abstract

Microwave staring correlated imaging (MSCI) can achieve ultra-high resolution in real aperture staring radar imaging using the correlated imaging process (CIP) under all-weather and all-day circumstances. The CIP must combine the received echo signal with the temporal-spatial stochastic radiation field. However, a precondition [...] Read more.

Microwave staring correlated imaging (MSCI) can achieve ultra-high resolution in real aperture staring radar imaging using the correlated imaging process (CIP) under all-weather and all-day circumstances. The CIP must combine the received echo signal with the temporal-spatial stochastic radiation field. However, a precondition of the CIP is that the continuous imaging region must be discretized to a fine grid, and the measurement matrix should be accurately computed, which makes the imaging process highly complex when the MSCI system observes a wide area. This paper proposes an adaptive imaging approach for the targets in discrete clusters to reduce the complexity of the CIP. The approach is divided into two main stages. First, as discrete clustered targets are distributed in different range strips in the imaging region, the transmitters of the MSCI emit narrow-pulse waveforms to separate the echoes of the targets in different strips in the time domain; using spectral entropy, a modified method robust against noise is put forward to detect the echoes of the discrete clustered targets, based on which the strips with targets can be adaptively located. Second, in a strip with targets, the matched filter reconstruction algorithm is used to locate the regions with targets, and only the regions of interest are discretized to a fine grid; sparse recovery is used, and the band exclusion is used to maintain the non-correlation of the dictionary. Simulation results are presented to demonstrate that the proposed approach can accurately and adaptively locate the regions with targets and obtain high-quality reconstructed images. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 1878 KiB

Open AccessArticle

Separation and Analysis of Adherent and Non-Adherent Cancer Cells Using a Single-Cell Microarray Chip

by Shohei Yamamura^*, Eriko Yamada, Fukiko Kimura, Kumiko Miyajima and Hajime Shigeto

Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan

Sensors 2017, 17(10), 2410; https://doi.org/10.3390/s17102410 - 21 Oct 2017

Cited by 9 | Viewed by 6803

Abstract

A new single-cell microarray chip was designed and developed to separate and analyze single adherent and non-adherent cancer cells. The single-cell microarray chip is made of polystyrene with over 60,000 microchambers of 10 different size patterns (31–40 µm upper diameter, 11–20 µm lower [...] Read more.

A new single-cell microarray chip was designed and developed to separate and analyze single adherent and non-adherent cancer cells. The single-cell microarray chip is made of polystyrene with over 60,000 microchambers of 10 different size patterns (31–40 µm upper diameter, 11–20 µm lower diameter). A drop of suspension of adherent carcinoma (NCI-H1650) and non-adherent leukocyte (CCRF-CEM) cells was placed onto the chip, and single-cell occupancy of NCI-H1650 and CCRF-CEM was determined to be 79% and 84%, respectively. This was achieved by controlling the chip design and surface treatment. Analysis of protein expression in single NCI-H1650 and CCRF-CEM cells was performed on the single-cell microarray chip by multi-antibody staining. Additionally, with this system, we retrieved positive single cells from the microchambers by a micromanipulator. Thus, this system demonstrates the potential for easy and accurate separation and analysis of various types of single cells. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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14 pages, 5876 KiB

Open AccessArticle

An Improved Method of Pose Estimation for Lighthouse Base Station Extension

by Yi Yang¹, Dongdong Weng^1,*, Dong Li² and Hang Xun¹

¹ School of Optoelectronics, Beijing Institute of Technology (BIT) No. 5 Yard, Zhongguancun South Street Haidian District, Beijing 100081, China

² Institute of Software Chinese Academy of Sciences, No. 4 South Fourth Street, Zhongguancun, Haidian District, Beijing 100190, China

Sensors 2017, 17(10), 2411; https://doi.org/10.3390/s17102411 - 22 Oct 2017

Cited by 17 | Viewed by 6018

Abstract

In 2015, HTC and Valve launched a virtual reality headset empowered with Lighthouse, the cutting-edge space positioning technology. Although Lighthouse is superior in terms of accuracy, latency and refresh rate, its algorithms do not support base station expansion, and is flawed concerning occlusion [...] Read more.

In 2015, HTC and Valve launched a virtual reality headset empowered with Lighthouse, the cutting-edge space positioning technology. Although Lighthouse is superior in terms of accuracy, latency and refresh rate, its algorithms do not support base station expansion, and is flawed concerning occlusion in moving targets, that is, it is unable to calculate their poses with a small set of sensors, resulting in the loss of optical tracking data. In view of these problems, this paper proposes an improved pose estimation algorithm for cases where occlusion is involved. Our algorithm calculates the pose of a given object with a unified dataset comprising of inputs from sensors recognized by all base stations, as long as three or more sensors detect a signal in total, no matter from which base station. To verify our algorithm, HTC official base stations and autonomous developed receivers are used for prototyping. The experiment result shows that our pose calculation algorithm can achieve precise positioning when a few sensors detect the signal. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 2701 KiB

Open AccessArticle

A High-Temperature MEMS Surface Fence for Wall-Shear-Stress Measurement in Scramjet Flow

by Chengyu Ma

, Binghe Ma^*, Jinjun Deng, Weizheng Yuan, Zitong Zhou and Han Zhang

Key Laboratory of Micro/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(10), 2412; https://doi.org/10.3390/s17102412 - 22 Oct 2017

Cited by 1 | Viewed by 6114

Abstract

A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 [...] Read more.

A new variant of MEMS surface fence is proposed for shear-stress estimation under high-speed, high-temperature flow conditions. Investigation of high-temperature resistance including heat-resistant mechanism and process, in conjunction with high-temperature packaging design, enable the sensor to be used in environment up to 400 °C. The packaged sensor is calibrated over a range of ~65 Pa and then used to examine the development of the transient flow of the scramjet ignition process (Mach 2 airflow, stagnation pressure, and a temperature of 0.8 MPa and 950 K, respectively). The results show that the sensor is able to detect the transient flow conditions of the scramjet ignition process including shock impact, flow correction, steady state, and hydrogen off. Full article

(This article belongs to the Special Issue Sensors and Materials for Harsh Environments)

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31 pages, 13782 KiB

Open AccessArticle

Assessing Lightning and Wildfire Hazard by Land Properties and Cloud to Ground Lightning Data with Association Rule Mining in Alberta, Canada

by DongHwan Cha, Xin Wang and Jeong Woo Kim^*

Department of Geomatics Engineering, University of Calgary, Calgary, AB T2N1N4, Canada

Sensors 2017, 17(10), 2413; https://doi.org/10.3390/s17102413 - 23 Oct 2017

Cited by 11 | Viewed by 7031

Abstract

Hotspot analysis was implemented to find regions in the province of Alberta (Canada) with high frequency Cloud to Ground (CG) lightning strikes clustered together. Generally, hotspot regions are located in the central, central east, and south central regions of the study region. About [...] Read more.

Hotspot analysis was implemented to find regions in the province of Alberta (Canada) with high frequency Cloud to Ground (CG) lightning strikes clustered together. Generally, hotspot regions are located in the central, central east, and south central regions of the study region. About 94% of annual lightning occurred during warm months (June to August) and the daily lightning frequency was influenced by the diurnal heating cycle. The association rule mining technique was used to investigate frequent CG lightning patterns, which were verified by similarity measurement to check the patterns’ consistency. The similarity coefficient values indicated that there were high correlations throughout the entire study period. Most wildfires (about 93%) in Alberta occurred in forests, wetland forests, and wetland shrub areas. It was also found that lightning and wildfires occur in two distinct areas: frequent wildfire regions with a high frequency of lightning, and frequent wild-fire regions with a low frequency of lightning. Further, the preference index (PI) revealed locations where the wildfires occurred more frequently than in other class regions. The wildfire hazard area was estimated with the CG lightning hazard map and specific land use types. Full article

(This article belongs to the Special Issue Remote Sensing and GIS for Geo-Hazards and Disasters)

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10 pages, 2650 KiB

Open AccessArticle

Low-Cost Interrogation Technique for Dynamic Measurements with FBG-Based Devices

by Camilo A. R. Díaz^1,*

, Cátia Leitão^2,3

, Carlos A. Marques^2,3

, M. Fátima Domingues^2,3

, Nélia Alberto^3,4

, Maria José Pontes¹

, Anselmo Frizera¹

, Moisés R. N. Ribeiro¹

, Paulo S. B. André⁵ and Paulo F. C. Antunes^2,3

¹ Telecommunications Laboratory LABTEL, Electrical Engineering Department, Federal University of Espírito Santo, 29075-910 Espírito Santo, Brazil

² Department of Physics & I3N, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

³ Instituto de Telecomunicações, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

⁴ Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

⁵ Department of Electrical and Computer Engineering and Instituto de Telecomunicações, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal

Sensors 2017, 17(10), 2414; https://doi.org/10.3390/s17102414 - 23 Oct 2017

Cited by 65 | Viewed by 7283

Abstract

Fiber Bragg gratings are widely used optical fiber sensors for measuring temperature and/or mechanical strain. Nevertheless, the high cost of the interrogation systems is the most important drawback for their large commercial application. In this work, an in-line Fabry–Perot interferometer based edge filter [...] Read more.

Fiber Bragg gratings are widely used optical fiber sensors for measuring temperature and/or mechanical strain. Nevertheless, the high cost of the interrogation systems is the most important drawback for their large commercial application. In this work, an in-line Fabry–Perot interferometer based edge filter is explored in the interrogation of fiber Bragg grating dynamic measurements up to 5 kHz. Two devices an accelerometer and an arterial pulse wave probe were interrogated with the developed approach and the results were compared with a commercial interrogation monitor. The data obtained with the edge filter are in agreement with the commercial device, with a maximum RMSE of 0.05 being able to meet the requirements of the measurements. Resolutions of 3.6 pm and 2.4 pm were obtained, using the optical accelerometer and the arterial pulse wave probe, respectively. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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11 pages, 4879 KiB

Open AccessArticle

Stable and Fast-Response Capacitive Humidity Sensors Based on a ZnO Nanopowder/PVP-RGO Multilayer

by Hui Yang¹, Qiangqiang Ye¹, Ruixue Zeng¹, Junkai Zhang¹, Lei Yue¹, Ming Xu¹, Zhi-Jun Qiu^1,2,* and Dongping Wu^1,*

¹ State Key Laboratory of ASIC and System, Fudan University, Shanghai 200433, China

² School of Information Science and Technology, Fudan University, Shanghai 200433, China

Sensors 2017, 17(10), 2415; https://doi.org/10.3390/s17102415 - 23 Oct 2017

Cited by 59 | Viewed by 7589

Abstract

In this paper, capacitive-type humidity sensors were prepared by sequentially drop-coating the aqueous suspensions of zinc oxide (ZnO) nanopowders and polyvinyl pyrrolidone–reduced graphene oxide (PVP-RGO) nanocomposites onto interdigitated electrodes. Significant improvements in both sensitivity and linearity were achieved for the ZnO/PVP-RGO sensors compared [...] Read more.

In this paper, capacitive-type humidity sensors were prepared by sequentially drop-coating the aqueous suspensions of zinc oxide (ZnO) nanopowders and polyvinyl pyrrolidone–reduced graphene oxide (PVP-RGO) nanocomposites onto interdigitated electrodes. Significant improvements in both sensitivity and linearity were achieved for the ZnO/PVP-RGO sensors compared with the PVP-RGO/ZnO, PVP-RGO, and ZnO counterparts. Moreover, the produced ZnO/PVP-RGO sensors exhibited rather small hysteresis, fast response-recovery time, and long-term stability. Based on morphological and structural analyses, it can be inferred that the excellent humidity sensing properties of the ZnO/PVP-RGO sensors may be attributed to the high surface-to-volume ratio of the multilayer structure and the supporting roles of the PVP-RGO nanocomposites. The results in this work hence provide adequate guidelines for designing high-performance humidity sensors that make use of the multilayer structure of semiconductor oxide materials and PVP-RGO nanocomposites. Full article

(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)

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9 pages, 2366 KiB

Open AccessArticle

Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer

by Jaehyo Jung, Jihoon Lee, Siho Shin and Youn Tae Kim^*

IT Fusion Technology Research Center, Department of IT Fusion Technology, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea

Sensors 2017, 17(10), 2416; https://doi.org/10.3390/s17102416 - 23 Oct 2017

Cited by 13 | Viewed by 5642

Abstract

In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the [...] Read more.

In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V) converter to convert the current generated by the reduction-oxidation (redox) reaction of the buffer solution to a voltage signal. This signal is then digitized by the processor. The configuration of the power and ground of the printed circuit board (PCB) layer is divided into digital and analog parts to minimize the noise interference of each part. The proposed analyzer occupies an area of 5.9 × 3.25 cm² with a current resolution of 0.4 nA. A potential of 0~2.1 V can be applied between the working and the counter electrodes. The results of this study showed the accuracy of the proposed analyzer by measuring the Ruthenium(III) chloride (

{Ru}^{III}

) concentration in 10 mM phosphate-buffered saline (PBS) solution with a pH of 7.4. The measured data can be transmitted to a PC or a mobile such as a smartphone or a tablet PC using the included Bluetooth module. The proposed analyzer uses a 3.7 V, 120 mAh lithium polymer battery and can be operated for 60 min when fully charged, including data processing and wireless communication. Full article

(This article belongs to the Section Chemical Sensors)

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20 pages, 4655 KiB

Open AccessArticle

A New Polar Transfer Alignment Algorithm with the Aid of a Star Sensor and Based on an Adaptive Unscented Kalman Filter

by Jianhua Cheng, Tongda Wang^*, Lu Wang and Zhenmin Wang

College of Automation, Harbin Engineering University, Harbin 150001, China

Sensors 2017, 17(10), 2417; https://doi.org/10.3390/s17102417 - 23 Oct 2017

Cited by 19 | Viewed by 4691

Abstract

Because of the harsh polar environment, the master strapdown inertial navigation system (SINS) has low accuracy and the system model information becomes abnormal. In this case, existing polar transfer alignment (TA) algorithms which use the measurement information provided by master SINS would lose [...] Read more.

Because of the harsh polar environment, the master strapdown inertial navigation system (SINS) has low accuracy and the system model information becomes abnormal. In this case, existing polar transfer alignment (TA) algorithms which use the measurement information provided by master SINS would lose their effectiveness. In this paper, a new polar TA algorithm with the aid of a star sensor and based on an adaptive unscented Kalman filter (AUKF) is proposed to deal with the problems. Since the measurement information provided by master SINS is inaccurate, the accurate information provided by the star sensor is chosen as the measurement. With the compensation of lever-arm effect and the model of star sensor, the nonlinear navigation equations are derived. Combined with the attitude matching method, the filter models for polar TA are designed. An AUKF is introduced to solve the abnormal information of system model. Then, the AUKF is used to estimate the states of TA. Results have demonstrated that the performance of the new polar TA algorithm is better than the state-of-the-art polar TA algorithms. Therefore, the new polar TA algorithm proposed in this paper is effectively to ensure and improve the accuracy of TA in the harsh polar environment. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 1155 KiB

Open AccessArticle

Optical Methods in Fingerprint Imaging for Medical and Personality Applications

by Chia-Nan Wang^1,*

, Jing-Wein Wang^2,*, Ming-Hsun Lin^1,*, Yao-Lang Chang^1,* and Chia-Ming Kuo¹

¹ Industrial Engineering and Management, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

² Institute of Photonics and Communications, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

Sensors 2017, 17(10), 2418; https://doi.org/10.3390/s17102418 - 23 Oct 2017

Cited by 8 | Viewed by 7275

Abstract

Over the years, analysis and induction of personality traits has been a topic for individual subjective conjecture or speculation, rather than a focus of inductive scientific analysis. This study proposes a novel framework for analysis and induction of personality traits. First, 14 personality [...] Read more.

Over the years, analysis and induction of personality traits has been a topic for individual subjective conjecture or speculation, rather than a focus of inductive scientific analysis. This study proposes a novel framework for analysis and induction of personality traits. First, 14 personality constructs based on the “Big Five” personality factors were developed. Next, a new fingerprint image algorithm was used for classification, and the fingerprints were classified into eight types. The relationship between personality traits and fingerprint type was derived from the results of the questionnaire survey. After comparison of pre-test and post-test results, this study determined the induction ability of personality traits from fingerprint type. Experimental results showed that the left/right thumbprint type of a majority of subjects was left loop/right loop and that the personalities of individuals with this fingerprint type were moderate with no significant differences in the 14 personality constructs. Full article

(This article belongs to the Special Issue Optical Methods in Sensing and Imaging for Medical and Biological Applications)

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13 pages, 12657 KiB

Open AccessArticle

The SAR Payload Design and Performance for the GF-3 Mission

by Jili Sun^*, Weidong Yu and Yunkai Deng

Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

Sensors 2017, 17(10), 2419; https://doi.org/10.3390/s17102419 - 23 Oct 2017

Cited by 133 | Viewed by 9515

Abstract

This paper describes the C-band multi-polarization Synthetic Aperture Radar (SAR) sensor for the Gaofen-3 (GF-3) mission. Based on the requirement analysis, the design of working modes and SAR payload are given. An accurate antenna model is introduced for the pattern optimization and SAR [...] Read more.

This paper describes the C-band multi-polarization Synthetic Aperture Radar (SAR) sensor for the Gaofen-3 (GF-3) mission. Based on the requirement analysis, the design of working modes and SAR payload are given. An accurate antenna model is introduced for the pattern optimization and SAR performance calculation. The paper concludes with an overview of predicted performance which was verified by in-orbit tests. Full article

(This article belongs to the Special Issue First Experiences with Chinese Gaofen-3 SAR Sensor)

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22 pages, 1279 KiB

Open AccessReview

Screening and Biosensor-Based Approaches for Lung Cancer Detection

by Lulu Wang^1,2

¹ School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Hefei 230009, China

² Institute of Biomedical Technologies, Auckland University of Technology, Auckland 1142, New Zealand

Sensors 2017, 17(10), 2420; https://doi.org/10.3390/s17102420 - 23 Oct 2017

Cited by 46 | Viewed by 9977 | Correction

Abstract

Early diagnosis of lung cancer helps to reduce the cancer death rate significantly. Over the years, investigators worldwide have extensively investigated many screening modalities for lung cancer detection, including computerized tomography, chest X-ray, positron emission tomography, sputum cytology, magnetic resonance imaging and biopsy. [...] Read more.

Early diagnosis of lung cancer helps to reduce the cancer death rate significantly. Over the years, investigators worldwide have extensively investigated many screening modalities for lung cancer detection, including computerized tomography, chest X-ray, positron emission tomography, sputum cytology, magnetic resonance imaging and biopsy. However, these techniques are not suitable for patients with other pathologies. Developing a rapid and sensitive technique for early diagnosis of lung cancer is urgently needed. Biosensor-based techniques have been recently recommended as a rapid and cost-effective tool for early diagnosis of lung tumor markers. This paper reviews the recent development in screening and biosensor-based techniques for early lung cancer detection. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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20 pages, 3025 KiB

Open AccessArticle

A Hyperspectral Image Classification Framework with Spatial Pixel Pair Features

by Lingyan Ran¹

, Yanning Zhang^1,*, Wei Wei^1,*

and Qilin Zhang²

¹ School of Computer Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China

² Highly Automated Driving Team, HERE Technologies Automotive Division, Chicago, IL 60606, USA

Sensors 2017, 17(10), 2421; https://doi.org/10.3390/s17102421 - 23 Oct 2017

Cited by 57 | Viewed by 12159

Abstract

During recent years, convolutional neural network (CNN)-based methods have been widely applied to hyperspectral image (HSI) classification by mostly mining the spectral variabilities. However, the spatial consistency in HSI is rarely discussed except as an extra convolutional channel. Very recently, the development of [...] Read more.

During recent years, convolutional neural network (CNN)-based methods have been widely applied to hyperspectral image (HSI) classification by mostly mining the spectral variabilities. However, the spatial consistency in HSI is rarely discussed except as an extra convolutional channel. Very recently, the development of pixel pair features (PPF) for HSI classification offers a new way of incorporating spatial information. In this paper, we first propose an improved PPF-style feature, the spatial pixel pair feature (SPPF), that better exploits both the spatial/contextual information and spectral information. On top of the new SPPF, we further propose a flexible multi-stream CNN-based classification framework that is compatible with multiple in-stream sub-network designs. The proposed SPPF is different from the original PPF in its paring pixel selection strategy: only pixels immediately adjacent to the central one are eligible, therefore imposing stronger spatial regularization. Additionally, with off-the-shelf classification sub-network designs, the proposed multi-stream, late-fusion CNN-based framework outperforms competing ones without requiring extensive network configuration tuning. Experimental results on three publicly available datasets demonstrate the performance of the proposed SPPF-based HSI classification framework. Full article

(This article belongs to the Special Issue Analysis of Multispectral and Hyperspectral Data)

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14 pages, 4071 KiB

Open AccessFeature PaperArticle

Planar Microstrip Ring Resonators for Microwave-Based Gas Sensing: Design Aspects and Initial Transducers for Humidity and Ammonia Sensing

by Andreas Bogner

, Carsten Steiner

, Stefanie Walter

, Jaroslaw Kita

, Gunter Hagen

and Ralf Moos^*

Department of Functional Materials, University of Bayreuth, 95447 Bayreuth, Germany

Sensors 2017, 17(10), 2422; https://doi.org/10.3390/s17102422 - 24 Oct 2017

Cited by 70 | Viewed by 13341

Abstract

A planar microstrip ring resonator structure on alumina was developed using the commercial FEM software COMSOL. Design parameters were evaluated, eventually leading to an optimized design of a miniaturized microwave gas sensor. The sensor was covered with a zeolite film. The device was [...] Read more.

A planar microstrip ring resonator structure on alumina was developed using the commercial FEM software COMSOL. Design parameters were evaluated, eventually leading to an optimized design of a miniaturized microwave gas sensor. The sensor was covered with a zeolite film. The device was successfully operated at around 8.5 GHz at room temperature as a humidity sensor. In the next step, an additional planar heater will be included on the reverse side of the resonator structure to allow for testing of gas-sensitive materials under sensor conditions. Full article

(This article belongs to the Collection Gas Sensors)

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Graphical abstract

13 pages, 710 KiB

Open AccessArticle

Laser-Interferometric Broadband Seismometer for Epicenter Location Estimation

by Kyunghyun Lee, Hyungkwan Kwon and Kwanho You^*

Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea

Sensors 2017, 17(10), 2423; https://doi.org/10.3390/s17102423 - 23 Oct 2017

Cited by 10 | Viewed by 5665

Abstract

In this paper, we suggest a seismic signal measurement system that uses a laser interferometer. The heterodyne laser interferometer is used as a seismometer due to its high accuracy and robustness. Seismic data measured by the laser interferometer is used to analyze crucial [...] Read more.

In this paper, we suggest a seismic signal measurement system that uses a laser interferometer. The heterodyne laser interferometer is used as a seismometer due to its high accuracy and robustness. Seismic data measured by the laser interferometer is used to analyze crucial earthquake characteristics. To measure P-S time more precisely, the short time Fourier transform and instantaneous frequency estimation methods are applied to the intensity signal (

I_{y}

) of the laser interferometer. To estimate the epicenter location, the range difference of arrival algorithm is applied with the P-S time result. The linear matrix equation of the epicenter localization can be derived using P-S time data obtained from more than three observatories. We prove the performance of the proposed algorithm through simulation and experimental results. Full article

(This article belongs to the Special Issue Innovative Smart Sensors for Control Systems)

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6 pages, 2338 KiB

Open AccessArticle

Effect of MgO Underlying Layer on the Growth of GaO_x Tunnel Barrier in Epitaxial Fe/GaO_x/(MgO)/Fe Magnetic Tunnel Junction Structure

by Sai Krishna Narayananellore¹

, Naoki Doko^1,2, Norihiro Matsuo^1,2, Hidekazu Saito^1,* and Shinji Yuasa¹

¹ National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, Japan

² Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan

Sensors 2017, 17(10), 2424; https://doi.org/10.3390/s17102424 - 23 Oct 2017

Cited by 6 | Viewed by 4724

Abstract

We investigated the effect of a thin MgO underlying layer (~3 monoatomic layers) on the growth of GaO_x tunnel barrier in Fe/GaO_x/(MgO)/Fe(001) magnetic tunnel junctions. To obtain a single-crystalline barrier, an in situ annealing was conducted with the temperature being [...] Read more.

We investigated the effect of a thin MgO underlying layer (~3 monoatomic layers) on the growth of GaO_x tunnel barrier in Fe/GaO_x/(MgO)/Fe(001) magnetic tunnel junctions. To obtain a single-crystalline barrier, an in situ annealing was conducted with the temperature being raised up to 500 °C under an O₂ atmosphere. This annealing was performed after the deposition of the GaO_x on the Fe(001) bottom electrode with or without the MgO(001) underlying layer. Reflection high-energy electron diffraction patterns after the annealing indicated the formation of a single-crystalline layer regardless of with or without the MgO layer. Ex situ structural studies such as transmission electron microscopy revealed that the GaO_x grown on the MgO underlying layer has a cubic MgAl₂O₄-type spinel structure with a (001) orientation. When without MgO layer, however, a Ga-Fe-O ternary compound having the same crystal structure and orientation as the crystalline GaO_x was observed. The results indicate that the MgO underlying layer effectively prevents the Fe bottom electrode from oxidation during the annealing process. Tunneling magneto-resistance effect was observed only for the sample with the MgO underlying layer, suggesting that Ga-Fe-O layer is not an effective tunnel-barrier. Full article

(This article belongs to the Special Issue GMR and TMR Sensors)

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12 pages, 1795 KiB

Open AccessArticle

Bias-Voltage Stabilizer for HVHF Amplifiers in VHF Pulse-Echo Measurement Systems

by Hojong Choi¹, Chulwoo Park¹, Jungsuk Kim^2,* and Hayong Jung^3,*

¹ Department of Medical IT Convergence Engineering, Kumho National Institute of Technology, Gumi 39253, Korea

² Department of Biomedical Engineering, Gachon University, In-cheon 21936, Korea

³ National Institute of Health Transducer Resource Center and Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA

Sensors 2017, 17(10), 2425; https://doi.org/10.3390/s17102425 - 23 Oct 2017

Cited by 22 | Viewed by 7362

Abstract

The impact of high-voltage–high-frequency (HVHF) amplifiers on echo-signal quality is greater with very-high-frequency (VHF, ≥100 MHz) ultrasound transducers than with low-frequency (LF, ≤15 MHz) ultrasound transducers. Hence, the bias voltage of an HVHF amplifier must be stabilized to ensure stable echo-signal amplitudes. We [...] Read more.

The impact of high-voltage–high-frequency (HVHF) amplifiers on echo-signal quality is greater with very-high-frequency (VHF, ≥100 MHz) ultrasound transducers than with low-frequency (LF, ≤15 MHz) ultrasound transducers. Hence, the bias voltage of an HVHF amplifier must be stabilized to ensure stable echo-signal amplitudes. We propose a bias-voltage stabilizer circuit to maintain stable DC voltages over a wide input range, thus reducing the harmonic-distortion components of the echo signals in VHF pulse-echo measurement systems. To confirm the feasibility of the bias-voltage stabilizer, we measured and compared the deviations in the gain of the HVHF amplifier with and without a bias-voltage stabilizer. Between −13 and 26 dBm, the measured gain deviations of a HVHF amplifier with a bias-voltage stabilizer are less than that of an amplifier without a bias-voltage stabilizer. In order to confirm the feasibility of the bias-voltage stabilizer, we compared the pulse-echo responses of the amplifiers, which are typically used for the evaluation of transducers or electronic components used in pulse-echo measurement systems. From the responses, we observed that the amplitudes of the echo signals of a VHF transducer triggered by the HVHF amplifier with a bias-voltage stabilizer were higher than those of the transducer triggered by the HVHF amplifier alone. The second, third, and fourth harmonic-distortion components of the HVHF amplifier with the bias-voltage stabilizer were also lower than those of the HVHF amplifier alone. Hence, the proposed scheme is a promising method for stabilizing the bias voltage of an HVHF amplifier, and improving the echo-signal quality of VHF transducers. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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23 pages, 27304 KiB

Open AccessArticle

A Search-and-Rescue Robot System for Remotely Sensing the Underground Coal Mine Environment

by Jingchao Zhao^1,2

, Junyao Gao^1,3,*, Fangzhou Zhao^1,3 and Yi Liu^1,4

¹ Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, 5 Nandajie, Zhongguancun, Haidian, Beijing 100081, China

² Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing 100081, China

³ Key Laboratory of Biomimetic Robots and Systems, Ministry of Education, Beijing Institute of Technology, Beijing 100081, China

⁴ Key Laboratory of Intelligent Control and Decision of Complex System, Beijing Institute of Technology, Beijing 100081, China

Sensors 2017, 17(10), 2426; https://doi.org/10.3390/s17102426 - 23 Oct 2017

Cited by 79 | Viewed by 17750

Abstract

This paper introduces a search-and-rescue robot system used for remote sensing of the underground coal mine environment, which is composed of an operating control unit and two mobile robots with explosion-proof and waterproof function. This robot system is designed to observe and collect [...] Read more.

This paper introduces a search-and-rescue robot system used for remote sensing of the underground coal mine environment, which is composed of an operating control unit and two mobile robots with explosion-proof and waterproof function. This robot system is designed to observe and collect information of the coal mine environment through remote control. Thus, this system can be regarded as a multifunction sensor, which realizes remote sensing. When the robot system detects danger, it will send out signals to warn rescuers to keep away. The robot consists of two gas sensors, two cameras, a two-way audio, a 1 km-long fiber-optic cable for communication and a mechanical explosion-proof manipulator. Especially, the manipulator is a novel explosion-proof manipulator for cleaning obstacles, which has 3-degree-of-freedom, but is driven by two motors. Furthermore, the two robots can communicate in series for 2 km with the operating control unit. The development of the robot system may provide a reference for developing future search-and-rescue systems. Full article

(This article belongs to the Special Issue Smart Sensors for Mechatronic and Robotic Systems)

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22 pages, 22785 KiB

Open AccessArticle

A Novel Unsupervised Segmentation Quality Evaluation Method for Remote Sensing Images

by Han Gao^1,2

, Yunwei Tang^1,*

, Linhai Jing^1,*, Hui Li¹

and Haifeng Ding¹

¹ Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Sensors 2017, 17(10), 2427; https://doi.org/10.3390/s17102427 - 24 Oct 2017

Cited by 38 | Viewed by 5595

Abstract

The segmentation of a high spatial resolution remote sensing image is a critical step in geographic object-based image analysis (GEOBIA). Evaluating the performance of segmentation without ground truth data, i.e., unsupervised evaluation, is important for the comparison of segmentation algorithms and the automatic [...] Read more.

The segmentation of a high spatial resolution remote sensing image is a critical step in geographic object-based image analysis (GEOBIA). Evaluating the performance of segmentation without ground truth data, i.e., unsupervised evaluation, is important for the comparison of segmentation algorithms and the automatic selection of optimal parameters. This unsupervised strategy currently faces several challenges in practice, such as difficulties in designing effective indicators and limitations of the spectral values in the feature representation. This study proposes a novel unsupervised evaluation method to quantitatively measure the quality of segmentation results to overcome these problems. In this method, multiple spectral and spatial features of images are first extracted simultaneously and then integrated into a feature set to improve the quality of the feature representation of ground objects. The indicators designed for spatial stratified heterogeneity and spatial autocorrelation are included to estimate the properties of the segments in this integrated feature set. These two indicators are then combined into a global assessment metric as the final quality score. The trade-offs of the combined indicators are accounted for using a strategy based on the Mahalanobis distance, which can be exhibited geometrically. The method is tested on two segmentation algorithms and three testing images. The proposed method is compared with two existing unsupervised methods and a supervised method to confirm its capabilities. Through comparison and visual analysis, the results verified the effectiveness of the proposed method and demonstrated the reliability and improvements of this method with respect to other methods. Full article

(This article belongs to the Special Issue Spatial Analysis and Remote Sensing)

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22 pages, 4707 KiB

Open AccessArticle

Comparison between Random Forests, Artificial Neural Networks and Gradient Boosted Machines Methods of On-Line Vis-NIR Spectroscopy Measurements of Soil Total Nitrogen and Total Carbon

by Said Nawar^1,2,3,* and Abdul M. Mouazen¹

¹ Department of Soil Management, Ghent University, Coupure 653, 9000 Gent, Belgium

² Cranfield Soil and AgriFood Institute, School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK

³ Faculty of Agriculture, Suez Canal University, Ismailia 41522, Egypt

Sensors 2017, 17(10), 2428; https://doi.org/10.3390/s17102428 - 24 Oct 2017

Cited by 147 | Viewed by 8682

Abstract

Accurate and detailed spatial soil information about within-field variability is essential for variable-rate applications of farm resources. Soil total nitrogen (TN) and total carbon (TC) are important fertility parameters that can be measured with on-line (mobile) visible and near infrared (vis-NIR) spectroscopy. This [...] Read more.

Accurate and detailed spatial soil information about within-field variability is essential for variable-rate applications of farm resources. Soil total nitrogen (TN) and total carbon (TC) are important fertility parameters that can be measured with on-line (mobile) visible and near infrared (vis-NIR) spectroscopy. This study compares the performance of local farm scale calibrations with those based on the spiking of selected local samples from both fields into an European dataset for TN and TC estimation using three modelling techniques, namely gradient boosted machines (GBM), artificial neural networks (ANNs) and random forests (RF). The on-line measurements were carried out using a mobile, fiber type, vis-NIR spectrophotometer (305–2200 nm) (AgroSpec from tec5, Germany), during which soil spectra were recorded in diffuse reflectance mode from two fields in the UK. After spectra pre-processing, the entire datasets were then divided into calibration (75%) and prediction (25%) sets, and calibration models for TN and TC were developed using GBM, ANN and RF with leave-one-out cross-validation. Results of cross-validation showed that the effect of spiking of local samples collected from a field into an European dataset when combined with RF has resulted in the highest coefficients of determination (R²) values of 0.97 and 0.98, the lowest root mean square error (RMSE) of 0.01% and 0.10%, and the highest residual prediction deviations (RPD) of 5.58 and 7.54, for TN and TC, respectively. Results for laboratory and on-line predictions generally followed the same trend as for cross-validation in one field, where the spiked European dataset-based RF calibration models outperformed the corresponding GBM and ANN models. In the second field ANN has replaced RF in being the best performing. However, the local field calibrations provided lower R² and RPD in most cases. Therefore, from a cost-effective point of view, it is recommended to adopt the spiked European dataset-based RF/ANN calibration models for successful prediction of TN and TC under on-line measurement conditions. Full article

(This article belongs to the Special Issue Sensors in Agriculture)

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9 pages, 2489 KiB

Open AccessArticle

Fiber-Optic Point-Based Sensor Using Specklegram Measurement

by Jiao-Jiao Wang, Shao-Cheng Yan, Ya-Ping Ruan^*, Fei Xu and Yan-Qing Lu

College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China

Sensors 2017, 17(10), 2429; https://doi.org/10.3390/s17102429 - 24 Oct 2017

Cited by 27 | Viewed by 6506

Abstract

Here, we report a fiber-optic point-based sensor to measure temperature and weight based on correlated specklegrams induced by spatial multimode interference. The device is realized simply by splicing a multimode fiber (MMF) to a single-mode fiber (SMF) with a core offset. A series [...] Read more.

Here, we report a fiber-optic point-based sensor to measure temperature and weight based on correlated specklegrams induced by spatial multimode interference. The device is realized simply by splicing a multimode fiber (MMF) to a single-mode fiber (SMF) with a core offset. A series of experiments demonstrates the approximately linear relation between the correlation coefficient and variation. Furthermore, we show the potential applications of the refractive index sensing of our device by disconnecting the splicing point of MMF and SMF. A modification of the algorithm in order to improve the sensitivity of the sensor is also discussed at the end of the paper. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 3402 KiB

Open AccessReview

Lithium Ion Sensors

by Megi Kamenica, Raghuram Reddy Kothur

, Alison Willows

, Bhavik Anil Patel and Peter J. Cragg^*

School of Pharmacy & Biomolecular Sciences, University of Brighton, Huxley Building, Brighton BN2 4GJ, UK

Sensors 2017, 17(10), 2430; https://doi.org/10.3390/s17102430 - 24 Oct 2017

Cited by 45 | Viewed by 8629

Abstract

The detection and monitoring of lithium in environmental and clinical settings is becoming increasingly important. In this review, sensors incorporating conductive polymers and lithium bronzes are discussed, together with electrochemical and spectroscopic approaches. Ionophore-based methods have been employed extensively, with varying degrees of [...] Read more.

The detection and monitoring of lithium in environmental and clinical settings is becoming increasingly important. In this review, sensors incorporating conductive polymers and lithium bronzes are discussed, together with electrochemical and spectroscopic approaches. Ionophore-based methods have been employed extensively, with varying degrees of selectivity and sensitivity, and these are discussed in depth. Full article

(This article belongs to the Section Chemical Sensors)

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10 pages, 7855 KiB

Open AccessArticle

Three-Axis Ground Reaction Force Distribution during Straight Walking

by Masataka Hori, Akihito Nakai and Isao Shimoyama^*

Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Sensors 2017, 17(10), 2431; https://doi.org/10.3390/s17102431 - 24 Oct 2017

Cited by 8 | Viewed by 8134

Abstract

We measured the three-axis ground reaction force (GRF) distribution during straight walking. Small three-axis force sensors composed of rubber and sensor chips were fabricated and calibrated. After sensor calibration, 16 force sensors were attached to the left shoe. The three-axis force distribution during [...] Read more.

We measured the three-axis ground reaction force (GRF) distribution during straight walking. Small three-axis force sensors composed of rubber and sensor chips were fabricated and calibrated. After sensor calibration, 16 force sensors were attached to the left shoe. The three-axis force distribution during straight walking was measured, and the local features of the three-axis force under the sole of the shoe were analyzed. The heel area played a role in receiving the braking force, the base area of the fourth and fifth toes applied little vertical or shear force, the base area of the second and third toes generated a portion of the propulsive force and received a large vertical force, and the base area of the big toe helped move the body’s center of mass to the other foot. The results demonstrate that measuring the three-axis GRF distribution is useful for a detailed analysis of bipedal locomotion. Full article

(This article belongs to the Special Issue Sensors for Gait, Posture, and Health Monitoring)

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13 pages, 1752 KiB

Open AccessArticle

Towards Harmonious Coexistence in the Unlicensed Spectrum: Rational Cooperation of Operators

by Sunghwan Bae

and Hongseok Kim^*

Department of Electronic Engineering, Sogang University, Seoul 04107, Korea

Sensors 2017, 17(10), 2432; https://doi.org/10.3390/s17102432 - 24 Oct 2017

Viewed by 4750

Abstract

5G New Radio (NR) operating in the unlicensed spectrum is accelerating the Fourth Industrial Revolution by supporting Internet of Things (IoT) networks or Industrial IoT deployments. Specifically, LTE-Advanced (LTE-A) is looking to achieve spectrum integration through coexistence with multi-radio access technology (RAT) systems [...] Read more.

5G New Radio (NR) operating in the unlicensed spectrum is accelerating the Fourth Industrial Revolution by supporting Internet of Things (IoT) networks or Industrial IoT deployments. Specifically, LTE-Advanced (LTE-A) is looking to achieve spectrum integration through coexistence with multi-radio access technology (RAT) systems in the same unlicensed bands with both licensed-assisted and stand-alone access. The listen-before-talk (LBT) mechanism is mainly considered to enable an LTE operator to protect other incumbent unlicensed systems. In this article, we investigate the behaviors of multiple LTE operators along with the deployment of WiFi networks in the unlicensed spectrum from both short- and long-term points of view. In countries without mandatory LBT requirements, we show that an LTE operator is susceptible to collusion with another LTE operator, thus exploiting scarce spectrum resources by deceiving other wireless networks into thinking that channels are always busy; hence, mandatory usage of LTE with LBT is highly recommended at national level to achieve harmonious coexistence in the unlicensed spectrum. We discuss several possible coexistence scenarios to resolve the operator’s dilemmaas well as to improve unlicensed spectrum efficiency among multi-RAT systems, which is viable in the near future. Full article

(This article belongs to the Special Issue Green Wireless Networks in 5G-inspired Applications)

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25 pages, 3475 KiB

Open AccessArticle

mlCAF: Multi-Level Cross-Domain Semantic Context Fusioning for Behavior Identification

by Muhammad Asif Razzaq¹

, Claudia Villalonga², Sungyoung Lee¹, Usman Akhtar¹

, Maqbool Ali¹, Eun-Soo Kim³, Asad Masood Khattak⁴, Hyonwoo Seung⁵, Taeho Hur¹, Jaehun Bang¹

, Dohyeong Kim¹ and Wajahat Ali Khan^1,*

¹ Ubiquitous Computing Lab, Department of Computer Engineering, Kyung Hee University (Global Campus), Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701, Korea

² School of Engineering and Technology, Universidad Internacional de La Rioja (UNIR), C/ Almansa 101, 28040 Madrid, Spain

³ Department of Electronic Engineering, Kwangwoon University 20 Kwangwoon-ro, Nowon-gu, Seoul 01897, Korea

⁴ College of Technological Innovation, Zayed University, Abu Dhabi 144534, UAE

⁵ Department of Computer Science, Seoul Women’s University, Seoul 01797, Korea

Sensors 2017, 17(10), 2433; https://doi.org/10.3390/s17102433 - 24 Oct 2017

Cited by 10 | Viewed by 5593

Abstract

The emerging research on automatic identification of user’s contexts from the cross-domain environment in ubiquitous and pervasive computing systems has proved to be successful. Monitoring the diversified user’s contexts and behaviors can help in controlling lifestyle associated to chronic diseases using context-aware applications. [...] Read more.

The emerging research on automatic identification of user’s contexts from the cross-domain environment in ubiquitous and pervasive computing systems has proved to be successful. Monitoring the diversified user’s contexts and behaviors can help in controlling lifestyle associated to chronic diseases using context-aware applications. However, availability of cross-domain heterogeneous contexts provides a challenging opportunity for their fusion to obtain abstract information for further analysis. This work demonstrates extension of our previous work from a single domain (i.e., physical activity) to multiple domains (physical activity, nutrition and clinical) for context-awareness. We propose multi-level Context-aware Framework (mlCAF), which fuses the multi-level cross-domain contexts in order to arbitrate richer behavioral contexts. This work explicitly focuses on key challenges linked to multi-level context modeling, reasoning and fusioning based on the mlCAF open-source ontology. More specifically, it addresses the interpretation of contexts from three different domains, their fusioning conforming to richer contextual information. This paper contributes in terms of ontology evolution with additional domains, context definitions, rules and inclusion of semantic queries. For the framework evaluation, multi-level cross-domain contexts collected from 20 users were used to ascertain abstract contexts, which served as basis for behavior modeling and lifestyle identification. The experimental results indicate a context recognition average accuracy of around 92.65% for the collected cross-domain contexts. Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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14 pages, 2285 KiB

Open AccessArticle

Precise GNSS Positioning Using Smart Devices

by Eugenio Realini^*,†

, Stefano Caldera^†, Lisa Pertusini^† and Daniele Sampietro

¹ Geomatics Research & Development s.r.l. (GReD), via Cavour 2, c/o ComoNExT, 22074 Lomazzo (Como), Italy

^† These authors contributed equally to this work.

Sensors 2017, 17(10), 2434; https://doi.org/10.3390/s17102434 - 24 Oct 2017

Cited by 119 | Viewed by 12194

Abstract

The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether [...] Read more.

The recent access to GNSS (Global Navigation Satellite System) phase observations on smart devices, enabled by Google through its Android operating system, opens the possibility to apply precise positioning techniques using off-the-shelf, mass-market devices. The target of this work is to evaluate whether this is feasible, and which positioning accuracy can be achieved by relative positioning of the smart device with respect to a base station. Positioning of a Google/HTC Nexus 9 tablet was performed by means of batch least-squares adjustment of L1 phase double-differenced observations, using the open source goGPS software, over baselines ranging from approximately 10 m to 8 km, with respect to both physical (geodetic or low-cost) and virtual base stations. The same positioning procedure was applied also to a co-located u-blox low-cost receiver, to compare the performance between the receiver and antenna embedded in the Nexus 9 and a standard low-cost single-frequency receiver with external patch antenna. The results demonstrate that with a smart device providing raw GNSS phase observations, like the Nexus 9, it is possible to reach decimeter-level accuracy through rapid-static surveys, without phase ambiguity resolution. It is expected that sub-centimeter accuracy could be achieved, as demonstrated for the u-blox case, if integer phase ambiguities were correctly resolved. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 5595 KiB

Open AccessArticle

Detection of Stress Levels from Biosignals Measured in Virtual Reality Environments Using a Kernel-Based Extreme Learning Machine

by Dongrae Cho¹, Jinsil Ham¹, Jooyoung Oh¹, Jeanho Park², Sayup Kim², Nak-Kyu Lee² and Boreom Lee^1,*

¹ Department of Biomedical Science and Engineering (BMSE), Institute of Integrated Technology (IIT), Gwangju Institute of Science and Technology, Gwangju 61005, Korea

² Research Institute of Industrial Technology Convergence, Korea Institute of Industrial Technology, Ansan 15588, Korea

Sensors 2017, 17(10), 2435; https://doi.org/10.3390/s17102435 - 24 Oct 2017

Cited by 117 | Viewed by 9938

Abstract

Virtual reality (VR) is a computer technique that creates an artificial environment composed of realistic images, sounds, and other sensations. Many researchers have used VR devices to generate various stimuli, and have utilized them to perform experiments or to provide treatment. In this [...] Read more.

Virtual reality (VR) is a computer technique that creates an artificial environment composed of realistic images, sounds, and other sensations. Many researchers have used VR devices to generate various stimuli, and have utilized them to perform experiments or to provide treatment. In this study, the participants performed mental tasks using a VR device while physiological signals were measured: a photoplethysmogram (PPG), electrodermal activity (EDA), and skin temperature (SKT). In general, stress is an important factor that can influence the autonomic nervous system (ANS). Heart-rate variability (HRV) is known to be related to ANS activity, so we used an HRV derived from the PPG peak interval. In addition, the peak characteristics of the skin conductance (SC) from EDA and SKT variation can also reflect ANS activity; we utilized them as well. Then, we applied a kernel-based extreme-learning machine (K-ELM) to correctly classify the stress levels induced by the VR task to reflect five different levels of stress situations: baseline, mild stress, moderate stress, severe stress, and recovery. Twelve healthy subjects voluntarily participated in the study. Three physiological signals were measured in stress environment generated by VR device. As a result, the average classification accuracy was over 95% using K-ELM and the integrated feature (IT = HRV + SC + SKT). In addition, the proposed algorithm can embed a microcontroller chip since K-ELM algorithm have very short computation time. Therefore, a compact wearable device classifying stress levels using physiological signals can be developed. Full article

(This article belongs to the Special Issue Advanced Electronic Devices, Circuits, and Signal Processing for Biomedical Sensors Application)

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7 pages, 3507 KiB

Open AccessArticle

Development and Elucidation of a Novel Fluorescent Boron-Sensor for the Analysis of Boronic Acid-Containing Compounds

by Yoshihide Hattori^*

, Takuya Ogaki, Miki Ishimura, Yoichiro Ohta and Mitsunori Kirihata

Research Center of Boron Neutron Capture Therapy, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan

Sensors 2017, 17(10), 2436; https://doi.org/10.3390/s17102436 - 24 Oct 2017

Cited by 16 | Viewed by 7390

Abstract

Novel boron-containing drugs have recently been suggested as a new class of pharmaceuticals. However, the majority of current boron-detection techniques require expensive facilities and/or tedious pretreatment methods. Thus, to develop a novel and convenient detection method for boron-based pharmaceuticals, imine-type boron-chelating-ligands were previously [...] Read more.

Novel boron-containing drugs have recently been suggested as a new class of pharmaceuticals. However, the majority of current boron-detection techniques require expensive facilities and/or tedious pretreatment methods. Thus, to develop a novel and convenient detection method for boron-based pharmaceuticals, imine-type boron-chelating-ligands were previously synthesized for use in a fluorescent sensor for boronic acid containing compounds. However, the fluorescence quantum yield of the imine-type sensor was particularly low, and the sensor was easily decomposed in aqueous media. Thus, in this paper, we report the development of a novel, convenient, and stable fluorescent boron-sensor based on O- and N-chelation (i.e., 2-(pyridine-2yl)phenol), and a corresponding method for the quantitative and qualitative detection of boronic acid-containing compounds using this commercially available sensor is presented. Full article

(This article belongs to the Special Issue Fluorescent Probes and Sensors)

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14 pages, 9077 KiB

Open AccessArticle

Near-Field Three-Dimensional Planar Millimeter-Wave Holographic Imaging by Using Frequency Scaling Algorithm

by Ye Zhang

, Bin Deng^*, Qi Yang

, Jingkun Gao

, Yuliang Qin and Hongqiang Wang

College of Electronic Science, National University of Defense Technology, Changsha 410073, China

Sensors 2017, 17(10), 2438; https://doi.org/10.3390/s17102438 - 24 Oct 2017

Cited by 15 | Viewed by 5786

Abstract

In this paper, a fast three-dimensional (3-D) frequency scaling algorithm (FSA) with large depth of focus is presented for near-field planar millimeter-wave (MMW) holographic imaging. Considering the cross-range range coupling term which is neglected in the conventional range migration algorithm (RMA), we propose [...] Read more.

In this paper, a fast three-dimensional (3-D) frequency scaling algorithm (FSA) with large depth of focus is presented for near-field planar millimeter-wave (MMW) holographic imaging. Considering the cross-range range coupling term which is neglected in the conventional range migration algorithm (RMA), we propose an algorithm performing the range cell migration correction for de-chirped signals without interpolation by using a 3-D frequency scaling operation. First, to deal with the cross-range range coupling term, a 3-D frequency scaling operator is derived to eliminate the space variation of range cell migration. Then, a range migration correction factor is performed to compensate for the residual range cell migration. Finally, the imaging results are obtained by matched filtering in the cross-range direction. Compared with the conventional RMA, the proposed algorithm is comparable in accuracy but more efficient by using only chirp multiplications and fast Fourier transforms (FFTs). The algorithm has been tested with satisfying results by both simulation and experiment. Full article

(This article belongs to the Section Remote Sensors)

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Sensors, Volume 17, Issue 10 (October 2017) – 280 articles

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