Sensors

16 pages, 1741 KiB

Open AccessArticle

Quantification of Finger-Tapping Angle Based on Wearable Sensors

by Milica Djurić-Jovičić^1,*, Nenad S. Jovičić², Agnes Roby-Brami³

, Mirjana B. Popović², Vladimir S. Kostić^4,5 and Antonije R. Djordjević^2,5

¹ Innovation Center, School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade, Serbia

² School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade, Serbia

³ Institut des Systèmes Intelligents et de Robotique, Université Pierre et Marie Curie, 4 Place JUSSIEU, 75005 Paris, France

⁴ Institute for Neurology, School of Medicine, University of Belgrade, Dr. Subotića 6, 11120 Belgrade, Serbia

⁵ Serbian Academy of Sciences and Arts, Knez Mihajlova 35, 11001 Belgrade, Serbia

Sensors 2017, 17(2), 203; https://doi.org/10.3390/s17020203 - 25 Jan 2017

Cited by 34 | Viewed by 8536

Abstract

We propose a novel simple method for quantitative and qualitative finger-tapping assessment based on miniature inertial sensors (3D gyroscopes) placed on the thumb and index-finger. We propose a simplified description of the finger tapping by using a single angle, describing rotation around a [...] Read more.

We propose a novel simple method for quantitative and qualitative finger-tapping assessment based on miniature inertial sensors (3D gyroscopes) placed on the thumb and index-finger. We propose a simplified description of the finger tapping by using a single angle, describing rotation around a dominant axis. The method was verified on twelve subjects, who performed various tapping tasks, mimicking impaired patterns. The obtained tapping angles were compared with results of a motion capture camera system, demonstrating excellent accuracy. The root-mean-square (RMS) error between the two sets of data is, on average, below 4°, and the intraclass correlation coefficient is, on average, greater than 0.972. Data obtained by the proposed method may be used together with scores from clinical tests to enable a better diagnostic. Along with hardware simplicity, this makes the proposed method a promising candidate for use in clinical practice. Furthermore, our definition of the tapping angle can be applied to all tapping assessment systems. Full article

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

▼ Show Figures

Figure 1

16 pages, 4069 KiB

Open AccessArticle

Volatile Organic Compounds Sensing Using Optical Fibre Long Period Grating with Mesoporous Nano-Scale Coating

by Jiri Hromadka^1,2, Sergiy Korposh^1,3,*

, Matthew Partridge³

, Stephen W. James³, Frank Davis⁴, Derrick Crump⁵ and Ralph P. Tatam³

¹ Optics and Photonics Group, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK

² Institute for Environmental Studies, Charles University in Prague, Benatska 2, Prague 2 CZ-128 01, Czech Republic

³ Centre for Engineering Photonics, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK

⁴ Department of Engineering and Applied Design, University of Chichester Bognor Regis, West Sussex PO21 1HR, UK

⁵ Environmental Science and Technology Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK

Sensors 2017, 17(2), 205; https://doi.org/10.3390/s17020205 - 8 Feb 2017

Cited by 24 | Viewed by 8322

Abstract

A long period grating (LPG) modified with a mesoporous film infused with a calixarene as a functional compound was employed for the detection of individual volatile organic compounds (VOCs) and their mixtures. The mesoporous film consisted of an inorganic part, SiO₂ nanoparticles [...] Read more.

A long period grating (LPG) modified with a mesoporous film infused with a calixarene as a functional compound was employed for the detection of individual volatile organic compounds (VOCs) and their mixtures. The mesoporous film consisted of an inorganic part, SiO₂ nanoparticles (NPs), along with an organic moiety of poly(allylamine hydrochloride) polycation PAH, which was finally infused with the functional compound, p-sulphanato calix[4]arene (CA[4]) or p-sulphanato calix[8]arene (CA[8]). The LPG sensor was designed to operate at the phase matching turning point to provide the highest sensitivity. The sensing mechanism is based on the measurement of the refractive index (RI) change induced by a complex of the VOCs with calixarene. The LPG, modified with a coating of 5 cycles of (SiO₂ NPs/PAH) and infused with CA[4] or CA[8], was exposed to chloroform, benzene, toluene and acetone vapours. The British Standards test of the VOCs emissions from material (BS EN ISO 16000-9:2006) was used to test the LPG sensor performance. Full article

(This article belongs to the Special Issue Gas Nanosensors)

▼ Show Figures

Figure 1

19 pages, 1666 KiB

Open AccessArticle

Intelligent RF-Based Gesture Input Devices Implemented Using e-Textiles

by Dana Hughes^1,*, Halley Profita¹, Sarah Radzihovsky² and Nikolaus Correll^1,*

¹ Department of Computer Science, University of Colorado Boulder, Boulder, CO 80309, USA

² Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA

Sensors 2017, 17(2), 219; https://doi.org/10.3390/s17020219 - 24 Jan 2017

Cited by 6 | Viewed by 7440

Abstract

We present an radio-frequency (RF)-based approach to gesture detection and recognition, using e-textile versions of common transmission lines used in microwave circuits. This approach allows for easy fabrication of input swatches that can detect a continuum of finger positions and similarly basic gestures, [...] Read more.

We present an radio-frequency (RF)-based approach to gesture detection and recognition, using e-textile versions of common transmission lines used in microwave circuits. This approach allows for easy fabrication of input swatches that can detect a continuum of finger positions and similarly basic gestures, using a single measurement line. We demonstrate that the swatches can perform gesture detection when under thin layers of cloth or when weatherproofed, providing a high level of versatility not present with other types of approaches. Additionally, using small convolutional neural networks, low-level gestures can be identified with a high level of accuracy using a small, inexpensive microcontroller, allowing for an intelligent fabric that reports only gestures of interest, rather than a simple sensor requiring constant surveillance from an external computing device. The resulting e-textile smart composite has applications in controlling wearable devices by providing a simple, eyes-free mechanism to input simple gestures. Full article

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

▼ Show Figures

Figure 1

17 pages, 6832 KiB

Open AccessArticle

A Modified Azimuth Weighting Method in a Two-Step Process Approach for Sliding Spotlight Data Processing

by Feng Xiao, Ze-gang Ding^*, Bin Xiong and Teng Long

Beijing Key Laboratory of Embedded Real-time Information Processing Technology, School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China

Sensors 2017, 17(2), 220; https://doi.org/10.3390/s17020220 - 24 Jan 2017

Cited by 1 | Viewed by 4480

Abstract

Low sidelobes are important and essential in all SAR (Synthetic Aperture Radar) images, regardless of the imaging mode, for fewer artificial targets. For strip-map mode all targets overlap in frequency, which is convenient to suppress sidelobes. However, weighting requires total overlap in the [...] Read more.

Low sidelobes are important and essential in all SAR (Synthetic Aperture Radar) images, regardless of the imaging mode, for fewer artificial targets. For strip-map mode all targets overlap in frequency, which is convenient to suppress sidelobes. However, weighting requires total overlap in the time or frequency domain, which a sliding spotlight signal could not satisfy. Furthermore, the wavelength cannot be regarded as a constant value under the condition of a wideband chirp signal, which leads to the variation of the Doppler bandwidth along with the range frequency. In this article, an azimuth weighting method is proposed that considers the influence of a wideband based on a two-step algorithm. The computer simulation is given to verify the presented method. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

9 pages, 4080 KiB

Open AccessArticle

Microshell Arrays Enhanced Sensitivity in Detection of Specific Antibody for Reduced Graphene Oxide Optical Sensor

by Wen-Shuai Jiang¹, Wei Xin¹, Shao-Nan Chen¹, Cun-Bo Li¹, Xiao-Guang Gao¹, Lei-Ting Pan¹, Zhi-Bo Liu^1,2,* and Jian-Guo Tian^1,2

¹ The Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics School and School of Physics, Nankai University, Tianjin 300071, China

² The 2011 Project Collaborative Innovation Center for Biological Therapy, Nankai University, Tianjin 300071, China

Sensors 2017, 17(2), 221; https://doi.org/10.3390/s17020221 - 24 Jan 2017

Cited by 7 | Viewed by 5918

Abstract

Protein-protein interactions play an important role in the investigation of biomolecules. In this paper, we reported on the use of a reduced graphene oxide microshell (RGOM)-based optical biosensor for the determination of goat anti-rabbit IgG. The biosensor was prepared through a self-assembly of [...] Read more.

Protein-protein interactions play an important role in the investigation of biomolecules. In this paper, we reported on the use of a reduced graphene oxide microshell (RGOM)-based optical biosensor for the determination of goat anti-rabbit IgG. The biosensor was prepared through a self-assembly of monolayers of monodisperse polystyrene microspheres, combined with a high-temperature reduction, in order to decorate the RGOM with rabbit IgG. The periodic microshells allowed a simpler functionalization and modification of RGOM with bioreceptor units, than reduced graphene oxide (RGO). With additional antibody-antigen binding, the RGOM-based biosensor achieved better real-time and label-free detection. The RGOM-based biosensor presented a more satisfactory response to goat anti-rabbit IgG than the RGO-based biosensor. This method is promising for immobilizing biomolecules on graphene surfaces and for the fabrication of biosensors with enhanced sensitivity. Full article

(This article belongs to the Special Issue Biosensors for Antibody Detection)

▼ Show Figures

Figure 1

14 pages, 6767 KiB

Open AccessArticle

A Hierarchical Building Segmentation in Digital Surface Models for 3D Reconstruction

by Yiming Yan^1,*, Fengjiao Gao^2,*, Shupei Deng³ and Nan Su³

¹ Institute of Information Technology, Harbin Engineering University, Harbin 150001, China

² Institute of Automation of Heilongjiang Academy of Sciences, Harbin 150001, China

³ Department of Information Engineering, Harbin Institute of Technology, Harbin 150001, China

Sensors 2017, 17(2), 222; https://doi.org/10.3390/s17020222 - 24 Jan 2017

Cited by 20 | Viewed by 6693

Abstract

In this study, a hierarchical method for segmenting buildings in a digital surface model (DSM), which is used in a novel framework for 3D reconstruction, is proposed. Most 3D reconstructions of buildings are model-based. However, the limitations of these methods are overreliance on [...] Read more.

In this study, a hierarchical method for segmenting buildings in a digital surface model (DSM), which is used in a novel framework for 3D reconstruction, is proposed. Most 3D reconstructions of buildings are model-based. However, the limitations of these methods are overreliance on completeness of the offline-constructed models of buildings, and the completeness is not easily guaranteed since in modern cities buildings can be of a variety of types. Therefore, a model-free framework using high precision DSM and texture-images buildings was introduced. There are two key problems with this framework. The first one is how to accurately extract the buildings from the DSM. Most segmentation methods are limited by either the terrain factors or the difficult choice of parameter-settings. A level-set method are employed to roughly find the building regions in the DSM, and then a recently proposed ‘occlusions of random textures model’ are used to enhance the local segmentation of the buildings. The second problem is how to generate the facades of buildings. Synergizing with the corresponding texture-images, we propose a roof-contour guided interpolation of building facades. The 3D reconstruction results achieved by airborne-like images and satellites are compared. Experiments show that the segmentation method has good performance, and 3D reconstruction is easily performed by our framework, and better visualization results can be obtained by airborne-like images, which can be further replaced by UAV images. Full article

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

▼ Show Figures

Figure 1

14 pages, 7394 KiB

Open AccessArticle

A 11 mW 2.4 GHz 0.18 µm CMOS Transceivers for Wireless Sensor Networks

by Bing Hou¹, Hua Chen²

, Zhiyu Wang^2,*, Jiongjiong Mo², Junli Chen³, Faxin Yu² and Wenbo Wang¹

¹ School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China

² School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China

³ School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Sensors 2017, 17(2), 223; https://doi.org/10.3390/s17020223 - 24 Jan 2017

Cited by 5 | Viewed by 6467

Abstract

In this paper, a low power transceiver for wireless sensor networks (WSN) is proposed. The system is designed with fully functional blocks including a receiver, a fractional-N frequency synthesizer, and a class-E transmitter, and it is optimized with a good balance among output [...] Read more.

In this paper, a low power transceiver for wireless sensor networks (WSN) is proposed. The system is designed with fully functional blocks including a receiver, a fractional-N frequency synthesizer, and a class-E transmitter, and it is optimized with a good balance among output power, sensitivity, power consumption, and silicon area. A transmitter and receiver (TX-RX) shared input-output matching network is used so that only one off-chip inductor is needed in the system. The power and area efficiency-oriented, fully-integrated frequency synthesizer is able to provide programmable output frequencies in the 2.4 GHz range while occupying a small silicon area. Implemented in a standard 0.18 μm RF Complementary Metal Oxide Semiconductor (CMOS) technology, the whole transceiver occupies a chip area of 0.5 mm² (1.2 mm² including bonding pads for a QFN package). Measurement results suggest that the design is able to work at amplitude shift keying (ASK)/on-off-keying (OOK) and FSK modes with up to 500 kbps data rate. With an input sensitivity of −60 dBm and an output power of 3 dBm, the receiver, transmitter and frequency synthesizer consumes 2.3 mW, 4.8 mW, and 3.9 mW from a 1.8 V supply voltage, respectively. Full article

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

▼ Show Figures

Figure 1

23 pages, 941 KiB

Open AccessArticle

Outage Probability Minimization for Energy Harvesting Cognitive Radio Sensor Networks

by Fan Zhang^*, Tao Jing, Yan Huo and Kaiwei Jiang

School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China

Sensors 2017, 17(2), 224; https://doi.org/10.3390/s17020224 - 24 Jan 2017

Cited by 12 | Viewed by 6004

Abstract

The incorporation of cognitive radio (CR) capability in wireless sensor networks yields a promising network paradigm known as CR sensor networks (CRSNs), which is able to provide spectrum efficient data communication. However, due to the high energy consumption results from spectrum sensing, as [...] Read more.

The incorporation of cognitive radio (CR) capability in wireless sensor networks yields a promising network paradigm known as CR sensor networks (CRSNs), which is able to provide spectrum efficient data communication. However, due to the high energy consumption results from spectrum sensing, as well as subsequent data transmission, the energy supply for the conventional sensor nodes powered by batteries is regarded as a severe bottleneck for sustainable operation. The energy harvesting technique, which gathers energy from the ambient environment, is regarded as a promising solution to perpetually power-up energy-limited devices with a continual source of energy. Therefore, applying the energy harvesting (EH) technique in CRSNs is able to facilitate the self-sustainability of the energy-limited sensors. The primary concern of this study is to design sensing-transmission policies to minimize the long-term outage probability of EH-powered CR sensor nodes. We formulate this problem as an infinite-horizon discounted Markov decision process and propose an ϵ-optimal sensing-transmission (ST) policy through using the value iteration algorithm. ϵ is the error bound between the ST policy and the optimal policy, which can be pre-defined according to the actual need. Moreover, for a special case that the signal-to-noise (SNR) power ratio is sufficiently high, we present an efficient transmission (ET) policy and prove that the ET policy achieves the same performance with the ST policy. Finally, extensive simulations are conducted to evaluate the performance of the proposed policies and the impaction of various network parameters. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

26 pages, 6586 KiB

Open AccessArticle

An Efficient Location Verification Scheme for Static Wireless Sensor Networks

by In-hwan Kim^*, Bo-sung Kim and JooSeok Song

Department of Computer Science, College of Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

Sensors 2017, 17(2), 225; https://doi.org/10.3390/s17020225 - 24 Jan 2017

Cited by 5 | Viewed by 4785

Abstract

In wireless sensor networks (WSNs), the accuracy of location information is vital to support many interesting applications. Unfortunately, sensors have difficulty in estimating their location when malicious sensors attack the location estimation process. Even though secure localization schemes have been proposed to protect [...] Read more.

In wireless sensor networks (WSNs), the accuracy of location information is vital to support many interesting applications. Unfortunately, sensors have difficulty in estimating their location when malicious sensors attack the location estimation process. Even though secure localization schemes have been proposed to protect location estimation process from attacks, they are not enough to eliminate the wrong location estimations in some situations. The location verification can be the solution to the situations or be the second-line defense. The problem of most of the location verifications is the explicit involvement of many sensors in the verification process and requirements, such as special hardware, a dedicated verifier and the trusted third party, which causes more communication and computation overhead. In this paper, we propose an efficient location verification scheme for static WSN called mutually-shared region-based location verification (MSRLV), which reduces those overheads by utilizing the implicit involvement of sensors and eliminating several requirements. In order to achieve this, we use the mutually-shared region between location claimant and verifier for the location verification. The analysis shows that MSRLV reduces communication overhead by 77% and computation overhead by 92% on average, when compared with the other location verification schemes, in a single sensor verification. In addition, simulation results for the verification of the whole network show that MSRLV can detect the malicious sensors by over 90% when sensors in the network have five or more neighbors. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

7 pages, 2240 KiB

Open AccessArticle

Single-Step Purification of Monomeric l-Selectin via Aptamer Affinity Chromatography

by Christian Kuehne^1,*, Stefanie Wedepohl²

and Jens Dernedde¹

¹ Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany

² Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany

Sensors 2017, 17(2), 226; https://doi.org/10.3390/s17020226 - 24 Jan 2017

Cited by 14 | Viewed by 6221

Abstract

l-selectin is a transmembrane receptor expressed on the surface of white blood cells and responsible for the tethering of leukocytes to vascular endothelial cells. This initial intercellular contact is the first step of the complex leukocyte adhesion cascade that ultimately permits extravasation [...] Read more.

l-selectin is a transmembrane receptor expressed on the surface of white blood cells and responsible for the tethering of leukocytes to vascular endothelial cells. This initial intercellular contact is the first step of the complex leukocyte adhesion cascade that ultimately permits extravasation of leukocytes into the surrounding tissue in case of inflammation. Here we show the binding of a soluble histidine tagged l-selectin to a recently described shortened variant of an l-selectin specific DNA aptamer with surface plasmon resonance. The high specificity of this aptamer in combination with its high binding affinity of ~12 nM, allows for a single-step protein purification from cell culture supernatants. In comparison to the well-established Ni-NTA based technology, aptamer affinity chromatography (AAC) was easier to establish, resulted in a 3.6-fold higher protein yield, and increased protein purity. Moreover, due to target specificity, the DNA aptamer facilitated binding studies directly from cell culture supernatant, a helpful characteristic to quickly monitor successful expression of biological active l-selectin. Full article

(This article belongs to the Special Issue Aptasensors 2016)

▼ Show Figures

Figure 1

26 pages, 17233 KiB

Open AccessArticle

Customization of UWB 3D-RTLS Based on the New Uncertainty Model of the AoA Ranging Technique

by Bartosz Jachimczyk^1,*, Damian Dziak² and Wlodek J. Kulesza³

¹ BetterSolutions S.A., Al. Grunwaldzka 472, 80-309 Gdansk, Poland

² Faculty of Electrical and Control Engineering, Gdansk University of Technology, G. Narutowicza 11/12, 80-233 Gdansk, Poland

³ Department of Applied Signal Processing, Blekinge Institute of Technology, 37179 Karlskrona, Sweden

Sensors 2017, 17(2), 227; https://doi.org/10.3390/s17020227 - 25 Jan 2017

Cited by 19 | Viewed by 8472

Abstract

The increased potential and effectiveness of Real-time Locating Systems (RTLSs) substantially influence their application spectrum. They are widely used, inter alia, in the industrial sector, healthcare, home care, and in logistic and security applications. The research aims to develop an analytical method to [...] Read more.

The increased potential and effectiveness of Real-time Locating Systems (RTLSs) substantially influence their application spectrum. They are widely used, inter alia, in the industrial sector, healthcare, home care, and in logistic and security applications. The research aims to develop an analytical method to customize UWB-based RTLS, in order to improve their localization performance in terms of accuracy and precision. The analytical uncertainty model of Angle of Arrival (AoA) localization in a 3D indoor space, which is the foundation of the customization concept, is established in a working environment. Additionally, a suitable angular-based 3D localization algorithm is introduced. The paper investigates the following issues: the influence of the proposed correction vector on the localization accuracy; the impact of the system’s configuration and LS’s relative deployment on the localization precision distribution map. The advantages of the method are verified by comparing them with a reference commercial RTLS localization engine. The results of simulations and physical experiments prove the value of the proposed customization method. The research confirms that the analytical uncertainty model is the valid representation of RTLS’ localization uncertainty in terms of accuracy and precision and can be useful for its performance improvement. The research shows, that the Angle of Arrival localization in a 3D indoor space applying the simple angular-based localization algorithm and correction vector improves of localization accuracy and precision in a way that the system challenges the reference hardware advanced localization engine. Moreover, the research guides the deployment of location sensors to enhance the localization precision. Full article

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

▼ Show Figures

Figure 1

23 pages, 12094 KiB

Open AccessArticle

Fusion of High Resolution Multispectral Imagery in Vulnerable Coastal and Land Ecosystems

by Edurne Ibarrola-Ulzurrun^1,2,*

, Consuelo Gonzalo-Martin²

, Javier Marcello-Ruiz¹

, Angel Garcia-Pedrero²

and Dionisio Rodriguez-Esparragon¹

¹ Instituto de Oceanografía y Cambio Global, IOCAG, Universidad Las Palmas de Gran Canaria (ULPGC), Parque Científico Tecnológico Marino de Taliarte , 35214 Telde, Spain

² Centro de Tecnología Biomédica, Universidad Politécnica de Madrid (UPM), Campus de Montegancedo, 28223 Pozuelo de Alarcón, Spain

Sensors 2017, 17(2), 228; https://doi.org/10.3390/s17020228 - 25 Jan 2017

Cited by 18 | Viewed by 5519

Abstract

Ecosystems provide a wide variety of useful resources that enhance human welfare, but these resources are declining due to climate change and anthropogenic pressure. In this work, three vulnerable ecosystems, including shrublands, coastal areas with dunes systems and areas of shallow water, are [...] Read more.

Ecosystems provide a wide variety of useful resources that enhance human welfare, but these resources are declining due to climate change and anthropogenic pressure. In this work, three vulnerable ecosystems, including shrublands, coastal areas with dunes systems and areas of shallow water, are studied. As far as these resources’ reduction is concerned, remote sensing and image processing techniques could contribute to the management of these natural resources in a practical and cost-effective way, although some improvements are needed for obtaining a higher quality of the information available. An important quality improvement is the fusion at the pixel level. Hence, the objective of this work is to assess which pansharpening technique provides the best fused image for the different types of ecosystems. After a preliminary evaluation of twelve classic and novel fusion algorithms, a total of four pansharpening algorithms was analyzed using six quality indices. The quality assessment was implemented not only for the whole set of multispectral bands, but also for the subset of spectral bands covered by the wavelength range of the panchromatic image and outside of it. A better quality result is observed in the fused image using only the bands covered by the panchromatic band range. It is important to highlight the use of these techniques not only in land and urban areas, but a novel analysis in areas of shallow water ecosystems. Although the algorithms do not show a high difference in land and coastal areas, coastal ecosystems require simpler algorithms, such as fast intensity hue saturation, whereas more heterogeneous ecosystems need advanced algorithms, as weighted wavelet ‘à trous’ through fractal dimension maps for shrublands and mixed ecosystems. Moreover, quality map analysis was carried out in order to study the fusion result in each band at the local level. Finally, to demonstrate the performance of these pansharpening techniques, advanced Object-Based (OBIA) support vector machine classification was applied, and a thematic map for the shrubland ecosystem was obtained, which corroborates wavelet ‘à trous’ through fractal dimension maps as the best fusion algorithm for this ecosystem. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

12 pages, 5093 KiB

Open AccessArticle

Hysteresis Compensation of Piezoresistive Carbon Nanotube/Polydimethylsiloxane Composite-Based Force Sensors

by Ji-Sik Kim¹ and Gi-Woo Kim^2,*

¹ School of Nano & Advanced Material Engineering, Kyungpook National University, Sang-Ju, 37224, Korea

² Department of Mechanical Engineering, Inha University, Incheon 22212, Korea

Sensors 2017, 17(2), 229; https://doi.org/10.3390/s17020229 - 24 Jan 2017

Cited by 51 | Viewed by 9623

Abstract

This paper provides a preliminary study on the hysteresis compensation of a piezoresistive silicon-based polymer composite, poly(dimethylsiloxane) dispersed with carbon nanotubes (CNTs), to demonstrate its feasibility as a conductive composite (i.e., a force-sensitive resistor) for force sensors. In this study, the potential use [...] Read more.

This paper provides a preliminary study on the hysteresis compensation of a piezoresistive silicon-based polymer composite, poly(dimethylsiloxane) dispersed with carbon nanotubes (CNTs), to demonstrate its feasibility as a conductive composite (i.e., a force-sensitive resistor) for force sensors. In this study, the potential use of the nanotube/polydimethylsiloxane (CNT/PDMS) as a force sensor is evaluated for the first time. The experimental results show that the electrical resistance of the CNT/PDMS composite changes in response to sinusoidal loading and static compressive load. The compensated output based on the Duhem hysteresis model shows a linear relationship. This simple hysteresis model can compensate for the nonlinear frequency-dependent hysteresis phenomenon when a dynamic sinusoidal force input is applied. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

13 pages, 2051 KiB

Open AccessArticle

Wideband Direction of Arrival Estimation in the Presence of Unknown Mutual Coupling

by Weixing Li^*, Yue Zhang, Jianzhi Lin, Rui Guo and Zengping Chen

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

Sensors 2017, 17(2), 230; https://doi.org/10.3390/s17020230 - 6 Feb 2017

Cited by 9 | Viewed by 4441

Abstract

This paper investigates a subarray based algorithm for direction of arrival (DOA) estimation of wideband uniform linear array (ULA), under the presence of frequency-dependent mutual coupling effects. Based on the Toeplitz structure of mutual coupling matrices, the whole array is divided into the [...] Read more.

This paper investigates a subarray based algorithm for direction of arrival (DOA) estimation of wideband uniform linear array (ULA), under the presence of frequency-dependent mutual coupling effects. Based on the Toeplitz structure of mutual coupling matrices, the whole array is divided into the middle subarray and the auxiliary subarray. Then two-sided correlation transformation is applied to the correlation matrix of the middle subarray instead of the whole array. In this way, the mutual coupling effects can be eliminated. Finally, the multiple signal classification (MUSIC) method is utilized to derive the DOAs. For the condition when the blind angles exist, we refine DOA estimation by using a simple approach based on the frequency-dependent mutual coupling matrixes (MCMs). The proposed method can achieve high estimation accuracy without any calibration sources. It has a low computational complexity because iterative processing is not required. Simulation results validate the effectiveness and feasibility of the proposed algorithm. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 3705 KiB

Open AccessArticle

Emission Flux Measurement Error with a Mobile DOAS System and Application to NO_x Flux Observations

by Fengcheng Wu¹, Ang Li^1,*, Pinhua Xie^1,2,3,*, Hao Chen¹, Zhaokun Hu¹, Qiong Zhang¹, Jianguo Liu¹

and Wenqing Liu¹

¹ Key Laboratory of Environmental Optical and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China

² Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China

³ School of Environmental Science and Optoeclectronic Technology, University of Science and Technology of China, Hefei 230026, China

Sensors 2017, 17(2), 231; https://doi.org/10.3390/s17020231 - 25 Jan 2017

Cited by 22 | Viewed by 5963

Abstract

Mobile differential optical absorption spectroscopy (mobile DOAS) is an optical remote sensing method that can rapidly measure trace gas emission flux from air pollution sources (such as power plants, industrial areas, and cities) in real time. Generally, mobile DOAS is influenced by wind, [...] Read more.

Mobile differential optical absorption spectroscopy (mobile DOAS) is an optical remote sensing method that can rapidly measure trace gas emission flux from air pollution sources (such as power plants, industrial areas, and cities) in real time. Generally, mobile DOAS is influenced by wind, drive velocity, and other factors, especially in the usage of wind field when the emission flux in a mobile DOAS system is observed. This paper presents a detailed error analysis and NOx emission with mobile DOAS system from a power plant in Shijiazhuang city, China. Comparison of the SO₂ emission flux from mobile DOAS observations with continuous emission monitoring system (CEMS) under different drive speeds and wind fields revealed that the optimal drive velocity is 30–40 km/h, and the wind field at plume height is selected when mobile DOAS observations are performed. In addition, the total errors of SO₂ and NO₂ emissions with mobile DOAS measurements are 32% and 30%, respectively, combined with the analysis of the uncertainties of column density, wind field, and drive velocity. Furthermore, the NO_x emission of 0.15 ± 0.06 kg/s from the power plant is estimated, which is in good agreement with that from CEMS observations of 0.17 ± 0.07 kg/s. This study has significantly contributed to the measurement of the mobile DOAS system on emission from air pollution sources, thus improving estimation accuracy. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

▼ Show Figures

Figure 1

22 pages, 735 KiB

Open AccessArticle

Capacity-Delay Trade-Off in Collaborative Hybrid Ad-Hoc Networks with Coverage Sensing

by Lingyu Chen¹, Wenbin Luo¹, Chen Liu¹, Xuemin Hong^1,2,* and Jianghong Shi^1,2

¹ Department of Communications Engineering, School of Information Science and Technology, Xiamen University, Xiamen 361005, Fujian, China

² Key Laboratory of Underwater Acoustic Communication and Marine Information Technology, Ministry of Education, Xiamen University, Xiamen 361005, Fujian, China

Sensors 2017, 17(2), 232; https://doi.org/10.3390/s17020232 - 26 Jan 2017

Cited by 4 | Viewed by 5294

Abstract

The integration of ad hoc device-to-device (D2D) communications and open-access small cells can result in a networking paradigm called hybrid the ad hoc network, which is particularly promising in delivering delay-tolerant data. The capacity-delay performance of hybrid ad hoc networks has been studied [...] Read more.

The integration of ad hoc device-to-device (D2D) communications and open-access small cells can result in a networking paradigm called hybrid the ad hoc network, which is particularly promising in delivering delay-tolerant data. The capacity-delay performance of hybrid ad hoc networks has been studied extensively under a popular framework called scaling law analysis. These studies, however, do not take into account aspects of interference accumulation and queueing delay and, therefore, may lead to over-optimistic results. Moreover, focusing on the average measures, existing works fail to give finer-grained insights into the distribution of delays. This paper proposes an alternative analytical framework based on queueing theoretic models and physical interference models. We apply this framework to study the capacity-delay performance of a collaborative cellular D2D network with coverage sensing and two-hop relay. The new framework allows us to fully characterize the delay distribution in the transform domain and pinpoint the impacts of coverage sensing, user and base station densities, transmit power, user mobility and packet size on the capacity-delay trade-off. We show that under the condition of queueing equilibrium, the maximum throughput capacity per device saturates to an upper bound of 0.7239

λ_{b} / λ_{u}

bits/s/Hz, where

λ_{b}

and

λ_{u}

are the densities of base stations and mobile users, respectively. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

▼ Show Figures

Figure 1

24 pages, 18936 KiB

Open AccessArticle

A Denoising Scheme for Randomly Clustered Noise Removal in ICCD Sensing Image

by Fei Wang, Yibin Wang, Meng Yang^*, Xuetao Zhang and Nanning Zheng

Institute of Artificial Intelligence and Robotics, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(2), 233; https://doi.org/10.3390/s17020233 - 26 Jan 2017

Cited by 15 | Viewed by 6105

Abstract

An Intensified Charge-Coupled Device (ICCD) image is captured by the ICCD image sensor in extremely low-light conditions. Its noise has two distinctive characteristics. (a) Different from the independent identically distributed (i.i.d.) noise in natural image, the noise in the ICCD sensing [...] Read more.

An Intensified Charge-Coupled Device (ICCD) image is captured by the ICCD image sensor in extremely low-light conditions. Its noise has two distinctive characteristics. (a) Different from the independent identically distributed (i.i.d.) noise in natural image, the noise in the ICCD sensing image is spatially clustered, which induces unexpected structure information; (b) The pattern of the clustered noise is formed randomly. In this paper, we propose a denoising scheme to remove the randomly clustered noise in the ICCD sensing image. First, we decompose the image into non-overlapped patches and classify them into flat patches and structure patches according to if real structure information is included. Then, two denoising algorithms are designed for them, respectively. For each flat patch, we simulate multiple similar patches for it in pseudo-time domain and remove its noise by averaging all the simulated patches, considering that the structure information induced by the noise varies randomly over time. For each structure patch, we design a structure-preserved sparse coding algorithm to reconstruct the real structure information. It reconstructs each patch by describing it as a weighted summation of its neighboring patches and incorporating the weights into the sparse representation of the current patch. Based on all the reconstructed patches, we generate a reconstructed image. After that, we repeat the whole process by changing relevant parameters, considering that blocking artifacts exist in a single reconstructed image. Finally, we obtain the reconstructed image by merging all the generated images into one. Experiments are conducted on an ICCD sensing image dataset, which verifies its subjective performance in removing the randomly clustered noise and preserving the real structure information in the ICCD sensing image. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Graphical abstract

17 pages, 788 KiB

Open AccessArticle

Set-Based Discriminative Measure for Electrocardiogram Beat Classification

by Wei Li^1,*, Jianqing Li^1,2 and Qin Qin¹

¹ School of Instrument Science and Engineering, Southeast University, 2 Sipailou, Nanjing 210096, China

² School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Avenue, Nanjing 211166, China

Sensors 2017, 17(2), 234; https://doi.org/10.3390/s17020234 - 25 Jan 2017

Cited by 11 | Viewed by 5593

Abstract

Computer aided diagnosis systems can help to reduce the high mortality rate among cardiac patients. Automatical classification of electrocardiogram (ECG) beats plays an important role in such systems, but this issue is challenging because of the complexities of ECG signals. In literature, feature [...] Read more.

Computer aided diagnosis systems can help to reduce the high mortality rate among cardiac patients. Automatical classification of electrocardiogram (ECG) beats plays an important role in such systems, but this issue is challenging because of the complexities of ECG signals. In literature, feature designing has been broadly-studied. However, such methodology is inevitably limited by the heuristics of hand-crafting process and the challenge of signals themselves. To address it, we treat the problem of ECG beat classification from the metric and measurement perspective. We propose a novel approach, named “Set-Based Discriminative Measure”, which first learns a discriminative metric space to ensure that intra-class distances are smaller than inter-class distances for ECG features in a global way, and then measures a new set-based dissimilarity in such learned space to cope with the local variation of samples. Experimental results have demonstrated the advantage of this approach in terms of effectiveness, robustness, and flexibility based on ECG beats from the MIT-BIH Arrhythmia Database. Full article

(This article belongs to the Section State-of-the-Art Sensors Technologies)

▼ Show Figures

Figure 1

12 pages, 3725 KiB

Open AccessArticle

Earthquake Damage Visualization (EDV) Technique for the Rapid Detection of Earthquake-Induced Damages Using SAR Data

by Ram C. Sharma^1,2,*, Ryutaro Tateishi¹, Keitarou Hara², Hoan Thanh Nguyen³, Saeid Gharechelou^1,4 and Luong Viet Nguyen⁵

¹ Center for Environmental Remote Sensing (CEReS), Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

² Department of Informatics, Tokyo University of Information Sciences, 4-1 Onaridai, Wakaba-ku, Chiba 265-8501, Japan

³ Institute of Geography, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Dist., Hanoi 10000, Vietnam

⁴ Department of Civil Engineering, Shahrood University of Technology, Shahrood 3619995161, Iran

⁵ Space Technology Institute, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Dist., Hanoi 10000, Vietnam

Sensors 2017, 17(2), 235; https://doi.org/10.3390/s17020235 - 27 Jan 2017

Cited by 40 | Viewed by 9455

Abstract

The damage of buildings and manmade structures, where most of human activities occur, is the major cause of casualties of from earthquakes. In this paper, an improved technique, Earthquake Damage Visualization (EDV) is presented for the rapid detection of earthquake damage using the [...] Read more.

The damage of buildings and manmade structures, where most of human activities occur, is the major cause of casualties of from earthquakes. In this paper, an improved technique, Earthquake Damage Visualization (EDV) is presented for the rapid detection of earthquake damage using the Synthetic Aperture Radar (SAR) data. The EDV is based on the pre-seismic and co-seismic coherence change method. The normalized difference between the pre-seismic and co-seismic coherences, and vice versa, are used to calculate the forward (from pre-seismic to co-seismic) and backward (from co-seismic to pre-seismic) change parameters, respectively. The backward change parameter is added to visualize the retrospective changes caused by factors other than the earthquake. The third change-free parameter uses the average values of the pre-seismic and co-seismic coherence maps. These three change parameters were ultimately merged into the EDV as an RGB (Red, Green, and Blue) composite imagery. The EDV could visualize the earthquake damage efficiently using Horizontal transmit and Horizontal receive (HH), and Horizontal transmit and Vertical receive (HV) polarizations data from the Advanced Land Observing Satellite-2 (ALOS-2). Its performance was evaluated in the Kathmandu Valley, which was hit severely by the 2015 Nepal Earthquake. The cross-validation results showed that the EDV is more sensitive to the damaged buildings than the existing method. The EDV could be used for building damage detection in other earthquakes as well. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

▼ Show Figures

Figure 1

10 pages, 3328 KiB

Open AccessArticle

Fabrication of Annealed Gold Nanostructures on Pre-Treated Glow-Discharge Cleaned Glasses and Their Used for Localized Surface Plasmon Resonance (LSPR) and Surface Enhanced Raman Spectroscopy (SERS) Detection of Adsorbed (Bio)molecules

by Rodica Elena Ionescu^1,*

, Ece Neslihan Aybeke², Eric Bourillot², Yvon Lacroute², Eric Lesniewska²

, Pierre-Michel Adam¹ and Jean-Louis Bijeon¹

¹ Laboratory of Nanotechnology, Instrumentation and Optics, UMR-CNRS 6281, Institute Charles Delaunay, University of Champagne, University of Technology of Troyes, 12 Rue Marie Curie CS 42060, 10004 Troyes CEDEX, France

² Laboratory Interdisciplinaire Carnot de Bourgogne (ICB), UMR-CNRS 6303, University of Bourgogne Franche-Comte, 9 Avenue Alain Savary, 21078 Dijon CEDEX, France

Sensors 2017, 17(2), 236; https://doi.org/10.3390/s17020236 - 26 Jan 2017

Cited by 18 | Viewed by 7315

Abstract

Metallic nanoparticles are considered as active supports in the development of specific chemical or biological biosensors. Well-organized nanoparticles can be prepared either through expensive (e.g., electron beam lithography) or inexpensive (e.g., thermal synthesis) approaches where different shapes of nanoparticles are easily obtained over [...] Read more.

Metallic nanoparticles are considered as active supports in the development of specific chemical or biological biosensors. Well-organized nanoparticles can be prepared either through expensive (e.g., electron beam lithography) or inexpensive (e.g., thermal synthesis) approaches where different shapes of nanoparticles are easily obtained over large solid surfaces. Herein, the authors propose a low-cost thermal synthesis of active plasmonic nanostructures on thin gold layers modified glass supports after 1 h holding on a hot plate (~350 °C). The resulted annealed nanoparticles proved a good reproducibility of localized surface plasmon resonance (LSPR) and surface enhanced Raman spectroscopy (SERS) optical responses and where used for the detection of low concentrations of two model (bio)chemical molecules, namely the human cytochrome b5 (Cyt-b5) and trans-1,2-bis(4-pyridyl)ethylene (BPE). Full article

(This article belongs to the Special Issue Last Advances in Nanoplasmonics Biosensors)

▼ Show Figures

Figure 1

19 pages, 802 KiB

Open AccessArticle

Practical Considerations in the Implementation of Collaborative Beamforming on Wireless Sensor Networks

by Santiago Felici-Castell^1,*

, Enrique A. Navarro^1,2

, Juan J. Pérez-Solano¹

, Jaume Segura-García¹

and Miguel García-Pineda¹

¹ Departament de Informàtica, Escola Tècnica Superior d’Enginyeria, Universitat de València, Avd. de la Universidad S/N, 46100 Burjassot, Spain

² Institut de Robòtica, Universitat de València, Catedrático José Beltran, 2, 46980 Paterna, Spain

Sensors 2017, 17(2), 237; https://doi.org/10.3390/s17020237 - 26 Jan 2017

Cited by 23 | Viewed by 6611

Abstract

Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These motes have their own power supply, processing unit, sensors and wireless communications However with many constraints, such as limited energy, bandwidth and computational capabilities. In these networks, at [...] Read more.

Wireless Sensor Networks (WSNs) are composed of spatially distributed autonomous sensor devices, named motes. These motes have their own power supply, processing unit, sensors and wireless communications However with many constraints, such as limited energy, bandwidth and computational capabilities. In these networks, at least one mote called a sink, acts as a gateway to connect with other networks. These sensor networks run monitoring applications and then the data gathered by these motes needs to be retrieved by the sink. When this sink is located in the far field, there have been many proposals in the literature based on Collaborative Beamforming (CB), also known as Distributed or Cooperative Beamforming, for these long range communications to reach the sink. In this paper, we conduct a thorough study of the related work and analyze the requirements to do CB. In order to implement these communications in real scenarios, we will consider if these requirements and the assumptions made are feasible from the point of view of commercial motes and their constraints. In addition, we will go a step further and will consider different alternatives, by relaxing these requirements, trying to find feasible assumptions to carry out these types of communications with commercial motes. This research considers the nonavailability of a central clock that synchronizes all motes in the WSN, and all motes have identical hardware. This is a feasibility study to do CB on WSN, using a simulated scenario with randomized delays obtained from experimental data from commercial motes. Full article

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

▼ Show Figures

Figure 1

17 pages, 4142 KiB

Open AccessArticle

Combining CHAMP and Swarm Satellite Data to Invert the Lithospheric Magnetic Field in the Tibetan Plateau

by Yaodong Qiu¹, Zhengtao Wang¹, Weiping Jiang^2,*, Bingbing Zhang¹

, Fupeng Li¹ and Fei Guo¹

¹ School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

² GNSS Research Center of Wuhan University, 129 Luoyu Road, Wuhan 430079, China

Sensors 2017, 17(2), 238; https://doi.org/10.3390/s17020238 - 26 Jan 2017

Cited by 12 | Viewed by 6735

Abstract

CHAMP and Swarm satellite magnetic data are combined to establish the lithospheric magnetic field over the Tibetan Plateau at satellite altitude by using zonal revised spherical cap harmonic analysis (R-SCHA). These data are integrated with geological structures data to analyze the relationship between [...] Read more.

CHAMP and Swarm satellite magnetic data are combined to establish the lithospheric magnetic field over the Tibetan Plateau at satellite altitude by using zonal revised spherical cap harmonic analysis (R-SCHA). These data are integrated with geological structures data to analyze the relationship between magnetic anomaly signals and large-scale geological tectonic over the Tibetan Plateau and to explore the active tectonic region based on the angle of the magnetic anomaly. Results show that the model fitting error is small for a layer 250–500 km high, and the RMSE of the horizontal and radial geomagnetic components is better than 0.3 nT. The proposed model can accurately describe medium- to long-scale lithospheric magnetic anomalies. Analysis indicates that a negative magnetic anomaly in the Tibetan Plateau significantly differs with a positive magnetic anomaly in the surrounding area, and the boundary of the positive and negative regions is generally consistent with the geological tectonic boundary in the plateau region. Significant differences exist between the basement structures of the hinterland of the plateau and the surrounding area. The magnetic anomaly in the Central and Western Tibetan Plateau shows an east–west trend, which is identical to the direction of the geological structures. The magnetic anomaly in the eastern part is arc-shaped and extends along the northeast direction. Its direction is significantly different from the trend of the geological structures. The strongest negative anomaly is located in the Himalaya block, with a central strength of up to −9 nT at a height of 300 km. The presence of a strong negative anomaly implies that the Curie isotherm in this area is relatively shallow and deep geological tectonic activity may exist. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

▼ Show Figures

Figure 1

26 pages, 6906 KiB

Open AccessArticle

Performance Enhancement of a USV INS/CNS/DVL Integration Navigation System Based on an Adaptive Information Sharing Factor Federated Filter

by Qiuying Wang, Xufei Cui, Yibing Li^* and Fang Ye

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

Sensors 2017, 17(2), 239; https://doi.org/10.3390/s17020239 - 3 Feb 2017

Cited by 66 | Viewed by 6481

Abstract

To improve the ability of autonomous navigation for Unmanned Surface Vehicles (USVs), multi-sensor integrated navigation based on Inertial Navigation System (INS), Celestial Navigation System (CNS) and Doppler Velocity Log (DVL) is proposed. The CNS position and the DVL velocity are introduced as the [...] Read more.

To improve the ability of autonomous navigation for Unmanned Surface Vehicles (USVs), multi-sensor integrated navigation based on Inertial Navigation System (INS), Celestial Navigation System (CNS) and Doppler Velocity Log (DVL) is proposed. The CNS position and the DVL velocity are introduced as the reference information to correct the INS divergence error. The autonomy of the integrated system based on INS/CNS/DVL is much better compared with the integration based on INS/GNSS alone. However, the accuracy of DVL velocity and CNS position are decreased by the measurement noise of DVL and bad weather, respectively. Hence, the INS divergence error cannot be estimated and corrected by the reference information. To resolve the problem, the Adaptive Information Sharing Factor Federated Filter (AISFF) is introduced to fuse data. The information sharing factor of the Federated Filter is adaptively adjusted to maintaining multiple component solutions usable as back-ups, which can improve the reliability of overall system. The effectiveness of this approach is demonstrated by simulation and experiment, the results show that for the INS/CNS/DVL integrated system, when the DVL velocity accuracy is decreased and the CNS cannot work under bad weather conditions, the INS/CNS/DVL integrated system can operate stably based on the AISFF method. Full article

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

▼ Show Figures

Figure 1

17 pages, 3997 KiB

Open AccessArticle

Geometric Positioning for Satellite Imagery without Ground Control Points by Exploiting Repeated Observation

by Zhenling Ma^1,*,†

, Xiaoliang Wu², Li Yan³ and Zhenliang Xu⁴

¹ Shanghai Engineering Research Center of Hadal Science and Technology, Research Center for Ocean Mapping and Applications, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China

² Commonwealth Scientific and Industrial Research Organisation (CSIRO) DATA61, Western Australia 6014, Australia

³ School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China

⁴ China Center for Resources Satellite Data and Application, Beijing 100094, China

^† Current address: No. 999 Huchenghuan Road, Pudong District, Shanghai 201306, China.

Sensors 2017, 17(2), 240; https://doi.org/10.3390/s17020240 - 26 Jan 2017

Cited by 12 | Viewed by 6093

Abstract

With the development of space technology and the performance of remote sensors, high-resolution satellites are continuously launched by countries around the world. Due to high efficiency, large coverage and not being limited by the spatial regulation, satellite imagery becomes one of the important [...] Read more.

With the development of space technology and the performance of remote sensors, high-resolution satellites are continuously launched by countries around the world. Due to high efficiency, large coverage and not being limited by the spatial regulation, satellite imagery becomes one of the important means to acquire geospatial information. This paper explores geometric processing using satellite imagery without ground control points (GCPs). The outcome of spatial triangulation is introduced for geo-positioning as repeated observation. Results from combining block adjustment with non-oriented new images indicate the feasibility of geometric positioning with the repeated observation. GCPs are a must when high accuracy is demanded in conventional block adjustment; the accuracy of direct georeferencing with repeated observation without GCPs is superior to conventional forward intersection and even approximate to conventional block adjustment with GCPs. The conclusion is drawn that taking the existing oriented imagery as repeated observation enhances the effective utilization of previous spatial triangulation achievement, which makes the breakthrough for repeated observation to improve accuracy by increasing the base-height ratio and redundant observation. Georeferencing tests using data from multiple sensors and platforms with the repeated observation will be carried out in the follow-up research. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

▼ Show Figures

Figure 1

25 pages, 4180 KiB

Open AccessArticle

IEEE 802.15.4 Frame Aggregation Enhancement to Provide High Performance in Life-Critical Patient Monitoring Systems

by Muhammad Sajjad Akbar¹, Hongnian Yu^1,*

and Shuang Cang²

¹ Faculty of Science and Technology, Bournemouth University, Poole BH12 5BB, UK

² Faculty of Management, Bournemouth University, Poole BH12 5BB, UK

Sensors 2017, 17(2), 241; https://doi.org/10.3390/s17020241 - 28 Jan 2017

Cited by 24 | Viewed by 7253

Abstract

In wireless body area sensor networks (WBASNs), Quality of Service (QoS) provision for patient monitoring systems in terms of time-critical deadlines, high throughput and energy efficiency is a challenging task. The periodic data from these systems generates a large number of small packets [...] Read more.

In wireless body area sensor networks (WBASNs), Quality of Service (QoS) provision for patient monitoring systems in terms of time-critical deadlines, high throughput and energy efficiency is a challenging task. The periodic data from these systems generates a large number of small packets in a short time period which needs an efficient channel access mechanism. The IEEE 802.15.4 standard is recommended for low power devices and widely used for many wireless sensor networks applications. It provides a hybrid channel access mechanism at the Media Access Control (MAC) layer which plays a key role in overall successful transmission in WBASNs. There are many WBASN’s MAC protocols that use this hybrid channel access mechanism in variety of sensor applications. However, these protocols are less efficient for patient monitoring systems where life critical data requires limited delay, high throughput and energy efficient communication simultaneously. To address these issues, this paper proposes a frame aggregation scheme by using the aggregated-MAC protocol data unit (A-MPDU) which works with the IEEE 802.15.4 MAC layer. To implement the scheme accurately, we develop a traffic patterns analysis mechanism to understand the requirements of the sensor nodes in patient monitoring systems, then model the channel access to find the performance gap on the basis of obtained requirements, finally propose the design based on the needs of patient monitoring systems. The mechanism is initially verified using numerical modelling and then simulation is conducted using NS2.29, Castalia 3.2 and OMNeT++. The proposed scheme provides the optimal performance considering the required QoS. Full article

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

▼ Show Figures

Figure 1

16 pages, 2405 KiB

Open AccessArticle

Structure-From-Motion in 3D Space Using 2D Lidars

by Dong-Geol Choi¹, Yunsu Bok^2,*, Jun-Sik Kim³

, Inwook Shim¹ and In So Kweon¹

¹ Robotics and Computer Vision Lab, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea

² Broadcasting Media Research Lab, Electronics and Telecommunications Research Institute, 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Korea

³ Center for Robotics Research, Korea Institute of Science and Technology, Seoul 02792, Korea

Sensors 2017, 17(2), 242; https://doi.org/10.3390/s17020242 - 3 Feb 2017

Cited by 13 | Viewed by 5397

Abstract

This paper presents a novel structure-from-motion methodology using 2D lidars (Light Detection And Ranging). In 3D space, 2D lidars do not provide sufficient information for pose estimation. For this reason, additional sensors have been used along with the lidar measurement. In this paper, [...] Read more.

This paper presents a novel structure-from-motion methodology using 2D lidars (Light Detection And Ranging). In 3D space, 2D lidars do not provide sufficient information for pose estimation. For this reason, additional sensors have been used along with the lidar measurement. In this paper, we use a sensor system that consists of only 2D lidars, without any additional sensors. We propose a new method of estimating both the 6D pose of the system and the surrounding 3D structures. We compute the pose of the system using line segments of scan data and their corresponding planes. After discarding the outliers, both the pose and the 3D structures are refined via nonlinear optimization. Experiments with both synthetic and real data show the accuracy and robustness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

24 pages, 17782 KiB

Open AccessArticle

A Quantitative Comparison of Calibration Methods for RGB-D Sensors Using Different Technologies

by Víctor Villena-Martínez^*, Andrés Fuster-Guilló, Jorge Azorín-López, Marcelo Saval-Calvo, Jeronimo Mora-Pascual, Jose Garcia-Rodriguez and Alberto Garcia-Garcia

Department of Computer Technology, University of Alicante, Carretera San Vicente s/n, San Vicente del Raspeig 03690, Alicante, Spain

Sensors 2017, 17(2), 243; https://doi.org/10.3390/s17020243 - 27 Jan 2017

Cited by 22 | Viewed by 9514

Abstract

RGB-D (Red Green Blue and Depth) sensors are devices that can provide color and depth information from a scene at the same time. Recently, they have been widely used in many solutions due to their commercial growth from the entertainment market [...] Read more.

RGB-D (Red Green Blue and Depth) sensors are devices that can provide color and depth information from a scene at the same time. Recently, they have been widely used in many solutions due to their commercial growth from the entertainment market to many diverse areas (e.g., robotics, CAD, etc.). In the research community, these devices have had good uptake due to their acceptable levelofaccuracyformanyapplicationsandtheirlowcost,butinsomecases,theyworkatthelimitof their sensitivity, near to the minimum feature size that can be perceived. For this reason, calibration processes are critical in order to increase their accuracy and enable them to meet the requirements of such kinds of applications. To the best of our knowledge, there is not a comparative study of calibration algorithms evaluating its results in multiple RGB-D sensors. Speciﬁcally, in this paper, a comparison of the three most used calibration methods have been applied to three different RGB-D sensors based on structured light and time-of-ﬂight. The comparison of methods has been carried out by a set of experiments to evaluate the accuracy of depth measurements. Additionally, an object reconstruction application has been used as example of an application for which the sensor works at the limit of its sensitivity. The obtained results of reconstruction have been evaluated through visual inspection and quantitative measurements. Full article

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

▼ Show Figures

Figure 1

14 pages, 1393 KiB

Open AccessArticle

Application of the PAMONO-Sensor for Quantiﬁcation of Microvesicles and Determination of Nano-Particle Size Distribution

by Victoria Shpacovitch^1,*, Irina Sidorenko², Jan Eric Lenssen³, Vladimir Temchura⁴, Frank Weichert³

, Heinrich Müller³, Klaus Überla⁴, Alexander Zybin¹, Alexander Schramm⁵

and Roland Hergenröder¹

¹ Leibniz Institute für Analytische Wissenschaften, ISAS e.V., Bunsen-Kirchhoff-Straße 11, 44139 Dortmund, Germany

² MIVITEC GmbH, Wamslerstraße.4, 81829 Munich, Germany

³ Department of Computer Science VII, TU Dortmund University, Otto-Hahn-Straße. 16, 44227Dortmund,Germany

⁴ Institute of Clinical and Molecular Virology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany

⁵ Children’s Hospital, Oncology Laboratory, University Clinic Essen, Hufelandstraße. 55, 45122 Essen, Germany

Sensors 2017, 17(2), 244; https://doi.org/10.3390/s17020244 - 27 Jan 2017

Cited by 27 | Viewed by 7906

Abstract

The PAMONO-sensor (plasmon assisted microscopy of nano-objects) demonstrated an ability to detect and quantify individual viruses and virus-like particles. However, another group of biological vesicles—microvesicles (100–1000 nm)—also attracts growing interest as biomarkers of different pathologies and needs development of novel techniques for characterization. [...] Read more.

The PAMONO-sensor (plasmon assisted microscopy of nano-objects) demonstrated an ability to detect and quantify individual viruses and virus-like particles. However, another group of biological vesicles—microvesicles (100–1000 nm)—also attracts growing interest as biomarkers of different pathologies and needs development of novel techniques for characterization. This work shows the applicability of a PAMONO-sensor for selective detection of microvesicles in aquatic samples. The sensor permits comparison of relative concentrations of microvesicles between samples. We also study a possibility of repeated use of a sensor chip after elution of the microvesicle capturing layer. Moreover, we improve the detection features of the PAMONO-sensor. The detection process utilizes novel machine learning techniques on the sensor image data to estimate particle size distributions of nano-particles in polydisperse samples. Altogether, our ﬁndings expand analytical features and the application ﬁeld of the PAMONO-sensor. They can also serve for a maturation of diagnostic tools based on the PAMONO-sensor platform. Full article

(This article belongs to the Special Issue Last Advances in Nanoplasmonics Biosensors)

▼ Show Figures

Figure 1

12 pages, 2371 KiB

Open AccessArticle

Trust-Based Cooperative Social System Applied to a Carpooling Platform for Smartphones

by Cándido Caballero-Gil^1,*, Pino Caballero-Gil¹

, Jezabel Molina-Gil¹, Francisco Martín-Fernández² and Vincenzo Loia³

¹ Departament of Computer Engineering and Systems, University of La Laguna, 38271 Tenerife, Spain

² IBM Research, 38271 Tenerife, Spain

³ Dipartimento di Scienze Aziendali—Management & Innovation Systems/DISA-MIS, University of Salerno, 84084 Fisciano, Italy

Sensors 2017, 17(2), 245; https://doi.org/10.3390/s17020245 - 27 Jan 2017

Cited by 14 | Viewed by 7946

Abstract

One of the worst trafﬁc problems today is the existence of huge trafﬁc jams in almost any big city, produced by the large number of commuters using private cars. This problem has led to an increase in research on the optimization of vehicle [...] Read more.

One of the worst trafﬁc problems today is the existence of huge trafﬁc jams in almost any big city, produced by the large number of commuters using private cars. This problem has led to an increase in research on the optimization of vehicle occupancy in urban areas as this would help to solve the problem that most cars are occupied by single passengers. The solution of sharing the available seats in cars, known as carpooling, is already available in major cities around the world. However, carpooling is still not considered a safe and reliable solution for many users. With the widespread use of mobile technology and social networks, it is possible to create a trust-based platform to promote carpooling through a convenient, fast and secure system. The main objective of this work is the design and implementation of a carpool system that improves some important aspects of previous systems, focusing on trust between users, and on the security of the system. The proposed system guarantees user privacy and measures trust levels through a new reputation algorithm. In addition to this, the proposal has been developed as a mobile application for devices using the Android Open Source Project. Full article

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

▼ Show Figures

Figure 1

5 pages, 1085 KiB

Open AccessEditorial

Why Using Molecularly Imprinted Polymers in Connection to Biosensors?

by Bo Mattiasson^1,2,* and Gizem Ertürk^1,2

¹ CapSenze Biosystems AB, Scheelevägen 22, 22363 Lund, Sweden

² Department of Biotechnology, Lund University, Box 117, 221 00 Lund, Sweden

Sensors 2017, 17(2), 246; https://doi.org/10.3390/s17020246 - 27 Jan 2017

Cited by 5 | Viewed by 4329

Abstract

The area of biosensor-oriented research has grown rapidly during recent years. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

▼ Show Figures

Figure 1

15 pages, 4808 KiB

Open AccessArticle

A Novel Method for Separating and Locating Multiple Partial Discharge Sources in a Substation

by Pengfei Li¹, Wenjun Zhou¹, Shuai Yang^1,*, Yushun Liu¹

, Yan Tian² and Yong Wang²

¹ School of Electrical Engineering, Wuhan University, No.299, Bayi Road, Wuhan 430072, China

² Guangzhou Power Supply Bureau Co. Ltd., No.38, Huangshidong Road, Guangzhou 510620, China

Sensors 2017, 17(2), 247; https://doi.org/10.3390/s17020247 - 27 Jan 2017

Cited by 12 | Viewed by 4522

Abstract

To separate and locate multi-partial discharge (PD) sources in a substation, the use of spectrum differences of ultra-high frequency signals radiated from various sources as characteristic parameters has been previously reported. However, the separation success rate was poor when signal-to-noise ratio was low, [...] Read more.

To separate and locate multi-partial discharge (PD) sources in a substation, the use of spectrum differences of ultra-high frequency signals radiated from various sources as characteristic parameters has been previously reported. However, the separation success rate was poor when signal-to-noise ratio was low, and the localization result was a coordinate on two-dimensional plane. In this paper, a novel method is proposed to improve the separation rate and the localization accuracy. A directional measuring platform is built using two directional antennas. The time delay (TD) of the signals captured by the antennas is calculated, and TD sequences are obtained by rotating the platform at different angles. The sequences are separated with the TD distribution feature, and the directions of the multi-PD sources are calculated. The PD sources are located by directions using the error probability method. To verify the method, a simulated model with three PD sources was established by XFdtd. Simulation results show that the separation rate is increased from 71% to 95% compared with the previous method, and an accurate three-dimensional localization result was obtained. A field test with two PD sources was carried out, and the sources were separated and located accurately by the proposed method. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

20 pages, 4733 KiB

Open AccessArticle

Ultrafast Fiber Bragg Grating Interrogation for Sensing in Detonation and Shock Wave Experiments

by George Rodriguez^1,*

and Steve M. Gilbertson²

¹ Los Alamos National Laboratory, Laboratory for Ultrafast Materials and Optical Science, MS K771, Los Alamos, NM 87545, USA

² Los Alamos National Laboratory, DARHT Experiments and Diagnostics, MS P940, Los Alamos, NM 87545, USA

Sensors 2017, 17(2), 248; https://doi.org/10.3390/s17020248 - 27 Jan 2017

Cited by 23 | Viewed by 6949

Abstract

Chirped ﬁber Bragg grating (CFBG) sensors coupled to high speed interrogation systems are described as robust diagnostic approaches to monitoring shock wave and detonation front propagation tracking events for use in high energy density shock physics applications. Taking advantage of the linear distributed [...] Read more.

Chirped ﬁber Bragg grating (CFBG) sensors coupled to high speed interrogation systems are described as robust diagnostic approaches to monitoring shock wave and detonation front propagation tracking events for use in high energy density shock physics applications. Taking advantage of the linear distributed spatial encoding of the spectral band in single-mode CFBGs, embedded ﬁber systems and associated photonic interrogation methodologies are shown as an effective approach to sensing shock and detonation-driven loading processes along the CFBG length. Two approaches, one that detects spectral changes in the integrated spectrum of the CFBG and another coherent pulse interrogation approach that fully resolves its spectral response, shows that 100-MHz–1-GHz interrogation rates are possible with spatial resolution along the CFBG in the 50 µm to sub-millimeter range depending on the combination of CFBG parameters (i.e., length, chirp rate, spectrum) and interrogator design speciﬁcs. Results from several dynamic tests are used to demonstrate the performance of these high speed systems for shock and detonation propagation tracking under strong and weak shock pressure loading: (1) linear detonation front tracking in the plastic bonded explosive (PBX) PBX-9501; (2) tracking of radial decaying shock with crossover to non-destructive CFBG response; (3) shock wave tracking along an aluminum cylinder wall under weak loading accompanied by dynamic strain effects in the CFBG sensor. Full article

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

▼ Show Figures

Figure 1

35 pages, 7130 KiB

Open AccessArticle

Superframe Duration Allocation Schemes to Improve the Throughput of Cluster-Tree Wireless Sensor Networks

by Erico Leão^1,2,*

, Carlos Montez³

, Ricardo Moraes⁴, Paulo Portugal¹ and Francisco Vasques¹

¹ INEGI/INESC-TEC, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal

² Department of Computing, Federal University of Piauí, 64049-550 Teresina, Brazil

³ Department of Automation and Systems, Federal University of Santa Catarina, 88040-900 Florianópolis, Brazil

⁴ Department of Computing, Federal University of Santa Catarina, 88905-120 Araranguá, Brazil

Sensors 2017, 17(2), 249; https://doi.org/10.3390/s17020249 - 27 Jan 2017

Cited by 20 | Viewed by 6228

Abstract

The use of Wireless Sensor Network (WSN) technologies is an attractive option to support wide-scale monitoring applications, such as the ones that can be found in precision agriculture, environmental monitoring and industrial automation. The IEEE 802.15.4/ZigBee cluster-tree topology is a suitable topology to [...] Read more.

The use of Wireless Sensor Network (WSN) technologies is an attractive option to support wide-scale monitoring applications, such as the ones that can be found in precision agriculture, environmental monitoring and industrial automation. The IEEE 802.15.4/ZigBee cluster-tree topology is a suitable topology to build wide-scale WSNs. Despite some of its known advantages, including timing synchronisation and duty-cycle operation, cluster-tree networks may suffer from severe network congestion problems due to the convergecast pattern of its communication traffic. Therefore, the careful adjustment of transmission opportunities (superframe durations) allocated to the cluster-heads is an important research issue. This paper proposes a set of proportional Superframe Duration Allocation (SDA) schemes, based on well-defined protocol and timing models, and on the message load imposed by child nodes (Load-SDA scheme), or by number of descendant nodes (Nodes-SDA scheme) of each cluster-head. The underlying reasoning is to adequately allocate transmission opportunities (superframe durations) and parametrize buffer sizes, in order to improve the network throughput and avoid typical problems, such as: network congestion, high end-to-end communication delays and discarded messages due to buffer overflows. Simulation assessments show how proposed allocation schemes may clearly improve the operation of wide-scale cluster-tree networks. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

10 pages, 2948 KiB

Open AccessArticle

Impedance-Based Pre-Stress Monitoring of Rock Bolts Using a Piezoceramic-Based Smart Washer—A Feasibility Study

by Bo Wang¹, Linsheng Huo²

, Dongdong Chen², Weijie Li³ and Gangbing Song^3,*

¹ Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China;

² State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China;

³ Smart Material and Structure Laboratory, Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA;

Sensors 2017, 17(2), 250; https://doi.org/10.3390/s17020250 - 27 Jan 2017

Cited by 76 | Viewed by 6393

Abstract

Pre-stress degradation or looseness of rock bolts in mining or tunnel engineering threatens the stability and reliability of the structures. In this paper, an innovative piezoelectric device named a “smart washer” with the impedance method is proposed with the aim of developing a [...] Read more.

Pre-stress degradation or looseness of rock bolts in mining or tunnel engineering threatens the stability and reliability of the structures. In this paper, an innovative piezoelectric device named a “smart washer” with the impedance method is proposed with the aim of developing a real-time device to monitor the pre-stress level of rock bolts. The proposed method was verified through tests on a rock bolt specimen. By applying high-frequency sweep excitations (typically >30 kHz) to the smart washer that was installed on the rock bolt specimen, we observed that the variation in impedance signatures indicated the rock bolt pre-stress status. With the degradation of rock bolt pre-stress, the frequency in the dominating peak of the real part of the electrical impedance signature increased. To quantify the effectiveness of the proposed technique, a normalized root mean square deviation (RMSD) index was developed to evaluate the degradation level of the rock bolt pre-stress. The experimental results demonstrated that the normalized RMSD-based looseness index, which was computed from the impedance value detected by the “smart washer”, increased with loss of the pre-stress of the rock bolt. Therefore, the proposed method can effectively detect the degradation of rock bolt pre-stress, as demonstrated by experiments. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

18 pages, 5293 KiB

Open AccessArticle

Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

by R. Brian Jenkins^1,*, Peter Joyce² and Deborah Mechtel¹

¹ Department of Electrical and Computer Engineering, US Naval Academy, 105 Maryland Ave, Annapolis, MD 21402, USA

² Department of Mechanical Engineering, US Naval Academy, 590 Holloway Rd., Annapolis, MD 21402, USA

Sensors 2017, 17(2), 251; https://doi.org/10.3390/s17020251 - 27 Jan 2017

Cited by 15 | Viewed by 5751

Abstract

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its [...] Read more.

Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay. Full article

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

▼ Show Figures

Figure 1

14 pages, 4534 KiB

Open AccessArticle

A Novel Earphone Type Sensor for Measuring Mealtime: Consideration of the Method to Distinguish between Running and Meals

by Kazuhiro Taniguchi^1,*

, Hikaru Chiaki¹, Mami Kurosawa² and Atsushi Nishikawa³

¹ Graduate School of Information Sciences, Hiroshima City University, 3-4-1 Ozukahigashi, Asaminami-ku, Hiroshima 731-3194, Japan

² Graduate School of Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567, Japan

³ Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567, Japan

Sensors 2017, 17(2), 252; https://doi.org/10.3390/s17020252 - 27 Jan 2017

Cited by 19 | Viewed by 6598

Abstract

In this study, we describe a technique for estimating meal times using an earphone-type wearable sensor. A small optical sensor composed of a light-emitting diode and phototransistor is inserted into the ear hole of a user and estimates the meal times of the [...] Read more.

In this study, we describe a technique for estimating meal times using an earphone-type wearable sensor. A small optical sensor composed of a light-emitting diode and phototransistor is inserted into the ear hole of a user and estimates the meal times of the user from the time variations in the amount of light received. This is achieved by emitting light toward the inside of the ear canal and receiving light reflected back from the ear canal. This proposed technique allowed “meals” to be differentiated from having conversations, sneezing, walking, ascending and descending stairs, operating a computer, and using a smartphone. Conventional devices worn on the head of users and that measure food intake can vibrate during running as the body is jolted more violently than during walking; this can result in the misidentification of running as eating by these devices. To solve this problem, we used two of our sensors simultaneously: one in the left ear and one in the right ear. This was based on our finding that measurements from the left and right ear canals have a strong correlation during running but no correlation during eating. This allows running and eating to be distinguished based on correlation coefficients, which can reduce misidentification. Moreover, by using an optical sensor composed of a semiconductor, a small and lightweight device can be created. This measurement technique can also measure body motion associated with running, and the data obtained from the optical sensor inserted into the ear can be used to support a healthy lifestyle regarding both eating and exercise. Full article

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

▼ Show Figures

Figure 1

17 pages, 6741 KiB

Open AccessArticle

An Interactive Image Segmentation Method in Hand Gesture Recognition

by Disi Chen¹, Gongfa Li^1,*, Ying Sun¹, Jianyi Kong¹, Guozhang Jiang¹, Heng Tang¹, Zhaojie Ju², Hui Yu²

and Honghai Liu²

¹ School of Machinery and Automation, Wuhan University of Science and Technology, Wuhan 430081, China

² School of Computing, University of Portsmouth, Portsmouth PO1 3HE, UK

Sensors 2017, 17(2), 253; https://doi.org/10.3390/s17020253 - 27 Jan 2017

Cited by 82 | Viewed by 11811

Abstract

In order to improve the recognition rate of hand gestures a new interactive image segmentation method for hand gesture recognition is presented, and popular methods, e.g., Graph cut, Random walker, Interactive image segmentation using geodesic star convexity, are studied in this article. The [...] Read more.

In order to improve the recognition rate of hand gestures a new interactive image segmentation method for hand gesture recognition is presented, and popular methods, e.g., Graph cut, Random walker, Interactive image segmentation using geodesic star convexity, are studied in this article. The Gaussian Mixture Model was employed for image modelling and the iteration of Expectation Maximum algorithm learns the parameters of Gaussian Mixture Model. We apply a Gibbs random field to the image segmentation and minimize the Gibbs Energy using Min-cut theorem to find the optimal segmentation. The segmentation result of our method is tested on an image dataset and compared with other methods by estimating the region accuracy and boundary accuracy. Finally five kinds of hand gestures in different backgrounds are tested on our experimental platform, and the sparse representation algorithm is used, proving that the segmentation of hand gesture images helps to improve the recognition accuracy. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

15 pages, 6420 KiB

Open AccessArticle

A New, Adaptable, Optical High-Resolution 3-Axis Sensor

by Niels Buchhold^* and Christian Baumgartner^*

Institute for Health Care Engineering, Graz University of Technology, Stremayrgasse 16, 8010 Graz, Austria

Sensors 2017, 17(2), 254; https://doi.org/10.3390/s17020254 - 27 Jan 2017

Cited by 2 | Viewed by 5814

Abstract

This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed [...] Read more.

This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD). The downstream microcontroller’s software identifies the geometric shape’s center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels), the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates) and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user’s range of motion (stroke and force). This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

25 pages, 8326 KiB

Open AccessArticle

Loose and Tight GNSS/INS Integrations: Comparison of Performance Assessed in Real Urban Scenarios

by Gianluca Falco^*

, Marco Pini and Gianluca Marucco

Istituto Superiore Mario Boella, Torino 10138, Italy

Sensors 2017, 17(2), 255; https://doi.org/10.3390/s17020255 - 29 Jan 2017

Cited by 211 | Viewed by 13693

Abstract

Global Navigation Satellite Systems (GNSSs) remain the principal mean of positioning in many applications and systems, but in several types of environment, the performance of standalone receivers is degraded. Although many works show the benefits of the integration between GNSS and Inertial Navigation [...] Read more.

Global Navigation Satellite Systems (GNSSs) remain the principal mean of positioning in many applications and systems, but in several types of environment, the performance of standalone receivers is degraded. Although many works show the benefits of the integration between GNSS and Inertial Navigation Systems (INSs), tightly-coupled architectures are mainly implemented in professional devices and are based on high-grade Inertial Measurement Units (IMUs). This paper investigates the performance improvements enabled by the tight integration, using low-cost sensors and a mass-market GNSS receiver. Performance is assessed through a series of tests carried out in real urban scenarios and is compared against commercial modules, operating in standalone mode or featuring loosely-coupled integrations. The paper describes the developed tight-integration algorithms with a terse mathematical model and assesses their efficacy from a practical perspective. Full article

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

▼ Show Figures

Figure 1

21 pages, 2600 KiB

Open AccessReview

Analytical Protein Microarrays: Advancements Towards Clinical Applications

by Ursula Sauer

AIT Austrian Institute of Technology GmbH, Center for Health and Bioresources, 3430 Tulln, Austria

Sensors 2017, 17(2), 256; https://doi.org/10.3390/s17020256 - 29 Jan 2017

Cited by 35 | Viewed by 11782

Abstract

Protein microarrays represent a powerful technology with the potential to serve as tools for the detection of a broad range of analytes in numerous applications such as diagnostics, drug development, food safety, and environmental monitoring. Key features of analytical protein microarrays include high [...] Read more.

Protein microarrays represent a powerful technology with the potential to serve as tools for the detection of a broad range of analytes in numerous applications such as diagnostics, drug development, food safety, and environmental monitoring. Key features of analytical protein microarrays include high throughput and relatively low costs due to minimal reagent consumption, multiplexing, fast kinetics and hence measurements, and the possibility of functional integration. So far, especially fundamental studies in molecular and cell biology have been conducted using protein microarrays, while the potential for clinical, notably point-of-care applications is not yet fully utilized. The question arises what features have to be implemented and what improvements have to be made in order to fully exploit the technology. In the past we have identified various obstacles that have to be overcome in order to promote protein microarray technology in the diagnostic field. Issues that need significant improvement to make the technology more attractive for the diagnostic market are for instance: too low sensitivity and deficiency in reproducibility, inadequate analysis time, lack of high-quality antibodies and validated reagents, lack of automation and portable instruments, and cost of instruments necessary for chip production and read-out. The scope of the paper at hand is to review approaches to solve these problems. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

▼ Show Figures

Figure 1

13 pages, 7102 KiB

Open AccessArticle

Topologically Optimized Nano-Positioning Stage Integrating with a Capacitive Comb Sensor

by Tao Chen, Yaqiong Wang, Huicong Liu^*, Zhan Yang^*

, Pengbo Wang and Lining Sun

Jiangsu Provincial Key Laboratory of Advanced Robotics & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China

Sensors 2017, 17(2), 257; https://doi.org/10.3390/s17020257 - 28 Jan 2017

Cited by 7 | Viewed by 5988

Abstract

Nano-positioning technology has been widely used in many fields, such as microelectronics, optical engineering, and micro manufacturing. This paper presents a one-dimensional (1D) nano-positioning system, adopting a piezoelectric ceramic (PZT) actuator and a multi-objective topological optimal structure. The combination of a nano-positioning stage [...] Read more.

Nano-positioning technology has been widely used in many fields, such as microelectronics, optical engineering, and micro manufacturing. This paper presents a one-dimensional (1D) nano-positioning system, adopting a piezoelectric ceramic (PZT) actuator and a multi-objective topological optimal structure. The combination of a nano-positioning stage and a feedback capacitive comb sensor has been achieved. In order to obtain better performance, a wedge-shaped structure is used to apply the precise pre-tension for the piezoelectric ceramics. Through finite element analysis and experimental verification, better static performance and smaller kinetic coupling are achieved. The output displacement of the system achieves a long-stroke of up to 14.7 μm and high-resolution of less than 3 nm. It provides a flexible and efficient way in the design and optimization of the nano-positioning system. Full article

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

▼ Show Figures

Figure 1

10 pages, 1690 KiB

Open AccessArticle

THz Pyro-Optical Detector Based on LiNbO₃ Whispering Gallery Mode Microdisc Resonator

by Alessandro Cosci^1,2,*, Matteo Cerminara³

, Gualtiero Nunzi Conti²

, Silvia Soria²

, Giancarlo C. Righini^1,2 and Stefano Pelli^1,2

¹ Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi”, Piazza del Viminale 1, 00184 Rome, Italy

² IFAC-CNR, Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy

³ Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Via della Faggiola 32, 56126 Pisa, Italy

Sensors 2017, 17(2), 258; https://doi.org/10.3390/s17020258 - 28 Jan 2017

Cited by 7 | Viewed by 5382

Abstract

This study analyzes the capabilities of a LiNbO₃ whispering gallery mode microdisc resonator as a potential bolometer detector in the THz range. The resonator is theoretically characterized in the stationary regime by its thermo-optic and thermal coefficients. Considering a Q-factor of 10 [...] Read more.

This study analyzes the capabilities of a LiNbO₃ whispering gallery mode microdisc resonator as a potential bolometer detector in the THz range. The resonator is theoretically characterized in the stationary regime by its thermo-optic and thermal coefficients. Considering a Q-factor of 10⁷, a minimum detectable power of 20 μW was evaluated, three orders of magnitude above its noise equivalent power. This value opens up the feasibility of exploiting LiNbO₃ disc resonators as sensitive room-temperature detectors in the THz range. Full article

(This article belongs to the Special Issue Infrared Detectors)

▼ Show Figures

Figure 1

18 pages, 17459 KiB

Open AccessArticle

Evaluation of the Vegetation Coverage Resilience in Areas Damaged by the Wenchuan Earthquake Based on MODIS-EVI Data

by Xiaofu Liu^1,2,3

, Weiguo Jiang^1,3,*

, Jing Li¹ and Wenjie Wang²

¹ State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China

² Institute of Environmental Information, Chinese Research Academy of Environmental Sciences, Beijing 100012, China

³ Academy of Disaster Reduction and Emergency Management, Beijing Normal University, Beijing 100875, China

Sensors 2017, 17(2), 259; https://doi.org/10.3390/s17020259 - 28 Jan 2017

Cited by 23 | Viewed by 5229

Abstract

The concept of resilience was integrated into post-earthquake ecological restoration assessments in 10 counties heavily impacted by the 2008 Wenchuan earthquake. Ecological resilience was defined as the time interval required for the vegetation coverage to recover to pre-earthquake levels in damaged areas. MODIS-EVI [...] Read more.

The concept of resilience was integrated into post-earthquake ecological restoration assessments in 10 counties heavily impacted by the 2008 Wenchuan earthquake. Ecological resilience was defined as the time interval required for the vegetation coverage to recover to pre-earthquake levels in damaged areas. MODIS-EVI data from May to August in 2000 to 2016 were used to calculate the ecological resilience by fitting the curve of recovery rate (RR) versus time. The following conclusions were reached: (1) An area of 424.1 km² sustained vegetation damage. (2) The vegetation recovery was found to be linear based on the statistical analysis of the most common components of the damaged areas; consequently, linear fitting was used to estimate the resilience. (3) In terms of vegetation coverage, 44.2% of the damaged areas have already recovered. The vast majority of damaged areas are predicted to achieve vegetation recovery by 2022, but 5.3% of the damaged areas will not recover within this time period and have no resilience. (4) The management of damaged areas near roads, rivers and mining operations, especially at elevations of 2000–2500 m, slopes greater than 30°, and precipitation levels greater than 1200 mm, should be prioritized in the future. (5) The innovations of this study include the method used to extract earthquake-related vegetation damage and the prediction of vegetation succession based on resilience. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

▼ Show Figures

Graphical abstract

21 pages, 26693 KiB

Open AccessArticle

A Semantic Labeling of the Environment Based on What People Do

by Jonathan Crespo^*

, Clara Gómez, Alejandra Hernández and Ramón Barber

Department of Systems Engineering and Automation, University Carlos III of Madrid, 28911, Spain

Sensors 2017, 17(2), 260; https://doi.org/10.3390/s17020260 - 29 Jan 2017

Cited by 3 | Viewed by 4904

Abstract

In this work, a system is developed for semantic labeling of locations based on what people do. This system is useful for semantic navigation of mobile robots. The system differentiates environments according to what people do in them. Background sound, number of people [...] Read more.

In this work, a system is developed for semantic labeling of locations based on what people do. This system is useful for semantic navigation of mobile robots. The system differentiates environments according to what people do in them. Background sound, number of people in a room and amount of movement of those people are items to be considered when trying to tell if people are doing different actions. These data are sampled, and it is assumed that people behave differently and perform different actions. A support vector machine is trained with the obtained samples, and therefore, it allows one to identify the room. Finally, the results are discussed and support the hypothesis that the proposed system can help to semantically label a room. Full article

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

▼ Show Figures

Figure 1

12 pages, 3446 KiB

Open AccessArticle

Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors

by Marzena Hirsch^1,†, Daria Majchrowicz^1,†, Paweł Wierzba¹, Matthieu Weber², Mikhael Bechelany² and Małgorzata Jędrzejewska-Szczerska^1,*

¹ Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, Narutowicza Street 11/12, 80-233 Gdańsk, Poland

² Institut Européen des Membranes, UMR-5635, Université de Montpellier, École Nationale Supérieure de Chimie de Montpellier, Centre national de la recherche scientifique, Place Eugène Bataillon, Montpellier 34095, France

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 261; https://doi.org/10.3390/s17020261 - 28 Jan 2017

Cited by 51 | Viewed by 7327

Abstract

Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The [...] Read more.

Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO₂) and aluminum oxide (Al₂O₃) with thicknesses from 30 to 220 nm have been evaluated numerically and compared. TiO₂ films were found to be the most promising candidates for the tuning of FPI reflectivity. In order to verify and illustrate the results of modelling, TiO₂ films with the thickness of 80 nm have been deposited on the tip of a single-mode optical fiber by atomic layer deposition (ALD). The thickness, the structure, and the chemical properties of the films have been determined. The ability of the selected TiO₂ films to modify the reflectivity of the Fabry-Pérot cavity, to provide protection of the fibers from aggressive environments, and to create multi-cavity interferometric sensors in FPI has then been studied. The presented sensor exhibits an ability to measure refractive index in the range close to that of silica glass fiber, where sensors without reflective films do not work, as was demonstrated by the measurement of the refractive index of benzene. This opens up the prospects of applying the investigated sensor in biosensing, which we confirmed by measuring the refractive index of hemoglobin and glucose. Full article

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

▼ Show Figures

Figure 1

15 pages, 4403 KiB

Open AccessArticle

An Information Retrieval Approach for Robust Prediction of Road Surface States

by Jae-Hyung Park¹ and Kwanho Kim^2,*

¹ ICT Convergence R & D Center, Metabuild Co., Ltd., 5F 1487-6 Seocho-3dong, Seocho-gu, Seoul 06708, Korea

² Department of Industrial and Management Engineering, College of Engineering, Incheon National University, Incheon 22012, Korea

Sensors 2017, 17(2), 262; https://doi.org/10.3390/s17020262 - 28 Jan 2017

Cited by 1 | Viewed by 4567

Abstract

Recently, due to the increasing importance of reducing severe vehicle accidents on roads (especially on highways), the automatic identification of road surface conditions, and the provisioning of such information to drivers in advance, have recently been gaining significant momentum as a proactive solution [...] Read more.

Recently, due to the increasing importance of reducing severe vehicle accidents on roads (especially on highways), the automatic identification of road surface conditions, and the provisioning of such information to drivers in advance, have recently been gaining significant momentum as a proactive solution to decrease the number of vehicle accidents. In this paper, we firstly propose an information retrieval approach that aims to identify road surface states by combining conventional machine-learning techniques and moving average methods. Specifically, when signal information is received from a radar system, our approach attempts to estimate the current state of the road surface based on the similar instances observed previously based on utilizing a given similarity function. Next, the estimated state is then calibrated by using the recently estimated states to yield both effective and robust prediction results. To validate the performances of the proposed approach, we established a real-world experimental setting on a section of actual highway in South Korea and conducted a comparison with the conventional approaches in terms of accuracy. The experimental results show that the proposed approach successfully outperforms the previously developed methods. Full article

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

▼ Show Figures

Figure 1

13 pages, 3291 KiB

Open AccessArticle

Replacement Condition Detection of Railway Point Machines Using an Electric Current Sensor

by Jaewon Sa¹

, Younchang Choi¹, Yongwha Chung^1,*, Hee-Young Kim², Daihee Park¹ and Sukhan Yoon³

¹ Department of Computer and Information Science, Korea University, Sejong 30019, Korea

² Department of Applied Statistics, Korea University, Sejong 30019, Korea

³ Sehwa R&D Center, Techno 2-ro, Yuseong-gu, Daejeon 34026, Korea

Sensors 2017, 17(2), 263; https://doi.org/10.3390/s17020263 - 29 Jan 2017

Cited by 19 | Viewed by 6524

Abstract

Detecting replacement conditions of railway point machines is important to simultaneously satisfy the budget-limit and train-safety requirements. In this study, we consider classification of the subtle differences in the aging effect—using electric current shape analysis—for the purpose of replacement condition detection of railway [...] Read more.

Detecting replacement conditions of railway point machines is important to simultaneously satisfy the budget-limit and train-safety requirements. In this study, we consider classification of the subtle differences in the aging effect—using electric current shape analysis—for the purpose of replacement condition detection of railway point machines. After analyzing the shapes of after-replacement data and then labeling the shapes of each before-replacement data, we can derive the criteria that can handle the subtle differences between “does-not-need-to-be-replaced” and “needs-to-be-replaced” shapes. On the basis of the experimental results with in-field replacement data, we confirmed that the proposed method could detect the replacement conditions with acceptable accuracy, as well as provide visual interpretability of the criteria used for the time-series classification. Full article

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

▼ Show Figures

Figure 1

19 pages, 9574 KiB

Open AccessArticle

A Kalman Filter for SINS Self-Alignment Based on Vector Observation

by Xiang Xu^1,2

, Xiaosu Xu^1,2,*

, Tao Zhang^1,2, Yao Li^1,2 and Jinwu Tong^1,2

¹ Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Nanjing 210096, China

² Ministry of Education, School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

Sensors 2017, 17(2), 264; https://doi.org/10.3390/s17020264 - 29 Jan 2017

Cited by 44 | Viewed by 7398

Abstract

In this paper, a self-alignment method for strapdown inertial navigation systems based on the q-method is studied. In addition, an improved method based on integrating gravitational apparent motion to form apparent velocity is designed, which can reduce the random noises of the [...] Read more.

In this paper, a self-alignment method for strapdown inertial navigation systems based on the q-method is studied. In addition, an improved method based on integrating gravitational apparent motion to form apparent velocity is designed, which can reduce the random noises of the observation vectors. For further analysis, a novel self-alignment method using a Kalman filter based on adaptive filter technology is proposed, which transforms the self-alignment procedure into an attitude estimation using the observation vectors. In the proposed method, a linear psuedo-measurement equation is adopted by employing the transfer method between the quaternion and the observation vectors. Analysis and simulation indicate that the accuracy of the self-alignment is improved. Meanwhile, to improve the convergence rate of the proposed method, a new method based on parameter recognition and a reconstruction algorithm for apparent gravitation is devised, which can reduce the influence of the random noises of the observation vectors. Simulations and turntable tests are carried out, and the results indicate that the proposed method can acquire sound alignment results with lower standard variances, and can obtain higher alignment accuracy and a faster convergence rate. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

33 pages, 3320 KiB

Open AccessReview

A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications

by Jun Zhang^1,2, Gui Yun Tian^1,2,*, Adi M. J. Marindra¹, Ali Imam Sunny¹ and Ao Bo Zhao¹

¹ School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

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

Sensors 2017, 17(2), 265; https://doi.org/10.3390/s17020265 - 29 Jan 2017

Cited by 357 | Viewed by 31441

Abstract

In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find [...] Read more.

In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well. Full article

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

▼ Show Figures

Figure 1

13 pages, 6928 KiB

Open AccessArticle

Liquid Temperature Measurements Using Two Different Tunable Hollow Prisms

by Sergio Calixto^1,*

, Martha Rosete-Aguilar² and Ismael Torres-Gomez¹

¹ Centro de Investigaciones en Optica, Loma del Bosque 115, Leon 37150, Mexico

² Centro de Ciencias Aplicadas y Desarrollo Tecnológico (CCADET), Universidad Nacional Autónoma de México (UNAM), Av. Universidad 3000, Coyoacán, Distrito Federal 04510, Mexico

Sensors 2017, 17(2), 266; https://doi.org/10.3390/s17020266 - 29 Jan 2017

Cited by 2 | Viewed by 6852

Abstract

This paper describes the design, fabrication, and testing of two hollow prisms. One is a prism with a grating glued to its hypotenuse. This ensemble, prism + grating, is called a grism. It can be applied as an on-axis tunable spectrometer. The other [...] Read more.

This paper describes the design, fabrication, and testing of two hollow prisms. One is a prism with a grating glued to its hypotenuse. This ensemble, prism + grating, is called a grism. It can be applied as an on-axis tunable spectrometer. The other hollow prism is a constant deviation one called a Pellin-Broca. It can be used as a tunable dispersive element in a spectrometer with no moving parts. The application of prisms as temperature sensors is shown. Full article

(This article belongs to the Special Issue Innovative Sensing Control Scheme for Advanced Materials)

▼ Show Figures

Figure 1

12 pages, 3597 KiB

Open AccessArticle

Enhanced Living by Assessing Voice Pathology Using a Co-Occurrence Matrix

by Ghulam Muhammad^1,*

, Mohammed F. Alhamid², M. Shamim Hossain², Ahmad S. Almogren³

and Athanasios V. Vasilakos⁴

¹ Department of Computer Engineering, College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia

² Department of Software Engineering, College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia

³ Department of Computer Science, College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia

⁴ Department of Computer Science, Electrical and Space Engineering, Lulea University of Technology, 93187 Skellefteå, Sweden

Sensors 2017, 17(2), 267; https://doi.org/10.3390/s17020267 - 29 Jan 2017

Cited by 38 | Viewed by 5557

Abstract

A large number of the population around the world suffers from various disabilities. Disabilities affect not only children but also adults of different professions. Smart technology can assist the disabled population and lead to a comfortable life in an enhanced living environment (ELE). [...] Read more.

A large number of the population around the world suffers from various disabilities. Disabilities affect not only children but also adults of different professions. Smart technology can assist the disabled population and lead to a comfortable life in an enhanced living environment (ELE). In this paper, we propose an effective voice pathology assessment system that works in a smart home framework. The proposed system takes input from various sensors, and processes the acquired voice signals and electroglottography (EGG) signals. Co-occurrence matrices in different directions and neighborhoods from the spectrograms of these signals were obtained. Several features such as energy, entropy, contrast, and homogeneity from these matrices were calculated and fed into a Gaussian mixture model-based classifier. Experiments were performed with a publicly available database, namely, the Saarbrucken voice database. The results demonstrate the feasibility of the proposed system in light of its high accuracy and speed. The proposed system can be extended to assess other disabilities in an ELE. Full article

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

▼ Show Figures

Figure 1

15 pages, 13133 KiB

Open AccessReview

Recent Advances in Silicon Nanomaterial-Based Fluorescent Sensors

by Houyu Wang and Yao He^*

Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123, China

Sensors 2017, 17(2), 268; https://doi.org/10.3390/s17020268 - 3 Feb 2017

Cited by 44 | Viewed by 8896

Abstract

During the past decades, owing to silicon nanomaterials’ unique optical properties, benign biocompatibility, and abundant surface chemistry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance fluorescent sensors for the detection of various chemical and biological species. Among [...] Read more.

During the past decades, owing to silicon nanomaterials’ unique optical properties, benign biocompatibility, and abundant surface chemistry, different dimensional silicon nanostructures have been widely employed for rationally designing and fabricating high-performance fluorescent sensors for the detection of various chemical and biological species. Among of these, zero-dimensional silicon nanoparticles (SiNPs) and one-dimensional silicon nanowires (SiNWs) are of particular interest. Herein, we focus on reviewing recent advances in silicon nanomaterials-based fluorescent sensors from a broad perspective and discuss possible future directions. Firstly, we introduce the latest achievement of zero-dimensional SiNP-based fluorescent sensors. Next, we present recent advances of one-dimensional SiNW-based fluorescent sensors. Finally, we discuss the major challenges and prospects for the development of silicon-based fluorescent sensors. Full article

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

▼ Show Figures

Figure 1

11 pages, 3428 KiB

Open AccessArticle

A Ring Artifact Correction Method: Validation by Micro-CT Imaging with Flat-Panel Detectors and a 2D Photon-Counting Detector

by Mohamed Elsayed Eldib, Mohamed Hegazy, Yang Ji Mun, Myung Hye Cho, Min Hyoung Cho and Soo Yeol Lee^*

Department of Biomedical Engineering, Kyung Hee University, Yongin, Gyeonggi 17104, Korea

Sensors 2017, 17(2), 269; https://doi.org/10.3390/s17020269 - 30 Jan 2017

Cited by 41 | Viewed by 10382

Abstract

We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT). In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean [...] Read more.

We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT). In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean value at each detector element along the view angle in the sinogram to obtain the one-dimensional (1D) mean vector, and we then compute the 1D correction vector by taking inverse of the mean vector. We multiply the correction vector with the sinogram row by row over all view angles. In the third step, we apply a Gaussian filter on the difference image between the original CT image and the corrected CT image obtained in the previous step. The filtered difference image is added to the corrected CT image to compensate the possible contrast anomaly that may appear due to the contrast change in the sinogram after removing stripe artifacts. We applied the proposed method to the projection data acquired by two flat-panel detectors (FPDs) and a silicon-based photon-counting X-ray detector (PCXD). Micro-CT imaging experiments of phantoms and a small animal have shown that the proposed method can greatly reduce ring artifacts regardless of detector types. Despite the great reduction of ring artifacts, the proposed method does not compromise the original spatial resolution and contrast. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 1522 KiB

Open AccessArticle

Real-Time Straight-Line Detection for XGA-Size Videos by Hough Transform with Parallelized Voting Procedures

by Jungang Guan^*, Fengwei An^*, Xiangyu Zhang^*

, Lei Chen^* and Hans Jürgen Mattausch^*

Hiroshima University, 1-3-1 Higashi-Hiroshima, Hiroshima 739-8530, Japan

Sensors 2017, 17(2), 270; https://doi.org/10.3390/s17020270 - 30 Jan 2017

Cited by 24 | Viewed by 8324

Abstract

The Hough Transform (HT) is a method for extracting straight lines from an edge image. The main limitations of the HT for usage in actual applications are computation time and storage requirements. This paper reports a hardware architecture for HT implementation on a [...] Read more.

The Hough Transform (HT) is a method for extracting straight lines from an edge image. The main limitations of the HT for usage in actual applications are computation time and storage requirements. This paper reports a hardware architecture for HT implementation on a Field Programmable Gate Array (FPGA) with parallelized voting procedure. The 2-dimensional accumulator array, namely the Hough space in parametric form (ρ, θ), for computing the strength of each line by a voting mechanism is mapped on a 1-dimensional array with regular increments of θ. Then, this Hough space is divided into a number of parallel parts. The computation of (ρ, θ) for the edge pixels and the voting procedure for straight-line determination are therefore executable in parallel. In addition, a synchronized initialization for the Hough space further increases the speed of straight-line detection, so that XGA video processing becomes possible. The designed prototype system has been synthesized on a DE4 platform with a Stratix-IV FPGA device. In the application of road-lane detection, the average processing speed of this HT implementation is 5.4ms per XGA-frame at 200 MHz working frequency. Full article

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

▼ Show Figures

Figure 1

27 pages, 4038 KiB

Open AccessReview

Survey on Ranging Sensors and Cooperative Techniques for Relative Positioning of Vehicles

by Fabian De Ponte Müller

German Aerospace Center (DLR), Institute of Communications and Navigation, 82234Wessling, Germany

Sensors 2017, 17(2), 271; https://doi.org/10.3390/s17020271 - 31 Jan 2017

Cited by 237 | Viewed by 16633

Abstract

Future driver assistance systems will rely on accurate, reliable and continuous knowledge on the position of other road participants, including pedestrians, bicycles and other vehicles. The usual approach to tackle this requirement is to use on-board ranging sensors inside the vehicle. Radar, laser [...] Read more.

Future driver assistance systems will rely on accurate, reliable and continuous knowledge on the position of other road participants, including pedestrians, bicycles and other vehicles. The usual approach to tackle this requirement is to use on-board ranging sensors inside the vehicle. Radar, laser scanners or vision-based systems are able to detect objects in their line-of-sight. In contrast to these non-cooperative ranging sensors, cooperative approaches follow a strategy in which other road participants actively support the estimation of the relative position. The limitations of on-board ranging sensors regarding their detection range and angle of view and the facility of blockage can be approached by using a cooperative approach based on vehicle-to-vehicle communication. The fusion of both, cooperative and non-cooperative strategies, seems to offer the largest benefits regarding accuracy, availability and robustness. This survey offers the reader a comprehensive review on different techniques for vehicle relative positioning. The reader will learn the important performance indicators when it comes to relative positioning of vehicles, the different technologies that are both commercially available and currently under research, their expected performance and their intrinsic limitations. Moreover, the latest research in the area of vision-based systems for vehicle detection, as well as the latest work on GNSS-based vehicle localization and vehicular communication for relative positioning of vehicles, are reviewed. The survey also includes the research work on the fusion of cooperative and non-cooperative approaches to increase the reliability and the availability. Full article

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

▼ Show Figures

Figure 1

15 pages, 5892 KiB

Open AccessArticle

Classification of Multiple Chinese Liquors by Means of a QCM-based E-Nose and MDS-SVM Classifier

by Qiang Li, Yu Gu^*

and Jing Jia

School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China

Sensors 2017, 17(2), 272; https://doi.org/10.3390/s17020272 - 30 Jan 2017

Cited by 53 | Viewed by 7462

Abstract

Chinese liquors are internationally well-known fermentative alcoholic beverages. They have unique flavors attributable to the use of various bacteria and fungi, raw materials, and production processes. Developing a novel, rapid, and reliable method to identify multiple Chinese liquors is of positive significance. This [...] Read more.

Chinese liquors are internationally well-known fermentative alcoholic beverages. They have unique flavors attributable to the use of various bacteria and fungi, raw materials, and production processes. Developing a novel, rapid, and reliable method to identify multiple Chinese liquors is of positive significance. This paper presents a pattern recognition system for classifying ten brands of Chinese liquors based on multidimensional scaling (MDS) and support vector machine (SVM) algorithms in a quartz crystal microbalance (QCM)-based electronic nose (e-nose) we designed. We evaluated the comprehensive performance of the MDS-SVM classifier that predicted all ten brands of Chinese liquors individually. The prediction accuracy (98.3%) showed superior performance of the MDS-SVM classifier over the back-propagation artificial neural network (BP-ANN) classifier (93.3%) and moving average-linear discriminant analysis (MA-LDA) classifier (87.6%). The MDS-SVM classifier has reasonable reliability, good fitting and prediction (generalization) performance in classification of the Chinese liquors. Taking both application of the e-nose and validation of the MDS-SVM classifier into account, we have thus created a useful method for the classification of multiple Chinese liquors. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

18 pages, 856 KiB

Open AccessArticle

Learning to Monitor Machine Health with Convolutional Bi-Directional LSTM Networks

by Rui Zhao^1,2, Ruqiang Yan^1,*, Jinjiang Wang³ and Kezhi Mao²

¹ School of Instrument Science and Engineering, Southeast University, Nanjing 210009, China

² School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

³ School of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China

Sensors 2017, 17(2), 273; https://doi.org/10.3390/s17020273 - 30 Jan 2017

Cited by 689 | Viewed by 24915

Abstract

In modern manufacturing systems and industries, more and more research efforts have been made in developing effective machine health monitoring systems. Among various machine health monitoring approaches, data-driven methods are gaining in popularity due to the development of advanced sensing and data analytic [...] Read more.

In modern manufacturing systems and industries, more and more research efforts have been made in developing effective machine health monitoring systems. Among various machine health monitoring approaches, data-driven methods are gaining in popularity due to the development of advanced sensing and data analytic techniques. However, considering the noise, varying length and irregular sampling behind sensory data, this kind of sequential data cannot be fed into classiﬁcation and regression models directly. Therefore, previous work focuses on feature extraction/fusion methods requiring expensive human labor and high quality expert knowledge. With the development of deep learning methods in the last few years, which redeﬁne representation learning from raw data, a deep neural network structure named Convolutional Bi-directional Long Short-Term Memory networks (CBLSTM) has been designed here to address raw sensory data. CBLSTM ﬁrstly uses CNN to extract local features that are robust and informative from the sequential input. Then, bi-directional LSTM is introduced to encode temporal information. Long Short-Term Memory networks(LSTMs) are able to capture long-term dependencies and model sequential data, and the bi-directional structure enables the capture of past and future contexts. Stacked, fully-connected layers and the linear regression layer are built on top of bi-directional LSTMs to predict the target value. Here, a real-life tool wear test is introduced, and our proposed CBLSTM is able to predict the actual tool wear based on raw sensory data. The experimental results have shown that our model is able to outperform several state-of-the-art baseline methods. Full article

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

▼ Show Figures

Figure 1

14 pages, 5289 KiB

Open AccessArticle

IRNSS/NavIC L5 Attitude Determination

by Safoora Zaminpardaz^1,*, Peter J.G. Teunissen^1,2 and Nandakumaran Nadarajah¹

¹ GNSS Research Centre, Department of Spatial Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia

² Department of Geoscience and Remote Sensing, Delft University of Technology, PO Box 5048, 2600 GA Delft, The Netherlands

Sensors 2017, 17(2), 274; https://doi.org/10.3390/s17020274 - 30 Jan 2017

Cited by 8 | Viewed by 7032

Abstract

The Indian Regional Navigation Satellite System (IRNSS) has recently (May 2016) become fully-operational and has been provided with the operational name of NavIC (Navigation with Indian Constellation). It has been developed by the Indian Space Research Organization (ISRO) with the objective of offering [...] Read more.

The Indian Regional Navigation Satellite System (IRNSS) has recently (May 2016) become fully-operational and has been provided with the operational name of NavIC (Navigation with Indian Constellation). It has been developed by the Indian Space Research Organization (ISRO) with the objective of offering positioning, navigation and timing (PNT) to the users in its service area. This contribution provides for the ﬁrst time an assessment of the IRNSS L5-signal capability to achieve instantaneous attitude determination on the basis of data collected in Perth, Australia. Our evaluations are conducted for both a linear array of two antennas and a planar array of three antennas. A pre-requisite for precise and fast IRNSS attitude determination is the successful resolution of the double-differenced (DD) integer carrier-phase ambiguities. In this contribution, we will compare the performances of different such methods, amongst which the unconstrained and the multivariate-constrained LAMBDA method for both linear and planar arrays. It is demonstrated that the instantaneous ambiguity success rates increase from 15% to 90% for the linear array and from 5% to close to 100% for the planar array, thus showing that standalone IRNSS can realize 24-h almost instantaneous precise attitude determination with heading and elevation standard deviations of 0.05 and 0.10 degrees, respectively. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

23 pages, 2656 KiB

Open AccessArticle

Active AU Based Patch Weighting for Facial Expression Recognition

by Weicheng Xie, Linlin Shen^*

, Meng Yang and Zhihui Lai

Computer Vision Institute, School of Computer Science & Software Engineering, Shenzhen University, Shenzhen, Guangdong 518060, China

Sensors 2017, 17(2), 275; https://doi.org/10.3390/s17020275 - 30 Jan 2017

Cited by 14 | Viewed by 6402

Abstract

Facial expression has many applications in human-computer interaction. Although feature extraction and selection have been well studied, the speciﬁcity of each expression variation is not fully explored in state-of-the-art works. In this work, the problem of multiclass expression recognition is converted into triplet-wise [...] Read more.

Facial expression has many applications in human-computer interaction. Although feature extraction and selection have been well studied, the speciﬁcity of each expression variation is not fully explored in state-of-the-art works. In this work, the problem of multiclass expression recognition is converted into triplet-wise expression recognition. For each expression triplet, a new feature optimization model based on action unit (AU) weighting and patch weight optimization is proposed to represent the speciﬁcity of the expression triplet. The sparse representation-based approach is then proposed to detect the active AUs of the testing sample for better generalization. The algorithm achieved competitive accuracies of 89.67% and 94.09% for the Jaffe and Cohn–Kanade (CK+) databases, respectively. Better cross-database performance has also been observed. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

10 pages, 1967 KiB

Open AccessArticle

A Paper-Based Electrochromic Array for Visualized Electrochemical Sensing

by Fengling Zhang¹, Tianyi Cai¹, Liang Ma¹, Liyuan Zhan¹ and Hong Liu^1,2,*

¹ State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China

² Laboratory of Environment and Biosafety, Research Institute of Southeast University in Suzhou, Suzhou 215123, China

Sensors 2017, 17(2), 276; https://doi.org/10.3390/s17020276 - 31 Jan 2017

Cited by 16 | Viewed by 7175

Abstract

We report a battery-powered, paper-based electrochromic array for visualized electrochemical sensing. The paper-based sensing system consists of six parallel electrochemical cells, which are powered by an aluminum-air battery. Each single electrochemical cell uses a Prussian Blue spot electrodeposited on an indium-doped tin oxide [...] Read more.

We report a battery-powered, paper-based electrochromic array for visualized electrochemical sensing. The paper-based sensing system consists of six parallel electrochemical cells, which are powered by an aluminum-air battery. Each single electrochemical cell uses a Prussian Blue spot electrodeposited on an indium-doped tin oxide thin film as the electrochromic indicator. Each electrochemical cell is preloaded with increasing amounts of analyte. The sample activates the battery for the sensing. Both the preloaded analyte and the analyte in the sample initiate the color change of Prussian Blue to Prussian White. With a reaction time of 60 s, the number of electrochemical cells with complete color changes is correlated to the concentration of analyte in the sample. As a proof-of-concept analyte, lactic acid was detected semi-quantitatively using the naked eye. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

▼ Show Figures

Figure 1

12 pages, 2252 KiB

Open AccessArticle

Non-Destructive Sensor-Based Prediction of Maturity and Optimum Harvest Date of Sweet Cherry Fruit

by Verena Overbeck¹, Michaela Schmitz² and Michael Blanke^1,*

¹ INRES-Horticultural Science, Faculty of Agriculture, University of Bonn, D-53121 Bonn, Germany

² Department of Applied Science, Bonn-Rhein-Sieg University, D-53359 Rheinbach, Germany

Sensors 2017, 17(2), 277; https://doi.org/10.3390/s17020277 - 31 Jan 2017

Cited by 24 | Viewed by 6655

Abstract

(1) Background: The aim of the study was to use innovative sensor technology for non-destructive determination and prediction of optimum harvest date (OHD), using sweet cherry as a model fruit, based on different ripening parameters. (2) Methods: Two cherry varieties in two growing [...] Read more.

(1) Background: The aim of the study was to use innovative sensor technology for non-destructive determination and prediction of optimum harvest date (OHD), using sweet cherry as a model fruit, based on different ripening parameters. (2) Methods: Two cherry varieties in two growing systems viz. field and polytunnel in two years were employed. The fruit quality parameters such as fruit weight and size proved unsuitable to detect OHD alone due to their dependence on crop load, climatic conditions, cultural practices, and season. Coloration during cherry ripening was characterized by a complete decline of green chlorophyll and saturation of the red anthocyanins, and was measured with a portable sensor viz. spectrometer 3–4 weeks before expected harvest until 2 weeks after harvest. (3) Results: Expressed as green NDVI (normalized differential vegetation index) and red NAI (normalized anthocyanin index) values, NAI increased from −0.5 (unripe) to +0.7 to +0.8 in mature fruit and remained at this saturation level with overripe fruits, irrespective of variety, treatment, and year. A model was developed to predict the OHD, which coincided with when NDVI reached and exceeded zero and the first derivative of NAI asymptotically approached zero. (4) Conclusion: The use of this sensor technology appears suitable for several cherry varieties and growing systems to predict the optimum harvest date. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 3340 KiB

Open AccessArticle

Performance Characterization of an xy-Stage Applied to Micrometric Laser Direct Writing Lithography

by Juan Jaramillo¹, Artur Zarzycki^2,*, July Galeano³ and Patrick Sandoz⁴

¹ Grupo de Investigación Electromagnetismo Aplicado, línea Microingeniería, Universidad EAFIT, Medellín 050022, Colombia

² Grupo de Investigación en Automática, Electrónica y Ciencias Computacionales, Línea Sistemas de Control y Robótica, Instituto Tecnológico Metropolitano, ITM, Medellín 050013, Colombia

³ Grupo de Investigación en Materiales Avanzados y Energía MatyEr, Línea Biomateriales y Electromedicina, Instituto Tecnológico Metropolitano, ITM, Medellín 050013, Colombia

⁴ Department of Applied Mechanics, FEMTO-ST Institute, University Bourgogne Franche-Comté, UFC/CNRS/ENSMM/UTBM, Besançon 25000, France

Sensors 2017, 17(2), 278; https://doi.org/10.3390/s17020278 - 31 Jan 2017

Cited by 8 | Viewed by 6567

Abstract

This article concerns the characterization of the stability and performance of a motorized stage used in laser direct writing lithography. The system was built from commercial components and commanded by G-code. Measurements use a pseudo-periodic-pattern (PPP) observed by a camera and image processing [...] Read more.

This article concerns the characterization of the stability and performance of a motorized stage used in laser direct writing lithography. The system was built from commercial components and commanded by G-code. Measurements use a pseudo-periodic-pattern (PPP) observed by a camera and image processing is based on Fourier transform and phase measurement methods. The results report that the built system has a stability against vibrations determined by peak-valley deviations of 65 nm and 26 nm in the x and y directions, respectively, with a standard deviation of 10 nm in both directions. When the xy-stage is in movement, it works with a resolution of 0.36 μm, which is an acceptable value for most of research and development (R and D) microtechnology developments in which the typical feature size used is in the micrometer range. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 5007 KiB

Open AccessArticle

Analysis of Temperature and Humidity Field in a New Bulk Tobacco Curing Barn Based on CFD

by Zhipeng Bai, Duoduo Guo, Shoucang Li and Yaohua Hu^*

College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling 712100, China

Sensors 2017, 17(2), 279; https://doi.org/10.3390/s17020279 - 31 Jan 2017

Cited by 17 | Viewed by 7680

Abstract

A new structure bulk tobacco curing barn was presented. To study the temperature and humidity field in the new structure tobacco curing barn, a 3D transient computational fluid dynamics (CFD) model was developed using porous medium, species transport, κ-ε turbulence and discrete phase [...] Read more.

A new structure bulk tobacco curing barn was presented. To study the temperature and humidity field in the new structure tobacco curing barn, a 3D transient computational fluid dynamics (CFD) model was developed using porous medium, species transport, κ-ε turbulence and discrete phase models. The CFD results demonstrated that (1) the temperature and relative humidity predictions were validated by the experimental results, and comparison of simulation results with experimental data showed a fairly close agreement; (2) the temperature of the bottom and inlet area was higher than the top and outlet area, and water vapor concentrated on the top and outlet area in the barn; (3) tobacco loading density and thickness of tobacco leaves had an explicit effect on the temperature distributions in the barn. Full article

▼ Show Figures

Figure 1

20 pages, 1804 KiB

Open AccessArticle

A Versatile and Reproducible Multi-Frequency Electrical Impedance Tomography System

by James Avery^*

, Thomas Dowrick, Mayo Faulkner, Nir Goren and David Holder

Department Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK

Sensors 2017, 17(2), 280; https://doi.org/10.3390/s17020280 - 31 Jan 2017

Cited by 87 | Viewed by 10342

Abstract

A highly versatile Electrical Impedance Tomography (EIT) system, nicknamed the ScouseTom, has been developed. The system allows control over current amplitude, frequency, number of electrodes, injection protocol and data processing. Current is injected using a Keithley 6221 current source, and voltages are recorded [...] Read more.

A highly versatile Electrical Impedance Tomography (EIT) system, nicknamed the ScouseTom, has been developed. The system allows control over current amplitude, frequency, number of electrodes, injection protocol and data processing. Current is injected using a Keithley 6221 current source, and voltages are recorded with a 24-bit EEG system with minimum bandwidth of 3.2 kHz. Custom PCBs interface with a PC to control the measurement process, electrode addressing and triggering of external stimuli. The performance of the system was characterised using resistor phantoms to represent human scalp recordings, with an SNR of 77.5 dB, stable across a four hour recording and 20 Hz to 20 kHz. In studies of both haeomorrhage using scalp electrodes, and evoked activity using epicortical electrode mats in rats, it was possible to reconstruct images matching established literature at known areas of onset. Data collected using scalp electrode in humans matched known tissue impedance spectra and was stable over frequency. The experimental procedure is software controlled and is readily adaptable to new paradigms. Where possible, commercial or open-source components were used, to minimise the complexity in reproduction. The hardware designs and software for the system have been released under an open source licence, encouraging contributions and allowing for rapid replication. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Graphical abstract

6 pages, 823 KiB

Open AccessCommunication

An Electrochemical Gas Biosensor Based on Enzymes Immobilized on Chromatography Paper for Ethanol Vapor Detection

by Tatsumi Kuretake, Shogo Kawahara, Masanobu Motooka and Shigeyasu Uno^*

Department of Electrical and Electronic Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan

Sensors 2017, 17(2), 281; https://doi.org/10.3390/s17020281 - 1 Feb 2017

Cited by 48 | Viewed by 6810

Abstract

This paper presents a novel method of fabricating an enzymatic biosensor for breath analysis using chromatography paper as enzyme supporting layer and a liquid phase layer on top of screen printed carbon electrodes. We evaluated the performance with ethanol vapor being one of [...] Read more.

This paper presents a novel method of fabricating an enzymatic biosensor for breath analysis using chromatography paper as enzyme supporting layer and a liquid phase layer on top of screen printed carbon electrodes. We evaluated the performance with ethanol vapor being one of the breathing ingredients. The experimental results show that our sensor is able to measure the concentration of ethanol vapor within the range of 50 to 500 ppm. These results suggest the ability of detecting breath ethanol, and it can possibly be applied as a generic vapor biosensor to a wide range of diseases. Full article

(This article belongs to the Special Issue Gas Sensors for Health Care and Medical Applications)

▼ Show Figures

Figure 1

14 pages, 4279 KiB

Open AccessArticle

Real-Time Performance of a Self-Powered Environmental IoT Sensor Network System

by Fan Wu¹

, Christoph Rüdiger²

and Mehmet Rasit Yuce^1,*

¹ Department of Electrical and Computer Systems Engineering, Monash University, Wellington Rd., Clayton VIC 3800, Australia

² Department of Civil Engineering, Monash University, Wellington Rd., Clayton VIC 3800, Australia

Sensors 2017, 17(2), 282; https://doi.org/10.3390/s17020282 - 1 Feb 2017

Cited by 117 | Viewed by 13193

Abstract

Wireless sensor networks (WSNs) play an increasingly important role in monitoring applications in many areas. With the emergence of the Internet-of-Things (IoT), many more lowpower sensors will need to be deployed in various environments to collect and monitor data about environmental factors in [...] Read more.

Wireless sensor networks (WSNs) play an increasingly important role in monitoring applications in many areas. With the emergence of the Internet-of-Things (IoT), many more lowpower sensors will need to be deployed in various environments to collect and monitor data about environmental factors in real time. Providing power supply to these sensor nodes becomes a critical challenge for realizations of IoT applications as sensor nodes are normally battery-powered and have a limited lifetime. This paper proposes a wireless sensor network that is powered by solar energy harvesting. The sensor network monitors the environmental data with low-power sensor electronics and forms a network using multiple XBee wireless modules. A detailed performance analysis of the network system under solar energy harvesting has been presented. The sensor network system and the proposed energy-harvesting techniques are configured to achieve a continuous energy source for the sensor network. The proposed energy-harvesting system has been successfully designed to enable an energy solution in order to keep sensor nodes active and reliable for a whole day. The paper also outlines some of our experiences in real-time implementation of a sensor network system with energy harvesting. Full article

(This article belongs to the Special Issue Autonomous Sensors)

▼ Show Figures

Figure 1

20 pages, 7941 KiB

Open AccessArticle

SOUNET: Self-Organized Underwater Wireless Sensor Network

by Hee-won Kim and Ho-Shin Cho^*

School of Electronics Engineering, Kyungpook National University, Daegu 41566, Korea

Sensors 2017, 17(2), 283; https://doi.org/10.3390/s17020283 - 2 Feb 2017

Cited by 22 | Viewed by 5221

Abstract

In this paper, we propose an underwater wireless sensor network (UWSN) named SOUNET where sensor nodes form and maintain a tree-topological network for data gathering in a self-organized manner. After network topology discovery via packet flooding, the sensor nodes consistently update their parent [...] Read more.

In this paper, we propose an underwater wireless sensor network (UWSN) named SOUNET where sensor nodes form and maintain a tree-topological network for data gathering in a self-organized manner. After network topology discovery via packet flooding, the sensor nodes consistently update their parent node to ensure the best connectivity by referring to the timevarying neighbor tables. Such a persistent and self-adaptive method leads to high network connectivity without any centralized control, even when sensor nodes are added or unexpectedly lost. Furthermore, malfunctions that frequently happen in self-organized networks such as node isolation and closed loop are resolved in a simple way. Simulation results show that SOUNET outperforms other conventional schemes in terms of network connectivity, packet delivery ratio (PDR), and energy consumption throughout the network. In addition, we performed an experiment at the Gyeongcheon Lake in Korea using commercial underwater modems to verify that SOUNET works well in a real environment. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

11 pages, 3303 KiB

Open AccessArticle

High-Sensitivity and Low-Hysteresis Porous MIMType Capacitive Humidity Sensor Using Functional Polymer Mixed with TiO2 Microparticles

by Ming-Qing Liu, Cong Wang^*

and Nam-Young Kim^*

Radio Frequency Integrated Circuit Center, Kwangwoon University, Nowon-gu, Seoul 139-701, Korea

Sensors 2017, 17(2), 284; https://doi.org/10.3390/s17020284 - 2 Feb 2017

Cited by 79 | Viewed by 7323

Abstract

In this study, a high-sensitivity and low-hysteresis porous metal–insulator–metal-type capacitive humidity sensor is investigated using a functional polymer mixed with TiO2 microparticles. The humidity sensor consists of an optimally designed porous top electrode, a functional polymer humidity sensitive layer, a bottom electrode, and [...] Read more.

In this study, a high-sensitivity and low-hysteresis porous metal–insulator–metal-type capacitive humidity sensor is investigated using a functional polymer mixed with TiO2 microparticles. The humidity sensor consists of an optimally designed porous top electrode, a functional polymer humidity sensitive layer, a bottom electrode, and a glass substrate. The porous top electrode is designed to increase the contact area between the sensing layer and water vapor, leading to high sensitivity and quick response time. The functional polymer mixed with TiO2 microparticles shows excellent hysteresis under a wide humidity-sensing range with good longterm stability. The results show that as the relative humidity ranges from 10% RH to 90% RH, the proposed humidity sensor achieves a high sensitivity of 0.85 pF/% RH and a fast response time of less than 35 s. Furthermore, the sensor shows an ultra-low hysteresis of 0.95% RH at 60% RH, a good temperature dependence, and a stable capacitance value with a maximum of 0.17% RH drift during 120 h of continuous test. Full article

(This article belongs to the Special Issue Humidity Sensors)

▼ Show Figures

Figure 1

12 pages, 5084 KiB

Open AccessArticle

Camber Angle Inspection for Vehicle Wheel Alignments

by Jieh-Shian Young^*, Hong-Yi Hsu and Chih-Yuan Chuang

Institute of Vehicle Engineering, National Changhua University of Education, Changhua County 50007, Taiwan

Sensors 2017, 17(2), 285; https://doi.org/10.3390/s17020285 - 3 Feb 2017

Cited by 10 | Viewed by 10693

Abstract

This paper introduces an alternative approach to the camber angle measurement for vehicle wheel alignment. Instead of current commercial approaches that apply computation vision techniques, this study aims at realizing a micro-control-unit (MCU)-based camber inspection system with a 3-axis accelerometer. We analyze the [...] Read more.

This paper introduces an alternative approach to the camber angle measurement for vehicle wheel alignment. Instead of current commercial approaches that apply computation vision techniques, this study aims at realizing a micro-control-unit (MCU)-based camber inspection system with a 3-axis accelerometer. We analyze the precision of the inspection system for the axis misalignments of the accelerometer. The results show that the axes of the accelerometer can be aligned to the axes of the camber inspection system imperfectly. The calibrations that can amend these axis misalignments between the camber inspection system and the accelerometer are also originally proposed since misalignments will usually happen in fabrications of the inspection systems. During camber angle measurements, the x-axis or z-axis of the camber inspection system and the wheel need not be perfectly aligned in the proposed approach. We accomplished two typical authentic camber angle measurements. The results show that the proposed approach is applicable with a precision of

\pm {0.015}^{\circ}

and therefore facilitates the camber measurement process without downgrading the precision by employing an appropriate 3-axis accelerometer. In addition, the measured results of camber angles can be transmitted via the medium such as RS232, Bluetooth, and Wi-Fi. Full article

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

▼ Show Figures

Figure 1

15 pages, 6335 KiB

Open AccessArticle

Real Time Apnoea Monitoring of Children Using the Microsoft Kinect Sensor: A Pilot Study

by Ali Al-Naji^1,2,*

, Kim Gibson³, Sang-Heon Lee¹

and Javaan Chahl^1,4

¹ School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia

² Electrical Engineering Technical College, Middle Technical University, Al Doura 10022, Baghdad, Iraq

³ School of Nursing and Midwifery, University of South Australia, Adelaide, SA 5001, Australia

⁴ Joint and Operations Analysis Division, Defence Science and Technology Group, Melbourne, Victoria 3207, Australia

Sensors 2017, 17(2), 286; https://doi.org/10.3390/s17020286 - 3 Feb 2017

Cited by 70 | Viewed by 13149

Abstract

The objective of this study was to design a non-invasive system for the observation of respiratory rates and detection of apnoea using analysis of real time image sequences captured in any given sleep position and under any light conditions (even in dark environments). [...] Read more.

The objective of this study was to design a non-invasive system for the observation of respiratory rates and detection of apnoea using analysis of real time image sequences captured in any given sleep position and under any light conditions (even in dark environments). A Microsoft Kinect sensor was used to visualize the variations in the thorax and abdomen from the respiratory rhythm. These variations were magnified, analyzed and detected at a distance of 2.5 m from the subject. A modified motion magnification system and frame subtraction technique were used to identify breathing movements by detecting rapid motion areas in the magnified frame sequences. The experimental results on a set of video data from five subjects (3 h for each subject) showed that our monitoring system can accurately measure respiratory rate and therefore detect apnoea in infants and young children. The proposed system is feasible, accurate, safe and low computational complexity, making it an efficient alternative for non-contact home sleep monitoring systems and advancing health care applications. Full article

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

▼ Show Figures

Figure 1

12 pages, 2528 KiB

Open AccessArticle

Diagnosis by Volatile Organic Compounds in Exhaled Breath from Lung Cancer Patients Using Support Vector Machine Algorithm

by Yuichi Sakumura^1,*, Yutaro Koyama¹, Hiroaki Tokutake¹, Toyoaki Hida², Kazuo Sato³, Toshio Itoh⁴, Takafumi Akamatsu⁴ and Woosuck Shin^4,*

¹ Department of Information Science and Technology, Aichi Prefectural University, Nagakute 480-1198, Japan

² Department of Thoracic Oncology, Aichi Cancer Center, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681, Japan

³ Department of Mechanical Engineering, Aichi Institute of Technology, Toyota, 470-0392, Japan

⁴ Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Shimo-Shidami, Moriyama-ku, Nagoya 463-8560, Japan

Sensors 2017, 17(2), 287; https://doi.org/10.3390/s17020287 - 4 Feb 2017

Cited by 105 | Viewed by 12545

Abstract

Monitoring exhaled breath is a very attractive, noninvasive screening technique for early diagnosis of diseases, especially lung cancer. However, the technique provides insufficient accuracy because the exhaled air has many crucial volatile organic compounds (VOCs) at very low concentrations (ppb level). We analyzed [...] Read more.

Monitoring exhaled breath is a very attractive, noninvasive screening technique for early diagnosis of diseases, especially lung cancer. However, the technique provides insufficient accuracy because the exhaled air has many crucial volatile organic compounds (VOCs) at very low concentrations (ppb level). We analyzed the breath exhaled by lung cancer patients and healthy subjects (controls) using gas chromatography/mass spectrometry (GC/MS), and performed a subsequent statistical analysis to diagnose lung cancer based on the combination of multiple lung cancer-related VOCs. We detected 68 VOCs as marker species using GC/MS analysis. We reduced the number of VOCs and used support vector machine (SVM) algorithm to classify the samples. We observed that a combination of five VOCs (CHN, methanol, CH₃CN, isoprene, 1-propanol) is sufficient for 89.0% screening accuracy, and hence, it can be used for the design and development of a desktop GC-sensor analysis system for lung cancer. Full article

(This article belongs to the Special Issue Gas Sensors for Health Care and Medical Applications)

▼ Show Figures

Figure 1

17 pages, 1799 KiB

Open AccessReview

Molecular Imprinting Techniques Used for the Preparation of Biosensors

by Gizem Ertürk^1,* and Bo Mattiasson^1,2

¹ CapSenze Biosystems AB, Lund SE-22363, Sweden

² Department of Biotechnology, Lund University, Lund SE-22369, Sweden

Sensors 2017, 17(2), 288; https://doi.org/10.3390/s17020288 - 4 Feb 2017

Cited by 254 | Viewed by 14594

Abstract

Molecular imprinting is the technology of creating artificial recognition sites in polymeric matrices which are complementary to the template in their size, shape and spatial arrangement of the functional groups. Molecularly imprinted polymers (MIPs) and their incorporation with various transducer platforms are among [...] Read more.

Molecular imprinting is the technology of creating artificial recognition sites in polymeric matrices which are complementary to the template in their size, shape and spatial arrangement of the functional groups. Molecularly imprinted polymers (MIPs) and their incorporation with various transducer platforms are among the most promising approaches for detection of several analytes. There are a variety of molecular imprinting techniques used for the preparation of biomimetic sensors including bulk imprinting, surface imprinting (soft lithography, template immobilization, grafting, emulsion polymerization) and epitope imprinting. This chapter presents an overview of all of these techniques with examples from particular publications. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

▼ Show Figures

Figure 1

16 pages, 2090 KiB

Open AccessArticle

A Novel Physical Layer Assisted Authentication Scheme for Mobile Wireless Sensor Networks

by Qiuhua Wang

School of Cyberspace, Hangzhou Dianzi University, Hangzhou 310018, China

Sensors 2017, 17(2), 289; https://doi.org/10.3390/s17020289 - 4 Feb 2017

Cited by 29 | Viewed by 5104

Abstract

Physical-layer authentication can address physical layer vulnerabilities and security threats in wireless sensor networks, and has been considered as an effective complementary enhancement to existing upper-layer authentication mechanisms. In this paper, to advance the existing research and improve the authentication performance, we propose [...] Read more.

Physical-layer authentication can address physical layer vulnerabilities and security threats in wireless sensor networks, and has been considered as an effective complementary enhancement to existing upper-layer authentication mechanisms. In this paper, to advance the existing research and improve the authentication performance, we propose a novel physical layer assisted authentication scheme for mobile wireless sensor networks. In our proposed scheme, we explore the reciprocity and spatial uncorrelation of the wireless channel to verify the identities of involved transmitting users and decide whether all data frames are from the same sender. In our proposed scheme, a new method is developed for the legitimate users to compare their received signal strength (RSS) records, which avoids the information from being disclosed to the adversary. Our proposed scheme can detect the spoofing attack even in a high dynamic environment. We evaluate our scheme through experiments under indoor and outdoor environments. Experiment results show that our proposed scheme is more efficient and achieves a higher detection rate as well as keeping a lower false alarm rate. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

▼ Show Figures

Figure 1

15 pages, 6501 KiB

Open AccessArticle

A Detailed Algorithm for Vital Sign Monitoring of a Stationary/Non-Stationary Human through IR-UWB Radar

by Faheem Khan

and Sung Ho Cho^*

Department of Electronics and Computer Engineering, Hanyang University, 222 Wangsimini-ro, Seongdong-gu, 133-791 Seoul, Korea

Sensors 2017, 17(2), 290; https://doi.org/10.3390/s17020290 - 4 Feb 2017

Cited by 126 | Viewed by 17714

Abstract

The vital sign monitoring through Impulse Radio Ultra-Wide Band (IR-UWB) radar provides continuous assessment of a patient’s respiration and heart rates in a non-invasive manner. In this paper, IR UWB radar is used for monitoring respiration and the human heart rate. The breathing [...] Read more.

The vital sign monitoring through Impulse Radio Ultra-Wide Band (IR-UWB) radar provides continuous assessment of a patient’s respiration and heart rates in a non-invasive manner. In this paper, IR UWB radar is used for monitoring respiration and the human heart rate. The breathing and heart rate frequencies are extracted from the signal reflected from the human body. A Kalman filter is applied to reduce the measurement noise from the vital signal. An algorithm is presented to separate the heart rate signal from the breathing harmonics. An auto-correlation based technique is applied for detecting random body movements (RBM) during the measurement process. Experiments were performed in different scenarios in order to show the validity of the algorithm. The vital signs were estimated for the signal reflected from the chest, as well as from the back side of the body in different experiments. The results from both scenarios are compared for respiration and heartbeat estimation accuracy. Full article

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

▼ Show Figures

Figure 1

16 pages, 1807 KiB

Open AccessArticle

A Spot Reminder System for the Visually Impaired Based on a Smartphone Camera

by Hotaka Takizawa^1,*

, Kazunori Orita¹, Mayumi Aoyagi², Nobuo Ezaki³ and Shinji Mizuno⁴

¹ University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Ibaraki, Japan

² Aichi University of Education, 1 Hirosawa, Igaya, Kariya 448-8542, Aichi, Japan

³ National Institute of Technology, Toba College, 1-1 Ikegami, Toba 517-8501, Mie, Japan

⁴ Aichi Institute of Technology, 1247 Yachigusa, Yakusa, Toyota 470-0392, Aichi, Japan

Sensors 2017, 17(2), 291; https://doi.org/10.3390/s17020291 - 4 Feb 2017

Cited by 5 | Viewed by 5270

Abstract

The present paper proposes a smartphone-camera-based system to assist visually impaired users in recalling their memories related to important locations, called spots, that they visited. The memories are recorded as voice memos, which can be played back when the users return to the [...] Read more.

The present paper proposes a smartphone-camera-based system to assist visually impaired users in recalling their memories related to important locations, called spots, that they visited. The memories are recorded as voice memos, which can be played back when the users return to the spots. Spot-to-spot correspondence is determined by image matching based on the scale invariant feature transform. The main contribution of the proposed system is to allow visually impaired users to associate arbitrary voice memos with arbitrary spots. The users do not need any special devices or systems except smartphones and do not need to remember the spots where the voice memos were recorded. In addition, the proposed system can identify spots in environments that are inaccessible to the global positioning system. The proposed system has been evaluated by two experiments: image matching tests and a user study. The experimental results suggested the effectiveness of the system to help visually impaired individuals, including blind individuals, recall information about regularly-visited spots. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 2062 KiB

Open AccessArticle

A Multichannel Calorimetric Simultaneous Assay Platform Using a Microampere Constant-Current Looped Enthalpy Sensor Array

by Hsien-Chin Wei¹

, Su-Hua Huang², Joe-Air Jiang^1,3,4 and Yeun-Chung Lee^1,*

¹ Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taipei 10617, Taiwan

² Department of Biotechnology, Asia University, Taichung 41354, Taiwan

³ Education and Research Center for Bio-Industrial Automation, National Taiwan University, Taipei 10617, Taiwan

⁴ Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40447, Taiwan

Sensors 2017, 17(2), 292; https://doi.org/10.3390/s17020292 - 4 Feb 2017

Cited by 2 | Viewed by 4704

Abstract

Calorimetric biochemical measurements offer various advantages such as low waste, low cost, low sample consumption, short operating time, and labor-savings. Multichannel calorimeters can enhance the possibility of performing higher-throughput biochemical measurements. An enthalpy sensor (ES) array is a key device in multichannel calorimeters. [...] Read more.

Calorimetric biochemical measurements offer various advantages such as low waste, low cost, low sample consumption, short operating time, and labor-savings. Multichannel calorimeters can enhance the possibility of performing higher-throughput biochemical measurements. An enthalpy sensor (ES) array is a key device in multichannel calorimeters. Most ES arrays use Wheatstone bridge amplifiers to condition the sensor signals, but such an approach is only suitable for null detection and low resistance sensors. To overcome these limitations, we have developed a multichannel calorimetric simultaneous assay (MCSA) platform. An adjustable microampere constant-current (AMCC) source was designed for exciting the ES array using a microampere current loop measurement circuit topology. The MCSA platform comprises a measurement unit, which contains a multichannel calorimeter and an automatic simultaneous injector, and a signal processing unit, which contains multiple ES signal conditioners and a data processor. This study focused on the construction of the MCSA platform; in particular, construction of the measurement circuit and calorimeter array in a single block. The performance of the platform, including current stability, temperature sensitivity and heat sensitivity, was evaluated. The sensor response time and calorimeter constants were given. The capability of the platform to detect relative enzyme activity was also demonstrated. The experimental results show that the proposed MCSA is a flexible and powerful biochemical measurement device with higher throughput than existing alternatives. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 4610 KiB

Open AccessArticle

G-Channel Restoration for RWB CFA with Double-Exposed W Channel

by Chulhee Park, Ki Sun Song and Moon Gi Kang^*

Yonsei University, Deptartment of Electrical and Electronic Engineering, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

Sensors 2017, 17(2), 293; https://doi.org/10.3390/s17020293 - 5 Feb 2017

Cited by 7 | Viewed by 6325

Abstract

In this paper, we propose a green (G)-channel restoration for a red–white–blue (RWB) color filter array (CFA) image sensor using the dual sampling technique. By using white (W) pixels instead of G pixels, the RWB CFA provides high-sensitivity imaging and an improved signal-to-noise [...] Read more.

In this paper, we propose a green (G)-channel restoration for a red–white–blue (RWB) color filter array (CFA) image sensor using the dual sampling technique. By using white (W) pixels instead of G pixels, the RWB CFA provides high-sensitivity imaging and an improved signal-to-noise ratio compared to the Bayer CFA. However, owing to this high sensitivity, the W pixel values become rapidly over-saturated before the red–blue (RB) pixel values reach the appropriate levels. Because the missing G color information included in the W channel cannot be restored with a saturated W, multiple captures with dual sampling are necessary to solve this early W-pixel saturation problem. Each W pixel has a different exposure time when compared to those of the R and B pixels, because the W pixels are double-exposed. Therefore, a RWB-to-RGB color conversion method is required in order to restore the G color information, using a double-exposed W channel. The proposed G-channel restoration algorithm restores G color information from the W channel by considering the energy difference caused by the different exposure times. Using the proposed method, the RGB full-color image can be obtained while maintaining the high-sensitivity characteristic of the W pixels. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 6014 KiB

Open AccessArticle

Calibration of Laser Beam Direction for Inner Diameter Measuring Device

by Tongyu Yang, Zhong Wang, Zhengang Wu, Xingqiang Li

, Lei Wang and Changjie Liu^*

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(2), 294; https://doi.org/10.3390/s17020294 - 5 Feb 2017

Cited by 31 | Viewed by 9284

Abstract

The laser triangulation method is one of the most advanced methods for large inner diameter measurement. Our research group proposed a kind of inner diameter measuring device that is principally composed of three laser displacement sensors known to be fixed in the same [...] Read more.

The laser triangulation method is one of the most advanced methods for large inner diameter measurement. Our research group proposed a kind of inner diameter measuring device that is principally composed of three laser displacement sensors known to be fixed in the same plane measurement position. It is necessary to calibrate the direction of the laser beams that are emitted by laser displacement sensors because they do not meet the theoretical model accurately. For the purpose of calibrating the direction of laser beams, a calibration method and mathematical model were proposed. The inner diameter measuring device is equipped with the spindle of the machine tool. The laser beams rotate and translate in the plane and constitute the rotary rays which are driven to scan the inner surface of the ring gauge. The direction calibration of the laser beams can be completed by the sensors’ distance information and corresponding data processing method. The corresponding error sources are analyzed and the validity of the method is verified. After the calibration, the measurement error of the inner diameter measuring device reduced from

\pm 25 μ m

to

\pm 15 μ m

and the relative error was not more than 0.011%. Full article

(This article belongs to the Special Issue Laser Sensors for Displacement, Distance, Flow, Velocity and Vibrations Measurements)

▼ Show Figures

Figure 1

21 pages, 8691 KiB

Open AccessArticle

Multichannel and Wide-Angle SAR Imaging Based on Compressed Sensing

by Chao Sun^1,*

, Baoping Wang^2,*, Yang Fang¹

, Zuxun Song¹ and Shuzhen Wang³

¹ School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710129, China

² Science and Technology on UAV Laboratory, Northwestern Polytechnical University, Xi’an 710065, China

³ School of Computer Science and Technology, Xidian University, Xi’an 710071, China

Sensors 2017, 17(2), 295; https://doi.org/10.3390/s17020295 - 5 Feb 2017

Cited by 8 | Viewed by 4506

Abstract

The multichannel or wide-angle imaging performance of synthetic aperture radar (SAR) can be improved by applying the compressed sensing (CS) theory to each channel or sub-aperture image formation independently. However, this not only neglects the complementary information between signals of each channel or [...] Read more.

The multichannel or wide-angle imaging performance of synthetic aperture radar (SAR) can be improved by applying the compressed sensing (CS) theory to each channel or sub-aperture image formation independently. However, this not only neglects the complementary information between signals of each channel or sub-aperture, but also may lead to failure in guaranteeing the consistency of the position of a scatterer in different channel or sub-aperture images which will make the extraction of some scattering information become difficult. By exploiting the joint sparsity of the signal ensemble, this paper proposes a novel CS-based method for joint sparse recovery of all channel or sub-aperture images. Solving the joint sparse recovery problem with a modified orthogonal matching pursuit algorithm, the recovery precision of scatterers is effectively improved and the scattering information is also preserved during the image formation process. Finally, the simulation and real data is used for verifying the effectiveness of the proposed method. Compared with single channel or sub-aperture independent CS processing, the proposed method can not only obtain better imaging performance with fewer measurements, but also preserve more valuable scattering information for target recognition. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

15 pages, 6583 KiB

Open AccessArticle

Real-Time GNSS-Based Attitude Determination in the Measurement Domain

by Lin Zhao¹, Na Li¹, Liang Li^1,2,*, Yi Zhang¹ and Chun Cheng¹

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

² Academy of Opto-electronics, Chinese Academy of Sciences; Beijing 100094, China

Sensors 2017, 17(2), 296; https://doi.org/10.3390/s17020296 - 5 Feb 2017

Cited by 24 | Viewed by 4883

Abstract

A multi-antenna-based GNSS receiver is capable of providing high-precision and drift-free attitude solution. Carrier phase measurements need be utilized to achieve high-precision attitude. The traditional attitude determination methods in the measurement domain and the position domain resolve the attitude and the ambiguity sequentially. [...] Read more.

A multi-antenna-based GNSS receiver is capable of providing high-precision and drift-free attitude solution. Carrier phase measurements need be utilized to achieve high-precision attitude. The traditional attitude determination methods in the measurement domain and the position domain resolve the attitude and the ambiguity sequentially. The redundant measurements from multiple baselines have not been fully utilized to enhance the reliability of attitude determination. A multi-baseline-based attitude determination method in the measurement domain is proposed to estimate the attitude parameters and the ambiguity simultaneously. Meanwhile, the redundancy of attitude resolution has also been increased so that the reliability of ambiguity resolution and attitude determination can be enhanced. Moreover, in order to further improve the reliability of attitude determination, we propose a partial ambiguity resolution method based on the proposed attitude determination model. The static and kinematic experiments were conducted to verify the performance of the proposed method. When compared with the traditional attitude determination methods, the static experimental results show that the proposed method can improve the accuracy by at least 0.03° and enhance the continuity by 18%, at most. The kinematic result has shown that the proposed method can obtain an optimal balance between accuracy and reliability performance. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

16 pages, 11160 KiB

Open AccessArticle

Augmented Reality Tool for the Situational Awareness Improvement of UAV Operators

by Susana Ruano^1,*, Carlos Cuevas¹, Guillermo Gallego²

and Narciso García¹

¹ Grupo de Tratamiento de Imágenes (GTI), Information Processing and Telecommunications Center (IPTC) and ETSI Telecomunicación, Universidad Politécnica de Madrid (UPM), ES-28040 Madrid, Spain

² Robotics and Perception Group, University of Zurich, CH-8050 Zurich, Switzerland

Sensors 2017, 17(2), 297; https://doi.org/10.3390/s17020297 - 6 Feb 2017

Cited by 31 | Viewed by 10372

Abstract

Unmanned Aerial Vehicles (UAVs) are being extensively used nowadays. Therefore, pilots of traditional aerial platforms should adapt their skills to operate them from a Ground Control Station (GCS). Common GCSs provide information in separate screens: one presents the video stream while the other [...] Read more.

Unmanned Aerial Vehicles (UAVs) are being extensively used nowadays. Therefore, pilots of traditional aerial platforms should adapt their skills to operate them from a Ground Control Station (GCS). Common GCSs provide information in separate screens: one presents the video stream while the other displays information about the mission plan and information coming from other sensors. To avoid the burden of fusing information displayed in the two screens, an Augmented Reality (AR) tool is proposed in this paper. The AR system has two functionalities for Medium-Altitude Long-Endurance (MALE) UAVs: route orientation and target identification. Route orientation allows the operator to identify the upcoming waypoints and the path that the UAV is going to follow. Target identification allows a fast target localization, even in the presence of occlusions. The AR tool is implemented following the North Atlantic Treaty Organization (NATO) standards so that it can be used in different GCSs. The experiments show how the AR tool improves significantly the situational awareness of the UAV operators. Full article

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

▼ Show Figures

Figure 1

13 pages, 2971 KiB

Open AccessArticle

Detectability Analysis of Road Vehicles in Radarsat-2 Fully Polarimetric SAR Images for Traffic Monitoring

by Bo Zhang, Chao Wang^*, Hong Zhang

, Fan Wu

and Yi-Xian Tang

Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

Sensors 2017, 17(2), 298; https://doi.org/10.3390/s17020298 - 6 Feb 2017

Cited by 7 | Viewed by 5332

Abstract

By acquiring information over a wide area regardless of weather conditions and solar illumination, space-borne Synthetic Aperture Radar (SAR) has the potential to be a promising application for traffic monitoring. However, the backscatter character of a vehicle in a SAR image is unstable [...] Read more.

By acquiring information over a wide area regardless of weather conditions and solar illumination, space-borne Synthetic Aperture Radar (SAR) has the potential to be a promising application for traffic monitoring. However, the backscatter character of a vehicle in a SAR image is unstable and varies with image parameters, such as aspect and incidence angle. To investigate vehicle detectability in SAR images for traffic monitoring applications, images of four common types of vehicles in China were acquired using the fully polarimetric (FP) SAR of Radarsat-2 in our experiments. Methods for measuring a vehicle’s aspect angle and backscatter intensity are introduced. The experimental FP SAR images are used to analyze the detectability, which is affected by factors such as vehicle size, vehicle shape, and aspect angle. Moreover, a new metric to improve vehicle detectability in FP SAR images is proposed and compared with the well-known intensity metric. The experimental results show that shape is a crucial factor in affecting the backscatter intensity of vehicles, which also oscillates with varying aspect angle. If the size of a vehicle is smaller than the SAR image resolution, using the intensity metric would result in low detectability. However, it could be improved in an FP SAR image by using the proposed metric. Compared with the intensity metric, the overall detectability is improved from 72% to 90% in our experiments. Therefore, this study indicates that FP SAR images have the ability to detect stationary vehicles on the road and are meaningful for traffic monitoring. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

22 pages, 10383 KiB

Open AccessArticle

A 3D Human-Machine Integrated Design and Analysis Framework for Squat Exercises with a Smith Machine

by Haerin Lee¹, Moonki Jung², Ki-Kwang Lee³ and Sang Hun Lee^1,*

¹ Intelligence and Interaction Lab., Graduate School of Automotive Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Korea

² AnyBody Technology A/S, Niels Jernes Vej 10, Aalborg East 9220, Denmark

³ Biomechanics Lab, Department of Sports Science, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Korea

Sensors 2017, 17(2), 299; https://doi.org/10.3390/s17020299 - 6 Feb 2017

Cited by 10 | Viewed by 12896

Abstract

In this paper, we propose a three-dimensional design and evaluation framework and process based on a probabilistic-based motion synthesis algorithm and biomechanical analysis system for the design of the Smith machine and squat training programs. Moreover, we implemented a prototype system to validate [...] Read more.

In this paper, we propose a three-dimensional design and evaluation framework and process based on a probabilistic-based motion synthesis algorithm and biomechanical analysis system for the design of the Smith machine and squat training programs. Moreover, we implemented a prototype system to validate the proposed framework. The framework consists of an integrated human–machine–environment model as well as a squat motion synthesis system and biomechanical analysis system. In the design and evaluation process, we created an integrated model in which interactions between a human body and machine or the ground are modeled as joints with constraints at contact points. Next, we generated Smith squat motion using the motion synthesis program based on a Gaussian process regression algorithm with a set of given values for independent variables. Then, using the biomechanical analysis system, we simulated joint moments and muscle activities from the input of the integrated model and squat motion. We validated the model and algorithm through physical experiments measuring the electromyography (EMG) signals, ground forces, and squat motions as well as through a biomechanical simulation of muscle forces. The proposed approach enables the incorporation of biomechanics in the design process and reduces the need for physical experiments and prototypes in the development of training programs and new Smith machines. Full article

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

▼ Show Figures

Figure 1

19 pages, 618 KiB

Open AccessArticle

RiPPAS: A Ring-Based Privacy-Preserving Aggregation Scheme in Wireless Sensor Networks

by Kejia Zhang¹, Qilong Han^1,*, Zhipeng Cai² and Guisheng Yin¹

¹ College of Computer Science & Technology, Harbin Engineering University, Harbin 150001, China

² Department of Computer Science, Georgia State University, Atlanta, GA 30303, USA

Sensors 2017, 17(2), 300; https://doi.org/10.3390/s17020300 - 7 Feb 2017

Cited by 19 | Viewed by 4832

Abstract

Recently, data privacy in wireless sensor networks (WSNs) has been paid increased attention. The characteristics of WSNs determine that users’ queries are mainly aggregation queries. In this paper, the problem of processing aggregation queries in WSNs with data privacy preservation is investigated. A [...] Read more.

Recently, data privacy in wireless sensor networks (WSNs) has been paid increased attention. The characteristics of WSNs determine that users’ queries are mainly aggregation queries. In this paper, the problem of processing aggregation queries in WSNs with data privacy preservation is investigated. A Ring-based Privacy-Preserving Aggregation Scheme (RiPPAS) is proposed. RiPPAS adopts ring structure to perform aggregation. It uses pseudonym mechanism for anonymous communication and uses homomorphic encryption technique to add noise to the data easily to be disclosed. RiPPAS can handle both

s u m ()

queries and

m i n () / m a x ()

queries, while the existing privacy-preserving aggregation methods can only deal with

s u m ()

queries. For processing

s u m ()

queries, compared with the existing methods, RiPPAS has advantages in the aspects of privacy preservation and communication efficiency, which can be proved by theoretical analysis and simulation results. For processing

m i n () / m a x ()

queries, RiPPAS provides effective privacy preservation and has low communication overhead. Full article

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

▼ Show Figures

Figure 1

21 pages, 1126 KiB

Open AccessArticle

Enabling Secure XMPP Communications in Federated IoT Clouds Through XEP 0027 and SAML/SASL SSO

by Antonio Celesti^1,*

, Maria Fazio² and Massimo Villari^2,3

¹ Scientific Research Organisational Unit, University of Messina, 98122 Messina, Iatly

² Department of Engineering, University of Messina, 98166 Messina, Italy

³ IRCCS Centro Neurolesi Bonino Pulejo, 98124 Messina, Italy

Sensors 2017, 17(2), 301; https://doi.org/10.3390/s17020301 - 7 Feb 2017

Cited by 13 | Viewed by 7765

Abstract

Nowadays, in the panorama of Internet of Things (IoT), finding a right compromise between interactivity and security is not trivial at all. Currently, most of pervasive communication technologies are designed to work locally. As a consequence, the development of large-scale Internet services and [...] Read more.

Nowadays, in the panorama of Internet of Things (IoT), finding a right compromise between interactivity and security is not trivial at all. Currently, most of pervasive communication technologies are designed to work locally. As a consequence, the development of large-scale Internet services and applications is not so easy for IoT Cloud providers. The main issue is that both IoT architectures and services have started as simple but they are becoming more and more complex. Consequently, the web service technology is often inappropriate. Recently, many operators in both academia and industry fields are considering the possibility to adopt the eXtensible Messaging and Presence Protocol (XMPP) for the implementation of IoT Cloud communication systems. In fact, XMPP offers many advantages in term of real-time capabilities, efficient data distribution, service discovery and inter-domain communication compared to other technologies. Nevertheless, the protocol lacks of native security, data confidentiality and trustworthy federation features. In this paper, considering an XMPP-based IoT Cloud architectural model, we discuss how can be possible to enforce message signing/encryption and Single-Sign On (SSO) authentication respectively for secure inter-module and inter-domain communications in a federated environment. Experiments prove that security mechanisms introduce an acceptable overhead, considering the obvious advantages achieved in terms of data trustiness and privacy. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

21 pages, 5957 KiB

Open AccessArticle

A Signal Processing Approach with a Smooth Empirical Mode Decomposition to Reveal Hidden Trace of Corrosion in Highly Contaminated Guided Wave Signals for Concrete-Covered Pipes

by Javad Rostami^*, Jingming Chen and Peter W. Tse

Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China

Sensors 2017, 17(2), 302; https://doi.org/10.3390/s17020302 - 7 Feb 2017

Cited by 38 | Viewed by 7923

Abstract

Ultrasonic guided waves have been extensively applied for non-destructive testing of plate-like structures particularly pipes in past two decades. In this regard, if a structure has a simple geometry, obtained guided waves’ signals are easy to explain. However, any small degree of complexity [...] Read more.

Ultrasonic guided waves have been extensively applied for non-destructive testing of plate-like structures particularly pipes in past two decades. In this regard, if a structure has a simple geometry, obtained guided waves’ signals are easy to explain. However, any small degree of complexity in the geometry such as contacting with other materials may cause an extra amount of complication in the interpretation of guided wave signals. The problem deepens if defects have irregular shapes such as natural corrosion. Signal processing techniques that have been proposed for guided wave signals’ analysis are generally good for simple signals obtained in a highly controlled experimental environment. In fact, guided wave signals in a real situation such as the existence of natural corrosion in wall-covered pipes are much more complicated. Considering pipes in residential buildings that pass through concrete walls, in this paper we introduced Smooth Empirical Mode Decomposition (SEMD) to efficiently separate overlapped guided waves. As empirical mode decomposition (EMD) which is a good candidate for analyzing non-stationary signals, suffers from some shortcomings, wavelet transform was adopted in the sifting stage of EMD to improve its outcome in SEMD. However, selection of mother wavelet that suits best for our purpose plays an important role. Since in guided wave inspection, the incident waves are well known and are usually tone-burst signals, we tailored a complex tone-burst signal to be used as our mother wavelet. In the sifting stage of EMD, wavelet de-noising was applied to eliminate unwanted frequency components from each IMF. SEMD greatly enhances the performance of EMD in guided wave analysis for highly contaminated signals. In our experiment on concrete covered pipes with natural corrosion, this method not only separates the concrete wall indication clearly in time domain signal, a natural corrosion with complex geometry that was hidden and located inside the concrete section was successfully exposed. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

▼ Show Figures

Figure 1

11 pages, 3809 KiB

Open AccessArticle

Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection

by Kwangjae Lee^1,†

, Young-Seok Shim^2,†, Young Geun Song²

, Soo Deok Han^2,3

, Youn-Sung Lee^1,* and Chong-Yun Kang^2,3,*

¹ Contents Convergence Research Center, Korea Electronics Technology Institute (KETI), 11, World cup buk-ro 54-gil, Seoul 03924, Korea

² Center for Electronic Materials, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 136-791, Korea

³ KU-KIST Graduate School of Converging Science and Technology, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 303; https://doi.org/10.3390/s17020303 - 7 Feb 2017

Cited by 43 | Viewed by 8388

Abstract

A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique [...] Read more.

A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique is used to make the highly porous structure such as nanocolumns (NCs) of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO₂, WO₃ and In₂O₃ NCs) is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides) (PVC) decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C), the resistances of the metal-oxide NCs are abruptly changed and SnO₂ NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C). The response time of SnO₂ NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection. Full article

(This article belongs to the Collection Gas Sensors)

▼ Show Figures

Figure 1

19 pages, 11539 KiB

Open AccessArticle

Preliminary Study for Designing a Novel Vein-Visualizing Device

by Donghoon Kim^1,2, Yujin Kim¹, Siyeop Yoon^1,3 and Deukhee Lee^1,3,*

¹ Center for Bionics, Korea Institute of Science and Technology, Seoul 02792, Korea

² Department of Electrical and Computer Engineering, the Ohio State University, Columbus, OH 43210, USA

³ Department of Biomedical Engineering, Korea University of Science and Technology, Deajeon 305-350, Korea

Sensors 2017, 17(2), 304; https://doi.org/10.3390/s17020304 - 7 Feb 2017

Cited by 33 | Viewed by 10887

Abstract

Venipuncture is an important health diagnosis process. Although venipuncture is one of the most commonly performed procedures in medical environments, locating the veins of infants, obese, anemic, or colored patients is still an arduous task even for skilled practitioners. To solve this problem, [...] Read more.

Venipuncture is an important health diagnosis process. Although venipuncture is one of the most commonly performed procedures in medical environments, locating the veins of infants, obese, anemic, or colored patients is still an arduous task even for skilled practitioners. To solve this problem, several devices using infrared light have recently become commercially available. However, such devices for venipuncture share a common drawback, especially when visualizing deep veins or veins of a thick part of the body like the cubital fossa. This paper proposes a new vein-visualizing device applying a new penetration method using near-infrared (NIR) light. The light module is attached directly on to the declared area of the skin. Then, NIR beam is rayed from two sides of the light module to the vein with a specific angle. This gives a penetration effect. In addition, through an image processing procedure, the vein structure is enhanced to show it more accurately. Through a phantom study, the most effective penetration angle of the NIR module is decided. Additionally, the feasibility of the device is verified through experiments in vivo. The prototype allows us to visualize the vein patterns of thicker body parts, such as arms. Full article

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

▼ Show Figures

Figure 1

20 pages, 5987 KiB

Open AccessArticle

A Study on the Influence of Speed on Road Roughness Sensing: The SmartRoadSense Case

by Giacomo Alessandroni, Alberto Carini^*

, Emanuele Lattanzi

, Valerio Freschi and Alessandro Bogliolo

DiSPeA—University of Urbino, 61029 Urbino, Italy

Sensors 2017, 17(2), 305; https://doi.org/10.3390/s17020305 - 7 Feb 2017

Cited by 49 | Viewed by 9793

Abstract

SmartRoadSense is a crowdsensing project aimed at monitoring the conditions of the road surface. Using the sensors of a smartphone, SmartRoadSense monitors the vertical accelerations inside a vehicle traveling the road and extracts a roughness index conveying information about the road conditions. The [...] Read more.

SmartRoadSense is a crowdsensing project aimed at monitoring the conditions of the road surface. Using the sensors of a smartphone, SmartRoadSense monitors the vertical accelerations inside a vehicle traveling the road and extracts a roughness index conveying information about the road conditions. The roughness index and the smartphone GPS data are periodically sent to a central server where they are processed, associated with the specific road, and aggregated with data measured by other smartphones. This paper studies how the smartphone vertical accelerations and the roughness index are related to the vehicle speed. It is shown that the dependence can be locally approximated with a gamma (power) law. Extensive experimental results using data extracted from SmartRoadSense database confirm the gamma law relationship between the roughness index and the vehicle speed. The gamma law is then used for improving the SmartRoadSense data aggregation accounting for the effect of vehicle speed. Full article

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

▼ Show Figures

Figure 1

10 pages, 3612 KiB

Open AccessArticle

Water Plume Temperature Measurements by an Unmanned Aerial System (UAS)

by Anthony DeMario¹, Pete Lopez¹, Eli Plewka¹, Ryan Wix¹, Hai Xia¹, Emily Zamora¹, Dan Gessler^2,* and Azer P. Yalin¹

¹ Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA

² Alden Research Laboratory, Inc. 2000 S. College Ave Suite 300, Fort Collins, CO 80525, USA

Sensors 2017, 17(2), 306; https://doi.org/10.3390/s17020306 - 7 Feb 2017

Cited by 19 | Viewed by 5993

Abstract

We report on the development and testing of a proof of principle water temperature measurement system deployed on an unmanned aerial system (UAS), for field measurements of thermal discharges into water. The primary elements of the system include a quad-copter UAS to which [...] Read more.

We report on the development and testing of a proof of principle water temperature measurement system deployed on an unmanned aerial system (UAS), for field measurements of thermal discharges into water. The primary elements of the system include a quad-copter UAS to which has been integrated, for the first time, both a thermal imaging infrared (IR) camera and an immersible probe that can be dipped below the water surface to obtain vertical water temperature profiles. The IR camera is used to take images of the overall water surface to geo-locate the plume, while the immersible probe provides quantitative temperature depth profiles at specific locations. The full system has been tested including the navigation of the UAS, its ability to safely carry the sensor payload, and the performance of both the IR camera and the temperature probe. Finally, the UAS sensor system was successfully deployed in a pilot field study at a coal burning power plant, and obtained images and temperature profiles of the thermal effluent. Full article

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

▼ Show Figures

Figure 1

21 pages, 2021 KiB

Open AccessArticle

Novel Hierarchical Fall Detection Algorithm Using a Multiphase Fall Model

by Chia-Yeh Hsieh

, Kai-Chun Liu

, Chih-Ning Huang, Woei-Chyn Chu and Chia-Tai Chan^*

Department of Biomedical Engineering, National Yang-Ming University, Taipei 112, Taiwan

Sensors 2017, 17(2), 307; https://doi.org/10.3390/s17020307 - 8 Feb 2017

Cited by 65 | Viewed by 9226

Abstract

Falls are the primary cause of accidents for the elderly in the living environment. Reducing hazards in the living environment and performing exercises for training balance and muscles are the common strategies for fall prevention. However, falls cannot be avoided completely; fall detection [...] Read more.

Falls are the primary cause of accidents for the elderly in the living environment. Reducing hazards in the living environment and performing exercises for training balance and muscles are the common strategies for fall prevention. However, falls cannot be avoided completely; fall detection provides an alarm that can decrease injuries or death caused by the lack of rescue. The automatic fall detection system has opportunities to provide real-time emergency alarms for improving the safety and quality of home healthcare services. Two common technical challenges are also tackled in order to provide a reliable fall detection algorithm, including variability and ambiguity. We propose a novel hierarchical fall detection algorithm involving threshold-based and knowledge-based approaches to detect a fall event. The threshold-based approach efficiently supports the detection and identification of fall events from continuous sensor data. A multiphase fall model is utilized, including free fall, impact, and rest phases for the knowledge-based approach, which identifies fall events and has the potential to deal with the aforementioned technical challenges of a fall detection system. Seven kinds of falls and seven types of daily activities arranged in an experiment are used to explore the performance of the proposed fall detection algorithm. The overall performances of the sensitivity, specificity, precision, and accuracy using a knowledge-based algorithm are 99.79%, 98.74%, 99.05% and 99.33%, respectively. The results show that the proposed novel hierarchical fall detection algorithm can cope with the variability and ambiguity of the technical challenges and fulfill the reliability, adaptability, and flexibility requirements of an automatic fall detection system with respect to the individual differences. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

▼ Show Figures

Figure 1

14 pages, 3765 KiB

Open AccessArticle

A Miniature Magnetic-Force-Based Three-Axis AC Magnetic Sensor with Piezoelectric/Vibrational Energy-Harvesting Functions

by Chiao-Fang Hung¹, Po-Chen Yeh¹ and Tien-Kan Chung^1,2,*

¹ Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

² International College of Semiconductor Technology, National Chiao Tung University, Hsinchu 30010, Taiwan

Sensors 2017, 17(2), 308; https://doi.org/10.3390/s17020308 - 8 Feb 2017

Cited by 16 | Viewed by 8963

Abstract

In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic–mechanical–piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x [...] Read more.

In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic–mechanical–piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x-axis and y-axis in-plane and z-axis magnetic fields into piezoelectric voltage outputs. Under the x-axis magnetic field (sine-wave, 100 Hz, 0.2–3.2 gauss) and the z-axis magnetic field (sine-wave, 142 Hz, 0.2–3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13–26.15 mV with 8.79 mV/gauss and 1.31–8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x-axis vibration (sine-wave, 100 Hz, 3.5 g) and z-axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on. Full article

(This article belongs to the Special Issue Autonomous Sensors)

▼ Show Figures

Figure 1

17 pages, 2716 KiB

Open AccessArticle

GaitKeeper: A System for Measuring Canine Gait

by Cassim Ladha^1,*, Jack O’Sullivan¹, Zoe Belshaw²

and Lucy Asher¹

¹ Centre for Behaviour and Evolution, Henry Wellcome Building, Newcastle University, Newcastle NE2 4HH, UK

² School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK

Sensors 2017, 17(2), 309; https://doi.org/10.3390/s17020309 - 8 Feb 2017

Cited by 19 | Viewed by 10568

Abstract

It is understood gait has the potential to be used as a window into neurodegenerative disorders, identify markers of subclinical pathology, inform diagnostic algorithms of disease progression and measure the efficacy of interventions. Dogs’ gaits are frequently assessed in a veterinary setting to [...] Read more.

It is understood gait has the potential to be used as a window into neurodegenerative disorders, identify markers of subclinical pathology, inform diagnostic algorithms of disease progression and measure the efficacy of interventions. Dogs’ gaits are frequently assessed in a veterinary setting to detect signs of lameness. Despite this, a reliable, affordable and objective method to assess lameness in dogs is lacking. Most described canine lameness assessments are subjective, unvalidated and at high risk of bias. This means reliable, early detection of canine gait abnormalities is challenging, which may have detrimental implications for dogs’ welfare. In this paper, we draw from approaches and technologies used in human movement science and describe a system for objectively measuring temporal gait characteristics in dogs (step-time, swing-time, stance-time). Asymmetries and variabilities in these characteristics are of known clinical significance when assessing lameness but presently may only be assessed on coarse scales or under highly instrumented environments. The system consists an inertial measurement unit, containing a 3-axis accelerometer and gyroscope coupled with a standardized walking course. The measurement unit is attached to each leg of the dog under assessment before it is walked around the course. The data by the measurement unit is then processed to identify steps and subsequently, micro-gait characteristics. This method has been tested on a cohort of 19 healthy dogs of various breeds ranging in height from 34.2 cm to 84.9 cm. We report the system as capable of making precise step delineations with detections of initial and final contact times of foot-to-floor to a mean precision of 0.011 s and 0.048 s, respectively. Results are based on analysis of 12,678 foot falls and we report a sensitivity, positive predictive value and F-score of 0.81, 0.83 and 0.82 respectively. To investigate the effect of gait on system performance, the approach was tested in both walking and trotting with no significant performance deviation with 7249 steps reported for a walking gait and 4977 for a trotting gait. The number of steps reported for each leg were approximately equal and this consistency was true in both walking and trotting gaits. In the walking gait 1965, 1790, 1726 and 1768 steps were reported for the front left, front right, hind left and hind right legs respectively. 1361, 1250, 1176 and 1190 steps were reported for each of the four legs in the trotting gait. The proposed system is a pragmatic and precise solution for obtaining objective measurements of canine gait. With further development, it promises potential for a wide range of applications in both research and clinical practice. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

15 pages, 1895 KiB

Open AccessArticle

Dynamic Voltage-Frequency and Workload Joint Scaling Power Management for Energy Harvesting Multi-Core WSN Node SoC

by Xiangyu Li^*

, Nijie Xie and Xinyue Tian

Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(2), 310; https://doi.org/10.3390/s17020310 - 8 Feb 2017

Cited by 9 | Viewed by 5041

Abstract

This paper proposes a scheduling and power management solution for energy harvesting heterogeneous multi-core WSN node SoC such that the system continues to operate perennially and uses the harvested energy efficiently. The solution consists of a heterogeneous multi-core system oriented task scheduling algorithm [...] Read more.

This paper proposes a scheduling and power management solution for energy harvesting heterogeneous multi-core WSN node SoC such that the system continues to operate perennially and uses the harvested energy efficiently. The solution consists of a heterogeneous multi-core system oriented task scheduling algorithm and a low-complexity dynamic workload scaling and configuration optimization algorithm suitable for light-weight platforms. Moreover, considering the power consumption of most WSN applications have the characteristic of data dependent behavior, we introduce branches handling mechanism into the solution as well. The experimental result shows that the proposed algorithm can operate in real-time on a lightweight embedded processor (MSP430), and that it can make a system do more valuable works and make more than 99.9% use of the power budget. Full article

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

▼ Show Figures

Figure 1

19 pages, 6178 KiB

Open AccessArticle

Hybrid Analytical and Data-Driven Modeling for Feed-Forward Robot Control †

by René Felix Reinhart¹

, Zeeshan Shareef^2,* and Jochen Jakob Steil²

¹ Fraunhofer Research Institute for Mechatronic Systems Design (IEM), Zukunftsmeile 1, 33102 Paderborn, Germany

² Institute for Robotics and Process Control (IRP), Technische Universität Braunschweig, Mühlenpfordstraße 23, 38106 Braunschweig, Germany

Sensors 2017, 17(2), 311; https://doi.org/10.3390/s17020311 - 8 Feb 2017

Cited by 70 | Viewed by 12155

Abstract

Feed-forward model-based control relies on models of the controlled plant, e.g., in robotics on accurate knowledge of manipulator kinematics or dynamics. However, mechanical and analytical models do not capture all aspects of a plant’s intrinsic properties and there remain unmodeled dynamics due to [...] Read more.

Feed-forward model-based control relies on models of the controlled plant, e.g., in robotics on accurate knowledge of manipulator kinematics or dynamics. However, mechanical and analytical models do not capture all aspects of a plant’s intrinsic properties and there remain unmodeled dynamics due to varying parameters, unmodeled friction or soft materials. In this context, machine learning is an alternative suitable technique to extract non-linear plant models from data. However, fully data-based models suffer from inaccuracies as well and are inefficient if they include learning of well known analytical models. This paper thus argues that feed-forward control based on hybrid models comprising an analytical model and a learned error model can significantly improve modeling accuracy. Hybrid modeling here serves the purpose to combine the best of the two modeling worlds. The hybrid modeling methodology is described and the approach is demonstrated for two typical problems in robotics, i.e., inverse kinematics control and computed torque control. The former is performed for a redundant soft robot and the latter for a rigid industrial robot with redundant degrees of freedom, where a complete analytical model is not available for any of the platforms. Full article

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

▼ Show Figures

Figure 1

16 pages, 835 KiB

Open AccessArticle

Basic Send-on-Delta Sampling for Signal Tracking-Error Reduction

by Miguel Diaz-Cacho^1,*,†,‡

, Emma Delgado^2,†,‡

, Antonio Barreiro^2,†,‡ and Pablo Falcón^2,†,‡

¹ School of Computer Engineering, Campus de Ourense, Edificio Politecnico, 32004 Ourense, Spain

² School of Industrial Engineering, Campus Lagoas-Marcosende, 36310 Vigo, Spain

^† Systems Engineering and Automation, University of Vigo, 36310 Vigo, Spain.

^‡ These authors contributed equally to this work.

Sensors 2017, 17(2), 312; https://doi.org/10.3390/s17020312 - 8 Feb 2017

Cited by 16 | Viewed by 4416

Abstract

This paper investigates the dynamic selection of an appropriate threshold for basic Send-on-Delta (SoD) sampling strategies, given an available transmission rate to reduce the signal tracking-error. The paper formulates the error-reduction principle and proposes an algorithm that calculates, in real time, the amplitude [...] Read more.

This paper investigates the dynamic selection of an appropriate threshold for basic Send-on-Delta (SoD) sampling strategies, given an available transmission rate to reduce the signal tracking-error. The paper formulates the error-reduction principle and proposes an algorithm that calculates, in real time, the amplitude threshold value (also called delta value) for a desired mean transmission rate. The algorithm is implemented to be computed in a Send-on-Delta driver and is tested with three signals that match the step response of a second order control system. Comparison results with a conformant periodic transmission strategy reveals that it improves deeply the tracking-error while maintaining the desired average throughput. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

34 pages, 11798 KiB

Open AccessReview

A Survey on Banknote Recognition Methods by Various Sensors

by Ji Woo Lee, Hyung Gil Hong, Ki Wan Kim and Kang Ryoung Park^*

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

Sensors 2017, 17(2), 313; https://doi.org/10.3390/s17020313 - 8 Feb 2017

Cited by 61 | Viewed by 19491

Abstract

Despite a decrease in the use of currency due to the recent growth in the use of electronic financial transactions, real money transactions remain very important in the global market. While performing transactions with real money, touching and counting notes by hand, is [...] Read more.

Despite a decrease in the use of currency due to the recent growth in the use of electronic financial transactions, real money transactions remain very important in the global market. While performing transactions with real money, touching and counting notes by hand, is still a common practice in daily life, various types of automated machines, such as ATMs and banknote counters, are essential for large-scale and safe transactions. This paper presents studies that have been conducted in four major areas of research (banknote recognition, counterfeit banknote detection, serial number recognition, and fitness classification) in the accurate banknote recognition field by various sensors in such automated machines, and describes the advantages and drawbacks of the methods presented in those studies. While to a limited extent some surveys have been presented in previous studies in the areas of banknote recognition or counterfeit banknote recognition, this paper is the first of its kind to review all four areas. Techniques used in each of the four areas recognize banknote information (denomination, serial number, authenticity, and physical condition) based on image or sensor data, and are actually applied to banknote processing machines across the world. This study also describes the technological challenges faced by such banknote recognition techniques and presents future directions of research to overcome them. Full article

(This article belongs to the Special Issue Human Detection, Identification, and Recognition of Gesture and Behavior based on Thermal Camera)

▼ Show Figures

Figure 1

19 pages, 1081 KiB

Open AccessArticle

Hyperspectral Image Classification with Spatial Filtering and \(l_{(2,1)}\) Norm

by Hao Li¹

, Chang Li^2,*

, Cong Zhang¹, Zhe Liu²

and Chengyin Liu²

¹ School of Mathematics and Computer Science, Wuhan Polytechnic University, Wuhan 430023, China

² School of Electronic Information and Communications, Huazhong University of Science and Technology, Wuhan 430074, China

Sensors 2017, 17(2), 314; https://doi.org/10.3390/s17020314 - 8 Feb 2017

Cited by 16 | Viewed by 4535

Abstract

Recently, the sparse representation based classification methods have received particular attention in the classification of hyperspectral imagery. However, current sparse representation based classification models have not considered all the test pixels simultaneously. In this paper, we propose a hyperspectral classification method with spatial [...] Read more.

Recently, the sparse representation based classification methods have received particular attention in the classification of hyperspectral imagery. However, current sparse representation based classification models have not considered all the test pixels simultaneously. In this paper, we propose a hyperspectral classification method with spatial filtering and \(l_{(2,1)}\) norm (SFL) that can deal with all the test pixels simultaneously. The \(l_{(2,1)}\) norm regularization is used to extract relevant training samples among the whole training data set with joint sparsity. In addition, the \(l_{(2,1)}\) norm loss function is adopted to make it robust for samples that deviate significantly from the rest of the samples. Moreover, to take the spatial information into consideration, a spatial filtering step is implemented where all the training and testing samples are spatially averaged with its nearest neighbors. Furthermore, the non-negative constraint is added to the sparse representation matrix motivated by hyperspectral unmixing. Finally, the alternating direction method of multipliers is used to solve SFL. Experiments on real hyperspectral images demonstrate that the proposed SFL method can obtain better classification performance than some other popular classifiers. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

14 pages, 4518 KiB

Open AccessArticle

Depicting Binding-Mediated Translocation of HIV-1 Tat Peptides in Living Cells with Nanoscale Pens of Tat-Conjugated Quantum Dots

by Chien Y. Lin^1,†, Jung Y. Huang^1,*,† and Leu-Wei Lo^2,†

¹ The T.K.P. Research Center for Photonics, Chiao Tung University, Hsinchu 300, Taiwan

² Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan 350, Taiwan

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 315; https://doi.org/10.3390/s17020315 - 10 Feb 2017

Cited by 4 | Viewed by 4291

Abstract

Cell-penetrating peptides (CPPs) can translocate across cell membranes, and thus have great potential for the cellular delivery of macromolecular cargoes. However, the mechanism of this cellular uptake process is not yet fully understood. In this study, a time-lapse single-particle light-sheet microscopy technique was [...] Read more.

Cell-penetrating peptides (CPPs) can translocate across cell membranes, and thus have great potential for the cellular delivery of macromolecular cargoes. However, the mechanism of this cellular uptake process is not yet fully understood. In this study, a time-lapse single-particle light-sheet microscopy technique was implemented to obtain a parallel visualization of the translocating process of individual human immunodeficiency virus 1 (HIV-1) transactivator of transcription (Tat) peptide conjugated quantum dots (TatP-QDs) in complex cellular terrains. Here, TatP-QDs served as nanoscale dynamic pens, which depict remarkable trajectory aggregates of TatP-QDs on the cell surface. Spectral-embedding analysis of the trajectory aggregates revealed a manifold formed by isotropic diffusion and a fraction of directed movement, possibly caused by interaction between the Tat peptides and heparan sulfate groups on the plasma membrane. Further analysis indicated that the membrane deformation induced by Tat-peptide attachment increased with the disruption of the actin framework in cytochalasin D (cyto D)-treated cells, yielding higher interactions on the TatP-QDs. In native cells, the Tat peptides can remodel the actin framework to reduce their interaction with the local membrane environment. Characteristic hot spots for interaction were detected on the membrane, suggesting that a funnel passage may have formed for the Tat-coated particles. This finding offers valuable insight into the cellular delivery of nanoscale cargo, suggesting an avenue for direct therapeutic delivery. Full article

(This article belongs to the Special Issue Single-Molecule Sensing)

▼ Show Figures

Figure 1

16 pages, 593 KiB

Open AccessArticle

Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks

by Guangjie Han^1,*

, Shanshan Li¹, Chunsheng Zhu², Jinfang Jiang¹ and Wenbo Zhang³

¹ Department of Information and Communication Systems, Hohai University, 200 North Jinling Road, Changzhou 213022, China

² Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada

³ School of Information Science and Engineering, Shenyang Ligong University, China

Sensors 2017, 17(2), 316; https://doi.org/10.3390/s17020316 - 8 Feb 2017

Cited by 21 | Viewed by 5297

Abstract

Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information [...] Read more.

Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency. Full article

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

▼ Show Figures

Figure 1

22 pages, 11219 KiB

Open AccessArticle

Towards Building a Computer Aided Education System for Special Students Using Wearable Sensor Technologies

by Raja Majid Mehmood¹ and Hyo Jong Lee^1,2,*

¹ Division of Computer Science and Engineering, Chonbuk National University, Jeonju 54896, Korea

² Center for Advanced Image and Information Technology, Chonbuk National University, Jeonju 54896, Korea

Sensors 2017, 17(2), 317; https://doi.org/10.3390/s17020317 - 8 Feb 2017

Cited by 31 | Viewed by 8111

Abstract

Human computer interaction is a growing field in terms of helping people in their daily life to improve their living. Especially, people with some disability may need an interface which is more appropriate and compatible with their needs. Our research is focused on [...] Read more.

Human computer interaction is a growing field in terms of helping people in their daily life to improve their living. Especially, people with some disability may need an interface which is more appropriate and compatible with their needs. Our research is focused on similar kinds of problems, such as students with some mental disorder or mood disruption problems. To improve their learning process, an intelligent emotion recognition system is essential which has an ability to recognize the current emotional state of the brain. Nowadays, in special schools, instructors are commonly use some conventional methods for managing special students for educational purposes. In this paper, we proposed a novel computer aided method for instructors at special schools where they can teach special students with the support of our system using wearable technologies. Full article

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

▼ Show Figures

Figure 1

12 pages, 10744 KiB

Open AccessArticle

Online Condition Monitoring of a Rail Fastening System on High-Speed Railways Based on Wavelet Packet Analysis

by Jiahong Wei¹

, Chong Liu^1,2, Tongqun Ren^1,*, Haixia Liu² and Wenjing Zhou³

¹ Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China

² Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116024, China

³ The 45th Research Institute of CETC, Beijing 100176, China

Sensors 2017, 17(2), 318; https://doi.org/10.3390/s17020318 - 8 Feb 2017

Cited by 46 | Viewed by 8857

Abstract

The rail fastening system is an important part of a high-speed railway track. It is always critical to the operational safety and comfort of railway vehicles. Therefore, the condition detection of the rail fastening system, looseness or absence, is an important task in [...] Read more.

The rail fastening system is an important part of a high-speed railway track. It is always critical to the operational safety and comfort of railway vehicles. Therefore, the condition detection of the rail fastening system, looseness or absence, is an important task in railway maintenance. However, the vision-based method cannot identify the severity of rail fastener looseness. In this paper, the condition of rail fastening system is monitored based on an automatic and remote-sensing measurement system. Meanwhile, wavelet packet analysis is used to analyze the acceleration signals, based on which two damage indices are developed to locate the damage position and evaluate the severity of rail fasteners looseness, respectively. To verify the effectiveness of the proposed method, an experiment is performed on a high-speed railway experimental platform. The experimental results show that the proposed method is effective to assess the condition of the rail fastening system. The monitoring system significantly reduces the inspection time and increases the efficiency of maintenance management. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

▼ Show Figures

Figure 1

18 pages, 3363 KiB

Open AccessArticle

Time-Elastic Generative Model for Acceleration Time Series in Human Activity Recognition

by Mario Munoz-Organero^*

and Ramona Ruiz-Blazquez

Telematics Engineering Department, Universidad Carlos III de Madrid; Av. Universidad, 30, 28911 Leganes, Spain

Sensors 2017, 17(2), 319; https://doi.org/10.3390/s17020319 - 8 Feb 2017

Cited by 21 | Viewed by 6113

Abstract

Body-worn sensors in general and accelerometers in particular have been widely used in order to detect human movements and activities. The execution of each type of movement by each particular individual generates sequences of time series of sensed data from which specific movement [...] Read more.

Body-worn sensors in general and accelerometers in particular have been widely used in order to detect human movements and activities. The execution of each type of movement by each particular individual generates sequences of time series of sensed data from which specific movement related patterns can be assessed. Several machine learning algorithms have been used over windowed segments of sensed data in order to detect such patterns in activity recognition based on intermediate features (either hand-crafted or automatically learned from data). The underlying assumption is that the computed features will capture statistical differences that can properly classify different movements and activities after a training phase based on sensed data. In order to achieve high accuracy and recall rates (and guarantee the generalization of the system to new users), the training data have to contain enough information to characterize all possible ways of executing the activity or movement to be detected. This could imply large amounts of data and a complex and time-consuming training phase, which has been shown to be even more relevant when automatically learning the optimal features to be used. In this paper, we present a novel generative model that is able to generate sequences of time series for characterizing a particular movement based on the time elasticity properties of the sensed data. The model is used to train a stack of auto-encoders in order to learn the particular features able to detect human movements. The results of movement detection using a newly generated database with information on five users performing six different movements are presented. The generalization of results using an existing database is also presented in the paper. The results show that the proposed mechanism is able to obtain acceptable recognition rates (F = 0.77) even in the case of using different people executing a different sequence of movements and using different hardware. Full article

(This article belongs to the Special Issue Body Worn Behavior Sensing)

▼ Show Figures

Figure 1

10 pages, 2223 KiB

Open AccessArticle

Investigation of Pristine Graphite Oxide as Room-Temperature Chemiresistive Ammonia Gas Sensing Material

by Alexander G. Bannov¹

, Jan Prášek^2,*, Ondřej Jašek³ and Lenka Zajíčková^3,4

¹ Department of Chemistry and Chemical Technology, Novosibirsk State Technical University, K. Marx 20, RU-630073 Novosibirsk, Russia

² SIX Research Centre, Brno University of Technology, Technická 10, CZ-61600 Brno, Czech Republic

³ Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic

⁴ RG Plasma Technologies, CEITEC—Central European Institute of Technology, Masaryk University, Purkyňova 123, CZ-61200 Brno, Czech Republic

Sensors 2017, 17(2), 320; https://doi.org/10.3390/s17020320 - 9 Feb 2017

Cited by 62 | Viewed by 9576

Abstract

Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray [...] Read more.

Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10–1000 ppm) and under different relative humidity levels (3%–65%). It was concluded that the graphite oxide–based sensor possessed a good response to NH₃ in dry synthetic air (ΔR/R₀ ranged from 2.5% to 7.4% for concentrations of 100–500 ppm and 3% relative humidity) with negligible cross-sensitivity towards H₂ and CH₄. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level. Full article

(This article belongs to the Special Issue Gas Nanosensors)

▼ Show Figures

Figure 1

24 pages, 6608 KiB

Open AccessArticle

Intelligent Luminance Control of Lighting Systems Based on Imaging Sensor Feedback

by Haoting Liu¹

, Qianxiang Zhou^1,*

, Jin Yang², Ting Jiang², Zhizhen Liu² and Jie Li²

¹ School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China

² Astronaut Research and Training Center of China, Beijing 100094, China

Sensors 2017, 17(2), 321; https://doi.org/10.3390/s17020321 - 9 Feb 2017

Cited by 19 | Viewed by 6585

Abstract

An imaging sensor-based intelligent Light Emitting Diode (LED) lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of [...] Read more.

An imaging sensor-based intelligent Light Emitting Diode (LED) lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of the environmental light; thus it can guide a more precise lighting control. Before this system works, first lots of typical imaging lighting data of the desk application are accumulated. Second, a series of subjective and objective Lighting Effect Evaluation Metrics (LEEMs) are defined and assessed for these datasets above. Then the cluster benchmarks of these objective LEEMs can be obtained. Third, both a single LEEM-based control and a multiple LEEMs-based control are developed to realize a kind of optimal luminance tuning. When this system works, first it captures the lighting image using a wearable camera. Then it computes the objective LEEMs of the captured image and compares them with the cluster benchmarks of the objective LEEMs. Finally, the single LEEM-based or the multiple LEEMs-based control can be implemented to get a kind of optimal lighting effect. Many experiment results have shown the proposed system can tune the LED lamp automatically according to environment luminance changes. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 6739 KiB

Open AccessArticle

A Study on the Thermomechanical Reliability Risks of Through-Silicon-Vias in Sensor Applications

by Shuai Shao^1,*,†

, Dapeng Liu^1,*,†, Yuling Niu¹, Kathy O’Donnell², Dipak Sengupta² and Seungbae Park¹

¹ Department of Mechanical Engineering, State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902, USA

² Analog Devices, Inc., Wilmington, MA 01887, USA

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 322; https://doi.org/10.3390/s17020322 - 9 Feb 2017

Cited by 10 | Viewed by 8693

Abstract

Reliability risks for two different types of through-silicon-vias (TSVs) are discussed in this paper. The first is a partially-filled copper TSV, if which the copper layer covers the side walls and bottom. A polymer is used to fill the rest of the cavity. [...] Read more.

Reliability risks for two different types of through-silicon-vias (TSVs) are discussed in this paper. The first is a partially-filled copper TSV, if which the copper layer covers the side walls and bottom. A polymer is used to fill the rest of the cavity. Stresses in risk sites are studied and ranked for this TSV structure by FEA modeling. Parametric studies for material properties (modulus and thermal expansion) of TSV polymer are performed. The second type is a high aspect ratio TSV filled by polycrystalline silicon (poly Si). Potential risks of the voids in the poly Si due to filling defects are studied. Fracture mechanics methods are utilized to evaluate the risk for two different assembly conditions: package assembled to printed circuit board (PCB) and package assembled to flexible substrate. The effect of board/substrate/die thickness and the size and location of the void are discussed. Full article

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

▼ Show Figures

Figure 1

15 pages, 6815 KiB

Open AccessArticle

BeiDou Signal Acquisition with Neumann–Hoffman Code Modulation in a Degraded Channel

by Lin Zhao, Aimeng Liu, Jicheng Ding^* and Jing Wang

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

Sensors 2017, 17(2), 323; https://doi.org/10.3390/s17020323 - 9 Feb 2017

Cited by 5 | Viewed by 6843

Abstract

With the modernization of global navigation satellite systems (GNSS), secondary codes, also known as the Neumann–Hoffman (NH) codes, are modulated on the satellite signal to obtain a better positioning performance. However, this leads to an attenuation of the acquisition sensitivity of classic integration [...] Read more.

With the modernization of global navigation satellite systems (GNSS), secondary codes, also known as the Neumann–Hoffman (NH) codes, are modulated on the satellite signal to obtain a better positioning performance. However, this leads to an attenuation of the acquisition sensitivity of classic integration algorithms because of the frequent bit transitions that refer to the NH codes. Taking weak BeiDou navigation satellite system (BDS) signals as objects, the present study analyzes the side effect of NH codes on acquisition in detail and derives a straightforward formula, which indicates that bit transitions decrease the frequency accuracy. To meet the requirement of carrier-tracking loop initialization, a frequency recalculation algorithm is proposed based on verified fast Fourier transform (FFT) to mitigate the effect, meanwhile, the starting point of NH codes is found. Then, a differential correction is utilized to improve the acquisition accuracy of code phase. Monte Carlo simulations and real BDS data tests demonstrate that the new structure is superior to the conventional algorithms both in detection probability and frequency accuracy in a degraded channel. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

17 pages, 908 KiB

Open AccessArticle

mDARAL: A Multi-Radio Version for the DARAL Routing Algorithm

by Francisco José Estévez^1,2,*

, José María Castillo-Secilla³

, Jesús González²

, Joaquín Olivares⁴

and Peter Glösekötter¹

¹ Department of Electrical Engineering and Computer Science, University of Applied Sciences of Münster, Stegerwaldstr. 39, D-48565 Steinfurt, Germany

² Department of Computer Architecture and Technology, University of Granada, Periodista Daniel Saucedo Aranda, S/N, 18071 Granada, Spain

³ Department of Computer Technology, University of Alicante, Carretera San Vicente del Raspeig, S/N, 03690 Alicante, Spain

⁴ Department of Computer Architecture and Technology, University of Cordoba, Campus de Rabanales, 14001 Cordoba, Spain

Sensors 2017, 17(2), 324; https://doi.org/10.3390/s17020324 - 9 Feb 2017

Cited by 3 | Viewed by 4296

Abstract

Smart Cities are called to change the daily life of human beings. This concept permits improving the efficiency of our cities in several areas such as the use of water, energy consumption, waste treatment, and mobility both for people as well as vehicles [...] Read more.

Smart Cities are called to change the daily life of human beings. This concept permits improving the efficiency of our cities in several areas such as the use of water, energy consumption, waste treatment, and mobility both for people as well as vehicles throughout the city. This represents an interconnected scenario in which thousands of embedded devices need to work in a collaborative way both for sensing and modifying the environment properly. Under this scenario, the majority of devices will use wireless protocols for communicating among them, representing a challenge for optimizing the use of the electromagnetic spectrum. When the density of deployed nodes increases, the competition for using the physical medium becomes harder and, in consequence, traffic collisions will be higher, affecting data-rates in the communication process. This work presents mDARAL, a multi-radio routing algorithm based on the Dynamic and Adaptive Radio Algorithm (DARAL), which has the capability of isolating groups of nodes into sub-networks. The nodes of each sub-network will communicate among them using a dedicated radio frequency, thus isolating the use of the radio channel to a reduced number of nodes. Each sub-network will have a master node with two physical radios, one for communicating with its neighbours and the other for being the contact point among its group and other sub-networks. The communication among sub-networks is done through master nodes in a dedicated radio frequency. The algorithm works to maximize the overall performance of the network through the distribution of the traffic messages into unoccupied frequencies. The obtained results show that mDARAL achieves great improvement in terms of the number of control messages necessary to connect a node to the network, convergence time and energy consumption during the connection phase compared to DARAL. Full article

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

▼ Show Figures

Figure 1

26 pages, 1653 KiB

Open AccessArticle

Improved Omnidirectional Odometry for a View-Based Mapping Approach

by David Valiente^1,*

, Arturo Gil¹, Óscar Reinoso¹

, Miguel Juliá² and Mathew Holloway³

¹ System Engineering and Automation Department, Miguel Hernández University, Elche (Alicante) 03202, Spain

² Q-Bot Ltd., Riverside Business Park, London SW18 4UQ, UK

³ Dyson School of Design Engineering, Imperial College, London SW7 1NA, UK

Sensors 2017, 17(2), 325; https://doi.org/10.3390/s17020325 - 9 Feb 2017

Cited by 20 | Viewed by 7613

Abstract

This work presents an improved visual odometry using omnidirectional images. The main purpose is to generate a reliable prior input which enhances the SLAM (Simultaneous Localization and Mapping) estimation tasks within the framework of navigation in mobile robotics, in detriment of the internal [...] Read more.

This work presents an improved visual odometry using omnidirectional images. The main purpose is to generate a reliable prior input which enhances the SLAM (Simultaneous Localization and Mapping) estimation tasks within the framework of navigation in mobile robotics, in detriment of the internal odometry data. Generally, standard SLAM approaches extensively use data such as the main prior input to localize the robot. They also tend to consider sensory data acquired with GPSs, lasers or digital cameras, as the more commonly acknowledged to re-estimate the solution. Nonetheless, the modeling of the main prior is crucial, and sometimes especially challenging when it comes to non-systematic terms, such as those associated with the internal odometer, which ultimately turn to be considerably injurious and compromise the convergence of the system. This omnidirectional odometry relies on an adaptive feature point matching through the propagation of the current uncertainty of the system. Ultimately, it is fused as the main prior input in an EKF (Extended Kalman Filter) view-based SLAM system, together with the adaption of the epipolar constraint to the omnidirectional geometry. Several improvements have been added to the initial visual odometry proposal so as to produce better performance. We present real data experiments to test the validity of the proposal and to demonstrate its benefits, in contrast to the internal odometry. Furthermore, SLAM results are included to assess its robustness and accuracy when using the proposed prior omnidirectional odometry. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 2242 KiB

Open AccessArticle

Development and Experimental Validation of a Dry Non-Invasive Multi-Channel Mouse Scalp EEG Sensor through Visual Evoked Potential Recordings

by Donghyeon Kim¹

, Chanmi Yeon² and Kiseon Kim^1,*

¹ School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

² Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

Sensors 2017, 17(2), 326; https://doi.org/10.3390/s17020326 - 9 Feb 2017

Cited by 11 | Viewed by 8719

Abstract

In this paper, we introduce a dry non-invasive multi-channel sensor for measuring brainwaves on the scalps of mice. The research on laboratory animals provide insights to various practical applications involving human beings and other animals such as working animals, pets, and livestock. An [...] Read more.

In this paper, we introduce a dry non-invasive multi-channel sensor for measuring brainwaves on the scalps of mice. The research on laboratory animals provide insights to various practical applications involving human beings and other animals such as working animals, pets, and livestock. An experimental framework targeting the laboratory animals has the potential to lead to successful translational research when it closely resembles the environment of real applications. To serve scalp electroencephalography (EEG) research environments for the laboratory mice, the dry non-invasive scalp EEG sensor with sixteen electrodes is proposed to measure brainwaves over the entire brain area without any surgical procedures. We validated the proposed sensor system with visual evoked potential (VEP) experiments elicited by flash stimulations. The VEP responses obtained from experiments are compared with the existing literature, and analyzed in temporal and spatial perspectives. We further interpret the experimental results using time-frequency distribution (TFD) and distance measurements. The developed sensor guarantees stable operations for in vivo experiments in a non-invasive manner without surgical procedures, therefore exhibiting a high potential to strengthen longitudinal experimental studies and reliable translational research exploiting non-invasive paradigms. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

9 pages, 3517 KiB

Open AccessArticle

Alternative cDEP Design to Facilitate Cell Isolation for Identification by Raman Spectroscopy

by Cynthia Hanson and Elizabeth Vargis^*

Department of Biological Engineering, Utah State University, Logan, UT 84322, USA

Sensors 2017, 17(2), 327; https://doi.org/10.3390/s17020327 - 9 Feb 2017

Cited by 11 | Viewed by 6620

Abstract

Dielectrophoresis (DEP) uses non-uniform electric fields to cause motion in particles due to the particles’ intrinsic properties. As such, DEP is a well-suited label-free means for cell sorting. Of the various methods of implementing DEP, contactless dielectrophoresis (cDEP) is advantageous as it avoids [...] Read more.

Dielectrophoresis (DEP) uses non-uniform electric fields to cause motion in particles due to the particles’ intrinsic properties. As such, DEP is a well-suited label-free means for cell sorting. Of the various methods of implementing DEP, contactless dielectrophoresis (cDEP) is advantageous as it avoids common problems associated with DEP, such as electrode fouling and electrolysis. Unfortunately, cDEP devices can be difficult to fabricate, replicate, and reuse. In addition, the operating parameters are limited by the dielectric breakdown of polydimethylsiloxane (PDMS). This study presents an alternative way to fabricate a cDEP device allowing for higher operating voltages, improved replication, and the opportunity for analysis using Raman spectroscopy. In this device, channels were formed in fused silica rather than PDMS. The device successfully trapped 3.3 μm polystyrene spheres for analysis by Raman spectroscopy. The successful implementation indicates the potential to use cDEP to isolate and identify biological samples on a single device. Full article

(This article belongs to the Special Issue Applications of Raman Spectroscopy in Biosensors)

▼ Show Figures

Figure 1

12 pages, 24555 KiB

Open AccessArticle

Proof of Concept of Integrated Load Measurement in 3D Printed Structures

by Michaël Hinderdael^1,*, Zoé Jardon¹, Margot Lison¹, Dieter De Baere¹, Wim Devesse¹

, Maria Strantza² and Patrick Guillaume¹

¹ Department of Mechanical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Belgium

² Vrije Universiteit Brussel, Department of Mechanics of Materials and Constructions, Pleinlaan 2, 1050 Elsene, Belgium

Sensors 2017, 17(2), 328; https://doi.org/10.3390/s17020328 - 9 Feb 2017

Cited by 8 | Viewed by 5707

Abstract

Currently, research on structural health monitoring systems is focused on direct integration of the system into a component or structure. The latter results in a so-called smart structure. One example of a smart structure is a component with integrated strain sensing for continuous [...] Read more.

Currently, research on structural health monitoring systems is focused on direct integration of the system into a component or structure. The latter results in a so-called smart structure. One example of a smart structure is a component with integrated strain sensing for continuous load monitoring. Additive manufacturing, or 3D printing, now also enables such integration of functions inside components. As a proof-of-concept, the Fused Deposition Modeling (FDM) technique was used to integrate a strain sensing element inside polymer (ABS) tensile test samples. The strain sensing element consisted of a closed capillary filled with a fluid and connected to an externally mounted pressure sensor. The volumetric deformation of the integrated capillary resulted in pressure changes in the fluid. The obtained pressure measurements during tensile testing are reported in this paper and compared to state-of-the-art extensometer measurements. The sensitivity of the 3D printed pressure-based strain sensor is primarily a function of the compressibility of the capillary fluid. Air- and watertightness are of critical importance for the proper functioning of the 3D printed pressure-based strain sensor. Therefore, the best after-treatment procedure was selected on basis of a comparative analysis. The obtained pressure measurements are linear with respect to the extensometer readings, and the uncertainty on the strain measurement of a capillary filled with water (incompressible fluid) is ±3.1 µstrain, which is approximately three times less sensitive than conventional strain gauges (±1 µstrain), but 32 times more sensitive than the same sensor based on air (compressible fluid) (±101 µstrain). Full article

(This article belongs to the Special Issue 3D Printed Sensors)

▼ Show Figures

Figure 1

14 pages, 4786 KiB

Open AccessArticle

Effect of the Matching Circuit on the Electromechanical Characteristics of Sandwiched Piezoelectric Transducers

by Shuyu Lin^* and Jie Xu

Shaanxi key Laboratory of Ultrasonics, Shaanxi Normal University, Xi’an 710119, China

Sensors 2017, 17(2), 329; https://doi.org/10.3390/s17020329 - 10 Feb 2017

Cited by 50 | Viewed by 8728

Abstract

The input electrical impedance behaves as a capacitive when a piezoelectric transducer is excited near its resonance frequency. In order to increase the energy transmission efficiency, a series or parallel inductor should be used to compensate the capacitive impedance of the piezoelectric transducer. [...] Read more.

The input electrical impedance behaves as a capacitive when a piezoelectric transducer is excited near its resonance frequency. In order to increase the energy transmission efficiency, a series or parallel inductor should be used to compensate the capacitive impedance of the piezoelectric transducer. In this paper, the effect of the series matching inductor on the electromechanical characteristics of the piezoelectric transducer is analyzed. The dependency of the resonance/anti-resonance frequency, the effective electromechanical coupling coefficient, the electrical quality factor and the electro-acoustical efficiency on the matching inductor is obtained. It is shown that apart from compensating the capacitive impedance of the piezoelectric transducer, the series matching inductor can also change the electromechanical characteristics of the piezoelectric transducer. When series matching inductor is increased, the resonance frequency is decreased and the anti-resonance unchanged; the effective electromechanical coupling coefficient is increased. For the electrical quality factor and the electroacoustic efficiency, the dependency on the matching inductor is different when the transducer is operated at the resonance and the anti-resonance frequency. The electromechanical characteristics of the piezoelectric transducer with series matching inductor are measured. It is shown that the theoretically predicted relationship between the electromechanical characteristics and the series matching inductor is in good agreement with the experimental results. Full article

(This article belongs to the Special Issue Self-Powered Sensors)

▼ Show Figures

Figure 1

9 pages, 2913 KiB

Open AccessArticle

Hybrid Visible Light and Ultrasound-Based Sensor for Distance Estimation

by Jose Rabadan^1,*, Victor Guerra¹

, Rafael Rodríguez¹, Julio Rufo¹

, Martin Luna-Rivera² and Rafael Perez-Jimenez¹

¹ IDeTIC, Universidad de Las Palmas de Gran Canaria, PCT Tafira, 35017 Las Palmas, Spain

² Facultad de Ciencias, Universidad Autónoma de San Luis Potosi, Avda Salvador Nava S/N, 78290 San Luis Potosi, Mexico

Sensors 2017, 17(2), 330; https://doi.org/10.3390/s17020330 - 10 Feb 2017

Cited by 21 | Viewed by 5912

Abstract

Distance estimation plays an important role in location-based services, which has become very popular in recent years. In this paper, a new short range cricket sensor-based approach is proposed for indoor location applications. This solution uses Time Difference of Arrival (TDoA) between an [...] Read more.

Distance estimation plays an important role in location-based services, which has become very popular in recent years. In this paper, a new short range cricket sensor-based approach is proposed for indoor location applications. This solution uses Time Difference of Arrival (TDoA) between an optical and an ultrasound signal which are transmitted simultaneously, to estimate the distance from the base station to the mobile receiver. The measurement of the TDoA at the mobile receiver endpoint is proportional to the distance. The use of optical and ultrasound signals instead of the conventional radio wave signal makes the proposed approach suitable for environments with high levels of electromagnetic interference or where the propagation of radio frequencies is entirely restricted. Furthermore, unlike classical cricket systems, a double-way measurement procedure is introduced, allowing both the base station and mobile node to perform distance estimation simultaneously. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

▼ Show Figures

Figure 1

15 pages, 3381 KiB

Open AccessArticle

Geometric Shape Induced Small Change of Seebeck Coefficient in Bulky Metallic Wires

by Gang Li, Xiaohui Su, Fan Yang, Xiaoye Huo, Gengmin Zhang and Shengyong Xu^*

Key Laboratory for the Physics & Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing 100871, China

Sensors 2017, 17(2), 331; https://doi.org/10.3390/s17020331 - 10 Feb 2017

Cited by 3 | Viewed by 4566

Abstract

In this paper, we report the results of slight changes in the thermopower of long W, Mo, Zn, Cu, brass, and Ti wires, that resulted from changes in the wire’s diameter or cross-sectional area. The samples used in the tests had a round [...] Read more.

In this paper, we report the results of slight changes in the thermopower of long W, Mo, Zn, Cu, brass, and Ti wires, that resulted from changes in the wire’s diameter or cross-sectional area. The samples used in the tests had a round shape with a diameter that ranged from tens of micron to 2 mm, which was much larger than the corresponding mean free paths of these materials. Nevertheless, a small change in thermopower, at the order of 1–10 nV/K, was repeatedly observed when the wire diameter was changed, or when the cross-sectional area of the wire was altered by mechanical methods, such as grinding or splitting. The results are consistent with previous observations showing that the thermopower in metallic thin film stripes changes with their width, from 100 μm to as little as 70 nm, implying a universal, geometric-boundary-related size effect of thermopower in metal materials, that occurs at the nanometer scale and continuously decreases all the way to the millimeter scale. This effect could be applied in the manufacturing of high-temperature sensors with simple structures. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 2958 KiB

Open AccessArticle

A Web of Things-Based Emerging Sensor Network Architecture for Smart Control Systems

by Murad Khan, Bhagya Nathali Silva

and Kijun Han^*

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

Sensors 2017, 17(2), 332; https://doi.org/10.3390/s17020332 - 9 Feb 2017

Cited by 42 | Viewed by 7213

Abstract

The Web of Things (WoT) plays an important role in the representation of the objects connected to the Internet of Things in a more transparent and effective way. Thus, it enables seamless and ubiquitous web communication between users and the smart things. Considering [...] Read more.

The Web of Things (WoT) plays an important role in the representation of the objects connected to the Internet of Things in a more transparent and effective way. Thus, it enables seamless and ubiquitous web communication between users and the smart things. Considering the importance of WoT, we propose a WoT-based emerging sensor network (WoT-ESN), which collects data from sensors, routes sensor data to the web, and integrate smart things into the web employing a representational state transfer (REST) architecture. A smart home scenario is introduced to evaluate the proposed WoT-ESN architecture. The smart home scenario is tested through computer simulation of the energy consumption of various household appliances, device discovery, and response time performance. The simulation results show that the proposed scheme significantly optimizes the energy consumption of the household appliances and the response time of the appliances. Full article

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

▼ Show Figures

Figure 1

10 pages, 2118 KiB

Open AccessArticle

Reliable Identiﬁcation of Vehicle-Boarding Actions Based on Fuzzy Inference Syste

by DaeHan Ahn¹, Homin Park², Seokhyun Hwang³ and Taejoon Park^4,*

¹ Department of Information and Communication Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno jungang-daero, Hyeonpung-myeon, Dalseong-gun, Daegu 42988, Korea

² Research Institute of Engineering & Technology, Hanyang University, 55 Hanyangdaehak-ro, Ansan, Gyeonggi-do 15588, Korea

³ Department of Interdisciplinary Engineering System, Hanyang University, 55 Hanyangdaehak-ro, Ansan, Gyeonggi-do 15588, Korea

⁴ Department of Robotics Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan, Gyeonggi-do 15588, Korea

Sensors 2017, 17(2), 333; https://doi.org/10.3390/s17020333 - 9 Feb 2017

Cited by 11 | Viewed by 4976

Abstract

Existing smartphone-based solutions to prevent distracted driving suffer from inadequate system designs that only recognize simple and clean vehicle-boarding actions, thereby failing to meet the required level of accuracy in real-life environments. In this paper, exploiting unique sensory features consistently monitored from a [...] Read more.

Existing smartphone-based solutions to prevent distracted driving suffer from inadequate system designs that only recognize simple and clean vehicle-boarding actions, thereby failing to meet the required level of accuracy in real-life environments. In this paper, exploiting unique sensory features consistently monitored from a broad range of complicated vehicle-boarding actions, we propose a reliable and accurate system based on fuzzy inference to classify the sides of vehicle entrancebyleveragingbuilt-insmartphonesensorsonly. Theresultsofourcomprehensiveevaluation on three vehicle types with four participants demonstrate that the proposed system achieves 91.1%∼94.0% accuracy, outperforming other methods by 26.9%∼38.4% and maintains at least 87.8 %accuracy regardless of smartphone positions and vehicle types. Full article

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

▼ Show Figures

Figure 1

17 pages, 2061 KiB

Open AccessArticle

Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems

by Tao Liu, Yin Guo^*, Shourui Yang, Shibin Yin and Jigui Zhu

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(2), 334; https://doi.org/10.3390/s17020334 - 14 Feb 2017

Cited by 7 | Viewed by 5856

Abstract

Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree [...] Read more.

Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF) pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points on the part before the robot moved to grasp it. In order to estimate the part pose, a nonlinear optimization model based on the camera object space collinearity error in different poses is established, and the initial iteration value is estimated with the differential transformation. Measuring poses of the camera are optimized based on uncertainty analysis. Also, the principle of the robotic intelligent grasping system was developed, with which the robot could adjust its pose to grasp the part. In experimental tests, the part poses estimated with the method described in this paper were compared with those produced by a laser tracker, and results show the RMS angle and position error are about 0.0228° and 0.4603 mm. Robotic intelligent grasping tests were also successfully performed in the experiments. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 3413 KiB

Open AccessArticle

Wind Tunnel Measurements for Flutter of a Long-Afterbody Bridge Deck

by Zeng-Shun Chen^1,2, Cheng Zhang^3,*, Xu Wang^1,* and Cun-Ming Ma⁴

¹ State Key Laboratory Breeding Base of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074, China

² Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China

³ Shenzhen Bridge Design & Research Institute Co., Ltd., Shenzhen 518052, China

⁴ School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China

Sensors 2017, 17(2), 335; https://doi.org/10.3390/s17020335 - 9 Feb 2017

Cited by 28 | Viewed by 5964

Abstract

Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao [...] Read more.

Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks. Full article

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

▼ Show Figures

Figure 1

17 pages, 30073 KiB

Open AccessArticle

Vehicle Detection in Aerial Images Based on Region Convolutional Neural Networks and Hard Negative Example Mining

by Tianyu Tang

, Shilin Zhou^*, Zhipeng Deng

, Huanxin Zou and Lin Lei

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

Sensors 2017, 17(2), 336; https://doi.org/10.3390/s17020336 - 10 Feb 2017

Cited by 260 | Viewed by 16072

Abstract

Detecting vehicles in aerial imagery plays an important role in a wide range of applications. The current vehicle detection methods are mostly based on sliding-window search and handcrafted or shallow-learning-based features, having limited description capability and heavy computational costs. Recently, due to the [...] Read more.

Detecting vehicles in aerial imagery plays an important role in a wide range of applications. The current vehicle detection methods are mostly based on sliding-window search and handcrafted or shallow-learning-based features, having limited description capability and heavy computational costs. Recently, due to the powerful feature representations, region convolutional neural networks (CNN) based detection methods have achieved state-of-the-art performance in computer vision, especially Faster R-CNN. However, directly using it for vehicle detection in aerial images has many limitations: (1) region proposal network (RPN) in Faster R-CNN has poor performance for accurately locating small-sized vehicles, due to the relatively coarse feature maps; and (2) the classifier after RPN cannot distinguish vehicles and complex backgrounds well. In this study, an improved detection method based on Faster R-CNN is proposed in order to accomplish the two challenges mentioned above. Firstly, to improve the recall, we employ a hyper region proposal network (HRPN) to extract vehicle-like targets with a combination of hierarchical feature maps. Then, we replace the classifier after RPN by a cascade of boosted classifiers to verify the candidate regions, aiming at reducing false detection by negative example mining. We evaluate our method on the Munich vehicle dataset and the collected vehicle dataset, with improvements in accuracy and robustness compared to existing methods. Full article

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

▼ Show Figures

Figure 1

18 pages, 5556 KiB

Open AccessArticle

Robust Video Stabilization Using Particle Keypoint Update and l₁-Optimized Camera Path

by Semi Jeon¹, Inhye Yoon^1,2, Jinbeum Jang¹

, Seungji Yang³, Jisung Kim³ and Joonki Paik^1,*

¹ Department of Image, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Korea

² ADAS Camera Team, LG Electronics, 322 Gyeongmyeong-daero, Seo-gu, Incheon 22744, Korea

³ Future Technology R&D, SK Telecom, Sunae-dong, Bundang-gu, Seongnam 13595, Korea

Sensors 2017, 17(2), 337; https://doi.org/10.3390/s17020337 - 10 Feb 2017

Cited by 21 | Viewed by 7858

Abstract

Acquisition of stabilized video is an important issue for various type of digital cameras. This paper presents an adaptive camera path estimation method using robust feature detection to remove shaky artifacts in a video. The proposed algorithm consists of three steps: (i) robust [...] Read more.

Acquisition of stabilized video is an important issue for various type of digital cameras. This paper presents an adaptive camera path estimation method using robust feature detection to remove shaky artifacts in a video. The proposed algorithm consists of three steps: (i) robust feature detection using particle keypoints between adjacent frames; (ii) camera path estimation and smoothing; and (iii) rendering to reconstruct a stabilized video. As a result, the proposed algorithm can estimate the optimal homography by redefining important feature points in the flat region using particle keypoints. In addition, stabilized frames with less holes can be generated from the optimal, adaptive camera path that minimizes a temporal total variation (TV). The proposed video stabilization method is suitable for enhancing the visual quality for various portable cameras and can be applied to robot vision, driving assistant systems, and visual surveillance systems. Full article

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

▼ Show Figures

Figure 1

17 pages, 624 KiB

Open AccessArticle

Synthesizing Existing CSMA and TDMA Based MAC Protocols for VANETs

by Jiawei Huang¹, Qi Li¹, Shaohua Zhong¹, Lianhai Liu¹, Ping Zhong^1,*

, Jianxin Wang¹ and Jin Ye²

¹ School of Information Science and Engineering, Central South University, Changsha 410083, China

² School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China

Sensors 2017, 17(2), 338; https://doi.org/10.3390/s17020338 - 10 Feb 2017

Cited by 22 | Viewed by 6434

Abstract

Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies [...] Read more.

Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies used in these MAC protocols are complementary. Based on this insight, we design CTMAC, a MAC protocol that synthesizes existing strategies; namely, random accessing channel (used in CSMA-style protocols) and arbitral reserving channel (used in TDMA-based protocols). CTMAC swiftly changes its strategy according to the vehicle density, and its performance is better than the state-of-the-art protocols. We evaluate CTMAC using at-scale simulations. Our results show that CTMAC reduces the channel completion time and increases the network goodput by 45% for a wide range of application workloads and network settings. Full article

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

▼ Show Figures

Figure 1

16 pages, 912 KiB

Open AccessArticle

Context Sensing System Analysis for Privacy Preservation Based on Game Theory

by Shengling Wang¹, Luyun Li¹, Weiman Sun², Junqi Guo^1,*, Rongfang Bie¹ and Kai Lin³

¹ College of Information Science and Technology, Beijing Normal University, Beijing 100875, China

² Department of Physics, Beijing Normal University, Beijing 100875, China

³ Telecommunications Engineering with Management, International School, Beijing University of Posts and Telecommunications, Beijing 100876, China

Sensors 2017, 17(2), 339; https://doi.org/10.3390/s17020339 - 10 Feb 2017

Cited by 12 | Viewed by 6117

Abstract

In a context sensing system in which a sensor-equipped mobile phone runs an unreliable context-aware application, the application can infer the user’s contexts, based on which it provides personalized services. However, the application may sell the user’s contexts to some malicious adversaries to [...] Read more.

In a context sensing system in which a sensor-equipped mobile phone runs an unreliable context-aware application, the application can infer the user’s contexts, based on which it provides personalized services. However, the application may sell the user’s contexts to some malicious adversaries to earn extra profits, which will hinder its widespread use. In the real world, the actions of the user, the application and the adversary in the context sensing system affect each other, so that their payoffs are constrained mutually. To figure out under which conditions they behave well (the user releases, the application does not leak and the adversary does not retrieve the context), we take advantage of game theory to analyze the context sensing system. We use the extensive form game and the repeated game, respectively, to analyze two typical scenarios, single interaction and multiple interaction among three players, from which Nash equilibriums and cooperation conditions are obtained. Our results show that the reputation mechanism for the context-sensing system in the former scenario is crucial to privacy preservation, so is the extent to which the participants are concerned about future payoffs in the latter one. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

▼ Show Figures

Figure 1

17 pages, 1869 KiB

Open AccessArticle

Fusion of Inertial/Magnetic Sensor Measurements and Map Information for Pedestrian Tracking

by Shu-Di Bao¹

, Xiao-Li Meng², Wendong Xiao³ and Zhi-Qiang Zhang^4,*

¹ School of Electronic and Information Engineering, Ningbo University of Technology, Ningbo 315200, China

² Institute for Infocomm Research, Singapore 138632, Singapore

³ School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China

⁴ School of Electronic and Electrical Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK

Sensors 2017, 17(2), 340; https://doi.org/10.3390/s17020340 - 10 Feb 2017

Cited by 42 | Viewed by 5858

Abstract

The wearable inertial/magnetic sensor based human motion analysis plays an important role in many biomedical applications, such as physical therapy, gait analysis and rehabilitation. One of the main challenges for the lower body bio-motion analysis is how to reliably provide position estimations of [...] Read more.

The wearable inertial/magnetic sensor based human motion analysis plays an important role in many biomedical applications, such as physical therapy, gait analysis and rehabilitation. One of the main challenges for the lower body bio-motion analysis is how to reliably provide position estimations of human subject during walking. In this paper, we propose a particle filter based human position estimation method using a foot-mounted inertial and magnetic sensor module, which not only uses the traditional zero velocity update (ZUPT), but also applies map information to further correct the acceleration double integration drift and thus improve estimation accuracy. In the proposed method, a simple stance phase detector is designed to identify the stance phase of a gait cycle based on gyroscope measurements. For the non-stance phase during a gait cycle, an acceleration control variable derived from ZUPT information is introduced in the process model, while vector map information is taken as binary pseudo-measurements to further enhance position estimation accuracy and reduce uncertainty of walking trajectories. A particle filter is then designed to fuse ZUPT information and binary pseudo-measurements together. The proposed human position estimation method has been evaluated with closed-loop walking experiments in indoor and outdoor environments. Results of comparison study have illustrated the effectiveness of the proposed method for application scenarios with useful map information. Full article

(This article belongs to the Special Issue Sensors and Analytics for Precision Medicine)

▼ Show Figures

Figure 1

36 pages, 2302 KiB

Open AccessReview

A Review of Wearable Technologies for Elderly Care that Can Accurately Track Indoor Position, Recognize Physical Activities and Monitor Vital Signs in Real Time

by Zhihua Wang^1,2, Zhaochu Yang^1,* and Tao Dong^3,*

¹ Institute of Applied Micro-Nano Science and Technology, Chongqing Technology and Business University, Chongqing 400067, China

² College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha 410073, China

³ Institute for Microsystems (IMS), Faculty of Technology and Maritime Science, University College of Southeast Norway (HSN), Horten 3184, Norway

Sensors 2017, 17(2), 341; https://doi.org/10.3390/s17020341 - 10 Feb 2017

Cited by 307 | Viewed by 30106

Abstract

Rapid growth of the aged population has caused an immense increase in the demand for healthcare services. Generally, the elderly are more prone to health problems compared to other age groups. With effective monitoring and alarm systems, the adverse effects of unpredictable events [...] Read more.

Rapid growth of the aged population has caused an immense increase in the demand for healthcare services. Generally, the elderly are more prone to health problems compared to other age groups. With effective monitoring and alarm systems, the adverse effects of unpredictable events such as sudden illnesses, falls, and so on can be ameliorated to some extent. Recently, advances in wearable and sensor technologies have improved the prospects of these service systems for assisting elderly people. In this article, we review state-of-the-art wearable technologies that can be used for elderly care. These technologies are categorized into three types: indoor positioning, activity recognition and real time vital sign monitoring. Positioning is the process of accurate localization and is particularly important for elderly people so that they can be found in a timely manner. Activity recognition not only helps ensure that sudden events (e.g., falls) will raise alarms but also functions as a feasible way to guide people’s activities so that they avoid dangerous behaviors. Since most elderly people suffer from age-related problems, some vital signs that can be monitored comfortably and continuously via existing techniques are also summarized. Finally, we discussed a series of considerations and future trends with regard to the construction of “smart clothing” system. Full article

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

▼ Show Figures

Graphical abstract

28 pages, 1321 KiB

Open AccessArticle

A Framework for Bus Trajectory Extraction and Missing Data Recovery for Data Sampled from the Internet

by Changfei Tong^1,*, Huiling Chen¹, Qi Xuan² and Xuhua Yang³

¹ College of Physics & Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China

² College of Information Engineering, Zhejiang University of Technology, Hangzhou 310023, China

³ College of Computer Science and Technology, Zhejiang University of Technology, Hangzhou 310023, China

Sensors 2017, 17(2), 342; https://doi.org/10.3390/s17020342 - 10 Feb 2017

Cited by 9 | Viewed by 6479

Abstract

This paper presents a novel framework for trajectories’ extraction and missing data recovery for bus traveling data sampled from the Internet. The trajectory extraction procedure is composed of three main parts: trajectory clustering, trajectory cleaning and trajectory connecting. In the clustering procedure, we [...] Read more.

This paper presents a novel framework for trajectories’ extraction and missing data recovery for bus traveling data sampled from the Internet. The trajectory extraction procedure is composed of three main parts: trajectory clustering, trajectory cleaning and trajectory connecting. In the clustering procedure, we focus on feature construction and parameter selection for the fuzzy C-means clustering method. Following the clustering procedure, the trajectory cleaning algorithm is implemented based on a new introduced fuzzy connecting matrix, which evaluates the possibility of data belonging to the same trajectory and helps detect the anomalies in a ranked context-related order. Finally, the trajectory connecting algorithm is proposed to solve the issue that occurs in some cases when a route trajectory is incorrectly partitioned into several clusters. In the missing data recovery procedure, we developed the contextual linear interpolation for the cases of missing data occurring inside the trajectory and the median value interpolation for the cases of missing data outside the trajectory. Extensive experiments are conducted to demonstrate that the proposed framework offers a powerful ability to extract and recovery bus trajectories sampled from the Internet. Full article

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

▼ Show Figures

Figure 1

25 pages, 14195 KiB

Open AccessArticle

A Methodology to Monitor Airborne PM₁₀ Dust Particles Using a Small Unmanned Aerial Vehicle

by Miguel Alvarado^1,*, Felipe Gonzalez², Peter Erskine¹, David Cliff³ and Darlene Heuff⁴

¹ Environment Centre, Sustainable Mineral Institute, The University of Queensland, 4072 Brisbane, Australia

² Science and Engineering Faculty, Queensland University of Technology (QUT), 4000 Brisbane, Australia

³ People Centre, Sustainable Mineral Institute, The University of Queensland, 4072 Brisbane, Australia

⁴ Advanced Environmental Dynamics Pty Ltd., Ferny Hills, 4055 Queensland, Australia

Sensors 2017, 17(2), 343; https://doi.org/10.3390/s17020343 - 14 Feb 2017

Cited by 68 | Viewed by 10741

Abstract

Throughout the process of coal extraction from surface mines, gases and particles are emitted in the form of fugitive emissions by activities such as hauling, blasting and transportation. As these emissions are diffuse in nature, estimations based upon emission factors and dispersion/advection equations [...] Read more.

Throughout the process of coal extraction from surface mines, gases and particles are emitted in the form of fugitive emissions by activities such as hauling, blasting and transportation. As these emissions are diffuse in nature, estimations based upon emission factors and dispersion/advection equations need to be measured directly from the atmosphere. This paper expands upon previous research undertaken to develop a relative methodology to monitor PM₁₀ dust particles produced by mining activities making use of small unmanned aerial vehicles (UAVs). A module sensor using a laser particle counter (OPC-N2 from Alphasense, Great Notley, Essex, UK) was tested. An aerodynamic flow experiment was undertaken to determine the position and length of a sampling probe of the sensing module. Flight tests were conducted in order to demonstrate that the sensor provided data which could be used to calculate the emission rate of a source. Emission rates are a critical variable for further predictive dispersion estimates. First, data collected by the airborne module was verified using a 5.0 m tower in which a TSI DRX 8533 (reference dust monitoring device, TSI, Shoreview, MN, USA) and a duplicate of the module sensor were installed. Second, concentration values collected by the monitoring module attached to the UAV (airborne module) obtaining a percentage error of 1.1%. Finally, emission rates from the source were calculated, with airborne data, obtaining errors as low as 1.2%. These errors are low and indicate that the readings collected with the airborne module are comparable to the TSI DRX and could be used to obtain specific emission factors from fugitive emissions for industrial activities. Full article

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

▼ Show Figures

Figure 1

18 pages, 854 KiB

Open AccessArticle

A Review of the Bayesian Occupancy Filter

by Marcelo Saval-Calvo¹, Luis Medina-Valdés¹, José María Castillo-Secilla^1,*, Sergio Cuenca-Asensi¹, Antonio Martínez-Álvarez¹ and Jorge Villagrá²

¹ University Institute for Computing Research, University of Alicante, 03690 San Vicente del Raspeig, Spain

² Centre for Automation and Robotics (UPM-CSIC), 28500 Arganda del Rey, Madrid, Spain

Sensors 2017, 17(2), 344; https://doi.org/10.3390/s17020344 - 10 Feb 2017

Cited by 32 | Viewed by 7675

Abstract

Autonomous vehicle systems are currently the object of intense research within scientiﬁc and industrial communities; however, many problems remain to be solved. One of the most critical aspects addressed in both autonomous driving and robotics is environment perception, since it consists of the [...] Read more.

Autonomous vehicle systems are currently the object of intense research within scientiﬁc and industrial communities; however, many problems remain to be solved. One of the most critical aspects addressed in both autonomous driving and robotics is environment perception, since it consists of the ability to understand the surroundings of the vehicle to estimate risks and make decisions on future movements. In recent years, the Bayesian Occupancy Filter (BOF) method has been developed to evaluate occupancy by tessellation of the environment. A review of the BOF and its variants is presented in this paper. Moreover, we propose a detailed taxonomy where the BOF is decomposed into ﬁve progressive layers, from the level closest to the sensor to the highest abstractlevelofriskassessment. Inaddition,wepresentastudyofimplementedusecasestoprovide a practical understanding on the main uses of the BOF and its taxonomy. Full article

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

▼ Show Figures

Figure 1

12 pages, 5071 KiB

Open AccessArticle

Structural Health Monitoring Using Textile Reinforcement Structures with Integrated Optical Fiber Sensors

by Kort Bremer^1,*, Frank Weigand², Yulong Zheng¹, Lourdes Shanika Alwis³

, Reinhard Helbig² and Bernhard Roth¹

¹ Hannover Centre for Optical Technologies (HOT), Leibniz University Hannover, Hannover 30167, Germany

² Saxon Textile Research Institute (STFI), Chemnitz 09125, Germany

³ School of Engineering and the Built Environment, Edinburgh Napier University, Edinburgh EH10 5DT, UK

Sensors 2017, 17(2), 345; https://doi.org/10.3390/s17020345 - 10 Feb 2017

Cited by 83 | Viewed by 9619

Abstract

Optical fiber-based sensors “embedded” in functionalized carbon structures (FCSs) and textile net structures (TNSs) based on alkaline-resistant glass are introduced for the purpose of structural health monitoring (SHM) of concrete-based structures. The design aims to monitor common SHM parameters such as strain and [...] Read more.

Optical fiber-based sensors “embedded” in functionalized carbon structures (FCSs) and textile net structures (TNSs) based on alkaline-resistant glass are introduced for the purpose of structural health monitoring (SHM) of concrete-based structures. The design aims to monitor common SHM parameters such as strain and cracks while at the same time acting as a structural strengthening mechanism. The sensor performances of the two systems are characterized in situ using Mach-Zehnder interferometric (MZI) and optical attenuation measurement techniques, respectively. For this purpose, different FCS samples were subjected to varying elongation using a tensile testing machine by carefully incrementing the applied force, and good correlation between the applied force and measured length change was observed. For crack detection, the functionalized TNSs were embedded into a concrete block which was then exposed to varying load using the three-point flexural test until destruction. Promising results were observed, identifying that the location of the crack can be determined using the conventional optical time domain reflectometry (OTDR) technique. The embedded sensors thus evaluated show the value of the dual achievement of the schemes proposed in obtaining strain/crack measurement while being utilized as strengthening agents as well. Full article

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

▼ Show Figures

Figure 1

17 pages, 2826 KiB

Open AccessArticle

Development of a Hybrid Piezo Natural Rubber Piezoelectricity and Piezoresistivity Sensor with Magnetic Clusters Made by Electric and Magnetic Field Assistance and Filling with Magnetic Compound Fluid

by Kunio Shimada^1,*

and Norihiko Saga²

¹ Faculty of Symbiotic Systems Sciences, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan

² Department of Human System Interaction, Kansai Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan

Sensors 2017, 17(2), 346; https://doi.org/10.3390/s17020346 - 10 Feb 2017

Cited by 19 | Viewed by 8319

Abstract

Piezoelements used in robotics require large elasticity and extensibility to be installed in an artificial robot skin. However, the piezoelements used until recently are vulnerable to large forces because of the thin solid materials employed. To resolve this issue, we utilized a natural [...] Read more.

Piezoelements used in robotics require large elasticity and extensibility to be installed in an artificial robot skin. However, the piezoelements used until recently are vulnerable to large forces because of the thin solid materials employed. To resolve this issue, we utilized a natural rubber and applied our proposed new method of aiding with magnetic and electric fields as well as filling with magnetic compound fluid (MCF) and doping. We have verified the piezoproperties of the resulting MCF rubber. The effect of the created magnetic clusters is featured in a new two types of multilayered structures of the piezoelement. By measuring the piezoelectricity response to pressure, the synergetic effects of the magnetic clusters, the doping and the electric polymerization on the piezoelectric effect were clarified. In addition, by examining the relation between the piezoelectricity and the piezoresistivity created in the MCF piezo element, we propose a hybrid piezoelement. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

11 pages, 749 KiB

Open AccessArticle

A Probability-Based Algorithm Using Image Sensors to Track the LED in a Vehicle Visible Light Communication System

by Phat Huynh, Trong-Hop Do

and Myungsik Yoo^*

School of Electronic Engineering, Soongsil University, Seoul 06978, Korea

Sensors 2017, 17(2), 347; https://doi.org/10.3390/s17020347 - 10 Feb 2017

Cited by 24 | Viewed by 5195

Abstract

This paper proposes a probability-based algorithm to track the LED in vehicle visible light communication systems using a camera. In this system, the transmitters are the vehicles’ front and rear LED lights. The receivers are high speed cameras that take a series of [...] Read more.

This paper proposes a probability-based algorithm to track the LED in vehicle visible light communication systems using a camera. In this system, the transmitters are the vehicles’ front and rear LED lights. The receivers are high speed cameras that take a series of images of the LEDs. ThedataembeddedinthelightisextractedbyﬁrstdetectingthepositionoftheLEDsintheseimages. Traditionally, LEDs are detected according to pixel intensity. However, when the vehicle is moving, motion blur occurs in the LED images, making it difﬁcult to detect the LEDs. Particularly at high speeds, some frames are blurred at a high degree, which makes it impossible to detect the LED as well as extract the information embedded in these frames. The proposed algorithm relies not only on the pixel intensity, but also on the optical ﬂow of the LEDs and on statistical information obtained from previous frames. Based on this information, the conditional probability that a pixel belongs to a LED is calculated. Then, the position of LED is determined based on this probability. To verify the suitability of the proposed algorithm, simulations are conducted by considering the incidents that can happen in a real-world situation, including a change in the position of the LEDs at each frame, as well as motion blur due to the vehicle speed. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

15 pages, 3830 KiB

Open AccessArticle

An Optoelectronic Equivalent Narrowband Filter for High Resolution Optical Spectrum Analysis

by Kunpeng Feng^1,†

, Jiwen Cui^1,*,†, Hong Dang^1,†, Weidong Wu¹, Xun Sun¹, Xuelin Jiang^1,2 and Jiubin Tan¹

¹ Center of Ultra-Precision Optoelectronic Instrument, Harbin Institute of Technology, Harbin 150080, China

² Shanghai Micro Electronics Equipment Co., Ltd., Shanghai 201203, China

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 348; https://doi.org/10.3390/s17020348 - 10 Feb 2017

Cited by 9 | Viewed by 5132

Abstract

To achieve a narrow bandwidth optical filter with a wide swept range for new generation optical spectrum analysis (OSA) of high performance optical sensors, an optoelectronic equivalent narrowband filter (OENF) was investigated and a swept optical filter with bandwidth of several MHz and [...] Read more.

To achieve a narrow bandwidth optical filter with a wide swept range for new generation optical spectrum analysis (OSA) of high performance optical sensors, an optoelectronic equivalent narrowband filter (OENF) was investigated and a swept optical filter with bandwidth of several MHz and sweep range of several tens of nanometers was built using electric filters and a sweep laser as local oscillator (LO). The principle of OENF is introduced and analysis of the OENF system is presented. Two electric filters are optimized to be RBW filters for high and medium spectral resolution applications. Both simulations and experiments are conducted to verify the OENF principle and the results show that the power uncertainty is less than 1.2% and the spectral resolution can reach 6 MHz. Then, a real-time wavelength calibration system consisting of a HCN gas cell and Fabry–Pérot etalon is proposed to guarantee a wavelength accuracy of ±0.4 pm in the C-band and to reduce the influence of phase noise and nonlinear velocity of the LO sweep. Finally, OSA experiments on actual spectra of various optical sensors are conducted using the OENF system. These experimental results indicate that OENF system has an excellent capacity for the analysis of fine spectrum structures. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

17 pages, 5146 KiB

Open AccessArticle

Compact Planar Ultrawideband Antennas with 3.5/5.2/5.8 GHz Triple Band-Notched Characteristics for Internet of Things Applications

by Jian Dong^1,*, Qianqian Li¹ and Lianwen Deng²

¹ School of Information Science and Engineering, Central South University, Changsha 410083, China

² School of Physics and Electronics, Central South University, Changsha 410083, China

Sensors 2017, 17(2), 349; https://doi.org/10.3390/s17020349 - 10 Feb 2017

Cited by 24 | Viewed by 6863

Abstract

Ultrawideband (UWB) antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT). A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna [...] Read more.

Ultrawideband (UWB) antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT). A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna has a very compact size of 10 x 16 mm2 and is composed of a square slotted radiation patch and a narrow rectangular ground plane on the back of the substrate. First, by etching a pair of inverted T-shaped slots at the bottom of the radiation patch, one notched band at 5-6 GHz for rejecting the Wireless Local Area Network (WLAN) is generated. Then, by cutting a comb-shaped slot on the top of the radiation patch, a second notched band for rejecting 3.5 GHz Worldwide Interoperability for Microwave Access (WiMAX) is obtained. Further, by cutting a pair of rectangular slots and a C-shaped slot as well as adding a pair of small square parasitic patches at the center of the radiating patch, two separate notched bands for rejecting 5.2 GHz lower WLAN and 5.8 GHz upper WLAN are realized, respectively. Additionally, by integrating the slotted radiation patch with the narrow rectangular ground plane, an enhanced impedance bandwidth can be achieved, especially at the higher band. The antenna consists of linear symmetrical sections only and is easy for fabrication and fine-tuning. The measured results show that the designed antenna provides a wide impedance bandwidth of 150% from 2.12 to 14.80 GHz for VSWR < 2, except for three notched bands of 3.36–4.16, 4.92–5.36, and 5.68–6.0 GHz. Additionally, the antenna exhibits nearly omnidirectional radiation characteristics, low gain at the stopbands, and flat group delay over the whole UWB except at the stopbands. Simulated and experimental results show that the proposed antenna can provide good frequency-domain and time-domain performances at desired UWB frequencies and be an attractive candidate for portable IoT applications. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 8206 KiB

Open AccessArticle

A Novel Strain-Based Method to Estimate Tire Conditions Using Fuzzy Logic for Intelligent Tires

by Daniel Garcia-Pozuelo¹, Oluremi Olatunbosun²

, Jorge Yunta^1,*, Xiaoguang Yang³ and Vicente Diaz¹

¹ Mechanical Engineering Department, Universidad Carlos III de Madrid, Avd. De la Universidad, 28911 Madrid, Spain

² School of Mechanical Engineering, University of Birmingham, Edgbaston B15 2TT, UK

³ Vanlead Rubber & Tire Research Institute, Wanli Tire Corporation Limited, Guangzhou 510425, China

Sensors 2017, 17(2), 350; https://doi.org/10.3390/s17020350 - 10 Feb 2017

Cited by 65 | Viewed by 7040

Abstract

The so-called intelligent tires are one of the most promising research fields for automotive engineers. These tires are equipped with sensors which provide information about vehicle dynamics. Up to now, the commercial intelligent tires only provide information about inflation pressure and their contribution [...] Read more.

The so-called intelligent tires are one of the most promising research fields for automotive engineers. These tires are equipped with sensors which provide information about vehicle dynamics. Up to now, the commercial intelligent tires only provide information about inflation pressure and their contribution to stability control systems is currently very limited. Nowadays one of the major problems for intelligent tire development is how to embed feasible and low cost sensors to obtain reliable information such as inflation pressure, vertical load or rolling speed. These parameters provide key information for vehicle dynamics characterization. In this paper, we propose a novel algorithm based on fuzzy logic to estimate the mentioned parameters by means of a single strain-based system. Experimental tests have been carried out in order to prove the suitability and durability of the proposed on-board strain sensor system, as well as its low cost advantages, and the accuracy of the obtained estimations by means of fuzzy logic. Full article

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

▼ Show Figures

Figure 1

17 pages, 4757 KiB

Open AccessArticle

Assessing Human Activity in Elderly People Using Non-Intrusive Load Monitoring

by José M. Alcalá, Jesús Ureña^*

, Álvaro Hernández and David Gualda

Electronics Department, University of Alcalá, Escuela Politécnica, Ctra. Madrid-Barcelona, Km. 33,600, 28871 Alcalá de Henares, Spain

Sensors 2017, 17(2), 351; https://doi.org/10.3390/s17020351 - 11 Feb 2017

Cited by 58 | Viewed by 7907

Abstract

The ageing of the population, and their increasing wish of living independently, are motivating the development of welfare and healthcare models. Existing approaches based on the direct heath-monitoring using body sensor networks (BSN) are precise and accurate. Nonetheless, their intrusiveness causes non-acceptance. New [...] Read more.

The ageing of the population, and their increasing wish of living independently, are motivating the development of welfare and healthcare models. Existing approaches based on the direct heath-monitoring using body sensor networks (BSN) are precise and accurate. Nonetheless, their intrusiveness causes non-acceptance. New approaches seek the indirect monitoring through monitoring activities of daily living (ADLs), which proves to be a suitable solution. ADL monitoring systems use many heterogeneous sensors, are less intrusive, and are less expensive than BSN, however, the deployment and maintenance of wireless sensor networks (WSN) prevent them from a widespread acceptance. In this work, a novel technique to monitor the human activity, based on non-intrusive load monitoring (NILM), is presented. The proposal uses only smart meter data, which leads to minimum intrusiveness and a potential massive deployment at minimal cost. This could be the key to develop sustainable healthcare models for smart homes, capable of complying with the elderly people’ demands. This study also uses the Dempster-Shafer theory to provide a daily score of normality with regard to the regular behavior. This approach has been evaluated using real datasets and, additionally, a benchmarking against a Gaussian mixture model approach is presented. Full article

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

▼ Show Figures

Graphical abstract

18 pages, 337 KiB

Open AccessArticle

Reduced-Drift Virtual Gyro from an Array of Low-Cost Gyros

by Richard J. Vaccaro^1,*

and Ahmed S. Zaki²

¹ Department of Electrical, Computer, and Biomedical Engineering, University of Rhode Island, Kingston, RI 02881, USA

² Naval Undersea Warfare Center, Division Newport, Newport, RI 02840, USA

Sensors 2017, 17(2), 352; https://doi.org/10.3390/s17020352 - 11 Feb 2017

Cited by 23 | Viewed by 5487

Abstract

A Kalman filter approach for combining the outputs of an array of high-drift gyros to obtain a virtual lower-drift gyro has been known in the literature for more than a decade. The success of this approach depends on the correlations of the random [...] Read more.

A Kalman filter approach for combining the outputs of an array of high-drift gyros to obtain a virtual lower-drift gyro has been known in the literature for more than a decade. The success of this approach depends on the correlations of the random drift components of the individual gyros. However, no method of estimating these correlations has appeared in the literature. This paper presents an algorithm for obtaining the statistical model for an array of gyros, including the cross-correlations of the individual random drift components. In order to obtain this model, a new statistic, called the “Allan covariance” between two gyros, is introduced. The gyro array model can be used to obtain the Kalman filter-based (KFB) virtual gyro. Instead, we consider a virtual gyro obtained by taking a linear combination of individual gyro outputs. The gyro array model is used to calculate the optimal coefficients, as well as to derive a formula for the drift of the resulting virtual gyro. The drift formula for the optimal linear combination (OLC) virtual gyro is identical to that previously derived for the KFB virtual gyro. Thus, a Kalman filter is not necessary to obtain a minimum drift virtual gyro. The theoretical results of this paper are demonstrated using simulated as well as experimental data. In experimental results with a 28-gyro array, the OLC virtual gyro has a drift spectral density 40 times smaller than that obtained by taking the average of the gyro signals. Full article

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

▼ Show Figures

Figure 1

19 pages, 4153 KiB

Open AccessArticle

A Passive Learning Sensor Architecture for Multimodal Image Labeling: An Application for Social Robots

by Marco A. Gutiérrez^1,*, Luis J. Manso¹, Harit Pandya² and Pedro Núñez¹

¹ Robotics and Artificial Vision Laboratory, University of Extremadura, 10003 Cáceres, Spain

² Robotics Research Center, IIIT Hyderabad, 500032 Hyderabad, India

Sensors 2017, 17(2), 353; https://doi.org/10.3390/s17020353 - 11 Feb 2017

Cited by 4 | Viewed by 5860

Abstract

Object detection and classification have countless applications in human–robot interacting systems. It is a necessary skill for autonomous robots that perform tasks in household scenarios. Despite the great advances in deep learning and computer vision, social robots performing non-trivial tasks usually spend most [...] Read more.

Object detection and classification have countless applications in human–robot interacting systems. It is a necessary skill for autonomous robots that perform tasks in household scenarios. Despite the great advances in deep learning and computer vision, social robots performing non-trivial tasks usually spend most of their time finding and modeling objects. Working in real scenarios means dealing with constant environment changes and relatively low-quality sensor data due to the distance at which objects are often found. Ambient intelligence systems equipped with different sensors can also benefit from the ability to find objects, enabling them to inform humans about their location. For these applications to succeed, systems need to detect the objects that may potentially contain other objects, working with relatively low-resolution sensor data. A passive learning architecture for sensors has been designed in order to take advantage of multimodal information, obtained using an RGB-D camera and trained semantic language models. The main contribution of the architecture lies in the improvement of the performance of the sensor under conditions of low resolution and high light variations using a combination of image labeling and word semantics. The tests performed on each of the stages of the architecture compare this solution with current research labeling techniques for the application of an autonomous social robot working in an apartment. The results obtained demonstrate that the proposed sensor architecture outperforms state-of-the-art approaches. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Graphical abstract

22 pages, 3719 KiB

Open AccessArticle

New Approaches to Exciting Exergame-Experiences for People with Motor Function Impairments

by Martina Eckert^*, Ignacio Gómez-Martinho, Juan Meneses and José-Fernán Martínez

Centro de Investigación en Tecnologías Software y Sistemas Multimedia para la Sostenibilidad (CITSEM), Campus Sur Universidad Politécnica de Madrid (UPM), Madrid 28031, Spain

Sensors 2017, 17(2), 354; https://doi.org/10.3390/s17020354 - 12 Feb 2017

Cited by 29 | Viewed by 10079

Abstract

The work presented here suggests new ways to tackle exergames for physical rehabilitation and to improve the players’ immersion and involvement. The primary (but not exclusive) purpose is to increase the motivation of children and adolescents with severe physical impairments, for doing their [...] Read more.

The work presented here suggests new ways to tackle exergames for physical rehabilitation and to improve the players’ immersion and involvement. The primary (but not exclusive) purpose is to increase the motivation of children and adolescents with severe physical impairments, for doing their required exercises while playing. The proposed gaming environment is based on the Kinect sensor and the Blender Game Engine. A middleware has been implemented that efficiently transmits the data from the sensor to the game. Inside the game, different newly proposed mechanisms have been developed to distinguish pure exercise-gestures from other movements used to control the game (e.g., opening a menu). The main contribution is the amplification of weak movements, which allows the physically impaired to have similar gaming experiences as the average population. To test the feasibility of the proposed methods, four mini-games were implemented and tested by a group of 11 volunteers with different disabilities, most of them bound to a wheelchair. Their performance has also been compared to that of a healthy control group. Results are generally positive and motivating, although there is much to do to improve the functionalities. There is a major demand for applications that help to include disabled people in society and to improve their life conditions. This work will contribute towards providing them with more fun during exercise. Full article

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

▼ Show Figures

Graphical abstract

19 pages, 1251 KiB

Open AccessArticle

A Novel Fiber Optic Based Surveillance System for Prevention of Pipeline Integrity Threats

by Javier Tejedor^1,†, Javier Macias-Guarasa^2,*

, Hugo F. Martins¹, Daniel Piote¹, Juan Pastor-Graells², Sonia Martin-Lopez², Pedro Corredera³ and Miguel Gonzalez-Herraez²

¹ FOCUS S.L., 28804 Madrid, Spain

² Department of Electronics, University of Alcalá, 28801 Alcalá de Henares, Spain

³ Instituto de Óptica, CSIC, 28006 Madrid, Spain

^† Current address: Department of Information Technology, University CEU San Pablo, 28003 Madrid, Spain.

Sensors 2017, 17(2), 355; https://doi.org/10.3390/s17020355 - 12 Feb 2017

Cited by 127 | Viewed by 8050

Abstract

This paper presents a novel surveillance system aimed at the detection and classification of threats in the vicinity of a long gas pipeline. The sensing system is based on phase-sensitive optical time domain reflectometry (ϕ-OTDR) technology for signal acquisition and pattern [...] Read more.

This paper presents a novel surveillance system aimed at the detection and classification of threats in the vicinity of a long gas pipeline. The sensing system is based on phase-sensitive optical time domain reflectometry (ϕ-OTDR) technology for signal acquisition and pattern recognition strategies for threat identification. The proposal incorporates contextual information at the feature level and applies a system combination strategy for pattern classification. The contextual information at the feature level is based on the tandem approach (using feature representations produced by discriminatively-trained multi-layer perceptrons) by employing feature vectors that spread different temporal contexts. The system combination strategy is based on a posterior combination of likelihoods computed from different pattern classification processes. The system operates in two different modes: (1) machine + activity identification, which recognizes the activity being carried out by a certain machine, and (2) threat detection, aimed at detecting threats no matter what the real activity being conducted is. In comparison with a previous system based on the same rigorous experimental setup, the results show that the system combination from the contextual feature information improves the results for each individual class in both operational modes, as well as the overall classification accuracy, with statistically-significant improvements. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 5748 KiB

Open AccessArticle

A Real-Time High Performance Computation Architecture for Multiple Moving Target Tracking Based on Wide-Area Motion Imagery via Cloud and Graphic Processing Units

by Kui Liu¹, Sixiao Wei¹, Zhijiang Chen¹, Bin Jia¹, Genshe Chen¹, Haibin Ling², Carolyn Sheaff³ and Erik Blasch^3,*

¹ Intelligent Fusion Technology, Inc., Germantown, MD 20876, USA

² Department of Computer and Information Sciences, Temple University, Philadelphia, PA 19122, USA

³ Air Force Research Laboratory, Information Directorate, Rome, NY 13441, USA

Sensors 2017, 17(2), 356; https://doi.org/10.3390/s17020356 - 12 Feb 2017

Cited by 14 | Viewed by 6836

Abstract

This paper presents the first attempt at combining Cloud with Graphic Processing Units (GPUs) in a complementary manner within the framework of a real-time high performance computation architecture for the application of detecting and tracking multiple moving targets based on Wide Area Motion [...] Read more.

This paper presents the first attempt at combining Cloud with Graphic Processing Units (GPUs) in a complementary manner within the framework of a real-time high performance computation architecture for the application of detecting and tracking multiple moving targets based on Wide Area Motion Imagery (WAMI). More specifically, the GPU and Cloud Moving Target Tracking (GC-MTT) system applied a front-end web based server to perform the interaction with Hadoop and highly parallelized computation functions based on the Compute Unified Device Architecture (CUDA©). The introduced multiple moving target detection and tracking method can be extended to other applications such as pedestrian tracking, group tracking, and Patterns of Life (PoL) analysis. The cloud and GPUs based computing provides an efficient real-time target recognition and tracking approach as compared to methods when the work flow is applied using only central processing units (CPUs). The simultaneous tracking and recognition results demonstrate that a GC-MTT based approach provides drastically improved tracking with low frame rates over realistic conditions. Full article

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

▼ Show Figures

Figure 1

11 pages, 2238 KiB

Open AccessArticle

Performance Characterization of a Switchable Acoustic Resolution and Optical Resolution Photoacoustic Microscopy System

by Mohesh Moothanchery and Manojit Pramanik^*

School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore

Sensors 2017, 17(2), 357; https://doi.org/10.3390/s17020357 - 12 Feb 2017

Cited by 62 | Viewed by 8655

Abstract

Photoacoustic microscopy (PAM) is a scalable bioimaging modality; one can choose low acoustic resolution with deep penetration depth or high optical resolution with shallow imaging depth. High spatial resolution and deep penetration depth is rather difficult to achieve using a single system. Here [...] Read more.

Photoacoustic microscopy (PAM) is a scalable bioimaging modality; one can choose low acoustic resolution with deep penetration depth or high optical resolution with shallow imaging depth. High spatial resolution and deep penetration depth is rather difficult to achieve using a single system. Here we report a switchable acoustic resolution and optical resolution photoacoustic microscopy (AR-OR-PAM) system in a single imaging system capable of both high resolution and low resolution on the same sample. Lateral resolution of 4.2 µm (with ~1.4 mm imaging depth) and lateral resolution of 45 μm (with ~7.6 mm imaging depth) was successfully demonstrated using a switchable system. In vivo blood vasculature imaging was also performed for its biological application. Full article

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

▼ Show Figures

Figure 1

12 pages, 5064 KiB

Open AccessArticle

Novel Fingertip Image-Based Heart Rate Detection Methods for a Smartphone

by Rifat Zaman¹, Chae Ho Cho¹, Konrad Hartmann-Vaccarezza²

, Tra Nguyen Phan¹, Gwonchan Yoon¹ and Jo Woon Chong^1,*

¹ Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409, USA

² Instituto de Ingenieria Biológica y Médica, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile

Sensors 2017, 17(2), 358; https://doi.org/10.3390/s17020358 - 12 Feb 2017

Cited by 21 | Viewed by 7525

Abstract

We hypothesize that our fingertip image-based heart rate detection methods using smartphone reliably detect the heart rhythm and rate of subjects. We propose fingertip curve line movement-based and fingertip image intensity-based detection methods, which both use the movement of successive fingertip images obtained [...] Read more.

We hypothesize that our fingertip image-based heart rate detection methods using smartphone reliably detect the heart rhythm and rate of subjects. We propose fingertip curve line movement-based and fingertip image intensity-based detection methods, which both use the movement of successive fingertip images obtained from smartphone cameras. To investigate the performance of the proposed methods, heart rhythm and rate of the proposed methods are compared to those of the conventional method, which is based on average image pixel intensity. Using a smartphone, we collected 120 s pulsatile time series data from each recruited subject. The results show that the proposed fingertip curve line movement-based method detects heart rate with a maximum deviation of 0.0832 Hz and 0.124 Hz using time- and frequency-domain based estimation, respectively, compared to the conventional method. Moreover, another proposed fingertip image intensity-based method detects heart rate with a maximum deviation of 0.125 Hz and 0.03 Hz using time- and frequency-based estimation, respectively. Full article

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

▼ Show Figures

Figure 1

23 pages, 6962 KiB

Open AccessArticle

Mitigating Multipath Bias Using a Dual-Polarization Antenna: Theoretical Performance, Algorithm Design, and Simulation

by Lin Xie

, Xiaowei Cui^*, Sihao Zhao

and Mingquan Lu

Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(2), 359; https://doi.org/10.3390/s17020359 - 13 Feb 2017

Cited by 34 | Viewed by 6882

Abstract

It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, [...] Read more.

It is well known that multipath effect remains a dominant error source that affects the positioning accuracy of Global Navigation Satellite System (GNSS) receivers. Significant efforts have been made by researchers and receiver manufacturers to mitigate multipath error in the past decades. Recently, a multipath mitigation technique using dual-polarization antennas has become a research hotspot for it provides another degree of freedom to distinguish the line-of-sight (LOS) signal from the LOS and multipath composite signal without extensively increasing the complexity of the receiver. Numbers of multipath mitigation techniques using dual-polarization antennas have been proposed and all of them report performance improvement over the single-polarization methods. However, due to the unpredictability of multipath, multipath mitigation techniques based on dual-polarization are not always effective while few studies discuss the condition under which the multipath mitigation using a dual-polarization antenna can outperform that using a single-polarization antenna, which is a fundamental question for dual-polarization multipath mitigation (DPMM) and the design of multipath mitigation algorithms. In this paper we analyze the characteristics of the signal received by a dual-polarization antenna and use the maximum likelihood estimation (MLE) to assess the theoretical performance of DPMM in different received signal cases. Based on the assessment we answer this fundamental question and find the dual-polarization antenna’s capability in mitigating short delay multipath—the most challenging one among all types of multipath for the majority of the multipath mitigation techniques. Considering these effective conditions, we propose a dual-polarization sequential iterative maximum likelihood estimation (DP-SIMLE) algorithm for DPMM. The simulation results verify our theory and show superior performance of the proposed DP-SIMLE algorithm over the traditional one using only an RHCP antenna. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

19 pages, 2312 KiB

Open AccessArticle

Optimal Resonant Band Demodulation Based on an Improved Correlated Kurtosis and Its Application in Bearing Fault Diagnosis

by Xianglong Chen¹, Bingzhi Zhang², Fuzhou Feng^1,* and Pengcheng Jiang¹

¹ Department of Mechanical Engineering, Academy of Armored Forces Engineering, Beijing 100072, China

² Beijing Special Vehicle Research Institute, Beijing 100072, China

Sensors 2017, 17(2), 360; https://doi.org/10.3390/s17020360 - 13 Feb 2017

Cited by 45 | Viewed by 5109

Abstract

The kurtosis-based indexes are usually used to identify the optimal resonant frequency band. However, kurtosis can only describe the strength of transient impulses, which cannot differentiate impulse noises and repetitive transient impulses cyclically generated in bearing vibration signals. As a result, it may [...] Read more.

The kurtosis-based indexes are usually used to identify the optimal resonant frequency band. However, kurtosis can only describe the strength of transient impulses, which cannot differentiate impulse noises and repetitive transient impulses cyclically generated in bearing vibration signals. As a result, it may lead to inaccurate results in identifying resonant frequency bands, in demodulating fault features and hence in fault diagnosis. In view of those drawbacks, this manuscript redefines the correlated kurtosis based on kurtosis and auto-correlative function, puts forward an improved correlated kurtosis based on squared envelope spectrum of bearing vibration signals. Meanwhile, this manuscript proposes an optimal resonant band demodulation method, which can adaptively determine the optimal resonant frequency band and accurately demodulate transient fault features of rolling bearings, by combining the complex Morlet wavelet filter and the Particle Swarm Optimization algorithm. Analysis of both simulation data and experimental data reveal that the improved correlated kurtosis can effectively remedy the drawbacks of kurtosis-based indexes and the proposed optimal resonant band demodulation is more accurate in identifying the optimal central frequencies and bandwidth of resonant bands. Improved fault diagnosis results in experiment verified the validity and advantage of the proposed method over the traditional kurtosis-based indexes. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

17 pages, 5389 KiB

Open AccessArticle

A Continuous Object Boundary Detection and Tracking Scheme for Failure-Prone Sensor Networks

by Sajida Imran and Young-Bae Ko^*

Department of Computer Engineering, Ajou University, Suwon 443749, Korea

Sensors 2017, 17(2), 361; https://doi.org/10.3390/s17020361 - 13 Feb 2017

Cited by 26 | Viewed by 5168

Abstract

In wireless sensor networks, detection and tracking of continuous natured objects is more challenging owing to their unique characteristics such as uneven expansion and contraction. A continuous object is usually spread over a large area, and, therefore, a substantial number of sensor nodes [...] Read more.

In wireless sensor networks, detection and tracking of continuous natured objects is more challenging owing to their unique characteristics such as uneven expansion and contraction. A continuous object is usually spread over a large area, and, therefore, a substantial number of sensor nodes are needed to detect the object. Nodes communicate with each other as well as with the sink to exchange control messages and report their detection status. The sink performs computations on the received data to estimate the object boundary. For accurate boundary estimation, nodes at the phenomenon boundary need to be carefully selected. Failure of one or multiple boundary nodes (BNs) can significantly affect the object detection and boundary estimation accuracy at the sink. We develop an efficient failure-prone object detection approach that not only detects and recovers from BN failures but also reduces the number and size of transmissions without compromising the boundary estimation accuracy. The proposed approach utilizes the spatial and temporal features of sensor nodes to detect object BNs. A Voronoi diagram-based network clustering, and failure detection and recovery scheme is used to increase boundary estimation accuracy. Simulation results show the significance of our approach in terms of energy efficiency, communication overhead, and boundary accuracy. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

19 pages, 11729 KiB

Open AccessArticle

Projections onto Convex Sets Super-Resolution Reconstruction Based on Point Spread Function Estimation of Low-Resolution Remote Sensing Images

by Chong Fan^1,2, Chaoyun Wu^1,*, Grand Li³ and Jun Ma^1,*

¹ School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

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

³ SiChuan Remote Sensing Geomatics Institute, NO. 2, Jianshe Road, Longquanyi District, Chengdu 610100, China

Sensors 2017, 17(2), 362; https://doi.org/10.3390/s17020362 - 13 Feb 2017

Cited by 37 | Viewed by 7561

Abstract

To solve the problem on inaccuracy when estimating the point spread function (PSF) of the ideal original image in traditional projection onto convex set (POCS) super-resolution (SR) reconstruction, this paper presents an improved POCS SR algorithm based on PSF estimation of low-resolution (LR) [...] Read more.

To solve the problem on inaccuracy when estimating the point spread function (PSF) of the ideal original image in traditional projection onto convex set (POCS) super-resolution (SR) reconstruction, this paper presents an improved POCS SR algorithm based on PSF estimation of low-resolution (LR) remote sensing images. The proposed algorithm can improve the spatial resolution of the image and benefit agricultural crop visual interpolation. The PSF of the highresolution (HR) image is unknown in reality. Therefore, analysis of the relationship between the PSF of the HR image and the PSF of the LR image is important to estimate the PSF of the HR image by using multiple LR images. In this study, the linear relationship between the PSFs of the HR and LR images can be proven. In addition, the novel slant knife-edge method is employed, which can improve the accuracy of the PSF estimation of LR images. Finally, the proposed method is applied to reconstruct airborne digital sensor 40 (ADS40) three-line array images and the overlapped areas of two adjacent GF-2 images by embedding the estimated PSF of the HR image to the original POCS SR algorithm. Experimental results show that the proposed method yields higher quality of reconstructed images than that produced by the blind SR method and the bicubic interpolation method. Full article

(This article belongs to the Special Issue Sensors and Smart Sensing of Agricultural Land Systems)

▼ Show Figures

Figure 1

15 pages, 4285 KiB

Open AccessArticle

Synthesis of Graphene-Based Sensors and Application on Detecting SF6 Decomposing Products: A Review

by Xiaoxing Zhang^1,2,*, Hao Cui¹ and Yingang Gui¹

¹ State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China

² School of Electrical Engineering, Wuhan University, Wuhan 430072, China

Sensors 2017, 17(2), 363; https://doi.org/10.3390/s17020363 - 13 Feb 2017

Cited by 47 | Viewed by 6337

Abstract

Graphene-based materials have aroused enormous focus on a wide range of engineering fields because of their unique structure. One of the most promising applications is gas adsorption and sensing. In electrical engineering, graphene-based sensors are also employed as detecting devices to estimate the [...] Read more.

Graphene-based materials have aroused enormous focus on a wide range of engineering fields because of their unique structure. One of the most promising applications is gas adsorption and sensing. In electrical engineering, graphene-based sensors are also employed as detecting devices to estimate the operation status of gas insulated switchgear (GIS). This paper reviews the main synthesis methods of graphene, gas adsorption, and sensing mechanism of its based sensors, as well as their applications in detecting SF6 decomposing products, such as SO2, H2S, SO2F2, and SOF2, in GIS. Both theoretical and experimental researches on gas response of graphene-based sensors to these typical gases are summarized. Finally, the future research trend about graphene synthesis technique and relevant perspective are also given. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

10 pages, 3499 KiB

Open AccessArticle

An Electromagnetic Sensor for the Autonomous Running of Visually Impaired and Blind Athletes (Part I: The Fixed Infrastructure)

by Marco Pieralisi¹, Valentina Di Mattia^1,*, Valerio Petrini¹, Alfredo De Leo¹, Giovanni Manfredi¹, Paola Russo¹, Lorenzo Scalise²

and Graziano Cerri¹

¹ Department of Information Engineering, Marche Polytechnic University, 60131 Ancona, Italy

² Department of Industrial Engineering and Mathematical Science, Marche Polytechnic University, 60131 Ancona, Italy

Sensors 2017, 17(2), 364; https://doi.org/10.3390/s17020364 - 14 Feb 2017

Cited by 17 | Viewed by 6150

Abstract

Sport is one of the best ways to promote the social integration of people affected by physical disability, because it helps them to increase their self-esteem by facing difficulties and overcoming their disabilities. Nowadays, a large number of sports can be easily played [...] Read more.

Sport is one of the best ways to promote the social integration of people affected by physical disability, because it helps them to increase their self-esteem by facing difficulties and overcoming their disabilities. Nowadays, a large number of sports can be easily played by visually impaired and blind athletes without any special supports, but, there are some disciplines that require the presence of a sighted guide. In this work, the attention will be focused on marathons, during which athletes with visual disorders have to be linked to the sighted guide by means of a non-stretchable elbow tether, with an evident reduction of their performance and autonomy. In this context, this paper presents a fixed electromagnetic infrastructure to equip a standard running racetrack in order to help a blind athlete to safely run without the presence of a sighted guide. The athlete runs inside an invisible hallway, just wearing a light and a comfortable sensor unit. The patented system has been homemade, designed, realized and finally tested by a blind Paralympic marathon champion with encouraging results and interesting suggestions for technical improvements. In this paper (Part I), the transmitting unit, whose main task is to generate the two magnetic fields that delimit the safe hallway, is presented and discussed. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 4740 KiB

Open AccessArticle

A Wearable Wireless Sensor Network for Indoor Smart Environment Monitoring in Safety Applications

by Diego Antolín^*

, Nicolás Medrano

, Belén Calvo and Francisco Pérez

Grupo de Diseño Electrónico (I3A), Departamento de Ingeniería Electrónica y Comunicaciones, Universidad de Zaragoza, C/Pedro Cerbuna 12, Zaragoza 50009, Spain

Sensors 2017, 17(2), 365; https://doi.org/10.3390/s17020365 - 14 Feb 2017

Cited by 73 | Viewed by 10806

Abstract

This paper presents the implementation of a wearable wireless sensor network aimed at monitoring harmful gases in industrial environments. The proposed solution is based on a customized wearable sensor node using a low-power low-rate wireless personal area network (LR-WPAN) communications protocol, which as [...] Read more.

This paper presents the implementation of a wearable wireless sensor network aimed at monitoring harmful gases in industrial environments. The proposed solution is based on a customized wearable sensor node using a low-power low-rate wireless personal area network (LR-WPAN) communications protocol, which as a first approach measures CO₂ concentration, and employs different low power strategies for appropriate energy handling which is essential to achieving long battery life. These wearables nodes are connected to a deployed static network and a web-based application allows data storage, remote control and monitoring of the complete network. Therefore, a complete and versatile remote web application with a locally implemented decision-making system is accomplished, which allows early detection of hazardous situations for exposed workers. Full article

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

▼ Show Figures

Figure 1

18 pages, 2654 KiB

Open AccessArticle

3D Imaging of Rapidly Spinning Space Targets Based on a Factorization Method

by Yanxian Bi, Shaoming Wei

, Jun Wang^* and Shiyi Mao

School of Electronic and Information Engineering, Beihang University, Beijing 100191, China

Sensors 2017, 17(2), 366; https://doi.org/10.3390/s17020366 - 14 Feb 2017

Cited by 5 | Viewed by 3930

Abstract

Three-dimensional (3D) imaging of space targets can provide crucial information about the target shape and size, which are significant supports for the application of automatic target classification and recognition. In this paper, a new 3D imaging of space spinning targets via a factorization [...] Read more.

Three-dimensional (3D) imaging of space targets can provide crucial information about the target shape and size, which are significant supports for the application of automatic target classification and recognition. In this paper, a new 3D imaging of space spinning targets via a factorization method is proposed. Firstly, after the translational compensation, the scattering centers two-dimensional (2D) range and range-rate sequence induced by the target spinning is extracted using a high resolution spectral estimation technique. Secondly, measurement data association is implemented to obtain the scattering center trajectory matrix by using a range-Doppler tracker. Then, we use an initial coarse angular velocity to generate the projection matrix, which consists of the scattering centers range and cross-range, and a factorization method is applied iteratively to the projection matrix to estimate the accurate angular velocity. Finally, we use the accurate estimate spinning angular velocity to rescale the projection matrix and the well-scaled target 3D geometry is reconstructed. Compared to the previous literature methods, ambiguity in the spatial axes can be removed by this method. Simulation results have demonstrated the effectiveness and robustness of the proposed method. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

24 pages, 5142 KiB

Open AccessReview

Micromachined Fluid Inertial Sensors

by Shiqiang Liu and Rong Zhu^*

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

Sensors 2017, 17(2), 367; https://doi.org/10.3390/s17020367 - 14 Feb 2017

Cited by 41 | Viewed by 8360

Abstract

Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, [...] Read more.

Micromachined fluid inertial sensors are an important class of inertial sensors, which mainly includes thermal accelerometers and fluid gyroscopes, which have now been developed since the end of the last century for about 20 years. Compared with conventional silicon or quartz inertial sensors, the fluid inertial sensors use a fluid instead of a solid proof mass as the moving and sensitive element, and thus offer advantages of simple structures, low cost, high shock resistance, and large measurement ranges while the sensitivity and bandwidth are not competitive. Many studies and various designs have been reported in the past two decades. This review firstly introduces the working principles of fluid inertial sensors, followed by the relevant research developments. The micromachined thermal accelerometers based on thermal convection have developed maturely and become commercialized. However, the micromachined fluid gyroscopes, which are based on jet flow or thermal flow, are less mature. The key issues and technologies of the thermal accelerometers, mainly including bandwidth, temperature compensation, monolithic integration of tri-axis accelerometers and strategies for high production yields are also summarized and discussed. For the micromachined fluid gyroscopes, improving integration and sensitivity, reducing thermal errors and cross coupling errors are the issues of most concern. Full article

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

▼ Show Figures

Figure 1

19 pages, 4446 KiB

Open AccessArticle

Uncertainty Analysis in Humidity Measurements by the Psychrometer Method

by Jiunyuan Chen and Chiachung Chen^*

Department of Bio-industrial Mechatronics Engineering, National ChungHsing University, Taichung 40227, Taiwan

Sensors 2017, 17(2), 368; https://doi.org/10.3390/s17020368 - 14 Feb 2017

Cited by 23 | Viewed by 9281

Abstract

The most common and cheap indirect technique to measure relative humidity is by using psychrometer based on a dry and a wet temperature sensor. In this study, the measurement uncertainty of relative humidity was evaluated by this indirect method with some empirical equations [...] Read more.

The most common and cheap indirect technique to measure relative humidity is by using psychrometer based on a dry and a wet temperature sensor. In this study, the measurement uncertainty of relative humidity was evaluated by this indirect method with some empirical equations for calculating relative humidity. Among the six equations tested, the Penman equation had the best predictive ability for the dry bulb temperature range of 15–50 °C. At a fixed dry bulb temperature, an increase in the wet bulb depression increased the error. A new equation for the psychrometer constant was established by regression analysis. This equation can be computed by using a calculator. The average predictive error of relative humidity was <0.1% by this new equation. The measurement uncertainty of the relative humidity affected by the accuracy of dry and wet bulb temperature and the numeric values of measurement uncertainty were evaluated for various conditions. The uncertainty of wet bulb temperature was the main factor on the RH measurement uncertainty. Full article

(This article belongs to the Special Issue Humidity Sensors)

▼ Show Figures

Figure 1

16 pages, 2081 KiB

Open AccessArticle

State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics

by Peter W. Tse^* and Dong Wang

Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Hong Kong, China

Sensors 2017, 17(2), 369; https://doi.org/10.3390/s17020369 - 14 Feb 2017

Cited by 14 | Viewed by 5098

Abstract

Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing [...] Read more.

Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL). Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI) so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

19 pages, 5270 KiB

Open AccessArticle

CSAC Characterization and Its Impact on GNSS Clock Augmentation Performance

by Enric Fernández^*, David Calero^* and M. Eulàlia Parés^*

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC/CERCA), Parc Mediterrani de la Tecnologia (PMT), Building B4, Av. Carl Friedrich Gauss 7, 08860 Castelldefels, Spain

Sensors 2017, 17(2), 370; https://doi.org/10.3390/s17020370 - 14 Feb 2017

Cited by 24 | Viewed by 9131

Abstract

Chip Scale Atomic Clocks (CSAC) are recently-developed electronic instruments that, when used together with a Global Navigation Satellite Systems (GNSS) receiver, help improve the performance of GNSS navigation solutions in certain conditions (i.e., low satellite visibility). Current GNSS receivers include a Temperature Compensated [...] Read more.

Chip Scale Atomic Clocks (CSAC) are recently-developed electronic instruments that, when used together with a Global Navigation Satellite Systems (GNSS) receiver, help improve the performance of GNSS navigation solutions in certain conditions (i.e., low satellite visibility). Current GNSS receivers include a Temperature Compensated Cristal Oscillator (TCXO) clock characterized by a short-term stability (τ = 1 s) of 10⁻⁹ s that leads to an error of 0.3 m in pseudorange measurements. The CSAC can achieve a short-term stability of 2.5 × 10⁻¹² s, which implies a range error of 0.075 m, making for an 87.5% improvement over TCXO. Replacing the internal TCXO clock of GNSS receivers with a higher frequency stability clock such as a CSAC oscillator improves the navigation solution in terms of low satellite visibility positioning accuracy, solution availability, signal recovery (holdover), multipath and jamming mitigation and spoofing attack detection. However, CSAC suffers from internal systematic instabilities and errors that should be minimized if optimal performance is desired. Hence, for operating CSAC at its best, the deterministic errors from the CSAC need to be properly modelled. Currently, this modelling is done by determining and predicting the clock frequency stability (i.e., clock bias and bias rate) within the positioning estimation process. The research presented in this paper aims to go a step further, analysing the correlation between temperature and clock stability noise and the impact of its proper modelling in the holdover recovery time and in the positioning performance. Moreover, it shows the potential of fine clock coasting modelling. With the proposed model, an improvement in vertical positioning precision of around 50% with only three satellites can be achieved. Moreover, an increase in the navigation solution availability is also observed, a reduction of holdover recovery time from dozens of seconds to only a few can be achieved. Full article

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

▼ Show Figures

Figure 1

15 pages, 1261 KiB

Open AccessArticle

Initial Results from SQUID Sensor: Analysis and Modeling for the ELF/VLF Atmospheric Noise

by Huan Hao¹, Huali Wang^1,*, Liang Chen¹, Jun Wu², Longqing Qiu² and Liangliang Rong²

¹ College of Communications Engineering, PLA University of Science and Technology, Nanjing 210007, China

² Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China

Sensors 2017, 17(2), 371; https://doi.org/10.3390/s17020371 - 14 Feb 2017

Cited by 6 | Viewed by 6391

Abstract

In this paper, the amplitude probability density (APD) of the wideband extremely low frequency (ELF) and very low frequency (VLF) atmospheric noise is studied. The electromagnetic signals from the atmosphere, referred to herein as atmospheric noise, was recorded by a mobile low-temperature superconducting [...] Read more.

In this paper, the amplitude probability density (APD) of the wideband extremely low frequency (ELF) and very low frequency (VLF) atmospheric noise is studied. The electromagnetic signals from the atmosphere, referred to herein as atmospheric noise, was recorded by a mobile low-temperature superconducting quantum interference device (SQUID) receiver under magnetically unshielded conditions. In order to eliminate the adverse effect brought by the geomagnetic activities and powerline, the measured field data was preprocessed to suppress the baseline wandering and harmonics by symmetric wavelet transform and least square methods firstly. Then statistical analysis was performed for the atmospheric noise on different time and frequency scales. Finally, the wideband ELF/VLF atmospheric noise was analyzed and modeled separately. Experimental results show that, Gaussian model is appropriate to depict preprocessed ELF atmospheric noise by a hole puncher operator. While for VLF atmospheric noise, symmetric α-stable (SαS) distribution is more accurate to fit the heavy-tail of the envelope probability density function (pdf). Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

31 pages, 15946 KiB

Open AccessArticle

From Sensor Networks to Internet of Things. Bluetooth Low Energy, a Standard for This Evolution

by Diego Hortelano^1,*,†, Teresa Olivares^2,†, M. Carmen Ruiz^2,†

, Celia Garrido-Hidalgo^1,† and Vicente López^1,†

¹ Albacete Research Institute of Informatics, University of Castilla-La Mancha, 02071 Albacete, Spain

² Faculty of Computer Science Engineering, University of Castilla-La Mancha, 02071 Albacete, Spain

^† These authors contributed equally to this work

Sensors 2017, 17(2), 372; https://doi.org/10.3390/s17020372 - 14 Feb 2017

Cited by 71 | Viewed by 11627

Abstract

Current sensor networks need to be improved and updated to satisfy new essential requirements of the Internet of Things, where cutting-edge applications will appear. These requirements are: total coverage, zero fails (high performance), scalability and sustainability (hardware and software). We are going to [...] Read more.

Current sensor networks need to be improved and updated to satisfy new essential requirements of the Internet of Things, where cutting-edge applications will appear. These requirements are: total coverage, zero fails (high performance), scalability and sustainability (hardware and software). We are going to evaluate Bluetooth Low Energy as wireless transmission technology and as the ideal candidate for these improvements, due to its low power consumption, its low cost radio chips and its ability to communicate with users directly, using their smartphones or smartbands. However, this technology is relatively recent, and standard network topologies are not able to fulfil its new requirements. To address these shortcomings, the implementation of other more flexible topologies (as the mesh topology) will be very interesting. After studying it in depth, we have identified certain weaknesses, for example, specific devices are needed to provide network scalability, and the need to choose between high performance or sustainability. In this paper, after presenting the studies carried out on these new technologies, we propose a new packet format and a new BLE mesh topology, with two different configurations: Individual Mesh and Collaborative Mesh. Our results show how this topology improves the scalability, sustainability, coverage and performance. Full article

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

▼ Show Figures

Figure 1

14 pages, 1130 KiB

Open AccessArticle

Tracking the Turn Maneuvering Target Using the Multi-Target Bayes Filter with an Adaptive Estimation of Turn Rate

by Zong-xiang Liu^*, De-hui Wu

, Wei-xin Xie and Liang-qun Li

College of Information Engineering, Shenzhen University, Shenzhen 518060, China

Sensors 2017, 17(2), 373; https://doi.org/10.3390/s17020373 - 15 Feb 2017

Cited by 8 | Viewed by 3792

Abstract

Tracking the target that maneuvers at a variable turn rate is a challenging problem. The traditional solution for this problem is the use of the switching multiple models technique, which includes several dynamic models with different turn rates for matching the motion mode [...] Read more.

Tracking the target that maneuvers at a variable turn rate is a challenging problem. The traditional solution for this problem is the use of the switching multiple models technique, which includes several dynamic models with different turn rates for matching the motion mode of the target at each point in time. However, the actual motion mode of a target at any time may be different from all of the dynamic models, because these models are usually limited. To address this problem, we establish a formula for estimating the turn rate of a maneuvering target. By applying the estimation method of the turn rate to the multi-target Bayes (MB) filter, we develop a MB filter with an adaptive estimation of the turn rate, in order to track multiple maneuvering targets. Simulation results indicate that the MB filter with an adaptive estimation of the turn rate, is better than the existing filter at tracking the target that maneuvers at a variable turn rate. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

9 pages, 1833 KiB

Open AccessArticle

Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

by Xu Jiang¹, Keda Wang², Junqing Li³, Hui Zhan², Zhenan Song², Guohang Che² and Guohui Lyu^2,*

¹ College of Information Science and Technology, Heilongjiang University, Harbin 150080, China

² Research Center for Fiber Optic Sensing Technology National Local Joint Engineering, Electronic Engineering College, Heilongjiang University, Harbin 150080, China

³ Physics Department, Harbin Institute of Technology, Harbin 150001, China

Sensors 2017, 17(2), 374; https://doi.org/10.3390/s17020374 - 15 Feb 2017

Cited by 13 | Viewed by 5695

Abstract

This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature [...] Read more.

This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE) light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed. Full article

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

▼ Show Figures

Figure 1

9 pages, 5532 KiB

Open AccessArticle

Design of Novel FBG-Based Sensor of Differential Pressure with Magnetic Transfer

by Guohui Lyu¹, Guohang Che¹, Junqing Li², Xu Jiang^3,*, Keda Wang¹, Yueqiang Han¹ and Laixu Gao¹

¹ Research Center for Fiber Optic Sensing Technology National Local Joint Engineering, Electronic Engineering College, Heilongjiang University, Harbin 150080, China

² Physics Department, Harbin Institute of Technology, Harbin 150001, China

³ College of Information Science and Technology, Heilongjiang University, Harbin 150080, China

Sensors 2017, 17(2), 375; https://doi.org/10.3390/s17020375 - 15 Feb 2017

Cited by 7 | Viewed by 5868

Abstract

In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. [...] Read more.

In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. The test shows that the designed sensor is effective for measuring differential pressure in the range of 0~10 kPa with a sensitivity of 0.0112 nm/kPa, which can be used in environments with high temperature, strong corrosion and high overload measurements. Full article

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

▼ Show Figures

Figure 1

20 pages, 494 KiB

Open AccessArticle

Energy-Based Acoustic Source Localization Methods: A Survey

by Wei Meng^1,2

and Wendong Xiao^1,*

¹ School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China

² Temasek Laboratories, National University of Singapore, Singapore 117411, Singapore

Sensors 2017, 17(2), 376; https://doi.org/10.3390/s17020376 - 15 Feb 2017

Cited by 32 | Viewed by 6160

Abstract

Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers [...] Read more.

Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions. Full article

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

▼ Show Figures

Figure 1

19 pages, 365 KiB

Open AccessArticle

Performance Analysis of Physical Layer Security of Opportunistic Scheduling in Multiuser Multirelay Cooperative Networks

by Kyusung Shim¹, Nhu Tri Do²

and Beongku An^3,*

¹ Graduate School of Smart City Science Management, Hongik University, Seoul 30016, Korea

² Department of Electronics and Computer Engineering, Hongik University, Seoul 30016, Korea

³ Department of Computer and Information Communications Engineering, Hongik University, Seoul 30016, Korea

Sensors 2017, 17(2), 377; https://doi.org/10.3390/s17020377 - 15 Feb 2017

Cited by 17 | Viewed by 4971

Abstract

In this paper, we study the physical layer security (PLS) of opportunistic scheduling for uplink scenarios of multiuser multirelay cooperative networks. To this end, we propose a low-complexity, yet comparable secrecy performance source relay selection scheme, called the proposed source relay selection (PSRS) [...] Read more.

In this paper, we study the physical layer security (PLS) of opportunistic scheduling for uplink scenarios of multiuser multirelay cooperative networks. To this end, we propose a low-complexity, yet comparable secrecy performance source relay selection scheme, called the proposed source relay selection (PSRS) scheme. Specifically, the PSRS scheme first selects the least vulnerable source and then selects the relay that maximizes the system secrecy capacity for the given selected source. Additionally, the maximal ratio combining (MRC) technique and the selection combining (SC) technique are considered at the eavesdropper, respectively. Investigating the system performance in terms of secrecy outage probability (SOP), closed-form expressions of the SOP are derived. The developed analysis is corroborated through Monte Carlo simulation. Numerical results show that the PSRS scheme significantly improves the secure ability of the system compared to that of the random source relay selection scheme, but does not outperform the optimal joint source relay selection (OJSRS) scheme. However, the PSRS scheme drastically reduces the required amount of channel state information (CSI) estimations compared to that required by the OJSRS scheme, specially in dense cooperative networks. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

11 pages, 2352 KiB

Open AccessFeature PaperArticle

Collagen-Gold Nanoparticle Conjugates for Versatile Biosensing

by Sarah Unser, Samuel Holcomb, ReJeana Cary and Laura Sagle^*

Department of Chemistry, College of Arts and Sciences, University of Cincinnati, 301 West Clifton Court, Cincinnati, OH 45221-0172, USA

Sensors 2017, 17(2), 378; https://doi.org/10.3390/s17020378 - 15 Feb 2017

Cited by 28 | Viewed by 7309

Abstract

Integration of noble metal nanoparticles with proteins offers promising potential to create a wide variety of biosensors that possess both improved selectivity and versatility. The multitude of functionalities that proteins offer coupled with the unique optical properties of noble metal nanoparticles can allow [...] Read more.

Integration of noble metal nanoparticles with proteins offers promising potential to create a wide variety of biosensors that possess both improved selectivity and versatility. The multitude of functionalities that proteins offer coupled with the unique optical properties of noble metal nanoparticles can allow for the realization of simple, colorimetric sensors for a significantly larger range of targets. Herein, we integrate the structural protein collagen with 10 nm gold nanoparticles to develop a protein-nanoparticle conjugate which possess the functionality of the protein with the desired colorimetric properties of the nanoparticles. Applying the many interactions that collagen undergoes in the extracellular matrix, we are able to selectively detect both glucose and heparin with the same collagen-nanoparticle conjugate. Glucose is directly detected through the cross-linking of the collagen fibrils, which brings the attached nanoparticles into closer proximity, leading to a red-shift in the LSPR frequency. Conversely, heparin is detected through a competition assay in which heparin-gold nanoparticles are added to solution and compete with heparin in the solution for the binding sites on the collagen fibrils. The collagen-nanoparticle conjugates are shown to detect both glucose and heparin in the physiological range. Lastly, glucose is selectively detected in 50% mouse serum with the collagen-nanoparticle devices possessing a linear range of 3–25 mM, which is also within the physiologically relevant range. Full article

(This article belongs to the Special Issue Last Advances in Nanoplasmonics Biosensors)

▼ Show Figures

Figure 1

10 pages, 3931 KiB

Open AccessArticle

Detection of Atmospheric Methyl Mercaptan Using Wavelength Modulation Spectroscopy with Multicomponent Spectral Fitting

by Zhenhui Du^1,*

, Jiaxin Wan¹, Jinyi Li², Gang Luo¹, Hong Gao¹ and Yiwen Ma¹

¹ State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

² Key Laboratory of Advanced Electrical Engineering and Energy Technology, Tianjin Polytechnic University, Tianjin 300387, China

Sensors 2017, 17(2), 379; https://doi.org/10.3390/s17020379 - 16 Feb 2017

Cited by 13 | Viewed by 6199

Abstract

Detection of methyl mercaptan (CH₃SH) is essential for environmental atmosphere assessment and exhaled-breath analysis. This paper presents a sensitive CH₃SH sensor based on wavelength modulation spectroscopy (WMS) with a mid-infrared distributed feedback interband cascade laser (DFB-ICL). Multicomponent spectral fitting [...] Read more.

Detection of methyl mercaptan (CH₃SH) is essential for environmental atmosphere assessment and exhaled-breath analysis. This paper presents a sensitive CH₃SH sensor based on wavelength modulation spectroscopy (WMS) with a mid-infrared distributed feedback interband cascade laser (DFB-ICL). Multicomponent spectral fitting was used not only to enhance the sensitivity of the sensor but also to determine the concentration of interferents (atmospheric water and methane). The results showed that the uncertainties in the measurement of CH₃SH, H₂O, and CH₄ were less than 1.2%, 1.7% and 2.0%, respectively, with an integration time of 10 s. The CH₃SH detection limit was as low as 7.1 ppb with an integration time of 295 s. Overall, the reported sensor, boasting the merits of high sensitivity, can be used for atmospheric methyl mercaptan detection, as well as multiple components detection of methyl mercaptan, water, and methane, simultaneously. Full article

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

▼ Show Figures

Figure 1

22 pages, 1463 KiB

Open AccessArticle

An Auction-Based Spectrum Leasing Mechanism for Mobile Macro-Femtocell Networks of IoT

by Xin Chen¹, Lei Xing¹, Tie Qiu^2,*

and Zhuo Li¹

¹ School of Computer Science, Beijing Information Science and Technology University, Beijing 100101, China

² School of Software, Dalian University of Technology, Dalian 116620, China

Sensors 2017, 17(2), 380; https://doi.org/10.3390/s17020380 - 16 Feb 2017

Cited by 19 | Viewed by 5936

Abstract

The Internet of Things (IoT) is a vision of the upcoming society. It can provide pervasive communication between two or more entities using 4G-LTE (Long Term Evolution) communication technology. In 4G-LTE networks, there are two important problems: helping manage the spectrum demands of [...] Read more.

The Internet of Things (IoT) is a vision of the upcoming society. It can provide pervasive communication between two or more entities using 4G-LTE (Long Term Evolution) communication technology. In 4G-LTE networks, there are two important problems: helping manage the spectrum demands of IoT devices and achieving much more revenue with the limited resource. This paper proposes a pricing framework to investigate the spectrum leasing in mobile heterogeneous networks with single macrocell and multiple femtocells. We modeled the leasing procedure between the macrocell service provider (MSP) and femtocell holders (FHs) as an auction to motivate the MSP to lease its spectrum resource. All FHs act as the bidders, and the monopolist MSP acts as the auctioneer. In the auction, FHs submit their bids to rent the spectrum resource so that they can make a profit by selling it to their subscribers. The MSP determines the spectrum leasing amount and chooses the winning FHs by solving the dynamic programming-based 0–1 knapsack problem. In our proposed framework, we focus on the spectrum pricing strategy and revenue maximization of the MSP. The simulation results show that the proposed scheme provides effective motivation for the MSP to lease the spectrum to FHs, and both the MSP and FHs can benefit from spectrum leasing. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

▼ Show Figures

Figure 1

11 pages, 2455 KiB

Open AccessArticle

An Electromagnetic Sensor for the Autonomous Running of Visually Impaired and Blind Athletes (Part II: The Wearable Device)

by Marco Pieralisi¹, Valentina Di Mattia^1,*, Valerio Petrini¹, Alfredo De Leo¹, Giovanni Manfredi¹, Paola Russo¹, Lorenzo Scalise²

and Graziano Cerri¹

¹ Department of Information Engineering, Universita’ Politecnica delle Marche, 60121 Ancona, Italy

² Department of Industrial Engineering and Mathematical Science, Universita’ Politecnica delle Marche, 60121 Ancona, Italy

Sensors 2017, 17(2), 381; https://doi.org/10.3390/s17020381 - 16 Feb 2017

Cited by 17 | Viewed by 5606

Abstract

Currently, the availability of technology developed to increase the autonomy of visually impaired athletes during sports is limited. The research proposed in this paper (Part I and Part II) focuses on the realization of an electromagnetic system that can guide a blind runner [...] Read more.

Currently, the availability of technology developed to increase the autonomy of visually impaired athletes during sports is limited. The research proposed in this paper (Part I and Part II) focuses on the realization of an electromagnetic system that can guide a blind runner along a race track without the need for a sighted guide. In general, the system is composed of a transmitting unit (widely described in Part I) and a receiving unit, whose components and main features are described in this paper. Special attention is paid to the definition of an electromagnetic model able to faithfully represent the physical mechanisms of interaction between the two units, as well as between the receiving magnetic sensor and the body of the user wearing the device. This theoretical approach allows for an estimation of the signals to be detected, and guides the design of a suitable signal processing board. This technology has been realized, patented, and tested with a blind volunteer with successful results and this paper presents interesting suggestions for further improvements. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

15 pages, 3408 KiB

Open AccessArticle

Molecularly Imprinted Sol-Gel-Based QCM Sensor Arrays for the Detection and Recognition of Volatile Aldehydes

by Chuanjun Liu^1,*, Bartosz Wyszynski¹, Rui Yatabe¹, Kenshi Hayashi^1,2 and Kiyoshi Toko^1,2

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

² Graduate School of Information Science and Electrical Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan

Sensors 2017, 17(2), 382; https://doi.org/10.3390/s17020382 - 16 Feb 2017

Cited by 40 | Viewed by 7372

Abstract

The detection and recognition of metabolically derived aldehydes, which have been identified as important products of oxidative stress and biomarkers of cancers; are considered as an effective approach for early cancer detection as well as health status monitoring. Quartz crystal microbalance (QCM) sensor [...] Read more.

The detection and recognition of metabolically derived aldehydes, which have been identified as important products of oxidative stress and biomarkers of cancers; are considered as an effective approach for early cancer detection as well as health status monitoring. Quartz crystal microbalance (QCM) sensor arrays based on molecularly imprinted sol-gel (MISG) materials were developed in this work for highly sensitive detection and highly selective recognition of typical aldehyde vapors including hexanal (HAL); nonanal (NAL) and bezaldehyde (BAL). The MISGs were prepared by a sol-gel procedure using two matrix precursors: tetraethyl orthosilicate (TEOS) and tetrabutoxytitanium (TBOT). Aminopropyltriethoxysilane (APT); diethylaminopropyltrimethoxysilane (EAP) and trimethoxy-phenylsilane (TMP) were added as functional monomers to adjust the imprinting effect of the matrix. Hexanoic acid (HA); nonanoic acid (NA) and benzoic acid (BA) were used as psuedotemplates in view of their analogous structure to the target molecules as well as the strong hydrogen-bonding interaction with the matrix. Totally 13 types of MISGs with different components were prepared and coated on QCM electrodes by spin coating. Their sensing characters towards the three aldehyde vapors with different concentrations were investigated qualitatively. The results demonstrated that the response of individual sensors to each target strongly depended on the matrix precursors; functional monomers and template molecules. An optimization of the 13 MISG materials was carried out based on statistical analysis such as principle component analysis (PCA); multivariate analysis of covariance (MANCOVA) and hierarchical cluster analysis (HCA). The optimized sensor array consisting of five channels showed a high discrimination ability on the aldehyde vapors; which was confirmed by quantitative comparison with a randomly selected array. It was suggested that both the molecularly imprinting (MIP) effect and the matrix effect contributed to the sensitivity and selectivity of the optimized sensor array. The developed MISGs were expected to be promising materials for the detection and recognition of volatile aldehydes contained in exhaled breath or human body odor. Full article

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

▼ Show Figures

Figure 1

11 pages, 1268 KiB

Open AccessArticle

Electrochemical Oxidation of l-selenomethionine and Se-methylseleno-l-cysteine at a Thiol-Compound-Modified Gold Electrode: Its Application in a Flow-Through Voltammetric Sensor

by Lai-Hao Wang^* and Yu-Han Zhang

Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, 60 Erh-Jen Road, Section 1, Rende, Tainan 71743, Taiwan

Sensors 2017, 17(2), 383; https://doi.org/10.3390/s17020383 - 16 Feb 2017

Cited by 5 | Viewed by 6375

Abstract

A flow-electrolytic cell that consists of a bare gold wire or of different thiol-compound-modified gold electrodes (such as 2,4-thiazolidinedione, 2-mercapto-5-thiazoline, 2-mercaptothiazoline, l-cysteine, thioglycolic acid) was designed to be used in a voltammetric detector to identify l-selenomethionine and Se-methylseleno-l-cysteine using [...] Read more.

A flow-electrolytic cell that consists of a bare gold wire or of different thiol-compound-modified gold electrodes (such as 2,4-thiazolidinedione, 2-mercapto-5-thiazoline, 2-mercaptothiazoline, l-cysteine, thioglycolic acid) was designed to be used in a voltammetric detector to identify l-selenomethionine and Se-methylseleno-l-cysteine using high-performance liquid chromatography. Both l-selenomethionine and Se-methylseleno-l-cysteine are more efficiently electrochemically oxidized on a thiol/gold than on a bare gold electrode. For the DC mode, and for measurements with suitable experimental parameters, a linear concentration from 10 to 1600 ng·mL⁻¹ was found. The limits of quantification for l-selenomethionine and Se-methylseleno-l-cysteine were below 10 ng·mL⁻¹. The method can be applied to the quantitative determination of l-selenomethionine and Se-methylseleno-l-cysteine in commercial selenium-containing supplement products. Findings using high-performance liquid chromatography with a flow-through voltammetric detector and ultraviolet detector are comparable. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

16 pages, 3790 KiB

Open AccessArticle

A Hierarchical Framework Combining Motion and Feature Information for Infrared-Visible Video Registration

by Xinglong Sun¹, Tingfa Xu^1,2,*, Jizhou Zhang¹ and Xiangmin Li¹

¹ School of Optoelectronics, Image Engineering & Video Technology Lab, Beijing Institute of Technology, Beijing 100081, China

² Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Beijing 100081, China

Sensors 2017, 17(2), 384; https://doi.org/10.3390/s17020384 - 16 Feb 2017

Cited by 10 | Viewed by 5038

Abstract

In this paper, we propose a novel hierarchical framework that combines motion and feature information to implement infrared-visible video registration on nearly planar scenes. In contrast to previous approaches, which involve the direct use of feature matching to find the global homography, the [...] Read more.

In this paper, we propose a novel hierarchical framework that combines motion and feature information to implement infrared-visible video registration on nearly planar scenes. In contrast to previous approaches, which involve the direct use of feature matching to find the global homography, the framework adds coarse registration based on the motion vectors of targets to estimate scale and rotation prior to matching. In precise registration based on keypoint matching, the scale and rotation are used in re-location to eliminate their impact on targets and keypoints. To strictly match the keypoints, first, we improve the quality of keypoint matching by using normalized location descriptors and descriptors generated by the histogram of edge orientation. Second, we remove most mismatches by counting the matching directions of correspondences. We tested our framework on a public dataset, where our proposed framework outperformed two recently-proposed state-of-the-art global registration methods in almost all tested videos. Full article

(This article belongs to the Special Issue Infrared Detectors)

▼ Show Figures

Figure 1

16 pages, 1215 KiB

Open AccessArticle

A Robust Random Forest-Based Approach for Heart Rate Monitoring Using Photoplethysmography Signal Contaminated by Intense Motion Artifacts

by Yalan Ye¹, Wenwen He¹, Yunfei Cheng¹

, Wenxia Huang^2,* and Zhilin Zhang^3,*

¹ School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

² West China Hospital of Sichuan University, Chengdu 610041, China

³ Samsung Research America—Dallas, Richardson, TX 75082, USA

Sensors 2017, 17(2), 385; https://doi.org/10.3390/s17020385 - 16 Feb 2017

Cited by 39 | Viewed by 8606

Abstract

The estimation of heart rate (HR) based on wearable devices is of interest in fitness. Photoplethysmography (PPG) is a promising approach to estimate HR due to low cost; however, it is easily corrupted by motion artifacts (MA). In this work, a robust approach [...] Read more.

The estimation of heart rate (HR) based on wearable devices is of interest in fitness. Photoplethysmography (PPG) is a promising approach to estimate HR due to low cost; however, it is easily corrupted by motion artifacts (MA). In this work, a robust approach based on random forest is proposed for accurately estimating HR from the photoplethysmography signal contaminated by intense motion artifacts, consisting of two stages. Stage 1 proposes a hybrid method to effectively remove MA with a low computation complexity, where two MA removal algorithms are combined by an accurate binary decision algorithm whose aim is to decide whether or not to adopt the second MA removal algorithm. Stage 2 proposes a random forest-based spectral peak-tracking algorithm, whose aim is to locate the spectral peak corresponding to HR, formulating the problem of spectral peak tracking into a pattern classification problem. Experiments on the PPG datasets including 22 subjects used in the 2015 IEEE Signal Processing Cup showed that the proposed approach achieved the average absolute error of 1.65 beats per minute (BPM) on the 22 PPG datasets. Compared to state-of-the-art approaches, the proposed approach has better accuracy and robustness to intense motion artifacts, indicating its potential use in wearable sensors for health monitoring and fitness tracking. Full article

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

▼ Show Figures

Figure 1

9 pages, 8719 KiB

Open AccessArticle

Detection of Salmonella Typhimurium on Spinach Using Phage-Based Magnetoelastic Biosensors

by Fengen Wang^1,*, Shin Horikawa², Jiajia Hu³, Howard C. Wikle III²

, I-Hsuan Chen⁴, Songtao Du², Yuzhe Liu² and Bryan A. Chin²

¹ Institute of Quality Standard and Testing Technology for Agro-Products, Shandong Academy of Agricultural Sciences, Jinan 250100, China

² Materials Research and Education Center, Auburn University, Auburn, AL 36849, USA

³ Jiangsu Key Laboratory of Materials Surface Technology, School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China

⁴ Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA

Sensors 2017, 17(2), 386; https://doi.org/10.3390/s17020386 - 16 Feb 2017

Cited by 35 | Viewed by 5899

Abstract

Phage-based magnetoelastic (ME) biosensors have been studied as an in-situ, real-time, wireless, direct detection method of foodborne pathogens in recent years. This paper investigates an ME biosensor method for the detection of Salmonella Typhimurium on fresh spinach leaves. A procedure to obtain a [...] Read more.

Phage-based magnetoelastic (ME) biosensors have been studied as an in-situ, real-time, wireless, direct detection method of foodborne pathogens in recent years. This paper investigates an ME biosensor method for the detection of Salmonella Typhimurium on fresh spinach leaves. A procedure to obtain a concentrated suspension of Salmonella from contaminated spinach leaves is described that is based on methods outlined in the U.S. FDA Bacteriological Analytical Manual for the detection of Salmonella on leafy green vegetables. The effects of an alternative pre-enrichment broth (LB broth vs. lactose broth), incubation time on the detection performance and negative control were investigated. In addition, different blocking agents (BSA, Casein, and Superblock) were evaluated to minimize the effect of nonspecific binding. None of the blocking agents was found to be superior to the others, or even better than none. Unblocked ME biosensors were placed directly in a concentrated suspension and allowed to bind with Salmonella cells for 30 min before measuring the resonant frequency using a surface-scanning coil detector. It was found that 7 h incubation at 37 °C in LB broth was necessary to detect an initial spike of 100 cfu/25 g S. Typhimurium on spinach leaves with a confidence level of difference greater than 95% (p < 0.05). Thus, the ME biosensor method, on both partly and fully detection, was demonstrated to be a robust and competitive method for foodborne pathogens on fresh products. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

11 pages, 3624 KiB

Open AccessArticle

A Low-G Silicon Inertial Micro-Switch with Enhanced Contact Effect Using Squeeze-Film Damping

by Yingchun Peng^1,2,*

, Zhiyu Wen^1,2, Dongling Li^1,2 and Zhengguo Shang^1,2

¹ Microsystem Research Center, Chongqing University, Chongqing 400044, China

² Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology, Chongqing University, Chongqing 400044, China

Sensors 2017, 17(2), 387; https://doi.org/10.3390/s17020387 - 16 Feb 2017

Cited by 13 | Viewed by 5439

Abstract

Contact time is one of the most important properties for inertial micro-switches. However, it is usually less than 20 μs for the switch with rigid electrode, which is difficult for the external circuit to recognize. This issue is traditionally addressed by designing the [...] Read more.

Contact time is one of the most important properties for inertial micro-switches. However, it is usually less than 20 μs for the switch with rigid electrode, which is difficult for the external circuit to recognize. This issue is traditionally addressed by designing the switch with a keep-close function or flexible electrode. However, the switch with keep-close function requires an additional operation to re-open itself, causing inconvenience for some applications wherein repeated monitoring is needed. The switch with a flexible electrode is usually fabricated by electroplating technology, and it is difficult to realize low-g switches (<50 g) due to inherent fabrication errors. This paper reports a contact enhancement using squeeze-film damping effect for low-g switches. A vertically driven switch with large proof mass and flexible springs was designed based on silicon micromachining, in order to achieve a damping ratio of 2 and a threshold value of 10 g. The proposed contact enhancement was investigated by theoretical and experimental studies. The results show that the damping effect can not only prolong the contact time for the dynamic acceleration load, but also reduce the contact bounce for the quasi-static acceleration load. The contact time under dynamic and quasi-static loads was 40 μs and 570 μs, respectively. Full article

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

▼ Show Figures

Figure 1

15 pages, 1542 KiB

Open AccessArticle

Differential Characteristics Based Iterative Multiuser Detection for Wireless Sensor Networks

by Xiaoguang Chen^1,2, Xu Jiang³

, Zhilu Wu^3,* and Shufeng Zhuang³

¹ School of Astronautics, Harbin Institute of Technology, Harbin 150001, China

² China Academy of Space Technology, Beijing 100089, China

³ School of Electronics and Information Engineering, Harbin Institute of Technology, Harbin 150001, China

Sensors 2017, 17(2), 388; https://doi.org/10.3390/s17020388 - 16 Feb 2017

Cited by 3 | Viewed by 4316

Abstract

High throughput, low latency and reliable communication has always been a hot topic for wireless sensor networks (WSNs) in various applications. Multiuser detection is widely used to suppress the bad effect of multiple access interference in WSNs. In this paper, a novel multiuser [...] Read more.

High throughput, low latency and reliable communication has always been a hot topic for wireless sensor networks (WSNs) in various applications. Multiuser detection is widely used to suppress the bad effect of multiple access interference in WSNs. In this paper, a novel multiuser detection method based on differential characteristics is proposed to suppress multiple access interference. The proposed iterative receive method consists of three stages. Firstly, a differential characteristics function is presented based on the optimal multiuser detection decision function; then on the basis of differential characteristics, a preliminary threshold detection is utilized to find the potential wrongly received bits; after that an error bit corrector is employed to correct the wrong bits. In order to further lower the bit error ratio (BER), the differential characteristics calculation, threshold detection and error bit correction process described above are iteratively executed. Simulation results show that after only a few iterations the proposed multiuser detection method can achieve satisfactory BER performance. Besides, BER and near far resistance performance are much better than traditional suboptimal multiuser detection methods. Furthermore, the proposed iterative multiuser detection method also has a large system capacity. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

▼ Show Figures

Figure 1

12 pages, 3629 KiB

Open AccessArticle

Theoretical Analysis of an Optical Accelerometer Based on Resonant Optical Tunneling Effect

by Aoqun Jian^1,2, Chongguang Wei^1,2, Lifang Guo³, Jie Hu^1,2, Jun Tang^4,5, Jun Liu^4,5, Xuming Zhang^6,*

and Shengbo Sang^1,2,*

¹ MicroNano System Research Center, Taiyuan University of Technology, Taiyuan 030024, China

² Key Laboratory of Advanced Transducers and Intelligent Control System, Shanxi Province and Ministry of Education, Taiyuan 030024, China

³ Laboratory of Wireless Communication Network, Taiyuan University of Technology, Taiyuan 030024, China

⁴ State Key Laboratory of Science and Technology on Electronic Test & Measurement, North University of China, Taiyuan 030051, China

⁵ Key Laboratory of Instrumentation Science & Dynamic Measurement, North University of China, Ministry of Education, Taiyuan 030051, China

⁶ Department of Applied Physics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Sensors 2017, 17(2), 389; https://doi.org/10.3390/s17020389 - 17 Feb 2017

Cited by 20 | Viewed by 6080

Abstract

Acceleration is a significant parameter for monitoring the status of a given objects. This paper presents a novel linear acceleration sensor that functions via a unique physical mechanism, the resonant optical tunneling effect (ROTE). The accelerometer consists of a fixed frame, two elastic [...] Read more.

Acceleration is a significant parameter for monitoring the status of a given objects. This paper presents a novel linear acceleration sensor that functions via a unique physical mechanism, the resonant optical tunneling effect (ROTE). The accelerometer consists of a fixed frame, two elastic cantilevers, and a major cylindrical mass comprised of a resonant cavity that is separated by two air tunneling gaps in the middle. The performance of the proposed sensor was analyzed with a simplified mathematical model, and simulated using finite element modeling. The simulation results showed that the optical Q factor and the sensitivity of the accelerometer reach up to 8.857 × 10⁷ and 9 pm/g, respectively. The linear measurement range of the device is ±130 g. The work bandwidth obtained is located in 10–1500 Hz. The results of this study provide useful guidelines to improve measurement range and resolution of integrated optical acceleration sensors. Full article

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

▼ Show Figures

Figure 1

21 pages, 2468 KiB

Open AccessFeature PaperReview

Capacitive Biosensors and Molecularly Imprinted Electrodes

by Gizem Ertürk^1,* and Bo Mattiasson^1,2

¹ CapSenze Biosystems AB, Lund 223 63, Sweden

² Department of Biotechnology, Lund University, Lund 222 40, Sweden

Sensors 2017, 17(2), 390; https://doi.org/10.3390/s17020390 - 17 Feb 2017

Cited by 62 | Viewed by 9007

Abstract

Capacitive biosensors belong to the group of affinity biosensors that operate by registering direct binding between the sensor surface and the target molecule. This type of biosensors measures the changes in dielectric properties and/or thickness of the dielectric layer at the electrolyte/electrode interface. [...] Read more.

Capacitive biosensors belong to the group of affinity biosensors that operate by registering direct binding between the sensor surface and the target molecule. This type of biosensors measures the changes in dielectric properties and/or thickness of the dielectric layer at the electrolyte/electrode interface. Capacitive biosensors have so far been successfully used for detection of proteins, nucleotides, heavy metals, saccharides, small organic molecules and microbial cells. In recent years, the microcontact imprinting method has been used to create very sensitive and selective biorecognition cavities on surfaces of capacitive electrodes. This chapter summarizes the principle and different applications of capacitive biosensors with an emphasis on microcontact imprinting method with its recent capacitive biosensor applications. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

▼ Show Figures

Figure 1

19 pages, 1452 KiB

Open AccessFeature PaperReview

Nanomaterials for the Selective Detection of Hydrogen Sulfide in Air

by Eduard Llobet^1,*

, Jérôme Brunet², Alain Pauly²

, Amadou Ndiaye²

and Christelle Varenne²

¹ MINOS-EMaS, Universitat Rovira i Virgili, E-43007 Tarragona, Spain

² CNRS, Institut Pascal, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France

Sensors 2017, 17(2), 391; https://doi.org/10.3390/s17020391 - 17 Feb 2017

Cited by 49 | Viewed by 10570

Abstract

This paper presents a focused review on the nanomaterials and associated transduction schemes that have been developed for the selective detection of hydrogen sulfide. It presents a quite comprehensive overview of the latest developments, briefly discusses the hydrogen sulfide detection mechanisms, identifying the [...] Read more.

This paper presents a focused review on the nanomaterials and associated transduction schemes that have been developed for the selective detection of hydrogen sulfide. It presents a quite comprehensive overview of the latest developments, briefly discusses the hydrogen sulfide detection mechanisms, identifying the reasons for the selectivity (or lack of) observed experimentally. It critically reviews performance, shortcomings, and identifies missing or overlooked important aspects. It identifies the most mature/promising materials and approaches for achieving inexpensive hydrogen sulfide sensors that could be employed in widespread, miniaturized, and inexpensive detectors and, suggests what research should be undertaken for ensuring that requirements are met. Full article

(This article belongs to the Special Issue Gas Nanosensors)

▼ Show Figures

Figure 1

18 pages, 12551 KiB

Open AccessArticle

Middleware Design for Swarm-Driving Robots Accompanying Humans

by Min Su Kim¹, Sang Hyuck Kim¹ and Soon Ju Kang^2,*

¹ Department of Software Convergence, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 702-701, Korea

² School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 702-701, Korea

Sensors 2017, 17(2), 392; https://doi.org/10.3390/s17020392 - 17 Feb 2017

Cited by 3 | Viewed by 5452

Abstract

Research on robots that accompany humans is being continuously studied. The Pet-Bot provides walking-assistance and object-carrying services without any specific controls through interaction between the robot and the human in real time. However, with Pet-Bot, there is a limit to the number of [...] Read more.

Research on robots that accompany humans is being continuously studied. The Pet-Bot provides walking-assistance and object-carrying services without any specific controls through interaction between the robot and the human in real time. However, with Pet-Bot, there is a limit to the number of robots a user can use. If this limit is overcome, the Pet-Bot can provide services in more areas. Therefore, in this study, we propose a swarm-driving middleware design adopting the concept of a swarm, which provides effective parallel movement to allow multiple human-accompanying robots to accomplish a common purpose. The functions of middleware divide into three parts: a sequence manager for swarm process, a messaging manager, and a relative-location identification manager. This middleware processes the sequence of swarm-process of robots in the swarm through message exchanging using radio frequency (RF) communication of an IEEE 802.15.4 MAC protocol and manages an infrared (IR) communication module identifying relative location with IR signal strength. The swarm in this study is composed of the master interacting with the user and the slaves having no interaction with the user. This composition is intended to control the overall swarm in synchronization with the user activity, which is difficult to predict. We evaluate the accuracy of the relative-location estimation using IR communication, the response time of the slaves to a change in user activity, and the time to organize a network according to the number of slaves. Full article

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

▼ Show Figures

Figure 1

14 pages, 727 KiB

Open AccessArticle

Smooth Sensor Motion Planning for Robotic Cyber Physical Social Sensing (CPSS)

by Hong Tang¹

, Liangzhi Li^2,*

and Nanfeng Xiao¹

¹ School of Computer Science & Engineering, South China University of Technology, Guangzhou 510641, China

² Department of Information and Electronic Engineering, Muroran Institute of Technology, Muroran 050-0071, Japan

Sensors 2017, 17(2), 393; https://doi.org/10.3390/s17020393 - 17 Feb 2017

Cited by 6 | Viewed by 5031

Abstract

Although many researchers have begun to study the area of Cyber Physical Social Sensing (CPSS), few are focused on robotic sensors. We successfully utilize robots in CPSS, and propose a sensor trajectory planning method in this paper. Trajectory planning is a fundamental problem [...] Read more.

Although many researchers have begun to study the area of Cyber Physical Social Sensing (CPSS), few are focused on robotic sensors. We successfully utilize robots in CPSS, and propose a sensor trajectory planning method in this paper. Trajectory planning is a fundamental problem in mobile robotics. However, traditional methods are not suited for robotic sensors, because of their low efficiency, instability, and non-smooth-generated paths. This paper adopts an optimizing function to generate several intermediate points and regress these discrete points to a quintic polynomial which can output a smooth trajectory for the robotic sensor. Simulations demonstrate that our approach is robust and efficient, and can be well applied in the CPSS field. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

▼ Show Figures

Figure 1

23 pages, 8967 KiB

Open AccessArticle

A High Performance Piezoelectric Sensor for Dynamic Force Monitoring of Landslide

by Ming Li^*

, Wei Cheng^*, Jiangpan Chen, Ruili Xie and Xiongfei Li

Institute of Solid Mechanics, Beihang University, Beijing 100191, China

Sensors 2017, 17(2), 394; https://doi.org/10.3390/s17020394 - 17 Feb 2017

Cited by 31 | Viewed by 6959

Abstract

Due to the increasing influence of human engineering activities, it is important to monitor the transient disturbance during the evolution process of landslide. For this purpose, a high-performance piezoelectric sensor is presented in this paper. To adapt the high static and dynamic stress [...] Read more.

Due to the increasing influence of human engineering activities, it is important to monitor the transient disturbance during the evolution process of landslide. For this purpose, a high-performance piezoelectric sensor is presented in this paper. To adapt the high static and dynamic stress environment in slope engineering, two key techniques, namely, the self-structure pressure distribution method (SSPDM) and the capacitive circuit voltage distribution method (CCVDM) are employed in the design of the sensor. The SSPDM can greatly improve the compressive capacity and the CCVDM can quantitatively decrease the high direct response voltage. Then, the calibration experiments are conducted via the independently invented static and transient mechanism since the conventional testing machines cannot match the calibration requirements. The sensitivity coefficient is obtained and the results reveal that the sensor has the characteristics of high compressive capacity, stable sensitivities under different static preload levels and wide-range dynamic measuring linearity. Finally, to reduce the measuring error caused by charge leakage of the piezoelectric element, a low-frequency correction method is proposed and experimental verified. Therefore, with the satisfactory static and dynamic properties and the improving low-frequency measuring reliability, the sensor can complement dynamic monitoring capability of the existing landslide monitoring and forecasting system. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

21 pages, 6065 KiB

Open AccessArticle

A Delay-Aware and Reliable Data Aggregation for Cyber-Physical Sensing

by Jinhuan Zhang, Jun Long^*

, Chengyuan Zhang and Guihu Zhao

School of Information Science and Engineering, Central South University, Changsha 410083, China

Sensors 2017, 17(2), 395; https://doi.org/10.3390/s17020395 - 17 Feb 2017

Cited by 12 | Viewed by 4212

Abstract

Physical information sensed by various sensors in a cyber-physical system should be collected for further operation. In many applications, data aggregation should take reliability and delay into consideration. To address these problems, a novel Tiered Structure Routing-based Delay-Aware and Reliable Data Aggregation scheme [...] Read more.

Physical information sensed by various sensors in a cyber-physical system should be collected for further operation. In many applications, data aggregation should take reliability and delay into consideration. To address these problems, a novel Tiered Structure Routing-based Delay-Aware and Reliable Data Aggregation scheme named TSR-DARDA for spherical physical objects is proposed. By dividing the spherical network constructed by dispersed sensor nodes into circular tiers with specifically designed widths and cells, TSTR-DARDA tries to enable as many nodes as possible to transmit data simultaneously. In order to ensure transmission reliability, lost packets are retransmitted. Moreover, to minimize the latency while maintaining reliability for data collection, in-network aggregation and broadcast techniques are adopted to deal with the transmission between data collecting nodes in the outer layer and their parent data collecting nodes in the inner layer. Thus, the optimization problem is transformed to minimize the delay under reliability constraints by controlling the system parameters. To demonstrate the effectiveness of the proposed scheme, we have conducted extensive theoretical analysis and comparisons to evaluate the performance of TSR-DARDA. The analysis and simulations show that TSR-DARDA leads to lower delay with reliability satisfaction. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

▼ Show Figures

Figure 1

16 pages, 3365 KiB

Open AccessArticle

Steady γ-Ray Effects on the Performance of PPP-BOTDA and TW-COTDR Fiber Sensing

by Isabelle Planes^1,2,*, Sylvain Girard¹, Aziz Boukenter¹

, Emmanuel Marin¹, Sylvie Delepine-Lesoille², Claude Marcandella³ and Youcef Ouerdane¹

¹ Univ Lyon, Laboratoire Hubert Curien (LabHC), Université de Lyon, CNRS UMR 5516, F-42000 Saint-Etienne, France

² Agence Nationale Pour la gestion des Déchets Radioactifs (Andra), F-92298 Châtenay-Malabry, France

³ CEA DAM DIF (French Alternative Energies and Atomic Energy Commission), F-91297 Arpajon, France

Sensors 2017, 17(2), 396; https://doi.org/10.3390/s17020396 - 17 Feb 2017

Cited by 11 | Viewed by 5089

Abstract

We investigated the evolution of the performances of Pulse Pre Pump-Brillouin Time Domain Analysis (PPP-BOTDA) and Tunable Wavelength Coherent Optical Time Domain Reflectometry (TW-COTDR) fiber-based temperature and strain sensors when the sensing optical fiber is exposed to two γ-ray irradiation conditions: (i) at [...] Read more.

We investigated the evolution of the performances of Pulse Pre Pump-Brillouin Time Domain Analysis (PPP-BOTDA) and Tunable Wavelength Coherent Optical Time Domain Reflectometry (TW-COTDR) fiber-based temperature and strain sensors when the sensing optical fiber is exposed to two γ-ray irradiation conditions: (i) at room temperature and a dose rate of 370 Gy(SiO2)/h up to a total ionizing dose (TID) of 56 kGy; (ii) at room temperature and a dose rate of 25 kGy(SiO2)/h up to a TID of 10 MGy. Two main different classes of single-mode optical fibers have been tested in situ, radiation-tolerant ones: fluorine-doped or nitrogen-doped core fibers, as well as Telecom-grade germanosilicate ones. Brillouin and Rayleigh Sensitivities of N-Doped fibers were not reported yet, and these characterizations pave the way for a novel and alternative sensing scheme. Moreover, in these harsh conditions, our results showed that the main parameter affecting the sensor sensitivity remains the Radiation Induced Attenuation (RIA) at its operation wavelength of 1550 nm. RIA limits the maximal sensing range but does not influence the measurement uncertainty. F-doped fiber is the most tolerant against RIA with induced losses below 8 dB/km after a 56 kGy accumulated dose whereas the excess losses of other fibers exceed 22 dB/km. Both Rayleigh and Brillouin signatures that are exploited by the PPP-BOTDA and the TW-COTDR remain unchanged (within our experimental uncertainties). The strain and temperature coefficients of the various fibers under test are not modified by radiations, at these dose/dose rate levels. Consequently, this enables the design of a robust strain and temperature sensing architecture for the monitoring of radioactive waste disposals. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

10 pages, 3023 KiB

Open AccessArticle

UW Imaging of Seismic-Physical-Models in Air Using Fiber-Optic Fabry-Perot Interferometer

by Qiangzhou Rong, Yongxin Hao, Ruixiang Zhou, Xunli Yin, Zhihua Shao, Lei Liang and Xueguang Qiao^*

Physics Department, Northwest University, No.229, Taibai Road (North), Xi’an 710069, China

Sensors 2017, 17(2), 397; https://doi.org/10.3390/s17020397 - 17 Feb 2017

Cited by 20 | Viewed by 5851

Abstract

A fiber-optic Fabry-Perot interferometer (FPI) has been proposed and demonstrated for the ultrasound wave (UW) imaging of seismic-physical models. The sensor probe comprises a single mode fiber (SMF) that is inserted into a ceramic tube terminated by an ultra-thin gold film. The probe [...] Read more.

A fiber-optic Fabry-Perot interferometer (FPI) has been proposed and demonstrated for the ultrasound wave (UW) imaging of seismic-physical models. The sensor probe comprises a single mode fiber (SMF) that is inserted into a ceramic tube terminated by an ultra-thin gold film. The probe performs with an excellent UW sensitivity thanks to the nanolayer gold film, and thus is capable of detecting a weak UW in air medium. Furthermore, the compact sensor is a symmetrical structure so that it presents a good directionality in the UW detection. The spectral band-side filter technique is used for UW interrogation. After scanning the models using the sensing probe in air, the two-dimensional (2D) images of four physical models are reconstructed. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

14 pages, 5461 KiB

Open AccessArticle

Formation and Applications of the Secondary Fiber Bragg Grating

by Bai-Ou Guan^*, Yang Ran

, Fu-Rong Feng

and Long Jin

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

Sensors 2017, 17(2), 398; https://doi.org/10.3390/s17020398 - 18 Feb 2017

Cited by 14 | Viewed by 6516

Abstract

Being one of the most proven fiber optic devices, the fiber Bragg grating has developed continually to extend its applications, particularly in extreme environments. Accompanying the growth of Type-IIa Bragg gratings in some active fibers, a new resonance appears at the shorter wavelength. [...] Read more.

Being one of the most proven fiber optic devices, the fiber Bragg grating has developed continually to extend its applications, particularly in extreme environments. Accompanying the growth of Type-IIa Bragg gratings in some active fibers, a new resonance appears at the shorter wavelength. This new type of grating was named “secondary Bragg grating” (SBG). This paper describes the formation and applications of the SBGs. The formation of the SBG is attributed to the intracore Talbot-type-fringes as a result of multi-order diffractions of the inscribing beams. The SBG presents a variety of interesting characteristics, including dip merge, high-temperature resistance, distinct temperature response, and the strong higher-order harmonic reflection. These features enable its promising applications in fiber lasers and fiber sensing technology. Full article

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

▼ Show Figures

Figure 1

12 pages, 362 KiB

Open AccessArticle

Non-Dispersive Infrared Sensor for Online Condition Monitoring of Gearbox Oil

by Markus S. Rauscher^*, Anton J. Tremmel, Michael Schardt and Alexander W. Koch

Institute for Measurement Systems and Sensor Technology, Technical University of Munich, 80333 Munich, Germany

Sensors 2017, 17(2), 399; https://doi.org/10.3390/s17020399 - 18 Feb 2017

Cited by 28 | Viewed by 8713

Abstract

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of [...] Read more.

The condition of lubricating oil used in automotive and industrial gearboxes must be controlled in order to guarantee optimum performance and prevent damage to machinery parts. In normal practice, this is done by regular oil change intervals and routine laboratory analysis, both of which involve considerable operating costs. In this paper, we present a compact and robust optical sensor that can be installed in the lubrication circuit to provide quasi-continuous information about the condition of the oil. The measuring principle is based on non-dispersive infrared spectroscopy. The implemented sensor setup consists of an optical measurement cell, two thin-film infrared emitters, and two four-channel pyroelectric detectors equipped with optical bandpass filters. We present a method based on multivariate partial least squares regression to select appropriate optical bandpass filters for monitoring the oxidation, water content, and acid number of the oil. We perform a ray tracing analysis to analyze and correct the influence of the light path in the optical setup on the optical parameters of the bandpass filters. The measurement values acquired with the sensor for three different gearbox oil types show high correlation with laboratory reference data for the oxidation, water content, and acid number. The presented sensor can thus be a useful supplementary tool for the online condition monitoring of lubricants when integrated into a gearbox oil circuit. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

12 pages, 3483 KiB

Open AccessArticle

Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts

by Markus Feulner, Gunter Hagen, Kathrin Hottner, Sabrina Redel, Andreas Müller and Ralf Moos^*

Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95447 Bayreuth, Germany

Sensors 2017, 17(2), 400; https://doi.org/10.3390/s17020400 - 18 Feb 2017

Cited by 19 | Viewed by 9904

Abstract

Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies [...] Read more.

Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF). The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor. Full article

(This article belongs to the Collection Gas Sensors)

▼ Show Figures

Figure 1

16 pages, 5114 KiB

Open AccessArticle

Gimbal Influence on the Stability of Exterior Orientation Parameters of UAV Acquired Images

by Mateo Gašparović^*

and Luka Jurjević

Chair of Photogrammetry and Remote Sensing, Faculty of Geodesy, University of Zagreb, Zagreb 10000, Croatia

Sensors 2017, 17(2), 401; https://doi.org/10.3390/s17020401 - 18 Feb 2017

Cited by 43 | Viewed by 13213

Abstract

In this paper, results from the analysis of the gimbal impact on the determination of the camera exterior orientation parameters of an Unmanned Aerial Vehicle (UAV) are presented and interpreted. Additionally, a new approach and methodology for testing the influence of gimbals on [...] Read more.

In this paper, results from the analysis of the gimbal impact on the determination of the camera exterior orientation parameters of an Unmanned Aerial Vehicle (UAV) are presented and interpreted. Additionally, a new approach and methodology for testing the influence of gimbals on the exterior orientation parameters of UAV acquired images is presented. The main motive of this study is to examine the possibility of obtaining better geometry and favorable spatial bundles of rays of images in UAV photogrammetric surveying. The subject is a 3-axis brushless gimbal based on a controller board (Storm32). Only two gimbal axes are taken into consideration: roll and pitch axes. Testing was done in a flight simulation, and in indoor and outdoor flight mode, to analyze the Inertial Measurement Unit (IMU) and photogrammetric data. Within these tests the change of the exterior orientation parameters without the use of a gimbal is determined, as well as the potential accuracy of the stabilization with the use of a gimbal. The results show that using a gimbal has huge potential. Significantly, smaller discrepancies between data are noticed when a gimbal is used in flight simulation mode, even four times smaller than in other test modes. In this test the potential accuracy of a low budget gimbal for application in real conditions is determined. Full article

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

▼ Show Figures

Figure 1

24 pages, 7251 KiB

Open AccessArticle

Towards a Semantic Web of Things: A Hybrid Semantic Annotation, Extraction, and Reasoning Framework for Cyber-Physical System

by Zhenyu Wu^1,*, Yuan Xu², Yunong Yang², Chunhong Zhang², Xinning Zhu² and Yang Ji^1,2

¹ Information Network Engineering Research Center of Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876, China

² State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876, China

Sensors 2017, 17(2), 403; https://doi.org/10.3390/s17020403 - 20 Feb 2017

Cited by 41 | Viewed by 9553

Abstract

Web of Things (WoT) facilitates the discovery and interoperability of Internet of Things (IoT) devices in a cyber-physical system (CPS). Moreover, a uniform knowledge representation of physical resources is quite necessary for further composition, collaboration, and decision-making process in CPS. Though several efforts [...] Read more.

Web of Things (WoT) facilitates the discovery and interoperability of Internet of Things (IoT) devices in a cyber-physical system (CPS). Moreover, a uniform knowledge representation of physical resources is quite necessary for further composition, collaboration, and decision-making process in CPS. Though several efforts have integrated semantics with WoT, such as knowledge engineering methods based on semantic sensor networks (SSN), it still could not represent the complex relationships between devices when dynamic composition and collaboration occur, and it totally depends on manual construction of a knowledge base with low scalability. In this paper, to addresses these limitations, we propose the semantic Web of Things (SWoT) framework for CPS (SWoT4CPS). SWoT4CPS provides a hybrid solution with both ontological engineering methods by extending SSN and machine learning methods based on an entity linking (EL) model. To testify to the feasibility and performance, we demonstrate the framework by implementing a temperature anomaly diagnosis and automatic control use case in a building automation system. Evaluation results on the EL method show that linking domain knowledge to DBpedia has a relative high accuracy and the time complexity is at a tolerant level. Advantages and disadvantages of SWoT4CPS with future work are also discussed. Full article

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

▼ Show Figures

Figure 1

12 pages, 13945 KiB

Open AccessArticle

Remote Sensing of Urban Microclimate Change in L’Aquila City (Italy) after Post-Earthquake Depopulation in an Open Source GIS Environment

by Valerio Baiocchi^1,*

, Fabio Zottele²

and Donatella Dominici³

¹ Department of Civil, Constructional and Environmental Engineeering (DICEA), Sapienza University of Rome, I-00184 Rome, Italy

² Fondazione Mach, Centre for Technology Transfer, I-38010 S. Michele all’Adige (TN), Italy

³ Department of Civil, Construction-Architectural and Environmental Engineering (DICEAA), University of L’Aquila, I-67100 L’Aquila, Italy

Sensors 2017, 17(2), 404; https://doi.org/10.3390/s17020404 - 19 Feb 2017

Cited by 17 | Viewed by 6463

Abstract

This work reports a first attempt to use Landsat satellite imagery to identify possible urban microclimate changes in a city center after a seismic event that affected L’Aquila City (Abruzzo Region, Italy), on 6 April 2009. After the main seismic event, the collapse [...] Read more.

This work reports a first attempt to use Landsat satellite imagery to identify possible urban microclimate changes in a city center after a seismic event that affected L’Aquila City (Abruzzo Region, Italy), on 6 April 2009. After the main seismic event, the collapse of part of the buildings, and the damaging of most of them, with the consequence of an almost total depopulation of the historic city center, may have caused alterations to the microclimate. This work develops an inexpensive work flow—using Landsat Enhanced Thematic Mapper Plus (ETM+) scenes—to construct the evolution of urban land use after the catastrophic main seismic event that hit L’Aquila. We hypothesized, that, possibly, before the event, the temperature was higher in the city center due to the presence of inhabitants (and thus home heating); while the opposite case occurred in the surrounding areas, where new settlements of inhabitants grew over a period of a few months. We decided not to look to independent meteorological data in order to avoid being biased in their investigations; thus, only the smallest dataset of Landsat ETM+ scenes were considered as input data in order to describe the thermal evolution of the land surface after the earthquake. We managed to use the Landsat archive images to provide thermal change indications, useful for understanding the urban changes induced by catastrophic events, setting up an easy to implement, robust, reproducible, and fast procedure. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

▼ Show Figures

Figure 1

10 pages, 3238 KiB

Open AccessArticle

A Biocompatible Colorimetric Triphenylamine- Dicyanovinyl Conjugated Fluorescent Probe for Selective and Sensitive Detection of Cyanide Ion in Aqueous Media and Living Cells

by Zi-Hua Zheng^1,2, Zhi-Ke Li³, Lin-Jiang Song³, Qi-Wei Wang¹, Qing-Fei Huang^1,* and Li Yang^3,*

¹ Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China

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

³ Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610041, China

Sensors 2017, 17(2), 405; https://doi.org/10.3390/s17020405 - 19 Feb 2017

Cited by 13 | Viewed by 8800

Abstract

A colorimetric and turn-on fluorescent probe 1 bearing triphenylamine-thiophene and dicyanovinyl groups has been synthesized and used to detect cyanide anion via a nucleophilic addition reaction. Probe 1 exhibited prominent selectivity and sensitivity towards CN⁻ in aqueous media, even in the presence [...] Read more.

A colorimetric and turn-on fluorescent probe 1 bearing triphenylamine-thiophene and dicyanovinyl groups has been synthesized and used to detect cyanide anion via a nucleophilic addition reaction. Probe 1 exhibited prominent selectivity and sensitivity towards CN⁻ in aqueous media, even in the presence of other anions such as S²⁻, HS⁻, SO₃²⁻, S₂O₃²⁻, S₂O₈²⁻, I⁻, Br⁻, Cl⁻, F⁻, NO₂⁻, N₃⁻, SO₄²⁻, SCN⁻, HCO₃⁻, CO₃²⁻ and AcO⁻. Moreover, a low detection limit (LOD, 51 nM) was observed. In addition, good cell membrane permeability and low cytotoxicity to HeLa cells were also observed, suggesting its promising potential in bio-imaging. Full article

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

▼ Show Figures

Graphical abstract

12 pages, 4400 KiB

Open AccessArticle

An Optical Fibre Depth (Pressure) Sensor for Remote Operated Vehicles in Underwater Applications

by Dinesh Babu Duraibabu^1,*

, Sven Poeggel¹

, Edin Omerdic²

, Romano Capocci², Elfed Lewis^1,*

, Thomas Newe^1,2

, Gabriel Leen¹

, Daniel Toal²

and Gerard Dooly²

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

² Mobile & Marine Robotics Research Centre, University of Limerick, Limerick V94 T9PX, Ireland

Sensors 2017, 17(2), 406; https://doi.org/10.3390/s17020406 - 19 Feb 2017

Cited by 39 | Viewed by 8864

Abstract

A miniature sensor for accurate measurement of pressure (depth) with temperature compensation in the ocean environment is described. The sensor is based on an optical fibre Extrinsic Fabry-Perot interferometer (EFPI) combined with a Fibre Bragg Grating (FBG). The EFPI provides pressure measurements while [...] Read more.

A miniature sensor for accurate measurement of pressure (depth) with temperature compensation in the ocean environment is described. The sensor is based on an optical fibre Extrinsic Fabry-Perot interferometer (EFPI) combined with a Fibre Bragg Grating (FBG). The EFPI provides pressure measurements while the Fibre Bragg Grating (FBG) provides temperature measurements. The sensor is mechanically robust, corrosion-resistant and suitable for use in underwater applications. The combined pressure and temperature sensor system was mounted on-board a mini remotely operated underwater vehicle (ROV) in order to monitor the pressure changes at various depths. The reflected optical spectrum from the sensor was monitored online and a pressure or temperature change caused a corresponding observable shift in the received optical spectrum. The sensor exhibited excellent stability when measured over a 2 h period underwater and its performance is compared with a commercially available reference sensor also mounted on the ROV. The measurements illustrates that the EFPI/FBG sensor is more accurate for depth measurements (depth of ~0.020 m). Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

7 pages, 1556 KiB

Open AccessArticle

Compliment Graphene Oxide Coating on Silk Fiber Surface via Electrostatic Force for Capacitive Humidity Sensor Applications

by Kook In Han¹, Seungdu Kim¹, In Gyu Lee¹, Jong Pil Kim², Jung-Ha Kim², Suck Won Hong³

, Byung Jin Cho⁴ and Wan Sik Hwang^1,*

¹ Department of Materials Engineering, Korea Aerospace University, Goyang 10540, Korea

² Division of High Technology Materials Research & Molecular Materials Research Team, Korea Basic Science Institute, Busan 168-230, Korea

³ Department of Cogno-Mechatronics Engineering, Department of Optics and Mechatronics Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan 46241, Korea

⁴ Department of Electrical Engineering, KAIST, Daejeon 34141, Korea

Sensors 2017, 17(2), 407; https://doi.org/10.3390/s17020407 - 19 Feb 2017

Cited by 26 | Viewed by 8652

Abstract

Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively [...] Read more.

Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively charged SF surface was controlled through the static electricity charges created on the SF surface. The GO coating ability on the SF improved as the SF’s positive charge increased. The GO-coated SFs at various conditions were characterized using an optical microscope, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and LCR meter. Unlike the intact SF, the GO-coated SF showed clear response-recovery behavior and well-behaved repeatability when it was exposed to 20% relative humidity (RH) and 90% RH alternatively in a capacitive mode. This approach allows humidity sensors to take advantage of GO’s excellent sensing properties and SF’s flexibility, expediting the production of flexible, low power consumption devices at relatively low costs. Full article

(This article belongs to the Special Issue Humidity Sensors)

▼ Show Figures

Figure 1

19 pages, 7613 KiB

Open AccessArticle

Formal Uncertainty and Dispersion of Single and Double Difference Models for GNSS-Based Attitude Determination

by Wen Chen^1,2,3

, Chao Yu^1,2,3,*, Danan Dong^1,2,3, Miaomiao Cai¹, Feng Zhou¹, Zhiren Wang¹, Lei Zhang^1,2,3 and Zhengqi Zheng^1,3

¹ Engineering Center of SHMEC for Space Information and GNSS, East China Normal University, Shanghai 200241, China

² Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, China

³ Shanghai Key Laboratory of Multidimensional Information Processing, East China Normal University, Shanghai 200241, China

Sensors 2017, 17(2), 408; https://doi.org/10.3390/s17020408 - 20 Feb 2017

Cited by 19 | Viewed by 5708

Abstract

With multi-antenna synchronized global navigation satellite system (GNSS) receivers, the single difference (SD) between two antennas is able to eliminate both satellite and receiver clock error, thus it becomes necessary to reconsider the equivalency problem between the SD and double difference (DD) models. [...] Read more.

With multi-antenna synchronized global navigation satellite system (GNSS) receivers, the single difference (SD) between two antennas is able to eliminate both satellite and receiver clock error, thus it becomes necessary to reconsider the equivalency problem between the SD and double difference (DD) models. In this paper, we quantitatively compared the formal uncertainties and dispersions between multiple SD models and the DD model, and also carried out static and kinematic short baseline experiments. The theoretical and experimental results show that under a non-common clock scheme the SD and DD model are equivalent. Under a common clock scheme, if we estimate stochastic uncalibrated phase delay (UPD) parameters every epoch, this SD model is still equivalent to the DD model, but if we estimate only one UPD parameter for all epochs or take it as a known constant, the SD (here called SD2) and DD models are no longer equivalent. For the vertical component of baseline solutions, the formal uncertainties of the SD2 model are two times smaller than those of the DD model, and the dispersions of the SD2 model are even more than twice smaller than those of the DD model. In addition, to obtain baseline solutions, the SD2 model requires a minimum of three satellites, while the DD model requires a minimum of four satellites, which makes the SD2 more advantageous in attitude determination under sheltered environments. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

13 pages, 3048 KiB

Open AccessArticle

Quasi-Static Calibration Method of a High-g Accelerometer

by Yan Wang^1,2,*, Jinbiao Fan², Jing Zu¹ and Peng Xu¹

¹ Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China

² School of Computer Science and Control Engineering, North University of China, Taiyuan 030051, China

Sensors 2017, 17(2), 409; https://doi.org/10.3390/s17020409 - 20 Feb 2017

Cited by 17 | Viewed by 5708

Abstract

To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static [...] Read more.

To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static calibration theory. We establish a quasi-static calibration testing system, which uses a gas gun to generate high-g acceleration signals, and apply a laser interferometer to reproduce the impact acceleration. These signals are used to drive the calibrated accelerometer. By comparing the excitation acceleration signal and the output responses of the calibrated accelerometer to the excitation signals, the impact sensitivity of the calibrated accelerometer is obtained. As indicated by the calibration test results, this calibration system produces excitation acceleration signals with a pulse width of less than 1000 μs, and realize the quasi-static calibration of high-g accelerometers with a resonant frequency above 20 kHz when the calibration error was 3%. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 3874 KiB

Open AccessArticle

Toward Improving Electrocardiogram (ECG) Biometric Verification using Mobile Sensors: A Two-Stage Classifier Approach

by Robin Tan

and Marek Perkowski^*

Department of Electrical and Computer Engineering, Portland State University, Portland, OR 97201, USA

Sensors 2017, 17(2), 410; https://doi.org/10.3390/s17020410 - 20 Feb 2017

Cited by 71 | Viewed by 7446

Abstract

Electrocardiogram (ECG) signals sensed from mobile devices pertain the potential for biometric identity recognition applicable in remote access control systems where enhanced data security is demanding. In this study, we propose a new algorithm that consists of a two-stage classifier combining random forest [...] Read more.

Electrocardiogram (ECG) signals sensed from mobile devices pertain the potential for biometric identity recognition applicable in remote access control systems where enhanced data security is demanding. In this study, we propose a new algorithm that consists of a two-stage classifier combining random forest and wavelet distance measure through a probabilistic threshold schema, to improve the effectiveness and robustness of a biometric recognition system using ECG data acquired from a biosensor integrated into mobile devices. The proposed algorithm is evaluated using a mixed dataset from 184 subjects under different health conditions. The proposed two-stage classifier achieves a total of 99.52% subject verification accuracy, better than the 98.33% accuracy from random forest alone and 96.31% accuracy from wavelet distance measure algorithm alone. These results demonstrate the superiority of the proposed algorithm for biometric identification, hence supporting its practicality in areas such as cloud data security, cyber-security or remote healthcare systems. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

20 pages, 8857 KiB

Open AccessArticle

Dynamic Method of Neutral Axis Position Determination and Damage Identification with Distributed Long-Gauge FBG Sensors

by Yongsheng Tang^1,*

and Zhongdao Ren²

¹ School of Urban Rail Transportation, Soochow University, Suzhou 215137, China

² Department of Civil Engineering, Yanshan University, Qinhuangdao 066004, China

Sensors 2017, 17(2), 411; https://doi.org/10.3390/s17020411 - 20 Feb 2017

Cited by 19 | Viewed by 6619

Abstract

The neutral axis position (NAP) is a key parameter of a flexural member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In [...] Read more.

The neutral axis position (NAP) is a key parameter of a flexural member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS). In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG) sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC) is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC) beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of flexural structures can be facilitated. Full article

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

▼ Show Figures

Figure 1

15 pages, 5945 KiB

Open AccessArticle

An Improved Azimuth Angle Estimation Method with a Single Acoustic Vector Sensor Based on an Active Sonar Detection System

by Anbang Zhao^1,2, Lin Ma^1,2, Xuefei Ma^1,2,*

and Juan Hui^1,2

¹ College of Underwater Acoustic Engineering, Harbin 150001, China

² Science and Technology Underwater Acoustic Laboratory, Harbin 150001, China

Sensors 2017, 17(2), 412; https://doi.org/10.3390/s17020412 - 20 Feb 2017

Cited by 27 | Viewed by 7216

Abstract

In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on [...] Read more.

In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on complex acoustic intensity measurement, the mathematical and physical model of this proposed method is described in detail. The computer simulation and lake experiments results indicate that this method can realize the azimuth angle estimation with high precision by using only a single AVS. Compared with the conventional method, the proposed method achieves better estimation performance. Moreover, the proposed method does not require complex operations in frequencydomain and achieves computational complexity reduction. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

21 pages, 7199 KiB

Open AccessArticle

Analyzing the Effects of UAV Mobility Patterns on Data Collection in Wireless Sensor Networks

by Sarmad Rashed and Mujdat Soyturk^*

Department of Computer Engineering, Faculty of Engineering, Marmara University, 34722 Istanbul, Turkey

Sensors 2017, 17(2), 413; https://doi.org/10.3390/s17020413 - 20 Feb 2017

Cited by 46 | Viewed by 7151

Abstract

Sensor nodes in a Wireless Sensor Network (WSN) can be dispersed over a remote sensing area (e.g., the regions that are hardly accessed by human beings). In such kinds of networks, datacollectionbecomesoneofthemajorissues. Getting connected to each sensor node and retrieving the information in [...] Read more.

Sensor nodes in a Wireless Sensor Network (WSN) can be dispersed over a remote sensing area (e.g., the regions that are hardly accessed by human beings). In such kinds of networks, datacollectionbecomesoneofthemajorissues. Getting connected to each sensor node and retrieving the information in time introduces new challenges. Mobile sink usage—especially Unmanned Aerial Vehicles (UAVs)—is the most convenient approach to covering the area and accessing each sensor node in such a large-scale WSN. However, the operation of the UAV depends on some parameters, such as endurance time, altitude, speed, radio type in use, and the path. In this paper, we explore various UAV mobility patterns that follow different paths to sweep the operation area in order to seek the best area coverage with the maximum number of covered nodes in the least amount of time needed by the mobile sink. We also introduce a new metric to formulate the tradeoff between maximizing the covered nodes and minimizing the operation time when choosing the appropriate mobility pattern. A realistic simulation environment is used in order to compare and evaluate the performance of the system. We present the performance results for the explored UAV mobility patterns. The results are very useful to present the tradeoff between maximizing the covered nodes and minimizing the operation time to choose the appropriate mobility pattern. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

15 pages, 3709 KiB

Open AccessArticle

An Adaptive Multi-Sensor Data Fusion Method Based on Deep Convolutional Neural Networks for Fault Diagnosis of Planetary Gearbox

by Luyang Jing¹, Taiyong Wang^1,*, Ming Zhao²

and Peng Wang¹

¹ School of Mechanical Engineering, Tianjin University, Tianjin 300354, China

² School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(2), 414; https://doi.org/10.3390/s17020414 - 21 Feb 2017

Cited by 372 | Viewed by 21043

Abstract

A fault diagnosis approach based on multi-sensor data fusion is a promising tool to deal with complicated damage detection problems of mechanical systems. Nevertheless, this approach suffers from two challenges, which are (1) the feature extraction from various types of sensory data and [...] Read more.

A fault diagnosis approach based on multi-sensor data fusion is a promising tool to deal with complicated damage detection problems of mechanical systems. Nevertheless, this approach suffers from two challenges, which are (1) the feature extraction from various types of sensory data and (2) the selection of a suitable fusion level. It is usually difficult to choose an optimal feature or fusion level for a specific fault diagnosis task, and extensive domain expertise and human labor are also highly required during these selections. To address these two challenges, we propose an adaptive multi-sensor data fusion method based on deep convolutional neural networks (DCNN) for fault diagnosis. The proposed method can learn features from raw data and optimize a combination of different fusion levels adaptively to satisfy the requirements of any fault diagnosis task. The proposed method is tested through a planetary gearbox test rig. Handcraft features, manual-selected fusion levels, single sensory data, and two traditional intelligent models, back-propagation neural networks (BPNN) and a support vector machine (SVM), are used as comparisons in the experiment. The results demonstrate that the proposed method is able to detect the conditions of the planetary gearbox effectively with the best diagnosis accuracy among all comparative methods in the experiment. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

20 pages, 5264 KiB

Open AccessTechnical Note

Inertial Navigation System/Doppler Velocity Log (INS/DVL) Fusion with Partial DVL Measurements

by Asaf Tal^1,2,*, Itzik Klein² and Reuven Katz¹

¹ Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel

² Rafael Advanced Defense Systems Ltd, Haifa 3102102, Israel

Sensors 2017, 17(2), 415; https://doi.org/10.3390/s17020415 - 22 Feb 2017

Cited by 144 | Viewed by 15155

Abstract

The Technion autonomous underwater vehicle (TAUV) is an ongoing project aiming to develop and produce a small AUV to carry on research missions, including payload dropping, and to demonstrate acoustic communication. Its navigation system is based on an inertial navigation system (INS) aided [...] Read more.

The Technion autonomous underwater vehicle (TAUV) is an ongoing project aiming to develop and produce a small AUV to carry on research missions, including payload dropping, and to demonstrate acoustic communication. Its navigation system is based on an inertial navigation system (INS) aided by a Doppler velocity log (DVL), magnetometer, and pressure sensor (PS). In many INSs, such as the one used in TAUV, only the velocity vector (provided by the DVL) can be used for aiding the INS, i.e., enabling only a loosely coupled integration approach. In cases of partial DVL measurements, such as failure to maintain bottom lock, the DVL cannot estimate the vehicle velocity. Thus, in partial DVL situations no velocity data can be integrated into the TAUV INS, and as a result its navigation solution will drift in time. To circumvent that problem, we propose a DVL-based vehicle velocity solution using the measured partial raw data of the DVL and additional information, thereby deriving an extended loosely coupled (ELC) approach. The implementation of the ELC approach requires only software modification. In addition, we present the TAUV six degrees of freedom (6DOF) simulation that includes all functional subsystems. Using this simulation, the proposed approach is evaluated and the benefit of using it is shown. Full article

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

▼ Show Figures

Figure 1

20 pages, 20441 KiB

Open AccessArticle

Dynamic Fluid in a Porous Transducer-Based Angular Accelerometer

by Siyuan Cheng¹

, Mengyin Fu^1,2, Meiling Wang^1,*, Li Ming¹, Huijin Fu¹ and Tonglei Wang^1,3

¹ School of Automation, Beijing Institute of Technology, Beijing 100081, China

² School of Automation, Nanjing University of Science and Technology, Nanjing 210094, China

³ Beijing Automation Control Equipment Institute, Beijing 100074, China

Sensors 2017, 17(2), 416; https://doi.org/10.3390/s17020416 - 21 Feb 2017

Cited by 17 | Viewed by 5749

Abstract

This paper presents a theoretical model of the dynamics of liquid flow in an angular accelerometer comprising a porous transducer in a circular tube of liquid. Wave speed and dynamic permeability of the transducer are considered to describe the relation between angular acceleration [...] Read more.

This paper presents a theoretical model of the dynamics of liquid flow in an angular accelerometer comprising a porous transducer in a circular tube of liquid. Wave speed and dynamic permeability of the transducer are considered to describe the relation between angular acceleration and the differential pressure on the transducer. The permeability and streaming potential coupling coefficient of the transducer are determined in the experiments, and special prototypes are utilized to validate the theoretical model in both the frequency and time domains. The model is applied to analyze the influence of structural parameters on the frequency response and the transient response of the fluidic system. It is shown that the radius of the circular tube and the wave speed affect the low frequency gain, as well as the bandwidth of the sensor. The hydrodynamic resistance of the transducer and the cross-section radius of the circular tube can be used to control the transient performance. The proposed model provides the basic techniques to achieve the optimization of the angular accelerometer together with the methodology to control the wave speed and the hydrodynamic resistance of the transducer. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

26 pages, 4784 KiB

Open AccessArticle

A Sensor Data Fusion System Based on k-Nearest Neighbor Pattern Classification for Structural Health Monitoring Applications

by Jaime Vitola^1,4,†, Francesc Pozo^1,*,†

, Diego A. Tibaduiza^2,†

and Maribel Anaya^3,†

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

² Departamento de Ingeniería Eléctrica y Electrónica, Universidad Nacional de Colombia, Cra 45 No. 26-85, Bogotá 111321, Colombia

³ Faculty of Engineering, Fundación Universitaria Los Libertadores, Cra 16 No. 63A-68, Bogotá 111221, Colombia

⁴ MEM (Materials-Electronics and Modelling Research Group), Faculty of Electronics Engineering, Universidad Santo Tomás, Cra 9 No. 51-11, Bogotá 110231, Colombia

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 417; https://doi.org/10.3390/s17020417 - 21 Feb 2017

Cited by 138 | Viewed by 11978

Abstract

Civil and military structures are susceptible and vulnerable to damage due to the environmental and operational conditions. Therefore, the implementation of technology to provide robust solutions in damage identification (by using signals acquired directly from the structure) is a requirement to reduce operational [...] Read more.

Civil and military structures are susceptible and vulnerable to damage due to the environmental and operational conditions. Therefore, the implementation of technology to provide robust solutions in damage identification (by using signals acquired directly from the structure) is a requirement to reduce operational and maintenance costs. In this sense, the use of sensors permanently attached to the structures has demonstrated a great versatility and benefit since the inspection system can be automated. This automation is carried out with signal processing tasks with the aim of a pattern recognition analysis. This work presents the detailed description of a structural health monitoring (SHM) system based on the use of a piezoelectric (PZT) active system. The SHM system includes: (i) the use of a piezoelectric sensor network to excite the structure and collect the measured dynamic response, in several actuation phases; (ii) data organization; (iii) advanced signal processing techniques to define the feature vectors; and finally; (iv) the nearest neighbor algorithm as a machine learning approach to classify different kinds of damage. A description of the experimental setup, the experimental validation and a discussion of the results from two different structures are included and analyzed. Full article

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

▼ Show Figures

Figure 1

14 pages, 4357 KiB

Open AccessArticle

Data Collection and Analysis Using Wearable Sensors for Monitoring Knee Range of Motion after Total Knee Arthroplasty

by Chih-Yen Chiang¹

, Kun-Hui Chen^1,2, Kai-Chun Liu¹

, Steen Jun-Ping Hsu³

and Chia-Tai Chan^1,*

¹ Department of Biomedical Engineering, National Yang-Ming University, No. 155, Li-Nong St., Section 2, Peitou, Taipei 11221, Taiwan

² Department of Orthopaedic Surgery, Taichung Veterans General Hospital, 1650 Taiwan Boulevard Section 4, Taichung 40705, Taiwan

³ Department of Information Management, Minghsin University of Science and Technology, No.1, Xinxing Road, Hsinchu 30401, Taiwan

Sensors 2017, 17(2), 418; https://doi.org/10.3390/s17020418 - 22 Feb 2017

Cited by 79 | Viewed by 9872

Abstract

Total knee arthroplasty (TKA) is the most common treatment for degenerative osteoarthritis of that articulation. However, either in rehabilitation clinics or in hospital wards, the knee range of motion (ROM) can currently only be assessed using a goniometer. In order to provide continuous [...] Read more.

Total knee arthroplasty (TKA) is the most common treatment for degenerative osteoarthritis of that articulation. However, either in rehabilitation clinics or in hospital wards, the knee range of motion (ROM) can currently only be assessed using a goniometer. In order to provide continuous and objective measurements of knee ROM, we propose the use of wearable inertial sensors to record the knee ROM during the recovery progress. Digitalized and objective data can assist the surgeons to control the recovery status and flexibly adjust rehabilitation programs during the early acute inpatient stage. The more knee flexion ROM regained during the early inpatient period, the better the long-term knee recovery will be and the sooner early discharge can be achieved. The results of this work show that the proposed wearable sensor approach can provide an alternative for continuous monitoring and objective assessment of knee ROM recovery progress for TKA patients compared to the traditional goniometer measurements. Full article

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

▼ Show Figures

Figure 1

15 pages, 4284 KiB

Open AccessArticle

Long Term Amperometric Recordings in the Brain Extracellular Fluid of Freely Moving Immunocompromised NOD SCID Mice

by Caroline H. Reid and Niall J. Finnerty^*

Chemistry Department, Maynooth University, Maynooth, County Kildare W23 F2H6, Ireland

Sensors 2017, 17(2), 419; https://doi.org/10.3390/s17020419 - 22 Feb 2017

Cited by 9 | Viewed by 4876

Abstract

We describe the in vivo characterization of microamperometric sensors for the real-time monitoring of nitric oxide (NO) and oxygen (O₂) in the striatum of immunocompromised NOD SCID mice. The latter strain has been utilized routinely in the establishment of humanized models [...] Read more.

We describe the in vivo characterization of microamperometric sensors for the real-time monitoring of nitric oxide (NO) and oxygen (O₂) in the striatum of immunocompromised NOD SCID mice. The latter strain has been utilized routinely in the establishment of humanized models of disease e.g., Parkinson’s disease. NOD SCID mice were implanted with highly sensitive and selective NO and O₂ sensors that have been previously characterized both in vitro and in freely moving rats. Animals were systemically administered compounds that perturbed the amperometric current and confirmed sensor performance. Furthermore, the stability of the amperometric current was investigated and 24 h recordings examined. Saline injections caused transient changes in both currents that were not significant from baseline. l-NAME caused significant decreases in NO (p < 0.05) and O₂ (p < 0.001) currents compared to saline. l-Arginine produced a significant increase (p < 0.001) in NO current, and chloral hydrate and Diamox (acetazolamide) caused significant increases in O₂ signal (p < 0.01) compared against saline. The stability of both currents were confirmed over an eight-day period and analysis of 24-h recordings identified diurnal variations in both signals. These findings confirm the efficacy of the amperometric sensors to perform continuous and reliable recordings in immunocompromised mice. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

16 pages, 10194 KiB

Open AccessArticle

A Soft Sensor-Based Three-Dimensional (3-D) Finger Motion Measurement System

by Wookeun Park

, Kyongkwan Ro, Suin Kim and Joonbum Bae^*

Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea

Sensors 2017, 17(2), 420; https://doi.org/10.3390/s17020420 - 22 Feb 2017

Cited by 68 | Viewed by 18077

Abstract

In this study, a soft sensor-based three-dimensional (3-D) finger motion measurement system is proposed. The sensors, made of the soft material Ecoflex, comprise embedded microchannels filled with a conductive liquid metal (EGaln). The superior elasticity, light weight, and sensitivity of soft sensors allows [...] Read more.

In this study, a soft sensor-based three-dimensional (3-D) finger motion measurement system is proposed. The sensors, made of the soft material Ecoflex, comprise embedded microchannels filled with a conductive liquid metal (EGaln). The superior elasticity, light weight, and sensitivity of soft sensors allows them to be embedded in environments in which conventional sensors cannot. Complicated finger joints, such as the carpometacarpal (CMC) joint of the thumb are modeled to specify the location of the sensors. Algorithms to decouple the signals from soft sensors are proposed to extract the pure flexion, extension, abduction, and adduction joint angles. The performance of the proposed system and algorithms are verified by comparison with a camera-based motion capture system. Full article

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

▼ Show Figures

Figure 1

17 pages, 2172 KiB

Open AccessArticle

Efficient Data Collection in Widely Distributed Wireless Sensor Networks with Time Window and Precedence Constraints

by Peng Liu, Tingting Fu^*, Jia Xu and Yue Ding

Key Laboratory of Complex Systems Modeling and Simulation, School of Computer Science, Hangzhou Dianzi University, Hangzhou 310018, China

Sensors 2017, 17(2), 421; https://doi.org/10.3390/s17020421 - 22 Feb 2017

Cited by 1 | Viewed by 5077

Abstract

In addition to the traditional densely deployed cases, widely distributed wireless sensor networks (WDWSNs) have begun to emerge. In these networks, sensors are far away from each other and have no network connections. In this paper, a special application of data collection for [...] Read more.

In addition to the traditional densely deployed cases, widely distributed wireless sensor networks (WDWSNs) have begun to emerge. In these networks, sensors are far away from each other and have no network connections. In this paper, a special application of data collection for WDWSNs is considered where each sensor (Unmanned Ground Vehicle, UGV) moves in a hazardous and complex terrain with many obstacles. They have their own work cycles and can be accessed only at a few locations. A mobile sink cruises on the ground to collect data gathered from these UGVs. Considerable delay is inevitable if the UGV and the mobile sink miss the meeting window or wait idly at the meeting spot. The unique challenge here is that, for each cycle of an UGV, there is only a limited time window for it to appear in front of the mobile sink. Therefore, we propose scheduling the path of a single mobile sink, targeted at visiting a maximum number of UGVs in a timely manner with the shortest path, according to the timing constraints bound by the cycles of UGVs. We then propose a bipartite matching based algorithm to reduce the number of mobile sinks. Simulation results show that the proposed algorithm can achieve performance close to the theoretical maximum determined by the duty cycle instance. Full article

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

▼ Show Figures

Figure 1

24 pages, 1751 KiB

Open AccessArticle

A Temperature-Dependent Battery Model for Wireless Sensor Networks

by Leonardo M. Rodrigues^1,*, Carlos Montez¹

, Ricardo Moraes², Paulo Portugal³ and Francisco Vasques³

¹ Department of Automation and Systems, UFSC—Federal University of Santa Catarina, 88040-900 Florianópolis, Brazil

² Department of Computing, UFSC—Federal University of Santa Catarina, 88905-120 Araranguá, Brazil

³ INEGI/INESC-TEC—Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal

Sensors 2017, 17(2), 422; https://doi.org/10.3390/s17020422 - 22 Feb 2017

Cited by 40 | Viewed by 7980

Abstract

Energy consumption is a major issue in Wireless Sensor Networks (WSNs), as nodes are powered by chemical batteries with an upper bounded lifetime. Estimating the lifetime of batteries is a difficult task, as it depends on several factors, such as operating temperatures and [...] Read more.

Energy consumption is a major issue in Wireless Sensor Networks (WSNs), as nodes are powered by chemical batteries with an upper bounded lifetime. Estimating the lifetime of batteries is a difficult task, as it depends on several factors, such as operating temperatures and discharge rates. Analytical battery models can be used for estimating both the battery lifetime and the voltage behavior over time. Still, available models usually do not consider the impact of operating temperatures on the battery behavior. The target of this work is to extend the widely-used Kinetic Battery Model (KiBaM) to include the effect of temperature on the battery behavior. The proposed Temperature-Dependent KiBaM (T-KiBaM) is able to handle operating temperatures, providing better estimates for the battery lifetime and voltage behavior. The performed experimental validation shows that T-KiBaM achieves an average accuracy error smaller than 0.33%, when estimating the lifetime of Ni-MH batteries for different temperature conditions. In addition, T-KiBaM significantly improves the original KiBaM voltage model. The proposed model can be easily adapted to handle other battery technologies, enabling the consideration of different WSN deployments. Full article

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

▼ Show Figures

Figure 1

18 pages, 6744 KiB

Open AccessArticle

Experimental Validation of Depth Cameras for the Parameterization of Functional Balance of Patients in Clinical Tests

by Francisco-Ángel Moreno^1,†, José Antonio Merchán-Baeza^2,†, Manuel González-Sánchez^2,3, Javier González-Jiménez¹

and Antonio I. Cuesta-Vargas^2,4,*

¹ MAPIR-UMA Group, Department Ingeniería de Sistemas y Automática. Universidad de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga 29071, Spain

² Departamento de Fisioterapia, Universidad de Málaga, Grupo Clinimetría FE-14, Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga 29071, Spain

³ Departamento de Ciencias de la Salud, Universidad de Jaén, Jaén 23071, Spain

⁴ School of Clinical Sciences of the Faculty of Health, the Queensland University of Technology, Brisbane QLD 4000, Australia

^† These authors contributed equally to this work.

Sensors 2017, 17(2), 424; https://doi.org/10.3390/s17020424 - 22 Feb 2017

Cited by 13 | Viewed by 6448

Abstract

In clinical practice, patients’ balance can be assessed using standard scales. Two of the most validated clinical tests for measuring balance are the Timed Up and Go (TUG) test and the MultiDirectional Reach Test (MDRT). Nowadays, inertial sensors (IS) are employed for kinematic [...] Read more.

In clinical practice, patients’ balance can be assessed using standard scales. Two of the most validated clinical tests for measuring balance are the Timed Up and Go (TUG) test and the MultiDirectional Reach Test (MDRT). Nowadays, inertial sensors (IS) are employed for kinematic analysis of functional tests in the clinical setting, and have become an alternative to expensive, 3D optical motion capture systems. In daily clinical practice, however, IS-based setups are yet cumbersome and inconvenient to apply. Current depth cameras have the potential for such application, presenting many advantages as, for instance, being portable, low-cost and minimally-invasive. This paper aims at experimentally validating to what extent this technology can substitute IS for the parameterization and kinematic analysis of the TUG and the MDRT tests. Twenty healthy young adults were recruited as participants to perform five different balance tests while kinematic data from their movements were measured by both a depth camera and an inertial sensor placed on their trunk. The reliability of the camera’s measurements is examined through the Interclass Correlation Coefficient (ICC), whilst the Pearson Correlation Coefficient (r) is computed to evaluate the correlation between both sensor’s measurements, revealing excellent reliability and strong correlations in most cases. Full article

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

▼ Show Figures

Figure 1

21 pages, 3723 KiB

Open AccessArticle

A New Deep Learning Model for Fault Diagnosis with Good Anti-Noise and Domain Adaptation Ability on Raw Vibration Signals

by Wei Zhang, Gaoliang Peng^*, Chuanhao Li, Yuanhang Chen and Zhujun Zhang

State Key Laboratory of Robotics and System, Harbin Institute of Technology, No. 92 Xidazhi Street, Harbin 150001, China

Sensors 2017, 17(2), 425; https://doi.org/10.3390/s17020425 - 22 Feb 2017

Cited by 1539 | Viewed by 31916

Abstract

Intelligent fault diagnosis techniques have replaced time-consuming and unreliable human analysis, increasing the efficiency of fault diagnosis. Deep learning models can improve the accuracy of intelligent fault diagnosis with the help of their multilayer nonlinear mapping ability. This paper proposes a novel method [...] Read more.

Intelligent fault diagnosis techniques have replaced time-consuming and unreliable human analysis, increasing the efficiency of fault diagnosis. Deep learning models can improve the accuracy of intelligent fault diagnosis with the help of their multilayer nonlinear mapping ability. This paper proposes a novel method named Deep Convolutional Neural Networks with Wide First-layer Kernels (WDCNN). The proposed method uses raw vibration signals as input (data augmentation is used to generate more inputs), and uses the wide kernels in the first convolutional layer for extracting features and suppressing high frequency noise. Small convolutional kernels in the preceding layers are used for multilayer nonlinear mapping. AdaBN is implemented to improve the domain adaptation ability of the model. The proposed model addresses the problem that currently, the accuracy of CNN applied to fault diagnosis is not very high. WDCNN can not only achieve 100% classification accuracy on normal signals, but also outperform the state-of-the-art DNN model which is based on frequency features under different working load and noisy environment conditions. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

18 pages, 19228 KiB

Open AccessArticle

The Impact of 3D Stacking and Technology Scaling on the Power and Area of Stereo Matching Processors

by Seung-Ho Ok¹, Yong-Hwan Lee², Jae Hoon Shim³, Sung Kyu Lim⁴ and Byungin Moon^3,*

¹ Samsung Electronics, Hwaseong-si, Gyeonggi-do 18448, Korea

² School of Electronic Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea

³ School of Electronics Engineering, Kyungpook National University, Daegu 41566, Korea

⁴ School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

Sensors 2017, 17(2), 426; https://doi.org/10.3390/s17020426 - 22 Feb 2017

Cited by 2 | Viewed by 6183

Abstract

Recently, stereo matching processors have been adopted in real-time embedded systems such as intelligent robots and autonomous vehicles, which require minimal hardware resources and low power consumption. Meanwhile, thanks to the through-silicon via (TSV), three-dimensional (3D) stacking technology has emerged as a practical [...] Read more.

Recently, stereo matching processors have been adopted in real-time embedded systems such as intelligent robots and autonomous vehicles, which require minimal hardware resources and low power consumption. Meanwhile, thanks to the through-silicon via (TSV), three-dimensional (3D) stacking technology has emerged as a practical solution to achieving the desired requirements of a high-performance circuit. In this paper, we present the benefits of 3D stacking and process technology scaling on stereo matching processors. We implemented 2-tier 3D-stacked stereo matching processors with GlobalFoundries 130-nm and Nangate 45-nm process design kits and compare them with their two-dimensional (2D) counterparts to identify comprehensive design benefits. In addition, we examine the findings from various analyses to identify the power benefits of 3D-stacked integrated circuit (IC) and device technology advancements. From experiments, we observe that the proposed 3D-stacked ICs, compared to their 2D IC counterparts, obtain 43% area, 13% power, and 14% wire length reductions. In addition, we present a logic partitioning method suitable for a pipeline-based hardware architecture that minimizes the use of TSVs. Full article

(This article belongs to the Special Issue Advances on Resources Management for Multi-Platform Infrastructures)

▼ Show Figures

Figure 1

13 pages, 2777 KiB

Open AccessArticle

Dual MIMU Pedestrian Navigation by Inequality Constraint Kalman Filtering

by Wei Shi^1,*

, Yang Wang¹ and Yuanxin Wu²

¹ School of Aeronautics and Astronautics, Central South University, Changsha 410083, China

² Shanghai Key Laboratory of Navigation and Location based Services, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Sensors 2017, 17(2), 427; https://doi.org/10.3390/s17020427 - 22 Feb 2017

Cited by 38 | Viewed by 5787

Abstract

The foot-mounted inertial navigation system is an important method of pedestrian navigation as it, in principle, does not rely any external assistance. A real-time range decomposition constraint method is proposed in this paper to combine the information of dual foot-mounted inertial navigation systems. [...] Read more.

The foot-mounted inertial navigation system is an important method of pedestrian navigation as it, in principle, does not rely any external assistance. A real-time range decomposition constraint method is proposed in this paper to combine the information of dual foot-mounted inertial navigation systems. It is well known that low-cost inertial pedestrian navigation aided with both ZUPT (zero velocity update) and the range decomposition constraint performs better than those in their own respective methods. This paper recommends that the separation distance between the position estimates of the two foot-mounted inertial navigation systems be restricted by an ellipsoidal constraint that relates to the maximum step length and the leg height. The performance of the proposed method is studied by utilizing experimental data, and the results indicate that the method can effectively correct the dual navigation systems’ position over the traditional spherical constraint. Full article

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

▼ Show Figures

Figure 1

Journal Menu

Journal Browser

Sensors, Volume 17, Issue 2 (February 2017) – 210 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI