Sensors

15 pages, 4782 KiB

Open AccessArticle

Development of Diamond and Silicon MEMS Sensor Arrays with Integrated Readout for Vapor Detection

by Maira Possas-Abreu^1,*, Farbod Ghassemi¹, Lionel Rousseau¹, Emmanuel Scorsone², Emilie Descours³ and Gaelle Lissorgues¹

¹ ESYCOM, ESIEE-Paris, Cité Descartes BP99, 93162 Noisy-le-Grand, France

² CEA, LIST, Diamond Sensor Laboratory, 91191 Gif-sur-Yvette, France

³ ISIPCA, 34–36 Rue du Parc de Clagny, 78000 Versailles, France

Sensors 2017, 17(6), 1163; https://doi.org/10.3390/s17061163 - 24 May 2017

Cited by 21 | Viewed by 7122

Abstract

This paper reports on the development of an autonomous instrument based on an array of eight resonant microcantilevers for vapor detection. The fabricated sensors are label-free devices, allowing chemical and biological functionalization. In this work, sensors based on an array of silicon and [...] Read more.

This paper reports on the development of an autonomous instrument based on an array of eight resonant microcantilevers for vapor detection. The fabricated sensors are label-free devices, allowing chemical and biological functionalization. In this work, sensors based on an array of silicon and synthetic diamond microcantilevers are sensitized with polymeric films for the detection of analytes. The main advantage of the proposed system is that sensors can be easily changed for another application or for cleaning since the developed gas cell presents removable electrical connections. We report the successful application of our electronic nose approach to detect 12 volatile organic compounds. Moreover, the response pattern of the cantilever arrays is interpreted via principal component analysis (PCA) techniques in order to identify samples. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in France 2016)

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16 pages, 1763 KiB

Open AccessArticle

Natural Inspired Intelligent Visual Computing and Its Application to Viticulture

by Li Minn Ang^1,3, Kah Phooi Seng^1,2,3,* and Feng Lu Ge³

¹ School of Computing & Mathematics, Charles Sturt University, Wagga Wagga 2678, Australia

² National Grape and Wine Industries Centre, Wagga Wagga 2678, Australia

³ CM3 Research Centre, Charles Sturt University, Bathurst 2795, Australia

Sensors 2017, 17(6), 1186; https://doi.org/10.3390/s17061186 - 23 May 2017

Cited by 1 | Viewed by 5311

Abstract

This paper presents an investigation of natural inspired intelligent computing and its corresponding application towards visual information processing systems for viticulture. The paper has three contributions: (1) a review of visual information processing applications for viticulture; (2) the development of natural inspired computing [...] Read more.

This paper presents an investigation of natural inspired intelligent computing and its corresponding application towards visual information processing systems for viticulture. The paper has three contributions: (1) a review of visual information processing applications for viticulture; (2) the development of natural inspired computing algorithms based on artificial immune system (AIS) techniques for grape berry detection; and (3) the application of the developed algorithms towards real-world grape berry images captured in natural conditions from vineyards in Australia. The AIS algorithms in (2) were developed based on a nature-inspired clonal selection algorithm (CSA) which is able to detect the arcs in the berry images with precision, based on a fitness model. The arcs detected are then extended to perform the multiple arcs and ring detectors information processing for the berry detection application. The performance of the developed algorithms were compared with traditional image processing algorithms like the circular Hough transform (CHT) and other well-known circle detection methods. The proposed AIS approach gave a Fscore of 0.71 compared with Fscores of 0.28 and 0.30 for the CHT and a parameter-free circle detection technique (RPCD) respectively. Full article

(This article belongs to the Special Issue System-Integrated Intelligence and Intelligent Systems)

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19 pages, 6117 KiB

Open AccessArticle

Multimodal Bio-Inspired Tactile Sensing Module for Surface Characterization

by Thiago Eustaquio Alves de Oliveira^1,*

, Ana-Maria Cretu² and Emil M. Petriu^1,†

¹ School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6N5, Canada

² Department of Computer Science and Engineering, Université du Quebec en Outaouais, Gatineau, QC J8X 3X7, Canada

^† This paper is an extended version of Alves de Oliveira, T.E.; Rocha Lima, B.M.; Cretu, A.; Petriu, E. Tactile profile classification using a multimodal MEMs-based sensing module. In Proceedings of the 3rd International Electronic Conference on Sensors and Applications, online, 15–30 November 2016; Volume 3, p. E007.

Sensors 2017, 17(6), 1187; https://doi.org/10.3390/s17061187 - 23 May 2017

Cited by 24 | Viewed by 7525

Abstract

Robots are expected to recognize the properties of objects in order to handle them safely and efficiently in a variety of applications, such as health and elder care, manufacturing, or high-risk environments. This paper explores the issue of surface characterization by monitoring the [...] Read more.

Robots are expected to recognize the properties of objects in order to handle them safely and efficiently in a variety of applications, such as health and elder care, manufacturing, or high-risk environments. This paper explores the issue of surface characterization by monitoring the signals acquired by a novel bio-inspired tactile probe in contact with ridged surfaces. The tactile module comprises a nine Degree of Freedom Microelectromechanical Magnetic, Angular Rate, and Gravity system (9-DOF MEMS MARG) and a deep MEMS pressure sensor embedded in a compliant structure that mimics the function and the organization of mechanoreceptors in human skin as well as the hardness of the human skin. When the modules tip slides over a surface, the MARG unit vibrates and the deep pressure sensor captures the overall normal force exerted. The module is evaluated in two experiments. The first experiment compares the frequency content of the data collected in two setups: one when the module is mounted over a linear motion carriage that slides four grating patterns at constant velocities; the second when the module is carried by a robotic finger in contact with the same grating patterns while performing a sliding motion, similar to the exploratory motion employed by humans to detect object roughness. As expected, in the linear setup, the magnitude spectrum of the sensors’ output shows that the module can detect the applied stimuli with frequencies ranging from 3.66 Hz to 11.54 Hz with an overall maximum error of ±0.1 Hz. The second experiment shows how localized features extracted from the data collected by the robotic finger setup over seven synthetic shapes can be used to classify them. The classification method consists on applying multiscale principal components analysis prior to the classification with a multilayer neural network. Achieved accuracies from 85.1% to 98.9% for the various sensor types demonstrate the usefulness of traditional MEMS as tactile sensors embedded into flexible substrates. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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11 pages, 4278 KiB

Open AccessArticle

An Iterative Distortion Compensation Algorithm for Camera Calibration Based on Phase Target

by Yongjia Xu¹, Feng Gao^1,*

, Hongyu Ren¹, Zonghua Zhang²

and Xiangqian Jiang¹

¹ EPSRC Center, University of Huddersfield, Huddersfield HD1 3DH, UK

² School of Mechanical Engineering, Hebei University of Technology, Tianjin 300130, China

Sensors 2017, 17(6), 1188; https://doi.org/10.3390/s17061188 - 23 May 2017

Cited by 34 | Viewed by 7907

Abstract

Camera distortion is a critical factor affecting the accuracy of camera calibration. A conventional calibration approach cannot satisfy the requirement of a measurement system demanding high calibration accuracy due to the inaccurate distortion compensation. This paper presents a novel camera calibration method with [...] Read more.

Camera distortion is a critical factor affecting the accuracy of camera calibration. A conventional calibration approach cannot satisfy the requirement of a measurement system demanding high calibration accuracy due to the inaccurate distortion compensation. This paper presents a novel camera calibration method with an iterative distortion compensation algorithm. The initial parameters of the camera are calibrated by full-field camera pixels and the corresponding points on a phase target. An iterative algorithm is proposed to compensate for the distortion. A 2D fitting and interpolation method is also developed to enhance the accuracy of the phase target. Compared to the conventional calibration method, the proposed method does not rely on a distortion mathematical model, and is stable and effective in terms of complex distortion conditions. Both the simulation work and experimental results show that the proposed calibration method is more than 100% more accurate than the conventional calibration method. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 17071 KiB

Open AccessArticle

Atmospheric Sampling on Ascension Island Using Multirotor UAVs

by Colin Greatwood¹, Thomas S. Richardson^1,*, Jim Freer^2,3, Rick M. Thomas⁴, A. Rob MacKenzie⁴, Rebecca Brownlow⁵, David Lowry⁵, Rebecca E. Fisher⁵ and Euan G. Nisbet⁵

¹ Department of Aerospace Engineering, University of Bristol, Bristol BS8 1TR, UK

² School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK

³ Cabot Institute, University of Bristol, Bristol BS8 1SS, UK

⁴ School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK

⁵ Royal Holloway, University of London, Egham TW20 0EX, UK

Sensors 2017, 17(6), 1189; https://doi.org/10.3390/s17061189 - 23 May 2017

Cited by 33 | Viewed by 8319

Abstract

As part of an NERC-funded project investigating the southern methane anomaly, a team drawn from the Universities of Bristol, Birmingham and Royal Holloway flew small unmanned multirotors from Ascension Island for the purposes of atmospheric sampling. The objective of these flights was to [...] Read more.

As part of an NERC-funded project investigating the southern methane anomaly, a team drawn from the Universities of Bristol, Birmingham and Royal Holloway flew small unmanned multirotors from Ascension Island for the purposes of atmospheric sampling. The objective of these flights was to collect air samples from below, within and above a persistent atmospheric feature, the Trade Wind Inversion, in order to characterise methane concentrations and their isotopic composition. These parameters allow the methane in the different air masses to be tied to different source locations, which can be further analysed using back trajectory atmospheric computer modelling. This paper describes the campaigns as a whole including the design of the bespoke eight rotor aircraft and the operational requirements that were needed in order to collect targeted multiple air samples up to 2.5 km above the ground level in under 20 min of flight time. Key features of the system described include real-time feedback of temperature and humidity, as well as system health data. This enabled detailed targeting of the air sampling design to be realised and planned during the flight mission on the downward leg, a capability that is invaluable in the presence of uncertainty in the pre-flight meteorological data. Environmental considerations are also outlined together with the flight plans that were created in order to rapidly fly vertical transects of the atmosphere whilst encountering changing wind conditions. Two sampling campaigns were carried out in September 2014 and July 2015 with over one hundred high altitude sampling missions. Lessons learned are given throughout, including those associated with operating in the testing environment encountered on Ascension Island. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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15 pages, 3476 KiB

Open AccessArticle

Sensors and Actuators on Determining Parameters for Being Considered in Selection of Elastomers for Biomimetic Hands

by Vlad Cârlescu¹, Dumitru N. Olaru¹, Gheorghe Prisăcaru¹, Cezar Oprişan¹ and José Machado^2,*

¹ Department Mechanical Engineering, Mechatronics and Robotics, the “Gheorghe Asachi” Technical University of Iasi, Bulevardul Profesor Dimitrie Mangeron 67, 700050 Iași, Romania

² Mechanical Engineering Department, MEtRICs Research Center, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal

Sensors 2017, 17(6), 1190; https://doi.org/10.3390/s17061190 - 23 May 2017

Cited by 2 | Viewed by 4023

Abstract

In this paper, the authors present a new methodology to study the viscoelastic behaviour of the human finger. The methodology is based on experimental research consisting of a finger’s indentation with a small steel cylindrical object for various indentation speeds. The tests were [...] Read more.

In this paper, the authors present a new methodology to study the viscoelastic behaviour of the human finger. The methodology is based on experimental research consisting of a finger’s indentation with a small steel cylindrical object for various indentation speeds. The tests were realized on a CETR UMT-2 Tribometer for indentation speed between 0.02 mm/s and 4 mm/s with a normal load of up to 22 N. Using the force–deformation diagrams recorded at the smallest indentation speed determined the elastic modulus of the human finger according to an adapted Hertzian model. By considering the increasing of the indentation force with indentation speed, the viscous component of the human finger was evidenced. The power dissipated in the finger tissue as a result of the prehension process has been obtained as a function of indentation speed and indentation depth. In addition, a general equation for the prehension force as a function of indentation speed and indentation depth has been obtained. The results of this study will be relevant for selection of the specific elastomers used in biomimetic hands. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 2251 KiB

Open AccessArticle

Thermal Characterization of Dynamic Silicon Cantilever Array Sensors by Digital Holographic Microscopy

by Marjan Zakerin¹, Antonin Novak²

, Masaya Toda³, Yves Emery⁴, Filipe Natalio⁵, Hans-Jürgen Butt¹ and Rüdiger Berger^1,*

¹ Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

² Laboratoire d’Acoustique de l’Université du Maine (LAUM, UMR CNRS 6613), 72000 Le Mans, France

³ Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki-Aza-Aoba, Aoba-ku, 980-8579 Sendai, Japan

⁴ Lyncee Tec SA, PSE-A, CH-1015 Lausanne, Switzerland

⁵ Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Straße 2, 06120 Halle (Saale), Germany

Sensors 2017, 17(6), 1191; https://doi.org/10.3390/s17061191 - 23 May 2017

Cited by 7 | Viewed by 6590

Abstract

In this paper, we apply a digital holographic microscope (DHM) in conjunction with stroboscopic acquisition synchronization. Here, the temperature-dependent decrease of the first resonance frequency (S₁(T)) and Young’s elastic modulus (E₁(T)) of silicon [...] Read more.

In this paper, we apply a digital holographic microscope (DHM) in conjunction with stroboscopic acquisition synchronization. Here, the temperature-dependent decrease of the first resonance frequency (S₁(T)) and Young’s elastic modulus (E₁(T)) of silicon micromechanical cantilever sensors (MCSs) are measured. To perform these measurements, the MCSs are uniformly heated from T₀ = 298 K to T = 450 K while being externally actuated with a piezo-actuator in a certain frequency range close to their first resonance frequencies. At each temperature, the DHM records the time-sequence of the 3D topographies for the given frequency range. Such holographic data allow for the extracting of the out-of-plane vibrations at any relevant area of the MCSs. Next, the Bode and Nyquist diagrams are used to determine the resonant frequencies with a precision of 0.1 Hz. Our results show that the decrease of resonance frequency is a direct consequence of the reduction of the silicon elastic modulus upon heating. The measured temperature dependence of the Young’s modulus is in very good accordance with the previously-reported values, validating the reliability and applicability of this method for micromechanical sensing applications. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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10 pages, 5602 KiB

Open AccessArticle

A High-Sensitive Pressure Sensor Using a Single-Mode Fiber Embedded Microbubble with Thin Film Characteristics

by Guanjun Wang^1,2,3,†, Xinglin Liu^2,3,†, Zhiguo Gui², Yongquan An^2,3,*, Jinyu Gu^2,3, Meiqin Zhang^2,3, Lu Yan^2,3

, Gao Wang² and Zhibin Wang^2,3

¹ Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

² School of Information and Communication Engineering, North University of China, Taiyuan 030051, China

³ Engineering Technology Research Center of Shanxi Province for Opto-Electronic Information and Instrument, Taiyuan 030051, China

^† These two authors contributed equally to this work.

Sensors 2017, 17(6), 1192; https://doi.org/10.3390/s17061192 - 23 May 2017

Cited by 17 | Viewed by 6716

Abstract

A new fiber pressure sensor is proposed and analyzed in this paper. A commercial arc fusion splicer and pressure-assisted arc discharge technology are used here to fabricate a silica hollow microbubble from a common glass tube with the characteristics of a thin film. [...] Read more.

A new fiber pressure sensor is proposed and analyzed in this paper. A commercial arc fusion splicer and pressure-assisted arc discharge technology are used here to fabricate a silica hollow microbubble from a common glass tube with the characteristics of a thin film. Then the single mode fiber is embedded into the microbubble to form a fiber Fabry–Perot interferometer by measuring the reflected interference spectrum from the fiber tip and microbubble end. As the wall thickness of the micro-bubble can reach up to several micrometers, it can then be used for measuring the outer pressure with high sensitivity. The fabrication method has the merits of being simple, low in cost, and is easy to control. Experimental results show that its pressure sensitivity can reach 164.56 pm/kPa and the temperature sensitivity can reach 4 pm/°C. Therefore, it also has the advantage of being insensitive to temperature fluctuation. Full article

(This article belongs to the Special Issue Recent Advances in Fiber Bragg Grating Sensing)

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25 pages, 1130 KiB

Open AccessArticle

LoRa Scalability: A Simulation Model Based on Interference Measurements

by Jetmir Haxhibeqiri^*

, Floris Van den Abeele, Ingrid Moerman

and Jeroen Hoebeke

Department of Information Technology, Ghent University—imec, IDLab, Technologiepark-Zwijnaarde 15, B-9052 Ghent, Belgium

Sensors 2017, 17(6), 1193; https://doi.org/10.3390/s17061193 - 23 May 2017

Cited by 247 | Viewed by 17491

Abstract

LoRa is a long-range, low power, low bit rate and single-hop wireless communication technology. It is intended to be used in Internet of Things (IoT) applications involving battery-powered devices with low throughput requirements. A LoRaWAN network consists of multiple end nodes that communicate [...] Read more.

LoRa is a long-range, low power, low bit rate and single-hop wireless communication technology. It is intended to be used in Internet of Things (IoT) applications involving battery-powered devices with low throughput requirements. A LoRaWAN network consists of multiple end nodes that communicate with one or more gateways. These gateways act like a transparent bridge towards a common network server. The amount of end devices and their throughput requirements will have an impact on the performance of the LoRaWAN network. This study investigates the scalability in terms of the number of end devices per gateway of single-gateway LoRaWAN deployments. First, we determine the intra-technology interference behavior with two physical end nodes, by checking the impact of an interfering node on a transmitting node. Measurements show that even under concurrent transmission, one of the packets can be received under certain conditions. Based on these measurements, we create a simulation model for assessing the scalability of a single gateway LoRaWAN network. We show that when the number of nodes increases up to 1000 per gateway, the losses will be up to 32%. In such a case, pure Aloha will have around 90% losses. However, when the duty cycle of the application layer becomes lower than the allowed radio duty cycle of 1%, losses will be even lower. We also show network scalability simulation results for some IoT use cases based on real data. Full article

(This article belongs to the Section Sensor Networks)

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10 pages, 8898 KiB

Open AccessArticle

In-Process Atomic-Force Microscopy (AFM) Based Inspection

by Samir Mekid

Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia

Sensors 2017, 17(6), 1194; https://doi.org/10.3390/s17061194 - 31 May 2017

Cited by 3 | Viewed by 5743

Abstract

A new in-process atomic-force microscopy (AFM) based inspection is presented for nanolithography to compensate for any deviation such as instantaneous degradation of the lithography probe tip. Traditional method used the AFM probes for lithography work and retract to inspect the obtained feature but [...] Read more.

A new in-process atomic-force microscopy (AFM) based inspection is presented for nanolithography to compensate for any deviation such as instantaneous degradation of the lithography probe tip. Traditional method used the AFM probes for lithography work and retract to inspect the obtained feature but this practice degrades the probe tip shape and hence, affects the measurement quality. This paper suggests a second dedicated lithography probe that is positioned back-to-back to the AFM probe under two synchronized controllers to correct any deviation in the process compared to specifications. This method shows that the quality improvement of the nanomachining, in progress probe tip wear, and better understanding of nanomachining. The system is hosted in a recently developed nanomanipulator for educational and research purposes. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1329 KiB

Open AccessArticle

A Monitoring System for Laying Hens That Uses a Detection Sensor Based on Infrared Technology and Image Pattern Recognition

by Mauro Zaninelli^1,*

, Veronica Redaelli², Fabio Luzi³, Valentino Bontempo⁴, Vittorio Dell’Orto⁴ and Giovanni Savoini⁴

¹ Department of Human Sciences and Quality of Life Promotion, Università Telematica San Raffaele Roma, Via di Val Cannuta 247, Rome 00166, Italy

² Freelance Certified Infrared Thermal Technician, Oggiono (LC) 23848, Italy

³ Department of Veterinary Medicine, Università degli Studi di Milano, Via Celoria 10, Milan 20133, Italy

⁴ Department of Health, Animal Science and Food Safety (VESPA), Università degli Studi di Milano, Via Celoria 10, Milan 20133, Italy

Sensors 2017, 17(6), 1195; https://doi.org/10.3390/s17061195 - 24 May 2017

Cited by 25 | Viewed by 8813

Abstract

In Italy, organic egg production farms use free-range housing systems with a big outdoor area and a flock of no more than 500 hens. With additional devices and/or farming procedures, the whole flock could be forced to stay in the outdoor area for [...] Read more.

In Italy, organic egg production farms use free-range housing systems with a big outdoor area and a flock of no more than 500 hens. With additional devices and/or farming procedures, the whole flock could be forced to stay in the outdoor area for a limited time of the day. As a consequence, ozone treatments of housing areas could be performed in order to reduce the levels of atmospheric ammonia and bacterial load without risks, due by its toxicity, both for hens and workers. However, an automatic monitoring system, and a sensor able to detect the presence of animals, would be necessary. For this purpose, a first sensor was developed but some limits, related to the time necessary to detect a hen, were observed. In this study, significant improvements, for this sensor, are proposed. They were reached by an image pattern recognition technique that was applied to thermografic images acquired from the housing system. An experimental group of seven laying hens was selected for the tests, carried out for three weeks. The first week was used to set-up the sensor. Different templates, to use for the pattern recognition, were studied and different floor temperature shifts were investigated. At the end of these evaluations, a template of elliptical shape, and sizes of 135 × 63 pixels, was chosen. Furthermore, a temperature shift of one degree was selected to calculate, for each image, a color background threshold to apply in the following field tests. Obtained results showed an improvement of the sensor detection accuracy that reached values of sensitivity and specificity of 95.1% and 98.7%. In addition, the range of time necessary to detect a hen, or classify a case, was reduced at two seconds. This result could allow the sensor to control a bigger area of the housing system. Thus, the resulting monitoring system could allow to perform the sanitary treatments without risks both for animals and humans. Full article

(This article belongs to the Special Issue Infrared Detectors)

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10 pages, 3180 KiB

Open AccessArticle

Thermochemical Humidity Detection in Harsh or Non-Steady Environments

by Devon Bridgeman^1,2, Francis Tsow^1,2, Xiaojun Xian¹, Qinan Chang², Yongming Liu² and Erica Forzani^1,2,*

¹ Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA

² Fulton School of Engineering Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287, USA

Sensors 2017, 17(6), 1196; https://doi.org/10.3390/s17061196 - 24 May 2017

Cited by 3 | Viewed by 4671

Abstract

We present a new method of chemical quantification utilizing thermal analysis for the detection of relative humidity. By measuring the temperature change of a hydrophilically-modified temperature sensing element vs. a hydrophobically-modified reference element, the total heat from chemical interactions in the sensing element [...] Read more.

We present a new method of chemical quantification utilizing thermal analysis for the detection of relative humidity. By measuring the temperature change of a hydrophilically-modified temperature sensing element vs. a hydrophobically-modified reference element, the total heat from chemical interactions in the sensing element can be measured and used to calculate a change in relative humidity. We have probed the concept by assuming constant temperature streams, and having constant reference humidity (~0% in this case). The concept has been probed with the two methods presented here: (1) a thermistor-based method and (2) a thermographic method. For the first method, a hydrophilically-modified thermistor was used, and a detection range of 0–75% relative humidity was demonstrated. For the second method, a hydrophilically-modified disposable surface (sensing element) and thermal camera were used, and thermal signatures for different relative humidity were demonstrated. These new methods offer opportunities in either chemically harsh environments or in rapidly changing environments. For sensing humidity in a chemically harsh environment, a hydrophilically-modified thermistor can provide a sensing method, eliminating the exposure of metallic contacts, which can be easily corroded by the environment. On the other hand, the thermographic method can be applied with a disposable non-contact sensing element, which is a low-cost upkeep option in environments where damage or fouling is inevitable. In addition, for environments that are rapidly changing, the thermographic method could potentially provide a very rapid humidity measurement as the chemical interactions are rapid and their changes are easily quantified. Full article

(This article belongs to the Special Issue Humidity Sensors)

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22 pages, 1404 KiB

Open AccessReview

Human Thalamic Somatosensory Nucleus (Ventral Caudal, Vc) as a Locus for Stimulation by INPUTS from Tactile, Noxious and Thermal Sensors on an Active Prosthesis

by Jui Hong Chien¹, Anna Korzeniewska²

, Luana Colloca³, Claudia Campbell⁴, Patrick Dougherty⁵ and Frederick Lenz^1,*

¹ Department of Neurosurgery, Johns Hopkins University, Baltimore, MD 21287, USA

² Departments of Neurology and Cognitive Science, Johns Hopkins University, Baltimore, MD 21287, USA

³ Department of Pain Translational Symptom Science, School of Nursing, and Department of Anesthesiology, School of Medicine, University of Maryland, Baltimore, MD 20742, USA

⁴ Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD 21287, USA

⁵ Department of Anesthesiology and Critical Care Medicine, M.D. Anderson Hospital, Houston, TX 77054, USA

Sensors 2017, 17(6), 1197; https://doi.org/10.3390/s17061197 - 24 May 2017

Cited by 9 | Viewed by 6087

Abstract

The forebrain somatic sensory locus for input from sensors on the surface of an active prosthesis is an important component of the Brain Machine Interface. We now review the neuronal responses to controlled cutaneous stimuli and the sensations produced by Threshold Stimulation at [...] Read more.

The forebrain somatic sensory locus for input from sensors on the surface of an active prosthesis is an important component of the Brain Machine Interface. We now review the neuronal responses to controlled cutaneous stimuli and the sensations produced by Threshold Stimulation at Microampere current levels (TMIS) in such a locus, the human thalamic Ventral Caudal nucleus (Vc). The responses of these neurons to tactile stimuli mirror those for the corresponding class of tactile mechanoreceptor fiber in the peripheral nerve, and TMIS can evoke sensations like those produced by the stimuli that optimally activate each class. These neuronal responses show a somatotopic arrangement from lateral to medial in the sequence: leg, arm, face and intraoral structures. TMIS evoked sensations show a much more detailed organization into anterior posteriorly oriented rods, approximately 300 microns diameter, that represent smaller parts of the body, such as parts of individual digits. Neurons responding to painful and thermal stimuli are most dense around the posterior inferior border of Vc, and TMIS evoked pain sensations occur in one of two patterns: (i) pain evoked regardless of the frequency or number of spikes in a burst of TMIS; and (ii) the description and intensity of the sensation changes with increasing frequencies and numbers. In patients with major injuries leading to loss of somatic sensory input, TMIS often evokes sensations in the representation of parts of the body with loss of sensory input, e.g., the phantom after amputation. Some patients with these injuries have ongoing pain and pain evoked by TMIS of the representation in those parts of the body. Therefore, thalamic TMIS may produce useful patterned somatotopic feedback to the CNS from sensors on an active prosthesis that is sometimes complicated by TMIS evoked pain in the representation of those parts of the body. Full article

(This article belongs to the Special Issue Tactile Sensors and Sensing)

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17 pages, 3826 KiB

Open AccessArticle

Diazonium Salt-Based Surface-Enhanced Raman Spectroscopy Nanosensor: Detection and Quantitation of Aromatic Hydrocarbons in Water Samples

by Inga Tijunelyte¹, Stéphanie Betelu^2,*, Jonathan Moreau³, Ioannis Ignatiadis²

, Catherine Berho², Nathalie Lidgi-Guigui¹, Erwann Guénin⁴, Catalina David⁵, Sébastien Vergnole⁵, Emmanuel Rinnert³

and Marc Lamy de la Chapelle^1,*

¹ CSPBAT Laboratory, UMR 7244, UFR SMBH, University of Paris 13, Sorbonne Paris Cite, 93017 Bobigny, France

² BRGM, F-45060 Orléans CEDEX 02, France

³ IFREMER, Brittany Center, Detection, Sensors and Measurements Laboratory, CS10070, 29280 Plouzané, France

⁴ Laboratoire TIMR, EA4297, Sorbonne Universités—Université de Technologie de Compiègne, Centre de recherche de Royallieu, rue du docteur Schweitzer, CS 60319, 60203 Compiègne CEDEX, France

⁵ HORIBA Jobin Yvon SAS, 59650 Villeneuve d’Ascq, France

Sensors 2017, 17(6), 1198; https://doi.org/10.3390/s17061198 - 24 May 2017

Cited by 33 | Viewed by 8995

Abstract

Here, we present a surface-enhanced Raman spectroscopy (SERS) nanosensor for environmental pollutants detection. This study was conducted on three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BaP), fluoranthene (FL), and naphthalene (NAP). SERS substrates were chemically functionalized using 4-dodecyl benzenediazonium-tetrafluoroborate and SERS analyses were conducted [...] Read more.

Here, we present a surface-enhanced Raman spectroscopy (SERS) nanosensor for environmental pollutants detection. This study was conducted on three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BaP), fluoranthene (FL), and naphthalene (NAP). SERS substrates were chemically functionalized using 4-dodecyl benzenediazonium-tetrafluoroborate and SERS analyses were conducted to detect the pollutants alone and in mixtures. Compounds were first measured in water-methanol (9:1 volume ratio) samples. Investigation on solutions containing concentrations ranging from 10⁻⁶ g L⁻¹ to 10⁻³ g L⁻¹ provided data to plot calibration curves and to determine the performance of the sensor. The calculated limit of detection (LOD) was 0.026 mg L⁻¹ (10⁻⁷ mol L⁻¹) for BaP, 0.064 mg L⁻¹ (3.2 × 10⁻⁷ mol L⁻¹) for FL, and 3.94 mg L⁻¹ (3.1 × 10⁻⁵ mol L⁻¹) for NAP, respectively. The correlation between the calculated LOD values and the octanol-water partition coefficient (K_ow) of the investigated PAHs suggests that the developed nanosensor is particularly suitable for detecting highly non-polar PAH compounds. Measurements conducted on a mixture of the three analytes (i) demonstrated the ability of the developed technology to detect and identify the three analytes in the mixture; (ii) provided the exact quantitation of pollutants in a mixture. Moreover, we optimized the surface regeneration step for the nanosensor. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in France 2016)

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11 pages, 2304 KiB

Open AccessArticle

A Simple Drain Current Model for MOS Transistors with the Lorentz Force Effect

by Hwang-Cherng Chow^*, Prasenjit Chatterjee^* and Wu-Shiung Feng

Graduate Institute of Electronic Engineering, Chang Gung University, 259 Wenhwa 1st Road, Kweishan, Taoyuan 333, Taiwan

Sensors 2017, 17(6), 1199; https://doi.org/10.3390/s17061199 - 24 May 2017

Cited by 6 | Viewed by 4268

Abstract

A novel concept of drain current modelling in rectangular normal MOS transistors with the Lorentz force has been proposed for the first time. The single-drain MOS transistor is qualified as a magnetic sensor. To create the Lorentz force, a DC loop current is [...] Read more.

A novel concept of drain current modelling in rectangular normal MOS transistors with the Lorentz force has been proposed for the first time. The single-drain MOS transistor is qualified as a magnetic sensor. To create the Lorentz force, a DC loop current is applied through an on-chip metal loop around the device, and the relation between the applied loop current and the created magnetic field is assumed to be linear in nature. The drain current of the MOS transistor is reduced with the applied Lorentz force from both directions. This change in the drain current is ascribed to a change in mobility in the strong inversion region, and a change in mobility of around 4.45% is observed. To model this change, a set of novel drain current equations, under the Lorentz force, for the strong inversion region has been proposed. A satisfactory agreement of an average error of less than 2% between the measured and the calculated drain currents under the magnetic field created by an on-chip metal loop is achieved. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 6260 KiB

Open AccessArticle

Biomechanical Modeling of Pterygium Radiation Surgery: A Retrospective Case Study

by Bojan Pajic^1,2,3,4

, Daniel M. Aebersold⁵, Andreas Eggspuehler⁶, Frederik R. Theler⁷ and Harald P. Studer^1,8,*

¹ Eye Clinic Orasis, Swiss Eye Research Foundation, CH-5734 Reinach, Switzerland

² Department of Physics, Faculty of Sciences, University of Novi Sad, 21000 Novi Sad, Serbia

³ Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, CH-1205 Geneva, Switzerland

⁴ Faculty of Medicine of the Military Medical Academy, University of Defence, 11000 Belgrade, Serbia

⁵ Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland

⁶ Department of Neurology, Schulthess Klinik, CH-8008 Zuerich, Switzerland

⁷ Optimo Medical, CH-2503 Biel, Switzerland

⁸ OCTlab, Department of Ophthalmology, University of Basel, CH-4001 Basel, Switzerland

Sensors 2017, 17(6), 1200; https://doi.org/10.3390/s17061200 - 24 May 2017

Cited by 3 | Viewed by 4170

Abstract

Pterygium is a vascularized, invasive transformation on the anterior corneal surface that can be treated by Strontium-/Yttrium90 beta irradiation. Finite element modeling was used to analyze the biomechanical effects governing the treatment, and to help understand clinically observed changes in corneal astigmatism. Results [...] Read more.

Pterygium is a vascularized, invasive transformation on the anterior corneal surface that can be treated by Strontium-/Yttrium90 beta irradiation. Finite element modeling was used to analyze the biomechanical effects governing the treatment, and to help understand clinically observed changes in corneal astigmatism. Results suggested that irradiation-induced pulling forces on the anterior corneal surface can cause astigmatism, as well as central corneal flattening. Finite element modeling of corneal biomechanics closely predicted the postoperative corneal surface (astigmatism error −0.01D; central curvature error −0.16D), and can help in understanding beta irradiation treatment. Numerical simulations have the potential to preoperatively predict corneal shape and function changes, and help to improve corneal treatments. Full article

(This article belongs to the Special Issue Optical Methods in Sensing and Imaging for Medical and Biological Applications)

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10 pages, 1162 KiB

Open AccessArticle

The Effects of Dithiothreitol on DNA

by Søren Fjelstrup^1,2, Marie Bech Andersen¹, Jonas Thomsen¹, Jing Wang¹, Magnus Stougaard³, Finn Skou Pedersen^1,2, Yi-Ping Ho^1,2,4

, Marianne Smedegaard Hede^5,* and Birgitta Ruth Knudsen^1,2,*

¹ Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark

² Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus, Denmark

³ Department of Pathology, Aarhus University Hospital, 8000 Aarhus, Denmark

⁴ Division of Biomedical Engineering, Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China

⁵ Zymonostics ApS, 8000 Aarhus, Denmark

Sensors 2017, 17(6), 1201; https://doi.org/10.3390/s17061201 - 24 May 2017

Cited by 19 | Viewed by 9145

Abstract

With the novel possibilities for detecting molecules of interest with extreme sensitivity also comes the risk of encountering hitherto negligible sources of error. In life science, such sources of error might be the broad variety of additives such as dithiothreitol (DTT) used to [...] Read more.

With the novel possibilities for detecting molecules of interest with extreme sensitivity also comes the risk of encountering hitherto negligible sources of error. In life science, such sources of error might be the broad variety of additives such as dithiothreitol (DTT) used to preserve enzyme stability during in vitro reactions. Using two different assays that can sense strand interruptions in double stranded DNA, we here show that DTT is able to introduce nicks in the DNA backbone. DTT was furthermore shown to facilitate the immobilization of fluorescent DNA on an NHS-ester functionalized glass surface. Such reactions may in particular impact the readout from single molecule detection studies and other ultrasensitive assays. This was highlighted by the finding that DTT markedly decreased the signal to noise ratio in a DNA sensor based assay with single molecule resolution. Full article

(This article belongs to the Special Issue Genosensing)

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23 pages, 3387 KiB

Open AccessArticle

The Effect of Leaf Stacking on Leaf Reflectance and Vegetation Indices Measured by Contact Probe during the Season

by Eva Neuwirthová¹, Zuzana Lhotáková¹

and Jana Albrechtová^1,2,*

¹ Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Vinicna 5, 128 44 Prague 2, Czech Republic

² Institute of Botany, Academy of Sciences, Zámek 1, 252 43 Pruhonice, Czech Republic

Sensors 2017, 17(6), 1202; https://doi.org/10.3390/s17061202 - 24 May 2017

Cited by 23 | Viewed by 6823

Abstract

The aims of the study were: (i) to compare leaf reflectance in visible (VIS) (400–700 nm), near-infrared (NIR) (740–1140 nm) and short-wave infrared (SWIR) (2000–2400 nm) spectral ranges measured monthly by a contact probe on a single leaf and a stack of five [...] Read more.

The aims of the study were: (i) to compare leaf reflectance in visible (VIS) (400–700 nm), near-infrared (NIR) (740–1140 nm) and short-wave infrared (SWIR) (2000–2400 nm) spectral ranges measured monthly by a contact probe on a single leaf and a stack of five leaves (measurement setup (MS)) of two broadleaved tree species during the vegetative season; and (ii) to test if and how selected vegetation indices differ under these two MS. In VIS, the pigment-related spectral region, the effect of MS on reflectance was negligible. The major influence of MS on reflectance was detected in NIR (up to 25%), the structure-related spectral range; and weaker effect in SWIR, the water-related spectral range. Vegetation indices involving VIS wavelengths were independent of MS while indices combining wavelengths from both VIS and NIR were MS-affected throughout the season. The effect of leaf stacking contributed to weakening the correlation between the leaf chlorophyll content and selected vegetation indices due to a higher leaf mass per area of the leaf sample. The majority of MS-affected indices were better correlated with chlorophyll content in both species in comparison with MS-unaffected indices. Therefore, in terms of monitoring leaf chlorophyll content using the contact probe reflectance measurement, these MS-affected indices should be used with caution, as discussed in the paper. If the vegetation indices are used for assessment of plant physiological status in various times of the vegetative season, then it is essential to take into consideration their possible changes induced by the particular contact probe measurement setup regarding the leaf stacking. Full article

(This article belongs to the Section Remote Sensors)

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9 pages, 9494 KiB

Open AccessArticle

Amorphous In–Ga–Zn–O Powder with High Gas Selectivity towards Wide Range Concentration of C₂H₅OH

by Hongxiang Chen, Wei Jiang, Lianfeng Zhu and Youwei Yao^*

Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China

Sensors 2017, 17(6), 1203; https://doi.org/10.3390/s17061203 - 24 May 2017

Cited by 14 | Viewed by 5358

Abstract

Amorphous indium gallium zinc oxide (a-IGZO) powder was prepared by typical solution-based process and post-annealing process. The sample was used as sensor for detecting C₂H₅OH, H₂, and CO. Gas-sensing performance was found to be highly sensitive to [...] Read more.

Amorphous indium gallium zinc oxide (a-IGZO) powder was prepared by typical solution-based process and post-annealing process. The sample was used as sensor for detecting C₂H₅OH, H₂, and CO. Gas-sensing performance was found to be highly sensitive to C₂H₅OH gas in a wide range of concentration (0.5–1250 ppm) with the response of 2.0 towards 0.5 ppm and 89.2 towards 1250 ppm. Obvious difference of response towards C₂H₅OH, H₂, and CO was found that the response e.g., was 33.20, 6.64, and 2.84 respectively at the concentration of 200 ppm. The response time and recovery time of was 32 s and 14 s respectively towards 200 ppm concentration of C₂H₅OH gas under heating voltage of 6.5 V. Full article

(This article belongs to the Section Chemical Sensors)

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15 pages, 3208 KiB

Open AccessArticle

A New Calibration Method for Commercial RGB-D Sensors

by Walid Darwish¹, Shenjun Tang^1,2,3, Wenbin Li¹ and Wu Chen^1,*

¹ Department of Land Surveying & Geo-Informatics, The Hong Kong Polytechnic University, Hung Hom 999077, Hong Kong, China

² State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

³ Shenzhen Key Laboratory of Spatial Smart Sensing and Services & The Key Laboratory for Geo-Environment Monitoring of Coastal Zone of the National Administration of Surveying, Mapping and GeoInformation, Shenzhen University, Shenzhen 518060, China

Sensors 2017, 17(6), 1204; https://doi.org/10.3390/s17061204 - 24 May 2017

Cited by 38 | Viewed by 9296

Abstract

Commercial RGB-D sensors such as Kinect and Structure Sensors have been widely used in the game industry, where geometric fidelity is not of utmost importance. For applications in which high quality 3D is required, i.e., 3D building models of centimeter‑level accuracy, accurate and [...] Read more.

Commercial RGB-D sensors such as Kinect and Structure Sensors have been widely used in the game industry, where geometric fidelity is not of utmost importance. For applications in which high quality 3D is required, i.e., 3D building models of centimeter‑level accuracy, accurate and reliable calibrations of these sensors are required. This paper presents a new model for calibrating the depth measurements of RGB-D sensors based on the structured light concept. Additionally, a new automatic method is proposed for the calibration of all RGB-D parameters, including internal calibration parameters for all cameras, the baseline between the infrared and RGB cameras, and the depth error model. When compared with traditional calibration methods, this new model shows a significant improvement in depth precision for both near and far ranges. Full article

(This article belongs to the Special Issue Indoor LiDAR/Vision Systems)

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15 pages, 42171 KiB

Open AccessArticle

Evaluation and Comparison of the Processing Methods of Airborne Gravimetry Concerning the Errors Effects on Downward Continuation Results: Case Studies in Louisiana (USA) and the Tibetan Plateau (China)

by Qilong Zhao^1,2,3,*, Gabriel Strykowski², Jiancheng Li^1,3, Xiong Pan⁴ and Xinyu Xu^1,3

¹ School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China

² National Space Institute, Technical University of Denmark, Copenhagen Ø 2800, Denmark

³ Key Laboratory of Geospace Environment and Geodesy of Ministry of Education, Wuhan University, Wuhan 430079, China

⁴ Faculty of Information Engineering, China University of Geosciences, Wuhan 430074, China

Sensors 2017, 17(6), 1205; https://doi.org/10.3390/s17061205 - 25 May 2017

Cited by 5 | Viewed by 3951

Abstract

Gravity data gaps in mountainous areas are nowadays often filled in with the data from airborne gravity surveys. Because of the errors caused by the airborne gravimeter sensors, and because of rough flight conditions, such errors cannot be completely eliminated. The precision of [...] Read more.

Gravity data gaps in mountainous areas are nowadays often filled in with the data from airborne gravity surveys. Because of the errors caused by the airborne gravimeter sensors, and because of rough flight conditions, such errors cannot be completely eliminated. The precision of the gravity disturbances generated by the airborne gravimetry is around 3–5 mgal. A major obstacle in using airborne gravimetry are the errors caused by the downward continuation. In order to improve the results the external high-accuracy gravity information e.g., from the surface data can be used for high frequency correction, while satellite information can be applying for low frequency correction. Surface data may be used to reduce the systematic errors, while regularization methods can reduce the random errors in downward continuation. Airborne gravity surveys are sometimes conducted in mountainous areas and the most extreme area of the world for this type of survey is the Tibetan Plateau. Since there are no high-accuracy surface gravity data available for this area, the above error minimization method involving the external gravity data cannot be used. We propose a semi-parametric downward continuation method in combination with regularization to suppress the systematic error effect and the random error effect in the Tibetan Plateau; i.e., without the use of the external high-accuracy gravity data. We use a Louisiana airborne gravity dataset from the USA National Oceanic and Atmospheric Administration (NOAA) to demonstrate that the new method works effectively. Furthermore, and for the Tibetan Plateau we show that the numerical experiment is also successfully conducted using the synthetic Earth Gravitational Model 2008 (EGM08)-derived gravity data contaminated with the synthetic errors. The estimated systematic errors generated by the method are close to the simulated values. In addition, we study the relationship between the downward continuation altitudes and the error effect. The analysis results show that the proposed semi-parametric method combined with regularization is efficient to address such modelling problems. Full article

(This article belongs to the Section Remote Sensors)

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21 pages, 1412 KiB

Open AccessArticle

A Novel Complex-Coefficient In-Band Interference Suppression Algorithm for Cognitive Ultra-Wide Band Wireless Sensors Networks

by Hailiang Xiong^1,*, Wensheng Zhang^1,*, Hongji Xu¹, Zhengfeng Du¹, Huaibin Tang² and Jing Li³

¹ School of Information Science and Engineering, Shandong University, Jinan 250100, China

² School of Microelectronics, Shandong University, Jinan 250100, China

³ Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China

Sensors 2017, 17(6), 1206; https://doi.org/10.3390/s17061206 - 25 May 2017

Cited by 6 | Viewed by 4729

Abstract

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been [...] Read more.

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been considered as significant solutions to solve the harmonious coexistence issues. UWB wireless sensors can share the spectrum with primary user (PU) systems without harmful interference. The in-band interference of UWB systems should be considered because such interference can severely affect the transmissions of UWB wireless systems. In order to solve the in-band interference issues for UWB wireless sensor networks (WSN), a novel in-band narrow band interferences (NBIs) elimination scheme is proposed in this paper. The proposed narrow band interferences suppression scheme is based on a novel complex-coefficient adaptive notch filter unit with a single constrained zero-pole pair. Moreover, in order to reduce the computation complexity of the proposed scheme, an adaptive complex-coefficient iterative method based on two-order Taylor series is designed. To cope with multiple narrow band interferences, a linear cascaded high order adaptive filter and a cyclic cascaded high order matrix adaptive filter (CCHOMAF) interference suppression algorithm based on the basic adaptive notch filter unit are also presented. The theoretical analysis and numerical simulation results indicate that the proposed CCHOMAF algorithm can achieve better performance in terms of average bit error rate for UWB WSNs. The proposed in-band NBIs elimination scheme can significantly improve the reception performance of low-cost and low-power UWB wireless systems. Full article

(This article belongs to the Section Sensor Networks)

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21 pages, 5106 KiB

Open AccessArticle

Traffic Sign Detection System for Locating Road Intersections and Roundabouts: The Chilean Case

by Gabriel Villalón-Sepúlveda¹, Miguel Torres-Torriti¹ and Marco Flores-Calero^2,3,*

¹ Departamento de Ingeniería Eléctrica, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Casilla 306-22, Santiago, Chile

² Departamento de Eléctrica y Electrónica, Universidad de las Fuerzas Armadas-ESPE, Av. Gral. Rumiñahui s/n, PBX 171-5-231B Sangolquí, Pichincha, Ecuador

³ Departamento de Sistemas Inteligentes, Tecnologías I&H, CP 050102, Latacunga, Cotopaxi, Ecuador

Sensors 2017, 17(6), 1207; https://doi.org/10.3390/s17061207 - 25 May 2017

Cited by 12 | Viewed by 9958

Abstract

This paper presents a traffic sign detection method for signs close to road intersections and roundabouts, such as stop and yield (give way) signs. The proposed method relies on statistical templates built using color information for both segmentation and classification. The segmentation method [...] Read more.

This paper presents a traffic sign detection method for signs close to road intersections and roundabouts, such as stop and yield (give way) signs. The proposed method relies on statistical templates built using color information for both segmentation and classification. The segmentation method uses the RGB-normalized (ErEgEb) color space for ROIs (Regions of Interest) generation based on a chromaticity filter, where templates at 10 scales are applied to the entire image. Templates consider the mean and standard deviation of normalized color of the traffic signs to build thresholding intervals where the expected color should lie for a given sign. The classification stage employs the information of the statistical templates over YCbCr and ErEgEb color spaces, for which the background has been previously removed by using a probability function that models the probability that the pixel corresponds to a sign given its chromaticity values. This work includes an analysis of the detection rate as a function of the distance between the vehicle and the sign. Such information is useful to validate the robustness of the approach and is often not included in the existing literature. The detection rates, as a function of distance, are compared to those of the well-known Viola–Jones method. The results show that for distances less than 48 m, the proposed method achieves a detection rate of

87.5 %

and

95.4 %

for yield and stop signs, respectively. For distances less than 30 m, the detection rate is

100 %

for both signs. The Viola–Jones approach has detection rates below

20 %

for distances between 30 and 48 m, and barely improves in the 20–30 m range with detection rates of up to

60 %

. Thus, the proposed method provides a robust alternative for intersection detection that relies on statistical color-based templates instead of shape information. The experiments employed videos of traffic signs taken in several streets of Santiago, Chile, using a research platform implemented at the Robotics and Automation Laboratory of PUC to develop driver assistance systems. Full article

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

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18 pages, 1159 KiB

Open AccessArticle

A Max-Flow Based Algorithm for Connected Target Coverage with Probabilistic Sensors

by Anxing Shan¹, Xianghua Xu^1,*, Zongmao Cheng² and Wensheng Wang³

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

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

³ College of Economics, Hangzhou Dianzi University, Hangzhou 310018, China

Sensors 2017, 17(6), 1208; https://doi.org/10.3390/s17061208 - 25 May 2017

Cited by 10 | Viewed by 3748

Abstract

Coverage is a fundamental issue in the research field of wireless sensor networks (WSNs). Connected target coverage discusses the sensor placement to guarantee the needs of both coverage and connectivity. Existing works largely leverage on the Boolean disk model, which is only a [...] Read more.

Coverage is a fundamental issue in the research field of wireless sensor networks (WSNs). Connected target coverage discusses the sensor placement to guarantee the needs of both coverage and connectivity. Existing works largely leverage on the Boolean disk model, which is only a coarse approximation to the practical sensing model. In this paper, we focus on the connected target coverage issue based on the probabilistic sensing model, which can characterize the quality of coverage more accurately. In the probabilistic sensing model, sensors are only be able to detect a target with certain probability. We study the collaborative detection probability of target under multiple sensors. Armed with the analysis of collaborative detection probability, we further formulate the minimum ϵ-connected target coverage problem, aiming to minimize the number of sensors satisfying the requirements of both coverage and connectivity. We map it into a flow graph and present an approximation algorithm called the minimum vertices maximum flow algorithm (MVMFA) with provable time complex and approximation ratios. To evaluate our design, we analyze the performance of MVMFA theoretically and also conduct extensive simulation studies to demonstrate the effectiveness of our proposed algorithm. Full article

(This article belongs to the Section Sensor Networks)

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12 pages, 5191 KiB

Open AccessArticle

Amorphous SiC/c-ZnO-Based Quasi-Lamb Mode Sensor for Liquid Environments

by Cinzia Caliendo^1,*

, Muhammad Hamidullah¹

and Farouk Laidoudi²

¹ Institute of Photonics and Nanotechnologies, IFN-CNR, Via Cineto Romano 42, 00156 Rome, Italy

² Research Center in Industrial Technologies CRTI, ex-CSC, P.O. Box 64, Cheraga, 16014 Algiers, Algeria

Sensors 2017, 17(6), 1209; https://doi.org/10.3390/s17061209 - 25 May 2017

Cited by 9 | Viewed by 4788

Abstract

The propagation of the quasi-Lamb modes along a-SiC/ZnO thin composite plates was modeled and analysed with the aim to design a sensor able to detect the changes in parameters of a liquid environment, such as added mass and viscosity changes. The modes propagation [...] Read more.

The propagation of the quasi-Lamb modes along a-SiC/ZnO thin composite plates was modeled and analysed with the aim to design a sensor able to detect the changes in parameters of a liquid environment, such as added mass and viscosity changes. The modes propagation was modeled by numerically solving the system of coupled electro-mechanical field equations in three media. The mode shape, the power flow, the phase velocity, and the electroacoustic coupling efficiency (K²) of the modes were calculated, specifically addressing the design of enhanced-coupling, microwave frequency sensors for applications in probing the solid/liquid interface. Three modes were identified that have predominant longitudinal polarization, high phase velocity, and quite good K²: the fundamental quasi symmetric mode (qS₀) and two higher order quasi-longitudinal modes (qL₁ and qL₂) with a dominantly longitudinal displacement component in one plate side. The velocity and attenuation of these modes were calculated for different liquid viscosities and added mass, and the gravimetric and viscosity sensitivities of both the phase velocity and attenuation were theoretically calculated. The present study highlights the feasibility of the a-SiC/ZnO acoustic waveguides for the development of high-frequency, integrated-circuit compatible electroacoustic devices suitable for working in a liquid environment. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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16 pages, 8137 KiB

Open AccessArticle

Mapping Winter Wheat with Multi-Temporal SAR and Optical Images in an Urban Agricultural Region

by Tao Zhou¹

, Jianjun Pan^1,*, Peiyu Zhang¹, Shanbao Wei² and Tao Han¹

¹ College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China

² College of Public Administration, Nanjing Agricultural University, Nanjing 210095, China

Sensors 2017, 17(6), 1210; https://doi.org/10.3390/s17061210 - 25 May 2017

Cited by 101 | Viewed by 7543

Abstract

Winter wheat is the second largest food crop in China. It is important to obtain reliable winter wheat acreage to guarantee the food security for the most populous country in the world. This paper focuses on assessing the feasibility of in-season winter wheat [...] Read more.

Winter wheat is the second largest food crop in China. It is important to obtain reliable winter wheat acreage to guarantee the food security for the most populous country in the world. This paper focuses on assessing the feasibility of in-season winter wheat mapping and investigating potential classification improvement by using SAR (Synthetic Aperture Radar) images, optical images, and the integration of both types of data in urban agricultural regions with complex planting structures in Southern China. Both SAR (Sentinel-1A) and optical (Landsat-8) data were acquired, and classification using different combinations of Sentinel-1A-derived information and optical images was performed using a support vector machine (SVM) and a random forest (RF) method. The interference coherence and texture images were obtained and used to assess the effect of adding them to the backscatter intensity images on the classification accuracy. The results showed that the use of four Sentinel-1A images acquired before the jointing period of winter wheat can provide satisfactory winter wheat classification accuracy, with an F1 measure of 87.89%. The combination of SAR and optical images for winter wheat mapping achieved the best F1 measure–up to 98.06%. The SVM was superior to RF in terms of the overall accuracy and the kappa coefficient, and was faster than RF, while the RF classifier was slightly better than SVM in terms of the F1 measure. In addition, the classification accuracy can be effectively improved by adding the texture and coherence images to the backscatter intensity data. Full article

(This article belongs to the Special Issue Recent Innovative Microwave Remote Sensing Instrumentation for Land Surface Applications)

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9 pages, 1735 KiB

Open AccessArticle

Excimer Laser Surgery: Biometrical Iris Eye Recognition with Cyclorotational Control Eye Tracker System

by Bojan Pajic^1,2,3,4

, Zeljka Cvejic², Zoran Mijatovic^2,*, Dragan Indjin⁵ and Joerg Mueller¹

¹ Swiss Eye Research Foundation, Eye Clinic ORASIS, 5734 Reinach AG, Switzerland

² Faculty of Sciences, Department of Physics, University of Novi Sad, Trg Dositeja Obradovica 4, Novi Sad 21000, Serbia

³ Medical Faculty, Military Medical Academy, University of Defans Belgrade, Belgrade 11000, Serbia

⁴ Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, Genève 1205, Switzerland

⁵ School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK

Sensors 2017, 17(6), 1211; https://doi.org/10.3390/s17061211 - 25 May 2017

Cited by 6 | Viewed by 5171

Abstract

A prospective comparative study assessing the importance of the intra-operative dynamic rotational tracking—especially in the treatment of astigmatisms in corneal refractive Excimer laser correction—concerning clinical outcomes is presented. The cyclotorsion from upright to supine position was measured using iris image comparison. The Group [...] Read more.

A prospective comparative study assessing the importance of the intra-operative dynamic rotational tracking—especially in the treatment of astigmatisms in corneal refractive Excimer laser correction—concerning clinical outcomes is presented. The cyclotorsion from upright to supine position was measured using iris image comparison. The Group 1 of patients was additionally treated with cyclorotational control and Group 2 only with X-Y control. Significant differences were observed between the groups regarding the mean postoperative cylinder refraction (p < 0.05). The mean cyclotorsion can be calculated to 3.75° with a standard deviation of 3.1°. The total range of torsion was from −14.9° to +12.6°. Re-treatment rate was 2.2% in Group 1 and 8.2% in Group 2, which is highly significant (p < 0.01). The investigation confirms that the dynamic rotational tracking system used for LASIK results in highly predictable refraction quality with significantly less postoperative re-treatments. Full article

(This article belongs to the Special Issue Optical Methods in Sensing and Imaging for Medical and Biological Applications)

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11 pages, 1553 KiB

Open AccessArticle

Automatic Detection of Driver Fatigue Using Driving Operation Information for Transportation Safety

by Zuojin Li^*, Liukui Chen, Jun Peng and Ying Wu^*

College of Electrical and Information Engineering, Chongqing University of Science and Technology, Chongqing 401331, China

Sensors 2017, 17(6), 1212; https://doi.org/10.3390/s17061212 - 25 May 2017

Cited by 95 | Viewed by 8554

Abstract

Fatigued driving is a major cause of road accidents. For this reason, the method in this paper is based on the steering wheel angles (SWA) and yaw angles (YA) information under real driving conditions to detect drivers’ fatigue levels. It analyzes the operation [...] Read more.

Fatigued driving is a major cause of road accidents. For this reason, the method in this paper is based on the steering wheel angles (SWA) and yaw angles (YA) information under real driving conditions to detect drivers’ fatigue levels. It analyzes the operation features of SWA and YA under different fatigue statuses, then calculates the approximate entropy (ApEn) features of a short sliding window on time series. Using the nonlinear feature construction theory of dynamic time series, with the fatigue features as input, designs a “2-6-6-3” multi-level back propagation (BP) Neural Networks classifier to realize the fatigue detection. An approximately 15-h experiment is carried out on a real road, and the data retrieved are segmented and labeled with three fatigue levels after expert evaluation, namely “awake”, “drowsy” and “very drowsy”. The average accuracy of 88.02% in fatigue identification was achieved in the experiment, endorsing the value of the proposed method for engineering applications. Full article

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

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16 pages, 5487 KiB

Open AccessArticle

LOCALI: Calibration-Free Systematic Localization Approach for Indoor Positioning

by Muhammad Usman Ali, Soojung Hur and Yongwan Park^*

Department of Information and Communication Engineering, Yeungnam University, Gyeongsan 38541, Korea

Sensors 2017, 17(6), 1213; https://doi.org/10.3390/s17061213 - 25 May 2017

Cited by 34 | Viewed by 6037

Abstract

Recent advancements in indoor positioning systems are based on infrastructure-free solutions, aimed at improving the location accuracy in complex indoor environments without the use of specialized resources. A popular infrastructure-free solution for indoor positioning is a calibration-based positioning, commonly known as fingerprinting. Fingerprinting [...] Read more.

Recent advancements in indoor positioning systems are based on infrastructure-free solutions, aimed at improving the location accuracy in complex indoor environments without the use of specialized resources. A popular infrastructure-free solution for indoor positioning is a calibration-based positioning, commonly known as fingerprinting. Fingerprinting solutions require extensive and error-free surveys of environments to build radio-map databases, which play a key role in position estimation. Fingerprinting also requires random updates of the database, when there are significant changes in the environment or a decrease in the accuracy. The calibration of the fingerprinting database is a time-consuming and laborious effort that prevents the extensive adoption of this technique. In this paper, we present a systematic LOCALIzation approach, “LOCALI”, for indoor positioning, which does not require a calibration database and extensive updates. The LOCALI exploits the floor plan/wall map of the environment to estimate the target position by generating radio maps by integrating path-losses over certain trajectories in complex indoor environments, where triangulation using time information or the received signal strength level is highly erroneous due to the fading effects caused by multi-path propagation or absorption by environmental elements or varying antenna alignment. Experimental results demonstrate that by using the map information and environmental parameters, a significant level of accuracy in indoor positioning can be achieved. Moreover, this process requires considerably lesser effort compared to the calibration-based techniques. Full article

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

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23 pages, 8940 KiB

Open AccessArticle

DeepMap+: Recognizing High-Level Indoor Semantics Using Virtual Features and Samples Based on a Multi-Length Window Framework

by Wei Zhang^†

and Siwang Zhou^*,†

¹ College of Computer Science and Electronic Engineering, Hunan University, Changsha 410000, China

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1214; https://doi.org/10.3390/s17061214 - 26 May 2017

Cited by 2 | Viewed by 3679

Abstract

Existing indoor semantic recognition schemes are mostly capable of discovering patterns through smartphone sensing, but it is hard to recognize rich enough high-level indoor semantics for map enhancement. In this work we present DeepMap+, an automatical inference system for recognizing high-level indoor semantics [...] Read more.

Existing indoor semantic recognition schemes are mostly capable of discovering patterns through smartphone sensing, but it is hard to recognize rich enough high-level indoor semantics for map enhancement. In this work we present DeepMap+, an automatical inference system for recognizing high-level indoor semantics using complex human activities with wrist-worn sensing. DeepMap+ is the first deep computation system using deep learning (DL) based on a multi-length window framework to enrich the data source. Furthermore, we propose novel methods of increasing virtual features and virtual samples for DeepMap+ to better discover hidden patterns of complex hand gestures. We have performed 23 high-level indoor semantics (including public facilities and functional zones) and collected wrist-worn data at a Wal-Mart supermarket. The experimental results show that our proposed methods can effectively improve the classification accuracy. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 2273 KiB

Open AccessArticle

Internal Model-Based Robust Tracking Control Design for the MEMS Electromagnetic Micromirror

by Jiazheng Tan¹, Weijie Sun¹ and John T. W. Yeow^2,*

¹ College of Automation Science and Engineering, South China University of Technology, Guangzhou 510000, China

² Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada

Sensors 2017, 17(6), 1215; https://doi.org/10.3390/s17061215 - 26 May 2017

Cited by 24 | Viewed by 4809

Abstract

The micromirror based on micro-electro-mechanical systems (MEMS) technology is widely employed in different areas, such as scanning, imaging and optical switching. This paper studies the MEMS electromagnetic micromirror for scanning or imaging application. In these application scenarios, the micromirror is required to track [...] Read more.

The micromirror based on micro-electro-mechanical systems (MEMS) technology is widely employed in different areas, such as scanning, imaging and optical switching. This paper studies the MEMS electromagnetic micromirror for scanning or imaging application. In these application scenarios, the micromirror is required to track the command sinusoidal signal, which can be converted to an output regulation problem theoretically. In this paper, based on the internal model principle, the output regulation problem is solved by designing a robust controller that is able to force the micromirror to track the command signal accurately. The proposed controller relies little on the accuracy of the model. Further, the proposed controller is implemented, and its effectiveness is examined by experiments. The experimental results demonstrate that the performance of the proposed controller is satisfying. Full article

(This article belongs to the Section Physical Sensors)

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31 pages, 1413 KiB

Open AccessArticle

LEM Characterization of Synthetic Jet Actuators Driven by Piezoelectric Element: A Review

by Matteo Chiatto^*

, Francesco Capuano, Gennaro Coppola

and Luigi De Luca

Department of Industrial Engineering, Aerospace Sector, Universitá degli Studi di Napoli “Federico II”, p.le Tecchio 80, 80125 Naples, Italy

Sensors 2017, 17(6), 1216; https://doi.org/10.3390/s17061216 - 26 May 2017

Cited by 58 | Viewed by 7312

Abstract

In the last decades, Synthetic jet actuators have gained much interest among the flow control techniques due to their short response time, high jet velocity and absence of traditional piping, which matches the requirements of reduced size and low weight. A synthetic jet [...] Read more.

In the last decades, Synthetic jet actuators have gained much interest among the flow control techniques due to their short response time, high jet velocity and absence of traditional piping, which matches the requirements of reduced size and low weight. A synthetic jet is generated by the diaphragm oscillation (generally driven by a piezoelectric element) in a relatively small cavity, producing periodic cavity pressure variations associated with cavity volume changes. The pressured air exhausts through an orifice, converting diaphragm electrodynamic energy into jet kinetic energy. This review paper considers the development of various Lumped-Element Models (LEMs) as practical tools to design and manufacture the actuators. LEMs can quickly predict device performances such as the frequency response in terms of diaphragm displacement, cavity pressure and jet velocity, as well as the efficiency of energy conversion of input Joule power into useful kinetic power of air jet. The actuator performance is also analyzed by varying typical geometric parameters such as cavity height and orifice diameter and length, through a suited dimensionless form of the governing equations. A comprehensive and detailed physical modeling aimed to evaluate the device efficiency is introduced, shedding light on the different stages involved in the process. Overall, the influence of the coupling degree of the two oscillators, the diaphragm and the Helmholtz frequency, on the device performance is discussed throughout the paper. Full article

(This article belongs to the Special Issue Piezoelectric Micro- and Nano-Devices)

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16 pages, 7418 KiB

Open AccessArticle

A Smart Power Electronic Multiconverter for the Residential Sector

by Miguel Angel Guerrero-Martinez^*, Maria Isabel Milanes-Montero, Fermin Barrero-Gonzalez, Victor Manuel Miñambres-Marcos

, Enrique Romero-Cadaval and Eva Gonzalez-Romera

Power Electrical and Electronic Systems Research Group, Escuela de Ingenierías Industriales, Universidad de Extremadura, Avda. de Elvas, s/n, Badajoz 06006, Spain

Sensors 2017, 17(6), 1217; https://doi.org/10.3390/s17061217 - 26 May 2017

Cited by 20 | Viewed by 5788

Abstract

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and [...] Read more.

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and Energy Management Systems (EMS) are necessary. The trend direction is towards the creation of energy resource hubs, such as the smart community concept. This paper presents a smart multiconverter system for residential/housing sector with a Hybrid Energy Storage System (HESS) consisting of supercapacitor and battery, and with local photovoltaic (PV) energy source integration. The device works as a distributed energy unit located in each house of the community, receiving active power set-points provided by a smart community EMS. This central EMS is responsible for managing the active energy flows between the electricity grid, renewable energy sources, storage equipment and loads existing in the community. The proposed multiconverter is responsible for complying with the reference active power set-points with proper power quality; guaranteeing that the local PV modules operate with a Maximum Power Point Tracking (MPPT) algorithm; and extending the lifetime of the battery thanks to a cooperative operation of the HESS. A simulation model has been developed in order to show the detailed operation of the system. Finally, a prototype of the multiconverter platform has been implemented and some experimental tests have been carried out to validate it. Full article

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

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16 pages, 3101 KiB

Open AccessArticle

Modelling and Optimization of Four-Segment Shielding Coils of Current Transformers

by Yucheng Gao¹

, Wei Zhao¹, Qing Wang^2,*

, Kaifeng Qu³, He Li⁴, Haiming Shao⁵ and Songling Huang¹

¹ Department of Electrical Engineering, Tsinghua University, Beijing 100084, China

² School of Engineering and Computing Sciences, Durham University, Durham DH1 3LE, UK

³ Beijing Internet Based Engineering Co., Ltd., Beijing 100083, China

⁴ Institute of Instrumentation and Measurement, State Grid Electric Power Research Institute, Wuhan 430074, China

⁵ Division of Electricity and Magnetism, National Institute of Metrology, Beijing 100029, China

Sensors 2017, 17(6), 1218; https://doi.org/10.3390/s17061218 - 26 May 2017

Cited by 3 | Viewed by 4155

Abstract

Applying shielding coils is a practical way to protect current transformers (CTs) for large-capacity generators from the intensive magnetic interference produced by adjacent bus-bars. The aim of this study is to build a simple analytical model for the shielding coils, from which the [...] Read more.

Applying shielding coils is a practical way to protect current transformers (CTs) for large-capacity generators from the intensive magnetic interference produced by adjacent bus-bars. The aim of this study is to build a simple analytical model for the shielding coils, from which the optimization of the shielding coils can be calculated effectively. Based on an existing stray flux model, a new analytical model for the leakage flux of partial coils is presented, and finite element method-based simulations are carried out to develop empirical equations for the core-pickup factors of the models. Using the flux models, a model of the common four-segment shielding coils is derived. Furthermore, a theoretical analysis is carried out on the optimal performance of the four-segment shielding coils in a typical six-bus-bars scenario. It turns out that the “all parallel” shielding coils with a 45° starting position have the best shielding performance, whereas the “separated loop” shielding coils with a 0° starting position feature the lowest heating value. Physical experiments were performed, which verified all the models and the conclusions proposed in the paper. In addition, for shielding coils with other than the four-segment configuration, the analysis process will generally be the same. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 3704 KiB

Open AccessArticle

Corrugated-Diaphragm Based Fiber Laser Hydrophone with Sub-100 μPa/Hz^1/2 Resolution

by Wen-Zhao Yang, Long Jin^*, Yi-Zhi Liang, Jun Ma and Bai-Ou Guan

Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou 510632, China

Sensors 2017, 17(6), 1219; https://doi.org/10.3390/s17061219 - 26 May 2017

Cited by 18 | Viewed by 7370

Abstract

In this work, a beat-frequency encoded fiber laser hydrophone is developed for high-resolution acoustic detection by using an elastic corrugated diaphragm. The diaphragm is center-supported by the fiber. Incident acoustic waves deform the diaphragm and induce a concentrated lateral load on the laser [...] Read more.

In this work, a beat-frequency encoded fiber laser hydrophone is developed for high-resolution acoustic detection by using an elastic corrugated diaphragm. The diaphragm is center-supported by the fiber. Incident acoustic waves deform the diaphragm and induce a concentrated lateral load on the laser cavity. The acoustically induced perturbation changes local optical phases and frequency-modulates the radio-frequency beat signal between two orthogonal lasing modes of the cavity. Theoretical analysis reveals that a higher corrugation-depth/thickness ratio or larger diaphragm area can provide higher transduction efficiency. The experimentally achieved average sensitivity in beat-frequency variation is 185.7 kHz/Pa over a bandwidth of 1 kHz. The detection capability can be enhanced by shortening the cavity length to enhance the signal-to-noise ratio. The minimum detectable acoustic pressure reaches 74 µPa/Hz^1/2 at 1 kHz, which is comparable to the zeroth order sea noise. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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10 pages, 4693 KiB

Open AccessArticle

Development of a Flexible Artificial Lateral Line Canal System for Hydrodynamic Pressure Detection

by Yonggang Jiang^1,2,*

, Zhiqiang Ma¹, Jianchao Fu¹ and Deyuan Zhang¹

¹ School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China

² International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China

Sensors 2017, 17(6), 1220; https://doi.org/10.3390/s17061220 - 26 May 2017

Cited by 45 | Viewed by 6576

Abstract

Surface mounted ‘smart skin’ can enhance the situational and environmental awareness of marine vehicles, which requires flexible, reliable, and light-weight hydrodynamic pressure sensors. Inspired by the lateral line canal system in fish, we developed an artificial lateral line (ALL) canal system by integrating [...] Read more.

Surface mounted ‘smart skin’ can enhance the situational and environmental awareness of marine vehicles, which requires flexible, reliable, and light-weight hydrodynamic pressure sensors. Inspired by the lateral line canal system in fish, we developed an artificial lateral line (ALL) canal system by integrating cantilevered flow-sensing elements in a polydimethylsiloxane (PDMS) canal. Polypropylene and polyvinylidene fluoride (PVDF) layers were laminated together to form the cantilevered flow-sensing elements. Both the ALL canal system and its superficial counterpart were characterized using a dipole vibration source. Experimental results showed that the peak frequencies of both the canal and superficial sensors were approximately 110 Hz, which was estimated to be the resonance frequency of the cantilevered flow-sensing element. The proposed ALL canal system demonstrated high-pass filtering capabilities to attenuate low-frequency stimulus and a pressure gradient detection limit of approximately 11 Pa/m at a frequency of 115 ± 1 Hz. Because of its structural flexibility and noise immunity, the proposed ALL canal system shows significant potential for underwater robotics applications. Full article

(This article belongs to the Special Issue Piezoelectric Micro- and Nano-Devices)

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16 pages, 4280 KiB

Open AccessArticle

Time Series Data Analysis of Wireless Sensor Network Measurements of Temperature

by Siddhartha Bhandari^1,2, Neil Bergmann^1,*

, Raja Jurdak² and Branislav Kusy²

¹ School of ITEE, University of Queensland, Brisbane 4072, Australia

² CSIRO/Data61, Pullenvale 4069, Australia

Sensors 2017, 17(6), 1221; https://doi.org/10.3390/s17061221 - 26 May 2017

Cited by 34 | Viewed by 9029

Abstract

Wireless sensor networks have gained significant traction in environmental signal monitoring and analysis. The cost or lifetime of the system typically depends on the frequency at which environmental phenomena are monitored. If sampling rates are reduced, energy is saved. Using empirical datasets collected [...] Read more.

Wireless sensor networks have gained significant traction in environmental signal monitoring and analysis. The cost or lifetime of the system typically depends on the frequency at which environmental phenomena are monitored. If sampling rates are reduced, energy is saved. Using empirical datasets collected from environmental monitoring sensor networks, this work performs time series analyses of measured temperature time series. Unlike previous works which have concentrated on suppressing the transmission of some data samples by time-series analysis but still maintaining high sampling rates, this work investigates reducing the sampling rate (and sensor wake up rate) and looks at the effects on accuracy. Results show that the sampling period of the sensor can be increased up to one hour while still allowing intermediate and future states to be estimated with interpolation RMSE less than 0.2 °C and forecasting RMSE less than 1 °C. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 3648 KiB

Open AccessArticle

A Multiple Sensors Platform Method for Power Line Inspection Based on a Large Unmanned Helicopter

by Xiaowei Xie¹

, Zhengjun Liu^1,*

, Caijun Xu²

and Yongzhen Zhang¹

¹ Institute of Photogrammetry and Remote Sensing, Chinese Academy of Surveying and Mapping, Beijing 100830, China

² School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China

Sensors 2017, 17(6), 1222; https://doi.org/10.3390/s17061222 - 26 May 2017

Cited by 46 | Viewed by 5799

Abstract

Many theoretical and experimental studies have been carried out in order to improve the efficiency and reduce labor for power line inspection, but problems related to stability, efficiency, and comprehensiveness still exist. This paper presents a multiple sensors platform method for overhead power [...] Read more.

Many theoretical and experimental studies have been carried out in order to improve the efficiency and reduce labor for power line inspection, but problems related to stability, efficiency, and comprehensiveness still exist. This paper presents a multiple sensors platform method for overhead power line inspection based on the use of a large unmanned helicopter. Compared with the existing methods, multiple sensors can realize synchronized inspection on all power line components and surrounding objects within one sortie. Flight safety of unmanned helicopter, scheduling of sensors and exact tracking on power line components are very important aspects when using the proposed multiple sensors platform, therefore this paper introduces in detail the planning method for the flight path of the unmanned helicopter and tasks of the sensors before inspecting power lines, and the method used for tracking power lines and insulators automatically during the inspection process. To validate the method, experiments on a transmission line at Qingyuan in Guangdong Province were carried out, the results show that the proposed method is effective for power line inspection. Full article

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

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21 pages, 3940 KiB

Open AccessArticle

Complete Tri-Axis Magnetometer Calibration with a Gyro Auxiliary

by Deng Yang^1,2

, Zheng You^1,2,*, Bin Li^1,2, Wenrui Duan^1,2 and Binwen Yuan^1,2

¹ Department of Precision Instrument, Tsinghua University, Beijing 100084, China

² State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(6), 1223; https://doi.org/10.3390/s17061223 - 26 May 2017

Cited by 29 | Viewed by 7110

Abstract

Magnetometers combined with inertial sensors are widely used for orientation estimation, and calibrations are necessary to achieve high accuracy. This paper presents a complete tri-axis magnetometer calibration algorithm with a gyro auxiliary. The magnetic distortions and sensor errors, including the misalignment error between [...] Read more.

Magnetometers combined with inertial sensors are widely used for orientation estimation, and calibrations are necessary to achieve high accuracy. This paper presents a complete tri-axis magnetometer calibration algorithm with a gyro auxiliary. The magnetic distortions and sensor errors, including the misalignment error between the magnetometer and assembled platform, are compensated after calibration. With the gyro auxiliary, the magnetometer linear interpolation outputs are calculated, and the error parameters are evaluated under linear operations of magnetometer interpolation outputs. The simulation and experiment are performed to illustrate the efficiency of the algorithm. After calibration, the heading errors calculated by magnetometers are reduced to 0.5° (1σ). This calibration algorithm can also be applied to tri-axis accelerometers whose error model is similar to tri-axis magnetometers. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 6531 KiB

Open AccessArticle

Comparison Study between RMS and Edge Detection Image Processing Algorithms for a Pulsed Laser UWPI (Ultrasonic Wave Propagation Imaging)-Based NDT Technique

by Changgil Lee¹, Aoqi Zhang¹, Byoungjoon Yu² and Seunghee Park^1,*

¹ School of Civil, Architectural Engineering and Landscape Architecture, Sungkyunkwan University, Gyeonggi-do, Suwon-si 16419, Korea

² Department of Convergence Engineering for Future City, Sungkyunkwan University, Gyeonggi-do, Suwon-si 16419, Korea

Sensors 2017, 17(6), 1224; https://doi.org/10.3390/s17061224 - 26 May 2017

Cited by 18 | Viewed by 6334

Abstract

In this study, a non-contact laser ultrasonic propagation imaging technique was applied to detect the damage of plate-like structures. Lamb waves were generated by an Nd:YAG pulse laser system, while a galvanometer-based laser scanner was used to scan the preliminarily designated area. The [...] Read more.

In this study, a non-contact laser ultrasonic propagation imaging technique was applied to detect the damage of plate-like structures. Lamb waves were generated by an Nd:YAG pulse laser system, while a galvanometer-based laser scanner was used to scan the preliminarily designated area. The signals of the structural responses were measured using a piezoelectric sensor attached on the front or back side of the plates. The obtained responses were analyzed by calculating the root mean square (RMS) values to achieve the visualization of structural defects such as crack, corrosion, and so on. If the propagating waves encounter the damage, the waves are scattered at the damage and the energy of the scattered waves can be expressed by the RMS values. In this study, notch and corrosion were artificially formed on aluminum plates and were considered as structural defects. The notches were created with different depths and angles on the aluminum plates, and the corrosion damage was formed with different depths and areas. To visualize the damage more clearly, edge detection methodologies were applied to the RMS images and the feasibility of the methods was investigated. The results showed that most of the edge detection methods were good at detecting the shape and/or the size of the damage while they had poor performance of detecting the depth of the damage. Full article

(This article belongs to the Special Issue Intelligent Sensing Technologies for Nondestructive Evaluation)

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11 pages, 1214 KiB

Open AccessArticle

DOA Finding with Support Vector Regression Based Forward–Backward Linear Prediction

by Jingjing Pan¹

, Yide Wang^1,*

, Cédric Le Bastard^1,2 and Tianzhen Wang³

¹ Institut d’Electronique et Télécommunications de Rennes, UMR CNRS 6164, Polytech Nantes, Rue Christian Pauc, BP 50609, 44306 Nantes CEDEX 3, France

² Cerema, 49136 Les Ponts de Cé, France

³ Logistics Engineering College, Shanghai Maritime University, Shanghai 201306, China

Sensors 2017, 17(6), 1225; https://doi.org/10.3390/s17061225 - 27 May 2017

Cited by 13 | Viewed by 5360

Abstract

Direction-of-arrival (DOA) estimation has drawn considerable attention in array signal processing, particularly with coherent signals and a limited number of snapshots. Forward–backward linear prediction (FBLP) is able to directly deal with coherent signals. Support vector regression (SVR) is robust with small samples. This [...] Read more.

Direction-of-arrival (DOA) estimation has drawn considerable attention in array signal processing, particularly with coherent signals and a limited number of snapshots. Forward–backward linear prediction (FBLP) is able to directly deal with coherent signals. Support vector regression (SVR) is robust with small samples. This paper proposes the combination of the advantages of FBLP and SVR in the estimation of DOAs of coherent incoming signals with low snapshots. The performance of the proposed method is validated with numerical simulations in coherent scenarios, in terms of different angle separations, numbers of snapshots, and signal-to-noise ratios (SNRs). Simulation results show the effectiveness of the proposed method. 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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16 pages, 578 KiB

Open AccessArticle

Adaptive Data Aggregation and Compression to Improve Energy Utilization in Solar-Powered Wireless Sensor Networks

by Ikjune Yoon¹

, Hyeok Kim² and Dong Kun Noh^2,*

¹ Department of Smart Systems Software, Soongsil University, Seoul 06978, Korea

² Department of Software Convergence, Soongsil University, Seoul 06978, Korea

Sensors 2017, 17(6), 1226; https://doi.org/10.3390/s17061226 - 27 May 2017

Cited by 27 | Viewed by 6463

Abstract

A node in a solar-powered wireless sensor network (WSN) collects energy when the sun shines and stores it in a battery or capacitor for use when no solar power is available, in particular at night. In our scheme, each tiny node in a [...] Read more.

A node in a solar-powered wireless sensor network (WSN) collects energy when the sun shines and stores it in a battery or capacitor for use when no solar power is available, in particular at night. In our scheme, each tiny node in a WSN periodically determines its energy budget, which takes into account its residual energy, and its likely acquisition and consumption. If it expects to acquire more energy than it can store, the data which has it has sensed is aggregated with data from other nodes, compressed, and transmitted. Otherwise, the node continues to sense data, but turns off its wireless communication to reduce energy consumption. We compared several schemes by simulation. Our scheme reduced the number of nodes forced to black out due to lack of energy so that more data arrives at the sink node. Full article

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

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19 pages, 5528 KiB

Open AccessArticle

A Protocol Layer Trust-Based Intrusion Detection Scheme for Wireless Sensor Networks

by Jian Wang^1,*, Shuai Jiang¹ and Abraham O. Fapojuwo²

¹ School of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China

² Department of Electrical and Computer Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(6), 1227; https://doi.org/10.3390/s17061227 - 27 May 2017

Cited by 40 | Viewed by 6172

Abstract

This article proposes a protocol layer trust-based intrusion detection scheme for wireless sensor networks. Unlike existing work, the trust value of a sensor node is evaluated according to the deviations of key parameters at each protocol layer considering the attacks initiated at different [...] Read more.

This article proposes a protocol layer trust-based intrusion detection scheme for wireless sensor networks. Unlike existing work, the trust value of a sensor node is evaluated according to the deviations of key parameters at each protocol layer considering the attacks initiated at different protocol layers will inevitably have impacts on the parameters of the corresponding protocol layers. For simplicity, the paper mainly considers three aspects of trustworthiness, namely physical layer trust, media access control layer trust and network layer trust. The per-layer trust metrics are then combined to determine the overall trust metric of a sensor node. The performance of the proposed intrusion detection mechanism is then analyzed using the t-distribution to derive analytical results of false positive and false negative probabilities. Numerical analytical results, validated by simulation results, are presented in different attack scenarios. It is shown that the proposed protocol layer trust-based intrusion detection scheme outperforms a state-of-the-art scheme in terms of detection probability and false probability, demonstrating its usefulness for detecting cross-layer attacks. Full article

(This article belongs to the Collection Smart Communication Protocols and Algorithms for Sensor Networks)

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12 pages, 31763 KiB

Open AccessArticle

Underwater Depth and Temperature Sensing Based on Fiber Optic Technology for Marine and Fresh Water Applications

by Dinesh Babu Duraibabu^1,2,*

, Gabriel Leen¹

, Daniel Toal², Thomas Newe^1,2

, Elfed Lewis^1,*

and Gerard Dooly²

¹ Optical Fibre Sensors Research Centre (OFSRC), University of Limerick, Limerick V94 T9PX, Ireland

² Mobile and Marine Robotics Research Centre (MMRRC); University of Limeirck, Limerick V94 T9PX, Ireland

Sensors 2017, 17(6), 1228; https://doi.org/10.3390/s17061228 - 27 May 2017

Cited by 59 | Viewed by 13174

Abstract

Oceanic conditions play an important role in determining the effects of climate change and these effects can be monitored through the changes in the physical properties of sea water. In fact, Oceanographers use various probes for measuring the properties within the water column. [...] Read more.

Oceanic conditions play an important role in determining the effects of climate change and these effects can be monitored through the changes in the physical properties of sea water. In fact, Oceanographers use various probes for measuring the properties within the water column. CTDs (Conductivity, Temperature and Depth) provide profiles of physical and chemical parameters of the water column. A CTD device consists of Conductivity (C), Temperature (T) and Depth (D) probes to monitor the water column changes with respect to relative depth. An optical fibre-based point sensor used as a combined pressure (depth) and temperature sensor and the sensor system are described. Measurements accruing from underwater trials of a miniature sensor for pressure (depth) and temperature in the ocean and in fresh water are reported. The sensor exhibits excellent stability and its performance is shown to be comparable with the Sea-Bird Scientific commercial sensor: SBE9Plus. Full article

(This article belongs to the Special Issue Marine Sensing)

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20 pages, 7099 KiB

Open AccessArticle

Evaluation of Feature Extraction and Recognition for Activity Monitoring and Fall Detection Based on Wearable sEMG Sensors

by Xugang Xi^1,*

, Minyan Tang¹

, Seyed M. Miran² and Zhizeng Luo¹

¹ School of Automation, Hangzhou Dianzi University, Hangzhou 310018, China

² Department of Mechanical Engineering, University of Akron, Akron, OH, 44325, USA

Sensors 2017, 17(6), 1229; https://doi.org/10.3390/s17061229 - 27 May 2017

Cited by 119 | Viewed by 8446

Abstract

As an essential subfield of context awareness, activity awareness, especially daily activity monitoring and fall detection, plays a significant role for elderly or frail people who need assistance in their daily activities. This study investigates the feature extraction and pattern recognition of surface [...] Read more.

As an essential subfield of context awareness, activity awareness, especially daily activity monitoring and fall detection, plays a significant role for elderly or frail people who need assistance in their daily activities. This study investigates the feature extraction and pattern recognition of surface electromyography (sEMG), with the purpose of determining the best features and classifiers of sEMG for daily living activities monitoring and fall detection. This is done by a serial of experiments. In the experiments, four channels of sEMG signal from wireless, wearable sensors located on lower limbs are recorded from three subjects while they perform seven activities of daily living (ADL). A simulated trip fall scenario is also considered with a custom-made device attached to the ankle. With this experimental setting, 15 feature extraction methods of sEMG, including time, frequency, time/frequency domain and entropy, are analyzed based on class separability and calculation complexity, and five classification methods, each with 15 features, are estimated with respect to the accuracy rate of recognition and calculation complexity for activity monitoring and fall detection. It is shown that a high accuracy rate of recognition and a minimal calculation time for daily activity monitoring and fall detection can be achieved in the current experimental setting. Specifically, the Wilson Amplitude (WAMP) feature performs the best, and the classifier Gaussian Kernel Support Vector Machine (GK-SVM) with Permutation Entropy (PE) or WAMP results in the highest accuracy for activity monitoring with recognition rates of 97.35% and 96.43%. For fall detection, the classifier Fuzzy Min-Max Neural Network (FMMNN) has the best sensitivity and specificity at the cost of the longest calculation time, while the classifier Gaussian Kernel Fisher Linear Discriminant Analysis (GK-FDA) with the feature WAMP guarantees a high sensitivity (98.70%) and specificity (98.59%) with a short calculation time (65.586 ms), making it a possible choice for pre-impact fall detection. The thorough quantitative comparison of the features and classifiers in this study supports the feasibility of a wireless, wearable sEMG sensor system for automatic activity monitoring and fall detection. Full article

(This article belongs to the Section Biosensors)

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25 pages, 2350 KiB

Open AccessArticle

Location-Enhanced Activity Recognition in Indoor Environments Using Off the Shelf Smart Watch Technology and BLE Beacons

by Avgoustinos Filippoupolitis^*, William Oliff, Babak Takand and George Loukas

Computing and Information Systems Department, University of Greenwich, Old Royal Naval College, Park Row, London SE10 9LS, UK

Sensors 2017, 17(6), 1230; https://doi.org/10.3390/s17061230 - 27 May 2017

Cited by 33 | Viewed by 6674

Abstract

Activity recognition in indoor spaces benefits context awareness and improves the efficiency of applications related to personalised health monitoring, building energy management, security and safety. The majority of activity recognition frameworks, however, employ a network of specialised building sensors or a network of [...] Read more.

Activity recognition in indoor spaces benefits context awareness and improves the efficiency of applications related to personalised health monitoring, building energy management, security and safety. The majority of activity recognition frameworks, however, employ a network of specialised building sensors or a network of body-worn sensors. As this approach suffers with respect to practicality, we propose the use of commercial off-the-shelf devices. In this work, we design and evaluate an activity recognition system composed of a smart watch, which is enhanced with location information coming from Bluetooth Low Energy (BLE) beacons. We evaluate the performance of this approach for a variety of activities performed in an indoor laboratory environment, using four supervised machine learning algorithms. Our experimental results indicate that our location-enhanced activity recognition system is able to reach a classification accuracy ranging from 92% to 100%, while without location information classification accuracy it can drop to as low as 50% in some cases, depending on the window size chosen for data segmentation. Full article

(This article belongs to the Special Issue Smart Sensing Technologies for Personalised Coaching)

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20 pages, 9060 KiB

Open AccessArticle

A Compact Magnetic Field-Based Obstacle Detection and Avoidance System for Miniature Spherical Robots

by Fang Wu

, Akash Vibhute, Gim Song Soh, Kristin L. Wood and Shaohui Foong^*

Engineering Product Development, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore

Sensors 2017, 17(6), 1231; https://doi.org/10.3390/s17061231 - 28 May 2017

Cited by 14 | Viewed by 7748

Abstract

Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical [...] Read more.

Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical robots, yet very limited studies have been conducted regarding the obstacle avoidance capability of spherical robots. Most of the existing spherical robots rely on the “hit and run” technique, which has been argued to be a reasonable strategy because spherical robots have an inherent ability to recover from collisions. Without protruding components, they will not become stuck and can simply roll back after running into bstacles. However, for small scale spherical robots that contain sensitive surveillance sensors and cannot afford to utilize heavy protective shells, the absence of obstacle avoidance solutions would leave the robot at the mercy of potentially dangerous obstacles. In this paper, a compact magnetic field-based obstacle detection and avoidance system has been developed for miniature spherical robots. It utilizes a passive magnetic field so that the system is both compact and power efficient. The proposed system can detect not only the presence, but also the approaching direction of a ferromagnetic obstacle, therefore, an intelligent avoidance behavior can be generated by adapting the trajectory tracking method with the detection information. Design optimization is conducted to enhance the obstacle detection performance and detailed avoidance strategies are devised. Experimental results are also presented for validation purposes. Full article

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

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19 pages, 755 KiB

Open AccessArticle

History-Based Response Threshold Model for Division of Labor in Multi-Agent Systems

by Wonki Lee and DaeEun Kim^*

School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea

Sensors 2017, 17(6), 1232; https://doi.org/10.3390/s17061232 - 28 May 2017

Cited by 15 | Viewed by 4224

Abstract

Dynamic task allocation is a necessity in a group of robots. Each member should decide its own task such that it is most commensurate with its current state in the overall system. In this work, the response threshold model is applied to a [...] Read more.

Dynamic task allocation is a necessity in a group of robots. Each member should decide its own task such that it is most commensurate with its current state in the overall system. In this work, the response threshold model is applied to a dynamic foraging task. Each robot employs a task switching function based on the local task demand obtained from the surrounding environment, and no communication occurs between the robots. Each individual member has a constant-sized task demand history that reflects the global demand. In addition, it has response threshold values for all of the tasks and manages the task switching process depending on the stimuli of the task demands. The robot then determines the task to be executed to regulate the overall division of labor. This task selection induces a specialized tendency for performing a specific task and regulates the division of labor. In particular, maintaining a history of the task demands is very effective for the dynamic foraging task. Various experiments are performed using a simulation with multiple robots, and the results show that the proposed algorithm is more effective as compared to the conventional model. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 3602 KiB

Open AccessArticle

Performance of BDS-3: Measurement Quality Analysis, Precise Orbit and Clock Determination

by Xin Xie¹, Tao Geng^1,*

, Qile Zhao¹, Jingnan Liu¹ and Bin Wang²

¹ GNSS Research Center, Wuhan University, Wuhan 430079, China

² Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China

Sensors 2017, 17(6), 1233; https://doi.org/10.3390/s17061233 - 28 May 2017

Cited by 65 | Viewed by 7415

Abstract

Since 2015, China has successfully launched five experimental BeiDou global navigation system (BDS-3) satellites for expanding the regional system to global coverage. An initial performance assessment and characterization analysis of the BDS-3 is presented. Twenty days of tracking data have been collected from [...] Read more.

Since 2015, China has successfully launched five experimental BeiDou global navigation system (BDS-3) satellites for expanding the regional system to global coverage. An initial performance assessment and characterization analysis of the BDS-3 is presented. Twenty days of tracking data have been collected from eleven monitoring stations. The tracking characteristics and measurement quality are analyzed and compared with the regional BDS (BDS-2) in terms of observed carrier-to-noise density ratio, pseudo-range multipath, and noise. The preliminary results suggest that the measurement quality of BDS-3 outperforms the BDS-2 for the same type of satellites. In addition, the analysis of multipath combinations reveals that the problem of satellite-induced code biases found in BDS-2 seems to have been solved for BDS-3. Precise orbit and clock determination are carried out and evaluated. The orbit overlap comparison show a precision of 2–6 dm in 3D root mean square (RMS) and 6–14 cm in the radial component for experimental BDS-3 satellites. External validations with satellite laser ranging (SLR) show residual RMS on the level of 1–3 dm. Finally, the performance of the new-generation onboard atomic clocks is evaluated and results confirm an increased stability compared to BDS-2 satellite clocks. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 7482 KiB

Open AccessArticle

High Resolution Full-Aperture ISAR Processing through Modified Doppler History Based Motion Compensation

by Jung-Hwan Song¹, Kee-Woong Lee¹, Woo-Kyung Lee^1,*

and Chul-Ho Jung²

¹ Department of Electronic and Information Engineering, Korea Aerospace University, 76 Hanggongdaehak-ro, Deogyang-gu, Goyang-si, Gyeonggi-do 412-791, Korea

² CAL Lab., HyperSensing Inc., Yusong-gu, Gwahak-ro, Daejeon 169-84, Korea

Sensors 2017, 17(6), 1234; https://doi.org/10.3390/s17061234 - 28 May 2017

Cited by 3 | Viewed by 6560

Abstract

A high resolution inverse synthetic aperture radar (ISAR) technique is presented using modified Doppler history based motion compensation. To this purpose, a novel wideband ISAR system is developed that accommodates parametric processing over extended aperture length. The proposed method is derived from an [...] Read more.

A high resolution inverse synthetic aperture radar (ISAR) technique is presented using modified Doppler history based motion compensation. To this purpose, a novel wideband ISAR system is developed that accommodates parametric processing over extended aperture length. The proposed method is derived from an ISAR-to-SAR approach that makes use of high resolution spotlight SAR and sub-aperture recombination. It is dedicated to wide aperture ISAR imaging and exhibits robust performance against unstable targets having non-linear motions. We demonstrate that the Doppler histories of the full aperture ISAR echoes from disturbed targets are efficiently retrieved with good fitting models. Experiments have been conducted on real aircraft targets and the feasibility of the full aperture ISAR processing is verified through the acquisition of high resolution ISAR imagery. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 25466 KiB

Open AccessArticle

Study of ZnS Nanostructures Based Electrochemical and Photoelectrochemical Biosensors for Uric Acid Detection

by Yao Zhao, Xueyong Wei^*

, Niancai Peng, Jiuhong Wang and Zhuangde Jiang

State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710054, China

Sensors 2017, 17(6), 1235; https://doi.org/10.3390/s17061235 - 28 May 2017

Cited by 25 | Viewed by 6528

Abstract

Uric acid (UA) is a kind of purine metabolism product and important in clinical diagnosis. In this work, we present a study of ZnS nanostructures-based electrochemical and photoelectrochemical biosensors for UA detection. Through a simple hydrothermal method and varying the ratio of reaction [...] Read more.

Uric acid (UA) is a kind of purine metabolism product and important in clinical diagnosis. In this work, we present a study of ZnS nanostructures-based electrochemical and photoelectrochemical biosensors for UA detection. Through a simple hydrothermal method and varying the ratio of reaction solvents, we obtained ZnS nanomaterials of one-dimensional to three-dimensional morphologies and they were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). To fabricate the UA biosensor and study the effect of material morphology on its performance, ZnS nanomaterials were deposited on indium tin oxide (ITO) conducting glass and then coated with uricase by physical absorption. Three kinds of working electrodes were characterized by cyclic voltammetry method. The effect of material morphology on performance of UA detection was investigated via amperometric response based electrochemical method based on enzymatic reaction. The ZnS urchin-like nanostructures electrode shows better sensitivity compared with those made of nanoparticles and nanoflakes because of its high surface-area-to-volume ratio. The photoelectrochemical method for detection of UA was also studied. The sensitivity was increased 5 times after irradiation of 300 nm UV light. These results indicate that ZnS nanostructures are good candidate materials for developing enzyme-based UA biosensors. Full article

(This article belongs to the Section Biosensors)

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22 pages, 4817 KiB

Open AccessArticle

Denoising Algorithm for CFA Image Sensors Considering Inter-Channel Correlation

by Min Seok Lee¹, Sang Wook Park² and Moon Gi Kang^1,*

¹ School of Electrical and Electronics Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul 03722, Korea

² Medical Device Development Centre, Daegu-Gyeongbuk Medical Innovation Foundation, 80 Cheombok-Ro, Dong-gu, Daegu 41061, Korea

Sensors 2017, 17(6), 1236; https://doi.org/10.3390/s17061236 - 28 May 2017

Cited by 8 | Viewed by 5870

Abstract

In this paper, a spatio-spectral-temporal filter considering an inter-channel correlation is proposed for the denoising of a color filter array (CFA) sequence acquired by CCD/CMOS image sensors. Owing to the alternating under-sampled grid of the CFA pattern, the inter-channel correlation must be considered [...] Read more.

In this paper, a spatio-spectral-temporal filter considering an inter-channel correlation is proposed for the denoising of a color filter array (CFA) sequence acquired by CCD/CMOS image sensors. Owing to the alternating under-sampled grid of the CFA pattern, the inter-channel correlation must be considered in the direct denoising process. The proposed filter is applied in the spatial, spectral, and temporal domain, considering the spatio-tempo-spectral correlation. First, nonlocal means (NLM) spatial filtering with patch-based difference (PBD) refinement is performed by considering both the intra-channel correlation and inter-channel correlation to overcome the spatial resolution degradation occurring with the alternating under-sampled pattern. Second, a motion-compensated temporal filter that employs inter-channel correlated motion estimation and compensation is proposed to remove the noise in the temporal domain. Then, a motion adaptive detection value controls the ratio of the spatial filter and the temporal filter. The denoised CFA sequence can thus be obtained without motion artifacts. Experimental results for both simulated and real CFA sequences are presented with visual and numerical comparisons to several state-of-the-art denoising methods combined with a demosaicing method. Experimental results confirmed that the proposed frameworks outperformed the other techniques in terms of the objective criteria and subjective visual perception in CFA sequences. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 4416 KiB

Open AccessArticle

Generalized Chirp Scaling Combined with Baseband Azimuth Scaling Algorithm for Large Bandwidth Sliding Spotlight SAR Imaging

by Tianzhu Yi^1,*

, Zhihua He¹, Feng He¹, Zhen Dong¹ and Manqing Wu²

¹ School of Electronic Science and Engineering, National University of Defense Technology, Sanyi Avenue, Changsha 410073, China

² China Electronics Technology Group Corporation (CETC), China Academy of Electronics and Information Technology, Beijing 100846, China

Sensors 2017, 17(6), 1237; https://doi.org/10.3390/s17061237 - 29 May 2017

Cited by 6 | Viewed by 4710

Abstract

This paper presents an efficient and precise imaging algorithm for the large bandwidth sliding spotlight synthetic aperture radar (SAR). The existing sub-aperture processing method based on the baseband azimuth scaling (BAS) algorithm cannot cope with the high order phase coupling along the range [...] Read more.

This paper presents an efficient and precise imaging algorithm for the large bandwidth sliding spotlight synthetic aperture radar (SAR). The existing sub-aperture processing method based on the baseband azimuth scaling (BAS) algorithm cannot cope with the high order phase coupling along the range and azimuth dimensions. This coupling problem causes defocusing along the range and azimuth dimensions. This paper proposes a generalized chirp scaling (GCS)-BAS processing algorithm, which is based on the GCS algorithm. It successfully mitigates the deep focus along the range dimension of a sub-aperture of the large bandwidth sliding spotlight SAR, as well as high order phase coupling along the range and azimuth dimensions. Additionally, the azimuth focusing can be achieved by this azimuth scaling method. Simulation results demonstrate the ability of the GCS-BAS algorithm to process the large bandwidth sliding spotlight SAR data. It is proven that great improvements of the focus depth and imaging accuracy are obtained via the GCS-BAS algorithm. Full article

(This article belongs to the Section Remote Sensors)

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16 pages, 6511 KiB

Open AccessArticle

Corrosivity Sensor for Exposed Pipelines Based on Wireless Energy Transfer

by Lydia Lawand^1,†

, Oleg Shiryayev^1,*

, Khalil Al Handawi^1,†

, Nader Vahdati¹ and Paul Rostron²

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

² Chemistry Department, Khalifa University of Science and Technology, Petroleum Institute, P.O. Box 2533, Abu Dhabi, UAE

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

Sensors 2017, 17(6), 1238; https://doi.org/10.3390/s17061238 - 30 May 2017

Cited by 10 | Viewed by 6880

Abstract

External corrosion was identified as one of the main causes of pipeline failures worldwide. A solution that addresses the issue of detecting and quantifying corrosivity of environment for application to existing exposed pipelines has been developed. It consists of a sensing array made [...] Read more.

External corrosion was identified as one of the main causes of pipeline failures worldwide. A solution that addresses the issue of detecting and quantifying corrosivity of environment for application to existing exposed pipelines has been developed. It consists of a sensing array made of an assembly of thin strips of pipeline steel and a circuit that provides a visual sensor reading to the operator. The proposed sensor is passive and does not require a constant power supply. Circuit design was validated through simulations and lab experiments. Accelerated corrosion experiment was conducted to confirm the feasibility of the proposed corrosivity sensor design. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 2508 KiB

Open AccessArticle

Multi-Site Simultaneous Time-Resolved Photometry with a Low Cost Electro-Optics System

by Forrest Gasdia^1,2,*, Aroh Barjatya¹ and Sergei Bilardi^1,†

¹ Space and Atmospheric Instrumentation Lab, Center for Space and Atmospheric Research, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA

² Ann & H. J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO 80309, USA

^† This paper is an extended version of an earlier conference paper: Forrest Gasdia, Aroh Barjatya, Sergei Bilardi. Time-resolved CubeSat photometry with a low cost electro-optics system. In Proceedings of Advanced Maui Optical and Space Surveillance Technologies Conference, Maui, HI, USA, 20–23 September 2016.

Sensors 2017, 17(6), 1239; https://doi.org/10.3390/s17061239 - 30 May 2017

Cited by 8 | Viewed by 5482

Abstract

Sunlight reflected off of resident space objects can be used as an optical signal for astrometric orbit determination and for deducing geometric information about the object. With the increasing population of small satellites and debris in low Earth orbit, photometry is a powerful [...] Read more.

Sunlight reflected off of resident space objects can be used as an optical signal for astrometric orbit determination and for deducing geometric information about the object. With the increasing population of small satellites and debris in low Earth orbit, photometry is a powerful tool in operational support of space missions, whether for anomaly resolution or object identification. To accurately determine size, shape, spin rate, status of deployables, or attitude information of an unresolved resident space object, multi-hertz sample rate photometry is required to capture the relatively rapid changes in brightness that these objects can exhibit. OSCOM, which stands for Optical tracking and Spectral characterization of CubeSats for Operational Missions, is a low cost and portable telescope system capable of time-resolved small satellite photometry, and is field deployable on short notice for simultaneous observation from multiple sites. We present the electro-optical design principles behind OSCOM and light curves of the 1.5 U DICE-2 CubeSat and simultaneous observations of the main body of the ASTRO-H satellite after its fragmentation event. Full article

(This article belongs to the Section Physical Sensors)

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25 pages, 8322 KiB

Open AccessArticle

Vital Sign Monitoring and Mobile Phone Usage Detection Using IR-UWB Radar for Intended Use in Car Crash Prevention

by Seong Kyu Leem^†

, Faheem Khan^†

and Sung Ho Cho^*

¹ Department of Electronics and Computer Engineering, Hanyang University, 222 Wangsimini-ro, Seongdong-gu, Seoul 04763, Korea

^† Co-first authors, these authors contributed equally to this work.

Sensors 2017, 17(6), 1240; https://doi.org/10.3390/s17061240 - 30 May 2017

Cited by 96 | Viewed by 15692

Abstract

In order to avoid car crashes, active safety systems are becoming more and more important. Many crashes are caused due to driver drowsiness or mobile phone usage. Detecting the drowsiness of the driver is very important for the safety of a car. Monitoring [...] Read more.

In order to avoid car crashes, active safety systems are becoming more and more important. Many crashes are caused due to driver drowsiness or mobile phone usage. Detecting the drowsiness of the driver is very important for the safety of a car. Monitoring of vital signs such as respiration rate and heart rate is important to determine the occurrence of driver drowsiness. In this paper, robust vital signs monitoring through impulse radio ultra-wideband (IR-UWB) radar is discussed. We propose a new algorithm that can estimate the vital signs even if there is motion caused by the driving activities. We analyzed the whole fast time vital detection region and found the signals at those fast time locations that have useful information related to the vital signals. We segmented those signals into sub-signals and then constructed the desired vital signal using the correlation method. In this way, the vital signs of the driver can be monitored noninvasively, which can be used by researchers to detect the drowsiness of the driver which is related to the vital signs i.e., respiration and heart rate. In addition, texting on a mobile phone during driving may cause visual, manual or cognitive distraction of the driver. In order to reduce accidents caused by a distracted driver, we proposed an algorithm that can detect perfectly a driver's mobile phone usage even if there are various motions of the driver in the car or changes in background objects. These novel techniques, which monitor vital signs associated with drowsiness and detect phone usage before a driver makes a mistake, may be very helpful in developing techniques for preventing a car crash. Full article

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

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21 pages, 12259 KiB

Open AccessArticle

Using Color, Texture and Object-Based Image Analysis of Multi-Temporal Camera Data to Monitor Soil Aggregate Breakdown

by Irena Ymeti^*, Harald Van der Werff

, Dhruba Pikha Shrestha, Victor G. Jetten, Caroline Lievens and Freek Van der Meer

Department of Earth Systems Analysis, Faculty of Geo-Information Science and Earth Observation, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

Sensors 2017, 17(6), 1241; https://doi.org/10.3390/s17061241 - 30 May 2017

Cited by 11 | Viewed by 5731

Abstract

Remote sensing has shown its potential to assess soil properties and is a fast and non-destructive method for monitoring soil surface changes. In this paper, we monitor soil aggregate breakdown under natural conditions. From November 2014 to February 2015, images and weather data [...] Read more.

Remote sensing has shown its potential to assess soil properties and is a fast and non-destructive method for monitoring soil surface changes. In this paper, we monitor soil aggregate breakdown under natural conditions. From November 2014 to February 2015, images and weather data were collected on a daily basis from five soils susceptible to detachment (Silty Loam with various organic matter content, Loam and Sandy Loam). Three techniques that vary in image processing complexity and user interaction were tested for the ability of monitoring aggregate breakdown. Considering that the soil surface roughness causes shadow cast, the blue/red band ratio is utilized to observe the soil aggregate changes. Dealing with images with high spatial resolution, image texture entropy, which reflects the process of soil aggregate breakdown, is used. In addition, the Huang thresholding technique, which allows estimation of the image area occupied by soil aggregate, is performed. Our results show that all three techniques indicate soil aggregate breakdown over time. The shadow ratio shows a gradual change over time with no details related to weather conditions. Both the entropy and the Huang thresholding technique show variations of soil aggregate breakdown responding to weather conditions. Using data obtained with a regular camera, we found that freezing–thawing cycles are the cause of soil aggregate breakdown. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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18 pages, 5705 KiB

Open AccessArticle

Belief Interval of Dempster-Shafer Theory for Line-of-Sight Identification in Indoor Positioning Applications

by Jinwu Wu, Tingyu Zhao, Shang Li and Chung-Ming Own^*

School of Computer Software, Tianjin University, Tianjin 300350, China

Sensors 2017, 17(6), 1242; https://doi.org/10.3390/s17061242 - 30 May 2017

Cited by 3 | Viewed by 4718

Abstract

Location data are among the most widely used contextual data in context-aware and ubiquitous computing applications. Numerous systems with distinct deployment costs and levels of positioning accuracy have been developed over the past decade for indoor positioning purposes. The most useful method focuses [...] Read more.

Location data are among the most widely used contextual data in context-aware and ubiquitous computing applications. Numerous systems with distinct deployment costs and levels of positioning accuracy have been developed over the past decade for indoor positioning purposes. The most useful method focuses on the received signal strength (RSS) and provides a set of signal transmission access points. Furthermore, most positioning systems are based on non-line-of-sight (NLOS) rather than line-of-sight (LOS) conditions, and this cause ranging errors for location predictions. Hence, manually compiling a fingerprint database measuring RSS involves high costs and is thus impractical in online prediction environments. In our proposed method, a comparison method is derived on the basis of belief intervals, as proposed in Dempster-Shafer theory, and the signal features are characterized on the LOS and NLOS conditions for different field experiments. The system performance levels were examined with different features and under different environments through robust testing and by using several widely used machine learning methods. The results showed that the proposed method can not only retain positioning accuracy but also save computation time in location predictions. Full article

(This article belongs to the Special Issue The Architectures, Systems, and Applications of Internet of Things for Smart Cities)

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17 pages, 3286 KiB

Open AccessArticle

Extraction of Rice Phenological Differences under Heavy Metal Stress Using EVI Time-Series from HJ-1A/B Data

by Shuyuan Liu, Xiangnan Liu^*, Meiling Liu, Ling Wu, Chao Ding and Zhi Huang

School of Information Engineering, China University of Geosciences, Beijing 100083, China

Sensors 2017, 17(6), 1243; https://doi.org/10.3390/s17061243 - 30 May 2017

Cited by 22 | Viewed by 5620

Abstract

An effective method to monitor heavy metal stress in crops is of critical importance to assure agricultural production and food security. Phenology, as a sensitive indicator of environmental change, can respond to heavy metal stress in crops and remote sensing is an effective [...] Read more.

An effective method to monitor heavy metal stress in crops is of critical importance to assure agricultural production and food security. Phenology, as a sensitive indicator of environmental change, can respond to heavy metal stress in crops and remote sensing is an effective method to detect plant phenological changes. This study focused on identifying the rice phenological differences under varied heavy metal stress using EVI (enhanced vegetation index) time-series, which was obtained from HJ-1A/B CCD images and fitted with asymmetric Gaussian model functions. We extracted three phenological periods using first derivative analysis: the tillering period, heading period, and maturation period; and constructed two kinds of metrics with phenological characteristics: date-intervals and time-integrated EVI, to explore the rice phenological differences under mild and severe stress levels. Results indicated that under severe stress the values of the metrics for presenting rice phenological differences in the experimental areas of heavy metal stress were smaller than the ones under mild stress. This finding represents a new method for monitoring heavy metal contamination through rice phenology. Full article

(This article belongs to the Special Issue Earth Observation for Biodiversity and Ecosystem Services: Remote Sensing Data Handling and Analysis)

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15 pages, 4736 KiB

Open AccessArticle

The Lateral Tracking Control for the Intelligent Vehicle Based on Adaptive PID Neural Network

by Gaining Han^1,2, Weiping Fu^1,*, Wen Wang¹ and Zongsheng Wu^1,2

¹ School of Mechanical and Precision Instrument Engineering, Xi’an University of Technology, Xi’an 710048, China

² School of Computer, Xianyang Normal University, Xianyang 712000, China

Sensors 2017, 17(6), 1244; https://doi.org/10.3390/s17061244 - 30 May 2017

Cited by 145 | Viewed by 10873

Abstract

The intelligent vehicle is a complicated nonlinear system, and the design of a path tracking controller is one of the key technologies in intelligent vehicle research. This paper mainly designs a lateral control dynamic model of the intelligent vehicle, which is used for [...] Read more.

The intelligent vehicle is a complicated nonlinear system, and the design of a path tracking controller is one of the key technologies in intelligent vehicle research. This paper mainly designs a lateral control dynamic model of the intelligent vehicle, which is used for lateral tracking control. Firstly, the vehicle dynamics model (i.e., transfer function) is established according to the vehicle parameters. Secondly, according to the vehicle steering control system and the CARMA (Controlled Auto-Regression and Moving-Average) model, a second-order control system model is built. Using forgetting factor recursive least square estimation (FFRLS), the system parameters are identified. Finally, a neural network PID (Proportion Integral Derivative) controller is established for lateral path tracking control based on the vehicle model and the steering system model. Experimental simulation results show that the proposed model and algorithm have the high real-time and robustness in path tracing control. This provides a certain theoretical basis for intelligent vehicle autonomous navigation tracking control, and lays the foundation for the vertical and lateral coupling control. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 2969 KiB

Open AccessArticle

Smartphone-Based pH Sensor for Home Monitoring of Pulmonary Exacerbations in Cystic Fibrosis

by Alexander Sun¹, Tom Phelps¹, Chengyang Yao¹, A. G. Venkatesh¹, Douglas Conrad² and Drew A. Hall^1,*

¹ Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093, USA

² Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA

Sensors 2017, 17(6), 1245; https://doi.org/10.3390/s17061245 - 30 May 2017

Cited by 16 | Viewed by 8629

Abstract

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral [...] Read more.

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral pH measurement device was designed to attach directly to the headphone port to harvest power and communicate with a smartphone application. This platform was tested using prepared pH buffers and sputum samples from CF patients. The system matches within ~0.03 pH of a benchtop pH meter while fully powering itself and communicating with a Samsung Galaxy S3 smartphone paired with either a glass or Iridium Oxide (IrOx) electrode. The IrOx electrodes were found to have 25% higher sensitivity than the glass probes at the expense of larger drift and matrix sensitivity that can be addressed with proper calibration. The smartphone-based platform has been demonstrated as a portable replacement for laboratory pH meters, and supports both highly robust glass probes and the sensitive and miniature IrOx electrodes with calibration. This tool can enable more frequent pH sputum tracking for CF patients to help detect the onset of pulmonary exacerbation to provide timely and appropriate treatment before serious damage occurs. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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18 pages, 5375 KiB

Open AccessArticle

An Improved Compressive Sensing and Received Signal Strength-Based Target Localization Algorithm with Unknown Target Population for Wireless Local Area Networks

by Jun Yan¹, Kegen Yu², Ruizhi Chen^3,4

and Liang Chen^3,4,*

¹ College of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

² School of Geodesy and Geomatics and the Collaborative Innovation Center for Geospatial Technology, Wuhan University, Wuhan 430079, China

³ State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China

⁴ Collaborative Innovation Center of Geospatial Technology (INNOGST), Wuhan 430079, China

Sensors 2017, 17(6), 1246; https://doi.org/10.3390/s17061246 - 30 May 2017

Cited by 16 | Viewed by 4902

Abstract

In this paper a two-phase compressive sensing (CS) and received signal strength (RSS)-based target localization approach is proposed to improve position accuracy by dealing with the unknown target population and the effect of grid dimensions on position error. In the coarse localization phase, [...] Read more.

In this paper a two-phase compressive sensing (CS) and received signal strength (RSS)-based target localization approach is proposed to improve position accuracy by dealing with the unknown target population and the effect of grid dimensions on position error. In the coarse localization phase, by formulating target localization as a sparse signal recovery problem, grids with recovery vector components greater than a threshold are chosen as the candidate target grids. In the fine localization phase, by partitioning each candidate grid, the target position in a grid is iteratively refined by using the minimum residual error rule and the least-squares technique. When all the candidate target grids are iteratively partitioned and the measurement matrix is updated, the recovery vector is re-estimated. Threshold-based detection is employed again to determine the target grids and hence the target population. As a consequence, both the target population and the position estimation accuracy can be significantly improved. Simulation results demonstrate that the proposed approach achieves the best accuracy among all the algorithms compared. Full article

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

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18 pages, 10968 KiB

Open AccessArticle

Frequency Domain Analysis of Sensor Data for Event Classification in Real-Time Robot Assisted Deburring

by Bobby K Pappachan¹, Wahyu Caesarendra¹

, Tegoeh Tjahjowidodo^2,*

and Tomi Wijaya¹

¹ Rolls-Royce @ NTU Corporate Lab, 65 Nanyang Avenue, Singapore 637460, Singapore

² School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore

Sensors 2017, 17(6), 1247; https://doi.org/10.3390/s17061247 - 30 May 2017

Cited by 17 | Viewed by 6307

Abstract

Process monitoring using indirect methods relies on the usage of sensors. Using sensors to acquire vital process related information also presents itself with the problem of big data management and analysis. Due to uncertainty in the frequency of events occurring, a higher sampling [...] Read more.

Process monitoring using indirect methods relies on the usage of sensors. Using sensors to acquire vital process related information also presents itself with the problem of big data management and analysis. Due to uncertainty in the frequency of events occurring, a higher sampling rate is often used in real-time monitoring applications to increase the chances of capturing and understanding all possible events related to the process. Advanced signal processing methods are used to further decipher meaningful information from the acquired data. In this research work, power spectrum density (PSD) of sensor data acquired at sampling rates between 40–51.2 kHz was calculated and the corelation between PSD and completed number of cycles/passes is presented. Here, the progress in number of cycles/passes is the event this research work intends to classify and the algorithm used to compute PSD is Welch’s estimate method. A comparison between Welch’s estimate method and statistical methods is also discussed. A clear co-relation was observed using Welch’s estimate to classify the number of cycles/passes. The paper also succeeds in classifying vibration signal generated by the spindle from the vibration signal acquired during finishing process. Full article

(This article belongs to the Section Sensor Networks)

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6 pages, 1704 KiB

Open AccessCommunication

A Low-Cost System Based on Image Analysis for Monitoring the Crystal Growth Process

by Fabrício Venâncio¹, Francisca F. do Rosário² and João Cajaiba^1,*

¹ Instituto de Química, Universidade Federal do Rio de Janeiro (UFRJ), Hélio de Almeida St., 40, Cidade Universitária, Rio de Janeiro 21941-614, Brazil

² Centro de Pesquisas e Desenvolvimento Leopoldo Américo Miguez de Mello, PETROBRAS, Cidade Universitária, Rio de Janeiro 21040-000, Brazil

Sensors 2017, 17(6), 1248; https://doi.org/10.3390/s17061248 - 31 May 2017

Cited by 9 | Viewed by 4465

Abstract

Many techniques are used to monitor one or more of the phenomena involved in the crystallization process. One of the challenges in crystal growth monitoring is finding techniques that allow direct interpretation of the data. The present study used a low-cost system, composed [...] Read more.

Many techniques are used to monitor one or more of the phenomena involved in the crystallization process. One of the challenges in crystal growth monitoring is finding techniques that allow direct interpretation of the data. The present study used a low-cost system, composed of a commercial webcam and a simple white LED (Light Emitting Diode) illuminator, to follow the calcium carbonate crystal growth process. The experiments were followed with focused beam reflectance measurement (FBRM), a common technique for obtaining information about the formation and growth of crystals. The images obtained in real time were treated with the red, blue, and green (RGB) system. The results showed a qualitative response of the system to crystal formation and growth processes, as there was an observed decrease in the signal as the growth process occurred. Control of the crystal growth was managed by increasing the viscosity of the test solution with the addition of monoethylene glycol (MEG) at 30% and 70% in a mass to mass relationship, providing different profiles of the RGB average curves. The decrease in the average RGB value became slower as the concentration of MEG was increased; this reflected a lag in the growth process that was proven by the FBRM. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 1677 KiB

Open AccessArticle

Enhanced Flexibility and Reusability through State Machine-Based Architectures for Multisensor Intelligent Robotics

by Héctor Herrero^1,*

, Jose Luis Outón¹

, Mildred Puerto¹, Damien Sallé¹ and Karmele López de Ipiña²

¹ Tecnalia Research and Innovation, Industry and Transport Division, San Sebastián 20009, Spain

² Department of Systems Engineering and Automation, Universidad del País Vasco/Euskal Herriko Unibertsitatea, EleKin Research Group, San Sebastián 20009, Spain

Sensors 2017, 17(6), 1249; https://doi.org/10.3390/s17061249 - 31 May 2017

Cited by 6 | Viewed by 6784

Abstract

This paper presents a state machine-based architecture, which enhances the flexibility and reusability of industrial robots, more concretely dual-arm multisensor robots. The proposed architecture, in addition to allowing absolute control of the execution, eases the programming of new applications by increasing the reusability [...] Read more.

This paper presents a state machine-based architecture, which enhances the flexibility and reusability of industrial robots, more concretely dual-arm multisensor robots. The proposed architecture, in addition to allowing absolute control of the execution, eases the programming of new applications by increasing the reusability of the developed modules. Through an easy-to-use graphical user interface, operators are able to create, modify, reuse and maintain industrial processes, increasing the flexibility of the cell. Moreover, the proposed approach is applied in a real use case in order to demonstrate its capabilities and feasibility in industrial environments. A comparative analysis is presented for evaluating the presented approach versus traditional robot programming techniques. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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20 pages, 5579 KiB

Open AccessArticle

Electromagnetic Field Assessment as a Smart City Service: The SmartSantander Use-Case

by Luis Diez^*

, Ramón Agüero

and Luis Muñoz

Engineering Communications Department, University of Cantabria, Santander 39005, Spain

Sensors 2017, 17(6), 1250; https://doi.org/10.3390/s17061250 - 31 May 2017

Cited by 17 | Viewed by 5737

Abstract

Despite the increasing presence of wireless communications in everyday life, there exist some voices raising concerns about their adverse effects. One particularly relevant example is the potential impact of the electromagnetic field they induce on the population’s health. Traditionally, very specialized methods and [...] Read more.

Despite the increasing presence of wireless communications in everyday life, there exist some voices raising concerns about their adverse effects. One particularly relevant example is the potential impact of the electromagnetic field they induce on the population’s health. Traditionally, very specialized methods and devices (dosimetry) have been used to assess the strength of the E-field, with the main objective of checking whether it respects the corresponding regulations. In this paper, we propose a complete novel approach, which exploits the functionality leveraged by a smart city platform. We deploy a number of measuring probes, integrated as sensing devices, to carry out a characterization embracing large areas, as well as long periods of time. This unique platform has been active for more than one year, generating a vast amount of information. We process such information, and the obtained results validate the whole methodology. In addition, we discuss the variation of the E-field caused by cellular networks, considering additional information, such as usage statistics. Finally, we establish the exposure that can be attributed to the base stations within the scenario under analysis. Full article

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

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18 pages, 5314 KiB

Open AccessReview

Metallic Glass/PVDF Magnetoelectric Laminates for Resonant Sensors and Actuators: A Review

by Jon Gutiérrez^1,2,*

, Andoni Lasheras², Pedro Martins³

, Nélson Pereira³

, Jose M. Barandiarán^1,2 and Senentxu Lanceros-Mendez^1,4

¹ BCMaterials, Technology Park of Biscay, Building 500, 48160 Derio, Spain

² Departamento de Electricidad y Electrónica, Universidad del País Vasco UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain

³ Centro/Departamento de Física, Universidade do Minho, 4710-057 Braga, Portugal

⁴ IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain

Sensors 2017, 17(6), 1251; https://doi.org/10.3390/s17061251 - 31 May 2017

Cited by 62 | Viewed by 7459

Abstract

Among magnetoelectric (ME) heterostructures, ME laminates of the type Metglas-like/PVDF (magnetostrictive+piezoelectric constituents) have shown the highest induced ME voltages, usually detected at the magnetoelastic resonance of the magnetostrictive constituent. This ME coupling happens because of the high cross-correlation coupling between magnetostrictive and piezoelectric [...] Read more.

Among magnetoelectric (ME) heterostructures, ME laminates of the type Metglas-like/PVDF (magnetostrictive+piezoelectric constituents) have shown the highest induced ME voltages, usually detected at the magnetoelastic resonance of the magnetostrictive constituent. This ME coupling happens because of the high cross-correlation coupling between magnetostrictive and piezoelectric material, and is usually associated with a promising application scenario for sensors or actuators. In this work we detail the basis of the operation of such devices, as well as some arising questions (as size effects) concerning their best performance. Also, some examples of their use as very sensitive magnetic fields sensors or innovative energy harvesting devices will be reviewed. At the end, the challenges, future perspectives and technical difficulties that will determine the success of ME composites for sensor applications are discussed. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 3687 KiB

Open AccessArticle

Distributed Piezoelectric Sensor System for Damage Identification in Structures Subjected to Temperature Changes

by Jaime Vitola^1,2,†, Francesc Pozo^1,*,†

, Diego A. Tibaduiza^3,†

and Maribel Anaya^4,†

¹ Control, Dynamics and Applications (CoDAlab), Departament de Matemàtiques, Escola d’Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya (UPC), Campus Diagonal-Besòs (CDB), Eduard Maristany, 6–12, Sant Adrià de Besòs (Barcelona) 08930, Spain

² MEM (Modelling-Electronics and Monitoring Research Group), Faculty of Electronics Engineering, Universidad Santo Tomás, Bogotá 110231, Colombia

³ Departamento de Ingeniería Eléctrica y Electrónica, Universidad Nacional de Colombia, Cra 45 No. 26-85, Bogotá 111321, Colombia

⁴ Facultad de Ingeniería, Fundación Universitaria Los Libertadores, Carrera 16 No. 63A-68, Bogotá 111221, Colombia

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1252; https://doi.org/10.3390/s17061252 - 31 May 2017

Cited by 54 | Viewed by 7290

Abstract

Structural health monitoring (SHM) is a very important area in a wide spectrum of fields and engineering applications. With an SHM system, it is possible to reduce the number of non-necessary inspection tasks, the associated risk and the maintenance cost in a wide [...] Read more.

Structural health monitoring (SHM) is a very important area in a wide spectrum of fields and engineering applications. With an SHM system, it is possible to reduce the number of non-necessary inspection tasks, the associated risk and the maintenance cost in a wide range of structures during their lifetime. One of the problems in the detection and classification of damage are the constant changes in the operational and environmental conditions. Small changes of these conditions can be considered by the SHM system as damage even though the structure is healthy. Several applications for monitoring of structures have been developed and reported in the literature, and some of them include temperature compensation techniques. In real applications, however, digital processing technologies have proven their value by: (i) offering a very interesting way to acquire information from the structures under test; (ii) applying methodologies to provide a robust analysis; and (iii) performing a damage identification with a practical useful accuracy. This work shows the implementation of an SHM system based on the use of piezoelectric (PZT) sensors for inspecting a structure subjected to temperature changes. The methodology includes the use of multivariate analysis, sensor data fusion and machine learning approaches. The methodology is tested and evaluated with aluminum and composite structures that are subjected to temperature variations. Results show that damage can be detected and classified in all of the cases in spite of the temperature changes. Full article

(This article belongs to the Section Physical Sensors)

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7 pages, 2112 KiB

Open AccessArticle

A Point Temperature Sensor Based on Upconversion Emission in Er³⁺/Yb³⁺ Codoped Tellurite-Zinc-Niobium Glass

by Ting Wu, Rui Tong, Liwen Liao, Lihui Huang, Shilong Zhao^* and Shiqing Xu

College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018, China

Sensors 2017, 17(6), 1253; https://doi.org/10.3390/s17061253 - 31 May 2017

Cited by 21 | Viewed by 5442

Abstract

Er³⁺/Yb³⁺ codoped tellurite-zinc-niobium (TZNb) glass was prepared by the melt-quenching method and used for the construction of a point all-fiber temperature sensor. The glass thermal stability and network structural properties were studied by differential thermal analysis and Raman spectrum, respectively. [...] Read more.

Er³⁺/Yb³⁺ codoped tellurite-zinc-niobium (TZNb) glass was prepared by the melt-quenching method and used for the construction of a point all-fiber temperature sensor. The glass thermal stability and network structural properties were studied by differential thermal analysis and Raman spectrum, respectively. High glass transition temperature is beneficial to widen the working temperature range. The dependence of fluorescence intensity ratio (FIR) of green upconversion emissions on the surrounding temperature from 276 to 363 K was experimentally investigated and the maximum temperature sensitivity is 95 × 10⁻⁴ K⁻¹ at 363 K. Strong green upconversion emission, broad temperature measurement range and high sensitivity indicate this point temperature sensor is a promising optical device for application on optical temperature sensing. 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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18 pages, 2282 KiB

Open AccessArticle

Adaptive Estimation of Multiple Fading Factors for GPS/INS Integrated Navigation Systems

by Chen Jiang¹, Shu-Bi Zhang^1,2,* and Qiu-Zhao Zhang^1,2

¹ School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221116, China

² Collaborative Innovation Center for Resource Utilization and Ecological Restoration of Old Industrial Base, China University of Mining and Technology, Xuzhou 221116, China

Sensors 2017, 17(6), 1254; https://doi.org/10.3390/s17061254 - 1 Jun 2017

Cited by 35 | Viewed by 4140

Abstract

The Kalman filter has been widely applied in the field of dynamic navigation and positioning. However, its performance will be degraded in the presence of significant model errors and uncertain interferences. In the literature, the fading filter was proposed to control the influences [...] Read more.

The Kalman filter has been widely applied in the field of dynamic navigation and positioning. However, its performance will be degraded in the presence of significant model errors and uncertain interferences. In the literature, the fading filter was proposed to control the influences of the model errors, and the H-infinity filter can be adopted to address the uncertainties by minimizing the estimation error in the worst case. In this paper, a new multiple fading factor, suitable for the Global Positioning System (GPS) and the Inertial Navigation System (INS) integrated navigation system, is proposed based on the optimization of the filter, and a comprehensive filtering algorithm is constructed by integrating the advantages of the H-infinity filter and the proposed multiple fading filter. Measurement data of the GPS/INS integrated navigation system are collected under actual conditions. Stability and robustness of the proposed filtering algorithm are tested with various experiments and contrastive analysis are performed with the measurement data. Results demonstrate that both the filter divergence and the influences of outliers are restrained effectively with the proposed filtering algorithm, and precision of the filtering results are improved simultaneously. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 1990 KiB

Open AccessArticle

Nanoporous Gold Films Prepared by a Combination of Sputtering and Dealloying for Trace Detection of Benzo[a]pyrene Based on Surface Plasmon Resonance Spectroscopy

by Li Wang^1,2, Xiu-Mei Wan^1,2, Ran Gao¹, Dan-Feng Lu^1,* and Zhi-Mei Qi^1,*

¹ State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

² School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

Sensors 2017, 17(6), 1255; https://doi.org/10.3390/s17061255 - 1 Jun 2017

Cited by 16 | Viewed by 6036

Abstract

A wavelength-interrogated surface plasmon resonance (SPR) sensor based on a nanoporous gold (NPG) film has been fabricated for the sensitive detection of trace quantities of benzo[a]pyrene (BaP) in water. The large-area uniform NPG film was prepared by a two-step process that includes sputtering [...] Read more.

A wavelength-interrogated surface plasmon resonance (SPR) sensor based on a nanoporous gold (NPG) film has been fabricated for the sensitive detection of trace quantities of benzo[a]pyrene (BaP) in water. The large-area uniform NPG film was prepared by a two-step process that includes sputtering deposition of a 60-nm-thick AuAg alloy film on a glass substrate and chemical dealloying of the alloy film in nitric acid. For SPR sensor applications, the NPG film plays the dual roles of analyte enrichment and supporting surface plasmon waves, which leads to sensitivity enhancement. In this work, the as-prepared NPG film was first modified with 1-dodecanethiol molecules to make the film hydrophobic so as to improve BaP enrichment from water via hydrophobic interactions. The SPR sensor with the hydrophobic NPG film enables one to detect BaP at concentrations as low as 1 nmol·L⁻¹. In response to this concentration of BaP the sensor produced a resonance-wavelength shift of Δλ_R = 2.22 nm. After the NPG film was functionalized with mouse monoclonal IgG1 that is the antibody against BaP, the sensor’s sensitivity was further improved and the BaP detection limit decreased further down to 5 pmol·L⁻¹ (the corresponding Δλ_R = 1.77 nm). In contrast, the conventional SPR sensor with an antibody-functionalized dense gold film can give a response of merely Δλ_R = 0.9 nm for 100 pmol·L⁻¹ BaP. Full article

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

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19 pages, 5632 KiB

Open AccessArticle

Design and Implementation of a Hypothermic Machine Perfusion Device for Clinical Preservation of Isolated Organs

by Fei Shen

and Ruqiang Yan^*

School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

Sensors 2017, 17(6), 1256; https://doi.org/10.3390/s17061256 - 1 Jun 2017

Cited by 3 | Viewed by 6293

Abstract

The imbalance between limited organ supply and huge potential need has hindered the development of organ-graft techniques. In this paper a low-cost hypothermic machine perfusion (HMP) device is designed and implemented to maintain suitable preservation surroundings and extend the survival life of isolated [...] Read more.

The imbalance between limited organ supply and huge potential need has hindered the development of organ-graft techniques. In this paper a low-cost hypothermic machine perfusion (HMP) device is designed and implemented to maintain suitable preservation surroundings and extend the survival life of isolated organs. Four necessary elements (the machine perfusion, the physiological parameter monitoring, the thermostatic control and the oxygenation apparatus) involved in this HMP device are introduced. Especially during the thermostatic control process, a modified Bayes estimation, which introduces the concept of improvement factor, is realized to recognize and reduce the possible measurement errors resulting from sensor faults and noise interference. Also, a fuzzy-PID controller contributes to improve the accuracy and reduces the computational load using the DSP. Our experiments indicate that the reliability of the instrument meets the design requirements, thus being appealing for potential clinical preservation applications. Full article

(This article belongs to the Special Issue Intelligent Sensing and Information Mining—Selected Papers from the 10th International Conference on Sensing Technology)

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40 pages, 1815 KiB

Open AccessReview

Survey of Motion Tracking Methods Based on Inertial Sensors: A Focus on Upper Limb Human Motion

by Alessandro Filippeschi^1,*

, Norbert Schmitz², Markus Miezal³, Gabriele Bleser^2,3

, Emanuele Ruffaldi¹ and Didier Stricker²

¹ TeCIP Institute, Scuola Superiore Sant’Anna, 56127 Pisa, Italy

² German Research Center for Artificial Intelligence, 67663 Kaiserslautern, Germany

³ Junior research group wearHEALTH, Department of Computer Science, University of Kaiserslautern, 67663 Kaiserslautern, Germany

Sensors 2017, 17(6), 1257; https://doi.org/10.3390/s17061257 - 1 Jun 2017

Cited by 292 | Viewed by 24163

Abstract

Motion tracking based on commercial inertial measurements units (IMUs) has been widely studied in the latter years as it is a cost-effective enabling technology for those applications in which motion tracking based on optical technologies is unsuitable. This measurement method has a high [...] Read more.

Motion tracking based on commercial inertial measurements units (IMUs) has been widely studied in the latter years as it is a cost-effective enabling technology for those applications in which motion tracking based on optical technologies is unsuitable. This measurement method has a high impact in human performance assessment and human-robot interaction. IMU motion tracking systems are indeed self-contained and wearable, allowing for long-lasting tracking of the user motion in situated environments. After a survey on IMU-based human tracking, five techniques for motion reconstruction were selected and compared to reconstruct a human arm motion. IMU based estimation was matched against motion tracking based on the Vicon marker-based motion tracking system considered as ground truth. Results show that all but one of the selected models perform similarly (about 35 mm average position estimation error). Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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11 pages, 432 KiB

Open AccessArticle

Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks

by Bin Lyu, Zhen Yang^*, Guan Gui

and Hikmet Sari

Key Laboratory of Ministry of Education in Broadband Wireless Communication and Sensor Network Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

Sensors 2017, 17(6), 1258; https://doi.org/10.3390/s17061258 - 1 Jun 2017

Cited by 30 | Viewed by 5517

Abstract

This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly [...] Read more.

This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly divided into two parts corresponding to the data backscattering and transmission periods, respectively. The users first backscatter data to the information receiver in time division multiple access (TDMA) during the data backscattering period. When one user works in the BackCom mode, the other users harvest energy from the power station. During the data transmission period, two schemes, i.e., non-orthogonal multiple access (NOMA) and TDMA, are considered. To maximize the system throughput, the optimal time allocation policies are obtained. Simulation results demonstrate the superiority of the proposed model. Full article

(This article belongs to the Special Issue New Paradigms in Data Sensing and Processing for Edge Computing)

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8 pages, 3660 KiB

Open AccessArticle

Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber

by G. Salceda-Delgado^1,*, A. Martinez-Rios², R. Selvas-Aguilar¹, R. I. Álvarez-Tamayo³

, A. Castillo-Guzman¹, B. Ibarra-Escamilla⁴, V. M. Durán-Ramírez⁵ and L. F. Enriquez-Gomez^2,6

¹ Universidad Autónoma de Nuevo León, Pedro de Alba S/N, Ciudad Universitaria, 66455 San Nicolás de los Garza, Nuevo León, Mexico

² Centro de Investigaciones en Óptica A. C., Loma del bosque 115, Col. Lomas del Campestre, 37150 León, Gto., Mexico

³ CONACYT – Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas, 66455 San Nicolás de los Garza, Nuevo León, Mexico

⁴ Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), L. E. Erro 1, Sta. Ma. Tonantzintla, Puebla 72824, Mexico

⁵ Centro Universitario de los Lagos, Universidad de Guadalajara, Enrique Díaz de León 1144, paseos de la montaña, 47460 Lagos de Moreno, Jalisco, Mexico

⁶ Instituto Tecnológico de Aguascalientes, Avenida Adolfo López Mateos 1801, 20256 Aguascalientes, Ags., Mexico

Sensors 2017, 17(6), 1259; https://doi.org/10.3390/s17061259 - 2 Jun 2017

Cited by 26 | Viewed by 6906

Abstract

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal [...] Read more.

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 3376 KiB

Open AccessArticle

Chang’E-5T Orbit Determination Using Onboard GPS Observations

by Xing Su

, Tao Geng^*

, Wenwen Li, Qile Zhao and Xin Xie

GNSS Research Center, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

Sensors 2017, 17(6), 1260; https://doi.org/10.3390/s17061260 - 1 Jun 2017

Cited by 17 | Viewed by 4517

Abstract

In recent years, Global Navigation Satellite System (GNSS) has played an important role in Space Service Volume, the region enclosing the altitudes above 3000 km up to 36,000 km. As an in-flight test for the feasibility as well as for the performance of [...] Read more.

In recent years, Global Navigation Satellite System (GNSS) has played an important role in Space Service Volume, the region enclosing the altitudes above 3000 km up to 36,000 km. As an in-flight test for the feasibility as well as for the performance of GNSS-based satellite orbit determination (OD), the Chinese experimental lunar mission Chang’E-5T had been equipped with an onboard high-sensitivity GNSS receiver with GPS and GLONASS tracking capability. In this contribution, the 2-h onboard GPS data are evaluated in terms of tracking performance as well as observation quality. It is indicated that the onboard receiver can track 7–8 GPS satellites per epoch on average and the ratio of carrier to noise spectral density (C/N0) values are higher than 28 dB-Hz for 90% of all the observables. The C1 code errors are generally about 4.15 m but can be better than 2 m with C/N0 values over 36 dB-Hz. GPS-based Chang’E-5T OD is performed and the Helmert variance component estimation method is investigated to determine the weights of code and carrier phase observations. The results reveal that the orbit consistency is about 20 m. OD is furthermore analyzed with GPS data screened out according to different C/N0 thresholds. It is indicated that for the Chang’E-5T, the precision of OD is dominated by the number of observed satellite. Although increased C/N0 thresholds can improve the overall data quality, the available number of GPS observations is greatly reduced and the resulting orbit solution is poor. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 3269 KiB

Open AccessArticle

Classification of K-Pop Dance Movements Based on Skeleton Information Obtained by a Kinect Sensor

by Dohyung Kim¹, Dong-Hyeon Kim² and Keun-Chang Kwak^2,*

¹ Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea

² Department of Control and Instrumentation Engineering, Chosun University, Gwangju 61452, Korea

Sensors 2017, 17(6), 1261; https://doi.org/10.3390/s17061261 - 1 Jun 2017

Cited by 36 | Viewed by 13150

Abstract

This paper suggests a method of classifying Korean pop (K-pop) dances based on human skeletal motion data obtained from a Kinect sensor in a motion-capture studio environment. In order to accomplish this, we construct a K-pop dance database with a total of 800 [...] Read more.

This paper suggests a method of classifying Korean pop (K-pop) dances based on human skeletal motion data obtained from a Kinect sensor in a motion-capture studio environment. In order to accomplish this, we construct a K-pop dance database with a total of 800 dance-movement data points including 200 dance types produced by four professional dancers, from skeletal joint data obtained by a Kinect sensor. Our classification of movements consists of three main steps. First, we obtain six core angles representing important motion features from 25 markers in each frame. These angles are concatenated with feature vectors for all of the frames of each point dance. Then, a dimensionality reduction is performed with a combination of principal component analysis and Fisher’s linear discriminant analysis, which is called fisherdance. Finally, we design an efficient Rectified Linear Unit (ReLU)-based Extreme Learning Machine Classifier (ELMC) with an input layer composed of these feature vectors transformed by fisherdance. In contrast to conventional neural networks, the presented classifier achieves a rapid processing time without implementing weight learning. The results of experiments conducted on the constructed K-pop dance database reveal that the proposed method demonstrates a better classification performance than those of conventional methods such as KNN (K-Nearest Neighbor), SVM (Support Vector Machine), and ELM alone. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 4340 KiB

Open AccessArticle

Structural Health Monitoring for a Z-Type Special Vehicle

by Chaolin Yuan¹, Liang Ren^1,*

and Hongnan Li^1,2

¹ State Key Lab of Offshore and Coastal Engineering, Dalian University of Technology, Dalian 116024, China

² School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

Sensors 2017, 17(6), 1262; https://doi.org/10.3390/s17061262 - 1 Jun 2017

Cited by 7 | Viewed by 5378

Abstract

Nowadays there exist various kinds of special vehicles designed for some purposes, which are different from regular vehicles in overall dimension and design. In that case, accidents such as overturning will lead to large economical loss and casualties. There are still no technical [...] Read more.

Nowadays there exist various kinds of special vehicles designed for some purposes, which are different from regular vehicles in overall dimension and design. In that case, accidents such as overturning will lead to large economical loss and casualties. There are still no technical specifications to follow to ensure the safe operation and driving of these special vehicles. Owing to the poor efficiency of regular maintenance, it is more feasible and effective to apply real-time monitoring during the operation and driving process. In this paper, the fiber Bragg grating (FBG) sensors are used to monitor the safety of a z-type special vehicle. Based on the structural features and force distribution, a reasonable structural health monitoring (SHM) scheme is presented. Comparing the monitoring results with the finite element simulation results guarantees the accuracy and reliability of the monitoring results. Large amounts of data are collected during the operation and driving progress to evaluate the structural safety condition and provide reference for SHM systems developed for other special vehicles. Full article

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

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14 pages, 2362 KiB

Open AccessArticle

Comparative Study of Neural Network Frameworks for the Next Generation of Adaptive Optics Systems

by Carlos González-Gutiérrez¹

, Jesús Daniel Santos^2,*

, Mario Martínez-Zarzuela³

, Alistair G. Basden⁴

, James Osborn⁴, Francisco Javier Díaz-Pernas³ and Francisco Javier De Cos Juez¹

¹ Mining Exploitation and Prospecting Department, University of Oviedo, 33004 Oviedo, Spain

² Department of Physics, University of Oviedo, 33004 Oviedo, Spain

³ Department of Signal Theory and Communications and Telematics Engineering, University of Valladolid, 47011 Valladolid, Spain

⁴ Department of Physics, Centre for Advanced Instrumentation, University of Durham, South Road, Durham DH1 3LE, UK

Sensors 2017, 17(6), 1263; https://doi.org/10.3390/s17061263 - 2 Jun 2017

Cited by 22 | Viewed by 4494

Abstract

Many of the next generation of adaptive optics systems on large and extremely large telescopes require tomographic techniques in order to correct for atmospheric turbulence over a large field of view. Multi-object adaptive optics is one such technique. In this paper, different implementations [...] Read more.

Many of the next generation of adaptive optics systems on large and extremely large telescopes require tomographic techniques in order to correct for atmospheric turbulence over a large field of view. Multi-object adaptive optics is one such technique. In this paper, different implementations of a tomographic reconstructor based on a machine learning architecture named “CARMEN” are presented. Basic concepts of adaptive optics are introduced first, with a short explanation of three different control systems used on real telescopes and the sensors utilised. The operation of the reconstructor, along with the three neural network frameworks used, and the developed CUDA code are detailed. Changes to the size of the reconstructor influence the training and execution time of the neural network. The native CUDA code turns out to be the best choice for all the systems, although some of the other frameworks offer good performance under certain circumstances. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 3662 KiB

Open AccessArticle

Analysis and Validation of Contactless Time-Gated Interrogation Technique for Quartz Resonator Sensors

by Marco Baù^1,*

, Marco Ferrari^1,2

and Vittorio Ferrari^1,2

¹ Department of Information Engineering, University of Brescia, Via Branze 38, Brescia 25123, Italy

² INO-CNR (National Research Council), Via Branze 45, Brescia 25123, Italy

Sensors 2017, 17(6), 1264; https://doi.org/10.3390/s17061264 - 2 Jun 2017

Cited by 26 | Viewed by 5416

Abstract

A technique for contactless electromagnetic interrogation of AT-cut quartz piezoelectric resonator sensors is proposed based on a primary coil electromagnetically air-coupled to a secondary coil connected to the electrodes of the resonator. The interrogation technique periodically switches between interleaved excitation and detection phases. [...] Read more.

A technique for contactless electromagnetic interrogation of AT-cut quartz piezoelectric resonator sensors is proposed based on a primary coil electromagnetically air-coupled to a secondary coil connected to the electrodes of the resonator. The interrogation technique periodically switches between interleaved excitation and detection phases. During the excitation phase, the resonator is set into vibration by a driving voltage applied to the primary coil, whereas in the detection phase, the excitation signal is turned off and the transient decaying response of the resonator is sensed without contact by measuring the voltage induced back across the primary coil. This approach ensures that the readout frequency of the sensor signal is to a first order approximation independent of the interrogation distance between the primary and secondary coils. A detailed theoretical analysis of the interrogation principle based on a lumped-element equivalent circuit is presented. The analysis has been experimentally validated on a 4.432 MHz AT-cut quartz crystal resonator, demonstrating the accurate readout of the series resonant frequency and quality factor over an interrogation distance of up to 2 cm. As an application, the technique has been applied to the measurement of liquid microdroplets deposited on a 4.8 MHz AT-cut quartz crystal. More generally, the proposed technique can be exploited for the measurement of any physical or chemical quantities affecting the resonant response of quartz resonator sensors. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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33 pages, 3895 KiB

Open AccessArticle

Towards Citizen Co-Created Public Service Apps

by Mikel Emaldi^1,*

, Unai Aguilera¹

, Diego López-de-Ipiña¹

and Jorge Pérez-Velasco²

¹ DeustoTech - Deusto Foundation, University of Deusto, Avda. Universidades, 24, 48007 Bilbao, Spain

² Tecnalia, eServices, Calle de Velázquez, 64-66, 28001 Madrid, Spain

Sensors 2017, 17(6), 1265; https://doi.org/10.3390/s17061265 - 2 Jun 2017

Cited by 16 | Viewed by 5296

Abstract

WeLive project’s main objective is about transforming the current e-government approach by providing a new paradigm based on a new open model oriented towards the design, production and deployment of public services and mobile apps based on the collaboration of different stakeholders. These [...] Read more.

WeLive project’s main objective is about transforming the current e-government approach by providing a new paradigm based on a new open model oriented towards the design, production and deployment of public services and mobile apps based on the collaboration of different stakeholders. These stakeholders form the quadruple helix, i.e., citizens, private companies, research institutes and public administrations. Through the application of open innovation, open data and open services paradigms, the framework developed within the WeLive project enables the co-creation of urban apps. In this paper, we extend the description of the WeLive platform presented at , plus the preliminary results of the first pilot phase. The two-phase evaluation methodology designed and the evaluation results of first pilot sub-phase are also presented. Full article

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

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12 pages, 3255 KiB

Open AccessArticle

Innovative High-Throughput SAXS Methodologies Based on Photonic Lab-on-a-Chip Sensors: Application to Macromolecular Studies

by Isaac Rodríguez-Ruiz¹

, Dimitri Radajewski², Sophie Charton¹

, Nhat Phamvan², Martha Brennich³, Petra Pernot³, Françoise Bonneté⁴

and Sébastien Teychené^2,*

¹ CEA, DEN, DMRC, SA2I, 30207 Bagnols-sur-Cèze, France

² Laboratoire de Génie Chimique, UMR 5503, 4 allée Emile Monso, 31432 Toulouse, France

³ European Molecular Biology Laboratory, 71 avenue des Martyrs, 38000 Grenoble, France

⁴ Institut des Biomolécules Max-Mousseron, UMR 5247, Université d’Avignon, 33 rue Louis Pasteur, 84000 Avignon, France

Sensors 2017, 17(6), 1266; https://doi.org/10.3390/s17061266 - 2 Jun 2017

Cited by 20 | Viewed by 5683

Abstract

The relevance of coupling droplet-based Photonic Lab-on-a-Chip (PhLoC) platforms and Small-Angle X-Ray Scattering (SAXS) technique is here highlighted for the performance of high throughput investigations, related to the study of protein macromolecular interactions. With this configuration, minute amounts of sample are required to [...] Read more.

The relevance of coupling droplet-based Photonic Lab-on-a-Chip (PhLoC) platforms and Small-Angle X-Ray Scattering (SAXS) technique is here highlighted for the performance of high throughput investigations, related to the study of protein macromolecular interactions. With this configuration, minute amounts of sample are required to obtain reliable statistical data. The PhLoC platforms presented in this work are designed to allow and control an effective mixing of precise amounts of proteins, crystallization reagents and buffer in nanoliter volumes, and the subsequent generation of nanodroplets by means of a two-phase flow. Spectrophotometric sensing permits a fine control on droplet generation frequency and stability as well as on concentration conditions, and finally the droplet flow is synchronized to perform synchrotron radiation SAXS measurements in individual droplets (each one acting as an isolated microreactor) to probe protein interactions. With this configuration, droplet physic-chemical conditions can be reproducibly and finely tuned, and monitored without cross-contamination, allowing for the screening of a substantial number of saturation conditions with a small amount of biological material. The setup was tested and validated using lysozyme as a model of study. By means of SAXS experiments, the proteins gyration radius and structure envelope were calculated as a function of protein concentration. The obtained values were found to be in good agreement with previously reported data, but with a dramatic reduction of sample volume requirements compared to studies reported in the literature. Full article

(This article belongs to the Special Issue Microfluidic Sensors and Control Devices)

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20 pages, 451 KiB

Open AccessArticle

A Lifetime Maximization Relay Selection Scheme in Wireless Body Area Networks

by Yu Zhang, Bing Zhang^* and Shi Zhang

State Key Laboratory of Integrated Services Networks, Xidian University, Xi’an 710071, China

Sensors 2017, 17(6), 1267; https://doi.org/10.3390/s17061267 - 2 Jun 2017

Cited by 28 | Viewed by 6103

Abstract

Network Lifetime is one of the most important metrics in Wireless Body Area Networks (WBANs). In this paper, a relay selection scheme is proposed under the topology constrains specified in the IEEE 802.15.6 standard to maximize the lifetime of WBANs through formulating and [...] Read more.

Network Lifetime is one of the most important metrics in Wireless Body Area Networks (WBANs). In this paper, a relay selection scheme is proposed under the topology constrains specified in the IEEE 802.15.6 standard to maximize the lifetime of WBANs through formulating and solving an optimization problem where relay selection of each node acts as optimization variable. Considering the diversity of the sensor nodes in WBANs, the optimization problem takes not only energy consumption rate but also energy difference among sensor nodes into account to improve the network lifetime performance. Since it is Non-deterministic Polynomial-hard (NP-hard) and intractable, a heuristic solution is then designed to rapidly address the optimization. The simulation results indicate that the proposed relay selection scheme has better performance in network lifetime compared with existing algorithms and that the heuristic solution has low time complexity with only a negligible performance degradation gap from optimal value. Furthermore, we also conduct simulations based on a general WBAN model to comprehensively illustrate the advantages of the proposed algorithm. At the end of the evaluation, we validate the feasibility of our proposed scheme via an implementation discussion. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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24 pages, 16894 KiB

Open AccessArticle

A LiDAR and IMU Integrated Indoor Navigation System for UAVs and Its Application in Real-Time Pipeline Classification

by G. Ajay Kumar, Ashok Kumar Patil

, Rekha Patil, Seong Sill Park and Young Ho Chai^*

Graduate School of Advanced Imaging Science, Multimedia and Film Chung-Ang University, Seoul 156-756, Korea

Sensors 2017, 17(6), 1268; https://doi.org/10.3390/s17061268 - 2 Jun 2017

Cited by 138 | Viewed by 21183

Abstract

Mapping the environment of a vehicle and localizing a vehicle within that unknown environment are complex issues. Although many approaches based on various types of sensory inputs and computational concepts have been successfully utilized for ground robot localization, there is difficulty in localizing [...] Read more.

Mapping the environment of a vehicle and localizing a vehicle within that unknown environment are complex issues. Although many approaches based on various types of sensory inputs and computational concepts have been successfully utilized for ground robot localization, there is difficulty in localizing an unmanned aerial vehicle (UAV) due to variation in altitude and motion dynamics. This paper proposes a robust and efficient indoor mapping and localization solution for a UAV integrated with low-cost Light Detection and Ranging (LiDAR) and Inertial Measurement Unit (IMU) sensors. Considering the advantage of the typical geometric structure of indoor environments, the planar position of UAVs can be efficiently calculated from a point-to-point scan matching algorithm using measurements from a horizontally scanning primary LiDAR. The altitude of the UAV with respect to the floor can be estimated accurately using a vertically scanning secondary LiDAR scanner, which is mounted orthogonally to the primary LiDAR. Furthermore, a Kalman filter is used to derive the 3D position by fusing primary and secondary LiDAR data. Additionally, this work presents a novel method for its application in the real-time classification of a pipeline in an indoor map by integrating the proposed navigation approach. Classification of the pipeline is based on the pipe radius estimation considering the region of interest (ROI) and the typical angle. The ROI is selected by finding the nearest neighbors of the selected seed point in the pipeline point cloud, and the typical angle is estimated with the directional histogram. Experimental results are provided to determine the feasibility of the proposed navigation system and its integration with real-time application in industrial plant engineering. Full article

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

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22 pages, 963 KiB

Open AccessArticle

Computationally Efficient Direction Finding for a Mixture of Circular and Strictly Noncircular Sources with Uniform Rectangular Arrays

by Qing Wang¹, Xiaotian Zhu¹, Hua Chen^2,*, Laihua Wang³, Weiqing Yan⁴ and Haoyu Fang¹

¹ School of Electrical Information Engineering, Tianjin University, 92 Weijin Road, Tianjin 300072, China

² Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China

³ School of Software, Qufu Normal University, Qufu 273165, China

⁴ School of Computer and Control Engineering, Yantai University, Yantai 264005, China

Sensors 2017, 17(6), 1269; https://doi.org/10.3390/s17061269 - 2 Jun 2017

Cited by 4 | Viewed by 4062

Abstract

In this paper, a novel two-dimensional (2D) direction-of-arrival (DOA) estimation algorithm for the mixed circular and strictly noncircular sources is proposed. A general array model with a mixture of signals is firstly built based on uniform rectangular arrays (URAs), and then, the approach, [...] Read more.

In this paper, a novel two-dimensional (2D) direction-of-arrival (DOA) estimation algorithm for the mixed circular and strictly noncircular sources is proposed. A general array model with a mixture of signals is firstly built based on uniform rectangular arrays (URAs), and then, the approach, which uses the rank-reduction-based ROOT-MUSIC, can solve 2D DOA estimation problem. Besides, the theoretical error of the proposed algorithm, a criterion of the performance for evaluation, is analyzed by the first-order Taylor expression using second-order statistics. As verified by the simulation results, a better DOA estimation performance and a lower computational complexity are achieved by the proposed algorithm than the existing methods resorting to the noncircularity of the incoming signals. 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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12 pages, 3811 KiB

Open AccessArticle

Investigation of Azimuth Multichannel Reconstruction for Moving Targets in High Resolution Wide Swath SAR

by Weixian Tan^1,2,*, Wei Xu³, Pingping Huang^1,2

, Zengshu Huang⁴, Yaolong Qi⁴ and Kuoye Han⁵

¹ College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China

² Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China

³ Department of Spaceborne Microwave Remote Sensing, Institute of Electronics, Chinese Academy of Sciences (IECAS), Beijing 100190, China

⁴ Electronics & Information Engineering, Beihang University, Beijing 100191, China

⁵ China Electronics Technology Group Corporation, Information Science Academy, Beijing 100098, China

Sensors 2017, 17(6), 1270; https://doi.org/10.3390/s17061270 - 2 Jun 2017

Cited by 15 | Viewed by 4138

Abstract

The azimuth multichannel imaging scheme with the large receive antenna divided into multiple sub-apertures usually leads to azimuth non-uniform sampling, and echoes from all azimuth channels should be reconstructed based on the signal model before conventional SAR imaging. Unfortunately, the multichannel signal model [...] Read more.

The azimuth multichannel imaging scheme with the large receive antenna divided into multiple sub-apertures usually leads to azimuth non-uniform sampling, and echoes from all azimuth channels should be reconstructed based on the signal model before conventional SAR imaging. Unfortunately, the multichannel signal model of a moving target is different from that of a fixed target. This paper analyzes the multichannel signal model of the moving target and the effect of the target velocity on azimuth multichannel reconstruction. Based on the multichannel signal mode of the moving target, a new multichannel signal reconstruction algorithm is proposed. Furthermore, the slant range velocity is estimated by computing signal energy distribution. Simulation results on point targets validate the proposed approach. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 4172 KiB

Open AccessArticle

Magnetoelectric Current Sensors

by Mirza Bichurin^*, Roman Petrov

, Viktor Leontiev, Gennadiy Semenov and Oleg Sokolov

Department of Design and Technology of Radioequipment, Novgorod State University, Veliky Novgorod 173003, Russia

Sensors 2017, 17(6), 1271; https://doi.org/10.3390/s17061271 - 2 Jun 2017

Cited by 61 | Viewed by 8215

Abstract

In this work a magnetoelectric (ME) current sensor design based on a magnetoelectric effect is presented and discussed. The resonant and non-resonant type of ME current sensors are considered. Theoretical calculations of the ME current sensors by the equivalent circuit method were conducted. [...] Read more.

In this work a magnetoelectric (ME) current sensor design based on a magnetoelectric effect is presented and discussed. The resonant and non-resonant type of ME current sensors are considered. Theoretical calculations of the ME current sensors by the equivalent circuit method were conducted. The application of different sensors using the new effects, for example, the ME effect, is made possible with the development of new ME composites. A large number of studies conducted in the field of new composites, allowed us to obtain a high magnetostrictive-piezoelectric laminate sensitivity. An optimal ME structure composition was matched. The characterization of a non-resonant current sensor showed that in the operation range to 5 A, the sensor had a sensitivity of 0.34 V/A, non-linearity less than 1% and for a resonant current sensor in the same operation range, the sensitivity was of 0.53 V/A, non-linearity less than 0.5%. Full article

(This article belongs to the Special Issue Magnetoelectric Heterostructures and Sensors)

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18 pages, 7134 KiB

Open AccessArticle

A Map/INS/Wi-Fi Integrated System for Indoor Location-Based Service Applications

by Chunyang Yu^1,2,*, Haiyu Lan², Fuqiang Gu³

, Fei Yu¹ and Naser El-Sheimy²

¹ College of Automation, Harbin Engineering University, Harbin 150001, China

² Department of Geomatics, University of Calgary, Calgary, AB T2N 1N4, Canada

³ Infrastructure Engineering, University of Melbourne, Melbourne, VIC 3010, Australia

Sensors 2017, 17(6), 1272; https://doi.org/10.3390/s17061272 - 2 Jun 2017

Cited by 40 | Viewed by 6217

Abstract

In this research, a new Map/INS/Wi-Fi integrated system for indoor location-based service (LBS) applications based on a cascaded Particle/Kalman filter framework structure is proposed. Two-dimension indoor map information, together with measurements from an inertial measurement unit (IMU) and Received Signal Strength Indicator (RSSI) [...] Read more.

In this research, a new Map/INS/Wi-Fi integrated system for indoor location-based service (LBS) applications based on a cascaded Particle/Kalman filter framework structure is proposed. Two-dimension indoor map information, together with measurements from an inertial measurement unit (IMU) and Received Signal Strength Indicator (RSSI) value, are integrated for estimating positioning information. The main challenge of this research is how to make effective use of various measurements that complement each other in order to obtain an accurate, continuous, and low-cost position solution without increasing the computational burden of the system. Therefore, to eliminate the cumulative drift caused by low-cost IMU sensor errors, the ubiquitous Wi-Fi signal and non-holonomic constraints are rationally used to correct the IMU-derived navigation solution through the extended Kalman Filter (EKF). Moreover, the map-aiding method and map-matching method are innovatively combined to constrain the primary Wi-Fi/IMU-derived position through an Auxiliary Value Particle Filter (AVPF). Different sources of information are incorporated through a cascaded structure EKF/AVPF filter algorithm. Indoor tests show that the proposed method can effectively reduce the accumulation of positioning errors of a stand-alone Inertial Navigation System (INS), and provide a stable, continuous and reliable indoor location service. Full article

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

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19 pages, 1842 KiB

Open AccessArticle

A Robust 96.6-dB-SNDR 50-kHz-Bandwidth Switched-Capacitor Delta-Sigma Modulator for IR Imagers in Space Instrumentation

by Michele Dei^1,*

, Stepan Sutula¹, Jose Cisneros¹, Ernesto Pun², Richard Jan Engel Jansen³, Lluís Terés^1,4 and Francisco Serra-Graells^1,4

¹ Instituto de Microelectrónica de Barcelona IMB-CNM(CSIC), 08193 Barcelona, Spain

² Arquimea Ingenierìa S.L.U., 28918 Madrid, Spain

³ European Space Research and Technology Centre, 2201 AG Noordwijk, The Netherlands

⁴ Department of Microelectronics and Electronic Systems of Universitat Autònoma de Barcelona, 08193 Barcelona, Spain

Sensors 2017, 17(6), 1273; https://doi.org/10.3390/s17061273 - 2 Jun 2017

Cited by 3 | Viewed by 7584

Abstract

Infrared imaging technology, used both to study deep-space bodies’ radiation and environmental changes on Earth, experienced constant improvements in the last few years, pushing data converter designers to face new challenges in terms of speed, power consumption and robustness against extremely harsh operating [...] Read more.

Infrared imaging technology, used both to study deep-space bodies’ radiation and environmental changes on Earth, experienced constant improvements in the last few years, pushing data converter designers to face new challenges in terms of speed, power consumption and robustness against extremely harsh operating conditions. This paper presents a 96.6-dB-SNDR (Signal-to-Noise-plus-Distortion Ratio) 50-kHz-bandwidth fourth-order single-bit switched-capacitor delta-sigma modulator for ADC operating at 1.8 V and consuming 7.9 mW ﬁt for space instrumentation. The circuit features novel Class-AB single-stage switched variable-mirror ampliﬁers (SVMAs) enabling low-power operation, as well as low sensitivity to both process and temperature deviations for the whole modulator. The physical implementation resulted in a 1.8-mm²chip integrated in a standard 0.18-µm 1-poly-6-metal (1P6M) CMOS technology, and it reaches a 164.6-dB Schreier ﬁgure of merit from experimental SNDR measurements without making use of any clock bootstrapping,analogcalibration,nordigitalcompensationtechnique. Whencoupledtoa2048×2048 IR imager, the current design allows more than 50 frames per minute with a resolution of 16 effective number of bits (ENOB) while consuming less than 300 mW. Full article

(This article belongs to the Special Issue Infrared Detectors)

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11 pages, 2125 KiB

Open AccessArticle

Research and Analysis on the Localization of a 3-D Single Source in Lossy Medium Using Uniform Circular Array

by Bing Xue^1,2, Xiaodong Qu^1,2,*, Guangyou Fang^1,2 and Yicai Ji^1,2

¹ Key Laboratory of Electromagnetic Radiation and Sensing Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

² University of Chinese Academy of Sciences, Beijing 100039, China

Sensors 2017, 17(6), 1274; https://doi.org/10.3390/s17061274 - 2 Jun 2017

Cited by 1 | Viewed by 3992

Abstract

In this paper, the methods and analysis for estimating the location of a three-dimensional (3-D) single source buried in lossy medium are presented with uniform circular array (UCA). The mathematical model of the signal in the lossy medium is proposed. Using information in [...] Read more.

In this paper, the methods and analysis for estimating the location of a three-dimensional (3-D) single source buried in lossy medium are presented with uniform circular array (UCA). The mathematical model of the signal in the lossy medium is proposed. Using information in the covariance matrix obtained by the sensors’ outputs, equations of the source location (azimuth angle, elevation angle, and range) are obtained. Then, the phase and amplitude of the covariance matrix function are used to process the source localization in the lossy medium. By analyzing the characteristics of the proposed methods and the multiple signal classification (MUSIC) method, the computational complexity and the valid scope of these methods are given. From the results, whether the loss is known or not, we can choose the best method for processing the issues (localization in lossless medium or lossy medium). 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, 2345 KiB

Open AccessArticle

Indoor Trajectory Tracking Scheme Based on Delaunay Triangulation and Heuristic Information in Wireless Sensor Networks

by Junping Qin^1,2, Shiwen Sun², Qingxu Deng^1,*, Limin Liu² and Yonghong Tian²

¹ School of Computer Science and Engineering, Northeastern University, Shenyang 110819, China

² College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010080, China

Sensors 2017, 17(6), 1275; https://doi.org/10.3390/s17061275 - 2 Jun 2017

Cited by 10 | Viewed by 5464

Abstract

Object tracking and detection is one of the most significant research areas for wireless sensor networks. Existing indoor trajectory tracking schemes in wireless sensor networks are based on continuous localization and moving object data mining. Indoor trajectory tracking based on the received signal [...] Read more.

Object tracking and detection is one of the most significant research areas for wireless sensor networks. Existing indoor trajectory tracking schemes in wireless sensor networks are based on continuous localization and moving object data mining. Indoor trajectory tracking based on the received signal strength indicator (RSSI) has received increased attention because it has low cost and requires no special infrastructure. However, RSSI tracking introduces uncertainty because of the inaccuracies of measurement instruments and the irregularities (unstable, multipath, diffraction) of wireless signal transmissions in indoor environments. Heuristic information includes some key factors for trajectory tracking procedures. This paper proposes a novel trajectory tracking scheme based on Delaunay triangulation and heuristic information (TTDH). In this scheme, the entire field is divided into a series of triangular regions. The common side of adjacent triangular regions is regarded as a regional boundary. Our scheme detects heuristic information related to a moving object’s trajectory, including boundaries and triangular regions. Then, the trajectory is formed by means of a dynamic time-warping position-fingerprint-matching algorithm with heuristic information constraints. Field experiments show that the average error distance of our scheme is less than 1.5 m, and that error does not accumulate among the regions. Full article

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

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8 pages, 2427 KiB

Open AccessArticle

Fluorometric Index for Sensing Oil in the Sea Environment

by Emilia Baszanowska and Zbigniew Otremba^*

Physics Department, Gdynia Maritime University, 81-225 Gdynia, Poland

Sensors 2017, 17(6), 1276; https://doi.org/10.3390/s17061276 - 2 Jun 2017

Cited by 18 | Viewed by 4281

Abstract

Excitation-emission matrix spectroscopy (EEMS) was applied to determine the fluorometric index (FI) as a parameter indicating the presence of a source of oil pollution in a specific area of the sea. Seawater from the Polish coast (the Baltic Sea) and the same water [...] Read more.

Excitation-emission matrix spectroscopy (EEMS) was applied to determine the fluorometric index (FI) as a parameter indicating the presence of a source of oil pollution in a specific area of the sea. Seawater from the Polish coast (the Baltic Sea) and the same water combined with various amounts of crude oil extracted from the Baltic Sea shelf (Petrobaltic-type oil) were used in this study. The FI values were calculated for excitation and emission wavelengths found at the maximal peak, taking into account the natural seawater and the seawater artificially contaminated (for an oil-to-water ratio range of 0.5 × 10⁻⁶ − 500 × 10⁻⁶). The wavelength configurations (Ex/Em) (225/355 and 225/340) for the FI index were applied. It was found that, independent of the amount of oil, the FI achieves a higher value for natural seawater than for seawater that has had contact with oil. These results provide the basis to design a sensor signaling the appearance of oil in a defined sea area. Full article

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

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39 pages, 374 KiB

Open AccessReview

A Review of Activity Trackers for Senior Citizens: Research Perspectives, Commercial Landscape and the Role of the Insurance Industry

by Salvatore Tedesco^*

, John Barton

and Brendan O’Flynn

Tyndall National Institute, University College Cork/Lee Maltings, Prospect Row, Cork T12R5CP, Ireland

Sensors 2017, 17(6), 1277; https://doi.org/10.3390/s17061277 - 3 Jun 2017

Cited by 107 | Viewed by 18160

Abstract

The objective assessment of physical activity levels through wearable inertial-based motion detectors for the automatic, continuous and long-term monitoring of people in free-living environments is a well-known research area in the literature. However, their application to older adults can present particular constraints. This [...] Read more.

The objective assessment of physical activity levels through wearable inertial-based motion detectors for the automatic, continuous and long-term monitoring of people in free-living environments is a well-known research area in the literature. However, their application to older adults can present particular constraints. This paper reviews the adoption of wearable devices in senior citizens by describing various researches for monitoring physical activity indicators, such as energy expenditure, posture transitions, activity classification, fall detection and prediction, gait and balance analysis, also by adopting consumer-grade fitness trackers with the associated limitations regarding acceptability. This review also describes and compares existing commercial products encompassing activity trackers tailored for older adults, thus providing a comprehensive outlook of the status of commercially available motion tracking systems. Finally, the impact of wearable devices on life and health insurance companies, with a description of the potential benefits for the industry and the wearables market, was analyzed as an example of the potential emerging market drivers for such technology in the future. Full article

(This article belongs to the Section Physical Sensors)

10 pages, 3262 KiB

Open AccessArticle

Air Flow Detection in Crude Oil by Infrared Light

by Guilherme Dutra¹

, Cicero Martelli^1,2,*, Marco José Da Silva^1,4, Rodolfo L. Patyk¹ and Rigoberto E. M. Morales^3,4

¹ Graduate Program in Electrical and Computer Engineering (CPGEI), Federal University of Technology-PR, Curitiba 80230-901, Brazil

² Department of Electronics, Federal University of Technology-PR, Curitiba 80230-901, Brazil

³ Graduate Program in Mechanical and Materials Engineering (PPGEM), Federal University of Technology-PR, Curitiba 80230-901, Brazil

⁴ Multiphase Flow Research Center (NUEM), Federal University of Technology-PR, Curitiba 80230-901, Brazil

Sensors 2017, 17(6), 1278; https://doi.org/10.3390/s17061278 - 3 Jun 2017

Cited by 12 | Viewed by 6935

Abstract

In this paper, we used infrared light in the range of 8–12 μm to develop and test an optical imaging system to detect air bubbles flowing in oil. The system basically comprises a broadband light source and a 31 × 32 thermopile array [...] Read more.

In this paper, we used infrared light in the range of 8–12 μm to develop and test an optical imaging system to detect air bubbles flowing in oil. The system basically comprises a broadband light source and a 31 × 32 thermopile array to generate images. To analyze the effects related to light absorption, reflection, and refraction on air-oil boundaries, a numerical model was developed and the predominance of the refraction instead of the absorption in bubbles with diameters below a certain critical value was observed. The IR region of the electromagnetic spectrum has both optical and thermic behavior. To understand the limits of each effect on the oil flow imaging, a study of the influence of temperature variation on the petroleum optical detection was performed. The developed optical imaging system allowed the detection of air flow in static oil and in oil-air two-phase flow. With the presented system, it was possible to achieve images through up to 12 mm of oil volumes, but this may be enhanced by the use of optimized IR sources and detectors. Full article

(This article belongs to the Special Issue Infrared Detectors)

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27 pages, 7188 KiB

Open AccessReview

Resonance-Based Sparse Signal Decomposition and its Application in Mechanical Fault Diagnosis: A Review

by Wentao Huang^*, Hongjian Sun and Weijie Wang

School of Mechatronics Engineering, Harbin Institute of Technology, No. 92 Xidazhi Street, Harbin 150001, China

Sensors 2017, 17(6), 1279; https://doi.org/10.3390/s17061279 - 3 Jun 2017

Cited by 34 | Viewed by 6051

Abstract

Mechanical equipment is the heart of industry. For this reason, mechanical fault diagnosis has drawn considerable attention. In terms of the rich information hidden in fault vibration signals, the processing and analysis techniques of vibration signals have become a crucial research issue in [...] Read more.

Mechanical equipment is the heart of industry. For this reason, mechanical fault diagnosis has drawn considerable attention. In terms of the rich information hidden in fault vibration signals, the processing and analysis techniques of vibration signals have become a crucial research issue in the field of mechanical fault diagnosis. Based on the theory of sparse decomposition, Selesnick proposed a novel nonlinear signal processing method: resonance-based sparse signal decomposition (RSSD). Since being put forward, RSSD has become widely recognized, and many RSSD-based methods have been developed to guide mechanical fault diagnosis. This paper attempts to summarize and review the theoretical developments and application advances of RSSD in mechanical fault diagnosis, and to provide a more comprehensive reference for those interested in RSSD and mechanical fault diagnosis. Followed by a brief introduction of RSSD’s theoretical foundation, based on different optimization directions, applications of RSSD in mechanical fault diagnosis are categorized into five aspects: original RSSD, parameter optimized RSSD, subband optimized RSSD, integrated optimized RSSD, and RSSD combined with other methods. On this basis, outstanding issues in current RSSD study are also pointed out, as well as corresponding instructional solutions. We hope this review will provide an insightful reference for researchers and readers who are interested in RSSD and mechanical fault diagnosis. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 911 KiB

Open AccessArticle

A Spawn Mobile Agent Itinerary Planning Approach for Energy-Efficient Data Gathering in Wireless Sensor Networks

by Huthiafa Q. Qadori^*,†, Zuriati A. Zulkarnain^*,†, Zurina Mohd Hanapi^†

and Shamala Subramaniam^†

¹ Department of Wireless and Communication Technology, Faculty of Computer Science and Information Technolog, University Putra Malaysia, Serdang 43400, Malaysia

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1280; https://doi.org/10.3390/s17061280 - 3 Jun 2017

Cited by 24 | Viewed by 4784

Abstract

Mobile agent (MA), a part of the mobile computing paradigm, was recently proposed for data gathering in Wireless Sensor Networks (WSNs). The MA-based approach employs two algorithms: Single-agent Itinerary Planning (SIP) and Multi-mobile agent Itinerary Planning (MIP) for energy-efficient data gathering. The MIP [...] Read more.

Mobile agent (MA), a part of the mobile computing paradigm, was recently proposed for data gathering in Wireless Sensor Networks (WSNs). The MA-based approach employs two algorithms: Single-agent Itinerary Planning (SIP) and Multi-mobile agent Itinerary Planning (MIP) for energy-efficient data gathering. The MIP was proposed to outperform the weakness of SIP by introducing distributed multi MAs to perform the data gathering task. Despite the advantages of MIP, finding the optimal number of distributed MAs and their itineraries are still regarded as critical issues. The existing MIP algorithms assume that the itinerary of the MA has to start and return back to the sink node. Moreover, each distributed MA has to carry the processing code (data aggregation code) to collect the sensory data and return back to the sink with the accumulated data. However, these assumptions have resulted in an increase in the number of MA’s migration hops, which subsequently leads to an increase in energy and time consumption. In this paper, a spawn multi-mobile agent itinerary planning (SMIP) approach is proposed to mitigate the substantial increase in cost of energy and time used in the data gathering processes. The proposed approach is based on the agent spawning such that the main MA is able to spawn other MAs with different tasks assigned from the main MA. Extensive simulation experiments have been conducted to test the performance of the proposed approach against some selected MIP algorithms. The results show that the proposed SMIP outperforms the counterpart algorithms in terms of energy consumption and task delay (time), and improves the integrated energy-delay performance. Full article

(This article belongs to the Section Sensor Networks)

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25 pages, 16818 KiB

Open AccessArticle

High Dynamic Range Spectral Imaging Pipeline For Multispectral Filter Array Cameras

by Pierre-Jean Lapray¹

, Jean-Baptiste Thomas^2,3,* and Pierre Gouton³

¹ MIPS Laboratory, Université de Haute Alsace, 68093 Mulhouse, France

² The Norwegian Colour and Visual Computing Laboratory, NTNU - Norwegian University of Science and Technology, 2815 Gjøvik, Norway

³ Le2i Laboratory, FRE CNRS 2005, Université de Bourgogne Franche-Comté, 21000 Dijon, France

Sensors 2017, 17(6), 1281; https://doi.org/10.3390/s17061281 - 3 Jun 2017

Cited by 21 | Viewed by 9234

Abstract

Spectral filter arrays imaging exhibits a strong similarity with color filter arrays. This permits us to embed this technology in practical vision systems with little adaptation of the existing solutions. In this communication, we define an imaging pipeline that permits high dynamic range [...] Read more.

Spectral filter arrays imaging exhibits a strong similarity with color filter arrays. This permits us to embed this technology in practical vision systems with little adaptation of the existing solutions. In this communication, we define an imaging pipeline that permits high dynamic range (HDR)-spectral imaging, which is extended from color filter arrays. We propose an implementation of this pipeline on a prototype sensor and evaluate the quality of our implementation results on real data with objective metrics and visual examples. We demonstrate that we reduce noise, and, in particular we solve the problem of noise generated by the lack of energy balance. Data are provided to the community in an image database for further research. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in France 2016)

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12 pages, 5129 KiB

Open AccessArticle

Optimal Design of an Hourglass in-Fiber Air Fabry-Perot Microcavity—Towards Spectral Characteristics and Strain Sensing Technology

by Qi Wang^1,2,*

, Dongchao Yan¹, Binbin Cui¹ and Zixuan Guo¹

¹ College of Information Science and Engineering, Northeastern University, Shenyang 110819, China

² State Key Laboratory of Synthetical Automation for Process Industries (Northeastern University), Shenyang 110819, China

Sensors 2017, 17(6), 1282; https://doi.org/10.3390/s17061282 - 4 Jun 2017

Cited by 4 | Viewed by 5269

Abstract

An hourglass in-fiber air microcavity Fabry-Perot interferometer is proposed in this paper, and its second reflecting surface of in-fiber microcavity is designed to be a concave reflector with the best curvature radius in order to improve the spectral characteristics. Experimental results proved that [...] Read more.

An hourglass in-fiber air microcavity Fabry-Perot interferometer is proposed in this paper, and its second reflecting surface of in-fiber microcavity is designed to be a concave reflector with the best curvature radius in order to improve the spectral characteristics. Experimental results proved that the extinction ratio of Fabry-Perot interferometer with cavity length of 60 μm and concave reflector radius of 60 μm is higher than for a rectangular Fabry-Perot interferometer with cavity length of 60 μm (14 dB: 11 dB). Theory and numerical simulation results show that the strain sensitivity of sensor can be improved by reducing the microcavity wall thickness and microcavity diameter, and when the in-fiber microcavity length is 40 μm, the microcavity wall thickness is 10 μm, the microcavity diameter is 20 μm, and the curvature radius of reflective surface II is 50 μm, the interference fringe contrast of is greater than 0.97, an Axial-pull sensitivity of 20.46 nm/N and resolution of 1 mN can be achieved in the range of 0–1 N axial tension. The results show that the performance of hourglass in-fiber microcavity interferometer is far superior to that of the traditional Fabry-Perot interferometer. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 5638 KiB

Open AccessArticle

A Novel Real-Time Path Servo Control of a Hardware-in-the-Loop for a Large-Stroke Asymmetric Rod-Less Pneumatic System under Variable Loads

by Hao-Ting Lin

Department of Mechanical and Computer-Aided Engineering, Feng Chia University; Taichung 407, Taiwan

Sensors 2017, 17(6), 1283; https://doi.org/10.3390/s17061283 - 4 Jun 2017

Cited by 5 | Viewed by 5504

Abstract

This project aims to develop a novel large stroke asymmetric pneumatic servo system of a hardware-in-the-loop for path tracking control under variable loads based on the MATLAB Simulink real-time system. High pressure compressed air provided by the air compressor is utilized for the [...] Read more.

This project aims to develop a novel large stroke asymmetric pneumatic servo system of a hardware-in-the-loop for path tracking control under variable loads based on the MATLAB Simulink real-time system. High pressure compressed air provided by the air compressor is utilized for the pneumatic proportional servo valve to drive the large stroke asymmetric rod-less pneumatic actuator. Due to the pressure differences between two chambers, the pneumatic actuator will operate. The highly nonlinear mathematical models of the large stroke asymmetric pneumatic system were analyzed and developed. The functional approximation technique based on the sliding mode controller (FASC) is developed as a controller to solve the uncertain time-varying nonlinear system. The MATLAB Simulink real-time system was a main control unit of a hardware-in-the-loop system proposed to establish driver blocks for analog and digital I/O, a linear encoder, a CPU and a large stroke asymmetric pneumatic rod-less system. By the position sensor, the position signals of the cylinder will be measured immediately. The measured signals will be viewed as the feedback signals of the pneumatic servo system for the study of real-time positioning control and path tracking control. Finally, real-time control of a large stroke asymmetric pneumatic servo system with measuring system, a large stroke asymmetric pneumatic servo system, data acquisition system and the control strategy software will be implemented. Thus, upgrading the high position precision and the trajectory tracking performance of the large stroke asymmetric pneumatic servo system will be realized to promote the high position precision and path tracking capability. Experimental results show that fifth order paths in various strokes and the sine wave path are successfully implemented in the test rig. Also, results of variable loads under the different angle were implemented experimentally. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 3467 KiB

Open AccessArticle

Design and Performance of a Metal-Shielded Piezoelectric Sensor

by Álvaro Sáenz de Inestrillas¹, Francisco Camarena^2,*

, Manuel Bou Cabo¹, Julián M. Barreiro¹ and Antonio Reig³

¹ Institut d’Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC), Escola Politècnica Superior de Gandia (EPSG), Universitat Politècnica de València (UPV), 46730 Grau de Gandia, Spain

² Instituto de Instrumentación para Imagen Molecular (i3M), Universitat Politècnica de València (UPV), Consejo Superior de Investigaciones Científicas (CSIC), 46022 València, Spain

³ Departamento de Física Aplicada, Universitat Politècnica de València (UPV), 46022 València, Spain

Sensors 2017, 17(6), 1284; https://doi.org/10.3390/s17061284 - 4 Jun 2017

Cited by 9 | Viewed by 5221

Abstract

In certain circumstances when acoustic measurements are required in the presence of explosive atmospheres the sensor must be placed inside a Faraday Cage. Piezoelectric active materials are suitable for this purpose as they do not need an electrical power supply, although the metal [...] Read more.

In certain circumstances when acoustic measurements are required in the presence of explosive atmospheres the sensor must be placed inside a Faraday Cage. Piezoelectric active materials are suitable for this purpose as they do not need an electrical power supply, although the metal shielding can considerably reduce sensor sensitivity, which is already low at the acoustic frequency range (<20 kHz). This paper describes a metal-shielded piezoelectric sensor designed to work in the range of frequencies between 1 and 2 kHz and in these environmental conditions. The main idea was to add a thin material layer to the front face of the piezoelectric ceramic in order to force the system to vibrate in flexure mode at low frequencies. The resonant frequency and sensitivity of the system was studied as a function of the radius, thickness, and material of the thin layer. The study includes a comparison of theoretical model, FEM simulation, and real data measured using three aluminum and three steel prototypes of different sizes. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 7187 KiB

Open AccessArticle

The Use of Flexible Ultrasound Transducers for the Detection of Laser-Induced Guided Waves on Curved Surfaces at Elevated Temperatures

by Tai Chieh Wu^1,*, Makiko Kobayashi²

, Masayuki Tanabe²

and Che Hua Yang¹

¹ College of Mechanical and Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

² Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto 8608555, Japan

Sensors 2017, 17(6), 1285; https://doi.org/10.3390/s17061285 - 4 Jun 2017

Cited by 18 | Viewed by 6029

Abstract

In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of [...] Read more.

In this study, a flexible ultrasonic transducer (FUT) was applied in a laser ultrasonic technique (LUT) for non-destructive characterization of metallic pipes at high temperatures of up to 176 °C. Compared with normal ultrasound transducers, a FUT is a piezoelectric film made of a PZT/PZT sol-gel composite which has advantages due to its high sensitivity, curved surface adaptability and high temperature durability. By operating a pulsed laser in B-scan mode along with the integration of FUT and LUT, a multi-mode dispersion spectrum of a stainless steel pipe at high temperature can be measured. In addition, dynamic wave propagation behaviors are experimentally visualized with two dimensional scanning. The images directly interpret the reflections from the interior defects and also can locate their positions. This hybrid technique shows great potential for non-destructive evaluation of structures with complex geometry, especially in high temperature environments. Full article

(This article belongs to the Special Issue Intelligent Sensing Technologies for Nondestructive Evaluation)

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9 pages, 2047 KiB

Open AccessArticle

Magnetic Lateral Flow Strip for the Detection of Cocaine in Urine by Naked Eyes and Smart Phone Camera

by Jing Wu^1,2, Mingling Dong³, Cheng Zhang¹

, Yu Wang^1,*

, Mengxia Xie^2,* and Yiping Chen^3,*

¹ Liver Research Center, Beijing Friendship Hospital, Capital Medical University, National Clinical Research Center of Digestive Diseases, 95 Yong-an Road, Xicheng District, Beijing 100050, China

² Analytical & Testing Center of Beijing Normal University, Beijing 100875, China

³ CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China

Sensors 2017, 17(6), 1286; https://doi.org/10.3390/s17061286 - 5 Jun 2017

Cited by 37 | Viewed by 8136

Abstract

Magnetic lateral flow strip (MLFS) based on magnetic bead (MB) and smart phone camera has been developed for quantitative detection of cocaine (CC) in urine samples. CC and CC-bovine serum albumin (CC-BSA) could competitively react with MB-antibody (MB-Ab) of CC on the surface [...] Read more.

Magnetic lateral flow strip (MLFS) based on magnetic bead (MB) and smart phone camera has been developed for quantitative detection of cocaine (CC) in urine samples. CC and CC-bovine serum albumin (CC-BSA) could competitively react with MB-antibody (MB-Ab) of CC on the surface of test line of MLFS. The color of MB-Ab conjugate on the test line relates to the concentration of target in the competition immunoassay format, which can be used as a visual signal. Furthermore, the color density of the MB-Ab conjugate can be transferred into digital signal (gray value) by a smart phone, which can be used as a quantitative signal. The linear detection range for CC is 5–500 ng/mL and the relative standard deviations are under 10%. The visual limit of detection was 5 ng/mL and the whole analysis time was within 10 min. The MLFS has been successfully employed for the detection of CC in urine samples without sample pre-treatment and the result is also agreed to that of enzyme-linked immunosorbent assay (ELISA). With the popularization of smart phone cameras, the MLFS has large potential in the detection of drug residues in virtue of its stability, speediness, and low-cost. Full article

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

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18 pages, 1890 KiB

Open AccessArticle

Wearable Sensor Data Classification for Human Activity Recognition Based on an Iterative Learning Framework

by Juan Carlos Davila^*, Ana-Maria Cretu and Marek Zaremba

Department of Computer Science and Engineering, Université du Québec en Outaouais, Gatineau, QC J8Y 3G5, Canada

Sensors 2017, 17(6), 1287; https://doi.org/10.3390/s17061287 - 7 Jun 2017

Cited by 34 | Viewed by 8176

Abstract

The design of multiple human activity recognition applications in areas such as healthcare, sports and safety relies on wearable sensor technologies. However, when making decisions based on the data acquired by such sensors in practical situations, several factors related to sensor data alignment, [...] Read more.

The design of multiple human activity recognition applications in areas such as healthcare, sports and safety relies on wearable sensor technologies. However, when making decisions based on the data acquired by such sensors in practical situations, several factors related to sensor data alignment, data losses, and noise, among other experimental constraints, deteriorate data quality and model accuracy. To tackle these issues, this paper presents a data-driven iterative learning framework to classify human locomotion activities such as walk, stand, lie, and sit, extracted from the Opportunity dataset. Data acquired by twelve 3-axial acceleration sensors and seven inertial measurement units are initially de-noised using a two-stage consecutive filtering approach combining a band-pass Finite Impulse Response (FIR) and a wavelet filter. A series of statistical parameters are extracted from the kinematical features, including the principal components and singular value decomposition of roll, pitch, yaw and the norm of the axial components. The novel interactive learning procedure is then applied in order to minimize the number of samples required to classify human locomotion activities. Only those samples that are most distant from the centroids of data clusters, according to a measure presented in the paper, are selected as candidates for the training dataset. The newly built dataset is then used to train an SVM multi-class classifier. The latter will produce the lowest prediction error. The proposed learning framework ensures a high level of robustness to variations in the quality of input data, while only using a much lower number of training samples and therefore a much shorter training time, which is an important consideration given the large size of the dataset. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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27 pages, 4361 KiB

Open AccessArticle

Adaptive Temporal Matched Filtering for Noise Suppression in Fiber Optic Distributed Acoustic Sensing

by İbrahim Ölçer^1,2,*

and Ahmet Öncü²

¹ TÜBİTAK BİLGEM, Barış Mah., Dr. Zeki Acar Cad., Gebze 41470, Kocaeli, Turkey

² Electrical & Electronics Engineering Department, Boğaziçi University, Bebek, İstanbul 34342, Turkey

Sensors 2017, 17(6), 1288; https://doi.org/10.3390/s17061288 - 5 Jun 2017

Cited by 49 | Viewed by 11242

Abstract

Distributed vibration sensing based on phase-sensitive optical time domain reflectometry (

ϕ

-OTDR) is being widely used in several applications. However, one of the main challenges in coherent detection-based

ϕ

-OTDR systems is the fading noise, which impacts the detection performance. In addition, [...] Read more.

Distributed vibration sensing based on phase-sensitive optical time domain reflectometry (

ϕ

-OTDR) is being widely used in several applications. However, one of the main challenges in coherent detection-based

ϕ

-OTDR systems is the fading noise, which impacts the detection performance. In addition, typical signal averaging and differentiating techniques are not suitable for detecting high frequency events. This paper presents a new approach for reducing the effect of fading noise in fiber optic distributed acoustic vibration sensing systems without any impact on the frequency response of the detection system. The method is based on temporal adaptive processing of

ϕ

-OTDR signals. The fundamental theory underlying the algorithm, which is based on signal-to-noise ratio (SNR) maximization, is presented, and the efficacy of our algorithm is demonstrated with laboratory experiments and field tests. With the proposed digital processing technique, the results show that more than 10 dB of SNR values can be achieved without any reduction in the system bandwidth and without using additional optical amplifier stages in the hardware. We believe that our proposed adaptive processing approach can be effectively used to develop fiber optic-based distributed acoustic vibration sensing systems. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1681 KiB

Open AccessArticle

Proof of Concept of Home IoT Connected Vehicles

by Younsun Kim, Hyunggoy Oh and Sungho Kang^*

Department of Electrical and Electronic Engineering, Yonsei University, 03722 Seoul, Korea

Sensors 2017, 17(6), 1289; https://doi.org/10.3390/s17061289 - 5 Jun 2017

Cited by 27 | Viewed by 7864

Abstract

The way in which we interact with our cars is changing, driven by the increased use of mobile devices, cloud-based services, and advanced automotive technology. In particular, the requirements and market demand for the Internet of Things (IoT) device-connected vehicles will continuously increase. [...] Read more.

The way in which we interact with our cars is changing, driven by the increased use of mobile devices, cloud-based services, and advanced automotive technology. In particular, the requirements and market demand for the Internet of Things (IoT) device-connected vehicles will continuously increase. In addition, the advances in cloud computing and IoT have provided a promising opportunity for developing vehicular software and services in the automotive domain. In this paper, we introduce the concept of a home IoT connected vehicle with a voice-based virtual personal assistant comprised of a vehicle agent and a home agent. The proposed concept is evaluated by implementing a smartphone linked with home IoT devices that are connected to an infotainment system for the vehicle, a smartphone-based natural language interface input device, and cloud-based home IoT devices for the home. The home-to-vehicle connected service scenarios that aim to reduce the inconvenience due to simple and repetitive tasks by improving the urban mobility efficiency in IoT environments are substantiated by analyzing real vehicle testing and lifestyle research. Remarkable benefits are derived by making repetitive routine tasks one task that is executed by a command and by executing essential tasks automatically, without any request. However, it should be used with authorized permission, applied without any error at the right time, and applied under limited conditions to sense the habitants’ intention correctly and to gain the required trust regarding the remote execution of tasks. Full article

(This article belongs to the Section Sensor Networks)

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16 pages, 1355 KiB

Open AccessArticle

Machine Learning-Based Calibration of Low-Cost Air Temperature Sensors Using Environmental Data

by Kyosuke Yamamoto^1,*

, Takashi Togami¹, Norio Yamaguchi¹ and Seishi Ninomiya²

¹ PS Solutions Corp., 1-5-2 Higashi-Shimbashi, Minato-ku, Tokyo 105-7104, Japan

² Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Midori-cho, Nishi-Tokyo, Tokyo 188-0002, Japan

Sensors 2017, 17(6), 1290; https://doi.org/10.3390/s17061290 - 5 Jun 2017

Cited by 49 | Viewed by 7639

Abstract

The measurement of air temperature is strongly influenced by environmental factors such as solar radiation, humidity, wind speed and rainfall. This is problematic in low-cost air temperature sensors, which lack a radiation shield or a forced aspiration system, exposing them to direct sunlight [...] Read more.

The measurement of air temperature is strongly influenced by environmental factors such as solar radiation, humidity, wind speed and rainfall. This is problematic in low-cost air temperature sensors, which lack a radiation shield or a forced aspiration system, exposing them to direct sunlight and condensation. In this study, we developed a machine learning-based calibration method for air temperature measurement by a low-cost sensor. An artificial neural network (ANN) was used to balance the effect of multiple environmental factors on the measurements. Data were collected over 305 days, at three different locations in Japan, and used to evaluate the performance of the approach. Data collected at the same location and at different locations were used for training and testing, and the former was also used for k-fold cross-validation, demonstrating an average improvement in mean absolute error (MAE) from 1.62 to 0.67 by applying our method. Some calibration failures were noted, due to abrupt changes in environmental conditions such as solar radiation or rainfall. The MAE was shown to decrease even when the data collected in different nearby locations were used for training and testing. However, the results also showed that negative effects arose when data obtained from widely-separated locations were used, because of the significant environmental differences between them. Full article

(This article belongs to the Section Sensor Networks)

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16 pages, 1947 KiB

Open AccessArticle

A Forward GPS Multipath Simulator Based on the Vegetation Radiative Transfer Equation Model

by Xuerui Wu^1,2,*

, Shuanggen Jin^1,2

and Junming Xia³

¹ Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China

² Key Laboratory of Planetary Sciences, Chinese Academy of Sciences, Shanghai 200030, China

³ National Space Science Centers, Chinese Academic of Sciences, Beijing 100190, China

Sensors 2017, 17(6), 1291; https://doi.org/10.3390/s17061291 - 5 Jun 2017

Cited by 6 | Viewed by 4842

Abstract

Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However, bistatic scattering properties and [...] Read more.

Global Navigation Satellite Systems (GNSS) have been widely used in navigation, positioning and timing. Nowadays, the multipath errors may be re-utilized for the remote sensing of geophysical parameters (soil moisture, vegetation and snow depth), i.e., GPS-Multipath Reflectometry (GPS-MR). However, bistatic scattering properties and the relation between GPS observables and geophysical parameters are not clear, e.g., vegetation. In this paper, a new element on bistatic scattering properties of vegetation is incorporated into the traditional GPS-MR model. This new element is the first-order radiative transfer equation model. The new forward GPS multipath simulator is able to explicitly link the vegetation parameters with GPS multipath observables (signal-to-noise-ratio (SNR), code pseudorange and carrier phase observables). The trunk layer and its corresponding scattering mechanisms are ignored since GPS-MR is not suitable for high forest monitoring due to the coherence of direct and reflected signals. Based on this new model, the developed simulator can present how the GPS signals (L1 and L2 carrier frequencies, C/A, P(Y) and L2C modulations) are transmitted (scattered and absorbed) through vegetation medium and received by GPS receivers. Simulation results show that the wheat will decrease the amplitudes of GPS multipath observables (SNR, phase and code), if we increase the vegetation moisture contents or the scatters sizes (stem or leaf). Although the Specular-Ground component dominates the total specular scattering, vegetation covered ground soil moisture has almost no effects on the final multipath signatures. Our simulated results are consistent with previous results for environmental parameter detections by GPS-MR. Full article

(This article belongs to the Special Issue Recent Innovative Microwave Remote Sensing Instrumentation for Land Surface Applications)

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14 pages, 4623 KiB

Open AccessArticle

Graphene-Supported Spinel CuFe₂O₄ Composites: Novel Adsorbents for Arsenic Removal in Aqueous Media

by Duong Duc La¹

, Tuan Anh Nguyen², Lathe A. Jones^1,3

and Sheshanath V. Bhosale^1,*

¹ School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia

² Applied Nanomaterial Laboratory, ANTECH, Hanoi 100000, Vietnam

³ Centre for Advanced Materials and Industrial Chemistry (CAMIC), School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia

Sensors 2017, 17(6), 1292; https://doi.org/10.3390/s17061292 - 5 Jun 2017

Cited by 33 | Viewed by 6677

Abstract

A graphene nanoplate-supported spinel CuFe₂O₄ composite (GNPs/CuFe₂O₄) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray [...] Read more.

A graphene nanoplate-supported spinel CuFe₂O₄ composite (GNPs/CuFe₂O₄) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the prepared composite. The arsenic adsorption behavior of the GNPs/CuFe₂O₄ composite was investigated by carrying out batch experiments. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, where the sorption kinetics of arsenic adsorption by the composite were found to be pseudo-second order. The selectivity of the adsorbent toward arsenic over common metal ions in water was also demonstrated. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled column filter test. The GNPs/CuFe₂O₄ composite exhibited significant, fast adsorption of arsenic over a wide range of solution pHs with exceptional durability, selectivity, and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solution. The highly sensitive adsorption of the material toward arsenic could be potentially employed for arsenic sensing. Full article

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

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28 pages, 8486 KiB

Open AccessReview

Cell Microarray Technologies for High-Throughput Cell-Based Biosensors

by Hye Jin Hong¹

, Woong Sub Koom² and Won-Gun Koh^1,*

¹ Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea

² Department of Radiation Oncology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea

Sensors 2017, 17(6), 1293; https://doi.org/10.3390/s17061293 - 5 Jun 2017

Cited by 39 | Viewed by 10866

Abstract

Due to the recent demand for high-throughput cellular assays, a lot of efforts have been made on miniaturization of cell-based biosensors by preparing cell microarrays. Various microfabrication technologies have been used to generate cell microarrays, where cells of different phenotypes are immobilized either [...] Read more.

Due to the recent demand for high-throughput cellular assays, a lot of efforts have been made on miniaturization of cell-based biosensors by preparing cell microarrays. Various microfabrication technologies have been used to generate cell microarrays, where cells of different phenotypes are immobilized either on a flat substrate (positional array) or on particles (solution or suspension array) to achieve multiplexed and high-throughput cell-based biosensing. After introducing the fabrication methods for preparation of the positional and suspension cell microarrays, this review discusses the applications of the cell microarray including toxicology, drug discovery and detection of toxic agents. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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13 pages, 15416 KiB

Open AccessArticle

Multi-Axis Force Sensor for Human–Robot Interaction Sensing in a Rehabilitation Robotic Device

by Victor Grosu^*

, Svetlana Grosu, Bram Vanderborght, Dirk Lefeber and Carlos Rodriguez-Guerrero

MECH Department, Vrije Universiteit Brussel and Flanders Make, Pleinlaan 2, Brussels 1050, Belgium

Sensors 2017, 17(6), 1294; https://doi.org/10.3390/s17061294 - 5 Jun 2017

Cited by 40 | Viewed by 8871

Abstract

Human–robot interaction sensing is a compulsory feature in modern robotic systems where direct contact or close collaboration is desired. Rehabilitation and assistive robotics are fields where interaction forces are required for both safety and increased control performance of the device with a more [...] Read more.

Human–robot interaction sensing is a compulsory feature in modern robotic systems where direct contact or close collaboration is desired. Rehabilitation and assistive robotics are fields where interaction forces are required for both safety and increased control performance of the device with a more comfortable experience for the user. In order to provide an efficient interaction feedback between the user and rehabilitation device, high performance sensing units are demanded. This work introduces a novel design of a multi-axis force sensor dedicated for measuring pelvis interaction forces in a rehabilitation exoskeleton device. The sensor is conceived such that it has different sensitivity characteristics for the three axes of interest having also movable parts in order to allow free rotations and limit crosstalk errors. Integrated sensor electronics make it easy to acquire and process data for a real-time distributed system architecture. Two of the developed sensors are integrated and tested in a complex gait rehabilitation device for safe and compliant control. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 4062 KiB

Open AccessArticle

Remote Sensing Image Change Detection Based on NSCT-HMT Model and Its Application

by Pengyun Chen¹

, Yichen Zhang¹, Zhenhong Jia^1,*, Jie Yang² and Nikola Kasabov³

¹ College of Information Science and Engineering, Xinjiang University, Urumuqi 830046, China

² Institute of Image Processing and Pattern Recognition, Shanghai Jiao Tong University, Shanghai 200400, China

³ Knowledge Engineering and Discovery Research Institute, Auckland University of Technology, Auckland 1020, New Zealand

Sensors 2017, 17(6), 1295; https://doi.org/10.3390/s17061295 - 6 Jun 2017

Cited by 20 | Viewed by 4732

Abstract

Traditional image change detection based on a non-subsampled contourlet transform always ignores the neighborhood information’s relationship to the non-subsampled contourlet coefficients, and the detection results are susceptible to noise interference. To address these disadvantages, we propose a denoising method based on the non-subsampled [...] Read more.

Traditional image change detection based on a non-subsampled contourlet transform always ignores the neighborhood information’s relationship to the non-subsampled contourlet coefficients, and the detection results are susceptible to noise interference. To address these disadvantages, we propose a denoising method based on the non-subsampled contourlet transform domain that uses the Hidden Markov Tree model (NSCT-HMT) for change detection of remote sensing images. First, the ENVI software is used to calibrate the original remote sensing images. After that, the mean-ratio operation is adopted to obtain the difference image that will be denoised by the NSCT-HMT model. Then, using the Fuzzy Local Information C-means (FLICM) algorithm, the difference image is divided into the change area and unchanged area. The proposed algorithm is applied to a real remote sensing data set. The application results show that the proposed algorithm can effectively suppress clutter noise, and retain more detailed information from the original images. The proposed algorithm has higher detection accuracy than the Markov Random Field-Fuzzy C-means (MRF-FCM), the non-subsampled contourlet transform-Fuzzy C-means clustering (NSCT-FCM), the pointwise approach and graph theory (PA-GT), and the Principal Component Analysis-Nonlocal Means (PCA-NLM) denosing algorithm. Finally, the five algorithms are used to detect the southern boundary of the Gurbantunggut Desert in Xinjiang Uygur Autonomous Region of China, and the results show that the proposed algorithm has the best effect on real remote sensing image change detection. Full article

(This article belongs to the Section Remote Sensors)

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10 pages, 2909 KiB

Open AccessArticle

Ultrasensitive Magnetic Nanoparticle Detector for Biosensor Applications

by Yu-Chi Liang^1,2, Long Chang^2,3, Wenlan Qiu^2,4, Arati G. Kolhatkar⁵, Binh Vu¹, Katerina Kourentzi¹, T. Randall Lee⁵

, Youli Zu⁶, Richard Willson^1,7 and Dmitri Litvinov^1,2,3,4,5,*

¹ Department of Chemical & Biomolecular Engineering, University of Houston, Houston, TX 77204, USA

² Center for Integrated Bio & Nano Systems, University of Houston, Houston, TX 77204, USA

³ Department of Electrical & Computer Engineering, University of Houston, Houston, TX 77204, USA

⁴ Materials Science & Engineering, University of Houston, Houston, TX 77204, USA

⁵ Department of Chemistry, University of Houston, Houston, TX 77204, USA

⁶ Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030, USA

⁷ Centro de Biotecnología FEMSA, Departamento de Biotecnología e Ingeniería de Alimentos, Tecnológico de Monterrey, Monterrey, NL 64849, Mexico

Sensors 2017, 17(6), 1296; https://doi.org/10.3390/s17061296 - 6 Jun 2017

Cited by 24 | Viewed by 7005

Abstract

Ta/Ru/Co/Ru/Co/Cu/Co/Ni₈₀Fe₂₀/Ta spin-valve giant magnetoresistive (GMR) multilayers were deposited using UHV magnetron sputtering and optimized to achieve a 13% GMR ratio before patterning. The GMR multilayer was patterned into 12 sensor arrays using a combination of e-beam and optical lithographies. [...] Read more.

Ta/Ru/Co/Ru/Co/Cu/Co/Ni₈₀Fe₂₀/Ta spin-valve giant magnetoresistive (GMR) multilayers were deposited using UHV magnetron sputtering and optimized to achieve a 13% GMR ratio before patterning. The GMR multilayer was patterned into 12 sensor arrays using a combination of e-beam and optical lithographies. Arrays were constructed with 400 nm × 400 nm and 400 nm × 200 nm sensors for the detection of reporter nanoparticles. Nanoparticle detection was based on measuring the shift in high-to-low resistance switching field of the GMR sensors in the presence of magnetic particle(s). Due to shape anisotropy and the corresponding demag field, the resistance state switching fields were significantly larger and the switching field distribution significantly broader in the 400 nm × 200 nm sensors as compared to the 400 nm × 400 nm sensors. Thus, sensor arrays with 400 nm × 400 nm dimensions were used for the demonstration of particle detection. Detection of a single 225 nm Fe₃O₄ magnetic nanoparticle and a small number (~10) of 100 nm nanoparticles was demonstrated. With appropriate functionalization for biomolecular recognition, submicron GMR sensor arrays can serve as the basis of ultrasensitive chemical and biological sensors. Full article

(This article belongs to the Special Issue Micro and Nanofabrication Technologies for Biosensors)

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21 pages, 2326 KiB

Open AccessArticle

Convolutional Neural Network-Based Finger-Vein Recognition Using NIR Image Sensors

by Hyung Gil Hong, Min Beom Lee 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(6), 1297; https://doi.org/10.3390/s17061297 - 6 Jun 2017

Cited by 181 | Viewed by 11395

Abstract

Conventional finger-vein recognition systems perform recognition based on the finger-vein lines extracted from the input images or image enhancement, and texture feature extraction from the finger-vein images. In these cases, however, the inaccurate detection of finger-vein lines lowers the recognition accuracy. In the [...] Read more.

Conventional finger-vein recognition systems perform recognition based on the finger-vein lines extracted from the input images or image enhancement, and texture feature extraction from the finger-vein images. In these cases, however, the inaccurate detection of finger-vein lines lowers the recognition accuracy. In the case of texture feature extraction, the developer must experimentally decide on a form of the optimal filter for extraction considering the characteristics of the image database. To address this problem, this research proposes a finger-vein recognition method that is robust to various database types and environmental changes based on the convolutional neural network (CNN). In the experiments using the two finger-vein databases constructed in this research and the SDUMLA-HMT finger-vein database, which is an open database, the method proposed in this research showed a better performance compared to the conventional methods. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 4084 KiB

Open AccessArticle

Comparison and Evaluation of Annual NDVI Time Series in China Derived from the NOAA AVHRR LTDR and Terra MODIS MOD13C1 Products

by Xiaoyi Guo

, Hongyan Zhang^*, Zhengfang Wu^*, Jianjun Zhao

and Zhengxiang Zhang

School of Geographical Sciences, Northeast Normal University, Changchun 130024, China

Sensors 2017, 17(6), 1298; https://doi.org/10.3390/s17061298 - 6 Jun 2017

Cited by 42 | Viewed by 6520

Abstract

Time series of Normalized Difference Vegetation Index (NDVI) derived from multiple satellite sensors are crucial data to study vegetation dynamics. The Land Long Term Data Record Version 4 (LTDR V4) NDVI dataset was recently released at a 0.05 × 0.05° spatial resolution and [...] Read more.

Time series of Normalized Difference Vegetation Index (NDVI) derived from multiple satellite sensors are crucial data to study vegetation dynamics. The Land Long Term Data Record Version 4 (LTDR V4) NDVI dataset was recently released at a 0.05 × 0.05° spatial resolution and daily temporal resolution. In this study, annual NDVI time series that are composited by the LTDR V4 and Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI datasets (MOD13C1) are compared and evaluated for the period from 2001 to 2014 in China. The spatial patterns of the NDVI generally match between the LTDR V4 and MOD13C1 datasets. The transitional zone between high and low NDVI values generally matches the boundary of semi-arid and sub-humid regions. A significant and high coefficient of determination is found between the two datasets according to a pixel-based correlation analysis. The spatially averaged NDVI of LTDR V4 is characterized by a much weaker positive regression slope relative to that of the spatially averaged NDVI of the MOD13C1 dataset because of changes in NOAA AVHRR sensors between 2005 and 2006. The measured NDVI values of LTDR V4 were always higher than that of MOD13C1 in western China due to the relatively lower atmospheric water vapor content in western China, and opposite observation appeared in eastern China. In total, 18.54% of the LTDR V4 NDVI pixels exhibit significant trends, whereas 35.79% of the MOD13C1 NDVI pixels show significant trends. Good agreement is observed between the significant trends of the two datasets in the Northeast Plain, Bohai Economic Rim, Loess Plateau, and Yangtze River Delta. By contrast, the datasets contrasted in northwestern desert regions and southern China. A trend analysis of the regression slope values according to the vegetation type shows good agreement between the LTDR V4 and MOD13C1 datasets. This study demonstrates the spatial and temporal consistencies and discrepancies between the AVHRR LTDR and MODIS MOD13C1 NDVI products in China, which could provide useful information for the choice of NDVI products in subsequent studies of vegetation dynamics. Full article

(This article belongs to the Section Remote Sensors)

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29 pages, 6564 KiB

Open AccessArticle

Study on an Indoor Positioning System for Harsh Environments Based on Wi-Fi and Bluetooth Low Energy

by Gabriel De Blasio^1,*

, Alexis Quesada-Arencibia¹

, Carmelo R. García¹

, Jezabel Miriam Molina-Gil² and Cándido Caballero-Gil²

¹ Instituto Universitario de Ciencias y Tecnologías Cibernéticas, ULPGC, 35001 Las Palmas de Gran Canaria, Las Palmas, Spain

² Department of Computer Engineering and Systems, University of La Laguna, 38200 San Cristóbal de La Laguna, Santa Cruz de Tenerife, Spain

Sensors 2017, 17(6), 1299; https://doi.org/10.3390/s17061299 - 6 Jun 2017

Cited by 49 | Viewed by 7899

Abstract

This paper presents a study of positioning system that provides advanced information services based on Wi-Fi and Bluetooth Low Energy (BLE) technologies. It uses Wi-Fi for rough positioning and BLE for fine positioning. It is designed for use in public transportation system stations [...] Read more.

This paper presents a study of positioning system that provides advanced information services based on Wi-Fi and Bluetooth Low Energy (BLE) technologies. It uses Wi-Fi for rough positioning and BLE for fine positioning. It is designed for use in public transportation system stations and terminals where the conditions are “hostile” or unfavourable due to signal noise produced by the continuous movement of passengers and buses, data collection conducted in the constant presence thereof, multipath fading, non-line of sight (NLOS) conditions, the fact that part of the wireless communication infrastructure has already been deployed and positioned in a way that may not be optimal for positioning purposes, variable humidity conditions, etc. The ultimate goal is to provide a service that may be used to assist people with special needs. We present experimental results based on scene analysis; the main distance metric used was the Euclidean distance but the Mahalanobis distance was also used in one case. The algorithm employed to compare fingerprints was the weighted k-nearest neighbor one. For Wi-Fi, with only three visible access points, accuracy ranged from 3.94 to 4.82 m, and precision from 5.21 to 7.0 m 90% of the time. With respect to BLE, with a low beacon density (1 beacon per 45.7 m²), accuracy ranged from 1.47 to 2.15 m, and precision from 1.81 to 3.58 m 90% of the time. Taking into account the fact that this system is designed to work in real situations in a scenario with high environmental fluctuations, and comparing the results with others obtained in laboratory scenarios, our results are promising and demonstrate that the system would be able to position users with these reasonable values of accuracy and precision. Full article

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

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13 pages, 1547 KiB

Open AccessArticle

Two-Dimensional DOA Estimation for Coherently Distributed Sources with Symmetric Properties in Crossed Arrays

by Zhengliang Dai^*

, Weijia Cui, Bin Ba, Daming Wang and Youming Sun

National Digital System Engineering and Technological Research R&D Center, Zhengzhou 450001, China

Sensors 2017, 17(6), 1300; https://doi.org/10.3390/s17061300 - 6 Jun 2017

Cited by 12 | Viewed by 4638

Abstract

In this paper, a novel algorithm is proposed for the two-dimensional (2D) central direction-of-arrival (DOA) estimation of coherently distributed (CD) sources. Specifically, we focus on a centro-symmetric crossed array consisting of two uniform linear arrays (ULAs). Unlike the conventional low-complexity methods using the [...] Read more.

In this paper, a novel algorithm is proposed for the two-dimensional (2D) central direction-of-arrival (DOA) estimation of coherently distributed (CD) sources. Specifically, we focus on a centro-symmetric crossed array consisting of two uniform linear arrays (ULAs). Unlike the conventional low-complexity methods using the one-order Taylor series approximation to obtain the approximate rotational invariance relation, we first prove the symmetric property of angular signal distributed weight vectors of the CD source for an arbitrary centrosymmetric array, and then use this property to establish two generalized rotational invariance relations inside the array manifolds in the two ULAs. Making use of such relations, the central elevation and azimuth DOAs are obtained by employing a polynomial-root-based search-free approach, respectively. Finally, simple parameter matching is accomplished by searching for the minimums of the cost function of the estimated 2D angular parameters. When compared with the existing low-complexity methods, the proposed algorithm can greatly improve estimation accuracy without significant increment in computation complexity. Moreover, it performs independently of the deterministic angular distributed function. Simulation results are presented to illustrate the performance of the proposed algorithm. 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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3 pages, 691 KiB

Open AccessCorrection

Correction: Moreno, A., et al. Design of a Cooperative ITS Architecture Based on Distributed RSUs.

by Asier Moreno^1,2, Eneko Osaba^1,2

, Enrique Onieva^1,2

, Asier Perallos^1,2,*, Giovanni Iovino³ and Pablo Fernández^1,2

¹ DeustoTech—Fundación Deusto, Avda. Universidades, 24, 48007 Bilbao, Spain

² Faculty of Engineering, University of Deusto, Avda. Universidades, 24, 48007 Bilbao, Spain

³ INTECS SpA, Via Umberto Forti 5, 56121 Pisa, Italy

Sensors 2017, 17(6), 1301; https://doi.org/10.3390/s17061301 - 6 Jun 2017

Viewed by 3393

Abstract

The authors wish to make the following corrections to this paper: [...]
Full article

(This article belongs to the Special Issue Selected Papers from UCAmI, IWAAL and AmIHEALTH 2015)

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11 pages, 2968 KiB

Open AccessArticle

An Approach to Speed up Single-Frequency PPP Convergence with Quad-Constellation GNSS and GIM

by Changsheng Cai¹, Yangzhao Gong¹, Yang Gao^2,3,*

and Cuilin Kuang¹

¹ School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

² School of Surveying and Urban Spatial Information, Beijing University of Civil Engineering and Architecture, Beijing 100044, China

³ Department of Geomatics Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(6), 1302; https://doi.org/10.3390/s17061302 - 6 Jun 2017

Cited by 50 | Viewed by 5977

Abstract

The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. [...] Read more.

The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. In this study, an approach is proposed to accelerate the single-frequency PPP convergence by combining quad-constellation global navigation satellite system (GNSS) and global ionospheric map (GIM) data. In this proposed approach, the GPS, GLONASS, BeiDou, and Galileo observations are directly used in an uncombined observation model and as a result the ionospheric and hardware delay (IHD) can be estimated together as a single unknown parameter. The IHD values acquired from the GIM product and the multi-GNSS differential code bias (DCB) product are then utilized as pseudo-observables of the IHD parameter in the observation model. A time varying weight scheme has also been proposed for the pseudo-observables to gradually decrease its contribution to the position solutions during the convergence period. To evaluate the proposed approach, datasets from twelve Multi-GNSS Experiment (MGEX) stations on seven consecutive days are processed and analyzed. The numerical results indicate that the single-frequency PPP with quad-constellation GNSS and GIM data are able to reduce the convergence time by 56%, 47%, 41% in the east, north, and up directions compared to the GPS-only single-frequency PPP. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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18 pages, 3112 KiB

Open AccessArticle

Node Scheduling Strategies for Achieving Full-View Area Coverage in Camera Sensor Networks

by Peng-Fei Wu^1,2, Fu Xiao^1,2, Chao Sha^1,2,3,*

, Hai-Ping Huang^1,2

, Ru-Chuan Wang^1,2 and Nai-Xue Xiong⁴

¹ School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

² Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks, Nanjing 210003, China

³ Nanjing University of Information Science & Technology, Nanjing 210044, China

⁴ Department of Mathematics and Computer Science, Northeastern State University, Tahlequah, OK 74464, USA

Sensors 2017, 17(6), 1303; https://doi.org/10.3390/s17061303 - 6 Jun 2017

Cited by 43 | Viewed by 5764

Abstract

Unlike conventional scalar sensors, camera sensors at different positions can capture a variety of views of an object. Based on this intrinsic property, a novel model called full-view coverage was proposed. We study the problem that how to select the minimum number of [...] Read more.

Unlike conventional scalar sensors, camera sensors at different positions can capture a variety of views of an object. Based on this intrinsic property, a novel model called full-view coverage was proposed. We study the problem that how to select the minimum number of sensors to guarantee the full-view coverage for the given region of interest (ROI). To tackle this issue, we derive the constraint condition of the sensor positions for full-view neighborhood coverage with the minimum number of nodes around the point. Next, we prove that the full-view area coverage can be approximately guaranteed, as long as the regular hexagons decided by the virtual grid are seamlessly stitched. Then we present two solutions for camera sensor networks in two different deployment strategies. By computing the theoretically optimal length of the virtual grids, we put forward the deployment pattern algorithm (DPA) in the deterministic implementation. To reduce the redundancy in random deployment, we come up with a local neighboring-optimal selection algorithm (LNSA) for achieving the full-view coverage. Finally, extensive simulation results show the feasibility of our proposed solutions. Full article

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

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15 pages, 5096 KiB

Open AccessArticle

Dynamics of Hierarchical Urban Green Space Patches and Implications for Management Policy

by Zhoulu Yu¹, Yaohui Wang¹, Jinsong Deng^1,2, Zhangquan Shen¹, Ke Wang¹, Jinxia Zhu³ and Muye Gan^1,*

¹ Institute of Applied Remote Sensing and Information Technology, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China

² State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China

³ Institute of Land and Urban-Rural Development, Zhejiang University of Finance & Economics, 18 Xueyuan Road, Hangzhou 310019, China

Sensors 2017, 17(6), 1304; https://doi.org/10.3390/s17061304 - 6 Jun 2017

Cited by 31 | Viewed by 6213

Abstract

Accurately quantifying the variation of urban green space is the prerequisite for fully understanding its ecosystem services. However, knowledge about the spatiotemporal dynamics of urban green space is still insufficient due to multiple challenges that remain in mapping green spaces within heterogeneous urban [...] Read more.

Accurately quantifying the variation of urban green space is the prerequisite for fully understanding its ecosystem services. However, knowledge about the spatiotemporal dynamics of urban green space is still insufficient due to multiple challenges that remain in mapping green spaces within heterogeneous urban environments. This paper uses the city of Hangzhou to demonstrate an analysis methodology that integrates sub-pixel mapping technology and landscape analysis to fully investigate the spatiotemporal pattern and variation of hierarchical urban green space patches. Firstly, multiple endmember spectral mixture analysis was applied to time series Landsat data to derive green space coverage at the sub-pixel level. Landscape metric analysis was then employed to characterize the variation pattern of urban green space patches. Results indicate that Hangzhou has experienced a significant loss of urban greenness, producing a more fragmented and isolated vegetation landscape. Additionally, a remarkable amelioration of urban greenness occurred in the city core from 2002 to 2013, characterized by the significant increase of small-sized green space patches. The green space network has been formed as a consequence of new urban greening strategies in Hangzhou. These strategies have greatly fragmented the built-up areas and enriched the diversity of the urban landscape. Gradient analysis further revealed a distinct pattern of urban green space landscape variation in the process of urbanization. By integrating both sub-pixel mapping technology and landscape analysis, our approach revealed the subtle variation of urban green space patches which are otherwise easy to overlook. Findings from this study will help us to refine our understanding of the evolution of heterogeneous urban environments. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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30 pages, 20033 KiB

Open AccessArticle

A High-Speed Target-Free Vision-Based Sensor for Bus Rapid Transit Viaduct Vibration Measurements Using CMT and ORB Algorithms

by Qijun Hu¹, Songsheng He¹, Shilong Wang², Yugang Liu^2,*, Zutao Zhang³

, Leping He¹, Fubin Wang⁴, Qijie Cai², Rendan Shi¹ and Yuan Yang¹

¹ School of Civil Engineering and Architecture, Southwest Petroleum University, Chengdu 610500, China

² School of Transportation and Logistics, Southwest Jiaotong University, Chengdu 610031, China

³ School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China

⁴ School of Information Science and Technology, Southwest Jiaotong University, Chengdu 610031, China

Sensors 2017, 17(6), 1305; https://doi.org/10.3390/s17061305 - 6 Jun 2017

Cited by 31 | Viewed by 5581

Abstract

Bus Rapid Transit (BRT) has become an increasing source of concern for public transportation of modern cities. Traditional contact sensing techniques during the process of health monitoring of BRT viaducts cannot overcome the deficiency that the normal free-flow of traffic would be blocked. [...] Read more.

Bus Rapid Transit (BRT) has become an increasing source of concern for public transportation of modern cities. Traditional contact sensing techniques during the process of health monitoring of BRT viaducts cannot overcome the deficiency that the normal free-flow of traffic would be blocked. Advances in computer vision technology provide a new line of thought for solving this problem. In this study, a high-speed target-free vision-based sensor is proposed to measure the vibration of structures without interrupting traffic. An improved keypoints matching algorithm based on consensus-based matching and tracking (CMT) object tracking algorithm is adopted and further developed together with oriented brief (ORB) keypoints detection algorithm for practicable and effective tracking of objects. Moreover, by synthesizing the existing scaling factor calculation methods, more rational approaches to reducing errors are implemented. The performance of the vision-based sensor is evaluated through a series of laboratory tests. Experimental tests with different target types, frequencies, amplitudes and motion patterns are conducted. The performance of the method is satisfactory, which indicates that the vision sensor can extract accurate structure vibration signals by tracking either artificial or natural targets. Field tests further demonstrate that the vision sensor is both practicable and reliable. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2627 KiB

Open AccessReview

Bioluminescence Assays for Monitoring Chondrogenic Differentiation and Cartilage Regeneration

by Hyeon Jeong Je, Min Gu Kim and Hyuck Joon Kwon^*

Department of Physical Therapy and Rehabilitation Science, College of Health Science, Eulji University, Gyeonggi 13135, Korea

Sensors 2017, 17(6), 1306; https://doi.org/10.3390/s17061306 - 6 Jun 2017

Cited by 9 | Viewed by 6231

Abstract

Since articular cartilage has a limited regeneration potential, for developing biological therapies for cartilage regeneration it is important to study the mechanisms underlying chondrogenesis of stem cells. Bioluminescence assays can visualize a wide range of biological phenomena such as gene expression, signaling, metabolism, [...] Read more.

Since articular cartilage has a limited regeneration potential, for developing biological therapies for cartilage regeneration it is important to study the mechanisms underlying chondrogenesis of stem cells. Bioluminescence assays can visualize a wide range of biological phenomena such as gene expression, signaling, metabolism, development, cellular movements, and molecular interactions by using visible light and thus contribute substantially to elucidation of their biological functions. This article gives a concise review to introduce basic principles of bioluminescence assays and applications of the technology to visualize the processes of chondrogenesis and cartilage regeneration. Applications of bioluminescence assays have been highlighted in the methods of real-time monitoring of gene expression and intracellular levels of biomolecules and noninvasive cell tracking within animal models. This review suggests that bioluminescence assays can be applied towards a visual understanding of chondrogenesis and cartilage regeneration. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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16 pages, 3860 KiB

Open AccessArticle

Diagnosis of Compound Fault Using Sparsity Promoted-Based Sparse Component Analysis

by Yansong Hao¹, Liuyang Song^1,2,*

, Yanliang Ke¹, Huaqing Wang^1,*

and Peng Chen²

¹ College of Mechanical & Electrical Engineering, Beijing University of Chemical Technology, Chao Yang District, Beijing 100029, China

² Graduate School of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan

Sensors 2017, 17(6), 1307; https://doi.org/10.3390/s17061307 - 6 Jun 2017

Cited by 26 | Viewed by 3956

Abstract

Compound faults often occur in rotating machinery, which increases the difficulty of fault diagnosis. In this case, blind source separation, which usually includes independent component analysis (ICA) and sparse component analysis (SCA), was proposed to separate mixed signals. SCA, which is based on [...] Read more.

Compound faults often occur in rotating machinery, which increases the difficulty of fault diagnosis. In this case, blind source separation, which usually includes independent component analysis (ICA) and sparse component analysis (SCA), was proposed to separate mixed signals. SCA, which is based on the sparsity of target signals, was developed to sever the compound faults and effectively diagnose the fault due to its advantage over ICA in underdetermined conditions. However, there is an issue regarding the vibration signals, which are inadequately sparse, and it is difficult to represent them in a sparse way. Accordingly, to overcome the above-mentioned problem, a sparsity-promoted approach named wavelet modulus maxima is applied to obtain the sparse observation signal. Then, the potential function is utilized to estimate the number of source signals and the mixed matrix based on the sparse signal. Finally, the separation of the source signals can be achieved according to the shortest path method. To validate the effectiveness of the proposed method, the simulated signals and vibration signals measured from faulty roller bearings are used. The faults that occur in a roller bearing are the outer-race flaw, the inner-race flaw and the rolling element flaw. The results show that the fault features acquired using the proposed approach are evidently close to the theoretical values. For instance, the inner-race feature frequency 101.3 Hz is very similar to the theoretical calculation 101 Hz. Therefore, it is effective to achieve the separation of compound faults utilizing the suggest method, even in underdetermined cases. In addition, a comparison is applied to prove that the proposed method outperforms the traditional SCA method when the vibration signals are inadequate. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 2102 KiB

Open AccessArticle

Improved Short-Term Clock Prediction Method for Real-Time Positioning

by Yifei Lv, Zhiqiang Dai^*, Qile Zhao^*, Sheng Yang, Jinning Zhou and Jingnan Liu

GNSS Research Center, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

Sensors 2017, 17(6), 1308; https://doi.org/10.3390/s17061308 - 6 Jun 2017

Cited by 28 | Viewed by 4645

Abstract

The application of real-time precise point positioning (PPP) requires real-time precise orbit and clock products that should be predicted within a short time to compensate for the communication delay or data gap. Unlike orbit correction, clock correction is difficult to model and predict. [...] Read more.

The application of real-time precise point positioning (PPP) requires real-time precise orbit and clock products that should be predicted within a short time to compensate for the communication delay or data gap. Unlike orbit correction, clock correction is difficult to model and predict. The widely used linear model hardly fits long periodic trends with a small data set and exhibits significant accuracy degradation in real-time prediction when a large data set is used. This study proposes a new prediction model for maintaining short-term satellite clocks to meet the high-precision requirements of real-time clocks and provide clock extrapolation without interrupting the real-time data stream. Fast Fourier transform (FFT) is used to analyze the linear prediction residuals of real-time clocks. The periodic terms obtained through FFT are adopted in the sliding window prediction to achieve a significant improvement in short-term prediction accuracy. This study also analyzes and compares the accuracy of short-term forecasts (less than 3 h) by using different length observations. Experimental results obtained from International GNSS Service (IGS) final products and our own real-time clocks show that the 3-h prediction accuracy is better than 0.85 ns. The new model can replace IGS ultra-rapid products in the application of real-time PPP. It is also found that there is a positive correlation between the prediction accuracy and the short-term stability of on-board clocks. Compared with the accuracy of the traditional linear model, the accuracy of the static PPP using the new model of the 2-h prediction clock in N, E, and U directions is improved by about 50%. Furthermore, the static PPP accuracy of 2-h clock products is better than 0.1 m. When an interruption occurs in the real-time model, the accuracy of the kinematic PPP solution using 1-h clock prediction product is better than 0.2 m, without significant accuracy degradation. This model is of practical significance because it solves the problems of interruption and delay in data broadcast in real-time clock estimation and can meet the requirements of real-time PPP. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 4881 KiB

Open AccessArticle

A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity

by Juan D. Reverte-Ors¹, Juan L. Pedreño-Molina^1,*, Pablo S. Fernández², Antonio J. Lozano-Guerrero¹, Paula M. Periago² and Alejandro Díaz-Morcillo¹

¹ Department of Information and Communication Technologies, Universidad Politécnica de Cartagena, Plaza del Hospital, 1, 30202 Cartagena (Murcia), Spain

² Department of Food Engineering and Agricultural Equipment, Universidad Politécnica de Cartagena, Paseo Alfonso XIII, 48, 30203 Cartagena (Murcia), Spain

Sensors 2017, 17(6), 1309; https://doi.org/10.3390/s17061309 - 7 Jun 2017

Cited by 9 | Viewed by 4856

Abstract

In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and [...] Read more.

In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures. Full article

(This article belongs to the Section Physical Sensors)

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6 pages, 1896 KiB

Open AccessArticle

Development of High Sensitivity Humidity Sensor Based on Gray TiO₂/SrTiO₃ Composite

by Min Zhang¹, Shunhang Wei², Wei Ren^3,* and Rong Wu^1,*

¹ The School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China

² Shanghai Key Lab of Chemical Assessment and Sustainability, School of Chemical Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China

³ Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry, CAS, Urumqi 830011, China

Sensors 2017, 17(6), 1310; https://doi.org/10.3390/s17061310 - 7 Jun 2017

Cited by 20 | Viewed by 4919

Abstract

A gray TiO₂/SrTiO₃ composite nanocrystalline sensor with narrow band-gap was successfully prepared through a facile wet chemical method. The precursor was calcined in N₂ flow under atmospheric pressure and thereafter, a humidity sensor based on the composite was fabricated. [...] Read more.

A gray TiO₂/SrTiO₃ composite nanocrystalline sensor with narrow band-gap was successfully prepared through a facile wet chemical method. The precursor was calcined in N₂ flow under atmospheric pressure and thereafter, a humidity sensor based on the composite was fabricated. The sensor showed high resistive sensitivity and varied by more than four orders of magnitude with an increase in relative humidity (RH) from 11% to 95%. The response and recovery time were about 3.1 s and 76 s, respectively with maximum hysteresis at 1% RH. In comparison with pure SrTiO₃ and black TiO₂, the gray composite based device exhibits a higher sensitivity. These results demonstrate the potential of gray TiO₂/SrTiO₃ for humidity sensing applications. Full article

(This article belongs to the Special Issue Humidity Sensors)

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14 pages, 4015 KiB

Open AccessArticle

Development of Laser Scanner for Full Cross-Sectional Deformation Monitoring of Underground Gateroads

by Qianlong Yang^1,2, Zhenyu Zhang^1,*

, Xiaoqian Liu¹ and Shuqi Ma^3,4

¹ State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

² Laboratory and Equipment Managing Division, Chongqing University, Chongqing 400044, China

³ School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639789, Singapore

⁴ Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China

Sensors 2017, 17(6), 1311; https://doi.org/10.3390/s17061311 - 7 Jun 2017

Cited by 10 | Viewed by 5690

Abstract

The deformation of underground gateroads tends to be asymmetric and complex. Traditional instrumentation fails to accurately and conveniently monitor the full cross-sectional deformation of underground gateroads. Here, a full cross-sectional laser scanner was developed, together with a visualization software package. The developed system [...] Read more.

The deformation of underground gateroads tends to be asymmetric and complex. Traditional instrumentation fails to accurately and conveniently monitor the full cross-sectional deformation of underground gateroads. Here, a full cross-sectional laser scanner was developed, together with a visualization software package. The developed system used a polar coordinate measuring method and the full cross-sectional measurement was shown by 360° rotation of a laser sensor driven by an electrical motor. Later on, the potential impact of gateroad wall flatness, roughness, and geometrical profile, as well as coal dust environment on the performance of the developed laser scanner will be evaluated. The study shows that high-level flatness is favorable in the application of the developed full cross-sectional deformation monitoring system. For a smooth surface of gateroad, the sensor cannot receive reflected light when the incidence angle of laser beam is large, causing data loss. Conversely, the roughness surface shows its nature as the diffuse reflection light can be received by the sensor. With regards to coal dust in the measurement environment, fine particles of floating coal dust in the air can lead to the loss of measurement data to some extent, due to scattering of the laser beam. Full article

(This article belongs to the Special Issue Sensors for Deformation Monitoring of Large Civil Infrastructures)

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17 pages, 5911 KiB

Open AccessArticle

A Capacitance-To-Digital Converter for MEMS Sensors for Smart Applications

by Javier Pérez Sanjurjo^1,*, Enrique Prefasi¹

, Cesare Buffa² and Richard Gaggl²

¹ Electronic Technology Department, Carlos III University of Madrid, Madrid 28911, Spain

² Infineon Technologies, RF & Sensors, Villach 9500, Austria

Sensors 2017, 17(6), 1312; https://doi.org/10.3390/s17061312 - 7 Jun 2017

Cited by 24 | Viewed by 11823

Abstract

The use of MEMS sensors has been increasing in recent years. To cover all the applications, many different readout circuits are needed. To reduce the cost and time to market, a generic capacitance-to-digital converter (CDC) seems to be the logical next step. This [...] Read more.

The use of MEMS sensors has been increasing in recent years. To cover all the applications, many different readout circuits are needed. To reduce the cost and time to market, a generic capacitance-to-digital converter (CDC) seems to be the logical next step. This work presents a configurable CDC designed for capacitive MEMS sensors. The sensor is built with a bridge of MEMS, where some of them function with pressure. Then, the capacitive to digital conversion is realized using two steps. First, a switched-capacitor (SC) preamplifier is used to make the capacitive to voltage (C-V) conversion. Second, a self-oscillated noise-shaping integrating dual-slope (DS) converter is used to digitize this magnitude. The proposed converter uses time instead of amplitude resolution to generate a multibit digital output stream. In addition it performs noise shaping of the quantization error to reduce measurement time. This article shows the effectiveness of this method by measurements performed on a prototype, designed and fabricated using standard 0.13 µm CMOS technology. Experimental measurements show that the CDC achieves a resolution of 17 bits, with an effective area of 0.317 mm², which means a pressure resolution of 1 Pa, while consuming 146 µA from a 1.5 V power supply. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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22 pages, 7313 KiB

Open AccessArticle

Spatial Characterization of Radio Propagation Channel in Urban Vehicle-to-Infrastructure Environments to Support WSNs Deployment

by Fausto Granda^1,2

, Leyre Azpilicueta^2,*

, Cesar Vargas-Rosales², Peio Lopez-Iturri³

, Erik Aguirre³

, Jose Javier Astrain^4,5

, Jesus Villandangos^4,5

and Francisco Falcone^3,5

¹ Electrical and Electronic Engineering Dept., Universidad de las Fuerzas Armadas ESPE, Sangolquí 171-5-231B, Ecuador

² School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey 64849, Mexico

³ Electrical and Electronic Engineering Dept, Public University of Navarre, Pamplona 31006, Spain

⁴ Mathematical Engineering and Computer Science Department, Public University of Navarre, Pamplona 31006, Spain

⁵ Institute of Smart Cities, Public University of Navarre, Pamplona 31006, Spain

Sensors 2017, 17(6), 1313; https://doi.org/10.3390/s17061313 - 7 Jun 2017

Cited by 22 | Viewed by 5173

Abstract

Vehicular ad hoc Networks (VANETs) enable vehicles to communicate with each other as well as with roadside units (RSUs). Although there is a significant research effort in radio channel modeling focused on vehicle-to-vehicle (V2V), not much work has been done for vehicle-to-infrastructure (V2I) [...] Read more.

Vehicular ad hoc Networks (VANETs) enable vehicles to communicate with each other as well as with roadside units (RSUs). Although there is a significant research effort in radio channel modeling focused on vehicle-to-vehicle (V2V), not much work has been done for vehicle-to-infrastructure (V2I) using 3D ray-tracing tools. This work evaluates some important parameters of a V2I wireless channel link such as large-scale path loss and multipath metrics in a typical urban scenario using a deterministic simulation model based on an in-house 3D Ray-Launching (3D-RL) algorithm at 5.9 GHz. Results show the high impact that the spatial distance; link frequency; placement of RSUs; and factors such as roundabout, geometry and relative position of the obstacles have in V2I propagation channel. A detailed spatial path loss characterization of the V2I channel along the streets and avenues is presented. The 3D-RL results show high accuracy when compared with measurements, and represent more reliably the propagation phenomena when compared with analytical path loss models. Performance metrics for a real test scenario implemented with a VANET wireless sensor network implemented ad-hoc are also described. These results constitute a starting point in the design phase of Wireless Sensor Networks (WSNs) radio-planning in the urban V2I deployment in terms of coverage. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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16 pages, 3617 KiB

Open AccessArticle

Tyrosinase-Based Biosensors for Selective Dopamine Detection

by Monica Florescu^*

and Melinda David

Faculty of Medicine, Transilvania University of Brasov, 500019 Brasov, Romania

Sensors 2017, 17(6), 1314; https://doi.org/10.3390/s17061314 - 7 Jun 2017

Cited by 60 | Viewed by 7592

Abstract

A novel tyrosinase-based biosensor was developed for the detection of dopamine (DA). For increased selectivity, gold electrodes were previously modified with cobalt (II)-porphyrin (CoP) film with electrocatalytic activity, to act both as an electrochemical mediator and an enzyme support, upon which the enzyme [...] Read more.

A novel tyrosinase-based biosensor was developed for the detection of dopamine (DA). For increased selectivity, gold electrodes were previously modified with cobalt (II)-porphyrin (CoP) film with electrocatalytic activity, to act both as an electrochemical mediator and an enzyme support, upon which the enzyme tyrosinase (Tyr) was cross-linked. Differential pulse voltammetry was used for electrochemical detection and the reduction current of dopamine-quinone was measured as a function of dopamine concentration. Our experiments demonstrated that the presence of CoP improves the selectivity of the electrode towards dopamine in the presence of ascorbic acid (AA), with a linear trend of concentration dependence in the range of 2–30 µM. By optimizing the conditioning parameters, a separation of 130 mV between the peak potentials for ascorbic acid AA and DA was obtained, allowing the selective detection of DA. The biosensor had a sensitivity of 1.22 ± 0.02 µA·cm⁻²·µM⁻¹ and a detection limit of 0.43 µM. Biosensor performances were tested in the presence of dopamine medication, with satisfactory results in terms of recovery (96%), and relative standard deviation values below 5%. These results confirmed the applicability of the biosensors in real samples such as human urine and blood serum. Full article

(This article belongs to the Special Issue Sensors for Biomedical, Environmental and Food Monitoring Applications)

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12 pages, 3014 KiB

Open AccessArticle

Joint Estimation of Source Range and Depth Using a Bottom-Deployed Vertical Line Array in Deep Water

by Hui Li^1,2, Kunde Yang^1,2,*, Rui Duan^1,2 and Zhixiong Lei^1,2

¹ School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

² Key Laboratory of Ocean Acoustics and Sensing(Northwestern Polytechnical University), Ministry of Industry and Information Technology, Xi’an 710072, China

Sensors 2017, 17(6), 1315; https://doi.org/10.3390/s17061315 - 7 Jun 2017

Cited by 18 | Viewed by 4493

Abstract

This paper presents a joint estimation method of source range and depth using a bottom-deployed vertical line array (VLA). The method utilizes the information on the arrival angle of direct (D) path in space domain and the interference characteristic of D and surface-reflected [...] Read more.

This paper presents a joint estimation method of source range and depth using a bottom-deployed vertical line array (VLA). The method utilizes the information on the arrival angle of direct (D) path in space domain and the interference characteristic of D and surface-reflected (SR) paths in frequency domain. The former is related to a ray tracing technique to backpropagate the rays and produces an ambiguity surface of source range. The latter utilizes Lloyd’s mirror principle to obtain an ambiguity surface of source depth. The acoustic transmission duct is the well-known reliable acoustic path (RAP). The ambiguity surface of the combined estimation is a dimensionless ad hoc function. Numerical efficiency and experimental verification show that the proposed method is a good candidate for initial coarse estimation of source position. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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14 pages, 3707 KiB

Open AccessArticle

Design and Fabrication of a Ratiometric Planar Optode for Simultaneous Imaging of pH and Oxygen

by Zike Jiang, Xinsheng Yu^*

and Yingyan Hao

Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, College of Marine Geosciences, Ocean University of China, Qingdao 266100, China

Sensors 2017, 17(6), 1316; https://doi.org/10.3390/s17061316 - 7 Jun 2017

Cited by 23 | Viewed by 7582

Abstract

This paper presents a simple, high resolution imaging approach utilizing ratiometric planar optode for simultaneous measurement of dissolved oxygen (DO) and pH. The planar optode comprises a plastic optical film coated with oxygen indicator Platinum(II) octaethylporphyrin (PtOEP) and reference quantum dots (QDs) embedded [...] Read more.

This paper presents a simple, high resolution imaging approach utilizing ratiometric planar optode for simultaneous measurement of dissolved oxygen (DO) and pH. The planar optode comprises a plastic optical film coated with oxygen indicator Platinum(II) octaethylporphyrin (PtOEP) and reference quantum dots (QDs) embedded in polystyrene (PS), pH indicator 5-Hexadecanoylamino-fluorescein (5-Fluorescein) embedded in Hydromed D4 matrix. The indicator and reference dyes are excited by utilizing an LED (Light Emitting Diode) source with a central wavelength of 405 nm, the emission respectively matches the different channels (red, green, and blue) of a 3CCD camera after eliminating the excitation source by utilizing the color filter. The result shows that there is low cross-sensitivity between the two analytes dissolved oxygen and pH, and it shows good performance in the dynamic response ranges of 0–12 mg/L and a dynamic range of pH 6−8. The optode has been tested with regard to the response times, accuracy, photostability and stability. The applied experiment for detecting pH/Oxygen of sea-water under the influence of the rain drops is demonstrated. It is shown that the planar optode measuring system provides a simple method with low cross-talk for pH/Oxygen imaging in aqueous applications. Full article

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

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24 pages, 2134 KiB

Open AccessArticle

Improving Multidimensional Wireless Sensor Network Lifetime Using Pearson Correlation and Fractal Clustering

by Fernando R. Almeida^1,2,*,†, Angelo Brayner³, Joel J. P. C. Rodrigues^4,5,6

and Jose E. Bessa Maia⁷

¹ PPGIA, University of Fortaleza (UNIFOR), Fortaleza 60811-905, Brazil

² Computer Engineering, Federal University of Ceará (UFC), Campus de Sobral, Sobral 62010-560, Brazil

³ Department of Computer Science, Federal University of Ceará (UFC), Fortaleza 60440-900, Brazil

⁴ National Institute of Telecommunications (Inatel), Santa Rita do Sapucaí 37540-000, Brazil

⁵ Instituto de Telecomunicações, Universidade da Beira Interior, Covilhã 6201-001, Portugal

⁶ ITMO University, St. Petersburg 197101, Russia

⁷ University of Fortaleza (UNIFOR), Fortaleza 60811-905, Brazil

^† Current address: Federal University of Ceará (UFC), Rua Estanislau Frota, s/n - Bloco de Tecnologia, Campus do Mucambinho—Centro, Sobral–CE 62010-560, Brazil.

Sensors 2017, 17(6), 1317; https://doi.org/10.3390/s17061317 - 7 Jun 2017

Cited by 24 | Viewed by 4601

Abstract

An efficient strategy for reducing message transmission in a wireless sensor network (WSN) is to group sensors by means of an abstraction denoted cluster. The key idea behind the cluster formation process is to identify a set of sensors whose sensed values present [...] Read more.

An efficient strategy for reducing message transmission in a wireless sensor network (WSN) is to group sensors by means of an abstraction denoted cluster. The key idea behind the cluster formation process is to identify a set of sensors whose sensed values present some data correlation. Nowadays, sensors are able to simultaneously sense multiple different physical phenomena, yielding in this way multidimensional data. This paper presents three methods for clustering sensors in WSNs whose sensors collect multidimensional data. The proposed approaches implement the concept of multidimensional behavioral clustering. To show the benefits introduced by the proposed methods, a prototype has been implemented and experiments have been carried out on real data. The results prove that the proposed methods decrease the amount of data flowing in the network and present low root-mean-square error (RMSE). Full article

(This article belongs to the Special Issue Selected Papers from International Conference on Ubiquitous and Future Networks (ICUFN 2016))

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22 pages, 5571 KiB

Open AccessArticle

An Empirical Study of the Transmission Power Setting for Bluetooth-Based Indoor Localization Mechanisms

by Manuel Castillo-Cara^1,2,*,†

, Jesús Lovón-Melgarejo^1,†, Gusseppe Bravo-Rocca¹, Luis Orozco-Barbosa² and Ismael García-Varea²

¹ Computer Science School, Sciences Faculty, Center of Information and Communication Technologies, Universidad Nacional de Ingeniería, Lima 25, Peru

² Albacete Research Institute of Informatics, Universidad de Castilla-La Mancha, 02071 Albacete, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1318; https://doi.org/10.3390/s17061318 - 7 Jun 2017

Cited by 41 | Viewed by 9289

Abstract

Nowadays, there is a great interest in developing accurate wireless indoor localization mechanisms enabling the implementation of many consumer-oriented services. Among the many proposals, wireless indoor localization mechanisms based on the Received Signal Strength Indication (RSSI) are being widely explored. Most studies have [...] Read more.

Nowadays, there is a great interest in developing accurate wireless indoor localization mechanisms enabling the implementation of many consumer-oriented services. Among the many proposals, wireless indoor localization mechanisms based on the Received Signal Strength Indication (RSSI) are being widely explored. Most studies have focused on the evaluation of the capabilities of different mobile device brands and wireless network technologies. Furthermore, different parameters and algorithms have been proposed as a means of improving the accuracy of wireless-based localization mechanisms. In this paper, we focus on the tuning of the RSSI fingerprint to be used in the implementation of a Bluetooth Low Energy 4.0 (BLE4.0) Bluetooth localization mechanism. Following a holistic approach, we start by assessing the capabilities of two Bluetooth sensor/receiver devices. We then evaluate the relevance of the RSSI fingerprint reported by each BLE4.0 beacon operating at various transmission power levels using feature selection techniques. Based on our findings, we use two classification algorithms in order to improve the setting of the transmission power levels of each of the BLE4.0 beacons. Our main findings show that our proposal can greatly improve the localization accuracy by setting a custom transmission power level for each BLE4.0 beacon. Full article

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

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12 pages, 5936 KiB

Open AccessArticle

Artificial Neural Network-Based Early-Age Concrete Strength Monitoring Using Dynamic Response Signals

by Junkyeong Kim¹

, Chaggil Lee¹ and Seunghee Park^2,*

¹ Department of Civil & Environmental System Engineering, Sungkyunkwan University 2066, Seobu-ro, Jangan-gu, Suwon-si, 16419 Gyonggi-do, Korea

² School of Civil & Architectural Engineering, Sungkyunkwan University 2066, Seobu-ro, Jangan-gu, Suwon-si, 16419 Gyonggi-do, Korea

Sensors 2017, 17(6), 1319; https://doi.org/10.3390/s17061319 - 7 Jun 2017

Cited by 30 | Viewed by 5507

Abstract

Concrete is one of the most common materials used to construct a variety of civil infrastructures. However, since concrete might be susceptible to brittle fracture, it is essential to confirm the strength of concrete at the early-age stage of the curing process to [...] Read more.

Concrete is one of the most common materials used to construct a variety of civil infrastructures. However, since concrete might be susceptible to brittle fracture, it is essential to confirm the strength of concrete at the early-age stage of the curing process to prevent unexpected collapse. To address this issue, this study proposes a novel method to estimate the early-age strength of concrete, by integrating an artificial neural network algorithm with a dynamic response measurement of the concrete material. The dynamic response signals of the concrete, including both electromechanical impedances and guided ultrasonic waves, are obtained from an embedded piezoelectric sensor module. The cross-correlation coefficient of the electromechanical impedance signals and the amplitude of the guided ultrasonic wave signals are selected to quantify the variation in dynamic responses according to the strength of the concrete. Furthermore, an artificial neural network algorithm is used to verify a relationship between the variation in dynamic response signals and concrete strength. The results of an experimental study confirm that the proposed approach can be effectively applied to estimate the strength of concrete material from the early-age stage of the curing process. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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28 pages, 1920 KiB

Open AccessArticle

A Reliable Data Transmission Model for IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi Interference

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, Linkou 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(6), 1320; https://doi.org/10.3390/s17061320 - 7 Jun 2017

Cited by 35 | Viewed by 8016

Abstract

The IEEE 802.15.4e standard proposes Medium Access Control (MAC) to support collision-free wireless channel access mechanisms for industrial, commercial and healthcare applications. However, unnecessary wastage of energy and bandwidth consumption occur due to inefficient backoff management and collisions. In this paper, a new [...] Read more.

The IEEE 802.15.4e standard proposes Medium Access Control (MAC) to support collision-free wireless channel access mechanisms for industrial, commercial and healthcare applications. However, unnecessary wastage of energy and bandwidth consumption occur due to inefficient backoff management and collisions. In this paper, a new channel access mechanism is designed for the buffer constraint sensor devices to reduce the packet drop rate, energy consumption and collisions. In order to avoid collision due to the hidden terminal problem, a new frame structure is designed for the data transmission. A new superframe structure is proposed to mitigate the problems due to WiFi and ZigBee interference. A modified superframe structure with a new retransmission opportunity for failure devices is proposed to reduce the collisions and retransmission delay with high reliability. Performance evaluation and validation of our scheme indicate that the packet drop rate, throughput, reliability, energy consumption and average delay of the nodes can be improved significantly. Full article

(This article belongs to the Collection Smart Communication Protocols and Algorithms for Sensor Networks)

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21 pages, 1652 KiB

Open AccessArticle

Faller Classification in Older Adults Using Wearable Sensors Based on Turn and Straight-Walking Accelerometer-Based Features

by Dylan Drover¹, Jennifer Howcroft¹, Jonathan Kofman^1,* and Edward D. Lemaire^2,3

¹ Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada

² Centre for Rehabilitation Research and Development, Ottawa Hospital Research Institute, Ottawa, ON K1H 8M2, Canada

³ Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada

Sensors 2017, 17(6), 1321; https://doi.org/10.3390/s17061321 - 7 Jun 2017

Cited by 52 | Viewed by 6648

Abstract

Faller classification in elderly populations can facilitate preventative care before a fall occurs. A novel wearable-sensor based faller classification method for the elderly was developed using accelerometer-based features from straight walking and turns. Seventy-six older individuals (74.15 ± 7.0 years), categorized as prospective [...] Read more.

Faller classification in elderly populations can facilitate preventative care before a fall occurs. A novel wearable-sensor based faller classification method for the elderly was developed using accelerometer-based features from straight walking and turns. Seventy-six older individuals (74.15 ± 7.0 years), categorized as prospective fallers and non-fallers, completed a six-minute walk test with accelerometers attached to their lower legs and pelvis. After segmenting straight and turn sections, cross validation tests were conducted on straight and turn walking features to assess classification performance. The best “classifier model—feature selector” combination used turn data, random forest classifier, and select-5-best feature selector (73.4% accuracy, 60.5% sensitivity, 82.0% specificity, and 0.44 Matthew’s Correlation Coefficient (MCC)). Using only the most frequently occurring features, a feature subset (minimum of anterior-posterior ratio of even/odd harmonics for right shank, standard deviation (SD) of anterior left shank acceleration SD, SD of mean anterior left shank acceleration, maximum of medial-lateral first quartile of Fourier transform (FQFFT) for lower back, maximum of anterior-posterior FQFFT for lower back) achieved better classification results, with 77.3% accuracy, 66.1% sensitivity, 84.7% specificity, and 0.52 MCC score. All classification performance metrics improved when turn data was used for faller classification, compared to straight walking data. Combining turn and straight walking features decreased performance metrics compared to turn features for similar classifier model—feature selector combinations. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Canada 2017)

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16 pages, 4189 KiB

Open AccessArticle

Adaptive Grouping Distributed Compressive Sensing Reconstruction of Plant Hyperspectral Data

by Ping Xu, Junfeng Liu, Lingyun Xue^*, Jingcheng Zhang^* and Bo Qiu

College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018, China

Sensors 2017, 17(6), 1322; https://doi.org/10.3390/s17061322 - 7 Jun 2017

Cited by 11 | Viewed by 4514

Abstract

With the development of hyperspectral technology, to establish an effective spectral data compressive reconstruction method that can improve data storage, transmission, and maintaining spectral information is critical for quantitative remote sensing research and application in vegetation. The spectral adaptive grouping distributed compressive sensing [...] Read more.

With the development of hyperspectral technology, to establish an effective spectral data compressive reconstruction method that can improve data storage, transmission, and maintaining spectral information is critical for quantitative remote sensing research and application in vegetation. The spectral adaptive grouping distributed compressive sensing (AGDCS) algorithm is proposed, which enables a distributed compressed sensing reconstruction of plant hyperspectral data. The spectral characteristics of hyperspectral data are analyzed and the joint sparse model is constructed. The spectral bands are adaptively grouped and the hyperspectral data are compressed and reconstructed on the basis of grouping. The experimental results showed that, compared with orthogonal matching pursuit (OMP) and gradient projection for sparse reconstruction (GPSR), AGDCS can significantly improve the visual effect of image reconstruction in the spatial domain. The peak signal-to-noise ratio (PSNR) at a low sampling rate (the sampling rate is lower than 0.2) increases by 13.72 dB than OMP and 1.66 dB than GPSR. In the spectral domain, the average normalized root mean square error, the mean absolute percentage error, and the mean absolute error of AGDCS is 35.38%, 31.83%, and 33.33% lower than GPSR, respectively. Additionally, AGDCS can achieve relatively high reconstructed efficiency. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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12 pages, 3605 KiB

Open AccessArticle

Left–Right Asymmetry in Spectral Characteristics of Lung Sounds Detected Using a Dual-Channel Auscultation System in Healthy Young Adults

by Jang-Zern Tsai¹, Ming-Lang Chang¹

, Jiun-Yue Yang¹, Dar Kuo², Ching-Hsiung Lin^3,4,5 and Cheng-Deng Kuo^5,6,*

¹ Department of Electrical Engineering, National Central University, Zhongli, Taiyuan 320, Taiwan

² Mt. San Antonio College, Walnut, CA 91789, USA

³ Department of Respiratory Care, College of Health Sciences, Chang Jung Christian University, Tainan 711, Taiwan

⁴ School of Medicine, Chung Shan Medical University, Taichung 402, Taiwan

⁵ Division of Chest Medicine, Department of Internal Medicine, Changhua Christian Hospital, Changhua 500, Taiwan

⁶ Laboratory of Biophysics, Department of Medical Research, Taipei Veterans General Hospital, Taipei 112, Taiwan

Sensors 2017, 17(6), 1323; https://doi.org/10.3390/s17061323 - 7 Jun 2017

Cited by 4 | Viewed by 6471

Abstract

Though lung sounds auscultation is important for the diagnosis and monitoring of lung diseases, the spectral characteristics of lung sounds have not been fully understood. This study compared the spectral characteristics of lung sounds between the right and left lungs and between healthy [...] Read more.

Though lung sounds auscultation is important for the diagnosis and monitoring of lung diseases, the spectral characteristics of lung sounds have not been fully understood. This study compared the spectral characteristics of lung sounds between the right and left lungs and between healthy male and female subjects using a dual-channel auscultation system. Forty-two subjects aged 18–22 years without smoking habits and any known pulmonary diseases participated in this study. The lung sounds were recorded from seven pairs of auscultation sites on the chest wall simultaneously. We found that in four out of seven auscultation pairs, the lung sounds from the left lung had a higher total power (P_T) than those from the right lung. The P_T of male subjects was higher than that of female ones in most auscultation pairs. The ratio of inspiration power to expiration power (R_I/E) of lung sounds from the right lung was greater than that from the left lung at auscultation pairs on the anterior chest wall, while this phenomenon was reversed at auscultation pairs on the posterior chest wall in combined subjects, and similarly in both male and female subjects. Though the frequency corresponding to maximum power density of lung sounds (F_MPD) from the left and right lungs was not significantly different, the frequency that equally divided the power spectrum of lung sounds (F₅₀) from the left lung was significantly smaller than that from the right lung at auscultation site on the anterior and lateral chest walls, while it was significantly larger than that of from the right lung at auscultation site on the posterior chest walls. In conclusion, significant differences in the P_T, F_MPD, F₅₀, and R_I/E between the left and right lungs at some auscultation pairs were observed by using a dual-channel auscultation system in this study. Structural differences between the left and the right lungs, between the female and male subjects, and between anterior and posterior lungs might account for the observed differences in the spectral characteristics of lung sounds. The dual-channel auscultation system might be useful for future development of digital stethoscopes and power spectral analysis of lung sounds in patients with various kinds of cardiopulmonary diseases. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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13 pages, 3855 KiB

Open AccessArticle

Calibration of Magnetometers with GNSS Receivers and Magnetometer-Aided GNSS Ambiguity Fixing

by Patrick Henkel

Department of Electrical and Computer Engineering, Technische Universität München, Arcisstrasse 21, 80333 München, Germany

Sensors 2017, 17(6), 1324; https://doi.org/10.3390/s17061324 - 8 Jun 2017

Cited by 8 | Viewed by 6612

Abstract

Magnetometers provide compass information, and are widely used for navigation, orientation and alignment of objects. As magnetometers are affected by sensor biases and eventually by systematic distortions of the Earth magnetic field, a calibration is needed. In this paper, a method for calibration [...] Read more.

Magnetometers provide compass information, and are widely used for navigation, orientation and alignment of objects. As magnetometers are affected by sensor biases and eventually by systematic distortions of the Earth magnetic field, a calibration is needed. In this paper, a method for calibration of magnetometers with three Global Navigation Satellite System (GNSS) receivers is presented. We perform a least-squares estimation of the magnetic flux and sensor biases using GNSS-based attitude information. The attitude is obtained from the relative positions between the GNSS receivers in the North-East-Down coordinate frame and prior knowledge of these relative positions in the platform’s coordinate frame. The relative positions and integer ambiguities of the periodic carrier phase measurements are determined with an integer least-squares estimation using an integer decorrelation and sequential tree search. Prior knowledge on the relative positions is used to increase the success rate of ambiguity fixing. We have validated the proposed method with low-cost magnetometers and GNSS receivers on a vehicle in a test drive. The calibration enabled a consistent heading determination with an accuracy of five degrees. This precise magnetometer-based attitude information allows an instantaneous GNSS integer ambiguity fixing. Full article

(This article belongs to the Special Issue Magnetoelectric Heterostructures and Sensors)

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22 pages, 6367 KiB

Open AccessArticle

Study on Impact Acoustic—Visual Sensor-Based Sorting of ELV Plastic Materials

by Jiu Huang^*, Chuyuan Tian, Jingwei Ren and Zhengfu Bian

School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou 221000, China

Sensors 2017, 17(6), 1325; https://doi.org/10.3390/s17061325 - 8 Jun 2017

Cited by 20 | Viewed by 5465

Abstract

This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles’ (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based [...] Read more.

This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles’ (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41.4% for PP/EPDM scraps as well as 62.4% for ABS, and 70.8% for ABS/PC scraps. Within the diameter range of 8-13 mm, only 25% of PP and 27% of PP/EPDM scraps, as well as 43% of ABS, and 47% of ABS/PC scraps were finally separated. This research proposes a new approach for sensor-aided automatic recognition and sorting of black plastic materials, it is an effective method for ASR reduction and recycling. Full article

(This article belongs to the Special Issue Acoustic Wave Resonator-Based Sensors)

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25 pages, 6450 KiB

Open AccessArticle

Automatic Artifact Removal in EEG of Normal and Demented Individuals Using ICA–WT during Working Memory Tasks

by Noor Kamal Al-Qazzaz^1,2,*, Sawal Hamid Bin Mohd Ali¹, Siti Anom Ahmad^3,4

, Mohd Shabiul Islam⁵ and Javier Escudero⁶

¹ Department of Electrical, Electronic & Systems Engineering, Faculty of Engineering & Built Environment, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor 43600, Malaysia

² Department of Biomedical Engineering, Al-Khwarizmi College of Engineering, Baghdad University, Baghdad 47146, Iraq

³ Department of Electrical and Electronic Engineering, Faculty of Engineering, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia

⁴ Malaysian Research Institute of Ageing (MyAgeing), Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia

⁵ Faculty of Engineering, Multimedia Universiti, MMU Cyberjaya, Selangor 63100, Malaysia

⁶ Institute for Digital Communications, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FB, UK

Sensors 2017, 17(6), 1326; https://doi.org/10.3390/s17061326 - 8 Jun 2017

Cited by 64 | Viewed by 6668

Abstract

Characterizing dementia is a global challenge in supporting personalized health care. The electroencephalogram (EEG) is a promising tool to support the diagnosis and evaluation of abnormalities in the human brain. The EEG sensors record the brain activity directly with excellent time resolution. In [...] Read more.

Characterizing dementia is a global challenge in supporting personalized health care. The electroencephalogram (EEG) is a promising tool to support the diagnosis and evaluation of abnormalities in the human brain. The EEG sensors record the brain activity directly with excellent time resolution. In this study, EEG sensor with 19 electrodes were used to test the background activities of the brains of five vascular dementia (VaD), 15 stroke-related patients with mild cognitive impairment (MCI), and 15 healthy subjects during a working memory (WM) task. The objective of this study is twofold. First, it aims to enhance the recorded EEG signals using a novel technique that combines automatic independent component analysis (AICA) and wavelet transform (WT), that is, the AICA–WT technique; second, it aims to extract and investigate the spectral features that characterize the post-stroke dementia patients compared to the control subjects. The proposed AICA–WT technique is a four-stage approach. In the first stage, the independent components (ICs) were estimated. In the second stage, three-step artifact identification metrics were applied to detect the artifactual components. The components identified as artifacts were marked as critical and denoised through DWT in the third stage. In the fourth stage, the corrected ICs were reconstructed to obtain artifact-free EEG signals. The performance of the proposed AICA–WT technique was compared with those of two other techniques based on AICA and WT denoising methods using cross-correlation

X C o r r

and peak signal to noise ratio

(P S N R)

(ANOVA,

p

˂ 0.05). The AICA–WT technique exhibited the best artifact removal performance. The assumption that there would be a deceleration of EEG dominant frequencies in VaD and MCI patients compared with control subjects was assessed with AICA–WT (ANOVA,

p

˂ 0.05). Therefore, this study may provide information on post-stroke dementia particularly VaD and stroke-related MCI patients through spectral analysis of EEG background activities that can help to provide useful diagnostic indexes by using EEG signal processing. Full article

(This article belongs to the Section Biosensors)

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22 pages, 2108 KiB

Open AccessArticle

Data Acquisition Based on Stable Matching of Bipartite Graph in Cooperative Vehicle–Infrastructure Systems

by Xiaolan Tang, Donghui Hong and Wenlong Chen^*

College of Information Engineering, Capital Normal University, Beijing 100048, China

Sensors 2017, 17(6), 1327; https://doi.org/10.3390/s17061327 - 8 Jun 2017

Cited by 10 | Viewed by 5007

Abstract

Existing studies on data acquisition in vehicular networks often take the mobile vehicular nodes as data carriers. However, their autonomous movements, limited resources and security risks impact the quality of services. In this article, we propose a data acquisition model using stable matching [...] Read more.

Existing studies on data acquisition in vehicular networks often take the mobile vehicular nodes as data carriers. However, their autonomous movements, limited resources and security risks impact the quality of services. In this article, we propose a data acquisition model using stable matching of bipartite graph in cooperative vehicle-infrastructure systems, namely, DAS. Contents are distributed to roadside units, while vehicular nodes support supplementary storage. The original distribution problem is formulated as a stable matching problem of bipartite graph, where the data and the storage cells compose two sides of vertices. Regarding the factors relevant with the access ratio and delay, the preference rankings for contents and roadside units are calculated, respectively. With a multi-replica preprocessing algorithm to handle the potential one-to-many mapping, the matching problem is addressed in polynomial time. In addition, vehicular nodes carry and forward assistant contents to deliver the failed packets because of bandwidth competition. Furthermore, an incentive strategy is put forward to boost the vehicle cooperation and to achieve a fair bandwidth allocation at roadside units. Experiments show that DAS achieves a high access ratio and a small storage cost with an acceptable delay. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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12 pages, 5978 KiB

Open AccessArticle

Development and Testing of a Dual Accelerometer Vector Sensor for AUV Acoustic Surveys

by Agni Mantouka^1,*, Paulo Felisberto¹

, Paulo Santos¹

, Friedrich Zabel², Mário Saleiro¹, Sérgio M. Jesus¹ and Luís Sebastião³

¹ Laboratory for Robotics and Engineering Systems, University of Algarve, 8005-139 Faro, Portugal

² Marsensing Lda, 8005-139 Faro, Portugal

³ Instituto Superior Téchico, Institute for Systems and Robotics,1049-001 Lisbon, Portugal

Sensors 2017, 17(6), 1328; https://doi.org/10.3390/s17061328 - 8 Jun 2017

Cited by 20 | Viewed by 5862

Abstract

This paper presents the design, manufacturing and testing of a Dual Accelerometer Vector Sensor (DAVS). The device was built within the activities of the WiMUST project, supported under the Horizon 2020 Framework Programme, which aims to improve the efficiency of the methodologies used [...] Read more.

This paper presents the design, manufacturing and testing of a Dual Accelerometer Vector Sensor (DAVS). The device was built within the activities of the WiMUST project, supported under the Horizon 2020 Framework Programme, which aims to improve the efficiency of the methodologies used to perform geophysical acoustic surveys at sea by the use of Autonomous Underwater Vehicles (AUVs). The DAVS has the potential to contribute to this aim in various ways, for example, owing to its spatial filtering capability, it may reduce the amount of post processing by discriminating the bottom from the surface reflections. Additionally, its compact size allows easier integration with AUVs and hence facilitates the vehicle manoeuvrability compared to the classical towed arrays. The present paper is focused on results related to acoustic wave azimuth estimation as an example of its spatial filtering capabilities. The DAVS device consists of two tri-axial accelerometers and one hydrophone moulded in one unit. Sensitivity and directionality of these three sensors were measured in a tank, whilst the direction estimation capabilities of the accelerometers paired with the hydrophone, forming a vector sensor, were evaluated on a Medusa Class AUV, which was sailing around a deployed sound source. Results of these measurements are presented in this paper. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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14 pages, 6863 KiB

Open AccessArticle

The Development of an Open Hardware and Software System Onboard Unmanned Aerial Vehicles to Monitor Concentrated Solar Power Plants

by Francisco Javier Mesas-Carrascosa^*

, Daniel Verdú Santano, Fernando Pérez Porras, José Emilio Meroño-Larriva

and Alfonso García-Ferrer

Department of Graphic Engineering and Geomatics, Campus de Rabanales, University of Córdoba, Córdoba 14071, Spain

Sensors 2017, 17(6), 1329; https://doi.org/10.3390/s17061329 - 8 Jun 2017

Cited by 13 | Viewed by 6502

Abstract

Concentrated solar power (CSP) plants are increasingly gaining interest as a source of renewable energy. These plants face several technical problems and the inspection of components such as absorber tubes in parabolic trough concentrators (PTC), which are widely deployed, is necessary to guarantee [...] Read more.

Concentrated solar power (CSP) plants are increasingly gaining interest as a source of renewable energy. These plants face several technical problems and the inspection of components such as absorber tubes in parabolic trough concentrators (PTC), which are widely deployed, is necessary to guarantee plant efficiency. This article presents a system for real-time industrial inspection of CSP plants using low-cost, open-source components in conjunction with a thermographic sensor and an unmanned aerial vehicle (UAV). The system, available in open-source hardware and software, is designed to be employed independently of the type of device used for inspection (laptop, smartphone, tablet or smartglasses) and its operating system. Several UAV flight missions were programmed as follows: flight altitudes at 20, 40, 60, 80, 100 and 120 m above ground level; and three cruising speeds: 5, 7 and 10 m/s. These settings were chosen and analyzed in order to optimize inspection time. The results indicate that it is possible to perform inspections by an UAV in real time at CSP plants as a means of detecting anomalous absorber tubes and improving the effectiveness of methodologies currently being utilized. Moreover, aside from thermographic sensors, this contribution can be applied to other sensors and can be used in a broad range of applications where real-time georeferenced data visualization is necessary. Full article

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

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31 pages, 4826 KiB

Open AccessArticle

Maritime Data Transfer Protocol (MDTP): A Proposal for a Data Transmission Protocol in Resource-Constrained Underwater Environments Involving Cyber-Physical Systems

by Jesús Rodríguez-Molina^1,*

, Belén Martínez²

, Sonia Bilbao² and Tamara Martín-Wanton³

¹ Research Center on Software Technologies and Multimedia Systems for Sustainability (Centro de Investigación en Tecnologías Software y Sistemas Multimedia Para la Sostenibilidad—CITSEM), Campus Sur UPM, Ctra. Valencia, Km 7, 28031 Madrid, Spain

² Tecnalia Research & Innovation, Parque Científico y Tecnológico de Bizkaia, C/Geldo, Edificio 700, 48160 Derio, Spain

³ HI Iberia Ingeniería y Proyectos, Juan Hurtado de Mendoza 14, 28036 Madrid, Spain

Sensors 2017, 17(6), 1330; https://doi.org/10.3390/s17061330 - 8 Jun 2017

Cited by 13 | Viewed by 8005

Abstract

The utilization of autonomous maritime vehicles is becoming widespread in operations that are deemed too hazardous for humans to be directly involved in them. One of the ways to increase the productivity of the tools used during missions is the deployment of several [...] Read more.

The utilization of autonomous maritime vehicles is becoming widespread in operations that are deemed too hazardous for humans to be directly involved in them. One of the ways to increase the productivity of the tools used during missions is the deployment of several vehicles with the same objective regarding data collection and transfer, both for the benefit of human staff and policy makers. However, the interchange of data in such an environment poses major challenges, such as a low bandwidth and the unreliability of the environment where transmissions take place. Furthermore, the relevant information that must be sent, as well as the exact size that will allow understanding it, is usually not clearly established, as standardization works are scarce in this domain. Under these conditions, establishing a way to interchange information at the data level among autonomous maritime vehicles becomes of critical importance since the needed information, along with the size of the transferred data, will have to be defined. This manuscript puts forward the Maritime Data Transfer Protocol, (MDTP) a way to interchange standardized pieces of information at the data level for maritime autonomous maritime vehicles, as well as the procedures that are required for information interchange. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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25 pages, 4384 KiB

Open AccessArticle

An FPGA-Based WASN for Remote Real-Time Monitoring of Endangered Species: A Case Study on the Birdsong Recognition of Botaurus stellaris

by Marcos Hervás^*

, Rosa Ma Alsina-Pagès

, Francesc Alías

and Martí Salvador

GTM—Grup de recerca en Tecnologies Mèdia, La Salle-Universitat Ramon Llull, C/Quatre Camins 30, 08022 Barcelona, Spain

Sensors 2017, 17(6), 1331; https://doi.org/10.3390/s17061331 - 8 Jun 2017

Cited by 14 | Viewed by 6635

Abstract

Fast environmental variations due to climate change can cause mass decline or even extinctions of species, having a dramatic impact on the future of biodiversity. During the last decade, different approaches have been proposed to track and monitor endangered species, generally based on [...] Read more.

Fast environmental variations due to climate change can cause mass decline or even extinctions of species, having a dramatic impact on the future of biodiversity. During the last decade, different approaches have been proposed to track and monitor endangered species, generally based on costly semi-automatic systems that require human supervision adding limitations in coverage and time. However, the recent emergence of Wireless Acoustic Sensor Networks (WASN) has allowed non-intrusive remote monitoring of endangered species in real time through the automatic identification of the sound they emit. In this work, an FPGA-based WASN centralized architecture is proposed and validated on a simulated operation environment. The feasibility of the architecture is evaluated in a case study designed to detect the threatened Botaurus stellaris among other 19 cohabiting birds species in The Parc Natural dels Aiguamolls de l’Empord Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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13 pages, 6684 KiB

Open AccessArticle

The Development of the Differential MEMS Vector Hydrophone

by Guojun Zhang^†, Mengran Liu^*,†, Nixin Shen, Xubo Wang and Wendong Zhang

¹ Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan 030051, China

^† These authors contributed equally to this study.

Sensors 2017, 17(6), 1332; https://doi.org/10.3390/s17061332 - 8 Jun 2017

Cited by 13 | Viewed by 7634

Abstract

To solve the problem that MEMS vector hydrophones are greatly interfered with by the vibration of the platform and flow noise in applications, this paper describes a differential MEMS vector hydrophone that could simultaneously receive acoustic signals and reject acceleration signals. Theoretical and [...] Read more.

To solve the problem that MEMS vector hydrophones are greatly interfered with by the vibration of the platform and flow noise in applications, this paper describes a differential MEMS vector hydrophone that could simultaneously receive acoustic signals and reject acceleration signals. Theoretical and simulation analyses have been carried out. Lastly, a prototype of the differential MEMS vector hydrophone has been created and tested using a standing wave tube and a vibration platform. The results of the test show that this hydrophone has a high sensitivity, M_v = −185 dB (@ 500 Hz, 0 dB reference 1 V/μPa), which is almost the same as the previous MEMS vector hydrophones, and has a low acceleration sensitivity, M_v = −58 dB (0 dB reference 1 V/g), which has decreased by 17 dB compared with the previous MEMS vector hydrophone. The differential MEMS vector hydrophone basically meets the requirements of acoustic vector detection when it is rigidly fixed to a working platform, which lays the foundation for engineering applications of MEMS vector hydrophones. Full article

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

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22 pages, 920 KiB

Open AccessArticle

On Line Service Composition in the Integrated Clinical Environment for eHealth and Medical Systems

by Marisol García-Valls^*

and Imad Eddine Touahria

Department of Telematics Engineering, Universidad Carlos III de Madrid, 28911 Leganés, Spain

Sensors 2017, 17(6), 1333; https://doi.org/10.3390/s17061333 - 8 Jun 2017

Cited by 7 | Viewed by 4417

Abstract

Medical and eHealth systems are progressively realized in the context of standardized architectures that support safety and ease the integration of the heterogeneous (and often proprietary) medical devices and sensors. The Integrated Clinical Environment (ICE) architecture appeared recently with the goal of becoming [...] Read more.

Medical and eHealth systems are progressively realized in the context of standardized architectures that support safety and ease the integration of the heterogeneous (and often proprietary) medical devices and sensors. The Integrated Clinical Environment (ICE) architecture appeared recently with the goal of becoming a common framework for defining the structure of the medical applications as concerns the safe integration of medical devices and sensors. ICE is simply a high level architecture that defines the functional blocks that should be part of a medical system to support interoperability. As a result, the underlying communication backbone is broadly undefined as concerns the enabling software technology (including the middleware) and associated algorithms that meet the ICE requirements of the flexible integration of medical devices and services. Supporting the on line composition of services in a medical system is also not part of ICE; however, supporting this behavior would enable flexible orchestration of functions (e.g., addition and/or removal of services and medical equipment) on the fly. iLandis one of the few software technologies that supports on line service composition and reconfiguration, ensuring time-bounded transitions across different service orchestrations; it supports the design, deployment and on line reconfiguration of applications, which this paper applies to service-based eHealth domains. This paper designs the integration between ICE architecture and iLand middleware to enhance the capabilities of ICE with on line service composition and the time-bounded reconfiguration of medical systems based on distributed services. A prototype implementation of a service-based eHealth system for the remote monitoring of patients is described; it validates the enhanced capacity of ICE to support dynamic reconfiguration of the application services. Results show that the temporal cost of the on line reconfiguration of the eHealth application is bounded, achieving a low overhead resulting from the addition of ICE compliance. Full article

(This article belongs to the Section Sensor Networks)

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18 pages, 856 KiB

Open AccessArticle

Security-Enhanced Push Button Configuration for Home Smart Control

by Junghee Han^1,*

and Taejoon Park²

¹ School of Electronics and Information Engineering, Korea Aerospace University, 76 Hanggongdaehang-ro, Goyang-si, Gyeonggi-do 412-791, Korea

² Department of Robotics Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan, Gyeonggi-do 15588, Korea

Sensors 2017, 17(6), 1334; https://doi.org/10.3390/s17061334 - 8 Jun 2017

Cited by 4 | Viewed by 4503

Abstract

With the emergence of smart and converged home services, the need for the secure and easy interplay of various devices has been increased. Push Button Configuration (PBC) is one of the technologies proposed for easy set-up of a secure session between IT and [...] Read more.

With the emergence of smart and converged home services, the need for the secure and easy interplay of various devices has been increased. Push Button Configuration (PBC) is one of the technologies proposed for easy set-up of a secure session between IT and consumer devices. Although the Wi-Fi Direct specification explicitly states that all devices must support the PBC method, its applicability is very limited. This is because the security vulnerability of PBC can be maliciously exploited so that attackers can make illegitimate sessions with consumer devices. To address this problem, this paper proposes a novel Security-enhanced PBC (SePBC) scheme with which we can uncover suspicious or malicious devices. The proposed mechanism has several unique features. First, we develop a secure handshake distance measurement protocol by preventing an adversary sitting outside the region from maliciously manipulating its distance to be fake. Second, it is compatible with the original Wi-Fi PBC without introducing a brand-new methodology. Finally, SePBC uses lightweight operations without CPU-intensive cryptography computation and employs inexpensive H/W. Moreover, it needs to incur little overhead when there is no attack. This paper also designs and implements the proposed SePBC in the real world. Our experimental results and analysis show that the proposed SePBC scheme effectively defeats attacks on PBC while minimizing the modification of the original PBC equipment. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

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14 pages, 5439 KiB

Open AccessArticle

Image Processing of Porous Silicon Microarray in Refractive Index Change Detection

by Zhiqing Guo¹, Zhenhong Jia^1,*, Jie Yang², Nikola Kasabov³ and Chuanxi Li⁴

¹ College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China

² Institute of Image Processing and Pattern Recognition, Shanghai Jiao Tong University, Shanghai 200240, China

³ Knowledge Engineering and Discovery Research Institute, Auckland University of Technology, Auckland 1020, New Zealand

⁴ School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China

Sensors 2017, 17(6), 1335; https://doi.org/10.3390/s17061335 - 8 Jun 2017

Cited by 8 | Viewed by 5001

Abstract

A new method for extracting the dots is proposed by the reflected light image of porous silicon (PSi) microarray utilization in this paper. The method consists of three parts: pretreatment, tilt correction and spot segmentation. First, based on the characteristics of different components [...] Read more.

A new method for extracting the dots is proposed by the reflected light image of porous silicon (PSi) microarray utilization in this paper. The method consists of three parts: pretreatment, tilt correction and spot segmentation. First, based on the characteristics of different components in HSV (Hue, Saturation, Value) space, a special pretreatment is proposed for the reflected light image to obtain the contour edges of the array cells in the image. Second, through the geometric relationship of the target object between the initial external rectangle and the minimum bounding rectangle (MBR), a new tilt correction algorithm based on the MBR is proposed to adjust the image. Third, based on the specific requirements of the reflected light image segmentation, the array cells are segmented into dots as large as possible and the distance between the dots is equal in the corrected image. Experimental results show that the pretreatment part of this method can effectively avoid the influence of complex background and complete the binarization processing of the image. The tilt correction algorithm has a shorter computation time, which makes it highly suitable for tilt correction of reflected light images. The segmentation algorithm makes the dots in a regular arrangement, excludes the edges and the bright spots. This method could be utilized in the fast, accurate and automatic dots extraction of the PSi microarray reflected light image. Full article

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

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17 pages, 7027 KiB

Open AccessArticle

3D Printing-Based Integrated Water Quality Sensing System

by Muinul Banna¹, Kaustav Bera², Ryan Sochol³, Liwei Lin⁴, Homayoun Najjaran¹, Rehan Sadiq¹ and Mina Hoorfar^1,*

¹ School of Engineering, University of British Columbia, Kelowna, BC V1V 1V7, Canada

² Indian Institute of Technology, Kharagpur, West Bengal 721302, India

³ Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA

⁴ Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA 94720, USA

Sensors 2017, 17(6), 1336; https://doi.org/10.3390/s17061336 - 8 Jun 2017

Cited by 32 | Viewed by 14770

Abstract

The online and accurate monitoring of drinking water supply networks is critically in demand to rapidly detect the accidental or deliberate contamination of drinking water. At present, miniaturized water quality monitoring sensors developed in the laboratories are usually tested under ambient pressure and [...] Read more.

The online and accurate monitoring of drinking water supply networks is critically in demand to rapidly detect the accidental or deliberate contamination of drinking water. At present, miniaturized water quality monitoring sensors developed in the laboratories are usually tested under ambient pressure and steady-state flow conditions; however, in Water Distribution Systems (WDS), both the pressure and the flowrate fluctuate. In this paper, an interface is designed and fabricated using additive manufacturing or 3D printing technology—material extrusion (Trade Name: fused deposition modeling, FDM) and material jetting—to provide a conduit for miniaturized sensors for continuous online water quality monitoring. The interface is designed to meet two main criteria: low pressure at the inlet of the sensors and a low flowrate to minimize the water bled (i.e., leakage), despite varying pressure from WDS. To meet the above criteria, a two-dimensional computational fluid dynamics model was used to optimize the geometry of the channel. The 3D printed interface, with the embedded miniaturized pH and conductivity sensors, was then tested at different temperatures and flowrates. The results show that the response of the pH sensor is independent of the flowrate and temperature. As for the conductivity sensor, the flowrate and temperature affect only the readings at a very low conductivity (4 µS/cm) and high flowrates (30 mL/min), and a very high conductivity (460 µS/cm), respectively. Full article

(This article belongs to the Special Issue 3D Printed Sensors)

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14 pages, 2895 KiB

Open AccessArticle

Development of a Flexible Strain Sensor Based on PEDOT:PSS for Thin Film Structures

by Alexandra El Zein^1,2, Camille Huppé^1,2 and Cédric Cochrane^1,2,*

¹ ENSAIT, GEMTEX, F-59100 Roubaix, France

² University Lille Nord de France, F-59000 Lille, France

Sensors 2017, 17(6), 1337; https://doi.org/10.3390/s17061337 - 9 Jun 2017

Cited by 38 | Viewed by 7394

Abstract

The aim of this study was to develop and optimize a reproducible flexible sensor adapted to thin low-density polyethylene (LDPE) films and/or structures to enable their deformation measurements. As these deformations are suspected to be weak (less than 10%), the developed sensor needs [...] Read more.

The aim of this study was to develop and optimize a reproducible flexible sensor adapted to thin low-density polyethylene (LDPE) films and/or structures to enable their deformation measurements. As these deformations are suspected to be weak (less than 10%), the developed sensor needs to be particularly sensitive. Moreover, it is of prime importance that sensor integration and usability do not modify the mechanical behavior of its LDPE substrate. The literature review allowed several materials to be investigated and an elastomer/intrinsically conductive polymer PEDOT:PSS (Clevios^TM) filled composite was selected to simultaneously combine mechanical properties and electrical conductivity. This composite (made of PEDOT:PSS and silicone Bluesil^®) presented satisfying compatibilities with piezoresistive effects, negative temperature performances (in a range from −60 °C to 20 °C), as well as elongation properties (until the elastic limit of the substrate was reached). The method used for creating the sensor is fully described, as are the optimization of the sensor manufacture in terms of used materials, the used amount of materials where the percolation theory aspects must be considered, the adhesion to the substrate, and the manufacturing protocol. Electromechanical characterization was performed to assess the gauge factor (K) of the sensor on its substrate. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 7832 KiB

Open AccessArticle

A Weekly Indicator of Surface Moisture Status from Satellite Data for Operational Monitoring of Crop Conditions

by Francesco Nutini^1,*, Daniela Stroppiana¹, Lorenzo Busetto¹

, Dario Bellingeri², Chiara Corbari³, Marco Mancini³, Enrico Zini², Pietro Alessandro Brivio¹

and Mirco Boschetti¹

¹ Institute for Electromagnetic Sensing of the Environment, Italian National Research Council, Via Bassini 15, Milano 20133, Italy

² ARPA Lombardia, Lombardy Environmental Protection Agency, Via Ippolito Rosellini 17, Milano 20124, Italy

³ Politecnico di Milano, Department of Civil and Environmental Engineering, Piazza Leonardo da Vinci 32, Milano 20133, Italy

Sensors 2017, 17(6), 1338; https://doi.org/10.3390/s17061338 - 9 Jun 2017

Cited by 5 | Viewed by 5091

Abstract

The triangle method has been applied to derive a weekly indicator of evaporative fraction on vegetated areas in a temperate region in Northern Italy. Daily MODIS Aqua Land Surface Temperature (MYD11A1) data has been combined with air temperature maps and 8-day composite MODIS [...] Read more.

The triangle method has been applied to derive a weekly indicator of evaporative fraction on vegetated areas in a temperate region in Northern Italy. Daily MODIS Aqua Land Surface Temperature (MYD11A1) data has been combined with air temperature maps and 8-day composite MODIS NDVI (MOD13Q1/MYD13Q1) data to estimate the Evaporative Fraction (EF) at 1 km resolution, on a daily basis. Measurements at two eddy covariance towers located within the study area have been exploited to assess the reliability of satellite based EF estimations as well as the robustness of input data. Weekly syntheses of the daily EF indicator (EF_w) were then derived at regional scale for the years 2010, 2011 and 2012 as a proxy of overall surface moisture condition. EF_w showed a temporal behavior consistent with growing cycles and agro-practices of the main crops cultivated in the study area (rice, forages and corn). Comparison with official regional corn yield data showed that variations in EF_w cumulated over summer are related with crop production shortages induced by water scarcity. These results suggest that weekly-averaged EF estimated from MODIS data is sensible to water stress conditions and can be used as an indicator of crops’ moisture conditions at agronomical district level. Advantages and disadvantages of the proposed approach to provide information useful to issue operational near real time bulletins on crop conditions at regional scale are discussed. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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18 pages, 1325 KiB

Open AccessArticle

A Smartphone Indoor Localization Algorithm Based on WLAN Location Fingerprinting with Feature Extraction and Clustering

by Junhai Luo^*

and Liang Fu

School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 610073, China

Sensors 2017, 17(6), 1339; https://doi.org/10.3390/s17061339 - 9 Jun 2017

Cited by 57 | Viewed by 5564

Abstract

With the development of communication technology, the demand for location-based services is growing rapidly. This paper presents an algorithm for indoor localization based on Received Signal Strength (RSS), which is collected from Access Points (APs). The proposed localization algorithm contains the offline information [...] Read more.

With the development of communication technology, the demand for location-based services is growing rapidly. This paper presents an algorithm for indoor localization based on Received Signal Strength (RSS), which is collected from Access Points (APs). The proposed localization algorithm contains the offline information acquisition phase and online positioning phase. Firstly, the AP selection algorithm is reviewed and improved based on the stability of signals to remove useless AP; secondly, Kernel Principal Component Analysis (KPCA) is analyzed and used to remove the data redundancy and maintain useful characteristics for nonlinear feature extraction; thirdly, the Affinity Propagation Clustering (APC) algorithm utilizes RSS values to classify data samples and narrow the positioning range. In the online positioning phase, the classified data will be matched with the testing data to determine the position area, and the Maximum Likelihood (ML) estimate will be employed for precise positioning. Eventually, the proposed algorithm is implemented in a real-world environment for performance evaluation. Experimental results demonstrate that the proposed algorithm improves the accuracy and computational complexity. Full article

(This article belongs to the Special Issue Smartphone-based Pedestrian Localization and Navigation)

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10 pages, 1213 KiB

Open AccessArticle

Doppler Navigation System with a Non-Stabilized Antenna as a Sea-Surface Wind Sensor

by Alexey Nekrasov^1,2,3,*

, Alena Khachaturian¹

, Vladimir Veremyev¹ and Mikhail Bogachev¹

¹ Department of Radio Engineering Systems, Saint Petersburg Electrotechnical University, Professora Popova 5, Saint Petersburg 197376, Russia

² Institute for Computer Technologies and Information Security, Southern Federal University, Chekhova 2, Taganrog 347922, Russia

³ Faculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, Košice 04200, Slovakia

Sensors 2017, 17(6), 1340; https://doi.org/10.3390/s17061340 - 9 Jun 2017

Cited by 12 | Viewed by 5863

Abstract

We propose a concept of the utilization of an aircraft Doppler Navigation System (DNS) as a sea-surface wind sensor complementary to its normal functionality. The DNS with an antenna, which is non-stabilized physically to the local horizontal with x-configured beams, is considered. [...] Read more.

We propose a concept of the utilization of an aircraft Doppler Navigation System (DNS) as a sea-surface wind sensor complementary to its normal functionality. The DNS with an antenna, which is non-stabilized physically to the local horizontal with x-configured beams, is considered. We consider the wind measurements by the DNS configured in the multi-beam scatterometer mode for a rectilinear flight scenario. The system feasibility and the efficiency of the proposed wind algorithm retrieval are supported by computer simulations. Finally, the associated limitations of the proposed approach are considered. Full article

(This article belongs to the Special Issue Marine Sensing)

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18 pages, 3711 KiB

Open AccessArticle

Convolutional Neural Network-Based Robot Navigation Using Uncalibrated Spherical Images

by Lingyan Ran¹

, Yanning Zhang^1,*, Qilin Zhang² and Tao Yang¹

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(6), 1341; https://doi.org/10.3390/s17061341 - 12 Jun 2017

Cited by 85 | Viewed by 12055

Abstract

Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer [...] Read more.

Vision-based mobile robot navigation is a vibrant area of research with numerous algorithms having been developed, the vast majority of which either belong to the scene-oriented simultaneous localization and mapping (SLAM) or fall into the category of robot-oriented lane-detection/trajectory tracking. These methods suffer from high computational cost and require stringent labelling and calibration efforts. To address these challenges, this paper proposes a lightweight robot navigation framework based purely on uncalibrated spherical images. To simplify the orientation estimation, path prediction and improve computational efficiency, the navigation problem is decomposed into a series of classification tasks. To mitigate the adverse effects of insufficient negative samples in the “navigation via classification” task, we introduce the spherical camera for scene capturing, which enables 360° fisheye panorama as training samples and generation of sufficient positive and negative heading directions. The classification is implemented as an end-to-end Convolutional Neural Network (CNN), trained on our proposed Spherical-Navi image dataset, whose category labels can be efficiently collected. This CNN is capable of predicting potential path directions with high confidence levels based on a single, uncalibrated spherical image. Experimental results demonstrate that the proposed framework outperforms competing ones in realistic applications. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 2354 KiB

Open AccessArticle

Recognizing Bedside Events Using Thermal and Ultrasonic Readings

by Danielsen Asbjørn^1,*

and Torresen Jim²

¹ UiT—The Arctic University of Norway, 8505 Narvik, Norway

² UiO—University of Oslo, 0373 Oslo, Norway

Sensors 2017, 17(6), 1342; https://doi.org/10.3390/s17061342 - 9 Jun 2017

Cited by 15 | Viewed by 5311

Abstract

Falls in homes of the elderly, in residential care facilities and in hospitals commonly occur in close proximity to the bed. Most approaches for recognizing falls use cameras, which challenge privacy, or sensor devices attached to the bed or the body to recognize [...] Read more.

Falls in homes of the elderly, in residential care facilities and in hospitals commonly occur in close proximity to the bed. Most approaches for recognizing falls use cameras, which challenge privacy, or sensor devices attached to the bed or the body to recognize bedside events and bedside falls. We use data collected from a ceiling mounted 80 × 60 thermal array combined with an ultrasonic sensor device. This approach makes it possible to monitor activity while preserving privacy in a non-intrusive manner. We evaluate three different approaches towards recognizing location and posture of an individual. Bedside events are recognized using a 10-second floating image rule/filter-based approach, recognizing bedside falls with 98.62% accuracy. Bed-entry and exit events are recognized with 98.66% and 96.73% accuracy, respectively. Full article

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

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16 pages, 1191 KiB

Open AccessArticle

Improved Scheduling Mechanisms for Synchronous Information and Energy Transmission

by Danyang Qin^*, Songxiang Yang, Yan Zhang, Jingya Ma and Qun Ding

Key Laboratory of Electronics Engineering, College of Heilongjiang University, Harbin 150080, China

Sensors 2017, 17(6), 1343; https://doi.org/10.3390/s17061343 - 9 Jun 2017

Cited by 1 | Viewed by 3942

Abstract

Wireless energy collecting technology can effectively reduce the network time overhead and prolong the wireless sensor network (WSN) lifetime. However, the traditional energy collecting technology cannot achieve the balance between ergodic channel capacity and average collected energy. In order to solve the problem [...] Read more.

Wireless energy collecting technology can effectively reduce the network time overhead and prolong the wireless sensor network (WSN) lifetime. However, the traditional energy collecting technology cannot achieve the balance between ergodic channel capacity and average collected energy. In order to solve the problem of the network transmission efficiency and the limited energy of wireless devices, three improved scheduling mechanisms are proposed: improved signal noise ratio (SNR) scheduling mechanism (IS2M), improved N-SNR scheduling mechanism (INS2M) and an improved Equal Throughput scheduling mechanism (IETSM) for different channel conditions to improve the whole network performance. Meanwhile, the average collected energy of single users and the ergodic channel capacity of three scheduling mechanisms can be obtained through the order statistical theory in Rayleig, Ricean, Nakagami-m and Weibull fading channels. It is concluded that the proposed scheduling mechanisms can achieve better balance between energy collection and data transmission, so as to provide a new solution to realize synchronous information and energy transmission for WSNs. 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, 2600 KiB

Open AccessArticle

Feed-Forward Neural Network Prediction of the Mechanical Properties of Sandcrete Materials

by Panagiotis G. Asteris^1,*, Panayiotis C. Roussis² and Maria G. Douvika¹

¹ Computational Mechanics Laboratory, School of Pedagogical and Technological Education, Heraklion, GR, 14121 Athens, Greece

² Department of Civil and Environmental Engineering, University of Cyprus, 1678 Nicosia, Cyprus

Sensors 2017, 17(6), 1344; https://doi.org/10.3390/s17061344 - 9 Jun 2017

Cited by 178 | Viewed by 9244

Abstract

This work presents a soft-sensor approach for estimating critical mechanical properties of sandcrete materials. Feed-forward (FF) artificial neural network (ANN) models are employed for building soft-sensors able to predict the 28-day compressive strength and the modulus of elasticity of sandcrete materials. To this [...] Read more.

This work presents a soft-sensor approach for estimating critical mechanical properties of sandcrete materials. Feed-forward (FF) artificial neural network (ANN) models are employed for building soft-sensors able to predict the 28-day compressive strength and the modulus of elasticity of sandcrete materials. To this end, a new normalization technique for the pre-processing of data is proposed. The comparison of the derived results with the available experimental data demonstrates the capability of FF ANNs to predict with pinpoint accuracy the mechanical properties of sandcrete materials. Furthermore, the proposed normalization technique has been proven effective and robust compared to other normalization techniques available in the literature. Full article

(This article belongs to the Special Issue Soft Sensors and Intelligent Algorithms for Data Fusion)

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19 pages, 2577 KiB

Open AccessArticle

A Noise Removal Method for Uniform Circular Arrays in Complex Underwater Noise Environments with Low SNR

by Huijun Xia^1,2

, Kunde Yang^1,2,*, Yuanliang Ma^1,2, Yong Wang³ and Yaxiong Liu^1,2

¹ School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

² Key Laboratory of Ocean Acoustics and Sensing, Ministry of Industry and Information Technology, Xi’an 710072, China

³ School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710072, China

Sensors 2017, 17(6), 1345; https://doi.org/10.3390/s17061345 - 9 Jun 2017

Cited by 2 | Viewed by 4330

Abstract

Generally, many beamforming methods are derived under the assumption of white noise. In practice, the actual underwater ambient noise is complex. As a result, the noise removal capacity of the beamforming method may be deteriorated considerably. Furthermore, in underwater environment with extremely low [...] Read more.

Generally, many beamforming methods are derived under the assumption of white noise. In practice, the actual underwater ambient noise is complex. As a result, the noise removal capacity of the beamforming method may be deteriorated considerably. Furthermore, in underwater environment with extremely low signal-to-noise ratio (SNR), the performances of the beamforming method may be deteriorated. To tackle these problems, a noise removal method for uniform circular array (UCA) is proposed to remove the received noise and improve the SNR in complex noise environments with low SNR. First, the symmetrical noise sources are defined and the spatial correlation of the symmetrical noise sources is calculated. Then, based on the preceding results, the noise covariance matrix is decomposed into symmetrical and asymmetrical components. Analysis indicates that the symmetrical component only affect the real part of the noise covariance matrix. Consequently, the delay-and-sum (DAS) beamforming is performed by using the imaginary part of the covariance matrix to remove the symmetrical component. However, the noise removal method causes two problems. First, the proposed method produces a false target. Second, the proposed method would seriously suppress the signal when it is located in some directions. To solve the first problem, two methods to reconstruct the signal covariance matrix are presented: based on the estimation of signal variance and based on the constrained optimization algorithm. To solve the second problem, we can design the array configuration and select the suitable working frequency. Theoretical analysis and experimental results are included to demonstrate that the proposed methods are particularly effective in complex noise environments with low SNR. The proposed method can be extended to any array. Full article

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

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24 pages, 4276 KiB

Open AccessArticle

Toward a Trust Evaluation Mechanism in the Social Internet of Things

by Nguyen Binh Truong¹, Hyunwoo Lee², Bob Askwith¹ and Gyu Myoung Lee^1,*

¹ Department of Computer Science, Liverpool John Moores University, Liverpool L3 3AF, UK

² Media Research Division, Broadcasting & Media Research Laboratory, Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea

Sensors 2017, 17(6), 1346; https://doi.org/10.3390/s17061346 - 9 Jun 2017

Cited by 107 | Viewed by 9908

Abstract

In the blooming era of the Internet of Things (IoT), trust has been accepted as a vital factor for provisioning secure, reliable, seamless communications and services. However, a large number of challenges still remain unsolved due to the ambiguity of the concept of [...] Read more.

In the blooming era of the Internet of Things (IoT), trust has been accepted as a vital factor for provisioning secure, reliable, seamless communications and services. However, a large number of challenges still remain unsolved due to the ambiguity of the concept of trust as well as the variety of divergent trust models in different contexts. In this research, we augment the trust concept, the trust definition and provide a general conceptual model in the context of the Social IoT (SIoT) environment by breaking down all attributes influencing trust. Then, we propose a trust evaluation model called REK, comprised of the triad of trust indicators (TIs) Reputation, Experience and Knowledge. The REK model covers multi-dimensional aspects of trust by incorporating heterogeneous information from direct observation (as Knowledge TI), personal experiences (as Experience TI) to global opinions (as Reputation TI). The associated evaluation models for the three TIs are also proposed and provisioned. We then come up with an aggregation mechanism for deriving trust values as the final outcome of the REK evaluation model. We believe this article offers better understandings on trust as well as provides several prospective approaches for the trust evaluation in the SIoT environment. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 1387 KiB

Open AccessArticle

Development and Positioning Accuracy Assessment of Single-Frequency Precise Point Positioning Algorithms by Combining GPS Code-Pseudorange Measurements with Real-Time SSR Corrections

by Miso Kim¹ and Kwan-Dong Park^2,*

¹ PPSoln Inc., 606 Seobusaet-gil #A-2409, Seoul 08504, Korea

² WCSL (World Class Smart Lab) of intelligent vehicle Inha research Lab, Department of Geoinformatic Engineering, Inha University, 100 Inha-ro, Incheon 22212, Korea

Sensors 2017, 17(6), 1347; https://doi.org/10.3390/s17061347 - 9 Jun 2017

Cited by 10 | Viewed by 4510

Abstract

We have developed a suite of real-time precise point positioning programs to process GPS pseudorange observables, and validated their performance through static and kinematic positioning tests. To correct inaccurate broadcast orbits and clocks, and account for signal delays occurring from the ionosphere and [...] Read more.

We have developed a suite of real-time precise point positioning programs to process GPS pseudorange observables, and validated their performance through static and kinematic positioning tests. To correct inaccurate broadcast orbits and clocks, and account for signal delays occurring from the ionosphere and troposphere, we applied State Space Representation (SSR) error corrections provided by the Seoul Broadcasting System (SBS) in South Korea. Site displacements due to solid earth tide loading are also considered for the purpose of improving the positioning accuracy, particularly in the height direction. When the developed algorithm was tested under static positioning, Kalman-filtered solutions produced a root-mean-square error (RMSE) of 0.32 and 0.40 m in the horizontal and vertical directions, respectively. For the moving platform, the RMSE was found to be 0.53 and 0.69 m in the horizontal and vertical directions. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 2019 KiB

Open AccessArticle

Rapid Waterborne Pathogen Detection with Mobile Electronics

by Tsung-Feng Wu^1,*, Yu-Chen Chen¹, Wei-Chung Wang¹, Ashwini S. Kucknoor², Che-Jen Lin²

, Yu-Hwa Lo³

, Chun-Wei Yao² and Ian Lian^2,*

¹ VOR, Inc., San Diego 92122, CA, USA

² Center for Advances in Water & Air Quality, Lamar University, Beaumont, TX 77710, USA

³ Department of Electrical and Computer Engineering, University of California at San Diego, San Diego, CA 92093, USA

Sensors 2017, 17(6), 1348; https://doi.org/10.3390/s17061348 - 9 Jun 2017

Cited by 12 | Viewed by 6892

Abstract

Pathogen detection in water samples, without complex and time consuming procedures such as fluorescent-labeling or culture-based incubation, is essential to public safety. We propose an immunoagglutination-based protocol together with the microfluidic device to quantify pathogen levels directly from water samples. Utilizing ubiquitous complementary [...] Read more.

Pathogen detection in water samples, without complex and time consuming procedures such as fluorescent-labeling or culture-based incubation, is essential to public safety. We propose an immunoagglutination-based protocol together with the microfluidic device to quantify pathogen levels directly from water samples. Utilizing ubiquitous complementary metal–oxide–semiconductor (CMOS) imagers from mobile electronics, a low-cost and one-step reaction detection protocol is developed to enable field detection for waterborne pathogens. 10 mL of pathogen-containing water samples was processed using the developed protocol including filtration enrichment, immune-reaction detection and imaging processing. The limit of detection of 10 E. coli O157:H7 cells/10 mL has been demonstrated within 10 min of turnaround time. The protocol can readily be integrated into a mobile electronics such as smartphones for rapid and reproducible field detection of waterborne pathogens. Full article

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

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17 pages, 2781 KiB

Open AccessArticle

Design and Validation of a Breathing Detection System for Scuba Divers

by Corentin Altepe^1,2,*,†, S. Murat Egi^3,4,†, Tamer Ozyigit^3,†, D. Ruzgar Sinoplu^1,†, Alessandro Marroni^4,† and Paola Pierleoni^2,†

¹ Bogazici Underwater Research Center, Yavuzturk Sk. 32/1 Altiyol, 34716 Istanbul, Turkey

² Information Engineering Department, Marche Polytechnic University, Via Brecce Bianche 12, 60131 Ancona, Italy

³ Computer Engineering Department, Galatasaray University, Ciragan Cad. 36 Ortakoy, 34349 Istanbul, Turkey

⁴ DAN Europe Research Division, Contada Padune 11, 64026 Roseto degli Abruzzi, Italy

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1349; https://doi.org/10.3390/s17061349 - 9 Jun 2017

Cited by 14 | Viewed by 7709

Abstract

Drowning is the major cause of death in self-contained underwater breathing apparatus (SCUBA) diving. This study proposes an embedded system with a live and light-weight algorithm which detects the breathing of divers through the analysis of the intermediate pressure (IP) signal of the [...] Read more.

Drowning is the major cause of death in self-contained underwater breathing apparatus (SCUBA) diving. This study proposes an embedded system with a live and light-weight algorithm which detects the breathing of divers through the analysis of the intermediate pressure (IP) signal of the SCUBA regulator. A system composed mainly of two pressure sensors and a low-power microcontroller was designed and programmed to record the pressure sensors signals and provide alarms in absence of breathing. An algorithm was developed to analyze the signals and identify inhalation events of the diver. A waterproof case was built to accommodate the system and was tested up to a depth of 25 m in a pressure chamber. To validate the system in the real environment, a series of dives with two different types of workload requiring different ranges of breathing frequencies were planned. Eight professional SCUBA divers volunteered to dive with the system to collect their IP data in order to participate to validation trials. The subjects underwent two dives, each of 52 min on average and a maximum depth of 7 m. The algorithm was optimized for the collected dataset and proved a sensitivity of inhalation detection of 97.5% and a total number of 275 false positives (FP) over a total recording time of 13.9 h. The detection algorithm presents a maximum delay of 5.2 s and requires only 800 bytes of random-access memory (RAM). The results were compared against the analysis of video records of the dives by two blinded observers and proved a sensitivity of 97.6% on the data set. The design includes a buzzer to provide audible alarms to accompanying dive buddies which will be triggered in case of degraded health conditions such as near drowning (absence of breathing), hyperventilation (breathing frequency too high) and skip-breathing (breathing frequency too low) measured by the improper breathing frequency. The system also measures the IP at rest before the dive and indicates with flashing light-emitting diodes and audible alarm the regulator malfunctions due to high or low IP that may cause fatal accidents during the dive by preventing natural breathing. It is also planned to relay the alarm signal to underwater and surface rescue authorities by means of acoustic communication. Full article

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

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18 pages, 6996 KiB

Open AccessArticle

Prediction of Driver’s Intention of Lane Change by Augmenting Sensor Information Using Machine Learning Techniques

by Il-Hwan Kim¹, Jae-Hwan Bong², Jooyoung Park^3,* and Shinsuk Park^2,*

¹ Hyundai Motor Company, Hwaseong-si 18280, Korea

² Department of Mechanical Engineering, Korea University, Seoul 02841, Korea

³ Department of Control and Instrumentation Engineering, Korea University, Sejong 30019, Korea

Sensors 2017, 17(6), 1350; https://doi.org/10.3390/s17061350 - 10 Jun 2017

Cited by 109 | Viewed by 11078

Abstract

Driver assistance systems have become a major safety feature of modern passenger vehicles. The advanced driver assistance system (ADAS) is one of the active safety systems to improve the vehicle control performance and, thus, the safety of the driver and the passengers. To [...] Read more.

Driver assistance systems have become a major safety feature of modern passenger vehicles. The advanced driver assistance system (ADAS) is one of the active safety systems to improve the vehicle control performance and, thus, the safety of the driver and the passengers. To use the ADAS for lane change control, rapid and correct detection of the driver’s intention is essential. This study proposes a novel preprocessing algorithm for the ADAS to improve the accuracy in classifying the driver’s intention for lane change by augmenting basic measurements from conventional on-board sensors. The information on the vehicle states and the road surface condition is augmented by using an artificial neural network (ANN) models, and the augmented information is fed to a support vector machine (SVM) to detect the driver’s intention with high accuracy. The feasibility of the developed algorithm was tested through driving simulator experiments. The results show that the classification accuracy for the driver’s intention can be improved by providing an SVM model with sufficient driving information augmented by using ANN models of vehicle dynamics. Full article

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

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13 pages, 6043 KiB

Open AccessArticle

Acoustic Emission and Echo Signal Compensation Techniques Applied to an Ultrasonic Logging-While-Drilling Caliper

by Yongchao Yao^*

, Xiaodong Ju, Junqiang Lu and Baiyong Men

State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China

Sensors 2017, 17(6), 1351; https://doi.org/10.3390/s17061351 - 10 Jun 2017

Cited by 17 | Viewed by 8204

Abstract

A logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range [...] Read more.

A logging-while-drilling (LWD) caliper is a tool used for the real-time measurement of a borehole diameter in oil drilling engineering. This study introduces the mechanical structure and working principle of a new LWD caliper based on ultrasonic distance measurement (UDM). The detection range is a major performance index of a UDM system. This index is determined by the blind zone length and remote reflecting interface detection capability of the system. To reduce the blind zone length and detect near the reflecting interface, a full bridge acoustic emission technique based on bootstrap gate driver (BGD) and metal-oxide-semiconductor field effect transistor (MOSFET) is designed by analyzing the working principle and impedance characteristics of a given piezoelectric transducer. To detect the remote reflecting interface and reduce the dynamic range of the received echo signals, the relationships between the echo amplitude and propagation distance of ultrasonic waves are determined. A signal compensation technique based on time-varying amplification theory, which can automatically change the gain according to the echo arrival time is designed. Lastly, the aforementioned techniques and corresponding circuits are experimentally verified. Results show that the blind zone length in the UDM system of the LWD caliper is significantly reduced and the capability to detect the remote reflecting interface is considerably improved. Full article

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

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21 pages, 783 KiB

Open AccessArticle

Optimization of Perovskite Gas Sensor Performance: Characterization, Measurement and Experimental Design

by Francesco Bertocci^1,*

, Ada Fort¹

, Valerio Vignoli¹

, Marco Mugnaini¹

and Rossella Berni²

¹ Department of Information Engineering and Mathematics, University of Siena, Via Roma 56, 53100 Siena, Italy

² Department of Statistics, Computer Science, Applications “G. Parenti”, University of Florence, Viale Morgagni 59, 50134 Florence, Italy

Sensors 2017, 17(6), 1352; https://doi.org/10.3390/s17061352 - 10 Jun 2017

Cited by 12 | Viewed by 8125

Abstract

Eight different types of nanostructured perovskites based on YCoO

_{3}

with different chemical compositions are prepared as gas sensor materials, and they are studied with two target gases NO

_{2}

and CO. Moreover, a statistical approach is adopted to optimize their performance. The [...] Read more.

Eight different types of nanostructured perovskites based on YCoO

_{3}

with different chemical compositions are prepared as gas sensor materials, and they are studied with two target gases NO

_{2}

and CO. Moreover, a statistical approach is adopted to optimize their performance. The innovative contribution is carried out through a split-plot design planning and modeling, also involving random effects, for studying Metal Oxide Semiconductors (MOX) sensors in a robust design context. The statistical results prove the validity of the proposed approach; in fact, for each material type, the variation of the electrical resistance achieves a satisfactory optimized value conditional to the working temperature and by controlling for the gas concentration variability. Just to mention some results, the sensing material YCo

_{0.9}

Pd

_{0.1}

O

_{3}

(Mt1) achieved excellent solutions during the optimization procedure. In particular, Mt1 resulted in being useful and feasible for the detection of both gases, with optimal response equal to +10.23% and working temperature at

312^{\circ}

C for CO (284 ppm, from design) and response equal to −14.17% at

185^{\circ}

C for NO

_{2}

(16 ppm, from design). Analogously, for NO

_{2}

(16 ppm, from design), the material type YCo

_{0.9}

O

_{2.85} + 1 %

Pd (Mt8) allows for optimizing the response value at

- 15.39 %

with a working temperature at

181.0^{\circ}

C, whereas for YCo

_{0.95}

Pd

_{0.05}

O

_{3}

(Mt3), the best response value is achieved at

- 15.40 %

with the temperature equal to

204^{\circ}

C. Full article

(This article belongs to the Collection Gas Sensors)

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16 pages, 5813 KiB

Open AccessArticle

A Sparse Bayesian Approach for Forward-Looking Superresolution Radar Imaging

by Yin Zhang^*, Yongchao Zhang

, Yulin Huang and Jianyu Yang

University of Electronic Science and Technology of China, Chengdu 610051

Sensors 2017, 17(6), 1353; https://doi.org/10.3390/s17061353 - 10 Jun 2017

Cited by 27 | Viewed by 4784

Abstract

This paper presents a sparse superresolution approach for high cross-range resolution imaging of forward-looking scanning radar based on the Bayesian criterion. First, a novel forward-looking signal model is established as the product of the measurement matrix and the cross-range target distribution, which is [...] Read more.

This paper presents a sparse superresolution approach for high cross-range resolution imaging of forward-looking scanning radar based on the Bayesian criterion. First, a novel forward-looking signal model is established as the product of the measurement matrix and the cross-range target distribution, which is more accurate than the conventional convolution model. Then, based on the Bayesian criterion, the widely-used sparse regularization is considered as the penalty term to recover the target distribution. The derivation of the cost function is described, and finally, an iterative expression for minimizing this function is presented. Alternatively, this paper discusses how to estimate the single parameter of Gaussian noise. With the advantage of a more accurate model, the proposed sparse Bayesian approach enjoys a lower model error. Meanwhile, when compared with the conventional superresolution methods, the proposed approach shows high cross-range resolution and small location error. The superresolution results for the simulated point target, scene data, and real measured data are presented to demonstrate the superior performance of the proposed approach. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 2733 KiB

Open AccessArticle

Development and Validation of a New Near-Infrared Sensor to Measure Polyethylene Glycol (PEG) Concentration in Water

by Olivier Buzzi^1,*, Shengyang Yuan¹

and Benjamin Routley²

¹ Priority Research Centre for Geotechnical and Materials Modelling, University of Newcastle, Callaghan NSW 2308, Australia

² School of Electrical Engineering and Computer Science, University of Newcastle, Callaghan NSW 2308, Australia

Sensors 2017, 17(6), 1354; https://doi.org/10.3390/s17061354 - 10 Jun 2017

Cited by 7 | Viewed by 5583

Abstract

A near-infrared absorption based laser sensor has been designed and validated for the real-time measurement of polyethylene glycol (PEG) concentration. The wavelength was selected after the determination of the absorption spectrum of deionised water and PEG solutions using a Varian Cary 6000i spectrophotometer, [...] Read more.

A near-infrared absorption based laser sensor has been designed and validated for the real-time measurement of polyethylene glycol (PEG) concentration. The wavelength was selected after the determination of the absorption spectrum of deionised water and PEG solutions using a Varian Cary 6000i spectrophotometer, in order to limit the influence of PEG molecular mass on the absorption measurement. With this new sensor, the water is treated as the attenuating species and the addition of PEG in water reduces the absorbance of the medium. The concept was validated using three different PEG types (PEG 6,000, 20,000, and 35,000) and it was found that the results follow Beer Lambert’s law. The influence of temperature was assessed by testing the PEG 20,000 at four different temperatures that could be encountered in a laboratory environment. The data show a slight temperature influence (increase of absorbance by 8% when the temperature rises from about 20 to about 29 degrees). Following the validation phase conducted ex situ, a prototype of an immersible sensor was built and calibrated for in situ measurements. Full article

(This article belongs to the Section Chemical Sensors)

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16 pages, 6129 KiB

Open AccessArticle

Aspheric Surface Measurement Using Capacitive Sensors

by Daocheng Yuan^1,2, Huiying Zhao^1,*, Xin Tao², Shaobo Li², Xueliang Zhu¹ and Chupeng Zhang¹

¹ State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² Institute of Machinery Manufacturing Technology, China Academy of Engineering Physics, Mianyang 621000, China

Sensors 2017, 17(6), 1355; https://doi.org/10.3390/s17061355 - 11 Jun 2017

Cited by 6 | Viewed by 5248

Abstract

This paper proposes a new method for the measurement of spherical coordinates by using capacitive sensors as a non-contact probe solution of measurement of aspheric surfaces. The measurement of the average effect of the capacitive probe and the influence of capacitive probe tilting [...] Read more.

This paper proposes a new method for the measurement of spherical coordinates by using capacitive sensors as a non-contact probe solution of measurement of aspheric surfaces. The measurement of the average effect of the capacitive probe and the influence of capacitive probe tilting were studied with respect to an eccentric spherical surface. Based on the tested characteristic curve of the average effect of the sphere and probe, it was found that nonlinear and linear compensation resulted in high measurement accuracy. The capacitance probe was found to be trying to fulfill a need for performing nm-level precision measurement of aspheric electromagnetic surfaces. Full article

(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)

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16 pages, 3090 KiB

Open AccessReview

Review on the Traction System Sensor Technology of a Rail Transit Train

by Jianghua Feng^*, Junfeng Xu, Wu Liao

and Yong Liu

Research Institute of Electrical Technology & Material Engineering, CRRC Zhuzhou Institute Company, Ltd., Zhuzhou 412001, China

Sensors 2017, 17(6), 1356; https://doi.org/10.3390/s17061356 - 11 Jun 2017

Cited by 42 | Viewed by 14522

Abstract

The development of high-speed intelligent rail transit has increased the number of sensors applied on trains. These play an important role in train state control and monitoring. These sensors generally work in a severe environment, so the key problem for sensor data acquisition [...] Read more.

The development of high-speed intelligent rail transit has increased the number of sensors applied on trains. These play an important role in train state control and monitoring. These sensors generally work in a severe environment, so the key problem for sensor data acquisition is to ensure data accuracy and reliability. In this paper, we follow the sequence of sensor signal flow, present sensor signal sensing technology, sensor data acquisition, and processing technology, as well as sensor fault diagnosis technology based on the voltage, current, speed, and temperature sensors which are commonly used in train traction systems. Finally, intelligent sensors and future research directions of rail transit train sensors are discussed. Full article

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

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21 pages, 5296 KiB

Open AccessArticle

‘HighChest’: An Augmented Freezer Designed for Smart Food Management and Promotion of Eco-Efficient Behaviour

by Manuele Bonaccorsi¹, Stefano Betti¹, Giovanni Rateni¹, Dario Esposito¹, Alessia Brischetto², Marco Marseglia³, Paolo Dario¹ and Filippo Cavallo^1,*

¹ The BioRobotics Institute, Scuola Superiore Sant’Anna, Viale Rinaldo Piaggio 34, Pontedera 56025, Italy

² Laboratory of Ergonomy & Design, Department of Architecture, University of Florence, Via Sandro Pertini 93, Calenzano 50041, Italy

³ Laboratory of Design for Sustainability, Department of Architecture, University of Florence, Via Sandro Pertini 93, Calenzano 50041, Italy

Sensors 2017, 17(6), 1357; https://doi.org/10.3390/s17061357 - 11 Jun 2017

Cited by 21 | Viewed by 7589

Abstract

This paper introduces HighChest, an innovative smart freezer designed to promote energy efficient behavior and the responsible use of food. Introducing a novel human–machine interface (HMI) design developed through assessment phases and a user involvement stage, HighChest is state of the art, featuring [...] Read more.

This paper introduces HighChest, an innovative smart freezer designed to promote energy efficient behavior and the responsible use of food. Introducing a novel human–machine interface (HMI) design developed through assessment phases and a user involvement stage, HighChest is state of the art, featuring smart services that exploit embedded sensors and Internet of things functionalities, which enhance the local capabilities of the appliance. The industrial design thinking approach followed for the advanced HMI is intended to maximize the social impact of the food management service, enhancing both the user experience of the product and the user’s willingness to adopt eco- and energy-friendly behaviors. The sensor equipment realizes automatic recognition of food by learning from the users, as well as automatic localization inside the deposit space. Moreover, it provides monitoring of the appliance’s usage, avoiding temperature and humidity issues related to improper use. Experimental tests were conducted to evaluate the localization system, and the results showed 100% accuracy for weights greater or equal to 0.5 kg. Drifts due to the lid opening and prolonged usage time were also measured, to implement automatic reset corrections. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

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20 pages, 3662 KiB

Open AccessArticle

An NFC on Two-Coil WPT Link for Implantable Biomedical Sensors under Ultra-Weak Coupling

by Chen Gong

, Dake Liu^*, Zhidong Miao

, Wei Wang and Min Li

Institute of Application Specific Instruction-Set Processors, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China

Sensors 2017, 17(6), 1358; https://doi.org/10.3390/s17061358 - 11 Jun 2017

Cited by 20 | Viewed by 8422

Abstract

The inductive link is widely used in implantable biomedical sensor systems to achieve near-field communication (NFC) and wireless power transfer (WPT). However, it is tough to achieve reliable NFC on an inductive WPT link when the coupling coefficient is ultra-low (0.01 typically), since [...] Read more.

The inductive link is widely used in implantable biomedical sensor systems to achieve near-field communication (NFC) and wireless power transfer (WPT). However, it is tough to achieve reliable NFC on an inductive WPT link when the coupling coefficient is ultra-low (0.01 typically), since the NFC signal (especially for the uplink from the in-body part to the out-body part) could be too weak to be detected. Traditional load shift keying (LSK) requires strong coupling to pass the load modulation information to the power source. Instead of using LSK, we propose a dual-carrier NFC scheme for the weak-coupled inductive link; using binary phase shift keying (BPSK) modulation, its downlink data are modulated on the power carrier (2 MHz), while its uplink data are modulated on another carrier (125 kHz). The two carriers are transferred through the same coil pair. To overcome the strong interference of the power carrier, dedicated circuits are introduced. In addition, to minimize the power transfer efficiency decrease caused by adding NFC, we optimize the inductive link circuit parameters and approach the receiver sensitivity limit. In the prototype experiments, even though the coupling coefficient is as low as 0.008, the in-body transmitter costs only 0.61 mW power carrying 10 kbps of data, and achieves a 1 × 10

- 7

bit error rate under the strong interference of WPT. This dual-carrier NFC scheme could be useful for small-sized implantable biomedical sensor applications. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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29 pages, 6689 KiB

Open AccessArticle

Emotional Self-Regulation of Individuals with Autism Spectrum Disorders: Smartwatches for Monitoring and Interaction

by Juan C. Torrado^*, Javier Gomez and Germán Montoro

Department of Computer Engineering, Universidad Autónoma de Madrid, Madrid 28049, Spain

Sensors 2017, 17(6), 1359; https://doi.org/10.3390/s17061359 - 11 Jun 2017

Cited by 85 | Viewed by 16668

Abstract

In this paper, we analyze the needs of individuals with Autism Spectrum Disorders (ASD) to have a pervasive, feasible and non-stigmatizing form of assistance in their emotional self-regulation, in order to ease certain behavioral issues that undermine their mental health throughout their life. [...] Read more.

In this paper, we analyze the needs of individuals with Autism Spectrum Disorders (ASD) to have a pervasive, feasible and non-stigmatizing form of assistance in their emotional self-regulation, in order to ease certain behavioral issues that undermine their mental health throughout their life. We argue the potential of recent widespread wearables, and more specifically smartwatches, to achieve this goal. Then, a smartwatch system that implements a wide range of self-regulation strategies and infers outburst patterns from physiological signals and movement is presented, along with an authoring tool for smartphones that is to be used by caregivers or family members to create and edit these strategies, in an adaptive way. We conducted an intensive experiment with two individuals with ASD who showed varied, representative behavioral responses to their emotional dysregulation. Both users were able to employ effective, customized emotional self-regulation strategies by means of the system, recovering from the majority of mild stress episodes and temper tantrums experienced in the nine days of experiment in their classroom. Full article

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

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21 pages, 3706 KiB

Open AccessArticle

Privacy-Preserving Electrocardiogram Monitoring for Intelligent Arrhythmia Detection

by Junggab Son¹, Juyoung Park², Heekuck Oh³, Md Zakirul Alam Bhuiyan⁴, Junbeom Hur^5,*

and Kyungtae Kang^3,*

¹ Department of Computer Science, Kennesaw State University, Marietta, GA 30060, USA

² Sustainable Management Strategy, Korea Expressway Corporation, Gimcheon 39660, Korea

³ Department of Computer Science and Engineering, Hanyang University, Ansan 15588, Korea

⁴ Department of Computer and Information Sciences, Fordham University, Bronx, NY 10458, USA

⁵ Department of Computer Science and Engineering, Korea University, Seoul 02841, Korea

Sensors 2017, 17(6), 1360; https://doi.org/10.3390/s17061360 - 12 Jun 2017

Cited by 19 | Viewed by 8255

Abstract

Long-term electrocardiogram (ECG) monitoring, as a representative application of cyber-physical systems, facilitates the early detection of arrhythmia. A considerable number of previous studies has explored monitoring techniques and the automated analysis of sensing data. However, ensuring patient privacy or confidentiality has not been [...] Read more.

Long-term electrocardiogram (ECG) monitoring, as a representative application of cyber-physical systems, facilitates the early detection of arrhythmia. A considerable number of previous studies has explored monitoring techniques and the automated analysis of sensing data. However, ensuring patient privacy or confidentiality has not been a primary concern in ECG monitoring. First, we propose an intelligent heart monitoring system, which involves a patient-worn ECG sensor (e.g., a smartphone) and a remote monitoring station, as well as a decision support server that interconnects these components. The decision support server analyzes the heart activity, using the Pan–Tompkins algorithm to detect heartbeats and a decision tree to classify them. Our system protects sensing data and user privacy, which is an essential attribute of dependability, by adopting signal scrambling and anonymous identity schemes. We also employ a public key cryptosystem to enable secure communication between the entities. Simulations using data from the MIT-BIH arrhythmia database demonstrate that our system achieves a 95.74% success rate in heartbeat detection and almost a 96.63% accuracy in heartbeat classification, while successfully preserving privacy and securing communications among the involved entities. Full article

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

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18 pages, 545 KiB

Open AccessArticle

Modeling the Error of the Medtronic Paradigm Veo Enlite Glucose Sensor

by Lyvia Biagi^1,2,†, Charrise M. Ramkissoon^1,†

, Andrea Facchinetti³

, Yenny Leal^4,5 and Josep Vehi^1,*

¹ Institut d’Informàtica i Aplicacions, Universitat de Girona, Campus de Montilivi, s/n, Edifici P4, 17071 Girona, Spain

² Federal University of Technology—Paraná, 85053-252 Guarapuava, Brazil

³ Department of Information Engineering, University of Padova, 35131 Padova, Italy

⁴ Service of Diabetes, Endocrinology and Nutrition (UDEN), Institut d’Investigació Biomédica de Girona (IdIBGi), Avinguda de França s/n, 17007 Girona, Spain

⁵ CIBER Pathophysiology of Obesity and Nutrition, Instituto de Salud Carlos III, 28029 Madrid, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1361; https://doi.org/10.3390/s17061361 - 12 Jun 2017

Cited by 18 | Viewed by 5820

Abstract

Continuous glucose monitors (CGMs) are prone to inaccuracy due to time lags, sensor drift, calibration errors, and measurement noise. The aim of this study is to derive the model of the error of the second generation Medtronic Paradigm Veo Enlite (ENL) sensor and [...] Read more.

Continuous glucose monitors (CGMs) are prone to inaccuracy due to time lags, sensor drift, calibration errors, and measurement noise. The aim of this study is to derive the model of the error of the second generation Medtronic Paradigm Veo Enlite (ENL) sensor and compare it with the Dexcom SEVEN PLUS (7P), G4 PLATINUM (G4P), and advanced G4 for Artificial Pancreas studies (G4AP) systems. An enhanced methodology to a previously employed technique was utilized to dissect the sensor error into several components. The dataset used included 37 inpatient sessions in 10 subjects with type 1 diabetes (T1D), in which CGMs were worn in parallel and blood glucose (BG) samples were analyzed every 15 ± 5 min Calibration error and sensor drift of the ENL sensor was best described by a linear relationship related to the gain and offset. The mean time lag estimated by the model is 9.4 ± 6.5 min. The overall average mean absolute relative difference (MARD) of the ENL sensor was 11.68 ± 5.07% Calibration error had the highest contribution to total error in the ENL sensor. This was also reported in the 7P, G4P, and G4AP. The model of the ENL sensor error will be useful to test the in silico performance of CGM-based applications, i.e., the artificial pancreas, employing this kind of sensor. Full article

(This article belongs to the Section Biosensors)

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17 pages, 9362 KiB

Open AccessArticle

Development of a Rigid One-Meter-Side and Cooled Coil Sensor at 77 K for Magnetic Resonance Sounding to Detect Subsurface Water Sources

by Jun Lin^1,2, Guanfeng Du^1,2, Jian Zhang^1,2

, Xiaofeng Yi^1,2, Chuandong Jiang^1,2,*

and Tingting Lin^1,2,*

¹ College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130061, China

² Key Laboratory of Geophysics Exploration Equipment, Ministry of Education of China, Changchun 130061, China

Sensors 2017, 17(6), 1362; https://doi.org/10.3390/s17061362 - 12 Jun 2017

Cited by 16 | Viewed by 6049

Abstract

Magnetic resonance sounding (MRS) using the Earth’s magnetic field is a noninvasive and on-site geophysical technique providing quantitative characteristics of aquifers in the subsurface. When the MRS technology is applied in a mine or tunnel for advance detecting the source of water that [...] Read more.

Magnetic resonance sounding (MRS) using the Earth’s magnetic field is a noninvasive and on-site geophysical technique providing quantitative characteristics of aquifers in the subsurface. When the MRS technology is applied in a mine or tunnel for advance detecting the source of water that may cause disastrous accident, spatial constraints limit the size of coil sensor and thus lower the detection capability. In this paper, a coil sensor for detecting the weak MRS signal is designed and the signal to noise (SNR) for the coil sensor is analyzed and optimized. The coil sensor has a rigid structure and square size of 1 m for deploying in a narrow underground space and is cooled at a low temperature of 77 K for improving the SNR. A theoretical calculation and an experimental test in an electromagnetically shielded room (EMSR) show that the optimal design of coil sensor consists of an 80-turn coil and a low-current-noise preamplifier AD745. It has a field sensitivity of 0.17

fT / \sqrt{Hz}

in the EMSR at 77 K, which is superior to the low temperature Superconducting Quantum Interference Device (LT SQUID) that is the latest application in MRS and the cooled coil with a diameter of 9 cm when detecting the laboratory NMR signal in kHz range. In the field experiment above the Taipingchi Reservoir near Changchun in China, the cooled coil sensor (CCS) developed in this paper has successfully obtained a valid weak MRS signal in high noise environment. The field results showed that the quality of measured MRS signal at 77 K is significantly superior to that at 298 K and the SNR is improved up to three times. This property of CCS makes the MRS instrument more convenient and reliable in a constricted space underground engineering environment (e.g., a mine or a tunnel). Full article

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

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13 pages, 1722 KiB

Open AccessArticle

Impacts of Satellite Orbit and Clock on Real-Time GPS Point and Relative Positioning

by Junbo Shi^1,2,*, Gaojing Wang^1,3

, Xianquan Han⁴ and Jiming Guo^1,2

¹ School of Geodesy and Geomatics,Wuhan University, Wuhan 430079, China

² Key Laboratory of Precise Engineering and Industry Surveying, National Administration of Surveying, Mapping and Geoinformation,Wuhan University, Wuhan 430079, China

³ State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University,Wuhan 430079, China

⁴ Engineering Safety and Disaster Prevention Department, Yangtze River Scientific Research Institute, Wuhan 430010, China

Sensors 2017, 17(6), 1363; https://doi.org/10.3390/s17061363 - 12 Jun 2017

Cited by 18 | Viewed by 4648

Abstract

Satellite orbit and clock corrections are always treated as known quantities in GPS positioning models. Therefore, any error in the satellite orbit and clock products will probably cause significant consequences for GPS positioning, especially for real-time applications. Currently three types of satellite products [...] Read more.

Satellite orbit and clock corrections are always treated as known quantities in GPS positioning models. Therefore, any error in the satellite orbit and clock products will probably cause significant consequences for GPS positioning, especially for real-time applications. Currently three types of satellite products have been made available for real-time positioning, including the broadcast ephemeris, the International GNSS Service (IGS) predicted ultra-rapid product, and the real-time product. In this study, these three predicted/real-time satellite orbit and clock products are first evaluated with respect to the post-mission IGS final product, which demonstrates cm to m level orbit accuracies and sub-ns to ns level clock accuracies. Impacts of real-time satellite orbit and clock products on GPS point and relative positioning are then investigated using the P3 and GAMIT software packages, respectively. Numerical results show that the real-time satellite clock corrections affect the point positioning more significantly than the orbit corrections. On the contrary, only the real-time orbit corrections impact the relative positioning. Compared with the positioning solution using the IGS final product with the nominal orbit accuracy of ~2.5 cm, the real-time broadcast ephemeris with ~2 m orbit accuracy provided <2 cm relative positioning error for baselines no longer than 216 km. As for the baselines ranging from 574 to 2982 km, the cm–dm level positioning error was identified for the relative positioning solution using the broadcast ephemeris. The real-time product could result in <5 mm relative positioning accuracy for baselines within 2982 km, slightly better than the predicted ultra-rapid product. Full article

(This article belongs to the Section Remote Sensors)

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27 pages, 5007 KiB

Open AccessArticle

Local Competition-Based Superpixel Segmentation Algorithm in Remote Sensing

by Jiayin Liu^1,*, Zhenmin Tang¹, Ying Cui² and Guoxing Wu³

¹ School of Computer Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

² College of Computer Science and Engineering, Zhejiang University of Technology, Hangzhou 310023, China

³ Huawei Technologies Co., Ltd., Nanjing 210012, China

Sensors 2017, 17(6), 1364; https://doi.org/10.3390/s17061364 - 12 Jun 2017

Cited by 12 | Viewed by 4726

Abstract

Remote sensing technologies have been widely applied in urban environments’ monitoring, synthesis and modeling. Incorporating spatial information in perceptually coherent regions, superpixel-based approaches can effectively eliminate the “salt and pepper” phenomenon which is common in pixel-wise approaches. Compared with fixed-size windows, superpixels have [...] Read more.

Remote sensing technologies have been widely applied in urban environments’ monitoring, synthesis and modeling. Incorporating spatial information in perceptually coherent regions, superpixel-based approaches can effectively eliminate the “salt and pepper” phenomenon which is common in pixel-wise approaches. Compared with fixed-size windows, superpixels have adaptive sizes and shapes for different spatial structures. Moreover, superpixel-based algorithms can significantly improve computational efficiency owing to the greatly reduced number of image primitives. Hence, the superpixel algorithm, as a preprocessing technique, is more and more popularly used in remote sensing and many other fields. In this paper, we propose a superpixel segmentation algorithm called Superpixel Segmentation with Local Competition (SSLC), which utilizes a local competition mechanism to construct energy terms and label pixels. The local competition mechanism leads to energy terms locality and relativity, and thus, the proposed algorithm is less sensitive to the diversity of image content and scene layout. Consequently, SSLC could achieve consistent performance in different image regions. In addition, the Probability Density Function (PDF), which is estimated by Kernel Density Estimation (KDE) with the Gaussian kernel, is introduced to describe the color distribution of superpixels as a more sophisticated and accurate measure. To reduce computational complexity, a boundary optimization framework is introduced to only handle boundary pixels instead of the whole image. We conduct experiments to benchmark the proposed algorithm with the other state-of-the-art ones on the Berkeley Segmentation Dataset (BSD) and remote sensing images. Results demonstrate that the SSLC algorithm yields the best overall performance, while the computation time-efficiency is still competitive. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 2534 KiB

Open AccessArticle

The Development of Indicator Cotton Swabs for the Detection of pH in Wounds

by Cindy Schaude¹, Eleonore Fröhlich²

, Claudia Meindl², Jennifer Attard³

, Barbara Binder⁴ and Gerhard J. Mohr^1,*

¹ JOANNEUM RESEARCH Forschungsgesellschaft mbH-Materials, Franz-Pichler-Straße 30, A-8160 Weiz, Austria

² Medical University of Graz, Center for Medical Research, Stiftingtalstraße 24, A-8010 Graz, Austria

³ Green Chemistry Centre of Excellence, University of York, York YO10 5DD, UK

⁴ Department of Dermatology and Venereology, Medical University of Graz, Auenbruggerplatz 8, A-8036 Graz, Austria

Sensors 2017, 17(6), 1365; https://doi.org/10.3390/s17061365 - 12 Jun 2017

Cited by 37 | Viewed by 9443

Abstract

Indicator cotton swabs have been developed in order to enable faster, less expensive, and simpler information gathering of a wound status. Swabs are normally used for cleaning the wound, but here, they were covalently functionalized with indicator chemistry. Thus, they in principle enable [...] Read more.

Indicator cotton swabs have been developed in order to enable faster, less expensive, and simpler information gathering of a wound status. Swabs are normally used for cleaning the wound, but here, they were covalently functionalized with indicator chemistry. Thus, they in principle enable simultaneous wound cleaning and wound pH detection. Using an indicator dye with a color change from yellow to red, combined with an inert dye of blue color, a traffic light color change from green to red is induced when pH increases. The indicator cotton swabs (ICSs) show a color change from green (appropriate wound pH) to red (elevated wound pH). This color change can be interpreted by the naked eye as well as by an optical color measurement device in order to obtain quantitative data based on the CIE L*a*b* color space. Two types of swabs have been developed—indicator cotton swabs ICS1 with a sensitive range from pH 5 to 7 and swabs ICS2 with a sensitive range from 6.5 to 8.5. The swabs are gamma-sterilized and the effect of sterilization on performance was found to be negligible. Furthermore, cytotoxicity testing shows cell viability and endotoxin levels to be within the allowable range. Full article

(This article belongs to the Section Chemical Sensors)

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28 pages, 8794 KiB

Open AccessArticle

An Energy-Aware Hybrid ARQ Scheme with Multi-ACKs for Data Sensing Wireless Sensor Networks

by Jinhuan Zhang and Jun Long^*

School of Information Science and Engineering, Central South University, Changsha 410083, China

Sensors 2017, 17(6), 1366; https://doi.org/10.3390/s17061366 - 12 Jun 2017

Cited by 5 | Viewed by 3891

Abstract

Wireless sensor networks (WSNs) are one of the important supporting technologies of edge computing. In WSNs, reliable communications are essential for most applications due to the unreliability of wireless links. In addition, network lifetime is also an important performance metric and needs to [...] Read more.

Wireless sensor networks (WSNs) are one of the important supporting technologies of edge computing. In WSNs, reliable communications are essential for most applications due to the unreliability of wireless links. In addition, network lifetime is also an important performance metric and needs to be considered in many WSN studies. In the paper, an energy-aware hybrid Automatic Repeat-reQuest protocol (ARQ) scheme is proposed to ensure energy efficiency under the guarantee of network transmission reliability. In the scheme, the source node sends data packets continuously with the correct window size and it does not need to wait for the acknowledgement (ACK) confirmation for each data packet. When the destination receives K data packets, it will return multiple copies of one ACK for confirmation to avoid ACK packet loss. The energy consumption of each node in flat circle network applying the proposed scheme is statistical analyzed and the cases under which it is more energy efficiency than the original scheme is discussed. Moreover, how to select parameters of the scheme is addressed to extend the network lifetime under the constraint of the network reliability. In addition, the energy efficiency of the proposed schemes is evaluated. Simulation results are presented to demonstrate that a node energy consumption reduction could be gained and the network lifetime is prolonged. Full article

(This article belongs to the Special Issue New Paradigms in Data Sensing and Processing for Edge Computing)

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10 pages, 3425 KiB

Open AccessArticle

A Novel Laser Refractive Surgical Treatment for Presbyopia: Optics-Based Customization for Improved Clinical Outcome

by Bojan Pajic^1,2,3,4

, Brigitte Pajic-Eggspuehler¹, Joerg Mueller¹, Zeljka Cvejic² and Harald Studer^1,5,*

¹ Eye Clinic Orasis, Swiss Eye Research Foundation, CH-5734 Reinach, Switzerland

² Department of Physics, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 4, 21000 Novi Sad, Serbia

³ Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, CH-1205 Geneva, Switzerland

⁴ Faculty of Medicine of the Military Medical academy, University of Defence, 11000 Belgrade, Serbia

⁵ OCTlab, Department of Ophthalmology, University of Basel, CH-4001 Basel, Switzerland

Sensors 2017, 17(6), 1367; https://doi.org/10.3390/s17061367 - 13 Jun 2017

Cited by 9 | Viewed by 5658

Abstract

Laser Assisted in Situ Keratomileusis (LASIK) is a proven treatment method for corneal refractive surgery. Surgically induced higher order optical aberrations were a major reason why the method was only rarely used to treat presbyopia, an age-related near-vision loss. In this study, a [...] Read more.

Laser Assisted in Situ Keratomileusis (LASIK) is a proven treatment method for corneal refractive surgery. Surgically induced higher order optical aberrations were a major reason why the method was only rarely used to treat presbyopia, an age-related near-vision loss. In this study, a novel customization algorithm for designing multifocal ablation patterns, thereby minimizing induced optical aberrations, was used to treat 36 presbyopic subjects. Results showed that most candidates went from poor visual acuity to uncorrected 20/20 vision or better for near (78%), intermediate (92%), and for distance (86%) vision, six months after surgery. All subjects were at 20/25 or better for distance and intermediate vision, and a majority (94%) were also better for near vision. Even though further studies are necessary, our results suggest that the employed methodology is a safe, reliable, and predictable refractive surgical treatment for presbyopia. 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, 2734 KiB

Open AccessArticle

Gold Electrodes Modified with Calix[4]arene for Electrochemical Determination of Dopamine in the Presence of Selected Neurotransmitters

by Katarzyna Kurzątkowska¹

, Serkan Sayin²

, Mustafa Yilmaz³, Hanna Radecka¹ and Jerzy Radecki^1,*

¹ Department of Biosensors, Institute of Animal Reproduction and Food Research Polish Academy of Science, Tuwima 10 Street, Olsztyn 10-748, Poland

² Department of Environmental Engineering, Faculty of Engineering, Giresun University, Giresun-28200, Turkey

³ Department of Chemistry, Selcuk University, Konya 42100, Turkey

Sensors 2017, 17(6), 1368; https://doi.org/10.3390/s17061368 - 13 Jun 2017

Cited by 12 | Viewed by 5960

Abstract

Here, we present an electrochemical sensor based on gold electrodes modified with calix[4]arene functionalized with carboxypiperidino groups at the upper rim. It has been demonstrated that these groups are involved in a complex formation with dopamine (DA) on the surface of gold electrodes. [...] Read more.

Here, we present an electrochemical sensor based on gold electrodes modified with calix[4]arene functionalized with carboxypiperidino groups at the upper rim. It has been demonstrated that these groups are involved in a complex formation with dopamine (DA) on the surface of gold electrodes. The supramolecular complex calix[4]arene–DA created on the gold electrode surface has been characterized electrochemically and the measuring conditions have been optimized. The presented sensor displayed a detection limit in the pM range. The DA determination was performed successfully in the presence of ascorbic acid, uric acid and selected neurotransmitters. Full article

(This article belongs to the Section Chemical Sensors)

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13 pages, 6166 KiB

Open AccessArticle

Ranging Consistency Based on Ranging-Compensated Temperature-Sensing Sensor for Inter-Satellite Link of Navigation Constellation

by Zhijun Meng, Jun Yang, Xiye Guo^* and Yongbin Zhou

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

Sensors 2017, 17(6), 1369; https://doi.org/10.3390/s17061369 - 13 Jun 2017

Viewed by 3566

Abstract

Global Navigation Satellite System performance can be significantly enhanced by introducing inter-satellite links (ISLs) in navigation constellation. The improvement in position, velocity, and time accuracy as well as the realization of autonomous functions requires ISL distance measurement data as the original input. To [...] Read more.

Global Navigation Satellite System performance can be significantly enhanced by introducing inter-satellite links (ISLs) in navigation constellation. The improvement in position, velocity, and time accuracy as well as the realization of autonomous functions requires ISL distance measurement data as the original input. To build a high-performance ISL, the ranging consistency among navigation satellites is an urgent problem to be solved. In this study, we focus on the variation in the ranging delay caused by the sensitivity of the ISL payload equipment to the ambient temperature in space and propose a simple and low-power temperature-sensing ranging compensation sensor suitable for onboard equipment. The experimental results show that, after the temperature-sensing ranging compensation of the ISL payload equipment, the ranging consistency becomes less than 0.2 ns when the temperature change is 90 °C. Full article

(This article belongs to the Section Remote Sensors)

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28 pages, 4615 KiB

Open AccessArticle

A Novel Unsupervised Adaptive Learning Method for Long-Term Electromyography (EMG) Pattern Recognition

by Qi Huang^1,*

, Dapeng Yang¹

, Li Jiang^1,*, Huajie Zhang¹, Hong Liu¹ and Kiyoshi Kotani²

¹ State Key Laboratory of Robotics and System, School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China

² Research Center for Advanced Science and Technology, the University of Tokyo and PRESTO/JST, Tokyo 153-8904, Japan

Sensors 2017, 17(6), 1370; https://doi.org/10.3390/s17061370 - 13 Jun 2017

Cited by 46 | Viewed by 7373

Abstract

Performance degradation will be caused by a variety of interfering factors for pattern recognition-based myoelectric control methods in the long term. This paper proposes an adaptive learning method with low computational cost to mitigate the effect in unsupervised adaptive learning scenarios. We presents [...] Read more.

Performance degradation will be caused by a variety of interfering factors for pattern recognition-based myoelectric control methods in the long term. This paper proposes an adaptive learning method with low computational cost to mitigate the effect in unsupervised adaptive learning scenarios. We presents a particle adaptive classifier (PAC), by constructing a particle adaptive learning strategy and universal incremental least square support vector classifier (LS-SVC). We compared PAC performance with incremental support vector classifier (ISVC) and non-adapting SVC (NSVC) in a long-term pattern recognition task in both unsupervised and supervised adaptive learning scenarios. Retraining time cost and recognition accuracy were compared by validating the classification performance on both simulated and realistic long-term EMG data. The classification results of realistic long-term EMG data showed that the PAC significantly decreased the performance degradation in unsupervised adaptive learning scenarios compared with NSVC (9.03% ± 2.23%, p < 0.05) and ISVC (13.38% ± 2.62%, p = 0.001), and reduced the retraining time cost compared with ISVC (2 ms per updating cycle vs. 50 ms per updating cycle). Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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22 pages, 5314 KiB

Open AccessArticle

Simple Smartphone-Based Guiding System for Visually Impaired People

by Bor-Shing Lin¹

, Cheng-Che Lee¹ and Pei-Ying Chiang^2,*

¹ Department of Computer Science and Information Engineering, National Taipei University, New Taipei City 23741, Taiwan

² Department of Computer Science and Information Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

Sensors 2017, 17(6), 1371; https://doi.org/10.3390/s17061371 - 13 Jun 2017

Cited by 95 | Viewed by 11020

Abstract

Visually impaired people are often unaware of dangers in front of them, even in familiar environments. Furthermore, in unfamiliar environments, such people require guidance to reduce the risk of colliding with obstacles. This study proposes a simple smartphone-based guiding system for solving the [...] Read more.

Visually impaired people are often unaware of dangers in front of them, even in familiar environments. Furthermore, in unfamiliar environments, such people require guidance to reduce the risk of colliding with obstacles. This study proposes a simple smartphone-based guiding system for solving the navigation problems for visually impaired people and achieving obstacle avoidance to enable visually impaired people to travel smoothly from a beginning point to a destination with greater awareness of their surroundings. In this study, a computer image recognition system and smartphone application were integrated to form a simple assisted guiding system. Two operating modes, online mode and offline mode, can be chosen depending on network availability. When the system begins to operate, the smartphone captures the scene in front of the user and sends the captured images to the backend server to be processed. The backend server uses the faster region convolutional neural network algorithm or the you only look once algorithm to recognize multiple obstacles in every image, and it subsequently sends the results back to the smartphone. The results of obstacle recognition in this study reached 60%, which is sufficient for assisting visually impaired people in realizing the types and locations of obstacles around them. Full article

(This article belongs to the Special Issue Smartphone-based Pedestrian Localization and Navigation)

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23 pages, 3888 KiB

Open AccessArticle

A Multi-Parametric Device with Innovative Solid Electrodes for Long-Term Monitoring of pH, Redox-Potential and Conductivity in a Nuclear Waste Repository

by Jordan Daoudi^1,*, Stephanie Betelu^1,*, Theodore Tzedakis², Johan Bertrand³ and Ioannis Ignatiadis¹

¹ Water, Environment and Eco-technologies, BRGM French Geological Survey, 45060 Orléans, France

² Laboratory of Chemical Engineering, Université de Toulouse III Paul Sabatier, 31062 Toulouse, France

³ Monitoring and Data Processing Department (DRD/MTD), ANDRA French National Radioactive Waste Management Agency, 92290 Châtenay Malabry, France

Sensors 2017, 17(6), 1372; https://doi.org/10.3390/s17061372 - 13 Jun 2017

Cited by 16 | Viewed by 5897

Abstract

We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl⁻ selective [...] Read more.

We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl⁻ selective electrodes, one Ag₂S/Ag-based reference or S²⁻ selective electrode, as well as four platinum electrodes, a gold electrode and a glassy-carbon electrode for redox potential measurements. Galvanostatic electrochemistry impedance spectroscopy using AgCl/Ag-based and platinum electrodes measure conductivity. The use of such a multi-parameter probe provides redundant information, based as it is on the simultaneous behaviour under identical conditions of different electrodes of the same material, as well as on that of electrodes made of different materials. This identifies the changes in physical and chemical parameters in a solution, as well as the redox reactions controlling the measured potential, both in the solution and/or at the electrode/solution interface. Understanding the electrochemical behaviour of selected materials thus is a key point of our research, as provides the basis for constructing the abacuses needed for developing robust and reliable field sensors. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in France 2016)

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15 pages, 2373 KiB

Open AccessArticle

Crop Classification in Satellite Images through Probabilistic Segmentation Based on Multiple Sources

by Oscar S. Dalmau^1,*,‡

, Teresa E. Alarcón^2,*,‡ and Francisco E. Oliva^2,‡

¹ Centro de Investigación en Matemat́icas, CIMAT, 36023 Guanajuato, Mexico

² Centro Universitario de los Valles, Universidad de Guadalajara, 46600 Ameca, Jalisco, Mexico

^‡ These authors contributed equally to this work.

Sensors 2017, 17(6), 1373; https://doi.org/10.3390/s17061373 - 13 Jun 2017

Cited by 6 | Viewed by 4377

Abstract

Classification methods based on Gaussian Markov Measure Field Models and other probabilistic approaches have to face the problem of construction of the likelihood. Typically, in these methods, the likelihood is computed from 1D or 3D histograms. However, when the number of information sources [...] Read more.

Classification methods based on Gaussian Markov Measure Field Models and other probabilistic approaches have to face the problem of construction of the likelihood. Typically, in these methods, the likelihood is computed from 1D or 3D histograms. However, when the number of information sources grows, as in the case of satellite images, the histogram construction becomes more difficult due to the high dimensionality of the feature space. In this work, we propose a generalization of Gaussian Markov Measure Field Models and provide a probabilistic segmentation scheme, which fuses multiple information sources for image segmentation. In particular, we apply the general model to classify types of crops in satellite images. The proposed method allows us to combine several feature spaces. For this purpose, the method requires prior information for building a 3D histogram for each considered feature space. Based on previous histograms, we can compute the likelihood of each site of the image to belong to a class. The computed likelihoods are the main input of the proposed algorithm and are combined in the proposed model using a contrast criteria. Different feature spaces are analyzed, among them are 6 spectral bands from LANDSAT 5 TM, 3 principal components from PCA on 6 spectral bands and 3 principal components from PCA applied on 10 vegetation indices. The proposed algorithm was applied to a real image and obtained excellent results in comparison to different classification algorithms used in crop classification. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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12 pages, 1182 KiB

Open AccessArticle

Interacting Multiple Model (IMM) Fifth-Degree Spherical Simplex-Radial Cubature Kalman Filter for Maneuvering Target Tracking

by Hua Liu^* and Wen Wu

Ministerial Key Laboratory of JGMT, Nanjing University of Science and Technology, Nanjing 210094, China

Sensors 2017, 17(6), 1374; https://doi.org/10.3390/s17061374 - 13 Jun 2017

Cited by 27 | Viewed by 7571

Abstract

For improving the tracking accuracy and model switching speed of maneuvering target tracking in nonlinear systems, a new algorithm named the interacting multiple model fifth-degree spherical simplex-radial cubature Kalman filter (IMM5thSSRCKF) is proposed in this paper. The new algorithm is a combination of [...] Read more.

For improving the tracking accuracy and model switching speed of maneuvering target tracking in nonlinear systems, a new algorithm named the interacting multiple model fifth-degree spherical simplex-radial cubature Kalman filter (IMM5thSSRCKF) is proposed in this paper. The new algorithm is a combination of the interacting multiple model (IMM) filter and the fifth-degree spherical simplex-radial cubature Kalman filter (5thSSRCKF). The proposed algorithm makes use of Markov process to describe the switching probability among the models, and uses 5thSSRCKF to deal with the state estimation of each model. The 5thSSRCKF is an improved filter algorithm, which utilizes the fifth-degree spherical simplex-radial rule to improve the filtering accuracy. Finally, the tracking performance of the IMM5thSSRCKF is evaluated by simulation in a typical maneuvering target tracking scenario. Simulation results show that the proposed algorithm has better tracking performance and quicker model switching speed when disposing maneuver models compared with the interacting multiple model unscented Kalman filter (IMMUKF), the interacting multiple model cubature Kalman filter (IMMCKF) and the interacting multiple model fifth-degree cubature Kalman filter (IMM5thCKF). Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 7085 KiB

Open AccessArticle

Microcontact Imprinted Plasmonic Nanosensors: Powerful Tools in the Detection of Salmonella paratyphi

by Işık Perçin¹, Neslihan Idil¹, Monireh Bakhshpour²

, Erkut Yılmaz³, Bo Mattiasson^4,5 and Adil Denizli^2,*

¹ Department of Biology, Hacettepe University, 06800 Ankara, Turkey

² Department of Chemistry, Hacettepe University, 06800 Ankara, Turkey

³ Department of Biotechnology and Molecular Biology, Aksaray University, 68100 Aksaray, Turkey

⁴ Department of Biotechnology, Lund University, 223 62 Lund, Sweden

⁵ CapSenze Biosystems AB, 223 63 Lund, Sweden

Sensors 2017, 17(6), 1375; https://doi.org/10.3390/s17061375 - 13 Jun 2017

Cited by 82 | Viewed by 7165

Abstract

Identification of pathogenic microorganisms by traditional methods is slow and cumbersome. Therefore, the focus today is on developing new and quicker analytical methods. In this study, a Surface Plasmon Resonance (SPR) sensor with a microcontact imprinted sensor chip was developed for detecting Salmonella [...] Read more.

Identification of pathogenic microorganisms by traditional methods is slow and cumbersome. Therefore, the focus today is on developing new and quicker analytical methods. In this study, a Surface Plasmon Resonance (SPR) sensor with a microcontact imprinted sensor chip was developed for detecting Salmonella paratyphi. For this purpose, the stamps of the target microorganism were prepared and then, microcontact S. paratyphi-imprinted SPR chips were prepared with the functional monomer N-methacryloyl-L-histidine methyl ester (MAH). Characterization studies of the SPR chips were carried out with ellipsometry and scanning electron microscopy (SEM). The real-time Salmonella paratyphi detection was performed within the range of 2.5 × 10⁶–15 × 10⁶ CFU/mL. Selectivity of the prepared sensors was examined by using competing bacterial strains such as Escherichia coli, Staphylococcus aureus and Bacillus subtilis. The imprinting efficiency of the prepared sensor system was determined by evaluating the responses of the SPR chips prepared with both molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs). Real sample experiments were performed with apple juice. The recognition of Salmonella paratyphi was achieved using these SPR sensor with a detection limit of 1.4 × 10⁶ CFU/mL. In conclusion, SPR sensor has the potential to serve as an excellent candidate for monitoring Salmonella paratyphi in food supplies or contaminated water and clearly makes it possible to develop rapid and appropriate control strategies. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

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20 pages, 1489 KiB

Open AccessArticle

QuickCash: Secure Transfer Payment Systems

by Abdulrahman Alhothaily^1,2, Arwa Alrawais^1,3, Tianyi Song¹, Bin Lin^4,* and Xiuzhen Cheng¹

¹ Department of Computer Science, The George Washington University, Washington, DC 20052, USA

² General Department of Payment Systems, Saudi Arabian Monetary Authority, Riyadh 11169, Saudi Arabia

³ College of Computer Engineering and Sciences, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia

⁴ Department of Information Science and Technology, Dalian Maritime University, Dalian 116026, China

Sensors 2017, 17(6), 1376; https://doi.org/10.3390/s17061376 - 13 Jun 2017

Cited by 12 | Viewed by 8342

Abstract

Payment systems play a significant role in our daily lives. They are an important driver of economic activities and a vital part of the banking infrastructure of any country. Several current payment systems focus on security and reliability but pay less attention to [...] Read more.

Payment systems play a significant role in our daily lives. They are an important driver of economic activities and a vital part of the banking infrastructure of any country. Several current payment systems focus on security and reliability but pay less attention to users’ needs and behaviors. For example, people may share their bankcards with friends or relatives to withdraw money for various reasons. This behavior can lead to a variety of privacy and security issues since the cardholder has to share a bankcard and other sensitive information such as a personal identification number (PIN). In addition, it is commonplace that cardholders may lose their cards, and may not be able to access their accounts due to various reasons. Furthermore, transferring money to an individual who has lost their bankcard and identification information is not a straightforward task. A user-friendly person-to-person payment system is urgently needed to perform secure and reliable transactions that benefit from current technological advancements. In this paper, we propose two secure fund transfer methods termed QuickCash Online and QuickCash Offline to transfer money from peer to peer using the existing banking infrastructure. Our methods provide a convenient way to transfer money quickly, and they do not require using bank cards or any identification card. Unlike other person-to-person payment systems, the proposed methods do not require the receiving entity to have a bank account, or to perform any registration procedure. We implement our QuickCash payment systems and analyze their security strengths and properties. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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32 pages, 15249 KiB

Open AccessReview

France’s State of the Art Distributed Optical Fibre Sensors Qualified for the Monitoring of the French Underground Repository for High Level and Intermediate Level Long Lived Radioactive Wastes

by Sylvie Delepine-Lesoille^1,*, Sylvain Girard², Marcel Landolt¹, Johan Bertrand¹, Isabelle Planes^1,2, Aziz Boukenter²

, Emmanuel Marin², Georges Humbert³, Stéphanie Leparmentier^1,3, Jean-Louis Auguste³ and Youcef Ouerdane²

¹ National Radioactive Waste Management Agency (Andra), F-92298 Chatenay-Malabry, France

² Laboratoire Hubert Curien CNRS UMR 5516, University of Lyon, F-42000 Saint-Etienne, France

³ XLIM Research Institute, UMR 7252 CNRS/University of Limoges, 123 Avenue Albert Thomas, F-87060, Limoges, France

Sensors 2017, 17(6), 1377; https://doi.org/10.3390/s17061377 - 13 Jun 2017

Cited by 46 | Viewed by 9076

Abstract

This paper presents the state of the art distributed sensing systems, based on optical fibres, developed and qualified for the French Cigéo project, the underground repository for high level and intermediate level long-lived radioactive wastes. Four main parameters, namely strain, temperature, radiation and [...] Read more.

This paper presents the state of the art distributed sensing systems, based on optical fibres, developed and qualified for the French Cigéo project, the underground repository for high level and intermediate level long-lived radioactive wastes. Four main parameters, namely strain, temperature, radiation and hydrogen concentration are currently investigated by optical fibre sensors, as well as the tolerances of selected technologies to the unique constraints of the Cigéo’s severe environment. Using fluorine-doped silica optical fibre surrounded by a carbon layer and polyimide coating, it is possible to exploit its Raman, Brillouin and Rayleigh scattering signatures to achieve the distributed sensing of the temperature and the strain inside the repository cells of radioactive wastes. Regarding the dose measurement, promising solutions are proposed based on Radiation Induced Attenuation (RIA) responses of sensitive fibres such as the P-doped ones. While for hydrogen measurements, the potential of specialty optical fibres with Pd particles embedded in their silica matrix is currently studied for this gas monitoring through its impact on the fibre Brillouin signature evolution. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in France 2016)

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20 pages, 1966 KiB

Open AccessArticle

Joint Optimization of Receiver Placement and Illuminator Selection for a Multiband Passive Radar Network

by Rui Xie¹, Xianrong Wan^1,*, Sheng Hong² and Jianxin Yi¹

¹ Radio Detection Research Center, School of Electronic Information, Wuhan University, Wuhan 430072, China

² Cognitive Radio Sensor Networks Laboratory, School of Information Engineering, Nanchang University, Nanchang 330038, China

Sensors 2017, 17(6), 1378; https://doi.org/10.3390/s17061378 - 14 Jun 2017

Cited by 9 | Viewed by 4274

Abstract

The performance of a passive radar network can be greatly improved by an optimal radar network structure. Generally, radar network structure optimization consists of two aspects, namely the placement of receivers in suitable places and selection of appropriate illuminators. The present study investigates [...] Read more.

The performance of a passive radar network can be greatly improved by an optimal radar network structure. Generally, radar network structure optimization consists of two aspects, namely the placement of receivers in suitable places and selection of appropriate illuminators. The present study investigates issues concerning the joint optimization of receiver placement and illuminator selection for a passive radar network. Firstly, the required radar cross section (RCS) for target detection is chosen as the performance metric, and the joint optimization model boils down to the partition p-center problem (PPCP). The PPCP is then solved by a proposed bisection algorithm. The key of the bisection algorithm lies in solving the partition set covering problem (PSCP), which can be solved by a hybrid algorithm developed by coupling the convex optimization with the greedy dropping algorithm. In the end, the performance of the proposed algorithm is validated via numerical simulations. Full article

(This article belongs to the Special Issue Cognitive Radio Sensing and Sensor Networks)

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24 pages, 2293 KiB

Open AccessReview

Tracking the Evolution of the Internet of Things Concept Across Different Application Domains

by Jorge E. Ibarra-Esquer^1,*

, Félix F. González-Navarro²

, Brenda L. Flores-Rios², Larysa Burtseva² and María A. Astorga-Vargas¹

¹ Facultad de Ingeniería, Universidad Autónoma de Baja California. Blvd. Benito Juárez S/N, Col. Insurgentes Este. Mexicali 21270, Mexico

² Instituto de Ingeniería, Universidad Autónoma de Baja California. Calle de la Normal S/N, Col. Insurgentes Este. Mexicali 21270, Mexico

Sensors 2017, 17(6), 1379; https://doi.org/10.3390/s17061379 - 14 Jun 2017

Cited by 135 | Viewed by 13403

Abstract

Both the idea and technology for connecting sensors and actuators to a network to remotely monitor and control physical systems have been known for many years and developed accordingly. However, a little more than a decade ago the concept of the Internet of [...] Read more.

Both the idea and technology for connecting sensors and actuators to a network to remotely monitor and control physical systems have been known for many years and developed accordingly. However, a little more than a decade ago the concept of the Internet of Things (IoT) was coined and used to integrate such approaches into a common framework. Technology has been constantly evolving and so has the concept of the Internet of Things, incorporating new terminology appropriate to technological advances and different application domains. This paper presents the changes that the IoT has undertaken since its conception and research on how technological advances have shaped it and fostered the arising of derived names suitable to specific domains. A two-step literature review through major publishers and indexing databases was conducted; first by searching for proposals on the Internet of Things concept and analyzing them to find similarities, differences, and technological features that allow us to create a timeline showing its development; in the second step the most mentioned names given to the IoT for specific domains, as well as closely related concepts were identified and briefly analyzed. The study confirms the claim that a consensus on the IoT definition has not yet been reached, as enabling technology keeps evolving and new application domains are being proposed. However, recent changes have been relatively moderated, and its variations on application domains are clearly differentiated, with data and data technologies playing an important role in the IoT landscape. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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8 pages, 7807 KiB

Open AccessArticle

Detection Performance Improvement of Distributed Vibration Sensor Based on Curvelet Denoising Method

by Zengguang Qin^*, Hui Chen and Jun Chang

School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China

Sensors 2017, 17(6), 1380; https://doi.org/10.3390/s17061380 - 14 Jun 2017

Cited by 30 | Viewed by 4911

Abstract

A curvelet denoising method has been proposed to reduce the time domain noise to improve the detection performance in the distributed fiber vibration sensing system based on phase-sensitive optical time domain reflectometry. The raw Rayleigh backscattering traces are regarded as a gray image [...] Read more.

A curvelet denoising method has been proposed to reduce the time domain noise to improve the detection performance in the distributed fiber vibration sensing system based on phase-sensitive optical time domain reflectometry. The raw Rayleigh backscattering traces are regarded as a gray image and the random noise can be eliminated by the curvelet transform; hence, the amplitude difference induced by the external vibration can be extracted. The detection of a vibration event with 10 m spatial resolution along a 4 km single mode fiber is demonstrated. The signal-to-noise ratio (SNR) of location information for 50 Hz and 1 kHz vibration based on this new method increases to as high as 7.8 dB and 8.0 dB, respectively, compared to the conventional method, showing the remarkable denoising capability of this new approach. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 15290 KiB

Open AccessArticle

Design and Fabrication of Piezoelectric Micromachined Ultrasound Transducer (pMUT) with Partially-Etched ZnO Film

by Junhong Li^*, Wei Ren, Guoxiang Fan and Chenghao Wang

State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Science, Beijing 100190, China

Sensors 2017, 17(6), 1381; https://doi.org/10.3390/s17061381 - 14 Jun 2017

Cited by 37 | Viewed by 8592

Abstract

A square piezoelectric composite diaphragm was analyzed by the finite element method to enhance the sensitivity of a piezoelectric micromachined ultrasound transducer (pMUT). The structures of electrode and piezoelectric film were optimized and a centric electrode was designed to avoid the counteraction of [...] Read more.

A square piezoelectric composite diaphragm was analyzed by the finite element method to enhance the sensitivity of a piezoelectric micromachined ultrasound transducer (pMUT). The structures of electrode and piezoelectric film were optimized and a centric electrode was designed to avoid the counteraction of stress in the centre and edges. In order to further improve the sensitivity; a pMUT with partially-etched piezoelectric film was adopted. The receive and transmit sensitivities of the pMUT were analyzed in details. The receive sensitivity of pMUT with partially-etched ZnO film is 3.3 dB or 6.8 dB higher than those with a centric and whole electrode, respectively; and the amplitude of a partially-etched ZnO film pMUT under a certain voltage is 5.5 dB and 30 dB higher than those with centric and whole electrode separately. Two pMUT-based ZnO films were fabricated by micromachining technology and their receive and transmit sensitivities were tested. The ZnO films deposited by direct current (DC) magnetron sputtering exhibit a densely packed structure with columnar crystallites. The test results show that the structure of the square diaphragm with partially-etched piezoelectric layer can significantly improve the transducer sensitivity. The receive sensitivity and transmit sensitivity are −238.35 dB (ref. 1 V/μPa) and 150.42 dB (ref. 1 μPa/V); respectively. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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25 pages, 3738 KiB

Open AccessArticle

A Framework for Learning Analytics Using Commodity Wearable Devices

by Yu Lu^1,2,*, Sen Zhang³

, Zhiqiang Zhang⁴

, Wendong Xiao³ and Shengquan Yu¹

¹ Advanced Innovation Center for Future Education, Beijing Normal University, Beijing 100875, China

² Institute for Infocomm Research, Agency for Science, Technology and Research, Singapore 138632, Singapore

³ School of Automation and Electrical Engineering, University of Science and Technology, Beijing 100083, China

⁴ School of Electronic and Electrical Engineering, University of Leeds, Leeds LS29JT, UK

Sensors 2017, 17(6), 1382; https://doi.org/10.3390/s17061382 - 14 Jun 2017

Cited by 35 | Viewed by 6607

Abstract

We advocate for and introduce LEARNSense, a framework for learning analytics using commodity wearable devices to capture learner’s physical actions and accordingly infer learner context (e.g., student activities and engagement status in class). Our work is motivated by the observations that: (a) the [...] Read more.

We advocate for and introduce LEARNSense, a framework for learning analytics using commodity wearable devices to capture learner’s physical actions and accordingly infer learner context (e.g., student activities and engagement status in class). Our work is motivated by the observations that: (a) the fine-grained individual-specific learner actions are crucial to understand learners and their context information; (b) sensor data available on the latest wearable devices (e.g., wrist-worn and eye wear devices) can effectively recognize learner actions and help to infer learner context information; (c) the commodity wearable devices that are widely available on the market can provide a hassle-free and non-intrusive solution. Following the above observations and under the proposed framework, we design and implement a sensor-based learner context collector running on the wearable devices. The latest data mining and sensor data processing techniques are employed to detect different types of learner actions and context information. Furthermore, we detail all of the above efforts by offering a novel and exemplary use case: it successfully provides the accurate detection of student actions and infers the student engagement states in class. The specifically designed learner context collector has been implemented on the commodity wrist-worn device. Based on the collected and inferred learner information, the novel intervention and incentivizing feedback are introduced into the system service. Finally, a comprehensive evaluation with the real-world experiments, surveys and interviews demonstrates the effectiveness and impact of the proposed framework and this use case. The F1 score for the student action classification tasks achieve 0.9, and the system can effectively differentiate the defined three learner states. Finally, the survey results show that the learners are satisfied with the use of our system (mean score of 3.7 with a standard deviation of 0.55). Full article

(This article belongs to the Section Sensor Networks)

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22 pages, 4452 KiB

Open AccessArticle

Dynamic Speed Adaptation for Path Tracking Based on Curvature Information and Speed Limits

by Citlalli Gámez Serna^*,‡ and Yassine Ruichek^‡

¹ Le2i FRE2005, CNRS, Arts et Métiers, University Bourgogne Franche-Comté, UTBM, F-90010 Belfort, France

^‡ These authors contributed equally to this work.

Sensors 2017, 17(6), 1383; https://doi.org/10.3390/s17061383 - 14 Jun 2017

Cited by 52 | Viewed by 12636

Abstract

A critical concern of autonomous vehicles is safety. Different approaches have tried to enhance driving safety to reduce the number of fatal crashes and severe injuries. As an example, Intelligent Speed Adaptation (ISA) systems warn the driver when the vehicle exceeds the recommended [...] Read more.

A critical concern of autonomous vehicles is safety. Different approaches have tried to enhance driving safety to reduce the number of fatal crashes and severe injuries. As an example, Intelligent Speed Adaptation (ISA) systems warn the driver when the vehicle exceeds the recommended speed limit. However, these systems only take into account fixed speed limits without considering factors like road geometry. In this paper, we consider road curvature with speed limits to automatically adjust vehicle’s speed with the ideal one through our proposed Dynamic Speed Adaptation (DSA) method. Furthermore, ‘curve analysis extraction’ and ‘speed limits database creation’ are also part of our contribution. An algorithm that analyzes GPS information off-line identifies high curvature segments and estimates the speed for each curve. The speed limit database contains information about the different speed limit zones for each traveled path. Our DSA senses speed limits and curves of the road using GPS information and ensures smooth speed transitions between current and ideal speeds. Through experimental simulations with different control algorithms on real and simulated datasets, we prove that our method is able to significantly reduce lateral errors on sharp curves, to respect speed limits and consequently increase safety and comfort for the passenger. Full article

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

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24 pages, 10223 KiB

Open AccessArticle

Instrumented Compliant Wrist with Proximity and Contact Sensing for Close Robot Interaction Control

by Pascal Laferrière and Pierre Payeur^*

School of Electrical Engineering and Computer Science, University of Ottawa, 800 King Edward, Ottawa, ON K1N 6N5, Canada

Sensors 2017, 17(6), 1384; https://doi.org/10.3390/s17061384 - 14 Jun 2017

Cited by 1 | Viewed by 5250

Abstract

Compliance has been exploited in various forms in robotic systems to allow rigid mechanisms to come into contact with fragile objects, or with complex shapes that cannot be accurately modeled. Force feedback control has been the classical approach for providing compliance in robotic [...] Read more.

Compliance has been exploited in various forms in robotic systems to allow rigid mechanisms to come into contact with fragile objects, or with complex shapes that cannot be accurately modeled. Force feedback control has been the classical approach for providing compliance in robotic systems. However, by integrating other forms of instrumentation with compliance into a single device, it is possible to extend close monitoring of nearby objects before and after contact occurs. As a result, safer and smoother robot control can be achieved both while approaching and while touching surfaces. This paper presents the design and extensive experimental evaluation of a versatile, lightweight, and low-cost instrumented compliant wrist mechanism which can be mounted on any rigid robotic manipulator in order to introduce a layer of compliance while providing the controller with extra sensing signals during close interaction with an object’s surface. Arrays of embedded range sensors provide real-time measurements on the position and orientation of surfaces, either located in proximity or in contact with the robot’s end-effector, which permits close guidance of its operation. Calibration procedures are formulated to overcome inter-sensor variability and achieve the highest available resolution. A versatile solution is created by embedding all signal processing, while wireless transmission connects the device to any industrial robot’s controller to support path control. Experimental work demonstrates the device’s physical compliance as well as the stability and accuracy of the device outputs. Primary applications of the proposed instrumented compliant wrist include smooth surface following in manufacturing, inspection, and safe human-robot interaction. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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18 pages, 1404 KiB

Open AccessArticle

Major Depression Detection from EEG Signals Using Kernel Eigen-Filter-Bank Common Spatial Patterns

by Shih-Cheng Liao^1,†, Chien-Te Wu^1,2,†, Hao-Chuan Huang³, Wei-Teng Cheng⁴ and Yi-Hung Liu^3,5,*

¹ Department of Psychiatry, National Taiwan University Hospital, Taipei 10051, Taiwan

² School of Occupational Therapy, College of Medicine, National Taiwan University, Taipei 10051, Taiwan

³ Graduate Institute of Mechatronics Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

⁴ Department of Mechanical Engineering, Chung Yuan Christian University, Chungli 32023, Taiwan

⁵ Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

^† These authors contributed equally to this work

Sensors 2017, 17(6), 1385; https://doi.org/10.3390/s17061385 - 14 Jun 2017

Cited by 138 | Viewed by 10637

Abstract

Major depressive disorder (MDD) has become a leading contributor to the global burden of disease; however, there are currently no reliable biological markers or physiological measurements for efficiently and effectively dissecting the heterogeneity of MDD. Here we propose a novel method based on [...] Read more.

Major depressive disorder (MDD) has become a leading contributor to the global burden of disease; however, there are currently no reliable biological markers or physiological measurements for efficiently and effectively dissecting the heterogeneity of MDD. Here we propose a novel method based on scalp electroencephalography (EEG) signals and a robust spectral-spatial EEG feature extractor called kernel eigen-filter-bank common spatial pattern (KEFB-CSP). The KEFB-CSP first filters the multi-channel raw EEG signals into a set of frequency sub-bands covering the range from theta to gamma bands, then spatially transforms the EEG signals of each sub-band from the original sensor space to a new space where the new signals (i.e., CSPs) are optimal for the classification between MDD and healthy controls, and finally applies the kernel principal component analysis (kernel PCA) to transform the vector containing the CSPs from all frequency sub-bands to a lower-dimensional feature vector called KEFB-CSP. Twelve patients with MDD and twelve healthy controls participated in this study, and from each participant we collected 54 resting-state EEGs of 6 s length (5 min and 24 s in total). Our results show that the proposed KEFB-CSP outperforms other EEG features including the powers of EEG frequency bands, and fractal dimension, which had been widely applied in previous EEG-based depression detection studies. The results also reveal that the 8 electrodes from the temporal areas gave higher accuracies than other scalp areas. The KEFB-CSP was able to achieve an average EEG classification accuracy of 81.23% in single-trial analysis when only the 8-electrode EEGs of the temporal area and a support vector machine (SVM) classifier were used. We also designed a voting-based leave-one-participant-out procedure to test the participant-independent individual classification accuracy. The voting-based results show that the mean classification accuracy of about 80% can be achieved by the KEFP-CSP feature and the SVM classifier with only several trials, and this level of accuracy seems to become stable as more trials (i.e., <7 trials) are used. These findings therefore suggest that the proposed method has a great potential for developing an efficient (required only a few 6-s EEG signals from the 8 electrodes over the temporal) and effective (~80% classification accuracy) EEG-based brain-computer interface (BCI) system which may, in the future, help psychiatrists provide individualized and effective treatments for MDD patients. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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14 pages, 1162 KiB

Open AccessArticle

Time-Frequency Analysis of Non-Stationary Biological Signals with Sparse Linear Regression Based Fourier Linear Combiner

by Yubo Wang¹ and Kalyana C. Veluvolu^2,*

¹ School of Life Science and Technology, Xidian University, Xi’an 710071, China

² School of Electronics Engineering, Kungpook National University, Daegu 702-701, Korea

Sensors 2017, 17(6), 1386; https://doi.org/10.3390/s17061386 - 14 Jun 2017

Cited by 14 | Viewed by 7122

Abstract

It is often difficult to analyze biological signals because of their nonlinear and non-stationary characteristics. This necessitates the usage of time-frequency decomposition methods for analyzing the subtle changes in these signals that are often connected to an underlying phenomena. This paper presents a [...] Read more.

It is often difficult to analyze biological signals because of their nonlinear and non-stationary characteristics. This necessitates the usage of time-frequency decomposition methods for analyzing the subtle changes in these signals that are often connected to an underlying phenomena. This paper presents a new approach to analyze the time-varying characteristics of such signals by employing a simple truncated Fourier series model, namely the band-limited multiple Fourier linear combiner (BMFLC). In contrast to the earlier designs, we first identified the sparsity imposed on the signal model in order to reformulate the model to a sparse linear regression model. The coefficients of the proposed model are then estimated by a convex optimization algorithm. The performance of the proposed method was analyzed with benchmark test signals. An energy ratio metric is employed to quantify the spectral performance and results show that the proposed method Sparse-BMFLC has high mean energy (0.9976) ratio and outperforms existing methods such as short-time Fourier transfrom (STFT), continuous Wavelet transform (CWT) and BMFLC Kalman Smoother. Furthermore, the proposed method provides an overall 6.22% in reconstruction error. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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15 pages, 3488 KiB

Open AccessArticle

An LMS Programming Scheme and Floating-Gate Technology Enabled Trimmer-Less and Low Voltage Flame Detection Sensor

by Juan Carlos Iglesias-Rojas^1,*

, Felipe Gomez-Castañeda² and Jose Antonio Moreno-Cadenas²

¹ Department of Communications and Electronics, National Polytechnic Institute, Mexico City 07738, Mexico

² Department of Electrical Engineering, Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico City 07360, Mexico

Sensors 2017, 17(6), 1387; https://doi.org/10.3390/s17061387 - 14 Jun 2017

Viewed by 7648

Abstract

In this paper, a Least Mean Square (LMS) programming scheme is used to set the offset voltage of two operational amplifiers that were built using floating-gate transistors, enabling a 0.95 V_RMS trimmer-less flame detection sensor. The programming scheme is capable of setting [...] Read more.

In this paper, a Least Mean Square (LMS) programming scheme is used to set the offset voltage of two operational amplifiers that were built using floating-gate transistors, enabling a 0.95 V_RMS trimmer-less flame detection sensor. The programming scheme is capable of setting the offset voltage over a wide range of values by means of electron injection. The flame detection sensor consists of two programmable offset operational amplifiers; the first amplifier serves as a 26 μV offset voltage follower, whereas the second amplifier acts as a programmable trimmer-less voltage comparator. Both amplifiers form the proposed sensor, whose principle of functionality is based on the detection of the electrical changes produced by the flame ionization. The experimental results show that it is possible to measure the presence of a flame accurately after programming the amplifiers with a maximum of 35 LMS-algorithm iterations. Current commercial flame detectors are mainly used in absorption refrigerators and large industrial gas heaters, where a high voltage AC source and several mechanical trimmings are used in order to accurately measure the presence of the flame. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 3786 KiB

Open AccessArticle

A Novel Sensor Based on a Single-Pixel Microwave Radiometer for Warm Object Counting: Concept Validation and IoT Perspectives

by Federico Alimenti^*

, Stefania Bonafoni

and Luca Roselli

Department of Engineering, University of Perugia, via G. Duranti 93, 06125 Perugia, Italy

Sensors 2017, 17(6), 1388; https://doi.org/10.3390/s17061388 - 14 Jun 2017

Cited by 5 | Viewed by 6243

Abstract

Controlled measurements by a low-cost single-pixel microwave radiometer operating at 12.65 GHz were carried out to assess the detection and counting capability for targets warmer than the surroundings. The adopted reference test targets were pre-warmed water and oil; and a hand, both naked [...] Read more.

Controlled measurements by a low-cost single-pixel microwave radiometer operating at 12.65 GHz were carried out to assess the detection and counting capability for targets warmer than the surroundings. The adopted reference test targets were pre-warmed water and oil; and a hand, both naked and wearing a glove. The results showed the reliability of microwave radiometry for counting operations under controlled conditions, and its effectiveness at detecting even warm targets masked by unheated dielectric layers. An electromagnetic model describing the scenario sensed by the radiometer antenna is proposed, and comparison with the experimental observations shows a good agreement. The measurements prove that reliable counting is enabled by an antenna temperature increment, for each target sample added, of around 1 K. Starting from this value, an analysis of the antenna filling factor was performed to provide an instrument useful for evaluating real applicability in many practical situations. This study also allows the direct people counting problem to be addressed, providing preliminary operational indications, reference numbers and experimental validation. Full article

(This article belongs to the Special Issue New Generation Sensors Enabling and Fostering IoT)

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17 pages, 2847 KiB

Open AccessArticle

A Novel Approach to Measuring Muscle Mechanics in Vehicle Collision Conditions

by Simon Krašna^1,*, Srđan Đorđević², Marija Hribernik³ and Ana Trajkovski¹

¹ Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenia

² TMG-BMC d.o.o., Štihova ulica 24, 1000 Ljubljana, Slovenia

³ Faculty of Medicine, University of Ljubljana, Korytkova ulica 2, 1000 Ljubljana, Slovenia

Sensors 2017, 17(6), 1389; https://doi.org/10.3390/s17061389 - 14 Jun 2017

Cited by 7 | Viewed by 5136

Abstract

The aim of the study was to evaluate a novel approach to measuring neck muscle load and activity in vehicle collision conditions. A series of sled tests were performed on 10 healthy volunteers at three severity levels to simulate low-severity frontal impacts. Electrical [...] Read more.

The aim of the study was to evaluate a novel approach to measuring neck muscle load and activity in vehicle collision conditions. A series of sled tests were performed on 10 healthy volunteers at three severity levels to simulate low-severity frontal impacts. Electrical activity—electromyography (EMG)—and muscle mechanical tension was measured bilaterally on the upper trapezius. A novel mechanical contraction (MC) sensor was used to measure the tension on the muscle surface. The neck extensor loads were estimated based on the inverse dynamics approach. The results showed strong linear correlation (Pearson’s coefficient = 0.821) between the estimated neck muscle load and the muscle tension measured with the MC sensor. The peak of the estimated neck muscle force delayed 0.2 ± 30.6 ms on average vs. the peak MC sensor signal compared to the average delay of 61.8 ± 37.4 ms vs. the peak EMG signal. The observed differences in EMG and MC sensor collected signals indicate that the MC sensor offers an additional insight into the analysis of the neck muscle load and activity in impact conditions. This approach enables a more detailed assessment of the muscle-tendon complex load of a vehicle occupant in pre-impact and impact conditions. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 4320 KiB

Open AccessArticle

An Extended Kriging Method to Interpolate Near-Surface Soil Moisture Data Measured by Wireless Sensor Networks

by Jialin Zhang^1,2, Xiuhong Li^1,2, Rongjin Yang³, Qiang Liu^1,2,*

, Long Zhao^1,2 and Baocheng Dou^1,2

¹ Center for Global Change Studies, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China

² State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences Beijing Normal University, Beijing 100101, China

³ Chinese Research Academy of Environmental Sciences, Beijing 100012, China

Sensors 2017, 17(6), 1390; https://doi.org/10.3390/s17061390 - 15 Jun 2017

Cited by 36 | Viewed by 6648

Abstract

In the practice of interpolating near-surface soil moisture measured by a wireless sensor network (WSN) grid, traditional Kriging methods with auxiliary variables, such as Co-kriging and Kriging with external drift (KED), cannot achieve satisfactory results because of the heterogeneity of soil moisture and [...] Read more.

In the practice of interpolating near-surface soil moisture measured by a wireless sensor network (WSN) grid, traditional Kriging methods with auxiliary variables, such as Co-kriging and Kriging with external drift (KED), cannot achieve satisfactory results because of the heterogeneity of soil moisture and its low correlation with the auxiliary variables. This study developed an Extended Kriging method to interpolate with the aid of remote sensing images. The underlying idea is to extend the traditional Kriging by introducing spectral variables, and operating on spatial and spectral combined space. The algorithm has been applied to WSN-measured soil moisture data in HiWATER campaign to generate daily maps from 10 June to 15 July 2012. For comparison, three traditional Kriging methods are applied: Ordinary Kriging (OK), which used WSN data only, Co-kriging and KED, both of which integrated remote sensing data as covariate. Visual inspections indicate that the result from Extended Kriging shows more spatial details than that of OK, Co-kriging, and KED. The Root Mean Square Error (RMSE) of Extended Kriging was found to be the smallest among the four interpolation results. This indicates that the proposed method has advantages in combining remote sensing information and ground measurements in soil moisture interpolation. Full article

(This article belongs to the Special Issue Sensors and Smart Sensing of Agricultural Land Systems)

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17 pages, 2324 KiB

Open AccessArticle

TrackCC: A Practical Wireless Indoor Localization System Based on Less-Expensive Chips

by Xiaolong Li^1,2,*

, Yan Zheng¹

, Jun Cai³ and Yunfei Yi⁴

¹ The School of Computer Science and Information Security, Guangxi Key Laboratory of Trusted Software, Guilin University of Electronic Technology, Guilin 541004, China

² Mobile E-Business Collaborative Innovation Center of Hunan Province, Key Laboratory of Hunan Province for Mobile Business Intelligence, Hunan University of Commerce, Changsha 410205, China

³ The Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada

⁴ The Department of Computer and Information Engineering, Hechi University, Hechi 546300, China

Sensors 2017, 17(6), 1391; https://doi.org/10.3390/s17061391 - 15 Jun 2017

Cited by 3 | Viewed by 4572

Abstract

This paper aims at proposing a new wireless indoor localization system (ILS), called TrackCC, based on a commercial type of low-power system-on-chip (SoC), nRF24LE1. This type of chip has only l output power levels and acute fluctuation for a received minimum power level [...] Read more.

This paper aims at proposing a new wireless indoor localization system (ILS), called TrackCC, based on a commercial type of low-power system-on-chip (SoC), nRF24LE1. This type of chip has only l output power levels and acute fluctuation for a received minimum power level in operation, which give rise to many practical challenges for designing localization algorithms. In order to address these challenges, we exploit the Markov theory to construct a

(l + 1) \times (l + 1)

-sized state transition matrix to remove the fluctuation, and then propose a priority-based pattern matching algorithm to search for the most similar match in the signal map to estimate the real position of unknown nodes. The experimental results show that, compared to two existing wireless ILSs, LANDMARC and SAIL, which have meter level positioning accuracy, the proposed TrackCC can achieve the decimeter level accuracy on average in both line-of-sight (LOS) and non-line-of-sight (NLOS) senarios. Full article

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

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17 pages, 34170 KiB

Open AccessArticle

Study of a Compression-Molding Process for Ultraviolet Light-Emitting Diode Exposure Systems via Finite-Element Analysis

by Kuo-Tsai Wu¹, Sheng-Jye Hwang^1,* and Huei-Huang Lee²

¹ Department of Mechanical Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan

² Department of Engineering Science, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan

Sensors 2017, 17(6), 1392; https://doi.org/10.3390/s17061392 - 15 Jun 2017

Cited by 2 | Viewed by 6038

Abstract

Although wafer-level camera lenses are a very promising technology, problems such as warpage with time and non-uniform thickness of products still exist. In this study, finite element simulation was performed to simulate the compression molding process for acquiring the pressure distribution on the [...] Read more.

Although wafer-level camera lenses are a very promising technology, problems such as warpage with time and non-uniform thickness of products still exist. In this study, finite element simulation was performed to simulate the compression molding process for acquiring the pressure distribution on the product on completion of the process and predicting the deformation with respect to the pressure distribution. Results show that the single-gate compression molding process significantly increases the pressure at the center of the product, whereas the multi-gate compressing molding process can effectively distribute the pressure. This study evaluated the non-uniform thickness of product and changes in the process parameters through computer simulations, which could help to improve the compression molding process. Full article

(This article belongs to the Special Issue Innovative Sensing Control Scheme for Advanced Materials)

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17 pages, 3516 KiB

Open AccessArticle

An Unobtrusive Fall Detection and Alerting System Based on Kalman Filter and Bayes Network Classifier

by Jian He^1,2,3

, Shuang Bai³ and Xiaoyi Wang^1,2,3,*

¹ Beijing Advanced Innovation Center for Future Internet Technology, Beijing 100124, China

² Beijing Engineering Research Center for IoT Software and Systems, Beijing 100124, China

³ School of Software Engineering, Beijing University of Technology, Beijing 100124, China

Sensors 2017, 17(6), 1393; https://doi.org/10.3390/s17061393 - 16 Jun 2017

Cited by 53 | Viewed by 10161

Abstract

Falls are one of the main health risks among the elderly. A fall detection system based on inertial sensors can automatically detect fall event and alert a caregiver for immediate assistance, so as to reduce injuries causing by falls. Nevertheless, most inertial sensor-based [...] Read more.

Falls are one of the main health risks among the elderly. A fall detection system based on inertial sensors can automatically detect fall event and alert a caregiver for immediate assistance, so as to reduce injuries causing by falls. Nevertheless, most inertial sensor-based fall detection technologies have focused on the accuracy of detection while neglecting quantization noise caused by inertial sensor. In this paper, an activity model based on tri-axial acceleration and gyroscope is proposed, and the difference between activities of daily living (ADLs) and falls is analyzed. Meanwhile, a Kalman filter is proposed to preprocess the raw data so as to reduce noise. A sliding window and Bayes network classifier are introduced to develop a wearable fall detection system, which is composed of a wearable motion sensor and a smart phone. The experiment shows that the proposed system distinguishes simulated falls from ADLs with a high accuracy of 95.67%, while sensitivity and specificity are 99.0% and 95.0%, respectively. Furthermore, the smart phone can issue an alarm to caregivers so as to provide timely and accurate help for the elderly, as soon as the system detects a fall. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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13 pages, 4124 KiB

Open AccessArticle

A Study on the Model of Detecting the Liquid Level of Sealed Containers Based on Kirchhoff Approximation Theory

by Bin Zhang^1,2, Wen-Ai Song^3,*, Yue-Juan Wei^3,*, Dong-Song Zhang³ and Wen-Yi Liu^1,2

¹ Key Laboratory of Instrumentation Science & Dynamic Measurement, Ministry of Education, North University of China, Taiyuan 030051, China

² Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan 030051, China

³ Software School of North University of China, Taiyuan 030051, China

Sensors 2017, 17(6), 1394; https://doi.org/10.3390/s17061394 - 15 Jun 2017

Cited by 3 | Viewed by 4994

Abstract

By simulating the sound field of a round piston transducer with the Kirchhoff integral theorem and analyzing the shape of ultrasound beams and propagation characteristics in a metal container wall, this study presents a model for calculating the echo sound pressure by using [...] Read more.

By simulating the sound field of a round piston transducer with the Kirchhoff integral theorem and analyzing the shape of ultrasound beams and propagation characteristics in a metal container wall, this study presents a model for calculating the echo sound pressure by using the Kirchhoff paraxial approximation theory, based on which and according to different ultrasonic impedance between gas and liquid media, a method for detecting the liquid level from outside of sealed containers is proposed. Then, the proposed method is evaluated through two groups of experiments. In the first group, three kinds of liquid media with different ultrasonic impedance are used as detected objects; the echo sound pressure is calculated by using the proposed model under conditions of four sets of different wall thicknesses. The changing characteristics of the echo sound pressure in the entire detection process are analyzed, and the effects of different ultrasonic impedance of liquids on the echo sound pressure are compared. In the second group, taking water as an example, two transducers with different radii are selected to measure the liquid level under four sets of wall thickness. Combining with sound field characteristics, the influence of different size transducers on the pressure calculation and detection resolution are discussed and analyzed. Finally, the experimental results indicate that measurement uncertainly is better than ±5 mm, which meets the industrial inspection requirements. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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17 pages, 7331 KiB

Open AccessArticle

Study of the Relation between the Resonance Behavior of Thickness Shear Mode (TSM) Sensors and the Mechanical Characteristics of Biofilms

by Pedro Castro^1,*, Luis Elvira¹

, Juan Ramón Maestre² and Francisco Montero de Espinosa¹

¹ Institute of Physical and Information Technologies, CSIC, C/Serrano, 144, 28006 Madrid, Spain

² Servicio de Microbiología Clínica, Hospital Central de la Defensa Gómez-Ulla, Glorieta del Ejército, s/n, 28047 Madrid, Spain

Sensors 2017, 17(6), 1395; https://doi.org/10.3390/s17061395 - 15 Jun 2017

Cited by 7 | Viewed by 4485

Abstract

This work analyzes some key aspects of the behavior of sensors based on piezoelectric Thickness Shear Mode (TSM) resonators to study and monitor microbial biofilms. The operation of these sensors is based on the analysis of their resonance properties (both resonance frequency and [...] Read more.

This work analyzes some key aspects of the behavior of sensors based on piezoelectric Thickness Shear Mode (TSM) resonators to study and monitor microbial biofilms. The operation of these sensors is based on the analysis of their resonance properties (both resonance frequency and dissipation factor) that vary in contact with the analyzed sample. This work shows that different variations during the microorganism growth can be detected by the sensors and highlights which of these changes are indicative of biofilm formation. TSM sensors have been used to monitor in real time the development of Staphylococcus epidermidis and Escherichia coli biofilms, formed on the gold electrode of the quartz crystal resonators, without any coating. Strains with different ability to produce biofilm have been tested. It was shown that, once a first homogeneous adhesion of bacteria was produced on the substrate, the biofilm can be considered as a semi-infinite layer and the quartz sensor reflects only the viscoelastic properties of the region immediately adjacent to the resonator, not being sensitive to upper layers of the biofilm. The experiments allow the microrheological evaluation of the complex shear modulus (G* = G′ + jG″) of the biofilm at 5 MHz and at 15 MHz, showing that the characteristic parameter that indicates the adhesion of a biofilm for the case of S. epidermidis and E. coli, is an increase in the resonance frequency shift of the quartz crystal sensor, which is connected with an increase of the real shear modulus, related to the elasticity or stiffness of the layer. In addition both the real and the imaginary shear modulus are frequency dependent at these high frequencies in biofilms. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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23 pages, 4709 KiB

Open AccessArticle

Development of a Stereovision-Based Technique to Measure the Spread Patterns of Granular Fertilizer Spreaders

by Simon R. Cool^1,2,*, Jan G. Pieters¹, Dejan Seatovic³

, Koen C. Mertens²

, David Nuyttens²

, Tim C. Van De Gucht²

and Jürgen Vangeyte²

¹ Department of Biosystems Engineering, Ghent University, Coupure Links 653, 9000 Gent, Belgium

² Fisheries and Food Research, Institute of Agricultural, Burg. Van Gansberghelaan 115, 9820 Merelbeke, Belgium

³ Faculty of Information Management & Media, University of Applied Sciences, Moltkestrasse 30, 76133 Karlsruhe, Germany

Sensors 2017, 17(6), 1396; https://doi.org/10.3390/s17061396 - 15 Jun 2017

Cited by 12 | Viewed by 7043

Abstract

Centrifugal fertilizer spreaders are by far the most commonly used granular fertilizer spreader type in Europe. Their spread pattern however is error-prone, potentially leading to an undesired distribution of particles in the field and losses out of the field, which is often caused [...] Read more.

Centrifugal fertilizer spreaders are by far the most commonly used granular fertilizer spreader type in Europe. Their spread pattern however is error-prone, potentially leading to an undesired distribution of particles in the field and losses out of the field, which is often caused by poor calibration of the spreader for the specific fertilizer used. Due to the large environmental impact of fertilizer use, it is important to optimize the spreading process and minimize these errors. Spreader calibrations can be performed by using collection trays to determine the (field) spread pattern, but this is very time-consuming and expensive for the farmer and hence not common practice. Therefore, we developed an innovative multi-camera system to predict the spread pattern in a fast and accurate way, independent of the spreader configuration. Using high-speed stereovision, ejection parameters of particles leaving the spreader vanes were determined relative to a coordinate system associated with the spreader. The landing positions and subsequent spread patterns were determined using a ballistic model incorporating the effect of tractor motion and wind. Experiments were conducted with a commercial spreader and showed a high repeatability. The results were transformed to one spatial dimension to enable comparison with transverse spread patterns determined in the field and showed similar results. Full article

(This article belongs to the Collection Sensors in Agriculture and Forestry)

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14 pages, 7234 KiB

Open AccessArticle

LDMOS Channel Thermometer Based on a Thermal Resistance Sensor for Balancing Temperature in Monolithic Power ICs

by Tingyou Lin^1,*

, Yingchieh Ho^2,* and Chauchin Su³

¹ Institute of Communications Engineering, National Chiao-Tung University, Hsinchu 30010, Taiwan

² Department of Electrical Engineering, National Dong-Hwa University, Hualien 97401, Taiwan

³ Department of Electrical Engineering, National Chiao-Tung University, Hsinchu 30010, Taiwan

Sensors 2017, 17(6), 1397; https://doi.org/10.3390/s17061397 - 15 Jun 2017

Cited by 3 | Viewed by 5735

Abstract

This paper presents a method of thermal balancing for monolithic power integrated circuits (ICs). An on-chip temperature monitoring sensor that consists of a poly resistor strip in each of multiple parallel MOSFET banks is developed. A temperature-to-frequency converter (TFC) is proposed to quantize [...] Read more.

This paper presents a method of thermal balancing for monolithic power integrated circuits (ICs). An on-chip temperature monitoring sensor that consists of a poly resistor strip in each of multiple parallel MOSFET banks is developed. A temperature-to-frequency converter (TFC) is proposed to quantize on-chip temperature. A pulse-width-modulation (PWM) methodology is developed to balance the channel temperature based on the quantization. The modulated PWM pulses control the hottest of metal-oxide-semiconductor field-effect transistor (MOSFET) bank to reduce its power dissipation and heat generation. A test chip with eight parallel MOSFET banks is fabricated in TSMC 0.25 μm HV BCD processes, and total area is 900 × 914 μm². The maximal temperature variation among the eight banks can reduce to 2.8 °C by the proposed thermal balancing system from 9.5 °C with 1.5 W dissipation. As a result, our proposed system improves the lifetime of a power MOSFET by 20%. Full article

(This article belongs to the Special Issue Innovative Smart Sensors for Control Systems)

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10 pages, 3260 KiB

Open AccessArticle

Tunable Temperature Response of a Thermochromic Photonic Gel Sensor Containing N-Isopropylacrylamide and 4-Acryloyilmorpholine

by Hwanam Kye¹, Young Gook Koh², Youkyung Kim¹, Sung Gu Han¹, Hyunjung Lee^3,* and Wonmok Lee^1,2,*

¹ Department of Chemistry, Sejong University, 209 Neungdong-ro, Gwngjin-gu, Seoul 05006, Korea

² Engain Co. Ltd. Korea Bio Park BLD C-201, Seongnam 13488, korea

³ School of Advanced Materials Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Korea

Sensors 2017, 17(6), 1398; https://doi.org/10.3390/s17061398 - 15 Jun 2017

Cited by 26 | Viewed by 7231

Abstract

In this study, thermochromic photonic gels were fabricated using 2-hydroxyethyl methacrylate (HEMA) as a hydrogel building block, and 4-Acryloyl morpholine (ACMO) and N-isopropylacrylamide (NIPAAM) as thermoresponsive monomers with different critical solution temperature behaviors. Rapid photopolymerization of opal-templated monomer mixtures of varying ACMO [...] Read more.

In this study, thermochromic photonic gels were fabricated using 2-hydroxyethyl methacrylate (HEMA) as a hydrogel building block, and 4-Acryloyl morpholine (ACMO) and N-isopropylacrylamide (NIPAAM) as thermoresponsive monomers with different critical solution temperature behaviors. Rapid photopolymerization of opal-templated monomer mixtures of varying ACMO contents formed five individual thermochromic inverse opal photonic gels integrated on a single substrate. With temperature variation from 10 °C to 80 °C, the changes in reflective colors and reflectance spectra of the respective thermochromic gels were noted, and λ_peak changes were plotted. Because NIPAAM exhibits a lower critical solution temperature (LCST) at 33 °C, the NIPAAM-only gel showed a steep slope for dλ_peak/dT below 40 °C, whereas the slope became flatter at high temperatures. As the ACMO content increased in the thermochromic gel, the curve of dλ_peak/dT turned out to be gradual within the investigated temperature range, exhibiting the entire visible range of colors. The incorporation of ACMO in NIPAAM-based thermochromic gels therefore enabled a better control of color changes at a relatively high-temperature regime compared to a NIPAAM-only gel. In addition, ACMO-containing thermochromic gels exhibited a smaller hysteresis of λ_peak for the heating and cooling cycle. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 3192 KiB

Open AccessArticle

Equivalent Circuit Model of Low-Frequency Magnetoelectric Effect in Disk-Type Terfenol-D/PZT Laminate Composites Considering a New Interface Coupling Factor

by Guofeng Lou

, Xinjie Yu^* and Shihua Lu

State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(6), 1399; https://doi.org/10.3390/s17061399 - 15 Jun 2017

Cited by 10 | Viewed by 7146

Abstract

This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb_0.3Dy_0.7Fe_1.92)/PZT (Pb(Zr,Ti)O₃) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at [...] Read more.

This paper describes the modeling of magnetoelectric (ME) effects for disk-type Terfenol-D (Tb_0.3Dy_0.7Fe_1.92)/PZT (Pb(Zr,Ti)O₃) laminate composite at low frequency by combining the advantages of the static elastic model and the equivalent circuit model, aiming at providing a guidance for the design and fabrication of the sensors based on magnetoelectric laminate composite. Considering that the strains of the magnetostrictive and piezoelectric layers are not equal in actual operating due to the epoxy resin adhesive bonding condition, the magnetostrictive and piezoelectric layers were first modeled through the equation of motion separately, and then coupled together with a new interface coupling factor k_c, which physically reflects the strain transfer between the phases. Furthermore, a theoretical expression containing k_c for the transverse ME voltage coefficient α_v and the optimum thickness ratio n_optim to which the maximum ME voltage coefficient corresponds were derived from the modified equivalent circuit of ME laminate, where the interface coupling factor acted as an ideal transformer. To explore the influence of mechanical load on the interface coupling factor k_c, two sets of weights, i.e., 100 g and 500 g, were placed on the top of the ME laminates with the same thickness ratio n in the sample fabrication. A total of 22 T-T mode disk-type ME laminate samples with different configurations were fabricated. The interface coupling factors determined from the measured α_v and the DC bias magnetic field H_bias were 0.11 for 500 g pre-mechanical load and 0.08 for 100 g pre-mechanical load. Furthermore, the measured optimum thickness ratios were 0.61 for k_c = 0.11 and 0.56 for k_c = 0.08. Both the theoretical ME voltage coefficient α_v and optimum thickness ratio n_optim containing k_c agreed well with the measured data, verifying the reasonability and correctness for the introduction of k_c in the modified equivalent circuit model. Full article

(This article belongs to the Special Issue Magnetoelectric Heterostructures and Sensors)

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13 pages, 2055 KiB

Open AccessReview

Photoacoustic Drug Delivery

by Yuqi Zhang^1,2, Jicheng Yu^1,2, Anna R. Kahkoska³ and Zhen Gu^1,2,3,*

¹ Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh, NC 27695, USA

² Center for Nanotechnology in Drug Delivery and Division of Molecular Pharmaceutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA

³ Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA

Sensors 2017, 17(6), 1400; https://doi.org/10.3390/s17061400 - 15 Jun 2017

Cited by 42 | Viewed by 9865

Abstract

Photoacoustic (PA) technology holds great potential in clinical translation as a new non-invasive bioimaging modality. In contrast to conventional optical imaging, PA imaging (PAI) enables higher resolution imaging with deeper imaging depth. Besides applications for diagnosis, PA has also been extended to theranostic [...] Read more.

Photoacoustic (PA) technology holds great potential in clinical translation as a new non-invasive bioimaging modality. In contrast to conventional optical imaging, PA imaging (PAI) enables higher resolution imaging with deeper imaging depth. Besides applications for diagnosis, PA has also been extended to theranostic applications. The guidance of PAI facilitates remotely controlled drug delivery. This review focuses on the recent development of PAI-mediated drug delivery systems. We provide an overview of the design of different PAI agents for drug delivery. The challenges and further opportunities regarding PA therapy are also discussed. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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28 pages, 7229 KiB

Open AccessArticle

Indoor Autonomous Control of a Two-Wheeled Inverted Pendulum Vehicle Using Ultra Wide Band Technology

by Dunzhu Xia^*, Yanhong Yao and Limei Cheng

Key Laboratory of Micro-inertial Instrument and Advanced Navigation Technology, Ministry of Education, School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

Sensors 2017, 17(6), 1401; https://doi.org/10.3390/s17061401 - 15 Jun 2017

Cited by 8 | Viewed by 7095

Abstract

In this paper, we aimed to achieve the indoor tracking control of a two-wheeled inverted pendulum (TWIP) vehicle. The attitude data are acquired from a low cost micro inertial measurement unit (IMU), and the ultra-wideband (UWB) technology is utilized to obtain an accurate [...] Read more.

In this paper, we aimed to achieve the indoor tracking control of a two-wheeled inverted pendulum (TWIP) vehicle. The attitude data are acquired from a low cost micro inertial measurement unit (IMU), and the ultra-wideband (UWB) technology is utilized to obtain an accurate estimation of the TWIP’s position. We propose a dual-loop control method to realize the simultaneous balance and trajectory tracking control for the TWIP vehicle. A robust adaptive second-order sliding mode control (2-RASMC) method based on an improved super-twisting (STW) algorithm is investigated to obtain the control laws, followed by several simulations to verify its robustness. The outer loop controller is designed using the idea of backstepping. Moreover, three typical trajectories, including a circle, a trifolium and a hexagon, have been designed to prove the adaptability of the control combinations. Six different combinations of inner and outer loop control algorithms have been compared, and the characteristics of inner and outer loop algorithm combinations have been analyzed. Simulation results demonstrate its tracking performance and thus verify the validity of the proposed control methods. Trajectory tracking experiments in a real indoor environment have been performed using our experimental vehicle to further validate the feasibility of the proposed algorithm in practice. Full article

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

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16 pages, 1517 KiB

Open AccessArticle

Torsional Ultrasound Sensor Optimization for Soft Tissue Characterization

by Juan Melchor^*

, Rafael Muñoz

and Guillermo Rus

Department of Structural Mechanics, University of Granada; ETS Ingenieros de Caminos, Severo Ochoa s/n, 18071 Granada, Spain

Sensors 2017, 17(6), 1402; https://doi.org/10.3390/s17061402 - 15 Jun 2017

Cited by 16 | Viewed by 5623

Abstract

Torsion mechanical waves have the capability to characterize shear stiffness moduli of soft tissue. Under this hypothesis, a computational methodology is proposed to design and optimize a piezoelectrics-based transmitter and receiver to generate and measure the response of torsional ultrasonic waves. The procedure [...] Read more.

Torsion mechanical waves have the capability to characterize shear stiffness moduli of soft tissue. Under this hypothesis, a computational methodology is proposed to design and optimize a piezoelectrics-based transmitter and receiver to generate and measure the response of torsional ultrasonic waves. The procedure employed is divided into two steps: (i) a finite element method (FEM) is developed to obtain a transmitted and received waveform as well as a resonance frequency of a previous geometry validated with a semi-analytical simplified model and (ii) a probabilistic optimality criteria of the design based on inverse problem from the estimation of robust probability of detection (RPOD) to maximize the detection of the pathology defined in terms of changes of shear stiffness. This study collects different options of design in two separated models, in transmission and contact, respectively. The main contribution of this work describes a framework to establish such as forward, inverse and optimization procedures to choose a set of appropriate parameters of a transducer. This methodological framework may be generalizable for other different applications. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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12 pages, 3294 KiB

Open AccessArticle

Development of an Automatic Testing Platform for Aviator’s Night Vision Goggle Honeycomb Defect Inspection

by Bo-Lin Jian and Chao-Chung Peng^*

Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 70101, Taiwan

Sensors 2017, 17(6), 1403; https://doi.org/10.3390/s17061403 - 15 Jun 2017

Cited by 4 | Viewed by 6257

Abstract

Due to the direct influence of night vision equipment availability on the safety of night-time aerial reconnaissance, maintenance needs to be carried out regularly. Unfortunately, some defects are not easy to observe or are not even detectable by human eyes. As a consequence, [...] Read more.

Due to the direct influence of night vision equipment availability on the safety of night-time aerial reconnaissance, maintenance needs to be carried out regularly. Unfortunately, some defects are not easy to observe or are not even detectable by human eyes. As a consequence, this study proposed a novel automatic defect detection system for aviator’s night vision imaging systems AN/AVS-6(V)1 and AN/AVS-6(V)2. An auto-focusing process consisting of a sharpness calculation and a gradient-based variable step search method is applied to achieve an automatic detection system for honeycomb defects. This work also developed a test platform for sharpness measurement. It demonstrates that the honeycomb defects can be precisely recognized and the number of the defects can also be determined automatically during the inspection. Most importantly, the proposed approach significantly reduces the time consumption, as well as human assessment error during the night vision goggle inspection procedures. Full article

(This article belongs to the Special Issue Innovative Sensing Control Scheme for Advanced Materials)

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32 pages, 45593 KiB

Open AccessArticle

Hyperspectral IASI L1C Data Compression

by Joaquín García-Sobrino^*

, Joan Serra-Sagristà

and Joan Bartrina-Rapesta

Department of Information and Communications Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Sensors 2017, 17(6), 1404; https://doi.org/10.3390/s17061404 - 16 Jun 2017

Cited by 5 | Viewed by 5226

Abstract

The Infrared Atmospheric Sounding Interferometer (IASI), implemented on the MetOp satellite series, represents a significant step forward in atmospheric forecast and weather understanding. The instrument provides infrared soundings of unprecedented accuracy and spectral resolution to derive humidity and atmospheric temperature profiles, as well [...] Read more.

The Infrared Atmospheric Sounding Interferometer (IASI), implemented on the MetOp satellite series, represents a significant step forward in atmospheric forecast and weather understanding. The instrument provides infrared soundings of unprecedented accuracy and spectral resolution to derive humidity and atmospheric temperature profiles, as well as some of the chemical components playing a key role in climate monitoring. IASI collects rich spectral information, which results in large amounts of data (about 16 Gigabytes per day). Efficient compression techniques are requested for both transmission and storage of such huge data. This study reviews the performance of several state of the art coding standards and techniques for IASI L1C data compression. Discussion embraces lossless, near-lossless and lossy compression. Several spectral transforms, essential to achieve improved coding performance due to the high spectral redundancy inherent to IASI products, are also discussed. Illustrative results are reported for a set of 96 IASI L1C orbits acquired over a full year (4 orbits per month for each IASI-A and IASI-B from July 2013 to June 2014) . Further, this survey provides organized data and facts to assist future research and the atmospheric scientific community. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 994 KiB

Open AccessArticle

A Sequential Optimization Calibration Algorithm for Near-Field Source Localization

by Jingjing Li¹, Xianxiang Yu^2,* and Guolong Cui²

¹ Kexin College Hebei University of Engineering, Handan 056038, China

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

Sensors 2017, 17(6), 1405; https://doi.org/10.3390/s17061405 - 15 Jun 2017

Cited by 2 | Viewed by 4091

Abstract

This paper considers the near-field source location problem for a nonuniform linear array (non-ULA) in the presence of sensor gain and phase errors. A sequential optimization calibration method is proposed to simultaneously estimate the gain and phase errors as well as the locations [...] Read more.

This paper considers the near-field source location problem for a nonuniform linear array (non-ULA) in the presence of sensor gain and phase errors. A sequential optimization calibration method is proposed to simultaneously estimate the gain and phase errors as well as the locations of calibration sources involving the ranges and the azimuths by exploiting some imprecise a-priori knowledge of calibration sources. At each iteration of the proposed method, the source locations, and the gain and phase errors are obtained iteratively. Finally, at the analysis stage, we evaluate the effectiveness of the proposed technique using some numerical simulations. Results show that the proposed algorithm shares the capability to jointly estimate the source locations and the errors. Full article

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

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13 pages, 2814 KiB

Open AccessArticle

Identification of Pathogenic Factors in Klebsiella pneumoniae Using Impedimetric Sensor Equipped with Biomimetic Surfaces

by Duyen Thi Ngoc Huynh

, Ah-Young Kim and Young-Rok Kim^*

Department of Food Science and Biotechnology & Graduate School of Biotechnology, College of Life Sciences, Kyung Hee University, Yongin 17104, Korea

Sensors 2017, 17(6), 1406; https://doi.org/10.3390/s17061406 - 15 Jun 2017

Cited by 24 | Viewed by 6234

Abstract

K. pneumoniae is an opportunistic pathogen that causes nosocomial infections, such as, pneumonia, urinary tract infections, septic shock, and gastro intestinal disease. Lipopolysaccharide (LPS), capsular polysaccharide, and fimbriae are recognized major virulence factors of K. pneumoniae and play key roles during early stages [...] Read more.

K. pneumoniae is an opportunistic pathogen that causes nosocomial infections, such as, pneumonia, urinary tract infections, septic shock, and gastro intestinal disease. Lipopolysaccharide (LPS), capsular polysaccharide, and fimbriae are recognized major virulence factors of K. pneumoniae and play key roles during early stages of infections. In this study, we functionalized the surface of gold electrode with mannose and mucin to monitor the adhesion-associated virulence factors of K. pneumoniae. The binding characteristics of K. pneumoniae 2242 wild type and of its isogenic mutants lacking outer-core LPS (∆wabG) or fimbriae (∆fimA) were investigated using Faradaic impedance spectra. The results obtained showed fimbriae are responsible for K. pneumoniae adhesion to the mannose of glycoprotein on the surfaces of epithelial cells, whereas outer-core LPS and capsular polysaccharide are associated with specific binding to mucous. These results concurred with those of a conventional in vitro assay using human ileocecal epithelial cell (HCT-8 cells) and a human bladder epithelial cell (T-24), indicating that the devised method could be useful for investigating virulence-associated interactions of pathogenic bacteria with specific host cells and organs. Full article

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

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20 pages, 2624 KiB

Open AccessArticle

Dynamic Resource Allocation and Access Class Barring Scheme for Delay-Sensitive Devices in Machine to Machine (M2M) Communications

by Ning Li, Chao Cao^* and Cong Wang^*

College of Communications Engineering, PLA University of Science and Technology, Nanjing 210007, China

Sensors 2017, 17(6), 1407; https://doi.org/10.3390/s17061407 - 15 Jun 2017

Cited by 33 | Viewed by 5450

Abstract

Supporting simultaneous access of machine-type devices is a critical challenge in machine-to-machine (M2M) communications. In this paper, we propose an optimal scheme to dynamically adjust the Access Class Barring (ACB) factor and the number of random access channel (RACH) resources for clustered machine-to-machine [...] Read more.

Supporting simultaneous access of machine-type devices is a critical challenge in machine-to-machine (M2M) communications. In this paper, we propose an optimal scheme to dynamically adjust the Access Class Barring (ACB) factor and the number of random access channel (RACH) resources for clustered machine-to-machine (M2M) communications, in which Delay-Sensitive (DS) devices coexist with Delay-Tolerant (DT) ones. In M2M communications, since delay-sensitive devices share random access resources with delay-tolerant devices, reducing the resources consumed by delay-sensitive devices means that there will be more resources available to delay-tolerant ones. Our goal is to optimize the random access scheme, which can not only satisfy the requirements of delay-sensitive devices, but also take the communication quality of delay-tolerant ones into consideration. We discuss this problem from the perspective of delay-sensitive services by adjusting the resource allocation and ACB scheme for these devices dynamically. Simulation results show that our proposed scheme realizes good performance in satisfying the delay-sensitive services as well as increasing the utilization rate of the random access resources allocated to them. Full article

(This article belongs to the Special Issue The Architectures, Systems, and Applications of Internet of Things for Smart Cities)

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10 pages, 1444 KiB

Open AccessArticle

Breathing Analysis Using Thermal and Depth Imaging Camera Video Records

by Aleš Procházka^1,*

, Hana Charvátová²

, Oldřich Vyšata^1,3,4, Jakub Kopal¹ and Jonathon Chambers⁵

¹ Department of Computing and Control Engineering, University of Chemistry and Technology in Prague, 166 28 Prague, Czech Republic

² Faculty of Applied Informatics, Tomas Bata University in Zlín, 760 05 Zlín, Czech Republic

³ Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, 166 36 Prague, Czech Republic

⁴ Faculty of Medicine in Hradec Králové, Department of Neurology, Charles University, 500 05 Hradec Kralove, Czech Republic

⁵ School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK

Sensors 2017, 17(6), 1408; https://doi.org/10.3390/s17061408 - 16 Jun 2017

Cited by 63 | Viewed by 11042

Abstract

The paper is devoted to the study of facial region temperature changes using a simple thermal imaging camera and to the comparison of their time evolution with the pectoral area motion recorded by the MS Kinect depth sensor. The goal of this research [...] Read more.

The paper is devoted to the study of facial region temperature changes using a simple thermal imaging camera and to the comparison of their time evolution with the pectoral area motion recorded by the MS Kinect depth sensor. The goal of this research is to propose the use of video records as alternative diagnostics of breathing disorders allowing their analysis in the home environment as well. The methods proposed include (i) specific image processing algorithms for detecting facial parts with periodic temperature changes; (ii) computational intelligence tools for analysing the associated videosequences; and (iii) digital filters and spectral estimation tools for processing the depth matrices. Machine learning applied to thermal imaging camera calibration allowed the recognition of its digital information with an accuracy close to 100% for the classification of individual temperature values. The proposed detection of breathing features was used for monitoring of physical activities by the home exercise bike. The results include a decrease of breathing temperature and its frequency after a load, with mean values −0.16 °C/min and −0.72 bpm respectively, for the given set of experiments. The proposed methods verify that thermal and depth cameras can be used as additional tools for multimodal detection of breathing patterns. Full article

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

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17 pages, 7229 KiB

Open AccessArticle

Integration of P-CuO Thin Sputtered Layers onto Microsensor Platforms for Gas Sensing

by Lionel Presmanes^1,*

, Yohann Thimont¹

, Imane El Younsi¹, Audrey Chapelle², Frédéric Blanc², Chabane Talhi², Corine Bonningue¹, Antoine Barnabé¹, Philippe Menini^2,* and Philippe Tailhades¹

¹ CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, 118 Route de Narbonne, F-31062 Toulouse CEDEX 9, France

² LAAS-CNRS, Université de Toulouse, UPS, INSA, 7 avenue du colonel Roche, F-31031 Toulouse, France

Sensors 2017, 17(6), 1409; https://doi.org/10.3390/s17061409 - 16 Jun 2017

Cited by 31 | Viewed by 5742

Abstract

P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences [...] Read more.

P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH₃), acetaldehyde (C₂H₄O), and nitrogen dioxide (NO₂) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins. Because the microheaters were designed on a membrane, it was then possible to generate very rapid temperature variations (from room temperature to 550 °C in only 50 ms) and a rapid temperature cycling mode could be applied. This measurement mode allowed a significant improvement of the sensor response under 2 and 5 ppm of acetaldehyde. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in France 2016)

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21 pages, 1389 KiB

Open AccessArticle

Root System Water Consumption Pattern Identification on Time Series Data

by Manuel Figueroa

and Christopher Pope^*

Telefonica Investigación y Desarrollo Chile, Manuel Montt 1404, 7501105 Santiago, Chile

Sensors 2017, 17(6), 1410; https://doi.org/10.3390/s17061410 - 16 Jun 2017

Cited by 13 | Viewed by 5176

Abstract

In agriculture, soil and meteorological sensors are used along low power networks to capture data, which allows for optimal resource usage and minimizing environmental impact. This study uses time series analysis methods for outliers’ detection and pattern recognition on soil moisture sensor data [...] Read more.

In agriculture, soil and meteorological sensors are used along low power networks to capture data, which allows for optimal resource usage and minimizing environmental impact. This study uses time series analysis methods for outliers’ detection and pattern recognition on soil moisture sensor data to identify irrigation and consumption patterns and to improve a soil moisture prediction and irrigation system. This study compares three new algorithms with the current detection technique in the project; the results greatly decrease the number of false positives detected. The best result is obtained by the Series Strings Comparison (SSC) algorithm averaging a precision of 0.872 on the testing sets, vastly improving the current system’s 0.348 precision. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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16 pages, 33352 KiB

Open AccessArticle

A Multi-Disciplinary Approach to Remote Sensing through Low-Cost UAVs

by Gabriela Calvario^1,*

, Basilio Sierra¹, Teresa E. Alarcón², Carmen Hernandez¹ and Oscar Dalmau³

¹ Departamento de Ciencias de la Computación e Inteligencia Artificial, Universidad del País Vasco UPV/EHU, 20018 Donostia-San Sebastián, Spain

² Centro Universitario de los Valles, Carretera Guadalajara - Ameca Km. 45.5, CP 46600 Ameca, Jalisco, México

³ Centro de Investigación en Matemáticas, Jalisco SN, Col. Valenciana, CP 36240, Guanajuato, México

Sensors 2017, 17(6), 1411; https://doi.org/10.3390/s17061411 - 16 Jun 2017

Cited by 21 | Viewed by 6730

Abstract

The use of Unmanned Aerial Vehicles (UAVs) based on remote sensing has generated low cost monitoring, since the data can be acquired quickly and easily. This paper reports the experience related to agave crop analysis with a low cost UAV. The data were [...] Read more.

The use of Unmanned Aerial Vehicles (UAVs) based on remote sensing has generated low cost monitoring, since the data can be acquired quickly and easily. This paper reports the experience related to agave crop analysis with a low cost UAV. The data were processed by traditional photogrammetric flow and data extraction techniques were applied to extract new layers and separate the agave plants from weeds and other elements of the environment. Our proposal combines elements of photogrammetry, computer vision, data mining, geomatics and computer science. This fusion leads to very interesting results in agave control. This paper aims to demonstrate the potential of UAV monitoring in agave crops and the importance of information processing with reliable data flow. Full article

(This article belongs to the Section Remote Sensors)

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24 pages, 4132 KiB

Open AccessArticle

System Proposal for Mass Transit Service Quality Control Based on GPS Data

by Gabino Padrón, Teresa Cristóbal, Francisco Alayón, Alexis Quesada-Arencibia^*

and Carmelo R. García^*

Institute for Cybernetics, Campus de Tafira, Las Palmas de Gran Canaria, University of Las Palmas de Gran Canaria, Las Palmas 35017, Spain

Sensors 2017, 17(6), 1412; https://doi.org/10.3390/s17061412 - 16 Jun 2017

Cited by 5 | Viewed by 4448

Abstract

Quality is an essential aspect of public transport. In the case of regular public passenger transport by road, punctuality and regularity are criteria used to assess quality of service. Calculating metrics related to these criteria continuously over time and comprehensively across the entire [...] Read more.

Quality is an essential aspect of public transport. In the case of regular public passenger transport by road, punctuality and regularity are criteria used to assess quality of service. Calculating metrics related to these criteria continuously over time and comprehensively across the entire transport network requires the handling of large amounts of data. This article describes a system for continuously and comprehensively monitoring punctuality and regularity. The system uses location data acquired continuously in the vehicles and automatically transferred for analysis. These data are processed intelligently by elements that are commonly used by transport operators: GPS-based tracking system, onboard computer and wireless networks for mobile data communications. The system was tested on a transport company, for which we measured the punctuality of one of the routes that it operates; the results are presented in this article. Full article

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

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17 pages, 3853 KiB

Open AccessArticle

A Quantile Mapping Bias Correction Method Based on Hydroclimatic Classification of the Guiana Shield

by Justine Ringard^1,*

, Frederique Seyler²

and Laurent Linguet¹

¹ Université de Guyane, UMR ESPACE-DEV, IRD, Université de La Réunion, Université de Montpellier, F-97300 Cayenne, French Guiana

² IRD, UMR ESPACE-DEV, Université de Guyane, Université de La Réunion, Université de Montpellier, Maison de la Télédétection, 500 rue Jean-François Breton, F-34093 Montpellier CEDEX 5, France

Sensors 2017, 17(6), 1413; https://doi.org/10.3390/s17061413 - 16 Jun 2017

Cited by 75 | Viewed by 8331

Abstract

Satellite precipitation products (SPPs) provide alternative precipitation data for regions with sparse rain gauge measurements. However, SPPs are subject to different types of error that need correction. Most SPP bias correction methods use the statistical properties of the rain gauge data to adjust [...] Read more.

Satellite precipitation products (SPPs) provide alternative precipitation data for regions with sparse rain gauge measurements. However, SPPs are subject to different types of error that need correction. Most SPP bias correction methods use the statistical properties of the rain gauge data to adjust the corresponding SPP data. The statistical adjustment does not make it possible to correct the pixels of SPP data for which there is no rain gauge data. The solution proposed in this article is to correct the daily SPP data for the Guiana Shield using a novel two set approach, without taking into account the daily gauge data of the pixel to be corrected, but the daily gauge data from surrounding pixels. In this case, a spatial analysis must be involved. The first step defines hydroclimatic areas using a spatial classification that considers precipitation data with the same temporal distributions. The second step uses the Quantile Mapping bias correction method to correct the daily SPP data contained within each hydroclimatic area. We validate the results by comparing the corrected SPP data and daily rain gauge measurements using relative RMSE and relative bias statistical errors. The results show that analysis scale variation reduces rBIAS and rRMSE significantly. The spatial classification avoids mixing rainfall data with different temporal characteristics in each hydroclimatic area, and the defined bias correction parameters are more realistic and appropriate. This study demonstrates that hydroclimatic classification is relevant for implementing bias correction methods at the local scale. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 4891 KiB

Open AccessArticle

Long-Term In-Service Monitoring and Performance Assessment of the Main Cables of Long-Span Suspension Bridges

by Yang Deng^1,2,*, Yang Liu^1,* and Suren Chen³

¹ School of Civil Engineering and Architecture, Changsha University of Science & Technology, Changsha 410004, China

² Beijing Advanced Innovation Center for Future Urban Design, Beijing University of Civil Engineering and Architecture, Beijing 100044, China

³ Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO 80523, USA

Sensors 2017, 17(6), 1414; https://doi.org/10.3390/s17061414 - 16 Jun 2017

Cited by 25 | Viewed by 6835

Abstract

Despite the recent developments in structural health monitoring, there remain great challenges for accurately, conveniently, and economically assessing the in-service performance of the main cables for long-span suspension bridges. A long-term structural health monitoring technique is developed to measure the tension force with [...] Read more.

Despite the recent developments in structural health monitoring, there remain great challenges for accurately, conveniently, and economically assessing the in-service performance of the main cables for long-span suspension bridges. A long-term structural health monitoring technique is developed to measure the tension force with a conventional sensing technology and further provide the in-service performance assessment strategy of the main cable. The monitoring system adopts conventional vibrating strings transducers to monitor the tension forces of separate cable strands of the main cable in the anchor span. The performance evaluation of the main cable is conducted based on the collected health monitoring data: (1) the measured strand forces are used to derive the overall tension force of a main cable, which is further translated into load bearing capacity assessment using the concept of safety factor; and (2) the proposed technique can also evaluate the uniformity of tension forces from different cable strands. The assessment of uniformity of strand forces of a main cable offers critical information in terms of potential risks of partial damage and performance deterioration of the main cable. The results suggest the proposed low-cost monitoring system is an option to provide approximate estimation of tension forces of main cables for suspension bridges. With the long-term monitoring data, the proposed monitoring-based evaluation methods can further provide critical information to assess the safety and serviceability performance of main cables. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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9 pages, 1706 KiB

Open AccessArticle

High Sensitivity Refractometer Based on Reflective Smf-Small Diameter No Core Fiber Structure

by Guorui Zhou^1,2,†, Qiang Wu^2,*,†, Rahul Kumar^2,†, Wai Pang Ng², Hao Liu¹, Longfei Niu¹, Nageswara Lalam²

, Xiaodong Yuan¹

, Yuliya Semenova³, Gerald Farrell³, Jinhui Yuan⁴

, Chongxiu Yu⁴, Jie Zeng⁵, Gui Yun Tian⁶ and Yong Qing Fu²

¹ Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China

² Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK

³ Photonics Research Centre, Dublin Institute of Technology, Dublin 8, Ireland

⁴ State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China

⁵ State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

⁶ School of Electrical, Electronic and Computer Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK

^† These authors contributed equally to this work.

Sensors 2017, 17(6), 1415; https://doi.org/10.3390/s17061415 - 16 Jun 2017

Cited by 20 | Viewed by 6534

Abstract

A high sensitivity refractive index sensor based on a single mode-small diameter no core fiber structure is proposed. In this structure, a small diameter no core fiber (SDNCF) used as a sensor probe, was fusion spliced to the end face of a traditional [...] Read more.

A high sensitivity refractive index sensor based on a single mode-small diameter no core fiber structure is proposed. In this structure, a small diameter no core fiber (SDNCF) used as a sensor probe, was fusion spliced to the end face of a traditional single mode fiber (SMF) and the end face of the SDNCF was coated with a thin film of gold to provide reflective light. The influence of SDNCF diameter and length on the refractive index sensitivity of the sensor has been investigated by both simulations and experiments, where results show that the diameter of SDNCF has significant influence. However, SDNCF length has limited influence on the sensitivity. Experimental results show that a sensitivity of 327 nm/RIU (refractive index unit) has been achieved for refractive indices ranging from 1.33 to 1.38, which agrees well with the simulated results with a sensitivity of 349.5 nm/RIU at refractive indices ranging from 1.33 to 1.38. 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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21 pages, 5401 KiB

Open AccessArticle

Initial Alignment for SINS Based on Pseudo-Earth Frame in Polar Regions

by Yanbin Gao, Meng Liu^*, Guangchun Li and Xingxing Guang

College of Automation, Harbin Engineering University, Harbin 150001, China

Sensors 2017, 17(6), 1416; https://doi.org/10.3390/s17061416 - 16 Jun 2017

Cited by 15 | Viewed by 4503

Abstract

An accurate initial alignment must be required for inertial navigation system (INS). The performance of initial alignment directly affects the following navigation accuracy. However, the rapid convergence of meridians and the small horizontalcomponent of rotation of Earth make the traditional alignment methods ineffective [...] Read more.

An accurate initial alignment must be required for inertial navigation system (INS). The performance of initial alignment directly affects the following navigation accuracy. However, the rapid convergence of meridians and the small horizontalcomponent of rotation of Earth make the traditional alignment methods ineffective in polar regions. In this paper, from the perspective of global inertial navigation, a novel alignment algorithm based on pseudo-Earth frame and backward process is proposed to implement the initial alignment in polar regions. Considering that an accurate coarse alignment of azimuth is difficult to obtain in polar regions, the dynamic error modeling with large azimuth misalignment angle is designed. At the end of alignment phase, the strapdown attitude matrix relative to local geographic frame is obtained without influence of position errors and cumbersome computation. As a result, it would be more convenient to access the following polar navigation system. Then, it is also expected to unify the polar alignment algorithm as much as possible, thereby further unifying the form of external reference information. Finally, semi-physical static simulation and in-motion tests with large azimuth misalignment angle assisted by unscented Kalman filter (UKF) validate the effectiveness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 1982 KiB

Open AccessArticle

Surface Acoustic Wave Sensors for Hydrogen and Deuterium Detection

by Aurelian Marcu and Cristian Viespe^*

National Institute for Laser, Plasma and Radiation Physics, Magurele 077125, Romania

Sensors 2017, 17(6), 1417; https://doi.org/10.3390/s17061417 - 16 Jun 2017

Cited by 37 | Viewed by 5925

Abstract

A delay-line-type surface acoustic wave (SAW) sensor based on a zinc oxide (ZnO) sensitive layer was developed. Two types of sensitive layers were obtained: ZnO nanowires and ZnO thin films, both deposited using laser methods (VLS-PLD and PLD, respectively) onto quartz substrates. The [...] Read more.

A delay-line-type surface acoustic wave (SAW) sensor based on a zinc oxide (ZnO) sensitive layer was developed. Two types of sensitive layers were obtained: ZnO nanowires and ZnO thin films, both deposited using laser methods (VLS-PLD and PLD, respectively) onto quartz substrates. The responses of sensors with two different nanowire lengths (300 and 600 nm) were compared with those of sensors with thin films of different thicknesses (ca. 100 and 200 nm) to different concentrations of hydrogen and deuterium. The experimental results revealed a high response at low concentrations and a rapid saturated response for nanowires, but a low response at low concentrations and a linear response to much higher gas concentrations for the thin-film-based SAW sensors. Full article

(This article belongs to the Special Issue Acoustic Wave Resonator-Based Sensors)

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25 pages, 10744 KiB

Open AccessArticle

Unequal Probability Marking Approach to Enhance Security of Traceback Scheme in Tree-Based WSNs

by Changqin Huang¹, Ming Ma^2,3, Xiao Liu^2,*, Anfeng Liu²

and Zhengbang Zuo⁴

¹ School of Information Technology in Education, South China Normal University, Guangzhou 510631, China

² School of Information Science and Engineering, Central South University, Changsha 410083, China

³ Department of Computer Science, Stony Brook University, Stony Brook, NY 11794, USA

⁴ The affiliated middle school, Hunan Normal University, Changsha 410012, China

Sensors 2017, 17(6), 1418; https://doi.org/10.3390/s17061418 - 17 Jun 2017

Cited by 4 | Viewed by 4304

Abstract

Fog (from core to edge) computing is a newly emerging computing platform, which utilizes a large number of network devices at the edge of a network to provide ubiquitous computing, thus having great development potential. However, the issue of security poses an important [...] Read more.

Fog (from core to edge) computing is a newly emerging computing platform, which utilizes a large number of network devices at the edge of a network to provide ubiquitous computing, thus having great development potential. However, the issue of security poses an important challenge for fog computing. In particular, the Internet of Things (IoT) that constitutes the fog computing platform is crucial for preserving the security of a huge number of wireless sensors, which are vulnerable to attack. In this paper, a new unequal probability marking approach is proposed to enhance the security performance of logging and migration traceback (LM) schemes in tree-based wireless sensor networks (WSNs). The main contribution of this paper is to overcome the deficiency of the LM scheme that has a higher network lifetime and large storage space. In the unequal probability marking logging and migration (UPLM) scheme of this paper, different marking probabilities are adopted for different nodes according to their distances to the sink. A large marking probability is assigned to nodes in remote areas (areas at a long distance from the sink), while a small marking probability is applied to nodes in nearby area (areas at a short distance from the sink). This reduces the consumption of storage and energy in addition to enhancing the security performance, lifetime, and storage capacity. Marking information will be migrated to nodes at a longer distance from the sink for increasing the amount of stored marking information, thus enhancing the security performance in the process of migration. The experimental simulation shows that for general tree-based WSNs, the UPLM scheme proposed in this paper can store 1.12–1.28 times the amount of stored marking information that the equal probability marking approach achieves, and has 1.15–1.26 times the storage utilization efficiency compared with other schemes. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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21 pages, 4375 KiB

Open AccessArticle

3D Imaging Millimeter Wave Circular Synthetic Aperture Radar

by Renyuan Zhang

and Siyang Cao^*

Department of Electrical and Computer Engineering, University of Arizona, Tucson, AZ 85721, USA

Sensors 2017, 17(6), 1419; https://doi.org/10.3390/s17061419 - 17 Jun 2017

Cited by 16 | Viewed by 9130

Abstract

In this paper, a new millimeter wave 3D imaging radar is proposed. The user just needs to move the radar along a circular track, and high resolution 3D imaging can be generated. The proposed radar uses the movement of itself to synthesize a [...] Read more.

In this paper, a new millimeter wave 3D imaging radar is proposed. The user just needs to move the radar along a circular track, and high resolution 3D imaging can be generated. The proposed radar uses the movement of itself to synthesize a large aperture in both the azimuth and elevation directions. It can utilize inverse Radon transform to resolve 3D imaging. To improve the sensing result, the compressed sensing approach is further investigated. The simulation and experimental result further illustrated the design. Because a single transceiver circuit is needed, a light, affordable and high resolution 3D mmWave imaging radar is illustrated in the paper. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 15358 KiB

Open AccessArticle

Fabrication of Circuits on Flexible Substrates Using Conductive SU-8 for Sensing Applications

by Carlos D. Gerardo^1,*

, Edmond Cretu¹ and Robert Rohling^1,2

¹ Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada

² Department of Mechanical Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada

Sensors 2017, 17(6), 1420; https://doi.org/10.3390/s17061420 - 17 Jun 2017

Cited by 19 | Viewed by 6812

Abstract

This article describes a new low-cost rapid microfabrication technology for high-density interconnects and passive devices on flexible substrates for sensing applications. Silver nanoparticles with an average size of 80 nm were used to create a conductive SU-8 mixture with a concentration of wt [...] Read more.

This article describes a new low-cost rapid microfabrication technology for high-density interconnects and passive devices on flexible substrates for sensing applications. Silver nanoparticles with an average size of 80 nm were used to create a conductive SU-8 mixture with a concentration of wt 25%. The patterned structures after hard baking have a sheet resistance of 11.17

Ω

/□. This conductive SU-8 was used to pattern planar inductors, capacitors and interconnection lines on flexible Kapton film. The conductive SU-8 structures were used as a seed layer for a subsequent electroplating process to increase the conductivity of the devices. Examples of inductors, resistor-capacitor (RC) and inductor-capacitor (LC) circuits, interconnection lines and a near-field communication (NFC) antenna are presented as a demonstration. As an example of high-resolution miniaturization, we fabricated microinductors having line widths of 5

μ

m. Mechanical bending tests were successful down to a 5 mm radius. To the best of the authors’ knowledge, this is the first report of conductive SU-8 used to fabricate such planar devices and the first on flexible substrates. This is a proof of concept that this fabrication approach can be used as an alternative for microfabrication of planar passive devices on flexible substrates. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 1929 KiB

Open AccessArticle

A Source Anonymity-Based Lightweight Secure AODV Protocol for Fog-Based MANET

by Weidong Fang^1,2, Wuxiong Zhang^1,2,*, Jinchao Xiao³, Yang Yang^1,2 and Wei Chen⁴

¹ Key Laboratory of Wireless Sensor Network & Communication, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Shanghai 201800, China

² Shanghai Research Center for Wireless Communication, Shanghai 201210, China

³ Guangzhou Shenyang Institute of Automation, Chinese Academy of Sciences, Guangzhou 511458, China

⁴ School of Computer Science and Technology, China University of Mining and Technology, Xuzhou 221116, China

Sensors 2017, 17(6), 1421; https://doi.org/10.3390/s17061421 - 17 Jun 2017

Cited by 28 | Viewed by 5677

Abstract

Fog-based MANET (Mobile Ad hoc networks) is a novel paradigm of a mobile ad hoc network with the advantages of both mobility and fog computing. Meanwhile, as traditional routing protocol, ad hoc on-demand distance vector (AODV) routing protocol has been applied widely in [...] Read more.

Fog-based MANET (Mobile Ad hoc networks) is a novel paradigm of a mobile ad hoc network with the advantages of both mobility and fog computing. Meanwhile, as traditional routing protocol, ad hoc on-demand distance vector (AODV) routing protocol has been applied widely in fog-based MANET. Currently, how to improve the transmission performance and enhance security are the two major aspects in AODV’s research field. However, the researches on joint energy efficiency and security seem to be seldom considered. In this paper, we propose a source anonymity-based lightweight secure AODV (SAL-SAODV) routing protocol to meet the above requirements. In SAL-SAODV protocol, source anonymous and secure transmitting schemes are proposed and applied. The scheme involves the following three parts: the source anonymity algorithm is employed to achieve the source node, without being tracked and located; the improved secure scheme based on the polynomial of CRC-4 is applied to substitute the RSA digital signature of SAODV and guarantee the data integrity, in addition to reducing the computation and energy consumption; the random delayed transmitting scheme (RDTM) is implemented to separate the check code and transmitted data, and achieve tamper-proof results. The simulation results show that the comprehensive performance of the proposed SAL-SAODV is a trade-off of the transmission performance, energy efficiency, and security, and better than AODV and SAODV. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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16 pages, 1501 KiB

Open AccessArticle

Graph-Based Cooperative Localization Using Symmetric Measurement Equations

by Dhiraj Gulati¹, Feihu Zhang^2,*

, Daniel Clarke³ and Alois Knoll¹

¹ Robotics and Embedded Systems, Technische Universität München, Boltzmannstraße 3, 85748 Garching bei München, Germany

² School of Marine Science and Technology, Northwestern Polytechnical University, 710072 Xi’an, China

³ Cogsense Technologies Limited, Berkshire RG14 1QL, UK

Sensors 2017, 17(6), 1422; https://doi.org/10.3390/s17061422 - 17 Jun 2017

Cited by 10 | Viewed by 5820

Abstract

Precise localization is a key requirement for the success of highly assisted or autonomous vehicles. The diminishing cost of hardware has resulted in a proliferation of the number of sensors in the environment. Cooperative localization (CL) presents itself as a feasible and effective [...] Read more.

Precise localization is a key requirement for the success of highly assisted or autonomous vehicles. The diminishing cost of hardware has resulted in a proliferation of the number of sensors in the environment. Cooperative localization (CL) presents itself as a feasible and effective solution for localizing the ego-vehicle and its neighboring vehicles. However, one of the major challenges to fully realize the effective use of infrastructure sensors for jointly estimating the state of a vehicle in cooperative vehicle-infrastructure localization is an effective data association. In this paper, we propose a method which implements symmetric measurement equations within factor graphs in order to overcome the data association challenge with a reduced bandwidth overhead. Simulated results demonstrate the benefits of the proposed approach in comparison with our previously proposed approach of topology factors. Full article

(This article belongs to the Special Issue Sensors, Wireless Connectivity and Systems for Autonomous Vehicles and Smart Mobility)

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22 pages, 1593 KiB

Open AccessArticle

A Hybrid Scheme for Fine-Grained Search and Access Authorization in Fog Computing Environment

by Min Xiao¹, Jing Zhou², Xuejiao Liu^3,* and Mingda Jiang²

¹ School of Cyber Security and Information Law, Chongqing University of Posts and Telecommunicaitons, Chongqing 400065, China

² College of Computer Science and Technology, Chongqing University of Posts and Telecommunicaitons, Chongqing 400065, China

³ Institute of Service Engineering, Hangzhou Normal University, Hangzhou 311121, China

Sensors 2017, 17(6), 1423; https://doi.org/10.3390/s17061423 - 17 Jun 2017

Cited by 35 | Viewed by 5982

Abstract

In the fog computing environment, the encrypted sensitive data may be transferred to multiple fog nodes on the edge of a network for low latency; thus, fog nodes need to implement a search over encrypted data as a cloud server. Since the fog [...] Read more.

In the fog computing environment, the encrypted sensitive data may be transferred to multiple fog nodes on the edge of a network for low latency; thus, fog nodes need to implement a search over encrypted data as a cloud server. Since the fog nodes tend to provide service for IoT applications often running on resource-constrained end devices, it is necessary to design lightweight solutions. At present, there is little research on this issue. In this paper, we propose a fine-grained owner-forced data search and access authorization scheme spanning user-fog-cloud for resource constrained end users. Compared to existing schemes only supporting either index encryption with search ability or data encryption with fine-grained access control ability, the proposed hybrid scheme supports both abilities simultaneously, and index ciphertext and data ciphertext are constructed based on a single ciphertext-policy attribute based encryption (CP-ABE) primitive and share the same key pair, thus the data access efficiency is significantly improved and the cost of key management is greatly reduced. Moreover, in the proposed scheme, the resource constrained end devices are allowed to rapidly assemble ciphertexts online and securely outsource most of decryption task to fog nodes, and mediated encryption mechanism is also adopted to achieve instantaneous user revocation instead of re-encrypting ciphertexts with many copies in many fog nodes. The security and the performance analysis show that our scheme is suitable for a fog computing environment. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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16 pages, 4375 KiB

Open AccessArticle

Coarse Alignment Technology on Moving base for SINS Based on the Improved Quaternion Filter Algorithm

by Tao Zhang^1,2,*

, Yongyun Zhu^1,2, Feng Zhou^1,2, Yaxiong Yan^1,2 and Jinwu Tong^1,2

¹ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

² Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Nanjing 210096, China

Sensors 2017, 17(6), 1424; https://doi.org/10.3390/s17061424 - 17 Jun 2017

Cited by 15 | Viewed by 4714

Abstract

Initial alignment of the strapdown inertial navigation system (SINS) is intended to determine the initial attitude matrix in a short time with certain accuracy. The alignment accuracy of the quaternion filter algorithm is remarkable, but the convergence rate is slow. To solve this [...] Read more.

Initial alignment of the strapdown inertial navigation system (SINS) is intended to determine the initial attitude matrix in a short time with certain accuracy. The alignment accuracy of the quaternion filter algorithm is remarkable, but the convergence rate is slow. To solve this problem, this paper proposes an improved quaternion filter algorithm for faster initial alignment based on the error model of the quaternion filter algorithm. The improved quaternion filter algorithm constructs the K matrix based on the principle of optimal quaternion algorithm, and rebuilds the measurement model by containing acceleration and velocity errors to make the convergence rate faster. A doppler velocity log (DVL) provides the reference velocity for the improved quaternion filter alignment algorithm. In order to demonstrate the performance of the improved quaternion filter algorithm in the field, a turntable experiment and a vehicle test are carried out. The results of the experiments show that the convergence rate of the proposed improved quaternion filter is faster than that of the tradition quaternion filter algorithm. In addition, the improved quaternion filter algorithm also demonstrates advantages in terms of correctness, effectiveness, and practicability. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 8071 KiB

Open AccessArticle

Novel Descattering Approach for Stereo Vision in Dense Suspended Scatterer Environments

by Chanh D. Tr. Nguyen¹, Jihyuk Park¹, Kyeong-Yong Cho², Kyung-Soo Kim^1,* and Soohyun Kim^1,*

¹ Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea;

² Unmanned Safety Robot Research Center, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea;

Sensors 2017, 17(6), 1425; https://doi.org/10.3390/s17061425 - 17 Jun 2017

Cited by 3 | Viewed by 5146

Abstract

In this paper, we propose a model-based scattering removal method for stereo vision for robot manipulation in indoor scattering media where the commonly used ranging sensors are unable to work. Stereo vision is an inherently ill-posed and challenging problem. It is even more [...] Read more.

In this paper, we propose a model-based scattering removal method for stereo vision for robot manipulation in indoor scattering media where the commonly used ranging sensors are unable to work. Stereo vision is an inherently ill-posed and challenging problem. It is even more difficult in the case of images of dense fog or dense steam scenes illuminated by active light sources. Images taken in such environments suffer attenuation of object radiance and scattering of the active light sources. To solve this problem, we first derive the imaging model for images taken in a dense scattering medium with a single active illumination close to the cameras. Based on this physical model, the non-uniform backscattering signal is efficiently removed. The descattered images are then utilized as the input images of stereo vision. The performance of the method is evaluated based on the quality of the depth map from stereo vision. We also demonstrate the effectiveness of the proposed method by carrying out the real robot manipulation task. Full article

(This article belongs to the Section Physical Sensors)

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7 pages, 1777 KiB

Open AccessArticle

n⁺ GaAs/AuGeNi-Au Thermocouple-Type RF MEMS Power Sensors Based on Dual Thermal Flow Paths in GaAs MMIC

by Zhiqiang Zhang^* and Xiaoping Liao

Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096, China

Sensors 2017, 17(6), 1426; https://doi.org/10.3390/s17061426 - 17 Jun 2017

Cited by 7 | Viewed by 6083

Abstract

To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n⁺ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage [...] Read more.

To achieve radio frequency (RF) power detection, gain control, and circuit protection, this paper presents n⁺ GaAs/AuGeNi-Au thermocouple-type RF microelectromechanical system (MEMS) power sensors based on dual thermal flow paths. The sensors utilize a conversion principle of RF power-heat-voltage, where a thermovoltage is obtained as the RF power changes. To improve the heat transfer efficiency and the sensitivity, structures of two heat conduction paths are designed: one in which a thermal slug of Au is placed between two load resistors and hot junctions of the thermocouples, and one in which a back cavity is fabricated by the MEMS technology to form a substrate membrane underneath the resistors and the hot junctions. The improved sensors were fabricated by a GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that these sensors have reflection losses of less than −17 dB up to 12 GHz. At 1, 5, and 10 GHz, measured sensitivities are about 63.45, 53.97, and 44.14 µV/mW for the sensor with the thermal slug, and about 111.03, 94.79, and 79.04 µV/mW for the sensor with the thermal slug and the back cavity, respectively. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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20 pages, 3192 KiB

Open AccessArticle

Spatial Indexing for Data Searching in Mobile Sensing Environments

by Yuchao Zhou¹, Suparna De^1,*

, Wei Wang², Klaus Moessner¹

and Marimuthu S. Palaniswami³

¹ Institute for Communication Systems (ICS), University of Surrey, Guildford GU2 7XH, UK

² Department of Computer Science and Software Engineering, Xi’an Jiaotong-Liverpool University, Ren’ai Road Dushu Lake Higher Education Town SIP, Suzhou 215123, China

³ Department of Electrical and Electronic Engineering, University of Melbourne, Parkville, VIC 3010, Australia

Sensors 2017, 17(6), 1427; https://doi.org/10.3390/s17061427 - 18 Jun 2017

Cited by 16 | Viewed by 7425

Abstract

Data searching and retrieval is one of the fundamental functionalities in many Web of Things applications, which need to collect, process and analyze huge amounts of sensor stream data. The problem in fact has been well studied for data generated by sensors that [...] Read more.

Data searching and retrieval is one of the fundamental functionalities in many Web of Things applications, which need to collect, process and analyze huge amounts of sensor stream data. The problem in fact has been well studied for data generated by sensors that are installed at fixed locations; however, challenges emerge along with the popularity of opportunistic sensing applications in which mobile sensors keep reporting observation and measurement data at variable intervals and changing geographical locations. To address these challenges, we develop the Geohash-Grid Tree, a spatial indexing technique specially designed for searching data integrated from heterogeneous sources in a mobile sensing environment. Results of the experiments on a real-world dataset collected from the SmartSantander smart city testbed show that the index structure allows efficient search based on spatial distance, range and time windows in a large time series database. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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36 pages, 6569 KiB

Open AccessArticle

Intercomparison of Unmanned Aerial Vehicle and Ground-Based Narrow Band Spectrometers Applied to Crop Trait Monitoring in Organic Potato Production

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(6), 1428; https://doi.org/10.3390/s17061428 - 18 Jun 2017

Cited by 54 | Viewed by 15880 | Correction

Abstract

Vegetation properties can be estimated using optical sensors, acquiring data on board of different platforms. For instance, ground-based and Unmanned Aerial Vehicle (UAV)-borne spectrometers can measure reflectance in narrow spectral bands, while different modelling approaches, like regressions fitted to vegetation indices, can relate [...] Read more.

Vegetation properties can be estimated using optical sensors, acquiring data on board of different platforms. For instance, ground-based and Unmanned Aerial Vehicle (UAV)-borne spectrometers can measure reflectance in narrow spectral bands, while different modelling approaches, like regressions fitted to vegetation indices, can relate spectra with crop traits. Although monitoring frameworks using multiple sensors can be more flexible, they may result in higher inaccuracy due to differences related to the sensors characteristics, which can affect information sampling. Also organic production systems can benefit from continuous monitoring focusing on crop management and stress detection, but few studies have evaluated applications with this objective. In this study, ground-based and UAV spectrometers were compared in the context of organic potato cultivation. Relatively accurate estimates were obtained for leaf chlorophyll (RMSE = 6.07 µg·cm⁻²), leaf area index (RMSE = 0.67 m²·m⁻²), canopy chlorophyll (RMSE = 0.24 g·m⁻²) and ground cover (RMSE = 5.5%) using five UAV-based data acquisitions, from 43 to 99 days after planting. These retrievals are slightly better than those derived from ground-based measurements (RMSE = 7.25 µg·cm⁻², 0.85 m²·m⁻², 0.28 g·m⁻² and 6.8%, respectively), for the same period. Excluding observations corresponding to the first acquisition increased retrieval accuracy and made outputs more comparable between sensors, due to relatively low vegetation cover on this date. Intercomparison of vegetation indices indicated that indices based on the contrast between spectral bands in the visible and near-infrared, like OSAVI, MCARI2 and CI_g provided, at certain extent, robust outputs that could be transferred between sensors. Information sampling at plot level by both sensing solutions resulted in comparable discriminative potential concerning advanced stages of late blight incidence. These results indicate that optical sensors, and their integration, have great potential for monitoring this specific organic cropping system. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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9 pages, 2689 KiB

Open AccessArticle

Cataract Surgery Performed by High Frequency LDV Z8 Femtosecond Laser: Safety, Efficacy, and Its Physical Properties

by Bojan Pajic^1,2,3,4,*

, Zeljka Cvejic² and Brigitte Pajic-Eggspuehler¹

¹ Eye Clinic Orasis, Swiss Eye Research Foundation, 5734 Reinach AG, Switzerland

² Department of Physics, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 4, 21000 Novi Sad, Serbia

³ Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, Rue Gabrielle-Perret-Gentil 4, 1205 Genève, Switzerland

⁴ Faculty of Medicine of the Military Medical academy, University of Defense, 11000 Belgrade, Serbia

Sensors 2017, 17(6), 1429; https://doi.org/10.3390/s17061429 - 18 Jun 2017

Cited by 46 | Viewed by 6656

Abstract

Background: The aim of our study was to investigate the safety and efficacy of the LDV Z8 femtosecond laser in cataract surgery compared to the conventional procedure. Methods: This prospective study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, [...] Read more.

Background: The aim of our study was to investigate the safety and efficacy of the LDV Z8 femtosecond laser in cataract surgery compared to the conventional procedure. Methods: This prospective study was performed at the Swiss Eye Research Foundation, Eye Clinic ORASIS, Reinach, Switzerland. The study included 130 eyes from 130 patients: 68 treated with femtosecond laser-assisted cataract surgery (FLACS) using the FEMTO LDV Z8 and 62 treated with conventional phacoemulsification. Capsulotomy and lens fragmentation in the laser group were performed with the FEMTO LDV Z8 femtosecond laser system, which employs a new, low-energy, high repetition rate laser process for cataract surgery. In the conventional group, the capsulotomy was performed by a cystotome, and lens fragmentation was achieved by the stop-and-chop. Results: Ease of phacoemulsification (on a 4-point scale), the completeness of capsulotomy (on a 10-point scale), effective phacoemulsification time (seconds), uncorrected distance visual acuity (UCVA), best spectacle-corrected distance visual acuity (BSCVA), spherical equivalent (SE), and safety of the procedure were evaluated. The total follow-up time was three months. Conclusions: FLACS with the FEMTO LDV Z8 system was characterized by complete and reproducible capsulotomy and highly effective lens fragmentation. Postoperative visual outcomes were excellent, and the safety of the procedure was optimal. Full article

(This article belongs to the Special Issue Optical Methods in Sensing and Imaging for Medical and Biological Applications)

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23 pages, 1961 KiB

Open AccessReview

Wuhan Ionospheric Oblique Backscattering Sounding System and Its Applications—A Review

by Shuzhu Shi¹

, Guobin Yang^2,*, Chunhua Jiang², Yuannong Zhang² and Zhengyu Zhao²

¹ School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China

² School of Electronic Information, Wuhan University, Wuhan 430072, China

Sensors 2017, 17(6), 1430; https://doi.org/10.3390/s17061430 - 18 Jun 2017

Cited by 21 | Viewed by 6352

Abstract

For decades, high-frequency (HF) radar has played an important role in sensing the Earth’s environment. Advances in radar technology are providing opportunities to significantly improve the performance of HF radar, and to introduce more applications. This paper presents a low-power, small-size, and multifunctional [...] Read more.

For decades, high-frequency (HF) radar has played an important role in sensing the Earth’s environment. Advances in radar technology are providing opportunities to significantly improve the performance of HF radar, and to introduce more applications. This paper presents a low-power, small-size, and multifunctional HF radar developed by the Ionospheric Laboratory of Wuhan University, referred to as the Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS). Progress in the development of this radar is described in detail, including the basic principles of operation, the system configuration, the sounding waveforms, and the signal and data processing methods. Furthermore, its various remote sensing applications are briefly reviewed to show the good performance of this radar. Finally, some suggested solutions are given for further improvement of its performance. Full article

(This article belongs to the Section Remote Sensors)

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19 pages, 5572 KiB

Open AccessArticle

A Cost-Effective Vehicle Localization Solution Using an Interacting Multiple Model−Unscented Kalman Filters (IMM-UKF) Algorithm and Grey Neural Network

by Qimin Xu¹, Xu Li^1,* and Ching-Yao Chan²

¹ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

² California Partners for Advanced Transportation Technology (PATH), University of California, Berkeley, CA 94720, USA

Sensors 2017, 17(6), 1431; https://doi.org/10.3390/s17061431 - 18 Jun 2017

Cited by 50 | Viewed by 6992

Abstract

In this paper, we propose a cost-effective localization solution for land vehicles, which can simultaneously adapt to the uncertain noise of inertial sensors and bridge Global Positioning System (GPS) outages. First, three Unscented Kalman filters (UKFs) with different noise covariances are introduced into [...] Read more.

In this paper, we propose a cost-effective localization solution for land vehicles, which can simultaneously adapt to the uncertain noise of inertial sensors and bridge Global Positioning System (GPS) outages. First, three Unscented Kalman filters (UKFs) with different noise covariances are introduced into the framework of Interacting Multiple Model (IMM) algorithm to form the proposed IMM-based UKF, termed as IMM-UKF. The IMM algorithm can provide a soft switching among the three UKFs and therefore adapt to different noise characteristics. Further, two IMM-UKFs are executed in parallel when GPS is available. One fuses the information of low-cost GPS, in-vehicle sensors, and micro electromechanical system (MEMS)-based reduced inertial sensor systems (RISS), while the other fuses only in-vehicle sensors and MEMS-RISS. The differences between the state vectors of the two IMM-UKFs are considered as training data of a Grey Neural Network (GNN) module, which is known for its high prediction accuracy with a limited amount of samples. The GNN module can predict and compensate position errors when GPS signals are blocked. To verify the feasibility and effectiveness of the proposed solution, road-test experiments with various driving scenarios were performed. The experimental results indicate that the proposed solution outperforms all the compared methods. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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12 pages, 3638 KiB

Open AccessArticle

The Ship Movement Trajectory Prediction Algorithm Using Navigational Data Fusion

by Piotr Borkowski

Maritime University of Szczecin, Wały Chrobrego 1, Szczecin 70500, Poland

Sensors 2017, 17(6), 1432; https://doi.org/10.3390/s17061432 - 20 Jun 2017

Cited by 85 | Viewed by 9847

Abstract

It is essential for the marine navigator conducting maneuvers of his ship at sea to know future positions of himself and target ships in a specific time span to effectively solve collision situations. This article presents an algorithm of ship movement trajectory prediction, [...] Read more.

It is essential for the marine navigator conducting maneuvers of his ship at sea to know future positions of himself and target ships in a specific time span to effectively solve collision situations. This article presents an algorithm of ship movement trajectory prediction, which, through data fusion, takes into account measurements of the ship’s current position from a number of doubled autonomous devices. This increases the reliability and accuracy of prediction. The algorithm has been implemented in NAVDEC, a navigation decision support system and practically used on board ships. Full article

(This article belongs to the Special Issue Soft Sensors and Intelligent Algorithms for Data Fusion)

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14 pages, 819 KiB

Open AccessArticle

Two Novel Two-Stage Direction of Arrival Estimation Algorithms for Two-Dimensional Mixed Noncircular and Circular Sources

by Heping Shi¹, Wen Leng², Zhiwei Guan^1,* and Tongzhi Jin²

¹ School of Automotion and Transportation, Tianjin University of Technology and Education, Tianjin 300222, China

² School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(6), 1433; https://doi.org/10.3390/s17061433 - 18 Jun 2017

Cited by 7 | Viewed by 4808

Abstract

This paper addresses the two-dimensional (2D) direction-of-arrival (DOA) estimation problem with two novel methods for mixed noncircular and circular signals. The first proposed method is named the two-stage direction-of-arrival matrix (TSDOAM) method, and the other is called the two-stage rank reduction (TSRARE) method. [...] Read more.

This paper addresses the two-dimensional (2D) direction-of-arrival (DOA) estimation problem with two novel methods for mixed noncircular and circular signals. The first proposed method is named the two-stage direction-of-arrival matrix (TSDOAM) method, and the other is called the two-stage rank reduction (TSRARE) method. The proposed methods utilize both the circularity and the direction-of-arrival differences between the noncircular and circular sources to estimate the 2D directions-of-arrival (DOAs). The maximum detectable 2D angle parameters of the TSDOAM and TSRARE methods are twice those of the existing methods. Moreover, the TSRARE method can detect more incident signals than the TSDOAM method due to the array aperture of two parallel uniform linear arrays (ULAs) being fully utilized. Simulation results show that compared to the existing methods for the small angle separation of 2D directions-of-arrival, the two proposed methods perform well in terms of the signal-to-noise ratio (SNR) and snapshots. 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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19 pages, 1499 KiB

Open AccessArticle

A Novel Extreme Learning Machine Classification Model for e-Nose Application Based on the Multiple Kernel Approach

by Yulin Jian¹, Daoyu Huang¹, Jia Yan^1,2,*, Kun Lu³, Ying Huang¹, Tailai Wen¹, Tanyue Zeng¹, Shijie Zhong¹ and Qilong Xie¹

¹ College of Electronic and Information Engineering, Southwest University, Chongqing 400715, China

² Chongqing Key Laboratory of Nonlinear Circuits and Intelligent Information Processing, Chongqing 400715, China

³ High Tech Department, China International Engineering Consulting Corporation, Beijing 100048, China

Sensors 2017, 17(6), 1434; https://doi.org/10.3390/s17061434 - 19 Jun 2017

Cited by 29 | Viewed by 6823

Abstract

A novel classification model, named the quantum-behaved particle swarm optimization (QPSO)-based weighted multiple kernel extreme learning machine (QWMK-ELM), is proposed in this paper. Experimental validation is carried out with two different electronic nose (e-nose) datasets. Being different from the existing multiple kernel extreme [...] Read more.

A novel classification model, named the quantum-behaved particle swarm optimization (QPSO)-based weighted multiple kernel extreme learning machine (QWMK-ELM), is proposed in this paper. Experimental validation is carried out with two different electronic nose (e-nose) datasets. Being different from the existing multiple kernel extreme learning machine (MK-ELM) algorithms, the combination coefficients of base kernels are regarded as external parameters of single-hidden layer feedforward neural networks (SLFNs). The combination coefficients of base kernels, the model parameters of each base kernel, and the regularization parameter are optimized by QPSO simultaneously before implementing the kernel extreme learning machine (KELM) with the composite kernel function. Four types of common single kernel functions (Gaussian kernel, polynomial kernel, sigmoid kernel, and wavelet kernel) are utilized to constitute different composite kernel functions. Moreover, the method is also compared with other existing classification methods: extreme learning machine (ELM), kernel extreme learning machine (KELM), k-nearest neighbors (KNN), support vector machine (SVM), multi-layer perceptron (MLP), radical basis function neural network (RBFNN), and probabilistic neural network (PNN). The results have demonstrated that the proposed QWMK-ELM outperforms the aforementioned methods, not only in precision, but also in efficiency for gas classification. Full article

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

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7 pages, 1792 KiB

Open AccessArticle

Design and Performance of a Portable and Multichannel SPR Device

by Xiao-ling Zhang^1,†, Yan Liu^2,†, Ting Fan^1,2, Ning Hu^1,2,*

, Zhong Yang³, Xi Chen¹, Zhen-yu Wang⁴ and Jun Yang^1,*

¹ Key Laboratory of Biorheological Science and Technology, Chongqing University, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400030, China

² Chongqing Engineering Research Center of Medical Electronics Technology, Chongqing University, Bioengineering College, Chongqing University, Chongqing 400030, China

³ Department of Laboratory Medicine, Southwest Hospital, Third Military Medical University, Chongqing 400038, China

⁴ Department of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, China

^† These authors contributed equally in this study.

Sensors 2017, 17(6), 1435; https://doi.org/10.3390/s17061435 - 19 Jun 2017

Cited by 18 | Viewed by 8818

Abstract

A portable multichannel surface plasmon resonance (SPR) biosensor device is presented in this study. As an optical biosensor device, the core component of its light path is a semi-cylindrical prism, which is used as the coupling unit for the excitation of the SPR [...] Read more.

A portable multichannel surface plasmon resonance (SPR) biosensor device is presented in this study. As an optical biosensor device, the core component of its light path is a semi-cylindrical prism, which is used as the coupling unit for the excitation of the SPR phenomena. Based on this prism, a wedge-shaped incident light beam including a continuous angle range (10°) is chosen to replace the commonly-used parallel light beam in traditional SPR devices, in which the incident angle is adjusted by a sophisticated mechanical system. Thus, complicated, cumbersome, and costly mechanical structures can be avoided in this design. Furthermore, the selection of a small and high-stability semiconductor laser and matrix CCD detector as well as a microfluidic system aids in the realization of a miniaturized and multichannel device. Several different samples were used to test the performance of this new device. For ethanol with different concentrations, the sensing response was of good linear relativity with the concentration (Y = 3.17143X + 2.81518, R² = 0.97661). Mouse IgG and goat anti-mouse IgG were used as biological samples for immunological analysis, and BSA as the control group. Good specific recognition between mouse IgG and goat anti-mouse IgG has been achieved. The detection limit of antibody to antigen coated on the sensing surface was about 25 mg/L without surface modification. Full article

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

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16 pages, 2818 KiB

Open AccessArticle

Active2Gether: A Personalized m-Health Intervention to Encourage Physical Activity

by Michel C. A. Klein, Adnan Manzoor

and Julia S. Mollee^*

Department of Computer Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands

Sensors 2017, 17(6), 1436; https://doi.org/10.3390/s17061436 - 19 Jun 2017

Cited by 34 | Viewed by 8627

Abstract

Lack of physical activity is an increasingly important health risk. Modern mobile technology, such as smartphones and digital measurement devices, provides new opportunities to tackle physical inactivity. This paper describes the design of a system that aims to encourage young adults to be [...] Read more.

Lack of physical activity is an increasingly important health risk. Modern mobile technology, such as smartphones and digital measurement devices, provides new opportunities to tackle physical inactivity. This paper describes the design of a system that aims to encourage young adults to be more physically active. The system monitors the user’s behavior, uses social comparison and provides tailored and personalized feedback based on intelligent reasoning mechanisms. As the name suggests, social processes play an important role in the Active2Gether system. The design choices and functioning of the system are described in detail. Based on the experiences with the development and deployment of the system, a number of lessons learnt are provided and suggestions are proposed for improvements in future developments. Full article

(This article belongs to the Special Issue Smart Sensing Technologies for Personalised Coaching)

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17 pages, 3056 KiB

Open AccessArticle

Localization Framework for Real-Time UAV Autonomous Landing: An On-Ground Deployed Visual Approach

by Weiwei Kong^1,2, Tianjiang Hu^1,*, Daibing Zhang¹, Lincheng Shen¹ and Jianwei Zhang³

¹ College of Mechatronics and Automation, National University of Defense Technology, Changsha 410073, China

² Naval Academy of Armament, Beijing 100161, China

³ Institute of Technical Aspects of Multimodal Systems(TAMS), Department of Computer Science, University of Hamburg, 22527 Hamburg, Germany

Sensors 2017, 17(6), 1437; https://doi.org/10.3390/s17061437 - 19 Jun 2017

Cited by 32 | Viewed by 9195

Abstract

[-5]One of the greatest challenges for fixed-wing unmanned aircraft vehicles (UAVs) is safe landing. Hereafter, an on-ground deployed visual approach is developed in this paper. This approach is definitely suitable for landing within the global navigation satellite system (GNSS)-denied environments. As for applications, [...] Read more.

[-5]One of the greatest challenges for fixed-wing unmanned aircraft vehicles (UAVs) is safe landing. Hereafter, an on-ground deployed visual approach is developed in this paper. This approach is definitely suitable for landing within the global navigation satellite system (GNSS)-denied environments. As for applications, the deployed guidance system makes full use of the ground computing resource and feedbacks the aircraft’s real-time localization to its on-board autopilot. Under such circumstances, a separate long baseline stereo architecture is proposed to possess an extendable baseline and wide-angle field of view (FOV) against the traditional fixed baseline schemes. Furthermore, accuracy evaluation of the new type of architecture is conducted by theoretical modeling and computational analysis. Dataset-driven experimental results demonstrate the feasibility and effectiveness of the developed approach. Full article

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

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20 pages, 2553 KiB

Open AccessArticle

A New Filtering and Smoothing Algorithm for Railway Track Surveying Based on Landmark and IMU/Odometer

by Qingan Jiang, Wenqi Wu^*, Mingming Jiang and Yun Li

Department of Automatic Control, College of Mechatronics and Automation, National University of Defense Technology, Changsha 410073, China

Sensors 2017, 17(6), 1438; https://doi.org/10.3390/s17061438 - 19 Jun 2017

Cited by 27 | Viewed by 7482

Abstract

High-accuracy railway track surveying is essential for railway construction and maintenance. The traditional approaches based on total station equipment are not efficient enough since high precision surveying frequently needs static measurements. This paper proposes a new filtering and smoothing algorithm based on the [...] Read more.

High-accuracy railway track surveying is essential for railway construction and maintenance. The traditional approaches based on total station equipment are not efficient enough since high precision surveying frequently needs static measurements. This paper proposes a new filtering and smoothing algorithm based on the IMU/odometer and landmarks integration for the railway track surveying. In order to overcome the difficulty of estimating too many error parameters with too few landmark observations, a new model with completely observable error states is established by combining error terms of the system. Based on covariance analysis, the analytical relationship between the railway track surveying accuracy requirements and equivalent gyro drifts including bias instability and random walk noise are established. Experiment results show that the accuracy of the new filtering and smoothing algorithm for railway track surveying can reach 1 mm (1σ) when using a Ring Laser Gyroscope (RLG)-based Inertial Measurement Unit (IMU) with gyro bias instability of 0.03°/h and random walk noise of 0.005 °h while control points of the track control network (CPIII) position observations are provided by the optical total station in about every 60 m interval. The proposed approach can satisfy at the same time the demands of high accuracy and work efficiency for railway track surveying. Full article

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

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13 pages, 1944 KiB

Open AccessArticle

Adhesive Defect Monitoring of Glass Fiber Epoxy Plate Using an Impedance-Based Non-Destructive Testing Method for Multiple Structures

by Wongi S. Na^1,* and Jongdae Baek²

¹ Future Strategy & Convergence Research Institute, Korea Institute of Civil Engineering & Building Technology, Gyeonggi-Do 10223, Korea

² Highway & Transportation Research Institute, Korea Institute of Civil Engineering & Building Technology, Gyeonggi-Do 10223, Korea

Sensors 2017, 17(6), 1439; https://doi.org/10.3390/s17061439 - 19 Jun 2017

Cited by 6 | Viewed by 6331

Abstract

The emergence of composite materials has revolutionized the approach to building engineering structures. With the number of applications for composites increasing every day, maintaining structural integrity is of utmost importance. For composites, adhesive bonding is usually the preferred choice over the mechanical fastening [...] Read more.

The emergence of composite materials has revolutionized the approach to building engineering structures. With the number of applications for composites increasing every day, maintaining structural integrity is of utmost importance. For composites, adhesive bonding is usually the preferred choice over the mechanical fastening method, and monitoring for delamination is an essential factor in the field of composite materials. In this study, a non-destructive method known as the electromechanical impedance method is used with an approach of monitoring multiple areas by specifying certain frequency ranges to correspond to a certain test specimen. Experiments are conducted using various numbers of stacks created by attaching glass fiber epoxy composite plates onto one another, and two different debonding damage types are introduced to evaluate the performance of the multiple monitoring electromechanical impedance method. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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16 pages, 2182 KiB

Open AccessArticle

Rapid Global Calibration Technology for Hybrid Visual Inspection System

by Tao Liu, Shibin Yin^*, Yin Guo and Jigui Zhu

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(6), 1440; https://doi.org/10.3390/s17061440 - 19 Jun 2017

Cited by 7 | Viewed by 6049

Abstract

Vision-based methods for product quality inspection are playing an increasingly important role in modern industries for their good performance and high efficiency. A hybrid visual inspection system, which consists of an industrial robot with a flexible sensor and several stationary sensors, has been [...] Read more.

Vision-based methods for product quality inspection are playing an increasingly important role in modern industries for their good performance and high efficiency. A hybrid visual inspection system, which consists of an industrial robot with a flexible sensor and several stationary sensors, has been widely applied in mass production, especially in automobile manufacturing. In this paper, a rapid global calibration method for the hybrid visual inspection system is proposed. Global calibration of a flexible sensor is performed first based on the robot kinematic. Then, with the aid of the calibrated flexible sensor, stationary sensors are calibrated globally one by one based on homography. Only a standard sphere and an auxiliary target with a 2D planar pattern are applied during the system global calibration, and the calibration process can be easily re-performed during the system’s periodical maintenance. An error compensation method is proposed for the hybrid inspection system, and the final accuracy of the hybrid system is evaluated with the deviation and correlation coefficient between the measured results of the hybrid system and Coordinate Measuring Machine (CMM). An accuracy verification experiment shows that deviation of over 95% of featured points are less than ±0.3 mm, and the correlation coefficients of over 85% of points are larger than 0.7. Full article

(This article belongs to the Special Issue Laser Sensors for Displacement, Distance, Flow, Velocity and Vibrations Measurements)

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17 pages, 3557 KiB

Open AccessArticle

Image Mosaicking Approach for a Double-Camera System in the GaoFen2 Optical Remote Sensing Satellite Based on the Big Virtual Camera

by Yufeng Cheng

, Shuying Jin^*

, Mi Wang^*, Ying Zhu

and Zhipeng Dong

State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China

Sensors 2017, 17(6), 1441; https://doi.org/10.3390/s17061441 - 20 Jun 2017

Cited by 22 | Viewed by 6133

Abstract

The linear array push broom imaging mode is widely used for high resolution optical satellites (HROS). Using double-cameras attached by a high-rigidity support along with push broom imaging is one method to enlarge the field of view while ensuring high resolution. High accuracy [...] Read more.

The linear array push broom imaging mode is widely used for high resolution optical satellites (HROS). Using double-cameras attached by a high-rigidity support along with push broom imaging is one method to enlarge the field of view while ensuring high resolution. High accuracy image mosaicking is the key factor of the geometrical quality of complete stitched satellite imagery. This paper proposes a high accuracy image mosaicking approach based on the big virtual camera (BVC) in the double-camera system on the GaoFen2 optical remote sensing satellite (GF2). A big virtual camera can be built according to the rigorous imaging model of a single camera; then, each single image strip obtained by each TDI-CCD detector can be re-projected to the virtual detector of the big virtual camera coordinate system using forward-projection and backward-projection to obtain the corresponding single virtual image. After an on-orbit calibration and relative orientation, the complete final virtual image can be obtained by stitching the single virtual images together based on their coordinate information on the big virtual detector image plane. The paper subtly uses the concept of the big virtual camera to obtain a stitched image and the corresponding high accuracy rational function model (RFM) for concurrent post processing. Experiments verified that the proposed method can achieve seamless mosaicking while maintaining the geometric accuracy. Full article

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

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13 pages, 4867 KiB

Open AccessArticle

Micro-Viscometer for Measuring Shear-Varying Blood Viscosity over a Wide-Ranging Shear Rate

by Byung Jun Kim¹, Seung Yeob Lee¹, Solkeun Jee², Arslan Atajanov² and Sung Yang^1,2,*

¹ Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea

² School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea

Sensors 2017, 17(6), 1442; https://doi.org/10.3390/s17061442 - 20 Jun 2017

Cited by 38 | Viewed by 9691

Abstract

In this study, a micro-viscometer is developed for measuring shear-varying blood viscosity over a wide-ranging shear rate. The micro-viscometer consists of 10 microfluidic channel arrays, each of which has a different micro-channel width. The proposed design enables the retrieval of 10 different shear [...] Read more.

In this study, a micro-viscometer is developed for measuring shear-varying blood viscosity over a wide-ranging shear rate. The micro-viscometer consists of 10 microfluidic channel arrays, each of which has a different micro-channel width. The proposed design enables the retrieval of 10 different shear rates from a single flow rate, thereby enabling the measurement of shear-varying blood viscosity with a fixed flow rate condition. For this purpose, an optimal design that guarantees accurate viscosity measurement is selected from a parametric study. The functionality of the micro-viscometer is verified by both numerical and experimental studies. The proposed micro-viscometer shows 6.8% (numerical) and 5.3% (experimental) in relative error when compared to the result from a standard rotational viscometer. Moreover, a reliability test is performed by repeated measurement (N = 7), and the result shows 2.69 ± 2.19% for the mean relative error. Accurate viscosity measurements are performed on blood samples with variations in the hematocrit (35%, 45%, and 55%), which significantly influences blood viscosity. Since the blood viscosity correlated with various physical parameters of the blood, the micro-viscometer is anticipated to be a significant advancement for realization of blood on a chip. Full article

(This article belongs to the Special Issue Microfluidic Sensors and Control Devices)

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16 pages, 9168 KiB

Open AccessArticle

Development of a Novel Transparent Flexible Capacitive Micromachined Ultrasonic Transducer

by Da-Chen Pang^*

and Cheng-Min Chang

Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Jian Gong Rd., Sanmin Dist., Kaohsiung 80778, Taiwan

Sensors 2017, 17(6), 1443; https://doi.org/10.3390/s17061443 - 20 Jun 2017

Cited by 38 | Viewed by 7764

Abstract

This paper presents the world’s first transparent flexible capacitive micromachined ultrasonic transducer (CMUT) that was fabricated through a roll-lamination technique. This polymer-based CMUT has advantages of transparency, flexibility, and non-contacting detection which provide unique functions in display panel applications. Comprising an indium tin [...] Read more.

This paper presents the world’s first transparent flexible capacitive micromachined ultrasonic transducer (CMUT) that was fabricated through a roll-lamination technique. This polymer-based CMUT has advantages of transparency, flexibility, and non-contacting detection which provide unique functions in display panel applications. Comprising an indium tin oxide-polyethylene terephthalate (ITO-PET) substrate, SU-8 sidewall and vibrating membranes, and silver nanowire transparent electrode, the transducer has visible-light transmittance exceeding 80% and can operate on curved surfaces with a 40 mm radius of curvature. Unlike the traditional silicon-based high temperature process, the CMUT can be fabricated on a flexible substrate at a temperature below 100 °C to reduce residual stress introduced at high temperature. The CMUT on the curved surfaces can detect a flat target and finger at distances up to 50 mm and 40 mm, respectively. The transparent flexible CMUT provides a better human-machine interface than existing touch panels because it can be integrated with a display panel for non-contacting control in a health conscious environment and the flexible feature is critical for curved display and wearable electronics. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 2187 KiB

Open AccessFeature PaperArticle

Fabrication and Characterization of Plasmonic Nanopores with Cavities in the Solid Support

by Bita Malekian¹, Kunli Xiong¹, Gustav Emilsson¹, Jenny Andersson², Cecilia Fager³, Eva Olsson³, Elin M. Larsson-Langhammer² and Andreas B. Dahlin^1,*

¹ Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden

² Insplorion AB, Sahlgrenska Science Park, Medicinaregatan 8A, 41390 Gothenburg, Sweden

³ Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden

Sensors 2017, 17(6), 1444; https://doi.org/10.3390/s17061444 - 20 Jun 2017

Cited by 15 | Viewed by 7139

Abstract

Plasmonic nanostructures are widely used for various sensing applications by monitoring changes in refractive index through optical spectroscopy or as substrates for surface enhanced Raman spectroscopy. However, in most practical situations conventional surface plasmon resonance is preferred for biomolecular interaction analysis because of [...] Read more.

Plasmonic nanostructures are widely used for various sensing applications by monitoring changes in refractive index through optical spectroscopy or as substrates for surface enhanced Raman spectroscopy. However, in most practical situations conventional surface plasmon resonance is preferred for biomolecular interaction analysis because of its high resolution in surface coverage and the simple single-material planar interface. Still, plasmonic nanostructures may find unique sensing applications, for instance when the nanoscale geometry itself is of interest. This calls for new methods to prepare nanoscale particles and cavities with controllable dimensions and curvature. In this work, we present two types of plasmonic nanopores where the solid support underneath a nanohole array has been etched, thereby creating cavities denoted as ‘nanowells’ or ‘nanocaves’ depending on the degree of anisotropy (dry or wet etch). The refractometric sensitivity is shown to be enhanced upon removing the solid support because of an increased probing volume and a shift of the asymmetric plasmonic field towards the liquid side of the finite gold film. Furthermore, the structures exhibit different spectral changes upon binding inside the cavities compared to the gold surface, which means that the structures can be used for location-specific detection. Other sensing applications are also suggested. Full article

(This article belongs to the Special Issue Micro and Nanofabrication Technologies for Biosensors)

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26 pages, 1591 KiB

Open AccessReview

Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

by Yong He^1,* and Ka-Di Zhu²

¹ School of Mathematics and Physics, Changzhou University, Changzhou 213164, China

² Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China

Sensors 2017, 17(6), 1445; https://doi.org/10.3390/s17061445 - 20 Jun 2017

Cited by 14 | Viewed by 6908

Abstract

In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the [...] Read more.

In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction. Full article

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

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14 pages, 441 KiB

Open AccessArticle

A New Privacy-Preserving Handover Authentication Scheme for Wireless Networks

by Changji Wang^1,*, Yuan Yuan² and Jiayuan Wu³

¹ School of Information Science and Technology, Guangdong University of Foreign Studies, Guangzhou 510420, China

² School of Finance, Guangdong University of Foreign Studies, Guangzhou 510420, China

³ School of Data Science and Computer, Sun Yat-sen University, Guangzhou 510420, China

Sensors 2017, 17(6), 1446; https://doi.org/10.3390/s17061446 - 20 Jun 2017

Cited by 4 | Viewed by 5089

Abstract

Handover authentication is a critical issue in wireless networks, which is being used to ensure mobile nodes wander over multiple access points securely and seamlessly. A variety of handover authentication schemes for wireless networks have been proposed in the literature. Unfortunately, existing handover [...] Read more.

Handover authentication is a critical issue in wireless networks, which is being used to ensure mobile nodes wander over multiple access points securely and seamlessly. A variety of handover authentication schemes for wireless networks have been proposed in the literature. Unfortunately, existing handover authentication schemes are vulnerable to a few security attacks, or incur high communication and computation costs. Recently, He et al. proposed a handover authentication scheme PairHand and claimed it can resist various attacks without rigorous security proofs. In this paper, we show that PairHand does not meet forward secrecy and strong anonymity. More seriously, it is vulnerable to key compromise attack, where an adversary can recover the private key of any mobile node. Then, we propose a new efficient and provably secure handover authentication scheme for wireless networks based on elliptic curve cryptography. Compared with existing schemes, our proposed scheme can resist key compromise attack, and achieves forward secrecy and strong anonymity. Moreover, it is more efficient in terms of computation and communication. Full article

(This article belongs to the Special Issue Mobile Sensing Applications)

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Graphical abstract

13 pages, 1175 KiB

Open AccessArticle

Dual-Channel Cosine Function Based ITD Estimation for Robust Speech Separation

by Xuliang Li

, Zhaogui Ding, Weifeng Li^* and Qingmin Liao

Department of Electronic Engineering/Graduate School at Shenzhen, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(6), 1447; https://doi.org/10.3390/s17061447 - 20 Jun 2017

Cited by 3 | Viewed by 5243

Abstract

In speech separation tasks, many separation methods have the limitation that the microphones are closely spaced, which means that these methods are unprevailing for phase wrap-around. In this paper, we present a novel speech separation scheme by using two microphones that does not [...] Read more.

In speech separation tasks, many separation methods have the limitation that the microphones are closely spaced, which means that these methods are unprevailing for phase wrap-around. In this paper, we present a novel speech separation scheme by using two microphones that does not have this restriction. The technique utilizes the estimation of interaural time difference (ITD) statistics and binary time-frequency mask for the separation of mixed speech sources. The novelties of the paper consist in: (1) the extended application of delay-and-sum beamforming (DSB) and cosine function for ITD calculation; and (2) the clarification of the connection between ideal binary mask and DSB amplitude ratio. Our objective quality evaluation experiments demonstrate the effectiveness of the proposed method. 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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21 pages, 5768 KiB

Open AccessArticle

On the Application of Image Processing Methods for Bubble Recognition to the Study of Subcooled Flow Boiling of Water in Rectangular Channels

by Concepción Paz^*, Marcos Conde, Jacobo Porteiro and Miguel Concheiro

School of Industrial Engineering, University of Vigo, Lagoas-Marcosende, Vigo 36310, Spain

Sensors 2017, 17(6), 1448; https://doi.org/10.3390/s17061448 - 20 Jun 2017

Cited by 7 | Viewed by 6474

Abstract

This work introduces the use of machine vision in the massive bubble recognition process, which supports the validation of boiling models involving bubble dynamics, as well as nucleation frequency, active site density and size of the bubbles. The two algorithms presented are meant [...] Read more.

This work introduces the use of machine vision in the massive bubble recognition process, which supports the validation of boiling models involving bubble dynamics, as well as nucleation frequency, active site density and size of the bubbles. The two algorithms presented are meant to be run employing quite standard images of the bubbling process, recorded in general-purpose boiling facilities. The recognition routines are easily adaptable to other facilities if a minimum number of precautions are taken in the setup and in the treatment of the information. Both the side and front projections of subcooled flow-boiling phenomenon over a plain plate are covered. Once all of the intended bubbles have been located in space and time, the proper post-process of the recorded data become capable of tracking each of the recognized bubbles, sketching their trajectories and size evolution, locating the nucleation sites, computing their diameters, and so on. After validating the algorithm’s output against the human eye and data from other researchers, machine vision systems have been demonstrated to be a very valuable option to successfully perform the recognition process, even though the optical analysis of bubbles has not been set as the main goal of the experimental facility. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 8155 KiB

Open AccessArticle

Measurement of Rayleigh Wave Beams Using Angle Beam Wedge Transducers as the Transmitter and Receiver with Consideration of Beam Spreading

by Shuzeng Zhang¹, Xiongbing Li^1,* and Hyunjo Jeong²

¹ School of Traffic and Transportation Engineering, Central South University, Changsha 410075, China

² Division of Mechanical and Automotive Engineering, Wonkwang University, Iksan 570-749, Korea

Sensors 2017, 17(6), 1449; https://doi.org/10.3390/s17061449 - 20 Jun 2017

Cited by 22 | Viewed by 8824

Abstract

A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave [...] Read more.

A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave sound source distributions are evaluated numerically. Based on the reciprocity theorem and considering the actual sound source, the Rayleigh wave beams are modeled using an area integral method. The leaky Rayleigh wave theory is introduced to investigate the reception of the Rayleigh wave using the angle beam wedge transducers, and the effects of the wave spreading in the wedge and transducer size are considered in the reception process. The effects of attenuations of the Rayleigh wave and leaky Rayleigh wave are discussed, and the received wave results with different sizes of receivers are compared. The experiments are conducted using two angle beam wedge transducers to measure the Rayleigh wave, and the measurement results are compared with the predictions using different theoretical models. It is shown that the proposed model which considers the wave spreading in both the sample and wedges can be used to interpret the measurements reasonably. Full article

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

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16 pages, 5615 KiB

Open AccessReview

Current Research in Lidar Technology Used for the Remote Sensing of Atmospheric Aerosols

by Adolfo Comerón^1,*, Constantino Muñoz-Porcar¹, Francesc Rocadenbosch^1,2, Alejandro Rodríguez-Gómez¹

and Michaël Sicard^1,2

¹ Remote Sensing Laboratory, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain

² Ciències i Tecnologies de l’Espai–Centre de Recerca de l’Aeronàutica i de l’Espai/Institut d’Estudis Espacials de Catalunya (CTE-CRAE/IEEC), Universitat Politècnica de Catalunya, 08034 Barcelona, Spain

Sensors 2017, 17(6), 1450; https://doi.org/10.3390/s17061450 - 20 Jun 2017

Cited by 78 | Viewed by 14301

Abstract

Lidars are active optical remote sensing instruments with unique capabilities for atmospheric sounding. A manifold of atmospheric variables can be profiled using different types of lidar: concentration of species, wind speed, temperature, etc. Among them, measurement of the properties of aerosol particles, whose [...] Read more.

Lidars are active optical remote sensing instruments with unique capabilities for atmospheric sounding. A manifold of atmospheric variables can be profiled using different types of lidar: concentration of species, wind speed, temperature, etc. Among them, measurement of the properties of aerosol particles, whose influence in many atmospheric processes is important but is still poorly stated, stands as one of the main fields of application of current lidar systems. This paper presents a review on fundamentals, technology, methodologies and state-of-the art of the lidar systems used to obtain aerosol information. Retrieval of structural (aerosol layers profiling), optical (backscatter and extinction coefficients) and microphysical (size, shape and type) properties requires however different levels of instrumental complexity; this general outlook is structured following a classification that attends these criteria. Thus, elastic systems (detection only of emitted frequencies), Raman systems (detection also of Raman frequency-shifted spectral lines), high spectral resolution lidars, systems with depolarization measurement capabilities and multi-wavelength instruments are described, and the fundamentals in which the retrieval of aerosol parameters is based is in each case detailed. Full article

(This article belongs to the Special Issue Laser Sensors for Displacement, Distance, Flow, Velocity and Vibrations Measurements)

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16 pages, 3746 KiB

Open AccessArticle

Fiber Optic Thermo-Hygrometers for Soil Moisture Monitoring

by Marco Leone¹, Sofia Principe¹, Marco Consales¹, Roberto Parente¹, Armando Laudati², Stefano Caliro³, Antonello Cutolo¹

and Andrea Cusano^1,*

¹ Optoelectronic Division, Department of Engineering, University of Sannio, 82100 Benevento, Italy

² Optosmart s.r.l., 80055 Portici (NA), Italy

³ Istituto Nazionale di Geofisica e Vulcanologia—INGV, Osservatorio Vesuviano, 80124 Napoli, Italy

Sensors 2017, 17(6), 1451; https://doi.org/10.3390/s17061451 - 20 Jun 2017

Cited by 28 | Viewed by 10059

Abstract

This work deals with the fabrication, prototyping, and experimental validation of a fiber optic thermo-hygrometer-based soil moisture sensor, useful for rainfall-induced landslide prevention applications. In particular, we recently proposed a new generation of fiber Bragg grating (FBGs)-based soil moisture sensors for irrigation purposes. [...] Read more.

This work deals with the fabrication, prototyping, and experimental validation of a fiber optic thermo-hygrometer-based soil moisture sensor, useful for rainfall-induced landslide prevention applications. In particular, we recently proposed a new generation of fiber Bragg grating (FBGs)-based soil moisture sensors for irrigation purposes. This device was realized by integrating, inside a customized aluminum protection package, a FBG thermo-hygrometer with a polymer micro-porous membrane. Here, we first verify the limitations, in terms of the volumetric water content (VWC) measuring range, of this first version of the soil moisture sensor for its exploitation in landslide prevention applications. Successively, we present the development, prototyping, and experimental validation of a novel, optimized version of a soil VWC sensor, still based on a FBG thermo-hygrometer, but able to reliably monitor, continuously and in real-time, VWC values up to 37% when buried in the soil. Full article

(This article belongs to the Special Issue Humidity Sensors)

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25 pages, 9096 KiB

Open AccessArticle

MinT: Middleware for Cooperative Interaction of Things

by Soobin Jeon and Inbum Jung^*

Department of Computer Information and Communication Engineering, Kangwon National University, Chuncheon, Gangwondo 200-701, Korea

Sensors 2017, 17(6), 1452; https://doi.org/10.3390/s17061452 - 20 Jun 2017

Cited by 16 | Viewed by 7330

Abstract

This paper proposes an Internet of Things (IoT) middleware called Middleware for Cooperative Interaction of Things (MinT). MinT supports a fully distributed IoT environment in which IoT devices directly connect to peripheral devices easily construct a local or global network, and share their [...] Read more.

This paper proposes an Internet of Things (IoT) middleware called Middleware for Cooperative Interaction of Things (MinT). MinT supports a fully distributed IoT environment in which IoT devices directly connect to peripheral devices easily construct a local or global network, and share their data in an energy efficient manner. MinT provides a sensor abstract layer, a system layer and an interaction layer. These enable integrated sensing device operations, efficient resource management, and active interconnection between peripheral IoT devices. In addition, MinT provides a high-level API to develop IoT devices easily for IoT device developers. We aim to enhance the energy efficiency and performance of IoT devices through the performance improvements offered by MinT resource management and request processing. The experimental results show that the average request rate increased by 25% compared to Californium, which is a middleware for efficient interaction in IoT environments with powerful performance, an average response time decrease of 90% when resource management was used, and power consumption decreased by up to 68%. Finally, the proposed platform can reduce the latency and power consumption of IoT devices. Full article

(This article belongs to the Special Issue New Paradigms in Data Sensing and Processing for Edge Computing)

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22 pages, 4063 KiB

Open AccessReview

Smartphone-Based Food Diagnostic Technologies: A Review

by Giovanni Rateni^*, Paolo Dario and Filippo Cavallo

The BioRobotics Institute, Scuola Superiore Sant’Anna, Viale Rinaldo Piaggio 34, 56025 Pontedera (PI), Italy

Sensors 2017, 17(6), 1453; https://doi.org/10.3390/s17061453 - 20 Jun 2017

Cited by 260 | Viewed by 22606

Abstract

A new generation of mobile sensing approaches offers significant advantages over traditional platforms in terms of test speed, control, low cost, ease-of-operation, and data management, and requires minimal equipment and user involvement. The marriage of novel sensing technologies with cellphones enables the development [...] Read more.

A new generation of mobile sensing approaches offers significant advantages over traditional platforms in terms of test speed, control, low cost, ease-of-operation, and data management, and requires minimal equipment and user involvement. The marriage of novel sensing technologies with cellphones enables the development of powerful lab-on-smartphone platforms for many important applications including medical diagnosis, environmental monitoring, and food safety analysis. This paper reviews the recent advancements and developments in the field of smartphone-based food diagnostic technologies, with an emphasis on custom modules to enhance smartphone sensing capabilities. These devices typically comprise multiple components such as detectors, sample processors, disposable chips, batteries and software, which are integrated with a commercial smartphone. One of the most important aspects of developing these systems is the integration of these components onto a compact and lightweight platform that requires minimal power. To date, researchers have demonstrated several promising approaches employing various sensing techniques and device configurations. We aim to provide a systematic classification according to the detection strategy, providing a critical discussion of strengths and weaknesses. We have also extended the analysis to the food scanning devices that are increasingly populating the Internet of Things (IoT) market, demonstrating how this field is indeed promising, as the research outputs are quickly capitalized on new start-up companies. Full article

(This article belongs to the Special Issue Sensors for Biomedical, Environmental and Food Monitoring Applications)

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20 pages, 3443 KiB

Open AccessArticle

Compressed-Sensing Reconstruction Based on Block Sparse Bayesian Learning in Bearing-Condition Monitoring

by Jiedi Sun^1,*

, Yang Yu² and Jiangtao Wen²

¹ School of Information Science and Engineering, Yanshan University, 438, Hebei Avenue, Qinhuangdao 066004, China

² Key Laboratory of Measurement Technology and Instrumentation of Hebei Province, Yanshan University, Qinhuangdao 066004, China

Sensors 2017, 17(6), 1454; https://doi.org/10.3390/s17061454 - 21 Jun 2017

Cited by 17 | Viewed by 7027

Abstract

Remote monitoring of bearing conditions, using wireless sensor network (WSN), is a developing trend in the industrial field. In complicated industrial environments, WSN face three main constraints: low energy, less memory, and low operational capability. Conventional data-compression methods, which concentrate on data compression [...] Read more.

Remote monitoring of bearing conditions, using wireless sensor network (WSN), is a developing trend in the industrial field. In complicated industrial environments, WSN face three main constraints: low energy, less memory, and low operational capability. Conventional data-compression methods, which concentrate on data compression only, cannot overcome these limitations. Aiming at these problems, this paper proposed a compressed data acquisition and reconstruction scheme based on Compressed Sensing (CS) which is a novel signal-processing technique and applied it for bearing conditions monitoring via WSN. The compressed data acquisition is realized by projection transformation and can greatly reduce the data volume, which needs the nodes to process and transmit. The reconstruction of original signals is achieved in the host computer by complicated algorithms. The bearing vibration signals not only exhibit the sparsity property, but also have specific structures. This paper introduced the block sparse Bayesian learning (BSBL) algorithm which works by utilizing the block property and inherent structures of signals to reconstruct CS sparsity coefficients of transform domains and further recover the original signals. By using the BSBL, CS reconstruction can be improved remarkably. Experiments and analyses showed that BSBL method has good performance and is suitable for practical bearing-condition monitoring. Full article

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

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16 pages, 4082 KiB

Open AccessArticle

Soil Moisture Content Estimation Based on Sentinel-1 and Auxiliary Earth Observation Products. A Hydrological Approach

by Dimitrios D. Alexakis^*, Filippos-Dimitrios K. Mexis, Anthi-Eirini K. Vozinaki, Ioannis N. Daliakopoulos

and Ioannis K. Tsanis

School of Environmental Engineering, Technical University of Crete, Chania 73100, Greece

Sensors 2017, 17(6), 1455; https://doi.org/10.3390/s17061455 - 21 Jun 2017

Cited by 117 | Viewed by 11333

Abstract

A methodology for elaborating multi-temporal Sentinel-1 and Landsat 8 satellite images for estimating topsoil Soil Moisture Content (SMC) to support hydrological simulation studies is proposed. After pre-processing the remote sensing data, backscattering coefficient, Normalized Difference Vegetation Index (NDVI), thermal infrared temperature and incidence [...] Read more.

A methodology for elaborating multi-temporal Sentinel-1 and Landsat 8 satellite images for estimating topsoil Soil Moisture Content (SMC) to support hydrological simulation studies is proposed. After pre-processing the remote sensing data, backscattering coefficient, Normalized Difference Vegetation Index (NDVI), thermal infrared temperature and incidence angle parameters are assessed for their potential to infer ground measurements of SMC, collected at the top 5 cm. A non-linear approach using Artificial Neural Networks (ANNs) is tested. The methodology is applied in Western Crete, Greece, where a SMC gauge network was deployed during 2015. The performance of the proposed algorithm is evaluated using leave-one-out cross validation and sensitivity analysis. ANNs prove to be the most efficient in SMC estimation yielding R² values between 0.7 and 0.9. The proposed methodology is used to support a hydrological simulation with the HEC-HMS model, applied at the Keramianos basin which is ungauged for SMC. Results and model sensitivity highlight the contribution of combining Sentinel-1 SAR and Landsat 8 images for improving SMC estimates and supporting hydrological studies. Full article

(This article belongs to the Special Issue Recent Innovative Microwave Remote Sensing Instrumentation for Land Surface Applications)

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18 pages, 3547 KiB

Open AccessArticle

Single-Lead Fetal ECG Extraction Based on a Parallel Marginalized Particle Filter

by Zhidong Zhao^1,*, Huiling Tong², Yanjun Deng², Wen Xu², Yefei Zhang² and Haihui Ye³

¹ College of Electronics and Information, Hangzhou Dianzi University; Hangdian Smart City Research Center of Zhejiang Province, Hangzhou 310018, China

² School of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, China

³ Women’s Hospital School of Medicine Zhejiang University, Hangzhou 310006, China

Sensors 2017, 17(6), 1456; https://doi.org/10.3390/s17061456 - 21 Jun 2017

Cited by 6 | Viewed by 5589

Abstract

This paper presents a novel method for extracting the fetal ECG (FECG) from a single-lead abdominal signal. A dynamical model for a modified abdominal signal is proposed, in which both the maternal ECG (MECG) and the FECG are modeled, and then a parallel [...] Read more.

This paper presents a novel method for extracting the fetal ECG (FECG) from a single-lead abdominal signal. A dynamical model for a modified abdominal signal is proposed, in which both the maternal ECG (MECG) and the FECG are modeled, and then a parallel marginalized particle filter (par-MPF) is used for tracking the abdominal signal. Finally, the FECG and MECG are simultaneously separated. Several experiments are conducted using both simulated and clinical signals. The results indicate that the method proposed in this paper effectively extracts the FECG and outperforms other Bayesian filtering algorithms. Full article

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

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44 pages, 1566 KiB

Open AccessArticle

Towards the Internet of Smart Trains: A Review on Industrial IoT-Connected Railways

by Paula Fraga-Lamas^*

, Tiago M. Fernández-Caramés

and Luis Castedo

Department of Computer Engineering, Faculty of Computer Science, Universidade da Coruña,15071 A Coruña, Spain

Sensors 2017, 17(6), 1457; https://doi.org/10.3390/s17061457 - 21 Jun 2017

Cited by 196 | Viewed by 27416

Abstract

Nowadays, the railway industry is in a position where it is able to exploit the opportunities created by the IIoT (Industrial Internet of Things) and enabling communication technologies under the paradigm of Internet of Trains. This review details the evolution of communication technologies [...] Read more.

Nowadays, the railway industry is in a position where it is able to exploit the opportunities created by the IIoT (Industrial Internet of Things) and enabling communication technologies under the paradigm of Internet of Trains. This review details the evolution of communication technologies since the deployment of GSM-R, describing the main alternatives and how railway requirements, specifications and recommendations have evolved over time. The advantages of the latest generation of broadband communication systems (e.g., LTE, 5G, IEEE 802.11ad) and the emergence of Wireless Sensor Networks (WSNs) for the railway environment are also explained together with the strategic roadmap to ensure a smooth migration from GSM-R. Furthermore, this survey focuses on providing a holistic approach, identifying scenarios and architectures where railways could leverage better commercial IIoT capabilities. After reviewing the main industrial developments, short and medium-term IIoT-enabled services for smart railways are evaluated. Then, it is analyzed the latest research on predictive maintenance, smart infrastructure, advanced monitoring of assets, video surveillance systems, railway operations, Passenger and Freight Information Systems (PIS/FIS), train control systems, safety assurance, signaling systems, cyber security and energy efficiency. Overall, it can be stated that the aim of this article is to provide a detailed examination of the state-of-the-art of different technologies and services that will revolutionize the railway industry and will allow for confronting today challenges. Full article

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

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12 pages, 3293 KiB

Open AccessArticle

Ag Nanoparticles Drop-Casting Modification of Screen-Printed Electrodes for the Simultaneous Voltammetric Determination of Cu(II) and Pb(II)

by Clara Pérez-Ràfols¹, Julio Bastos-Arrieta^2,3

, Núria Serrano¹

, José Manuel Díaz-Cruz^1,*

, Cristina Ariño¹, Joan De Pablo^2,3,4 and Miquel Esteban¹

¹ Departament d’Enginyeria Química i Química Analítica, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain

² Departament d’Enginyeria Química, Universitat Politècnica de Catalunya (UPC), Campus Diagonal Besòs, Edificio I (EEBE), Carrer Eduard Maristany 10-14, 08019 Barcelona, Spain

³ Barcelona Research Center for Multiscale Science and Engineering, 08019 Barcelona, Spain

⁴ Fundació CTM Centre Tecnològic, Plaça de la Ciència 2, 08240 Manresa, Spain

Sensors 2017, 17(6), 1458; https://doi.org/10.3390/s17061458 - 21 Jun 2017

Cited by 45 | Viewed by 8150

Abstract

A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, [...] Read more.

A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, graphite, graphene and carbon nanofibers, were tested. The best analytical performance was achieved for the combination of Ag nanoseeds with a carbon nanofiber modified screen-printed electrode. The resulting sensor allowed the simultaneous determination of Pb(II) and Cu(II) at trace levels and its applicability to natural samples was successfully tested with a groundwater certified reference material, presenting high reproducibility and trueness. Full article

(This article belongs to the Special Issue Screen-Printed Electrodes)

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10 pages, 2652 KiB

Open AccessArticle

Light Emitting Marker for Robust Vision-Based On-The-Spot Bacterial Growth Detection

by Kyukwang Kim¹, Jieum Hyun¹ and Jessie S. Jeon^2,*

¹ Urban Robotics Laboratory, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Daejeon 34141, Korea

² Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Daejeon 34141, Korea

Sensors 2017, 17(6), 1459; https://doi.org/10.3390/s17061459 - 21 Jun 2017

Cited by 3 | Viewed by 6852

Abstract

Simple methods using the striped pattern paper marker and FFT (fast Fourier transformation) have been proposed as alternatives to measuring the optical density for determining the level of bacterial growth. The marker-based method can be easily automated, but due to image-processing-base of the [...] Read more.

Simple methods using the striped pattern paper marker and FFT (fast Fourier transformation) have been proposed as alternatives to measuring the optical density for determining the level of bacterial growth. The marker-based method can be easily automated, but due to image-processing-base of the method, the presence of light or the color of the culture broth can disturb the detection process. This paper proposes a modified version of marker-FFT-based growth detection that uses a light emitting diode (LED) array as a marker. Since the marker itself can emit the light, the measurements can be performed even when there is no light source or the bacteria are cultured in a large volume of darkly colored broth. In addition, an LED marker can function as a region of interest (ROI) indicator in the image. We expect that the proposed LED-based marker system will allow more robust growth detection compared to conventional methods. Full article

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

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16 pages, 2102 KiB

Open AccessArticle

Analysis of Maneuvering Targets with Complex Motions by Two-Dimensional Product Modified Lv’s Distribution for Quadratic Frequency Modulation Signals

by Fulong Jing, Shuhong Jiao, Changbo Hou^*, Weijian Si and Yu Wang

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

Sensors 2017, 17(6), 1460; https://doi.org/10.3390/s17061460 - 21 Jun 2017

Cited by 5 | Viewed by 5075

Abstract

For targets with complex motion, such as ships fluctuating with oceanic waves and high maneuvering airplanes, azimuth echo signals can be modeled as multicomponent quadratic frequency modulation (QFM) signals after migration compensation and phase adjustment. For the QFM signal model, the chirp rate [...] Read more.

For targets with complex motion, such as ships fluctuating with oceanic waves and high maneuvering airplanes, azimuth echo signals can be modeled as multicomponent quadratic frequency modulation (QFM) signals after migration compensation and phase adjustment. For the QFM signal model, the chirp rate (CR) and the quadratic chirp rate (QCR) are two important physical quantities, which need to be estimated. For multicomponent QFM signals, the cross terms create a challenge for detection, which needs to be addressed. In this paper, by employing a novel multi-scale parametric symmetric self-correlation function (PSSF) and modified scaled Fourier transform (mSFT), an effective parameter estimation algorithm is proposed—referred to as the Two-Dimensional product modified Lv’s distribution (2D-PMLVD)—for QFM signals. The 2D-PMLVD is simple and can be easily implemented by using fast Fourier transform (FFT) and complex multiplication. These measures are analyzed in the paper, including the principle, the cross term, anti-noise performance, and computational complexity. Compared to the other three representative methods, the 2D-PMLVD can achieve better anti-noise performance. The 2D-PMLVD, which is free of searching and has no identifiability problems, is more suitable for multicomponent situations. Through several simulations and analyses, the effectiveness of the proposed estimation algorithm is verified. 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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Sensors, Volume 17, Issue 6 (June 2017) – 277 articles

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