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10 pages, 2903 KiB

Open AccessArticle

Graphene Nanogrids FET Immunosensor: Signal to Noise Ratio Enhancement

by Jayeeta Basu and Chirasree RoyChaudhuri

Sensors 2016, 16(10), 1481; https://doi.org/10.3390/s16101481 - 8 Oct 2016

Cited by 19 | Viewed by 5981

Abstract

Recently, a reproducible and scalable chemical method for fabrication of smooth graphene nanogrids has been reported which addresses the challenges of graphene nanoribbons (GNR). These nanogrids have been found to be capable of attomolar detection of biomolecules in field effect transistor (FET) mode. [...] Read more.

Recently, a reproducible and scalable chemical method for fabrication of smooth graphene nanogrids has been reported which addresses the challenges of graphene nanoribbons (GNR). These nanogrids have been found to be capable of attomolar detection of biomolecules in field effect transistor (FET) mode. However, for detection of sub-femtomolar concentrations of target molecule in complex mixtures with reasonable accuracy, it is not sufficient to only explore the steady state sensitivities, but is also necessary to investigate the flicker noise which dominates at frequencies below 100 kHz. This low frequency noise is dependent on the exposure time of the graphene layer in the buffer solution and concentration of charged impurities at the surface. In this paper, the functionalization strategy of graphene nanogrids has been optimized with respect to concentration and incubation time of the cross linker for an enhancement in signal to noise ratio (SNR). It has been interestingly observed that as the sensitivity and noise power change at different rates with the functionalization parameters, SNR does not vary monotonically but is maximum corresponding to a particular parameter. The optimized parameter has improved the SNR by 50% which has enabled a detection of 0.05 fM Hep-B virus molecules with a sensitivity of around 30% and a standard deviation within 3%. Further, the SNR enhancement has resulted in improvement of quantification accuracy by five times and selectivity by two orders of magnitude. Full article

(This article belongs to the Special Issue Carbon MEMS and NEMS for Sensor Applications)

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27 pages, 5436 KiB

Open AccessArticle

Adaptive Connectivity Restoration from Node Failure(s) in Wireless Sensor Networks

by Huaiyuan Wang, Xu Ding, Cheng Huang and Xiaobei Wu

Sensors 2016, 16(10), 1487; https://doi.org/10.3390/s16101487 - 28 Sep 2016

Cited by 19 | Viewed by 5106

Abstract

Recently, there is a growing interest in the applications of wireless sensor networks (WSNs). A set of sensor nodes is deployed in order to collectively survey an area of interest and/or perform specific surveillance tasks in some of the applications, such as battlefield [...] Read more.

Recently, there is a growing interest in the applications of wireless sensor networks (WSNs). A set of sensor nodes is deployed in order to collectively survey an area of interest and/or perform specific surveillance tasks in some of the applications, such as battlefield reconnaissance. Due to the harsh deployment environments and limited energy supply, nodes may fail, which impacts the connectivity of the whole network. Since a single node failure (cut-vertex) will destroy the connectivity and divide the network into disjoint blocks, most of the existing studies focus on the problem of single node failure. However, the failure of multiple nodes would be a disaster to the whole network and must be repaired effectively. Only few studies are proposed to handle the problem of multiple cut-vertex failures, which is a special case of multiple node failures. Therefore, this paper proposes a comprehensive solution to address the problems of node failure (single and multiple). Collaborative Single Node Failure Restoration algorithm (CSFR) is presented to solve the problem of single node failure only with cooperative communication, but CSFR-M, which is the extension of CSFR, handles the single node failure problem more effectively with node motion. Moreover, Collaborative Connectivity Restoration Algorithm (CCRA) is proposed on the basis of cooperative communication and node maneuverability to restore network connectivity after multiple nodes fail. CSFR-M and CCRA are reactive methods that initiate the connectivity restoration after detecting the node failure(s). In order to further minimize the energy dissipation, CCRA opts to simplify the recovery process by gridding. Moreover, the distance that an individual node needs to travel during recovery is reduced by choosing the nearest suitable candidates. Finally, extensive simulations validate the performance of CSFR, CSFR-M and CCRA. Full article

(This article belongs to the Section Sensor Networks)

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10 pages, 2632 KiB

Open AccessArticle

Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing

by Di Peng, Lixia Yang, Tao Cai, Yingzheng Liu, Xiaofeng Zhao and Zhiqi Yao

Sensors 2016, 16(10), 1490; https://doi.org/10.3390/s16101490 - 28 Sep 2016

Cited by 15 | Viewed by 6706

Abstract

Yttria-stabilized zirconia (YSZ)-based thermal barrier coating (TBC) has been integrated with thermographic phosphors through air plasma spray (APS) for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm) on the bottom and a regular YSZ [...] Read more.

Yttria-stabilized zirconia (YSZ)-based thermal barrier coating (TBC) has been integrated with thermographic phosphors through air plasma spray (APS) for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm) on the bottom and a regular YSZ layer with a thickness up to 300 µm on top. A measurement system has been established; which included a portable; low-cost diode laser (405 nm); a photo-multiplier tube (PMT) and the related optics. Coating samples with different topcoat thickness were calibrated in a high-temperature furnace from room temperature to around 900 °C. The results convincingly showed that the current sensor and the measurement system was capable of in-depth temperature sensing over 800 °C with a YSZ top layer up to 300 µm. The topcoat thickness was found to have a strong effect on the luminescent signal level. Therefore; the measurement accuracy at high temperatures was reduced for samples with thick topcoats due to strong light attenuation. However; it seemed that the light transmissivity of YSZ topcoat increased with temperature; which would improve the sensor’s performance at high temperatures. The current sensor and the measurement technology have shown great potential in on-line monitoring of TBC interface temperature. Full article

(This article belongs to the Special Issue The Use of New and/or Improved Materials for Sensing Applications)

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18 pages, 8023 KiB

Open AccessArticle

An Online Gravity Modeling Method Applied for High Precision Free-INS

by Jing Wang, Gongliu Yang, Jing Li and Xiao Zhou

Sensors 2016, 16(10), 1541; https://doi.org/10.3390/s16101541 - 23 Sep 2016

Cited by 23 | Viewed by 5842

Abstract

For real-time solution of inertial navigation system (INS), the high-degree spherical harmonic gravity model (SHM) is not applicable because of its time and space complexity, in which traditional normal gravity model (NGM) has been the dominant technique for gravity compensation. In this paper, [...] Read more.

For real-time solution of inertial navigation system (INS), the high-degree spherical harmonic gravity model (SHM) is not applicable because of its time and space complexity, in which traditional normal gravity model (NGM) has been the dominant technique for gravity compensation. In this paper, a two-dimensional second-order polynomial model is derived from SHM according to the approximate linear characteristic of regional disturbing potential. Firstly, deflections of vertical (DOVs) on dense grids are calculated with SHM in an external computer. And then, the polynomial coefficients are obtained using these DOVs. To achieve global navigation, the coefficients and applicable region of polynomial model are both updated synchronously in above computer. Compared with high-degree SHM, the polynomial model takes less storage and computational time at the expense of minor precision. Meanwhile, the model is more accurate than NGM. Finally, numerical test and INS experiment show that the proposed method outperforms traditional gravity models applied for high precision free-INS. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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20 pages, 4162 KiB

Open AccessArticle

Secure Nearest Neighbor Query on Crowd-Sensing Data

by Ke Cheng, Liangmin Wang and Hong Zhong

Sensors 2016, 16(10), 1545; https://doi.org/10.3390/s16101545 - 22 Sep 2016

Cited by 6 | Viewed by 5826

Abstract

Nearest neighbor queries are fundamental in location-based services, and secure nearest neighbor queries mainly focus on how to securely and quickly retrieve the nearest neighbor in the outsourced cloud server. However, the previous big data system structure has changed because of the crowd-sensing [...] Read more.

Nearest neighbor queries are fundamental in location-based services, and secure nearest neighbor queries mainly focus on how to securely and quickly retrieve the nearest neighbor in the outsourced cloud server. However, the previous big data system structure has changed because of the crowd-sensing data. On the one hand, sensing data terminals as the data owner are numerous and mistrustful, while, on the other hand, in most cases, the terminals find it difficult to finish many safety operation due to computation and storage capability constraints. In light of they Multi Owners and Multi Users (MOMU) situation in the crowd-sensing data cloud environment, this paper presents a secure nearest neighbor query scheme based on the proxy server architecture, which is constructed by protocols of secure two-party computation and secure Voronoi diagram algorithm. It not only preserves the data confidentiality and query privacy but also effectively resists the collusion between the cloud server and the data owners or users. Finally, extensive theoretical and experimental evaluations are presented to show that our proposed scheme achieves a superior balance between the security and query performance compared to other schemes. Full article

(This article belongs to the Special Issue Big Data and Cloud Computing for Sensor Networks)

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18 pages, 3855 KiB

Open AccessArticle

An Online Dictionary Learning-Based Compressive Data Gathering Algorithm in Wireless Sensor Networks

by Donghao Wang, Jiangwen Wan, Junying Chen and Qiang Zhang

Sensors 2016, 16(10), 1547; https://doi.org/10.3390/s16101547 - 22 Sep 2016

Cited by 6 | Viewed by 4703

Abstract

To adapt to sense signals of enormous diversities and dynamics, and to decrease the reconstruction errors caused by ambient noise, a novel online dictionary learning method-based compressive data gathering (ODL-CDG) algorithm is proposed. The proposed dictionary is learned from a two-stage iterative procedure, [...] Read more.

To adapt to sense signals of enormous diversities and dynamics, and to decrease the reconstruction errors caused by ambient noise, a novel online dictionary learning method-based compressive data gathering (ODL-CDG) algorithm is proposed. The proposed dictionary is learned from a two-stage iterative procedure, alternately changing between a sparse coding step and a dictionary update step. The self-coherence of the learned dictionary is introduced as a penalty term during the dictionary update procedure. The dictionary is also constrained with sparse structure. It’s theoretically demonstrated that the sensing matrix satisfies the restricted isometry property (RIP) with high probability. In addition, the lower bound of necessary number of measurements for compressive sensing (CS) reconstruction is given. Simulation results show that the proposed ODL-CDG algorithm can enhance the recovery accuracy in the presence of noise, and reduce the energy consumption in comparison with other dictionary based data gathering methods. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 13999 KiB

Open AccessArticle

Reference Beam Pattern Design for Frequency Invariant Beamforming Based on Fast Fourier Transform

by Wang Zhang and Tao Su

Sensors 2016, 16(10), 1554; https://doi.org/10.3390/s16101554 - 22 Sep 2016

Cited by 12 | Viewed by 6767

Abstract

In the field of fast Fourier transform (FFT)-based frequency invariant beamforming (FIB), there is still an unsolved problem. That is the selection of the reference beam to make the designed wideband pattern frequency invariant (FI) over a given frequency range. This problem is [...] Read more.

In the field of fast Fourier transform (FFT)-based frequency invariant beamforming (FIB), there is still an unsolved problem. That is the selection of the reference beam to make the designed wideband pattern frequency invariant (FI) over a given frequency range. This problem is studied in this paper. The research shows that for a given array, the selection of the reference beam pattern is determined by the number of sensors and the ratio of the highest frequency to the lowest frequency of the signal (RHL). The length of the weight vector corresponding to a given reference beam pattern depends on the reference frequency. In addition, the upper bound of the weight length to ensure the FI property over the whole frequency band of interest is also given. When the constraints are added to the reference beam, it does not affect the FI property of the designed wideband beam as long as the symmetry of the reference beam is ensured. Based on this conclusion, a scheme for reference beam design is proposed. Full article

(This article belongs to the Special Issue Synthetic Aperture Radars: Models, Algorithms, Techniques and Tools for Data Exploitation)

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17 pages, 1557 KiB

Open AccessArticle

Performance Evaluation of Analog Beamforming with Hardware Impairments for mmW Massive MIMO Communication in an Urban Scenario

by Sonia Gimenez, Sandra Roger, Paolo Baracca, David Martín-Sacristán, Jose F. Monserrat, Volker Braun and Hardy Halbauer

Sensors 2016, 16(10), 1555; https://doi.org/10.3390/s16101555 - 22 Sep 2016

Cited by 17 | Viewed by 7804

Abstract

The use of massive multiple-input multiple-output (MIMO) techniques for communication at millimeter-Wave (mmW) frequency bands has become a key enabler to meet the data rate demands of the upcoming fifth generation (5G) cellular systems. In particular, analog and hybrid beamforming solutions are receiving [...] Read more.

The use of massive multiple-input multiple-output (MIMO) techniques for communication at millimeter-Wave (mmW) frequency bands has become a key enabler to meet the data rate demands of the upcoming fifth generation (5G) cellular systems. In particular, analog and hybrid beamforming solutions are receiving increasing attention as less expensive and more power efficient alternatives to fully digital precoding schemes. Despite their proven good performance in simple setups, their suitability for realistic cellular systems with many interfering base stations and users is still unclear. Furthermore, the performance of massive MIMO beamforming and precoding methods are in practice also affected by practical limitations and hardware constraints. In this sense, this paper assesses the performance of digital precoding and analog beamforming in an urban cellular system with an accurate mmW channel model under both ideal and realistic assumptions. The results show that analog beamforming can reach the performance of fully digital maximum ratio transmission under line of sight conditions and with a sufficient number of parallel radio-frequency (RF) chains, especially when the practical limitations of outdated channel information and per antenna power constraints are considered. This work also shows the impact of the phase shifter errors and combiner losses introduced by real phase shifter and combiner implementations over analog beamforming, where the former ones have minor impact on the performance, while the latter ones determine the optimum number of RF chains to be used in practice. Full article

(This article belongs to the Special Issue Millimeter Wave Wireless Communications and Networks)

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17 pages, 7900 KiB

Open AccessArticle

Analysis of Uncertainty in a Middle-Cost Device for 3D Measurements in BIM Perspective

by Alonso Sánchez, José-Manuel Naranjo, Antonio Jiménez and Alfonso González

Sensors 2016, 16(10), 1557; https://doi.org/10.3390/s16101557 - 22 Sep 2016

Cited by 7 | Viewed by 5793

Abstract

Medium-cost devices equipped with sensors are being developed to get 3D measurements. Some allow for generating geometric models and point clouds. Nevertheless, the accuracy of these measurements should be evaluated, taking into account the requirements of the Building Information Model (BIM). This paper [...] Read more.

Medium-cost devices equipped with sensors are being developed to get 3D measurements. Some allow for generating geometric models and point clouds. Nevertheless, the accuracy of these measurements should be evaluated, taking into account the requirements of the Building Information Model (BIM). This paper analyzes the uncertainty in outdoor/indoor three-dimensional coordinate measures and point clouds (using Spherical Accuracy Standard (SAS) methods) for Eyes Map, a medium-cost tablet manufactured by e-Capture Research & Development Company, Mérida, Spain. To achieve it, in outdoor tests, by means of this device, the coordinates of targets were measured from 1 to 6 m and cloud points were obtained. Subsequently, these were compared to the coordinates of the same targets measured by a Total Station. The Euclidean average distance error was 0.005–0.027 m for measurements by Photogrammetry and 0.013–0.021 m for the point clouds. All of them satisfy the tolerance for point cloud acquisition (0.051 m) according to the BIM Guide for 3D Imaging (General Services Administration); similar results are obtained in the indoor tests, with values of 0.022 m. In this paper, we establish the optimal distances for the observations in both, Photogrammetry and 3D Photomodeling modes (outdoor) and point out some working conditions to avoid in indoor environments. Finally, the authors discuss some recommendations for improving the performance and working methods of the device. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2015)

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15 pages, 1839 KiB

Open AccessArticle

ReliefF-Based EEG Sensor Selection Methods for Emotion Recognition

by Jianhai Zhang, Ming Chen, Shaokai Zhao, Sanqing Hu, Zhiguo Shi and Yu Cao

Sensors 2016, 16(10), 1558; https://doi.org/10.3390/s16101558 - 22 Sep 2016

Cited by 163 | Viewed by 9758

Abstract

Electroencephalogram (EEG) signals recorded from sensor electrodes on the scalp can directly detect the brain dynamics in response to different emotional states. Emotion recognition from EEG signals has attracted broad attention, partly due to the rapid development of wearable computing and the needs [...] Read more.

Electroencephalogram (EEG) signals recorded from sensor electrodes on the scalp can directly detect the brain dynamics in response to different emotional states. Emotion recognition from EEG signals has attracted broad attention, partly due to the rapid development of wearable computing and the needs of a more immersive human-computer interface (HCI) environment. To improve the recognition performance, multi-channel EEG signals are usually used. A large set of EEG sensor channels will add to the computational complexity and cause users inconvenience. ReliefF-based channel selection methods were systematically investigated for EEG-based emotion recognition on a database for emotion analysis using physiological signals (DEAP). Three strategies were employed to select the best channels in classifying four emotional states (joy, fear, sadness and relaxation). Furthermore, support vector machine (SVM) was used as a classifier to validate the performance of the channel selection results. The experimental results showed the effectiveness of our methods and the comparison with the similar strategies, based on the F-score, was given. Strategies to evaluate a channel as a unity gave better performance in channel reduction with an acceptable loss of accuracy. In the third strategy, after adjusting channels’ weights according to their contribution to the classification accuracy, the number of channels was reduced to eight with a slight loss of accuracy (58.51% ± 10.05% versus the best classification accuracy 59.13% ± 11.00% using 19 channels). In addition, the study of selecting subject-independent channels, related to emotion processing, was also implemented. The sensors, selected subject-independently from frontal, parietal lobes, have been identified to provide more discriminative information associated with emotion processing, and are distributed symmetrically over the scalp, which is consistent with the existing literature. The results will make a contribution to the realization of a practical EEG-based emotion recognition system. Full article

(This article belongs to the Special Issue Security and Privacy in Sensor Networks)

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17 pages, 4419 KiB

Open AccessArticle

Micro-Doppler Signal Time-Frequency Algorithm Based on STFRFT

by Cunsuo Pang, Yan Han, Huiling Hou, Shengheng Liu and Nan Zhang

Sensors 2016, 16(10), 1559; https://doi.org/10.3390/s16101559 - 24 Sep 2016

Cited by 23 | Viewed by 6890

Abstract

This paper proposes a time-frequency algorithm based on short-time fractional order Fourier transformation (STFRFT) for identification of a complicated movement targets. This algorithm, consisting of a STFRFT order-changing and quick selection method, is effective in reducing the computation load. A multi-order STFRFT time-frequency [...] Read more.

This paper proposes a time-frequency algorithm based on short-time fractional order Fourier transformation (STFRFT) for identification of a complicated movement targets. This algorithm, consisting of a STFRFT order-changing and quick selection method, is effective in reducing the computation load. A multi-order STFRFT time-frequency algorithm is also developed that makes use of the time-frequency feature of each micro-Doppler component signal. This algorithm improves the estimation accuracy of time-frequency curve fitting through multi-order matching. Finally, experiment data were used to demonstrate STFRFT’s performance in micro-Doppler time-frequency analysis. The results validated the higher estimate accuracy of the proposed algorithm. It may be applied to an LFM (Linear frequency modulated) pulse radar, SAR (Synthetic aperture radar), or ISAR (Inverse synthetic aperture radar), for improving the probability of target recognition. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1163 KiB

Open AccessArticle

Gateway-Assisted Retransmission for Lightweight and Reliable IoT Communications

by Hui-Ling Chang, Cheng-Gang Wang, Mong-Ting Wu, Meng-Hsun Tsai and Chia-Ying Lin

Sensors 2016, 16(10), 1560; https://doi.org/10.3390/s16101560 - 22 Sep 2016

Cited by 10 | Viewed by 5907

Abstract

Message Queuing Telemetry Transport for Sensor Networks (MQTT-SN) and Constrained Application Protocol (CoAP) are two protocols supporting publish/subscribe models for IoT devices to publish messages to interested subscribers. Retransmission mechanisms are introduced to compensate for the lack of data reliability. If the device [...] Read more.

Message Queuing Telemetry Transport for Sensor Networks (MQTT-SN) and Constrained Application Protocol (CoAP) are two protocols supporting publish/subscribe models for IoT devices to publish messages to interested subscribers. Retransmission mechanisms are introduced to compensate for the lack of data reliability. If the device does not receive the acknowledgement (ACK) before retransmission timeout (RTO) expires, the device will retransmit data. Setting an appropriate RTO is important because the delay may be large or retransmission may be too frequent when the RTO is inappropriate. We propose a Gateway-assisted CoAP (GaCoAP) to dynamically compute RTO for devices. Simulation models are proposed to investigate the performance of GaCoAP compared with four other methods. The experiment results show that GaCoAP is more suitable for IoT devices. Full article

(This article belongs to the Special Issue Recent Advances in Sensor Technologies and Applications in the Web of Things (WoT))

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10 pages, 1720 KiB

Open AccessArticle

A MoS₂ Nanosheet-Based Fluorescence Biosensor for Simple and Quantitative Analysis of DNA Methylation

by Le Xiao, Li Xu, Chuan Gao, Yulin Zhang, Qunfeng Yao and Guo-Jun Zhang

Sensors 2016, 16(10), 1561; https://doi.org/10.3390/s16101561 - 22 Sep 2016

Cited by 35 | Viewed by 6745

Abstract

MoS₂ nanomaterial has unique properties, including innate affinity with ss-DNA and quenching ability for fluorescence dyes. Here, we present the development of a simple fluorescence biosensor based on water-soluble MoS₂ nanosheets and restriction endonuclease BstUI for methylation analysis of p16 promoter. [...] Read more.

MoS₂ nanomaterial has unique properties, including innate affinity with ss-DNA and quenching ability for fluorescence dyes. Here, we present the development of a simple fluorescence biosensor based on water-soluble MoS₂ nanosheets and restriction endonuclease BstUI for methylation analysis of p16 promoter. The biosensing platform exhibited excellent sensitivity in detecting DNA with a linear range of 100 pM~20 nM and a detection limit of 140 pM. More importantly, our method could distinguish as low as 1% difference in methylation level. Compared with previous methylation analysis, our design is both time saving and simple to operate, avoiding the limitations of PCR-based assays without compromising performance. Full article

(This article belongs to the Section Biosensors)

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11 pages, 689 KiB

Open AccessArticle

An Off-Grid Turbo Channel Estimation Algorithm for Millimeter Wave Communications

by Lingyi Han, Yuexing Peng, Peng Wang and Yonghui Li

Sensors 2016, 16(10), 1562; https://doi.org/10.3390/s16101562 - 22 Sep 2016

Cited by 2 | Viewed by 5173

Abstract

The bandwidth shortage has motivated the exploration of the millimeter wave (mmWave) frequency spectrum for future communication networks. To compensate for the severe propagation attenuation in the mmWave band, massive antenna arrays can be adopted at both the transmitter and receiver to provide [...] Read more.

The bandwidth shortage has motivated the exploration of the millimeter wave (mmWave) frequency spectrum for future communication networks. To compensate for the severe propagation attenuation in the mmWave band, massive antenna arrays can be adopted at both the transmitter and receiver to provide large array gains via directional beamforming. To achieve such array gains, channel estimation (CE) with high resolution and low latency is of great importance for mmWave communications. However, classic super-resolution subspace CE methods such as multiple signal classification (MUSIC) and estimation of signal parameters via rotation invariant technique (ESPRIT) cannot be applied here due to RF chain constraints. In this paper, an enhanced CE algorithm is developed for the off-grid problem when quantizing the angles of mmWave channel in the spatial domain where off-grid problem refers to the scenario that angles do not lie on the quantization grids with high probability, and it results in power leakage and severe reduction of the CE performance. A new model is first proposed to formulate the off-grid problem. The new model divides the continuously-distributed angle into a quantized discrete grid part, referred to as the integral grid angle, and an offset part, termed fractional off-grid angle. Accordingly, an iterative off-grid turbo CE (IOTCE) algorithm is proposed to renew and upgrade the CE between the integral grid part and the fractional off-grid part under the Turbo principle. By fully exploiting the sparse structure of mmWave channels, the integral grid part is estimated by a soft-decoding based compressed sensing (CS) method called improved turbo compressed channel sensing (ITCCS). It iteratively updates the soft information between the linear minimum mean square error (LMMSE) estimator and the sparsity combiner. Monte Carlo simulations are presented to evaluate the performance of the proposed method, and the results show that it enhances the angle detection resolution greatly. Full article

(This article belongs to the Special Issue Millimeter Wave Wireless Communications and Networks)

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15 pages, 12638 KiB

Open AccessArticle

Indoor-Outdoor Detection Using a Smart Phone Sensor

by Weiping Wang, Qiang Chang, Qun Li, Zesen Shi and Wei Chen

Sensors 2016, 16(10), 1563; https://doi.org/10.3390/s16101563 - 22 Sep 2016

Cited by 64 | Viewed by 9432

Abstract

In the era of mobile internet, Location Based Services (LBS) have developed dramatically. Seamless Indoor and Outdoor Navigation and Localization (SNAL) has attracted a lot of attention. No single positioning technology was capable of meeting the various positioning requirements in different environments. Selecting [...] Read more.

In the era of mobile internet, Location Based Services (LBS) have developed dramatically. Seamless Indoor and Outdoor Navigation and Localization (SNAL) has attracted a lot of attention. No single positioning technology was capable of meeting the various positioning requirements in different environments. Selecting different positioning techniques for different environments is an alternative method. Detecting the users’ current environment is crucial for this technique. In this paper, we proposed to detect the indoor/outdoor environment automatically without high energy consumption. The basic idea was simple: we applied a machine learning algorithm to classify the neighboring Global System for Mobile (GSM) communication cellular base station’s signal strength in different environments, and identified the users’ current context by signal pattern recognition. We tested the algorithm in four different environments. The results showed that the proposed algorithm was capable of identifying open outdoors, semi-outdoors, light indoors and deep indoors environments with 100% accuracy using the signal strength of four nearby GSM stations. The required hardware and signal are widely available in our daily lives, implying its high compatibility and availability. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 5895 KiB

Open AccessArticle

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors

by Roberto Montanini, Antonino Recupero, Fabrizio De Domenico and Fabrizio Freni

Sensors 2016, 16(10), 1564; https://doi.org/10.3390/s16101564 - 22 Sep 2016

Cited by 16 | Viewed by 5743

Abstract

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem [...] Read more.

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1448 KiB

Open AccessArticle

Characterization of Biosensors Based on Recombinant Glutamate Oxidase: Comparison of Crosslinking Agents in Terms of Enzyme Loading and Efficiency Parameters

by Rochelle Ford, Susan J. Quinn and Robert D. O’Neill

Sensors 2016, 16(10), 1565; https://doi.org/10.3390/s16101565 - 23 Sep 2016

Cited by 23 | Viewed by 6741

Abstract

Amperometric l-glutamate (Glu) biosensors, based on both wild-type and a recombinant form of l-glutamate oxidase (GluOx), were designed and characterized in terms of enzyme-kinetic, sensitivity and stability parameters in attempts to fabricate a real-time Glu monitoring device suitable for future long-term [...] Read more.

Amperometric l-glutamate (Glu) biosensors, based on both wild-type and a recombinant form of l-glutamate oxidase (GluOx), were designed and characterized in terms of enzyme-kinetic, sensitivity and stability parameters in attempts to fabricate a real-time Glu monitoring device suitable for future long-term detection of this amino acid in biological and other complex media. A comparison of the enzyme from these two sources showed that they were similar in terms of biosensor performance. Optimization of the loading of the polycationic stabilization agent, polyethyleneimine (PEI), was established before investigating a range of crosslinking agents under different conditions: glutaraldehyde (GA), polyethylene glycol (PEG), and polyethylene glycol diglycidyl ether (PEGDE). Whereas PEI-free biosensor designs lost most of their meager Glu sensitivity after one or two days, configurations with a 2:5 ratio of dip-evaporation applications of PEI(1%):GluOx(400 U/mL) displayed a 20-fold increase in their initial sensitivity, and a decay half-life extended to 10 days. All the crosslinkers studied had no effect on initial Glu sensitivity, but enhanced biosensor stability, provided the crosslinking procedure was carried out under well-defined conditions. The resulting biosensor design based on the recombinant enzyme deposited on a permselective layer of poly-(ortho-phenylenediamine), PoPD/PEI₂/GluOx₅/PEGDE, displayed good sensitivity (LOD < 0.2 μM), response time (t_90% < 1 s) and stability over a 90-day period, making it an attractive candidate for future long-term monitoring of Glu concentration dynamics in complex media. Full article

(This article belongs to the Section Biosensors)

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12 pages, 2145 KiB

Open AccessArticle

Estimation of Energy Expenditure Using a Patch-Type Sensor Module with an Incremental Radial Basis Function Neural Network

by Meina Li, Keun-Chang Kwak and Youn Tae Kim

Sensors 2016, 16(10), 1566; https://doi.org/10.3390/s16101566 - 22 Sep 2016

Cited by 9 | Viewed by 5915

Abstract

Conventionally, indirect calorimetry has been used to estimate oxygen consumption in an effort to accurately measure human body energy expenditure. However, calorimetry requires the subject to wear a mask that is neither convenient nor comfortable. The purpose of our study is to develop [...] Read more.

Conventionally, indirect calorimetry has been used to estimate oxygen consumption in an effort to accurately measure human body energy expenditure. However, calorimetry requires the subject to wear a mask that is neither convenient nor comfortable. The purpose of our study is to develop a patch-type sensor module with an embedded incremental radial basis function neural network (RBFNN) for estimating the energy expenditure. The sensor module contains one ECG electrode and a three-axis accelerometer, and can perform real-time heart rate (HR) and movement index (MI) monitoring. The embedded incremental network includes linear regression (LR) and RBFNN based on context-based fuzzy c-means (CFCM) clustering. This incremental network is constructed by building a collection of information granules through CFCM clustering that is guided by the distribution of error of the linear part of the LR model. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

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28 pages, 3163 KiB

Open AccessArticle

A Geographical Heuristic Routing Protocol for VANETs

by Luis Urquiza-Aguiar, Carolina Tripp-Barba and Mónica Aguilar Igartua

Sensors 2016, 16(10), 1567; https://doi.org/10.3390/s16101567 - 23 Sep 2016

Cited by 12 | Viewed by 6117

Abstract

Vehicular ad hoc networks (VANETs) leverage the communication system of Intelligent Transportation Systems (ITS). Recently, Delay-Tolerant Network (DTN) routing protocols have increased their popularity among the research community for being used in non-safety VANET applications and services like traffic reporting. Vehicular DTN protocols [...] Read more.

Vehicular ad hoc networks (VANETs) leverage the communication system of Intelligent Transportation Systems (ITS). Recently, Delay-Tolerant Network (DTN) routing protocols have increased their popularity among the research community for being used in non-safety VANET applications and services like traffic reporting. Vehicular DTN protocols use geographical and local information to make forwarding decisions. However, current proposals only consider the selection of the best candidate based on a local-search. In this paper, we propose a generic Geographical Heuristic Routing (GHR) protocol that can be applied to any DTN geographical routing protocol that makes forwarding decisions hop by hop. GHR includes in its operation adaptations simulated annealing and Tabu-search meta-heuristics, which have largely been used to improve local-search results in discrete optimization. We include a complete performance evaluation of GHR in a multi-hop VANET simulation scenario for a reporting service. Our study analyzes all of the meaningful configurations of GHR and offers a statistical analysis of our findings by means of MANOVA tests. Our results indicate that the use of a Tabu list contributes to improving the packet delivery ratio by around 5% to 10%. Moreover, if Tabu is used, then the simulated annealing routing strategy gets a better performance than the selection of the best node used with carry and forwarding (default operation). Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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11 pages, 12693 KiB

Open AccessArticle

A Wireless and Batteryless Intelligent Carbon Monoxide Sensor

by Chen-Chia Chen, Gang-Neng Sung, Wen-Ching Chen, Chih-Ting Kuo, Jin-Ju Chue, Chieh-Ming Wu and Chun-Ming Huang

Sensors 2016, 16(10), 1568; https://doi.org/10.3390/s16101568 - 23 Sep 2016

Cited by 8 | Viewed by 6911

Abstract

Carbon monoxide (CO) poisoning from natural gas water heaters is a common household accident in Taiwan. We propose a wireless and batteryless intelligent CO sensor for improving the safety of operating natural gas water heaters. A micro-hydropower generator supplies power to a CO [...] Read more.

Carbon monoxide (CO) poisoning from natural gas water heaters is a common household accident in Taiwan. We propose a wireless and batteryless intelligent CO sensor for improving the safety of operating natural gas water heaters. A micro-hydropower generator supplies power to a CO sensor without battery (COSWOB) (2.5 W at a flow rate of 4.2 L/min), and the power consumption of the COSWOB is only ~13 mW. The COSWOB monitors the CO concentration in ambient conditions around natural gas water heaters and transmits it to an intelligent gateway. When the CO level reaches a dangerous level, the COSWOB alarm sounds loudly. Meanwhile, the intelligent gateway also sends a trigger to activate Wi-Fi alarms and sends notifications to the mobile device through the Internet. Our strategy can warn people indoors and outdoors, thereby reducing CO poisoning accidents. We also believe that our technique not only can be used for home security but also can be used in industrial applications (for example, to monitor leak occurrence in a pipeline). Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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20 pages, 3617 KiB

Open AccessArticle

Assessment of Receiver Signal Strength Sensing for Location Estimation Based on Fisher Information

by John Nielsen and Christopher Nielsen

Sensors 2016, 16(10), 1570; https://doi.org/10.3390/s16101570 - 24 Sep 2016

Cited by 1 | Viewed by 4159

Abstract

Currently there is almost ubiquitous availability of wireless signaling for data communications within commercial building complexes resulting in receiver signal strength (RSS) observables that are typically sufficient for generating viable location estimates of mobile wireless devices. However, while RSS observables are generally plentiful, [...] Read more.

Currently there is almost ubiquitous availability of wireless signaling for data communications within commercial building complexes resulting in receiver signal strength (RSS) observables that are typically sufficient for generating viable location estimates of mobile wireless devices. However, while RSS observables are generally plentiful, achieving an accurate estimation of location is difficult due to several factors affecting the electromagnetic coupling between the mobile antenna and the building access points that are not modeled and hence contribute to the overall estimation uncertainty. Such uncertainty is typically mitigated with a moderate redundancy of RSS sensor observations in combination with other constraints imposed on the mobile trajectory. In this paper, the Fisher Information (FI) of a set of RSS sensor observations in the context of variables related to the mobile location is developed. This provides a practical method of determining the potential location accuracy for the given set of wireless signals available. Furthermore, the information value of individual RSS measurements can be quantified and the RSS observables weighted accordingly in estimation combining algorithms. The practical utility of using FI in this context was demonstrated experimentally with an extensive set of RSS measurements recorded in an office complex. The resulting deviation of the mobile location estimation based on application of weighted likelihood processing to the experimental RSS data was shown to agree closely with the Cramer Rao bound determined from the FI analysis. Full article

(This article belongs to the Section Physical Sensors)

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41 pages, 3112 KiB

Open AccessArticle

A Novel Petri Nets-Based Modeling Method for the Interaction between the Sensor and the Geographic Environment in Emerging Sensor Networks

by Feng Zhang, Yuetong Xu and Jarong Chou

Sensors 2016, 16(10), 1571; https://doi.org/10.3390/s16101571 - 25 Sep 2016

Cited by 11 | Viewed by 6937

Abstract

The service of sensor device in Emerging Sensor Networks (ESNs) is the extension of traditional Web services. Through the sensor network, the service of sensor device can communicate directly with the entity in the geographic environment, and even impact the geographic entity directly. [...] Read more.

The service of sensor device in Emerging Sensor Networks (ESNs) is the extension of traditional Web services. Through the sensor network, the service of sensor device can communicate directly with the entity in the geographic environment, and even impact the geographic entity directly. The interaction between the sensor device in ESNs and geographic environment is very complex, and the interaction modeling is a challenging problem. This paper proposed a novel Petri Nets-based modeling method for the interaction between the sensor device and the geographic environment. The feature of the sensor device service in ESNs is more easily affected by the geographic environment than the traditional Web service. Therefore, the response time, the fault-tolerant ability and the resource consumption become important factors in the performance of the whole sensor application system. Thus, this paper classified IoT services as Sensing services and Controlling services according to the interaction between IoT service and geographic entity, and classified GIS services as data services and processing services. Then, this paper designed and analyzed service algebra and Colored Petri Nets model to modeling the geo-feature, IoT service, GIS service and the interaction process between the sensor and the geographic enviroment. At last, the modeling process is discussed by examples. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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13 pages, 6315 KiB

Open AccessArticle

A Low Power Digital Accumulation Technique for Digital-Domain CMOS TDI Image Sensor

by Changwei Yu, Kaiming Nie, Jiangtao Xu and Jing Gao

Sensors 2016, 16(10), 1572; https://doi.org/10.3390/s16101572 - 23 Sep 2016

Cited by 5 | Viewed by 6751

Abstract

In this paper, an accumulation technique suitable for digital domain CMOS time delay integration (TDI) image sensors is proposed to reduce power consumption without degrading the rate of imaging. In terms of the slight variations of quantization codes among different pixel exposures towards [...] Read more.

In this paper, an accumulation technique suitable for digital domain CMOS time delay integration (TDI) image sensors is proposed to reduce power consumption without degrading the rate of imaging. In terms of the slight variations of quantization codes among different pixel exposures towards the same object, the pixel array is divided into two groups: one is for coarse quantization of high bits only, and the other one is for fine quantization of low bits. Then, the complete quantization codes are composed of both results from the coarse-and-fine quantization. The equivalent operation comparably reduces the total required bit numbers of the quantization. In the 0.18 µm CMOS process, two versions of 16-stage digital domain CMOS TDI image sensor chains based on a 10-bit successive approximate register (SAR) analog-to-digital converter (ADC), with and without the proposed technique, are designed. The simulation results show that the average power consumption of slices of the two versions are

6.47 \times 10^{- 8}

J/line and

7.4 \times 10^{- 8}

J/line, respectively. Meanwhile, the linearity of the two versions are 99.74% and 99.99%, respectively. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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15 pages, 5456 KiB

Open AccessArticle

Design and Evaluation of Novel Textile Wearable Systems for the Surveillance of Vital Signals

by Isabel G. Trindade, José Machado da Silva, Rui Miguel, Madalena Pereira, José Lucas, Luís Oliveira, Bruno Valentim, Jorge Barreto and Manuel Santos Silva

Sensors 2016, 16(10), 1573; https://doi.org/10.3390/s16101573 - 24 Sep 2016

Cited by 47 | Viewed by 9002

Abstract

This article addresses the design, development, and evaluation of T-shirt prototypes that embed novel textile sensors for the capture of cardio and respiratory signals. The sensors are connected through textile interconnects to either an embedded custom-designed data acquisition and transmission unit or to [...] Read more.

This article addresses the design, development, and evaluation of T-shirt prototypes that embed novel textile sensors for the capture of cardio and respiratory signals. The sensors are connected through textile interconnects to either an embedded custom-designed data acquisition and transmission unit or to snap fastener terminals for connection to external monitoring devices. The performance of the T-shirt prototype is evaluated in terms of signal-to-noise ratio amplitude and signal interference caused by baseline wander and motion artefacts, through laboratory tests with subjects in standing and walking conditions. Performance tests were also conducted in a hospital environment using a T-shirt prototype connected to a commercial three-channel Holter monitoring device. The textile sensors and interconnects were realized with the assistance of an industrial six-needle digital embroidery tool and their resistance to wear addressed with normalized tests of laundering and abrasion. The performance of these wearable systems is discussed, and pathways and methods for their optimization are highlighted. Full article

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

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25 pages, 538 KiB

Open AccessArticle

Data Analytics for Smart Parking Applications

by Nicola Piovesan, Leo Turi, Enrico Toigo, Borja Martinez and Michele Rossi

Sensors 2016, 16(10), 1575; https://doi.org/10.3390/s16101575 - 23 Sep 2016

Cited by 22 | Viewed by 11287

Abstract

We consider real-life smart parking systems where parking lot occupancy data are collected from field sensor devices and sent to backend servers for further processing and usage for applications. Our objective is to make these data useful to end users, such as parking [...] Read more.

We consider real-life smart parking systems where parking lot occupancy data are collected from field sensor devices and sent to backend servers for further processing and usage for applications. Our objective is to make these data useful to end users, such as parking managers, and, ultimately, to citizens. To this end, we concoct and validate an automated classification algorithm having two objectives: (1) outlier detection: to detect sensors with anomalous behavioral patterns, i.e., outliers; and (2) clustering: to group the parking sensors exhibiting similar patterns into distinct clusters. We first analyze the statistics of real parking data, obtaining suitable simulation models for parking traces. We then consider a simple classification algorithm based on the empirical complementary distribution function of occupancy times and show its limitations. Hence, we design a more sophisticated algorithm exploiting unsupervised learning techniques (self-organizing maps). These are tuned following a supervised approach using our trace generator and are compared against other clustering schemes, namely expectation maximization, k-means clustering and DBSCAN, considering six months of data from a real sensor deployment. Our approach is found to be superior in terms of classification accuracy, while also being capable of identifying all of the outliers in the dataset. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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33 pages, 4162 KiB

Open AccessArticle

A Cluster-Based Dual-Adaptive Topology Control Approach in Wireless Sensor Networks

by Jinsong Gui, Kai Zhou and Naixue Xiong

Sensors 2016, 16(10), 1576; https://doi.org/10.3390/s16101576 - 25 Sep 2016

Cited by 15 | Viewed by 5155

Abstract

Multi-Input Multi-Output (MIMO) can improve wireless network performance. Sensors are usually single-antenna devices due to the high hardware complexity and cost, so several sensors are used to form virtual MIMO array, which is a desirable approach to efficiently take advantage of MIMO gains. [...] Read more.

Multi-Input Multi-Output (MIMO) can improve wireless network performance. Sensors are usually single-antenna devices due to the high hardware complexity and cost, so several sensors are used to form virtual MIMO array, which is a desirable approach to efficiently take advantage of MIMO gains. Also, in large Wireless Sensor Networks (WSNs), clustering can improve the network scalability, which is an effective topology control approach. The existing virtual MIMO-based clustering schemes do not either fully explore the benefits of MIMO or adaptively determine the clustering ranges. Also, clustering mechanism needs to be further improved to enhance the cluster structure life. In this paper, we propose an improved clustering scheme for virtual MIMO-based topology construction (ICV-MIMO), which can determine adaptively not only the inter-cluster transmission modes but also the clustering ranges. Through the rational division of cluster head function and the optimization of cluster head selection criteria and information exchange process, the ICV-MIMO scheme effectively reduces the network energy consumption and improves the lifetime of the cluster structure when compared with the existing typical virtual MIMO-based scheme. Moreover, the message overhead and time complexity are still in the same order of magnitude. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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17 pages, 5530 KiB

Open AccessArticle

Real-Time Performance of Mechatronic PZT Module Using Active Vibration Feedback Control

by Francesco Aggogeri, Alberto Borboni, Angelo Merlo, Nicola Pellegrini and Raffaele Ricatto

Sensors 2016, 16(10), 1577; https://doi.org/10.3390/s16101577 - 25 Sep 2016

Cited by 28 | Viewed by 6704

Abstract

This paper proposes an innovative mechatronic piezo-actuated module to control vibrations in modern machine tools. Vibrations represent one of the main issues that seriously compromise the quality of the workpiece. The active vibration control (AVC) device is composed of a host part integrated [...] Read more.

This paper proposes an innovative mechatronic piezo-actuated module to control vibrations in modern machine tools. Vibrations represent one of the main issues that seriously compromise the quality of the workpiece. The active vibration control (AVC) device is composed of a host part integrated with sensors and actuators synchronized by a regulator; it is able to make a self-assessment and adjust to alterations in the environment. In particular, an innovative smart actuator has been designed and developed to satisfy machining requirements during active vibration control. This study presents the mechatronic model based on the kinematic and dynamic analysis of the AVC device. To ensure a real time performance, a H2-LQG controller has been developed and validated by simulations involving a machine tool, PZT actuator and controller models. The Hardware in the Loop (HIL) architecture is adopted to control and attenuate the vibrations. A set of experimental tests has been performed to validate the AVC module on a commercial machine tool. The feasibility of the real time vibration damping is demonstrated and the simulation accuracy is evaluated. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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18 pages, 3897 KiB

Open AccessArticle

A Novel Zero Velocity Interval Detection Algorithm for Self-Contained Pedestrian Navigation System with Inertial Sensors

by Xiaochun Tian, Jiabin Chen, Yongqiang Han, Jianyu Shang and Nan Li

Sensors 2016, 16(10), 1578; https://doi.org/10.3390/s16101578 - 24 Sep 2016

Cited by 47 | Viewed by 6849

Abstract

Zero velocity update (ZUPT) plays an important role in pedestrian navigation algorithms with the premise that the zero velocity interval (ZVI) should be detected accurately and effectively. A novel adaptive ZVI detection algorithm based on a smoothed pseudo Wigner–Ville distribution to remove multiple [...] Read more.

Zero velocity update (ZUPT) plays an important role in pedestrian navigation algorithms with the premise that the zero velocity interval (ZVI) should be detected accurately and effectively. A novel adaptive ZVI detection algorithm based on a smoothed pseudo Wigner–Ville distribution to remove multiple frequencies intelligently (SPWVD-RMFI) is proposed in this paper. The novel algorithm adopts the SPWVD-RMFI method to extract the pedestrian gait frequency and to calculate the optimal ZVI detection threshold in real time by establishing the function relationships between the thresholds and the gait frequency; then, the adaptive adjustment of thresholds with gait frequency is realized and improves the ZVI detection precision. To put it into practice, a ZVI detection experiment is carried out; the result shows that compared with the traditional fixed threshold ZVI detection method, the adaptive ZVI detection algorithm can effectively reduce the false and missed detection rate of ZVI; this indicates that the novel algorithm has high detection precision and good robustness. Furthermore, pedestrian trajectory positioning experiments at different walking speeds are carried out to evaluate the influence of the novel algorithm on positioning precision. The results show that the ZVI detected by the adaptive ZVI detection algorithm for pedestrian trajectory calculation can achieve better performance. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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21 pages, 4612 KiB

Open AccessArticle

Gait Phase Recognition for Lower-Limb Exoskeleton with Only Joint Angular Sensors

by Du-Xin Liu, Xinyu Wu, Wenbin Du, Can Wang and Tiantian Xu

Sensors 2016, 16(10), 1579; https://doi.org/10.3390/s16101579 - 27 Sep 2016

Cited by 80 | Viewed by 13599

Abstract

Gait phase is widely used for gait trajectory generation, gait control and gait evaluation on lower-limb exoskeletons. So far, a variety of methods have been developed to identify the gait phase for lower-limb exoskeletons. Angular sensors on lower-limb exoskeletons are essential for joint [...] Read more.

Gait phase is widely used for gait trajectory generation, gait control and gait evaluation on lower-limb exoskeletons. So far, a variety of methods have been developed to identify the gait phase for lower-limb exoskeletons. Angular sensors on lower-limb exoskeletons are essential for joint closed-loop controlling; however, other types of sensors, such as plantar pressure, attitude or inertial measurement unit, are not indispensable.Therefore, to make full use of existing sensors, we propose a novel gait phase recognition method for lower-limb exoskeletons using only joint angular sensors. The method consists of two procedures. Firstly, the gait deviation distances during walking are calculated and classified by Fisher’s linear discriminant method, and one gait cycle is divided into eight gait phases. The validity of the classification results is also verified based on large gait samples. Secondly, we build a gait phase recognition model based on multilayer perceptron and train it with the phase-labeled gait data. The experimental result of cross-validation shows that the model has a 94.45% average correct rate of set (CRS) and an 87.22% average correct rate of phase (CRP) on the testing set, and it can predict the gait phase accurately. The novel method avoids installing additional sensors on the exoskeleton or human body and simplifies the sensory system of the lower-limb exoskeleton. Full article

(This article belongs to the Special Issue Wearable Biomedical Sensors)

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16 pages, 4309 KiB

Open AccessArticle

Analysis of Abnormal Intra-QRS Potentials in Signal-Averaged Electrocardiograms Using a Radial Basis Function Neural Network

by Chun-Cheng Lin

Sensors 2016, 16(10), 1580; https://doi.org/10.3390/s16101580 - 27 Sep 2016

Cited by 2 | Viewed by 4474

Abstract

Abnormal intra-QRS potentials (AIQPs) are commonly observed in patients at high risk for ventricular tachycardia. We present a method for approximating a measured QRS complex using a non-linear neural network with all radial basis functions having the same smoothness. We extracted the high [...] Read more.

Abnormal intra-QRS potentials (AIQPs) are commonly observed in patients at high risk for ventricular tachycardia. We present a method for approximating a measured QRS complex using a non-linear neural network with all radial basis functions having the same smoothness. We extracted the high frequency, but low amplitude intra-QRS potentials using the approximation error to identify possible ventricular tachycardia. With a specified number of neurons, we performed an orthogonal least squares algorithm to determine the center of each Gaussian radial basis function. We found that the AIQP estimation error arising from part of the normal QRS complex could cause clinicians to misjudge patients with ventricular tachycardia. Our results also show that it is possible to correct this misjudgment by combining multiple AIQP parameters estimated using various spread parameters and numbers of neurons. Clinical trials demonstrate that higher AIQP-to-QRS ratios in the X, Y and Z leads are visible in patients with ventricular tachycardia than in normal subjects. A linear combination of 60 AIQP-to-QRS ratios can achieve 100% specificity, 90% sensitivity, and 95.8% total prediction accuracy for diagnosing ventricular tachycardia. Full article

(This article belongs to the Special Issue Selected Papers from 2016 International Symposium on Computer, Consumer and Control (IS3C 2016))

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7 pages, 1828 KiB

Open AccessCommunication

A Human Serum-Based Enzyme-Free Continuous Glucose Monitoring Technique Using a Needle-Type Bio-Layer Interference Sensor

by Dongmin Seo, Sung-Ho Paek, Sangwoo Oh, Sungkyu Seo and Se-Hwan Paek

Sensors 2016, 16(10), 1581; https://doi.org/10.3390/s16101581 - 24 Sep 2016

Cited by 9 | Viewed by 7148

Abstract

The incidence of diabetes is continually increasing, and by 2030, it is expected to have increased by 69% and 20% in underdeveloped and developed countries, respectively. Therefore, glucose sensors are likely to remain in high demand in medical device markets. For the current [...] Read more.

The incidence of diabetes is continually increasing, and by 2030, it is expected to have increased by 69% and 20% in underdeveloped and developed countries, respectively. Therefore, glucose sensors are likely to remain in high demand in medical device markets. For the current study, we developed a needle-type bio-layer interference (BLI) sensor that can continuously monitor glucose levels. Using dialysis procedures, we were able to obtain hypoglycemic samples from commercial human serum. These dialysis-derived samples, alongside samples of normal human serum were used to evaluate the utility of the sensor for the detection of the clinical interest range of glucose concentrations (70–200 mg/dL), revealing high system performance for a wide glycemic state range (45–500 mg/dL). Reversibility and reproducibility were also tested over a range of time spans. Combined with existing BLI system technology, this sensor holds great promise for use as a wearable online continuous glucose monitoring system for patients in a hospital setting. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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18 pages, 2873 KiB

Open AccessArticle

A Wireless 32-Channel Implantable Bidirectional Brain Machine Interface

by Yi Su, Sudhamayee Routhu, Kee S. Moon, Sung Q. Lee, WooSub Youm and Yusuf Ozturk

Sensors 2016, 16(10), 1582; https://doi.org/10.3390/s16101582 - 24 Sep 2016

Cited by 34 | Viewed by 9160

Abstract

All neural information systems (NIS) rely on sensing neural activity to supply commands and control signals for computers, machines and a variety of prosthetic devices. Invasive systems achieve a high signal-to-noise ratio (SNR) by eliminating the volume conduction problems caused by tissue and [...] Read more.

All neural information systems (NIS) rely on sensing neural activity to supply commands and control signals for computers, machines and a variety of prosthetic devices. Invasive systems achieve a high signal-to-noise ratio (SNR) by eliminating the volume conduction problems caused by tissue and bone. An implantable brain machine interface (BMI) using intracortical electrodes provides excellent detection of a broad range of frequency oscillatory activities through the placement of a sensor in direct contact with cortex. This paper introduces a compact-sized implantable wireless 32-channel bidirectional brain machine interface (BBMI) to be used with freely-moving primates. The system is designed to monitor brain sensorimotor rhythms and present current stimuli with a configurable duration, frequency and amplitude in real time to the brain based on the brain activity report. The battery is charged via a novel ultrasonic wireless power delivery module developed for efficient delivery of power into a deeply-implanted system. The system was successfully tested through bench tests and in vivo tests on a behaving primate to record the local field potential (LFP) oscillation and stimulate the target area at the same time. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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11 pages, 3855 KiB

Open AccessArticle

Strain Modal Analysis of Small and Light Pipes Using Distributed Fibre Bragg Grating Sensors

by Jun Huang, Zude Zhou, Lin Zhang, Juntao Chen, Chunqian Ji and Duc Truong Pham

Sensors 2016, 16(10), 1583; https://doi.org/10.3390/s16101583 - 25 Sep 2016

Cited by 27 | Viewed by 10133

Abstract

Vibration fatigue failure is a critical problem of hydraulic pipes under severe working conditions. Strain modal testing of small and light pipes is a good option for dynamic characteristic evaluation, structural health monitoring and damage identification. Unique features such as small size, light [...] Read more.

Vibration fatigue failure is a critical problem of hydraulic pipes under severe working conditions. Strain modal testing of small and light pipes is a good option for dynamic characteristic evaluation, structural health monitoring and damage identification. Unique features such as small size, light weight, and high multiplexing capability enable Fibre Bragg Grating (FBG) sensors to measure structural dynamic responses where sensor size and placement are critical. In this paper, experimental strain modal analysis of pipes using distributed FBG sensors ispresented. Strain modal analysis and parameter identification methods are introduced. Experimental strain modal testing and finite element analysis for a cantilever pipe have been carried out. The analysis results indicate that the natural frequencies and strain mode shapes of the tested pipe acquired by FBG sensors are in good agreement with the results obtained by a reference accelerometer and simulation outputs. The strain modal parameters of a hydraulic pipe were obtained by the proposed strain modal testing method. FBG sensors have been shown to be useful in the experimental strain modal analysis of small and light pipes in mechanical, aeronautic and aerospace applications. Full article

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

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18 pages, 3499 KiB

Open AccessArticle

Electrocardiogram Signal Denoising Using Extreme-Point Symmetric Mode Decomposition and Nonlocal Means

by Xiaoying Tian, Yongshuai Li, Huan Zhou, Xiang Li, Lisha Chen and Xuming Zhang

Sensors 2016, 16(10), 1584; https://doi.org/10.3390/s16101584 - 25 Sep 2016

Cited by 20 | Viewed by 6955

Abstract

Electrocardiogram (ECG) signals contain a great deal of essential information which can be utilized by physicians for the diagnosis of heart diseases. Unfortunately, ECG signals are inevitably corrupted by noise which will severely affect the accuracy of cardiovascular disease diagnosis. Existing ECG signal [...] Read more.

Electrocardiogram (ECG) signals contain a great deal of essential information which can be utilized by physicians for the diagnosis of heart diseases. Unfortunately, ECG signals are inevitably corrupted by noise which will severely affect the accuracy of cardiovascular disease diagnosis. Existing ECG signal denoising methods based on wavelet shrinkage, empirical mode decomposition and nonlocal means (NLM) cannot provide sufficient noise reduction or well-detailed preservation, especially with high noise corruption. To address this problem, we have proposed a hybrid ECG signal denoising scheme by combining extreme-point symmetric mode decomposition (ESMD) with NLM. In the proposed method, the noisy ECG signals will first be decomposed into several intrinsic mode functions (IMFs) and adaptive global mean using ESMD. Then, the first several IMFs will be filtered by the NLM method according to the frequency of IMFs while the QRS complex detected from these IMFs as the dominant feature of the ECG signal and the remaining IMFs will be left unprocessed. The denoised IMFs and unprocessed IMFs are combined to produce the final denoised ECG signals. Experiments on both simulated ECG signals and real ECG signals from the MIT-BIH database demonstrate that the proposed method can suppress noise in ECG signals effectively while preserving the details very well, and it outperforms several state-of-the-art ECG signal denoising methods in terms of signal-to-noise ratio (SNR), root mean squared error (RMSE), percent root mean square difference (PRD) and mean opinion score (MOS) error index. Full article

(This article belongs to the Special Issue Noninvasive Biomedical Sensors)

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20 pages, 6438 KiB

Open AccessArticle

Inferring Human Activity Recognition with Ambient Sound on Wireless Sensor Nodes

by Etto L. Salomons, Paul J. M. Havinga and Henk Van Leeuwen

Sensors 2016, 16(10), 1586; https://doi.org/10.3390/s16101586 - 27 Sep 2016

Cited by 6 | Viewed by 4063

Abstract

A wireless sensor network that consists of nodes with a sound sensor can be used to obtain context awareness in home environments. However, the limited processing power of wireless nodes offers a challenge when extracting features from the signal, and subsequently, classifying the [...] Read more.

A wireless sensor network that consists of nodes with a sound sensor can be used to obtain context awareness in home environments. However, the limited processing power of wireless nodes offers a challenge when extracting features from the signal, and subsequently, classifying the source. Although multiple papers can be found on different methods of sound classification, none of these are aimed at limited hardware or take the efficiency of the algorithms into account. In this paper, we compare and evaluate several classification methods on a real sensor platform using different feature types and classifiers, in order to find an approach that results in a good classifier that can run on limited hardware. To be as realistic as possible, we trained our classifiers using sound waves from many different sources. We conclude that despite the fact that the classifiers are often of low quality due to the highly restricted hardware resources, sufficient performance can be achieved when (1) the window length for our classifiers is increased, and (2) if we apply a two-step approach that uses a refined classification after a global classification has been performed. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 8086 KiB

Open AccessArticle

Design of a Piezoelectric Accelerometer with High Sensitivity and Low Transverse Effect

by Bian Tian, Hanyue Liu, Ning Yang, Yulong Zhao and Zhuangde Jiang

Sensors 2016, 16(10), 1587; https://doi.org/10.3390/s16101587 - 26 Sep 2016

Cited by 59 | Viewed by 10744

Abstract

In order to meet the requirements of cable fault detection, a new structure of piezoelectric accelerometer was designed and analyzed in detail. The structure was composed of a seismic mass, two sensitive beams, and two added beams. Then, simulations including the maximum stress, [...] Read more.

In order to meet the requirements of cable fault detection, a new structure of piezoelectric accelerometer was designed and analyzed in detail. The structure was composed of a seismic mass, two sensitive beams, and two added beams. Then, simulations including the maximum stress, natural frequency, and output voltage were carried out. Moreover, comparisons with traditional structures of piezoelectric accelerometer were made. To verify which vibration mode is the dominant one on the acceleration and the space between the mass and glass, mode analysis and deflection analysis were carried out. Fabricated on an n-type single crystal silicon wafer, the sensor chips were wire-bonged to printed circuit boards (PCBs) and simply packaged for experiments. Finally, a vibration test was conducted. The results show that the proposed piezoelectric accelerometer has high sensitivity, low resonance frequency, and low transverse effect. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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19 pages, 5291 KiB

Open AccessArticle

Effect of Nanoparticles on Modified Screen Printed Inhibition Superoxide Dismutase Electrodes for Aluminum

by Miriam Barquero-Quirós and María Julia Arcos-Martínez

Sensors 2016, 16(10), 1588; https://doi.org/10.3390/s16101588 - 26 Sep 2016

Cited by 5 | Viewed by 5342

Abstract

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme superoxide dismutase has been developed. The oxidation signal of epinephrine substrate was affected by the presence of Al(III) ions leading to a decrease in its amperometric current. [...] Read more.

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme superoxide dismutase has been developed. The oxidation signal of epinephrine substrate was affected by the presence of Al(III) ions leading to a decrease in its amperometric current. The immobilization of the enzyme was performed with glutaraldehyde on screen-printed carbon electrodes modifiedwith tetrathiofulvalene (TTF) and different types ofnanoparticles. Nanoparticles of gold, platinum, rhodium and palladium were deposited on screen printed carbon electrodes by means of two electrochemical procedures. Nanoparticles were characterized trough scanning electronic microscopy, X-rays fluorescence, and atomic force microscopy. Palladium nanoparticles showed lower atomic force microscopy parameters and higher slope of aluminum calibration curves and were selected to perform sensor validation. The developed biosensor has a detection limit of 2.0 ± 0.2 μM for Al(III), with a reproducibility of 7.9% (n = 5). Recovery of standard reference material spiked to buffer solution was 103.8% with a relative standard deviation of 4.8% (n = 5). Recovery of tap water spiked with the standard reference material was 100.5 with a relative standard deviation of 3.4% (n = 3). The study of interfering ions has also been carried out. Full article

(This article belongs to the Special Issue Amperometric Biosensors)

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22 pages, 3910 KiB

Open AccessArticle

Enhanced RGB-D Mapping Method for Detailed 3D Indoor and Outdoor Modeling

by Shengjun Tang, Qing Zhu, Wu Chen, Walid Darwish, Bo Wu, Han Hu and Min Chen

Sensors 2016, 16(10), 1589; https://doi.org/10.3390/s16101589 - 27 Sep 2016

Cited by 33 | Viewed by 10002

Abstract

RGB-D sensors (sensors with RGB camera and Depth camera) are novel sensing systems that capture RGB images along with pixel-wise depth information. Although they are widely used in various applications, RGB-D sensors have significant drawbacks including limited measurement ranges (e.g., within 3 m) [...] Read more.

RGB-D sensors (sensors with RGB camera and Depth camera) are novel sensing systems that capture RGB images along with pixel-wise depth information. Although they are widely used in various applications, RGB-D sensors have significant drawbacks including limited measurement ranges (e.g., within 3 m) and errors in depth measurement increase with distance from the sensor with respect to 3D dense mapping. In this paper, we present a novel approach to geometrically integrate the depth scene and RGB scene to enlarge the measurement distance of RGB-D sensors and enrich the details of model generated from depth images. First, precise calibration for RGB-D Sensors is introduced. In addition to the calibration of internal and external parameters for both, IR camera and RGB camera, the relative pose between RGB camera and IR camera is also calibrated. Second, to ensure poses accuracy of RGB images, a refined false features matches rejection method is introduced by combining the depth information and initial camera poses between frames of the RGB-D sensor. Then, a global optimization model is used to improve the accuracy of the camera pose, decreasing the inconsistencies between the depth frames in advance. In order to eliminate the geometric inconsistencies between RGB scene and depth scene, the scale ambiguity problem encountered during the pose estimation with RGB image sequences can be resolved by integrating the depth and visual information and a robust rigid-transformation recovery method is developed to register RGB scene to depth scene. The benefit of the proposed joint optimization method is firstly evaluated with the publicly available benchmark datasets collected with Kinect. Then, the proposed method is examined by tests with two sets of datasets collected in both outside and inside environments. The experimental results demonstrate the feasibility and robustness of the proposed method. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 16314 KiB

Open AccessArticle

Effective Waterline Detection of Unmanned Surface Vehicles Based on Optical Images

by Yangjie Wei and Yuwei Zhang

Sensors 2016, 16(10), 1590; https://doi.org/10.3390/s16101590 - 27 Sep 2016

Cited by 22 | Viewed by 6009

Abstract

Real-time and accurate detection of the sailing or water area will help realize unmanned surface vehicle (USV) systems. Although there are some methods for using optical images in USV-oriented environmental modeling, both the robustness and precision of these published waterline detection methods are [...] Read more.

Real-time and accurate detection of the sailing or water area will help realize unmanned surface vehicle (USV) systems. Although there are some methods for using optical images in USV-oriented environmental modeling, both the robustness and precision of these published waterline detection methods are comparatively low for a real USV system moving in a complicated environment. This paper proposes an efficient waterline detection method based on structure extraction and texture analysis with respect to optical images and presents a practical application to a USV system for validation. First, the basic principles of local binary patterns (LBPs) and gray level co-occurrence matrix (GLCM) were analyzed, and their advantages were integrated to calculate the texture information of river images. Then, structure extraction was introduced to preprocess the original river images so that the textures resulting from USV motion, wind, and illumination are removed. In the practical application, the waterlines of many images captured by the USV system moving along an inland river were detected with the proposed method, and the results were compared with those of edge detection and super pixel segmentation. The experimental results showed that the proposed algorithm is effective and robust. The average error of the proposed method was 1.84 pixels, and the mean square deviation was 4.57 pixels. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 2752 KiB

Open AccessArticle

Infrared LED Enhanced Spectroscopic CdZnTe Detector Working under High Fluxes of X-rays

by Jakub Pekárek, Václav Dědič, Jan Franc, Eduard Belas, Martin Rejhon, Pavel Moravec, Jan Touš and Josef Voltr

Sensors 2016, 16(10), 1591; https://doi.org/10.3390/s16101591 - 27 Sep 2016

Cited by 17 | Viewed by 5798

Abstract

This paper describes an application of infrared light-induced de-polarization applied on a polarized CdZnTe detector working under high radiation fluxes. We newly demonstrate the influence of a high flux of X-rays and simultaneous 1200-nm LED illumination on the spectroscopic properties of a CdZnTe [...] Read more.

This paper describes an application of infrared light-induced de-polarization applied on a polarized CdZnTe detector working under high radiation fluxes. We newly demonstrate the influence of a high flux of X-rays and simultaneous 1200-nm LED illumination on the spectroscopic properties of a CdZnTe detector. CdZnTe detectors operating under high radiation fluxes usually suffer from the polarization effect, which occurs due to a screening of the internal electric field by a positive space charge caused by photogenerated holes trapped at a deep level. Polarization results in the degradation of detector charge collection efficiency. We studied the spectroscopic behavior of CdZnTe under various X-ray fluxes ranging between

5 \times 10^{5}

and

8 \times 10^{6}

photons per mm

^{2}

per second. It was observed that polarization occurs at an X-ray flux higher than

3 \times 10^{6}

mm

^{- 2}

·s

^{- 1}

. Using simultaneous illumination of the detector by a de-polarizing LED at 1200 nm, it was possible to recover X-ray spectra originally deformed by the polarization effect. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 5307 KiB

Open AccessArticle

The Design and Analysis of Split Row-Column Addressing Array for 2-D Transducer

by Xu Li, Yanping Jia, Mingyue Ding and Ming Yuchi

Sensors 2016, 16(10), 1592; https://doi.org/10.3390/s16101592 - 27 Sep 2016

Cited by 3 | Viewed by 5714

Abstract

For 3-D ultrasound imaging, the row-column addressing (RCA) with 2N connections for an N × N 2-D array makes the fabrication and interconnection simpler than the fully addressing with N² connections. However, RCA degrades the image quality because of defocusing in [...] Read more.

For 3-D ultrasound imaging, the row-column addressing (RCA) with 2N connections for an N × N 2-D array makes the fabrication and interconnection simpler than the fully addressing with N² connections. However, RCA degrades the image quality because of defocusing in signal channel direction in the transmit event. To solve this problem, a split row-column addressing scheme (SRCA) is proposed in this paper. Rather than connecting all the elements in the signal channel direction together, this scheme divides the elements in the signal channel direction into several disconnected blocks, thus enables focusing beam access in both signal channel and switch channel directions. Selecting an appropriate split scheme is the key for SRCA to maintaining a reasonable tradeoff between the image quality and the number of connections. Various split schemes for a 32 × 32 array are fully investigated with point spread function (PSF) analysis and imaging simulation. The result shows the split scheme with five blocks (4, 6, 12, 6, and 4 elements of each block) can provide similar image quality to fully addressing. The splitting schemes for different array sizes from 16 × 16 to 96 × 96 are also discussed. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 6168 KiB

Open AccessArticle

Design of a Sub-Picosecond Jitter with Adjustable-Range CMOS Delay-Locked Loop for High-Speed and Low-Power Applications

by Bilal I. Abdulrazzaq, Omar J. Ibrahim, Shoji Kawahito, Roslina M. Sidek, Suhaidi Shafie, Nurul Amziah Md. Yunus, Lini Lee and Izhal Abdul Halin

Sensors 2016, 16(10), 1593; https://doi.org/10.3390/s16101593 - 28 Sep 2016

Cited by 3 | Viewed by 7795

Abstract

A Delay-Locked Loop (DLL) with a modified charge pump circuit is proposed for generating high-resolution linear delay steps with sub-picosecond jitter performance and adjustable delay range. The small-signal model of the modified charge pump circuit is analyzed to bring forth the relationship between [...] Read more.

A Delay-Locked Loop (DLL) with a modified charge pump circuit is proposed for generating high-resolution linear delay steps with sub-picosecond jitter performance and adjustable delay range. The small-signal model of the modified charge pump circuit is analyzed to bring forth the relationship between the DLL’s internal control voltage and output time delay. Circuit post-layout simulation shows that a 0.97 ps delay step within a 69 ps delay range with 0.26 ps Root-Mean Square (RMS) jitter performance is achievable using a standard 0.13 µm Complementary Metal-Oxide Semiconductor (CMOS) process. The post-layout simulation results show that the power consumption of the proposed DLL architecture’s circuit is 0.1 mW when the DLL is operated at 2 GHz. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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25 pages, 4288 KiB

Open AccessArticle

Multi-Frequency Target Detection Techniques for DVB-T Based Passive Radar Sensors

by Tatiana Martelli, Fabiola Colone, Enrico Tilli and Annarita Di Lallo

Sensors 2016, 16(10), 1594; https://doi.org/10.3390/s16101594 - 28 Sep 2016

Cited by 37 | Viewed by 6987

Abstract

This paper investigates the possibility to improve target detection capability in a DVB-T- based passive radar sensor by jointly exploiting multiple digital television channels broadcast by the same transmitter of opportunity. Based on the remarkable results obtained by such a multi-frequency approach using [...] Read more.

This paper investigates the possibility to improve target detection capability in a DVB-T- based passive radar sensor by jointly exploiting multiple digital television channels broadcast by the same transmitter of opportunity. Based on the remarkable results obtained by such a multi-frequency approach using other signals of opportunity (i.e., FM radio broadcast transmissions), we propose appropriate modifications to the previously devised signal processing techniques for them to be effective in the newly considered scenarios. The resulting processing schemes are extensively applied against experimental DVB-T-based passive radar data pertaining to different surveillance applications. The obtained results clearly show the effectiveness of the proposed multi-frequency approaches and demonstrate their suitability for application in the considered scenarios. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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26 pages, 10326 KiB

Open AccessArticle

Home Automation System Based on Intelligent Transducer Enablers

by Manuel Suárez-Albela, Paula Fraga-Lamas, Tiago M. Fernández-Caramés, Adriana Dapena and Miguel González-López

Sensors 2016, 16(10), 1595; https://doi.org/10.3390/s16101595 - 28 Sep 2016

Cited by 47 | Viewed by 12064

Abstract

This paper presents a novel home automation system named HASITE (Home Automation System based on Intelligent Transducer Enablers), which has been specifically designed to identify and configure transducers easily and quickly. These features are especially useful in situations where many transducers are deployed, [...] Read more.

This paper presents a novel home automation system named HASITE (Home Automation System based on Intelligent Transducer Enablers), which has been specifically designed to identify and configure transducers easily and quickly. These features are especially useful in situations where many transducers are deployed, since their setup becomes a cumbersome task that consumes a significant amount of time and human resources. HASITE simplifies the deployment of a home automation system by using wireless networks and both self-configuration and self-registration protocols. Thanks to the application of these three elements, HASITE is able to add new transducers by just powering them up. According to the tests performed in different realistic scenarios, a transducer is ready to be used in less than 13 s. Moreover, all HASITE functionalities can be accessed through an API, which also allows for the integration of third-party systems. As an example, an Android application based on the API is presented. Remote users can use it to interact with transducers by just using a regular smartphone or a tablet. Full article

(This article belongs to the Special Issue Intelligent Internet of Things (IoT) Networks)

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21 pages, 6484 KiB

Open AccessArticle

A Real-Time Web of Things Framework with Customizable Openness Considering Legacy Devices

by Shuai Zhao, Le Yu and Bo Cheng

Sensors 2016, 16(10), 1596; https://doi.org/10.3390/s16101596 - 28 Sep 2016

Cited by 9 | Viewed by 5392

Abstract

With the development of the Internet of Things (IoT), resources and applications based on it have emerged on a large scale. However, most efforts are “silo” solutions where devices and applications are tightly coupled. Infrastructures are needed to connect sensors to the Internet, [...] Read more.

With the development of the Internet of Things (IoT), resources and applications based on it have emerged on a large scale. However, most efforts are “silo” solutions where devices and applications are tightly coupled. Infrastructures are needed to connect sensors to the Internet, open up and break the current application silos and move to a horizontal application mode. Based on the concept of Web of Things (WoT), many infrastructures have been proposed to integrate the physical world with the Web. However, issues such as no real-time guarantee, lack of fine-grained control of data, and the absence of explicit solutions for integrating heterogeneous legacy devices, hinder their widespread and practical use. To address these issues, this paper proposes a WoT resource framework that provides the infrastructures for the customizable openness and sharing of users’ data and resources under the premise of ensuring the real-time behavior of their own applications. The proposed framework is validated by actual systems and experimental evaluations. Full article

(This article belongs to the Special Issue Recent Advances in Sensor Technologies and Applications in the Web of Things (WoT))

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9 pages, 1812 KiB

Open AccessCommunication

The Usability of a Pressure-Indicating Film to Measure the Teat Load Caused by a Collapsing Liner

by Susanne Demba, Sabrina Elsholz, Christian Ammon and Sandra Rose-Meierhöfer

Sensors 2016, 16(10), 1597; https://doi.org/10.3390/s16101597 - 28 Sep 2016

Cited by 4 | Viewed by 4882

Abstract

Prevention of damage to the teat and mastitis requires determination of the teat load caused by a collapsing liner. The aim of this study was to test a pressure-indicating film designed to measure the pressure between a collapsing liner and artificial teats. The [...] Read more.

Prevention of damage to the teat and mastitis requires determination of the teat load caused by a collapsing liner. The aim of this study was to test a pressure-indicating film designed to measure the pressure between a collapsing liner and artificial teats. The Ultra Super Low and the Extreme Low pressure-indicating films were tested on two types of artificial teat. The experiments were performed with a conventional milking cluster equipped with round silicone liners. For each teat and film type, 30 repetitions were performed. Each repetition was performed with a new piece of film. Kruskal-Wallis tests were performed to detect differences between the pressure values for the different teats. The area of regions where pressure-indication color developed was calculated to determine the most suitable film type. Both film types measured the pressure applied to both artificial teats by the teat cup liner. Thus, the pressure-indicating films can be used to measure the pressure between a collapsing liner and an artificial teat. Based on the results of the present investigation, a pressure-indicating film with the measurement ranges of both film types combined would be an optimal tool to measure the overall pressure between an artificial teat and a collapsing liner. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 7934 KiB

Open AccessArticle

Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

by Muhammad Faizan Shirazi, Kibeom Park, Ruchire Eranga Wijesinghe, Hyosang Jeong, Sangyeob Han, Pilun Kim, Mansik Jeon and Jeehyun Kim

Sensors 2016, 16(10), 1598; https://doi.org/10.3390/s16101598 - 28 Sep 2016

Cited by 48 | Viewed by 8835

Abstract

An application of spectral domain optical coherence tomography (SD-OCT) was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD) panel was examined. Two identical SD-OCT systems were utilized [...] Read more.

An application of spectral domain optical coherence tomography (SD-OCT) was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD) panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast) scanning, while a stable linear motorized translational stage was used for lateral (slow) scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are difficult to observe using visual inspection methods. The rapid inspection enabled by this setup led to the early detection of product defects on the manufacturing line, resulting in a significant improvement in the quality assurance of industrial products. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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11 pages, 2846 KiB

Open AccessArticle

Characterization of Screen-Printed Organic Electrochemical Transistors to Detect Cations of Different Sizes

by Laura Contat-Rodrigo, Clara Pérez-Fuster, José Vicente Lidón-Roger, Annalisa Bonfiglio and Eduardo García-Breijo

Sensors 2016, 16(10), 1599; https://doi.org/10.3390/s16101599 - 28 Sep 2016

Cited by 12 | Viewed by 8844

Abstract

A novel screen-printing fabrication method was used to prepare organic electrochemical transistors (OECTs) based on poly(3,4-ethylenedioxythiophene) doped with polysterene sulfonate (PEDOT:PSS). Initially, three types of these screen-printed OECTs with a different channel and gate areas ratio were compared in terms of output characteristics, [...] Read more.

A novel screen-printing fabrication method was used to prepare organic electrochemical transistors (OECTs) based on poly(3,4-ethylenedioxythiophene) doped with polysterene sulfonate (PEDOT:PSS). Initially, three types of these screen-printed OECTs with a different channel and gate areas ratio were compared in terms of output characteristics, transfer characteristics, and current modulation in a phosphate buffered saline (PBS) solution. Results confirm that transistors with a gate electrode larger than the channel exhibit higher modulation. OECTs with this geometry were therefore chosen to investigate their ion-sensitive properties in aqueous solutions of cations of different sizes (sodium and rhodamine B). The effect of the gate electrode was additionally studied by comparing these all-PEDOT:PSS transistors with OECTs with the same geometry but with a non-polarizable metal gate (Ag). The operation of the all-PEDOT:PSS OECTs yields a response that is not dependent on a Na⁺ or rhodamine concentration. The weak modulation of these transistors can be explained assuming that PEDOT:PSS behaves like a supercapacitor. In contrast, the operation of Ag-Gate OECTs yields a response that is dependent on ion concentration due to the redox reaction taking place at the gate electrode with Cl⁻ counter-ions. This indicates that, for cation detection, the response is maximized in OECTs with non-polarizable gate electrodes. Full article

(This article belongs to the Section Chemical Sensors)

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10 pages, 2210 KiB

Open AccessArticle

Colorimetric Integrated PCR Protocol for Rapid Detection of Vibrio parahaemolyticus

by Kewen Cheng, Daodong Pan, Jun Teng, Li Yao, Yingwang Ye, Feng Xue, Fan Xia and Wei Chen

Sensors 2016, 16(10), 1600; https://doi.org/10.3390/s16101600 - 28 Sep 2016

Cited by 32 | Viewed by 9181

Abstract

Rapid detection of pathogens is of great significance for food safety and disease diagnosis. A new colorimetric method for rapid and easy detection of Vibrio parahaemolyticus (V. parahaemolyticus or Vp) has been developed in this research. A specific sequence was designed and [...] Read more.

Rapid detection of pathogens is of great significance for food safety and disease diagnosis. A new colorimetric method for rapid and easy detection of Vibrio parahaemolyticus (V. parahaemolyticus or Vp) has been developed in this research. A specific sequence was designed and integrated with the forward primer for molecular detection of Vp. This specific sequence was tested and treated as the horseradish peroxidase (HRP)-mimicking DNAzyme and could be amplified during the polymerase chain reaction (PCR) process. The products of PCR including the sequence of HRP-mimicking DNAzyme could produce the distinguished color in the presence of catalysis substrates. The optical signal of the catalysis reaction, which is in a linear relationship with the initial template of Vp, could be determined with the naked eye or measured with Ultraviolet-visible (UV-vis) for qualitative and quantitative detections, respectively. Based on the optical signal intensity, rapid and easy detection of Vp was successfully achieved with satisfied sensitivity and specificity. Furthermore, the detection of tdh, trh, tlh and toxR virulence genes of two Vp species (Vp 33847 and Vp 17802) were all performed successfully with this developed colorimetric integrated PCR protocol, which demonstrated potential applicability for the rapid detection of other bacteria. Full article

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

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18 pages, 3999 KiB

Open AccessArticle

Temporal Data-Driven Sleep Scheduling and Spatial Data-Driven Anomaly Detection for Clustered Wireless Sensor Networks

by Gang Li, Bin He, Hongwei Huang and Limin Tang

Sensors 2016, 16(10), 1601; https://doi.org/10.3390/s16101601 - 28 Sep 2016

Cited by 9 | Viewed by 5372

Abstract

The spatial–temporal correlation is an important feature of sensor data in wireless sensor networks (WSNs). Most of the existing works based on the spatial–temporal correlation can be divided into two parts: redundancy reduction and anomaly detection. These two parts are pursued separately in [...] Read more.

The spatial–temporal correlation is an important feature of sensor data in wireless sensor networks (WSNs). Most of the existing works based on the spatial–temporal correlation can be divided into two parts: redundancy reduction and anomaly detection. These two parts are pursued separately in existing works. In this work, the combination of temporal data-driven sleep scheduling (TDSS) and spatial data-driven anomaly detection is proposed, where TDSS can reduce data redundancy. The TDSS model is inspired by transmission control protocol (TCP) congestion control. Based on long and linear cluster structure in the tunnel monitoring system, cooperative TDSS and spatial data-driven anomaly detection are then proposed. To realize synchronous acquisition in the same ring for analyzing the situation of every ring, TDSS is implemented in a cooperative way in the cluster. To keep the precision of sensor data, spatial data-driven anomaly detection based on the spatial correlation and Kriging method is realized to generate an anomaly indicator. The experiment results show that cooperative TDSS can realize non-uniform sensing effectively to reduce the energy consumption. In addition, spatial data-driven anomaly detection is quite significant for maintaining and improving the precision of sensor data. Full article

(This article belongs to the Special Issue Recent Advances in Sensor Technologies and Applications in the Web of Things (WoT))

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12 pages, 1722 KiB

Open AccessArticle

Broadband Cooperative Spectrum Sensing Based on Distributed Modulated Wideband Converter

by Ziyong Xu, Zhi Li and Jian Li

Sensors 2016, 16(10), 1602; https://doi.org/10.3390/s16101602 - 28 Sep 2016

Cited by 18 | Viewed by 4467

Abstract

The modulated wideband converter (MWC) is a kind of sub-Nyquist sampling system which is developed from compressed sensing theory. It accomplishes highly accurate broadband sparse signal recovery by multichannel sub-Nyquist sampling sequences. However, when the number of sparse sub-bands becomes large, the amount [...] Read more.

The modulated wideband converter (MWC) is a kind of sub-Nyquist sampling system which is developed from compressed sensing theory. It accomplishes highly accurate broadband sparse signal recovery by multichannel sub-Nyquist sampling sequences. However, when the number of sparse sub-bands becomes large, the amount of sampling channels increases proportionally. Besides, it is very hard to adjust the number of sampling channels when the sparsity changes, because its undersampling board is designed by a given sparsity. Such hardware cost and inconvenience are unacceptable in practical applications. This paper proposes a distributed modulated wideband converter (DMWC) scheme innovatively, which regards one sensor node as one sampling channel and combines MWC technology with a broadband cooperative spectrum sensing network perfectly. Being different from the MWC scheme, DMWC takes phase shift and transmission loss into account in the input terminal, which are unavoidable in practical application. Our scheme is not only able to recover the support of broadband sparse signals quickly and accurately, but also reduces the hardware cost of the single node drastically. Theoretical analysis and numerical simulations show that phase shift has no influence on the recovery of frequency support, but transmission loss degrades the recovery performance to a different extent. Nevertheless, we can increase the amount of cooperative nodes and select satisfactory nodes by a different transmission distance to improve the recovery performance. Furthermore, we can adjust the amount of cooperative nodes flexibly when the sparsity changes. It indicates DMWC is extremely effective in the broadband cooperative spectrum sensing network. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 3561 KiB

Open AccessArticle

An Impedance-Based Mold Sensor with on-Chip Optical Reference

by Poornachandra Papireddy Vinayaka, Sander Van den Driesche, Roland Blank, Muhammad Waseem Tahir, Mathias Frodl, Walter Lang and Michael J. Vellekoop

Sensors 2016, 16(10), 1603; https://doi.org/10.3390/s16101603 - 28 Sep 2016

Cited by 10 | Viewed by 11592

Abstract

A new miniaturized sensor system with an internal optical reference for the detection of mold growth is presented. The sensor chip comprises a reaction chamber provided with a culture medium that promotes the growth of mold species from mold spores. The mold detection [...] Read more.

A new miniaturized sensor system with an internal optical reference for the detection of mold growth is presented. The sensor chip comprises a reaction chamber provided with a culture medium that promotes the growth of mold species from mold spores. The mold detection is performed by measuring impedance changes with integrated electrodes fabricated inside the reaction chamber. The impedance change in the culture medium is caused by shifts in the pH (i.e., from 5.5 to 8) as the mold grows. In order to determine the absolute pH value without the need for calibration, a methyl red indicator dye has been added to the culture medium. It changes the color of the medium as the pH passes specific values. This colorimetric principle now acts as a reference measurement. It also allows the sensitivity of the impedance sensor to be established in terms of impedance change per pH unit. Major mold species that are involved in the contamination of food, paper and indoor environments, like Fusarium oxysporum, Fusarium incarnatum, Eurotium amstelodami, Aspergillus penicillioides and Aspergillus restrictus, have been successfully analyzed on-chip. Full article

(This article belongs to the Section Biosensors)

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14 pages, 4616 KiB

Open AccessArticle

A Toolbox of Genetically Encoded FRET-Based Biosensors for Rapid l-Lysine Analysis

by Victoria Steffen, Julia Otten, Susann Engelmann, Andreas Radek, Michael Limberg, Bernd W. Koenig, Stephan Noack, Wolfgang Wiechert and Martina Pohl

Sensors 2016, 16(10), 1604; https://doi.org/10.3390/s16101604 - 28 Sep 2016

Cited by 32 | Viewed by 8410

Abstract

Background: The fast development of microbial production strains for basic and fine chemicals is increasingly carried out in small scale cultivation systems to allow for higher throughput. Such parallelized systems create a need for new rapid online detection systems to quantify the respective [...] Read more.

Background: The fast development of microbial production strains for basic and fine chemicals is increasingly carried out in small scale cultivation systems to allow for higher throughput. Such parallelized systems create a need for new rapid online detection systems to quantify the respective target compound. In this regard, biosensors, especially genetically encoded Förster resonance energy transfer (FRET)-based biosensors, offer tremendous opportunities. As a proof-of-concept, we have created a toolbox of FRET-based biosensors for the ratiometric determination of l-lysine in fermentation broth. Methods: The sensor toolbox was constructed based on a sensor that consists of an optimized central lysine-/arginine-/ornithine-binding protein (LAO-BP) flanked by two fluorescent proteins (enhanced cyan fluorescent protein (ECFP), Citrine). Further sensor variants with altered affinity and sensitivity were obtained by circular permutation of the binding protein as well as the introduction of flexible and rigid linkers between the fluorescent proteins and the LAO-BP, respectively. Results: The sensor prototype was applied to monitor the extracellular l-lysine concentration of the l-lysine producing Corynebacterium glutamicum (C. glutamicum) strain DM1933 in a BioLector^® microscale cultivation device. The results matched well with data obtained by HPLC analysis and the Ninhydrin assay, demonstrating the high potential of FRET-based biosensors for high-throughput microbial bioprocess optimization. Full article

(This article belongs to the Special Issue FRET Biosensors)

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20 pages, 4237 KiB

Open AccessArticle

Towards Enhanced Gas Sensor Performance with Fluoropolymer Membranes

by Thorsten Graunke, Katrin Schmitt, Stefan Raible and Jürgen Wöllenstein

Sensors 2016, 16(10), 1605; https://doi.org/10.3390/s16101605 - 28 Sep 2016

Cited by 20 | Viewed by 11159

Abstract

In this paper we report on how to increase the selectivity of gas sensors by using fluoropolymer membranes. The mass transport of polar and non-polar gases through a polymer membrane matrix was studied by systematic selection of polymers with different degrees of fluorination, [...] Read more.

In this paper we report on how to increase the selectivity of gas sensors by using fluoropolymer membranes. The mass transport of polar and non-polar gases through a polymer membrane matrix was studied by systematic selection of polymers with different degrees of fluorination, as well as polymers whose monomers have ether groups (-O-) in addition to fluorine groups (-F). For the study, a set of application-relevant gases including H₂, CO, CO₂, NO₂, methane, ethanol, acetone, and acetaldehyde as well as various concentrations of relative humidity were used. These gases have different functional groups and polarities, yet have a similar kinetic diameter and are therefore typically difficult to separate. The concentrations of the gases were chosen according to international indicative limit values (TWA, STEL). To measure the concentration in the feed and permeate, we used tin-dioxide-based metal oxide gas sensors with palladium catalyst (SnO₂:Pd), catalytic sensors (also SnO₂:Pd-based) and thermal conductivity sensors. This allows a close examination of the interdependence of diffusion and physicochemical operating principle of the sensor. Our goal is to increase the selectivity of gas sensors by using inexpensive fluoropolymer membranes. The measurements showed that through membranes with low polarity, preferably non-polar gases are transported. Furthermore, the degree of crystallization influences the permeability and selectivity of a polymer membrane. Basically the polar polymers showed a higher permeability to water vapor and polar substances than non-polar polymer membranes. Full article

(This article belongs to the Special Issue Gas Nanosensors)

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15 pages, 1378 KiB

Open AccessArticle

A Hybrid Secure Scheme for Wireless Sensor Networks against Timing Attacks Using Continuous-Time Markov Chain and Queueing Model

by Tianhui Meng, Xiaofan Li, Sha Zhang and Yubin Zhao

Sensors 2016, 16(10), 1606; https://doi.org/10.3390/s16101606 - 28 Sep 2016

Cited by 10 | Viewed by 6075

Abstract

Wireless sensor networks (WSNs) have recently gained popularity for a wide spectrum of applications. Monitoring tasks can be performed in various environments. This may be beneficial in many scenarios, but it certainly exhibits new challenges in terms of security due to increased data [...] Read more.

Wireless sensor networks (WSNs) have recently gained popularity for a wide spectrum of applications. Monitoring tasks can be performed in various environments. This may be beneficial in many scenarios, but it certainly exhibits new challenges in terms of security due to increased data transmission over the wireless channel with potentially unknown threats. Among possible security issues are timing attacks, which are not prevented by traditional cryptographic security. Moreover, the limited energy and memory resources prohibit the use of complex security mechanisms in such systems. Therefore, balancing between security and the associated energy consumption becomes a crucial challenge. This paper proposes a secure scheme for WSNs while maintaining the requirement of the security-performance tradeoff. In order to proceed to a quantitative treatment of this problem, a hybrid continuous-time Markov chain (CTMC) and queueing model are put forward, and the tradeoff analysis of the security and performance attributes is carried out. By extending and transforming this model, the mean time to security attributes failure is evaluated. Through tradeoff analysis, we show that our scheme can enhance the security of WSNs, and the optimal rekeying rate of the performance and security tradeoff can be obtained. Full article

(This article belongs to the Special Issue Security and Privacy in Sensor Networks)

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16 pages, 5250 KiB

Open AccessArticle

Analysis on Target Detection and Classification in LTE Based Passive Forward Scattering Radar

by Raja Syamsul Azmir Raja Abdullah, Noor Hafizah Abdul Aziz, Nur Emileen Abdul Rashid, Asem Ahmad Salah and Fazirulhisyam Hashim

Sensors 2016, 16(10), 1607; https://doi.org/10.3390/s16101607 - 29 Sep 2016

Cited by 50 | Viewed by 8831

Abstract

The passive bistatic radar (PBR) system can utilize the illuminator of opportunity to enhance radar capability. By utilizing the forward scattering technique and procedure into the specific mode of PBR can provide an improvement in target detection and classification. The system is known [...] Read more.

The passive bistatic radar (PBR) system can utilize the illuminator of opportunity to enhance radar capability. By utilizing the forward scattering technique and procedure into the specific mode of PBR can provide an improvement in target detection and classification. The system is known as passive Forward Scattering Radar (FSR). The passive FSR system can exploit the peculiar advantage of the enhancement in forward scatter radar cross section (FSRCS) for target detection. Thus, the aim of this paper is to show the feasibility of passive FSR for moving target detection and classification by experimental analysis and results. The signal source is coming from the latest technology of 4G Long-Term Evolution (LTE) base station. A detailed explanation on the passive FSR receiver circuit, the detection scheme and the classification algorithm are given. In addition, the proposed passive FSR circuit employs the self-mixing technique at the receiver; hence the synchronization signal from the transmitter is not required. The experimental results confirm the passive FSR system’s capability for ground target detection and classification. Furthermore, this paper illustrates the first classification result in the passive FSR system. The great potential in the passive FSR system provides a new research area in passive radar that can be used for diverse remote monitoring applications. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 4910 KiB

Open AccessArticle

Atmospheric Measurements by Ultra-Light SpEctrometer (AMULSE) Dedicated to Vertical Profile in Situ Measurements of Carbon Dioxide (CO₂) Under Weather Balloons: Instrumental Development and Field Application

by Lilian Joly, Rabih Maamary, Thomas Decarpenterie, Julien Cousin, Nicolas Dumelié, Nicolas Chauvin, Dominique Legain, Diane Tzanos and Georges Durry

Sensors 2016, 16(10), 1609; https://doi.org/10.3390/s16101609 - 29 Sep 2016

Cited by 8 | Viewed by 7913

Abstract

The concentration of greenhouse gases in the atmosphere plays an important role in the radiative effects in the Earth’s climate system. Therefore, it is crucial to increase the number of atmospheric observations in order to quantify the natural sinks and emission sources. We [...] Read more.

The concentration of greenhouse gases in the atmosphere plays an important role in the radiative effects in the Earth’s climate system. Therefore, it is crucial to increase the number of atmospheric observations in order to quantify the natural sinks and emission sources. We report in this paper the development of a new compact lightweight spectrometer (1.8 kg) called AMULSE based on near infrared laser technology at 2.04 µm coupled to a 6-m open-path multipass cell. The measurements were made using the Wavelength Modulation Spectroscopy (WMS) technique and the spectrometer is hence dedicated to in situ measuring the vertical profiles of the CO₂ at high precision levels (σ_Allan = 0.96 ppm in 1 s integration time (1σ)) and with high temporal/spatial resolution (1 Hz/5 m) using meteorological balloons. The instrument is compact, robust, cost-effective, fully autonomous, has low-power consumption, a non-intrusive probe and is plug & play. It was first calibrated and validated in the laboratory and then used for 17 successful flights up to 10 km altitude in the region Champagne—Ardenne, France in 2014. A rate of 100% of instrument recovery was validated due to the pre-localization prediction of the Météo—France based on the flight simulation software. Full article

(This article belongs to the Special Issue Autonomous Sensors)

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20 pages, 1665 KiB

Open AccessArticle

Integration of Error Compensation of Coordinate Measuring Machines into Feature Measurement: Part I—Model Development

by Roque Calvo, Roberto D’Amato, Emilio Gómez and Rosario Domingo

Sensors 2016, 16(10), 1610; https://doi.org/10.3390/s16101610 - 29 Sep 2016

Cited by 10 | Viewed by 8223

Abstract

The development of an error compensation model for coordinate measuring machines (CMMs) and its integration into feature measurement is presented. CMMs are widespread and dependable instruments in industry and laboratories for dimensional measurement. From the tip probe sensor to the machine display, there [...] Read more.

The development of an error compensation model for coordinate measuring machines (CMMs) and its integration into feature measurement is presented. CMMs are widespread and dependable instruments in industry and laboratories for dimensional measurement. From the tip probe sensor to the machine display, there is a complex transformation of probed point coordinates through the geometrical feature model that makes the assessment of accuracy and uncertainty measurement results difficult. Therefore, error compensation is not standardized, conversely to other simpler instruments. Detailed coordinate error compensation models are generally based on CMM as a rigid-body and it requires a detailed mapping of the CMM’s behavior. In this paper a new model type of error compensation is proposed. It evaluates the error from the vectorial composition of length error by axis and its integration into the geometrical measurement model. The non-explained variability by the model is incorporated into the uncertainty budget. Model parameters are analyzed and linked to the geometrical errors and uncertainty of CMM response. Next, the outstanding measurement models of flatness, angle, and roundness are developed. The proposed models are useful for measurement improvement with easy integration into CMM signal processing, in particular in industrial environments where built-in solutions are sought. A battery of implementation tests are presented in Part II, where the experimental endorsement of the model is included. Full article

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

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13 pages, 4982 KiB

Open AccessArticle

A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range

by Wei Wang, Jiapin Chen, Aleksandar. S. Zivkovic and Huikai Xie

Sensors 2016, 16(10), 1611; https://doi.org/10.3390/s16101611 - 29 Sep 2016

Cited by 22 | Viewed by 9681

Abstract

A Fourier transform spectrometer (FTS) that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS) micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, [...] Read more.

A Fourier transform spectrometer (FTS) that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS) micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, the MEMS mirror with a footprint of 4.3 mm × 3.1 mm is based on a modified lateral-shift-free (LSF) bimorph actuator design with large piston and reduced tilting. Combined with a position-sensitive device (PSD) for tilt angle sensing, the feedback controlled MEMS mirror generates a 430 µm stable linear piston scan with the mirror plate tilting angle less than ±0.002°. The usable piston scan range is increased to 78% of the MEMS mirror’s full scan capability, and a spectral resolution of 0.55 nm at 531.9 nm wavelength, has been achieved. It is a significant improvement compared to the prior work. Full article

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

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7 pages, 2312 KiB

Open AccessArticle

Planar Indium Tin Oxide Heater for Improved Thermal Distribution for Metal Oxide Micromachined Gas Sensors

by M. Cihan Çakır, Deniz Çalışkan, Bayram Bütün and Ekmel Özbay

Sensors 2016, 16(10), 1612; https://doi.org/10.3390/s16101612 - 29 Sep 2016

Cited by 13 | Viewed by 12051

Abstract

Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although [...] Read more.

Metal oxide gas sensors with integrated micro-hotplate structures are widely used in the industry and they are still being investigated and developed. Metal oxide gas sensors have the advantage of being sensitive to a wide range of organic and inorganic volatile compounds, although they lack selectivity. To introduce selectivity, the operating temperature of a single sensor is swept, and the measurements are fed to a discriminating algorithm. The efficiency of those data processing methods strongly depends on temperature uniformity across the active area of the sensor. To achieve this, hot plate structures with complex resistor geometries have been designed and additional heat-spreading structures have been introduced. In this work we designed and fabricated a metal oxide gas sensor integrated with a simple square planar indium tin oxide (ITO) heating element, by using conventional micromachining and thin-film deposition techniques. Power consumption–dependent surface temperature measurements were performed. A 420 °C working temperature was achieved at 120 mW power consumption. Temperature distribution uniformity was measured and a 17 °C difference between the hottest and the coldest points of the sensor at an operating temperature of 290 °C was achieved. Transient heat-up and cool-down cycle durations are measured as 40 ms and 20 ms, respectively. Full article

(This article belongs to the Special Issue Chemiresistive Sensors)

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14 pages, 3833 KiB

Open AccessArticle

Development of a Flexible Non-Metal Electrode for Cell Stimulation and Recording

by Cihun-Siyong Alex Gong, Wun-Jia Syu, Kin Fong Lei and Yih-Shiou Hwang

Sensors 2016, 16(10), 1613; https://doi.org/10.3390/s16101613 - 29 Sep 2016

Cited by 12 | Viewed by 5875

Abstract

This study presents a method of producing flexible electrodes for potentially simultaneously stimulating and measuring cellular signals in retinal cells. Currently, most multi-electrode applications rely primarily on etching, but the metals involved have a certain degree of brittleness, leaving them prone to cracking [...] Read more.

This study presents a method of producing flexible electrodes for potentially simultaneously stimulating and measuring cellular signals in retinal cells. Currently, most multi-electrode applications rely primarily on etching, but the metals involved have a certain degree of brittleness, leaving them prone to cracking under prolonged pressure. This study proposes using silver chloride ink as a conductive metal, and polydimethysiloxane (PDMS) as the substrate to provide electrodes with an increased degree of flexibility to allow them to bend. This structure is divided into the electrode layer made of PDMS and silver chloride ink, and a PDMS film coating layer. PDMS can be mixed in different proportions to modify the degree of rigidity. The proposed method involved three steps. The first segment entailed the manufacturing of the electrode, using silver chloride ink as the conductive material, and using computer software to define the electrode size and micro-engraving mechanisms to produce the electrode pattern. The resulting uniform PDMS pattern was then baked onto the model, and the flow channel was filled with the conductive material before air drying to produce the required electrode. In the second stage, we tested the electrode, using an impedance analyzer to measure electrode cyclic voltammetry and impedance. In the third phase, mechanical and biocompatibility tests were conducted to determine electrode properties. This study aims to produce a flexible, non-metallic sensing electrode which fits snugly for use in a range of measurement applications. Full article

(This article belongs to the Section Biosensors)

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23 pages, 5132 KiB

Open AccessArticle

Spectral Skyline Separation: Extended Landmark Databases and Panoramic Imaging

by Dario Differt and Ralf Möller

Sensors 2016, 16(10), 1614; https://doi.org/10.3390/s16101614 - 29 Sep 2016

Cited by 14 | Viewed by 5821

Abstract

Evidence from behavioral experiments suggests that insects use the skyline as a cue for visual navigation. However, changes of lighting conditions, over hours, days or possibly seasons, significantly affect the appearance of the sky and ground objects. One possible solution to this problem [...] Read more.

Evidence from behavioral experiments suggests that insects use the skyline as a cue for visual navigation. However, changes of lighting conditions, over hours, days or possibly seasons, significantly affect the appearance of the sky and ground objects. One possible solution to this problem is to extract the “skyline” by an illumination-invariant classification of the environment into two classes, ground objects and sky. In a previous study (Insect models of illumination-invariant skyline extraction from UV (ultraviolet) and green channels), we examined the idea of using two different color channels available for many insects (UV and green) to perform this segmentation. We found out that for suburban scenes in temperate zones, where the skyline is dominated by trees and artificial objects like houses, a “local” UV segmentation with adaptive thresholds applied to individual images leads to the most reliable classification. Furthermore, a “global” segmentation with fixed thresholds (trained on an image dataset recorded over several days) using UV-only information is only slightly worse compared to using both the UV and green channel. In this study, we address three issues: First, to enhance the limited range of environments covered by the dataset collected in the previous study, we gathered additional data samples of skylines consisting of minerals (stones, sand, earth) as ground objects. We could show that also for mineral-rich environments, UV-only segmentation achieves a quality comparable to multi-spectral (UV and green) segmentation. Second, we collected a wide variety of ground objects to examine their spectral characteristics under different lighting conditions. On the one hand, we found that the special case of diffusely-illuminated minerals increases the difficulty to reliably separate ground objects from the sky. On the other hand, the spectral characteristics of this collection of ground objects covers well with the data collected in the skyline databases, increasing, due to the increased variety of ground objects, the validity of our findings for novel environments. Third, we collected omnidirectional images, as often used for visual navigation tasks, of skylines using an UV-reflective hyperbolic mirror. We could show that “local” separation techniques can be adapted to the use of panoramic images by splitting the image into segments and finding individual thresholds for each segment. Contrarily, this is not possible for ‘global’ separation techniques. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 18196 KiB

Open AccessArticle

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee

by Sai Krishna Prabhala, Stanley Chien, Hiroki Yokota and Sohel Anwar

Sensors 2016, 16(10), 1615; https://doi.org/10.3390/s16101615 - 29 Sep 2016

Viewed by 7508

Abstract

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality [...] Read more.

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force. The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality. The results reveal that the device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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12 pages, 2677 KiB

Open AccessArticle

Arbitrarily Accessible 3D Microfluidic Device for Combinatorial High-Throughput Drug Screening

by Zhuofa Chen, Weizhi Li, Gihoon Choi, Xiaonan Yang, Jun Miao, Liwang Cui and Weihua Guan

Sensors 2016, 16(10), 1616; https://doi.org/10.3390/s16101616 - 29 Sep 2016

Cited by 20 | Viewed by 7497

Abstract

Microfluidics-based drug-screening systems have enabled efficient and high-throughput drug screening, but their routine uses in ordinary labs are limited due to the complexity involved in device fabrication and system setup. In this work, we report an easy-to-use and low-cost arbitrarily accessible 3D microfluidic [...] Read more.

Microfluidics-based drug-screening systems have enabled efficient and high-throughput drug screening, but their routine uses in ordinary labs are limited due to the complexity involved in device fabrication and system setup. In this work, we report an easy-to-use and low-cost arbitrarily accessible 3D microfluidic device that can be easily adopted by various labs to perform combinatorial assays for high-throughput drug screening. The device is capable of precisely performing automatic and simultaneous reagent loading and aliquoting tasks and performing multistep assays with arbitrary sequences. The device is not intended to compete with other microfluidic technologies regarding ultra-low reaction volume. Instead, its freedom from tubing or pumping systems and easy operation makes it an ideal platform for routine high-throughput drug screening outside traditional microfluidic labs. The functionality and quantitative reliability of the 3D microfluidic device were demonstrated with a histone acetyltransferase-based drug-screening assay using the recombinant Plasmodium falciparum GCN5 enzyme, benchmarked with a traditional microtiter plate-based method. This arbitrarily accessible, multistep capable, low-cost, and easy-to-use device can be widely adopted in various combinatorial assays beyond high-throughput drug screening. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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26 pages, 885 KiB

Open AccessArticle

Ontology-Based High-Level Context Inference for Human Behavior Identification

by Claudia Villalonga, Muhammad Asif Razzaq, Wajahat Ali Khan, Hector Pomares, Ignacio Rojas, Sungyoung Lee and Oresti Banos

Sensors 2016, 16(10), 1617; https://doi.org/10.3390/s16101617 - 29 Sep 2016

Cited by 22 | Viewed by 7642

Abstract

Recent years have witnessed a huge progress in the automatic identification of individual primitives of human behavior, such as activities or locations. However, the complex nature of human behavior demands more abstract contextual information for its analysis. This work presents an ontology-based method [...] Read more.

Recent years have witnessed a huge progress in the automatic identification of individual primitives of human behavior, such as activities or locations. However, the complex nature of human behavior demands more abstract contextual information for its analysis. This work presents an ontology-based method that combines low-level primitives of behavior, namely activity, locations and emotions, unprecedented to date, to intelligently derive more meaningful high-level context information. The paper contributes with a new open ontology describing both low-level and high-level context information, as well as their relationships. Furthermore, a framework building on the developed ontology and reasoning models is presented and evaluated. The proposed method proves to be robust while identifying high-level contexts even in the event of erroneously-detected low-level contexts. Despite reasonable inference times being obtained for a relevant set of users and instances, additional work is required to scale to long-term scenarios with a large number of users. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI, IWAAL and AmIHEALTH 2015)

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23 pages, 5336 KiB

Open AccessArticle

Vehicle Maneuver Detection with Accelerometer-Based Classification

by Javier Cervantes-Villanueva, Daniel Carrillo-Zapata, Fernando Terroso-Saenz, Mercedes Valdes-Vela and Antonio F. Skarmeta

Sensors 2016, 16(10), 1618; https://doi.org/10.3390/s16101618 - 29 Sep 2016

Cited by 28 | Viewed by 6210

Abstract

In the mobile computing era, smartphones have become instrumental tools to develop innovative mobile context-aware systems. In that sense, their usage in the vehicular domain eases the development of novel and personal transportation solutions. In this frame, the present work introduces an innovative [...] Read more.

In the mobile computing era, smartphones have become instrumental tools to develop innovative mobile context-aware systems. In that sense, their usage in the vehicular domain eases the development of novel and personal transportation solutions. In this frame, the present work introduces an innovative mechanism to perceive the current kinematic state of a vehicle on the basis of the accelerometer data from a smartphone mounted in the vehicle. Unlike previous proposals, the introduced architecture targets the computational limitations of such devices to carry out the detection process following an incremental approach. For its realization, we have evaluated different classification algorithms to act as agents within the architecture. Finally, our approach has been tested with a real-world dataset collected by means of the ad hoc mobile application developed. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 399 KiB

Open AccessArticle

Ensemble of One-Class Classifiers for Personal Risk Detection Based on Wearable Sensor Data

by Jorge Rodríguez, Ari Y. Barrera-Animas, Luis A. Trejo, Miguel Angel Medina-Pérez and Raúl Monroy

Sensors 2016, 16(10), 1619; https://doi.org/10.3390/s16101619 - 29 Sep 2016

Cited by 14 | Viewed by 5883

Abstract

This study introduces the One-Class K-means with Randomly-projected features Algorithm (OCKRA). OCKRA is an ensemble of one-class classifiers built over multiple projections of a dataset according to random feature subsets. Algorithms found in the literature spread over a wide range of applications where [...] Read more.

This study introduces the One-Class K-means with Randomly-projected features Algorithm (OCKRA). OCKRA is an ensemble of one-class classifiers built over multiple projections of a dataset according to random feature subsets. Algorithms found in the literature spread over a wide range of applications where ensembles of one-class classifiers have been satisfactorily applied; however, none is oriented to the area under our study: personal risk detection. OCKRA has been designed with the aim of improving the detection performance in the problem posed by the Personal RIsk DEtection(PRIDE) dataset. PRIDE was built based on 23 test subjects, where the data for each user were captured using a set of sensors embedded in a wearable band. The performance of OCKRA was compared against support vector machine and three versions of the Parzen window classifier. On average, experimental results show that OCKRA outperformed the other classifiers for at least 0.53% of the area under the curve (AUC). In addition, OCKRA achieved an AUC above 90% for more than 57% of the users. Full article

(This article belongs to the Special Issue Advances on Data Transmission and Analysis for Wearable Sensors Systems)

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14 pages, 10099 KiB

Open AccessArticle

Monitoring Heritage Buildings with Open Source Hardware Sensors: A Case Study of the Mosque-Cathedral of Córdoba

by Francisco Javier Mesas-Carrascosa, Daniel Verdú Santano, Jose Emilio Meroño de Larriva, Rafael Ortíz Cordero, Rafael Enrique Hidalgo Fernández and Alfonso García-Ferrer

Sensors 2016, 16(10), 1620; https://doi.org/10.3390/s16101620 - 29 Sep 2016

Cited by 45 | Viewed by 8266

Abstract

A number of physical factors can adversely affect cultural heritage. Therefore, monitoring parameters involved in the deterioration process, principally temperature and relative humidity, is useful for preventive conservation. In this study, a total of 15 microclimate stations using open source hardware were developed [...] Read more.

A number of physical factors can adversely affect cultural heritage. Therefore, monitoring parameters involved in the deterioration process, principally temperature and relative humidity, is useful for preventive conservation. In this study, a total of 15 microclimate stations using open source hardware were developed and stationed at the Mosque-Cathedral of Córdoba, which is registered with UNESCO for its outstanding universal value, to assess the behavior of interior temperature and relative humidity in relation to exterior weather conditions, public hours and interior design. Long-term monitoring of these parameters is of interest in terms of preservation and reducing the costs of future conservation strategies. Results from monitoring are presented to demonstrate the usefulness of this system. Full article

(This article belongs to the Section Remote Sensors)

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31 pages, 7657 KiB

Open AccessArticle

Assessment of Data Fusion Algorithms for Earth Observation Change Detection Processes

by Iñigo Molina, Estibaliz Martinez, Carmen Morillo, Jesus Velasco and Alvaro Jara

Sensors 2016, 16(10), 1621; https://doi.org/10.3390/s16101621 - 30 Sep 2016

Cited by 6 | Viewed by 6214

Abstract

In this work a parametric multi-sensor Bayesian data fusion approach and a Support Vector Machine (SVM) are used for a Change Detection problem. For this purpose two sets of SPOT5-PAN images have been used, which are in turn used for Change Detection Indices [...] Read more.

In this work a parametric multi-sensor Bayesian data fusion approach and a Support Vector Machine (SVM) are used for a Change Detection problem. For this purpose two sets of SPOT5-PAN images have been used, which are in turn used for Change Detection Indices (CDIs) calculation. For minimizing radiometric differences, a methodology based on zonal “invariant features” is suggested. The choice of one or the other CDI for a change detection process is a subjective task as each CDI is probably more or less sensitive to certain types of changes. Likewise, this idea might be employed to create and improve a “change map”, which can be accomplished by means of the CDI’s informational content. For this purpose, information metrics such as the Shannon Entropy and “Specific Information” have been used to weight the changes and no-changes categories contained in a certain CDI and thus introduced in the Bayesian information fusion algorithm. Furthermore, the parameters of the probability density functions (pdf’s) that best fit the involved categories have also been estimated. Conversely, these considerations are not necessary for mapping procedures based on the discriminant functions of a SVM. This work has confirmed the capabilities of probabilistic information fusion procedure under these circumstances. Full article

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

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15 pages, 2351 KiB

Open AccessArticle

Analysis of Aggregation Delay for Multisource Sensor Data with On-Off Traffic Pattern in Wireless Body Area Networks

by Un-Ha Kim, Eutteum Kong, Hyun-Ho Choi and Jung-Ryun Lee

Sensors 2016, 16(10), 1622; https://doi.org/10.3390/s16101622 - 30 Sep 2016

Cited by 17 | Viewed by 5513

Abstract

Data aggregation plays an important role to improve the transmission efficiency in wireless body area networks (WBANs); however, it inherently induces additional aggregation delay. Therefore, the effect of packet aggregation on WBAN applications, which are vulnerable to delay, must be analyzed rigorously. In [...] Read more.

Data aggregation plays an important role to improve the transmission efficiency in wireless body area networks (WBANs); however, it inherently induces additional aggregation delay. Therefore, the effect of packet aggregation on WBAN applications, which are vulnerable to delay, must be analyzed rigorously. In this paper, we analyze the packet aggregation delay for multisource sensor data with an on-off traffic pattern in WBANs. Considering two operational parameters of the aggregation threshold and aggregation timer, we calculate the probability that a packet aggregation occurs during a unit time and then derive the average aggregation delay in closed-form. The analysis results show that the aggregation delay increases as the aggregation timer or aggregation threshold increases, but is bounded below a certain level according to the number of active sensors and their on-off traffic attribute. This implies that the data aggregation technique can maximize the transmission efficiency while satisfying a given delay requirement in the WBAN system. Full article

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

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18 pages, 2871 KiB

Open AccessArticle

Amplitude Dispersion Compensation for Damage Detection Using Ultrasonic Guided Waves

by Liang Zeng, Jing Lin, Liping Huang and Ming Zhao

Sensors 2016, 16(10), 1623; https://doi.org/10.3390/s16101623 - 30 Sep 2016

Cited by 14 | Viewed by 6368

Abstract

Besides the phase and group velocities, the amplitude of guided wave mode is also frequency dependent. This amplitude dispersion also influences the performance of guided wave methods in nondestructive evaluation (NDE) and structural health monitoring (SHM). In this paper, the effects of amplitude [...] Read more.

Besides the phase and group velocities, the amplitude of guided wave mode is also frequency dependent. This amplitude dispersion also influences the performance of guided wave methods in nondestructive evaluation (NDE) and structural health monitoring (SHM). In this paper, the effects of amplitude dispersion to the spectrum and waveform of a propagating wave-packet are investigated. It is shown that the amplitude dispersion results in distortion in the spectrum of guided wave response, and thus influences the waveform of the wave-packet. To remove these effects, an amplitude dispersion compensation method is established on the basis of Vold–Kalman filter and Taylor series expansion. The performance of that method is then investigated by experimental examples. The results show that with the application of the amplitude dispersion compensation, the time reversibility could be preserved, which ensures the applicability of the time reversal method for damage detection. Besides, through amplitude dispersion compensation, the testing resolution of guided waves could be improved, so that the structural features located in the close proximity may be separately identified. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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18 pages, 16921 KiB

Open AccessArticle

Assessment of Atmospheric Algorithms to Retrieve Vegetation in Natural Protected Areas Using Multispectral High Resolution Imagery

by Javier Marcello, Francisco Eugenio, Ulises Perdomo and Anabella Medina

Sensors 2016, 16(10), 1624; https://doi.org/10.3390/s16101624 - 30 Sep 2016

Cited by 35 | Viewed by 6967

Abstract

The precise mapping of vegetation covers in semi-arid areas is a complex task as this type of environment consists of sparse vegetation mainly composed of small shrubs. The launch of high resolution satellites, with additional spectral bands and the ability to alter the [...] Read more.

The precise mapping of vegetation covers in semi-arid areas is a complex task as this type of environment consists of sparse vegetation mainly composed of small shrubs. The launch of high resolution satellites, with additional spectral bands and the ability to alter the viewing angle, offers a useful technology to focus on this objective. In this context, atmospheric correction is a fundamental step in the pre-processing of such remote sensing imagery and, consequently, different algorithms have been developed for this purpose over the years. They are commonly categorized as imaged-based methods as well as in more advanced physical models based on the radiative transfer theory. Despite the relevance of this topic, a few comparative studies covering several methods have been carried out using high resolution data or which are specifically applied to vegetation covers. In this work, the performance of five representative atmospheric correction algorithms (DOS, QUAC, FLAASH, ATCOR and 6S) has been assessed, using high resolution Worldview-2 imagery and field spectroradiometer data collected simultaneously, with the goal of identifying the most appropriate techniques. The study also included a detailed analysis of the parameterization influence on the final results of the correction, the aerosol model and its optical thickness being important parameters to be properly adjusted. The effects of corrections were studied in vegetation and soil sites belonging to different protected semi-arid ecosystems (high mountain and coastal areas). In summary, the superior performance of model-based algorithms, 6S in particular, has been demonstrated, achieving reflectance estimations very close to the in-situ measurements (RMSE of between 2% and 3%). Finally, an example of the importance of the atmospheric correction in the vegetation estimation in these natural areas is presented, allowing the robust mapping of species and the analysis of multitemporal variations related to the human activity and climate change. Full article

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

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12 pages, 3651 KiB

Open AccessArticle

A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils

by Jian Li, Dan Wu and Yan Han

Sensors 2016, 16(10), 1625; https://doi.org/10.3390/s16101625 - 30 Sep 2016

Cited by 10 | Viewed by 7813

Abstract

Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a [...] Read more.

Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent “I-shape” is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation. Full article

(This article belongs to the Special Issue Giant Magnetoresistive Sensors)

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20 pages, 4811 KiB

Open AccessArticle

Data-Gathering Scheme Using AUVs in Large-Scale Underwater Sensor Networks: A Multihop Approach

by Jawaad Ullah Khan and Ho-Shin Cho

Sensors 2016, 16(10), 1626; https://doi.org/10.3390/s16101626 - 30 Sep 2016

Cited by 45 | Viewed by 7205

Abstract

In this paper, we propose a data-gathering scheme for hierarchical underwater sensor networks, where multiple Autonomous Underwater Vehicles (AUVs) are deployed over large-scale coverage areas. The deployed AUVs constitute an intermittently connected multihop network through inter-AUV synchronization (in this paper, synchronization means an [...] Read more.

In this paper, we propose a data-gathering scheme for hierarchical underwater sensor networks, where multiple Autonomous Underwater Vehicles (AUVs) are deployed over large-scale coverage areas. The deployed AUVs constitute an intermittently connected multihop network through inter-AUV synchronization (in this paper, synchronization means an interconnection between nodes for communication) for forwarding data to the designated sink. In such a scenario, the performance of the multihop communication depends upon the synchronization among the vehicles. The mobility parameters of the vehicles vary continuously because of the constantly changing underwater currents. The variations in the AUV mobility parameters reduce the inter-AUV synchronization frequency contributing to delays in the multihop communication. The proposed scheme improves the AUV synchronization frequency by permitting neighboring AUVs to share their status information via a pre-selected node called an agent-node at the static layer of the network. We evaluate the proposed scheme in terms of the AUV synchronization frequency, vertical delay (node→AUV), horizontal delay (AUV→AUV), end-to-end delay, and the packet loss ratio. Simulation results show that the proposed scheme significantly reduces the aforementioned delays without the synchronization time-out process employed in conventional works. Full article

(This article belongs to the Section Sensor Networks)

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7 pages, 1037 KiB

Open AccessArticle

Compensation of Verdet Constant Temperature Dependence by Crystal Core Temperature Measurement

by Slobodan J. Petricevic and Pedja M. Mihailovic

Sensors 2016, 16(10), 1627; https://doi.org/10.3390/s16101627 - 30 Sep 2016

Cited by 12 | Viewed by 5365

Abstract

Compensation of the temperature dependence of the Verdet constant in a polarimetric extrinsic Faraday sensor is of major importance for applying the magneto-optical effect to AC current measurements and magnetic field sensing. This paper presents a method for compensating the temperature effect on [...] Read more.

Compensation of the temperature dependence of the Verdet constant in a polarimetric extrinsic Faraday sensor is of major importance for applying the magneto-optical effect to AC current measurements and magnetic field sensing. This paper presents a method for compensating the temperature effect on the Faraday rotation in a Bi₁₂GeO₂₀ crystal by sensing its optical activity effect on the polarization of a light beam. The method measures the temperature of the same volume of crystal that effects the beam polarization in a magnetic field or current sensing process. This eliminates the effect of temperature difference found in other indirect temperature compensation methods, thus allowing more accurate temperature compensation for the temperature dependence of the Verdet constant. The method does not require additional changes to an existing Δ/Σ configuration and is thus applicable for improving the performance of existing sensing devices. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2016)

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11 pages, 1980 KiB

Open AccessArticle

An Improved Manufacturing Approach for Discrete Silicon Microneedle Arrays with Tunable Height-Pitch Ratio

by Renxin Wang, Wei Wang and Zhihong Li

Sensors 2016, 16(10), 1628; https://doi.org/10.3390/s16101628 - 9 Oct 2016

Cited by 30 | Viewed by 7842

Abstract

Silicon microneedle arrays (MNAs) have been widely studied due to their potential in various transdermal applications. However, discrete MNAs, as a preferred choice to fabricate flexible penetrating devices that could adapt curved and elastic tissue, are rarely reported. Furthermore, the reported discrete MNAs [...] Read more.

Silicon microneedle arrays (MNAs) have been widely studied due to their potential in various transdermal applications. However, discrete MNAs, as a preferred choice to fabricate flexible penetrating devices that could adapt curved and elastic tissue, are rarely reported. Furthermore, the reported discrete MNAs have disadvantages lying in uniformity and height-pitch ratio. Therefore, an improved technique is developed to manufacture discrete MNA with tunable height-pitch ratio, which involves KOH-dicing-KOH process. The detailed process is sketched and simulated to illustrate the formation of microneedles. Furthermore, the undercutting of convex mask in two KOH etching steps are mathematically analyzed, in order to reveal the relationship between etching depth and mask dimension. Subsequently, fabrication results demonstrate KOH-dicing-KOH process. {321} facet is figured out as the surface of octagonal pyramid microneedle. MNAs with diverse height and pitch are also presented to identify the versatility of this approach. At last, the metallization is realized via successive electroplating. Full article

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

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23 pages, 2474 KiB

Open AccessArticle

QUEST: Eliminating Online Supervised Learning for Efficient Classification Algorithms

by Ardjan Zwartjes, Paul J. M. Havinga, Gerard J. M. Smit and Johann L. Hurink

Sensors 2016, 16(10), 1629; https://doi.org/10.3390/s16101629 - 1 Oct 2016

Cited by 5 | Viewed by 5321

Abstract

In this work, we introduce QUEST (QUantile Estimation after Supervised Training), an adaptive classification algorithm for Wireless Sensor Networks (WSNs) that eliminates the necessity for online supervised learning. Online processing is important for many sensor network applications. Transmitting raw sensor data puts high [...] Read more.

In this work, we introduce QUEST (QUantile Estimation after Supervised Training), an adaptive classification algorithm for Wireless Sensor Networks (WSNs) that eliminates the necessity for online supervised learning. Online processing is important for many sensor network applications. Transmitting raw sensor data puts high demands on the battery, reducing network life time. By merely transmitting partial results or classifications based on the sampled data, the amount of traffic on the network can be significantly reduced. Such classifications can be made by learning based algorithms using sampled data. An important issue, however, is the training phase of these learning based algorithms. Training a deployed sensor network requires a lot of communication and an impractical amount of human involvement. QUEST is a hybrid algorithm that combines supervised learning in a controlled environment with unsupervised learning on the location of deployment. Using the SITEX02 dataset, we demonstrate that the presented solution works with a performance penalty of less than 10% in 90% of the tests. Under some circumstances, it even outperforms a network of classifiers completely trained with supervised learning. As a result, the need for on-site supervised learning and communication for training is completely eliminated by our solution. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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28 pages, 17721 KiB

Open AccessArticle

A Power-Optimized Cooperative MAC Protocol for Lifetime Extension in Wireless Sensor Networks

by Kai Liu, Shan Wu, Bo Huang, Feng Liu and Zhen Xu

Sensors 2016, 16(10), 1630; https://doi.org/10.3390/s16101630 - 1 Oct 2016

Cited by 12 | Viewed by 5041

Abstract

In wireless sensor networks, in order to satisfy the requirement of long working time of energy-limited nodes, we need to design an energy-efficient and lifetime-extended medium access control (MAC) protocol. In this paper, a node cooperation mechanism that one or multiple nodes with [...] Read more.

In wireless sensor networks, in order to satisfy the requirement of long working time of energy-limited nodes, we need to design an energy-efficient and lifetime-extended medium access control (MAC) protocol. In this paper, a node cooperation mechanism that one or multiple nodes with higher channel gain and sufficient residual energy help a sender relay its data packets to its recipient is employed to achieve this objective. We first propose a transmission power optimization algorithm to prolong network lifetime by optimizing the transmission powers of the sender and its cooperative nodes to maximize their minimum residual energy after their data packet transmissions. Based on it, we propose a corresponding power-optimized cooperative MAC protocol. A cooperative node contention mechanism is designed to ensure that the sender can effectively select a group of cooperative nodes with the lowest energy consumption and the best channel quality for cooperative transmissions, thus further improving the energy efficiency. Simulation results show that compared to typical MAC protocol with direct transmissions and energy-efficient cooperative MAC protocol, the proposed cooperative MAC protocol can efficiently improve the energy efficiency and extend the network lifetime. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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18 pages, 5630 KiB

Open AccessArticle

Assessing Walking Strategies Using Insole Pressure Sensors for Stroke Survivors

by Mario Munoz-Organero, Jack Parker, Lauren Powell and Susan Mawson

Sensors 2016, 16(10), 1631; https://doi.org/10.3390/s16101631 - 1 Oct 2016

Cited by 28 | Viewed by 9761

Abstract

Insole pressure sensors capture the different forces exercised over the different parts of the sole when performing tasks standing up such as walking. Using data analysis and machine learning techniques, common patterns and strategies from different users to achieve different tasks can be [...] Read more.

Insole pressure sensors capture the different forces exercised over the different parts of the sole when performing tasks standing up such as walking. Using data analysis and machine learning techniques, common patterns and strategies from different users to achieve different tasks can be automatically extracted. In this paper, we present the results obtained for the automatic detection of different strategies used by stroke survivors when walking as integrated into an Information Communication Technology (ICT) enhanced Personalised Self-Management Rehabilitation System (PSMrS) for stroke rehabilitation. Fourteen stroke survivors and 10 healthy controls have participated in the experiment by walking six times a distance from chair to chair of approximately 10 m long. The Rivermead Mobility Index was used to assess the functional ability of each individual in the stroke survivor group. Several walking strategies are studied based on data gathered from insole pressure sensors and patterns found in stroke survivor patients are compared with average patterns found in healthy control users. A mechanism to automatically estimate a mobility index based on the similarity of the pressure patterns to a stereotyped stride is also used. Both data gathered from stroke survivors and healthy controls are used to evaluate the proposed mechanisms. The output of trained algorithms is applied to the PSMrS system to provide feedback on gait quality enabling stroke survivors to self-manage their rehabilitation. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

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12 pages, 4159 KiB

Open AccessArticle

Modeling and Control of the Redundant Parallel Adjustment Mechanism on a Deployable Antenna Panel

by Lili Tian, Hong Bao, Meng Wang and Xuechao Duan

Sensors 2016, 16(10), 1632; https://doi.org/10.3390/s16101632 - 1 Oct 2016

Cited by 3 | Viewed by 4782

Abstract

With the aim of developing multiple input and multiple output (MIMO) coupling systems with a redundant parallel adjustment mechanism on the deployable antenna panel, a structural control integrated design methodology is proposed in this paper. Firstly, the modal information from the finite element [...] Read more.

With the aim of developing multiple input and multiple output (MIMO) coupling systems with a redundant parallel adjustment mechanism on the deployable antenna panel, a structural control integrated design methodology is proposed in this paper. Firstly, the modal information from the finite element model of the structure of the antenna panel is extracted, and then the mathematical model is established with the Hamilton principle; Secondly, the discrete Linear Quadratic Regulator (LQR) controller is added to the model in order to control the actuators and adjust the shape of the panel. Finally, the engineering practicality of the modeling and control method based on finite element analysis simulation is verified. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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23 pages, 3541 KiB

Open AccessArticle

Design and Construction of a Bilateral Haptic System for the Remote Assessment of the Stiffness and Range of Motion of the Hand

by Fabio Oscari, Roberto Oboe, Omar Andres Daud Albasini, Stefano Masiero and Giulio Rosati

Sensors 2016, 16(10), 1633; https://doi.org/10.3390/s16101633 - 1 Oct 2016

Cited by 7 | Viewed by 6919

Abstract

The use of haptic devices in the rehabilitation of impaired limbs has become rather popular, given the proven effectiveness in promoting recovery. In a standard framework, such devices are used in rehabilitation centers, where patients interact with virtual tasks, presented on a screen. [...] Read more.

The use of haptic devices in the rehabilitation of impaired limbs has become rather popular, given the proven effectiveness in promoting recovery. In a standard framework, such devices are used in rehabilitation centers, where patients interact with virtual tasks, presented on a screen. To track their sessions, kinematic/dynamic parameters or performance scores are recorded. However, as Internet access is now available at almost every home and in order to reduce the hospitalization time of the patient, the idea of doing rehabilitation at home is gaining wide consent. Medical care programs can be synchronized with the home rehabilitation device; patient data can be sent to the central server that could redirect to the therapist laptop (tele-healthcare). The controversial issue is that the recorded data do not actually represent the clinical conditions of the patients according to the medical assessment scales, forcing them to frequently undergo clinical tests at the hospital. To respond to this demand, we propose the use of a bilateral master/slave haptic system that could allow the clinician, who interacts with the master, to assess remotely and in real time the clinical conditions of the patient that uses the home rehabilitation device as the slave. In this paper, we describe a proof of concept to highlight the main issues of such an application, limited to one degree of freedom, and to the measure of the stiffness and range of motion of the hand. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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17 pages, 4116 KiB

Open AccessArticle

Towards Real-Time Detection of Gait Events on Different Terrains Using Time-Frequency Analysis and Peak Heuristics Algorithm

by Hui Zhou, Ning Ji, Oluwarotimi Williams Samuel, Yafei Cao, Zheyi Zhao, Shixiong Chen and Guanglin Li

Sensors 2016, 16(10), 1634; https://doi.org/10.3390/s16101634 - 1 Oct 2016

Cited by 44 | Viewed by 7411

Abstract

Real-time detection of gait events can be applied as a reliable input to control drop foot correction devices and lower-limb prostheses. Among the different sensors used to acquire the signals associated with walking for gait event detection, the accelerometer is considered as a [...] Read more.

Real-time detection of gait events can be applied as a reliable input to control drop foot correction devices and lower-limb prostheses. Among the different sensors used to acquire the signals associated with walking for gait event detection, the accelerometer is considered as a preferable sensor due to its convenience of use, small size, low cost, reliability, and low power consumption. Based on the acceleration signals, different algorithms have been proposed to detect toe off (TO) and heel strike (HS) gait events in previous studies. While these algorithms could achieve a relatively reasonable performance in gait event detection, they suffer from limitations such as poor real-time performance and are less reliable in the cases of up stair and down stair terrains. In this study, a new algorithm is proposed to detect the gait events on three walking terrains in real-time based on the analysis of acceleration jerk signals with a time-frequency method to obtain gait parameters, and then the determination of the peaks of jerk signals using peak heuristics. The performance of the newly proposed algorithm was evaluated with eight healthy subjects when they were walking on level ground, up stairs, and down stairs. Our experimental results showed that the mean F1 scores of the proposed algorithm were above 0.98 for HS event detection and 0.95 for TO event detection on the three terrains. This indicates that the current algorithm would be robust and accurate for gait event detection on different terrains. Findings from the current study suggest that the proposed method may be a preferable option in some applications such as drop foot correction devices and leg prostheses. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 2547 KiB

Open AccessArticle

3D Printed Dry EEG Electrodes

by Sammy Krachunov and Alexander J. Casson

Sensors 2016, 16(10), 1635; https://doi.org/10.3390/s16101635 - 2 Oct 2016

Cited by 83 | Viewed by 24507

Abstract

Electroencephalography (EEG) is a procedure that records brain activity in a non-invasive manner. The cost and size of EEG devices has decreased in recent years, facilitating a growing interest in wearable EEG that can be used out-of-the-lab for a wide range of applications, [...] Read more.

Electroencephalography (EEG) is a procedure that records brain activity in a non-invasive manner. The cost and size of EEG devices has decreased in recent years, facilitating a growing interest in wearable EEG that can be used out-of-the-lab for a wide range of applications, from epilepsy diagnosis, to stroke rehabilitation, to Brain-Computer Interfaces (BCI). A major obstacle for these emerging applications is the wet electrodes, which are used as part of the EEG setup. These electrodes are attached to the human scalp using a conductive gel, which can be uncomfortable to the subject, causes skin irritation, and some gels have poor long-term stability. A solution to this problem is to use dry electrodes, which do not require conductive gel, but tend to have a higher noise floor. This paper presents a novel methodology for the design and manufacture of such dry electrodes. We manufacture the electrodes using low cost desktop 3D printers and off-the-shelf components for the first time. This allows quick and inexpensive electrode manufacturing and opens the possibility of creating electrodes that are customized for each individual user. Our 3D printed electrodes are compared against standard wet electrodes, and the performance of the proposed electrodes is suitable for BCI applications, despite the presence of additional noise. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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21 pages, 1039 KiB

Open AccessArticle

Conditional Entropy and Location Error in Indoor Localization Using Probabilistic Wi-Fi Fingerprinting

by Rafael Berkvens, Herbert Peremans and Maarten Weyn

Sensors 2016, 16(10), 1636; https://doi.org/10.3390/s16101636 - 2 Oct 2016

Cited by 26 | Viewed by 5346

Abstract

Localization systems are increasingly valuable, but their location estimates are only useful when the uncertainty of the estimate is known. This uncertainty is currently calculated as the location error given a ground truth, which is then used as a static measure in sometimes [...] Read more.

Localization systems are increasingly valuable, but their location estimates are only useful when the uncertainty of the estimate is known. This uncertainty is currently calculated as the location error given a ground truth, which is then used as a static measure in sometimes very different environments. In contrast, we propose the use of the conditional entropy of a posterior probability distribution as a complementary measure of uncertainty. This measure has the advantage of being dynamic, i.e., it can be calculated during localization based on individual sensor measurements, does not require a ground truth, and can be applied to discrete localization algorithms. Furthermore, for every consistent location estimation algorithm, both the location error and the conditional entropy measures must be related, i.e., a low entropy should always correspond with a small location error, while a high entropy can correspond with either a small or large location error. We validate this relationship experimentally by calculating both measures of uncertainty in three publicly available datasets using probabilistic Wi-Fi fingerprinting with eight different implementations of the sensor model. We show that the discrepancy between these measures, i.e., many location estimates having a high location error while simultaneously having a low conditional entropy, is largest for the least realistic implementations of the probabilistic sensor model. Based on the results presented in this paper, we conclude that conditional entropy, being dynamic, complementary to location error, and applicable to both continuous and discrete localization, provides an important extra means of characterizing a localization method. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 7827 KiB

Open AccessArticle

A Novel 3D Multilateration Sensor Using Distributed Ultrasonic Beacons for Indoor Navigation

by Rohan Kapoor, Subramanian Ramasamy, Alessandro Gardi, Chad Bieber, Larry Silverberg and Roberto Sabatini

Sensors 2016, 16(10), 1637; https://doi.org/10.3390/s16101637 - 8 Oct 2016

Cited by 29 | Viewed by 11191

Abstract

Navigation and guidance systems are a critical part of any autonomous vehicle. In this paper, a novel sensor grid using 40 KHz ultrasonic transmitters is presented for adoption in indoor 3D positioning applications. In the proposed technique, a vehicle measures the arrival time [...] Read more.

Navigation and guidance systems are a critical part of any autonomous vehicle. In this paper, a novel sensor grid using 40 KHz ultrasonic transmitters is presented for adoption in indoor 3D positioning applications. In the proposed technique, a vehicle measures the arrival time of incoming ultrasonic signals and calculates the position without broadcasting to the grid. This system allows for conducting silent or covert operations and can also be used for the simultaneous navigation of a large number of vehicles. The transmitters and receivers employed are first described. Transmission lobe patterns and receiver directionality determine the geometry of transmitter clusters. Range and accuracy of measurements dictate the number of sensors required to navigate in a given volume. Laboratory experiments were performed in which a small array of transmitters was set up and the sensor system was tested for position accuracy. The prototype system is shown to have a 1-sigma position error of about 16 cm, with errors between 7 and 11 cm in the local horizontal coordinates. This research work provides foundations for the future development of ultrasonic navigation sensors for a variety of autonomous vehicle applications. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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10 pages, 5416 KiB

Open AccessArticle

Methodological Comparison between a Novel Automatic Sampling System for Gas Chromatography versus Photoacoustic Spectroscopy for Measuring Greenhouse Gas Emissions under Field Conditions

by Alexander J. Schmithausen, Manfred Trimborn and Wolfgang Büscher

Sensors 2016, 16(10), 1638; https://doi.org/10.3390/s16101638 - 3 Oct 2016

Cited by 24 | Viewed by 7262

Abstract

Trace gases such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) are climate-related gases, and their emissions from agricultural livestock barns are not negligible. Conventional measurement systems in the field (Fourier transform infrared spectroscopy (FTIR); photoacoustic system (PAS)) are not sufficiently [...] Read more.

Trace gases such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) are climate-related gases, and their emissions from agricultural livestock barns are not negligible. Conventional measurement systems in the field (Fourier transform infrared spectroscopy (FTIR); photoacoustic system (PAS)) are not sufficiently sensitive to N2O. Laser-based measurement systems are highly accurate, but they are very expensive to purchase and maintain. One cost-effective alternative is gas chromatography (GC) with electron capture detection (ECD), but this is not suitable for field applications due to radiation. Measuring samples collected automatically under field conditions in the laboratory at a subsequent time presents many challenges. This study presents a sampling designed to promote laboratory analysis of N2O concentrations sampled under field conditions. Analyses were carried out using PAS in the field (online system) and GC in the laboratory (offline system). Both measurement systems showed a good correlation for CH4 and CO2 concentrations. Measured N2O concentrations were near the detection limit for PAS. GC achieved more reliable results for N2O in very low concentration ranges. Full article

(This article belongs to the Special Issue Sensors for Environmental Monitoring 2016)

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13 pages, 7148 KiB

Open AccessArticle

Quasi-3D Modeling and Efficient Simulation of Laminar Flows in Microfluidic Devices

by Md. Zahurul Islam and Ying Yin Tsui

Sensors 2016, 16(10), 1639; https://doi.org/10.3390/s16101639 - 3 Oct 2016

Cited by 4 | Viewed by 5963

Abstract

A quasi-3D model has been developed to simulate the flow in planar microfluidic systems with low Reynolds numbers. The model was developed by decomposing the flow profile along the height of a microfluidic system into a Fourier series. It was validated against the [...] Read more.

A quasi-3D model has been developed to simulate the flow in planar microfluidic systems with low Reynolds numbers. The model was developed by decomposing the flow profile along the height of a microfluidic system into a Fourier series. It was validated against the analytical solution for flow in a straight rectangular channel and the full 3D numerical COMSOL Navier-Stokes solver for flow in a T-channel. Comparable accuracy to the full 3D numerical solution was achieved by using only three Fourier terms with a significant decrease in computation time. The quasi-3D model was used to model flows in a micro-flow cytometer chip on a desktop computer and good agreement between the simulation and the experimental results was found. Full article

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12 pages, 1467 KiB

Open AccessArticle

An Exploration of the Metal Dependent Selectivity of a Metalloporphyrins Coated Quartz Microbalances Array

by Alexandro Catini, Raj Kumar, Rosamaria Capuano, Eugenio Martinelli, Roberto Paolesse and Corrado Di Natale

Sensors 2016, 16(10), 1640; https://doi.org/10.3390/s16101640 - 4 Oct 2016

Cited by 19 | Viewed by 4593

Abstract

Several studies in the last two decades have demonstrated that metalloporphyrins coated quartz microbalances can be fruitfully used in many diverse applications, spanning from medical diagnosis to environmental control. This large versatility is due to the combination of the ﬂexibility of metalloporphyrins molecular [...] Read more.

Several studies in the last two decades have demonstrated that metalloporphyrins coated quartz microbalances can be fruitfully used in many diverse applications, spanning from medical diagnosis to environmental control. This large versatility is due to the combination of the ﬂexibility of metalloporphyrins molecular design with the independence of the quartz microbalance signal from the interaction mechanisms. The nature of the metal atom in the metalloporphyrins is often indicated as one of the most effective tools to design differently selective sensors. However, the properties of sensors are also strongly affected by the characteristics of the transducer. In this paper, the role of the metal atom is investigated studying the response, to various volatile compounds, of six quartz microbalance sensors that are based on the same porphyrin but with different metals. Results show that, since quartz microbalances (QMB) transducers can sense all the interactions between porphyrin and volatile compounds, the metal ion does not completely determine the sensor behaviour. Rather, the sensors based on the same molecular ring but with different metal ions show a non-negligible common behaviour. However, even if limited, the different metals still confer peculiar properties to the sensors and might drive the sensor array identiﬁcation of the pool of tested volatile compounds. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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9 pages, 3848 KiB

Open AccessArticle

Research on High Sensitive D-Shaped FBG Hydrogen Sensors in Power Transformer Oil

by Ying-Ting Luo, Hong-Bin Wang, Guo-Ming Ma, Hong-Tu Song, Chengrong Li and Jun Jiang

Sensors 2016, 16(10), 1641; https://doi.org/10.3390/s16101641 - 4 Oct 2016

Cited by 29 | Viewed by 6984

Abstract

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration [...] Read more.

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG in this case is sensitive to curvature caused by stress from sensing coating, leading to Bragg wavelength shifts accordingly. The relationship between the D-FBG wavelength shift and dissolved hydrogen concentration in oil was measured experimentally in the laboratory. The detected sensitivity could be as high as 1.96 μL/L at every 1-pm wavelength shift. The results proved that a simple, polished FBG-based hydrogen sensor provides a linear measuring characteristic in the range of low hydrogen concentrations in transformer oil. Moreover, the stable hydrogen sensing performance was investigated by X-ray diffraction analysis. Full article

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

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13 pages, 6659 KiB

Open AccessArticle

Eddy-Current Sensors with Asymmetrical Point Spread Function

by Janusz Gajda and Marek Stencel

Sensors 2016, 16(10), 1642; https://doi.org/10.3390/s16101642 - 4 Oct 2016

Cited by 2 | Viewed by 5996

Abstract

This paper concerns a special type of eddy-current sensor in the form of inductive loops. Such sensors are applied in the measuring systems classifying road vehicles. They usually have a rectangular shape with dimensions of 1 × 2 m, and are installed under [...] Read more.

This paper concerns a special type of eddy-current sensor in the form of inductive loops. Such sensors are applied in the measuring systems classifying road vehicles. They usually have a rectangular shape with dimensions of 1 × 2 m, and are installed under the surface of the traffic lane. The wide Point Spread Function (PSF) of such sensors causes the information on chassis geometry, contained in the measurement signal, to be strongly averaged. This significantly limits the effectiveness of the vehicle classification. Restoration of the chassis shape, by solving the inverse problem (deconvolution), is also difficult due to the fact that it is ill-conditioned. An original approach to solving this problem is presented in this paper. It is a hardware-based solution and involves the use of inductive loops with an asymmetrical PSF. Laboratory experiments and simulation tests, conducted with models of an inductive loop, confirmed the effectiveness of the proposed solution. In this case, the principle applies that the higher the level of sensor spatial asymmetry, the greater the effectiveness of the deconvolution algorithm. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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11 pages, 3711 KiB

Open AccessArticle

Rapid On-Site Formation of a Free-Standing Flexible Optical Link for Sensing Applications

by Carlos Angulo Barrios

Sensors 2016, 16(10), 1643; https://doi.org/10.3390/s16101643 - 5 Oct 2016

Cited by 4 | Viewed by 6273

Abstract

An optical link, based on a conventional Scotch tape waveguide, for sensing applications requiring rapid on-site assembly is proposed and demonstrated. The flexible waveguide contains an integrated aluminum one-dimensional grating coupler that, when stuck on the radiative surface of a light emitting device, [...] Read more.

An optical link, based on a conventional Scotch tape waveguide, for sensing applications requiring rapid on-site assembly is proposed and demonstrated. The flexible waveguide contains an integrated aluminum one-dimensional grating coupler that, when stuck on the radiative surface of a light emitting device, allows light to be coupled in and transmitted through the tape, whose tip end is, in turn, adhered onto the photosensitive surface of a photodetector. The (de)coupling approaches exhibit high alignment tolerances that permit the formation of a free-standing flexible optical connection between surface-normal optoelectronic devices without the need of specialized equipment. As the first demonstration of a sensing application, the proposed optical link is easily configured as a cost-effective intensity-based refractometric sensor for liquid detection, which can be applicable to on-site quality and process control of, for example, beverages. Full article

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

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23 pages, 6869 KiB

Open AccessArticle

From WSN towards WoT: Open API Scheme Based on oneM2M Platforms

by Jaeho Kim, Sung-Chan Choi, Il-Yeup Ahn, Nak-Myoung Sung and Jaeseok Yun

Sensors 2016, 16(10), 1645; https://doi.org/10.3390/s16101645 - 6 Oct 2016

Cited by 16 | Viewed by 10274

Abstract

Conventional computing systems have been able to be integrated into daily objects and connected to each other due to advances in computing and network technologies, such as wireless sensor networks (WSNs), forming a global network infrastructure, called the Internet of Things (IoT). To [...] Read more.

Conventional computing systems have been able to be integrated into daily objects and connected to each other due to advances in computing and network technologies, such as wireless sensor networks (WSNs), forming a global network infrastructure, called the Internet of Things (IoT). To support the interconnection and interoperability between heterogeneous IoT systems, the availability of standardized, open application programming interfaces (APIs) is one of the key features of common software platforms for IoT devices, gateways, and servers. In this paper, we present a standardized way of extending previously-existing WSNs towards IoT systems, building the world of the Web of Things (WoT). Based on the oneM2M software platforms developed in the previous project, we introduce a well-designed open API scheme and device-speciﬁc thing adaptation software (TAS) enabling WSN elements, such as a wireless sensor node, to be accessed in a standardized way on a global scale. Three pilot services are implemented (i.e., a WiFi-enabled smart ﬂowerpot, voice-based control for ZigBee-connected home appliances, and WiFi-connected AR.Drone control) to demonstrate the practical usability of the open API scheme and TAS modules. Full details on the method of integrating WSN elements into three example systems are described at the programming code level, which is expected to help future researchers in integrating their WSN systems in IoT platforms, such as oneM2M. We hope that the ﬂexibly-deployable, easily-reusable common open API scheme and TAS-based integration method working with the oneM2M platforms will help the conventional WSNs in diverse industries evolve into the emerging WoT solutions. Full article

(This article belongs to the Special Issue Recent Advances in Sensor Technologies and Applications in the Web of Things (WoT))

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21 pages, 15005 KiB

Open AccessArticle

Analysis of Crack Image Recognition Characteristics in Concrete Structures Depending on the Illumination and Image Acquisition Distance through Outdoor Experiments

by Hyun-Woo Cho, Hyuk-Jin Yoon and Jae-Chan Yoon

Sensors 2016, 16(10), 1646; https://doi.org/10.3390/s16101646 - 6 Oct 2016

Cited by 32 | Viewed by 5676

Abstract

The effects of illumination and shooting distance on crack image recognition were investigated by examining cracks in images taken with a camera. In order to examine the effects, images of cracks in a concrete structure taken while varying the illumination and shooting distance [...] Read more.

The effects of illumination and shooting distance on crack image recognition were investigated by examining cracks in images taken with a camera. In order to examine the effects, images of cracks in a concrete structure taken while varying the illumination and shooting distance in an outdoor environment were analyzed. The images were acquired at a daytime illumination of 52,000 lx and a night illumination of 13 lx. The crack specimen images produced for the experiment were taken by increasing the shooting distance from 5 m to 100 m in each illumination. On the basis of the analysis on the modulation transfer function (MTF) and contrast sensitivity of the crack images, the effects of illumination and shooting distance on the sharpness of the crack images were investigated. The minimum crack widths that can be identified under each illumination were analyzed using MTF10 and Weber contrast 0.1, respectively. It was found that as the shooting distance increases, the effects of illumination on crack recognition become greater. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 1105 KiB

Open AccessArticle

Device Centric Throughput and QoS Optimization for IoTsin a Smart Building Using CRN-Techniques

by Saleem Aslam, Najam Ul Hasan, Adnan Shahid, Ju Wook Jang and Kyung-Geun Lee

Sensors 2016, 16(10), 1647; https://doi.org/10.3390/s16101647 - 6 Oct 2016

Cited by 15 | Viewed by 5821

Abstract

The Internet of Things (IoT) has gained an incredible importance in the communication and networking industry due to its innovative solutions and advantages in diverse domains. The IoT’ network is a network of smart physical objects: devices, vehicles, buildings, etc. The IoT has [...] Read more.

The Internet of Things (IoT) has gained an incredible importance in the communication and networking industry due to its innovative solutions and advantages in diverse domains. The IoT’ network is a network of smart physical objects: devices, vehicles, buildings, etc. The IoT has a number of applications ranging from smart home, smart surveillance to smart healthcare systems. Since IoT consists of various heterogeneous devices that exhibit different trafﬁc patterns and expect different quality of service (QoS) in terms of data rate, bit error rate and the stability index of the channel, therefore, in this paper, we formulated an optimization problem to assign channels to heterogeneous IoT devices within a smart building for the provisioning of their desired QoS. To solve this problem, a novel particle swarm optimization-based algorithm is proposed. Then, exhaustive simulations are carried out to evaluate the performance of the proposed algorithm. Simulation results demonstrate the supremacy of our proposed algorithm over the existing ones in terms of throughput, bit error rate and the stability index of the channel. Full article

(This article belongs to the Special Issue Intelligent Internet of Things (IoT) Networks)

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16 pages, 7827 KiB

Open AccessArticle

Automatic Extraction of Tunnel Lining Cross-Sections from Terrestrial Laser Scanning Point Clouds

by Yun-Jian Cheng, Wenge Qiu and Jin Lei

Sensors 2016, 16(10), 1648; https://doi.org/10.3390/s16101648 - 6 Oct 2016

Cited by 55 | Viewed by 7869

Abstract

Tunnel lining (bare-lining) cross-sections play an important role in analyzing deformations of tunnel linings. The goal of this paper is to develop an automatic method for extracting bare-lining cross-sections from terrestrial laser scanning (TLS) point clouds. First, the combination of a 2D projection [...] Read more.

Tunnel lining (bare-lining) cross-sections play an important role in analyzing deformations of tunnel linings. The goal of this paper is to develop an automatic method for extracting bare-lining cross-sections from terrestrial laser scanning (TLS) point clouds. First, the combination of a 2D projection strategy and angle criterion is used for tunnel boundary point detection, from which we estimate the two boundary lines in the X-Y plane. The initial direction of the cross-sectional plane is defined to be orthogonal to one of the two boundary lines. In order to compute the final cross-sectional plane, the direction is adjusted twice with the total least squares method and Rodrigues' rotation formula, respectively. The projection of nearby points is made onto the adjusted plane to generate tunnel cross-sections. Finally, we present a filtering algorithm (similar to the idea of the morphological erosion) to remove the non-lining points in the cross-section. The proposed method was implemented on railway tunnel data collected in Sichuan, China. Compared with an existing method of cross-sectional extraction, the proposed method can offer high accuracy and more reliable cross-sectional modeling. We also evaluated Type I and Type II errors of the proposed filter, at the same time, which gave suggestions on the parameter selection of the filter. Full article

(This article belongs to the Section Remote Sensors)

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8 pages, 2398 KiB

Open AccessArticle

Ultraviolet Imaging with Low Cost Smartphone Sensors: Development and Application of a Raspberry Pi-Based UV Camera

by Thomas C. Wilkes, Andrew J. S. McGonigle, Tom D. Pering, Angus J. Taggart, Benjamin S. White, Robert G. Bryant and Jon R. Willmott

Sensors 2016, 16(10), 1649; https://doi.org/10.3390/s16101649 - 6 Oct 2016

Cited by 71 | Viewed by 25996

Abstract

Here, we report, for what we believe to be the first time, on the modification of a low cost sensor, designed for the smartphone camera market, to develop an ultraviolet (UV) camera system. This was achieved via adaptation of Raspberry Pi cameras, which [...] Read more.

Here, we report, for what we believe to be the first time, on the modification of a low cost sensor, designed for the smartphone camera market, to develop an ultraviolet (UV) camera system. This was achieved via adaptation of Raspberry Pi cameras, which are based on back-illuminated complementary metal-oxide semiconductor (CMOS) sensors, and we demonstrated the utility of these devices for applications at wavelengths as low as 310 nm, by remotely sensing power station smokestack emissions in this spectral region. Given the very low cost of these units, ≈ USD 25, they are suitable for widespread proliferation in a variety of UV imaging applications, e.g., in atmospheric science, volcanology, forensics and surface smoothness measurements. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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18 pages, 8890 KiB

Open AccessArticle

A Steel Wire Stress Measuring Sensor Based on the Static Magnetization by Permanent Magnets

by Dongge Deng, Xinjun Wu and Su Zuo

Sensors 2016, 16(10), 1650; https://doi.org/10.3390/s16101650 - 6 Oct 2016

Cited by 13 | Viewed by 6382

Abstract

A new stress measuring sensor is proposed to evaluate the axial stress in steel wires. Without using excitation and induction coils, the sensor mainly consists of a static magnetization unit made of permanent magnets and a magnetic field measurement unit containing Hall element [...] Read more.

A new stress measuring sensor is proposed to evaluate the axial stress in steel wires. Without using excitation and induction coils, the sensor mainly consists of a static magnetization unit made of permanent magnets and a magnetic field measurement unit containing Hall element arrays. Firstly, the principle is illustrated in detail. Under the excitation of the magnetization unit, a spatially varying magnetized region in the steel wire is utilized as the measurement region. Radial and axial magnetic flux densities at different lift-offs in this region are measured by the measurement unit to calculate the differential permeability curve and magnetization curve. Feature parameters extracted from the curves are used to evaluate the axial stress. Secondly, the special stress sensor for Φ5 and Φ7 steel wires is developed accordingly. At last, the performance of the sensor is tested experimentally. Experimental results show that the sensor can measure the magnetization curve accurately with the error in the range of ±6%. Furthermore, the obtained differential permeability at working points 1200 A/m and 10000 A/m change almost linearly with the stress in steel wires, the goodness of linear fits are all higher than 0.987. Thus, the proposed steel wire stress measuring sensor is feasible. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2519 KiB

Open AccessArticle

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker

by Muhammad Azhar Hayat Nawaz, Sajid Rauf, Gaelle Catanante, Mian Hasnain Nawaz, Gilvanda Nunes, Jean Louis Marty and Akhtar Hayat

Sensors 2016, 16(10), 1651; https://doi.org/10.3390/s16101651 - 6 Oct 2016

Cited by 71 | Viewed by 8119

Abstract

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, [...] Read more.

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett– Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications. Full article

(This article belongs to the Special Issue Aptasensors 2016)

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12 pages, 2329 KiB

Open AccessArticle

Highly Selective and Ultrasensitive Turn-on Luminescence Chemosensor for Mercury (II) Determination Based on the Rhodamine 6G Derivative FC1 and Au Nanoparticles

by Romina Brasca, María C. Onaindia, Héctor C. Goicoechea, Arsenio Muñoz de la Peña and María J. Culzoni

Sensors 2016, 16(10), 1652; https://doi.org/10.3390/s16101652 - 6 Oct 2016

Cited by 8 | Viewed by 5987

Abstract

A method for the detection and quantitation of Hg2+ in aqueous samples by fluorescence spectroscopy is presented. It consists of a turn-on sensor developed by coupling Gold nanoparticles (AuNPs) with the rhodamine 6G derivative FC1, in which the response is generated by a [...] Read more.

A method for the detection and quantitation of Hg2+ in aqueous samples by fluorescence spectroscopy is presented. It consists of a turn-on sensor developed by coupling Gold nanoparticles (AuNPs) with the rhodamine 6G derivative FC1, in which the response is generated by a mercury-induced ring-opening reaction. The AuNPs were included in order to improve the sensitivity of the method towards the analyte, maintaining its high selectivity. The method was validated in terms of linearity, precision and accuracy, and applied to the quantitation of Hg2+ in Milli-Q and tap water with and without spiked analyte. The limit of detection and quantitation were 0.15 μg·L−1 and 0.43 μg·L−1, respectively, constituting a substantial improvement of sensitivity in comparison with the previously reported detection of Hg2+ with free FC1. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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21 pages, 3434 KiB

Open AccessArticle

An Enhanced Lightweight Anonymous Authentication Scheme for a Scalable Localization Roaming Service in Wireless Sensor Networks

by Youngseok Chung, Seokjin Choi, Youngsook Lee, Namje Park and Dongho Won

Sensors 2016, 16(10), 1653; https://doi.org/10.3390/s16101653 - 7 Oct 2016

Cited by 25 | Viewed by 5782

Abstract

More security concerns and complicated requirements arise in wireless sensor networks than in wired networks, due to the vulnerability caused by their openness. To address this vulnerability, anonymous authentication is an essential security mechanism for preserving privacy and providing security. Over recent years, [...] Read more.

More security concerns and complicated requirements arise in wireless sensor networks than in wired networks, due to the vulnerability caused by their openness. To address this vulnerability, anonymous authentication is an essential security mechanism for preserving privacy and providing security. Over recent years, various anonymous authentication schemes have been proposed. Most of them reveal both strengths and weaknesses in terms of security and efficiency. Recently, Farash et al. proposed a lightweight anonymous authentication scheme in ubiquitous networks, which remedies the security faults of previous schemes. However, their scheme still suffers from certain weaknesses. In this paper, we prove that Farash et al.’s scheme fails to provide anonymity, authentication, or password replacement. In addition, we propose an enhanced scheme that provides efficiency, as well as anonymity and security. Considering the limited capability of sensor nodes, we utilize only low-cost functions, such as one-way hash functions and bit-wise exclusive-OR operations. The security and lightness of the proposed scheme mean that it can be applied to roaming service in localized domains of wireless sensor networks, to provide anonymous authentication of sensor nodes. Full article

(This article belongs to the Special Issue Scalable Localization in Wireless Sensor Networks)

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14 pages, 3248 KiB

Open AccessFeature PaperArticle

Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy

by Magdalena Śliwińska, Celia Garcia-Hernandez, Mikołaj Kościński, Tomasz Dymerski, Waldemar Wardencki, Jacek Namieśnik, Małgorzata Śliwińska-Bartkowiak, Stefan Jurga, Cristina Garcia-Cabezon and Maria Luz Rodriguez-Mendez

Sensors 2016, 16(10), 1654; https://doi.org/10.3390/s16101654 - 9 Oct 2016

Cited by 15 | Viewed by 6430

Abstract

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong [...] Read more.

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin–Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content—the most important parameters to be measured in this type of liqueurs. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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10 pages, 14418 KiB

Open AccessArticle

High Sensitivity Refractive Index Sensor Based on Dual-Core Photonic Crystal Fiber with Hexagonal Lattice

by Haiyang Wang, Xin Yan, Shuguang Li, Guowen An and Xuenan Zhang

Sensors 2016, 16(10), 1655; https://doi.org/10.3390/s16101655 - 8 Oct 2016

Cited by 33 | Viewed by 7028

Abstract

A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated [...] Read more.

A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated by two air holes filled with the analyte whose refractive index is in the range of 1.33–1.41. Numerical simulation results show that the highest sensitivity can be up to 22,983 nm/RIU(refractive index unit) when the analyte refractive index is 1.41. The lowest sensitivity can reach to 21,679 nm/RIU when the analyte refractive index is 1.33. The sensor we proposed has significant advantages in the field of biomolecule detection as it provides a wide-range of detection with high sensitivity. Full article

(This article belongs to the Section Physical Sensors)

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6 pages, 1992 KiB

Open AccessArticle

Analysis of Hollow Fiber Temperature Sensor Filled with Graphene-Ag Composite Nanowire and Liquid

by Wei Xu, Jianquan Yao, Xianchao Yang, Jia Shi, Junfa Zhao and Cheng Zhang

Sensors 2016, 16(10), 1656; https://doi.org/10.3390/s16101656 - 8 Oct 2016

Cited by 10 | Viewed by 4929

Abstract

A hollow fiber temperature sensor filled with graphene-Ag composite nanowire and liquid is presented and numerically characterized. The coupling properties and sensing performances are analyzed by finite element method (FEM) using both wavelength and amplitude interrogations. Due to the asymmetrical surface plasmon resonance [...] Read more.

A hollow fiber temperature sensor filled with graphene-Ag composite nanowire and liquid is presented and numerically characterized. The coupling properties and sensing performances are analyzed by finite element method (FEM) using both wavelength and amplitude interrogations. Due to the asymmetrical surface plasmon resonance sensing (SPR) region, the designed sensor exhibits strong birefringence, supporting two separate resonance peaks in orthogonal polarizations. Results show that x-polarized resonance peak can provide much better signal to noise ratio (SNR), wavelength and amplitude sensitivities than y-polarized, which is more suitable for tempertature detecting. The graphene-Ag composite nanowire filled into the hollow fiber core can not only solve the oxidation problem but also avoid the metal coating. A wide temperature range from 22

^{\circ}

C to 47

^{\circ}

C with steps of 5

^{\circ}

C is calculated and the temperature sensitivities we obtained are 9.44 nm/

^{\circ}

C for x-polarized and 5.33 nm/

^{\circ}

C for y-polarized, much higher than other sensors of the same type. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 5124 KiB

Open AccessArticle

Design of a Wireless Sensor Module for Monitoring Conductor Galloping of Transmission Lines

by Xinbo Huang, Long Zhao and Guimin Chen

Sensors 2016, 16(10), 1657; https://doi.org/10.3390/s16101657 - 9 Oct 2016

Cited by 26 | Viewed by 4857

Abstract

Conductor galloping may cause flashovers and even tower collapses. The available conductor galloping monitoring methods often employ acceleration sensors to measure the conductor translations without considering the conductor twist. In this paper, a new sensor for monitoring conductor galloping of transmission lines based [...] Read more.

Conductor galloping may cause flashovers and even tower collapses. The available conductor galloping monitoring methods often employ acceleration sensors to measure the conductor translations without considering the conductor twist. In this paper, a new sensor for monitoring conductor galloping of transmission lines based on an inertial measurement unit and wireless communication is proposed. An inertial measurement unit is used for collecting the accelerations and angular rates of a conductor, which are further transformed into the corresponding geographic coordinate frame using a quaternion transformation to reconstruct the galloping of the conductor. Both the hardware design and the software design are described in details. The corresponding test platforms are established, and the experiments show the feasibility and accuracy of the proposed monitoring sensor. The field operation of the proposed sensor in a conductor spanning 734 m also shows its effectiveness. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 9979 KiB

Open AccessArticle

Design, Implementation and Validation of the Three-Wheel Holonomic Motion System of the Assistant Personal Robot (APR)

by Javier Moreno, Eduard Clotet, Ruben Lupiañez, Marcel Tresanchez, Dani Martínez, Tomàs Pallejà, Jordi Casanovas and Jordi Palacín

Sensors 2016, 16(10), 1658; https://doi.org/10.3390/s16101658 - 10 Oct 2016

Cited by 41 | Viewed by 11084

Abstract

This paper presents the design, implementation and validation of the three-wheel holonomic motion system of a mobile robot designed to operate in homes. The holonomic motion system is described in terms of mechanical design and electronic control. The paper analyzes the kinematics of [...] Read more.

This paper presents the design, implementation and validation of the three-wheel holonomic motion system of a mobile robot designed to operate in homes. The holonomic motion system is described in terms of mechanical design and electronic control. The paper analyzes the kinematics of the motion system and validates the estimation of the trajectory comparing the displacement estimated with the internal odometry of the motors and the displacement estimated with a SLAM procedure based on LIDAR information. Results obtained in different experiments have shown a difference on less than 30 mm between the position estimated with the SLAM and odometry, and a difference in the angular orientation of the mobile robot lower than 5° in absolute displacements up to 1000 mm. Full article

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

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12 pages, 4036 KiB

Open AccessArticle

An Infrared Absorbance Sensor for the Detection of Melanoma in Skin Biopsies

by Valeria Fioravanti, Lukas Brandhoff, Sander Van den Driesche, Heimo Breiteneder, Melitta Kitzwögerer, Christine Hafner and Michael J. Vellekoop

Sensors 2016, 16(10), 1659; https://doi.org/10.3390/s16101659 - 10 Oct 2016

Cited by 15 | Viewed by 7038

Abstract

An infrared (IR) absorbance sensor has been designed, realized and tested with the aim of detecting malignant melanomas in human skin biopsies. The sensor has been designed to obtain fast measurements (80 s) of a biopsy using a small light spot (0.5 mm [...] Read more.

An infrared (IR) absorbance sensor has been designed, realized and tested with the aim of detecting malignant melanomas in human skin biopsies. The sensor has been designed to obtain fast measurements (80 s) of a biopsy using a small light spot (0.5 mm in diameter, typically five to 10 times smaller than the biopsy size) to investigate different biopsy areas. The sensor has been equipped with a monochromator to record the whole IR spectrum in the 3330–3570 nm wavelength range (where methylene and methyl stretching vibrations occur) for a qualitative spectral investigation. From the collected spectra, the CH₂ stretch ratio values (ratio of the absorption intensities of the symmetric to asymmetric CH₂ stretching peaks) are determined and studied as a cancer indicator. Melanoma areas exhibit different spectral shapes and significantly higher CH₂ stretch ratios when compared to healthy skin. The results of the infrared investigation are compared with standard histology. This study shows that the IR sensor is a promising supportive tool to improve the diagnosis of melanoma during histopathological analysis, decreasing the risk of misdiagnosis. Full article

(This article belongs to the Special Issue Label-Free Optical Biosensors)

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9 pages, 17692 KiB

Open AccessArticle

Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications

by Yonggang Jiang, Jian Li, Zhiwen Zhou, Xinggang Jiang and Deyuan Zhang

Sensors 2016, 16(10), 1660; https://doi.org/10.3390/s16101660 - 17 Oct 2016

Cited by 49 | Viewed by 8094

Abstract

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated [...] Read more.

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1–0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 1773 KiB

Open AccessArticle

A Multifunctional Sensor in Ternary Solution Using Canonical Correlations for Variable Links Assessment

by Dan Liu, Qisong Wang, Xin Liu, Ruixin Niu, Yan Zhang and Jinwei Sun

Sensors 2016, 16(10), 1661; https://doi.org/10.3390/s16101661 - 21 Oct 2016

Cited by 4 | Viewed by 5293

Abstract

Accurately measuring the oil content and salt content of crude oil is very important for both estimating oil reserves and predicting the lifetime of an oil well. There are some problems with the current methods such as high cost, low precision, and difficulties [...] Read more.

Accurately measuring the oil content and salt content of crude oil is very important for both estimating oil reserves and predicting the lifetime of an oil well. There are some problems with the current methods such as high cost, low precision, and difficulties in operation. To solve these problems, we present a multifunctional sensor, which applies, respectively, conductivity method and ultrasound method to measure the contents of oil, water, and salt. Based on cross sensitivity theory, these two transducers are ideally integrated for simplifying the structure. A concentration test of ternary solutions is carried out to testify its effectiveness, and then Canonical Correlation Analysis is applied to evaluate the data. From the perspective of statistics, the sensor inputs, for instance, oil concentration, salt concentration, and temperature, are closely related to its outputs including output voltage and time of flight of ultrasound wave, which further identify the correctness of the sensing theory and the feasibility of the integrated design. Combined with reconstruction algorithms, the sensor can realize the content measurement of the solution precisely. The potential development of the proposed sensor and method in the aspect of online test for crude oil is of important reference and practical value. Full article

(This article belongs to the Special Issue Smart Sensor Interface Circuits and Systems)

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19 pages, 1400 KiB

Open AccessArticle

Achieving Passive Localization with Traffic Light Schedules in Urban Road Sensor Networks

by Qiang Niu, Xu Yang, Shouwan Gao, Pengpeng Chen and Shibing Chan

Sensors 2016, 16(10), 1662; https://doi.org/10.3390/s16101662 - 10 Oct 2016

Cited by 3 | Viewed by 4880

Abstract

Localization is crucial for the monitoring applications of cities, such as road monitoring, environment surveillance, vehicle tracking, etc. In urban road sensor networks, sensors are often sparely deployed due to the hardware cost. Under this sparse deployment, sensors cannot communicate with each other [...] Read more.

Localization is crucial for the monitoring applications of cities, such as road monitoring, environment surveillance, vehicle tracking, etc. In urban road sensor networks, sensors are often sparely deployed due to the hardware cost. Under this sparse deployment, sensors cannot communicate with each other via ranging hardware or one-hop connectivity, rendering the existing localization solutions ineffective. To address this issue, this paper proposes a novel Traffic Lights Schedule-based localization algorithm (TLS), which is built on the fact that vehicles move through the intersection with a known traffic light schedule. We can first obtain the law by binary vehicle detection time stamps and describe the law as a matrix, called a detection matrix. At the same time, we can also use the known traffic light information to construct the matrices, which can be formed as a collection called a known matrix collection. The detection matrix is then matched in the known matrix collection for identifying where sensors are located on urban roads. We evaluate our algorithm by extensive simulation. The results show that the localization accuracy of intersection sensors can reach more than 90%. In addition, we compare it with a state-of-the-art algorithm and prove that it has a wider operational region. Full article

(This article belongs to the Special Issue Scalable Localization in Wireless Sensor Networks)

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14 pages, 3253 KiB

Open AccessArticle

Mid-Infrared Photoacoustic Detection of Glucose in Human Skin: Towards Non-Invasive Diagnostics

by Jonas Kottmann, Julien M. Rey and Markus W. Sigrist

Sensors 2016, 16(10), 1663; https://doi.org/10.3390/s16101663 - 10 Oct 2016

Cited by 93 | Viewed by 14011

Abstract

Diabetes mellitus is a widespread metabolic disease without cure. Great efforts are being made to develop a non-invasive monitoring of the blood glucose level. Various attempts have been made, including a number of non-optical approaches as well as optical techniques involving visible, near- [...] Read more.

Diabetes mellitus is a widespread metabolic disease without cure. Great efforts are being made to develop a non-invasive monitoring of the blood glucose level. Various attempts have been made, including a number of non-optical approaches as well as optical techniques involving visible, near- and mid-infrared light. However, no true breakthrough has been achieved so far, i.e., there is no fully non-invasive monitoring device available. Here we present a new study based on mid-infrared spectroscopy and photoacoustic detection. We employ two setups, one with a fiber-coupled photoacoustic (PA) cell and a tunable quantum cascade laser (QCL), and a second setup with two QCLs at different wavelengths combined with PA detection. In both cases, the PA cells are in direct skin contact. The performance is tested with an oral glucose tolerance test. While the first setup often gives reasonable qualitative agreement with ordinary invasive blood glucose measurements, the dual-wavelength approach yields a considerably improved stability and an uncertainty of only ±30 mg/dL of the blood glucose concentration level at a confidence level of 90%. This result is achieved without advanced data treatment such as principal component analysis involving extended wavelength ranges. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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20 pages, 1042 KiB

Open AccessArticle

PILA: Sub-Meter Localization Using CSI from Commodity Wi-Fi Devices

by Zengshan Tian, Ze Li, Mu Zhou, Yue Jin and Zipeng Wu

Sensors 2016, 16(10), 1664; https://doi.org/10.3390/s16101664 - 10 Oct 2016

Cited by 25 | Viewed by 6714

Abstract

The aim of this paper is to present a new indoor localization approach by employing the Angle-of-arrival (AOA) and Received Signal Strength (RSS) measurements in Wi-Fi network. To achieve this goal, we first collect the Channel State Information (CSI) by using the commodity [...] Read more.

The aim of this paper is to present a new indoor localization approach by employing the Angle-of-arrival (AOA) and Received Signal Strength (RSS) measurements in Wi-Fi network. To achieve this goal, we first collect the Channel State Information (CSI) by using the commodity Wi-Fi devices with our designed three antennas to estimate the AOA of Wi-Fi signal. Second, we propose a direct path identification algorithm to obtain the direct signal path for the sake of reducing the interference of multipath effect on the AOA estimation. Third, we construct a new objective function to solve the localization problem by integrating the AOA and RSS information. Although the localization problem is non-convex, we use the Second-order Cone Programming (SOCP) relaxation approach to transform it into a convex problem. Finally, the effectiveness of our approach is verified based on the prototype implementation by using the commodity Wi-Fi devices. The experimental results show that our approach can achieve the median error 0.7 m in the actual indoor environment. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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10 pages, 1897 KiB

Open AccessArticle

One Binder to Bind Them All

by Oliver Hayden

Sensors 2016, 16(10), 1665; https://doi.org/10.3390/s16101665 - 10 Oct 2016

Cited by 8 | Viewed by 5480

Abstract

High quality binders, such as antibodies, are of critical importance for chemical sensing applications. With synthetic alternatives, such as molecularly imprinted polymers (MIPs), less sensor development time and higher stability of the binder can be achieved. In this feature paper, I will discuss [...] Read more.

High quality binders, such as antibodies, are of critical importance for chemical sensing applications. With synthetic alternatives, such as molecularly imprinted polymers (MIPs), less sensor development time and higher stability of the binder can be achieved. In this feature paper, I will discuss the impact of synthetic binders from an industrial perspective and I will challenge the molecular imprinting community on the next step to leapfrog the current status quo of MIPs for (bio)sensing. Equally important, but often neglected as an effective chemical sensor, is a good match of transducer and MIP coating for a respective application. To demonstrate an application-driven development, a biosensing use case with surface-imprinted layers on piezoacoustic sensors is reported. Depending on the electrode pattern for the transducer, the strong mechanical coupling of the analyte with the MIP layer coated device allows the adoption of the sensitivity from cell mass to cell viability with complete reversibility. Full article

(This article belongs to the Special Issue Molecular Imprinting and Functional Polymers for all Transducers and Applications)

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16 pages, 1920 KiB

Open AccessArticle

Adaptive Collaborative Gaussian Mixture Probability Hypothesis Density Filter for Multi-Target Tracking

by Feng Yang, Yongqi Wang, Hao Chen, Pengyan Zhang and Yan Liang

Sensors 2016, 16(10), 1666; https://doi.org/10.3390/s16101666 - 11 Oct 2016

Cited by 4 | Viewed by 5167

Abstract

In this paper, an adaptive collaborative Gaussian Mixture Probability Hypothesis Density (ACo-GMPHD) filter is proposed for multi-target tracking with automatic track extraction. Based on the evolutionary difference between the persistent targets and the birth targets, the measurements are adaptively partitioned into two parts, [...] Read more.

In this paper, an adaptive collaborative Gaussian Mixture Probability Hypothesis Density (ACo-GMPHD) filter is proposed for multi-target tracking with automatic track extraction. Based on the evolutionary difference between the persistent targets and the birth targets, the measurements are adaptively partitioned into two parts, persistent and birth measurement sets, for updating the persistent and birth target Probability Hypothesis Density, respectively. Furthermore, the collaboration mechanism of multiple probability hypothesis density (PHDs) is established, where tracks can be automatically extracted. Simulation results reveal that the proposed filter yields considerable computational savings in processing requirements and significant improvement in tracking accuracy. Full article

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

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12 pages, 5906 KiB

Open AccessArticle

Stretchable Complementary Split Ring Resonator (CSRR)-Based Radio Frequency (RF) Sensor for Strain Direction and Level Detection

by Seunghyun Eom and Sungjoon Lim

Sensors 2016, 16(10), 1667; https://doi.org/10.3390/s16101667 - 11 Oct 2016

Cited by 50 | Viewed by 10390

Abstract

In this paper, we proposed a stretchable radio frequency (RF) sensor to detect strain direction and level. The stretchable sensor is composed of two complementary split ring resonators (CSRR) with microfluidic channels. In order to achieve stretchability, liquid metal (eutectic gallium-indium, EGaIn) and [...] Read more.

In this paper, we proposed a stretchable radio frequency (RF) sensor to detect strain direction and level. The stretchable sensor is composed of two complementary split ring resonators (CSRR) with microfluidic channels. In order to achieve stretchability, liquid metal (eutectic gallium-indium, EGaIn) and Ecoflex substrate are used. Microfluidic channels are built by Ecoflex elastomer and microfluidic channel frames. A three-dimensional (3D) printer is used for fabrication of microfluidic channel frames. Two CSRR resonators are designed to resonate 2.03 GHz and 3.68 GHz. When the proposed sensor is stretched from 0 to 8 mm along the +x direction, the resonant frequency is shifted from 3.68 GHz to 3.13 GHz. When the proposed sensor is stretched from 0 to 8 mm along the −x direction, the resonant frequency is shifted from 2.03 GHz to 1.78 GHz. Therefore, we can detect stretched length and direction from independent variation of two resonant frequencies. Full article

(This article belongs to the Special Issue Advanced Technologies and Techniques for Microwave and Wireless Sensors)

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27 pages, 1648 KiB

Open AccessArticle

Effective World Modeling: Multisensor Data Fusion Methodology for Automated Driving

by Jos Elfring, Rein Appeldoorn, Sjoerd Van den Dries and Maurice Kwakkernaat

Sensors 2016, 16(10), 1668; https://doi.org/10.3390/s16101668 - 11 Oct 2016

Cited by 37 | Viewed by 8379

Abstract

The number of perception sensors on automated vehicles increases due to the increasing number of advanced driver assistance system functions and their increasing complexity. Furthermore, fail-safe systems require redundancy, thereby increasing the number of sensors even further. A one-size-fits-all multisensor data fusion architecture [...] Read more.

The number of perception sensors on automated vehicles increases due to the increasing number of advanced driver assistance system functions and their increasing complexity. Furthermore, fail-safe systems require redundancy, thereby increasing the number of sensors even further. A one-size-fits-all multisensor data fusion architecture is not realistic due to the enormous diversity in vehicles, sensors and applications. As an alternative, this work presents a methodology that can be used to effectively come up with an implementation to build a consistent model of a vehicle’s surroundings. The methodology is accompanied by a software architecture. This combination minimizes the effort required to update the multisensor data fusion system whenever sensors or applications are added or replaced. A series of real-world experiments involving different sensors and algorithms demonstrates the methodology and the software architecture. Full article

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

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13 pages, 2864 KiB

Open AccessArticle

Low-Frequency Error Extraction and Compensation for Attitude Measurements from STECE Star Tracker

by Yuwang Lai, Defeng Gu, Junhong Liu, Wenping Li and Dongyun Yi

Sensors 2016, 16(10), 1669; https://doi.org/10.3390/s16101669 - 12 Oct 2016

Cited by 7 | Viewed by 6355

Abstract

The low frequency errors (LFE) of star trackers are the most penalizing errors for high-accuracy satellite attitude determination. Two test star trackers- have been mounted on the Space Technology Experiment and Climate Exploration (STECE) satellite, a small satellite mission developed by China. To [...] Read more.

The low frequency errors (LFE) of star trackers are the most penalizing errors for high-accuracy satellite attitude determination. Two test star trackers- have been mounted on the Space Technology Experiment and Climate Exploration (STECE) satellite, a small satellite mission developed by China. To extract and compensate the LFE of the attitude measurements for the two test star trackers, a new approach, called Fourier analysis, combined with the Vondrak filter method (FAVF) is proposed in this paper. Firstly, the LFE of the two test star trackers’ attitude measurements are analyzed and extracted by the FAVF method. The remarkable orbital reproducibility features are found in both of the two test star trackers’ attitude measurements. Then, by using the reproducibility feature of the LFE, the two star trackers’ LFE patterns are estimated effectively. Finally, based on the actual LFE pattern results, this paper presents a new LFE compensation strategy. The validity and effectiveness of the proposed LFE compensation algorithm is demonstrated by the significant improvement in the consistency between the two test star trackers. The root mean square (RMS) of the relative Euler angle residuals are reduced from [27.95′′, 25.14′′, 82.43′′], 3σ to [16.12′′, 15.89′′, 53.27′′], 3σ. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2404 KiB

Open AccessArticle

Low-Coherence Reflectometry for Refractive Index Measurements of Cells in Micro-Capillaries

by Francesca Carpignano, Giulia Rigamonti, Giuliano Mazzini and Sabina Merlo

Sensors 2016, 16(10), 1670; https://doi.org/10.3390/s16101670 - 11 Oct 2016

Cited by 12 | Viewed by 6043

Abstract

The refractive index of cells provides insights into their composition, organization and function. Moreover, a good knowledge of the cell refractive index would allow an improvement of optical cytometric and diagnostic systems. Although interferometric techniques undoubtedly represent a good solution for quantifying optical [...] Read more.

The refractive index of cells provides insights into their composition, organization and function. Moreover, a good knowledge of the cell refractive index would allow an improvement of optical cytometric and diagnostic systems. Although interferometric techniques undoubtedly represent a good solution for quantifying optical path variation, obtaining the refractive index of a population of cells non-invasively remains challenging because of the variability in the geometrical thickness of the sample. In this paper, we demonstrate the use of infrared low-coherence reflectometry for non-invasively quantifying the average refractive index of cell populations gently confined in rectangular glass micro-capillaries. A suspension of human red blood cells in plasma is tested as a reference. As a use example, we apply this technique to estimate the average refractive index of cell populations belonging to epithelial and hematological families. Full article

(This article belongs to the Special Issue Label-Free Optical Biosensors)

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17 pages, 7759 KiB

Open AccessArticle

Design and Evaluation of a Scalable and Reconfigurable Multi-Platform System for Acoustic Imaging

by Alberto Izquierdo, Juan José Villacorta, Lara Del Val Puente and Luis Suárez

Sensors 2016, 16(10), 1671; https://doi.org/10.3390/s16101671 - 11 Oct 2016

Cited by 28 | Viewed by 6918

Abstract

This paper proposes a scalable and multi-platform framework for signal acquisition and processing, which allows for the generation of acoustic images using planar arrays of MEMS (Micro-Electro-Mechanical Systems) microphones with low development and deployment costs. Acoustic characterization of MEMS sensors was performed, and [...] Read more.

This paper proposes a scalable and multi-platform framework for signal acquisition and processing, which allows for the generation of acoustic images using planar arrays of MEMS (Micro-Electro-Mechanical Systems) microphones with low development and deployment costs. Acoustic characterization of MEMS sensors was performed, and the beam pattern of a module, based on an 8 × 8 planar array and of several clusters of modules, was obtained. A flexible framework, formed by an FPGA, an embedded processor, a computer desktop, and a graphic processing unit, was defined. The processing times of the algorithms used to obtain the acoustic images, including signal processing and wideband beamforming via FFT, were evaluated in each subsystem of the framework. Based on this analysis, three frameworks are proposed, defined by the specific subsystems used and the algorithms shared. Finally, a set of acoustic images obtained from sound reflected from a person are presented as a case study in the field of biometric identification. These results reveal the feasibility of the proposed system. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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14 pages, 5384 KiB

Open AccessArticle

Vision/INS Integrated Navigation System for Poor Vision Navigation Environments

by Youngsun Kim and Dong-Hwan Hwang

Sensors 2016, 16(10), 1672; https://doi.org/10.3390/s16101672 - 12 Oct 2016

Cited by 20 | Viewed by 5864

Abstract

In order to improve the performance of an inertial navigation system, many aiding sensors can be used. Among these aiding sensors, a vision sensor is of particular note due to its benefits in terms of weight, cost, and power consumption. This paper proposes [...] Read more.

In order to improve the performance of an inertial navigation system, many aiding sensors can be used. Among these aiding sensors, a vision sensor is of particular note due to its benefits in terms of weight, cost, and power consumption. This paper proposes an inertial and vision integrated navigation method for poor vision navigation environments. The proposed method uses focal plane measurements of landmarks in order to provide position, velocity and attitude outputs even when the number of landmarks on the focal plane is not enough for navigation. In order to verify the proposed method, computer simulations and van tests are carried out. The results show that the proposed method gives accurate and reliable position, velocity and attitude outputs when the number of landmarks is insufficient. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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18 pages, 1171 KiB

Open AccessArticle

I-AUV Docking and Panel Intervention at Sea

by Narcís Palomeras, Antonio Peñalver, Miquel Massot-Campos, Pep Lluís Negre, José Javier Fernández, Pere Ridao, Pedro J. Sanz and Gabriel Oliver-Codina

Sensors 2016, 16(10), 1673; https://doi.org/10.3390/s16101673 - 12 Oct 2016

Cited by 36 | Viewed by 8653

Abstract

The use of commercially available autonomous underwater vehicles (AUVs) has increased during the last fifteen years. While they are mainly used for routine survey missions, there is a set of applications that nowadays can be only addressed by manned submersibles or work-class remotely [...] Read more.

The use of commercially available autonomous underwater vehicles (AUVs) has increased during the last fifteen years. While they are mainly used for routine survey missions, there is a set of applications that nowadays can be only addressed by manned submersibles or work-class remotely operated vehicles (ROVs) equipped with teleoperated arms: the intervention applications. To allow these heavy vehicles controlled by human operators to perform intervention tasks, underwater structures like observatory facilities, subsea panels or oil-well Christmas trees have been adapted, making them more robust and easier to operate. The TRITON Spanish founded project proposes the use of a light-weight intervention AUV (I-AUV) to carry out intervention applications simplifying the adaptation of these underwater structures and drastically reducing the operational cost. To prove this concept, the Girona 500 I-AUV is used to autonomously dock into an adapted subsea panel and once docked perform an intervention composed of turning a valve and plugging in/unplugging a connector. The techniques used for the autonomous docking and manipulation as well as the design of an adapted subsea panel with a funnel-based docking system are presented in this article together with the results achieved in a water tank and at sea. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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11 pages, 7300 KiB

Open AccessArticle

Visual and Plasmon Resonance Absorption Sensor for Adenosine Triphosphate Based on the High Affinity between Phosphate and Zr(IV)

by Wenjing Qi, Zhongyuan Liu, Wei Zhang, Mohamed Ibrahim Halawa and Guobao Xu

Sensors 2016, 16(10), 1674; https://doi.org/10.3390/s16101674 - 12 Oct 2016

Cited by 5 | Viewed by 6485

Abstract

Zr(IV) can form phosphate and Zr(IV) (–PO₃²⁻–Zr⁴⁺–) complex owing to the high affinity between Zr(IV) with phosphate. Zr(IV) can induce the aggregation of gold nanoparticles (AuNPs), while adenosine triphosphate(ATP) can prevent Zr(IV)-induced aggregation of AuNPs. Herein, a visual [...] Read more.

Zr(IV) can form phosphate and Zr(IV) (–PO₃²⁻–Zr⁴⁺–) complex owing to the high affinity between Zr(IV) with phosphate. Zr(IV) can induce the aggregation of gold nanoparticles (AuNPs), while adenosine triphosphate(ATP) can prevent Zr(IV)-induced aggregation of AuNPs. Herein, a visual and plasmon resonance absorption (PRA)sensor for ATP have been developed using AuNPs based on the high affinity between Zr(IV)with ATP. AuNPs get aggregated in the presence of certain concentrations of Zr(IV). After the addition of ATP, ATP reacts with Zr(IV) and prevents AuNPs from aggregation, enabling the detection of ATP. Because of the fast interaction of ATP with Zr(IV), ATP can be detected with a detection limit of 0.5 μM within 2 min by the naked eye. Moreover, ATP can be detected by the PRA technique with higher sensitivity. The A_520nm/A_650nm values in PRA spectra increase linearly with the concentrations of ATP from 0.1 μM to 15 μM (r = 0.9945) with a detection limit of 28 nM. The proposed visual and PRA sensor exhibit good selectivity against adenosine, adenosine monophosphate, guanosine triphosphate, cytidine triphosphate and uridine triphosphate. The recoveries for the analysis of ATP in synthetic samples range from 95.3% to 102.0%. Therefore, the proposed novel sensor for ATP is promising for real-time or on-site detection of ATP. Full article

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

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22 pages, 6324 KiB

Open AccessArticle

A Novel Dynamic Spectrum Access Framework Based on Reinforcement Learning for Cognitive Radio Sensor Networks

by Yun Lin, Chao Wang, Jiaxing Wang and Zheng Dou

Sensors 2016, 16(10), 1675; https://doi.org/10.3390/s16101675 - 12 Oct 2016

Cited by 136 | Viewed by 6585

Abstract

Cognitive radio sensor networks are one of the kinds of application where cognitive techniques can be adopted and have many potential applications, challenges and future research trends. According to the research surveys, dynamic spectrum access is an important and necessary technology for future [...] Read more.

Cognitive radio sensor networks are one of the kinds of application where cognitive techniques can be adopted and have many potential applications, challenges and future research trends. According to the research surveys, dynamic spectrum access is an important and necessary technology for future cognitive sensor networks. Traditional methods of dynamic spectrum access are based on spectrum holes and they have some drawbacks, such as low accessibility and high interruptibility, which negatively affect the transmission performance of the sensor networks. To address this problem, in this paper a new initialization mechanism is proposed to establish a communication link and set up a sensor network without adopting spectrum holes to convey control information. Specifically, firstly a transmission channel model for analyzing the maximum accessible capacity for three different polices in a fading environment is discussed. Secondly, a hybrid spectrum access algorithm based on a reinforcement learning model is proposed for the power allocation problem of both the transmission channel and the control channel. Finally, extensive simulations have been conducted and simulation results show that this new algorithm provides a significant improvement in terms of the tradeoff between the control channel reliability and the efficiency of the transmission channel. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 4259 KiB

Open AccessArticle

SAR Ground Moving Target Indication Based on Relative Residue of DPCA Processing

by Jia Xu, Zuzhen Huang, Liang Yan, Xu Zhou, Furu Zhang and Teng Long

Sensors 2016, 16(10), 1676; https://doi.org/10.3390/s16101676 - 12 Oct 2016

Cited by 11 | Viewed by 5864

Abstract

For modern synthetic aperture radar (SAR), it has much more urgent demands on ground moving target indication (GMTI), which includes not only the point moving targets like cars, truck or tanks but also the distributed moving targets like river or ocean surfaces. Among [...] Read more.

For modern synthetic aperture radar (SAR), it has much more urgent demands on ground moving target indication (GMTI), which includes not only the point moving targets like cars, truck or tanks but also the distributed moving targets like river or ocean surfaces. Among the existing GMTI methods, displaced phase center antenna (DPCA) can effectively cancel the strong ground clutter and has been widely used. However, its detection performance is closely related to the target’s signal-to-clutter ratio (SCR) as well as radial velocity, and it cannot effectively detect the weak large-sized river surfaces in strong ground clutter due to their low SCR caused by specular scattering. This paper proposes a novel method called relative residue of DPCA (RR-DPCA), which jointly utilizes the DPCA cancellation outputs and the multi-look images to improve the detection performance of weak river surfaces. Furthermore, based on the statistics analysis of the RR-DPCA outputs on the homogenous background, the cell average (CA) method can be well applied for subsequent constant false alarm rate (CFAR) detection. The proposed RR-DPCA method can well detect the point moving targets and distributed moving targets simultaneously. Finally, the results of both simulated and real data are provided to demonstrate the effectiveness of the proposed SAR/GMTI method. Full article

(This article belongs to the Special Issue Synthetic Aperture Radars: Models, Algorithms, Techniques and Tools for Data Exploitation)

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19 pages, 13538 KiB

Open AccessArticle

Reduction of Kinematic Short Baseline Multipath Effects Based on Multipath Hemispherical Map

by Miaomiao Cai, Wen Chen, Danan Dong, Le Song, Minghua Wang, Zhiren Wang, Feng Zhou, Zhengqi Zheng and Chao Yu

Sensors 2016, 16(10), 1677; https://doi.org/10.3390/s16101677 - 12 Oct 2016

Cited by 26 | Viewed by 5114

Abstract

Multipath hemispherical map (MHM) is a kind of multipath mitigation approach that takes advantage of the spatial repeatability of the multipath effect under an unchanged environment. This approach is not only suitable for static environments, but also for some kinematic platforms, such as [...] Read more.

Multipath hemispherical map (MHM) is a kind of multipath mitigation approach that takes advantage of the spatial repeatability of the multipath effect under an unchanged environment. This approach is not only suitable for static environments, but also for some kinematic platforms, such as a moving ship and airplane, where the dominant multipath effects come from the platform itself and the multipath effects from the surrounding environment are considered minor or negligible. Previous studies have verified the feasibility of the MHM approach in static environments. In this study, we expanded the MHM approach to a kinematic shipborne environment. Both static and kinematic tests were carried out to demonstrate the feasibility of the MHM approach. The results indicate that, after MHM multipath mitigation, the root mean square (RMS) of baseline length deviations are reduced by 10.47% and 10.57%, and the RMS of residual values are reduced by 39.89% and 21.91% for the static and kinematic tests, respectively. Power spectrum analysis has shown that the MHM approach is more effective in mitigating multipath in low-frequency bands; the high-frequency multipath effects still exist, and are indistinguishable from observation noise. Taking the observation noise into account, the residual reductions increase to 41.68% and 24.51% in static and kinematic tests, respectively. To further improve the performance of MHM for kinematic platforms, we also analyzed the influence of spatial coverage and resolution on residual reduction. Full article

(This article belongs to the Section Remote Sensors)

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8 pages, 19320 KiB

Open AccessArticle

Application of Ultrasonic Sensors in Road Surface Condition Distinction Methods

by Shota Nakashima, Shingo Aramaki, Yuhki Kitazono, Shenglin Mu, Kanya Tanaka and Seiichi Serikawa

Sensors 2016, 16(10), 1678; https://doi.org/10.3390/s16101678 - 12 Oct 2016

Cited by 15 | Viewed by 7326

Abstract

The number of accidents involving elderly individuals has been increasing with the increase of the aging population, posing increasingly serious challenges. Most accidents are caused by reduced judgment and physical abilities, which lead to severe consequences. Therefore, studies on support systems for elderly [...] Read more.

The number of accidents involving elderly individuals has been increasing with the increase of the aging population, posing increasingly serious challenges. Most accidents are caused by reduced judgment and physical abilities, which lead to severe consequences. Therefore, studies on support systems for elderly and visually impaired people to improve the safety and quality of daily life are attracting considerable attention. In this study, a road surface condition distinction method using reflection intensities obtained by an ultrasonic sensor was proposed. The proposed method was applied to movement support systems for elderly and visually impaired individuals to detect dangerous road surfaces and give an alarm. The method did not perform well in previous studies of puddle detection, because the alert provided by the method did not enable users to avoid puddles. This study extended the method proposed by previous studies with respect to puddle detection ability. The findings indicate the effectiveness of the proposed method by considering four road surface conditions. The proposed method could detect puddle conditions. The effectiveness of the proposed method was verified in all four conditions, since users could differentiate between road surface conditions and classify the conditions as either safe or dangerous. Full article

(This article belongs to the Special Issue Selected Papers from 2016 International Symposium on Computer, Consumer and Control (IS3C 2016))

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12 pages, 4098 KiB

Open AccessArticle

A Fast and in-Situ Measuring Method Using Laser Triangulation Sensors for the Parameters of the Connecting Rod

by Xing-Qiang Li, Zhong Wang and Lu-Hua Fu

Sensors 2016, 16(10), 1679; https://doi.org/10.3390/s16101679 - 12 Oct 2016

Cited by 7 | Viewed by 6209

Abstract

The connecting rod is a critical part inside the marine engine. The inspection of its important parameters is directly related to the assembly and quality of the marine engine. A coordinate measuring machine (CMM) is a conventional choice to measure the parameters of [...] Read more.

The connecting rod is a critical part inside the marine engine. The inspection of its important parameters is directly related to the assembly and quality of the marine engine. A coordinate measuring machine (CMM) is a conventional choice to measure the parameters of a connecting rod. However, CMM requires significant resources in time and cost, which leads researchers into in-situ measurement. This article presents a fast and in-situ measuring method by using a laser-based measuring head. Two measuring strategies are adopted in the inspection process. For positional measurements (such as the hole–center distance), whose accuracy requirement is generally low, the coordinate system of the numerical control (NC) machine is combined with the measuring head to acquire the positional parameters. For dimensional measurements (such as inner diameters), whose accuracy requirement is rather high, the NC machine is used just as transportation. Note that the measuring head has the ability to perform the dimension inspection independently. The accuracy of the measuring head is high enough to meet the dimensional accuracy requirements. Experiments are performed to validate the proposed method. The measuring error of the inner diameters is from 5 μm to 7 μm. The measuring error of hole–center distance is within 15 μm. The measurement of all these parameters can be done within 1 min. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 821 KiB

Open AccessArticle

Dynamic Power-Saving Method for Wi-Fi Direct Based IoT Networks Considering Variable-Bit-Rate Video Traffic

by Meihua Jin, Ji-Young Jung and Jung-Ryun Lee

Sensors 2016, 16(10), 1680; https://doi.org/10.3390/s16101680 - 12 Oct 2016

Cited by 9 | Viewed by 5029

Abstract

With the arrival of the era of Internet of Things (IoT), Wi-Fi Direct is becoming an emerging wireless technology that allows one to communicate through a direct connection between the mobile devices anytime, anywhere. In Wi-Fi Direct-based IoT networks, all devices are categorized [...] Read more.

With the arrival of the era of Internet of Things (IoT), Wi-Fi Direct is becoming an emerging wireless technology that allows one to communicate through a direct connection between the mobile devices anytime, anywhere. In Wi-Fi Direct-based IoT networks, all devices are categorized by group of owner (GO) and client. Since portability is emphasized in Wi-Fi Direct devices, it is essential to control the energy consumption of a device very efficiently. In order to avoid unnecessary power consumed by GO, Wi-Fi Direct standard defines two power-saving methods: Opportunistic and Notice of Absence (NoA) power-saving methods. In this paper, we suggest an algorithm to enhance the energy efficiency of Wi-Fi Direct power-saving, considering the characteristics of multimedia video traffic. Proposed algorithm utilizes the statistical distribution for the size of video frames and adjusts the lengths of awake intervals in a beacon interval dynamically. In addition, considering the inter-dependency among video frames, the proposed algorithm ensures that a video frame having high priority is transmitted with higher probability than other frames having low priority. Simulation results show that the proposed method outperforms the traditional NoA method in terms of average delay and energy efficiency. Full article

(This article belongs to the Special Issue Enabling the Move from Wireless Sensor Networks to Internet of Things and Cyber-Physical Systems)

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13 pages, 3857 KiB

Open AccessArticle

Design and Implementation of an Electronic Front-End Based on Square Wave Excitation for Ultrasonic Torsional Guided Wave Viscosity Sensor

by Amir Rabani

Sensors 2016, 16(10), 1681; https://doi.org/10.3390/s16101681 - 12 Oct 2016

Cited by 6 | Viewed by 7208

Abstract

The market for process instruments generally requires low cost devices that are robust, small in size, portable, and usable in-plant. Ultrasonic torsional guided wave sensors have received much attention by researchers for measurement of viscosity and/or density of fluids in recent years. The [...] Read more.

The market for process instruments generally requires low cost devices that are robust, small in size, portable, and usable in-plant. Ultrasonic torsional guided wave sensors have received much attention by researchers for measurement of viscosity and/or density of fluids in recent years. The supporting electronic systems for these sensors providing many different settings of sine-wave signals are bulky and expensive. In contrast, a system based on bursts of square waves instead of sine waves would have a considerable advantage in that respect and could be built using simple integrated circuits at a cost that is orders of magnitude lower than for a windowed sine wave device. This paper explores the possibility of using square wave bursts as the driving signal source for the ultrasonic torsional guided wave viscosity sensor. A simple design of a compact and fully automatic analogue square wave front-end for the sensor is also proposed. The successful operation of the system is demonstrated by using the sensor for measuring the viscosity in a representative fluid. This work provides the basis for design and manufacture of low cost compact standalone ultrasonic guided wave sensors and enlightens the possibility of using coded excitation techniques utilising square wave sequences in such applications. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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20 pages, 1180 KiB

Open AccessArticle

LPI Radar Waveform Recognition Based on Time-Frequency Distribution

by Ming Zhang, Lutao Liu and Ming Diao

Sensors 2016, 16(10), 1682; https://doi.org/10.3390/s16101682 - 12 Oct 2016

Cited by 134 | Viewed by 10760

Abstract

In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating [...] Read more.

In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI) radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM), BPSK (Barker code modulation), Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4). The classifier is Elman neural network (ENN), and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA), image binarization algorithm and Pseudo–Zernike moments, etc., the features are extracted from the Choi–Williams time-frequency distribution (CWD) image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR) is 94.7% at signal-to-noise ratio (SNR) of −2 dB. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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14 pages, 2996 KiB

Open AccessArticle

Decomposition of Composite Electric Field in a Three-Phase D-Dot Voltage Transducer Measuring System

by Xueqi Hu, Jingang Wang, Gang Wei and Xudong Deng

Sensors 2016, 16(10), 1683; https://doi.org/10.3390/s16101683 - 12 Oct 2016

Cited by 8 | Viewed by 4446

Abstract

In line with the wider application of non-contact voltage transducers in the engineering field, transducers are required to have better performance for different measuring environments. In the present study, the D-dot voltage transducer is further improved based on previous research in order to [...] Read more.

In line with the wider application of non-contact voltage transducers in the engineering field, transducers are required to have better performance for different measuring environments. In the present study, the D-dot voltage transducer is further improved based on previous research in order to meet the requirements for long-distance measurement of electric transmission lines. When measuring three-phase electric transmission lines, problems such as synchronous data collection and composite electric field need to be resolved. A decomposition method is proposed with respect to the superimposed electric field generated between neighboring phases. The charge simulation method is utilized to deduce the decomposition equation of the composite electric field and the validity of the proposed method is verified by simulation calculation software. With the deduced equation as the algorithm foundation, this paper improves hardware circuits, establishes a measuring system and constructs an experimental platform for examination. Under experimental conditions, a 10 kV electric transmission line was tested for steady-state errors, and the measuring results of the transducer and the high-voltage detection head were compared. Ansoft Maxwell Stimulation Software was adopted to obtain the electric field intensity in different positions under transmission lines; its values and the measuring values of the transducer were also compared. Experimental results show that the three-phase transducer is characterized by a relatively good synchronization for data measurement, measuring results with high precision, and an error ratio within a prescribed limit. Therefore, the proposed three-phase transducer can be broadly applied and popularized in the engineering field. Full article

(This article belongs to the Section Physical Sensors)

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8 pages, 980 KiB

Open AccessArticle

ESIPT-Based Photoactivatable Fluorescent Probe for Ratiometric Spatiotemporal Bioimaging

by Xiaohong Zhou, Yuren Jiang, Xiongjie Zhao and Dong Guo

Sensors 2016, 16(10), 1684; https://doi.org/10.3390/s16101684 - 12 Oct 2016

Cited by 9 | Viewed by 7326

Abstract

Photoactivatable fluorophores have become an important technique for the high spatiotemporal resolution of biological imaging. Here, we developed a novel photoactivatable probe (PHBT), which is based on 2-(2-hydroxyphenyl)benzothiazole (HBT), a small organic fluorophore known for its classic luminescence mechanism through excited-state intramolecular proton [...] Read more.

Photoactivatable fluorophores have become an important technique for the high spatiotemporal resolution of biological imaging. Here, we developed a novel photoactivatable probe (PHBT), which is based on 2-(2-hydroxyphenyl)benzothiazole (HBT), a small organic fluorophore known for its classic luminescence mechanism through excited-state intramolecular proton transfer (ESIPT) with the keto form and the enol form. After photocleavage, PHBT released a ratiometric fluorophore HBT, which showed dual emission bands with more than 73-fold fluorescence enhancement at 512 nm in buffer and more than 69-fold enhancement at 452 nm in bovine serum. The probe displayed a high ratiometric imaging resolution and is believed to have a wide application in biological imaging. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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12 pages, 2551 KiB

Open AccessArticle

A Cooperative Downloading Method for VANET Using Distributed Fountain Code

by Jianhang Liu, Wenbin Zhang, Qi Wang, Shibao Li, Haihua Chen, Xuerong Cui and Yi Sun

Sensors 2016, 16(10), 1685; https://doi.org/10.3390/s16101685 - 12 Oct 2016

Cited by 4 | Viewed by 4786

Abstract

Cooperative downloading is one of the effective methods to improve the amount of downloaded data in vehicular ad hoc networking (VANET). However, the poor channel quality and short encounter time bring about a high packet loss rate, which decreases transmission efficiency and fails [...] Read more.

Cooperative downloading is one of the effective methods to improve the amount of downloaded data in vehicular ad hoc networking (VANET). However, the poor channel quality and short encounter time bring about a high packet loss rate, which decreases transmission efficiency and fails to satisfy the requirement of high quality of service (QoS) for some applications. Digital fountain code (DFC) can be utilized in the field of wireless communication to increase transmission efficiency. For cooperative forwarding, however, processing delay from frequent coding and decoding as well as single feedback mechanism using DFC cannot adapt to the environment of VANET. In this paper, a cooperative downloading method for VANET using concatenated DFC is proposed to solve the problems above. The source vehicle and cooperative vehicles encodes the raw data using hierarchical fountain code before they send to the client directly or indirectly. Although some packets may be lost, the client can recover the raw data, so long as it receives enough encoded packets. The method avoids data retransmission due to packet loss. Furthermore, the concatenated feedback mechanism in the method reduces the transmission delay effectively. Simulation results indicate the benefits of the proposed scheme in terms of increasing amount of downloaded data and data receiving rate. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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12 pages, 4105 KiB

Open AccessArticle

Application of CCG Sensors to a High-Temperature Structure Subjected to Thermo-Mechanical Load

by Weihua Xie, Songhe Meng, Hua Jin, Chong Du, Libin Wang, Tao Peng, Fabrizio Scarpa and Chenghai Xu

Sensors 2016, 16(10), 1686; https://doi.org/10.3390/s16101686 - 13 Oct 2016

Cited by 1 | Viewed by 5985

Abstract

This paper presents a simple methodology to perform a high temperature coupled thermo-mechanical test using ultra-high temperature ceramic material specimens (UHTCs), which are equipped with chemical composition gratings sensors (CCGs). The methodology also considers the presence of coupled loading within the response provided [...] Read more.

This paper presents a simple methodology to perform a high temperature coupled thermo-mechanical test using ultra-high temperature ceramic material specimens (UHTCs), which are equipped with chemical composition gratings sensors (CCGs). The methodology also considers the presence of coupled loading within the response provided by the CCG sensors. The theoretical strain of the UHTCs specimens calculated with this technique shows a maximum relative error of 2.15% between the analytical and experimental data. To further verify the validity of the results from the tests, a Finite Element (FE) model has been developed to simulate the temperature, stress and strain fields within the UHTC structure equipped with the CCG. The results show that the compressive stress exceeds the material strength at the bonding area, and this originates a failure by fracture of the supporting structure in the hot environment. The results related to the strain fields show that the relative error with the experimental data decrease with an increase of temperature. The relative error is less than 15% when the temperature is higher than 200 °C, and only 6.71% at 695 °C. Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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22 pages, 15491 KiB

Open AccessArticle

A Fast Superpixel Segmentation Algorithm for PolSAR Images Based on Edge Refinement and Revised Wishart Distance

by Yue Zhang, Huanxin Zou, Tiancheng Luo, Xianxiang Qin, Shilin Zhou and Kefeng Ji

Sensors 2016, 16(10), 1687; https://doi.org/10.3390/s16101687 - 13 Oct 2016

Cited by 31 | Viewed by 6240

Abstract

The superpixel segmentation algorithm, as a preprocessing technique, should show good performance in fast segmentation speed, accurate boundary adherence and homogeneous regularity. A fast superpixel segmentation algorithm by iterative edge refinement (IER) works well on optical images. However, it may generate poor superpixels [...] Read more.

The superpixel segmentation algorithm, as a preprocessing technique, should show good performance in fast segmentation speed, accurate boundary adherence and homogeneous regularity. A fast superpixel segmentation algorithm by iterative edge refinement (IER) works well on optical images. However, it may generate poor superpixels for Polarimetric synthetic aperture radar (PolSAR) images due to the influence of strong speckle noise and many small-sized or slim regions. To solve these problems, we utilized a fast revised Wishart distance instead of Euclidean distance in the local relabeling of unstable pixels, and initialized unstable pixels as all the pixels substituted for the initial grid edge pixels in the initialization step. Then, postprocessing with the dissimilarity measure is employed to remove the generated small isolated regions as well as to preserve strong point targets. Finally, the superiority of the proposed algorithm is validated with extensive experiments on four simulated and two real-world PolSAR images from Experimental Synthetic Aperture Radar (ESAR) and Airborne Synthetic Aperture Radar (AirSAR) data sets, which demonstrate that the proposed method shows better performance with respect to several commonly used evaluation measures, even with about nine times higher computational efficiency, as well as fine boundary adherence and strong point targets preservation, compared with three state-of-the-art methods. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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25 pages, 6594 KiB

Open AccessArticle

Performance Enhancement of Land Vehicle Positioning Using Multiple GPS Receivers in an Urban Area

by Jong-Hwa Song and Gyu-In Jee

Sensors 2016, 16(10), 1688; https://doi.org/10.3390/s16101688 - 14 Oct 2016

Cited by 9 | Viewed by 6047

Abstract

The Global Positioning System (GPS) is the most widely used navigation system in land vehicle applications. In urban areas, the GPS suffers from insufficient signal strength, multipath propagation and non-line-of-sight (NLOS) errors, so it thus becomes difficult to obtain accurate and reliable position [...] Read more.

The Global Positioning System (GPS) is the most widely used navigation system in land vehicle applications. In urban areas, the GPS suffers from insufficient signal strength, multipath propagation and non-line-of-sight (NLOS) errors, so it thus becomes difficult to obtain accurate and reliable position information. In this paper, an integration algorithm for multiple receivers is proposed to enhance the positioning performance of GPS for land vehicles in urban areas. The pseudoranges of multiple receivers are integrated based on a tightly coupled approach, and erroneous measurements are detected by testing the closeness of the pseudoranges. In order to fairly compare the pseudoranges, GPS errors and terms arising due to the differences between the positions of the receivers need to be compensated. The double-difference technique is used to eliminate GPS errors in the pseudoranges, and the geometrical distance is corrected by projecting the baseline vector between pairs of receivers. In order to test and analyze the proposed algorithm, an experiment involving live data was performed. The positioning performance of the algorithm was compared with that of the receiver autonomous integrity monitoring (RAIM)-based integration algorithm for multiple receivers. The test results showed that the proposed algorithm yields more accurate position information in urban areas. Full article

(This article belongs to the Special Issue Sensors for Autonomous Road Vehicles)

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25 pages, 4449 KiB

Open AccessArticle

A Bio-Inspired Model-Based Approach for Context-Aware Post-WIMP Tele-Rehabilitation

by Víctor López-Jaquero, Arturo C. Rodríguez, Miguel A. Teruel, Francisco Montero, Elena Navarro and Pascual Gonzalez

Sensors 2016, 16(10), 1689; https://doi.org/10.3390/s16101689 - 13 Oct 2016

Cited by 6 | Viewed by 5296

Abstract

Tele-rehabilitation is one of the main domains where Information and Communication Technologies (ICT) have been proven useful to move healthcare from care centers to patients’ home. Moreover, patients, especially those carrying out a physical therapy, cannot use a traditional Window, Icon, Menu, Pointer [...] Read more.

Tele-rehabilitation is one of the main domains where Information and Communication Technologies (ICT) have been proven useful to move healthcare from care centers to patients’ home. Moreover, patients, especially those carrying out a physical therapy, cannot use a traditional Window, Icon, Menu, Pointer (WIMP) system, but they need to interact in a natural way, that is, there is a need to move from WIMP systems to Post-WIMP ones. Moreover, tele-rehabilitation systems should be developed following the context-aware approach, so that they are able to adapt to the patients’ context to provide them with usable and effective therapies. In this work a model-based approach is presented to assist stakeholders in the development of context-aware Post-WIMP tele-rehabilitation systems. It entails three different models: (i) a task model for designing the rehabilitation tasks; (ii) a context model to facilitate the adaptation of these tasks to the context; and (iii) a bio-inspired presentation model to specify thoroughly how such tasks should be performed by the patients. Our proposal overcomes one of the limitations of the model-based approach for the development of context-aware systems supporting the specification of non-functional requirements. Finally, a case study is used to illustrate how this proposal can be put into practice to design a real world rehabilitation task. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI, IWAAL and AmIHEALTH 2015)

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15 pages, 4237 KiB

Open AccessArticle

Enhancement of Frequency Stability Using Synchronization of a Cantilever Array for MEMS-Based Sensors

by Francesc Torres, Arantxa Uranga, Martí Riverola, Guillermo Sobreviela and Núria Barniol

Sensors 2016, 16(10), 1690; https://doi.org/10.3390/s16101690 - 13 Oct 2016

Cited by 12 | Viewed by 4969

Abstract

Micro and nano electromechanical resonators have been widely used as single or multiple-mass detection sensors. Smaller devices with higher resonance frequencies and lower masses offer higher mass responsivities but suffer from lower frequency stability. Synchronization phenomena in multiple MEMS resonators have become an [...] Read more.

Micro and nano electromechanical resonators have been widely used as single or multiple-mass detection sensors. Smaller devices with higher resonance frequencies and lower masses offer higher mass responsivities but suffer from lower frequency stability. Synchronization phenomena in multiple MEMS resonators have become an important issue because they allow frequency stability improvement, thereby preserving mass responsivity. The authors present an array of five cantilevers (CMOS-MEMS system) that are forced to vibrate synchronously to enhance their frequency stability. The frequency stability has been determined in closed-loop configuration for long periods of time by calculating the Allan deviation. An Allan deviation of 0.013 ppm (@ 1 s averaging time) for a 1 MHz cantilever array MEMS system was obtained at the synchronized mode, which represents a 23-fold improvement in comparison with the non-synchronized operation mode (0.3 ppm). Full article

(This article belongs to the Special Issue Advanced Technologies and Techniques for Microwave and Wireless Sensors)

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10 pages, 1229 KiB

Open AccessArticle

A High-Sensitivity Tunable Two-Beam Fiber-Coupled High-Density Magnetometer with Laser Heating

by Igor Savukov and Malcolm G. Boshier

Sensors 2016, 16(10), 1691; https://doi.org/10.3390/s16101691 - 13 Oct 2016

Cited by 16 | Viewed by 6067

Abstract

Atomic magnetometers (AM) are finding many applications in biomagnetism, national security, industry, and science. Fiber-coupled (FC) designs promise to make them compact and flexible for operation. Most FC designs are based on a single-beam configuration or electrical heating. Here, we demonstrate a two-beam [...] Read more.

Atomic magnetometers (AM) are finding many applications in biomagnetism, national security, industry, and science. Fiber-coupled (FC) designs promise to make them compact and flexible for operation. Most FC designs are based on a single-beam configuration or electrical heating. Here, we demonstrate a two-beam FC AM with laser heating that has 5 fT/Hz^1/2 sensitivity at low frequency (50 Hz), which is higher than that of other fiber-coupled magnetometers and can be improved to the sub-femtotesla level. This magnetometer is widely tunable from DC to very high frequencies (as high as 100 MHz; the only issue might be the application of a suitable uniform and stable bias field) with a sensitivity under 10 fT/Hz^1/2 and can be used for magneto-encephalography (MEG), magneto-cardiography (MCG), underground communication, ultra-low MRI/NMR, NQR detection, and other applications. Full article

(This article belongs to the Special Issue Giant Magnetoresistive Sensors)

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18 pages, 4120 KiB

Open AccessArticle

Mapping Urban Environmental Noise Using Smartphones

by Jinbo Zuo, Hao Xia, Shuo Liu and Yanyou Qiao

Sensors 2016, 16(10), 1692; https://doi.org/10.3390/s16101692 - 13 Oct 2016

Cited by 64 | Viewed by 8742

Abstract

Noise mapping is an effective method of visualizing and accessing noise pollution. In this paper, a noise-mapping method based on smartphones to effectively and easily measure environmental noise is proposed. By using this method, a noise map of an entire area can be [...] Read more.

Noise mapping is an effective method of visualizing and accessing noise pollution. In this paper, a noise-mapping method based on smartphones to effectively and easily measure environmental noise is proposed. By using this method, a noise map of an entire area can be created using limited measurement data. To achieve the measurement with certain precision, a set of methods was designed to calibrate the smartphones. Measuring noise with mobile phones is different from the traditional static observations. The users may be moving at any time. Therefore, a method of attaching an additional microphone with a windscreen is proposed to reduce the wind effect. However, covering an entire area is impossible. Therefore, an interpolation method is needed to achieve full coverage of the area. To reduce the influence of spatial heterogeneity and improve the precision of noise mapping, a region-based noise-mapping method is proposed in this paper, which is based on the distribution of noise in different region types tagged by volunteers, to interpolate and combine them to create a noise map. To validate the effect of the method, a comparison of the interpolation results was made to analyse our method and the ordinary Kriging method. The result shows that our method is more accurate in reflecting the local distribution of noise and has better interpolation precision. We believe that the proposed noise-mapping method is a feasible and low-cost noise-mapping solution. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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27 pages, 2879 KiB

Open AccessArticle

Full On-Device Stay Points Detection in Smartphones for Location-Based Mobile Applications

by Rafael Pérez-Torres, César Torres-Huitzil and Hiram Galeana-Zapién

Sensors 2016, 16(10), 1693; https://doi.org/10.3390/s16101693 - 13 Oct 2016

Cited by 23 | Viewed by 7479

Abstract

The tracking of frequently visited places, also known as stay points, is a critical feature in location-aware mobile applications as a way to adapt the information and services provided to smartphones users according to their moving patterns. Location based applications usually employ the [...] Read more.

The tracking of frequently visited places, also known as stay points, is a critical feature in location-aware mobile applications as a way to adapt the information and services provided to smartphones users according to their moving patterns. Location based applications usually employ the GPS receiver along with Wi-Fi hot-spots and cellular cell tower mechanisms for estimating user location. Typically, fine-grained GPS location data are collected by the smartphone and transferred to dedicated servers for trajectory analysis and stay points detection. Such Mobile Cloud Computing approach has been successfully employed for extending smartphone’s battery lifetime by exchanging computation costs, assuming that on-device stay points detection is prohibitive. In this article, we propose and validate the feasibility of having an alternative event-driven mechanism for stay points detection that is executed fully on-device, and that provides higher energy savings by avoiding communication costs. Our solution is encapsulated in a sensing middleware for Android smartphones, where a stream of GPS location updates is collected in the background, supporting duty cycling schemes, and incrementally analyzed following an event-driven paradigm for stay points detection. To evaluate the performance of the proposed middleware, real world experiments were conducted under different stress levels, validating its power efficiency when compared against a Mobile Cloud Computing oriented solution. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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17 pages, 3362 KiB

Open AccessArticle

One-Time URL: A Proximity Security Mechanism between Internet of Things and Mobile Devices

by Antonio Solano, Raquel Dormido, Natividad Duro and Víctor González

Sensors 2016, 16(10), 1694; https://doi.org/10.3390/s16101694 - 13 Oct 2016

Viewed by 7979

Abstract

The aim of this paper is to determine the physical proximity of connected things when they are accessed from a smartphone. Links between connected things and mobile communication devices are temporarily created by means of dynamic URLs (uniform resource locators) which may be [...] Read more.

The aim of this paper is to determine the physical proximity of connected things when they are accessed from a smartphone. Links between connected things and mobile communication devices are temporarily created by means of dynamic URLs (uniform resource locators) which may be easily discovered with pervasive short-range radio frequency technologies available on smartphones. In addition, a multi cross domain silent logging mechanism to allow people to interact with their surrounding connected things from their mobile communication devices is presented. The proposed mechanisms are based in web standards technologies, evolving our social network of Internet of Things towards the so-called Web of Things. Full article

(This article belongs to the Special Issue Recent Advances in Sensor Technologies and Applications in the Web of Things (WoT))

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22 pages, 3058 KiB

Open AccessArticle

Fault Diagnosis Based on Chemical Sensor Data with an Active Deep Neural Network

by Peng Jiang, Zhixin Hu, Jun Liu, Shanen Yu and Feng Wu

Sensors 2016, 16(10), 1695; https://doi.org/10.3390/s16101695 - 13 Oct 2016

Cited by 56 | Viewed by 7549

Abstract

Big sensor data provide significant potential for chemical fault diagnosis, which involves the baseline values of security, stability and reliability in chemical processes. A deep neural network (DNN) with novel active learning for inducing chemical fault diagnosis is presented in this study. It [...] Read more.

Big sensor data provide significant potential for chemical fault diagnosis, which involves the baseline values of security, stability and reliability in chemical processes. A deep neural network (DNN) with novel active learning for inducing chemical fault diagnosis is presented in this study. It is a method using large amount of chemical sensor data, which is a combination of deep learning and active learning criterion to target the difficulty of consecutive fault diagnosis. DNN with deep architectures, instead of shallow ones, could be developed through deep learning to learn a suitable feature representation from raw sensor data in an unsupervised manner using stacked denoising auto-encoder (SDAE) and work through a layer-by-layer successive learning process. The features are added to the top Softmax regression layer to construct the discriminative fault characteristics for diagnosis in a supervised manner. Considering the expensive and time consuming labeling of sensor data in chemical applications, in contrast to the available methods, we employ a novel active learning criterion for the particularity of chemical processes, which is a combination of Best vs. Second Best criterion (BvSB) and a Lowest False Positive criterion (LFP), for further fine-tuning of diagnosis model in an active manner rather than passive manner. That is, we allow models to rank the most informative sensor data to be labeled for updating the DNN parameters during the interaction phase. The effectiveness of the proposed method is validated in two well-known industrial datasets. Results indicate that the proposed method can obtain superior diagnosis accuracy and provide significant performance improvement in accuracy and false positive rate with less labeled chemical sensor data by further active learning compared with existing methods. Full article

(This article belongs to the Section Sensor Networks)

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21 pages, 10256 KiB

Open AccessArticle

Development and Testing of a Two-UAV Communication Relay System

by Boyang Li, Yifan Jiang, Jingxuan Sun, Lingfeng Cai and Chih-Yung Wen

Sensors 2016, 16(10), 1696; https://doi.org/10.3390/s16101696 - 13 Oct 2016

Cited by 60 | Viewed by 16610

Abstract

In the development of beyond-line-of-sight (BLOS) Unmanned Aerial Vehicle (UAV) systems, communication between the UAVs and the ground control station (GCS) is of critical importance. The commonly used economical wireless modules are restricted by the short communication range and are easily blocked by [...] Read more.

In the development of beyond-line-of-sight (BLOS) Unmanned Aerial Vehicle (UAV) systems, communication between the UAVs and the ground control station (GCS) is of critical importance. The commonly used economical wireless modules are restricted by the short communication range and are easily blocked by obstacles. The use of a communication relay system provides a practical way to solve these problems, improving the performance of UAV communication in BLOS and cross-obstacle operations. In this study, a communication relay system, in which a quadrotor was used to relay radio communication for another quadrotor was developed and tested. First, the UAVs used as the airborne platform were constructed, and the hardware for the communication relay system was selected and built up. Second, a set of software programs and protocol for autonomous mission control, communication relay control, and ground control were developed. Finally, the system was fully integrated into the airborne platform and tested both indoor and in-flight. The Received Signal Strength Indication (RSSI) and noise value in two typical application scenarios were recorded. The test results demonstrated the ability of this system to extend the communication range and build communication over obstacles. This system also shows the feasibility to coordinate multiple UAVs’ communication with the same relay structure. Full article

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

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12 pages, 2762 KiB

Open AccessArticle

Selectivity Enhancement in Molecularly Imprinted Polymers for Binding of Bisphenol A

by Noof A. Alenazi, Jeffrey M. Manthorpe and Edward P. C. Lai

Sensors 2016, 16(10), 1697; https://doi.org/10.3390/s16101697 - 14 Oct 2016

Cited by 21 | Viewed by 5970

Abstract

Bisphenol A (BPA) is an estrogen-mimicking chemical that can be selectively detected in water using a chemical sensor based on molecularly imprinted polymers (MIPs). However, the utility of BPA-MIPs in sensor applications is limited by the presence of non-specific binding sites. This study [...] Read more.

Bisphenol A (BPA) is an estrogen-mimicking chemical that can be selectively detected in water using a chemical sensor based on molecularly imprinted polymers (MIPs). However, the utility of BPA-MIPs in sensor applications is limited by the presence of non-specific binding sites. This study explored a dual approach to eliminating these sites: optimizing the molar ratio of the template (bisphenol A) to functional monomer (methacrylic acid) to cross-linker (ethylene glycol dimethacrylate), and esterifying the carboxylic acid residues outside of specific binding sites by treatment with diazomethane. The binding selectivity of treated MIPs and non-treated MIPs for BPA and several potential interferents was compared by capillary electrophoresis with ultraviolet detection. Baclofen, diclofenac and metformin were demonstrated to be good model interferents to test all MIPs for selective binding of BPA. Treated MIPs demonstrated a significant decrease in binding of the interferents while offering high selectivity toward BPA. These results demonstrate that conventional optimization of the molar ratio, together with advanced esterification of non-specific binding sites, effectively minimizes the residual binding of interferents with MIPs to facilitate BPA sensing. Full article

(This article belongs to the Special Issue Molecular Imprinting and Functional Polymers for all Transducers and Applications)

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14 pages, 3954 KiB

Open AccessArticle

Performance Evaluation and Community Application of Low-Cost Sensors for Ozone and Nitrogen Dioxide

by Rachelle M. Duvall, Russell W. Long, Melinda R. Beaver, Keith G. Kronmiller, Michael L. Wheeler and James J. Szykman

Sensors 2016, 16(10), 1698; https://doi.org/10.3390/s16101698 - 13 Oct 2016

Cited by 59 | Viewed by 8291

Abstract

This study reports on the performance of electrochemical-based low-cost sensors and their use in a community application. CairClip sensors were collocated with federal reference and equivalent methods and operated in a network of sites by citizen scientists (community members) in Houston, Texas and [...] Read more.

This study reports on the performance of electrochemical-based low-cost sensors and their use in a community application. CairClip sensors were collocated with federal reference and equivalent methods and operated in a network of sites by citizen scientists (community members) in Houston, Texas and Denver, Colorado, under the umbrella of the NASA-led DISCOVER-AQ Earth Venture Mission. Measurements were focused on ozone (O₃) and nitrogen dioxide (NO₂). The performance evaluation showed that the CairClip O₃/NO₂ sensor provided a consistent measurement response to that of reference monitors (r² = 0.79 in Houston; r² = 0.72 in Denver) whereas the CairClip NO₂ sensor measurements showed no agreement to reference measurements. The CairClip O₃/NO₂ sensor data from the citizen science sites compared favorably to measurements at nearby reference monitoring sites. This study provides important information on data quality from low-cost sensor technologies and is one of few studies that reports sensor data collected directly by citizen scientists. Full article

(This article belongs to the Section Chemical Sensors)

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10 pages, 2004 KiB

Open AccessArticle

A Graphene Oxide-Based Fluorescent Method for the Detection of Human Chorionic Gonadotropin

by Ning Xia, Xin Wang and Lin Liu

Sensors 2016, 16(10), 1699; https://doi.org/10.3390/s16101699 - 13 Oct 2016

Cited by 25 | Viewed by 8043

Abstract

Human chorionic gonadotropin (hCG) has been regarded as a biomarker for the diagnosis of pregnancy and some cancers. Because the currently used methods (e.g., disposable Point of Care Testing (POCT) device) for hCG detection require the use of many less stable antibodies, simple [...] Read more.

Human chorionic gonadotropin (hCG) has been regarded as a biomarker for the diagnosis of pregnancy and some cancers. Because the currently used methods (e.g., disposable Point of Care Testing (POCT) device) for hCG detection require the use of many less stable antibodies, simple and cost-effective methods for the sensitive and selective detection of hCG have always been desired. In this work, we have developed a graphene oxide (GO)-based fluorescent platform for the detection of hCG using a fluorescein isothiocyanate (FITC)-labeled hCG-specific binding peptide aptamer (denoted as FITC-PPLRINRHILTR) as the probe, which can be manufactured cheaply and consistently. Specifically, FITC-PPLRINRHILTR adsorbed onto the surface of GO via electrostatic interaction showed a poor fluorescence signal. The specific binding of hCG to FITC-PPLRINRHILTR resulted in the release of the peptide from the GO surface. As a result, an enhanced fluorescence signal was observed. The fluorescence intensity was directly proportional to the hCG concentration in the range of 0.05–20 IU/mL. The detection limit was found to be 20 mIU/mL. The amenability of the strategy to hCG analysis in biological fluids was demonstrated by assaying hCG in the urine samples. Full article

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

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15 pages, 8396 KiB

Open AccessArticle

A Stepped Frequency Sweeping Method for Nonlinearity Measurement of Microresonators

by Yumiao Wei, Yonggui Dong, Xianxiang Huang and Zhili Zhang

Sensors 2016, 16(10), 1700; https://doi.org/10.3390/s16101700 - 13 Oct 2016

Cited by 13 | Viewed by 6111

Abstract

In order to measure the nonlinear features of micromechanical resonators, a free damped oscillation method based on stair-stepped frequency sinusoidal pulse excitation is investigated. In the vicinity of the resonant frequency, a frequency stepping sinusoidal pulse sequence is employed as the excitation signal. [...] Read more.

In order to measure the nonlinear features of micromechanical resonators, a free damped oscillation method based on stair-stepped frequency sinusoidal pulse excitation is investigated. In the vicinity of the resonant frequency, a frequency stepping sinusoidal pulse sequence is employed as the excitation signal. A set of free vibration response signals, containing different degrees of nonlinear dynamical characteristics, are obtained. The amplitude-frequency curves of the resonator are acquired from the forced vibration signals. Together with a singular spectrum analysis algorithm, the instantaneous amplitudes and instantaneous frequencies are extracted by a Hilbert transform from the free vibration signals. The calculated Backbone curves, and frequency response function (FRF) curves are distinct and can be used to characterize the nonlinear dynamics of the resonator. Taking a Duffing system as an example, numerical simulations are carried out for free vibration response signals in cases of different signal-to-noise ratios (SNRs). The results show that this method displays better anti-noise performance than FREEVIB. A vibrating ring microgyroscope is experimentally tested. The obtained Backbone and FRF curves agree with those obtained by the traditional frequency sweeping method. As a test technique, the proposed method can also be used to for experimentally testing the dynamic characteristics of other types of micromechanical resonators. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 867 KiB

Open AccessArticle

A Hybrid Spectral Clustering and Deep Neural Network Ensemble Algorithm for Intrusion Detection in Sensor Networks

by Tao Ma, Fen Wang, Jianjun Cheng, Yang Yu and Xiaoyun Chen

Sensors 2016, 16(10), 1701; https://doi.org/10.3390/s16101701 - 13 Oct 2016

Cited by 202 | Viewed by 12277

Abstract

The development of intrusion detection systems (IDS) that are adapted to allow routers and network defence systems to detect malicious network traffic disguised as network protocols or normal access is a critical challenge. This paper proposes a novel approach called SCDNN, which combines [...] Read more.

The development of intrusion detection systems (IDS) that are adapted to allow routers and network defence systems to detect malicious network traffic disguised as network protocols or normal access is a critical challenge. This paper proposes a novel approach called SCDNN, which combines spectral clustering (SC) and deep neural network (DNN) algorithms. First, the dataset is divided into k subsets based on sample similarity using cluster centres, as in SC. Next, the distance between data points in a testing set and the training set is measured based on similarity features and is fed into the deep neural network algorithm for intrusion detection. Six KDD-Cup99 and NSL-KDD datasets and a sensor network dataset were employed to test the performance of the model. These experimental results indicate that the SCDNN classifier not only performs better than backpropagation neural network (BPNN), support vector machine (SVM), random forest (RF) and Bayes tree models in detection accuracy and the types of abnormal attacks found. It also provides an effective tool of study and analysis of intrusion detection in large networks. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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26 pages, 3444 KiB

Open AccessArticle

A Novel Energy Efficient Topology Control Scheme Based on a Coverage-Preserving and Sleep Scheduling Model for Sensor Networks

by Binbin Shi, Wei Wei, Yihuai Wang and Wanneng Shu

Sensors 2016, 16(10), 1702; https://doi.org/10.3390/s16101702 - 14 Oct 2016

Cited by 10 | Viewed by 5007

Abstract

In high-density sensor networks, scheduling some sensor nodes to be in the sleep mode while other sensor nodes remain active for monitoring or forwarding packets is an effective control scheme to conserve energy. In this paper, a Coverage-Preserving Control Scheduling Scheme (CPCSS) based [...] Read more.

In high-density sensor networks, scheduling some sensor nodes to be in the sleep mode while other sensor nodes remain active for monitoring or forwarding packets is an effective control scheme to conserve energy. In this paper, a Coverage-Preserving Control Scheduling Scheme (CPCSS) based on a cloud model and redundancy degree in sensor networks is proposed. Firstly, the normal cloud model is adopted for calculating the similarity degree between the sensor nodes in terms of their historical data, and then all nodes in each grid of the target area can be classified into several categories. Secondly, the redundancy degree of a node is calculated according to its sensing area being covered by the neighboring sensors. Finally, a centralized approximation algorithm based on the partition of the target area is designed to obtain the approximate minimum set of nodes, which can retain the sufficient coverage of the target region and ensure the connectivity of the network at the same time. The simulation results show that the proposed CPCSS can balance the energy consumption and optimize the coverage performance of the sensor network. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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17 pages, 3420 KiB

Open AccessArticle

Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells

by Yanjun Wang, Haoyu Li, Xingbin Liu, Yuhui Zhang, Ronghua Xie, Chunhui Huang, Jinhai Hu and Gang Deng

Sensors 2016, 16(10), 1703; https://doi.org/10.3390/s16101703 - 14 Oct 2016

Cited by 22 | Viewed by 6771

Abstract

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried [...] Read more.

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5–60 m³/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2–60 m³/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 6018 KiB

Open AccessArticle

A Robust Method for Ego-Motion Estimation in Urban Environment Using Stereo Camera

by Wenyan Ci and Yingping Huang

Sensors 2016, 16(10), 1704; https://doi.org/10.3390/s16101704 - 17 Oct 2016

Cited by 14 | Viewed by 8192

Abstract

Visual odometry estimates the ego-motion of an agent (e.g., vehicle and robot) using image information and is a key component for autonomous vehicles and robotics. This paper proposes a robust and precise method for estimating the 6-DoF ego-motion, using a stereo rig with [...] Read more.

Visual odometry estimates the ego-motion of an agent (e.g., vehicle and robot) using image information and is a key component for autonomous vehicles and robotics. This paper proposes a robust and precise method for estimating the 6-DoF ego-motion, using a stereo rig with optical flow analysis. An objective function fitted with a set of feature points is created by establishing the mathematical relationship between optical flow, depth and camera ego-motion parameters through the camera’s 3-dimensional motion and planar imaging model. Accordingly, the six motion parameters are computed by minimizing the objective function, using the iterative Levenberg–Marquard method. One of key points for visual odometry is that the feature points selected for the computation should contain inliers as much as possible. In this work, the feature points and their optical flows are initially detected by using the Kanade–Lucas–Tomasi (KLT) algorithm. A circle matching is followed to remove the outliers caused by the mismatching of the KLT algorithm. A space position constraint is imposed to filter out the moving points from the point set detected by the KLT algorithm. The Random Sample Consensus (RANSAC) algorithm is employed to further refine the feature point set, i.e., to eliminate the effects of outliers. The remaining points are tracked to estimate the ego-motion parameters in the subsequent frames. The approach presented here is tested on real traffic videos and the results prove the robustness and precision of the method. Full article

(This article belongs to the Special Issue Sensors for Autonomous Road Vehicles)

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18 pages, 3590 KiB

Open AccessArticle

Integration of Error Compensation of Coordinate Measuring Machines into Feature Measurement: Part II—Experimental Implementation

by Roque Calvo, Roberto D’Amato, Emilio Gómez and Rosario Domingo

Sensors 2016, 16(10), 1705; https://doi.org/10.3390/s16101705 - 14 Oct 2016

Cited by 9 | Viewed by 6768

Abstract

Coordinate measuring machines (CMM) are main instruments of measurement in laboratories and in industrial quality control. A compensation error model has been formulated (Part I). It integrates error and uncertainty in the feature measurement model. Experimental implementation for the verification of this model [...] Read more.

Coordinate measuring machines (CMM) are main instruments of measurement in laboratories and in industrial quality control. A compensation error model has been formulated (Part I). It integrates error and uncertainty in the feature measurement model. Experimental implementation for the verification of this model is carried out based on the direct testing on a moving bridge CMM. The regression results by axis are quantified and compared to CMM indication with respect to the assigned values of the measurand. Next, testing of selected measurements of length, flatness, dihedral angle, and roundness features are accomplished. The measurement of calibrated gauge blocks for length or angle, flatness verification of the CMM granite table and roundness of a precision glass hemisphere are presented under a setup of repeatability conditions. The results are analysed and compared with alternative methods of estimation. The overall performance of the model is endorsed through experimental verification, as well as the practical use and the model capability to contribute in the improvement of current standard CMM measuring capabilities. Full article

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

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26 pages, 4106 KiB

Open AccessArticle

An Efficient Recommendation Filter Model on Smart Home Big Data Analytics for Enhanced Living Environments

by Hao Chen, Xiaoyun Xie, Wanneng Shu and Naixue Xiong

Sensors 2016, 16(10), 1706; https://doi.org/10.3390/s16101706 - 15 Oct 2016

Cited by 11 | Viewed by 7961

Abstract

With the rapid growth of wireless sensor applications, the user interfaces and configurations of smart homes have become so complicated and inflexible that users usually have to spend a great amount of time studying them and adapting to their expected operation. In order [...] Read more.

With the rapid growth of wireless sensor applications, the user interfaces and configurations of smart homes have become so complicated and inflexible that users usually have to spend a great amount of time studying them and adapting to their expected operation. In order to improve user experience, a weighted hybrid recommender system based on a Kalman Filter model is proposed to predict what users might want to do next, especially when users are located in a smart home with an enhanced living environment. Specifically, a weight hybridization method was introduced, which combines contextual collaborative filter and the contextual content-based recommendations. This method inherits the advantages of the optimum regression and the stability features of the proposed adaptive Kalman Filter model, and it can predict and revise the weight of each system component dynamically. Experimental results show that the hybrid recommender system can optimize the distribution of weights of each component, and achieve more reasonable recall and precision rates. Full article

(This article belongs to the Special Issue Multisensory Big Data Analytics for Enhanced Living Environments)

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18 pages, 7101 KiB

Open AccessArticle

A Temperature Compensation Method for Piezo-Resistive Pressure Sensor Utilizing Chaotic Ions Motion Algorithm Optimized Hybrid Kernel LSSVM

by Ji Li, Guoqing Hu, Yonghong Zhou, Chong Zou, Wei Peng and Jahangir Alam SM

Sensors 2016, 16(10), 1707; https://doi.org/10.3390/s16101707 - 14 Oct 2016

Cited by 26 | Viewed by 6215

Abstract

A piezo-resistive pressure sensor is made of silicon, the nature of which is considerably influenced by ambient temperature. The effect of temperature should be eliminated during the working period in expectation of linear output. To deal with this issue, an approach consists of [...] Read more.

A piezo-resistive pressure sensor is made of silicon, the nature of which is considerably influenced by ambient temperature. The effect of temperature should be eliminated during the working period in expectation of linear output. To deal with this issue, an approach consists of a hybrid kernel Least Squares Support Vector Machine (LSSVM) optimized by a chaotic ions motion algorithm presented. To achieve the learning and generalization for excellent performance, a hybrid kernel function, constructed by a local kernel as Radial Basis Function (RBF) kernel, and a global kernel as polynomial kernel is incorporated into the Least Squares Support Vector Machine. The chaotic ions motion algorithm is introduced to find the best hyper-parameters of the Least Squares Support Vector Machine. The temperature data from a calibration experiment is conducted to validate the proposed method. With attention on algorithm robustness and engineering applications, the compensation result shows the proposed scheme outperforms other compared methods on several performance measures as maximum absolute relative error, minimum absolute relative error mean and variance of the averaged value on fifty runs. Furthermore, the proposed temperature compensation approach lays a foundation for more extensive research. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 3993 KiB

Open AccessArticle

Self-Tuning Fully-Connected PID Neural Network System for Distributed Temperature Sensing and Control of Instrument with Multi-Modules

by Zhen Zhang, Cheng Ma and Rong Zhu

Sensors 2016, 16(10), 1709; https://doi.org/10.3390/s16101709 - 14 Oct 2016

Cited by 6 | Viewed by 7629

Abstract

High integration of multi-functional instruments raises a critical issue in temperature control that is challenging due to its spatial–temporal complexity. This paper presents a multi-input multi-output (MIMO) self-tuning temperature sensing and control system for efficiently modulating the temperature environment within a multi-module instrument. [...] Read more.

High integration of multi-functional instruments raises a critical issue in temperature control that is challenging due to its spatial–temporal complexity. This paper presents a multi-input multi-output (MIMO) self-tuning temperature sensing and control system for efficiently modulating the temperature environment within a multi-module instrument. The smart system ensures that the internal temperature of the instrument converges to a target without the need of a system model, thus making the control robust. The system consists of a fully-connected proportional–integral–derivative (PID) neural network (FCPIDNN) and an on-line self-tuning module. The experimental results show that the presented system can effectively control the internal temperature under various mission scenarios, in particular, it is able to self-reconfigure upon actuator failure. The system provides a new scheme for a complex and time-variant MIMO control system which can be widely applied for the distributed measurement and control of the environment in instruments, integration electronics, and house constructions. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2753 KiB

Open AccessArticle

A Low-Power All-Digital on-Chip CMOS Oscillator for a Wireless Sensor Node

by Duo Sheng and Min-Rong Hong

Sensors 2016, 16(10), 1710; https://doi.org/10.3390/s16101710 - 14 Oct 2016

Cited by 1 | Viewed by 4468

Abstract

This paper presents an all-digital low-power oscillator for reference clocks in wireless body area network (WBAN) applications. The proposed on-chip complementary metal-oxide-semiconductor (CMOS) oscillator provides low-frequency clock signals with low power consumption, high delay resolution, and low circuit complexity. The cascade-stage structure of [...] Read more.

This paper presents an all-digital low-power oscillator for reference clocks in wireless body area network (WBAN) applications. The proposed on-chip complementary metal-oxide-semiconductor (CMOS) oscillator provides low-frequency clock signals with low power consumption, high delay resolution, and low circuit complexity. The cascade-stage structure of the proposed design simultaneously achieves high resolution and a wide frequency range. The proposed hysteresis delay cell further reduces the power consumption and hardware costs by 92.4% and 70.4%, respectively, relative to conventional designs. The proposed design is implemented in a standard performance 0.18 μm CMOS process. The measured operational frequency ranged from 7 to 155 MHz, and the power consumption was improved to 79.6 μW (@7 MHz) with a 4.6 ps resolution. The proposed design can be implemented in an all-digital manner, which is highly desirable for system-level integration. Full article

(This article belongs to the Section Physical Sensors)

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22 pages, 929 KiB

Open AccessArticle

Performance Analysis of Integrated Wireless Sensor and Multibeam Satellite Networks Under Terrestrial Interference

by Hongjun Li, Hao Yin, Xiangwu Gong, Feihong Dong, Baoquan Ren, Yuanzhi He and Jingchao Wang

Sensors 2016, 16(10), 1711; https://doi.org/10.3390/s16101711 - 14 Oct 2016

Cited by 7 | Viewed by 4532

Abstract

This paper investigates the performance of integrated wireless sensor and multibeam satellite networks (IWSMSNs) under terrestrial interference. The IWSMSNs constitute sensor nodes (SNs), satellite sinks (SSs), multibeam satellite and remote monitoring hosts (RMHs). The multibeam satellite covers multiple beams and multiple SSs in [...] Read more.

This paper investigates the performance of integrated wireless sensor and multibeam satellite networks (IWSMSNs) under terrestrial interference. The IWSMSNs constitute sensor nodes (SNs), satellite sinks (SSs), multibeam satellite and remote monitoring hosts (RMHs). The multibeam satellite covers multiple beams and multiple SSs in each beam. The SSs can be directly used as SNs to transmit sensing data to RMHs via the satellite, and they can also be used to collect the sensing data from other SNs to transmit to the RMHs. We propose the hybrid one-dimensional (1D) and 2D beam models including the equivalent intra-beam interference factor β from terrestrial communication networks (TCNs) and the equivalent inter-beam interference factor α from adjacent beams. The terrestrial interference is possibly due to the signals from the TCNs or the signals of sinks being transmitted to other satellite networks. The closed-form approximations of capacity per beam are derived for the return link of IWSMSNs under terrestrial interference by using the Haar approximations where the IWSMSNs experience the Rician fading channel. The optimal joint decoding capacity can be considered as the upper bound where all of the SSs’ signals can be jointly decoded by a super-receiver on board the multibeam satellite or a gateway station that knows all of the code books. While the linear minimum mean square error (MMSE) capacity is where all of the signals of SSs are decoded singularly by a multibeam satellite or a gateway station. The simulations show that the optimal capacities are obviously higher than the MMSE capacities under the same conditions, while the capacities are lowered by Rician fading and converge as the Rician factor increases. α and β jointly affect the performance of hybrid 1D and 2D beam models, and the number of SSs also contributes different effects on the optimal capacity and MMSE capacity of the IWSMSNs. Full article

(This article belongs to the Section Sensor Networks)

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12 pages, 4040 KiB

Open AccessArticle

Use of Distributed Temperature Sensing Technology to Characterize Fire Behavior

by Douglas Cram, Christine E. Hatch, Scott Tyler and Carlos Ochoa

Sensors 2016, 16(10), 1712; https://doi.org/10.3390/s16101712 - 17 Oct 2016

Cited by 16 | Viewed by 6750

Abstract

We evaluated the potential of a fiber optic cable connected to distributed temperature sensing (DTS) technology to withstand wildland fire conditions and quantify fire behavior parameters. We used a custom-made ‘fire cable’ consisting of three optical fibers coated with three different materials—acrylate, copper [...] Read more.

We evaluated the potential of a fiber optic cable connected to distributed temperature sensing (DTS) technology to withstand wildland fire conditions and quantify fire behavior parameters. We used a custom-made ‘fire cable’ consisting of three optical fibers coated with three different materials—acrylate, copper and polyimide. The 150-m cable was deployed in grasslands and burned in three prescribed fires. The DTS system recorded fire cable output every three seconds and integrated temperatures every 50.6 cm. Results indicated the fire cable was physically capable of withstanding repeated rugged use. Fiber coating materials withstood temperatures up to 422 °C. Changes in fiber attenuation following fire were near zero (−0.81 to 0.12 dB/km) indicating essentially no change in light gain or loss as a function of distance or fire intensity over the length of the fire cable. Results indicated fire cable and DTS technology have potential to quantify fire environment parameters such as heat duration and rate of spread but additional experimentation and analysis are required to determine efficacy and response times. This study adds understanding of DTS and fire cable technology as a potential new method for characterizing fire behavior parameters at greater temporal and spatial scales. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 4729 KiB

Open AccessArticle

Hierarchical Activity Recognition Using Smart Watches and RGB-Depth Cameras

by Zhen Li, Zhiqiang Wei, Lei Huang, Shugang Zhang and Jie Nie

Sensors 2016, 16(10), 1713; https://doi.org/10.3390/s16101713 - 15 Oct 2016

Cited by 7 | Viewed by 5808

Abstract

Human activity recognition is important for healthcare and lifestyle evaluation. In this paper, a novel method for activity recognition by jointly considering motion sensor data recorded by wearable smart watches and image data captured by RGB-Depth (RGB-D) cameras is presented. A normalized cross [...] Read more.

Human activity recognition is important for healthcare and lifestyle evaluation. In this paper, a novel method for activity recognition by jointly considering motion sensor data recorded by wearable smart watches and image data captured by RGB-Depth (RGB-D) cameras is presented. A normalized cross correlation based mapping method is implemented to establish association between motion sensor data with corresponding image data from the same person in multi-person situations. Further, to improve the performance and accuracy of recognition, a hierarchical structure embedded with an automatic group selection method is proposed. Through this method, if the number of activities to be classified is changed, the structure will be changed correspondingly without interaction. Our comparative experiments against the single data source and single layer methods have shown that our method is more accurate and robust. Full article

(This article belongs to the Special Issue Body Worn Behavior Sensing)

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16 pages, 2058 KiB

Open AccessArticle

Coarse Alignment of Marine Strapdown INS Based on the Trajectory Fitting of Gravity Movement in the Inertial Space

by Lin Zhao, Dongxue Guan, Jianhua Cheng, Xiaomin Xu and Zaihui Fei

Sensors 2016, 16(10), 1714; https://doi.org/10.3390/s16101714 - 15 Oct 2016

Cited by 8 | Viewed by 6113

Abstract

A ship experiences the random motion of sea waves during its travels. Hence, the coarse alignment of the marine strapdown Inertial Navigation System (INS) suffers from rocking disturbances such as pitch and roll. In this paper, a novel approach of marine coarse alignment [...] Read more.

A ship experiences the random motion of sea waves during its travels. Hence, the coarse alignment of the marine strapdown Inertial Navigation System (INS) suffers from rocking disturbances such as pitch and roll. In this paper, a novel approach of marine coarse alignment was proposed for avoiding the resulting loss of accuracy from rocking disturbances. Unlike several current techniques, our alignment scheme is intuitional and concise. Moreover, the coarse alignment can be implemented without any external information. The gravity vector and its derivative expressed within the inertial frame can describe the attitude matrix between an inertial frame and the local geographic frame. We address the challenge of calculating the gravity derivative by the least-squares fitting of the trajectory of the gravity movement in the inertial frame. Meanwhile, the integration of angular rates measured by gyroscopes allows one to compute the attitude matrix between the inertial frame and the body frame. The coarse alignment can be thus accomplished by the combination of the above two attitude matrices. The experimental results show that the coarse alignment is effective with high accuracy and stability for demanding marine applications. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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16 pages, 4573 KiB

Open AccessArticle

Accurate Attitude Estimation Using ARS under Conditions of Vehicle Movement Based on Disturbance Acceleration Adaptive Estimation and Correction

by Li Xing, Yijun Hang, Zhi Xiong, Jianye Liu and Zhong Wan

Sensors 2016, 16(10), 1716; https://doi.org/10.3390/s16101716 - 16 Oct 2016

Cited by 9 | Viewed by 5192

Abstract

This paper describes a disturbance acceleration adaptive estimate and correction approach for an attitude reference system (ARS) so as to improve the attitude estimate precision under vehicle movement conditions. The proposed approach depends on a Kalman filter, where the attitude error, the gyroscope [...] Read more.

This paper describes a disturbance acceleration adaptive estimate and correction approach for an attitude reference system (ARS) so as to improve the attitude estimate precision under vehicle movement conditions. The proposed approach depends on a Kalman filter, where the attitude error, the gyroscope zero offset error and the disturbance acceleration error are estimated. By switching the filter decay coefficient of the disturbance acceleration model in different acceleration modes, the disturbance acceleration is adaptively estimated and corrected, and then the attitude estimate precision is improved. The filter was tested in three different disturbance acceleration modes (non-acceleration, vibration-acceleration and sustained-acceleration mode, respectively) by digital simulation. Moreover, the proposed approach was tested in a kinematic vehicle experiment as well. Using the designed simulations and kinematic vehicle experiments, it has been shown that the disturbance acceleration of each mode can be accurately estimated and corrected. Moreover, compared with the complementary filter, the experimental results have explicitly demonstrated the proposed approach further improves the attitude estimate precision under vehicle movement conditions. Full article

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

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16 pages, 4168 KiB

Open AccessArticle

Analysis of the Effects of Thermal Environment on Optical Systems for Navigation Guidance and Control in Supersonic Aircraft Based on Empirical Equations

by Xuemin Cheng, Yikang Yang and Qun Hao

Sensors 2016, 16(10), 1717; https://doi.org/10.3390/s16101717 - 17 Oct 2016

Cited by 9 | Viewed by 5508

Abstract

The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal [...] Read more.

The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal diffusion distance, and for basic factors such as flying parameters and the structure of the optical system. Finite element analysis (FEA) was used to study the relationship between flying and front dome parameters and the system temperature field. Systematic deduction was then conducted based on the effects of the temperature field on the physical geometry and ray tracing performance of the front dome and rear optical lenses, by deriving the relational expressions between the system temperature field and the spot size and positioning precision of the rear optical lens. The optical systems used for navigation guidance and control in supersonic aircraft when the flight speed is in the range of 1–5 Ma were analysed using the derived equations. Using this new method it was possible to control the precision within 10% when considering the light spot received by the four-quadrant detector, and computation time was reduced compared with the traditional method of separately analysing the temperature field of the front dome and rear optical lens using FEA. Thus, the method can effectively increase the efficiency of parameter analysis and computation in an airborne optical system, facilitating the systematic, effective and integrated thermal analysis of airborne optical systems for navigation guidance and control. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 10009 KiB

Open AccessArticle

Hierarchical Sparse Learning with Spectral-Spatial Information for Hyperspectral Imagery Denoising

by Shuai Liu, Licheng Jiao and Shuyuan Yang

Sensors 2016, 16(10), 1718; https://doi.org/10.3390/s16101718 - 17 Oct 2016

Cited by 13 | Viewed by 4975

Abstract

During the acquisition process hyperspectral images (HSI) are inevitably corrupted by various noises, which greatly influence their visual impression and subsequent applications. In this paper, a novel Bayesian approach integrating hierarchical sparse learning and spectral-spatial information is proposed for HSI denoising. Based on [...] Read more.

During the acquisition process hyperspectral images (HSI) are inevitably corrupted by various noises, which greatly influence their visual impression and subsequent applications. In this paper, a novel Bayesian approach integrating hierarchical sparse learning and spectral-spatial information is proposed for HSI denoising. Based on the structure correlations, spectral bands with similar and continuous features are segmented into the same band-subset. To exploit local similarity, each subset is then divided into overlapping cubic patches. All patches can be regarded as consisting of clean image component, Gaussian noise component and sparse noise component. The first term is depicted by a linear combination of dictionary elements, where Gaussian process with Gamma distribution is applied to impose spatial consistency on dictionary. The last two terms are utilized to fully depict the noise characteristics. Furthermore, the sparseness of the model is adaptively manifested through Beta-Bernoulli process. Calculated by Gibbs sampler, the proposed model can directly predict the noise and dictionary without priori information of the degraded HSI. The experimental results on both synthetic and real HSI demonstrate that the proposed approach can better suppress the existing various noises and preserve the structure/spectral-spatial information than the compared state-of-art approaches. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 3467 KiB

Open AccessArticle

Electrochemical Selective and Simultaneous Detection of Diclofenac and Ibuprofen in Aqueous Solution Using HKUST-1 Metal-Organic Framework-Carbon Nanofiber Composite Electrode

by Sorina Motoc, Florica Manea, Adriana Iacob, Alberto Martinez-Joaristi, Jorge Gascon, Aniela Pop and Joop Schoonman

Sensors 2016, 16(10), 1719; https://doi.org/10.3390/s16101719 - 17 Oct 2016

Cited by 43 | Viewed by 7743

Abstract

In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP) and diclofenac (DCF) in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF) electrode. The morphological and electrical characterization of modified composite electrode prepared [...] Read more.

In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP) and diclofenac (DCF) in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF) electrode. The morphological and electrical characterization of modified composite electrode prepared by film casting was studied by scanning electronic microscopy and four-point-probe methods. The electrochemical characterization of the electrode by cyclic voltammetry (CV) was considered the reference basis for the optimization of the operating conditions for chronoamperometry (CA) and multiple-pulsed amperometry (MPA). This electrode exhibited the possibility to selectively detect IBP and DCF by simple switching the detection potential using CA. However, the MPA operated under optimum working conditions of four potential levels selected based on CV shape in relation to the potential value, pulse time, and potential level number, and order allowed the selective/simultaneous detection of IBP and DCF characterized by the enhanced detection performance. For this application, the HKUST-CNF electrode exhibited a good stability and reproducibility of the results was achieved. Full article

(This article belongs to the Section Chemical Sensors)

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10 pages, 2105 KiB

Open AccessArticle

Non-Enzymatic Glucose Sensing Using Carbon Quantum Dots Decorated with Copper Oxide Nanoparticles

by Houcem Maaoui, Florina Teodoresu, Qian Wang, Guo-Hui Pan, Ahmed Addad, Radhouane Chtourou, Sabine Szunerits and Rabah Boukherroub

Sensors 2016, 16(10), 1720; https://doi.org/10.3390/s16101720 - 18 Oct 2016

Cited by 48 | Viewed by 10022

Abstract

Perturbations in glucose homeostasis is critical for human health, as hyperglycemia (defining diabetes) leads to premature death caused by macrovascular and microvascular complications. However, the simple and accurate detection of glucose in the blood at low cost remains a challenging task, although it [...] Read more.

Perturbations in glucose homeostasis is critical for human health, as hyperglycemia (defining diabetes) leads to premature death caused by macrovascular and microvascular complications. However, the simple and accurate detection of glucose in the blood at low cost remains a challenging task, although it is of great importance for the diagnosis and therapy of diabetic patients. In this work, carbon quantum dots decorated with copper oxide nanostructures (CQDs/Cu₂O) are prepared by a simple hydrothermal approach, and their potential for electrochemical non-enzymatic glucose sensing is evaluated. The proposed sensor exhibits excellent electrocatalytic activity towards glucose oxidation in alkaline solutions. The glucose sensor is characterized by a wide concentration range from 6 µM to 6 mM, a sensitivity of 2.9 ± 0.2 µA·µM⁻¹·cm⁻², and a detection limit of 6 µM at a signal-to-noise ratio S/N = 3. The sensors are successfully applied for glucose determination in human serum samples, demonstrating that the CQDs/Cu₂O-based glucose sensor satisfies the requirements of complex sample detection with adapted potential for therapeutic diagnostics. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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21 pages, 7658 KiB

Open AccessArticle

Generic Dynamic Environment Perception Using Smart Mobile Devices

by Radu Danescu, Razvan Itu and Andra Petrovai

Sensors 2016, 16(10), 1721; https://doi.org/10.3390/s16101721 - 17 Oct 2016

Cited by 5 | Viewed by 4949

Abstract

The driving environment is complex and dynamic, and the attention of the driver is continuously challenged, therefore computer based assistance achieved by processing image and sensor data may increase traffic safety. While active sensors and stereovision have the advantage of obtaining 3D data [...] Read more.

The driving environment is complex and dynamic, and the attention of the driver is continuously challenged, therefore computer based assistance achieved by processing image and sensor data may increase traffic safety. While active sensors and stereovision have the advantage of obtaining 3D data directly, monocular vision is easy to set up, and can benefit from the increasing computational power of smart mobile devices, and from the fact that almost all of them come with an embedded camera. Several driving assistance application are available for mobile devices, but they are mostly targeted for simple scenarios and a limited range of obstacle shapes and poses. This paper presents a technique for generic, shape independent real-time obstacle detection for mobile devices, based on a dynamic, free form 3D representation of the environment: the particle based occupancy grid. Images acquired in real time from the smart mobile device’s camera are processed by removing the perspective effect and segmenting the resulted bird-eye view image to identify candidate obstacle areas, which are then used to update the occupancy grid. The occupancy grid tracked cells are grouped into obstacles depicted as cuboids having position, size, orientation and speed. The easy to set up system is able to reliably detect most obstacles in urban traffic, and its measurement accuracy is comparable to a stereovision system. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 582 KiB

Open AccessArticle

Estimating Shape and Micro-Motion Parameter of Rotationally Symmetric Space Objects from the Infrared Signature

by Yabei Wu, Huanzhang Lu, Fei Zhao and Zhiyong Zhang

Sensors 2016, 16(10), 1722; https://doi.org/10.3390/s16101722 - 17 Oct 2016

Cited by 11 | Viewed by 4020

Abstract

Shape serves as an important additional feature for space target classification, which is complementary to those made available. Since different shapes lead to different projection functions, the projection property can be regarded as one kind of shape feature. In this work, the problem [...] Read more.

Shape serves as an important additional feature for space target classification, which is complementary to those made available. Since different shapes lead to different projection functions, the projection property can be regarded as one kind of shape feature. In this work, the problem of estimating the projection function from the infrared signature of the object is addressed. We show that the projection function of any rotationally symmetric object can be approximately represented as a linear combination of some base functions. Based on this fact, the signal model of the emissivity-area product sequence is constructed, which is a particular mathematical function of the linear coefficients and micro-motion parameters. Then, the least square estimator is proposed to estimate the projection function and micro-motion parameters jointly. Experiments validate the effectiveness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2142 KiB

Open AccessArticle

The Disturbing Effect of the Stray Magnetic Fields on Magnetoimpedance Sensors

by Tao Wang, Yong Zhou, Chong Lei, Shaotao Zhi, Lei Guo, Hengyu Li, Zhizheng Wu, Shaorong Xie, Jun Luo and Huayan Pu

Sensors 2016, 16(10), 1723; https://doi.org/10.3390/s16101723 - 17 Oct 2016

Cited by 4 | Viewed by 5042

Abstract

The disturbing effect of the stray magnetic fields of Fe-based amorphous ribbons on the giant magnetoimpedance (GMI) sensor has been investigated systematically in this paper. Two simple methods were used for examining the disturbing effect of the stray magnetic fields of ribbons on [...] Read more.

The disturbing effect of the stray magnetic fields of Fe-based amorphous ribbons on the giant magnetoimpedance (GMI) sensor has been investigated systematically in this paper. Two simple methods were used for examining the disturbing effect of the stray magnetic fields of ribbons on the GMI sensor. In order to study the influence of the stray magnetic fields on the GMI effect, the square-shaped amorphous ribbons were tested in front, at the back, on the left and on the top of a meander-line GMI sensor made up of soft ferromagnetic films, respectively. Experimental results show that the presence of ribbons in front or at the back of GMI sensor shifts the GMI curve to a lower external magnetic field. On the contrary, the presence of ribbons on the left or on the top of the GMI sensor shifts the GMI curve to a higher external magnetic field, which is related to the coupling effect of the external magnetic field and the stray magnetic fields. The influence of the area and angle of ribbons on GMI was also studied in this work. The GMI sensor exhibits high linearity for detection of the stray magnetic fields, which has made it feasible to construct a sensitive magnetometer for detecting the typical stray magnetic fields of general soft ferromagnetic materials. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1201 KiB

Open AccessArticle

A Vision-Based Approach for Building Telecare and Telerehabilitation Services

by Angela Barriga, José M. Conejero, Juan Hernández, Elena Jurado, Enrique Moguel and Fernando Sánchez-Figueroa

Sensors 2016, 16(10), 1724; https://doi.org/10.3390/s16101724 - 18 Oct 2016

Cited by 27 | Viewed by 5776

Abstract

In the last few years, telerehabilitation and telecare have become important topics in healthcare since they enable people to remain independent in their own homes by providing person-centered technologies to support the individual. These technologies allows elderly people to be assisted in their [...] Read more.

In the last few years, telerehabilitation and telecare have become important topics in healthcare since they enable people to remain independent in their own homes by providing person-centered technologies to support the individual. These technologies allows elderly people to be assisted in their home, instead of traveling to a clinic, providing them wellbeing and personalized health care. The literature shows a great number of interesting proposals to address telerehabilitation and telecare scenarios, which may be mainly categorized into two broad groups, namely wearable devices and context-aware systems. However, we believe that these apparently different scenarios may be addressed by a single context-aware approach, concretely a vision-based system that can operate automatically in a non-intrusive way for the elderly, and this is the goal of this paper. We present a general approach based on 3D cameras and neural network algorithms that offers an efficient solution for two different scenarios of telerehabilitation and telecare for elderly people. Our empirical analysis reveals the effectiveness and accuracy of the algorithms presented in our approach and provides more than promising results when the neural network parameters are properly adjusted. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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16 pages, 6515 KiB

Open AccessArticle

An Effective Correction Method for Seriously Oblique Remote Sensing Images Based on Multi-View Simulation and a Piecewise Model

by Chunyuan Wang, Xiang Liu, Xiaoli Zhao and Yongqi Wang

Sensors 2016, 16(10), 1725; https://doi.org/10.3390/s16101725 - 18 Oct 2016

Cited by 4 | Viewed by 4466

Abstract

Conventional correction approaches are unsuitable for effectively correcting remote sensing images acquired in the seriously oblique condition which has severe distortions and resolution disparity. Considering that the extraction of control points (CPs) and the parameter estimation of the correction model play important roles [...] Read more.

Conventional correction approaches are unsuitable for effectively correcting remote sensing images acquired in the seriously oblique condition which has severe distortions and resolution disparity. Considering that the extraction of control points (CPs) and the parameter estimation of the correction model play important roles in correction accuracy, this paper introduces an effective correction method for large angle (LA) images. Firstly, a new CP extraction algorithm is proposed based on multi-view simulation (MVS) to ensure the effective matching of CP pairs between the reference image and the LA image. Then, a new piecewise correction algorithm is advanced with the optimized CPs, where a concept of distribution measurement (DM) is introduced to quantify the CPs distribution. The whole image is partitioned into contiguous subparts which are corrected by different correction formulae to guarantee the accuracy of each subpart. The extensive experimental results demonstrate that the proposed method significantly outperforms conventional approaches. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 299 KiB

Open AccessArticle

Transmit Power Allocation for Physical Layer Security in Cooperative Multi-Hop Full-Duplex Relay Networks

by Jong-Ho Lee, Illsoo Sohn and Yong-Hwa Kim

Sensors 2016, 16(10), 1726; https://doi.org/10.3390/s16101726 - 17 Oct 2016

Cited by 12 | Viewed by 4324

Abstract

In this paper, we consider a transmit power allocation problem for secure transmission in multi-hop decode-and-forward (DF) full-duplex relay (FDR) networks, where multiple FDRs are located at each hop and perform cooperative beamforming to null out the signal at multiple eavesdroppers. For a [...] Read more.

In this paper, we consider a transmit power allocation problem for secure transmission in multi-hop decode-and-forward (DF) full-duplex relay (FDR) networks, where multiple FDRs are located at each hop and perform cooperative beamforming to null out the signal at multiple eavesdroppers. For a perfect self-interference cancellation (PSIC) case, where the self-interference signal at each FDR is completely canceled, we derive an optimal power allocation (OPA) strategy using the Karush-Kuhn-Tucker (KKT) conditions to maximize the achievable secrecy rate under an overall transmit power constraint. In the case where residual self-interferences exist owing to imperfect self-interference cancellation (ISIC), we also propose a transmit power allocation scheme using the geometric programming (GP) method. Numerical results are presented to verify the secrecy rate performance of the proposed power allocation schemes. Full article

(This article belongs to the Section Sensor Networks)

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16 pages, 5420 KiB

Open AccessArticle

Effectiveness Testing of a Piezoelectric Energy Harvester for an Automobile Wheel Using Stochastic Resonance

by Yunshun Zhang, Rencheng Zheng, Keisuke Shimono, Tsutomu Kaizuka and Kimihiko Nakano

Sensors 2016, 16(10), 1727; https://doi.org/10.3390/s16101727 - 17 Oct 2016

Cited by 71 | Viewed by 10295

Abstract

The collection of clean power from ambient vibrations is considered a promising method for energy harvesting. For the case of wheel rotation, the present study investigates the effectiveness of a piezoelectric energy harvester, with the application of stochastic resonance to optimize the efficiency [...] Read more.

The collection of clean power from ambient vibrations is considered a promising method for energy harvesting. For the case of wheel rotation, the present study investigates the effectiveness of a piezoelectric energy harvester, with the application of stochastic resonance to optimize the efficiency of energy harvesting. It is hypothesized that when the wheel rotates at variable speeds, the energy harvester is subjected to on-road noise as ambient excitations and a tangentially acting gravity force as a periodic modulation force, which can stimulate stochastic resonance. The energy harvester was miniaturized with a bistable cantilever structure, and the on-road noise was measured for the implementation of a vibrator in an experimental setting. A validation experiment revealed that the harvesting system was optimized to capture power that was approximately 12 times that captured under only on-road noise excitation and 50 times that captured under only the periodic gravity force. Moreover, the investigation of up-sweep excitations with increasing rotational frequency confirmed that stochastic resonance is effective in optimizing the performance of the energy harvester, with a certain bandwidth of vehicle speeds. An actual-vehicle experiment validates that the prototype harvester using stochastic resonance is capable of improving power generation performance for practical tire application. Full article

(This article belongs to the Special Issue Resonator Sensors)

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9 pages, 3237 KiB

Open AccessArticle

High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities

by Xiangao Zhang, Mingzhen Shao and Xiaoqi Zeng

Sensors 2016, 16(10), 1730; https://doi.org/10.3390/s16101730 - 18 Oct 2016

Cited by 33 | Viewed by 5030

Abstract

In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance [...] Read more.

In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly. Furthermore, by modulating the geometrical parameters appropriately, Fano resonances with high sensitivities to the changes in refractive index can be realized. A maximum figure of merit (FoM) value of 74.3 is obtained. Considerable applications for this work can be found in bio/chemical sensors with excellent performance and other nanophotonic integrated circuit devices such as optical filters, switches and modulators. Full article

(This article belongs to the Special Issue Resonator Sensors)

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14 pages, 7744 KiB

Open AccessArticle

Routing Topologies of Wireless Sensor Networks for Health Monitoring of a Cultural Heritage Site

by Sofía Aparicio, María I. Martínez-Garrido, Javier Ranz, Rafael Fort and Miguel Ángel G. Izquierdo

Sensors 2016, 16(10), 1732; https://doi.org/10.3390/s16101732 - 19 Oct 2016

Cited by 10 | Viewed by 4589

Abstract

This paper provides a performance evaluation of tree and mesh routing topologies of wireless sensor networks (WSNs) in a cultural heritage site. The historical site selected was San Juan Bautista church in Talamanca de Jarama (Madrid, Spain). We report the preliminary analysis required [...] Read more.

This paper provides a performance evaluation of tree and mesh routing topologies of wireless sensor networks (WSNs) in a cultural heritage site. The historical site selected was San Juan Bautista church in Talamanca de Jarama (Madrid, Spain). We report the preliminary analysis required to study the effects of heating in this historical location using WSNs to monitor the temperature and humidity conditions during periods of weeks. To test which routing topology was better for this kind of application, the WSNs were first deployed on the upper floor of the CAEND institute in Arganda del Rey simulating the church deployment, but in the former scenario there was no direct line of sight between the WSN elements. Two parameters were selected to evaluate the performance of the routing topologies of WSNs: the percentage of received messages and the lifetime of the wireless sensor network. To analyze in more detail which topology gave the best performance, other communication parameters were also measured. The tree topology used was the collection tree protocol and the mesh topology was the XMESH provided by MEMSIC (Andover, MA, USA). For the scenarios presented in this paper, it can be concluded that the tree topology lost fewer messages than the mesh topology. Full article

(This article belongs to the Section Sensor Networks)

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7 pages, 2997 KiB

Open AccessArticle

Microwave-Based Microfluidic Sensor for Non-Destructive and Quantitative Glucose Monitoring in Aqueous Solution

by Thomas Chretiennot, David Dubuc and Katia Grenier

Sensors 2016, 16(10), 1733; https://doi.org/10.3390/s16101733 - 19 Oct 2016

Cited by 74 | Viewed by 8271

Abstract

This paper presents a reliable microwave and microfluidic miniature sensor dedicated to the measurement of glucose concentration in aqueous solution. The device; which is integrated with microtechnologies; is made of a bandstop filter implemented in a thin film microstrip technology combined with a [...] Read more.

This paper presents a reliable microwave and microfluidic miniature sensor dedicated to the measurement of glucose concentration in aqueous solution. The device; which is integrated with microtechnologies; is made of a bandstop filter implemented in a thin film microstrip technology combined with a fluidic microchannel. Glucose aqueous solutions have been characterized for concentration ranging from 80 g/L down to 0.3 g/L and are identified with the normalized insertion loss at optimal frequency. The sensitivity of the sensor has consequently been estimated at 7.6 × 10⁻³ dB/(g/L); together with the experimental uncertainty; the resolution of the sensor comes to 0.4 g/L. These results demonstrate the potentialities of such a sensor for the quantitative analysis of glucose in aqueous solution. Full article

(This article belongs to the Special Issue Advanced Technologies and Techniques for Microwave and Wireless Sensors)

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13 pages, 3137 KiB

Open AccessArticle

CCD-Based Skinning Injury Recognition on Potato Tubers (Solanum tuberosum L.): A Comparison between Visible and Biospeckle Imaging

by Yingwang Gao, Jinfeng Geng, Xiuqin Rao and Yibin Ying

Sensors 2016, 16(10), 1734; https://doi.org/10.3390/s16101734 - 18 Oct 2016

Cited by 13 | Viewed by 5418

Abstract

Skinning injury on potato tubers is a kind of superficial wound that is generally inflicted by mechanical forces during harvest and postharvest handling operations. Though skinning injury is pervasive and obstructive, its detection is very limited. This study attempted to identify injured skin [...] Read more.

Skinning injury on potato tubers is a kind of superficial wound that is generally inflicted by mechanical forces during harvest and postharvest handling operations. Though skinning injury is pervasive and obstructive, its detection is very limited. This study attempted to identify injured skin using two CCD (Charge Coupled Device) sensor-based machine vision technologies, i.e., visible imaging and biospeckle imaging. The identification of skinning injury was realized via exploiting features extracted from varied ROIs (Region of Interests). The features extracted from visible images were pixel-wise color and texture features, while region-wise BA (Biospeckle Activity) was calculated from biospeckle imaging. In addition, the calculation of BA using varied numbers of speckle patterns were compared. Finally, extracted features were implemented into classifiers of LS-SVM (Least Square Support Vector Machine) and BLR (Binary Logistic Regression), respectively. Results showed that color features performed better than texture features in classifying sound skin and injured skin, especially for injured skin stored no less than 1 day, with the average classification accuracy of 90%. Image capturing and processing efficiency can be speeded up in biospeckle imaging, with captured 512 frames reduced to 125 frames. Classification results obtained based on the feature of BA were acceptable for early skinning injury stored within 1 day, with the accuracy of 88.10%. It is concluded that skinning injury can be recognized by visible and biospeckle imaging during different stages. Visible imaging has the aptitude in recognizing stale skinning injury, while fresh injury can be discriminated by biospeckle imaging. Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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14 pages, 2676 KiB

Open AccessArticle

Predicting Gilthead Sea Bream (Sparus aurata) Freshness by a Novel Combined Technique of 3D Imaging and SW-NIR Spectral Analysis

by Eugenio Ivorra, Samuel Verdu, Antonio J. Sánchez, Raúl Grau and José M. Barat

Sensors 2016, 16(10), 1735; https://doi.org/10.3390/s16101735 - 19 Oct 2016

Cited by 12 | Viewed by 6162

Abstract

A technique that combines the spatial resolution of a 3D structured-light (SL) imaging system with the spectral analysis of a hyperspectral short-wave near infrared system was developed for freshness predictions of gilthead sea bream on the first storage days (Days 0–6). This novel [...] Read more.

A technique that combines the spatial resolution of a 3D structured-light (SL) imaging system with the spectral analysis of a hyperspectral short-wave near infrared system was developed for freshness predictions of gilthead sea bream on the first storage days (Days 0–6). This novel approach allows the hyperspectral analysis of very specific fish areas, which provides more information for freshness estimations. The SL system obtains a 3D reconstruction of fish, and an automatic method locates gilthead’s pupils and irises. Once these regions are positioned, the hyperspectral camera acquires spectral information and a multivariate statistical study is done. The best region is the pupil with an R² of 0.92 and an RMSE of 0.651 for predictions. We conclude that the combination of 3D technology with the hyperspectral analysis offers plenty of potential and is a very promising technique to non destructively predict gilthead freshness. Full article

(This article belongs to the Special Issue Sensors for Biomedical, Environmental and Food Monitoring Applications)

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14 pages, 8599 KiB

Open AccessArticle

Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide

by Feiran Sun, Zhenguo Sun, Qiang Chen, Riichi Murayama and Hideo Nishino

Sensors 2016, 16(10), 1737; https://doi.org/10.3390/s16101737 - 19 Oct 2016

Cited by 11 | Viewed by 8382

Abstract

To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The [...] Read more.

To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1) mode, L(0,1) mode, and L(0,2) mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1) mode, while the SH0-wave is easier to convert to the L(0,1) mode and L(0,2) mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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18 pages, 6811 KiB

Open AccessArticle

A 3D CFD Simulation and Analysis of Flow-Induced Forces on Polymer Piezoelectric Sensors in a Chinese Liquors Identification E-Nose

by Yu Gu, Yang-Fu Wang, Qiang Li and Zu-Wu Liu

Sensors 2016, 16(10), 1738; https://doi.org/10.3390/s16101738 - 20 Oct 2016

Cited by 12 | Viewed by 6370

Abstract

Chinese liquors can be classified according to their flavor types. Accurate identification of Chinese liquor flavors is not always possible through professional sommeliers’ subjective assessment. A novel polymer piezoelectric sensor electric nose (e-nose) can be applied to distinguish Chinese liquors because of its [...] Read more.

Chinese liquors can be classified according to their flavor types. Accurate identification of Chinese liquor flavors is not always possible through professional sommeliers’ subjective assessment. A novel polymer piezoelectric sensor electric nose (e-nose) can be applied to distinguish Chinese liquors because of its excellent ability in imitating human senses by using sensor arrays and pattern recognition systems. The sensor, based on the quartz crystal microbalance (QCM) principle is comprised of a quartz piezoelectric crystal plate sandwiched between two specific gas-sensitive polymer coatings. Chinese liquors are identified by obtaining the resonance frequency value changes of each sensor using the e-nose. However, the QCM principle failed to completely account for a particular phenomenon: we found that the resonance frequency values fluctuated in the stable state. For better understanding the phenomenon, a 3D Computational Fluid Dynamics (CFD) simulation using the finite volume method is employed to study the influence of the flow-induced forces to the resonance frequency fluctuation of each sensor in the sensor box. A dedicated procedure was developed for modeling the flow of volatile gas from Chinese liquors in a realistic scenario to give reasonably good results with fair accuracy. The flow-induced forces on the sensors are displayed from the perspective of their spatial-temporal and probability density distributions. To evaluate the influence of the fluctuation of the flow-induced forces on each sensor and ensure the serviceability of the e-nose, the standard deviation of resonance frequency value (SD_F) and the standard deviation of resultant forces (SD_Fy) in y-direction (F_y) are compared. Results show that the fluctuations of F_y are bound up with the resonance frequency values fluctuations. To ensure that the sensor's resonance frequency values are steady and only fluctuate slightly, in order to improve the identification accuracy of Chinese liquors using the e-nose, the sensors in the sensor box should be in the proper place, i.e., where the fluctuations of the flow-induced forces is relatively small. This plays a significant reference role in determining the optimum design of the e-nose for accurately identifying Chinese liquors. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4190 KiB

Open AccessArticle

Preliminary Study on Continuous Recognition of Elbow Flexion/Extension Using sEMG Signals for Bilateral Rehabilitation

by Zhibin Song and Songyuan Zhang

Sensors 2016, 16(10), 1739; https://doi.org/10.3390/s16101739 - 19 Oct 2016

Cited by 6 | Viewed by 5350

Abstract

Surface electromyography (sEMG) signals are closely related to the activation of human muscles and the motion of the human body, which can be used to estimate the dynamics of human limbs in the rehabilitation field. They also have the potential to be used [...] Read more.

Surface electromyography (sEMG) signals are closely related to the activation of human muscles and the motion of the human body, which can be used to estimate the dynamics of human limbs in the rehabilitation field. They also have the potential to be used in the application of bilateral rehabilitation, where hemiplegic patients can train their affected limbs following the motion of unaffected limbs via some rehabilitation devices. Traditional methods to process the sEMG focused on motion pattern recognition, namely, discrete patterns, which are not satisfactory for use in bilateral rehabilitation. In order to overcome this problem, in this paper, we built a relationship between sEMG signals and human motion in elbow flexion and extension on the sagittal plane. During the conducted experiments, four participants were required to perform elbow flexion and extension on the sagittal plane smoothly with only an inertia sensor in their hands, where forearm dynamics were not considered. In these circumstances, sEMG signals were weak compared to those with heavy loads or high acceleration. The contrastive experimental results show that continuous motion can also be obtained within an acceptable precision range. Full article

(This article belongs to the Special Issue Wearable Biomedical Sensors)

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24 pages, 15699 KiB

Open AccessArticle

Robust Depth Image Acquisition Using Modulated Pattern Projection and Probabilistic Graphical Models

by Jaka Kravanja, Mario Žganec, Jerneja Žganec-Gros, Simon Dobrišek and Vitomir Štruc

Sensors 2016, 16(10), 1740; https://doi.org/10.3390/s16101740 - 19 Oct 2016

Cited by 1 | Viewed by 5599

Abstract

Depth image acquisition with structured light approaches in outdoor environments is a challenging problem due to external factors, such as ambient sunlight, which commonly affect the acquisition procedure. This paper presents a novel structured light sensor designed specifically for operation in outdoor environments. [...] Read more.

Depth image acquisition with structured light approaches in outdoor environments is a challenging problem due to external factors, such as ambient sunlight, which commonly affect the acquisition procedure. This paper presents a novel structured light sensor designed specifically for operation in outdoor environments. The sensor exploits a modulated sequence of structured light projected onto the target scene to counteract environmental factors and estimate a spatial distortion map in a robust manner. The correspondence between the projected pattern and the estimated distortion map is then established using a probabilistic framework based on graphical models. Finally, the depth image of the target scene is reconstructed using a number of reference frames recorded during the calibration process. We evaluate the proposed sensor on experimental data in indoor and outdoor environments and present comparative experiments with other existing methods, as well as commercial sensors. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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16 pages, 1508 KiB

Open AccessArticle

Iterative Diffusion-Based Distributed Cubature Gaussian Mixture Filter for Multisensor Estimation

by Bin Jia, Tao Sun and Ming Xin

Sensors 2016, 16(10), 1741; https://doi.org/10.3390/s16101741 - 20 Oct 2016

Cited by 5 | Viewed by 4796

Abstract

In this paper, a distributed cubature Gaussian mixture filter (DCGMF) based on an iterative diffusion strategy (DCGMF-ID) is proposed for multisensor estimation and information fusion. The uncertainties are represented as Gaussian mixtures at each sensor node. A high-degree cubature Kalman filter provides accurate [...] Read more.

In this paper, a distributed cubature Gaussian mixture filter (DCGMF) based on an iterative diffusion strategy (DCGMF-ID) is proposed for multisensor estimation and information fusion. The uncertainties are represented as Gaussian mixtures at each sensor node. A high-degree cubature Kalman filter provides accurate estimation of each Gaussian mixture component. An iterative diffusion scheme is utilized to fuse the mean and covariance of each Gaussian component obtained from each sensor node. The DCGMF-ID extends the conventional diffusion-based fusion strategy by using multiple iterative information exchanges among neighboring sensor nodes. The convergence property of the iterative diffusion is analyzed. In addition, it is shown that the convergence of the iterative diffusion can be interpreted from the information-theoretic perspective as minimization of the Kullback–Leibler divergence. The performance of the DCGMF-ID is compared with the DCGMF based on the average consensus (DCGMF-AC) and the DCGMF based on the iterative covariance intersection (DCGMF-ICI) via a maneuvering target-tracking problem using multiple sensors. The simulation results show that the DCGMF-ID has better performance than the DCGMF based on noniterative diffusion, which validates the benefit of iterative information exchanges. In addition, the DCGMF-ID outperforms the DCGMF-ICI and DCGMF-AC when the number of iterations is limited. Full article

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

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20 pages, 4921 KiB

Open AccessArticle

Chemically Roughened Solid Silver: A Simple, Robust and Broadband SERS Substrate

by Shavini Wijesuriya, Krishna Burugapalli, Ruth Mackay, Godwin Chukwuebuka Ajaezi and Wamadeva Balachandran

Sensors 2016, 16(10), 1742; https://doi.org/10.3390/s16101742 - 19 Oct 2016

Cited by 22 | Viewed by 8532

Abstract

Surface-enhanced Raman spectroscopy (SERS) substrates manufactured using complex nano-patterning techniques have become the norm. However, their cost of manufacture makes them unaffordable to incorporate into most biosensors. The technique shown in this paper is low-cost, reliable and highly sensitive. Chemical etching of solid [...] Read more.

Surface-enhanced Raman spectroscopy (SERS) substrates manufactured using complex nano-patterning techniques have become the norm. However, their cost of manufacture makes them unaffordable to incorporate into most biosensors. The technique shown in this paper is low-cost, reliable and highly sensitive. Chemical etching of solid Ag metal was used to produce simple, yet robust SERS substrates with broadband characteristics. Etching with ammonium hydroxide (NH₄OH) and nitric acid (HNO₃) helped obtain roughened Ag SERS substrates. Scanning electron microscopy (SEM) and interferometry were used to visualize and quantify surface roughness. Flattened Ag wires had inherent, but non-uniform roughness having peaks and valleys in the microscale. NH₄OH treatment removed dirt and smoothened the surface, while HNO₃ treatment produced a flake-like morphology with visibly more surface roughness features on Ag metal. SERS efficacy was tested using 4-methylbenzenethiol (MBT). The best SERS enhancement for 1 mM MBT was observed for Ag metal etched for 30 s in NH₄OH followed by 10 s in HNO₃. Further, MBT could be quantified with detection limits of 1 pM and 100 µM, respectively, using 514 nm and 1064 nm Raman spectrometers. Thus, a rapid and less energy intensive method for producing solid Ag SERS substrate and its efficacy in analyte sensing was demonstrated. Full article

(This article belongs to the Special Issue Applications of Raman Spectroscopy in Biosensors)

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15 pages, 5100 KiB

Open AccessArticle

Development and Application of a Wireless Sensor for Space Charge Density Measurement in an Ultra-High-Voltage, Direct-Current Environment

by Encheng Xin, Yong Ju and Haiwen Yuan

Sensors 2016, 16(10), 1743; https://doi.org/10.3390/s16101743 - 20 Oct 2016

Cited by 3 | Viewed by 5260

Abstract

A space charge density wireless measurement system based on the idea of distributed measurement is proposed for collecting and monitoring the space charge density in an ultra-high-voltage direct-current (UHVDC) environment. The proposed system architecture is composed of a number of wireless nodes connected [...] Read more.

A space charge density wireless measurement system based on the idea of distributed measurement is proposed for collecting and monitoring the space charge density in an ultra-high-voltage direct-current (UHVDC) environment. The proposed system architecture is composed of a number of wireless nodes connected with space charge density sensors and a base station. The space charge density sensor based on atmospheric ion counter method is elaborated and developed, and the ARM microprocessor and Zigbee radio frequency module are applied. The wireless network communication quality and the relationship between energy consumption and transmission distance in the complicated electromagnetic environment is tested. Based on the experimental results, the proposed measurement system demonstrates that it can adapt to the complex electromagnetic environment under the UHVDC transmission lines and can accurately measure the space charge density. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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16 pages, 2333 KiB

Open AccessArticle

Arrhythmia Classification Based on Multi-Domain Feature Extraction for an ECG Recognition System

by Hongqiang Li, Danyang Yuan, Youxi Wang, Dianyin Cui and Lu Cao

Sensors 2016, 16(10), 1744; https://doi.org/10.3390/s16101744 - 20 Oct 2016

Cited by 95 | Viewed by 11116

Abstract

Automatic recognition of arrhythmias is particularly important in the diagnosis of heart diseases. This study presents an electrocardiogram (ECG) recognition system based on multi-domain feature extraction to classify ECG beats. An improved wavelet threshold method for ECG signal pre-processing is applied to remove [...] Read more.

Automatic recognition of arrhythmias is particularly important in the diagnosis of heart diseases. This study presents an electrocardiogram (ECG) recognition system based on multi-domain feature extraction to classify ECG beats. An improved wavelet threshold method for ECG signal pre-processing is applied to remove noise interference. A novel multi-domain feature extraction method is proposed; this method employs kernel-independent component analysis in nonlinear feature extraction and uses discrete wavelet transform to extract frequency domain features. The proposed system utilises a support vector machine classifier optimized with a genetic algorithm to recognize different types of heartbeats. An ECG acquisition experimental platform, in which ECG beats are collected as ECG data for classification, is constructed to demonstrate the effectiveness of the system in ECG beat classification. The presented system, when applied to the MIT-BIH arrhythmia database, achieves a high classification accuracy of 98.8%. Experimental results based on the ECG acquisition experimental platform show that the system obtains a satisfactory classification accuracy of 97.3% and is able to classify ECG beats efficiently for the automatic identification of cardiac arrhythmias. Full article

(This article belongs to the Special Issue Wearable Biomedical Sensors)

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12 pages, 1945 KiB

Open AccessArticle

Chocolate Classification by an Electronic Nose with Pressure Controlled Generated Stimulation

by Luis F. Valdez and Juan Manuel Gutiérrez

Sensors 2016, 16(10), 1745; https://doi.org/10.3390/s16101745 - 20 Oct 2016

Cited by 23 | Viewed by 5953

Abstract

In this work, we will analyze the response of a Metal Oxide Gas Sensor (MOGS) array to a flow controlled stimulus generated in a pressure controlled canister produced by a homemade olfactometer to build an E-nose. The built E-nose is capable of chocolate [...] Read more.

In this work, we will analyze the response of a Metal Oxide Gas Sensor (MOGS) array to a flow controlled stimulus generated in a pressure controlled canister produced by a homemade olfactometer to build an E-nose. The built E-nose is capable of chocolate identification between the 26 analyzed chocolate bar samples and four features recognition (chocolate type, extra ingredient, sweetener and expiration date status). The data analysis tools used were Principal Components Analysis (PCA) and Artificial Neural Networks (ANNs). The chocolate identification E-nose average classification rate was of 81.3% with 0.99 accuracy (Acc), 0.86 precision (Prc), 0.84 sensitivity (Sen) and 0.99 specificity (Spe) for test. The chocolate feature recognition E-nose gives a classification rate of 85.36% with 0.96 Acc, 0.86 Prc, 0.85 Sen and 0.96 Spe. In addition, a preliminary sample aging analysis was made. The results prove the pressure controlled generated stimulus is reliable for this type of studies. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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23 pages, 3865 KiB

Open AccessArticle

A Novel Model-Based Driving Behavior Recognition System Using Motion Sensors

by Minglin Wu, Sheng Zhang and Yuhan Dong

Sensors 2016, 16(10), 1746; https://doi.org/10.3390/s16101746 - 20 Oct 2016

Cited by 60 | Viewed by 7311

Abstract

In this article, a novel driving behavior recognition system based on a specific physical model and motion sensory data is developed to promote traffic safety. Based on the theory of rigid body kinematics, we build a specific physical model to reveal the data [...] Read more.

In this article, a novel driving behavior recognition system based on a specific physical model and motion sensory data is developed to promote traffic safety. Based on the theory of rigid body kinematics, we build a specific physical model to reveal the data change rule during the vehicle moving process. In this work, we adopt a nine-axis motion sensor including a three-axis accelerometer, a three-axis gyroscope and a three-axis magnetometer, and apply a Kalman filter for noise elimination and an adaptive time window for data extraction. Based on the feature extraction guided by the built physical model, various classifiers are accomplished to recognize different driving behaviors. Leveraging the system, normal driving behaviors (such as accelerating, braking, lane changing and turning with caution) and aggressive driving behaviors (such as accelerating, braking, lane changing and turning with a sudden) can be classified with a high accuracy of 93.25%. Compared with traditional driving behavior recognition methods using machine learning only, the proposed system possesses a solid theoretical basis, performs better and has good prospects. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 3291 KiB

Open AccessArticle

Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension

by Boqian Sun, Shunyue Wang, Haixia Li and Xiaoxia He

Sensors 2016, 16(10), 1747; https://doi.org/10.3390/s16101747 - 20 Oct 2016

Cited by 11 | Viewed by 6789

Abstract

A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor [...] Read more.

A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor being controlled by a torque-rebalance loop. In this paper, a decoupling compensation method is proposed and investigated experimentally based on an electrostatically suspended micromachined gyroscope. In order to eliminate the negative spring effect inherent in the gyroscope dynamics, a stiffness compensation scheme was utilized in design of the decoupled rebalance loop to ensure loop stability and increase suspension stiffness. The experimental results show an overall stiffness increase of 30.3% after compensation. A decoupling method comprised of inner- and outer-loop decoupling compensators is proposed to minimize the cross-axis coupling error. The inner-loop decoupling compensator aims to attenuate the angular position coupling. The experimental frequency response shows a position coupling attenuation by 14.36 dB at 1 Hz. Moreover, the cross-axis coupling between the two angular rate output signals can be attenuated theoretically from −56.2 dB down to −102 dB by further appending the outer-loop decoupling compensator. The proposed dual-loop decoupling compensation algorithm could be applied to other dual-axis spinning-rotor gyroscopes with various suspension solutions. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 7734 KiB

Open AccessArticle

A Readout IC Using Two-Step Fastest Signal Identification for Compact Data Acquisition of PET Systems

by Sung-Jin Jung, Seong-Kwan Hong and Oh-Kyong Kwon

Sensors 2016, 16(10), 1748; https://doi.org/10.3390/s16101748 - 20 Oct 2016

Cited by 5 | Viewed by 6980

Abstract

A readout integrated circuit (ROIC) using two-step fastest signal identification (FSI) is proposed to reduce the number of input channels of a data acquisition (DAQ) block with a high-channel reduction ratio. The two-step FSI enables the proposed ROIC to filter out useless input [...] Read more.

A readout integrated circuit (ROIC) using two-step fastest signal identification (FSI) is proposed to reduce the number of input channels of a data acquisition (DAQ) block with a high-channel reduction ratio. The two-step FSI enables the proposed ROIC to filter out useless input signals that arise from scattering and electrical noise without using complex and bulky circuits. In addition, an asynchronous fastest signal identifier and a self-trimmed comparator are proposed to identify the fastest signal without using a high-frequency clock and to reduce misidentification, respectively. The channel reduction ratio of the proposed ROIC is 16:1 and can be extended to 16 × N:1 using N ROICs. To verify the performance of the two-step FSI, the proposed ROIC was implemented into a gamma photon detector module using a Geiger-mode avalanche photodiode with a lutetium-yttrium oxyorthosilicate array. The measured minimum detectable time is 1 ns. The difference of the measured energy and timing resolution between with and without the two-step FSI are 0.8% and 0.2 ns, respectively, which are negligibly small. These measurement results show that the proposed ROIC using the two-step FSI reduces the number of input channels of the DAQ block without sacrificing the performance of the positron emission tomography (PET) systems. Full article

(This article belongs to the Special Issue Smart Sensor Interface Circuits and Systems)

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9 pages, 1356 KiB

Open AccessArticle

Developing Benthic Class Specific, Chlorophyll-a Retrieving Algorithms for Optically-Shallow Water Using SeaWiFS

by Tara Blakey, Assefa Melesse, Michael C. Sukop, Georgio Tachiev, Dean Whitman and Fernando Miralles-Wilhelm

Sensors 2016, 16(10), 1749; https://doi.org/10.3390/s16101749 - 20 Oct 2016

Cited by 7 | Viewed by 4793

Abstract

This study evaluated the ability to improve Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) chl-a retrieval from optically shallow coastal waters by applying algorithms specific to the pixels’ benthic class. The form of the Ocean Color (OC) algorithm was assumed for this study. The operational [...] Read more.

This study evaluated the ability to improve Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) chl-a retrieval from optically shallow coastal waters by applying algorithms specific to the pixels’ benthic class. The form of the Ocean Color (OC) algorithm was assumed for this study. The operational atmospheric correction producing Level 2 SeaWiFS data was retained since the focus of this study was on establishing the benefit from the alternative specification of the bio-optical algorithm. Benthic class was determined through satellite image-based classification methods. Accuracy of the chl-a algorithms evaluated was determined through comparison with coincident in situ measurements of chl-a. The regionally-tuned models that were allowed to vary by benthic class produced more accurate estimates of chl-a than the single, unified regionally-tuned model. Mean absolute percent difference was approximately 70% for the regionally-tuned, benthic class-specific algorithms. Evaluation of the residuals indicated the potential for further improvement to chl-a estimation through finer characterization of benthic environments. Atmospheric correction procedures specialized to coastal environments were recognized as areas for future improvement as these procedures would improve both classification and algorithm tuning. Full article

(This article belongs to the Special Issue Sensors and Sensing in Water Quality Assessment and Monitoring)

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20 pages, 7213 KiB

Open AccessArticle

A Low-Cost Optical Remote Sensing Application for Glacier Deformation Monitoring in an Alpine Environment

by Daniele Giordan, Paolo Allasia, Niccolò Dematteis, Federico Dell’Anese, Marco Vagliasindi and Elena Motta

Sensors 2016, 16(10), 1750; https://doi.org/10.3390/s16101750 - 21 Oct 2016

Cited by 27 | Viewed by 7192

Abstract

In this work, we present the results of a low-cost optical monitoring station designed for monitoring the kinematics of glaciers in an Alpine environment. We developed a complete hardware/software data acquisition and processing chain that automatically acquires, stores and co-registers images. The system [...] Read more.

In this work, we present the results of a low-cost optical monitoring station designed for monitoring the kinematics of glaciers in an Alpine environment. We developed a complete hardware/software data acquisition and processing chain that automatically acquires, stores and co-registers images. The system was installed in September 2013 to monitor the evolution of the Planpincieux glacier, within the open-air laboratory of the Grandes Jorasses, Mont Blanc massif (NW Italy), and collected data with an hourly frequency. The acquisition equipment consists of a high-resolution DSLR camera operating in the visible band. The data are processed with a Pixel Offset algorithm based on normalized cross-correlation, to estimate the deformation of the observed glacier. We propose a method for the pixel-to-metric conversion and present the results of the projection on the mean slope of the glacier. The method performances are compared with measurements obtained by GB-SAR, and exhibit good agreement. The system provides good support for the analysis of the glacier evolution and allows the creation of daily displacement maps. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 3888 KiB

Open AccessArticle

A Self-Synthesis Approach to Perceptual Learning for Multisensory Fusion in Robotics

by Cristian Axenie, Christoph Richter and Jörg Conradt

Sensors 2016, 16(10), 1751; https://doi.org/10.3390/s16101751 - 20 Oct 2016

Cited by 11 | Viewed by 7087

Abstract

Biological and technical systems operate in a rich multimodal environment. Due to the diversity of incoming sensory streams a system perceives and the variety of motor capabilities a system exhibits there is no single representation and no singular unambiguous interpretation of such a [...] Read more.

Biological and technical systems operate in a rich multimodal environment. Due to the diversity of incoming sensory streams a system perceives and the variety of motor capabilities a system exhibits there is no single representation and no singular unambiguous interpretation of such a complex scene. In this work we propose a novel sensory processing architecture, inspired by the distributed macro-architecture of the mammalian cortex. The underlying computation is performed by a network of computational maps, each representing a different sensory quantity. All the different sensory streams enter the system through multiple parallel channels. The system autonomously associates and combines them into a coherent representation, given incoming observations. These processes are adaptive and involve learning. The proposed framework introduces mechanisms for self-creation and learning of the functional relations between the computational maps, encoding sensorimotor streams, directly from the data. Its intrinsic scalability, parallelisation, and automatic adaptation to unforeseen sensory perturbations make our approach a promising candidate for robust multisensory fusion in robotic systems. We demonstrate this by applying our model to a 3D motion estimation on a quadrotor. Full article

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

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24 pages, 8806 KiB

Open AccessArticle

Design and Implementation of Foot-Mounted Inertial Sensor Based Wearable Electronic Device for Game Play Application

by Qifan Zhou, Hai Zhang, Zahra Lari, Zhenbo Liu and Naser El-Sheimy

Sensors 2016, 16(10), 1752; https://doi.org/10.3390/s16101752 - 21 Oct 2016

Cited by 19 | Viewed by 7805

Abstract

Wearable electronic devices have experienced increasing development with the advances in the semiconductor industry and have received more attention during the last decades. This paper presents the development and implementation of a novel inertial sensor-based foot-mounted wearable electronic device for a brand new [...] Read more.

Wearable electronic devices have experienced increasing development with the advances in the semiconductor industry and have received more attention during the last decades. This paper presents the development and implementation of a novel inertial sensor-based foot-mounted wearable electronic device for a brand new application: game playing. The main objective of the introduced system is to monitor and identify the human foot stepping direction in real time, and coordinate these motions to control the player operation in games. This proposed system extends the utilized field of currently available wearable devices and introduces a convenient and portable medium to perform exercise in a more compelling way in the near future. This paper provides an overview of the previously-developed system platforms, introduces the main idea behind this novel application, and describes the implemented human foot moving direction identification algorithm. Practical experiment results demonstrate that the proposed system is capable of recognizing five foot motions, jump, step left, step right, step forward, and step backward, and has achieved an over 97% accuracy performance for different users. The functionality of the system for real-time application has also been verified through the practical experiments. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2239 KiB

Open AccessArticle

Underwater Sensor Network Redeployment Algorithm Based on Wolf Search

by Peng Jiang, Yang Feng and Feng Wu

Sensors 2016, 16(10), 1754; https://doi.org/10.3390/s16101754 - 21 Oct 2016

Cited by 19 | Viewed by 5581

Abstract

This study addresses the optimization of node redeployment coverage in underwater wireless sensor networks. Given that nodes could easily become invalid under a poor environment and the large scale of underwater wireless sensor networks, an underwater sensor network redeployment algorithm was developed based [...] Read more.

This study addresses the optimization of node redeployment coverage in underwater wireless sensor networks. Given that nodes could easily become invalid under a poor environment and the large scale of underwater wireless sensor networks, an underwater sensor network redeployment algorithm was developed based on wolf search. This study is to apply the wolf search algorithm combined with crowded degree control in the deployment of underwater wireless sensor networks. The proposed algorithm uses nodes to ensure coverage of the events, and it avoids the prematurity of the nodes. The algorithm has good coverage effects. In addition, considering that obstacles exist in the underwater environment, nodes are prevented from being invalid by imitating the mechanism of avoiding predators. Thus, the energy consumption of the network is reduced. Comparative analysis shows that the algorithm is simple and effective in wireless sensor network deployment. Compared with the optimized artificial fish swarm algorithm, the proposed algorithm exhibits advantages in network coverage, energy conservation, and obstacle avoidance. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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27 pages, 18231 KiB

Open AccessArticle

Fine-Scale Population Estimation by 3D Reconstruction of Urban Residential Buildings

by Shixin Wang, Ye Tian, Yi Zhou, Wenliang Liu and Chenxi Lin

Sensors 2016, 16(10), 1755; https://doi.org/10.3390/s16101755 - 21 Oct 2016

Cited by 33 | Viewed by 6922

Abstract

Fine-scale population estimation is essential in emergency response and epidemiological applications as well as urban planning and management. However, representing populations in heterogeneous urban regions with a finer resolution is a challenge. This study aims to obtain fine-scale population distribution based on 3D [...] Read more.

Fine-scale population estimation is essential in emergency response and epidemiological applications as well as urban planning and management. However, representing populations in heterogeneous urban regions with a finer resolution is a challenge. This study aims to obtain fine-scale population distribution based on 3D reconstruction of urban residential buildings with morphological operations using optical high-resolution (HR) images from the Chinese No. 3 Resources Satellite (ZY-3). Specifically, the research area was first divided into three categories when dasymetric mapping was taken into consideration. The results demonstrate that the morphological building index (MBI) yielded better results than built-up presence index (PanTex) in building detection, and the morphological shadow index (MSI) outperformed color invariant indices (CIIT) in shadow extraction and height retrieval. Building extraction and height retrieval were then combined to reconstruct 3D models and to estimate population. Final results show that this approach is effective in fine-scale population estimation, with a mean relative error of 16.46% and an overall Relative Total Absolute Error (RATE) of 0.158. This study gives significant insights into fine-scale population estimation in complicated urban landscapes, when detailed 3D information of buildings is unavailable. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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17 pages, 8776 KiB

Open AccessArticle

A Novel Gradient Vector Flow Snake Model Based on Convex Function for Infrared Image Segmentation

by Rui Zhang, Shiping Zhu and Qin Zhou

Sensors 2016, 16(10), 1756; https://doi.org/10.3390/s16101756 - 21 Oct 2016

Cited by 22 | Viewed by 7594

Abstract

Infrared image segmentation is a challenging topic because infrared images are characterized by high noise, low contrast, and weak edges. Active contour models, especially gradient vector flow, have several advantages in terms of infrared image segmentation. However, the GVF (Gradient Vector Flow) model [...] Read more.

Infrared image segmentation is a challenging topic because infrared images are characterized by high noise, low contrast, and weak edges. Active contour models, especially gradient vector flow, have several advantages in terms of infrared image segmentation. However, the GVF (Gradient Vector Flow) model also has some drawbacks including a dilemma between noise smoothing and weak edge protection, which decrease the effect of infrared image segmentation significantly. In order to solve this problem, we propose a novel generalized gradient vector flow snakes model combining GGVF (Generic Gradient Vector Flow) and NBGVF (Normally Biased Gradient Vector Flow) models. We also adopt a new type of coefficients setting in the form of convex function to improve the ability of protecting weak edges while smoothing noises. Experimental results and comparisons against other methods indicate that our proposed snakes model owns better ability in terms of infrared image segmentation than other snakes models. Full article

(This article belongs to the Special Issue Infrared and THz Sensing and Imaging)

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13 pages, 1044 KiB

Open AccessCommunication

First Results of a Detection Sensor for the Monitoring of Laying Hens Reared in a Commercial Organic Egg Production Farm Based on the Use of Infrared Technology

by Mauro Zaninelli, Veronica Redaelli, Erica Tirloni, Cristian Bernardi, Vittorio Dell’Orto and Giovanni Savoini

Sensors 2016, 16(10), 1757; https://doi.org/10.3390/s16101757 - 21 Oct 2016

Cited by 20 | Viewed by 5532

Abstract

The development of a monitoring system to identify the presence of laying hens, in a closed room of a free-range commercial organic egg production farm, was the aim of this study. This monitoring system was based on the infrared (IR) technology and had, [...] Read more.

The development of a monitoring system to identify the presence of laying hens, in a closed room of a free-range commercial organic egg production farm, was the aim of this study. This monitoring system was based on the infrared (IR) technology and had, as final target, a possible reduction of atmospheric ammonia levels and bacterial load. Tests were carried out for three weeks and involved 7 ISA (Institut de Sélection Animale) brown laying hens. The first 5 days was used to set up the detection sensor, while the other 15 days were used to evaluate the accuracy of the resulting monitoring system, in terms of sensitivity and specificity. The setup procedure included the evaluation of different color background (CB) thresholds, used to discriminate the information contents of the thermographic images. At the end of this procedure, a CB threshold equal to an increase of 3 °C from the floor temperature was chosen, and a cutoff level of 196 colored pixels was identified as the threshold to use to classify a positive case. The results of field tests showed that the developed monitoring system reached a fine detection accuracy (sensitivity = 97.9% and specificity = 94.9%) and the IR technology proved to be a possible solution for the development of a detection sensor necessary to reach the scope of this study. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 3299 KiB

Open AccessArticle

Moving Object Detection Using Scanning Camera on a High-Precision Intelligent Holder

by Shuoyang Chen, Tingfa Xu, Daqun Li, Jizhou Zhang and Shenwang Jiang

Sensors 2016, 16(10), 1758; https://doi.org/10.3390/s16101758 - 21 Oct 2016

Cited by 13 | Viewed by 11528

Abstract

During the process of moving object detection in an intelligent visual surveillance system, a scenario with complex background is sure to appear. The traditional methods, such as “frame difference” and “optical flow”, may not able to deal with the problem very well. In [...] Read more.

During the process of moving object detection in an intelligent visual surveillance system, a scenario with complex background is sure to appear. The traditional methods, such as “frame difference” and “optical flow”, may not able to deal with the problem very well. In such scenarios, we use a modified algorithm to do the background modeling work. In this paper, we use edge detection to get an edge difference image just to enhance the ability of resistance illumination variation. Then we use a “multi-block temporal-analyzing LBP (Local Binary Pattern)” algorithm to do the segmentation. In the end, a connected component is used to locate the object. We also produce a hardware platform, the core of which consists of the DSP (Digital Signal Processor) and FPGA (Field Programmable Gate Array) platforms and the high-precision intelligent holder. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 5262 KiB

Open AccessArticle

A Fiber Bragg Grating-Based Monitoring System for Roof Safety Control in Underground Coal Mining

by Yiming Zhao, Nong Zhang and Guangyao Si

Sensors 2016, 16(10), 1759; https://doi.org/10.3390/s16101759 - 21 Oct 2016

Cited by 64 | Viewed by 7758

Abstract

Monitoring of roof activity is a primary measure adopted in the prevention of roof collapse accidents and functions to optimize and support the design of roadways in underground coalmines. However, traditional monitoring measures, such as using mechanical extensometers or electronic gauges, either require [...] Read more.

Monitoring of roof activity is a primary measure adopted in the prevention of roof collapse accidents and functions to optimize and support the design of roadways in underground coalmines. However, traditional monitoring measures, such as using mechanical extensometers or electronic gauges, either require arduous underground labor or cannot function properly in the harsh underground environment. Therefore, in this paper, in order to break through this technological barrier, a novel monitoring system for roof safety control in underground coal mining, using fiber Bragg grating (FBG) material as a perceived element and transmission medium, has been developed. Compared with traditional monitoring equipment, the developed, novel monitoring system has the advantages of providing accurate, reliable, and continuous online monitoring of roof activities in underground coal mining. This is expected to further enable the prevention of catastrophic roof collapse accidents. The system has been successfully implemented at a deep hazardous roadway in Zhuji Coal Mine, China. Monitoring results from the study site have demonstrated the advantages of FBG-based sensors over traditional monitoring approaches. The dynamic impacts of progressive face advance on roof displacement and stress have been accurately captured by the novel roadway roof activity and safety monitoring system, which provided essential references for roadway support and design of the mine. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 8538 KiB

Open AccessArticle

A Comparative Study of the Application of Fluorescence Excitation-Emission Matrices Combined with Parallel Factor Analysis and Nonnegative Matrix Factorization in the Analysis of Zn Complexation by Humic Acids

by Patrycja Boguta, Piotr M. Pieczywek and Zofia Sokołowska

Sensors 2016, 16(10), 1760; https://doi.org/10.3390/s16101760 - 22 Oct 2016

Cited by 20 | Viewed by 6756

Abstract

The main aim of this study was the application of excitation-emission fluorescence matrices (EEMs) combined with two decomposition methods: parallel factor analysis (PARAFAC) and nonnegative matrix factorization (NMF) to study the interaction mechanisms between humic acids (HAs) and Zn(II) over a wide concentration [...] Read more.

The main aim of this study was the application of excitation-emission fluorescence matrices (EEMs) combined with two decomposition methods: parallel factor analysis (PARAFAC) and nonnegative matrix factorization (NMF) to study the interaction mechanisms between humic acids (HAs) and Zn(II) over a wide concentration range (0–50 mg·dm⁻³). The influence of HA properties on Zn(II) complexation was also investigated. Stability constants, quenching degree and complexation capacity were estimated for binding sites found in raw EEM, EEM-PARAFAC and EEM-NMF data using mathematical models. A combination of EEM fluorescence analysis with one of the proposed decomposition methods enabled separation of overlapping binding sites and yielded more accurate calculations of the binding parameters. PARAFAC and NMF processing allowed finding binding sites invisible in a few raw EEM datasets as well as finding totally new maxima attributed to structures of the lowest humification. Decomposed data showed an increase in Zn complexation with an increase in humification, aromaticity and molecular weight of HAs. EEM-PARAFAC analysis also revealed that the most stable compounds were formed by structures containing the highest amounts of nitrogen. The content of oxygen-functional groups did not influence the binding parameters, mainly due to fact of higher competition of metal cation with protons. EEM spectra coupled with NMF and especially PARAFAC processing gave more adequate assessments of interactions as compared to raw EEM data and should be especially recommended for modeling of complexation processes where the fluorescence intensities (FI) changes are weak or where the processes are interfered with by the presence of other fluorophores. Full article

(This article belongs to the Section Chemical Sensors)

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17 pages, 3772 KiB

Open AccessArticle

A Portable Farmland Information Collection System with Multiple Sensors

by Jianfeng Zhang, Jinyang Hu, Lvwen Huang, Zhiyong Zhang and Yimian Ma

Sensors 2016, 16(10), 1762; https://doi.org/10.3390/s16101762 - 22 Oct 2016

Cited by 17 | Viewed by 7754

Abstract

Precision agriculture is the trend of modern agriculture, and it is also one of the important ways to realize the sustainable development of agriculture. In order to meet the production requirements of precision agriculture—efficient use of agricultural resources, and improving the crop yields [...] Read more.

Precision agriculture is the trend of modern agriculture, and it is also one of the important ways to realize the sustainable development of agriculture. In order to meet the production requirements of precision agriculture—efficient use of agricultural resources, and improving the crop yields and quality—some necessary field information in crop growth environment needs to be collected and monitored. In this paper, a farmland information collection system is developed, which includes a portable farmland information collection device based on STM32 (a 32-bit comprehensive range of microcontrollers based on ARM Crotex-M3), a remote server and a mobile phone APP. The device realizes the function of portable and mobile collecting of multiple parameters farmland information, such as chlorophyll content of crop leaves, air temperature, air humidity, and light intensity. UM220-III (Unicore Communication Inc., Beijing, China) is used to realize the positioning based on BDS/GPS (BeiDou Navigation Satellite System, BDS/Global Positioning System, GPS) dual-mode navigation and positioning system, and the CDMA (Code Division Multiple Access, CDMA) wireless communication module is adopted to realize the real-time remote transmission. The portable multi-function farmland information collection system is real-time, accurate, and easy to use to collect farmland information and multiple information parameters of crops. Full article

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

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10 pages, 7853 KiB

Open AccessArticle

Achievement of High-Response Organic Field-Effect Transistor NO₂ Sensor by Using the Synergistic Effect of ZnO/PMMA Hybrid Dielectric and CuPc/Pentacene Heterojunction

by Shijiao Han, Jiang Cheng, Huidong Fan, Junsheng Yu and Lu Li

Sensors 2016, 16(10), 1763; https://doi.org/10.3390/s16101763 - 21 Oct 2016

Cited by 15 | Viewed by 8279

Abstract

High-response organic field-effect transistor (OFET)-based NO₂ sensors were fabricated using the synergistic effect the synergistic effect of zinc oxide/poly(methyl methacrylate) (ZnO/PMMA) hybrid dielectric and CuPc/Pentacene heterojunction. Compared with the OFET sensors without synergistic effect, the fabricated OFET sensors showed a remarkable shift [...] Read more.

High-response organic field-effect transistor (OFET)-based NO₂ sensors were fabricated using the synergistic effect the synergistic effect of zinc oxide/poly(methyl methacrylate) (ZnO/PMMA) hybrid dielectric and CuPc/Pentacene heterojunction. Compared with the OFET sensors without synergistic effect, the fabricated OFET sensors showed a remarkable shift of saturation current, field-effect mobility and threshold voltage when exposed to various concentrations of NO₂ analyte. Moreover, after being stored in atmosphere for 30 days, the variation of saturation current increased more than 10 folds at 0.5 ppm NO₂. By analyzing the electrical characteristics, and the morphologies of organic semiconductor films of the OFET-based sensors, the performance enhancement was ascribed to the synergistic effect of the dielectric and organic semiconductor. The ZnO nanoparticles on PMMA dielectric surface decreased the grain size of pentacene formed on hybrid dielectric, facilitating the diffusion of CuPc molecules into the grain boundary of pentacene and the approach towards the conducting channel of OFET. Hence, NO₂ molecules could interact with CuPc and ZnO nanoparticles at the interface of dielectric and organic semiconductor. Our results provided a promising strategy for the design of high performance OFET-based NO₂ sensors in future electronic nose and environment monitoring. Full article

(This article belongs to the Special Issue Gas Nanosensors)

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13 pages, 3634 KiB

Open AccessArticle

In-Field, In Situ, and In Vivo 3-Dimensional Elemental Mapping for Plant Tissue and Soil Analysis Using Laser-Induced Breakdown Spectroscopy

by Chunjiang Zhao, Daming Dong, Xiaofan Du and Wengang Zheng

Sensors 2016, 16(10), 1764; https://doi.org/10.3390/s16101764 - 22 Oct 2016

Cited by 22 | Viewed by 7159

Abstract

Sensing and mapping element distributions in plant tissues and its growth environment has great significance for understanding the uptake, transport, and accumulation of nutrients and harmful elements in plants, as well as for understanding interactions between plants and the environment. In this study, [...] Read more.

Sensing and mapping element distributions in plant tissues and its growth environment has great significance for understanding the uptake, transport, and accumulation of nutrients and harmful elements in plants, as well as for understanding interactions between plants and the environment. In this study, we developed a 3-dimensional elemental mapping system based on laser-induced breakdown spectroscopy that can be deployed in- field to directly measure the distribution of multiple elements in living plants as well as in the soil. Mapping is performed by a fast scanning laser, which ablates a micro volume of a sample to form a plasma. The presence and concentration of specific elements are calculated using the atomic, ionic, and molecular spectral characteristics of the plasma emission spectra. Furthermore, we mapped the pesticide residues in maize leaves after spraying to demonstrate the capacity of this method for trace elemental mapping. We also used the system to quantitatively detect the element concentrations in soil, which can be used to further understand the element transport between plants and soil. We demonstrate that this method has great potential for elemental mapping in plant tissues and soil with the advantages of 3-dimensional and multi-elemental mapping, in situ and in vivo measurement, flexible use, and low cost. Full article

(This article belongs to the Special Issue Sensors for Environmental Monitoring 2016)

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17 pages, 6345 KiB

Open AccessArticle

Experimental Study on Damage Detection in Timber Specimens Based on an Electromechanical Impedance Technique and RMSD-Based Mahalanobis Distance

by Dansheng Wang, Qinghua Wang, Hao Wang and Hongping Zhu

Sensors 2016, 16(10), 1765; https://doi.org/10.3390/s16101765 - 22 Oct 2016

Cited by 55 | Viewed by 5462

Abstract

In the electromechanical impedance (EMI) method, the PZT patch performs the functions of both sensor and exciter. Due to the high frequency actuation and non-model based characteristics, the EMI method can be utilized to detect incipient structural damage. In recent years EMI techniques [...] Read more.

In the electromechanical impedance (EMI) method, the PZT patch performs the functions of both sensor and exciter. Due to the high frequency actuation and non-model based characteristics, the EMI method can be utilized to detect incipient structural damage. In recent years EMI techniques have been widely applied to monitor the health status of concrete and steel materials, however, studies on application to timber are limited. This paper will explore the feasibility of using the EMI technique for damage detection in timber specimens. In addition, the conventional damage index, namely root mean square deviation (RMSD) is employed to evaluate the level of damage. On that basis, a new damage index, Mahalanobis distance based on RMSD, is proposed to evaluate the damage severity of timber specimens. Experimental studies are implemented to detect notch and hole damage in the timber specimens. Experimental results verify the availability and robustness of the proposed damage index and its superiority over the RMSD indexes. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 5264 KiB

Open AccessArticle

Plantar Pressure Detection with Fiber Bragg Gratings Sensing System

by Tsair-Chun Liang, Jhe-Jhun Lin and Lan-Yuen Guo

Sensors 2016, 16(10), 1766; https://doi.org/10.3390/s16101766 - 22 Oct 2016

Cited by 39 | Viewed by 10533

Abstract

In this paper, a novel fiber-optic sensing system based on fiber Bragg gratings (FBGs) to measure foot plantar pressure is proposed. This study first explores the Pedar-X insole foot pressure types of the adult-size chart and then defines six measurement areas to effectively [...] Read more.

In this paper, a novel fiber-optic sensing system based on fiber Bragg gratings (FBGs) to measure foot plantar pressure is proposed. This study first explores the Pedar-X insole foot pressure types of the adult-size chart and then defines six measurement areas to effectively identify four foot types: neutral foot, cavus foot, supinated foot and flat foot. The plantar pressure signals are detected by only six FBGs, which are embedded in silicone rubber. The performance of the fiber optic sensing is examined and compared with a digital pressure plate of i-Step P1000 with 1024 barometric sensors. In the experiment, there are 11 participants with different foot types to participate in the test. The Pearson correlation coefficient, which is determined from the measured results of the homemade fiber-optic plantar pressure system and i-Step P1000 plantar pressure plate, reaches up to 0.671 (p < 0.01). According to the measured results from the plantar pressure data, the proposed fiber optic sensing system can successfully identify the four different foot types. Measurements of this study have demonstrated the feasibility of the proposed system so that it can be an alternative for plantar pressure detection systems. Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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12 pages, 2274 KiB

Open AccessArticle

A Nanoporous Alumina Membrane Based Electrochemical Biosensor for Histamine Determination with Biofunctionalized Magnetic Nanoparticles Concentration and Signal Amplification

by Weiwei Ye, Yifan Xu, Lihao Zheng, Yu Zhang, Mo Yang and Peilong Sun

Sensors 2016, 16(10), 1767; https://doi.org/10.3390/s16101767 - 22 Oct 2016

Cited by 42 | Viewed by 8047

Abstract

Histamine is an indicator of food quality and indispensable in the efficient functioning of various physiological systems. Rapid and sensitive determination of histamine is urgently needed in food analysis and clinical diagnostics. Traditional histamine detection methods require qualified personnel, need complex operation processes, [...] Read more.

Histamine is an indicator of food quality and indispensable in the efficient functioning of various physiological systems. Rapid and sensitive determination of histamine is urgently needed in food analysis and clinical diagnostics. Traditional histamine detection methods require qualified personnel, need complex operation processes, and are time-consuming. In this study, a biofunctionalized nanoporous alumina membrane based electrochemical biosensor with magnetic nanoparticles (MNPs) concentration and signal amplification was developed for histamine determination. Nanoporous alumina membranes were modified by anti-histamine antibody and integrated into polydimethylsiloxane (PDMS) chambers. The specific antibody modified MNPs were used to concentrate histamine from samples and transferred to the antibody modified nanoporous membrane. The MNPs conjugated to histamine were captured in the nanopores via specific reaction between histamine and anti-histamine antibody, resulting in a blocking effect that was amplified by MNPs in the nanopores. The blockage signals could be measured by electrochemical impedance spectroscopy across the nanoporous alumina membrane. The sensing platform had great sensitivity and the limit of detection (LOD) reached as low as 3 nM. This biosensor could be successfully applied for histamine determination in saury that was stored in frozen conditions for different hours, presenting a potentially novel, sensitive, and specific sensing system for food quality assessment and safety support. Full article

(This article belongs to the Special Issue Nanobiosensors in Food Industry)

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18 pages, 5933 KiB

Open AccessArticle

An Improved Map-Matching Technique Based on the Fréchet Distance Approach for Pedestrian Navigation Services

by Yoonsik Bang, Jiyoung Kim and Kiyun Yu

Sensors 2016, 16(10), 1768; https://doi.org/10.3390/s16101768 - 22 Oct 2016

Cited by 24 | Viewed by 7985

Abstract

Wearable and smartphone technology innovations have propelled the growth of Pedestrian Navigation Services (PNS). PNS need a map-matching process to project a user’s locations onto maps. Many map-matching techniques have been developed for vehicle navigation services. These techniques are inappropriate for PNS because [...] Read more.

Wearable and smartphone technology innovations have propelled the growth of Pedestrian Navigation Services (PNS). PNS need a map-matching process to project a user’s locations onto maps. Many map-matching techniques have been developed for vehicle navigation services. These techniques are inappropriate for PNS because pedestrians move, stop, and turn in different ways compared to vehicles. In addition, the base map data for pedestrians are more complicated than for vehicles. This article proposes a new map-matching method for locating Global Positioning System (GPS) trajectories of pedestrians onto road network datasets. The theory underlying this approach is based on the Fréchet distance, one of the measures of geometric similarity between two curves. The Fréchet distance approach can provide reasonable matching results because two linear trajectories are parameterized with the time variable. Then we improved the method to be adaptive to the positional error of the GPS signal. We used an adaptation coefficient to adjust the search range for every input signal, based on the assumption of auto-correlation between consecutive GPS points. To reduce errors in matching, the reliability index was evaluated in real time for each match. To test the proposed map-matching method, we applied it to GPS trajectories of pedestrians and the road network data. We then assessed the performance by comparing the results with reference datasets. Our proposed method performed better with test data when compared to a conventional map-matching technique for vehicles. Full article

(This article belongs to the Section Physical Sensors)

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27 pages, 4984 KiB

Open AccessArticle

Underwater Communications for Video Surveillance Systems at 2.4 GHz

by Sandra Sendra, Jaime Lloret, Jose Miguel Jimenez and Joel J.P.C. Rodrigues

Sensors 2016, 16(10), 1769; https://doi.org/10.3390/s16101769 - 23 Oct 2016

Cited by 16 | Viewed by 7539

Abstract

Video surveillance is needed to control many activities performed in underwater environments. The use of wired media can be a problem since the material specially designed for underwater environments is very expensive. In order to transmit the images and videos wirelessly under water, [...] Read more.

Video surveillance is needed to control many activities performed in underwater environments. The use of wired media can be a problem since the material specially designed for underwater environments is very expensive. In order to transmit the images and videos wirelessly under water, three main technologies can be used: acoustic waves, which do not provide high bandwidth, optical signals, although the effect of light dispersion in water severely penalizes the transmitted signals and therefore, despite offering high transfer rates, the maximum distance is very small, and electromagnetic (EM) waves, which can provide enough bandwidth for video delivery. In the cases where the distance between transmitter and receiver is short, the use of EM waves would be an interesting option since they provide high enough data transfer rates to transmit videos with high resolution. This paper presents a practical study of the behavior of EM waves at 2.4 GHz in freshwater underwater environments. First, we discuss the minimum requirements of a network to allow video delivery. From these results, we measure the maximum distance between nodes and the round trip time (RTT) value depending on several parameters such as data transfer rate, signal modulations, working frequency, and water temperature. The results are statistically analyzed to determine their relation. Finally, the EM waves’ behavior is modeled by a set of equations. The results show that there are some combinations of working frequency, modulation, transfer rate and temperature that offer better results than others. Our work shows that short communication distances with high data transfer rates is feasible. Full article

(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)

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12 pages, 2326 KiB

Open AccessArticle

Development of an FBG Sensor Array for Multi-Impact Source Localization on CFRP Structures

by Mingshun Jiang, Yaozhang Sai, Xiangyi Geng, Qingmei Sui, Xiaohui Liu and Lei Jia

Sensors 2016, 16(10), 1770; https://doi.org/10.3390/s16101770 - 24 Oct 2016

Cited by 9 | Viewed by 4981

Abstract

We proposed and studied an impact detection system based on a fiber Bragg grating (FBG) sensor array and multiple signal classification (MUSIC) algorithm to determine the location and the number of low velocity impacts on a carbon fiber-reinforced polymer (CFRP) plate. A FBG [...] Read more.

We proposed and studied an impact detection system based on a fiber Bragg grating (FBG) sensor array and multiple signal classification (MUSIC) algorithm to determine the location and the number of low velocity impacts on a carbon fiber-reinforced polymer (CFRP) plate. A FBG linear array, consisting of seven FBG sensors, was used for detecting the ultrasonic signals from impacts. The edge-filter method was employed for signal demodulation. Shannon wavelet transform was used to extract narrow band signals from the impacts. The Gerschgorin disc theorem was used for estimating the number of impacts. We used the MUSIC algorithm to obtain the coordinates of multi-impacts. The impact detection system was tested on a 500 mm × 500 mm × 1.5 mm CFRP plate. The results show that the maximum error and average error of the multi-impacts’ localization are 9.2 mm and 7.4 mm, respectively. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 5466 KiB

Open AccessArticle

GNSS Spoofing Network Monitoring Based on Differential Pseudorange

by Zhenjun Zhang and Xingqun Zhan

Sensors 2016, 16(10), 1771; https://doi.org/10.3390/s16101771 - 23 Oct 2016

Cited by 20 | Viewed by 6472

Abstract

Spoofing is becoming a serious threat to various Global Navigation Satellite System (GNSS) applications, especially for those that require high reliability and security such as power grid synchronization and applications related to first responders and aviation safety. Most current works on anti-spoofing focus [...] Read more.

Spoofing is becoming a serious threat to various Global Navigation Satellite System (GNSS) applications, especially for those that require high reliability and security such as power grid synchronization and applications related to first responders and aviation safety. Most current works on anti-spoofing focus on spoofing detection from the individual receiver side, which identifies spoofing when it is under an attack. This paper proposes a novel spoofing network monitoring (SNM) mechanism aiming to reveal the presence of spoofing within an area. Consisting of several receivers and one central processing component, it keeps detecting spoofing even when the network is not attacked. The mechanism is based on the different time difference of arrival (TDOA) properties between spoofing and authentic signals. Normally, TDOAs of spoofing signals from a common spoofer are identical while those of authentic signals from diverse directions are dispersed. The TDOA is measured as the differential pseudorange to carrier frequency ratio (DPF). In a spoofing case, the DPFs include those of both authentic and spoofing signals, among which the DPFs of authentic are dispersed while those of spoofing are almost overlapped. An algorithm is proposed to search for the DPFs that are within a pre-defined small range, and an alarm will be raised if several DPFs are found within such range. The proposed SNM methodology is validated by simulations and a partial field trial. Results show 99.99% detection and 0.01% false alarm probabilities are achieved. The SNM has the potential to be adopted in various applications such as (1) alerting dedicated users when spoofing is occurring, which could significantly shorten the receiver side spoofing cost; (2) in combination with GNSS performance monitoring systems, such as the Continuous Operating Reference System (CORS) and GNSS Availability, Accuracy, Reliability anD Integrity Assessment for Timing and Navigation (GAARDIAN) System, to provide more reliable monitoring services. Full article

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

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15 pages, 597 KiB

Open AccessArticle

SNR Degradation in Undersampled Phase Measurement Systems

by David Salido-Monzú, Francisco J. Meca-Meca, Ernesto Martín-Gorostiza and José L. Lázaro-Galilea

Sensors 2016, 16(10), 1772; https://doi.org/10.3390/s16101772 - 24 Oct 2016

Cited by 10 | Viewed by 5285

Abstract

A wide range of measuring applications rely on phase estimation on sinusoidal signals. These systems, where the estimation is mainly implemented in the digital domain, can generally benefit from the use of undersampling to reduce the digitizer and subsequent digital processing requirements. This [...] Read more.

A wide range of measuring applications rely on phase estimation on sinusoidal signals. These systems, where the estimation is mainly implemented in the digital domain, can generally benefit from the use of undersampling to reduce the digitizer and subsequent digital processing requirements. This may be crucial when the application characteristics necessarily imply a simple and inexpensive sensor. However, practical limitations related to the phase stability of the band-pass filter prior digitization establish restrictions to the reduction of noise bandwidth. Due to this, the undersampling intensity is practically defined by noise aliasing, taking into account the amount of signal-to-noise ratio (SNR) reduction caused by it considering the application accuracy requirements. This work analyzes the relationship between undersampling frequency and SNR reduction, conditioned by the stability requirements of the filter that defines the noise bandwidth before digitization. The effect of undersampling is quantified in a practical situation where phase differences are measured by in-phase and quadrature (I/Q) demodulation for an infrared ranging application. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 2854 KiB

Open AccessArticle

Sparse Reconstruction for Micro Defect Detection in Acoustic Micro Imaging

by Yichun Zhang, Tielin Shi, Lei Su, Xiao Wang, Yuan Hong, Kepeng Chen and Guanglan Liao

Sensors 2016, 16(10), 1773; https://doi.org/10.3390/s16101773 - 24 Oct 2016

Cited by 9 | Viewed by 5921

Abstract

Acoustic micro imaging has been proven to be sufficiently sensitive for micro defect detection. In this study, we propose a sparse reconstruction method for acoustic micro imaging. A finite element model with a micro defect is developed to emulate the physical scanning. Then [...] Read more.

Acoustic micro imaging has been proven to be sufficiently sensitive for micro defect detection. In this study, we propose a sparse reconstruction method for acoustic micro imaging. A finite element model with a micro defect is developed to emulate the physical scanning. Then we obtain the point spread function, a blur kernel for sparse reconstruction. We reconstruct deblurred images from the oversampled C-scan images based on l₁-norm regularization, which can enhance the signal-to-noise ratio and improve the accuracy of micro defect detection. The method is further verified by experimental data. The results demonstrate that the sparse reconstruction is effective for micro defect detection in acoustic micro imaging. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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7 pages, 2611 KiB

Open AccessArticle

Optical Fiber Temperature and Torsion Sensor Based on Lyot-Sagnac Interferometer

by Li-Yang Shao, Xinpu Zhang, Haijun He, Zhiyong Zhang, Xihua Zou, Bin Luo, Wei Pan and Lianshan Yan

Sensors 2016, 16(10), 1774; https://doi.org/10.3390/s16101774 - 24 Oct 2016

Cited by 29 | Viewed by 6704

Abstract

An optical fiber temperature and torsion sensor has been proposed by employing the Lyot-Sagnac interferometer, which was composed by inserting two sections of high-birefringence (HiBi) fiber into the Sagnac loop. The two inserted sections of HiBi fiber have different functions; while one section [...] Read more.

An optical fiber temperature and torsion sensor has been proposed by employing the Lyot-Sagnac interferometer, which was composed by inserting two sections of high-birefringence (HiBi) fiber into the Sagnac loop. The two inserted sections of HiBi fiber have different functions; while one section acts as the temperature sensitive region, the other can be used as reference fiber. The temperature and twist sensor based on the proposed interferometer structure have been experimentally demonstrated. The experimental results show that the envelope of the output spectrum will shift with the temperature evolution. The temperature sensitivity is calculated to be −17.99 nm/°C, which is enlarged over 12 times compared to that of the single Sagnac interferometer. Additionally, the fringe visibility of the spectrum will change due to the fiber twist, and the test results reveal that the fringe visibility and twist angle perfectly conform to a Sine relationship over a 360° twist angle. Consequently, simultaneous torsion and temperature measurement could be realized by detecting the envelope shift and fringe visibility of the spectrum. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4480 KiB

Open AccessArticle

Geometric Calibration and Validation of Kompsat-3A AEISS-A Camera

by Doocheon Seo, Jaehong Oh, Changno Lee, Donghan Lee and Haejin Choi

Sensors 2016, 16(10), 1776; https://doi.org/10.3390/s16101776 - 24 Oct 2016

Cited by 17 | Viewed by 7666

Abstract

Kompsat-3A, which was launched on 25 March 2015, is a sister spacecraft of the Kompsat-3 developed by the Korea Aerospace Research Institute (KARI). Kompsat-3A’s AEISS-A (Advanced Electronic Image Scanning System-A) camera is similar to Kompsat-3’s AEISS but it was designed to provide PAN [...] Read more.

Kompsat-3A, which was launched on 25 March 2015, is a sister spacecraft of the Kompsat-3 developed by the Korea Aerospace Research Institute (KARI). Kompsat-3A’s AEISS-A (Advanced Electronic Image Scanning System-A) camera is similar to Kompsat-3’s AEISS but it was designed to provide PAN (Panchromatic) resolution of 0.55 m, MS (multispectral) resolution of 2.20 m, and TIR (thermal infrared) at 5.5 m resolution. In this paper we present the geometric calibration and validation work of Kompsat-3A that was completed last year. A set of images over the test sites was taken for two months and was utilized for the work. The workflow includes the boresight calibration, CCDs (charge-coupled devices) alignment and focal length determination, the merge of two CCD lines, and the band-to-band registration. Then, the positional accuracies without any GCPs (ground control points) were validated for hundreds of test sites across the world using various image acquisition modes. In addition, we checked the planimetric accuracy by bundle adjustments with GCPs. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

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Review

Jump to: Research, Other

26 pages, 2636 KiB

Open AccessReview

Six-Port Based Interferometry for Precise Radar and Sensing Applications

by Alexander Koelpin, Fabian Lurz, Sarah Linz, Sebastian Mann, Christoph Will and Stefan Lindner

Sensors 2016, 16(10), 1556; https://doi.org/10.3390/s16101556 - 22 Sep 2016

Cited by 74 | Viewed by 14851

Abstract

Microwave technology plays a more important role in modern industrial sensing applications. Pushed by the significant progress in monolithic microwave integrated circuit technology over the past decades, complex sensing systems operating in the microwave and even millimeter-wave range are available for reasonable costs [...] Read more.

Microwave technology plays a more important role in modern industrial sensing applications. Pushed by the significant progress in monolithic microwave integrated circuit technology over the past decades, complex sensing systems operating in the microwave and even millimeter-wave range are available for reasonable costs combined with exquisite performance. In the context of industrial sensing, this stimulates new approaches for metrology based on microwave technology. An old measurement principle nearly forgotten over the years has recently gained more and more attention in both academia and industry: the six-port interferometer. This paper reviews the basic concept, investigates promising applications in remote, as well as contact-based sensing and compares the system with state-of-the-art metrology. The significant advantages will be discussed just as the limitations of the six-port architecture. Particular attention will be paid to impairment effects and non-ideal behavior, as well as compensation and linearization concepts. It will be shown that in application fields, like remote distance sensing, precise alignment measurements, as well as interferometrically-evaluated mechanical strain analysis, the six-port architecture delivers extraordinary measurement results combined with high measurement data update rates for reasonable system costs. This makes the six-port architecture a promising candidate for industrial metrology. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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31 pages, 4274 KiB

Open AccessReview

Sensor Fusion and Smart Sensor in Sports and Biomedical Applications

by José Jair Alves Mendes Jr., Mário Elias Marinho Vieira, Marcelo Bissi Pires and Sergio Luiz Stevan Jr.

Sensors 2016, 16(10), 1569; https://doi.org/10.3390/s16101569 - 23 Sep 2016

Cited by 97 | Viewed by 25395

Abstract

The following work presents an overview of smart sensors and sensor fusion targeted at biomedical applications and sports areas. In this work, the integration of these areas is demonstrated, promoting a reflection about techniques and applications to collect, quantify and qualify some physical [...] Read more.

The following work presents an overview of smart sensors and sensor fusion targeted at biomedical applications and sports areas. In this work, the integration of these areas is demonstrated, promoting a reflection about techniques and applications to collect, quantify and qualify some physical variables associated with the human body. These techniques are presented in various biomedical and sports applications, which cover areas related to diagnostics, rehabilitation, physical monitoring, and the development of performance in athletes, among others. Although some applications are described in only one of two fields of study (biomedicine and sports), it is very likely that the same application fits in both, with small peculiarities or adaptations. To illustrate the contemporaneity of applications, an analysis of specialized papers published in the last six years has been made. In this context, the main characteristic of this review is to present the largest quantity of relevant examples of sensor fusion and smart sensors focusing on their utilization and proposals, without deeply addressing one specific system or technique, to the detriment of the others. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

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32 pages, 2003 KiB

Open AccessReview

Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

by Paloma Yáñez-Sedeño, Susana Campuzano and José M. Pingarrón

Sensors 2016, 16(10), 1585; https://doi.org/10.3390/s16101585 - 25 Sep 2016

Cited by 36 | Viewed by 8842

Abstract

Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled [...] Read more.

Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively) have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered. Full article

(This article belongs to the Special Issue Recent Advances in Biosensors Based Screen Printed Platforms)

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44 pages, 4836 KiB

Open AccessReview

A Review on Internet of Things for Defense and Public Safety

by Paula Fraga-Lamas, Tiago M. Fernández-Caramés, Manuel Suárez-Albela, Luis Castedo and Miguel González-López

Sensors 2016, 16(10), 1644; https://doi.org/10.3390/s16101644 - 5 Oct 2016

Cited by 180 | Viewed by 39258

Abstract

The Internet of Things (IoT) is undeniably transforming the way that organizations communicate and organize everyday businesses and industrial procedures. Its adoption has proven well suited for sectors that manage a large number of assets and coordinate complex and distributed processes. This survey [...] Read more.

The Internet of Things (IoT) is undeniably transforming the way that organizations communicate and organize everyday businesses and industrial procedures. Its adoption has proven well suited for sectors that manage a large number of assets and coordinate complex and distributed processes. This survey analyzes the great potential for applying IoT technologies (i.e., data-driven applications or embedded automation and intelligent adaptive systems) to revolutionize modern warfare and provide beneﬁts similar to those in industry. It identiﬁes scenarios where Defense and Public Safety (PS) could leverage better commercial IoT capabilities to deliver greater survivability to the warﬁghter or ﬁrst responders, while reducing costs and increasing operation efﬁciency and effectiveness. This article reviews the main tactical requirements and the architecture, examining gaps and shortcomings in existing IoT systems across the military ﬁeld and mission-critical scenarios. The review characterizes the open challenges for a broad deployment and presents a research roadmap for enabling an affordable IoT for defense and PS. Full article

(This article belongs to the Special Issue Enabling the Move from Wireless Sensor Networks to Internet of Things and Cyber-Physical Systems)

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23 pages, 271 KiB

Open AccessReview

Application and Uses of Electronic Noses for Clinical Diagnosis on Urine Samples: A Review

by Laura Capelli, Gianluigi Taverna, Alessia Bellini, Lidia Eusebio, Niccolò Buffi, Massimo Lazzeri, Giorgio Guazzoni, Giorgio Bozzini, Mauro Seveso, Alberto Mandressi, Lorenzo Tidu, Fabio Grizzi, Paolo Sardella, Giuseppe Latorre, Rodolfo Hurle, Giovanni Lughezzani, Paolo Casale, Sara Meregali and Selena Sironi

Sensors 2016, 16(10), 1708; https://doi.org/10.3390/s16101708 - 14 Oct 2016

Cited by 67 | Viewed by 9452

Abstract

The electronic nose is able to provide useful information through the analysis of the volatile organic compounds in body fluids, such as exhaled breath, urine and blood. This paper focuses on the review of electronic nose studies and applications in the specific field [...] Read more.

The electronic nose is able to provide useful information through the analysis of the volatile organic compounds in body fluids, such as exhaled breath, urine and blood. This paper focuses on the review of electronic nose studies and applications in the specific field of medical diagnostics based on the analysis of the gaseous headspace of human urine, in order to provide a broad overview of the state of the art and thus enhance future developments in this field. The research in this field is rather recent and still in progress, and there are several aspects that need to be investigated more into depth, not only to develop and improve specific electronic noses for different diseases, but also with the aim to discover and analyse the connections between specific diseases and the body fluids odour. Further research is needed to improve the results obtained up to now; the development of new sensors and data processing methods should lead to greater diagnostic accuracy thus making the electronic nose an effective tool for early detection of different kinds of diseases, ranging from infections to tumours or exposure to toxic agents. Full article

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

19 pages, 4352 KiB

Open AccessReview

Responsive Boronic Acid-Decorated (Co)polymers: From Glucose Sensors to Autonomous Drug Delivery

by Gertjan Vancoillie and Richard Hoogenboom

Sensors 2016, 16(10), 1736; https://doi.org/10.3390/s16101736 - 19 Oct 2016

Cited by 31 | Viewed by 10483

Abstract

Boronic acid-containing (co)polymers have fascinated researchers for decades, garnering attention for their unique responsiveness toward 1,2- and 1,3-diols, including saccharides and nucleotides. The applications of materials that exert this property are manifold including sensing, but also self-regulated drug delivery systems through responsive membranes [...] Read more.

Boronic acid-containing (co)polymers have fascinated researchers for decades, garnering attention for their unique responsiveness toward 1,2- and 1,3-diols, including saccharides and nucleotides. The applications of materials that exert this property are manifold including sensing, but also self-regulated drug delivery systems through responsive membranes or micelles. In this review, some of the main applications of boronic acid containing (co)polymers are discussed focusing on the role of the boronic acid group in the response mechanism. We hope that this summary, which highlights the importance and potential of boronic acid-decorated polymeric materials, will inspire further research within this interesting field of responsive polymers and polymeric materials. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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16 pages, 2723 KiB

Open AccessReview

Printable Electrochemical Biosensors: A Focus on Screen-Printed Electrodes and Their Application

by Keiichiro Yamanaka, Mun’delanji C. Vestergaard and Eiichi Tamiya

Sensors 2016, 16(10), 1761; https://doi.org/10.3390/s16101761 - 21 Oct 2016

Cited by 153 | Viewed by 14149

Abstract

In this review we present electrochemical biosensor developments, focusing on screen-printed electrodes (SPEs) and their applications. In particular, we discuss how SPEs enable simple integration, and the portability needed for on-field applications. First, we briefly discuss the general concept of biosensors and quickly [...] Read more.

In this review we present electrochemical biosensor developments, focusing on screen-printed electrodes (SPEs) and their applications. In particular, we discuss how SPEs enable simple integration, and the portability needed for on-field applications. First, we briefly discuss the general concept of biosensors and quickly move on to electrochemical biosensors. Drawing from research undertaken in this area, we cover the development of electrochemical DNA biosensors in great detail. Through specific examples, we describe the fabrication and surface modification of printed electrodes for sensitive and selective detection of targeted DNA sequences, as well as integration with reverse transcription-polymerase chain reaction (RT-PCR). For a more rounded approach, we also touch on electrochemical immunosensors and enzyme-based biosensors. Last, we present some electrochemical devices specifically developed for use with SPEs, including USB-powered compact mini potentiostat. The coupling demonstrates the practical use of printable electrode technologies for application at point-of-use. Although tremendous advances have indeed been made in this area, a few challenges remain. One of the main challenges is application of these technologies for on-field analysis, which involves complicated sample matrices. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

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7 pages, 1644 KiB

Open AccessLetter

Patterns-of-Life Aided Authentication

by Nan Zhao, Aifeng Ren, Zhiya Zhang, Tianqiao Zhu, Masood Ur Rehman, Xiaodong Yang and Fangming Hu

Sensors 2016, 16(10), 1574; https://doi.org/10.3390/s16101574 - 23 Sep 2016

Cited by 3 | Viewed by 5226

Abstract

Wireless Body Area Network (WBAN) applications have grown immensely in the past few years. However, security and privacy of the user are two major obstacles in their development. The complex and very sensitive nature of the body-mounted sensors means the traditional network layer [...] Read more.

Wireless Body Area Network (WBAN) applications have grown immensely in the past few years. However, security and privacy of the user are two major obstacles in their development. The complex and very sensitive nature of the body-mounted sensors means the traditional network layer security arrangements are not sufficient to employ their full potential, and novel solutions are necessary. In contrast, security methods based on physical layers tend to be more suitable and have simple requirements. The problem of initial trust needs to be addressed as a prelude to the physical layer security key arrangement. This paper proposes a patterns-of-life aided authentication model to solve this issue. The model employs the wireless channel fingerprint created by the user’s behavior characterization. The performance of the proposed model is established through experimental measurements at 2.45 GHz. Experimental results show that high correlation values of 0.852 to 0.959 with the habitual action of the user in different scenarios can be used for auxiliary identity authentication, which is a scalable result for future studies. Full article

(This article belongs to the Special Issue Body Worn Behavior Sensing)

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10 pages, 5386 KiB

Open AccessLetter

In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor

by Chi-Yuan Lee, Fang-Bor Weng, Yzu-Wei Kuo, Chao-Hsuan Tsai, Yen-Ting Cheng, Chih-Kai Cheng and Jyun-Ting Lin

Sensors 2016, 16(10), 1731; https://doi.org/10.3390/s16101731 - 18 Oct 2016

Cited by 19 | Viewed by 6435

Abstract

In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime [...] Read more.

In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery. Full article

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

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