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Sensors, Volume 17, Issue 12 (December 2017)

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Cover Story (view full-size image) Berveglieri and co-workers report a low-cost technique that uses vertical optical scanning with a [...] Read more.
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Open AccessArticle Out-of-Focus Projector Calibration Method with Distortion Correction on the Projection Plane in the Structured Light Three-Dimensional Measurement System
Sensors 2017, 17(12), 2963; https://doi.org/10.3390/s17122963
Received: 17 October 2017 / Revised: 18 December 2017 / Accepted: 19 December 2017 / Published: 20 December 2017
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Abstract
The three-dimensional measurement system with a binary defocusing technique is widely applied in diverse fields. The measurement accuracy is mainly determined by out-of-focus projector calibration accuracy. In this paper, a high-precision out-of-focus projector calibration method that is based on distortion correction on the
[...] Read more.
The three-dimensional measurement system with a binary defocusing technique is widely applied in diverse fields. The measurement accuracy is mainly determined by out-of-focus projector calibration accuracy. In this paper, a high-precision out-of-focus projector calibration method that is based on distortion correction on the projection plane and nonlinear optimization algorithm is proposed. To this end, the paper experimentally presents the principle that the projector has noticeable distortions outside its focus plane. In terms of this principle, the proposed method uses a high-order radial and tangential lens distortion representation on the projection plane to correct the calibration residuals caused by projection distortion. The final accuracy parameters of out-of-focus projector were obtained using a nonlinear optimization algorithm with good initial values, which were provided by coarsely calibrating the parameters of the out-of-focus projector on the focal and projection planes. Finally, the experimental results demonstrated that the proposed method can accuracy calibrate an out-of-focus projector, regardless of the amount of defocusing. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Quantitative and Sensitive Detection of Chloramphenicol by Surface-Enhanced Raman Scattering
Sensors 2017, 17(12), 2962; https://doi.org/10.3390/s17122962
Received: 23 October 2017 / Revised: 3 December 2017 / Accepted: 5 December 2017 / Published: 20 December 2017
Cited by 1 | PDF Full-text (1568 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We used surface-enhanced Raman scattering (SERS) for the quantitative and sensitive detection of chloramphenicol (CAP). Using 30 nm colloidal Au nanoparticles (NPs), a low detection limit for CAP of 10−8 M was obtained. The characteristic Raman peak of CAP centered at 1344
[...] Read more.
We used surface-enhanced Raman scattering (SERS) for the quantitative and sensitive detection of chloramphenicol (CAP). Using 30 nm colloidal Au nanoparticles (NPs), a low detection limit for CAP of 10−8 M was obtained. The characteristic Raman peak of CAP centered at 1344 cm−1 was used for the rapid quantitative detection of CAP in three different types of CAP eye drops, and the accuracy of the measurement result was verified by high-performance liquid chromatography (HPLC). The experimental results reveal that the SERS technique based on colloidal Au NPs is accurate and sensitive, and can be used for the rapid detection of various antibiotics. Full article
(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)
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Open AccessArticle Location Accuracy of INS/Gravity-Integrated Navigation System on the Basis of Ocean Experiment and Simulation
Sensors 2017, 17(12), 2961; https://doi.org/10.3390/s17122961
Received: 21 November 2017 / Revised: 15 December 2017 / Accepted: 19 December 2017 / Published: 20 December 2017
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Abstract
An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1′ × 1′ marine gravity anomaly
[...] Read more.
An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1′ × 1′ marine gravity anomaly reference map and multi-model adaptive Kalman filtering algorithm, a matching location experiment of IGNS was conducted using data obtained using marine gravimeter. The location accuracy under actual ocean conditions was 2.83 nautical miles (n miles). Several groups of simulated data of marine gravity anomalies were obtained by establishing normally distributed random error N ( u , σ 2 ) with varying mean u and noise variance σ 2 . Thereafter, the matching location of IGNS was simulated. The results show that the changes in u had little effect on the location accuracy. However, an increase in σ 2 resulted in a significant decrease in the location accuracy. A comparison between the actual ocean experiment and the simulation along the same route demonstrated the effectiveness of the proposed simulation method and quantitative analysis results. In addition, given the gravimeter (1–2 mGal accuracy) and the reference map (resolution 1′ × 1′; accuracy 3–8 mGal), location accuracy of IGNS was up to reach ~1.0–3.0 n miles in the South China Sea. Full article
(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)
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Open AccessArticle Remotely Exploring Deeper-Into-Matter by Non-Contact Detection of Audible Transients Excited by Laser Radiation
Sensors 2017, 17(12), 2960; https://doi.org/10.3390/s17122960
Received: 8 November 2017 / Revised: 13 December 2017 / Accepted: 16 December 2017 / Published: 20 December 2017
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Abstract
An acoustic spectroscopic approach to detect contents within different packaging, with substantially wider applicability than other currently available subsurface spectroscopies, is presented. A frequency-doubled Nd:YAG (neodymium-doped yttrium aluminum garnet) pulsed laser (13 ns pulse length) operated at 1 Hz was used to generate
[...] Read more.
An acoustic spectroscopic approach to detect contents within different packaging, with substantially wider applicability than other currently available subsurface spectroscopies, is presented. A frequency-doubled Nd:YAG (neodymium-doped yttrium aluminum garnet) pulsed laser (13 ns pulse length) operated at 1 Hz was used to generate the sound field of a two-component system at a distance of 50 cm. The acoustic emission was captured using a unidirectional microphone and analyzed in the frequency domain. The focused laser pulse hitting the system, with intensity above that necessary to ablate the irradiated surface, transferred an impulsive force which led the structure to vibrate. Acoustic airborne transients were directly radiated by the vibrating elastic structure of the outer component that excited the surrounding air in contact with. However, under boundary conditions, sound field is modulated by the inner component that modified the dynamical integrity of the system. Thus, the resulting frequency spectra are useful indicators of the concealed content that influences the contributions originating from the wall of the container. High-quality acoustic spectra could be recorded from a gas (air), liquid (water), and solid (sand) placed inside opaque chemical-resistant polypropylene and stainless steel sample containers. Discussion about effects of laser excitation energy and sampling position on the acoustic emission events is reported. Acoustic spectroscopy may complement the other subsurface alternative spectroscopies, severely limited by their inherent optical requirements for numerous detection scenarios. Full article
(This article belongs to the Special Issue Spectroscopy Based Sensors)
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Open AccessArticle A Large-Scale Multi-Hop Localization Algorithm Based on Regularized Extreme Learning for Wireless Networks
Sensors 2017, 17(12), 2959; https://doi.org/10.3390/s17122959
Received: 20 November 2017 / Revised: 12 December 2017 / Accepted: 18 December 2017 / Published: 20 December 2017
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Abstract
A novel large-scale multi-hop localization algorithm based on regularized extreme learning is proposed in this paper. The large-scale multi-hop localization problem is formulated as a learning problem. Unlike other similar localization algorithms, the proposed algorithm overcomes the shortcoming of the traditional algorithms which
[...] Read more.
A novel large-scale multi-hop localization algorithm based on regularized extreme learning is proposed in this paper. The large-scale multi-hop localization problem is formulated as a learning problem. Unlike other similar localization algorithms, the proposed algorithm overcomes the shortcoming of the traditional algorithms which are only applicable to an isotropic network, therefore has a strong adaptability to the complex deployment environment. The proposed algorithm is composed of three stages: data acquisition, modeling and location estimation. In data acquisition stage, the training information between nodes of the given network is collected. In modeling stage, the model among the hop-counts and the physical distances between nodes is constructed using regularized extreme learning. In location estimation stage, each node finds its specific location in a distributed manner. Theoretical analysis and several experiments show that the proposed algorithm can adapt to the different topological environments with low computational cost. Furthermore, high accuracy can be achieved by this method without setting complex parameters. Full article
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Open AccessArticle Optimal Rate Schedules with Data Sharing in Energy Harvesting Communication Systems
Sensors 2017, 17(12), 2958; https://doi.org/10.3390/s17122958
Received: 17 November 2017 / Revised: 13 December 2017 / Accepted: 17 December 2017 / Published: 20 December 2017
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Abstract
Despite the abundant research on energy-efficient rate scheduling polices in energy harvesting communication systems, few works have exploited data sharing among multiple applications to further enhance the energy utilization efficiency, considering that the harvested energy from environments is limited and unstable. In this
[...] Read more.
Despite the abundant research on energy-efficient rate scheduling polices in energy harvesting communication systems, few works have exploited data sharing among multiple applications to further enhance the energy utilization efficiency, considering that the harvested energy from environments is limited and unstable. In this paper, to overcome the energy shortage of wireless devices at transmitting data to a platform running multiple applications/requesters, we design rate scheduling policies to respond to data requests as soon as possible by encouraging data sharing among data requests and reducing the redundancy. We formulate the problem as a transmission completion time minimization problem under constraints of dynamical data requests and energy arrivals. We develop offline and online algorithms to solve this problem. For the offline setting, we discover the relationship between two problems: the completion time minimization problem and the energy consumption minimization problem with a given completion time. We first derive the optimal algorithm for the min-energy problem and then adopt it as a building block to compute the optimal solution for the min-completion-time problem. For the online setting without future information, we develop an event-driven online algorithm to complete the transmission as soon as possible. Simulation results validate the efficiency of the proposed algorithm. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle An Architecture Providing Depolarization Ratio Capability for a Multi-Wavelength Raman Lidar: Implementation and First Measurements
Sensors 2017, 17(12), 2957; https://doi.org/10.3390/s17122957
Received: 17 October 2017 / Revised: 10 December 2017 / Accepted: 15 December 2017 / Published: 20 December 2017
Cited by 1 | PDF Full-text (3695 KB) | HTML Full-text | XML Full-text
Abstract
A new architecture for the measurement of depolarization produced by atmospheric aerosols with a Raman lidar is presented. The system uses two different telescopes: one for depolarization measurements and another for total-power measurements. The system architecture and principle of operation are described. The
[...] Read more.
A new architecture for the measurement of depolarization produced by atmospheric aerosols with a Raman lidar is presented. The system uses two different telescopes: one for depolarization measurements and another for total-power measurements. The system architecture and principle of operation are described. The first experimental results are also presented, corresponding to a collection of atmospheric conditions over the city of Barcelona. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Enhancing Time Synchronization Support in Wireless Sensor Networks
Sensors 2017, 17(12), 2956; https://doi.org/10.3390/s17122956
Received: 19 October 2017 / Revised: 7 December 2017 / Accepted: 11 December 2017 / Published: 20 December 2017
Cited by 2 | PDF Full-text (7375 KB) | HTML Full-text | XML Full-text
Abstract
With the emerging Internet of Things (IoT) technology becoming reality, a number of applications are being proposed. Several of these applications are highly dependent on wireless sensor networks (WSN) to acquire data from the surrounding environment. In order to be really useful for
[...] Read more.
With the emerging Internet of Things (IoT) technology becoming reality, a number of applications are being proposed. Several of these applications are highly dependent on wireless sensor networks (WSN) to acquire data from the surrounding environment. In order to be really useful for most of applications, the acquired data must be coherent in terms of the time in which they are acquired, which implies that the entire sensor network presents a certain level of time synchronization. Moreover, to efficiently exchange and forward data, many communication protocols used in WSN rely also on time synchronization among the sensor nodes. Observing the importance in complying with this need for time synchronization, this work focuses on the second synchronization problem, proposing, implementing and testing a time synchronization service for low-power WSN using low frequency real-time clocks in each node. To implement this service, three algorithms based on different strategies are proposed: one based on an auto-correction approach, the second based on a prediction mechanism, while the third uses an analytical correction mechanism. Their goal is the same, i.e., to make the clocks of the sensor nodes converge as quickly as possible and then to keep them most similar as possible. This goal comes along with the requirement to keep low energy consumption. Differently from other works in the literature, the proposal here is independent of any specific protocol, i.e., it may be adapted to be used in different protocols. Moreover, it explores the minimum number of synchronization messages by means of a smart clock update strategy, allowing the trade-off between the desired level of synchronization and the associated energy consumption. Experimental results, which includes data acquired from simulations and testbed deployments, provide evidence of the success in meeting this goal, as well as providing means to compare these three approaches considering the best synchronization results and their costs in terms of energy consumption. Full article
(This article belongs to the Special Issue Internet of Things and Ubiquitous Sensing)
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Open AccessArticle Anti-Runaway Prevention System with Wireless Sensors for Intelligent Track Skates at Railway Stations
Sensors 2017, 17(12), 2955; https://doi.org/10.3390/s17122955
Received: 24 November 2017 / Revised: 7 December 2017 / Accepted: 14 December 2017 / Published: 19 December 2017
Cited by 1 | PDF Full-text (3300 KB) | HTML Full-text | XML Full-text
Abstract
Anti-runaway prevention of rolling stocks at a railway station is essential in railway safety management. The traditional track skates for anti-runaway prevention of rolling stocks have some disadvantages since they are operated and monitored completely manually. This paper describes an anti-runaway prevention system
[...] Read more.
Anti-runaway prevention of rolling stocks at a railway station is essential in railway safety management. The traditional track skates for anti-runaway prevention of rolling stocks have some disadvantages since they are operated and monitored completely manually. This paper describes an anti-runaway prevention system (ARPS) based on intelligent track skates equipped with sensors and real-time monitoring and management system. This system, which has been updated from the traditional track skates, comprises four parts: intelligent track skates, a signal reader, a database station, and a monitoring system. This system can monitor the real-time situation of track skates without changing their workflow for anti-runaway prevention, and thus realize the integration of anti-runaway prevention information management. This system was successfully tested and practiced at Sunjia station in Harbin Railway Bureau in 2014, and the results confirmed that the system showed 100% accuracy in reflecting the usage status of the track skates. The system could meet practical demands, as it is highly reliable and supports long-distance communication. Full article
(This article belongs to the Special Issue Sensors for Transportation)
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Open AccessArticle Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO2 Gas Sensor
Sensors 2017, 17(12), 2954; https://doi.org/10.3390/s17122954
Received: 7 November 2017 / Revised: 5 December 2017 / Accepted: 9 December 2017 / Published: 19 December 2017
Cited by 1 | PDF Full-text (1824 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ultrasensitive room temperature real-time NO2 sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO2 gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or
[...] Read more.
Ultrasensitive room temperature real-time NO2 sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO2 gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultrasensitive NO2 sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN) nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO) was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO2 sensing performance (10 ppb to 20 ppm) at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO2 sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors. Full article
(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)
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Open AccessArticle 3D-Printed Detector Band for Magnetic Off-Plane Flux Measurements in Laminated Machine Cores
Sensors 2017, 17(12), 2953; https://doi.org/10.3390/s17122953
Received: 7 November 2017 / Revised: 6 December 2017 / Accepted: 7 December 2017 / Published: 19 December 2017
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Abstract
Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the
[...] Read more.
Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core. Full article
(This article belongs to the Special Issue Magnetic Sensors and Their Applications)
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Open AccessReview Sensors and Biosensors for C-Reactive Protein, Temperature and pH, and Their Applications for Monitoring Wound Healing: A Review
Sensors 2017, 17(12), 2952; https://doi.org/10.3390/s17122952
Received: 27 October 2017 / Revised: 24 November 2017 / Accepted: 13 December 2017 / Published: 19 December 2017
Cited by 2 | PDF Full-text (2456 KB) | HTML Full-text | XML Full-text
Abstract
Wound assessment is usually performed in hospitals or specialized labs. However, since patients spend most of their time at home, a remote real time wound monitoring would help providing a better care and improving the healing rate. This review describes the advances in
[...] Read more.
Wound assessment is usually performed in hospitals or specialized labs. However, since patients spend most of their time at home, a remote real time wound monitoring would help providing a better care and improving the healing rate. This review describes the advances in sensors and biosensors for monitoring the concentration of C-reactive protein (CRP), temperature and pH in wounds. These three parameters can be used as qualitative biomarkers to assess the wound status and the effectiveness of therapy. CRP biosensors can be classified in: (a) field effect transistors, (b) optical immunosensors based on surface plasmon resonance, total internal reflection, fluorescence and chemiluminescence, (c) electrochemical sensors based on potentiometry, amperometry, and electrochemical impedance, and (d) piezoresistive sensors, such as quartz crystal microbalances and microcantilevers. The last section reports the most recent developments for wearable non-invasive temperature and pH sensors suitable for wound monitoring. Full article
(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)
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Open AccessReview Achievements and Prospects in Electrochemical-Based Biosensing Platforms for Aflatoxin M1 Detection in Milk and Dairy Products
Sensors 2017, 17(12), 2951; https://doi.org/10.3390/s17122951
Received: 15 November 2017 / Revised: 3 December 2017 / Accepted: 13 December 2017 / Published: 19 December 2017
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Abstract
Aflatoxins, which are mainly produced by Aspergillus flavus and parasiticus growing on plants and products stored under inappropriate conditions, represent the most studied group of mycotoxins. Contamination of human and animal milk with aflatoxin M1, the hydroxylated metabolite of aflatoxin B
[...] Read more.
Aflatoxins, which are mainly produced by Aspergillus flavus and parasiticus growing on plants and products stored under inappropriate conditions, represent the most studied group of mycotoxins. Contamination of human and animal milk with aflatoxin M1, the hydroxylated metabolite of aflatoxin B1, is an important health risk factor due to its carcinogenicity and mutagenicity. Due to the low concentration of this aflatoxin in milk and milk products, the analytical methods used for its quantification have to be highly sensitive, specific and simple. This paper presents an overview of the analytical methods, especially of the electrochemical immunosensors and aptasensors, used for determination of aflatoxin M1. Full article
(This article belongs to the Special Issue Protein-Based Biosensors)
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Open AccessArticle Investigation of Wavenumber Domain Imaging Algorithm for Ground-Based Arc Array SAR
Sensors 2017, 17(12), 2950; https://doi.org/10.3390/s17122950
Received: 23 October 2017 / Revised: 10 December 2017 / Accepted: 15 December 2017 / Published: 19 December 2017
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Abstract
Ground-based synthetic aperture radar (GB-SAR) has become an important technique for remote sensing deformation monitoring. However, most of the existing GB-SAR systems realize synthetic aperture by exploiting two closely spaced horn antennas to move along a linear rail. In order to obtain higher
[...] Read more.
Ground-based synthetic aperture radar (GB-SAR) has become an important technique for remote sensing deformation monitoring. However, most of the existing GB-SAR systems realize synthetic aperture by exploiting two closely spaced horn antennas to move along a linear rail. In order to obtain higher data acquisition efficiency and a wider view angle, we introduce arc antenna array technology into the GB-SAR system, which realizes a novel kind of system: ground-based arc array SAR (GB-AA-SAR). In this paper, we analyze arc observation geometry and derive analytic expressions of sampling criteria. Then, we propose a novel wavenumber domain imaging algorithm for GB-AA-SAR, which can achieve high image reconstruction precision through numerical solutions in the wavenumber domain. The proposed algorithm can be applied in wide azimuth view angle scenarios, and the problem of azimuth mismatch caused by distance approximation in arc geometric efficient omega-k imaging can be solved successfully. Finally, we analyze the two-dimensional (2D) spatial resolution of GB-AA-SAR, and verify the effectiveness of the proposed algorithm through numerical simulation experiments. Full article
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Open AccessFeature PaperArticle Integrity Testing of Pile Cover Using Distributed Fibre Optic Sensing
Sensors 2017, 17(12), 2949; https://doi.org/10.3390/s17122949
Received: 17 November 2017 / Revised: 9 December 2017 / Accepted: 14 December 2017 / Published: 19 December 2017
Cited by 2 | PDF Full-text (6832 KB) | HTML Full-text | XML Full-text
Abstract
The integrity of cast-in-place foundation piles is a major concern in geotechnical engineering. In this study, distributed fibre optic sensing (DFOS) cables, embedded in a pile during concreting, are used to measure the changes in concrete curing temperature profile to infer concrete cover
[...] Read more.
The integrity of cast-in-place foundation piles is a major concern in geotechnical engineering. In this study, distributed fibre optic sensing (DFOS) cables, embedded in a pile during concreting, are used to measure the changes in concrete curing temperature profile to infer concrete cover thickness through modelling of heat transfer processes within the concrete and adjacent ground. A field trial was conducted at a high-rise building construction site in London during the construction of a 51 m long test pile. DFOS cables were attached to the reinforcement cage of the pile at four different axial directions to obtain distributed temperature change data along the pile. The monitoring data shows a clear development of concrete hydration temperature with time and the pattern of the change varies due to small changes in concrete cover. A one-dimensional axisymmetric heat transfer finite element (FE) model is used to estimate the pile geometry with depth by back analysing the DFOS data. The results show that the estimated pile diameter varies with depth in the range between 1.40 and 1.56 m for this instrumented pile. This average pile diameter profile compares well to that obtained with the standard Thermal Integrity Profiling (TIP) method. A parametric study is conducted to examine the sensitivity of concrete and soil thermal properties on estimating the pile geometry. Full article
(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)
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