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11 pages, 10770 KiB

Open AccessArticle

Graphene-Ag Hybrids on Laser-Textured Si Surface for SERS Detection

by Chentao Zhang¹

, Kun Lin¹, Yuanqing Huang¹ and Jianhuan Zhang^1,2,3,*

¹ Department of Instrumental and Electrical Engineering, Xiamen University, Xiamen 361005, China

² Xiamen Key Laboratory of Optoelectronic Transducer Technology, Xiamen 361005, China

³ Fujian Key Laboratory of Universities and Colleges for Transducer Technology, Xiamen 361005, China

Sensors 2017, 17(7), 1462; https://doi.org/10.3390/s17071462 - 22 Jun 2017

Cited by 23 | Viewed by 6671

Abstract

Surface-enhanced Raman scattering (SERS) has been extensively investigated as an effective approach for trace species detection. Silver nanostructures are high-sensitivity SERS substrates in common use, but their poor chemical stability impedes practical applications. Herein, a stable and sensitive SERS substrate based on the [...] Read more.

Surface-enhanced Raman scattering (SERS) has been extensively investigated as an effective approach for trace species detection. Silver nanostructures are high-sensitivity SERS substrates in common use, but their poor chemical stability impedes practical applications. Herein, a stable and sensitive SERS substrate based on the hybrid structures of graphene/silver film/laser-textured Si (G/Ag/LTSi) was developed, and a simple, rapid, and low-cost fabrication approach was explored. Abundant nanoparticles were directly created and deposited on the Si surface via laser ablation. These aggregated nanoparticles functioned as hotspots after a 30 nm Ag film coating. A monolayer graphene was transferred to the Ag film surface to prevent the Ag from oxidation. The SERS behavior was investigated by detecting R6G and 4-MBT molecules. The experimental results indicate that the maximum enhancement factor achieved by the G/Ag/LTSi substrate is over 10⁷ and less than 23% SERS signals lost when the substrate was exposed to ambient conditions for 50 days. The covering graphene layer played crucial roles in both the Raman signals enhancement and the Ag nanostructure protection. The stable and sensitive SERS performance of G/Ag/LTSi substrate evince that the present strategy is a useful and convenient route to fabricate large-area graphene-silver plasmonic hybrids for SERS applications. Full article

(This article belongs to the Special Issue Sensors for Biomedical, Environmental and Food Monitoring Applications)

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14 pages, 7777 KiB

Open AccessArticle

Novel Concrete Temperature Monitoring Method Based on an Embedded Passive RFID Sensor Tag

by Yongsheng Liu¹, Fangming Deng^2,3,*, Yigang He³, Bing Li³, Zhen Liang⁴ and Shuangxi Zhou¹

¹ School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China

² School of Electrical and Automation Engineering, East China Jiaotong University, Nanchang 330013, China

³ School of Electrical Engineering and Automation, Hefei University of Technology, Hefei 230009, China

⁴ Rising Micro Electronics Co., Ltd., Guangzhou 510006, China

Sensors 2017, 17(7), 1463; https://doi.org/10.3390/s17071463 - 22 Jun 2017

Cited by 30 | Viewed by 7867

Abstract

This paper firstly introduces the importance of temperature control in concrete measurement, then a passive radio frequency identification (RFID) sensor tag embedded for concrete temperature monitoring is presented. In order to reduce the influences of concrete electromagnetic parameters during the drying process, a [...] Read more.

This paper firstly introduces the importance of temperature control in concrete measurement, then a passive radio frequency identification (RFID) sensor tag embedded for concrete temperature monitoring is presented. In order to reduce the influences of concrete electromagnetic parameters during the drying process, a T-type antenna is proposed to measure the concrete temperature at the required depth. The proposed RFID sensor tag is based on the EPC generation-2 ultra-high frequency (UHF) communication protocol and operates in passive mode. The temperature sensor can convert the sensor signals to corresponding digital signals without an external reference clock due to the adoption of phase-locked loop (PLL)-based architecture. Laboratory experimentation and on-site testing demonstrate that our sensor tag embedded in concrete can provide reliable communication performance in passive mode. The maximum communicating distance between reader and tag is 7 m at the operating frequency of 915 MHz and the tested results show high consistency with the results tested by a thermocouple. Full article

(This article belongs to the Special Issue Low Power Embedded Sensing: Hardware-Software Design and Applications)

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10 pages, 1300 KiB

Open AccessArticle

Paper as Active Layer in Inkjet-Printed Capacitive Humidity Sensors

by Cristina Gaspar^*, Juuso Olkkonen, Soile Passoja and Maria Smolander

Printed Functional Solutions, VTT Technical Research Centre of Finland, Espoo 02044, Finland

Sensors 2017, 17(7), 1464; https://doi.org/10.3390/s17071464 - 22 Jun 2017

Cited by 100 | Viewed by 9038

Abstract

An inkjet-printed relative humidity sensor based on capacitive changes which responds to different humidity levels in the environment is presented in this work. The inkjet-printed silver interdigitated electrodes configuration on the paper substrate allowed for the fabrication of a functional proof-of-concept of the [...] Read more.

An inkjet-printed relative humidity sensor based on capacitive changes which responds to different humidity levels in the environment is presented in this work. The inkjet-printed silver interdigitated electrodes configuration on the paper substrate allowed for the fabrication of a functional proof-of-concept of the relative humidity sensor, by using the paper itself as a sensing material. The sensor sensitivity in terms of relative humidity changes was calculated to be around 2 pF/RH %. The response time against different temperature steps from 3 to 85 °C was fairly constant (about 4–5 min), and it was considered fast for the aimed application, a smart label. Full article

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

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10 pages, 2777 KiB

Open AccessArticle

Automatic Detection and Classification of Pole-Like Objects for Urban Cartography Using Mobile Laser Scanning Data

by Celestino Ordóñez^1,*

, Carlos Cabo¹ and Enoc Sanz-Ablanedo²

¹ Departmento de Explotación de Minas, Grupo de Investigación en Geomática y Computación Gráfica (GEOGRAPH), Universidad de Oviedo, 33004 Oviedo, Spain

² Grupo de Investigación en Geomática e Ingeniería Cartográfica (GEOINCA), Universidad de León, Avenida de Astorga, s/n, 24001 Ponferrada, Spain

Sensors 2017, 17(7), 1465; https://doi.org/10.3390/s17071465 - 22 Jun 2017

Cited by 48 | Viewed by 7064

Abstract

Mobile laser scanning (MLS) is a modern and powerful technology capable of obtaining massive point clouds of objects in a short period of time. Although this technology is nowadays being widely applied in urban cartography and 3D city modelling, it has some drawbacks [...] Read more.

Mobile laser scanning (MLS) is a modern and powerful technology capable of obtaining massive point clouds of objects in a short period of time. Although this technology is nowadays being widely applied in urban cartography and 3D city modelling, it has some drawbacks that need to be avoided in order to strengthen it. One of the most important shortcomings of MLS data is concerned with the fact that it provides an unstructured dataset whose processing is very time-consuming. Consequently, there is a growing interest in developing algorithms for the automatic extraction of useful information from MLS point clouds. This work is focused on establishing a methodology and developing an algorithm to detect pole-like objects and classify them into several categories using MLS datasets. The developed procedure starts with the discretization of the point cloud by means of a voxelization, in order to simplify and reduce the processing time in the segmentation process. In turn, a heuristic segmentation algorithm was developed to detect pole-like objects in the MLS point cloud. Finally, two supervised classification algorithms, linear discriminant analysis and support vector machines, were used to distinguish between the different types of poles in the point cloud. The predictors are the principal component eigenvalues obtained from the Cartesian coordinates of the laser points, the range of the Z coordinate, and some shape-related indexes. The performance of the method was tested in an urban area with 123 poles of different categories. Very encouraging results were obtained, since the accuracy rate was over 90%. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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30 pages, 9970 KiB

Open AccessArticle

A Novel Active Imaging Model to Design Visual Systems: A Case of Inspection System for Specular Surfaces

by Jorge Azorin-Lopez^*

, Andres Fuster-Guillo

, Marcelo Saval-Calvo, Higinio Mora-Mora

and Juan Manuel Garcia-Chamizo

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

Sensors 2017, 17(7), 1466; https://doi.org/10.3390/s17071466 - 22 Jun 2017

Cited by 6 | Viewed by 5484

Abstract

The use of visual information is a very well known input from different kinds of sensors. However, most of the perception problems are individually modeled and tackled. It is necessary to provide a general imaging model that allows us to parametrize different input [...] Read more.

The use of visual information is a very well known input from different kinds of sensors. However, most of the perception problems are individually modeled and tackled. It is necessary to provide a general imaging model that allows us to parametrize different input systems as well as their problems and possible solutions. In this paper, we present an active vision model considering the imaging system as a whole (including camera, lighting system, object to be perceived) in order to propose solutions to automated visual systems that present problems that we perceive. As a concrete case study, we instantiate the model in a real application and still challenging problem: automated visual inspection. It is one of the most used quality control systems to detect defects on manufactured objects. However, it presents problems for specular products. We model these perception problems taking into account environmental conditions and camera parameters that allow a system to properly perceive the specific object characteristics to determine defects on surfaces. The validation of the model has been carried out using simulations providing an efficient way to perform a large set of tests (different environment conditions and camera parameters) as a previous step of experimentation in real manufacturing environments, which more complex in terms of instrumentation and more expensive. Results prove the success of the model application adjusting scale, viewpoint and lighting conditions to detect structural and color defects on specular surfaces. Full article

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

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18 pages, 2680 KiB

Open AccessArticle

A Carrier Estimation Method Based on MLE and KF for Weak GNSS Signals

by Hongyang Zhang¹

, Luping Xu^1,*, Bo Yan¹, Hua Zhang¹ and Liyan Luo²

¹ School of Aerospace Science and Technology, Xidian University, Xi’an 710126, China

² School of Information and Communication, Guilin University of Electronic Technology, Guilin 541004, China

Sensors 2017, 17(7), 1468; https://doi.org/10.3390/s17071468 - 22 Jun 2017

Cited by 11 | Viewed by 5093

Abstract

Maximum likelihood estimation (MLE) has been researched for some acquisition and tracking applications of global navigation satellite system (GNSS) receivers and shows high performance. However, all current methods are derived and operated based on the sampling data, which results in a large computation [...] Read more.

Maximum likelihood estimation (MLE) has been researched for some acquisition and tracking applications of global navigation satellite system (GNSS) receivers and shows high performance. However, all current methods are derived and operated based on the sampling data, which results in a large computation burden. This paper proposes a low-complexity MLE carrier tracking loop for weak GNSS signals which processes the coherent integration results instead of the sampling data. First, the cost function of the MLE of signal parameters such as signal amplitude, carrier phase, and Doppler frequency are used to derive a MLE discriminator function. The optimal value of the cost function is searched by an efficient Levenberg–Marquardt (LM) method iteratively. Its performance including Cramér–Rao bound (CRB), dynamic characteristics and computation burden are analyzed by numerical techniques. Second, an adaptive Kalman filter is designed for the MLE discriminator to obtain smooth estimates of carrier phase and frequency. The performance of the proposed loop, in terms of sensitivity, accuracy and bit error rate, is compared with conventional methods by Monte Carlo (MC) simulations both in pedestrian-level and vehicle-level dynamic circumstances. Finally, an optimal loop which combines the proposed method and conventional method is designed to achieve the optimal performance both in weak and strong signal circumstances. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 3286 KiB

Open AccessArticle

Fourier Transform Infrared Spectroscopy (FT-IR) and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Developmental Cotton Fibers

by Yongliang Liu^1,* and Hee-Jin Kim²

¹ Cotton Structure & Quality Research Unit, United States Department of Agriculture (USDA), Agricultural Research Service (ARS), New Orleans, LA 70124, USA

² Cotton Fiber Bioscience Research Unit, United States Department of Agriculture (USDA), Agricultural Research Service (ARS), New Orleans, LA 70124, USA

Sensors 2017, 17(7), 1469; https://doi.org/10.3390/s17071469 - 22 Jun 2017

Cited by 79 | Viewed by 7393

Abstract

With cotton fiber growth or maturation, cellulose content in cotton fibers markedly increases. Traditional chemical methods have been developed to determine cellulose content, but it is time-consuming and labor-intensive, mostly owing to the slow hydrolysis process of fiber cellulose components. As one approach, [...] Read more.

With cotton fiber growth or maturation, cellulose content in cotton fibers markedly increases. Traditional chemical methods have been developed to determine cellulose content, but it is time-consuming and labor-intensive, mostly owing to the slow hydrolysis process of fiber cellulose components. As one approach, the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy technique has also been utilized to monitor cotton cellulose formation, by implementing various spectral interpretation strategies of both multivariate principal component analysis (PCA) and 1-, 2- or 3-band/-variable intensity or intensity ratios. The main objective of this study was to compare the correlations between cellulose content determined by chemical analysis and ATR FT-IR spectral indices acquired by the reported procedures, among developmental Texas Marker-1 (TM-1) and immature fiber (im) mutant cotton fibers. It was observed that the R value, CI_IR, and the integrated intensity of the 895 cm⁻¹ band exhibited strong and linear relationships with cellulose content. The results have demonstrated the suitability and utility of ATR FT-IR spectroscopy, combined with a simple algorithm analysis, in assessing cotton fiber cellulose content, maturity, and crystallinity in a manner which is rapid, routine, and non-destructive. Full article

(This article belongs to the Section Chemical Sensors)

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13 pages, 3341 KiB

Open AccessArticle

A Decision Mixture Model-Based Method for Inshore Ship Detection Using High-Resolution Remote Sensing Images

by Fukun Bi^1,*, Jing Chen^1,*, Yin Zhuang², Mingming Bian³ and Qingjun Zhang³

¹ Department of Electronic and Information Engineering, North China University of Technology, Beijing 100144, China

² Department of Information and Electronic, Beijing Institute of Technology, Beijing 100081, China

³ Beijing Institute of Spacecraft System Engineering, Beijing 100094, China

Sensors 2017, 17(7), 1470; https://doi.org/10.3390/s17071470 - 22 Jun 2017

Cited by 29 | Viewed by 5220

Abstract

With the rapid development of optical remote sensing satellites, ship detection and identification based on large-scale remote sensing images has become a significant maritime research topic. Compared with traditional ocean-going vessel detection, inshore ship detection has received increasing attention in harbor dynamic surveillance [...] Read more.

With the rapid development of optical remote sensing satellites, ship detection and identification based on large-scale remote sensing images has become a significant maritime research topic. Compared with traditional ocean-going vessel detection, inshore ship detection has received increasing attention in harbor dynamic surveillance and maritime management. However, because the harbor environment is complex, gray information and texture features between docked ships and their connected dock regions are indistinguishable, most of the popular detection methods are limited by their calculation efficiency and detection accuracy. In this paper, a novel hierarchical method that combines an efficient candidate scanning strategy and an accurate candidate identification mixture model is presented for inshore ship detection in complex harbor areas. First, in the candidate region extraction phase, an omnidirectional intersected two-dimension scanning (OITDS) strategy is designed to rapidly extract candidate regions from the land-water segmented images. In the candidate region identification phase, a decision mixture model (DMM) is proposed to identify real ships from candidate objects. Specifically, to improve the robustness regarding the diversity of ships, a deformable part model (DPM) was employed to train a key part sub-model and a whole ship sub-model. Furthermore, to improve the identification accuracy, a surrounding correlation context sub-model is built. Finally, to increase the accuracy of candidate region identification, these three sub-models are integrated into the proposed DMM. Experiments were performed on numerous large-scale harbor remote sensing images, and the results showed that the proposed method has high detection accuracy and rapid computational efficiency. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 2304 KiB

Open AccessArticle

Analysis of Serotonin Molecules on Silver Nanocolloids—A Raman Computational and Experimental Study

by Felicia S. Manciu^1,2,3,*, John D. Ciubuc^1,2, Emma M. Sundin¹, Chao Qiu¹ and Kevin E. Bennet⁴

¹ Department of Physics, University of Texas at El Paso, El Paso, TX 79968, USA

² Department of Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968, USA

³ Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX 79968, USA

⁴ Division of Engineering, Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA

Sensors 2017, 17(7), 1471; https://doi.org/10.3390/s17071471 - 22 Jun 2017

Cited by 10 | Viewed by 5945

Abstract

Combined theoretical and experimental analysis of serotonin by quantum chemical density functional calculations and surface-enhanced Raman spectroscopy, respectively, is presented in this work to better understand phenomena related to this neurotransmitter’s detection and monitoring at very low concentrations specific to physiological levels. In [...] Read more.

Combined theoretical and experimental analysis of serotonin by quantum chemical density functional calculations and surface-enhanced Raman spectroscopy, respectively, is presented in this work to better understand phenomena related to this neurotransmitter’s detection and monitoring at very low concentrations specific to physiological levels. In addition to the successful ultrasensitive analyte detection on silver nanoparticles for concentrations as low as 10⁻¹¹ molar, the relatively good agreement between the simulated and experimentally determined results indicates the presence of all serotonin molecular forms, such as neutral, ionic, and those oxidized through redox reactions. Obvious structural molecular deformations such as bending of lateral amino chains are observed for both ionic and oxidized forms. Not only does this combined approach reveal more probable adsorption of serotonin into the silver surface through hydroxyl/oxygen sites than through NH/nitrogen sites, but also that it does so predominantly in its neutral (reduced) form, somewhat less so in its ionic forms, and much less in its oxidized forms. If the development of opto-voltammetric biosensors and their effective implementation is envisioned for the future, this study provides some needed scientific background for comprehending changes in the vibrational signatures of this important neurotransmitter. Full article

(This article belongs to the Special Issue Applications of Raman Spectroscopy in Biosensors)

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9 pages, 5529 KiB

Open AccessArticle

Performance Optimization Design for a High-Speed Weak FBG Interrogation System Based on DFB Laser

by Yiqiang Yao¹, Zhengying Li^1,2,*

, Yiming Wang², Siqi Liu², Yutang Dai¹, Jianmin Gong³ and Lixin Wang¹

¹ National Engineering Laboratory for Fiber Optic Sensing Technology, Wuhan University of Technology, Wuhan 430070, China

² Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China

³ Department of Optical Access Network, Huawei Technologies USA, Santa Clara, CA 95050, USA

Sensors 2017, 17(7), 1472; https://doi.org/10.3390/s17071472 - 22 Jun 2017

Cited by 17 | Viewed by 5367

Abstract

A performance optimization design for a high-speed fiber Bragg grating (FBG) interrogation system based on a high-speed distributed feedback (DFB) swept laser is proposed. A time-division-multiplexing sensor network with identical weak FBGs is constituted to realize high-capacity sensing. In order to further improve [...] Read more.

A performance optimization design for a high-speed fiber Bragg grating (FBG) interrogation system based on a high-speed distributed feedback (DFB) swept laser is proposed. A time-division-multiplexing sensor network with identical weak FBGs is constituted to realize high-capacity sensing. In order to further improve the multiplexing capacity, a waveform repairing algorithm is designed to extend the dynamic demodulation range of FBG sensors. It is based on the fact that the spectrum of an FBG keeps stable over a long period of time. Compared with the pre-collected spectra, the distorted spectra waveform are identified and repaired. Experimental results show that all the identical weak FBGs are distinguished and demodulated at the speed of 100 kHz with a linearity of above 0.99, and the range of dynamic demodulation is extended by 40%. Full article

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

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20 pages, 28184 KiB

Open AccessArticle

Stereo Vision-Based High Dynamic Range Imaging Using Differently-Exposed Image Pair

by Won-Jae Park¹, Seo-Won Ji¹, Seok-Jae Kang², Seung-Won Jung³ and Sung-Jea Ko^1,*

¹ School of Electrical Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-701, Korea

² Samsung Electronics Co. Ltd., 1, Samsungjeonja-ro, Hwaseong-si 445-330, Gyeonggi-do, Korea

³ Department of Multimedia Engineering, Dongguk University, Pildong-ro 1gil 30, Jung-gu, Seoul 100-715; Korea

Sensors 2017, 17(7), 1473; https://doi.org/10.3390/s17071473 - 22 Jun 2017

Cited by 20 | Viewed by 6405

Abstract

In this paper, a high dynamic range (HDR) imaging method based on the stereo vision system is presented. The proposed method uses differently exposed low dynamic range (LDR) images captured from a stereo camera. The stereo LDR images are first converted to initial [...] Read more.

In this paper, a high dynamic range (HDR) imaging method based on the stereo vision system is presented. The proposed method uses differently exposed low dynamic range (LDR) images captured from a stereo camera. The stereo LDR images are first converted to initial stereo HDR images using the inverse camera response function estimated from the LDR images. However, due to the limited dynamic range of the stereo LDR camera, the radiance values in under/over-exposed regions of the initial main-view (MV) HDR image can be lost. To restore these radiance values, the proposed stereo matching and hole-filling algorithms are applied to the stereo HDR images. Specifically, the auxiliary-view (AV) HDR image is warped by using the estimated disparity between initial the stereo HDR images and then effective hole-filling is applied to the warped AV HDR image. To reconstruct the final MV HDR, the warped and hole-filled AV HDR image is fused with the initial MV HDR image using the weight map. The experimental results demonstrate objectively and subjectively that the proposed stereo HDR imaging method provides better performance compared to the conventional method. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2657 KiB

Open AccessArticle

A Study for Texture Feature Extraction of High-Resolution Satellite Images Based on a Direction Measure and Gray Level Co-Occurrence Matrix Fusion Algorithm

by Xin Zhang^1,*

, Jintian Cui^1,2, Weisheng Wang³ and Chao Lin⁴

¹ Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China

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

³ Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi 830011, China

⁴ Bureau of Upriver of Zhang Management, Hai River Management Committee Ministry of Water Resources of China, Handan 056006, China

Sensors 2017, 17(7), 1474; https://doi.org/10.3390/s17071474 - 22 Jun 2017

Cited by 188 | Viewed by 10468

Abstract

To address the problem of image texture feature extraction, a direction measure statistic that is based on the directionality of image texture is constructed, and a new method of texture feature extraction, which is based on the direction measure and a gray level [...] Read more.

To address the problem of image texture feature extraction, a direction measure statistic that is based on the directionality of image texture is constructed, and a new method of texture feature extraction, which is based on the direction measure and a gray level co-occurrence matrix (GLCM) fusion algorithm, is proposed in this paper. This method applies the GLCM to extract the texture feature value of an image and integrates the weight factor that is introduced by the direction measure to obtain the final texture feature of an image. A set of classification experiments for the high-resolution remote sensing images were performed by using support vector machine (SVM) classifier with the direction measure and gray level co-occurrence matrix fusion algorithm. Both qualitative and quantitative approaches were applied to assess the classification results. The experimental results demonstrated that texture feature extraction based on the fusion algorithm achieved a better image recognition, and the accuracy of classification based on this method has been significantly improved. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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18 pages, 3528 KiB

Open AccessArticle

Block-Diagonal Constrained Low-Rank and Sparse Graph for Discriminant Analysis of Image Data

by Tan Guo^*, Xiaoheng Tan^*, Lei Zhang^*

, Chaochen Xie and Lu Deng

College of Communication Engineering, Chongqing University, Chongqing 400044, China

Sensors 2017, 17(7), 1475; https://doi.org/10.3390/s17071475 - 22 Jun 2017

Cited by 2 | Viewed by 5320

Abstract

Recently, low-rank and sparse model-based dimensionality reduction (DR) methods have aroused lots of interest. In this paper, we propose an effective supervised DR technique named block-diagonal constrained low-rank and sparse-based embedding (BLSE). BLSE has two steps, i.e., block-diagonal constrained low-rank and sparse representation [...] Read more.

Recently, low-rank and sparse model-based dimensionality reduction (DR) methods have aroused lots of interest. In this paper, we propose an effective supervised DR technique named block-diagonal constrained low-rank and sparse-based embedding (BLSE). BLSE has two steps, i.e., block-diagonal constrained low-rank and sparse representation (BLSR) and block-diagonal constrained low-rank and sparse graph embedding (BLSGE). Firstly, the BLSR model is developed to reveal the intrinsic intra-class and inter-class adjacent relationships as well as the local neighborhood relations and global structure of data. Particularly, there are mainly three items considered in BLSR. First, a sparse constraint is required to discover the local data structure. Second, a low-rank criterion is incorporated to capture the global structure in data. Third, a block-diagonal regularization is imposed on the representation to promote discrimination between different classes. Based on BLSR, informative and discriminative intra-class and inter-class graphs are constructed. With the graphs, BLSGE seeks a low-dimensional embedding subspace by simultaneously minimizing the intra-class scatter and maximizing the inter-class scatter. Experiments on public benchmark face and object image datasets demonstrate the effectiveness of the proposed approach. Full article

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

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20 pages, 1060 KiB

Open AccessArticle

A Comprehensive Study on the Internet of Underwater Things: Applications, Challenges, and Channel Models

by Chien-Chi Kao^1,*

, Yi-Shan Lin², Geng-De Wu¹ and Chun-Ju Huang¹

¹ Department of Communications, Navigation and Control Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan

² Department of Computer Science, National Chiao Tung University, Hsinchu 30010, Taiwan

Sensors 2017, 17(7), 1477; https://doi.org/10.3390/s17071477 - 22 Jun 2017

Cited by 226 | Viewed by 15513

Abstract

The Internet of Underwater Things (IoUT) is a novel class of Internet of Things (IoT), and is defined as the network of smart interconnected underwater objects. IoUT is expected to enable various practical applications, such as environmental monitoring, underwater exploration, and disaster prevention. [...] Read more.

The Internet of Underwater Things (IoUT) is a novel class of Internet of Things (IoT), and is defined as the network of smart interconnected underwater objects. IoUT is expected to enable various practical applications, such as environmental monitoring, underwater exploration, and disaster prevention. With these applications, IoUT is regarded as one of the potential technologies toward developing smart cities. To support the concept of IoUT, Underwater Wireless Sensor Networks (UWSNs) have emerged as a promising network system. UWSNs are different from the traditional Territorial Wireless Sensor Networks (TWSNs), and have several unique properties, such as long propagation delay, narrow bandwidth, and low reliability. These unique properties would be great challenges for IoUT. In this paper, we provide a comprehensive study of IoUT, and the main contributions of this paper are threefold: (1) we introduce and classify the practical underwater applications that can highlight the importance of IoUT; (2) we point out the differences between UWSNs and traditional TWSNs, and these differences are the main challenges for IoUT; and (3) we investigate and evaluate the channel models, which are the technical core for designing reliable communication protocols on IoUT. Full article

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

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13 pages, 15622 KiB

Open AccessArticle

Trimethylamine Sensors Based on Au-Modified Hierarchical Porous Single-Crystalline ZnO Nanosheets

by Fanli Meng¹

, Hanxiong Zheng², Yufeng Sun^2,*, Minqiang Li³ and Jinhuai Liu³

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

² Department of Mechanical and Automotive Engineering, Anhui Polytechnic University, Wuhu 241000, China

³ Nanomaterials and Environment Detection Laboratory, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, China

Sensors 2017, 17(7), 1478; https://doi.org/10.3390/s17071478 - 22 Jun 2017

Cited by 105 | Viewed by 7618

Abstract

It is of great significance for dynamic monitoring of foods in storage or during the transportation process through on-line detecting trimethylamine (TMA). Here, TMA were sensitively detected by Au-modified hierarchical porous single-crystalline ZnO nanosheets (HPSCZNs)-based sensors. The HPSCZNs were synthesized through a one-pot [...] Read more.

It is of great significance for dynamic monitoring of foods in storage or during the transportation process through on-line detecting trimethylamine (TMA). Here, TMA were sensitively detected by Au-modified hierarchical porous single-crystalline ZnO nanosheets (HPSCZNs)-based sensors. The HPSCZNs were synthesized through a one-pot wet-chemical method followed by an annealing treatment. Polyethyleneimine (PEI) was used to modify the surface of the HPSCZNs, and then the PEI-modified samples were mixed with Au nanoparticles (NPs) sol solution. Electrostatic interactions drive Au nanoparticles loading onto the surface of the HPSCZNs. The Au-modified HPSCZNs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS), respectively. The results show that Au-modified HPSCZNs-based sensors exhibit a high response to TMA. The linear range is from 10 to 300 ppb; while the detection limit is 10 ppb, which is the lowest value to our knowledge. Full article

(This article belongs to the Section Chemical Sensors)

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16 pages, 4959 KiB

Open AccessArticle

GADEN: A 3D Gas Dispersion Simulator for Mobile Robot Olfaction in Realistic Environments

by Javier Monroy^1,*

, Victor Hernandez-Bennetts²

, Han Fan², Achim Lilienthal²

and Javier Gonzalez-Jimenez¹

¹ Machine Perception and Intelligent Robotics group (MAPIR), Instituto de Investigación Biomedica de Malaga (IBIMA), Universidad de Malaga, 29071 Malaga, Spain

² Applied Autonomous Sensor Systems, Örebro University, Fakultetsgatan 1, 70182 Örebro, Sweden

Sensors 2017, 17(7), 1479; https://doi.org/10.3390/s17071479 - 23 Jun 2017

Cited by 98 | Viewed by 17161

Abstract

This work presents a simulation framework developed under the widely used Robot Operating System (ROS) to enable the validation of robotics systems and gas sensing algorithms under realistic environments. The framework is rooted in the principles of computational fluid dynamics and filament dispersion [...] Read more.

This work presents a simulation framework developed under the widely used Robot Operating System (ROS) to enable the validation of robotics systems and gas sensing algorithms under realistic environments. The framework is rooted in the principles of computational fluid dynamics and filament dispersion theory, modeling wind flow and gas dispersion in 3D real-world scenarios (i.e., accounting for walls, furniture, etc.). Moreover, it integrates the simulation of different environmental sensors, such as metal oxide gas sensors, photo ionization detectors, or anemometers. We illustrate the potential and applicability of the proposed tool by presenting a simulation case in a complex and realistic office-like environment where gas leaks of different chemicals occur simultaneously. Furthermore, we accomplish quantitative and qualitative validation by comparing our simulated results against real-world data recorded inside a wind tunnel where methane was released under different wind flow profiles. Based on these results, we conclude that our simulation framework can provide a good approximation to real world measurements when advective airflows are present in the environment. Full article

(This article belongs to the Section Chemical Sensors)

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11 pages, 2076 KiB

Open AccessArticle

Adenosine Triphosphate-Encapsulated Liposomes with Plasmonic Nanoparticles for Surface Enhanced Raman Scattering-Based Immunoassays

by Xuan-Hung Pham¹

, Eunil Hahm¹, Tae Han Kim¹, Hyung-Mo Kim¹, Sang Hun Lee², Yoon-Sik Lee², Dae Hong Jeong³ and Bong-Hyun Jun^1,*

¹ Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Korea

² School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea

³ Department of Chemistry Education, Seoul National University, Seoul 151-742, Korea

Sensors 2017, 17(7), 1480; https://doi.org/10.3390/s17071480 - 23 Jun 2017

Cited by 11 | Viewed by 7747

Abstract

In this study, we prepared adenosine triphosphate (ATP) encapsulated liposomes, and assessed their applicability for the surface enhanced Raman scattering (SERS)-based assays with gold-silver alloy (Au@Ag)-assembled silica nanoparticles (NPs; SiO₂@Au@Ag). The liposomes were prepared by the thin film hydration method from [...] Read more.

In this study, we prepared adenosine triphosphate (ATP) encapsulated liposomes, and assessed their applicability for the surface enhanced Raman scattering (SERS)-based assays with gold-silver alloy (Au@Ag)-assembled silica nanoparticles (NPs; SiO₂@Au@Ag). The liposomes were prepared by the thin film hydration method from a mixture of l-α-phosphatidylcholine, cholesterol, and PE-PEG2000 in chloroform; evaporating the solvent, followed by hydration of the resulting thin film with ATP in phosphate-buffered saline (PBS). Upon lysis of the liposome, the SERS intensity of the SiO₂@Au@Ag NPs increased with the logarithm of number of ATP-encapsulated liposomes after lysis in the range of 8 × 10⁶ to 8 × 10¹⁰. The detection limit of liposome was calculated to be 1.3 × 10⁻¹⁷ mol. The successful application of ATP-encapsulated liposomes to SiO₂@Au@Ag NPs based SERS analysis has opened a new avenue for Raman label chemical (RCL)-encapsulated liposome-enhanced SERS-based immunoassays. Full article

(This article belongs to the Special Issue Novel Approaches to Biosensing with Nanoparticles)

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10 pages, 2184 KiB

Open AccessArticle

An Operational In Situ Soil Moisture & Soil Temperature Monitoring Network for West Wales, UK: The WSMN Network

by George P. Petropoulos^1,*

and Jon P. McCalmont²

¹ Department of Geography and Earth Sciences, University of Aberystwyth, Aberystwyth SY23 3DB, UK

² Institute of Biological Environmental and Rural Sciences, University of Aberystwyth, Aberystwyth SY23 3EE, UK

Sensors 2017, 17(7), 1481; https://doi.org/10.3390/s17071481 - 23 Jun 2017

Cited by 31 | Viewed by 6485

Abstract

This paper describes a soil moisture dataset that has been collecting ground measurements of soil moisture, soil temperature and related parameters for west Wales, United Kingdom. Already acquired in situ data have been archived to the autonomous Wales Soil Moisture Network (WSMN) since [...] Read more.

This paper describes a soil moisture dataset that has been collecting ground measurements of soil moisture, soil temperature and related parameters for west Wales, United Kingdom. Already acquired in situ data have been archived to the autonomous Wales Soil Moisture Network (WSMN) since its foundation in July 2011. The sites from which measurements are being collected represent a range of conditions typical of the Welsh environment, with climate ranging from oceanic to temperate and a range of the most typical land use/cover types found in Wales. At present, WSMN consists of a total of nine monitoring sites across the area with a concentration of sites in three sub-areas around the region of Aberystwyth located in Mid-Wales. The dataset of composed of 0–5 (or 0–10) cm soil moisture, soil temperature, precipitation, and other ancillary data. WSMN data are provided openly to the public via the International Soil Moisture Network (ISMN) platform. At present, WSMN is also rapidly expanding thanks to funding obtained recently which allows more monitoring sites to be added to the network to the wider community interested in using its data. Full article

(This article belongs to the Special Issue Earth Observation and In-Situ Sensing for Risk Assessment from Natural Threats)

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18 pages, 483 KiB

Open AccessArticle

An Efficient User Authentication and User Anonymity Scheme with Provably Security for IoT-Based Medical Care System

by Chun-Ta Li¹

, Tsu-Yang Wu^2,3,*, Chin-Ling Chen^4,5,*, Cheng-Chi Lee^6,7

and Chien-Ming Chen⁸

¹ Department of Information Management, Tainan University of Technology, 529 Zhongzheng Road, Tainan 71002, Taiwan

² Fujian Provincial Key Laboratory of Big Data Mining and Applications, Fujian University of Technology, Fuzhou 350118, China

³ National Demonstration Center for Experimental Electronic Information and Electrical Technology Education, Fujian University of Technology, 3 Xueyuan Road, Fuzhou 350118, China

⁴ Department of Computer Science and Information Engineering, Chaoyang University of Technology, 168 Jifeng East Road, Taichung 41349, Taiwan

⁵ School of Information Engineering, Changchun University of Technology, Changchun 130600, China

⁶ Department of Library and Information Science, Fu Jen Catholic University, 510 Jhongjheng Road, New Taipei 24205, Taiwan

⁷ Department of Photonics and Communication Engineering, Asia University, 500 Lioufeng Road, Taichung 41354, Taiwan

⁸ Harbin Institute of Technology Shenzhen Graduate School, Shenzhen University Town, Xili, Nanshan District, Shenzhen 518055, China

Sensors 2017, 17(7), 1482; https://doi.org/10.3390/s17071482 - 23 Jun 2017

Cited by 118 | Viewed by 8394

Abstract

In recent years, with the increase in degenerative diseases and the aging population in advanced countries, demands for medical care of older or solitary people have increased continually in hospitals and healthcare institutions. Applying wireless sensor networks for the IoT-based telemedicine system enables [...] Read more.

In recent years, with the increase in degenerative diseases and the aging population in advanced countries, demands for medical care of older or solitary people have increased continually in hospitals and healthcare institutions. Applying wireless sensor networks for the IoT-based telemedicine system enables doctors, caregivers or families to monitor patients’ physiological conditions at anytime and anyplace according to the acquired information. However, transmitting physiological data through the Internet concerns the personal privacy of patients. Therefore, before users can access medical care services in IoT-based medical care system, they must be authenticated. Typically, user authentication and data encryption are most critical for securing network communications over a public channel between two or more participants. In 2016, Liu and Chung proposed a bilinear pairing-based password authentication scheme for wireless healthcare sensor networks. They claimed their authentication scheme cannot only secure sensor data transmission, but also resist various well-known security attacks. In this paper, we demonstrate that Liu–Chung’s scheme has some security weaknesses, and we further present an improved secure authentication and data encryption scheme for the IoT-based medical care system, which can provide user anonymity and prevent the security threats of replay and password/sensed data disclosure attacks. Moreover, we modify the authentication process to reduce redundancy in protocol design, and the proposed scheme is more efficient in performance compared with previous related schemes. Finally, the proposed scheme is provably secure in the random oracle model under ECDHP. Full article

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

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13 pages, 1119 KiB

Open AccessArticle

Relationship between Remote Sensing Data, Plant Biomass and Soil Nitrogen Dynamics in Intensively Managed Grasslands under Controlled Conditions

by Christoph Knoblauch^1,*, Conor Watson¹, Clara Berendonk², Rolf Becker³, Nicole Wrage-Mönnig⁴ and Florian Wichern¹

¹ Faculty of Life Sciences, Rhine-Waal University of Applied Sciences, Marie-Curie-Str. 1, 47533 Kleve, Germany

² Versuchs- und Bildungszentrum Landwirtschaft Haus Riswick, Elsenpaß 5, 47533 Kleve, Germany

³ Faculty of Communication and Environment, Rhine-Waal University of Applied Sciences, Friedrich-Heinrich-Allee 25, 47475 Kamp-Lintfort, Germany

⁴ Grassland and Fodder Sciences, Faculty of Agriculture and the Environment, University of Rostock, Justus-von-Liebig-Weg 6, 18059 Rostock, Germany

Sensors 2017, 17(7), 1483; https://doi.org/10.3390/s17071483 - 23 Jun 2017

Cited by 14 | Viewed by 5967

Abstract

The sustainable use of grasslands in intensive farming systems aims to optimize nitrogen (N) inputs to increase crop yields and decrease harmful losses to the environment at the same time. To achieve this, simple optical sensors may provide a non-destructive, time- and cost-effective [...] Read more.

The sustainable use of grasslands in intensive farming systems aims to optimize nitrogen (N) inputs to increase crop yields and decrease harmful losses to the environment at the same time. To achieve this, simple optical sensors may provide a non-destructive, time- and cost-effective tool for estimating plant biomass in the field, considering spatial and temporal variability. However, the plant growth and related N uptake is affected by the available N in the soil, and therefore, N mineralization and N losses. These soil N dynamics and N losses are affected by the N input and environmental conditions, and cannot easily be determined non-destructively. Therefore, the question arises: whether a relationship can be depicted between N fertilizer levels, plant biomass and N dynamics as indicated by nitrous oxide (N₂O) losses and inorganic N levels. We conducted a standardized greenhouse experiment to explore the potential of spectral measurements for analyzing yield response, N mineralization and N₂O emissions in a permanent grassland. Ryegrass was subjected to four mineral fertilizer input levels over 100 days (four harvests) under controlled environmental conditions. The soil temperature and moisture content were automatically monitored, and the emission rates of N₂O and carbon dioxide (CO₂) were detected frequently. Spectral measurements of the swards were performed directly before harvesting. The normalized difference vegetation index (NDVI) and simple ratio (SR) were moderately correlated with an increasing biomass as affected by fertilization level. Furthermore, we found a non-linear response of increasing N₂O emissions to elevated fertilizer levels. Moreover, inorganic N and extractable organic N levels at the end of the experiment tended to increase with the increasing N fertilizer addition. However, microbial biomass C and CO₂ efflux showed no significant differences among fertilizer treatments, reflecting no substantial changes in the soil biological pool size and the extent of the C mineralization. Neither the NDVI nor SR, nor the plant biomass, were related to cumulative N₂O emissions or inorganic N at harvesting. Our results verify the usefulness of optical sensors for biomass detection, and show the difficulty in linking spectral measurements of plant traits to N processes in the soil, despite that the latter affects the former. Full article

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

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18 pages, 2082 KiB

Open AccessFeature PaperArticle

Probing the Interaction of Dielectric Nanoparticles with Supported Lipid Membrane Coatings on Nanoplasmonic Arrays

by Abdul Rahim Ferhan^1,†, Gamaliel Junren Ma^1,†, Joshua A. Jackman¹, Tun Naw Sut¹, Jae Hyeon Park¹ and Nam-Joon Cho^1,2,*

¹ School of Materials Science and Engineering and Centre for Biomimetic Sensor Science, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore

² School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1484; https://doi.org/10.3390/s17071484 - 23 Jun 2017

Cited by 16 | Viewed by 6603

Abstract

The integration of supported lipid membranes with surface-based nanoplasmonic arrays provides a powerful sensing approach to investigate biointerfacial phenomena at membrane interfaces. While a growing number of lipid vesicles, protein, and nucleic acid systems have been explored with nanoplasmonic sensors, there has been [...] Read more.

The integration of supported lipid membranes with surface-based nanoplasmonic arrays provides a powerful sensing approach to investigate biointerfacial phenomena at membrane interfaces. While a growing number of lipid vesicles, protein, and nucleic acid systems have been explored with nanoplasmonic sensors, there has been only very limited investigation of the interactions between solution-phase nanomaterials and supported lipid membranes. Herein, we established a surface-based localized surface plasmon resonance (LSPR) sensing platform for probing the interaction of dielectric nanoparticles with supported lipid bilayer (SLB)-coated, plasmonic nanodisk arrays. A key emphasis was placed on controlling membrane functionality by tuning the membrane surface charge vis-à-vis lipid composition. The optical sensing properties of the bare and SLB-coated sensor surfaces were quantitatively compared, and provided an experimental approach to evaluate nanoparticle–membrane interactions across different SLB platforms. While the interaction of negatively-charged silica nanoparticles (SiNPs) with a zwitterionic SLB resulted in monotonic adsorption, a stronger interaction with a positively-charged SLB resulted in adsorption and lipid transfer from the SLB to the SiNP surface, in turn influencing the LSPR measurement responses based on the changing spatial proximity of transferred lipids relative to the sensor surface. Precoating SiNPs with bovine serum albumin (BSA) suppressed lipid transfer, resulting in monotonic adsorption onto both zwitterionic and positively-charged SLBs. Collectively, our findings contribute a quantitative understanding of how supported lipid membrane coatings influence the sensing performance of nanoplasmonic arrays, and demonstrate how the high surface sensitivity of nanoplasmonic sensors is well-suited for detecting the complex interactions between nanoparticles and lipid membranes. Full article

(This article belongs to the Special Issue Micro and Nanofabrication Technologies for Biosensors)

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14 pages, 3831 KiB

Open AccessArticle

A Novel Wearable Forehead EOG Measurement System for Human Computer Interfaces

by Jeong Heo¹, Heenam Yoon¹ and Kwang Suk Park^2,*

¹ Interdisciplinary Program of Bioengineering, Seoul National University, Seoul 03080, Korea

² Department of Biomedical Engineering, College of Medicine, Seoul National University, Seoul 03080, Korea

Sensors 2017, 17(7), 1485; https://doi.org/10.3390/s17071485 - 23 Jun 2017

Cited by 77 | Viewed by 17159

Abstract

Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is [...] Read more.

Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is generated by eye movements and can be measured with electrodes placed around the eye. In this study, we proposed a new practical electrode position on the forehead to measure EOG signals, and we developed a wearable forehead EOG measurement system for use in Human Computer/Machine interfaces (HCIs/HMIs). Four electrodes, including the ground electrode, were placed on the forehead. The two channels were arranged vertically and horizontally, sharing a positive electrode. Additionally, a real-time eye movement classification algorithm was developed based on the characteristics of the forehead EOG. Three applications were employed to evaluate the proposed system: a virtual keyboard using a modified Bremen BCI speller and an automatic sequential row-column scanner, and a drivable power wheelchair. The mean typing speeds of the modified Bremen brain–computer interface (BCI) speller and automatic row-column scanner were 10.81 and 7.74 letters per minute, and the mean classification accuracies were 91.25% and 95.12%, respectively. In the power wheelchair demonstration, the user drove the wheelchair through an 8-shape course without collision with obstacles. Full article

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

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24 pages, 2653 KiB

Open AccessArticle

Context Relevant Prediction Model for COPD Domain Using Bayesian Belief Network

by Hamid Mcheick^1,*

, Lokman Saleh², Hicham Ajami¹ and Hafedh Mili²

¹ Computer Science Department, University of Quebec at Chicoutimi, Chicoutimi, QC G7H 2B1, Canada

² Computer Science Department, University of Quebec at Montreal, Montreal, QC H2L 2C4, Canada

Sensors 2017, 17(7), 1486; https://doi.org/10.3390/s17071486 - 23 Jun 2017

Cited by 18 | Viewed by 6412

Abstract

In the last three decades, researchers have examined extensively how context-aware systems can assist people, specifically those suffering from incurable diseases, to help them cope with their medical illness. Over the years, a huge number of studies on Chronic Obstructive Pulmonary Disease (COPD) [...] Read more.

In the last three decades, researchers have examined extensively how context-aware systems can assist people, specifically those suffering from incurable diseases, to help them cope with their medical illness. Over the years, a huge number of studies on Chronic Obstructive Pulmonary Disease (COPD) have been published. However, how to derive relevant attributes and early detection of COPD exacerbations remains a challenge. In this research work, we will use an efficient algorithm to select relevant attributes where there is no proper approach in this domain. Such algorithm predicts exacerbations with high accuracy by adding discretization process, and organizes the pertinent attributes in priority order based on their impact to facilitate the emergency medical treatment. In this paper, we propose an extension of our existing Helper Context-Aware Engine System (HCES) for COPD. This project uses Bayesian network algorithm to depict the dependency between the COPD symptoms (attributes) in order to overcome the insufficiency and the independency hypothesis of naïve Bayesian. In addition, the dependency in Bayesian network is realized using TAN algorithm rather than consulting pneumologists. All these combined algorithms (discretization, selection, dependency, and the ordering of the relevant attributes) constitute an effective prediction model, comparing to effective ones. Moreover, an investigation and comparison of different scenarios of these algorithms are also done to verify which sequence of steps of prediction model gives more accurate results. Finally, we designed and validated a computer-aided support application to integrate different steps of this model. The findings of our system HCES has shown promising results using Area Under Receiver Operating Characteristic (AUC = 81.5%). Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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21 pages, 2320 KiB

Open AccessArticle

An Energy-Efficient Multi-Tier Architecture for Fall Detection on Smartphones

by M. Amac Guvensan^1,*, A. Oguz Kansiz², N. Cihan Camgoz³, H. Irem Turkmen¹, A. Gokhan Yavuz¹ and M. Elif Karsligil¹

¹ Department of Computer Engineering, Yildiz Technical University, 34220 Istanbul, Turkey

² IT Department, Garanti Technology, 34212 Istanbul, Turkey

³ Centre for Vision, Speech and Signal Processing (CVSSP), University of Surrey, GU2 7XH Guildford, UK

Sensors 2017, 17(7), 1487; https://doi.org/10.3390/s17071487 - 23 Jun 2017

Cited by 17 | Viewed by 5361

Abstract

Automatic detection of fall events is vital to providing fast medical assistance to the causality, particularly when the injury causes loss of consciousness. Optimization of the energy consumption of mobile applications, especially those which run 24/7 in the background, is essential for longer [...] Read more.

Automatic detection of fall events is vital to providing fast medical assistance to the causality, particularly when the injury causes loss of consciousness. Optimization of the energy consumption of mobile applications, especially those which run 24/7 in the background, is essential for longer use of smartphones. In order to improve energy-efficiency without compromising on the fall detection performance, we propose a novel 3-tier architecture that combines simple thresholding methods with machine learning algorithms. The proposed method is implemented on a mobile application, called uSurvive, for Android smartphones. It runs as a background service and monitors the activities of a person in daily life and automatically sends a notification to the appropriate authorities and/or user defined contacts when it detects a fall. The performance of the proposed method was evaluated in terms of fall detection performance and energy consumption. Real life performance tests conducted on two different models of smartphone demonstrate that our 3-tier architecture with feature reduction could save up to 62% of energy compared to machine learning only solutions. In addition to this energy saving, the hybrid method has a 93% of accuracy, which is superior to thresholding methods and better than machine learning only solutions. Full article

(This article belongs to the Section Sensor Networks)

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9 pages, 2701 KiB

Open AccessArticle

Slab Waveguide and Optical Fibers for Novel Plasmonic Sensor Configurations

by Nunzio Cennamo^*

, Francesco Mattiello and Luigi Zeni

Department of Industrial and Information Engineering, University of Campania “L. Vanvitelli”, via Roma 29, 81031 Aversa, Italy

Sensors 2017, 17(7), 1488; https://doi.org/10.3390/s17071488 - 24 Jun 2017

Cited by 29 | Viewed by 6531

Abstract

The use of plasmonic sensor devices often requires replaceable parts and disposable chips for easy, fast and on-site detection analysis. In light of these requests, we propose a novel low-cost surface plasmon resonance sensor platform for possible selective detection of analytes in aqueous [...] Read more.

The use of plasmonic sensor devices often requires replaceable parts and disposable chips for easy, fast and on-site detection analysis. In light of these requests, we propose a novel low-cost surface plasmon resonance sensor platform for possible selective detection of analytes in aqueous solutions. It is based on a Polymethyl methacrylate (PMMA) slab waveguide with a thin gold film on the top surface inserted in a special holder, designed to produce the plasmonic resonance at the gold-dielectric interface. A wide-band light is launched in the PMMA slab waveguide through a trench realized in the holder directly, and illuminated with a PMMA plastic optical fiber (POF) to excite surface Plasmon waves. The output light is then collected by another PMMA POF kept at the end of the slab at an angle of 90° to the trench, and carried to a spectrometer. In this configuration, the trench has been used because a large incident angle is required for surface plasmon resonance excitation. The preliminary results showed that the sensor’s performances make it suitable for bio-chemical applications. The easy replacement of the chip allows for the production of an engineered platform by simplifying the measurement procedures. Full article

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

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12 pages, 1547 KiB

Open AccessArticle

A Direct Georeferencing Method for Terrestrial Laser Scanning Using GNSS Data and the Vertical Deflection from Global Earth Gravity Models

by Edward Osada

, Krzysztof Sośnica

, Andrzej Borkowski^*, Magdalena Owczarek-Wesołowska and Anna Gromczak

Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, ul, Grunwaldzka 53, 50-357 Wrocław, Poland

Sensors 2017, 17(7), 1489; https://doi.org/10.3390/s17071489 - 24 Jun 2017

Cited by 13 | Viewed by 6615

Abstract

Terrestrial laser scanning is an efficient technique in providing highly accurate point clouds for various geoscience applications. The point clouds have to be transformed to a well-defined reference frame, such as the global Geodetic Reference System 1980. The transformation to the geocentric coordinate [...] Read more.

Terrestrial laser scanning is an efficient technique in providing highly accurate point clouds for various geoscience applications. The point clouds have to be transformed to a well-defined reference frame, such as the global Geodetic Reference System 1980. The transformation to the geocentric coordinate frame is based on estimating seven Helmert parameters using several GNSS (Global Navigation Satellite System) referencing points. This paper proposes a method for direct point cloud georeferencing that provides coordinates in the geocentric frame. The proposed method employs the vertical deflection from an external global Earth gravity model and thus demands a minimum number of GNSS measurements. The proposed method can be helpful when the number of georeferencing GNSS points is limited, for instance in city corridors. It needs only two georeferencing points. The validation of the method in a field test reveals that the differences between the classical georefencing and the proposed method amount at maximum to 7 mm with the standard deviation of 8 mm for all of three coordinate components. The proposed method may serve as an alternative for the laser scanning data georeferencing, especially when the number of GNSS points is insufficient for classical methods. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 4016 KiB

Open AccessArticle

A Real-Time Contactless Pulse Rate and Motion Status Monitoring System Based on Complexion Tracking

by Yu-Chen Lin¹

, Nai-Kuan Chou², Guan-You Lin¹, Meng-Han Li¹ and Yuan-Hsiang Lin^1,*

¹ Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, 10607 Taipei, Taiwan

² Department of Surgery, National Taiwan University Hospital, 10002 Taipei, Taiwan

Sensors 2017, 17(7), 1490; https://doi.org/10.3390/s17071490 - 24 Jun 2017

Cited by 23 | Viewed by 6414

Abstract

Subject movement and a dark environment will increase the difficulty of image-based contactless pulse rate detection. In this paper, we detected the subject’s motion status based on complexion tracking and proposed a motion index (MI) to filter motion artifacts in order to increase [...] Read more.

Subject movement and a dark environment will increase the difficulty of image-based contactless pulse rate detection. In this paper, we detected the subject’s motion status based on complexion tracking and proposed a motion index (MI) to filter motion artifacts in order to increase pulse rate measurement accuracy. Additionally, we integrated the near infrared (NIR) LEDs with the adopted sensor and proposed an effective method to measure the pulse rate in a dark environment. To achieve real-time data processing, the proposed framework is constructed on a Field Programmable Gate Array (FPGA) platform. Next, the instant pulse rate and motion status are transmitted to a smartphone for remote monitoring. The experiment results showed the error of the pulse rate detection to be within −3.44 to +4.53 bpm under sufficient ambient light and −2.96 to + 4.24 bpm for night mode detection, when the moving speed is higher than 14.45 cm/s. These results demonstrate that the proposed method can improve the robustness of image-based contactless pulse rate detection despite subject movement and a dark environment. Full article

(This article belongs to the Special Issue Advanced Physiological Sensing)

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16 pages, 4201 KiB

Open AccessArticle

Simultaneous Calibration: A Joint Optimization Approach for Multiple Kinect and External Cameras

by Yajie Liao¹, Ying Sun^1,2, Gongfa Li^1,2,*, Jianyi Kong^1,2, Guozhang Jiang^1,2, Du Jiang², Haibin Cai³, Zhaojie Ju³, Hui Yu³

and Honghai Liu³

¹ Key Laboratory of Metallurgical Equipment and Control Technology, Wuhan University of Science and Technology, Ministry of Education, Wuhan 430081, China

² Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China

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

Sensors 2017, 17(7), 1491; https://doi.org/10.3390/s17071491 - 24 Jun 2017

Cited by 51 | Viewed by 6926

Abstract

Camera calibration is a crucial problem in many applications, such as 3D reconstruction, structure from motion, object tracking and face alignment. Numerous methods have been proposed to solve the above problem with good performance in the last few decades. However, few methods are [...] Read more.

Camera calibration is a crucial problem in many applications, such as 3D reconstruction, structure from motion, object tracking and face alignment. Numerous methods have been proposed to solve the above problem with good performance in the last few decades. However, few methods are targeted at joint calibration of multi-sensors (more than four devices), which normally is a practical issue in the real-time systems. In this paper, we propose a novel method and a corresponding workflow framework to simultaneously calibrate relative poses of a Kinect and three external cameras. By optimizing the final cost function and adding corresponding weights to the external cameras in different locations, an effective joint calibration of multiple devices is constructed. Furthermore, the method is tested in a practical platform, and experiment results show that the proposed joint calibration method can achieve a satisfactory performance in a project real-time system and its accuracy is higher than the manufacturer’s calibration. Full article

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

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15 pages, 20213 KiB

Open AccessArticle

Static and Dynamic Accuracy of an Innovative Miniaturized Wearable Platform for Short Range Distance Measurements for Human Movement Applications

by Stefano Bertuletti^1,*

, Andrea Cereatti^1,2, Daniele Comotti³

, Michele Caldara³ and Ugo Della Croce¹

¹ Information Engineering Unit, Department of Information Engineering, Political Sciences and Communication Sciences, University of Sassari, Sassari 07100 (SS), Italy

² Department of Electronics and Telecommunications, Politecnico di Torino, Torino 10129 (TO), Italy

³ Department of Engineering and Applied Sciences, University of Bergamo, Dalmine 24044 (BG), Italy

Sensors 2017, 17(7), 1492; https://doi.org/10.3390/s17071492 - 24 Jun 2017

Cited by 27 | Viewed by 7348

Abstract

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. [...] Read more.

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. To overcome this limitation, we developed a wearable platform specifically designed for human movement analysis applications, which integrates a MIMU and an Infrared Time-of-Flight proximity sensor (IR-ToF), allowing for the estimate of inter-object distance. We proposed a thorough testing protocol for evaluating the IR-ToF sensor performances under experimental conditions resembling those encountered during gait. In particular, we tested the sensor performance for different (i) target colors; (ii) sensor-target distances (up to 200 mm) and (iii) sensor-target angles of incidence (AoI) (up to

60^{\circ}

). Both static and dynamic conditions were analyzed. A pendulum, simulating the oscillation of a human leg, was used to generate highly repeatable oscillations with a maximum angular velocity of 6 rad/s. Results showed that the IR-ToF proximity sensor was not sensitive to variations of both distance and target color (except for black). Conversely, a relationship between error magnitude and AoI values was found. For AoI equal to

0^{\circ}

, the IR-ToF sensor performed equally well both in static and dynamic acquisitions with a distance mean absolute error <1.5 mm. Errors increased up to

3.6

mm (static) and

11.9

mm (dynamic) for AoI equal to

\pm 30^{\circ}

, and up to

7.8

mm (static) and

25.6

mm (dynamic) for AoI equal to

\pm 60^{\circ}

. In addition, the wearable platform was used during a preliminary experiment for the estimation of the inter-foot distance on a single healthy subject while walking. In conclusion, the combination of magneto-inertial unit and IR-ToF technology represents a valuable alternative solution in terms of accuracy, sampling frequency, dimension and power consumption, compared to existing technologies. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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23 pages, 6867 KiB

Open AccessArticle

A Spaceborne Synthetic Aperture Radar Partial Fixed-Point Imaging System Using a Field- Programmable Gate Array−Application-Specific Integrated Circuit Hybrid Heterogeneous Parallel Acceleration Technique

by Chen Yang

, Bingyi Li, Liang Chen^*, Chunpeng Wei, Yizhuang Xie, He Chen and Wenyue Yu

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

Sensors 2017, 17(7), 1493; https://doi.org/10.3390/s17071493 - 24 Jun 2017

Cited by 32 | Viewed by 7201

Abstract

With the development of satellite load technology and very large scale integrated (VLSI) circuit technology, onboard real-time synthetic aperture radar (SAR) imaging systems have become a solution for allowing rapid response to disasters. A key goal of the onboard SAR imaging system design [...] Read more.

With the development of satellite load technology and very large scale integrated (VLSI) circuit technology, onboard real-time synthetic aperture radar (SAR) imaging systems have become a solution for allowing rapid response to disasters. A key goal of the onboard SAR imaging system design is to achieve high real-time processing performance with severe size, weight, and power consumption constraints. In this paper, we analyse the computational burden of the commonly used chirp scaling (CS) SAR imaging algorithm. To reduce the system hardware cost, we propose a partial fixed-point processing scheme. The fast Fourier transform (FFT), which is the most computation-sensitive operation in the CS algorithm, is processed with fixed-point, while other operations are processed with single precision floating-point. With the proposed fixed-point processing error propagation model, the fixed-point processing word length is determined. The fidelity and accuracy relative to conventional ground-based software processors is verified by evaluating both the point target imaging quality and the actual scene imaging quality. As a proof of concept, a field- programmable gate array−application-specific integrated circuit (FPGA-ASIC) hybrid heterogeneous parallel accelerating architecture is designed and realized. The customized fixed-point FFT is implemented using the 130 nm complementary metal oxide semiconductor (CMOS) technology as a co-processor of the Xilinx xc6vlx760t FPGA. A single processing board requires 12 s and consumes 21 W to focus a 50-km swath width, 5-m resolution stripmap SAR raw data with a granularity of 16,384 × 16,384. Full article

(This article belongs to the Section Remote Sensors)

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8 pages, 3458 KiB

Open AccessArticle

Tunable Fano Resonance in Asymmetric MIM Waveguide Structure

by Xuefeng Zhao, Zhidong Zhang^*

and Shubin Yan^*

Science and Technology on Electronic Test and Measurement Laboratory, North University of China, No. 3 Xueyuan Road, Taiyuan 030051, China

Sensors 2017, 17(7), 1494; https://doi.org/10.3390/s17071494 - 25 Jun 2017

Cited by 88 | Viewed by 8291

Abstract

A plasmonic waveguide coupled system that uses a metal-insulator-metal (MIM) waveguide with two silver baffles and a coupled ring cavity is proposed in this study. The transmission properties of the plasmonic system were investigated using the finite element method. The simulation results show [...] Read more.

A plasmonic waveguide coupled system that uses a metal-insulator-metal (MIM) waveguide with two silver baffles and a coupled ring cavity is proposed in this study. The transmission properties of the plasmonic system were investigated using the finite element method. The simulation results show a Fano profile in the transmission spectrum, which was caused by the interaction of the broadband resonance of the Fabry-Perot (F-P) cavity and the narrow band resonance of the ring cavity. The Fabry-Perot (F-P) cavity in this case was formed by two silver baffles dividing the MIM waveguide. The maximum sensitivity of 718 nm/RIU and the maximum figure of merit of 4354 were achieved. Furthermore, the effects of the structural parameters of the F-P cavity and the ring cavity on the transmission properties of the plasmonic system were analyzed. The results can provide a guide for designing highly sensitive on-chip sensors based on surface plasmon polaritons. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1200 KiB

Open AccessArticle

A Novel Range Compression Algorithm for Resolution Enhancement in GNSS-SARs

by Yu Zheng^*, Yang Yang and Wu Chen

Department of Land Surveying and Geo-informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Sensors 2017, 17(7), 1496; https://doi.org/10.3390/s17071496 - 25 Jun 2017

Cited by 14 | Viewed by 5903

Abstract

In this paper, a novel range compression algorithm for enhancing range resolutions of a passive Global Navigation Satellite System-based Synthetic Aperture Radar (GNSS-SAR) is proposed. In the proposed algorithm, within each azimuth bin, firstly range compression is carried out by correlating a reflected [...] Read more.

In this paper, a novel range compression algorithm for enhancing range resolutions of a passive Global Navigation Satellite System-based Synthetic Aperture Radar (GNSS-SAR) is proposed. In the proposed algorithm, within each azimuth bin, firstly range compression is carried out by correlating a reflected GNSS intermediate frequency (IF) signal with a synchronized direct GNSS base-band signal in the range domain. Thereafter, spectrum equalization is applied to the compressed results for suppressing side lobes to obtain a final range-compressed signal. Both theoretical analysis and simulation results have demonstrated that significant range resolution improvement in GNSS-SAR images can be achieved by the proposed range compression algorithm, compared to the conventional range compression algorithm. Full article

(This article belongs to the Section Remote Sensors)

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9 pages, 3534 KiB

Open AccessArticle

A Multi-Resolution Mode CMOS Image Sensor with a Novel Two-Step Single-Slope ADC for Intelligent Surveillance Systems

by Daehyeok Kim¹, Minkyu Song¹, Byeongseong Choe² and Soo Youn Kim^1,*

¹ Department of Semiconductor Science, Dongguk University-Seoul, Seoul 04620, Korea

² Department of Information and Telecommunication Engineering, Dongguk University-Seoul, Seoul 04620, Korea

Sensors 2017, 17(7), 1497; https://doi.org/10.3390/s17071497 - 25 Jun 2017

Cited by 17 | Viewed by 8631

Abstract

In this paper, we present a multi-resolution mode CMOS image sensor (CIS) for intelligent surveillance system (ISS) applications. A low column fixed-pattern noise (CFPN) comparator is proposed in 8-bit two-step single-slope analog-to-digital converter (TSSS ADC) for the CIS that supports normal, 1/2, 1/4, [...] Read more.

In this paper, we present a multi-resolution mode CMOS image sensor (CIS) for intelligent surveillance system (ISS) applications. A low column fixed-pattern noise (CFPN) comparator is proposed in 8-bit two-step single-slope analog-to-digital converter (TSSS ADC) for the CIS that supports normal, 1/2, 1/4, 1/8, 1/16, 1/32, and 1/64 mode of pixel resolution. We show that the scaled-resolution images enable CIS to reduce total power consumption while images hold steady without events. A prototype sensor of 176 × 144 pixels has been fabricated with a 0.18 μm 1-poly 4-metal CMOS process. The area of 4-shared 4T-active pixel sensor (APS) is 4.4 μm × 4.4 μm and the total chip size is 2.35 mm × 2.35 mm. The maximum power consumption is 10 mW (with full resolution) with supply voltages of 3.3 V (analog) and 1.8 V (digital) and 14 frame/s of frame rates. Full article

(This article belongs to the Special Issue Image Sensors)

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22 pages, 883 KiB

Open AccessArticle

Energy Efficiency Optimization for Downlink Cloud RAN with Limited Fronthaul Capacity

by Yong Wang

, Lin Ma and Yubin Xu^*

School of Electronics and Information Engineering, Harbin Institute of Technology, Harbin 150080, China

Sensors 2017, 17(7), 1498; https://doi.org/10.3390/s17071498 - 26 Jun 2017

Cited by 1 | Viewed by 4082

Abstract

In the downlink cloud radio access network (C-RAN), fronthaul compression has been developed to combat the performance bottleneck caused by the capacity-limited fronthaul links. Nevertheless, the state-of-arts focusing on fronthaul compression for spectral efficiency improvement become questionable for energy efficiency (EE) maximization, especially [...] Read more.

In the downlink cloud radio access network (C-RAN), fronthaul compression has been developed to combat the performance bottleneck caused by the capacity-limited fronthaul links. Nevertheless, the state-of-arts focusing on fronthaul compression for spectral efficiency improvement become questionable for energy efficiency (EE) maximization, especially for meeting its requirements of large-scale implementation. Therefore, this paper aims to develop a low-complexity algorithm with closed-form solution for the EE maximization problem in a downlink C-RAN with limited fronthaul capacity. To solve such a non-trivial problem, we first derive an optimal solution using branch-and-bound approach to provide a performance benchmark. Then, by transforming the original problem into a parametric subtractive form, we propose a low-complexity two-layer decentralized (TLD) algorithm. Specifically, a bisection search is involved in the outer layer, while in the inner layer we propose an alternating direction method of multipliers algorithm to find a closed-form solution in a parallel manner with convergence guaranteed. Simulations results demonstrate that the TLD algorithm can achieve near optimal solution, and its EE is much higher than the spectral efficiency maximization one. Furthermore, the optimal and TLD algorithms are also extended to counter the channel error. The results show that the robust algorithms can provide robust performance in the case of lacking perfect channel state information. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 9638 KiB

Open AccessArticle

Vicarious Calibration of sUAS Microbolometer Temperature Imagery for Estimation of Radiometric Land Surface Temperature

by Alfonso Torres-Rua

Utah Water Research Laboratory, Utah State University, Logan, UT 84322, USA

Sensors 2017, 17(7), 1499; https://doi.org/10.3390/s17071499 - 26 Jun 2017

Cited by 55 | Viewed by 8246

Abstract

In recent years, the availability of lightweight microbolometer thermal cameras compatible with small unmanned aerial systems (sUAS) has allowed their use in diverse scientific and management activities that require sub-meter pixel resolution. Nevertheless, as with sensors already used in temperature remote sensing (e.g., [...] Read more.

In recent years, the availability of lightweight microbolometer thermal cameras compatible with small unmanned aerial systems (sUAS) has allowed their use in diverse scientific and management activities that require sub-meter pixel resolution. Nevertheless, as with sensors already used in temperature remote sensing (e.g., Landsat satellites), a radiance atmospheric correction is necessary to estimate land surface temperature. This is because atmospheric conditions at any sUAS flight elevation will have an adverse impact on the image accuracy, derived calculations, and study replicability using the microbolometer technology. This study presents a vicarious calibration methodology (sUAS-specific, time-specific, flight-specific, and sensor-specific) for sUAS temperature imagery traceable back to NIST-standards and current atmospheric correction methods. For this methodology, a three-year data collection campaign with a sUAS called “AggieAir”, developed at Utah State University, was performed for vineyards near Lodi, California, for flights conducted at different times (early morning, Landsat overpass, and mid-afternoon”) and seasonal conditions. From the results of this study, it was found that, despite the spectral response of microbolometer cameras (7.0 to 14.0 μm), it was possible to account for the effects of atmospheric and sUAS operational conditions, regardless of time and weather, to acquire accurate surface temperature data. In addition, it was found that the main atmospheric correction parameters (transmissivity and atmospheric radiance) significantly varied over the course of a day. These parameters fluctuated the most in early morning and partially stabilized in Landsat overpass and in mid-afternoon times. In terms of accuracy, estimated atmospheric correction parameters presented adequate statistics (confidence bounds under ±0.1 for transmissivity and ±1.2 W/m²/sr/um for atmospheric radiance, with a range of RMSE below 1.0 W/m²/sr/um) for all sUAS flights. Differences in estimated temperatures between original thermal image and the vicarious calibration procedure reported here were estimated from −5 °C to 10 °C for early morning, and from 0 to 20 °C for Landsat overpass and mid-afternoon times. Full article

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

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22 pages, 23105 KiB

Open AccessArticle

SLAE–CPS: Smart Lean Automation Engine Enabled by Cyber-Physical Systems Technologies

by Jing Ma¹, Qiang Wang^1,* and Zhibiao Zhao²

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

² China Norinco Group Planning and Research Institute, Beijing 100053, China

Sensors 2017, 17(7), 1500; https://doi.org/10.3390/s17071500 - 28 Jun 2017

Cited by 92 | Viewed by 12512

Abstract

In the context of Industry 4.0, the demand for the mass production of highly customized products will lead to complex products and an increasing demand for production system flexibility. Simply implementing lean production-based human-centered production or high automation to improve system flexibility is [...] Read more.

In the context of Industry 4.0, the demand for the mass production of highly customized products will lead to complex products and an increasing demand for production system flexibility. Simply implementing lean production-based human-centered production or high automation to improve system flexibility is insufficient. Currently, lean automation (Jidoka) that utilizes cyber-physical systems (CPS) is considered a cost-efficient and effective approach for improving system flexibility under shrinking global economic conditions. Therefore, a smart lean automation engine enabled by CPS technologies (SLAE–CPS), which is based on an analysis of Jidoka functions and the smart capacity of CPS technologies, is proposed in this study to provide an integrated and standardized approach to design and implement a CPS-based smart Jidoka system. A set of comprehensive architecture and standardized key technologies should be presented to achieve the above-mentioned goal. Therefore, a distributed architecture that joins service-oriented architecture, agent, function block (FB), cloud, and Internet of things is proposed to support the flexible configuration, deployment, and performance of SLAE–CPS. Then, several standardized key techniques are proposed under this architecture. The first one is for converting heterogeneous physical data into uniform services for subsequent abnormality analysis and detection. The second one is a set of Jidoka scene rules, which is abstracted based on the analysis of the operator, machine, material, quality, and other factors in different time dimensions. These Jidoka rules can support executive FBs in performing different Jidoka functions. Finally, supported by the integrated and standardized approach of our proposed engine, a case study is conducted to verify the current research results. The proposed SLAE–CPS can serve as an important reference value for combining the benefits of innovative technology and proper methodology. Full article

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

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16 pages, 4360 KiB

Open AccessArticle

Spatiotemporal Recurrent Convolutional Networks for Traffic Prediction in Transportation Networks

by Haiyang Yu¹, Zhihai Wu¹, Shuqin Wang², Yunpeng Wang¹ and Xiaolei Ma^1,*

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

² Passenger Vehicle EE Development Department, China FAW R&D Center, Changchun 130011, China

Sensors 2017, 17(7), 1501; https://doi.org/10.3390/s17071501 - 26 Jun 2017

Cited by 534 | Viewed by 16097

Abstract

Predicting large-scale transportation network traffic has become an important and challenging topic in recent decades. Inspired by the domain knowledge of motion prediction, in which the future motion of an object can be predicted based on previous scenes, we propose a network grid [...] Read more.

Predicting large-scale transportation network traffic has become an important and challenging topic in recent decades. Inspired by the domain knowledge of motion prediction, in which the future motion of an object can be predicted based on previous scenes, we propose a network grid representation method that can retain the fine-scale structure of a transportation network. Network-wide traffic speeds are converted into a series of static images and input into a novel deep architecture, namely, spatiotemporal recurrent convolutional networks (SRCNs), for traffic forecasting. The proposed SRCNs inherit the advantages of deep convolutional neural networks (DCNNs) and long short-term memory (LSTM) neural networks. The spatial dependencies of network-wide traffic can be captured by DCNNs, and the temporal dynamics can be learned by LSTMs. An experiment on a Beijing transportation network with 278 links demonstrates that SRCNs outperform other deep learning-based algorithms in both short-term and long-term traffic prediction. Full article

(This article belongs to the Section Sensor Networks)

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15 pages, 2103 KiB

Open AccessArticle

Statistical Analysis of the Main Configuration Parameters of the Network Dynamic and Adaptive Radio Protocol (DARP)

by Francisco José Estevez^1,2,*, Jesús González²

, Peter Glösekötter¹

, Olga Valenzuela^3,* and Ignacio Rojas²

¹ Department of Electrical Engineering and Computer Science, University of Applied Sciences of Münster, Stegerweldstr. 39, 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 Applied Mathematics, University of Granada, Campus Fuentenueva, S/N, 18071 Granada, Spain

Sensors 2017, 17(7), 1502; https://doi.org/10.3390/s17071502 - 26 Jun 2017

Cited by 1 | Viewed by 3855

Abstract

The present work analyses the wireless sensor network protocol (DARP) and the impact of different configuration parameter sets on its performance. Different scenarios have been considered, in order to gain a better understanding of the influence of the configuration on network protocols. The [...] Read more.

The present work analyses the wireless sensor network protocol (DARP) and the impact of different configuration parameter sets on its performance. Different scenarios have been considered, in order to gain a better understanding of the influence of the configuration on network protocols. The developed statistical analysis is based on the method known as Analysis of Variance (ANOVA), which focuses on the effect of the configuration on the performance of DARP. Three main dependent variables were considered: number of control messages sent during the set-up time, energy consumption and convergence time. A total of 20,413 simulations were carried out to ensure greater robustness in the statistical conclusions. The main goal of this work is to discover the most critical configuration parameters for the protocol, with a view to potential applications in Smart City type scenarios. Full article

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

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11 pages, 4187 KiB

Open AccessArticle

Temperature Dependence of the Rayleigh Brillouin Spectrum Linewidth in Air and Nitrogen

by Kun Liang^1,2,3, Jiaqi Xu¹, Peng Zhang¹, Yuanqing Wang³, Qunjie Niu¹, Li Peng¹ and Bo Zhou^1,2,*

¹ School of Electronic Information and Communications, Huazhong University of Science and Technology, Wuhan 430074, China

² Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China

³ Laser Centre, Vrije Universiteit (VU), De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands

Sensors 2017, 17(7), 1503; https://doi.org/10.3390/s17071503 - 26 Jun 2017

Cited by 15 | Viewed by 5306

Abstract

The relation between spontaneous Rayleigh Brillouin (SRB) spectrum linewidth, gas temperature, and pressure are analyzed at the temperature range from 220 to 340 K and the pressure range from 0.1 to 1 bar, covering the stratosphere and troposphere relevant for the Earth’s atmosphere [...] Read more.

The relation between spontaneous Rayleigh Brillouin (SRB) spectrum linewidth, gas temperature, and pressure are analyzed at the temperature range from 220 to 340 K and the pressure range from 0.1 to 1 bar, covering the stratosphere and troposphere relevant for the Earth’s atmosphere and for atmospheric Lidar missions. Based on the analysis, a model retrieving gas temperature from directly measured linewidth is established and the accuracy limitations are estimated. Furthermore, some experimental data of air and nitrogen are used to verify the accuracy of the model. As the results show, the retrieved temperature shows good agreement with the reference temperature, and the absolute difference is less than 3 K, which indicates that this method provides a fruitful tool in satellite retrieval to extract the gaseous properties of atmospheres on-line by directly measuring the SRB spectrum linewidth. Full article

(This article belongs to the Special Issue Understanding Land Surface Processes and Ecosystem Changes with Optical and Laser Remote Sensing)

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21 pages, 3182 KiB

Open AccessArticle

Novel Hybrid Scheduling Technique for Sensor Nodes with Mixed Criticality Tasks

by Mihai-Victor Micea¹, Cristina-Sorina Stangaciu¹

, Valentin Stangaciu¹

and Daniel-Ioan Curiac^2,*

¹ Department of Computers and Information Technology, Politehnica University of Timisoara, V. Parvan No. 2, Timisoara 300223, Romania

² Department of Automation and Applied Informatics, Politehnica University of Timisoara, V. Parvan No. 2, Timisoara 300223, Romania

Sensors 2017, 17(7), 1504; https://doi.org/10.3390/s17071504 - 26 Jun 2017

Cited by 4 | Viewed by 5208

Abstract

Sensor networks become increasingly a key technology for complex control applications. Their potential use in safety- and time-critical domains has raised the need for task scheduling mechanisms specially adapted to sensor node specific requirements, often materialized in predictable jitter-less execution of tasks characterized [...] Read more.

Sensor networks become increasingly a key technology for complex control applications. Their potential use in safety- and time-critical domains has raised the need for task scheduling mechanisms specially adapted to sensor node specific requirements, often materialized in predictable jitter-less execution of tasks characterized by different criticality levels. This paper offers an efficient scheduling solution, named Hybrid Hard Real-Time Scheduling (H²RTS), which combines a static, clock driven method with a dynamic, event driven scheduling technique, in order to provide high execution predictability, while keeping a high node Central Processing Unit (CPU) utilization factor. From the detailed, integrated schedulability analysis of the H²RTS, a set of sufficiency tests are introduced and demonstrated based on the processor demand and linear upper bound metrics. The performance and correct behavior of the proposed hybrid scheduling technique have been extensively evaluated and validated both on a simulator and on a sensor mote equipped with ARM7 microcontroller. Full article

(This article belongs to the Section Sensor Networks)

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20 pages, 4509 KiB

Open AccessArticle

Development of a Computer Writing System Based on EOG

by Alberto López¹, Francisco Ferrero^1,*, David Yangüela¹, Constantina Álvarez¹ and Octavian Postolache²

¹ Departamento de Ingeniería Eléctrica, Electrónica, Computadores y Sistemas, Universidad de Oviedo, Campus of Gijón, 33204 Gijón, Spain

² Instituto de Telecomunicações, ISCTE-IUL, Av. Rovisco Pais, 1, 1049–001 Lisboa, Portugal

Sensors 2017, 17(7), 1505; https://doi.org/10.3390/s17071505 - 26 Jun 2017

Cited by 28 | Viewed by 9578

Abstract

The development of a novel computer writing system based on eye movements is introduced herein. A system of these characteristics requires the consideration of three subsystems: (1) A hardware device for the acquisition and transmission of the signals generated by eye movement to [...] Read more.

The development of a novel computer writing system based on eye movements is introduced herein. A system of these characteristics requires the consideration of three subsystems: (1) A hardware device for the acquisition and transmission of the signals generated by eye movement to the computer; (2) A software application that allows, among other functions, data processing in order to minimize noise and classify signals; and (3) A graphical interface that allows the user to write text easily on the computer screen using eye movements only. This work analyzes these three subsystems and proposes innovative and low cost solutions for each one of them. This computer writing system was tested with 20 users and its efficiency was compared to a traditional virtual keyboard. The results have shown an important reduction in the time spent on writing, which can be very useful, especially for people with severe motor disorders. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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16 pages, 1282 KiB

Open AccessArticle

Tuning the Sensitivity of the PDR5 Promoter-Based Detection of Diclofenac in Yeast Biosensors

by Astrid Schuller, Gerhard Rödel and Kai Ostermann^*

Institute of Genetics, Technische Universität Dresden, 01062 Dresden, Germany

Sensors 2017, 17(7), 1506; https://doi.org/10.3390/s17071506 - 26 Jun 2017

Cited by 8 | Viewed by 4657

Abstract

The commonly used drug diclofenac is an important environmental anthropogenic pollutant. Currently, detection of diclofenac is mainly based on chemical and physical methods. Here we describe a yeast biosensor that drives the diclofenac-dependent expression of a recombinant fluorescent protein from the authentic promoter [...] Read more.

The commonly used drug diclofenac is an important environmental anthropogenic pollutant. Currently, detection of diclofenac is mainly based on chemical and physical methods. Here we describe a yeast biosensor that drives the diclofenac-dependent expression of a recombinant fluorescent protein from the authentic promoter of the PDR5 gene. This key component of the pleiotropic drug response encodes a multidrug transporter that is involved in cellular detoxification. We analyse the effects on diclofenac sensitivity of artificial PDR5 promoter derivatives in wild-type and various yeast mutant strains. This approach enabled us to generate sensor strains with elevated drug sensitivity. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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12 pages, 4558 KiB

Open AccessArticle

Novel Gas Sensor Arrays Based on High-Q SAM-Modified Piezotransduced Single-Crystal Silicon Bulk Acoustic Resonators

by Yuan Zhao^†, Qingrui Yang^†, Ye Chang, Wei Pang, Hao Zhang and Xuexin Duan^*

¹ State Key Laboratory of Precision Measuring Technology & Instruments, Tianjin University, Tianjin 300072, China

^† The authors contributed equally to this work.

Sensors 2017, 17(7), 1507; https://doi.org/10.3390/s17071507 - 26 Jun 2017

Cited by 5 | Viewed by 7228

Abstract

This paper demonstrates a novel micro-size (120 μm × 200 μm) piezoelectric gas sensor based on a piezotransduced single-crystal silicon bulk acoustic resonator (PSBAR). The PSBARs operate at 102 MHz and possess high Q values (about 2000), ensuring the stability of the measurement. [...] Read more.

This paper demonstrates a novel micro-size (120 μm × 200 μm) piezoelectric gas sensor based on a piezotransduced single-crystal silicon bulk acoustic resonator (PSBAR). The PSBARs operate at 102 MHz and possess high Q values (about 2000), ensuring the stability of the measurement. A corresponding gas sensor array is fabricated by integrating three different self-assembled monolayers (SAMs) modified PSBARs. The limit of detection (LOD) for ethanol vapor is demonstrated to be as low as 25 ppm with a sensitivity of about 1.5 Hz/ppm. Two sets of identification code bars based on the sensitivities and the adsorption energy constants are utilized to successfully discriminate isopropanol (IPA), ethanol, hexane and heptane vapors at low and high gas partial pressures, respectively. The proposed sensor array shows the potential to form a portable electronic nose system for volatile organic compound (VOC) differentiation. Full article

(This article belongs to the Special Issue Acoustic Wave Resonator-Based Sensors)

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16 pages, 4221 KiB

Open AccessArticle

Does RAIM with Correct Exclusion Produce Unbiased Positions?

by Peter J. G. Teunissen^1,2,*, Davide Imparato¹ and Christian C. J. M. Tiberius²

¹ GNSS Research Centre, Curtin University of Technology, 6845 Perth, Australia

² Department of Geoscience and Remote Sensing, Delft University of Technology, 2628 CN Delft, The Netherlands

Sensors 2017, 17(7), 1508; https://doi.org/10.3390/s17071508 - 26 Jun 2017

Cited by 19 | Viewed by 4403

Abstract

As the navigation solution of exclusion-based RAIM follows from a combination of least-squares estimation and a statistically based exclusion-process, the computation of the integrity of the navigation solution has to take the propagated uncertainty of the combined estimation-testing procedure into account. In this [...] Read more.

As the navigation solution of exclusion-based RAIM follows from a combination of least-squares estimation and a statistically based exclusion-process, the computation of the integrity of the navigation solution has to take the propagated uncertainty of the combined estimation-testing procedure into account. In this contribution, we analyse, theoretically as well as empirically, the effect that this combination has on the first statistical moment, i.e., the mean, of the computed navigation solution. It will be shown, although statistical testing is intended to remove biases from the data, that biases will always remain under the alternative hypothesis, even when the correct alternative hypothesis is properly identified. The a posteriori exclusion of a biased satellite range from the position solution will therefore never remove the bias in the position solution completely. Full article

(This article belongs to the Section Remote Sensors)

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10 pages, 7400 KiB

Open AccessArticle

Ultra-Weak Fiber Bragg Grating Sensing Network Coated with Sensitive Material for Multi-Parameter Measurements

by Wei Bai¹, Minghong Yang^1,2,*, Chenyuan Hu^1,*, Jixiang Dai¹, Xuexiang Zhong¹, Shuai Huang¹ and Gaopeng Wang¹

¹ National Engineering Laboratory for Fiber Optic Sensing Technologies, Wuhan University of Technology, Wuhan 430070, China

² Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan, 430070, China

Sensors 2017, 17(7), 1509; https://doi.org/10.3390/s17071509 - 26 Jun 2017

Cited by 18 | Viewed by 5702

Abstract

A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG) array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the [...] Read more.

A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG) array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the performance of the proposed UFBG system is almost equal to that of traditional FBG, while the UFBG array system has obvious superiority with potential multiplexing ability for multi-point and multi-parameter measurement. The system experimented on a 144 UFBG array with the reflectivity of UFBG ~0.04% for the four target parameters: hydrogen, humidity, temperature and salinity. Moreover, a uniform solution was customized to divide the cross-sensitivity between temperature and other target parameters. It is expected that this scheme will be capable of handling thousands of multi-parameter sensors in a single fiber. Full article

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

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11 pages, 6193 KiB

Open AccessArticle

Research on a Novel Exciting Method for a Sandwich Transducer Operating in Longitudinal-Bending Hybrid Modes

by Yingxiang Liu^*

, Qiangqiang Shen, Shengjun Shi, Jie Deng, Weishan Chen and Liang Wang

State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China

Sensors 2017, 17(7), 1510; https://doi.org/10.3390/s17071510 - 27 Jun 2017

Cited by 6 | Viewed by 6260

Abstract

A novel exciting method for a sandwich type piezoelectric transducer operating in longitudinal-bending hybrid vibration modes is proposed and discussed, in which the piezoelectric elements for the excitations of the longitudinal and bending vibrations share the same axial location, but correspond to different [...] Read more.

A novel exciting method for a sandwich type piezoelectric transducer operating in longitudinal-bending hybrid vibration modes is proposed and discussed, in which the piezoelectric elements for the excitations of the longitudinal and bending vibrations share the same axial location, but correspond to different partitions. Whole-piece type piezoelectric plates with three separated partitions are used, in which the center partitions generate the first longitudinal vibration, while the upper and lower partitions produce the second bending vibration. Detailed comparisons between the proposed exciting method and the traditional one were accomplished by finite element method (FEM) calculations, which were further verified by experiments. Compared with the traditional exciting method using independent longitudinal ceramics and bending ceramics, the proposed method achieves higher electromechanical coupling factors and larger vibration amplitudes, especially for the bending vibration mode. This novel exciting method for longitudinal-bending hybrid vibrations has not changed the structural dimensions of the sandwich transducer, but markedly improves the mechanical output ability, which makes it very helpful and meaningful in designing new piezoelectric actuators operated in longitudinal-bending hybrid vibration modes. Full article

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

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11 pages, 4630 KiB

Open AccessArticle

Flexible Packaging by Film-Assisted Molding for Microintegration of Inertia Sensors

by Daniel Hera^1,*, Armin Berndt², Thomas Günther¹, Stephan Schmiel², Christine Harendt² and André Zimmermann^1,3

¹ Institute for Micro Assembly Technology, Hahn-Schickard e. V, Allmandring 9B, 70569 Stuttgart, Germany

² Institut für Mikroelektronik Stuttgart, Allmandring 30a, 70569 Stuttgart, Germany

³ Institute for Micro Integration (IFM), University of Stuttgart, Allmandring 9B, 70569 Stuttgart, Germany

Sensors 2017, 17(7), 1511; https://doi.org/10.3390/s17071511 - 27 Jun 2017

Cited by 4 | Viewed by 7318

Abstract

Packaging represents an important part in the microintegration of sensors based on microelectromechanical system (MEMS). Besides miniaturization and integration density, functionality and reliability in combination with flexibility in packaging design at moderate costs and consequently high-mix, low-volume production are the main requirements for [...] Read more.

Packaging represents an important part in the microintegration of sensors based on microelectromechanical system (MEMS). Besides miniaturization and integration density, functionality and reliability in combination with flexibility in packaging design at moderate costs and consequently high-mix, low-volume production are the main requirements for future solutions in packaging. This study investigates possibilities employing printed circuit board (PCB-)based assemblies to provide high flexibility for circuit designs together with film-assisted transfer molding (FAM) to package sensors. The feasibility of FAM in combination with PCB and MEMS as a packaging technology for highly sensitive inertia sensors is being demonstrated. The results prove the technology to be a viable method for damage-free packaging of stress- and pressure-sensitive MEMS. Full article

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

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26 pages, 13048 KiB

Open AccessArticle

Integration of Sensors, Controllers and Instruments Using a Novel OPC Architecture

by Isaías González^1,*

, Antonio José Calderón¹

, Antonio Javier Barragán²

and José Manuel Andújar²

¹ Department of Electrical Engineering, Electronics and Automation, University of Extremadura, Avenida de Elvas, s/n, 06006 Badajoz, Spain

² Department of Electronic, Computer Science and Automatic Engineering, University of Huelva, Escuela Técnica Superior, Crta. Huelva-Palos de la Fra, Palos de la Fra, 21919 Huelva, Spain

Sensors 2017, 17(7), 1512; https://doi.org/10.3390/s17071512 - 27 Jun 2017

Cited by 41 | Viewed by 12182

Abstract

The interconnection between sensors, controllers and instruments through a communication network plays a vital role in the performance and effectiveness of a control system. Since its inception in the 90s, the Object Linking and Embedding for Process Control (OPC) protocol has provided open [...] Read more.

The interconnection between sensors, controllers and instruments through a communication network plays a vital role in the performance and effectiveness of a control system. Since its inception in the 90s, the Object Linking and Embedding for Process Control (OPC) protocol has provided open connectivity for monitoring and automation systems. It has been widely used in several environments such as industrial facilities, building and energy automation, engineering education and many others. This paper presents a novel OPC-based architecture to implement automation systems devoted to R&D and educational activities. The proposal is a novel conceptual framework, structured into four functional layers where the diverse components are categorized aiming to foster the systematic design and implementation of automation systems involving OPC communication. Due to the benefits of OPC, the proposed architecture provides features like open connectivity, reliability, scalability, and flexibility. Furthermore, four successful experimental applications of such an architecture, developed at the University of Extremadura (UEX), are reported. These cases are a proof of concept of the ability of this architecture to support interoperability for different domains. Namely, the automation of energy systems like a smart microgrid and photobioreactor facilities, the implementation of a network-accessible industrial laboratory and the development of an educational hardware-in-the-loop platform are described. All cases include a Programmable Logic Controller (PLC) to automate and control the plant behavior, which exchanges operative data (measurements and signals) with a multiplicity of sensors, instruments and supervisory systems under the structure of the novel OPC architecture. Finally, the main conclusions and open research directions are highlighted. Full article

(This article belongs to the Section Sensor Networks)

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28 pages, 1869 KiB

Open AccessArticle

Analysis of Public Datasets for Wearable Fall Detection Systems

by Eduardo Casilari^*

, José-Antonio Santoyo-Ramón and José-Manuel Cano-García

Departamento de Tecnología Electrónica, Universidad de Málaga, ETSI Telecomunicación, 29071 Málaga, Spain

Sensors 2017, 17(7), 1513; https://doi.org/10.3390/s17071513 - 27 Jun 2017

Cited by 122 | Viewed by 15025

Abstract

Due to the boom of wireless handheld devices such as smartwatches and smartphones, wearable Fall Detection Systems (FDSs) have become a major focus of attention among the research community during the last years. The effectiveness of a wearable FDS must be contrasted against [...] Read more.

Due to the boom of wireless handheld devices such as smartwatches and smartphones, wearable Fall Detection Systems (FDSs) have become a major focus of attention among the research community during the last years. The effectiveness of a wearable FDS must be contrasted against a wide variety of measurements obtained from inertial sensors during the occurrence of falls and Activities of Daily Living (ADLs). In this regard, the access to public databases constitutes the basis for an open and systematic assessment of fall detection techniques. This paper reviews and appraises twelve existing available data repositories containing measurements of ADLs and emulated falls envisaged for the evaluation of fall detection algorithms in wearable FDSs. The analysis of the found datasets is performed in a comprehensive way, taking into account the multiple factors involved in the definition of the testbeds deployed for the generation of the mobility samples. The study of the traces brings to light the lack of a common experimental benchmarking procedure and, consequently, the large heterogeneity of the datasets from a number of perspectives (length and number of samples, typology of the emulated falls and ADLs, characteristics of the test subjects, features and positions of the sensors, etc.). Concerning this, the statistical analysis of the samples reveals the impact of the sensor range on the reliability of the traces. In addition, the study evidences the importance of the selection of the ADLs and the need of categorizing the ADLs depending on the intensity of the movements in order to evaluate the capability of a certain detection algorithm to discriminate falls from ADLs. Full article

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

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29 pages, 12931 KiB

Open AccessArticle

A Force-Sensing System on Legs for Biomimetic Hexapod Robots Interacting with Unstructured Terrain

by He Zhang^*

, Rui Wu^*, Changle Li^*, Xizhe Zang, Xuehe Zhang

, Hongzhe Jin and Jie Zhao

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

Sensors 2017, 17(7), 1514; https://doi.org/10.3390/s17071514 - 27 Jun 2017

Cited by 21 | Viewed by 12493

Abstract

The tiger beetle can maintain its stability by controlling the interaction force between its legs and an unstructured terrain while it runs. The biomimetic hexapod robot mimics a tiger beetle, and a comprehensive force sensing system combined with certain algorithms can provide force [...] Read more.

The tiger beetle can maintain its stability by controlling the interaction force between its legs and an unstructured terrain while it runs. The biomimetic hexapod robot mimics a tiger beetle, and a comprehensive force sensing system combined with certain algorithms can provide force information that can help the robot understand the unstructured terrain that it interacts with. This study introduces a complicated leg force sensing system for a hexapod robot that is the same for all six legs. First, the layout and configuration of sensing system are designed according to the structure and sizes of legs. Second, the joint toque sensors, 3-DOF foot-end force sensor and force information processing module are designed, and the force sensor performance parameters are tested by simulations and experiments. Moreover, a force sensing system is implemented within the robot control architecture. Finally, the experimental evaluation of the leg force sensor system on the hexapod robot is discussed and the performance of the leg force sensor system is verified. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 531 KiB

Open AccessArticle

Exploitation of SPR to Investigate the Importance of Glycan Chains in the Interaction between Lactoferrin and Bacteria

by Noelle O’Riordan^1,2, Michelle Kilcoyne²

, Lokesh Joshi² and Rita M. Hickey^1,*

¹ Biosciences Department, Teagasc Food Research Centre, Moorepark, Fermoy, P61C996 Co. Cork, Ireland

² Glycoscience Group, National Centre for Biomedical Engineering Science, National University of Ireland Galway, H91TK33, Galway, Ireland

Sensors 2017, 17(7), 1515; https://doi.org/10.3390/s17071515 - 27 Jun 2017

Cited by 3 | Viewed by 4570

Abstract

Bovine lactoferrin (LF) has been shown to prevent adhesion to and invasion of mammalian cell lines by pathogenic bacteria, with evidence for direct bacterial binding by the milk glycoprotein. However, the glycosylation pattern of LF changes over the lactation cycle. In this study, [...] Read more.

Bovine lactoferrin (LF) has been shown to prevent adhesion to and invasion of mammalian cell lines by pathogenic bacteria, with evidence for direct bacterial binding by the milk glycoprotein. However, the glycosylation pattern of LF changes over the lactation cycle. In this study, we aim to investigate the effect that this variation has on the milk glycoprotein’s ability to interact with pathogens. Surface plasmon resonance technology was employed to compare the binding of LF from colostrum (early lactation) and mature milk (late lactation) to a panel of pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Cronobacter sakazakii, Streptococcus pneumoniae, Pseudomonas aeruginosa, Listeria monocytogenes and Salmonella typhimurium). Novel interactions with LF were identified for C. sakazakii, S. pneumoniae and P. aeruginosa with the highest binding ability observed for mature milk LF in all cases, with the exception of S. typhimurium. The difference in bacterial binding observed may be as a result of the varying glycosylation profiles. This work demonstrates the potential of LF as a functional food ingredient to prevent bacterial infection. Full article

(This article belongs to the Special Issue Sensors for Glycoproteins and Glycated Proteins)

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12 pages, 3948 KiB

Open AccessArticle

Experimental Demonstration of Long-Range Underwater Acoustic Communication Using a Vertical Sensor Array

by Anbang Zhao^1,2,3, Caigao Zeng^1,2, Juan Hui^1,2,*, Lin Ma^1,2 and Xuejie Bi^1,2

¹ Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China

² College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China

³ National Key Laboratory of Science and Technology on Underwater Acoustic Antagonizing, China State Shipbuilding Corporation Systems Engineering Research Institute, Beijing 100036, China

Sensors 2017, 17(7), 1516; https://doi.org/10.3390/s17071516 - 27 Jun 2017

Cited by 11 | Viewed by 5058

Abstract

This paper proposes a composite channel virtual time reversal mirror (CCVTRM) for vertical sensor array (VSA) processing and applies it to long-range underwater acoustic (UWA) communication in shallow water. Because of weak signal-to-noise ratio (SNR), it is unable to accurately estimate the channel [...] Read more.

This paper proposes a composite channel virtual time reversal mirror (CCVTRM) for vertical sensor array (VSA) processing and applies it to long-range underwater acoustic (UWA) communication in shallow water. Because of weak signal-to-noise ratio (SNR), it is unable to accurately estimate the channel impulse response of each sensor of the VSA, thus the traditional passive time reversal mirror (PTRM) cannot perform well in long-range UWA communication in shallow water. However, CCVTRM only needs to estimate the composite channel of the VSA to accomplish time reversal mirror (TRM), which can effectively mitigate the inter-symbol interference (ISI) and reduce the bit error rate (BER). In addition, the calculation of CCVTRM is simpler than traditional PTRM. An UWA communication experiment using a VSA of 12 sensors was conducted in the South China Sea. The experiment achieves a very low BER communication at communication rate of 66.7 bit/s over an 80 km range. The results of the sea trial demonstrate that CCVTRM is feasible and can be applied to long-range UWA communication in shallow water. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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14 pages, 1003 KiB

Open AccessArticle

Algorithms for Lightweight Key Exchange

by Rafael Alvarez^1,*,‡

, Cándido Caballero-Gil^2,‡

, Juan Santonja^1,‡ and Antonio Zamora^1,‡

¹ Department of Computer Science and Artificial Intelligence, University of Alicante, 03690 Alicante, Spain

² Department of Computer Engineering and Systems, University of La Laguna, 38206 Tenerife, Spain

^‡ These authors contributed equally to this work.

Sensors 2017, 17(7), 1517; https://doi.org/10.3390/s17071517 - 27 Jun 2017

Cited by 30 | Viewed by 7365

Abstract

Public-key cryptography is too slow for general purpose encryption, with most applications limiting its use as much as possible. Some secure protocols, especially those that enable forward secrecy, make a much heavier use of public-key cryptography, increasing the demand for lightweight cryptosystems that [...] Read more.

Public-key cryptography is too slow for general purpose encryption, with most applications limiting its use as much as possible. Some secure protocols, especially those that enable forward secrecy, make a much heavier use of public-key cryptography, increasing the demand for lightweight cryptosystems that can be implemented in low powered or mobile devices. This performance requirements are even more significant in critical infrastructure and emergency scenarios where peer-to-peer networks are deployed for increased availability and resiliency. We benchmark several public-key key-exchange algorithms, determining those that are better for the requirements of critical infrastructure and emergency applications and propose a security framework based on these algorithms and study its application to decentralized node or sensor networks. Full article

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

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22 pages, 7072 KiB

Open AccessArticle

Active Multimodal Sensor System for Target Recognition and Tracking

by Yufu Qu^*

, Guirong Zhang, Zhaofan Zou, Ziyue Liu and Jiansen Mao

School of Instrumentation Scienc & Optoelectronics Engineering, Beihang University, Beijing 100191, China

Sensors 2017, 17(7), 1518; https://doi.org/10.3390/s17071518 - 28 Jun 2017

Cited by 14 | Viewed by 6347

Abstract

High accuracy target recognition and tracking systems using a single sensor or a passive multisensor set are susceptible to external interferences and exhibit environmental dependencies. These difficulties stem mainly from limitations to the available imaging frequency bands, and a general lack of coherent [...] Read more.

High accuracy target recognition and tracking systems using a single sensor or a passive multisensor set are susceptible to external interferences and exhibit environmental dependencies. These difficulties stem mainly from limitations to the available imaging frequency bands, and a general lack of coherent diversity of the available target-related data. This paper proposes an active multimodal sensor system for target recognition and tracking, consisting of a visible, an infrared, and a hyperspectral sensor. The system makes full use of its multisensor information collection abilities; furthermore, it can actively control different sensors to collect additional data, according to the needs of the real-time target recognition and tracking processes. This level of integration between hardware collection control and data processing is experimentally shown to effectively improve the accuracy and robustness of the target recognition and tracking system. Full article

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

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11 pages, 5704 KiB

Open AccessFeature PaperArticle

Nanoporous Gold Nanocomposites as a Versatile Platform for Plasmonic Engineering and Sensing

by Fusheng Zhao¹, Jianbo Zeng¹ and Wei-Chuan Shih^1,2,3,4,5,*

¹ Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun Rd, Houston, TX 77004, USA

² Department of Biomedical Engineering, University of Houston, 4800 Calhoun Rd, Houston, TX 77004, USA

³ Program of Materials Science and Engineering, University of Houston, 4800 Calhoun Rd, Houston, TX77004, USA

⁴ Department of Chemistry, University of Houston, 4800 Calhoun Rd, Houston, TX 77004, USA

⁵ Biomedical Institute for Global Health Research and Technology (BIGHEART), National University of Singapore 14 Medical Drive, Singapore 117599, Singapore

Sensors 2017, 17(7), 1519; https://doi.org/10.3390/s17071519 - 28 Jun 2017

Cited by 23 | Viewed by 6407

Abstract

Plasmonic metal nanostructures have shown great potential in sensing applications. Among various materials and structures, monolithic nanoporous gold disks (NPGD) have several unique features such as three-dimensional (3D) porous network, large surface area, tunable plasmonic resonance, high-density hot-spots, and excellent architectural integrity and [...] Read more.

Plasmonic metal nanostructures have shown great potential in sensing applications. Among various materials and structures, monolithic nanoporous gold disks (NPGD) have several unique features such as three-dimensional (3D) porous network, large surface area, tunable plasmonic resonance, high-density hot-spots, and excellent architectural integrity and environmental stability. They exhibit a great potential in surface-enhanced spectroscopy, photothermal conversion, and plasmonic sensing. In this work, interactions between smaller colloidal gold nanoparticles (AuNP) and individual NPGDs are studied. Specifically, colloidal gold nanoparticles with different sizes are loaded onto NPGD substrates to form NPG hybrid nanocomposites with tunable plasmonic resonance peaks in the near-infrared spectral range. Newly formed plasmonic hot-spots due to the coupling between individual nanoparticles and NPG disk have been identified in the nanocomposites, which have been experimentally studied using extinction and surface-enhanced Raman scattering. Numerical modeling and simulations have been employed to further unravel various coupling scenarios between AuNP and NPGDs. Full article

(This article belongs to the Special Issue Micro and Nanofabrication Technologies for Biosensors)

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13 pages, 3576 KiB

Open AccessArticle

Tuning Selectivity of Fluorescent Carbon Nanotube-Based Neurotransmitter Sensors

by Florian A. Mann^1,2, Niklas Herrmann¹, Daniel Meyer^1,2 and Sebastian Kruss^1,2,*

¹ Institute of Physical Chemistry, Göttingen University, 37077 Göttingen, Germany

² Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany

Sensors 2017, 17(7), 1521; https://doi.org/10.3390/s17071521 - 28 Jun 2017

Cited by 71 | Viewed by 10545

Abstract

Detection of neurotransmitters is an analytical challenge and essential to understand neuronal networks in the brain and associated diseases. However, most methods do not provide sufficient spatial, temporal, or chemical resolution. Near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) have been used as building [...] Read more.

Detection of neurotransmitters is an analytical challenge and essential to understand neuronal networks in the brain and associated diseases. However, most methods do not provide sufficient spatial, temporal, or chemical resolution. Near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) have been used as building blocks for sensors/probes that detect catecholamine neurotransmitters, including dopamine. This approach provides a high spatial and temporal resolution, but it is not understood if these sensors are able to distinguish dopamine from similar catecholamine neurotransmitters, such as epinephrine or norepinephrine. In this work, the organic phase (DNA sequence) around SWCNTs was varied to create sensors with different selectivity and sensitivity for catecholamine neurotransmitters. Most DNA-functionalized SWCNTs responded to catecholamine neurotransmitters, but both dissociation constants (K_d) and limits of detection were highly dependent on functionalization (sequence). K_d values span a range of 2.3 nM (SWCNT-(GC)₁₅ + norepinephrine) to 9.4 μM (SWCNT-(AT)₁₅ + dopamine) and limits of detection are mostly in the single-digit nM regime. Additionally, sensors of different SWCNT chirality show different fluorescence increases. Moreover, certain sensors (e.g., SWCNT-(GT)₁₀) distinguish between different catecholamines, such as dopamine and norepinephrine at low concentrations (50 nM). These results show that SWCNTs functionalized with certain DNA sequences are able to discriminate between catecholamine neurotransmitters or to detect them in the presence of interfering substances of similar structure. Such sensors will be useful to measure and study neurotransmitter signaling in complex biological settings. Full article

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

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14 pages, 10528 KiB

Open AccessArticle

Towards Mobile Gait Analysis: Concurrent Validity and Test-Retest Reliability of an Inertial Measurement System for the Assessment of Spatio-Temporal Gait Parameters

by Felix Kluge^1,*

, Heiko Gaßner², Julius Hannink¹

, Cristian Pasluosta^1,3, Jochen Klucken² and Björn M. Eskofier¹

¹ Digital Sports Group, Pattern Recognition Laboratory, Department of Computer Science, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany

² Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany

³ Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany

Sensors 2017, 17(7), 1522; https://doi.org/10.3390/s17071522 - 28 Jun 2017

Cited by 118 | Viewed by 11165

Abstract

The purpose of this study was to assess the concurrent validity and test–retest reliability of a sensor-based gait analysis system. Eleven healthy subjects and four Parkinson’s disease (PD) patients were asked to complete gait tasks whilst wearing two inertial measurement units at their [...] Read more.

The purpose of this study was to assess the concurrent validity and test–retest reliability of a sensor-based gait analysis system. Eleven healthy subjects and four Parkinson’s disease (PD) patients were asked to complete gait tasks whilst wearing two inertial measurement units at their feet. The extracted spatio-temporal parameters of 1166 strides were compared to those extracted from a reference camera-based motion capture system concerning concurrent validity. Test–retest reliability was assessed for five healthy subjects at three different days in a two week period. The two systems were highly correlated for all gait parameters (

r > 0.93

). The bias for stride time was

0 \pm 16

ms and for stride length was

1.4 \pm 6.7

cm. No systematic range dependent errors were observed and no significant changes existed between healthy subjects and PD patients. Test-retest reliability was excellent for all parameters (intraclass correlation (ICC) > 0.81) except for gait velocity (ICC > 0.55). The sensor-based system was able to accurately capture spatio-temporal gait parameters as compared to the reference camera-based system for normal and impaired gait. The system’s high retest reliability renders the use in recurrent clinical measurements and in long-term applications feasible. Full article

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

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22 pages, 40456 KiB

Open AccessArticle

Colorization-Based RGB-White Color Interpolation using Color Filter Array with Randomly Sampled Pattern

by Paul Oh¹, Sukho Lee² and Moon Gi Kang^1,*

¹ Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Ku, Seoul 03722, Korea

² Department of Software Engineering, Dongseo University, 47 Jurye-ro, Sasang-Ku, Busan 47011, Korea

Sensors 2017, 17(7), 1523; https://doi.org/10.3390/s17071523 - 28 Jun 2017

Cited by 18 | Viewed by 10115

Abstract

Recently, several RGB-White (RGBW) color filter arrays (CFAs) have been proposed, which have extra white (W) pixels in the filter array that are highly sensitive. Due to the high sensitivity, the W pixels have better SNR (Signal to Noise Ratio) characteristics than other [...] Read more.

Recently, several RGB-White (RGBW) color filter arrays (CFAs) have been proposed, which have extra white (W) pixels in the filter array that are highly sensitive. Due to the high sensitivity, the W pixels have better SNR (Signal to Noise Ratio) characteristics than other color pixels in the filter array, especially, in low light conditions. However, most of the RGBW CFAs are designed so that the acquired RGBW pattern image can be converted into the conventional Bayer pattern image, which is then again converted into the final color image by using conventional demosaicing methods, i.e., color interpolation techniques. In this paper, we propose a new RGBW color filter array based on a totally different color interpolation technique, the colorization algorithm. The colorization algorithm was initially proposed for colorizing a gray image into a color image using a small number of color seeds. Here, we adopt this algorithm as a color interpolation technique, so that the RGBW color filter array can be designed with a very large number of W pixels to make the most of the highly sensitive characteristics of the W channel. The resulting RGBW color filter array has a pattern with a large proportion of W pixels, while the small-numbered RGB pixels are randomly distributed over the array. The colorization algorithm makes it possible to reconstruct the colors from such a small number of RGB values. Due to the large proportion of W pixels, the reconstructed color image has a high SNR value, especially higher than those of conventional CFAs in low light condition. Experimental results show that many important information which are not perceived in color images reconstructed with conventional CFAs are perceived in the images reconstructed with the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 869 KiB

Open AccessArticle

Physical Layer Secret-Key Generation Scheme for Transportation Security Sensor Network

by Bin Yang and Jianfeng Zhang^*

College of Information Engineering, Northwest A&F University, Xianyang 712100, China

Sensors 2017, 17(7), 1524; https://doi.org/10.3390/s17071524 - 28 Jun 2017

Cited by 5 | Viewed by 5078

Abstract

Wireless Sensor Networks (WSNs) are widely used in different disciplines, including transportation systems, agriculture field environment monitoring, healthcare systems, and industrial monitoring. The security challenge of the wireless communication link between sensor nodes is critical in WSNs. In this paper, we propose a [...] Read more.

Wireless Sensor Networks (WSNs) are widely used in different disciplines, including transportation systems, agriculture field environment monitoring, healthcare systems, and industrial monitoring. The security challenge of the wireless communication link between sensor nodes is critical in WSNs. In this paper, we propose a new physical layer secret-key generation scheme for transportation security sensor network. The scheme is based on the cooperation of all the sensor nodes, thus avoiding the key distribution process, which increases the security of the system. Different passive and active attack models are analyzed in this paper. We also prove that when the cooperative node number is large enough, even when the eavesdropper is equipped with multiple antennas, the secret-key is still secure. Numerical results are performed to show the efficiency of the proposed scheme. Full article

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

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23 pages, 3193 KiB

Open AccessArticle

Characterizing Computer Access Using a One-Channel EEG Wireless Sensor

by Alberto J. Molina-Cantero^1,*,†

, Jaime Guerrero-Cubero^1,†, Isabel M. Gómez-González^1,†

, Manuel Merino-Monge^1,†

and Juan I. Silva-Silva²

¹ Departamento de Tecnología Electrónica, ETS Ingeniería Informática, Universidad de Sevilla, Campus de Reina Mercedes, Sevilla 41012, Spain

² ASPACE Sevilla, Dos Hermanas, Sevilla 41704, Spain

^† Current address: ETS Ingeniería Informática, Campus de Reina Mercedes sn, Sevilla 41012, Spain

Sensors 2017, 17(7), 1525; https://doi.org/10.3390/s17071525 - 29 Jun 2017

Cited by 12 | Viewed by 6348

Abstract

This work studies the feasibility of using mental attention to access a computer. Brain activity was measured with an electrode placed at the Fp1 position and the reference on the left ear; seven normally developed people and three subjects with cerebral palsy (CP) [...] Read more.

This work studies the feasibility of using mental attention to access a computer. Brain activity was measured with an electrode placed at the Fp1 position and the reference on the left ear; seven normally developed people and three subjects with cerebral palsy (CP) took part in the experimentation. They were asked to keep their attention high and low for as long as possible during several trials. We recorded attention levels and power bands conveyed by the sensor, but only the first was used for feedback purposes. All of the information was statistically analyzed to find the most significant parameters and a classifier based on linear discriminant analysis (LDA) was also set up. In addition, 60% of the participants were potential users of this technology with an accuracy of over 70%. Including power bands in the classifier did not improve the accuracy in discriminating between the two attentional states. For most people, the best results were obtained by using only the attention indicator in classification. Tiredness was higher in the group with disabilities (2.7 in a scale of 3) than in the other (1.5 in the same scale); and modulating the attention to access a communication board requires that it does not contain many pictograms (between 4 and 7) on screen and has a scanning period of a relatively high

t_{s c a n} \approx

10 s. The information transfer rate (ITR) is similar to the one obtained by other brain computer interfaces (BCI), like those based on sensorimotor rhythms (SMR) or slow cortical potentials (SCP), and makes it suitable as an eye-gaze independent BCI. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 3295 KiB

Open AccessArticle

Multisensor Parallel Largest Ellipsoid Distributed Data Fusion with Unknown Cross-Covariances

by Baoyu Liu¹, Xingqun Zhan^1,* and Zheng H. Zhu²

¹ School of Aeronautics and Astronautics, Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang District, Shanghai 200240, China

² Department of Mechanical Engineering, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada

Sensors 2017, 17(7), 1526; https://doi.org/10.3390/s17071526 - 29 Jun 2017

Cited by 10 | Viewed by 4922

Abstract

As the largest ellipsoid (LE) data fusion algorithm can only be applied to two-sensor system, in this contribution, parallel fusion structure is proposed to introduce the LE algorithm into a multisensor system with unknown cross-covariances, and three parallel fusion structures based on different [...] Read more.

As the largest ellipsoid (LE) data fusion algorithm can only be applied to two-sensor system, in this contribution, parallel fusion structure is proposed to introduce the LE algorithm into a multisensor system with unknown cross-covariances, and three parallel fusion structures based on different estimate pairing methods are presented and analyzed. In order to assess the influence of fusion structure on fusion performance, two fusion performance assessment parameters are defined as Fusion Distance and Fusion Index. Moreover, the formula for calculating the upper bounds of actual fused error covariances of the presented multisensor LE fusers is also provided. Demonstrated with simulation examples, the Fusion Index indicates fuser’s actual fused accuracy and its sensitivity to the sensor orders, as well as its robustness to the accuracy of newly added sensors. Compared to the LE fuser with sequential structure, the LE fusers with proposed parallel structures not only significantly improve their properties in these aspects, but also embrace better performances in consistency and computation efficiency. The presented multisensor LE fusers generally have better accuracies than that of covariance intersection (CI) fusion algorithm and are consistent when the local estimates are weakly correlated. Full article

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

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19 pages, 636 KiB

Open AccessArticle

Data Aggregation Based on Overlapping Rate of Sensing Area in Wireless Sensor Networks

by Xiaolan Tang¹, Hua Xie¹, Wenlong Chen^1,*, Jianwei Niu^2,3 and Shuhang Wang⁴

¹ College of Information Engineering, Capital Normal University, Beijing 100048, China

² State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing 100191, China

³ Research Institute of Beihang University in Shenzhen, Shenzhen 518057, China

⁴ Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA

Sensors 2017, 17(7), 1527; https://doi.org/10.3390/s17071527 - 29 Jun 2017

Cited by 7 | Viewed by 5084

Abstract

Wireless sensor networks are required in smart applications to provide accurate control, where the high density of sensors brings in a large quantity of redundant data. In order to reduce the waste of limited network resources, data aggregation is utilized to avoid redundancy [...] Read more.

Wireless sensor networks are required in smart applications to provide accurate control, where the high density of sensors brings in a large quantity of redundant data. In order to reduce the waste of limited network resources, data aggregation is utilized to avoid redundancy forwarding. However, most of aggregation schemes reduce information accuracy and prolong end-to-end delay when eliminating transmission overhead. In this paper, we propose a data aggregation scheme based on overlapping rate of sensing area, namely AggOR, aiming for energy-efficient data collection in wireless sensor networks with high information accuracy. According to aggregation rules, gathering nodes are selected from candidate parent nodes and appropriate neighbor nodes considering a preset threshold of overlapping rate of sensing area. Therefore, the collected data in a gathering area are highly correlated, and a large amount of redundant data could be cleaned. Meanwhile, AggOR keeps the original entropy by only deleting the duplicated data. Experiment results show that compared with others, AggOR has a high data accuracy and a short end-to-end delay with a similar network lifetime. Full article

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

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16 pages, 1760 KiB

Open AccessArticle

Online Recognition of Daily Activities by Color-Depth Sensing and Knowledge Models

by Carlos Fernando Crispim-Junior^1,2,*, Alvaro Gómez Uría¹, Carola Strumia¹, Michal Koperski¹, Alexandra König^2,3, Farhood Negin¹, Serhan Cosar¹, Anh Tuan Nghiem¹, Duc Phu Chau¹, Guillaume Charpiat¹ and Francois Bremond^1,2,*

¹ INRIA Sophia Antipolis, 2004 route des Lucioles, BP 93, 06902 Sophia Antipolis, France

² CobTek-Cognition Behaviour Technology, Université Nice Sophia Antipolis, 06100 Nice, France

³ MUMC-School for Mental Health and Neuroscience, Alzheimer Center Limburg, Maastricht University, 6200 Maastricht, The Netherlands

Sensors 2017, 17(7), 1528; https://doi.org/10.3390/s17071528 - 29 Jun 2017

Cited by 13 | Viewed by 5084

Abstract

Visual activity recognition plays a fundamental role in several research fields as a way to extract semantic meaning of images and videos. Prior work has mostly focused on classification tasks, where a label is given for a video clip. However, real life scenarios [...] Read more.

Visual activity recognition plays a fundamental role in several research fields as a way to extract semantic meaning of images and videos. Prior work has mostly focused on classification tasks, where a label is given for a video clip. However, real life scenarios require a method to browse a continuous video flow, automatically identify relevant temporal segments and classify them accordingly to target activities. This paper proposes a knowledge-driven event recognition framework to address this problem. The novelty of the method lies in the combination of a constraint-based ontology language for event modeling with robust algorithms to detect, track and re-identify people using color-depth sensing (Kinect^® sensor). This combination enables to model and recognize longer and more complex events and to incorporate domain knowledge and 3D information into the same models. Moreover, the ontology-driven approach enables human understanding of system decisions and facilitates knowledge transfer across different scenes. The proposed framework is evaluated with real-world recordings of seniors carrying out unscripted, daily activities at hospital observation rooms and nursing homes. Results demonstrated that the proposed framework outperforms state-of-the-art methods in a variety of activities and datasets, and it is robust to variable and low-frame rate recordings. Further work will investigate how to extend the proposed framework with uncertainty management techniques to handle strong occlusion and ambiguous semantics, and how to exploit it to further support medicine on the timely diagnosis of cognitive disorders, such as Alzheimer’s disease. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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9 pages, 2829 KiB

Open AccessArticle

Surface Acoustic Wave Sensor with Pd/ZnO Bilayer Structure for Room Temperature Hydrogen Detection

by Cristian Viespe

and Dana Miu^*

National Institute for Laser, Plasma and Radiation Physics, Laser Department, Atomistilor # 409, 077125 Bucharest-Magurele, Romania

Sensors 2017, 17(7), 1529; https://doi.org/10.3390/s17071529 - 29 Jun 2017

Cited by 43 | Viewed by 6534

Abstract

A Surface Acoustic Wave (SAW) hydrogen sensor with a Pd/ZnO bilayer structure for room temperature sensing operation has been obtained by Pulsed Laser Deposition (PLD). The sensor structure combines a Pd layer with optimized porosity for maximizing mass effects, with the large acoustoelectric [...] Read more.

A Surface Acoustic Wave (SAW) hydrogen sensor with a Pd/ZnO bilayer structure for room temperature sensing operation has been obtained by Pulsed Laser Deposition (PLD). The sensor structure combines a Pd layer with optimized porosity for maximizing mass effects, with the large acoustoelectric effect at the Pd/ZnO interface. The large acoustoelectric effect is due to the fact that ZnO has a surface conductivity which is highly sensitive to chemisorbed gases. The sensitivity of the sensor was determined for hydrogen concentrations between 0.2% and 2%. The limit of detection (LOD) of the bilayer sensor was about 4.5 times better than the single ZnO films and almost twice better than single Pd films. Full article

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

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12 pages, 2100 KiB

Open AccessArticle

Substrate Oxide Layer Thickness Optimization for a Dual-Width Plasmonic Grating for Surface-Enhanced Raman Spectroscopy (SERS) Biosensor Applications

by Stephen J. Bauman¹, Zachary T. Brawley², Ahmad A. Darweesh¹ and Joseph B. Herzog^1,2,*

¹ Microelectronics-Photonics Graduate Program, 731 W. Dickson St., University of Arkansas, Fayetteville, Arkansas, AR 72701, USA

² Department of Physics, 825 W. Dickson St., University of Arkansas, Fayetteville, Arkansas, AR 72701, USA

Sensors 2017, 17(7), 1530; https://doi.org/10.3390/s17071530 - 30 Jun 2017

Cited by 15 | Viewed by 7355

Abstract

This work investigates a new design for a plasmonic SERS biosensor via computational electromagnetic models. It utilizes a dual-width plasmonic grating design, which has two different metallic widths per grating period. These types of plasmonic gratings have shown larger optical enhancement than standard [...] Read more.

This work investigates a new design for a plasmonic SERS biosensor via computational electromagnetic models. It utilizes a dual-width plasmonic grating design, which has two different metallic widths per grating period. These types of plasmonic gratings have shown larger optical enhancement than standard single-width gratings. The new structures have additional increased enhancement when the spacing between the metal decreases to sub-10 nm dimensions. This work integrates an oxide layer to improve the enhancement even further by carefully studying the effects of the substrate oxide thickness on the enhancement and reports ideal substrate parameters. The combined effects of varying the substrate and the grating geometry are studied to fully optimize the device’s enhancement for SERS biosensing and other plasmonic applications. The work reports the ideal widths and substrate thickness for both a standard and a dual-width plasmonic grating SERS biosensor. The ideal geometry, comprising a dual-width grating structure atop an optimal SiO₂ layer thickness, improves the enhancement by 800%, as compared to non-optimized structures with a single-width grating and a non-optimal oxide thickness. Full article

(This article belongs to the Special Issue Applications of Raman Spectroscopy in Biosensors)

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13 pages, 3985 KiB

Open AccessArticle

Temperature Measurement and Numerical Prediction in Machining Inconel 718

by José Díaz-Álvarez^1,*

, Alberto Tapetado², Carmen Vázquez²

and Henar Miguélez³

¹ Department of Aerospace Engineering, University Carlos III of Madrid, 28911 Leganés, Spain

² Department of Electronics Technology, University Carlos III of Madrid, 28911 Leganés, Spain

³ Department of Mechanical Engineering, University Carlos III of Madrid, 28911 Leganés, Spain

Sensors 2017, 17(7), 1531; https://doi.org/10.3390/s17071531 - 30 Jun 2017

Cited by 44 | Viewed by 7177

Abstract

Thermal issues are critical when machining Ni-based superalloy components designed for high temperature applications. The low thermal conductivity and extreme strain hardening of this family of materials results in elevated temperatures around the cutting area. This elevated temperature could lead to machining-induced damage [...] Read more.

Thermal issues are critical when machining Ni-based superalloy components designed for high temperature applications. The low thermal conductivity and extreme strain hardening of this family of materials results in elevated temperatures around the cutting area. This elevated temperature could lead to machining-induced damage such as phase changes and residual stresses, resulting in reduced service life of the component. Measurement of temperature during machining is crucial in order to control the cutting process, avoiding workpiece damage. On the other hand, the development of predictive tools based on numerical models helps in the definition of machining processes and the obtainment of difficult to measure parameters such as the penetration of the heated layer. However, the validation of numerical models strongly depends on the accurate measurement of physical parameters such as temperature, ensuring the calibration of the model. This paper focuses on the measurement and prediction of temperature during the machining of Ni-based superalloys. The temperature sensor was based on a fiber-optic two-color pyrometer developed for localized temperature measurements in turning of Inconel 718. The sensor is capable of measuring temperature in the range of 250 to 1200 °C. Temperature evolution is recorded in a lathe at different feed rates and cutting speeds. Measurements were used to calibrate a simplified numerical model for prediction of temperature fields during turning. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 1187 KiB

Open AccessArticle

GNSS Spoofing Detection and Mitigation Based on Maximum Likelihood Estimation

by Fei Wang

, Hong Li^* and Mingquan Lu

Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(7), 1532; https://doi.org/10.3390/s17071532 - 30 Jun 2017

Cited by 44 | Viewed by 7408

Abstract

Spoofing attacks are threatening the global navigation satellite system (GNSS). The maximum likelihood estimation (MLE)-based positioning technique is a direct positioning method originally developed for multipath rejection and weak signal processing. We find this method also has a potential ability for GNSS anti-spoofing [...] Read more.

Spoofing attacks are threatening the global navigation satellite system (GNSS). The maximum likelihood estimation (MLE)-based positioning technique is a direct positioning method originally developed for multipath rejection and weak signal processing. We find this method also has a potential ability for GNSS anti-spoofing since a spoofing attack that misleads the positioning and timing result will cause distortion to the MLE cost function. Based on the method, an estimation-cancellation approach is presented to detect spoofing attacks and recover the navigation solution. A statistic is derived for spoofing detection with the principle of the generalized likelihood ratio test (GLRT). Then, the MLE cost function is decomposed to further validate whether the navigation solution obtained by MLE-based positioning is formed by consistent signals. Both formulae and simulations are provided to evaluate the anti-spoofing performance. Experiments with recordings in real GNSS spoofing scenarios are also performed to validate the practicability of the approach. Results show that the method works even when the code phase differences between the spoofing and authentic signals are much less than one code chip, which can improve the availability of GNSS service greatly under spoofing attacks. Full article

(This article belongs to the Section Remote Sensors)

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24 pages, 2118 KiB

Open AccessArticle

Dimension-Reduced Analog—Digital Mixed Measurement Method of Inductive Proximity Sensor

by Yi-Xin Guo^1,*,†

, Zhi-Biao Shao^1,†, Hui-Bin Tao^2,†, Kai-Liang Xu^3,† and Ting Li^1,†

¹ The School of Electronic and Information Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, China

² The Institute of AI & Robotics, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, China

³ The School of Automation and Information Engineering, Xi’an University of Technology, No.5 South Jinhua Road, Xi’an 710048, China

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1533; https://doi.org/10.3390/s17071533 - 30 Jun 2017

Cited by 9 | Viewed by 5282

Abstract

Inductive proximity sensors (IPSs) present a unique no-contact advantage. They are widely preferred for displacement measurement in various industrial fields (e.g., aviation and aerospace), and they are improved continuously. When the inductance and resistance components of the IPS sensing core are separated, the [...] Read more.

Inductive proximity sensors (IPSs) present a unique no-contact advantage. They are widely preferred for displacement measurement in various industrial fields (e.g., aviation and aerospace), and they are improved continuously. When the inductance and resistance components of the IPS sensing core are separated, the influence of temperature drift on measurement can be eliminated. The complexity of online computation of component separation can be reduced using a two-dimensional look-up table method. However, this method exhibits disadvantages, such as large capacity of the look-up table, dependency on precision measurement of sensing core parameter, and nonlinear distribution of measurement resolution. This study aims to overcome these disadvantages by examining the nonlinear relationship between the response of the sensing core and the ambient temperature, and proposes a dimension-reduced measurement method. The proposed method extracts the characteristics of the response curves at two temperatures and calculates the characteristics of the response curves at any temperature using a linear approximation. The look-up table capacity is less than 0.37% of the two-dimensional look-up table capacity (condensed) under the same condition; dimension reduction enables the construction of a complete look-up table directly by calibration procedures and avoids precise measurement on sensing core parameters; the calibration procedures establish uniform mapping of the distribution of measurement resolution. The experiment shows that, when the measurement ranges are 0–6, 0–5, and 0–4 mm, the maximum measurement errors are 0.140, 0.065, and 0.040 mm, respectively, under temperature ranging from 20

^{\circ}

C to 110

^{\circ}

C. This study extends the measurement range from 0–5 mm to 0–7 mm and improves the measurement accuracy over 0.1 mm (50% at 5 mm) compared with the two-dimensional look-up table method. Therefore, the proposed method not only inherits the advantages of the original method but also achieves the above-mentioned expected capacity improvements effectively. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 6450 KiB

Open AccessArticle

A Study of Deep CNN-Based Classification of Open and Closed Eyes Using a Visible Light Camera Sensor

by Ki Wan Kim, Hyung Gil Hong, Gi Pyo Nam 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(7), 1534; https://doi.org/10.3390/s17071534 - 30 Jun 2017

Cited by 81 | Viewed by 12340

Abstract

The necessity for the classification of open and closed eyes is increasing in various fields, including analysis of eye fatigue in 3D TVs, analysis of the psychological states of test subjects, and eye status tracking-based driver drowsiness detection. Previous studies have used various [...] Read more.

The necessity for the classification of open and closed eyes is increasing in various fields, including analysis of eye fatigue in 3D TVs, analysis of the psychological states of test subjects, and eye status tracking-based driver drowsiness detection. Previous studies have used various methods to distinguish between open and closed eyes, such as classifiers based on the features obtained from image binarization, edge operators, or texture analysis. However, when it comes to eye images with different lighting conditions and resolutions, it can be difficult to find an optimal threshold for image binarization or optimal filters for edge and texture extraction. In order to address this issue, we propose a method to classify open and closed eye images with different conditions, acquired by a visible light camera, using a deep residual convolutional neural network. After conducting performance analysis on both self-collected and open databases, we have determined that the classification accuracy of the proposed method is superior to that of existing methods. Full article

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

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13 pages, 7010 KiB

Open AccessArticle

An Automatic Car Counting System Using OverFeat Framework

by Debojit Biswas¹, Hongbo Su^1,*, Chengyi Wang², Jason Blankenship¹ and Aleksandar Stevanovic¹

¹ Department of Civil, Environmental and Geomatics Engineering, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA

² Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, No. 9 Dengzhuang South Road, Haidian District, Beijing 100094, China

Sensors 2017, 17(7), 1535; https://doi.org/10.3390/s17071535 - 30 Jun 2017

Cited by 37 | Viewed by 11331

Abstract

Automatic car counting is an important component in the automated traffic system. Car counting is very important to understand the traffic load and optimize the traffic signals. In this paper, we implemented the Gaussian Background Subtraction Method and OverFeat Framework to count cars. [...] Read more.

Automatic car counting is an important component in the automated traffic system. Car counting is very important to understand the traffic load and optimize the traffic signals. In this paper, we implemented the Gaussian Background Subtraction Method and OverFeat Framework to count cars. OverFeat Framework is a combination of Convolution Neural Network (CNN) and one machine learning classifier (like Support Vector Machines (SVM) or Logistic Regression). With this study, we showed another possible application area for the OverFeat Framework. The advantages and shortcomings of the Background Subtraction Method and OverFeat Framework were analyzed using six individual traffic videos with different perspectives, such as camera angles, weather conditions and time of the day. In addition, we compared the two algorithms above with manual counting and a commercial software called Placemeter. The OverFeat Framework showed significant potential in the field of car counting with the average accuracy of 96.55% in our experiment. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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11 pages, 5510 KiB

Open AccessArticle

A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor

by Huayu Zhang¹

, Fengqin Xie^2,*, Maoyong Cao³ and Mingming Zhong¹

¹ College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266590, China

² College of Transportation, Shandong University of Science and Technology, Qingdao 266590, China

³ College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, China

Sensors 2017, 17(7), 1536; https://doi.org/10.3390/s17071536 - 1 Jul 2017

Cited by 18 | Viewed by 8353

Abstract

To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current [...] Read more.

To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA) sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor), magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 3051 KiB

Open AccessArticle

Thiolate-Capped CdSe/ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose

by Samsulida Abd. Rahman^1,2, Nurhayati Ariffin¹, Nor Azah Yusof^2,3,*, Jaafar Abdullah^2,3

, Faruq Mohammad^4,*

, Zuhana Ahmad Zubir⁵ and Nik Mohd Azmi Nik Abd. Aziz⁵

¹ Industrial Biotechnology Research Centre (IBRC), SIRIM Berhad, No. 1, Persiaran Dato’ Menteri, Section 2, P.O. Box 7035, 40700 Shah Alam, Selangor, Malaysia

² Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia

³ Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM, Serdang, Malaysia

⁴ Surfactant Research Chair, Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia

⁵ Advance Material Research Centre (AMREC), SIRIM Berhad, Lot 34, Jalan Hi-Tech 2/3, Kulim Hi-Tech Park, 09000 Kulim, Malaysia

Sensors 2017, 17(7), 1537; https://doi.org/10.3390/s17071537 - 1 Jul 2017

Cited by 17 | Viewed by 8166

Abstract

A semiconducting water-soluble core-shell quantum dots (QDs) system capped with thiolated ligand was used in this study for the sensitive detection of glucose in aqueous samples. The QDs selected are of CdSe-coated ZnS and were prepared in house based on a hot injection [...] Read more.

A semiconducting water-soluble core-shell quantum dots (QDs) system capped with thiolated ligand was used in this study for the sensitive detection of glucose in aqueous samples. The QDs selected are of CdSe-coated ZnS and were prepared in house based on a hot injection technique. The formation of ZnS shell at the outer surface of CdSe core was made via a specific process namely, SILAR (successive ionic layer adsorption and reaction). The distribution, morphology, and optical characteristics of the prepared core-shell QDs were assessed by transmission electron microscopy (TEM) and spectrofluorescence, respectively. From the analysis, the results show that the mean particle size of prepared QDs is in the range of 10–12 nm and that the optimum emission condition was displayed at 620 nm. Further, the prepared CdSe/ZnS core shell QDs were modified by means of a room temperature ligand-exchange method that involves six organic ligands, L-cysteine, L-histidine, thio-glycolic acid (TGA or mercapto-acetic acid, MAA), mercapto-propionic acid (MPA), mercapto-succinic acid (MSA), and mercapto-undecanoic acid (MUA). This process was chosen in order to maintain a very dense water solubilizing environment around the QDs surface. From the analysis, the results show that the CdSe/ZnS capped with TGA (CdSe/ZnS-TGA) exhibited the strongest fluorescence emission as compared to others; hence, it was tested further for the glucose detection after their treatment with glucose oxidase (GOx) and horseradish peroxidase (HRP) enzymes. Here in this study, the glucose detection is based on the fluorescence quenching effect of the QDs, which is correlated to the oxidative reactions occurred between the conjugated enzymes and glucose. From the analysis of results, it can be inferred that the resultant GOx:HRP/CdSe/ZnS-TGA QDs system can be a suitable platform for the fluorescence-based determination of glucose in the real samples. Full article

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

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14 pages, 2474 KiB

Open AccessArticle

Detection of Quinoline in G. boninense-Infected Plants Using Functionalized Multi-Walled Carbon Nanotubes: A Field Study

by Fowotade Sulayman Akanbi^1,2, Nor Azah Yusof^1,3,*, Jaafar Abdullah¹

, Yusran Sulaiman¹

and Roozbeh Hushiarian^4,*

¹ Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia

² Department of Science Laboratory Technology, Hussaini Adamu Federal Polytechnic, A2 Kazaure, Nigeria

³ Institute of Advanced Technology, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia

⁴ La Trobe Institute for Molecular Science, La Trobe University, Victoria 3086, Australia

Sensors 2017, 17(7), 1538; https://doi.org/10.3390/s17071538 - 1 Jul 2017

Cited by 17 | Viewed by 6199

Abstract

Carbon nanotubes (CNTs) reinforced with gold nanoparticles (AuNPs) and chitosan nanoparticles (CTSNPs) were anchored on a screen-printed electrode to fabricate a multi-walled structure for the detection of quinoline. The surface morphology of the nanocomposites and the modified electrode was examined by an ultra-high [...] Read more.

Carbon nanotubes (CNTs) reinforced with gold nanoparticles (AuNPs) and chitosan nanoparticles (CTSNPs) were anchored on a screen-printed electrode to fabricate a multi-walled structure for the detection of quinoline. The surface morphology of the nanocomposites and the modified electrode was examined by an ultra-high resolution field emission scanning electron microscope (FESEM), and Fourier-transform infrared (FT-IR) spectroscopy was used to confirm the presence of specific functional groups on the multi-walled carbon nanotubes MWCNTs. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to monitor the layer-by-layer assembly of ultra-thin films of nanocomposites on the surface of the electrode and other electrochemical characterizations. Under optimized conditions, the novel sensor displayed outstanding electrochemical reactivity towards the electro-oxidation of quinoline. The linear range was fixed between 0.0004 and 1.0 μM, with a limit of detection (LOD) of 3.75 nM. The fabricated electrode exhibited high stability with excellent sensitivity and selectivity, specifically attributable to the salient characteristics of AuNPs, CTSNPs, and MWCNTs and the synergistic inter-relationship between them. The newly developed electrode was tested in the field. The Ipa increased with an increase in the amount of quinoline solution added, and the peak potential deviated minimally, depicting the real capability of the newly fabricated electrode. Full article

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

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12 pages, 4263 KiB

Open AccessArticle

Development of a PrGO-Modified Electrode for Uric Acid Determination in the Presence of Ascorbic Acid by an Electrochemical Technique

by Nurulkhalilah Tukimin¹, Jaafar Abdullah^1,2

and Yusran Sulaiman^1,2,*

¹ Department of Chemistry, Faculty of Science, Universiti Putra Malaysia (UPM), Serdang 43400, Selangor, Malaysia

² Institute of Advanced Technology (ITMA), Universiti Putra Malaysia (UPM), Serdang 43400, Selangor, Malaysia

Sensors 2017, 17(7), 1539; https://doi.org/10.3390/s17071539 - 1 Jul 2017

Cited by 37 | Viewed by 8071

Abstract

An attractive electrochemical sensor of poly(3,4-ethylenedioxythiophene)/reduced graphene oxide electrode (PrGO) was developed for an electrochemical technique for uric acid (UA) detection in the presence of ascorbic acid (AA). PrGO composite film showed an improved electrocatalytic activity towards UA oxidation in pH 6.0 (0.1 [...] Read more.

An attractive electrochemical sensor of poly(3,4-ethylenedioxythiophene)/reduced graphene oxide electrode (PrGO) was developed for an electrochemical technique for uric acid (UA) detection in the presence of ascorbic acid (AA). PrGO composite film showed an improved electrocatalytic activity towards UA oxidation in pH 6.0 (0.1 M PBS). The PrGO composite exhibited a high current signal and low charge transfer resistance (R_ct) compared to a reduced graphene oxide (rGO) electrode or a bare glassy carbon electrode (GCE). The limit of detection and sensitivity of PrGO for the detection of UA are 0.19 μM (S/N = 3) and 0.01 μA/μM, respectively, in the range of 1–300 μM of UA. Full article

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

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13 pages, 3019 KiB

Open AccessArticle

In-Situ Real-Time Focus Detection during Laser Processing Using Double-Hole Masks and Advanced Image Sensor Software

by Binh Xuan Cao^1,2

, Phuong Le Hoang³, Sanghoon Ahn¹

, Jeng-o Kim¹, Heeshin Kang¹ and Jiwhan Noh^1,2,*

¹ Department of Laser and Electron Beam Application, Korea Institute of Machinery & Materials (KIMM), Daejeon 34103, Korea

² Department of Nano-Mechatronics, Korea University of Science and Technology (UST), Daejeon 34113, Korea

³ Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea

Sensors 2017, 17(7), 1540; https://doi.org/10.3390/s17071540 - 1 Jul 2017

Cited by 12 | Viewed by 6499

Abstract

In modern high-intensity ultrafast laser processing, detecting the focal position of the working laser beam, at which the intensity is the highest and the beam diameter is the lowest, and immediately locating the target sample at that point are challenging tasks. A system [...] Read more.

In modern high-intensity ultrafast laser processing, detecting the focal position of the working laser beam, at which the intensity is the highest and the beam diameter is the lowest, and immediately locating the target sample at that point are challenging tasks. A system that allows in-situ real-time focus determination and fabrication using a high-power laser has been in high demand among both engineers and scientists. Conventional techniques require the complicated mathematical theory of wave optics, employing interference as well as diffraction phenomena to detect the focal position; however, these methods are ineffective and expensive for industrial application. Moreover, these techniques could not perform detection and fabrication simultaneously. In this paper, we propose an optical design capable of detecting the focal point and fabricating complex patterns on a planar sample surface simultaneously. In-situ real-time focus detection is performed using a bandpass filter, which only allows for the detection of laser transmission. The technique enables rapid, non-destructive, and precise detection of the focal point. Furthermore, it is sufficiently simple for application in both science and industry for mass production, and it is expected to contribute to the next generation of laser equipment, which can be used to fabricate micro-patterns with high complexity. Full article

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

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15 pages, 3266 KiB

Open AccessArticle

Hybrid Optical Unobtrusive Blood Pressure Measurements

by Guangfei Zhang¹, Caifeng Shan^1,*, Ihor Kirenko¹, Xi Long^1,2

and Ronald M. Aarts^1,2

¹ Philips Research Eindhoven, 5656 AE Eindhoven, The Netherlands

² Department of Electrical Engineering, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands

Sensors 2017, 17(7), 1541; https://doi.org/10.3390/s17071541 - 1 Jul 2017

Cited by 17 | Viewed by 6870

Abstract

Blood pressure (BP) is critical in diagnosing certain cardiovascular diseases such as hypertension. Some previous studies have proved that BP can be estimated by pulse transit time (PTT) calculated by a pair of photoplethysmography (PPG) signals at two body sites. Currently, contact PPG [...] Read more.

Blood pressure (BP) is critical in diagnosing certain cardiovascular diseases such as hypertension. Some previous studies have proved that BP can be estimated by pulse transit time (PTT) calculated by a pair of photoplethysmography (PPG) signals at two body sites. Currently, contact PPG (cPPG) and imaging PPG (iPPG) are two feasible ways to obtain PPG signals. In this study, we proposed a hybrid system (called the ICPPG system) employing both methods that can be implemented on a wearable device, facilitating the measurement of BP in an inconspicuous way. The feasibility of the ICPPG system was validated on a dataset with 29 subjects. It has been proved that the ICPPG system is able to estimate PTT values. Moreover, the PTT measured by the new system shows a correlation on average with BP variations for most subjects, which could facilitate a new generation of BP measurement using wearable and mobile devices. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 3036 KiB

Open AccessArticle

A Satellite-Based Imaging Instrumentation Concept for Hyperspectral Thermal Remote Sensing

by Thomas Udelhoven^1,*, Martin Schlerf², Karl Segl³, Kaniska Mallick², Christian Bossung¹, Rebecca Retzlaff¹

, Gilles Rock¹, Peter Fischer⁴, Andreas Müller⁴, Tobias Storch⁴, Andreas Eisele³, Dennis Weise⁵, Werner Hupfer⁵ and Thiemo Knigge⁵

¹ Department of Environmental Remote Sensing & Geoinformatics, University of Trier, 54286 Trier, Germany

² Luxembourg Institute of Science and Technology (LIST), L-4362 Esch-sur-Alzette, Luxembourg

³ German Research Centre for Geosciences (GFZ), 14473 Potsdam, Germany

⁴ DLR German Aerospace Center, 82234 Weßling, Germany

⁵ Airbus DS GmbH, 88090 Immenstaad, Germany

Sensors 2017, 17(7), 1542; https://doi.org/10.3390/s17071542 - 1 Jul 2017

Cited by 16 | Viewed by 9038

Abstract

This paper describes the concept of the hyperspectral Earth-observing thermal infrared (TIR) satellite mission HiTeSEM (High-resolution Temperature and Spectral Emissivity Mapping). The scientific goal is to measure specific key variables from the biosphere, hydrosphere, pedosphere, and geosphere related to two global problems of [...] Read more.

This paper describes the concept of the hyperspectral Earth-observing thermal infrared (TIR) satellite mission HiTeSEM (High-resolution Temperature and Spectral Emissivity Mapping). The scientific goal is to measure specific key variables from the biosphere, hydrosphere, pedosphere, and geosphere related to two global problems of significant societal relevance: food security and human health. The key variables comprise land and sea surface radiation temperature and emissivity, surface moisture, thermal inertia, evapotranspiration, soil minerals and grain size components, soil organic carbon, plant physiological variables, and heat fluxes. The retrieval of this information requires a TIR imaging system with adequate spatial and spectral resolutions and with day-night following observation capability. Another challenge is the monitoring of temporally high dynamic features like energy fluxes, which require adequate revisit time. The suggested solution is a sensor pointing concept to allow high revisit times for selected target regions (1–5 days at off-nadir). At the same time, global observations in the nadir direction are guaranteed with a lower temporal repeat cycle (>1 month). To account for the demand of a high spatial resolution for complex targets, it is suggested to combine in one optic (1) a hyperspectral TIR system with ~75 bands at 7.2–12.5 µm (instrument NEDT 0.05 K–0.1 K) and a ground sampling distance (GSD) of 60 m, and (2) a panchromatic high-resolution TIR-imager with two channels (8.0–10.25 µm and 10.25–12.5 µm) and a GSD of 20 m. The identified science case requires a good correlation of the instrument orbit with Sentinel-2 (maximum delay of 1–3 days) to combine data from the visible and near infrared (VNIR), the shortwave infrared (SWIR) and TIR spectral regions and to refine parameter retrieval. Full article

(This article belongs to the Special Issue Analysis of Multispectral and Hyperspectral Data)

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17 pages, 8015 KiB

Open AccessArticle

Design and Parametric Study of the Magnetic Sensor for Position Detection in Linear Motor Based on Nonlinear Parametric model order reduction

by Sarbajit Paul and Junghwan Chang^*

Mechatronics System Research Laboratory, Department of Electrical Engineering, Dong-A University, Busan 49315, Korea

Sensors 2017, 17(7), 1543; https://doi.org/10.3390/s17071543 - 1 Jul 2017

Cited by 7 | Viewed by 6718

Abstract

This paper presents a design approach for a magnetic sensor module to detect mover position using the proper orthogonal decomposition-dynamic mode decomposition (POD-DMD)-based nonlinear parametric model order reduction (PMOR). The parameterization of the sensor module is achieved by using the multipolar moment matching [...] Read more.

This paper presents a design approach for a magnetic sensor module to detect mover position using the proper orthogonal decomposition-dynamic mode decomposition (POD-DMD)-based nonlinear parametric model order reduction (PMOR). The parameterization of the sensor module is achieved by using the multipolar moment matching method. Several geometric variables of the sensor module are considered while developing the parametric study. The operation of the sensor module is based on the principle of the airgap flux density distribution detection by the Hall Effect IC. Therefore, the design objective is to achieve a peak flux density (PFD) greater than 0.1 T and total harmonic distortion (THD) less than 3%. To fulfill the constraint conditions, the specifications for the sensor module is achieved by using POD-DMD based reduced model. The POD-DMD based reduced model provides a platform to analyze the high number of design models very fast, with less computational burden. Finally, with the final specifications, the experimental prototype is designed and tested. Two different modes, 90° and 120° modes respectively are used to obtain the position information of the linear motor mover. The position information thus obtained are compared with that of the linear scale data, used as a reference signal. The position information obtained using the 120° mode has a standard deviation of 0.10 mm from the reference linear scale signal, whereas the 90° mode position signal shows a deviation of 0.23 mm from the reference. The deviation in the output arises due to the mechanical tolerances introduced into the specification during the manufacturing process. This provides a scope for coupling the reliability based design optimization in the design process as a future extension. Full article

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

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27 pages, 10594 KiB

Open AccessArticle

Efficient Depth Enhancement Using a Combination of Color and Depth Information

by Kyungjae Lee

, Yuseok Ban and Sangyoun Lee^*

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

Sensors 2017, 17(7), 1544; https://doi.org/10.3390/s17071544 - 1 Jul 2017

Cited by 9 | Viewed by 6221

Abstract

Studies on depth images containing three-dimensional information have been performed for many practical applications. However, the depth images acquired from depth sensors have inherent problems, such as missing values and noisy boundaries. These problems significantly affect the performance of applications that use a [...] Read more.

Studies on depth images containing three-dimensional information have been performed for many practical applications. However, the depth images acquired from depth sensors have inherent problems, such as missing values and noisy boundaries. These problems significantly affect the performance of applications that use a depth image as their input. This paper describes a depth enhancement algorithm based on a combination of color and depth information. To fill depth holes and recover object shapes, asynchronous cellular automata with neighborhood distance maps are used. Image segmentation and a weighted linear combination of spatial filtering algorithms are applied to extract object regions and fill disocclusion in the object regions. Experimental results on both real-world and public datasets show that the proposed method enhances the quality of the depth image with low computational complexity, outperforming conventional methods on a number of metrics. Furthermore, to verify the performance of the proposed method, we present stereoscopic images generated by the enhanced depth image to illustrate the improvement in quality. Full article

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

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10 pages, 1925 KiB

Open AccessArticle

An Infrared Actin Probe for Deep-Cell Electroporation-Based Single-Molecule Speckle (eSiMS) Microscopy

by Sawako Yamashiro^1,* and Naoki Watanabe^1,2

¹ Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan

² Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan

Sensors 2017, 17(7), 1545; https://doi.org/10.3390/s17071545 - 1 Jul 2017

Cited by 7 | Viewed by 5527

Abstract

Single-molecule speckle (SiMS) microscopy is a powerful method to directly elucidate biochemical reactions in live cells. However, since the signal from an individual fluorophore is extremely faint, the observation area by epi-fluorescence microscopy is restricted to the thin cell periphery to reduce autofluorescence, [...] Read more.

Single-molecule speckle (SiMS) microscopy is a powerful method to directly elucidate biochemical reactions in live cells. However, since the signal from an individual fluorophore is extremely faint, the observation area by epi-fluorescence microscopy is restricted to the thin cell periphery to reduce autofluorescence, or only molecules near the plasma membrane are visualized by total internal reflection fluorescence (TIRF) microscopy. Here, we introduce a new actin probe labeled with near infrared (NIR) emissive CF680R dye for easy-to-use, electroporation-based SiMS microscopy (eSiMS) for deep-cell observation. CF680R-labeled actin (CF680R-actin) incorporated into actin structures and showed excellent brightness and photostability suitable for single-molecule imaging. Importantly, the intensity of autofluorescence with respect to SiMS brightness was reduced to approximately 13% compared to DyLight 550-labeled actin (DL550-actin). CF680R-actin enabled the monitoring of actin SiMS in actomyosin bundles associated with adherens junctions (AJs) located at 3.5–4 µm above the basal surfaces of epithelial monolayers. These favorable properties of CF680R-actin extend the application of eSiMS to actin turnover and flow analyses in deep cellular structures. Full article

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

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25 pages, 2432 KiB

Open AccessArticle

Moving Object Detection in Heterogeneous Conditions in Embedded Systems

by Alessandro Garbo and Stefano Quer^*

Dipartimento di Automatica ed Informatica, Politecnico di Torino, 10129 Torino, Italy

Sensors 2017, 17(7), 1546; https://doi.org/10.3390/s17071546 - 1 Jul 2017

Cited by 4 | Viewed by 5545

Abstract

This paper presents a system for moving object exposure, focusing on pedestrian detection, in external, unfriendly, and heterogeneous environments. The system manipulates and accurately merges information coming from subsequent video frames, making small computational efforts in each single frame. Its main characterizing feature [...] Read more.

This paper presents a system for moving object exposure, focusing on pedestrian detection, in external, unfriendly, and heterogeneous environments. The system manipulates and accurately merges information coming from subsequent video frames, making small computational efforts in each single frame. Its main characterizing feature is to combine several well-known movement detection and tracking techniques, and to orchestrate them in a smart way to obtain good results in diversified scenarios. It uses dynamically adjusted thresholds to characterize different regions of interest, and it also adopts techniques to efficiently track movements, and detect and correct false positives. Accuracy and reliability mainly depend on the overall receipt, i.e., on how the software system is designed and implemented, on how the different algorithmic phases communicate information and collaborate with each other, and on how concurrency is organized. The application is specifically designed to work with inexpensive hardware devices, such as off-the-shelf video cameras and small embedded computational units, eventually forming an intelligent urban grid. As a matter of fact, the major contribution of the paper is the presentation of a tool for real-time applications in embedded devices with finite computational (time and memory) resources. We run experimental results on several video sequences (both home-made and publicly available), showing the robustness and accuracy of the overall detection strategy. Comparisons with state-of-the-art strategies show that our application has similar tracking accuracy but much higher frame-per-second rates. Full article

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

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23 pages, 6280 KiB

Open AccessArticle

Measuring Torque and Temperature in a Rotating Shaft Using Commercial SAW Sensors

by Diogo Silva¹, Joana C. Mendes^2,3,*

, António B. Pereira³

, François Gégot⁴ and Luís N. Alves^1,2

¹ Department of Electronics, Telecommunications and Informatics, University of Aveiro, 3810-193 Aveiro, Portugal

² Instituto de Telecomunicações, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

³ Centre for Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro, Portugal

⁴ SENSeOR, 18 rue Alain Savary, 25000 Besançon, France

Sensors 2017, 17(7), 1547; https://doi.org/10.3390/s17071547 - 2 Jul 2017

Cited by 30 | Viewed by 8369

Abstract

Real-time monitoring of torque in a rotating shaft is not easy to implement with technologies such as optic fiber sensors or strain gages. Surface acoustic wave (SAW) sensors are wireless and passive and can be used to monitor strain in moving parts. Commercial [...] Read more.

Real-time monitoring of torque in a rotating shaft is not easy to implement with technologies such as optic fiber sensors or strain gages. Surface acoustic wave (SAW) sensors are wireless and passive and can be used to monitor strain in moving parts. Commercial solutions (sensors, antennas and interrogation unit) can easily be purchased from some companies; however, they are not customized and may not meet the specificity of the measurements. In order to evaluate the adequacy of commercial off-the-shelf (COTS) solutions, temperature and strain sensors fabricated by SENSeOR (Besançon, France) were mounted on a load cell. The sensors were calibrated using a thermal chamber and a universal testing machine. The load cell was then assembled together with a steel shaft that rotated at different speeds inside an oven. The commercial antennas were replaced with an RF (radio frequency) coupler and the sensors were interrogated with the commercial interrogation unit. The influence of rotation in the accuracy on the measurements, as well as the adequacy of the sensors structure, was evaluated. It can be concluded that SAW sensors can be used to measure temperature or torque in a rotating environment; however, some customization of the components is required in order to overcome the limitations posed by COTS sensing solutions. Full article

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

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13 pages, 2655 KiB

Open AccessFeature PaperArticle

Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods

by Kuang-Li Lee^1,*, Tsung-Yeh Wu², Hsuan-Yeh Hsu³, Sen-Yeu Yang² and Pei-Kuen Wei^1,*

¹ Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan

² Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan

³ Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan

Sensors 2017, 17(7), 1548; https://doi.org/10.3390/s17071548 - 2 Jul 2017

Cited by 26 | Viewed by 6929

Abstract

We propose two approaches—hot-embossing and dielectric-heating nanoimprinting methods—for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures [...] Read more.

We propose two approaches—hot-embossing and dielectric-heating nanoimprinting methods—for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit). The rapid fabrication is also achieved by using radio-frequency (RF) sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen–antibody interactions using bovine serum albumin (BSA) and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications. Full article

(This article belongs to the Special Issue Micro and Nanofabrication Technologies for Biosensors)

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14 pages, 4613 KiB

Open AccessArticle

Rapid Detection of Ascorbic Acid Based on a Dual-Electrode Sensor System Using a Powder Microelectrode Embedded with Carboxyl Multi-Walled Carbon Nanotubes

by Bao-Shan He^*

and Jun-Xia Zhang

School of Food Science and Technology, Henan University of Technology, Lianhua Road 100#, Zhengzhou 450001, China

Sensors 2017, 17(7), 1549; https://doi.org/10.3390/s17071549 - 2 Jul 2017

Cited by 19 | Viewed by 4689

Abstract

In this paper, carboxyl groups were introduced by liquid oxidation methods onto multi-walled carbon nanotubes (MWCNTs) to improve the MWCNTs’ electrocatalytic properties. A platinum wire microelectrode (ME) was corroded using aqua regia and subsequently embedded with MWCNTs to achieve more active sites, producing [...] Read more.

In this paper, carboxyl groups were introduced by liquid oxidation methods onto multi-walled carbon nanotubes (MWCNTs) to improve the MWCNTs’ electrocatalytic properties. A platinum wire microelectrode (ME) was corroded using aqua regia and subsequently embedded with MWCNTs to achieve more active sites, producing a so-called powder microelectrode (PME). Compared with conventional MEs, the PME has a larger specific surface area and more active sites. When PME was used to detect ascorbic acid (AA), the AA oxidation potential shifted negatively and current peak was visibly increased. The calibration curve obtained for AA was in a range of 5.00 × 10⁻⁶~9.50 × 10⁻⁴ mol·L⁻¹: I_pa(μA) = 3.259 × 10⁻² + 1.801 × 10² C (mol·L⁻¹) under the optimum testing conditions. Moreover, the detection and quantitation limits were confirmed at 4.89 × 10⁻⁷ mol·L⁻¹ and 1.63 × 10⁻⁷ mol·L⁻¹, respectively. When the fabricated PME was practically applied to detect AA, it was shown a recovery rate of 94~107% with relative standard deviation (RSD) <5%. The proposed strategy thus offers a promising, rapid, selective and low-cost approach to effective analysis of AA. Full article

(This article belongs to the Section Chemical Sensors)

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41 pages, 4620 KiB

Open AccessArticle

Performance Analysis of the Direct Position Determination Method in the Presence of Array Model Errors

by Ding Wang^1,2,*

, Hongyi Yu^1,2, Zhidong Wu^1,2 and Cheng Wang^1,2

¹ National Digital Switching System Engineering & Technological Research Center, Zhengzhou 450002, China

² Zhengzhou Information Science and Technology Institute, Zhengzhou 450002, China

Sensors 2017, 17(7), 1550; https://doi.org/10.3390/s17071550 - 2 Jul 2017

Cited by 7 | Viewed by 5093

Abstract

The direct position determination approach was recently presented as a promising technique for the localization of a transmitting source with accuracy higher than that of the conventional two-step localization method. In this paper, the theoretical performance of a direct position determination estimator proposed [...] Read more.

The direct position determination approach was recently presented as a promising technique for the localization of a transmitting source with accuracy higher than that of the conventional two-step localization method. In this paper, the theoretical performance of a direct position determination estimator proposed by Weiss is examined for situations in which the array model errors are present. Our study starts from a matrix eigen-perturbation result, which expresses the perturbation of eigenvalues as a function of the disturbance added to the Hermitian matrix. The first-order asymptotic expression of the positioning errors is presented, from which an analytical expression for the mean square error of the direct localization is available. Additionally, explicit formulas for computing the probabilities of a successful localization are deduced. Finally, Cramér–Rao bound expressions for the position estimation are derived for two cases: (1) array model errors are absent and (2) array model errors are present. The obtained Cramér-Rao bounds provide insights into the effects of the array model errors on the localization accuracy. Simulation results support and corroborate the theoretical developments made in this paper. Full article

(This article belongs to the Special Issue Recent Advances in Array Signal Processing and Its Applications in IoT Security)

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17 pages, 5225 KiB

Open AccessArticle

A Damping Grid Strapdown Inertial Navigation System Based on a Kalman Filter for Ships in Polar Regions

by Weiquan Huang, Tao Fang^*, Li Luo, Lin Zhao and Fengzhu Che

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

Sensors 2017, 17(7), 1551; https://doi.org/10.3390/s17071551 - 3 Jul 2017

Cited by 29 | Viewed by 6664

Abstract

The grid strapdown inertial navigation system (SINS) used in polar navigation also includes three kinds of periodic oscillation errors as common SINS are based on a geographic coordinate system. Aiming ships which have the external information to conduct a system reset regularly, suppressing [...] Read more.

The grid strapdown inertial navigation system (SINS) used in polar navigation also includes three kinds of periodic oscillation errors as common SINS are based on a geographic coordinate system. Aiming ships which have the external information to conduct a system reset regularly, suppressing the Schuler periodic oscillation is an effective way to enhance navigation accuracy. The Kalman filter based on the grid SINS error model which applies to the ship is established in this paper. The errors of grid-level attitude angles can be accurately estimated when the external velocity contains constant error, and then correcting the errors of the grid-level attitude angles through feedback correction can effectively dampen the Schuler periodic oscillation. The simulation results show that with the aid of external reference velocity, the proposed external level damping algorithm based on the Kalman filter can suppress the Schuler periodic oscillation effectively. Compared with the traditional external level damping algorithm based on the damping network, the algorithm proposed in this paper can reduce the overshoot errors when the state of grid SINS is switched from the non-damping state to the damping state, and this effectively improves the navigation accuracy of the system. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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41 pages, 11908 KiB

Open AccessArticle

A Hybrid FPGA-Based System for EEG- and EMG-Based Online Movement Prediction

by Hendrik Wöhrle^1,*, Marc Tabie¹, Su Kyoung Kim¹, Frank Kirchner^1,2 and Elsa Andrea Kirchner^1,2

¹ DFKI GmbH, Robotics Innovation Center (RIC), Robert-Hooke-Str. 1, D-28359 Bremen, Germany

² Robotics Group, Department of Mathematics and Computer Science, University of Bremen, Robert-Hooke-Str. 1, D-28359 Bremen, Germany

Sensors 2017, 17(7), 1552; https://doi.org/10.3390/s17071552 - 3 Jul 2017

Cited by 43 | Viewed by 13417

Abstract

A current trend in the development of assistive devices for rehabilitation, for example exoskeletons or active orthoses, is to utilize physiological data to enhance their functionality and usability, for example by predicting the patient’s upcoming movements using electroencephalography (EEG) or electromyography (EMG). However, [...] Read more.

A current trend in the development of assistive devices for rehabilitation, for example exoskeletons or active orthoses, is to utilize physiological data to enhance their functionality and usability, for example by predicting the patient’s upcoming movements using electroencephalography (EEG) or electromyography (EMG). However, these modalities have different temporal properties and classification accuracies, which results in specific advantages and disadvantages. To use physiological data analysis in rehabilitation devices, the processing should be performed in real-time, guarantee close to natural movement onset support, provide high mobility, and should be performed by miniaturized systems that can be embedded into the rehabilitation device. We present a novel Field Programmable Gate Array (FPGA) -based system for real-time movement prediction using physiological data. Its parallel processing capabilities allows the combination of movement predictions based on EEG and EMG and additionally a P300 detection, which is likely evoked by instructions of the therapist. The system is evaluated in an offline and an online study with twelve healthy subjects in total. We show that it provides a high computational performance and significantly lower power consumption in comparison to a standard PC. Furthermore, despite the usage of fixed-point computations, the proposed system achieves a classification accuracy similar to systems with double precision floating-point precision. Full article

(This article belongs to the Special Issue Sensors and Analytics for Precision Medicine)

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24 pages, 4500 KiB

Open AccessFeature PaperArticle

Acoustic Sensing and Ultrasonic Drug Delivery in Multimodal Theranostic Capsule Endoscopy

by Fraser R. Stewart¹, Yongqiang Qiu²

, Holly S. Lay², Ian P. Newton¹, Benjamin F. Cox³, Mohammed A. Al-Rawhani², James Beeley², Yangminghao Liu⁴, Zhihong Huang⁴, David R. S. Cumming², Inke Näthke¹ and Sandy Cochran^2,*

¹ School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK

² School of Engineering, University of Glasgow, Glasgow G12 8QQ, Scotland, UK

³ School of Medicine, University of Dundee, Dundee DD1 9SY, Scotland, UK

⁴ School of Science and Engineering, University of Dundee, Dundee DD1 4HN, Scotland, UK

Sensors 2017, 17(7), 1553; https://doi.org/10.3390/s17071553 - 3 Jul 2017

Cited by 13 | Viewed by 10267

Abstract

Video capsule endoscopy (VCE) is now a clinically accepted diagnostic modality in which miniaturized technology, an on-board power supply and wireless telemetry stand as technological foundations for other capsule endoscopy (CE) devices. However, VCE does not provide therapeutic functionality, and research towards therapeutic [...] Read more.

Video capsule endoscopy (VCE) is now a clinically accepted diagnostic modality in which miniaturized technology, an on-board power supply and wireless telemetry stand as technological foundations for other capsule endoscopy (CE) devices. However, VCE does not provide therapeutic functionality, and research towards therapeutic CE (TCE) has been limited. In this paper, a route towards viable TCE is proposed, based on multiple CE devices including important acoustic sensing and drug delivery components. In this approach, an initial multimodal diagnostic device with high-frequency quantitative microultrasound that complements video imaging allows surface and subsurface visualization and computer-assisted diagnosis. Using focused ultrasound (US) to mark sites of pathology with exogenous fluorescent agents permits follow-up with another device to provide therapy. This is based on an US-mediated targeted drug delivery system with fluorescence imaging guidance. An additional device may then be utilized for treatment verification and monitoring, exploiting the minimally invasive nature of CE. While such a theranostic patient pathway for gastrointestinal treatment is presently incomplete, the description in this paper of previous research and work under way to realize further components for the proposed pathway suggests it is feasible and provides a framework around which to structure further work. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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21 pages, 2557 KiB

Open AccessArticle

Fuzzy-Logic Based Distributed Energy-Efficient Clustering Algorithm for Wireless Sensor Networks

by Ying Zhang^1,2, Jun Wang^2,*, Dezhi Han¹, Huafeng Wu³ and Rundong Zhou¹

¹ College of Information Engineering, Shanghai Maritime University, Shanghai 201306, China

² Department of Electrical and Computer Engineering, University of Central Florida, Orlando, FL 32816, USA

³ Merchant Marine College, Shanghai Maritime University, Shanghai 201306, China

Sensors 2017, 17(7), 1554; https://doi.org/10.3390/s17071554 - 3 Jul 2017

Cited by 98 | Viewed by 8487

Abstract

Due to the high-energy efficiency and scalability, the clustering routing algorithm has been widely used in wireless sensor networks (WSNs). In order to gather information more efficiently, each sensor node transmits data to its Cluster Head (CH) to which it belongs, by multi-hop [...] Read more.

Due to the high-energy efficiency and scalability, the clustering routing algorithm has been widely used in wireless sensor networks (WSNs). In order to gather information more efficiently, each sensor node transmits data to its Cluster Head (CH) to which it belongs, by multi-hop communication. However, the multi-hop communication in the cluster brings the problem of excessive energy consumption of the relay nodes which are closer to the CH. These nodes’ energy will be consumed more quickly than the farther nodes, which brings the negative influence on load balance for the whole networks. Therefore, we propose an energy-efficient distributed clustering algorithm based on fuzzy approach with non-uniform distribution (EEDCF). During CHs’ election, we take nodes’ energies, nodes’ degree and neighbor nodes’ residual energies into consideration as the input parameters. In addition, we take advantage of Takagi, Sugeno and Kang (TSK) fuzzy model instead of traditional method as our inference system to guarantee the quantitative analysis more reasonable. In our scheme, each sensor node calculates the probability of being as CH with the help of fuzzy inference system in a distributed way. The experimental results indicate EEDCF algorithm is better than some current representative methods in aspects of data transmission, energy consumption and lifetime of networks. Full article

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

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21 pages, 13698 KiB

Open AccessArticle

Landmark-Based Drift Compensation Algorithm for Inertial Pedestrian Navigation

by Estefania Munoz Diaz^*, Maria Caamano and Francisco Javier Fuentes Sánchez

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

Sensors 2017, 17(7), 1555; https://doi.org/10.3390/s17071555 - 3 Jul 2017

Cited by 13 | Viewed by 5150

Abstract

The navigation of pedestrians based on inertial sensors, i.e., accelerometers and gyroscopes, has experienced a great growth over the last years. However, the noise of medium- and low-cost sensors causes a high error in the orientation estimation, particularly in the yaw angle. This [...] Read more.

The navigation of pedestrians based on inertial sensors, i.e., accelerometers and gyroscopes, has experienced a great growth over the last years. However, the noise of medium- and low-cost sensors causes a high error in the orientation estimation, particularly in the yaw angle. This error, called drift, is due to the bias of the z-axis gyroscope and other slow changing errors, such as temperature variations. We propose a seamless landmark-based drift compensation algorithm that only uses inertial measurements. The proposed algorithm adds a great value to the state of the art, because the vast majority of the drift elimination algorithms apply corrections to the estimated position, but not to the yaw angle estimation. Instead, the presented algorithm computes the drift value and uses it to prevent yaw errors and therefore position errors. In order to achieve this goal, a detector of landmarks, i.e., corners and stairs, and an association algorithm have been developed. The results of the experiments show that it is possible to reliably detect corners and stairs using only inertial measurements eliminating the need that the user takes any action, e.g., pressing a button. Associations between re-visited landmarks are successfully made taking into account the uncertainty of the position. After that, the drift is computed out of all associations and used during a post-processing stage to obtain a low-drifted yaw angle estimation, that leads to successfully drift compensated trajectories. The proposed algorithm has been tested with quasi-error-free turn rate measurements introducing known biases and with medium-cost gyroscopes in 3D indoor and outdoor scenarios. Full article

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

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11 pages, 3997 KiB

Open AccessArticle

A Linear Birefringence Measurement Method for an Optical Fiber Current Sensor

by Shaoyi Xu¹, Haiming Shao², Chuansheng Li², Fangfang Xing³, Yuqiao Wang¹ and Wei Li^1,*

¹ School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, China

² National Institute of Metrology (NIM), Beijing 100029, China

³ School of Mechatronic Engineering, Xuzhou College of Industrial Technology, Xuzhou 221116, China

Sensors 2017, 17(7), 1556; https://doi.org/10.3390/s17071556 - 3 Jul 2017

Cited by 11 | Viewed by 5160

Abstract

In this work, a linear birefringence measurement method is proposed for an optical fiber current sensor (OFCS). First, the optical configuration of the measurement system is presented. Then, the elimination method of the effect of the azimuth angles between the sensing fiber and [...] Read more.

In this work, a linear birefringence measurement method is proposed for an optical fiber current sensor (OFCS). First, the optical configuration of the measurement system is presented. Then, the elimination method of the effect of the azimuth angles between the sensing fiber and the two polarizers is demonstrated. Moreover, the relationship of the linear birefringence, the Faraday rotation angle and the final output is determined. On these bases, the multi-valued problem on the linear birefringence is simulated and its solution is illustrated when the linear birefringence is unknown. Finally, the experiments are conducted to prove the feasibility of the proposed method. When the numbers of turns of the sensing fiber in the OFCS are about 15, 19, 23, 27, 31, 35, and 39, the measured linear birefringence obtained by the proposed method are about 1.3577, 1.8425, 2.0983, 2.5914, 2.7891, 3.2003 and 3.5198 rad. Two typical methods provide the references for the proposed method. The proposed method is proven to be suitable for the linear birefringence measurement in the full range without the limitation that the linear birefringence must be smaller than π/2. Full article

(This article belongs to the Section Physical Sensors)

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22 pages, 4506 KiB

Open AccessArticle

Motor Imagery EEG Classification for Patients with Amyotrophic Lateral Sclerosis Using Fractal Dimension and Fisher’s Criterion-Based Channel Selection

by Yi-Hung Liu^1,2,*

, Shiuan Huang¹ and Yi-De Huang¹

¹ Graduate Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

² Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

Sensors 2017, 17(7), 1557; https://doi.org/10.3390/s17071557 - 3 Jul 2017

Cited by 42 | Viewed by 8247

Abstract

Motor imagery is based on the volitional modulation of sensorimotor rhythms (SMRs); however, the sensorimotor processes in patients with amyotrophic lateral sclerosis (ALS) are impaired, leading to degenerated motor imagery ability. Thus, motor imagery classification in ALS patients has been considered challenging in [...] Read more.

Motor imagery is based on the volitional modulation of sensorimotor rhythms (SMRs); however, the sensorimotor processes in patients with amyotrophic lateral sclerosis (ALS) are impaired, leading to degenerated motor imagery ability. Thus, motor imagery classification in ALS patients has been considered challenging in the brain–computer interface (BCI) community. In this study, we address this critical issue by introducing the Grassberger–Procaccia and Higuchi’s methods to estimate the fractal dimensions (GPFD and HFD, respectively) of the electroencephalography (EEG) signals from ALS patients. Moreover, a Fisher’s criterion-based channel selection strategy is proposed to automatically determine the best patient-dependent channel configuration from 30 EEG recording sites. An EEG data collection paradigm is designed to collect the EEG signal of resting state and the imagination of three movements, including right hand grasping (RH), left hand grasping (LH), and left foot stepping (LF). Five late-stage ALS patients without receiving any SMR training participated in this study. Experimental results show that the proposed GPFD feature is not only superior to the previously-used SMR features (mu and beta band powers of EEG from sensorimotor cortex) but also better than HFD. The accuracies achieved by the SMR features are not satisfactory (all lower than 80%) in all binary classification tasks, including RH imagery vs. resting, LH imagery vs. resting, and LF imagery vs. resting. For the discrimination between RH imagery and resting, the average accuracies of GPFD in 30-channel (without channel selection) and top-five-channel configurations are 95.25% and 93.50%, respectively. When using only one channel (the best channel among the 30), a high accuracy of 91.00% can still be achieved by the GPFD feature and a linear discriminant analysis (LDA) classifier. The results also demonstrate that the proposed Fisher’s criterion-based channel selection is capable of removing a large amount of redundant and noisy EEG channels. The proposed GPFD feature extraction combined with the channel selection strategy can be used as the basis for further developing high-accuracy and high-usability motor imagery BCI systems from which the patients with ALS can really benefit. Full article

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

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15 pages, 4295 KiB

Open AccessArticle

Direct Quantification of Cd²⁺ in the Presence of Cu²⁺ by a Combination of Anodic Stripping Voltammetry Using a Bi-Film-Modified Glassy Carbon Electrode and an Artificial Neural Network

by Guo Zhao^1,2, Hui Wang^1,2

and Gang Liu^1,2,*

¹ Key Lab of Modern Precision Agriculture System Integration Research, Ministry of Education of China, China Agricultural University, Beijing 100083, China

² Key Lab of Agricultural Information Acquisition Technology, Ministry of Agricultural of China, China Agricultural University, Beijing 100083, China

Sensors 2017, 17(7), 1558; https://doi.org/10.3390/s17071558 - 3 Jul 2017

Cited by 17 | Viewed by 5788

Abstract

Abstract: In this study, a novel method based on a Bi/glassy carbon electrode (Bi/GCE) for quantitatively and directly detecting Cd²⁺ in the presence of Cu²⁺ without further electrode modifications by combining square-wave anodic stripping voltammetry (SWASV) and a back-propagation artificial [...] Read more.

Abstract: In this study, a novel method based on a Bi/glassy carbon electrode (Bi/GCE) for quantitatively and directly detecting Cd²⁺ in the presence of Cu²⁺ without further electrode modifications by combining square-wave anodic stripping voltammetry (SWASV) and a back-propagation artificial neural network (BP-ANN) has been proposed. The influence of the Cu²⁺ concentration on the stripping response to Cd²⁺ was studied. In addition, the effect of the ferrocyanide concentration on the SWASV detection of Cd²⁺ in the presence of Cu²⁺was investigated. A BP-ANN with two inputs and one output was used to establish the nonlinear relationship between the concentration of Cd²⁺ and the stripping peak currents of Cu²⁺ and Cd²⁺. The factors affecting the SWASV detection of Cd²⁺ and the key parameters of the BP-ANN were optimized. Moreover, the direct calibration model (i.e., adding 0.1 mM ferrocyanide before detection), the BP-ANN model and other prediction models were compared to verify the prediction performance of these models in terms of their mean absolute errors (MAEs), root mean square errors (RMSEs) and correlation coefficients. The BP-ANN model exhibited higher prediction accuracy than the direct calibration model and the other prediction models. Finally, the proposed method was used to detect Cd²⁺ in soil samples with satisfactory results. Full article

(This article belongs to the Section Chemical Sensors)

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24 pages, 1420 KiB

Open AccessArticle

Real-Time Station Grouping under Dynamic Traffic for IEEE 802.11ah

by Le Tian^1,*, Evgeny Khorov²

, Steven Latré¹ and Jeroen Famaey¹

¹ IDLab, Department of Mathematics and Computer Science, University of Antwerp—imec, 2020 Antwerp, Belgium

² Network Protocols Research Lab, Institute for Information Transmission Problems, Russian Academy of Sciences, 127051 Moscow, Russia

Sensors 2017, 17(7), 1559; https://doi.org/10.3390/s17071559 - 4 Jul 2017

Cited by 67 | Viewed by 7583

Abstract

IEEE 802.11ah, marketed as Wi-Fi HaLow, extends Wi-Fi to the sub-1 GHz spectrum. Through a number of physical layer (PHY) and media access control (MAC) optimizations, it aims to bring greatly increased range, energy-efficiency, and scalability. This makes 802.11ah the perfect candidate for [...] Read more.

IEEE 802.11ah, marketed as Wi-Fi HaLow, extends Wi-Fi to the sub-1 GHz spectrum. Through a number of physical layer (PHY) and media access control (MAC) optimizations, it aims to bring greatly increased range, energy-efficiency, and scalability. This makes 802.11ah the perfect candidate for providing connectivity to Internet of Things (IoT) devices. One of these new features, referred to as the Restricted Access Window (RAW), focuses on improving scalability in highly dense deployments. RAW divides stations into groups and reduces contention and collisions by only allowing channel access to one group at a time. However, the standard does not dictate how to determine the optimal RAW grouping parameters. The optimal parameters depend on the current network conditions, and it has been shown that incorrect configuration severely impacts throughput, latency and energy efficiency. In this paper, we propose a traffic-adaptive RAW optimization algorithm (TAROA) to adapt the RAW parameters in real time based on the current traffic conditions, optimized for sensor networks in which each sensor transmits packets with a certain (predictable) frequency and may change the transmission frequency over time. The TAROA algorithm is executed at each target beacon transmission time (TBTT), and it first estimates the packet transmission interval of each station only based on packet transmission information obtained by access point (AP) during the last beacon interval. Then, TAROA determines the RAW parameters and assigns stations to RAW slots based on this estimated transmission frequency. The simulation results show that, compared to enhanced distributed channel access/distributed coordination function (EDCA/DCF), the TAROA algorithm can highly improve the performance of IEEE 802.11ah dense networks in terms of throughput, especially when hidden nodes exist, although it does not always achieve better latency performance. This paper contributes with a practical approach to optimizing RAW grouping under dynamic traffic in real time, which is a major leap towards applying RAW mechanism in real-life IoT networks. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 973 KiB

Open AccessArticle

A Study on Wireless Charging for Prolonging the Lifetime of Wireless Sensor Networks

by Weijian Tu¹, Xianghua Xu^1,*, Tingcong Ye¹ and Zongmao Cheng²

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

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

Sensors 2017, 17(7), 1560; https://doi.org/10.3390/s17071560 - 4 Jul 2017

Cited by 28 | Viewed by 6169

Abstract

Wireless charging is an important issue in wireless sensor networks, since it can provide an emerging and effective solution in the absence of other power supplies. The state-of-the-art methods employ a mobile car and a predefined moving path to charge the sensor nodes [...] Read more.

Wireless charging is an important issue in wireless sensor networks, since it can provide an emerging and effective solution in the absence of other power supplies. The state-of-the-art methods employ a mobile car and a predefined moving path to charge the sensor nodes in the network. Previous studies only consider a factor of the network (i.e., residual energy of sensor node) as a constraint to design the wireless charging strategy. However, other factors, such as the travelled distance of the mobile car, can also affect the effectiveness of wireless charging strategy. In this work, we study wireless charging strategy based on the analysis of a combination of two factors, including the residual energy of sensor nodes and the travelled distance of the charging car. Firstly, we theoretically analyze the limited size of the sensor network to match the capability of a charging car. Then, the networked factors are selected as the weights of traveling salesman problem (TSP) to design the moving path of the charging car. Thirdly, the charging time of each sensor node is computed based on the linear programming problem for the charging car. Finally, a charging period for the network is studied. The experimental results show that the proposed approach can significantly maximize the lifetime of the wireless sensor network. Full article

(This article belongs to the Section Sensor Networks)

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18 pages, 2111 KiB

Open AccessArticle

Experimental Characterization of Close-Emitter Interference in an Optical Camera Communication System

by Patricia Chavez-Burbano^1,*,†, Victor Guerra^2,†

, Jose Rabadan², Dionisio Rodríguez-Esparragón³

and Rafael Perez-Jimenez²

¹ Facultad de Ingeniería en Electricidad y Computación, Escuela Superior Politécnica del Litoral (ESPOL), Campus Gustavo Galindo Km 30.5 Vía Perimetral, P.O. Box 09-01-5863 Guayaquil, Ecuador

² Institute for Technological Development and Innovation in Communications (IDeTIC), ULPG, Las Palmas 35001, Spain

³ Instituto de Oceanografía y Cambio Global (IOCAG), ULPG, Las Palmas 35214, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1561; https://doi.org/10.3390/s17071561 - 4 Jul 2017

Cited by 15 | Viewed by 6002

Abstract

Due to the massive insertion of embedded cameras in a wide variety of devices and the generalized use of LED lamps, Optical Camera Communication (OCC) has been proposed as a practical solution for future Internet of Things (IoT) and smart cities applications. Influence [...] Read more.

Due to the massive insertion of embedded cameras in a wide variety of devices and the generalized use of LED lamps, Optical Camera Communication (OCC) has been proposed as a practical solution for future Internet of Things (IoT) and smart cities applications. Influence of mobility, weather conditions, solar radiation interference, and external light sources over Visible Light Communication (VLC) schemes have been addressed in previous works. Some authors have studied the spatial intersymbol interference from close emitters within an OCC system; however, it has not been characterized or measured in function of the different transmitted wavelengths. In this work, this interference has been experimentally characterized and the Normalized Power Signal to Interference Ratio (NPSIR) for easily determining the interference in other implementations, independently of the selected system devices, has been also proposed. A set of experiments in a darkroom, working with RGB multi-LED transmitters and a general purpose camera, were performed in order to obtain the NPSIR values and to validate the deduced equations for 2D pixel representation of real distances. These parameters were used in the simulation of a wireless sensor network scenario in a small office, where the Bit Error Rate (BER) of the communication link was calculated. The experiments show that the interference of other close emitters in terms of the distance and the used wavelength can be easily determined with the NPSIR. Finally, the simulation validates the applicability of the deduced equations for scaling the initial results into real scenarios. Full article

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

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20 pages, 865 KiB

Open AccessArticle

An RFID-Based Smart Structure for the Supply Chain: Resilient Scanning Proofs and Ownership Transfer with Positive Secrecy Capacity Channels

by Mike Burmester¹

, Jorge Munilla^2,*

, Andrés Ortiz²

and Pino Caballero-Gil³

¹ Department of Computer Science, Florida State University, Tallahassee, FL 32304, USA

² Escuela Técnica Superior de Ingenieros de Telecomunicación, Universidad de Málaga, 29070 Málaga, Spain

³ Facultad de Ciencias, Departamento de Ingeniería de Informática y de Sistemas, Universidad de La Laguna, 38271 Tenerife, Spain

Sensors 2017, 17(7), 1562; https://doi.org/10.3390/s17071562 - 4 Jul 2017

Cited by 17 | Viewed by 5775

Abstract

The National Strategy for Global Supply Chain Security published in 2012 by the White House identifies two primary goals for strengthening global supply chains: first, to promote the efficient and secure movement of goods, and second to foster a resilient supply chain. The [...] Read more.

The National Strategy for Global Supply Chain Security published in 2012 by the White House identifies two primary goals for strengthening global supply chains: first, to promote the efficient and secure movement of goods, and second to foster a resilient supply chain. The Internet of Things (IoT), and in particular Radio Frequency Identification (RFID) technology, can be used to realize these goals. For product identification, tracking and real-time awareness, RFID tags are attached to goods. As tagged goods move along the supply chain from the suppliers to the manufacturers, and then on to the retailers until eventually they reach the customers, two major security challenges can be identified: (I) to protect the shipment of goods that are controlled by potentially untrusted carriers; and (II) to secure the transfer of ownership at each stage of the chain. For the former, grouping proofs in which the tags of the scanned goods generate a proof of “simulatenous” presence can be employed, while for the latter, ownership transfer protocols (OTP) are used. This paper describes enhanced security solutions for both challenges. We first extend earlier work on grouping proofs and group codes to capture resilient group scanning with untrusted readers; then, we describe a modified version of a recently published OTP based on channels with positive secrecy capacity adapted to be implemented on common RFID systems in the supply chain. The proposed solutions take into account the limitations of low cost tags employed in the supply chain, which are only required to generate pseudorandom numbers and compute one-way hash functions. Full article

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

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13 pages, 2482 KiB

Open AccessArticle

A Microfluidic pH Measurement Device with a Flowing Liquid Junction

by Akira Yamada^* and Miho Suzuki

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

Sensors 2017, 17(7), 1563; https://doi.org/10.3390/s17071563 - 4 Jul 2017

Cited by 11 | Viewed by 6400

Abstract

The pH values of aqueous solutions are conventionally measured with pH-sensitive electrodes such as glass electrodes or ion-sensitive field-effect transistors (ISFETs) used in conjunction with Ag/AgCl reference electrodes and KCl solutions. The speed of pH measurement with these systems can be deficient, however, [...] Read more.

The pH values of aqueous solutions are conventionally measured with pH-sensitive electrodes such as glass electrodes or ion-sensitive field-effect transistors (ISFETs) used in conjunction with Ag/AgCl reference electrodes and KCl solutions. The speed of pH measurement with these systems can be deficient, however, as the glass electrode responds slowly during measurements of sample solutions with low buffering capacities. Our group has constructed a new pH measurement system using a microfluidic device and ISFET sensors. The device has a channel with two inlets and one outlet, with a junction connected to a Y-shaped channel on the same plane. Two ISFET sensors and an Ag/AgCl pseudo reference electrode are fitted into the channel to construct a differential measurement device. A sample solution and baseline solution supplied into the inlets by gravity-driven pumps form a flowing liquid junction during measurement. The small size and fast response of the ISFET sensors enable measurement of about 2.0 mL of sample solution over a measurement period of 120 s. The 90% response time is within 2 s. The calibrated sensor signal exhibits a wide range (pH 1.68–10.0) of linearity with a correlation factor of 0.9997. The measurement error for all solutions tested, including diluted solutions, was 0.0343 ± 0.0974 pH (average error ± standard deviation (S.D.), n = 42). The new device developed in this research will serve as an innovative technology in the field of potentiometry. Full article

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

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21 pages, 11985 KiB

Open AccessArticle

Unsupervised Fault Diagnosis of a Gear Transmission Chain Using a Deep Belief Network

by Jun He^1,2, Shixi Yang^1,2,* and Chunbiao Gan^1,2

¹ The State Key Laboratory of Fluid Power and Mechatronic Systems, College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China

² The Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province, College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China

Sensors 2017, 17(7), 1564; https://doi.org/10.3390/s17071564 - 4 Jul 2017

Cited by 76 | Viewed by 6630

Abstract

Artificial intelligence (AI) techniques, which can effectively analyze massive amounts of fault data and automatically provide accurate diagnosis results, have been widely applied to fault diagnosis of rotating machinery. Conventional AI methods are applied using features selected by a human operator, which are [...] Read more.

Artificial intelligence (AI) techniques, which can effectively analyze massive amounts of fault data and automatically provide accurate diagnosis results, have been widely applied to fault diagnosis of rotating machinery. Conventional AI methods are applied using features selected by a human operator, which are manually extracted based on diagnostic techniques and field expertise. However, developing robust features for each diagnostic purpose is often labour-intensive and time-consuming, and the features extracted for one specific task may be unsuitable for others. In this paper, a novel AI method based on a deep belief network (DBN) is proposed for the unsupervised fault diagnosis of a gear transmission chain, and the genetic algorithm is used to optimize the structural parameters of the network. Compared to the conventional AI methods, the proposed method can adaptively exploit robust features related to the faults by unsupervised feature learning, thus requires less prior knowledge about signal processing techniques and diagnostic expertise. Besides, it is more powerful at modelling complex structured data. The effectiveness of the proposed method is validated using datasets from rolling bearings and gearbox. To show the superiority of the proposed method, its performance is compared with two well-known classifiers, i.e., back propagation neural network (BPNN) and support vector machine (SVM). The fault classification accuracies are 99.26% for rolling bearings and 100% for gearbox when using the proposed method, which are much higher than that of the other two methods. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2777 KiB

Open AccessArticle

A Frequency-Domain Adaptive Matched Filter for Active Sonar Detection

by Zhishan Zhao^1,2, Anbang Zhao^1,2,*, Juan Hui^1,2,*, Baochun Hou³, Reza Sotudeh³ and Fang Niu^1,2

¹ Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin 150001, China

² College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China

³ School of Engineering and Technology, University of Hertfordshire, Hatfield AL10 9AB, UK

Sensors 2017, 17(7), 1565; https://doi.org/10.3390/s17071565 - 4 Jul 2017

Cited by 24 | Viewed by 6439

Abstract

The most classical detector of active sonar and radar is the matched filter (MF), which is the optimal processor under ideal conditions. Aiming at the problem of active sonar detection, we propose a frequency-domain adaptive matched filter (FDAMF) with the use of a [...] Read more.

The most classical detector of active sonar and radar is the matched filter (MF), which is the optimal processor under ideal conditions. Aiming at the problem of active sonar detection, we propose a frequency-domain adaptive matched filter (FDAMF) with the use of a frequency-domain adaptive line enhancer (ALE). The FDAMF is an improved MF. In the simulations in this paper, the signal to noise ratio (SNR) gain of the FDAMF is about 18.6 dB higher than that of the classical MF when the input SNR is −10 dB. In order to improve the performance of the FDAMF with a low input SNR, we propose a pre-processing method, which is called frequency-domain time reversal convolution and interference suppression (TRC-IS). Compared with the classical MF, the FDAMF combined with the TRC-IS method obtains higher SNR gain, a lower detection threshold, and a better receiver operating characteristic (ROC) in the simulations in this paper. The simulation results show that the FDAMF has higher processing gain and better detection performance than the classical MF under ideal conditions. The experimental results indicate that the FDAMF does improve the performance of the MF, and can adapt to actual interference in a way. In addition, the TRC-IS preprocessing method works well in an actual noisy ocean environment. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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19 pages, 358 KiB

Open AccessArticle

Joint Transmit Power Allocation and Splitting for SWIPT Aided OFDM-IDMA in Wireless Sensor Networks

by Shanshan Li¹, Xiaotian Zhou^1,*, Cheng-Xiang Wang², Dongfeng Yuan¹ and Wensheng Zhang¹

¹ Shandong Provincial Key Laboratory of Wireless Communication Technologies, School of Information Science and Engineering, Shandong University, Jinan 250100, China

² Institute of Sensors, Signals and Systems, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK

Sensors 2017, 17(7), 1566; https://doi.org/10.3390/s17071566 - 4 Jul 2017

Cited by 12 | Viewed by 5545

Abstract

In this paper, we propose to combine Orthogonal Frequency Division Multiplexing-Interleave Division Multiple Access (OFDM-IDMA) with Simultaneous Wireless Information and Power Transfer (SWIPT), resulting in SWIPT aided OFDM-IDMA scheme for power-limited sensor networks. In the proposed system, the Receive Node (RN) applies Power [...] Read more.

In this paper, we propose to combine Orthogonal Frequency Division Multiplexing-Interleave Division Multiple Access (OFDM-IDMA) with Simultaneous Wireless Information and Power Transfer (SWIPT), resulting in SWIPT aided OFDM-IDMA scheme for power-limited sensor networks. In the proposed system, the Receive Node (RN) applies Power Splitting (PS) to coordinate the Energy Harvesting (EH) and Information Decoding (ID) process, where the harvested energy is utilized to guarantee the iterative Multi-User Detection (MUD) of IDMA to work under sufficient number of iterations. Our objective is to minimize the total transmit power of Source Node (SN), while satisfying the requirements of both minimum harvested energy and Bit Error Rate (BER) performance from individual receive nodes. We formulate such a problem as a joint power allocation and splitting one, where the iteration number of MUD is also taken into consideration as the key parameter to affect both EH and ID constraints. To solve it, a sub-optimal algorithm is proposed to determine the power profile, PS ratio and iteration number of MUD in an iterative manner. Simulation results verify that the proposed algorithm can provide significant performance improvement. Full article

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

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17 pages, 3770 KiB

Open AccessArticle

A Modified Differential Coherent Bit Synchronization Algorithm for BeiDou Weak Signals with Large Frequency Deviation

by Zhifeng Han^*

, Jianye Liu, Rongbing Li, Qinghua Zeng

and Yi Wang

College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China

Sensors 2017, 17(7), 1568; https://doi.org/10.3390/s17071568 - 4 Jul 2017

Cited by 2 | Viewed by 4180

Abstract

BeiDou system navigation messages are modulated with a secondary NH (Neumann-Hoffman) code of 1 kbps, where frequent bit transitions limit the coherent integration time to 1 millisecond. Therefore, a bit synchronization algorithm is necessary to obtain bit edges and NH code phases. In [...] Read more.

BeiDou system navigation messages are modulated with a secondary NH (Neumann-Hoffman) code of 1 kbps, where frequent bit transitions limit the coherent integration time to 1 millisecond. Therefore, a bit synchronization algorithm is necessary to obtain bit edges and NH code phases. In order to realize bit synchronization for BeiDou weak signals with large frequency deviation, a bit synchronization algorithm based on differential coherent and maximum likelihood is proposed. Firstly, a differential coherent approach is used to remove the effect of frequency deviation, and the differential delay time is set to be a multiple of bit cycle to remove the influence of NH code. Secondly, the maximum likelihood function detection is used to improve the detection probability of weak signals. Finally, Monte Carlo simulations are conducted to analyze the detection performance of the proposed algorithm compared with a traditional algorithm under the CN0s of 20~40 dB-Hz and different frequency deviations. The results show that the proposed algorithm outperforms the traditional method with a frequency deviation of 50 Hz. This algorithm can remove the effect of BeiDou NH code effectively and weaken the influence of frequency deviation. To confirm the feasibility of the proposed algorithm, real data tests are conducted. The proposed algorithm is suitable for BeiDou weak signal bit synchronization with large frequency deviation. Full article

(This article belongs to the Section Remote Sensors)

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16 pages, 12109 KiB

Open AccessArticle

Build a Robust Learning Feature Descriptor by Using a New Image Visualization Method for Indoor Scenario Recognition

by Jichao Jiao^*

, Xin Wang and Zhongliang Deng

School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China

Sensors 2017, 17(7), 1569; https://doi.org/10.3390/s17071569 - 4 Jul 2017

Cited by 6 | Viewed by 4463

Abstract

In order to recognize indoor scenarios, we extract image features for detecting objects, however, computers can make some unexpected mistakes. After visualizing the histogram of oriented gradient (HOG) features, we find that the world through the eyes of a computer is indeed different [...] Read more.

In order to recognize indoor scenarios, we extract image features for detecting objects, however, computers can make some unexpected mistakes. After visualizing the histogram of oriented gradient (HOG) features, we find that the world through the eyes of a computer is indeed different from human eyes, which assists researchers to see the reasons that cause a computer to make errors. Additionally, according to the visualization, we notice that the HOG features can obtain rich texture information. However, a large amount of background interference is also introduced. In order to enhance the robustness of the HOG feature, we propose an improved method for suppressing the background interference. On the basis of the original HOG feature, we introduce a principal component analysis (PCA) to extract the principal components of the image colour information. Then, a new hybrid feature descriptor, which is named HOG–PCA (HOGP), is made by deeply fusing these two features. Finally, the HOGP is compared to the state-of-the-art HOG feature descriptor in four scenes under different illumination. In the simulation and experimental tests, the qualitative and quantitative assessments indicate that the visualizing images of the HOGP feature are close to the observation results obtained by human eyes, which is better than the original HOG feature for object detection. Furthermore, the runtime of our proposed algorithm is hardly increased in comparison to the classic HOG feature. Full article

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

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16 pages, 7797 KiB

Open AccessArticle

Monitoring-Based Model for Personalizing the Clinical Process of Crohn’s Disease

by Alberto De Ramón-Fernández, Daniel Ruiz-Fernández^*

, Diego Marcos-Jorquera

, Virgilio Gilart-Iglesias

and Víctor Vives-Boix

Department of Computer Technology, University of Alicante, Alicante 03690, Spain

Sensors 2017, 17(7), 1570; https://doi.org/10.3390/s17071570 - 5 Jul 2017

Cited by 1 | Viewed by 6442

Abstract

Crohn’s disease is a chronic pathology belonging to the group of inflammatory bowel diseases. Patients suffering from Crohn’s disease must be supervised by a medical specialist for the rest of their lives; furthermore, each patient has its own characteristics and is affected by [...] Read more.

Crohn’s disease is a chronic pathology belonging to the group of inflammatory bowel diseases. Patients suffering from Crohn’s disease must be supervised by a medical specialist for the rest of their lives; furthermore, each patient has its own characteristics and is affected by the disease in a different way, so health recommendations and treatments cannot be generalized and should be individualized for a specific patient. To achieve this personalization in a cost-effective way using technology, we propose a model based on different information flows: control, personalization, and monitoring. As a result of the model and to perform a functional validation, an architecture based on services and a prototype of the system has been defined. In this prototype, a set of different devices and technologies to monitor variables from patients and their environment has been integrated. Artificial intelligence algorithms are also included to reduce the workload related to the review and analysis of the information gathered. Due to the continuous and automated monitoring of the Crohn’s patient, this proposal can help in the personalization of the Crohn’s disease clinical process. Full article

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

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12 pages, 3785 KiB

Open AccessArticle

A Stretchable Pressure-Sensitive Array Based on Polymer Matrix

by Yuanzheng Luo, Qi Xiao and Buyin Li^*

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

Sensors 2017, 17(7), 1571; https://doi.org/10.3390/s17071571 - 5 Jul 2017

Cited by 19 | Viewed by 6615

Abstract

Herein, a flexible 6 × 6 pressure-sensitive array (based on the PDMS (Polydimethylsiloxane) porous substrate) was designed. We have developed a facile method to fabricate the porous substrate, by a single-step operation using the sugar-template method. This strategy effectively diminishes the complexity of [...] Read more.

Herein, a flexible 6 × 6 pressure-sensitive array (based on the PDMS (Polydimethylsiloxane) porous substrate) was designed. We have developed a facile method to fabricate the porous substrate, by a single-step operation using the sugar-template method. This strategy effectively diminishes the complexity of the preparation process, as well as the device structure. The electrical resistivity of the stretchable array demonstrates the negative piezo resistive coefficient (NPRC) under 0–100 kpa. Moreover, the pressure-sensitive array reveals a high sensitivity and low delay time (<0.5 s) to the applied forces. Therefore, the pressure distribution could be easily recognized by testing its conductivity changes. Besides, these signal data can be collected into the upper computer, with the purpose of tracking and analyzing the azimuth of the applied loading. This cost-effective micro array has a broad application prospect for fabricating the tactile sensor, artificial skin, and human-computer interfaces. Full article

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

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26 pages, 1784 KiB

Open AccessArticle

MPH-M, AODV-M and DSR-M Performance Evaluation under Jamming Attacks

by Carolina Del-Valle-Soto^1,*,†, Carlos Mex-Perera^2,†, Raul Monroy^3,† and Juan A. Nolazco-Flores^4,†

¹ Universidad Panamericana. Facultad de Ingeniería. Prolongación Calzada Circunvalación Poniente 49, Zapopan, Jalisco 45010, Mexico

² Telemática Telemetría y Radiofrecuencia, Francia 1717, Col. Moderna, Guadalajara 44190, Mexico

³ Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Estado de México, Carretera al lago de Guadalupe Km 3.5, Col. Margarita M. de Juárez, Atizapán 52926, Mexico

⁴ Department of Electrical and Computer Engineering, Tecnológico de Monterrey, Ave. Eugenio Garza Sada #2501 Sur, Monterrey 64849, Mexico

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1573; https://doi.org/10.3390/s17071573 - 5 Jul 2017

Cited by 13 | Viewed by 6095

Abstract

In this work, we present the design of a mitigation scheme for jamming attacks integrated to the routing protocols MPH, AODV, and DSR. The resulting protocols are named MPH-M (Multi-Parent Hierarchical - Modified), AODV-M (Ad hoc On Demand Distance Vector - Modified), and [...] Read more.

In this work, we present the design of a mitigation scheme for jamming attacks integrated to the routing protocols MPH, AODV, and DSR. The resulting protocols are named MPH-M (Multi-Parent Hierarchical - Modified), AODV-M (Ad hoc On Demand Distance Vector - Modified), and DSR-M (Dynamic Source Routing - Modified). For the mitigation algorithm, if the detection algorithm running locally in each node produces a positive result then the node is isolated; second, the routing protocol adapts their paths avoiding the isolated nodes. We evaluated how jamming attacks affect different metrics for all these modified protocols. The metrics we employ to detect jamming attack are number of packet retransmissions, number of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) retries while waiting for an idle channel and the energy wasted by the node. The metrics to evaluate the performance of the modified routing protocols are the throughput and resilience of the system and the energy used by the nodes. We evaluated all the modified protocols when the attacker position was set near, middle and far of the collector node. The results of our evaluation show that performance for MPH-M is much better than AODV-M and DSR-M. For example, the node energy for MPH-M is 138.13% better than AODV-M and 126.07% better than DSR-M. Moreover, we also find that MPH-M benefits much more of the mitigation scheme than AODV-M and DSR-M. For example, the node energy consumption is 34.61% lower for MPH-M and only 3.92% and 3.42% for AODV-M and DSR-M, respectively. On throughput, the MPH protocol presents a packet reception efficiency at the collector node of 16.4% on to AODV and DSR when there is no mitigation mechanism. Moreover, MPH-M has an efficiency greater than 7.7% with respect to AODV-M and DSR-M when there is a mitigation scheme. In addition, we have that with the mitigation mechanism AODV-M and DSR-M do not present noticeable modification. However, MPH-M improves its efficiency by 8.4%. We also measure the resilience of these algorithms from the average packet re-transmissions perspective, and we find that MPH-M has around a 15% lower change rate than AODV-M and DSR-M. The MPH-M recovery time is 5 s faster than AODV-M and 2 s faster than DSR-M. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 651 KiB

Open AccessArticle

A Smart and Balanced Energy-Efficient Multihop Clustering Algorithm (Smart-BEEM) for MIMO IoT Systems in Future Networks ^†

by Lina Xu^1,*

, Gregory M. P. O’Hare^1,2 and Rem Collier¹

¹ School of Computer Science, University College Dublin, Belfield, Dublin 4, Ireland

² CONSUS (Crop OptimisatioN through Sensing, Understanding & viSualisation), University College Dublin, Belfield, Dublin 4, Ireland

Sensors 2017, 17(7), 1574; https://doi.org/10.3390/s17071574 - 5 Jul 2017

Cited by 54 | Viewed by 7142

Abstract

Wireless Sensor Networks (WSNs) are typically composed of thousands of sensors powered by limited energy resources. Clustering techniques were introduced to prolong network longevity offering the promise of green computing. However, most existing work fails to consider the network coverage when evaluating the [...] Read more.

Wireless Sensor Networks (WSNs) are typically composed of thousands of sensors powered by limited energy resources. Clustering techniques were introduced to prolong network longevity offering the promise of green computing. However, most existing work fails to consider the network coverage when evaluating the lifetime of a network. We believe that balancing the energy consumption in per unit area rather than on each single sensor can provide better-balanced power usage throughout the network. Our former work—Balanced Energy-Efficiency (BEE) and its Multihop version BEEM can not only extend the network longevity, but also maintain the network coverage. Following WSNs, Internet of Things (IoT) technology has been proposed with higher degree of diversities in terms of communication abilities and user scenarios, supporting a large range of real world applications. The IoT devices are embedded with multiple communication interfaces, normally referred as Multiple-In and Multiple-Out (MIMO) in 5G networks. The applications running on those devices can generate various types of data. Every interface has its own characteristics, which may be preferred and beneficial in some specific user scenarios. With MIMO becoming more available on the IoT devices, an advanced clustering solution for highly dynamic IoT systems is missing and also pressingly demanded in order to cater for differing user applications. In this paper, we present a smart clustering algorithm (Smart-BEEM) based on our former work BEE(M) to accomplish energy efficient and Quality of user Experience (QoE) supported communication in cluster based IoT networks. It is a user behaviour and context aware approach, aiming to facilitate IoT devices to choose beneficial communication interfaces and cluster headers for data transmission. Experimental results have proved that Smart-BEEM can further improve the performance of BEE and BEEM for coverage sensitive longevity. Full article

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

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20 pages, 1264 KiB

Open AccessArticle

A Reliability-Based Method to Sensor Data Fusion

by Wen Jiang^*

, Miaoyan Zhuang and Chunhe Xie

School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(7), 1575; https://doi.org/10.3390/s17071575 - 5 Jul 2017

Cited by 27 | Viewed by 5915

Abstract

Multi-sensor data fusion technology based on Dempster–Shafer evidence theory is widely applied in many fields. However, how to determine basic belief assignment (BBA) is still an open issue. The existing BBA methods pay more attention to the uncertainty of information, but do not [...] Read more.

Multi-sensor data fusion technology based on Dempster–Shafer evidence theory is widely applied in many fields. However, how to determine basic belief assignment (BBA) is still an open issue. The existing BBA methods pay more attention to the uncertainty of information, but do not simultaneously consider the reliability of information sources. Real-world information is not only uncertain, but also partially reliable. Thus, uncertainty and partial reliability are strongly associated with each other. To take into account this fact, a new method to represent BBAs along with their associated reliabilities is proposed in this paper, which is named reliability-based BBA. Several examples are carried out to show the validity of the proposed method. Full article

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

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10 pages, 8690 KiB

Open AccessArticle

Multiport Circular Polarized RFID-Tag Antenna for UHF Sensor Applications

by Jamal Zaid^1,*, Abdulhadi Abdulhadi¹, Arun Kesavan¹, Yassin Belaizi² and Tayeb A. Denidni¹

¹ Institut National de la Recherche Scientifique Centre Centre Énergie Matériaux Télécommunications 800, De La Gauchetière Ouest Bureau 6900, Montréal, QC H5A 1K6, Canada

² IES-UMR CNRS 5214 Université de Montpellier, 34095 Montpellier Cedex 5, France

Sensors 2017, 17(7), 1576; https://doi.org/10.3390/s17071576 - 5 Jul 2017

Cited by 16 | Viewed by 7644

Abstract

A circular polarized patch antenna for UHF RFID tag-based sensor applications is presented, with the circular polarization (CP) generated by a new antenna shape, an asymmetric stars shaped slotted microstrip patch antenna (CP-ASSSMP). Four stars etched on the patch allow the antenna’s size [...] Read more.

A circular polarized patch antenna for UHF RFID tag-based sensor applications is presented, with the circular polarization (CP) generated by a new antenna shape, an asymmetric stars shaped slotted microstrip patch antenna (CP-ASSSMP). Four stars etched on the patch allow the antenna’s size to be reduced by close to 20%. The proposed antenna is matched with two RFID chips via inductive-loop matching. The first chip is connected to a resistive sensor and acts as a sensor node, and the second is used as a reference node. The proposed antenna is used for two targets, serving as both reference and sensor simultaneously, thereby eliminating the need for a second antenna. Its reader can read the RFID chips at any orientation of the tag due to the CP. The measured reading range is about 25 m with mismatch polarization. The operating frequency band is 902–929 MHz for the two ports, which is covered by the US RFID band, and the axial-ratio bandwidth is about 7 MHz. In addition, the reader can also detect temperature, based on the minimum difference in the power required by the reference and sensor. Full article

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

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7 pages, 1377 KiB

Open AccessArticle

CeO₂ Enhanced Ethanol Sensing Performance in a CdS Gas Sensor

by Meishan Li¹, Wei Ren², Rong Wu¹ and Min Zhang^1,*

¹ The School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China

² Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry, CAS, Urumqi 830011, China

Sensors 2017, 17(7), 1577; https://doi.org/10.3390/s17071577 - 5 Jul 2017

Cited by 28 | Viewed by 6440

Abstract

CdS nanowires (NWs) were fabricated through a facile low-temperature solvothermal method, following which CeO₂ nanoparticles were modified on the NWs. The ethanol sensing characteristics of pure CdS and decorated ones with different CeO₂ content were studied. It was found that the [...] Read more.

CdS nanowires (NWs) were fabricated through a facile low-temperature solvothermal method, following which CeO₂ nanoparticles were modified on the NWs. The ethanol sensing characteristics of pure CdS and decorated ones with different CeO₂ content were studied. It was found that the sensing performance of CdS was significantly improved after CeO₂ decoration. In particular, the 5 at% CeO₂/CdS composite exhibited a much higher response to 100 ppm ethanol (about 52), which was 2.6 times larger than that of pure CdS. A fast response and recovery time (less than 12 s and 3 s, respectively) were obtained as well as an excellent selectivity. These results make the CeO₂-decorated CdS NWs good candidates for ethanol sensing applications. Full article

(This article belongs to the Collection Gas Sensors)

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19 pages, 4064 KiB

Open AccessArticle

Fast Vessel Detection in Gaofen-3 SAR Images with Ultrafine Strip-Map Mode

by Zongxu Pan^1,2,*

, Lei Liu^1,2, Xiaolan Qiu^1,2

and Bin Lei^1,2

¹ Key Laboratory of Technology in Geo-Spatial Information Processing and Application System, Chinese Academy of Sciences, Beijing 100190, China

² Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

Sensors 2017, 17(7), 1578; https://doi.org/10.3390/s17071578 - 5 Jul 2017

Cited by 34 | Viewed by 6098

Abstract

This study aims to detect vessels with lengths ranging from about 70 to 300 m, in Gaofen-3 (GF-3) SAR images with ultrafine strip-map (UFS) mode as fast as possible. Based on the analysis of the characteristics of vessels in GF-3 SAR imagery, an [...] Read more.

This study aims to detect vessels with lengths ranging from about 70 to 300 m, in Gaofen-3 (GF-3) SAR images with ultrafine strip-map (UFS) mode as fast as possible. Based on the analysis of the characteristics of vessels in GF-3 SAR imagery, an effective vessel detection method is proposed in this paper. Firstly, the iterative constant false alarm rate (CFAR) method is employed to detect the potential ship pixels. Secondly, the mean-shift operation is applied on each potential ship pixel to identify the candidate target region. During the mean-shift process, we maintain a selection matrix recording which pixels can be taken, and these pixels are called as the valid points of the candidate target. The

l_{1}

norm regression is used to extract the principal axis and detect the valid points. Finally, two kinds of false alarms, the bright line and the azimuth ambiguity, are removed by comparing the valid area of the candidate target with a pre-defined value and computing the displacement between the true target and the corresponding replicas respectively. Experimental results on three GF-3 SAR images with UFS mode demonstrate the effectiveness and efficiency of the proposed method. Full article

(This article belongs to the Special Issue First Experiences with Chinese Gaofen-3 SAR Sensor)

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24 pages, 10704 KiB

Open AccessFeature PaperArticle

Characterization of Signal Quality Monitoring Techniques for Multipath Detection in GNSS Applications

by Ali Pirsiavash^*

, Ali Broumandan and Gérard Lachapelle

Position, Location and Navigation (PLAN) Group, Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(7), 1579; https://doi.org/10.3390/s17071579 - 5 Jul 2017

Cited by 34 | Viewed by 6363

Abstract

The performance of Signal Quality Monitoring (SQM) techniques under different multipath scenarios is analyzed. First, SQM variation profiles are investigated as critical requirements in evaluating the theoretical performance of SQM metrics. The sensitivity and effectiveness of SQM approaches for multipath detection and mitigation [...] Read more.

The performance of Signal Quality Monitoring (SQM) techniques under different multipath scenarios is analyzed. First, SQM variation profiles are investigated as critical requirements in evaluating the theoretical performance of SQM metrics. The sensitivity and effectiveness of SQM approaches for multipath detection and mitigation are then defined and analyzed by comparing SQM profiles and multipath error envelopes for different discriminators. Analytical discussions includes two discriminator strategies, namely narrow and high resolution correlator techniques for BPSK(1), and BOC(1,1) signaling schemes. Data analysis is also carried out for static and kinematic scenarios to validate the SQM profiles and examine SQM performance in actual multipath environments. Results show that although SQM is sensitive to medium and long-delay multipath, its effectiveness in mitigating these ranges of multipath errors varies based on tracking strategy and signaling scheme. For short-delay multipath scenarios, the multipath effect on pseudorange measurements remains mostly undetected due to the low sensitivity of SQM metrics. Full article

(This article belongs to the Section Remote Sensors)

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9 pages, 2560 KiB

Open AccessArticle

Novel Selective Detection Method of Tumor Angiogenesis Factors Using Living Nano-Robots

by Mohamed Al-Fandi^1,3,*

, Nida Alshraiedeh², Rami Oweis¹, Hala Alshdaifat³, Omamah Al-Mahaseneh³, Khadijah Al-Tall³ and Rawan Alawneh³

¹ Nanotechnology Institute, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan

² Faculty of Pharmacy, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan

³ Micro and Nano Systems Lab., Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan

Sensors 2017, 17(7), 1580; https://doi.org/10.3390/s17071580 - 14 Jul 2017

Cited by 16 | Viewed by 5759

Abstract

This paper reports a novel self-detection method for tumor cells using living nano-robots. These living robots are a nonpathogenic strain of E. coli bacteria equipped with naturally synthesized bio-nano-sensory systems that have an affinity to VEGF, an angiogenic factor overly-expressed by cancer cells. [...] Read more.

This paper reports a novel self-detection method for tumor cells using living nano-robots. These living robots are a nonpathogenic strain of E. coli bacteria equipped with naturally synthesized bio-nano-sensory systems that have an affinity to VEGF, an angiogenic factor overly-expressed by cancer cells. The VEGF-affinity/chemotaxis was assessed using several assays including the capillary chemotaxis assay, chemotaxis assay on soft agar, and chemotaxis assay on solid agar. In addition, a microfluidic device was developed to possibly discover tumor cells through the overexpressed vascular endothelial growth factor (VEGF). Various experiments to study the sensing characteristic of the nano-robots presented a strong response toward the VEGF. Thus, a new paradigm of selective targeting therapies for cancer can be advanced using swimming E. coli as self-navigator miniaturized robots as well as drug-delivery vehicles. Full article

(This article belongs to the Special Issue Biosensors for Cancer Biomarkers)

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17 pages, 7748 KiB

Open AccessArticle

Symbiotic Navigation in Multi-Robot Systems with Remote Obstacle Knowledge Sharing

by Abhijeet Ravankar^*, Ankit A. Ravankar

, Yukinori Kobayashi and Takanori Emaru

Faculty of Engineering, Lab of Robotics and Dynamics, Hokkaido University, Sapporo 060-8628, Japan

Sensors 2017, 17(7), 1581; https://doi.org/10.3390/s17071581 - 5 Jul 2017

Cited by 36 | Viewed by 6581

Abstract

Large scale operational areas often require multiple service robots for coverage and task parallelism. In such scenarios, each robot keeps its individual map of the environment and serves specific areas of the map at different times. We propose a knowledge sharing mechanism for [...] Read more.

Large scale operational areas often require multiple service robots for coverage and task parallelism. In such scenarios, each robot keeps its individual map of the environment and serves specific areas of the map at different times. We propose a knowledge sharing mechanism for multiple robots in which one robot can inform other robots about the changes in map, like path blockage, or new static obstacles, encountered at specific areas of the map. This symbiotic information sharing allows the robots to update remote areas of the map without having to explicitly navigate those areas, and plan efficient paths. A node representation of paths is presented for seamless sharing of blocked path information. The transience of obstacles is modeled to track obstacles which might have been removed. A lazy information update scheme is presented in which only relevant information affecting the current task is updated for efficiency. The advantages of the proposed method for path planning are discussed against traditional method with experimental results in both simulation and real environments. Full article

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

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16 pages, 2585 KiB

Open AccessArticle

Optimizing the MAC Protocol in Localization Systems Based on IEEE 802.15.4 Networks

by Juan J. Pérez-Solano^*

, Jose M. Claver and Santiago Ezpeleta

Departament d’Informàtica, Universitat de València, Avd. de la Universitat, 46100 Burjassot, Spain

Sensors 2017, 17(7), 1582; https://doi.org/10.3390/s17071582 - 6 Jul 2017

Cited by 5 | Viewed by 5135

Abstract

Radio frequency signals are commonly used in the development of indoor localization systems. The infrastructure of these systems includes some beacons placed at known positions that exchange radio packets with users to be located. When the system is implemented using wireless sensor networks, [...] Read more.

Radio frequency signals are commonly used in the development of indoor localization systems. The infrastructure of these systems includes some beacons placed at known positions that exchange radio packets with users to be located. When the system is implemented using wireless sensor networks, the wireless transceivers integrated in the network motes are usually based on the IEEE 802.15.4 standard. But, the CSMA-CA, which is the basis for the medium access protocols in this category of communication systems, is not suitable when several users want to exchange bursts of radio packets with the same beacon to acquire the radio signal strength indicator (RSSI) values needed in the location process. Therefore, new protocols are necessary to avoid the packet collisions that appear when multiple users try to communicate with the same beacons. On the other hand, the RSSI sampling process should be carried out very quickly because some systems cannot tolerate a large delay in the location process. This is even more important when the RSSI sampling process includes measures with different signal power levels or frequency channels. The principal objective of this work is to speed up the RSSI sampling process in indoor localization systems. To achieve this objective, the main contribution is the proposal of a new MAC protocol that eliminates the medium access contention periods and decreases the number of packet collisions to accelerate the RSSI collection process. Moreover, the protocol increases the overall network throughput taking advantage of the frequency channel diversity. The presented results show the suitability of this protocol for reducing the RSSI gathering delay and increasing the network throughput in simulated and real environments. Full article

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

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18 pages, 5735 KiB

Open AccessArticle

GNSS-R Altimetry Performance Analysis for the GEROS Experiment on Board the International Space Station

by Adriano Camps^1,2,*

, Hyuk Park^1,2

, Ivan Sekulic¹ and Juan Manuel Rius¹

¹ CommSensLab, Unidad de Excelencia María de Maeztu, Department of Signal Theory and Communications, Universitat Politècnica de Catalunya, E-08034 Barcelona, Spain

² Institut d’Estudis Espacial de Catalunya/Centre de Tecnologies Espacials-Universitat Politècnica de Catalunya, UPC Campus Nord, E-08034 Barcelona, Spain

Sensors 2017, 17(7), 1583; https://doi.org/10.3390/s17071583 - 6 Jul 2017

Cited by 18 | Viewed by 5916

Abstract

The GEROS-ISS (GNSS rEflectometry, Radio Occultation and Scatterometry onboard International Space Station) is an innovative experiment for climate research, proposed in 2011 within a call of the European Space Agency (ESA). This proposal was the only one selected for further studies by ESA [...] Read more.

The GEROS-ISS (GNSS rEflectometry, Radio Occultation and Scatterometry onboard International Space Station) is an innovative experiment for climate research, proposed in 2011 within a call of the European Space Agency (ESA). This proposal was the only one selected for further studies by ESA out of ~25 ones that were submitted. In this work, the instrument performance for the near-nadir altimetry (GNSS-R) mode is assessed, including the effects of multi-path in the ISS structure, the electromagnetic-bias, and the orbital height decay. In the absence of ionospheric scintillations, the altimetry rms error is <50 cm for a swath <~250 km and for U₁₀ <10 m/s. If the transmitted power is 3 dB higher (likely to happen at beginning of life of the GNSS spacecrafts), mission requirements (rms error is <50 cm) are met for all ISS heights and for U₁₀ up to 15 m/s. However, around 1.5 GHz, the ionosphere can induce significant fading, from 2 to >20 dB at equatorial regions, mainly after sunset, which will seriously degrade the altimetry and the scatterometry performances of the instrument. Full article

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

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13 pages, 5193 KiB

Open AccessArticle

Single Carrier with Frequency Domain Equalization for Synthetic Aperture Underwater Acoustic Communications

by Chengbing He^*, Rui Xi, Han Wang, Lianyou Jing, Wentao Shi and Qunfei Zhang

School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(7), 1584; https://doi.org/10.3390/s17071584 - 6 Jul 2017

Cited by 7 | Viewed by 5174

Abstract

Phase-coherent underwater acoustic (UWA) communication systems typically employ multiple hydrophones in the receiver to achieve spatial diversity gain. However, small underwater platforms can only carry a single transducer which can not provide spatial diversity gain. In this paper, we propose single-carrier with frequency [...] Read more.

Phase-coherent underwater acoustic (UWA) communication systems typically employ multiple hydrophones in the receiver to achieve spatial diversity gain. However, small underwater platforms can only carry a single transducer which can not provide spatial diversity gain. In this paper, we propose single-carrier with frequency domain equalization (SC-FDE) for phase-coherent synthetic aperture acoustic communications in which a virtual array is generated by the relative motion between the transmitter and the receiver. This paper presents synthetic aperture acoustic communication results using SC-FDE through data collected during a lake experiment in January 2016. The performance of two receiver algorithms is analyzed and compared, including the frequency domain equalizer (FDE) and the hybrid time frequency domain equalizer (HTFDE). The distances between the transmitter and the receiver in the experiment were about 5 km. The bit error rate (BER) and output signal-to-noise ratio (SNR) performances with different receiver elements and transmission numbers were presented. After combining multiple transmissions, error-free reception using a convolution code with a data rate of 8 kbps was demonstrated. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 2352 KiB

Open AccessArticle

An Ontology-based Context-aware System for Smart Homes: E-care@home

by Marjan Alirezaie^1,*, Jennifer Renoux¹

, Uwe Köckemann¹, Annica Kristoffersson¹

, Lars Karlsson¹, Eva Blomqvist², Nicolas Tsiftes³

, Thiemo Voigt³ and Amy Loutfi¹

¹ Center for Applied Autonomous Sensor Systems, Örebro University, 70182 Örebro, Sweden

² RISE SICS East, 581 83 Linköping, Sweden

³ RISE SICS, 164 29 Stockholm, Sweden

Sensors 2017, 17(7), 1586; https://doi.org/10.3390/s17071586 - 6 Jul 2017

Cited by 110 | Viewed by 11415

Abstract

Smart home environments have a significant potential to provide for long-term monitoring of users with special needs in order to promote the possibility to age at home. Such environments are typically equipped with a number of heterogeneous sensors that monitor both health and [...] Read more.

Smart home environments have a significant potential to provide for long-term monitoring of users with special needs in order to promote the possibility to age at home. Such environments are typically equipped with a number of heterogeneous sensors that monitor both health and environmental parameters. This paper presents a framework called E-care@home, consisting of an IoT infrastructure, which provides information with an unambiguous, shared meaning across IoT devices, end-users, relatives, health and care professionals and organizations. We focus on integrating measurements gathered from heterogeneous sources by using ontologies in order to enable semantic interpretation of events and context awareness. Activities are deduced using an incremental answer set solver for stream reasoning. The paper demonstrates the proposed framework using an instantiation of a smart environment that is able to perform context recognition based on the activities and the events occurring in the home. Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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15 pages, 470 KiB

Open AccessArticle

Routing in Mobile Wireless Sensor Networks: A Leader-Based Approach

by Unai Burgos^1,2, Ugaitz Amozarrain¹, Carlos Gómez-Calzado² and Alberto Lafuente^1,*

¹ University of the Basque Country UPV/EHU, Barrio Sarriena, s/n, 48940 Leioa, Vizcaya, Spain

² Wimbi Technologies S.L., 20015 Donostia, Spain

Sensors 2017, 17(7), 1587; https://doi.org/10.3390/s17071587 - 7 Jul 2017

Cited by 20 | Viewed by 5688

Abstract

This paper presents a leader-based approach to routing in Mobile Wireless Sensor Networks (MWSN). Using local information from neighbour nodes, a leader election mechanism maintains a spanning tree in order to provide the necessary adaptations for efficient routing upon the connectivity changes resulting [...] Read more.

This paper presents a leader-based approach to routing in Mobile Wireless Sensor Networks (MWSN). Using local information from neighbour nodes, a leader election mechanism maintains a spanning tree in order to provide the necessary adaptations for efficient routing upon the connectivity changes resulting from the mobility of sensors or sink nodes. We present two protocols following the leader election approach, which have been implemented using Castalia and OMNeT++. The protocols have been evaluated, besides other reference MWSN routing protocols, to analyse the impact of network size and node velocity on performance, which has demonstrated the validity of our approach. Full article

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

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13 pages, 6343 KiB

Open AccessArticle

Towards a Cognitive Radar: Canada’s Third-Generation High Frequency Surface Wave Radar (HFSWR) for Surveillance of the 200 Nautical Mile Exclusive Economic Zone

by Anthony Ponsford¹, Rick McKerracher², Zhen Ding³, Peter Moo^3,* and Derek Yee¹

¹ Former Employee of Raytheon Canada Limited, 400 Phillip Street, Waterloo, ON N2L 6R7, Canada

² Raytheon Canada Limited, 400 Phillip Street, Waterloo, ON N2L 6R7, Canada

³ Radar Sensing and Exploitation Section, Defence Research and Development Canada; Ottawa, ON K1A 0Z4, Canada

Sensors 2017, 17(7), 1588; https://doi.org/10.3390/s17071588 - 7 Jul 2017

Cited by 19 | Viewed by 7708

Abstract

Canada’s third-generation HFSWR forms the foundation of a maritime domain awareness system that provides enforcement agencies with real-time persistent surveillance out to and beyond the 200 nautical mile exclusive economic zone (EEZ). Cognitive sense-and-adapt technology and dynamic spectrum management ensures robust and resilient [...] Read more.

Canada’s third-generation HFSWR forms the foundation of a maritime domain awareness system that provides enforcement agencies with real-time persistent surveillance out to and beyond the 200 nautical mile exclusive economic zone (EEZ). Cognitive sense-and-adapt technology and dynamic spectrum management ensures robust and resilient operation in the highly congested High Frequency (HF) band. Dynamic spectrum access enables the system to simultaneously operate on two frequencies on a non-interference and non-protected basis, without impacting other spectrum users. Sense-and-adapt technologies ensure that the system instantaneously switches to a new vacant channel on the detection of another user or unwanted jamming signal. Adaptive signal processing techniques mitigate against electrical noise, interference and clutter. Sense-and-adapt techniques applied at the detector and tracker stages maximize the probability of track initiation whilst minimizing the probability of false or otherwise erroneous track data. Full article

(This article belongs to the Special Issue Marine Sensing)

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12 pages, 1167 KiB

Open AccessArticle

USEQ: A Short Questionnaire for Satisfaction Evaluation of Virtual Rehabilitation Systems

by José-Antonio Gil-Gómez^1,*

, Pilar Manzano-Hernández², Sergio Albiol-Pérez³

, Carmen Aula-Valero², Hermenegildo Gil-Gómez¹ and José-Antonio Lozano-Quilis¹

¹ Instituto Universitario de Automática e Informática Industrial, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

² Hospital S. José, Av. Zaragoza 16, 44001 Teruel, Spain

³ Aragón Health Research Institute (IIS Aragón), Universidad de Zaragoza, Ciudad Escolar, 44003 Teruel, Spain

Sensors 2017, 17(7), 1589; https://doi.org/10.3390/s17071589 - 7 Jul 2017

Cited by 97 | Viewed by 9781

Abstract

New emerging technologies have proven their efficacy in aiding people in their rehabilitation. The tests that are usually used to evaluate usability (in general) or user satisfaction (in particular) of this technology are not specifically focused on virtual rehabilitation and patients. The objective [...] Read more.

New emerging technologies have proven their efficacy in aiding people in their rehabilitation. The tests that are usually used to evaluate usability (in general) or user satisfaction (in particular) of this technology are not specifically focused on virtual rehabilitation and patients. The objective of this contribution is to present and evaluate the USEQ (User Satisfaction Evaluation Questionnaire). The USEQ is a questionnaire that is designed to properly evaluate the satisfaction of the user (which constitutes part of usability) in virtual rehabilitation systems. Forty patients with balance disorders completed the USEQ after their first session with ABAR (Active Balance Rehabilitation), which is a virtual rehabilitation system that is designed for the rehabilitation of balance disorders. Internal consistency analysis and exploratory factor analysis were carried out to identify the factor structure of the USEQ. The six items of USEQ were significantly associated with each other, and the Cronbach alpha coefficient for the questionnaire was 0.716. In an analysis of the principal components, a one-factor solution was considered to be appropriate. The findings of the study suggest that the USEQ is a reliable questionnaire with adequate internal consistency. With regard to patient perception, the patients found the USEQ to be an easy-to-understand questionnaire with a convenient number of questions. Full article

(This article belongs to the Special Issue Sensors and Analytics for Precision Medicine)

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9 pages, 8686 KiB

Open AccessArticle

Ultrasensitive Magnetic Field Sensing Based on Refractive-Index-Matched Coupling

by Jie Rao¹, Shengli Pu^1,2,*

, Tianjun Yao¹ and Delong Su¹

¹ College of Science, University of Shanghai for Science and Technology, Shanghai 200093, China

² Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China

Sensors 2017, 17(7), 1590; https://doi.org/10.3390/s17071590 - 7 Jul 2017

Cited by 16 | Viewed by 5099

Abstract

An ultrasensitive magnetic field sensor is proposed and investigated experimentally. The no-core fiber is fusion-spliced between two pieces of single-mode fibers and then immersed in magnetic fluid with an appropriate value of refractive index. Under the refractive-index-matched coupling condition, the guided mode becomes [...] Read more.

An ultrasensitive magnetic field sensor is proposed and investigated experimentally. The no-core fiber is fusion-spliced between two pieces of single-mode fibers and then immersed in magnetic fluid with an appropriate value of refractive index. Under the refractive-index-matched coupling condition, the guided mode becomes leaky and a coupling wavelength dip in the transmission spectrum of the structure is observed. The coupling wavelength dip is extremely sensitive to the ambient environment. The excellent sensitivity to the refractive index is measured to be 116.681 μm/RIU (refractive index unit) in the refractive index range of 1.45691–1.45926. For the as-fabricated sensors, the highest magnetic field sensing sensitivities of 6.33 and 1.83 nm/mT are achieved at low and high fields, respectively. The sensitivity is considerably enhanced compared with those of previously designed, similar structures. Full article

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

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18 pages, 1660 KiB

Open AccessArticle

A Study of Vicon System Positioning Performance

by Pierre Merriaux^1,*,†, Yohan Dupuis^2,*,†, Rémi Boutteau¹

, Pascal Vasseur³ and Xavier Savatier¹

¹ Normandie University, UNIROUEN, ESIGELEC, IRSEEM, 76000 Rouen, France

² Department of Multimodal Transportation Infrastructure, Cerema, 76120 Le Grand Quevilly, France

³ Normandie University, UNIROUEN, UNIHAVRE, INSA Rouen, LITIS, 76000 Rouen, France

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1591; https://doi.org/10.3390/s17071591 - 7 Jul 2017

Cited by 336 | Viewed by 17886

Abstract

Motion capture setups are used in numerous fields. Studies based on motion capture data can be found in biomechanical, sport or animal science. Clinical science studies include gait analysis as well as balance, posture and motor control. Robotic applications encompass object tracking. Today’s [...] Read more.

Motion capture setups are used in numerous fields. Studies based on motion capture data can be found in biomechanical, sport or animal science. Clinical science studies include gait analysis as well as balance, posture and motor control. Robotic applications encompass object tracking. Today’s life applications includes entertainment or augmented reality. Still, few studies investigate the positioning performance of motion capture setups. In this paper, we study the positioning performance of one player in the optoelectronic motion capture based on markers: Vicon system. Our protocol includes evaluations of static and dynamic performances. Mean error as well as positioning variabilities are studied with calibrated ground truth setups that are not based on other motion capture modalities. We introduce a new setup that enables directly estimating the absolute positioning accuracy for dynamic experiments contrary to state-of-the art works that rely on inter-marker distances. The system performs well on static experiments with a mean absolute error of 0.15 mm and a variability lower than 0.025 mm. Our dynamic experiments were carried out at speeds found in real applications. Our work suggests that the system error is less than 2 mm. We also found that marker size and Vicon sampling rate must be carefully chosen with respect to the speed encountered in the application in order to reach optimal positioning performance that can go to 0.3 mm for our dynamic study. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 2479 KiB

Open AccessArticle

Leaf Area Index Estimation Using Chinese GF-1 Wide Field View Data in an Agriculture Region

by Xiangqin Wei^1,2,3

, Xingfa Gu^1,2,3,*

, Qingyan Meng^1,3, Tao Yu^1,3, Xiang Zhou^1,3, Zheng Wei³, Kun Jia^4,*

and Chunmei Wang^1,3

¹ Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China

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

³ Application Technology Center of China High-Resolution Earth Observation System, Beijing 100101, China

⁴ State Key Laboratory of Remote Sensing Science, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China

Sensors 2017, 17(7), 1593; https://doi.org/10.3390/s17071593 - 8 Jul 2017

Cited by 13 | Viewed by 5133

Abstract

Leaf area index (LAI) is an important vegetation parameter that characterizes leaf density and canopy structure, and plays an important role in global change study, land surface process simulation and agriculture monitoring. The wide field view (WFV) sensor on board the Chinese GF-1 [...] Read more.

Leaf area index (LAI) is an important vegetation parameter that characterizes leaf density and canopy structure, and plays an important role in global change study, land surface process simulation and agriculture monitoring. The wide field view (WFV) sensor on board the Chinese GF-1 satellite can acquire multi-spectral data with decametric spatial resolution, high temporal resolution and wide coverage, which are valuable data sources for dynamic monitoring of LAI. Therefore, an automatic LAI estimation algorithm for GF-1 WFV data was developed based on the radiative transfer model and LAI estimation accuracy of the developed algorithm was assessed in an agriculture region with maize as the dominated crop type. The radiative transfer model was firstly used to simulate the physical relationship between canopy reflectance and LAI under different soil and vegetation conditions, and then the training sample dataset was formed. Then, neural networks (NNs) were used to develop the LAI estimation algorithm using the training sample dataset. Green, red and near-infrared band reflectances of GF-1 WFV data were used as the input variables of the NNs, as well as the corresponding LAI was the output variable. The validation results using field LAI measurements in the agriculture region indicated that the LAI estimation algorithm could achieve satisfactory results (such as R² = 0.818, RMSE = 0.50). In addition, the developed LAI estimation algorithm had potential to operationally generate LAI datasets using GF-1 WFV land surface reflectance data, which could provide high spatial and temporal resolution LAI data for agriculture, ecosystem and environmental management researches. Full article

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

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14 pages, 4328 KiB

Open AccessArticle

On Transform Domain Communication Systems under Spectrum Sensing Mismatch: A Deterministic Analysis

by Chuanxue Jin¹, Su Hu¹, Yixuan Huang¹, Qu Luo¹, Dan Huang¹, Yi Li², Yuan Gao^3,4,*

and Shaochi Cheng³

¹ National Key Lab on Communication, University of Electronic Science and Technology of China, 611731 Chengdu, China

² The High School Affiliated to Renmin University of China, 100080 Beijing, China

³ China Defense Science and Technology Information Center, 100048 Beijing, China

⁴ Department of Electronic Engineering, Tsinghua University, 100084 Beijing, China

Sensors 2017, 17(7), 1594; https://doi.org/10.3390/s17071594 - 8 Jul 2017

Cited by 2 | Viewed by 4989

Abstract

Towards the era of mobile Internet and the Internet of Things (IoT), numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, traditional wireless communication technologies are facing challenges both in terms of the increasing shortage [...] Read more.

Towards the era of mobile Internet and the Internet of Things (IoT), numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, traditional wireless communication technologies are facing challenges both in terms of the increasing shortage of spectrum resources and massive multiple access. The transform-domain communication system (TDCS) is considered as an alternative multiple access system, where 5G and mobile IoT are mainly focused. However, previous studies about TDCS are under the assumption that the transceiver has the global spectrum information, without the consideration of spectrum sensing mismatch (SSM). In this paper, we present the deterministic analysis of TDCS systems under arbitrary given spectrum sensing scenarios, especially the influence of the SSM pattern to the signal to noise ratio (SNR) performance. Simulation results show that arbitrary SSM pattern can lead to inferior bit error rate (BER) performance. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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20 pages, 5297 KiB

Open AccessArticle

Multi-National Banknote Classification Based on Visible-light Line Sensor and Convolutional Neural Network

by Tuyen Danh Pham, Dong Eun Lee and Kang Ryoung Park^*

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

Sensors 2017, 17(7), 1595; https://doi.org/10.3390/s17071595 - 8 Jul 2017

Cited by 19 | Viewed by 7470

Abstract

Automatic recognition of banknotes is applied in payment facilities, such as automated teller machines (ATMs) and banknote counters. Besides the popular approaches that focus on studying the methods applied to various individual types of currencies, there have been studies conducted on simultaneous classification [...] Read more.

Automatic recognition of banknotes is applied in payment facilities, such as automated teller machines (ATMs) and banknote counters. Besides the popular approaches that focus on studying the methods applied to various individual types of currencies, there have been studies conducted on simultaneous classification of banknotes from multiple countries. However, their methods were conducted with limited numbers of banknote images, national currencies, and denominations. To address this issue, we propose a multi-national banknote classification method based on visible-light banknote images captured by a one-dimensional line sensor and classified by a convolutional neural network (CNN) considering the size information of each denomination. Experiments conducted on the combined banknote image database of six countries with 62 denominations gave a classification accuracy of 100%, and results show that our proposed algorithm outperforms previous methods. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 3669 KiB

Open AccessArticle

Real-Time Amperometric Recording of Extracellular H₂O₂ in the Brain of Immunocompromised Mice: An In Vitro, Ex Vivo and In Vivo Characterisation Study

by Caroline H. Reid and Niall J. Finnerty^*

Chemistry Department, Maynooth University, Maynooth W23 F2H6, County Kildare, Ireland

Sensors 2017, 17(7), 1596; https://doi.org/10.3390/s17071596 - 8 Jul 2017

Cited by 6 | Viewed by 5057

Abstract

We detail an extensive characterisation study on a previously described dual amperometric H₂O₂ biosensor consisting of H₂O₂ detection (blank) and degradation (catalase) electrodes. In vitro investigations demonstrated excellent H₂O₂ sensitivity and selectivity against the [...] Read more.

We detail an extensive characterisation study on a previously described dual amperometric H₂O₂ biosensor consisting of H₂O₂ detection (blank) and degradation (catalase) electrodes. In vitro investigations demonstrated excellent H₂O₂ sensitivity and selectivity against the interferent, ascorbic acid. Ex vivo studies were performed to mimic physiological conditions prior to in vivo deployment. Exposure to brain tissue homogenate identified reliable sensitivity and selectivity recordings up to seven days for both blank and catalase electrodes. Furthermore, there was no compromise in pre- and post-implanted catalase electrode sensitivity in ex vivo mouse brain. In vivo investigations performed in anaesthetised mice confirmed the ability of the H₂O₂ biosensor to detect increases in amperometric current following locally perfused/infused H₂O₂ and antioxidant inhibitors mercaptosuccinic acid and sodium azide. Subsequent recordings in freely moving mice identified negligible effects of control saline and sodium ascorbate interference injections on amperometric H₂O₂ current. Furthermore, the stability of the amperometric current was confirmed over a five-day period and analysis of 24-h signal recordings identified the absence of diurnal variations in amperometric current. Collectively, these findings confirm the biosensor current responds in vivo to increasing exogenous and endogenous H₂O₂ and tentatively supports measurement of H₂O₂ dynamics in freely moving NOD SCID mice. Full article

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

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24 pages, 6727 KiB

Open AccessArticle

A Novel Spatial Feature for the Identification of Motor Tasks Using High-Density Electromyography

by Mislav Jordanić^1,2, Mónica Rojas-Martínez^1,2,3, Miguel Angel Mañanas^1,2,*, Joan Francesc Alonso^1,2

and Hamid Reza Marateb^1,4

¹ Department of Automatic Control (ESAII), Biomedical Engineering Research Centre (CREB), Universitat Politècnica de Catalunya (UPC), Barcelona 08028, Spain

² Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid 28029, Spain

³ Bioengineering Department, El Bosque University, Bogotá 110121, Colombia

⁴ Biomedical Engineering Department, Engineering Faculty, University of Isfahan, Isfahan 81746-73441, Iran

Sensors 2017, 17(7), 1597; https://doi.org/10.3390/s17071597 - 8 Jul 2017

Cited by 28 | Viewed by 7666

Abstract

Estimation of neuromuscular intention using electromyography (EMG) and pattern recognition is still an open problem. One of the reasons is that the pattern-recognition approach is greatly influenced by temporal changes in electromyograms caused by the variations in the conductivity of the skin and/or [...] Read more.

Estimation of neuromuscular intention using electromyography (EMG) and pattern recognition is still an open problem. One of the reasons is that the pattern-recognition approach is greatly influenced by temporal changes in electromyograms caused by the variations in the conductivity of the skin and/or electrodes, or physiological changes such as muscle fatigue. This paper proposes novel features for task identification extracted from the high-density electromyographic signal (HD-EMG) by applying the mean shift channel selection algorithm evaluated using a simple and fast classifier-linear discriminant analysis. HD-EMG was recorded from eight subjects during four upper-limb isometric motor tasks (flexion/extension, supination/pronation of the forearm) at three different levels of effort. Task and effort level identification showed very high classification rates in all cases. This new feature performed remarkably well particularly in the identification at very low effort levels. This could be a step towards the natural control in everyday applications where a subject could use low levels of effort to achieve motor tasks. Furthermore, it ensures reliable identification even in the presence of myoelectric fatigue and showed robustness to temporal changes in EMG, which could make it suitable in long-term applications. Full article

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

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32 pages, 11165 KiB

Open AccessArticle

Pedestrian Detection Based on Adaptive Selection of Visible Light or Far-Infrared Light Camera Image by Fuzzy Inference System and Convolutional Neural Network-Based Verification

by Jin Kyu Kang, Hyung Gil Hong 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(7), 1598; https://doi.org/10.3390/s17071598 - 8 Jul 2017

Cited by 21 | Viewed by 6333

Abstract

A number of studies have been conducted to enhance the pedestrian detection accuracy of intelligent surveillance systems. However, detecting pedestrians under outdoor conditions is a challenging problem due to the varying lighting, shadows, and occlusions. In recent times, a growing number of studies [...] Read more.

A number of studies have been conducted to enhance the pedestrian detection accuracy of intelligent surveillance systems. However, detecting pedestrians under outdoor conditions is a challenging problem due to the varying lighting, shadows, and occlusions. In recent times, a growing number of studies have been performed on visible light camera-based pedestrian detection systems using a convolutional neural network (CNN) in order to make the pedestrian detection process more resilient to such conditions. However, visible light cameras still cannot detect pedestrians during nighttime, and are easily affected by shadows and lighting. There are many studies on CNN-based pedestrian detection through the use of far-infrared (FIR) light cameras (i.e., thermal cameras) to address such difficulties. However, when the solar radiation increases and the background temperature reaches the same level as the body temperature, it remains difficult for the FIR light camera to detect pedestrians due to the insignificant difference between the pedestrian and non-pedestrian features within the images. Researchers have been trying to solve this issue by inputting both the visible light and the FIR camera images into the CNN as the input. This, however, takes a longer time to process, and makes the system structure more complex as the CNN needs to process both camera images. This research adaptively selects a more appropriate candidate between two pedestrian images from visible light and FIR cameras based on a fuzzy inference system (FIS), and the selected candidate is verified with a CNN. Three types of databases were tested, taking into account various environmental factors using visible light and FIR cameras. The results showed that the proposed method performs better than the previously reported methods. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 3390 KiB

Open AccessArticle

Polar Grid Navigation Algorithm for Unmanned Underwater Vehicles

by Zheping Yan, Lu Wang^*, Wei Zhang, Jiajia Zhou and Man Wang

Marine Assembly and Automatic Technology Institute, College of Automation, Harbin Engineering University; Harbin 150001, China

Sensors 2017, 17(7), 1599; https://doi.org/10.3390/s17071599 - 9 Jul 2017

Cited by 36 | Viewed by 6154

Abstract

To solve the unavailability of a traditional strapdown inertial navigation system (SINS) for unmanned underwater vehicles (UUVs) in the polar region, a polar grid navigation algorithm for UUVs is proposed in this paper. Precise navigation is the basis for UUVs to complete missions. [...] Read more.

To solve the unavailability of a traditional strapdown inertial navigation system (SINS) for unmanned underwater vehicles (UUVs) in the polar region, a polar grid navigation algorithm for UUVs is proposed in this paper. Precise navigation is the basis for UUVs to complete missions. The rapid convergence of Earth meridians and the serious polar environment make it difficult to establish the true heading of the UUV at a particular instant. Traditional SINS and traditional representation of position are not suitable in the polar region. Due to the restrictions of the complex underwater conditions in the polar region, a SINS based on the grid frame with the assistance of the OCTANS and the Doppler velocity log (DVL) is chosen for a UUV navigating in the polar region. Data fusion of the integrated navigation system is realized by a modified fuzzy adaptive Kalman filter (MFAKF). By neglecting the negative terms, and using T-S fuzzy logic in the adaptive regulation of the noise covariance, the proposed filter algorithm can improve navigation accuracy. Simulation and experimental results demonstrate that the polar grid navigation algorithm can effectively navigate a UUV sailing in the polar region. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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21 pages, 6010 KiB

Open AccessArticle

Hardware/Software Data Acquisition System for Real Time Cell Temperature Monitoring in Air-Cooled Polymer Electrolyte Fuel Cells

by Francisca Segura^1,*

, Veronica Bartolucci² and José Manuel Andújar¹

¹ Department of Electronic, Computer Science and Automatic Engineering, University of Huelva, Engineering High School, Crta. Huelva- Palos de la Fra, 21919 Palos de la Fra, Huelva, Spain

² Dipartimento di Ingegneria dell’Informazione, Universita’ Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy

Sensors 2017, 17(7), 1600; https://doi.org/10.3390/s17071600 - 9 Jul 2017

Cited by 15 | Viewed by 6583

Abstract

This work presents a hardware/software data acquisition system developed for monitoring the temperature in real time of the cells in Air-Cooled Polymer Electrolyte Fuel Cells (AC-PEFC). These fuel cells are of great interest because they can carry out, in a single operation, the [...] Read more.

This work presents a hardware/software data acquisition system developed for monitoring the temperature in real time of the cells in Air-Cooled Polymer Electrolyte Fuel Cells (AC-PEFC). These fuel cells are of great interest because they can carry out, in a single operation, the processes of oxidation and refrigeration. This allows reduction of weight, volume, cost and complexity of the control system in the AC-PEFC. In this type of PEFC (and in general in any PEFC), the reliable monitoring of temperature along the entire surface of the stack is fundamental, since a suitable temperature and a regular distribution thereof, are key for a better performance of the stack and a longer lifetime under the best operating conditions. The developed data acquisition (DAQ) system can perform non-intrusive temperature measurements of each individual cell of an AC-PEFC stack of any power (from watts to kilowatts). The stack power is related to the temperature gradient; i.e., a higher power corresponds to a higher stack surface, and consequently higher temperature difference between the coldest and the hottest point. The developed DAQ system has been implemented with the low-cost open-source platform Arduino, and it is completed with a modular virtual instrument that has been developed using NI LabVIEW. Temperature vs time evolution of all the cells of an AC-PEFC both together and individually can be registered and supervised. The paper explains comprehensively the developed DAQ system together with experimental results that demonstrate the suitability of the system. Full article

(This article belongs to the Special Issue Biofuel Cells)

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13 pages, 3506 KiB

Open AccessArticle

Rapid Surface Enhanced Raman Scattering (SERS) Detection of Sibutramine Hydrochloride in Pharmaceutical Capsules with a β-Cyclodextrin- Ag/Polyvivnyl Alcohol Hydrogel Substrate

by Lei Ouyang^1,2,†, Zuyan Jiang^1,†, Nan Wang¹, Lihua Zhu^1,* and Heqing Tang^2,*

¹ School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

² Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South Central University for Nationalities, Wuhan 430074, China

^† These authors contribute equally to this work.

Sensors 2017, 17(7), 1601; https://doi.org/10.3390/s17071601 - 10 Jul 2017

Cited by 18 | Viewed by 7991

Abstract

Sibutramine hydrochloride (SH) is a banned weight-loss drug, but its illegal addition to health products is still rampant. This suggests a very urgent need for a fast and precise detection method for SH. Surface Enhanced Raman Scattering (SERS) is a promising candidate for [...] Read more.

Sibutramine hydrochloride (SH) is a banned weight-loss drug, but its illegal addition to health products is still rampant. This suggests a very urgent need for a fast and precise detection method for SH. Surface Enhanced Raman Scattering (SERS) is a promising candidate for this purpose, but the weak affinity between SH and bare metal limits its direct SERS detection. In the present work, β-cyclodextrin was capped in situ onto the surface of Ag nanoparticles to function as a scaffold to capture SH. The obtained Ag nanoparticles were encapsulated into polyvinyl alcohol (PVA) to fabricate a SERS active hydrogel with excellent reproducibility. A facile SERS strategy based on such substrate was proposed for trace SH quantification with a linear range of 7.0–150.0 µg·mL^–1, and a detection limit low to 3.0 µg·mL⁻¹. It was applied to analyze seven types of commercial slimming capsules with satisfactory results, showing good prospect for real applications. Full article

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

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10 pages, 801 KiB

Open AccessArticle

Energy Harvesting Based Body Area Networks for Smart Health

by Yixue Hao¹, Limei Peng^2,*, Huimin Lu³

, Mohammad Mehedi Hassan⁴

and Atif Alamri⁴

¹ School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China

² Department of Industrial and Information System Engineering, Ajou University, Suwon 443749 , Korea

³ Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Fukuoka prefecture 8048550, Japan

⁴ College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia

Sensors 2017, 17(7), 1602; https://doi.org/10.3390/s17071602 - 10 Jul 2017

Cited by 34 | Viewed by 6774

Abstract

Body area networks (BANs) are configured with a great number of ultra-low power consumption wearable devices, which constantly monitor physiological signals of the human body and thus realize intelligent monitoring. However, the collection and transfer of human body signals consume energy, and considering [...] Read more.

Body area networks (BANs) are configured with a great number of ultra-low power consumption wearable devices, which constantly monitor physiological signals of the human body and thus realize intelligent monitoring. However, the collection and transfer of human body signals consume energy, and considering the comfort demand of wearable devices, both the size and the capacity of a wearable device’s battery are limited. Thus, minimizing the energy consumption of wearable devices and optimizing the BAN energy efficiency is still a challenging problem. Therefore, in this paper, we propose an energy harvesting-based BAN for smart health and discuss an optimal resource allocation scheme to improve BAN energy efficiency. Specifically, firstly, considering energy harvesting in a BAN and the time limits of human body signal transfer, we formulate the energy efficiency optimization problem of time division for wireless energy transfer and wireless information transfer. Secondly, we convert the optimization problem into a convex optimization problem under a linear constraint and propose a closed-form solution to the problem. Finally, simulation results proved that when the size of data acquired by the wearable devices is small, the proportion of energy consumed by the circuit and signal acquisition of the wearable devices is big, and when the size of data acquired by the wearable devices is big, the energy consumed by the signal transfer of the wearable device is decisive. Full article

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

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15 pages, 11113 KiB

Open AccessArticle

Microfluidic Platform for the Long-Term On-Chip Cultivation of Mammalian Cells for Lab-On-A-Chip Applications

by Frank Bunge^1,2,*

, Sander Van den Driesche^1,2

and Michael J. Vellekoop^1,2

¹ Institute for Microsensors, -actuators and -systems (IMSAS), University of Bremen, 28359 Bremen, Germany

² Microsystems Center Bremen (MCB), University of Bremen, 28359 Bremen, Germany

Sensors 2017, 17(7), 1603; https://doi.org/10.3390/s17071603 - 10 Jul 2017

Cited by 23 | Viewed by 5889

Abstract

Lab-on-a-Chip (LoC) applications for the long-term analysis of mammalian cells are still very rare due to the lack of convenient cell cultivation devices. The difficulties are the integration of suitable supply structures, the need of expensive equipment like an incubator and sophisticated pumps [...] Read more.

Lab-on-a-Chip (LoC) applications for the long-term analysis of mammalian cells are still very rare due to the lack of convenient cell cultivation devices. The difficulties are the integration of suitable supply structures, the need of expensive equipment like an incubator and sophisticated pumps as well as the choice of material. The presented device is made out of hard, but non-cytotoxic materials (silicon and glass) and contains two vertical arranged membranes out of hydrogel. The porous membranes are used to separate the culture chamber from two supply channels for gases and nutrients. The cells are fed continuously by diffusion through the membranes without the need of an incubator and low requirements on the supply of medium to the assembly. The diffusion of oxygen is modelled in order to find the optimal dimensions of the chamber. The chip is connected via 3D-printed holders to the macroscopic world. The holders are coated with Parlyene C to ensure that only biocompatible materials are in contact with the culture medium. The experiments with MDCK-cells show the successful seeding inside the chip, culturing and passaging. Consequently, the presented platform is a step towards Lab-on-a-Chip applications that require long-term cultivation of mammalian cells. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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13 pages, 5333 KiB

Open AccessArticle

A Smartphone-Based Automatic Measurement Method for Colorimetric pH Detection Using a Color Adaptation Algorithm

by Sung Deuk Kim¹, Youngmi Koo² and Yeoheung Yun^2,*

¹ Department of Electronic Engineering Education, Andong National University, 1375 Gyeongdong-ro, Andong, Gyeongsangbuk-do 36729, Korea

² FIT BEST Laboratory, Department of Chemical, Biological, and Bioengineering, North Carolina A&T State University, 1601 E. Market St., Greensboro, NC 27411, USA

Sensors 2017, 17(7), 1604; https://doi.org/10.3390/s17071604 - 10 Jul 2017

Cited by 69 | Viewed by 9767

Abstract

This paper proposes a smartphone-based colorimetric pH detection method using a color adaptation algorithm for point-of-care applications. Although a smartphone camera can be utilized to measure the color information of colorimetric sensors, ambient light changes and unknown built-in automatic image correction operations make [...] Read more.

This paper proposes a smartphone-based colorimetric pH detection method using a color adaptation algorithm for point-of-care applications. Although a smartphone camera can be utilized to measure the color information of colorimetric sensors, ambient light changes and unknown built-in automatic image correction operations make it difficult to obtain stable color information. This paper utilizes a 3D printed mini light box and performs a calibration procedure with a paper-printed comparison chart and a reference image which overcomes the drawbacks of smartphone cameras and the difficulty in preparing for the calibration procedure. The color adaptation is performed in the CIE 1976 u’v’ color space by using the reference paper in order to stabilize the color variations. Non-rigid u’v’ curve interpolation is used to produce the high-resolution pH estimate. The final pH value is estimated by using the best-matching method to handle the nonlinear curve properties of multiple color patches. The experimental results obtained using a pH indicator paper show that the proposed algorithm provides reasonably good estimation of pH detection. With paper-printed accurate color comparison charts and smart color adaptation techniques, superior estimation is achieved in the smartphone-based colorimetric pH detection system for point-of-care application. Full article

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

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18 pages, 4530 KiB

Open AccessArticle

Array of Chemosensitive Resistors with Composites of Gas Chromatography (GC) Materials and Carbon Black for Detection and Recognition of VOCs: A Basic Study

by Bartosz Wyszynski^1,*, Rui Yatabe^1,*, Atsuo Nakao², Masaya Nakatani², Akio Oki², Hiroaki Oka² and Kiyoshi Toko¹

¹ Research and Development Center for Taste and Odor Sensing, Nishi-ku, Motooka 744, Fukuoka 819-0395, Japan

² Panasonic Automotive & Industrial Systems Company, Sensing Solutions Development Center, Kadomoa-shi, Oaza Kadoma 1006, Osaka 571-8501, Japan

Sensors 2017, 17(7), 1606; https://doi.org/10.3390/s17071606 - 11 Jul 2017

Cited by 12 | Viewed by 5919

Abstract

Mimicking the biological olfaction, large odor-sensor arrays can be used to acquire a broad range of chemical information, with a potentially high degree of redundancy, to allow for enhanced control over the sensitivity and selectivity of artificial olfaction systems. The arrays should consist [...] Read more.

Mimicking the biological olfaction, large odor-sensor arrays can be used to acquire a broad range of chemical information, with a potentially high degree of redundancy, to allow for enhanced control over the sensitivity and selectivity of artificial olfaction systems. The arrays should consist of the largest possible number of individual sensing elements while being miniaturized. Chemosensitive resistors are one of the sensing platforms that have a potential to satisfy these two conditions. In this work we test viability of fabricating a 16-element chemosensitive resistor array for detection and recognition of volatile organic compounds (VOCs). The sensors were fabricated using blends of carbon black and gas chromatography (GC) stationary-phase materials preselected based on their sorption properties. Blends of the selected GC materials with carbon black particles were subsequently coated over chemosensitive resistor devices and the resulting sensors/arrays evaluated in exposure experiments against vapors of pyrrole, benzenal, nonanal, and 2-phenethylamine at 150, 300, 450, and 900 ppb. Responses of the fabricated 16-element array were stable and differed for each individual odorant sample, proving the blends of GC materials with carbon black particles can be effectively used for fabrication of large odor-sensing arrays based on chemosensitive resistors. The obtained results suggest that the proposed sensing devices could be effective in discriminating odor/vapor samples at the sub-ppm level. Full article

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

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19 pages, 866 KiB

Open AccessArticle

Task Assignment and Path Planning for Multiple Autonomous Underwater Vehicles Using 3D Dubins Curves ^†

by Wenyu Cai^1,*

, Meiyan Zhang^2,* and Yahong Rosa Zheng³

¹ School of Electronics & Information, Hangzhou Dianzi University, Hangzhou 310018, China

² School of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou 310018, China

³ Department of Electrical & Computer Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA

Sensors 2017, 17(7), 1607; https://doi.org/10.3390/s17071607 - 11 Jul 2017

Cited by 69 | Viewed by 8628

Abstract

This paper investigates the task assignment and path planning problem for multiple AUVs in three dimensional (3D) underwater wireless sensor networks where nonholonomic motion constraints of underwater AUVs in 3D space are considered. The multi-target task assignment and path planning problem is modeled [...] Read more.

This paper investigates the task assignment and path planning problem for multiple AUVs in three dimensional (3D) underwater wireless sensor networks where nonholonomic motion constraints of underwater AUVs in 3D space are considered. The multi-target task assignment and path planning problem is modeled by the Multiple Traveling Sales Person (MTSP) problem and the Genetic Algorithm (GA) is used to solve the MTSP problem with Euclidean distance as the cost function and the Tour Hop Balance (THB) or Tour Length Balance (TLB) constraints as the stop criterion. The resulting tour sequences are mapped to 2D Dubins curves in the

X - Y

plane, and then interpolated linearly to obtain the Z coordinates. We demonstrate that the linear interpolation fails to achieve

G^{1}

continuity in the 3D Dubins path for multiple targets. Therefore, the interpolated 3D Dubins curves are checked against the AUV dynamics constraint and the ones satisfying the constraint are accepted to finalize the 3D Dubins curve selection. Simulation results demonstrate that the integration of the 3D Dubins curve with the MTSP model is successful and effective for solving the 3D target assignment and path planning problem. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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15 pages, 3734 KiB

Open AccessArticle

Rapid ELISA Using a Film-Stack Reaction Field with Micropillar Arrays

by Yuma Suzuki¹, Kazuhiro Morioka², Soichiro Ohata¹, Tetsuhide Shimizu¹

, Hizuru Nakajima³, Katsumi Uchiyama³ and Ming Yang^1,*

¹ Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo 191-0065, Japan

² Department of Biomedical Analysis, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan

³ Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan

Sensors 2017, 17(7), 1608; https://doi.org/10.3390/s17071608 - 11 Jul 2017

Cited by 7 | Viewed by 4816

Abstract

A film-stack reaction field with a micropillar array using a motor stirrer was developed for the high sensitivity and rapid enzyme-linked immunosorbent assay (ELISA) reaction. The effects of the incubation time of a protein (30 s, 5 min, and 10 min) on the [...] Read more.

A film-stack reaction field with a micropillar array using a motor stirrer was developed for the high sensitivity and rapid enzyme-linked immunosorbent assay (ELISA) reaction. The effects of the incubation time of a protein (30 s, 5 min, and 10 min) on the fluorescence intensity in ELISAs were investigated using a reaction field with different micropillar array dimensions (5-µm, 10-µm and 50-µm gaps between the micropillars). The difference in fluorescence intensity between the well with the reaction field of 50-µm gap for the incubation time of 30 s and the well without the reaction field with for incubation time of 10 min was 6%. The trend of the fluorescence intensity in the gap between the micro pillars in the film-stack reaction field was different between the short incubation time and the long incubation time. The theoretical analysis of the physical parameters related with the biomolecule transport indicated that the reaction efficiency defined in this study was the dominant factor determining the fluorescence intensity for the short incubation time, whereas the volumetric rate of the circulating flow through the space between films and the specific surface area were the dominant factors for the long incubation time. Full article

(This article belongs to the Section Biosensors)

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30 pages, 4765 KiB

Open AccessArticle

Secure Service Proxy: A CoAP(s) Intermediary for a Securer and Smarter Web of Things

by Floris Van den Abeele^*

, Ingrid Moerman

, Piet Demeester and Jeroen Hoebeke

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

Sensors 2017, 17(7), 1609; https://doi.org/10.3390/s17071609 - 11 Jul 2017

Cited by 12 | Viewed by 6616

Abstract

As the IoT continues to grow over the coming years, resource-constrained devices and networks will see an increase in traffic as everything is connected in an open Web of Things. The performance- and function-enhancing features are difficult to provide in resource-constrained environments, but [...] Read more.

As the IoT continues to grow over the coming years, resource-constrained devices and networks will see an increase in traffic as everything is connected in an open Web of Things. The performance- and function-enhancing features are difficult to provide in resource-constrained environments, but will gain importance if the WoT is to be scaled up successfully. For example, scalable open standards-based authentication and authorization will be important to manage access to the limited resources of constrained devices and networks. Additionally, features such as caching and virtualization may help further reduce the load on these constrained systems. This work presents the Secure Service Proxy (SSP): a constrained-network edge proxy with the goal of improving the performance and functionality of constrained RESTful environments. Our evaluations show that the proposed design reaches its goal by reducing the load on constrained devices while implementing a wide range of features as different adapters. Specifically, the results show that the SSP leads to significant savings in processing, network traffic, network delay and packet loss rates for constrained devices. As a result, the SSP helps to guarantee the proper operation of constrained networks as these networks form an ever-expanding Web of Things. Full article

(This article belongs to the Section Sensor Networks)

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34 pages, 958 KiB

Open AccessArticle

Secure and Time-Aware Communication of Wireless Sensors Monitoring Overhead Transmission Lines

by Katarzyna Mazur^1,*,†

, Michal Wydra²

and Bogdan Ksiezopolski^1,3

¹ Faculty of Mathematics, Physics and Computer Science, Maria Curie-Sklodowska University, Lublin 20-031, Poland

² Faculty of Electrical Engineering and Computer Science, Lublin University of Technology, Lublin 20-618, Poland

³ Department of Informatics, Polish-Japanese Academy of Information Technology, Warsaw 02-008, Poland

^† Current address: Pl. M. Curie-Sklodowskiej 5, 20-031 Lublin, Poland

Sensors 2017, 17(7), 1610; https://doi.org/10.3390/s17071610 - 11 Jul 2017

Cited by 23 | Viewed by 7820

Abstract

Existing transmission power grids suffer from high maintenance costs and scalability issues along with a lack of effective and secure system monitoring. To address these problems, we propose to use Wireless Sensor Networks (WSNs) as a technology to achieve energy efficient, reliable, and [...] Read more.

Existing transmission power grids suffer from high maintenance costs and scalability issues along with a lack of effective and secure system monitoring. To address these problems, we propose to use Wireless Sensor Networks (WSNs) as a technology to achieve energy efficient, reliable, and low-cost remote monitoring of transmission grids. With WSNs, smart grid enables both utilities and customers to monitor, predict and manage energy usage effectively and react to possible power grid disturbances in a timely manner. However, the increased application of WSNs also introduces new security challenges, especially related to privacy, connectivity, and security management, repeatedly causing unpredicted expenditures. Monitoring the status of the power system, a large amount of sensors generates massive amount of sensitive data. In order to build an effective Wireless Sensor Network (WSN) for a smart grid, we focus on designing a methodology of efficient and secure delivery of the data measured on transmission lines. We perform a set of simulations, in which we examine different routing algorithms, security mechanisms and WSN deployments in order to select the parameters that will not affect the delivery time but fulfill their role and ensure security at the same time. Furthermore, we analyze the optimal placement of direct wireless links, aiming at minimizing time delays, balancing network performance and decreasing deployment costs. Full article

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

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14 pages, 874 KiB

Open AccessArticle

A Fine-Grained and Privacy-Preserving Query Scheme for Fog Computing-Enhanced Location-Based Service

by Xue Yang^*

, Fan Yin and Xiaohu Tang

The Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China

Sensors 2017, 17(7), 1611; https://doi.org/10.3390/s17071611 - 11 Jul 2017

Cited by 20 | Viewed by 5560

Abstract

Location-based services (LBS), as one of the most popular location-awareness applications, has been further developed to achieve low-latency with the assistance of fog computing. However, privacy issues remain a research challenge in the context of fog computing. Therefore, in this paper, we present [...] Read more.

Location-based services (LBS), as one of the most popular location-awareness applications, has been further developed to achieve low-latency with the assistance of fog computing. However, privacy issues remain a research challenge in the context of fog computing. Therefore, in this paper, we present a fine-grained and privacy-preserving query scheme for fog computing-enhanced location-based services, hereafter referred to as FGPQ. In particular, mobile users can obtain the fine-grained searching result satisfying not only the given spatial range but also the searching content. Detailed privacy analysis shows that our proposed scheme indeed achieves the privacy preservation for the LBS provider and mobile users. In addition, extensive performance analyses and experiments demonstrate that the FGPQ scheme can significantly reduce computational and communication overheads and ensure the low-latency, which outperforms existing state-of-the art schemes. Hence, our proposed scheme is more suitable for real-time LBS searching. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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7 pages, 3090 KiB

Open AccessCommunication

Candle Soot Coating for Latent Fingermark Enhancement on Various Surfaces

by Qianhui Wei, Yu Zhu, Shouliang Liu, Yongjie Gao, Xiaolong Li, Mi Shi, Xueji Zhang^* and Meiqin Zhang^*

Research Center for Bioengineering and Sensing Technology, School of Chemistry & Biological Engineering, University of Science & Technology Beijing, Beijing 100083, China

Sensors 2017, 17(7), 1612; https://doi.org/10.3390/s17071612 - 11 Jul 2017

Cited by 6 | Viewed by 6699

Abstract

We demonstrate a facile method termed candle soot coating (CSC) for fast developing latent fingermarks (LFMs) on various kinds of surfaces (glass, ceramic, metal, paper and adhesive tape). The CSC method can be considered as simple, fast, and low-cost as well as providing [...] Read more.

We demonstrate a facile method termed candle soot coating (CSC) for fast developing latent fingermarks (LFMs) on various kinds of surfaces (glass, ceramic, metal, paper and adhesive tape). The CSC method can be considered as simple, fast, and low-cost as well as providing high contrast for LFM visualization in potential forensic applications. Full article

(This article belongs to the Section Chemical Sensors)

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16 pages, 5396 KiB

Open AccessArticle

A Synergy Cropland of China by Fusing Multiple Existing Maps and Statistics

by Miao Lu¹, Wenbin Wu^1,*, Liangzhi You^1,2, Di Chen¹, Li Zhang¹, Peng Yang¹ and Huajun Tang¹

¹ Key Laboratory of Agricultural Remote Sensing, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China

² International Food Policy Research Institute, Washington, DC 20006, USA

Sensors 2017, 17(7), 1613; https://doi.org/10.3390/s17071613 - 12 Jul 2017

Cited by 33 | Viewed by 6105

Abstract

Accurate information on cropland extent is critical for scientific research and resource management. Several cropland products from remotely sensed datasets are available. Nevertheless, significant inconsistency exists among these products and the cropland areas estimated from these products differ considerably from statistics. In this [...] Read more.

Accurate information on cropland extent is critical for scientific research and resource management. Several cropland products from remotely sensed datasets are available. Nevertheless, significant inconsistency exists among these products and the cropland areas estimated from these products differ considerably from statistics. In this study, we propose a hierarchical optimization synergy approach (HOSA) to develop a hybrid cropland map of China, circa 2010, by fusing five existing cropland products, i.e., GlobeLand30, Climate Change Initiative Land Cover (CCI-LC), GlobCover 2009, MODIS Collection 5 (MODIS C5), and MODIS Cropland, and sub-national statistics of cropland area. HOSA simplifies the widely used method of score assignment into two steps, including determination of optimal agreement level and identification of the best product combination. The accuracy assessment indicates that the synergy map has higher accuracy of spatial locations and better consistency with statistics than the five existing datasets individually. This suggests that the synergy approach can improve the accuracy of cropland mapping and enhance consistency with statistics. Full article

(This article belongs to the Special Issue Sensors and Smart Sensing of Agricultural Land Systems)

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18 pages, 11171 KiB

Open AccessArticle

Sea Ice Detection Based on Differential Delay-Doppler Maps from UK TechDemoSat-1

by Yongchao Zhu^1,2,3, Kegen Yu¹, Jingui Zou^1,2,* and Jens Wickert^3,4

¹ School of Geodesy and Geomatics and Collaborative Innovation Center for Geospatial Technology, Wuhan University, Wuhan 430079, China

² Key Laboratory of Precise Engineering and Industry Surveying, National Administration of Surveying, Mapping and Geoinformation, Wuhan 430079, China

³ German Research Centre for Geosciences, GFZ Potsdam 14473, Germany

⁴ Institute of Geodesy and Geoinformation Science, Technische Universität Berlin, Berlin 10623, Germany

Sensors 2017, 17(7), 1614; https://doi.org/10.3390/s17071614 - 12 Jul 2017

Cited by 47 | Viewed by 6714

Abstract

Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential [...] Read more.

Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential Delay-Doppler Maps (PN-D), to distinguish between sea ice and sea water using differential Delay-Doppler Maps (dDDMs). PS-D and PN-D make use of power-summation and pixel-number of dDDMs, respectively, to measure the degree of difference between two DDMs so as to determine the transition state (water-water, water-ice, ice-ice and ice-water) and hence ice and water are detected. Moreover, an adaptive incoherent averaging of DDMs is employed to improve the computational efficiency. A large number of DDMs recorded by UK TechDemoSat-1 (TDS-1) over the Arctic region are used to test the proposed sea ice detection methods. Through evaluating against ground-truth measurements from the Ocean Sea Ice SAF, the proposed PS-D and PN-D methods achieve a probability of detection of 99.72% and 99.69% respectively, while the probability of false detection is 0.28% and 0.31% respectively. Full article

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

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15 pages, 2736 KiB

Open AccessArticle

Radio-Frequency-Based NH₃-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

by Markus Dietrich^1,2, Gunter Hagen¹

, Willibald Reitmeier², Katharina Burger², Markus Hien², Philippe Grass², David Kubinski³, Jaco Visser³ and Ralf Moos^1,*

¹ Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95447 Bayreuth, Germany

² Continental Automotive GmbH, Division Powertrain, Siemensstraße 12, 93055 Regensburg, Germany

³ Ford Research and Innovation Center, 2101 Village Rd., Dearborn, MI 48124, USA

Sensors 2017, 17(7), 1615; https://doi.org/10.3390/s17071615 - 12 Jul 2017

Cited by 11 | Viewed by 7096

Abstract

The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic [...] Read more.

The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH₃ storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH₃ storage control, the influence of the storage degree on the catalyst performance, i.e., on NO_x conversion and NH₃ slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH₃ storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals. Full article

(This article belongs to the Section Chemical Sensors)

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24 pages, 15793 KiB

Open AccessArticle

Challenges in Wireless System Integration as Enablers for Indoor Context Aware Environments

by Peio López-Iturri^1,2

, Erik Aguirre^1,2

, Leyre Azpilicueta³

, José Javier Astrain^2,4

, Jesús Villandangos^2,4

and Francisco Falcone^1,2,*

¹ Electrical and Electronic Engineering Department, Public University of Navarre, Pamplona 31006, Spain

² Institute of Smart Cities, Public University of Navarre, Pamplona 31006, Spain

³ School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey 64849, Mexico

⁴ Mathematical Engineering and Computer Science Department, Public University of Navarre, Pamplona 31006, Spain

Sensors 2017, 17(7), 1616; https://doi.org/10.3390/s17071616 - 12 Jul 2017

Cited by 9 | Viewed by 4735

Abstract

The advent of fully interactive environments within Smart Cities and Smart Regions requires the use of multiple wireless systems. In the case of user-device interaction, which finds multiple applications such as Ambient Assisted Living, Intelligent Transportation Systems or Smart Grids, among others, large [...] Read more.

The advent of fully interactive environments within Smart Cities and Smart Regions requires the use of multiple wireless systems. In the case of user-device interaction, which finds multiple applications such as Ambient Assisted Living, Intelligent Transportation Systems or Smart Grids, among others, large amount of transceivers are employed in order to achieve anytime, anyplace and any device connectivity. The resulting combination of heterogeneous wireless network exhibits fundamental limitations derived from Coverage/Capacity relations, as a function of required Quality of Service parameters, required bit rate, energy restrictions and adaptive modulation and coding schemes. In this context, inherent transceiver density poses challenges in overall system operation, given by multiple node operation which increases overall interference levels. In this work, a deterministic based analysis applied to variable density wireless sensor network operation within complex indoor scenarios is presented, as a function of topological node distribution. The extensive analysis derives interference characterizations, both for conventional transceivers as well as wearables, which provide relevant information in terms of individual node configuration as well as complete network layout. Full article

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

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13 pages, 3297 KiB

Open AccessArticle

A Wi-Fi Union Mechanism for Internet Advertising Reciprocal Platform in Microenterprises

by Thi Thanh An Nguyen¹, Che-Pin Chang² and Shyan-Ming Yuan^2,*

¹ EECS International Graduate Programs, National Chiao Tung University, Hsinchu 300, Taiwan

² Department of Computer Science, National Chiao Tung University, Hsinchu 300, Taiwan

Sensors 2017, 17(7), 1617; https://doi.org/10.3390/s17071617 - 13 Jul 2017

Cited by 3 | Viewed by 4919

Abstract

With the evolution of the Internet and smartphone devices, Internet advertising has become one of the most important methods for delivering promotional marketing messages to customers. However, the efficiency of Internet advertising for microenterprise is not very high, since Wi-Fi advertising—which is limited [...] Read more.

With the evolution of the Internet and smartphone devices, Internet advertising has become one of the most important methods for delivering promotional marketing messages to customers. However, the efficiency of Internet advertising for microenterprise is not very high, since Wi-Fi advertising—which is limited by a small router coverage area—is mainly used. Moreover, because of the lack of money, microenterprises have been using low-cost methods to promote their products. Thus, enhancing the effectiveness of Wi-Fi advertising, and solving the problem of cost and the range of the views are now an essential investigation in this study. In this paper, we propose a reciprocal model with Wi-Fi union mechanism for Internet advertising based on fog computing architecture to enhance the efficiency of advertisement, reduce the cost, and increase the range of the views for microenterprise by using the Internet. In particular, the system was built in advertisers’, publishers’, and consumers’ sides. In our system, we use contribution point (CP) as an exchange value among the participants. Advertisers and publishers can get CP by helping the others in the system to promote their advertisements, increasing their CP by one unit. Similarly, advertisers and publishers can use their CP to ask for assistance from the others, decreasing their CP by one unit. The result shows that the system in a Wi-Fi union is easy to use, and advertisements can be seen by all customers who are using free Wi-Fi from the stores of the union. This method can solve the problem of cost and fixed consumer groups. Full article

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

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12 pages, 3163 KiB

Open AccessArticle

Fabrication of Flexible Arrayed Lactate Biosensor Based on Immobilizing LDH-NAD⁺ on NiO Film Modified by GO and MBs

by Jung-Chuan Chou^1,2,*

, Siao-Jie Yan¹, Yi-Hung Liao³, Chih-Hsien Lai^1,2

, You-Xiang Wu¹, Cian-Yi Wu¹, Hsiang-Yi Chen², Hong-Yu Huang² and Tong-Yu Wu⁴

¹ Graduate School of Electronic Engineering, National Yunlin University of Science and Technology, Douliu 64002, Taiwan

² Department of Electronic Engineering, National Yunlin University of Science and Technology, Douliu 64002, Taiwan

³ Department of Information and Electronic Commerce Management, TransWorld University, Douliu 64063, Taiwan

⁴ Graduate School of Mechanical Engineering, National Yunlin University of Science and Technology, Douliu 64002, Taiwan

Sensors 2017, 17(7), 1618; https://doi.org/10.3390/s17071618 - 12 Jul 2017

Cited by 15 | Viewed by 4656

Abstract

We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide (

{NAD}^{+}

) on nickel oxide (NiO) film, and which the average sensitivity could be enhanced by using graphene oxide (GO) and magnetic beads [...] Read more.

We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide (

{NAD}^{+}

) on nickel oxide (NiO) film, and which the average sensitivity could be enhanced by using graphene oxide (GO) and magnetic beads (MBs). By using GO and MBs, it exhibits excellent sensitivity (45.397 mV/mM) with a linearity of 0.992 in a range of 0.2 mM to 3 mM. According to the results of electrochemical impedance spectroscopy (EIS), the electron transfer resistance of LDH-

{NAD}^{+}

-MBs/GPTS/GO/NiO film was smaller than those of LDH-NAD⁺/GPTS/GO/NiO film and LDH-

{NAD}^{+}

/GPTS/NiO film, and it presented the outstanding electron transfer ability. After that, the limit of detection, anti-interference effect and bending test were also investigated. Full article

(This article belongs to the Section Biosensors)

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25 pages, 3075 KiB

Open AccessArticle

Cross Deployment Networking and Systematic Performance Analysis of Underwater Wireless Sensor Networks

by Zhengxian Wei^1,2, Min Song³, Guisheng Yin¹, Hongbin Wang¹, Xuefei Ma⁴

and Houbing Song^5,*

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

² Science and Technology on Underwater Acoustic Autagonizing Laboratory, Systems Engineering Research Institute, Beijing 100094, China

³ Information Technology Centre, Beijing Foreign Studies University, Beijing 100089, China

⁴ College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China

⁵ Department of Electrical, Computer, Software, and Systems Engineering, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA

Sensors 2017, 17(7), 1619; https://doi.org/10.3390/s17071619 - 12 Jul 2017

Cited by 6 | Viewed by 4181

Abstract

Underwater wireless sensor networks (UWSNs) have become a new hot research area. However, due to the work dynamics and harsh ocean environment, how to obtain an UWSN with the best systematic performance while deploying as few sensor nodes as possible and setting up [...] Read more.

Underwater wireless sensor networks (UWSNs) have become a new hot research area. However, due to the work dynamics and harsh ocean environment, how to obtain an UWSN with the best systematic performance while deploying as few sensor nodes as possible and setting up self-adaptive networking is an urgent problem that needs to be solved. Consequently, sensor deployment, networking, and performance calculation of UWSNs are challenging issues, hence the study in this paper centers on this topic and three relevant methods and models are put forward. Firstly, the normal body-centered cubic lattice to cross body-centered cubic lattice (CBCL) has been improved, and a deployment process and topology generation method are built. Then most importantly, a cross deployment networking method (CDNM) for UWSNs suitable for the underwater environment is proposed. Furthermore, a systematic quar-performance calculation model (SQPCM) is proposed from an integrated perspective, in which the systematic performance of a UWSN includes coverage, connectivity, durability and rapid-reactivity. Besides, measurement models are established based on the relationship between systematic performance and influencing parameters. Finally, the influencing parameters are divided into three types, namely, constraint parameters, device performance and networking parameters. Based on these, a networking parameters adjustment method (NPAM) for optimized systematic performance of UWSNs has been presented. The simulation results demonstrate that the approach proposed in this paper is feasible and efficient in networking and performance calculation of UWSNs. Full article

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

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22 pages, 3927 KiB

Open AccessArticle

A Study on the Data Compression Technology-Based Intelligent Data Acquisition (IDAQ) System for Structural Health Monitoring of Civil Structures

by Gwanghee Heo

and Joonryong Jeon^*

Department of Civil and Environment Engineering, Konyang University, 121 Daehak-ro, Nonsan, Chungnam 320-711, Korea

Sensors 2017, 17(7), 1620; https://doi.org/10.3390/s17071620 - 12 Jul 2017

Cited by 14 | Viewed by 4830

Abstract

In this paper, a data compression technology-based intelligent data acquisition (IDAQ) system was developed for structural health monitoring of civil structures, and its validity was tested using random signals (El-Centro seismic waveform). The IDAQ system was structured to include a high-performance CPU with [...] Read more.

In this paper, a data compression technology-based intelligent data acquisition (IDAQ) system was developed for structural health monitoring of civil structures, and its validity was tested using random signals (El-Centro seismic waveform). The IDAQ system was structured to include a high-performance CPU with large dynamic memory for multi-input and output in a radio frequency (RF) manner. In addition, the embedded software technology (EST) has been applied to it to implement diverse logics needed in the process of acquiring, processing and transmitting data. In order to utilize IDAQ system for the structural health monitoring of civil structures, this study developed an artificial filter bank by which structural dynamic responses (acceleration) were efficiently acquired, and also optimized it on the random El-Centro seismic waveform. All techniques developed in this study have been embedded to our system. The data compression technology-based IDAQ system was proven valid in acquiring valid signals in a compressed size. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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9 pages, 4284 KiB

Open AccessArticle

Effect of Distributed Mass on the Node, Frequency, and Sensitivity of Resonant-Mode Based Cantilevers

by Kewei Zhang^*, Qianke Zhu and Zhe Chen

School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China

Sensors 2017, 17(7), 1621; https://doi.org/10.3390/s17071621 - 13 Jul 2017

Cited by 5 | Viewed by 4988

Abstract

We derived an analytical expression for a resonant-mode based bi-layered cantilever with distributed mass load. The behavior of mode of vibration, nodal position, frequency shift, as well as sensitivity under different mass load distributions was theoretically studied. The theoretical results suggested that asymmetric [...] Read more.

We derived an analytical expression for a resonant-mode based bi-layered cantilever with distributed mass load. The behavior of mode of vibration, nodal position, frequency shift, as well as sensitivity under different mass load distributions was theoretically studied. The theoretical results suggested that asymmetric mass load distribution leads to the shift of nodes as well as the sensitive regions of a resonant-mode based cantilever. n − 1 local maximal sensitivities and n − 1 local minimal sensitivities are observed when the cantilever vibrates in the nth-order resonance. The maximal sensitivity is found at the first local maximal sensitivity and the behavior of mass load length as a function of the maximal sensitivity follows the rule of an exponent decaying function. The sensitivity increases as the load mass increases for the same mass load distribution, but the corresponding slopes are different. Full article

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

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13 pages, 6017 KiB

Open AccessArticle

The Regular Interaction Pattern among Odorants of the Same Type and Its Application in Odor Intensity Assessment

by Luchun Yan¹, Jiemin Liu^2,*, Shen Jiang², Chuandong Wu² and Kewei Gao¹

¹ School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China

² School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China

Sensors 2017, 17(7), 1624; https://doi.org/10.3390/s17071624 - 13 Jul 2017

Cited by 41 | Viewed by 5624

Abstract

The olfactory evaluation function (e.g., odor intensity rating) of e-nose is always one of the most challenging issues in researches about odor pollution monitoring. But odor is normally produced by a set of stimuli, and odor interactions among constituents significantly influenced their mixture’s [...] Read more.

The olfactory evaluation function (e.g., odor intensity rating) of e-nose is always one of the most challenging issues in researches about odor pollution monitoring. But odor is normally produced by a set of stimuli, and odor interactions among constituents significantly influenced their mixture’s odor intensity. This study investigated the odor interaction principle in odor mixtures of aldehydes and esters, respectively. Then, a modified vector model (MVM) was proposed and it successfully demonstrated the similarity of the odor interaction pattern among odorants of the same type. Based on the regular interaction pattern, unlike a determined empirical model only fit for a specific odor mixture in conventional approaches, the MVM distinctly simplified the odor intensity prediction of odor mixtures. Furthermore, the MVM also provided a way of directly converting constituents’ chemical concentrations to their mixture’s odor intensity. By combining the MVM with usual data-processing algorithm of e-nose, a new e-nose system was established for an odor intensity rating. Compared with instrumental analysis and human assessor, it exhibited accuracy well in both quantitative analysis (Pearson correlation coefficient was 0.999 for individual aldehydes (n = 12), 0.996 for their binary mixtures (n = 36) and 0.990 for their ternary mixtures (n = 60)) and odor intensity assessment (Pearson correlation coefficient was 0.980 for individual aldehydes (n = 15), 0.973 for their binary mixtures (n = 24), and 0.888 for their ternary mixtures (n = 25)). Thus, the observed regular interaction pattern is considered an important foundation for accelerating extensive application of olfactory evaluation in odor pollution monitoring. Full article

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

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18 pages, 11519 KiB

Open AccessArticle

Phenoliner: A New Field Phenotyping Platform for Grapevine Research

by Anna Kicherer^1,*, Katja Herzog¹, Nele Bendel¹, Hans-Christian Klück², Andreas Backhaus², Markus Wieland³, Johann Christian Rose³, Lasse Klingbeil³

, Thomas Läbe⁴, Christian Hohl⁵, Willi Petry⁵, Heiner Kuhlmann³, Udo Seiffert²

and Reinhard Töpfer¹

¹ Julius Kühn-Institut, Federal Research Centre of Cultivated Plants, Institute for Grapevine Breeding Geilweilerhof, 76833 Siebeldingen, Germany

² Fraunhofer Institute for Factory Operation and Automation (IFF), Biosystems Engineering, Sandtorstr. 22, 39108 Magdeburg, Germany

³ Institute of Geodesy and Geoinformation, Department of Geodesy, University of Bonn, Nussallee 17, 53115 Bonn, Germany

⁴ Institute of Geodesy and Geoinformation, Department of Photogrammetry, University of Bonn, Nussallee 15, 53115 Bonn, Germany

⁵ ERO-Gerätebau GmbH, Simmerner Str. 20,55469 Niederkumbd, Germany

Sensors 2017, 17(7), 1625; https://doi.org/10.3390/s17071625 - 14 Jul 2017

Cited by 45 | Viewed by 9473

Abstract

In grapevine research the acquisition of phenotypic data is largely restricted to the field due to its perennial nature and size. The methodologies used to assess morphological traits and phenology are mainly limited to visual scoring. Some measurements for biotic and abiotic stress, [...] Read more.

In grapevine research the acquisition of phenotypic data is largely restricted to the field due to its perennial nature and size. The methodologies used to assess morphological traits and phenology are mainly limited to visual scoring. Some measurements for biotic and abiotic stress, as well as for quality assessments, are done by invasive measures. The new evolving sensor technologies provide the opportunity to perform non-destructive evaluations of phenotypic traits using different field phenotyping platforms. One of the biggest technical challenges for field phenotyping of grapevines are the varying light conditions and the background. In the present study the Phenoliner is presented, which represents a novel type of a robust field phenotyping platform. The vehicle is based on a grape harvester following the concept of a moveable tunnel. The tunnel it is equipped with different sensor systems (RGB and NIR camera system, hyperspectral camera, RTK-GPS, orientation sensor) and an artificial broadband light source. It is independent from external light conditions and in combination with artificial background, the Phenoliner enables standardised acquisition of high-quality, geo-referenced sensor data. Full article

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

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14 pages, 2219 KiB

Open AccessArticle

Enhanced Handover Decision Algorithm in Heterogeneous Wireless Network

by Radhwan Mohamed Abdullah^*,† and Zuriati Ahmad Zukarnain^*,†

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

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1626; https://doi.org/10.3390/s17071626 - 14 Jul 2017

Cited by 37 | Viewed by 6168

Abstract

Transferring a huge amount of data between different network locations over the network links depends on the network’s traffic capacity and data rate. Traditionally, a mobile device may be moved to achieve the operations of vertical handover, considering only one criterion, that is [...] Read more.

Transferring a huge amount of data between different network locations over the network links depends on the network’s traffic capacity and data rate. Traditionally, a mobile device may be moved to achieve the operations of vertical handover, considering only one criterion, that is the Received Signal Strength (RSS). The use of a single criterion may cause service interruption, an unbalanced network load and an inefficient vertical handover. In this paper, we propose an enhanced vertical handover decision algorithm based on multiple criteria in the heterogeneous wireless network. The algorithm consists of three technology interfaces: Long-Term Evolution (LTE), Worldwide interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN). It also employs three types of vertical handover decision algorithms: equal priority, mobile priority and network priority. The simulation results illustrate that the three types of decision algorithms outperform the traditional network decision algorithm in terms of handover number probability and the handover failure probability. In addition, it is noticed that the network priority handover decision algorithm produces better results compared to the equal priority and the mobile priority handover decision algorithm. Finally, the simulation results are validated by the analytical model. Full article

(This article belongs to the Section Sensor Networks)

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15 pages, 2348 KiB

Open AccessArticle

Mechanomyography and Torque during FES-Evoked Muscle Contractions to Fatigue in Individuals with Spinal Cord Injury

by Nor Zainah Mohamad¹, Nur Azah Hamzaid^1,*, Glen M. Davis^1,2, Ahmad Khairi Abdul Wahab¹ and Nazirah Hasnan³

¹ Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia

² Clinical Exercise and Rehabilitation Unit, Discipline of Exercise and Sports Sciences, Faculty of Health Sciences, University of Sydney, Lidcombe, NSW 2141, Australia

³ Department of Rehabilitation Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia

Sensors 2017, 17(7), 1627; https://doi.org/10.3390/s17071627 - 14 Jul 2017

Cited by 13 | Viewed by 8420

Abstract

A mechanomyography muscle contraction (MC) sensor, affixed to the skin surface, was used to quantify muscle tension during repetitive functional electrical stimulation (FES)-evoked isometric rectus femoris contractions to fatigue in individuals with spinal cord injury (SCI). Nine persons with motor complete SCI were [...] Read more.

A mechanomyography muscle contraction (MC) sensor, affixed to the skin surface, was used to quantify muscle tension during repetitive functional electrical stimulation (FES)-evoked isometric rectus femoris contractions to fatigue in individuals with spinal cord injury (SCI). Nine persons with motor complete SCI were seated on a commercial muscle dynamometer that quantified peak torque and average torque outputs, while measurements from the MC sensor were simultaneously recorded. MC-sensor-predicted measures of dynamometer torques, including the signal peak (SP) and signal average (SA), were highly associated with isometric knee extension peak torque (SP: r = 0.91, p < 0.0001), and average torque (SA: r = 0.89, p < 0.0001), respectively. Bland-Altman (BA) analyses with Lin’s concordance (ρ_C) revealed good association between MC-sensor-predicted peak muscle torques (SP; ρ_C = 0.91) and average muscle torques (SA; ρ_C = 0.89) with the equivalent dynamometer measures, over a range of FES current amplitudes. The relationship of dynamometer torques and predicted MC torques during repetitive FES-evoked muscle contraction to fatigue were moderately associated (SP: r = 0.80, p < 0.0001; SA: r = 0.77; p < 0.0001), with BA associations between the two devices fair-moderate (SP; ρ_C = 0.70: SA; ρ_C = 0.30). These findings demonstrated that a skin-surface muscle mechanomyography sensor was an accurate proxy for electrically-evoked muscle contraction torques when directly measured during isometric dynamometry in individuals with SCI. The novel application of the MC sensor during FES-evoked muscle contractions suggested its possible application for real-world tasks (e.g., prolonged sit-to-stand, stepping,) where muscle forces during fatiguing activities cannot be directly measured. Full article

(This article belongs to the Section Biosensors)

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15 pages, 953 KiB

Open AccessArticle

A Pulse Rate Detection Method for Mouse Application Based on Multi-PPG Sensors

by Shu-Tyng Lin

, Wei-Hao Chen and Yuan-Hsiang Lin^*

Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan

Sensors 2017, 17(7), 1628; https://doi.org/10.3390/s17071628 - 14 Jul 2017

Cited by 25 | Viewed by 7179

Abstract

Heart rate is an important physiological parameter for healthcare. Among measurement methods, photoplethysmography (PPG) is an easy and convenient method for pulse rate detection. However, as the PPG signal faces the challenge of motion artifacts and is constrained by the position chosen, the [...] Read more.

Heart rate is an important physiological parameter for healthcare. Among measurement methods, photoplethysmography (PPG) is an easy and convenient method for pulse rate detection. However, as the PPG signal faces the challenge of motion artifacts and is constrained by the position chosen, the purpose of this paper is to implement a comfortable and easy-to-use multi-PPG sensor module combined with a stable and accurate real-time pulse rate detection method on a computer mouse. A weighted average method for multi-PPG sensors is used to adjust the weight of each signal channel in order to raise the accuracy and stability of the detected signal, therefore reducing the disturbance of noise under the environment of moving effectively and efficiently. According to the experiment results, the proposed method can increase the usability and probability of PPG signal detection on palms. Full article

(This article belongs to the Special Issue Advanced Physiological Sensing)

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29 pages, 641 KiB

Open AccessArticle

Real-Time Communication Support for Underwater Acoustic Sensor Networks

by Rodrigo Santos^1,*,‡

, Javier Orozco^1,§, Matias Micheletto^1,§, Sergio F. Ochoa^2,§

, Roc Meseguer^3,§

, Pere Millan^4,§

and Carlos Molina^4,§

¹ Department of Electrical Engineering and Computers, Universidad Nacional del Sur, CONICET, Bahía Blanca 8000, Argentina

² Computer Science Department, Universidad de Chile, Santiago 8370456, Chile

³ Department of Computer Architecture, Universitat Politècnica de Catalunya, Barcelona 08034, Spain

⁴ Department of Computer Engineering and Mathematics, Universitat Rovira i Virgili, Tarragona 43007, Spain

^‡ Current address: IIIE, UNS-CONICET, Alem 1253, Bahía Blanca 8000, Argentina.

^§ These authors contributed equally to this work.

Sensors 2017, 17(7), 1629; https://doi.org/10.3390/s17071629 - 14 Jul 2017

Cited by 14 | Viewed by 6420

Abstract

Underwater sensor networks represent an important and promising field of research due to the large diversity of underwater ubiquitous applications that can be supported by these networks, e.g., systems that deliver tsunami and oil spill warnings, or monitor submarine ecosystems. Most of these [...] Read more.

Underwater sensor networks represent an important and promising field of research due to the large diversity of underwater ubiquitous applications that can be supported by these networks, e.g., systems that deliver tsunami and oil spill warnings, or monitor submarine ecosystems. Most of these monitoring and warning systems require real-time communication in wide area networks that have a low density of nodes. The underwater communication medium involved in these networks is very harsh and imposes strong restrictions to the communication process. In this scenario, the real-time transmission of information is done mainly using acoustic signals, since the network nodes are not physically close. The features of the communication scenario and the requirements of the communication process represent major challenges for designers of both, communication protocols and monitoring and warning systems. The lack of models to represent these networks is the main stumbling block for the proliferation of underwater ubiquitous systems. This paper presents a real-time communication model for underwater acoustic sensor networks (UW-ASN) that are designed to cover wide areas with a low density of nodes, using any-to-any communication. This model is analytic, considers two solution approaches for scheduling the real-time messages, and provides a time-constraint analysis for the network performance. Using this model, the designers of protocols and underwater ubiquitous systems can quickly prototype and evaluate their solutions in an evolving way, in order to determine the best solution to the problem being addressed. The suitability of the proposal is illustrated with a case study that shows the performance of a UW-ASN under several initial conditions. This is the first analytic model for representing real-time communication in this type of network, and therefore, it opens the door for the development of underwater ubiquitous systems for several application scenarios. Full article

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

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11 pages, 2776 KiB

Open AccessArticle

A Label-Free Fluorescent Array Sensor Utilizing Liposome Encapsulating Calcein for Discriminating Target Proteins by Principal Component Analysis

by Ryota Imamura¹, Naoki Murata¹, Toshinori Shimanouchi², Kaoru Yamashita¹, Masayuki Fukuzawa¹ and Minoru Noda^1,*

¹ Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan

² Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan

Sensors 2017, 17(7), 1630; https://doi.org/10.3390/s17071630 - 15 Jul 2017

Cited by 10 | Viewed by 6111

Abstract

A new fluorescent arrayed biosensor has been developed to discriminate species and concentrations of target proteins by using plural different phospholipid liposome species encapsulating fluorescent molecules, utilizing differences in permeation of the fluorescent molecules through the membrane to modulate liposome-target protein interactions. This [...] Read more.

A new fluorescent arrayed biosensor has been developed to discriminate species and concentrations of target proteins by using plural different phospholipid liposome species encapsulating fluorescent molecules, utilizing differences in permeation of the fluorescent molecules through the membrane to modulate liposome-target protein interactions. This approach proposes a basically new label-free fluorescent sensor, compared with the common technique of developed fluorescent array sensors with labeling. We have confirmed a high output intensity of fluorescence emission related to characteristics of the fluorescent molecules dependent on their concentrations when they leak from inside the liposomes through the perturbed lipid membrane. After taking an array image of the fluorescence emission from the sensor using a CMOS imager, the output intensities of the fluorescence were analyzed by a principal component analysis (PCA) statistical method. It is found from PCA plots that different protein species with several concentrations were successfully discriminated by using the different lipid membranes with high cumulative contribution ratio. We also confirmed that the accuracy of the discrimination by the array sensor with a single shot is higher than that of a single sensor with multiple shots. Full article

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

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21 pages, 9799 KiB

Open AccessArticle

Design and Implementation of a Smart Home System Using Multisensor Data Fusion Technology

by Yu-Liang Hsu^1,*

, Po-Huan Chou², Hsing-Cheng Chang¹, Shyan-Lung Lin¹, Shih-Chin Yang³, Heng-Yi Su⁴, Chih-Chien Chang¹, Yuan-Sheng Cheng¹ and Yu-Chen Kuo¹

¹ Department of Automatic Control Engineering, Feng Chia University (FCU), No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan

² Department of Mechanical and Mechatronics Systems Research Labs., Industrial Technology Research Institute (ITRI), 195, Sec. 4, Chung Hsing Rd., Chutung, Hsinchu 31040, Taiwan

³ Department of Mechanical Engineering, National Taiwan University (NTU), No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan

⁴ Department of Electrical Engineering, Feng Chia University (FCU), No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan

Sensors 2017, 17(7), 1631; https://doi.org/10.3390/s17071631 - 15 Jul 2017

Cited by 84 | Viewed by 14253

Abstract

This paper aims to develop a multisensor data fusion technology-based smart home system by integrating wearable intelligent technology, artificial intelligence, and sensor fusion technology. We have developed the following three systems to create an intelligent smart home environment: (1) a wearable motion sensing [...] Read more.

This paper aims to develop a multisensor data fusion technology-based smart home system by integrating wearable intelligent technology, artificial intelligence, and sensor fusion technology. We have developed the following three systems to create an intelligent smart home environment: (1) a wearable motion sensing device to be placed on residents’ wrists and its corresponding 3D gesture recognition algorithm to implement a convenient automated household appliance control system; (2) a wearable motion sensing device mounted on a resident’s feet and its indoor positioning algorithm to realize an effective indoor pedestrian navigation system for smart energy management; (3) a multisensor circuit module and an intelligent fire detection and alarm algorithm to realize a home safety and fire detection system. In addition, an intelligent monitoring interface is developed to provide in real-time information about the smart home system, such as environmental temperatures, CO concentrations, communicative environmental alarms, household appliance status, human motion signals, and the results of gesture recognition and indoor positioning. Furthermore, an experimental testbed for validating the effectiveness and feasibility of the smart home system was built and verified experimentally. The results showed that the 3D gesture recognition algorithm could achieve recognition rates for automated household appliance control of 92.0%, 94.8%, 95.3%, and 87.7% by the 2-fold cross-validation, 5-fold cross-validation, 10-fold cross-validation, and leave-one-subject-out cross-validation strategies. For indoor positioning and smart energy management, the distance accuracy and positioning accuracy were around 0.22% and 3.36% of the total traveled distance in the indoor environment. For home safety and fire detection, the classification rate achieved 98.81% accuracy for determining the conditions of the indoor living environment. Full article

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

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17 pages, 1983 KiB

Open AccessArticle

A Multiscale Approach to the Smart Deployment of Micro-Sensors over Lightweight Structures

by Giovanni Capellari^1,†, Francesco Caimmi^2,†

, Matteo Bruggi^1,†

and Stefano Mariani^1,*,†

¹ Dipartimento di Ingegneria Civile e Ambientale, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy

² Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, Piazza L. daVinci 32, 20133 Milano, Italy

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1632; https://doi.org/10.3390/s17071632 - 15 Jul 2017

Cited by 3 | Viewed by 4167

Abstract

A topology optimization approach has been recently proposed to maximize the sensitivity to damage of measurements, collected through a network of sensors to be deployed over thin plates for structural health monitoring purposes. Within such a frame, damage is meant as a change [...] Read more.

A topology optimization approach has been recently proposed to maximize the sensitivity to damage of measurements, collected through a network of sensors to be deployed over thin plates for structural health monitoring purposes. Within such a frame, damage is meant as a change in the structural health characterized by a reduction of relevant stiffness and load-carrying properties. The sensitivity to a damage of unknown amplitude and location is computed by comparing the response to the external actions of the healthy structure and of a set of auxiliary damaged structures, each one featuring reduced mechanical properties in a small region only. The topology optimization scheme has been devised to properly account for the information coming from all of the sensors to be placed on the structure and for damage depending on its location. In this work, we extend the approach within a multiscale frame to account for three different length scales: a macroscopic one, linked to the dimensions of the whole structure to be monitored; a mesoscopic one, linked to the characteristic size of the damaged region; a microscopic one, linked to the size of inertial microelectromechanical systems (MEMS) to be used within a marginally-invasive health monitoring system. Results are provided for a square plate and for a section of fuselage with stiffeners, to show how the micro-sensors have to be deployed to maximize the capability to detect a damage, to assess the sensitivity of the results to the measurement noise and to also discuss the speedup in designing the network topology against a standard single-scale approach. Full article

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

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15 pages, 2241 KiB

Open AccessArticle

Non-Convex Sparse and Low-Rank Based Robust Subspace Segmentation for Data Mining

by Wenlong Cheng^1,2

, Mingbo Zhao^1,*, Naixue Xiong³

and Kwok Tai Chui²

¹ School of Information Science & Technology, Donghua University, Shanghai 200051, China

² Department of Electronic Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong, China

³ School of Mathematics and Computer Science, Northeastern State University, Tahlequah, OK 74464, USA

Sensors 2017, 17(7), 1633; https://doi.org/10.3390/s17071633 - 15 Jul 2017

Cited by 18 | Viewed by 4719

Abstract

Parsimony, including sparsity and low-rank, has shown great importance for data mining in social networks, particularly in tasks such as segmentation and recognition. Traditionally, such modeling approaches rely on an iterative algorithm that minimizes an objective function with convex l₁-norm or [...] Read more.

Parsimony, including sparsity and low-rank, has shown great importance for data mining in social networks, particularly in tasks such as segmentation and recognition. Traditionally, such modeling approaches rely on an iterative algorithm that minimizes an objective function with convex l₁-norm or nuclear norm constraints. However, the obtained results by convex optimization are usually suboptimal to solutions of original sparse or low-rank problems. In this paper, a novel robust subspace segmentation algorithm has been proposed by integrating l_p-norm and Schatten p-norm constraints. Our so-obtained affinity graph can better capture local geometrical structure and the global information of the data. As a consequence, our algorithm is more generative, discriminative and robust. An efficient linearized alternating direction method is derived to realize our model. Extensive segmentation experiments are conducted on public datasets. The proposed algorithm is revealed to be more effective and robust compared to five existing algorithms. Full article

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

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9 pages, 2654 KiB

Open AccessArticle

Development of Three-Dimensional Dental Scanning Apparatus Using Structured Illumination

by Jae Sung Ahn¹

, Anjin Park¹, Ju Wan Kim²

, Byeong Ha Lee³ and Joo Beom Eom^1,*

¹ Medical Photonics Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju 61007, Korea

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

³ School of Information and Communications, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

Sensors 2017, 17(7), 1634; https://doi.org/10.3390/s17071634 - 15 Jul 2017

Cited by 24 | Viewed by 6567

Abstract

We demonstrated a three-dimensional (3D) dental scanning apparatus based on structured illumination. A liquid lens was used for tuning focus and a piezomotor stage was used for the shift of structured light. A simple algorithm, which detects intensity modulation, was used to perform [...] Read more.

We demonstrated a three-dimensional (3D) dental scanning apparatus based on structured illumination. A liquid lens was used for tuning focus and a piezomotor stage was used for the shift of structured light. A simple algorithm, which detects intensity modulation, was used to perform optical sectioning with structured illumination. We reconstructed a 3D point cloud, which represents the 3D coordinates of the digitized surface of a dental gypsum cast by piling up sectioned images. We performed 3D registration of an individual 3D point cloud, which includes alignment and merging the 3D point clouds to exhibit a 3D model of the dental cast. Full article

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

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8 pages, 2569 KiB

Open AccessArticle

Passive Downhole Pressure Sensor Based on Surface Acoustic Wave Technology

by Sully M. M. Quintero^*, Sávio W. O. Figueiredo

, Victor L. Takahashi, Roberth A. W. Llerena and Arthur M. B. Braga

Mechanical Engineering Department, Pontifical Catholic University of Rio de Janeiro, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, Brazil

Sensors 2017, 17(7), 1635; https://doi.org/10.3390/s17071635 - 15 Jul 2017

Cited by 28 | Viewed by 7763

Abstract

A passive surface acoustic wave (SAW) pressure sensor was developed for real-time pressure monitoring in downhole application. The passive pressure sensor consists of a SAW resonator, which is attached to a circular metal diaphragm used as a pressure transducer. While the membrane deflects [...] Read more.

A passive surface acoustic wave (SAW) pressure sensor was developed for real-time pressure monitoring in downhole application. The passive pressure sensor consists of a SAW resonator, which is attached to a circular metal diaphragm used as a pressure transducer. While the membrane deflects as a function of pressure applied, the frequency response changes due to the variation of the SAW propagation parameters. The sensitivity and linearity of the SAW pressure sensor were measured to be 8.3 kHz/bar and 0.999, respectively. The experimental results were validated with a hybrid analytical–numerical analysis. The good results combined with the robust design and packaging for harsh environment demonstrated it to be a promising sensor for industrial applications. Full article

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

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18 pages, 1549 KiB

Open AccessArticle

Localization with Graph Diffusion Property

by Pengpeng Chen, Yuqing Yin, Shouwan Gao, Qiang Niu^* and Jun Gu

School of Computer Science and Technology, China University of Mining and Technology, Xuzhou 221116, China

Sensors 2017, 17(7), 1636; https://doi.org/10.3390/s17071636 - 15 Jul 2017

Cited by 1 | Viewed by 4409

Abstract

Node localization is an essential issue in wireless sensor networks (WSNs). Many range-free localization methods have been proposed to satisfy the requirement of low-system cost. However, some range-free methods only depend on network connectivity, and others only utilize the proximity information attached in [...] Read more.

Node localization is an essential issue in wireless sensor networks (WSNs). Many range-free localization methods have been proposed to satisfy the requirement of low-system cost. However, some range-free methods only depend on network connectivity, and others only utilize the proximity information attached in neighborhood ordering. To employ the strength of the above two aspects, this paper introduces a new metric system called Combined and Weighted Diffusion Distance (CWDD). CWDD is designed to obtain the relative distance among nodes based on both graph diffusion property and neighbor information. We implement our design by embedding CWDD into two well-known localization algorithms and evaluate it by extensive simulations. Results show that our design improves the localization performance in large scale and non-uniform sensor networks, which reduces positioning errors by as much as 26%. Full article

(This article belongs to the Special Issue Mobile Sensing Applications)

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14 pages, 3139 KiB

Open AccessArticle

Frame Transmission Efficiency-Based Cross-Layer Congestion Notification Scheme in Wireless Ad Hoc Networks

by Huaguang He^1,2,†, Taoshen Li^2,3,†, Luting Feng^2,3,† and Jin Ye^2,3,*,†

¹ School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641, China

² School of Computer and Electronic Information, Guangxi University, Nanning 530004, China

³ Guangxi Key Laboratory of Multimedia Communications and Network Technology (Cultivating Base), Guangxi University, Nanning 530004, China

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1637; https://doi.org/10.3390/s17071637 - 15 Jul 2017

Cited by 6 | Viewed by 3537

Abstract

Different from the traditional wired network, the fundamental cause of transmission congestion in wireless ad hoc networks is medium contention. How to utilize the congestion state from the MAC (Media Access Control) layer to adjust the transmission rate is core work for transport [...] Read more.

Different from the traditional wired network, the fundamental cause of transmission congestion in wireless ad hoc networks is medium contention. How to utilize the congestion state from the MAC (Media Access Control) layer to adjust the transmission rate is core work for transport protocol design. However, recent works have shown that the existing cross-layer congestion detection solutions are too complex to be deployed or not able to characterize the congestion accurately. We first propose a new congestion metric called frame transmission efficiency (i.e., the ratio of successful transmission delay to the frame service delay), which describes the medium contention in a fast and accurate manner. We further present the design and implementation of RECN (ECN and the ratio of successful transmission delay to the frame service delay in the MAC layer, namely, the frame transmission efficiency), a general supporting scheme that adjusts the transport sending rate through a standard ECN (Explicit Congestion Notification) signaling method. Our method can be deployed on commodity switches with small firmware updates, while making no modification on end hosts. We integrate RECN transparently (i.e., without modification) with TCP on NS2 simulation. The experimental results show that RECN remarkably improves network goodput across multiple concurrent TCP flows. Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 2839 KiB

Open AccessArticle

Electrochemical Flow-ELISA for Rapid and Sensitive Determination of Microcystin-LR Using Automated Sequential Injection System

by Lesedi Lebogang^1,2,*

, Jongjit Jantra^1,3, Martin Hedström^1,3 and Bo Mattiasson^1,3

¹ Department of Biotechnology, Lund University, Box 124, SE-22100 Lund, Sweden

² Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Private Bag 16, Plot 10071, Palapye, Botswana

³ CapSenze Biosystems AB, Scheelevägen 22, SE-22363 Lund, Sweden

Sensors 2017, 17(7), 1639; https://doi.org/10.3390/s17071639 - 16 Jul 2017

Cited by 13 | Viewed by 5875

Abstract

An amperometric immunoanalysis system based on monoclonal antibodies immobilized on Sepharose beads and packed into a micro-immunocolumn was developed for the quantification of microcystin-LR. Microcystin-LR (MCLR) was used as a reference microcystin variant. Inside the immunocolumn, free microcystins and microcystin-horseradish peroxidase (tracer) were [...] Read more.

An amperometric immunoanalysis system based on monoclonal antibodies immobilized on Sepharose beads and packed into a micro-immunocolumn was developed for the quantification of microcystin-LR. Microcystin-LR (MCLR) was used as a reference microcystin variant. Inside the immunocolumn, free microcystins and microcystin-horseradish peroxidase (tracer) were sequentially captured by the immobilized antibodies, and the detection was performed electrochemically using Super AquaBlue ELISA substrate 2,2′-azinobis(3-ethylbenzothiazoline-sulfonic acid) (ABTS). The ABTS^●+ generated by enzymatic oxidation of ABTS was electrochemically determined at a carbon working electrode by applying a reduction potential set at 0.4 V versus Ag/AgCl reference electrode. The peak current intensity was inversely proportional to the amount of analyte bound to the immunocolumn. The amperometric flow-ELISA system, which was automatically controlled through the CapSenze^TM (Lund, Sweden) computer software, enabled determination of MCLR as low as 0.01 µg/L. The assay time was very short (20 min for one assay cycle). In addition, the electrochemical signals were not significantly affected by possible interferences which could be present in the real samples. Along with the simplicity of automation, this makes the developed method a promising tool for use in water quality assessment. Full article

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

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12 pages, 1041 KiB

Open AccessArticle

Sensing Responses Based on Transfer Characteristics of InAs Nanowire Field-Effect Transistors

by Alex C. Tseng^1,2

, David Lynall^1,2

, Igor Savelyev¹, Marina Blumin¹, Shiliang Wang³ and Harry E. Ruda^1,2,*

¹ Centre for Advanced Nanotechnology, University of Toronto, 170 College Street, Toronto, ON M5S 3E4, Canada

² Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, ON M5S 3E4, Canada

³ Defence Research and Development Canada Suffield, Medicine Hat, AB T1A 8K6, Canada

Sensors 2017, 17(7), 1640; https://doi.org/10.3390/s17071640 - 16 Jul 2017

Cited by 14 | Viewed by 5784

Abstract

Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that [...] Read more.

Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that can be used in applications such as point-of-care testing for patients diagnosed with chronic diseases. Here, we propose devices based on a parallel configuration of InAs nanowires and investigate sensor responses from measurements of conductance over time and FET characteristics. The devices were tested in controlled concentrations of vapour containing acetic acid, 2-butanone and methanol. After adsorption of analyte molecules, trends in the transient current and transfer curves are correlated with the nature of the surface interaction. Specifically, we observed proportionality between acetic acid concentration and relative conductance change, off current and surface charge density extracted from subthreshold behaviour. We suggest the origin of the sensing response to acetic acid as a two-part, reversible acid-base and redox reaction between acetic acid, InAs and its native oxide that forms slow, donor-like states at the nanowire surface. We further describe a simple model that is able to distinguish the occurrence of physical versus chemical adsorption by comparing the values of the extracted surface charge density. These studies demonstrate that InAs nanowires can produce a multitude of sensor responses for the purpose of developing next generation, multi-dimensional sensor applications. Full article

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

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16 pages, 15375 KiB

Open AccessArticle

Development and Application of a Structural Health Monitoring System Based on Wireless Smart Aggregates

by Shi Yan^1,*

, Haoyan Ma¹, Peng Li², Gangbing Song²

and Jianxin Wu³

¹ School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

² Department of Mechanical Engineering, University of Houston, Houston, TX 77004, USA

³ Liaoning Electric Power Survey & Design Institute, Shenyang 110179, China

Sensors 2017, 17(7), 1641; https://doi.org/10.3390/s17071641 - 17 Jul 2017

Cited by 78 | Viewed by 13591

Abstract

Structural health monitoring (SHM) systems can improve the safety and reliability of structures, reduce maintenance costs, and extend service life. Research on concrete SHMs using piezoelectric-based smart aggregates have reached great achievements. However, the newly developed techniques have not been widely applied in [...] Read more.

Structural health monitoring (SHM) systems can improve the safety and reliability of structures, reduce maintenance costs, and extend service life. Research on concrete SHMs using piezoelectric-based smart aggregates have reached great achievements. However, the newly developed techniques have not been widely applied in practical engineering, largely due to the wiring problems associated with large-scale structural health monitoring. The cumbersome wiring requires much material and labor work, and more importantly, the associated maintenance work is also very heavy. Targeting a practical large scale concrete crack detection (CCD) application, a smart aggregates-based wireless sensor network system is proposed for the CCD application. The developed CCD system uses Zigbee 802.15.4 protocols, and is able to perform dynamic stress monitoring, structural impact capturing, and internal crack detection. The system has been experimentally validated, and the experimental results demonstrated the effectiveness of the proposed system. This work provides important support for practical CCD applications using wireless smart aggregates. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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27 pages, 511 KiB

Open AccessArticle

Extending Wireless Rechargeable Sensor Network Life without Full Knowledge

by Najeeb W. Najeeb^* and Carrick Detweiler

Computer Science and Engineering Department, University of Nebraska, Lincoln, NE 68588, USA

Sensors 2017, 17(7), 1642; https://doi.org/10.3390/s17071642 - 17 Jul 2017

Cited by 18 | Viewed by 5751

Abstract

When extending the life of Wireless Rechargeable Sensor Networks (WRSN), one challenge is charging networks as they grow larger. Overcoming this limitation will render a WRSN more practical and highly adaptable to growth in the real world. Most charging algorithms require a priori [...] Read more.

When extending the life of Wireless Rechargeable Sensor Networks (WRSN), one challenge is charging networks as they grow larger. Overcoming this limitation will render a WRSN more practical and highly adaptable to growth in the real world. Most charging algorithms require a priori full knowledge of sensor nodes’ power levels in order to determine the nodes that require charging. In this work, we present a probabilistic algorithm that extends the life of scalable WRSN without a priori power knowledge and without full network exploration. We develop a probability bound on the power level of the sensor nodes and utilize this bound to make decisions while exploring a WRSN. We verify the algorithm by simulating a wireless power transfer unmanned aerial vehicle, and charging a WRSN to extend its life. Our results show that, without knowledge, our proposed algorithm extends the life of a WRSN on average 90% of what an optimal full knowledge algorithm can achieve. This means that the charging robot does not need to explore the whole network, which enables the scaling of WRSN. We analyze the impact of network parameters on our algorithm and show that it is insensitive to a large range of parameter values. Full article

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

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13 pages, 3982 KiB

Open AccessArticle

Vibration Measurement Method of a String in Transversal Motion by Using a PSD

by Che-Hua Yang

and Tai-Chieh Wu^*

Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 10608, Taiwan

Sensors 2017, 17(7), 1643; https://doi.org/10.3390/s17071643 - 17 Jul 2017

Cited by 8 | Viewed by 6285

Abstract

A position sensitive detector (PSD) is frequently used for the measurement of a one-dimensional position along a line or a two-dimensional position on a plane, but is more often used for measuring static or quasi-static positions. Along with its quick response when measuring [...] Read more.

A position sensitive detector (PSD) is frequently used for the measurement of a one-dimensional position along a line or a two-dimensional position on a plane, but is more often used for measuring static or quasi-static positions. Along with its quick response when measuring short time-spans in the micro-second realm, a PSD is also capable of detecting the dynamic positions of moving objects. In this paper, theoretical modeling and experiments are conducted to explore the frequency characteristics of a vibrating string while moving transversely across a one-dimensional PSD. The theoretical predictions are supported by the experiments. When the string vibrates at its natural frequency while moving transversely, the PSD will detect two frequencies near this natural frequency; one frequency is higher than the natural frequency and the other is lower. Deviations in these two frequencies, which differ from the string’s natural frequency, increase while the speed of motion increases. Full article

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

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28 pages, 9267 KiB

Open AccessArticle

Minding the Cyber-Physical Gap: Model-Based Analysis and Mitigation of Systemic Perception-Induced Failure

by Yaniv Mordecai^1,2,*

and Dov Dori^3,4

¹ Researcher, William Davidson Faculty of Industrial Engineering and Management, Technion—Israel Institute of Technology, Haifa 32000, Israel

² Senior Systems Architect, Motorola Solutions Israel, Airport City 70099, Israel

³ Harry Lebensfeld Chair of Industrial Engineering, William Davidson Faculty of Industrial Engineering and Management, Technion—Israel Institute of Technology, Haifa 32000, Israel

⁴ Visiting Professor, Massachusetts Institute of Technology, Cambridge, MA 02142, USA

Sensors 2017, 17(7), 1644; https://doi.org/10.3390/s17071644 - 17 Jul 2017

Cited by 14 | Viewed by 6006

Abstract

The cyber-physical gap (CPG) is the difference between the ‘real’ state of the world and the way the system perceives it. This discrepancy often stems from the limitations of sensing and data collection technologies and capabilities, and is inevitable at some degree in [...] Read more.

The cyber-physical gap (CPG) is the difference between the ‘real’ state of the world and the way the system perceives it. This discrepancy often stems from the limitations of sensing and data collection technologies and capabilities, and is inevitable at some degree in any cyber-physical system (CPS). Ignoring or misrepresenting such limitations during system modeling, specification, design, and analysis can potentially result in systemic misconceptions, disrupted functionality and performance, system failure, severe damage, and potential detrimental impacts on the system and its environment. We propose CPG-Aware Modeling & Engineering (CPGAME), a conceptual model-based approach to capturing, explaining, and mitigating the CPG. CPGAME enhances the systems engineer’s ability to cope with CPGs, mitigate them by design, and prevent erroneous decisions and actions. We demonstrate CPGAME by applying it for modeling and analysis of the 1979 Three Miles Island 2 nuclear accident, and show how its meltdown could be mitigated. We use ISO-19450:2015—Object Process Methodology as our conceptual modeling framework. Full article

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

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21 pages, 14823 KiB

Open AccessArticle

Implementation of an IMU Aided Image Stacking Algorithm in a Digital Camera for Unmanned Aerial Vehicles

by Ahmad Audi^1,*, Marc Pierrot-Deseilligny², Christophe Meynard¹ and Christian Thom¹

¹ Université Paris-Est, IGN, LaSTIG, LOEMI, 73 Avenue de Paris, 94160 Saint-Mandé, France

² Université Paris-Est, IGN, LaSTIG, LOEMI, ENSG, 6-8 Avenue Blaise Pascal, 77420 Champs-sur-Marne, France

Sensors 2017, 17(7), 1646; https://doi.org/10.3390/s17071646 - 18 Jul 2017

Cited by 10 | Viewed by 7373

Abstract

Images acquired with a long exposure time using a camera embedded on UAVs (Unmanned Aerial Vehicles) exhibit motion blur due to the erratic movements of the UAV. The aim of the present work is to be able to acquire several images with a [...] Read more.

Images acquired with a long exposure time using a camera embedded on UAVs (Unmanned Aerial Vehicles) exhibit motion blur due to the erratic movements of the UAV. The aim of the present work is to be able to acquire several images with a short exposure time and use an image processing algorithm to produce a stacked image with an equivalent long exposure time. Our method is based on the feature point image registration technique. The algorithm is implemented on the light-weight IGN (Institut national de l’information géographique) camera, which has an IMU (Inertial Measurement Unit) sensor and an SoC (System on Chip)/FPGA (Field-Programmable Gate Array). To obtain the correct parameters for the resampling of the images, the proposed method accurately estimates the geometrical transformation between the first and the N-th images. Feature points are detected in the first image using the FAST (Features from Accelerated Segment Test) detector, then homologous points on other images are obtained by template matching using an initial position benefiting greatly from the presence of the IMU sensor. The SoC/FPGA in the camera is used to speed up some parts of the algorithm in order to achieve real-time performance as our ultimate objective is to exclusively write the resulting image to save bandwidth on the storage device. The paper includes a detailed description of the implemented algorithm, resource usage summary, resulting processing time, resulting images and block diagrams of the described architecture. The resulting stacked image obtained for real surveys does not seem visually impaired. An interesting by-product of this algorithm is the 3D rotation estimated by a photogrammetric method between poses, which can be used to recalibrate in real time the gyrometers of the IMU. Timing results demonstrate that the image resampling part of this algorithm is the most demanding processing task and should also be accelerated in the FPGA in future work. Full article

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

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12 pages, 939 KiB

Open AccessArticle

Flavonoid and Antioxidant Capacity of Propolis Prediction Using Near Infrared Spectroscopy

by Eddy Betances-Salcedo^1,†

, Isabel Revilla^2,†

, Ana M. Vivar-Quintana^2,†

and M. Inmaculada González-Martín^1,*,†

¹ Department of Analytical and Food Chemistry, Faculty of Chemistry, University of Salamanca, Plaza de la Merced, 37008 Salamanca, Spain

² Food Technology, University of Salamanca, E.P.S. de Zamora, AvenidaRequejo 33, 49022 Zamora, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1647; https://doi.org/10.3390/s17071647 - 18 Jul 2017

Cited by 34 | Viewed by 5863

Abstract

The use of propolis as a dietary supplement or as an ingredient in different food products is increasing, due to its antioxidant and bactericidal properties. These nutritional properties directly depend on its phenolic composition. For this reason, this study analysed the total contents [...] Read more.

The use of propolis as a dietary supplement or as an ingredient in different food products is increasing, due to its antioxidant and bactericidal properties. These nutritional properties directly depend on its phenolic composition. For this reason, this study analysed the total contents of flavones and flavonols, flavanones and dihydroflavonols, and the antioxidant capacity by using the methods of ABTS and linoleic acid/β-carotene in 99 samples of propolis from Spain and Chile. A rapid method was developed for quantifying these parameters in raw propolis using near infrared (NIR) spectroscopy with a remote reflectance fibre-optic probe applied directly to the ground-up sample. The models developed allow for the determination of the total flavones and flavonols (0–183 mg quercetin/g propolis and 0–72 mg rutin/g propolis), of the total flavanones and dihydroflavonols (9–109 mg pinocembrin/g propolis extract), and of its antioxidant capacity by the ABTS method based on the reduction of the 2.2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation(0–3212.6 nmol Trolox/mg of propolis) and of linoleic acid/β-carotene (22–86% inhibition). The NIR spectroscopy models were applied in external validation to different samples of the calibration group, which led to the conclusion that the methods developed provide significantly identical data to the initial chemical data of reference. Full article

(This article belongs to the Special Issue Infrared Detectors)

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14 pages, 2555 KiB

Open AccessArticle

Hydrostatic Pressure and Temperature Measurements Using an In-Line Mach-Zehnder Interferometer Based on a Two-Mode Highly Birefringent Microstructured Fiber

by Gabriela Statkiewicz-Barabach^1,*, Jacek Olszewski¹, Pawel Mergo² and Waclaw. Urbanczyk¹

¹ Department of Optics and Photonics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland

² Laboratory of Optical Fiber Technology, Maria Curie-Sklodowska University, 20-031 Lublin, Poland

Sensors 2017, 17(7), 1648; https://doi.org/10.3390/s17071648 - 18 Jul 2017

Cited by 10 | Viewed by 3896

Abstract

We present a comprehensive study of an in-line Mach-Zehnder intermodal interferometer fabricated in a boron-doped two-mode highly birefringent microstructured fiber. We observed different interference signals at the output of the interferometer, related to the intermodal interference of the fundamental and the first order [...] Read more.

We present a comprehensive study of an in-line Mach-Zehnder intermodal interferometer fabricated in a boron-doped two-mode highly birefringent microstructured fiber. We observed different interference signals at the output of the interferometer, related to the intermodal interference of the fundamental and the first order modes of the orthogonal polarizations and a beating of the polarimetric signal related to the difference in the group modal birefringence between the fundamental and the first order modes, respectively. The proposed interferometer was tested for measurements of hydrostatic pressure and temperature for different alignments of the input polarizer with no analyzer at the output. The sensitivities to hydrostatic pressure of the intermodal interference signals for x- and y-polarizations had an opposite sign and were equal to 0.229 nm/MPa and −0.179 nm/MPa, respectively, while the temperature sensitivities for both polarizations were similar and equal 0.020 nm/°C and 0.019 nm/°C. In the case of pressure, for the simultaneous excitation of both polarization modes, we observed a displacement of intermodal fringes with a sensitivity depending on the azimuth of the input polarization state, as well as on the displacement of their envelope with a sensitivity of 2.14 nm/MPa, accompanied by a change in the fringes visibility. Such properties of the proposed interferometer allow for convenient adjustments to the pressure sensitivity of the intermodal fringes and possible applications for the simultaneous interrogation of temperature and pressure. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 6608 KiB

Open AccessArticle

Preliminary Study of UAS Equipped with Thermal Camera for Volcanic Geothermal Monitoring in Taiwan

by Shih-Hong Chio^1,* and Cheng-Horng Lin²

¹ Department of Land Economics, National Chengchi University, No. 64, Sec. 2, ZhiNan Rd., Wenshan District, Taipei 11605, Taiwan

² Institute of Earth Sciences, Academia Sinica, No. 128, Sec. 2, Academia Road, Nangang, Taipei 11529, Taiwan

Sensors 2017, 17(7), 1649; https://doi.org/10.3390/s17071649 - 18 Jul 2017

Cited by 21 | Viewed by 6446

Abstract

Thermal infrared cameras sense the temperature information of sensed scenes. With the development of UASs (Unmanned Aircraft Systems), thermal infrared cameras can now be carried on a quadcopter UAV (Unmanned Aircraft Vehicle) to appropriately collect high-resolution thermal images for volcanic geothermal monitoring in [...] Read more.

Thermal infrared cameras sense the temperature information of sensed scenes. With the development of UASs (Unmanned Aircraft Systems), thermal infrared cameras can now be carried on a quadcopter UAV (Unmanned Aircraft Vehicle) to appropriately collect high-resolution thermal images for volcanic geothermal monitoring in a local area. Therefore, the quadcopter UAS used to acquire thermal images for volcanic geothermal monitoring has been developed in Taiwan as part of this study to overcome the difficult terrain with highly variable topography and extreme environmental conditions. An XM6 thermal infrared camera was employed in this thermal image collection system. The Trimble BD970 GNSS (Global Navigation Satellite System) OEM (Original Equipment Manufacturer) board was also carried on the quadcopter UAV to gather dual-frequency GNSS observations in order to determine the flying trajectory data by using the Post-Processed Kinematic (PPK) technique; this will be used to establish the position and orientation of collected thermal images with less ground control points (GCPs). The digital surface model (DSM) and thermal orthoimages were then produced from collected thermal images. Tests conducted in the Hsiaoyukeng area of Taiwan’s Yangmingshan National Park show that the difference between produced DSM and airborne LIDAR (Light Detection and Ranging) data are about 37% between −1 m and 1 m, and 66% between −2 m and 2 m in the area surrounded by GCPs. As the accuracy of thermal orthoimages is about 1.78 m, it is deemed sufficient for volcanic geothermal monitoring. In addition, the thermal orthoimages show some phenomena not only more globally than do the traditional methods for volcanic geothermal monitoring, but they also show that the developed system can be further employed in Taiwan in the future. Full article

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

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20 pages, 3360 KiB

Open AccessArticle

Electromagnetic Differential Measuring Method: Application in Microstrip Sensors Developing

by Francisco Javier Ferrández-Pastor^*

, Juan Manuel García-Chamizo and Mario Nieto-Hidalgo

Department of Computer Technology, University of Alicante, P.O. Box 99, E-03080 Alicante, Spain

Sensors 2017, 17(7), 1650; https://doi.org/10.3390/s17071650 - 18 Jul 2017

Cited by 62 | Viewed by 9087

Abstract

Electromagnetic radiation is energy that interacts with matter. The interaction process is of great importance to the sensing applications that characterize material media. Parameters like constant dielectric represent matter characteristics and they are identified using emission, interaction and reception of electromagnetic radiation in [...] Read more.

Electromagnetic radiation is energy that interacts with matter. The interaction process is of great importance to the sensing applications that characterize material media. Parameters like constant dielectric represent matter characteristics and they are identified using emission, interaction and reception of electromagnetic radiation in adapted environmental conditions. How the electromagnetic wave responds when it interacts with the material media depends on the range of frequency used and the medium parameters. Different disciplines use this interaction and provides non-intrusive applications with clear benefits, remote sensing, earth sciences (geology, atmosphere, hydrosphere), biological or medical disciplines use this interaction and provides non-intrusive applications with clear benefits. Electromagnetic waves are transmitted and analyzed in the receiver to determine the interaction produced. In this work a method based in differential measurement technique is proposed as a novel way of detecting and characterizing electromagnetic matter characteristics using sensors based on a microstrip patch. The experimental results, based on simulations, show that it is possible to obtain benefits from the behavior of the wave-medium interaction using differential measurement on reception of electromagnetic waves at different frequencies or environmental conditions. Differential method introduce advantages in measure processes and promote new sensors development. A new microstrip sensor that uses differential time measures is proposed to show the possibilities of this method. Full article

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

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11 pages, 1962 KiB

Open AccessArticle

Detection of Guanine and Adenine Using an Aminated Reduced Graphene Oxide Functional Membrane-Modified Glassy Carbon Electrode

by Di Li^1,†, Xiao-Lu Yang^1,†, Bao-Lin Xiao^1,†

, Fang-Yong Geng^1,†, Jun Hong^1,2,*,†

, Nader Sheibani³ and Ali Akbar Moosavi-Movahedi^4,*

¹ School of Life Sciences, Henan University, JinMing Road, Kaifeng 475000, China

² Institute of Biotechnology, Henan University, Kaifeng 475000, China

³ Department of Ophthalmology and Visual Sciences and Biomedical Engineering, University of Wisconsin School of Medicine and Public Health, Madison, WI 53726, USA

⁴ Institute of Biochemistry and Biophysics, University of Tehran, Enquelab Avenue, Tehran 13145-1384, Iran

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1652; https://doi.org/10.3390/s17071652 - 18 Jul 2017

Cited by 17 | Viewed by 7309

Abstract

A new electrochemical sensor based on a Nafion, aminated reduced graphene oxide and chitosan functional membrane-modified glassy carbon electrode was proposed for the simultaneous detection of adenine and guanine. Fourier transform-infrared spectrometry (FTIR), transmission electron microscopy (TEM), and electrochemical methods were utilized for [...] Read more.

A new electrochemical sensor based on a Nafion, aminated reduced graphene oxide and chitosan functional membrane-modified glassy carbon electrode was proposed for the simultaneous detection of adenine and guanine. Fourier transform-infrared spectrometry (FTIR), transmission electron microscopy (TEM), and electrochemical methods were utilized for the additional characterization of the membrane materials. The prepared electrode was utilized for the detection of guanine (G) and adenine (A). The anodic peak currents to G and A were linear in the concentrations ranging from 0.1 to 120 μM and 0.2 to 110 μM, respectively. The detection limits were found to be 0.1 μM and 0.2 μM, respectively. Moreover, the modified electrode could also be used to determine G and A in calf thymus DNA. Full article

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

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25 pages, 3744 KiB

Open AccessArticle

Practical Use of Metal Oxide Semiconductor Gas Sensors for Measuring Nitrogen Dioxide and Ozone in Urban Environments

by Philip J. D. Peterson¹, Amrita Aujla¹, Kirsty H. Grant¹

, Alex G. Brundle¹, Martin R. Thompson¹, Josh Vande Hey¹ and Roland J. Leigh^1,2,*

¹ Department of Physics and Astronomy, University of Leicester, Leicester LE17RH, UK

² Earthsense Systems Ltd., Leicester LE45NU, UK

Sensors 2017, 17(7), 1653; https://doi.org/10.3390/s17071653 - 19 Jul 2017

Cited by 112 | Viewed by 17250

Abstract

The potential of inexpensive Metal Oxide Semiconductor (MOS) gas sensors to be used for urban air quality monitoring has been the topic of increasing interest in the last decade. This paper discusses some of the lessons of three years of experience working with [...] Read more.

The potential of inexpensive Metal Oxide Semiconductor (MOS) gas sensors to be used for urban air quality monitoring has been the topic of increasing interest in the last decade. This paper discusses some of the lessons of three years of experience working with such sensors on a novel instrument platform (Small Open General purpose Sensor (SOGS)) in the measurement of atmospheric nitrogen dioxide and ozone concentrations. Analytic methods for increasing long-term accuracy of measurements are discussed, which permit nitrogen dioxide measurements with 95% confidence intervals of 20.0

μ g m^{- 3}

and ozone precision of 26.8

μ g m^{- 3}

, for measurements over a period one month away from calibration, averaged over 18 months of such calibrations. Beyond four months from calibration, sensor drift becomes significant, and accuracy is significantly reduced. Successful calibration schemes are discussed with the use of controlled artificial atmospheres complementing deployment on a reference weather station exposed to the elements. Manufacturing variation in the attributes of individual sensors are examined, an experiment possible due to the instrument being equipped with pairs of sensors of the same kind. Good repeatability (better than 0.7 correlation) between individual sensor elements is shown. The results from sensors that used fans to push air past an internal sensor element are compared with mounting the sensors on the outside of the enclosure, the latter design increasing effective integration time to more than a day. Finally, possible paths forward are suggested for improving the reliability of this promising sensor technology for measuring pollution in an urban environment. Full article

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

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11 pages, 6159 KiB

Open AccessArticle

Enhanced Strain Measurement Range of an FBG Sensor Embedded in Seven-Wire Steel Strands

by Jae-Min Kim¹

, Chul-Min Kim², Song-Yi Choi³ and Bang Yeon Lee^4,*

¹ Department of Marine and Civil Engineering, Chonnam National University, Yeosu 59626, Korea

² Department of Civil and Environmental Engineering, Graduate School, Chonnam National University, Yeosu 59626, Korea

³ INNOSE Tech., Incheon 21990, Korea

⁴ School of Architecture, Chonnam National University, Gwangju 61186, Korea

Sensors 2017, 17(7), 1654; https://doi.org/10.3390/s17071654 - 18 Jul 2017

Cited by 39 | Viewed by 8746

Abstract

FBG sensors offer many advantages, such as a lack of sensitivity to electromagnetic waves, small size, high durability, and high sensitivity. However, their maximum strain measurement range is lower than the yield strain range (about 1.0%) of steel strands when embedded in steel [...] Read more.

FBG sensors offer many advantages, such as a lack of sensitivity to electromagnetic waves, small size, high durability, and high sensitivity. However, their maximum strain measurement range is lower than the yield strain range (about 1.0%) of steel strands when embedded in steel strands. This study proposes a new FBG sensing technique in which an FBG sensor is recoated with polyimide and protected by a polyimide tube in an effort to enhance the maximum strain measurement range of FBG sensors embedded in strands. The validation test results showed that the proposed FBG sensing technique has a maximum strain measurement range of 1.73% on average, which is 1.73 times higher than the yield strain of the strands. It was confirmed that recoating the FBG sensor with polyimide and protecting the FBG sensor using a polyimide tube could effectively enhance the maximum strain measurement range of FBG sensors embedded in strands. Full article

(This article belongs to the Special Issue Integrated Photonic Technologies for Sensing Applications)

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9 pages, 1605 KiB

Open AccessArticle

Multifunctional Water Sensors for pH, ORP, and Conductivity Using Only Microfabricated Platinum Electrodes

by Wen-Chi Lin¹, Klaus Brondum², Charles W. Monroe³ and Mark A. Burns^1,4,*

¹ Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA

² Masco Corporation, Taylor, MI 48180, USA

³ Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK

⁴ Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA

Sensors 2017, 17(7), 1655; https://doi.org/10.3390/s17071655 - 19 Jul 2017

Cited by 25 | Viewed by 9464

Abstract

Monitoring of the pH, oxidation-reduction-potential (ORP), and conductivity of aqueous samples is typically performed using multiple sensors. To minimize the size and cost of these sensors for practical applications, we have investigated the use of a single sensor constructed with only bare platinum [...] Read more.

Monitoring of the pH, oxidation-reduction-potential (ORP), and conductivity of aqueous samples is typically performed using multiple sensors. To minimize the size and cost of these sensors for practical applications, we have investigated the use of a single sensor constructed with only bare platinum electrodes deposited on a glass substrate. The sensor can measure pH from 4 to 10 while simultaneously measuring ORP from 150 to 800 mV. The device can also measure conductivity up to 8000 μS/cm in the range of 10 °C to 50 °C, and all these measurements can be made even if the water samples contain common ions found in residential water. The sensor is inexpensive (i.e., ~$0.10/unit) and has a sensing area below 1 mm², suggesting that the unit is cost-efficient, robust, and widely applicable, including in microfluidic systems. Full article

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

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17 pages, 2965 KiB

Open AccessArticle

Mining Feature of Data Fusion in the Classification of Beer Flavor Information Using E-Tongue and E-Nose

by Hong Men, Yan Shi, Songlin Fu, Yanan Jiao

, Yu Qiao and Jingjing Liu^*

College of Automation Engineering, Northeast Electric Power University, Jilin 132012, China

Sensors 2017, 17(7), 1656; https://doi.org/10.3390/s17071656 - 19 Jul 2017

Cited by 61 | Viewed by 7474

Abstract

Multi-sensor data fusion can provide more comprehensive and more accurate analysis results. However, it also brings some redundant information, which is an important issue with respect to finding a feature-mining method for intuitive and efficient analysis. This paper demonstrates a feature-mining method based [...] Read more.

Multi-sensor data fusion can provide more comprehensive and more accurate analysis results. However, it also brings some redundant information, which is an important issue with respect to finding a feature-mining method for intuitive and efficient analysis. This paper demonstrates a feature-mining method based on variable accumulation to find the best expression form and variables’ behavior affecting beer flavor. First, e-tongue and e-nose were used to gather the taste and olfactory information of beer, respectively. Second, principal component analysis (PCA), genetic algorithm-partial least squares (GA-PLS), and variable importance of projection (VIP) scores were applied to select feature variables of the original fusion set. Finally, the classification models based on support vector machine (SVM), random forests (RF), and extreme learning machine (ELM) were established to evaluate the efficiency of the feature-mining method. The result shows that the feature-mining method based on variable accumulation obtains the main feature affecting beer flavor information, and the best classification performance for the SVM, RF, and ELM models with 96.67%, 94.44%, and 98.33% prediction accuracy, respectively. Full article

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

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17 pages, 5102 KiB

Open AccessArticle

Study on Finite Element Model Updating in Highway Bridge Static Loading Test Using Spatially-Distributed Optical Fiber Sensors

by Bitao Wu^*, Huaxi Lu, Bo Chen and Zhicheng Gao

School of Civil Engineering & Architecture, East China Jiao Tong University, Nanchang 330013, China

Sensors 2017, 17(7), 1657; https://doi.org/10.3390/s17071657 - 19 Jul 2017

Cited by 33 | Viewed by 6292

Abstract

A finite model updating method that combines dynamic-static long-gauge strain responses is proposed for highway bridge static loading tests. For this method, the objective function consisting of static long-gauge stains and the first order modal macro-strain parameter (frequency) is established, wherein the local [...] Read more.

A finite model updating method that combines dynamic-static long-gauge strain responses is proposed for highway bridge static loading tests. For this method, the objective function consisting of static long-gauge stains and the first order modal macro-strain parameter (frequency) is established, wherein the local bending stiffness, density and boundary conditions of the structures are selected as the design variables. The relationship between the macro-strain and local element stiffness was studied first. It is revealed that the macro-strain is inversely proportional to the local stiffness covered by the long-gauge strain sensor. This corresponding relation is important for the modification of the local stiffness based on the macro-strain. The local and global parameters can be simultaneously updated. Then, a series of numerical simulation and experiments were conducted to verify the effectiveness of the proposed method. The results show that the static deformation, macro-strain and macro-strain modal can be predicted well by using the proposed updating model. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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20 pages, 7412 KiB

Open AccessArticle

Surface Estimation for Microwave Imaging

by Douglas Kurrant^*, Jeremie Bourqui and Elise Fear

Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(7), 1658; https://doi.org/10.3390/s17071658 - 19 Jul 2017

Cited by 29 | Viewed by 5387

Abstract

Biomedical imaging and sensing applications in many scenarios demand accurate surface estimation from a sparse set of noisy measurements. These measurements may arise from a variety of sensing modalities, including laser or electromagnetic samples of an object’s surface. We describe a state-of-the-art microwave [...] Read more.

Biomedical imaging and sensing applications in many scenarios demand accurate surface estimation from a sparse set of noisy measurements. These measurements may arise from a variety of sensing modalities, including laser or electromagnetic samples of an object’s surface. We describe a state-of-the-art microwave imaging prototype that has sensors to acquire both microwave and laser measurements. The approach developed to translate sparse samples of the breast surface into an accurate estimate of the region of interest is detailed. To evaluate the efficacy of the method, laser and electromagnetic samples are acquired by sensors from three realistic breast models with varying sizes and shapes. A set of metrics is developed to assist with the investigation and demonstrate that the algorithm is able to accurately estimate the shape of a realistic breast phantom when only a sparse set of data are available. Moreover, the algorithm is robust to the presence of measurement noise, and is effective when applied to measurement scans of patients acquired with the prototype. Full article

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

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23 pages, 2287 KiB

Open AccessArticle

Radial Distance Estimation with Tapered Whisker Sensors

by Sejoon Ahn and DaeEun Kim^*

Biological Cybernetics Lab, School of Electrical and Electronic Engineering, Yonsei University, Shinchon, Seoul 120-749, Korea

Sensors 2017, 17(7), 1659; https://doi.org/10.3390/s17071659 - 19 Jul 2017

Cited by 8 | Viewed by 5513

Abstract

Rats use their whiskers as tactile sensors to sense their environment. Active whisking, moving whiskers back and forth continuously, is one of prominent features observed in rodents. They can discriminate different textures or extract features of a nearby object such as size, shape [...] Read more.

Rats use their whiskers as tactile sensors to sense their environment. Active whisking, moving whiskers back and forth continuously, is one of prominent features observed in rodents. They can discriminate different textures or extract features of a nearby object such as size, shape and distance through active whisking. There have been studies to localize objects with artificial whiskers inspired by rat whiskers. The linear whisker model based on beam theory has been used to estimate the radial distance, that is, the distance between the base of the whisker and a target object. In this paper, we investigate deflection angle measurements instead of forces or moments, based on a linear tapered whisker model to see the role of tapered whiskers found in real animals. We analyze how accurately this model estimates the radial distance, and quantify the estimation errors and noise sensitivity. We also compare the linear model simulation and nonlinear numerical solutions. It is shown that the radial distance can be estimated using deflection angles at two different positions on the tapered whisker. We argue that the tapered whisker has an advantage of estimating the radial distance better, as compared to an untapered whisker, and active sensing allows that estimation without the whisker’s material property and thickness or the moment at base. In addition, we investigate the potential of passive sensing for tactile localization. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 1569 KiB

Open AccessArticle

A Q-Learning-Based Delay-Aware Routing Algorithm to Extend the Lifetime of Underwater Sensor Networks

by Zhigang Jin¹

, Yingying Ma¹, Yishan Su^1,*, Shuo Li^1,* and Xiaomei Fu²

¹ School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China

² School of Marine Science and Technology, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(7), 1660; https://doi.org/10.3390/s17071660 - 19 Jul 2017

Cited by 71 | Viewed by 5178

Abstract

Underwater sensor networks (UWSNs) have become a hot research topic because of their various aquatic applications. As the underwater sensor nodes are powered by built-in batteries which are difficult to replace, extending the network lifetime is a most urgent need. Due to the [...] Read more.

Underwater sensor networks (UWSNs) have become a hot research topic because of their various aquatic applications. As the underwater sensor nodes are powered by built-in batteries which are difficult to replace, extending the network lifetime is a most urgent need. Due to the low and variable transmission speed of sound, the design of reliable routing algorithms for UWSNs is challenging. In this paper, we propose a Q-learning based delay-aware routing (QDAR) algorithm to extend the lifetime of underwater sensor networks. In QDAR, a data collection phase is designed to adapt to the dynamic environment. With the application of the Q-learning technique, QDAR can determine a global optimal next hop rather than a greedy one. We define an action-utility function in which residual energy and propagation delay are both considered for adequate routing decisions. Thus, the QDAR algorithm can extend the network lifetime by uniformly distributing the residual energy and provide lower end-to-end delay. The simulation results show that our protocol can yield nearly the same network lifetime, and can reduce the end-to-end delay by 20–25% compared with a classic lifetime-extended routing protocol (QELAR). Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 1828 KiB

Open AccessArticle

Amperometric Microsensors Monitoring Glutamate-Evoked In Situ Responses of Nitric Oxide and Carbon Monoxide from Live Human Neuroblastoma Cells

by Yejin Ha^1,†, Chaejeong Heo^2,†, Juhyun Woo^2,3, Hyunwoo Ryu^2,3, Youngmi Lee^1,* and And Minah Suh^2,3,4,*

¹ Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea

² Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon 16419, Korea

³ Department of Biomedical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Korea

⁴ Samsung Advanced Institute of Health Science and Technology (SAIHST), Sungkyunkwan University (SKKU), Suwon 16419, Korea

^† Authors are equally contributed to this work.

Sensors 2017, 17(7), 1661; https://doi.org/10.3390/s17071661 - 19 Jul 2017

Cited by 2 | Viewed by 4809

Abstract

In the brain, nitric oxide (NO) and carbon monoxide (CO) are important signaling gases which have multifaceted roles, such as neurotransmitters, neuromodulators, and vasodilators. Even though it is difficult to measure NO and CO in a living system due to their high diffusibility [...] Read more.

In the brain, nitric oxide (NO) and carbon monoxide (CO) are important signaling gases which have multifaceted roles, such as neurotransmitters, neuromodulators, and vasodilators. Even though it is difficult to measure NO and CO in a living system due to their high diffusibility and extremely low release levels, electrochemical sensors are promising tools to measure in vivo and in vitro NO and CO gases. In this paper, using amperometric dual and septuple NO/CO microsensors, real-time NO and CO changes evoked by glutamate were monitored simultaneously for human neuroblastoma (SH-SY5Y) cells. In cultures, the cells were differentiated and matured into functional neurons by retinoic acid and brain-derived neurotrophic factor. When glutamate was administrated to the cells, both NO and CO increases and subsequent decreases returning to the basal levels were observed with a dual NO/CO microsensor. In order to facilitate sensor’s measurement, a flower-type septuple NO/CO microsensor was newly developed and confirmed in terms of the sensitivity and selectivity. The septuple microsensor was employed for the measurements of NO and CO changes as a function of distances from the position of glutamate injection. Our sensor measurements revealed that only functionally differentiated cells responded to glutamate and released NO and CO. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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14 pages, 4897 KiB

Open AccessArticle

Selective Detection of Target Volatile Organic Compounds in Contaminated Humid Air Using a Sensor Array with Principal Component Analysis

by Toshio Itoh Takafumi Akamatsu^*, Akihiro Tsuruta and Woosuck Shin

National Institute of Advanced Industrial Science and Technology (AIST), Shimo-shidami, Moriyama-ku, Nagoya 463-8560, Japan

Sensors 2017, 17(7), 1662; https://doi.org/10.3390/s17071662 - 19 Jul 2017

Cited by 46 | Viewed by 7669

Abstract

We investigated selective detection of the target volatile organic compounds (VOCs) nonanal, n-decane, and acetoin for lung cancer-related VOCs, and acetone and methyl i-butyl ketone for diabetes-related VOCs, in humid air with simulated VOC contamination (total concentration: 300 μg/m³). [...] Read more.

We investigated selective detection of the target volatile organic compounds (VOCs) nonanal, n-decane, and acetoin for lung cancer-related VOCs, and acetone and methyl i-butyl ketone for diabetes-related VOCs, in humid air with simulated VOC contamination (total concentration: 300 μg/m³). We used six “grain boundary-response type” sensors, including four commercially available sensors (TGS 2600, 2610, 2610, and 2620) and two Pt, Pd, and Au-loaded SnO₂ sensors (Pt, Pd, Au/SnO₂), and two “bulk-response type” sensors, including Zr-doped CeO₂ (CeZr10), i.e., eight sensors in total. We then analyzed their sensor signals using principal component analysis (PCA). Although the six “grain boundary-response type” sensors were found to be insufficient for selective detection of the target gases in humid air, the addition of two “bulk-response type” sensors improved the selectivity, even with simulated VOC contamination. To further improve the discrimination, we selected appropriate sensors from the eight sensors based on the PCA results. The selectivity to each target gas was maintained and was not affected by contamination. Full article

(This article belongs to the Section Chemical Sensors)

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12 pages, 4308 KiB

Open AccessArticle

Thermal Anemometry Grid Sensor

by Martin Arlit^1,*, Eckhard Schleicher² and Uwe Hampel¹

¹ Technische Universitaet Dresden, AREVA Endowed Chair of Imaging Techniques in Energy and Process Engineering, 01062 Dresden, Germany

² Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, P.O. Box 510119, 01314 Dresden, Germany

Sensors 2017, 17(7), 1663; https://doi.org/10.3390/s17071663 - 19 Jul 2017

Cited by 15 | Viewed by 5501

Abstract

A novel thermal anemometry grid sensor was developed for the simultaneous measurement of cross-sectional temperature and axial velocity distribution in a fluid flow. The sensor consists of a set of platinum resistors arranged in a regular grid. Each platinum resistor allows the simultaneous [...] Read more.

A novel thermal anemometry grid sensor was developed for the simultaneous measurement of cross-sectional temperature and axial velocity distribution in a fluid flow. The sensor consists of a set of platinum resistors arranged in a regular grid. Each platinum resistor allows the simultaneous measurement of fluid temperature via electrical resistance and flow velocity via constant voltage thermal anemometry. Cross-sectional measurement was enabled by applying a special multiplexing-excitation scheme. In this paper, we present the design and characterization of a prototypical sensor for measurements in a range of very low velocities. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 6371 KiB

Open AccessArticle

Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

by Shilei Liu¹

, Yanye Yang¹, Zhengyang Ni¹, Xiasheng Guo^1,*, Linjiao Luo¹, Juan Tu¹, Dong Zhang^1,2,*

and And Jie Zhang³

¹ Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Centre of Advanced Microstructure, Nanjing University, Nanjing 210093, China

² The State Key Laboratory of Acoustics, Chinese Academy of Science, Beijing 10080, China

³ Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, UK

Sensors 2017, 17(7), 1664; https://doi.org/10.3390/s17071664 - 19 Jul 2017

Cited by 35 | Viewed by 8376

Abstract

Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF) and acoustic streaming (AS). In this paper, force conditions on [...] Read more.

Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF) and acoustic streaming (AS). In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL^® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV). Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning. Full article

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

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15 pages, 2170 KiB

Open AccessArticle

Dynamic Hierarchical Energy-Efficient Method Based on Combinatorial Optimization for Wireless Sensor Networks

by Yuchao Chang^1,2

, Hongying Tang¹, Yongbo Cheng^1,2, Qin Zhao^1,2 and Baoqing Li andXiaobing Yuan^1,1,*

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

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

Sensors 2017, 17(7), 1665; https://doi.org/10.3390/s17071665 - 19 Jul 2017

Cited by 32 | Viewed by 4797

Abstract

Routing protocols based on topology control are significantly important for improving network longevity in wireless sensor networks (WSNs). Traditionally, some WSN routing protocols distribute uneven network traffic load to sensor nodes, which is not optimal for improving network longevity. Differently to conventional WSN [...] Read more.

Routing protocols based on topology control are significantly important for improving network longevity in wireless sensor networks (WSNs). Traditionally, some WSN routing protocols distribute uneven network traffic load to sensor nodes, which is not optimal for improving network longevity. Differently to conventional WSN routing protocols, we propose a dynamic hierarchical protocol based on combinatorial optimization (DHCO) to balance energy consumption of sensor nodes and to improve WSN longevity. For each sensor node, the DHCO algorithm obtains the optimal route by establishing a feasible routing set instead of selecting the cluster head or the next hop node. The process of obtaining the optimal route can be formulated as a combinatorial optimization problem. Specifically, the DHCO algorithm is carried out by the following procedures. It employs a hierarchy-based connection mechanism to construct a hierarchical network structure in which each sensor node is assigned to a special hierarchical subset; it utilizes the combinatorial optimization theory to establish the feasible routing set for each sensor node, and takes advantage of the maximum–minimum criterion to obtain their optimal routes to the base station. Various results of simulation experiments show effectiveness and superiority of the DHCO algorithm in comparison with state-of-the-art WSN routing algorithms, including low-energy adaptive clustering hierarchy (LEACH), hybrid energy-efficient distributed clustering (HEED), genetic protocol-based self-organizing network clustering (GASONeC), and double cost function-based routing (DCFR) algorithms. Full article

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

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22 pages, 1791 KiB

Open AccessArticle

Dual-Source Linear Energy Prediction (LINE-P) Model in the Context of WSNs

by Faisal Ahmed^1,*, Gert Tamberg^2,*

, Yannick Le Moullec^1,*

and Paul Annus¹

¹ Thomas Johann Seebeck Department of Electronic, Tallinn University of Technology, Tallinn 12616, Estonia

² Department of Cybernetics, Tallinn University of Technology, Tallinn 12616, Estonia

Sensors 2017, 17(7), 1666; https://doi.org/10.3390/s17071666 - 20 Jul 2017

Cited by 7 | Viewed by 4969

Abstract

Energy harvesting technologies such as miniature power solar panels and micro wind turbines are increasingly used to help power wireless sensor network nodes. However, a major drawback of energy harvesting is its varying and intermittent characteristic, which can negatively affect the quality of [...] Read more.

Energy harvesting technologies such as miniature power solar panels and micro wind turbines are increasingly used to help power wireless sensor network nodes. However, a major drawback of energy harvesting is its varying and intermittent characteristic, which can negatively affect the quality of service. This calls for careful design and operation of the nodes, possibly by means of, e.g., dynamic duty cycling and/or dynamic frequency and voltage scaling. In this context, various energy prediction models have been proposed in the literature; however, they are typically compute-intensive or only suitable for a single type of energy source. In this paper, we propose Linear Energy Prediction “LINE-P”, a lightweight, yet relatively accurate model based on approximation and sampling theory; LINE-P is suitable for dual-source energy harvesting. Simulations and comparisons against existing similar models have been conducted with low and medium resolutions (i.e., 60 and 22 min intervals/24 h) for the solar energy source (low variations) and with high resolutions (15 min intervals/24 h) for the wind energy source. The results show that the accuracy of the solar-based and wind-based predictions is up to approximately 98% and 96%, respectively, while requiring a lower complexity and memory than the other models. For the cases where LINE-P’s accuracy is lower than that of other approaches, it still has the advantage of lower computing requirements, making it more suitable for embedded implementation, e.g., in wireless sensor network coordinator nodes or gateways. Full article

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

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15 pages, 4965 KiB

Open AccessArticle

A Novel Physical Sensing Principle for Liquid Characterization Using Paper-Based Hygro-Mechanical Systems (PB-HMS)

by Angel Perez-Cruz^1,2,*, Ion Stiharu¹ and Aurelio Dominguez-Gonzalez²

¹ Department of Mechanical and Industrial Engineering, Concordia University, 1455 De Maisonneuve Blvd, W. Montreal, QC H3G 1M8, Canada

² Facultad de Ingeniería, Universidad Autónoma de Querétaro, Cerro de las Campanas s/n Querétaro, Querétaro 76000, Mexico

Sensors 2017, 17(7), 1667; https://doi.org/10.3390/s17071667 - 20 Jul 2017

Cited by 2 | Viewed by 3691

Abstract

In recent years paper-based microfluidic systems have emerged as versatile tools for developing sensors in different areas. In this work; we report a novel physical sensing principle for the characterization of liquids using a paper-based hygro-mechanical system (PB-HMS). The PB-HMS is formed by [...] Read more.

In recent years paper-based microfluidic systems have emerged as versatile tools for developing sensors in different areas. In this work; we report a novel physical sensing principle for the characterization of liquids using a paper-based hygro-mechanical system (PB-HMS). The PB-HMS is formed by the interaction of liquid droplets and paper-based mini-structures such as cantilever beams. The proposed principle takes advantage of the hygroscopic properties of paper to produce hygro-mechanical motion. The dynamic response of the PB-HMS reveals information about the tested liquid that can be applied to characterize certain properties of liquids. A suggested method to characterize liquids by means of the proposed principle is introduced. The experimental results show the feasibility of such a method. It is expected that the proposed principle may be applied to sense properties of liquids in different applications where both disposability and portability are of extreme importance. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 2488 KiB

Open AccessArticle

Online Denoising Based on the Second-Order Adaptive Statistics Model

by Sheng-Lun Yi^1,2, Xue-Bo Jin^1,2

, Ting-Li Su^1,2,*, Zhen-Yun Tang³, Fa-Fa Wang^1,2, Na Xiang^1,2 and Jian-Lei Kong^1,2

¹ School of Computer Information and Engineering, Beijing Technology and Business University, Beijing 100048, China

² Beijing Key Laboratory of Big Data Technology for Food Safety, Beijing Technology and Business University, Beijing 100048, China

³ The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China

Sensors 2017, 17(7), 1668; https://doi.org/10.3390/s17071668 - 20 Jul 2017

Cited by 13 | Viewed by 5397

Abstract

Online denoising is motivated by real-time applications in the industrial process, where the data must be utilizable soon after it is collected. Since the noise in practical process is usually colored, it is quite a challenge for denoising techniques. In this paper, a [...] Read more.

Online denoising is motivated by real-time applications in the industrial process, where the data must be utilizable soon after it is collected. Since the noise in practical process is usually colored, it is quite a challenge for denoising techniques. In this paper, a novel online denoising method was proposed to achieve the processing of the practical measurement data with colored noise, and the characteristics of the colored noise were considered in the dynamic model via an adaptive parameter. The proposed method consists of two parts within a closed loop: the first one is to estimate the system state based on the second-order adaptive statistics model and the other is to update the adaptive parameter in the model using the Yule–Walker algorithm. Specifically, the state estimation process was implemented via the Kalman filter in a recursive way, and the online purpose was therefore attained. Experimental data in a reinforced concrete structure test was used to verify the effectiveness of the proposed method. Results show the proposed method not only dealt with the signals with colored noise, but also achieved a tradeoff between efficiency and accuracy. Full article

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

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15 pages, 1419 KiB

Open AccessArticle

User Interaction Modeling and Profile Extraction in Interactive Systems: A Groupware Application Case Study

by Cristina Tîrnăucă^*

, Rafael Duque and José L. Montaña

Departamento de Matemáticas, Estadística y Computación, Universidad de Cantabria, 39005 Santander, Spain

Sensors 2017, 17(7), 1669; https://doi.org/10.3390/s17071669 - 20 Jul 2017

Cited by 5 | Viewed by 5572

Abstract

A relevant goal in human–computer interaction is to produce applications that are easy to use and well-adjusted to their users’ needs. To address this problem it is important to know how users interact with the system. This work constitutes a methodological contribution capable [...] Read more.

A relevant goal in human–computer interaction is to produce applications that are easy to use and well-adjusted to their users’ needs. To address this problem it is important to know how users interact with the system. This work constitutes a methodological contribution capable of identifying the context of use in which users perform interactions with a groupware application (synchronous or asynchronous) and provides, using machine learning techniques, generative models of how users behave. Additionally, these models are transformed into a text that describes in natural language the main characteristics of the interaction of the users with the system. Full article

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

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16 pages, 5027 KiB

Open AccessArticle

Crack Detection in Concrete Tunnels Using a Gabor Filter Invariant to Rotation

by Roberto Medina¹, José Llamas¹

, Jaime Gómez-García-Bermejo^2,*

, Eduardo Zalama² and Miguel José Segarra³

¹ CARTIF Foundation, Parque Tecnológico de Boecillo, 47151 Valladolid, Spain

² ITAP-DISA, University of Valladolid, 47002 Valladolid, Spain

³ DRAGADOS S.A., Av. Camino de Santiago 50, 28050 Madrid, Spain

Sensors 2017, 17(7), 1670; https://doi.org/10.3390/s17071670 - 20 Jul 2017

Cited by 81 | Viewed by 10334

Abstract

In this article, a system for the detection of cracks in concrete tunnel surfaces, based on image sensors, is presented. Both data acquisition and processing are covered. Linear cameras and proper lighting are used for data acquisition. The required resolution of the camera [...] Read more.

In this article, a system for the detection of cracks in concrete tunnel surfaces, based on image sensors, is presented. Both data acquisition and processing are covered. Linear cameras and proper lighting are used for data acquisition. The required resolution of the camera sensors and the number of cameras is discussed in terms of the crack size and the tunnel type. Data processing is done by applying a new method called Gabor filter invariant to rotation, allowing the detection of cracks in any direction. The parameter values of this filter are set by using a modified genetic algorithm based on the Differential Evolution optimization method. The detection of the pixels belonging to cracks is obtained to a balanced accuracy of 95.27%, thus improving the results of previous approaches. Full article

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

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20 pages, 6260 KiB

Open AccessArticle

Control Measurements of Crane Rails Performed by Terrestrial Laser Scanning

by Klemen Kregar^1,*, Jan Možina², Tomaž Ambrožič¹

, Dušan Kogoj¹, Aleš Marjetič¹, Gašper Štebe¹ and Simona Savšek¹

¹ Faculty of Civil and Geodetic Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia

² BKR Ingenieurbüro GmbH, 69469 Weinheim, Germany

Sensors 2017, 17(7), 1671; https://doi.org/10.3390/s17071671 - 20 Jul 2017

Cited by 14 | Viewed by 5983

Abstract

This article presents a method for measuring the geometry of crane rails with terrestrial laser scanning (TLS). Two sets of crane rails were divided into segments, their planes were adjusted, and the characteristic rail lines were defined. We used their profiles to define [...] Read more.

This article presents a method for measuring the geometry of crane rails with terrestrial laser scanning (TLS). Two sets of crane rails were divided into segments, their planes were adjusted, and the characteristic rail lines were defined. We used their profiles to define the positional and altitude deviations of the rails, the span and height difference between the two rails, and we also verified that they complied with the Eurocode 3 standard. We tested the method on crane rails at the hydroelectric power plant in Krško and the thermal power plant in Brestanica. We used two scanning techniques: “pure” TLS (Riegel VZ-400) and “hybrid” TLS (Leica MS50) scanning. This article’s original contribution lies in the detailed presentation of the computations used to define the characteristic lines of the rails without using the numeric procedures from existing software packages. We also analysed the influence of segment length and point density on the rail geometry results, and compared the two laser scanning techniques. We also compared the results obtained by terrestrial laser scanning with the results obtained from the classic polar method, which served as a reference point for its precision. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 4553 KiB

Open AccessArticle

Theoretical Studies on Two-Photon Fluorescent Hg²⁺ Probes Based on the Coumarin-Rhodamine System

by Yujin Zhang and Jiancai Leng^*

School of Science, Qilu University of Technology, Jinan 250353, China

Sensors 2017, 17(7), 1672; https://doi.org/10.3390/s17071672 - 20 Jul 2017

Cited by 11 | Viewed by 5541

Abstract

The development of fluorescent sensors for Hg²⁺ has attracted much attention due to the well-known adverse effects of mercury on biological health. In the present work, the optical properties of two newly-synthesized Hg²⁺ chemosensors based on the coumarin-rhodamine system (named Pro1 [...] Read more.

The development of fluorescent sensors for Hg²⁺ has attracted much attention due to the well-known adverse effects of mercury on biological health. In the present work, the optical properties of two newly-synthesized Hg²⁺ chemosensors based on the coumarin-rhodamine system (named Pro1 and Pro2) were systematically investigated using time-dependent density functional theory. It is shown that Pro1 and Pro2 are effective ratiometric fluorescent Hg²⁺ probes, which recognize Hg²⁺ by Förster resonance energy transfer and through bond energy transfer mechanisms, respectively. To further understand the mechanisms of the two probes, we have developed an approach to predict the energy transfer rate between the donor and acceptor. Using this approach, it can be inferred that Pro1 has a six times higher energy transfer rate than Pro2. Thus the influence of spacer group between the donor and acceptor on the sensing performance of the probe is demonstrated. Specifically, two-photon absorption properties of these two probes are calculated. We have found that both probes show significant two-photon responses in the near-infrared light region. However, only the maximum two-photon absorption cross section of Pro1 is greatly enhanced with the presence of Hg²⁺, indicating that Pro1 can act as a potential two-photon excited fluorescent probe for Hg²⁺. The theoretical investigations would be helpful to build a relationship between the structure and the optical properties of the probes, providing information on the design of efficient two-photon fluorescent sensors that can be used for biological imaging of Hg²⁺ in vivo. Full article

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

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12 pages, 10526 KiB

Open AccessArticle

LEDs: Sources and Intrinsically Bandwidth-Limited Detectors

by Roberto Filippo^1,*, Emanuele Taralli² and Mauro Rajteri¹

¹ Nanoscience and materials division, INRiM—Istituto Nazionale di Ricerca Metrologica, Strada Delle Cacce, 91-10135 Torino TO, Italy

² SRON—Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands

Sensors 2017, 17(7), 1673; https://doi.org/10.3390/s17071673 - 20 Jul 2017

Cited by 71 | Viewed by 7148

Abstract

The increasing demand for light emitting diodes (LEDs) is driven by a number of application categories, including display backlighting, communications, signage, and general illumination. Nowadays, they have also become attractive candidates as new photometric standards. In recent years, LEDs have started to be [...] Read more.

The increasing demand for light emitting diodes (LEDs) is driven by a number of application categories, including display backlighting, communications, signage, and general illumination. Nowadays, they have also become attractive candidates as new photometric standards. In recent years, LEDs have started to be applied as wavelength-selective photo-detectors as well. Nevertheless, manufacturers’ datasheets are limited about LEDs used as sources in terms of degradation with operating time (aging) or shifting of the emission spectrum as a function of the forward current. On the contrary, as far as detection is concerned, information about spectral responsivity of LEDs is missing. We investigated, mainly from a radiometric point of view, more than 50 commercial LEDs of a wide variety of wavelength bands, ranging from ultraviolet (UV) to near infrared (NIR). Originally, the final aim was to find which LEDs could better work together as detector-emitter pairs for the creation of self-calibrating ground-viewing LED radiometers; however, the findings that we are sharing here following, have a general validity that could be exploited in several sensing applications. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 1065 KiB

Open AccessArticle

Scheduling for Emergency Tasks in Industrial Wireless Sensor Networks

by Changqing Xia¹, Xi Jin¹

, Linghe Kong^1,2 and Peng Zeng^1,*

¹ Laboratory of Networked Control Systems, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China

² Department of Computer Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Sensors 2017, 17(7), 1674; https://doi.org/10.3390/s17071674 - 20 Jul 2017

Cited by 10 | Viewed by 5218

Abstract

Wireless sensor networks (WSNs) are widely applied in industrial manufacturing systems. By means of centralized control, the real-time requirement and reliability can be provided by WSNs in industrial production. Furthermore, many approaches reserve resources for situations in which the controller cannot perform centralized [...] Read more.

Wireless sensor networks (WSNs) are widely applied in industrial manufacturing systems. By means of centralized control, the real-time requirement and reliability can be provided by WSNs in industrial production. Furthermore, many approaches reserve resources for situations in which the controller cannot perform centralized resource allocation. The controller assigns these resources as it becomes aware of when and where accidents have occurred. However, the reserved resources are limited, and such incidents are low-probability events. In addition, resource reservation may not be effective since the controller does not know when and where accidents will actually occur. To address this issue, we improve the reliability of scheduling for emergency tasks by proposing a method based on a stealing mechanism. In our method, an emergency task is transmitted by stealing resources allocated to regular flows. The challenges addressed in our work are as follows: (1) emergencies occur only occasionally, but the industrial system must deliver the corresponding flows within their deadlines when they occur; (2) we wish to minimize the impact of emergency flows by reducing the number of stolen flows. The contributions of this work are two-fold: (1) we first define intersections and blocking as new characteristics of flows; and (2) we propose a series of distributed routing algorithms to improve the schedulability and to reduce the impact of emergency flows. We demonstrate that our scheduling algorithm and analysis approach are better than the existing ones by extensive simulations. Full article

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

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14 pages, 2239 KiB

Open AccessArticle

An Adaptive Feature Learning Model for Sequential Radar High Resolution Range Profile Recognition

by Xuan Peng^*

, Xunzhang Gao, Yifan Zhang and Xiang Li

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

Sensors 2017, 17(7), 1675; https://doi.org/10.3390/s17071675 - 20 Jul 2017

Cited by 20 | Viewed by 5239

Abstract

This paper proposes a new feature learning method for the recognition of radar high resolution range profile (HRRP) sequences. HRRPs from a period of continuous changing aspect angles are jointly modeled and discriminated by a single model named the discriminative infinite restricted Boltzmann [...] Read more.

This paper proposes a new feature learning method for the recognition of radar high resolution range profile (HRRP) sequences. HRRPs from a period of continuous changing aspect angles are jointly modeled and discriminated by a single model named the discriminative infinite restricted Boltzmann machine (Dis-iRBM). Compared with the commonly used hidden Markov model (HMM)-based recognition method for HRRP sequences, which requires efficient preprocessing of the HRRP signal, the proposed method is an end-to-end method of which the input is the raw HRRP sequence, and the output is the label of the target. The proposed model can efficiently capture the global pattern in a sequence, while the HMM can only model local dynamics, which suffers from information loss. Last but not least, the proposed model learns the features of HRRP sequences adaptively according to the complexity of a single HRRP and the length of a HRRP sequence. Experimental results on the Moving and Stationary Target Acquisition and Recognition (MSTAR) database indicate that the proposed method is efficient and robust under various conditions. Full article

(This article belongs to the Section Remote Sensors)

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16 pages, 2462 KiB

Open AccessArticle

Identification of Load Categories in Rotor System Based on Vibration Analysis

by Kun Zhang

and Zhaojian Yang^*

College of Mechanical Engineering, Taiyuan University of Technology, Taiyuan 030024, China

Sensors 2017, 17(7), 1676; https://doi.org/10.3390/s17071676 - 20 Jul 2017

Cited by 10 | Viewed by 7108

Abstract

Rotating machinery is often subjected to variable loads during operation. Thus, monitoring and identifying different load types is important. Here, five typical load types have been qualitatively studied for a rotor system. A novel load category identification method for rotor system based on [...] Read more.

Rotating machinery is often subjected to variable loads during operation. Thus, monitoring and identifying different load types is important. Here, five typical load types have been qualitatively studied for a rotor system. A novel load category identification method for rotor system based on vibration signals is proposed. This method is a combination of ensemble empirical mode decomposition (EEMD), energy feature extraction, and back propagation (BP) neural network. A dedicated load identification test bench for rotor system was developed. According to loads characteristics and test conditions, an experimental plan was formulated, and loading tests for five loads were conducted. Corresponding vibration signals of the rotor system were collected for each load condition via eddy current displacement sensor. Signals were reconstructed using EEMD, and then features were extracted followed by energy calculations. Finally, characteristics were input to the BP neural network, to identify different load types. Comparison and analysis of identifying data and test data revealed a general identification rate of 94.54%, achieving high identification accuracy and good robustness. This shows that the proposed method is feasible. Due to reliable and experimentally validated theoretical results, this method can be applied to load identification and fault diagnosis for rotor equipment used in engineering applications. Full article

(This article belongs to the Special Issue Mechatronic Systems for Automatic Vehicles)

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22 pages, 503 KiB

Open AccessArticle

Lifetime Maximization via Hole Alleviation in IoT Enabling Heterogeneous Wireless Sensor Networks

by Zahid Wadud^1,2, Nadeem Javaid^3,*

, Muhammad Awais Khan³, Nabil Alrajeh⁴, Mohamad Souheil Alabed⁴ and Nadra Guizani⁵

¹ University of Engineering & Technology, Peshawar 25000, Pakistan

² Capital University of Science and Technology, Islamabad 44000, Pakistan

³ COMSATS Institute of Information Technology, Islamabad 44000, Pakistan

⁴ Biomedical Technology, Department College of Applied Medical Sciences, King Saud University, Riyadh 11633, Saudi Arabia

⁵ Department of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA

Sensors 2017, 17(7), 1677; https://doi.org/10.3390/s17071677 - 21 Jul 2017

Cited by 16 | Viewed by 6610

Abstract

In Internet of Things (IoT) enabled Wireless Sensor Networks (WSNs), there are two major factors which degrade the performance of the network. One is the void hole which occurs in a particular region due to unavailability of forwarder nodes. The other is the [...] Read more.

In Internet of Things (IoT) enabled Wireless Sensor Networks (WSNs), there are two major factors which degrade the performance of the network. One is the void hole which occurs in a particular region due to unavailability of forwarder nodes. The other is the presence of energy hole which occurs due to imbalanced data traffic load on intermediate nodes. Therefore, an optimum transmission strategy is required to maximize the network lifespan via hole alleviation. In this regard, we propose a heterogeneous network solution that is capable to balance energy dissipation among network nodes. In addition, the divide and conquer approach is exploited to evenly distribute number of transmissions over various network areas. An efficient forwarder node selection is performed to alleviate coverage and energy holes. Linear optimization is performed to validate the effectiveness of our proposed work in term of energy minimization. Furthermore, simulations are conducted to show that our claims are well grounded. Results show the superiority of our work as compared to the baseline scheme in terms of energy consumption and network lifetime. Full article

(This article belongs to the Special Issue Sensor Networks for Collaborative and Secure Internet of Things)

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30 pages, 7088 KiB

Open AccessArticle

Interference Effects Redress over Power-Efficient Wireless-Friendly Mesh Networks for Ubiquitous Sensor Communications across Smart Cities

by Jose Santana^1,2,*

, Domingo Marrero^1,3,*, Elsa Macías^1,3

, Vicente Mena^1,2 and Álvaro Suárez^1,3

¹ Grupo de Arquitectura y Concurrencia (GAC), Instituto Universitario de Ciencias y Tecnologías Cibernéticas (IUCTC), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria (ULPGC) 35017, Spain

² Departamento de Señales y Comunicaciones (DSC), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria (ULPGC) 35017, Spain

³ Departamento de Ingeniería Telemática (DIT), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria (ULPGC) 35017, Spain

Sensors 2017, 17(7), 1678; https://doi.org/10.3390/s17071678 - 21 Jul 2017

Cited by 9 | Viewed by 7638

Abstract

Ubiquitous sensing allows smart cities to take control of many parameters (e.g., road traffic, air or noise pollution levels, etc.). An inexpensive Wireless Mesh Network can be used as an efficient way to transport sensed data. When that mesh is autonomously powered (e.g., [...] Read more.

Ubiquitous sensing allows smart cities to take control of many parameters (e.g., road traffic, air or noise pollution levels, etc.). An inexpensive Wireless Mesh Network can be used as an efficient way to transport sensed data. When that mesh is autonomously powered (e.g., solar powered), it constitutes an ideal portable network system which can be deployed when needed. Nevertheless, its power consumption must be restrained to extend its operational cycle and for preserving the environment. To this end, our strategy fosters wireless interface deactivation among nodes which do not participate in any route. As we show, this contributes to a significant power saving for the mesh. Furthermore, our strategy is wireless-friendly, meaning that it gives priority to deactivation of nodes receiving (and also causing) interferences from (to) the rest of the smart city. We also show that a routing protocol can adapt to this strategy in which certain nodes deactivate their own wireless interfaces. Full article

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

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18 pages, 2001 KiB

Open AccessArticle

Classification of Alzheimer’s Patients through Ubiquitous Computing

by Alicia Nieto-Reyes^1,*, Rafael Duque¹, José Luis Montaña¹ and Carmen Lage²

¹ Department of Mathematics, Statistics and Computer Science, Universidad de Cantabria, 39005 Santander, Spain

² Cognitive Disorders Unit, Department of Neurology, Marqués de Valdecilla University Hospital (HUMV) Valdecilla Biomedical Research Institute (IDIVAL), 39008 Santander, Spain

Sensors 2017, 17(7), 1679; https://doi.org/10.3390/s17071679 - 21 Jul 2017

Cited by 13 | Viewed by 6049

Abstract

Functional data analysis and artificial neural networks are the building blocks of the proposed methodology that distinguishes the movement patterns among c’s patients on different stages of the disease and classifies new patients to their appropriate stage of the disease. The movement patterns [...] Read more.

Functional data analysis and artificial neural networks are the building blocks of the proposed methodology that distinguishes the movement patterns among c’s patients on different stages of the disease and classifies new patients to their appropriate stage of the disease. The movement patterns are obtained by the accelerometer device of android smartphones that the patients carry while moving freely. The proposed methodology is relevant in that it is flexible on the type of data to which it is applied. To exemplify that, it is analyzed a novel real three-dimensional functional dataset where each datum is observed in a different time domain. Not only is it observed on a difference frequency but also the domain of each datum has different length. The obtained classification success rate of

83 %

indicates the potential of the proposed methodology. Full article

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

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15 pages, 5053 KiB

Open AccessArticle

Hierarchical Stereo Matching in Two-Scale Space for Cyber-Physical System

by Eunah Choi¹, Sangyoon Lee² and Hyunki Hong^2,*

¹ Department of Imaging Science and Arts, GSAIM, Chung-Ang University, 221 Huksuk-dong, Dongjak-ku, Seoul 156-756, Korea

² School of Integrative Engineering, Chung-Ang University, 221 Huksuk-dong, Dongjak-ku, Seoul 156-756, Korea

Sensors 2017, 17(7), 1680; https://doi.org/10.3390/s17071680 - 21 Jul 2017

Cited by 4 | Viewed by 5834

Abstract

Dense disparity map estimation from a high-resolution stereo image is a very difficult problem in terms of both matching accuracy and computation efficiency. Thus, an exhaustive disparity search at full resolution is required. In general, examining more pixels in the stereo view results [...] Read more.

Dense disparity map estimation from a high-resolution stereo image is a very difficult problem in terms of both matching accuracy and computation efficiency. Thus, an exhaustive disparity search at full resolution is required. In general, examining more pixels in the stereo view results in more ambiguous correspondences. When a high-resolution image is down-sampled, the high-frequency components of the fine-scaled image are at risk of disappearing in the coarse-resolution image. Furthermore, if erroneous disparity estimates caused by missing high-frequency components are propagated across scale space, ultimately, false disparity estimates are obtained. To solve these problems, we introduce an efficient hierarchical stereo matching method in two-scale space. This method applies disparity estimation to the reduced-resolution image, and the disparity result is then up-sampled to the original resolution. The disparity estimation values of the high-frequency (or edge component) regions of the full-resolution image are combined with the up-sampled disparity results. In this study, we extracted the high-frequency areas from the scale-space representation by using difference of Gaussian (DoG) or found edge components, using a Canny operator. Then, edge-aware disparity propagation was used to refine the disparity map. The experimental results show that the proposed algorithm outperforms previous methods. Full article

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

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11 pages, 2407 KiB

Open AccessArticle

A Noncontact Dibutyl Phthalate Sensor Based on a Wireless-Electrodeless QCM-D Modified with Nano-Structured Nickel Hydroxide

by Daqi Chen¹

, Xiyang Sun¹, Kaihuan Zhang¹, Guokang Fan², You Wang¹, Guang Li¹ and Ruifen Hu^1,*

¹ State Key Laboratory of Industrial Control Technology, Institute of Cyber Systems and Control, Zhejiang University, Hangzhou 310027, China

² School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China

Sensors 2017, 17(7), 1681; https://doi.org/10.3390/s17071681 - 21 Jul 2017

Cited by 18 | Viewed by 5464

Abstract

Dibutyl phthalate (DBP) is a widely used plasticizer which has been found to be a reproductive and developmental toxicant and ubiquitously existing in the air. A highly sensitive method for DBP monitoring in the environment is urgently needed. A DBP sensor based on [...] Read more.

Dibutyl phthalate (DBP) is a widely used plasticizer which has been found to be a reproductive and developmental toxicant and ubiquitously existing in the air. A highly sensitive method for DBP monitoring in the environment is urgently needed. A DBP sensor based on a homemade wireless-electrodeless quartz crystal microbalance with dissipation (QCM-D) coated with nano-structured nickel hydroxide is presented. With the noncontact configuration, the sensing system could work at a higher resonance frequency (the 3rd overtone) and the response of the system was even more stable compared with a conventional quartz crystal microbalance (QCM). The sensor achieved a sensitivity of 7.3 Hz/ppb to DBP in a concentration range of 0.4–40 ppb and an ultra-low detection limit of 0.4 ppb of DBP has also been achieved. Full article

(This article belongs to the Section Chemical Sensors)

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24 pages, 4522 KiB

Open AccessArticle

4SM: A Novel Self-Calibrated Algebraic Ratio Method for Satellite-Derived Bathymetry and Water Column Correction

by Yann G. Morel^1,* and Fabio Favoretto²

¹ Retired, BP 2862 98703 Punaauia, French Polynesia

² Posgrado en Ciencias Marinas y Costeras (CIMACO) Universidad Autonoma de Baja California Sur, La Paz Baja California Sur 23080, Mexico

Sensors 2017, 17(7), 1682; https://doi.org/10.3390/s17071682 - 21 Jul 2017

Cited by 7 | Viewed by 7545

Abstract

All empirical water column correction methods have consistently been reported to require existing depth sounding data for the purpose of calibrating a simple depth retrieval model; they yield poor results over very bright or very dark bottoms. In contrast, we set out to [...] Read more.

All empirical water column correction methods have consistently been reported to require existing depth sounding data for the purpose of calibrating a simple depth retrieval model; they yield poor results over very bright or very dark bottoms. In contrast, we set out to (i) use only the relative radiance data in the image along with published data, and several new assumptions; (ii) in order to specify and operate the simplified radiative transfer equation (RTE); (iii) for the purpose of retrieving both the satellite derived bathymetry (SDB) and the water column corrected spectral reflectance over shallow seabeds. Sea truth regressions show that SDB depths retrieved by the method only need tide correction. Therefore it shall be demonstrated that, under such new assumptions, there is no need for (i) formal atmospheric correction; (ii) conversion of relative radiance into calibrated reflectance; or (iii) existing depth sounding data, to specify the simplified RTE and produce both SDB and spectral water column corrected radiance ready for bottom typing. Moreover, the use of the panchromatic band for that purpose is introduced. Altogether, we named this process the Self-Calibrated Supervised Spectral Shallow-sea Modeler (4SM). This approach requires a trained practitioner, though, to produce its results within hours of downloading the raw image. The ideal raw image should be a “near-nadir” view, exhibit homogeneous atmosphere and water column, include some coverage of optically deep waters and bare land, and lend itself to quality removal of haze, atmospheric adjacency effect, and sun/sky glint. Full article

(This article belongs to the Section Remote Sensors)

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22 pages, 8678 KiB

Open AccessArticle

Demonstration and Methodology of Structural Monitoring of Stringer Runs out Composite Areas by Embedded Optical Fiber Sensors and Connectors Integrated during Production in a Composite Plant

by Carlos Miguel Giraldo^1,2,*, Juan Zúñiga Sagredo¹, José Sánchez Gómez¹ and Pedro Corredera³

¹ Airbus Operations, S.L, Paseo John Lennon S/N, Getafe, 28906 Madrid, Spain

² Materials Science, ETSII, Universidad Politécnica de Madrid, José Gutiérrez Abascal, 2, 28006 Madrid, Spain

³ Instituto de Óptica (CSIC), 28006 Madrid, Spain

Sensors 2017, 17(7), 1683; https://doi.org/10.3390/s17071683 - 21 Jul 2017

Cited by 7 | Viewed by 8013

Abstract

Embedding optical fibers sensors into composite structures for Structural Health Monitoring purposes is not just one of the most attractive solutions contributing to smart structures, but also the optimum integration approach that insures maximum protection and integrity of the fibers. Nevertheless this intended [...] Read more.

Embedding optical fibers sensors into composite structures for Structural Health Monitoring purposes is not just one of the most attractive solutions contributing to smart structures, but also the optimum integration approach that insures maximum protection and integrity of the fibers. Nevertheless this intended integration level still remains an industrial challenge since today there is no mature integration process in composite plants matching all necessary requirements. This article describes the process developed to integrate optical fiber sensors in the Production cycle of a test specimen. The sensors, Bragg gratings, were integrated into the laminate during automatic tape lay-up and also by a secondary bonding process, both in the Airbus Composite Plant. The test specimen, completely representative of the root joint of the lower wing cover of a real aircraft, is comprised of a structural skin panel with the associated stringer run out. The ingress-egress was achieved through the precise design and integration of miniaturized optical connectors compatible with the manufacturing conditions and operational test requirements. After production, the specimen was trimmed, assembled and bolted to metallic plates to represent the real triform and buttstrap, and eventually installed into the structural test rig. The interrogation of the sensors proves the effectiveness of the integration process; the analysis of the strain results demonstrate the good correlation between fiber sensors and electrical gauges in those locations where they are installed nearby, and the curvature and load transfer analysis in the bolted stringer run out area enable demonstration of the consistency of the fiber sensors measurements. In conclusion, this work presents strong evidence of the performance of embedded optical sensors for structural health monitoring purposes, where in addition and most importantly, the fibers were integrated in a real production environment and the ingress-egress issue was solved by the design and integration of miniaturized connectors compatible with the manufacturing and structural test phases. Full article

(This article belongs to the Special Issue Non Destructive Testing and Evaluation of Aerospace Composite Structures)

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9 pages, 1696 KiB

Open AccessArticle

Selectively Enhanced UV-A Photoresponsivity of a GaN MSM UV Photodetector with a Step-Graded Al_xGa_1−xN Buffer Layer

by Chang-Ju Lee, Chul-Ho Won, Jung-Hee Lee, Sung-Ho Hahm and Hongsik Park^*

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

Sensors 2017, 17(7), 1684; https://doi.org/10.3390/s17071684 - 21 Jul 2017

Cited by 26 | Viewed by 7418

Abstract

The UV-to-visible rejection ratio is one of the important figure of merits of GaN-based UV photodetectors. For cost-effectiveness and large-scale fabrication of GaN devices, we tried to grow a GaN epitaxial layer on silicon substrate with complicated buffer layers for a stress-release. It [...] Read more.

The UV-to-visible rejection ratio is one of the important figure of merits of GaN-based UV photodetectors. For cost-effectiveness and large-scale fabrication of GaN devices, we tried to grow a GaN epitaxial layer on silicon substrate with complicated buffer layers for a stress-release. It is known that the structure of the buffer layers affects the performance of devices fabricated on the GaN epitaxial layers. In this study, we show that the design of a buffer layer structure can make effect on the UV-to-visible rejection ratio of GaN UV photodetectors. The GaN photodetector fabricated on GaN-on-silicon substrate with a step-graded Al_xGa_−xN buffer layer has a highly-selective photoresponse at 365-nm wavelength. The UV-to-visible rejection ratio of the GaN UV photodetector with the step-graded Al_xGa_1−xN buffer layer was an order-of-magnitude higher than that of a photodetector with a conventional GaN/AlN multi buffer layer. The maximum photoresponsivity was as high as 5 × 10⁻² A/W. This result implies that the design of buffer layer is important for photoresponse characteristics of GaN UV photodetectors as well as the crystal quality of the GaN epitaxial layers. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1244 KiB

Open AccessArticle

Noncontact Sleep Study by Multi-Modal Sensor Fusion

by Ku-young Chung¹, Kwangsub Song¹, Kangsoo Shin², Jinho Sohn², Seok Hyun Cho^3,* and Joon-Hyuk Chang^1,*

¹ Department of Electronics and Computer Engineering, Hanyang University, Seoul 04763, Korea

² Intelligence Lab, LG Electronics Woomyon Research and Development Campus, Seoul 06763, Korea

³ Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul 04763, Korea

Sensors 2017, 17(7), 1685; https://doi.org/10.3390/s17071685 - 21 Jul 2017

Cited by 32 | Viewed by 7400

Abstract

Polysomnography (PSG) is considered as the gold standard for determining sleep stages, but due to the obtrusiveness of its sensor attachments, sleep stage classification algorithms using noninvasive sensors have been developed throughout the years. However, the previous studies have not yet been proven [...] Read more.

Polysomnography (PSG) is considered as the gold standard for determining sleep stages, but due to the obtrusiveness of its sensor attachments, sleep stage classification algorithms using noninvasive sensors have been developed throughout the years. However, the previous studies have not yet been proven reliable. In addition, most of the products are designed for healthy customers rather than for patients with sleep disorder. We present a novel approach to classify sleep stages via low cost and noncontact multi-modal sensor fusion, which extracts sleep-related vital signals from radar signals and a sound-based context-awareness technique. This work is uniquely designed based on the PSG data of sleep disorder patients, which were received and certified by professionals at Hanyang University Hospital. The proposed algorithm further incorporates medical/statistical knowledge to determine personal-adjusted thresholds and devise post-processing. The efficiency of the proposed algorithm is highlighted by contrasting sleep stage classification performance between single sensor and sensor-fusion algorithms. To validate the possibility of commercializing this work, the classification results of this algorithm were compared with the commercialized sleep monitoring device, ResMed S+. The proposed algorithm was investigated with random patients following PSG examination, and results show a promising novel approach for determining sleep stages in a low cost and unobtrusive manner. Full article

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

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13 pages, 4535 KiB

Open AccessArticle

Aptamer-Based Carboxyl-Terminated Nanocrystalline Diamond Sensing Arrays for Adenosine Triphosphate Detection

by Evi Suaebah^1,*, Takuro Naramura¹, Miho Myodo¹, Masataka Hasegawa², Shuichi Shoji¹, Jorge J. Buendia¹ and Hiroshi Kawarada^1,3

¹ Department of Nanoscience and Nanoengineering, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan

² Technology Research Association for Single Wall Carbon Nanotube (TASC), 1-1-1 Higashi, Tsukuba 305-8565, Japan

³ Kagami Memorial Research Institute for Material Science and Technology, Shinjuku-ku, Tokyo 169-0051, Japan

Sensors 2017, 17(7), 1686; https://doi.org/10.3390/s17071686 - 21 Jul 2017

Cited by 7 | Viewed by 6810

Abstract

Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP) detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD). Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and [...] Read more.

Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP) detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD). Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and fluorine termination of the background region as a passivated layer were investigated by X-ray photoelectron spectroscopy. Single strand DNA (amide modification) was used as the supporting biomolecule to immobilize into the diamond surface via carboxyl termination and become a double strand with aptamer. ATP detection by aptamer was observed as a 66% fluorescence signal intensity decrease of the hybridization intensity signal. The sensor operation was also investigated by the field-effect characteristics. The shift of the drain current–drain voltage characteristics was used as the indicator for detection of ATP. From the field-effect characteristics, the shift of the drain current–drain voltage was observed in the negative direction. The negative charge direction shows that the aptamer is capable of detecting ATP. The ability of the sensor to detect ATP was investigated by fabricating a field-effect transistor on the modified NCD surface. Full article

(This article belongs to the Section Biosensors)

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18 pages, 6148 KiB

Open AccessArticle

Motor Control Training for the Shoulder with Smart Garments

by Qi Wang^1,*, Liesbet De Baets², Annick Timmermans², Wei Chen^3,4,*, Luca Giacolini¹, Thomas Matheve²

and Panos Markopoulos¹

¹ Department of Industrial Design, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands

² BIOMED REVAL Rehabilitation Research Institute, Faculty of Medicine and Life Sciences, Hasselt University, B-3590 Diepenbeek, Belgium

³ Center for Intelligent Medical Electronics, Department of Electronic Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China

⁴ Shanghai Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention, Shanghai 200000, China

Sensors 2017, 17(7), 1687; https://doi.org/10.3390/s17071687 - 22 Jul 2017

Cited by 23 | Viewed by 13193

Abstract

Wearable technologies for posture monitoring and posture correction are emerging as a way to support and enhance physical therapy treatment, e.g., for motor control training in neurological disorders or for treating musculoskeletal disorders, such as shoulder, neck, or lower back pain. Among the [...] Read more.

Wearable technologies for posture monitoring and posture correction are emerging as a way to support and enhance physical therapy treatment, e.g., for motor control training in neurological disorders or for treating musculoskeletal disorders, such as shoulder, neck, or lower back pain. Among the various technological options for posture monitoring, wearable systems offer potential advantages regarding mobility, use in different contexts and sustained tracking in daily life. We describe the design of a smart garment named Zishi to monitor compensatory movements and evaluate its applicability for shoulder motor control training in a clinical setting. Five physiotherapists and eight patients with musculoskeletal shoulder pain participated in the study. The attitudes of patients and therapists towards the system were measured using standardized survey instruments. The results indicate that patients and their therapists consider Zishi a credible aid for rehabilitation and patients expect it will help towards their recovery. The system was perceived as highly usable and patients were motivated to train with the system. Future research efforts on the improvement of the customization of feedback location and modality, and on the evaluation of Zishi as support for motor learning in shoulder patients, should be made. Full article

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

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21 pages, 1421 KiB

Open AccessArticle

Double-Layer Compressive Sensing Based Efficient DOA Estimation in WSAN with Block Data Loss

by Peng Sun¹

, Liantao Wu¹, Kai Yu¹

, Huajie Shao² and Zhi Wang^1,*

¹ State Key Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou 310027, China

² Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

Sensors 2017, 17(7), 1688; https://doi.org/10.3390/s17071688 - 22 Jul 2017

Cited by 2 | Viewed by 4962

Abstract

Accurate information acquisition is of vital importance for wireless sensor array network (WSAN) direction of arrival (DOA) estimation. However, due to the lossy nature of low-power wireless links, data loss, especially block data loss induced by adopting a large packet size, has a [...] Read more.

Accurate information acquisition is of vital importance for wireless sensor array network (WSAN) direction of arrival (DOA) estimation. However, due to the lossy nature of low-power wireless links, data loss, especially block data loss induced by adopting a large packet size, has a catastrophic effect on DOA estimation performance in WSAN. In this paper, we propose a double-layer compressive sensing (CS) framework to eliminate the hazards of block data loss, to achieve high accuracy and efficient DOA estimation. In addition to modeling the random packet loss during transmission as a passive CS process, an active CS procedure is introduced at each array sensor to further enhance the robustness of transmission. Furthermore, to avoid the error propagation from signal recovery to DOA estimation in conventional methods, we propose a direct DOA estimation technique under the double-layer CS framework. Leveraging a joint frequency and spatial domain sparse representation of the sensor array data, the fusion center (FC) can directly obtain the DOA estimation results according to the received data packets, skipping the phase of signal recovery. Extensive simulations demonstrate that the double-layer CS framework can eliminate the adverse effects induced by block data loss and yield a superior DOA estimation performance in WSAN. Full article

(This article belongs to the Section Sensor Networks)

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16 pages, 21411 KiB

Open AccessArticle

3D Reconstruction of Space Objects from Multi-Views by a Visible Sensor

by Haopeng Zhang^1,2,*

, Quanmao Wei^1,2 and Zhiguo Jiang^1,2,*

¹ Image Processing Center, School of Astronautics, Beihang University, Beijing 100191, China

² Beijing Key Laboratory of Digital Media, Beihang University, Beijing 100191, China

Sensors 2017, 17(7), 1689; https://doi.org/10.3390/s17071689 - 22 Jul 2017

Cited by 27 | Viewed by 7090

Abstract

In this paper, a novel 3D reconstruction framework is proposed to recover the 3D structural model of a space object from its multi-view images captured by a visible sensor. Given an image sequence, this framework first estimates the relative camera poses and recovers [...] Read more.

In this paper, a novel 3D reconstruction framework is proposed to recover the 3D structural model of a space object from its multi-view images captured by a visible sensor. Given an image sequence, this framework first estimates the relative camera poses and recovers the depths of the surface points by the structure from motion (SFM) method, then the patch-based multi-view stereo (PMVS) algorithm is utilized to generate a dense 3D point cloud. To resolve the wrong matches arising from the symmetric structure and repeated textures of space objects, a new strategy is introduced, in which images are added to SFM in imaging order. Meanwhile, a refining process exploiting the structural prior knowledge that most sub-components of artificial space objects are composed of basic geometric shapes is proposed and applied to the recovered point cloud. The proposed reconstruction framework is tested on both simulated image datasets and real image datasets. Experimental results illustrate that the recovered point cloud models of space objects are accurate and have a complete coverage of the surface. Moreover, outliers and points with severe noise are effectively filtered out by the refinement, resulting in an distinct improvement of the structure and visualization of the recovered points. Full article

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

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7 pages, 4441 KiB

Open AccessArticle

Pinhole Zone Plate Lens for Ultrasound Focusing

by Constanza Rubio¹

, José Miguel Fuster², Sergio Castiñeira-Ibáñez³, Antonio Uris¹, Francisco Belmar¹ and Pilar Candelas^1,*

¹ Centro de Tecnologías Físicas, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

² Departamento de Comunicaciones, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

³ Departamento de Ingeniería Electrónica, Universitat de València, Avd. de la Universitat s/n, 46100 Burjassot, Valencia, Spain

Sensors 2017, 17(7), 1690; https://doi.org/10.3390/s17071690 - 22 Jul 2017

Cited by 16 | Viewed by 8771

Abstract

The focusing capabilities of a pinhole zone plate lens are presented and compared with those of a conventional Fresnel zone plate lens. The focusing properties are examined both experimentally and numerically. The results confirm that a pinhole zone plate lens can be an [...] Read more.

The focusing capabilities of a pinhole zone plate lens are presented and compared with those of a conventional Fresnel zone plate lens. The focusing properties are examined both experimentally and numerically. The results confirm that a pinhole zone plate lens can be an alternative to a Fresnel lens. A smooth filtering effect is created in pinhole zone plate lenses, giving rise to a reduction of the side lobes around the principal focus associated with the conventional Fresnel zone plate lens. The manufacturing technique of the pinhole zone plate lens allows the designing and constructing of lenses for different focal lengths quickly and economically and without the need to drill new plates. Full article

(This article belongs to the Special Issue Acoustic Wave Resonator-Based Sensors)

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27 pages, 5196 KiB

Open AccessArticle

A Context-Driven Model for the Flat Roofs Construction Process through Sensing Systems, Internet-of-Things and Last Planner System

by María Dolores Andújar-Montoya¹, Diego Marcos-Jorquera²

, Francisco Manuel García-Botella²

and Virgilio Gilart-Iglesias^2,*

¹ Building Sciences and Urbanism Department, Polytechnic University College, University of Alicante, Carretera de San Vicente del Raspeig, s/n, 03690 Alicante, Spain

² Department of Computer Science and Technologies, Polytechnic University College, University of Alicante, Carretera de San Vicente del Raspeig, s/n, 03690 Alicante, Spain

Sensors 2017, 17(7), 1691; https://doi.org/10.3390/s17071691 - 22 Jul 2017

Cited by 10 | Viewed by 7172

Abstract

The main causes of building defects are errors in the design and the construction phases. These causes related to construction are mainly due to the general lack of control of construction work and represent approximately 75% of the anomalies. In particular, one of [...] Read more.

The main causes of building defects are errors in the design and the construction phases. These causes related to construction are mainly due to the general lack of control of construction work and represent approximately 75% of the anomalies. In particular, one of the main causes of such anomalies, which end in building defects, is the lack of control over the physical variables of the work environment during the execution of tasks. Therefore, the high percentage of defects detected in buildings that have the root cause in the construction phase could be avoidable with a more accurate and efficient control of the process. The present work proposes a novel integration model based on information and communications technologies for the automation of both construction work and its management at the execution phase, specifically focused on the flat roof construction process. Roofs represent the second area where more defects are claimed. The proposed model is based on a Web system, supported by a service oriented architecture, for the integral management of tasks through the Last Planner System methodology, but incorporating the management of task restrictions from the physical environment variables by designing specific sensing systems. Likewise, all workers are integrated into the management process by Internet-of-Things solutions that guide them throughout the execution process in a non-intrusive and transparent way. Full article

(This article belongs to the Special Issue New Generation Sensors Enabling and Fostering IoT)

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20 pages, 2567 KiB

Open AccessArticle

Angular Rate Sensing with GyroWheel Using Genetic Algorithm Optimized Neural Networks

by Yuyu Zhao^*, Hui Zhao, Xin Huo and Yu Yao

Control and Simulation Center, Harbin Institute of Technology, Harbin 150080, China

Sensors 2017, 17(7), 1692; https://doi.org/10.3390/s17071692 - 22 Jul 2017

Cited by 13 | Viewed by 5130

Abstract

GyroWheel is an integrated device that can provide three-axis control torques and two-axis angular rate sensing for small spacecrafts. Large tilt angle of its rotor and de-tuned spin rate lead to a complex and non-linear dynamics as well as difficulties in measuring angular [...] Read more.

GyroWheel is an integrated device that can provide three-axis control torques and two-axis angular rate sensing for small spacecrafts. Large tilt angle of its rotor and de-tuned spin rate lead to a complex and non-linear dynamics as well as difficulties in measuring angular rates. In this paper, the problem of angular rate sensing with the GyroWheel is investigated. Firstly, a simplified rate sensing equation is introduced, and the error characteristics of the method are analyzed. According to the analysis results, a rate sensing principle based on torque balance theory is developed, and a practical way to estimate the angular rates within the whole operating range of GyroWheel is provided by using explicit genetic algorithm optimized neural networks. The angular rates can be determined by the measurable values of the GyroWheel (including tilt angles, spin rate and torque coil currents), the weights and the biases of the neural networks. Finally, the simulation results are presented to illustrate the effectiveness of the proposed angular rate sensing method with GyroWheel. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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16 pages, 1108 KiB

Open AccessArticle

Efficient Retrieval of Massive Ocean Remote Sensing Images via a Cloud-Based Mean-Shift Algorithm

by Mengzhao Yang

, Wei Song

and Haibin Mei^*

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

Sensors 2017, 17(7), 1693; https://doi.org/10.3390/s17071693 - 23 Jul 2017

Cited by 7 | Viewed by 5630

Abstract

The rapid development of remote sensing (RS) technology has resulted in the proliferation of high-resolution images. There are challenges involved in not only storing large volumes of RS images but also in rapidly retrieving the images for ocean disaster analysis such as for [...] Read more.

The rapid development of remote sensing (RS) technology has resulted in the proliferation of high-resolution images. There are challenges involved in not only storing large volumes of RS images but also in rapidly retrieving the images for ocean disaster analysis such as for storm surges and typhoon warnings. In this paper, we present an efficient retrieval of massive ocean RS images via a Cloud-based mean-shift algorithm. Distributed construction method via the pyramid model is proposed based on the maximum hierarchical layer algorithm and used to realize efficient storage structure of RS images on the Cloud platform. We achieve high-performance processing of massive RS images in the Hadoop system. Based on the pyramid Hadoop distributed file system (HDFS) storage method, an improved mean-shift algorithm for RS image retrieval is presented by fusion with the canopy algorithm via Hadoop MapReduce programming. The results show that the new method can achieve better performance for data storage than HDFS alone and WebGIS-based HDFS. Speedup and scaleup are very close to linear changes with an increase of RS images, which proves that image retrieval using our method is efficient. Full article

(This article belongs to the Special Issue Marine Sensing)

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14 pages, 843 KiB

Open AccessArticle

Emotion Recognition from Chinese Speech for Smart Affective Services Using a Combination of SVM and DBN

by Lianzhang Zhu^1,*, Leiming Chen¹

, Dehai Zhao¹, Jiehan Zhou²

and Weishan Zhang^1,*

¹ Department of Software Engineering, China University of Petroleum, No. 66 Changjiang West Road, Qingdao 266031, China

² Department of Information Processing Science, University of Oulu, Oulu FI-91004, Finland

Sensors 2017, 17(7), 1694; https://doi.org/10.3390/s17071694 - 24 Jul 2017

Cited by 120 | Viewed by 9531

Abstract

Accurate emotion recognition from speech is important for applications like smart health care, smart entertainment, and other smart services. High accuracy emotion recognition from Chinese speech is challenging due to the complexities of the Chinese language. In this paper, we explore how to [...] Read more.

Accurate emotion recognition from speech is important for applications like smart health care, smart entertainment, and other smart services. High accuracy emotion recognition from Chinese speech is challenging due to the complexities of the Chinese language. In this paper, we explore how to improve the accuracy of speech emotion recognition, including speech signal feature extraction and emotion classification methods. Five types of features are extracted from a speech sample: mel frequency cepstrum coefficient (MFCC), pitch, formant, short-term zero-crossing rate and short-term energy. By comparing statistical features with deep features extracted by a Deep Belief Network (DBN), we attempt to find the best features to identify the emotion status for speech. We propose a novel classification method that combines DBN and SVM (support vector machine) instead of using only one of them. In addition, a conjugate gradient method is applied to train DBN in order to speed up the training process. Gender-dependent experiments are conducted using an emotional speech database created by the Chinese Academy of Sciences. The results show that DBN features can reflect emotion status better than artificial features, and our new classification approach achieves an accuracy of 95.8%, which is higher than using either DBN or SVM separately. Results also show that DBN can work very well for small training databases if it is properly designed. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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15 pages, 1781 KiB

Open AccessArticle

A Secure and Verifiable Outsourced Access Control Scheme in Fog-Cloud Computing

by Kai Fan^1,*

, Junxiong Wang¹, Xin Wang¹, Hui Li¹ and Yintang Yang²

¹ State Key Laboratory of Integrated Service Networks, Xidian University, Xi’an 710071, China

² Key Laboratory of the Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi’an 710071, China

Sensors 2017, 17(7), 1695; https://doi.org/10.3390/s17071695 - 24 Jul 2017

Cited by 77 | Viewed by 9929

Abstract

With the rapid development of big data and Internet of things (IOT), the number of networking devices and data volume are increasing dramatically. Fog computing, which extends cloud computing to the edge of the network can effectively solve the bottleneck problems of data [...] Read more.

With the rapid development of big data and Internet of things (IOT), the number of networking devices and data volume are increasing dramatically. Fog computing, which extends cloud computing to the edge of the network can effectively solve the bottleneck problems of data transmission and data storage. However, security and privacy challenges are also arising in the fog-cloud computing environment. Ciphertext-policy attribute-based encryption (CP-ABE) can be adopted to realize data access control in fog-cloud computing systems. In this paper, we propose a verifiable outsourced multi-authority access control scheme, named VO-MAACS. In our construction, most encryption and decryption computations are outsourced to fog devices and the computation results can be verified by using our verification method. Meanwhile, to address the revocation issue, we design an efficient user and attribute revocation method for it. Finally, analysis and simulation results show that our scheme is both secure and highly efficient. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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32 pages, 9071 KiB

Open AccessArticle

Parametric Loop Division for 3D Localization in Wireless Sensor Networks

by Tanveer Ahmad

, Xue Jun Li

and Boon-Chong Seet^*

Department of Electrical and Electronic Engineering, Auckland University of Technology, Auckland 1010, New Zealand

Sensors 2017, 17(7), 1697; https://doi.org/10.3390/s17071697 - 24 Jul 2017

Cited by 48 | Viewed by 7120

Abstract

Localization in Wireless Sensor Networks (WSNs) has been an active topic for more than two decades. A variety of algorithms were proposed to improve the localization accuracy. However, they are either limited to two-dimensional (2D) space, or require specific sensor deployment for proper [...] Read more.

Localization in Wireless Sensor Networks (WSNs) has been an active topic for more than two decades. A variety of algorithms were proposed to improve the localization accuracy. However, they are either limited to two-dimensional (2D) space, or require specific sensor deployment for proper operations. In this paper, we proposed a three-dimensional (3D) localization scheme for WSNs based on the well-known parametric Loop division (PLD) algorithm. The proposed scheme localizes a sensor node in a region bounded by a network of anchor nodes. By iteratively shrinking that region towards its center point, the proposed scheme provides better localization accuracy as compared to existing schemes. Furthermore, it is cost-effective and independent of environmental irregularity. We provide an analytical framework for the proposed scheme and find its lower bound accuracy. Simulation results shows that the proposed algorithm provides an average localization accuracy of 0.89 m with a standard deviation of 1.2 m. Full article

(This article belongs to the Section Sensor Networks)

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15 pages, 2504 KiB

Open AccessArticle

The Role of Heart-Rate Variability Parameters in Activity Recognition and Energy-Expenditure Estimation Using Wearable Sensors

by Heesu Park^†

, Suh-Yeon Dong^†

, Miran Lee and Inchan Youn^*

¹ Center for Bionics, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(7), 1698; https://doi.org/10.3390/s17071698 - 24 Jul 2017

Cited by 35 | Viewed by 7520

Abstract

Human-activity recognition (HAR) and energy-expenditure (EE) estimation are major functions in the mobile healthcare system. Both functions have been investigated for a long time; however, several challenges remain unsolved, such as the confusion between activities and the recognition of energy-consuming activities involving little [...] Read more.

Human-activity recognition (HAR) and energy-expenditure (EE) estimation are major functions in the mobile healthcare system. Both functions have been investigated for a long time; however, several challenges remain unsolved, such as the confusion between activities and the recognition of energy-consuming activities involving little or no movement. To solve these problems, we propose a novel approach using an accelerometer and electrocardiogram (ECG). First, we collected a database of six activities (sitting, standing, walking, ascending, resting and running) of 13 voluntary participants. We compared the HAR performances of three models with respect to the input data type (with none, all, or some of the heart-rate variability (HRV) parameters). The best recognition performance was 96.35%, which was obtained with some selected HRV parameters. EE was also estimated for different choices of the input data type (with or without HRV parameters) and the model type (single and activity-specific). The best estimation performance was found in the case of the activity-specific model with HRV parameters. Our findings indicate that the use of human physiological data, obtained by wearable sensors, has a significant impact on both HAR and EE estimation, which are crucial functions in the mobile healthcare system. Full article

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

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Review

Jump to: Research, Other

19 pages, 587 KiB

Open AccessReview

Bluetooth Low Energy Mesh Networks: A Survey

by Seyed Mahdi Darroudi

and Carles Gomez^*

Department of Network Engineering, Universitat Polit̀ecnica de Catalunya, Castelldefels 08860, Spain

Sensors 2017, 17(7), 1467; https://doi.org/10.3390/s17071467 - 22 Jun 2017

Cited by 143 | Viewed by 19596

Abstract

Bluetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. [...] Read more.

Bluetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. For these reasons, academia, industry, and standards development organizations have been designing solutions to enable BLE mesh networks. Nevertheless, the literature lacks a consolidated view on this emerging area. This paper comprehensively surveys state of the art BLE mesh networking. We first provide a taxonomy of BLE mesh network solutions. We then review the solutions, describing the variety of approaches that leverage existing BLE functionality to enable BLE mesh networks. We identify crucial aspects of BLE mesh network solutions and discuss their advantages and drawbacks. Finally, we highlight currently open issues. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 3105 KiB

Open AccessReview

Digital Microfluidics for Nucleic Acid Amplification

by Beatriz Coelho¹

, Bruno Veigas^1,2, Elvira Fortunato¹, Rodrigo Martins¹

, Hugo Águas¹

, Rui Igreja^1,*

and Pedro V. Baptista^2,*

¹ i3N|CENIMAT, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal

² UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal

Sensors 2017, 17(7), 1495; https://doi.org/10.3390/s17071495 - 25 Jun 2017

Cited by 54 | Viewed by 10018

Abstract

Digital Microfluidics (DMF) has emerged as a disruptive methodology for the control and manipulation of low volume droplets. In DMF, each droplet acts as a single reactor, which allows for extensive multiparallelization of biological and chemical reactions at a much smaller scale. DMF [...] Read more.

Digital Microfluidics (DMF) has emerged as a disruptive methodology for the control and manipulation of low volume droplets. In DMF, each droplet acts as a single reactor, which allows for extensive multiparallelization of biological and chemical reactions at a much smaller scale. DMF devices open entirely new and promising pathways for multiplex analysis and reaction occurring in a miniaturized format, thus allowing for healthcare decentralization from major laboratories to point-of-care with accurate, robust and inexpensive molecular diagnostics. Here, we shall focus on DMF platforms specifically designed for nucleic acid amplification, which is key for molecular diagnostics of several diseases and conditions, from pathogen identification to cancer mutations detection. Particular attention will be given to the device architecture, materials and nucleic acid amplification applications in validated settings. Full article

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

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30 pages, 980 KiB

Open AccessReview

Review of Portable and Low-Cost Sensors for the Ambient Air Monitoring of Benzene and Other Volatile Organic Compounds

by Laurent Spinelle¹

, Michel Gerboles^1,*

, Gertjan Kok², Stefan Persijn² and Tilman Sauerwald³

¹ European Commission—Joint Research Centre, 21027 Ispra, Italy

² VSL Dutch Metrology Institute, 2629 JA Delft, The Netherlands

³ Laboratory for Measurement Technology, Universitaet des Saarlandes, 66123 Saarbruecken, Germany

Sensors 2017, 17(7), 1520; https://doi.org/10.3390/s17071520 - 28 Jun 2017

Cited by 340 | Viewed by 23351

Abstract

This article presents a literature review of sensors for the monitoring of benzene in ambient air and other volatile organic compounds. Combined with information provided by stakeholders, manufacturers and literature, the review considers commercially available sensors, including PID-based sensors, semiconductor (resistive gas sensors) [...] Read more.

This article presents a literature review of sensors for the monitoring of benzene in ambient air and other volatile organic compounds. Combined with information provided by stakeholders, manufacturers and literature, the review considers commercially available sensors, including PID-based sensors, semiconductor (resistive gas sensors) and portable on-line measuring devices as for example sensor arrays. The bibliographic collection includes the following topics: sensor description, field of application at fixed sites, indoor and ambient air monitoring, range of concentration levels and limit of detection in air, model descriptions of the phenomena involved in the sensor detection process, gaseous interference selectivity of sensors in complex VOC matrix, validation data in lab experiments and under field conditions. Full article

(This article belongs to the Section Chemical Sensors)

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14 pages, 3441 KiB

Open AccessReview

Gas Sensors Based on Molecular Imprinting Technology

by Yumin Zhang^1,2, Jin Zhang^2,* and Qingju Liu^2,*

¹ School of Physics and Astronomy, Yunnan University, 650091 Kunming, China

² School of Materials Science and Engineering, Yunnan Key Laboratory for Micro/Nano Materials & Technology, Yunnan University, 650091 Kunming, China

Sensors 2017, 17(7), 1567; https://doi.org/10.3390/s17071567 - 4 Jul 2017

Cited by 50 | Viewed by 7853

Abstract

Molecular imprinting technology (MIT); often described as a method of designing a material to remember a target molecular structure (template); is a technique for the creation of molecularly imprinted polymers (MIPs) with custom-made binding sites complementary to the target molecules in shape; size [...] Read more.

Molecular imprinting technology (MIT); often described as a method of designing a material to remember a target molecular structure (template); is a technique for the creation of molecularly imprinted polymers (MIPs) with custom-made binding sites complementary to the target molecules in shape; size and functional groups. MIT has been successfully applied to analyze; separate and detect macromolecular organic compounds. Furthermore; it has been increasingly applied in assays of biological macromolecules. Owing to its unique features of structure specificity; predictability; recognition and universal application; there has been exploration of the possible application of MIPs in the field of highly selective gas sensors. In this present study; we outline the recent advances in gas sensors based on MIT; classify and introduce the existing molecularly imprinted gas sensors; summarize their advantages and disadvantages; and analyze further research directions. Full article

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

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20 pages, 3328 KiB

Open AccessReview

Early Diagnosis of Breast Cancer

by Lulu Wang^1,2

¹ School of Instrument Science and Opto-Electronics Engineering, Hefei University of Technology, Hefei 230009, China

² Institute of Biomedical Technologies, Auckland University of Technology, Auckland 1142, New Zealand

Sensors 2017, 17(7), 1572; https://doi.org/10.3390/s17071572 - 5 Jul 2017

Cited by 393 | Viewed by 41297

Abstract

Early-stage cancer detection could reduce breast cancer death rates significantly in the long-term. The most critical point for best prognosis is to identify early-stage cancer cells. Investigators have studied many breast diagnostic approaches, including mammography, magnetic resonance imaging, ultrasound, computerized tomography, positron emission [...] Read more.

Early-stage cancer detection could reduce breast cancer death rates significantly in the long-term. The most critical point for best prognosis is to identify early-stage cancer cells. Investigators have studied many breast diagnostic approaches, including mammography, magnetic resonance imaging, ultrasound, computerized tomography, positron emission tomography and biopsy. However, these techniques have some limitations such as being expensive, time consuming and not suitable for young women. Developing a high-sensitive and rapid early-stage breast cancer diagnostic method is urgent. In recent years, investigators have paid their attention in the development of biosensors to detect breast cancer using different biomarkers. Apart from biosensors and biomarkers, microwave imaging techniques have also been intensely studied as a promising diagnostic tool for rapid and cost-effective early-stage breast cancer detection. This paper aims to provide an overview on recent important achievements in breast screening methods (particularly on microwave imaging) and breast biomarkers along with biosensors for rapidly diagnosing breast cancer. Full article

(This article belongs to the Special Issue Biosensors for Cancer Biomarkers)

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9 pages, 1454 KiB

Open AccessReview

Overview of Single-Molecule Speckle (SiMS) Microscopy and Its Electroporation-Based Version with Efficient Labeling and Improved Spatiotemporal Resolution

by Sawako Yamashiro^1,* and Naoki Watanabe^1,2

¹ Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan

² Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan

Sensors 2017, 17(7), 1585; https://doi.org/10.3390/s17071585 - 6 Jul 2017

Cited by 5 | Viewed by 5436

Abstract

Live-cell single-molecule imaging was introduced more than a decade ago, and has provided critical information on remodeling of the actin cytoskeleton, the motion of plasma membrane proteins, and dynamics of molecular motor proteins. Actin remodeling has been the best target for this approach [...] Read more.

Live-cell single-molecule imaging was introduced more than a decade ago, and has provided critical information on remodeling of the actin cytoskeleton, the motion of plasma membrane proteins, and dynamics of molecular motor proteins. Actin remodeling has been the best target for this approach because actin and its associated proteins stop diffusing when assembled, allowing visualization of single-molecules of fluorescently-labeled proteins in a state specific manner. The approach based on this simple principle is called Single-Molecule Speckle (SiMS) microscopy. For instance, spatiotemporal regulation of actin polymerization and lifetime distribution of actin filaments can be monitored directly by tracking actin SiMS. In combination with fluorescently labeled probes of various actin regulators, SiMS microscopy has contributed to clarifying the processes underlying recycling, motion and remodeling of the live-cell actin network. Recently, we introduced an electroporation-based method called eSiMS microscopy, with high efficiency, easiness and improved spatiotemporal precision. In this review, we describe the application of live-cell single-molecule imaging to cellular actin dynamics and discuss the advantages of eSiMS microscopy over previous SiMS microscopy. Full article

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

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20 pages, 3475 KiB

Open AccessReview

Raman Plus X: Biomedical Applications of Multimodal Raman Spectroscopy

by Nandan K. Das, Yichuan Dai, Peng Liu, Chuanzhen Hu, Lieshu Tong, Xiaoya Chen and Zachary J. Smith^*

Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230027, China

Sensors 2017, 17(7), 1592; https://doi.org/10.3390/s17071592 - 7 Jul 2017

Cited by 34 | Viewed by 7973

Abstract

Raman spectroscopy is a label-free method of obtaining detailed chemical information about samples. Its compatibility with living tissue makes it an attractive choice for biomedical analysis, yet its translation from a research tool to a clinical tool has been slow, hampered by fundamental [...] Read more.

Raman spectroscopy is a label-free method of obtaining detailed chemical information about samples. Its compatibility with living tissue makes it an attractive choice for biomedical analysis, yet its translation from a research tool to a clinical tool has been slow, hampered by fundamental Raman scattering issues such as long integration times and limited penetration depth. In this review we detail the how combining Raman spectroscopy with other techniques yields multimodal instruments that can help to surmount the translational barriers faced by Raman alone. We review Raman combined with several optical and non-optical methods, including fluorescence, elastic scattering, OCT, phase imaging, and mass spectrometry. In each section we highlight the power of each combination along with a brief history and presentation of representative results. Finally, we conclude with a perspective detailing both benefits and challenges for multimodal Raman measurements, and give thoughts on future directions in the field. Full article

(This article belongs to the Special Issue Applications of Raman Spectroscopy in Biosensors)

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38 pages, 6419 KiB

Open AccessReview

Traceability of On-Machine Tool Measurement: A Review

by Unai Mutilba^1,*

, Eneko Gomez-Acedo¹, Gorka Kortaberria¹, Aitor Olarra¹ and Jose A. Yagüe-Fabra²

¹ Department of Mechanical Engineering, IK4-Tekniker, Eibar 20600, Spain

² I3A, Universidad de Zaragoza, Zaragoza 50018, Spain

Sensors 2017, 17(7), 1605; https://doi.org/10.3390/s17071605 - 11 Jul 2017

Cited by 72 | Viewed by 15847

Abstract

Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close [...] Read more.

Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close measurements and fast feedback into their manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They provide the possibility to measure the workpiece in-machine during or after its manufacture, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable enough for process control or product validation. The scientific objective is to determine the uncertainty on a machine tool measurement and, therefore, convert it into a machine integrated traceable measuring process. For that purpose, an error budget should consider error sources such as the machine tools, components under measurement and the interactions between both of them. This paper reviews all those uncertainty sources, being mainly focused on those related to the machine tool, either on the process of geometric error assessment of the machine or on the technology employed to probe the measurand. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 20565 KiB

Open AccessReview

Novel Flexible Wearable Sensor Materials and Signal Processing for Vital Sign and Human Activity Monitoring

by Amir Servati^1,2,*, Liang Zou¹

, Z. Jane Wang¹, Frank Ko² and Peyman Servati^1,*

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

² Department of Materials Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada

Sensors 2017, 17(7), 1622; https://doi.org/10.3390/s17071622 - 13 Jul 2017

Cited by 93 | Viewed by 16492

Abstract

Advances in flexible electronic materials and smart textile, along with broad availability of smart phones, cloud and wireless systems have empowered the wearable technologies for significant impact on future of digital and personalized healthcare as well as consumer electronics. However, challenges related to [...] Read more.

Advances in flexible electronic materials and smart textile, along with broad availability of smart phones, cloud and wireless systems have empowered the wearable technologies for significant impact on future of digital and personalized healthcare as well as consumer electronics. However, challenges related to lack of accuracy, reliability, high power consumption, rigid or bulky form factor and difficulty in interpretation of data have limited their wide-scale application in these potential areas. As an important solution to these challenges, we present latest advances in novel flexible electronic materials and sensors that enable comfortable and conformable body interaction and potential for invisible integration within daily apparel. Advances in novel flexible materials and sensors are described for wearable monitoring of human vital signs including, body temperature, respiratory rate and heart rate, muscle movements and activity. We then present advances in signal processing focusing on motion and noise artifact removal, data mining and aspects of sensor fusion relevant to future clinical applications of wearable technology. Full article

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

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17 pages, 3526 KiB

Open AccessReview

The Application of Whole Cell-Based Biosensors for Use in Environmental Analysis and in Medical Diagnostics

by Qingyuan Gui¹, Tom Lawson², Suyan Shan¹, Lu Yan¹ and Yong Liu^1,*

¹ Laboratory of Nanoscale Biosensing and Bioimaging, Instiute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xueyuanxi Road, Wenzhou 325027, China

² ARC Center of Excellence for Nanoscale BioPhotonics, Macquarie University, Sydney, NSW 2109, Australia

Sensors 2017, 17(7), 1623; https://doi.org/10.3390/s17071623 - 13 Jul 2017

Cited by 280 | Viewed by 23125

Abstract

Various whole cell-based biosensors have been reported in the literature for the last 20 years and these reports have shown great potential for their use in the areas of pollution detection in environmental and in biomedical diagnostics. Unlike other reviews of this growing [...] Read more.

Various whole cell-based biosensors have been reported in the literature for the last 20 years and these reports have shown great potential for their use in the areas of pollution detection in environmental and in biomedical diagnostics. Unlike other reviews of this growing field, this mini-review argues that: (1) the selection of reporter genes and their regulatory proteins are directly linked to the performance of celllular biosensors; (2) broad enhancements in microelectronics and information technologies have also led to improvements in the performance of these sensors; (3) their future potential is most apparent in their use in the areas of medical diagnostics and in environmental monitoring; and (4) currently the most promising work is focused on the better integration of cellular sensors with nano and micro scaled integrated chips. With better integration it may become practical to see these cells used as (5) real-time portable devices for diagnostics at the bedside and for remote environmental toxin detection and this in situ application will make the technology commonplace and thus as unremarkable as other ubiquitous technologies. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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16 pages, 3837 KiB

Open AccessReview

Zinc Oxide-Based Self-Powered Potentiometric Chemical Sensors for Biomolecules and Metal Ions

by Muhammad Israr-Qadir^1,2, Sadaf Jamil-Rana³, Omer Nur¹ and Magnus Willander^1,*

¹ Department of Science and Technology, Linköping University, SE-60174 Norrköping, Sweden

² Department of Materials Engineering, School of Chemical and Materials Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan

³ Department of Physics, Government College Women University, Sialkot 51310, Pakistan

Sensors 2017, 17(7), 1645; https://doi.org/10.3390/s17071645 - 19 Jul 2017

Cited by 16 | Viewed by 6883

Abstract

Advances in the miniaturization and portability of the chemical sensing devices have always been hindered by the external power supply problem, which has focused new interest in the fabrication of self-powered sensing devices for disease diagnosis and the monitoring of analytes. This review [...] Read more.

Advances in the miniaturization and portability of the chemical sensing devices have always been hindered by the external power supply problem, which has focused new interest in the fabrication of self-powered sensing devices for disease diagnosis and the monitoring of analytes. This review describes the fabrication of ZnO nanomaterial-based sensors synthesized on different conducting substrates for extracellular detection, and the use of a sharp borosilicate glass capillary (diameter, d = 700 nm) to grow ZnO nanostructures for intracellular detection purposes in individual human and frog cells. The electrocatalytic activity and fast electron transfer properties of the ZnO materials provide the necessary energy to operate as well as a quick sensing device output response, where the role of the nanomorphology utilized for the fabrication of the sensor is crucial for the production of the operational energy. Simplicity, design, cost, sensitivity, selectivity and a quick and stable response are the most important features of a reliable sensor for routine applications. The review details the extra- and intra-cellular applications of the biosensors for the detection and monitoring of different metallic ions present in biological matrices, along with the biomolecules glucose and cholesterol. Full article

(This article belongs to the Special Issue Self-Powered Sensors)

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21 pages, 6217 KiB

Open AccessReview

Predicting Magnetoelectric Coupling in Layered and Graded Composites

by Mirza Bichurin^*, Vladimir Petrov

and Alexander Tatarenko

Institute of Electronic and Information Systems, Novgorod State University, Veiky Novgorod 173003, Russia

Sensors 2017, 17(7), 1651; https://doi.org/10.3390/s17071651 - 19 Jul 2017

Cited by 14 | Viewed by 5580

Abstract

Magnetoelectric (ME) interaction in magnetostrictive-piezoelectric multiferroic structures consists in inducing the electric field across the structure in an applied magnetic field and is a product property of magnetostriction and piezoelectricity in components. ME voltage coefficient that is the ratio of induced electric field [...] Read more.

Magnetoelectric (ME) interaction in magnetostrictive-piezoelectric multiferroic structures consists in inducing the electric field across the structure in an applied magnetic field and is a product property of magnetostriction and piezoelectricity in components. ME voltage coefficient that is the ratio of induced electric field to applied magnetic field is the key parameter of ME coupling strength. It has been known that the ME coupling strength is dictated by the product of the piezoelectric and piezomagnetic coefficients of initial phases. As a result, using the laminates with graded piezoelectric and piezomagnetic parameters are a new pathway to the increase in the ME coupling strength. Recently developed models predict stronger ME interactions in composites based on graded components compared to homogeneous ones. We discuss predicting the ME coupling strength for layered structures of homogeneous and compositionally graded magnetostrictive and piezoelectric components based on the graphs of ME voltage coefficients against composite parameters. For obtaining the graphs, we developed equations for ME output in applied magnetic field for possible modes of operation and layered structure configurations. In particular, our studies have been performed on low-frequency ME coupling, enhanced ME effect in electromechanical resonance (EMR) region for longitudinal and bending modes. Additionally, ME coupling at magnetic resonance in magnetostrictive component and at overlapping the EMR and magnetic resonance is investigated. We considered symmetric trilayers and asymmetric bilayers of magnetostrictive and piezoelectric components and multilayered structures based on compositionally stepped initial components. Full article

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

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8 pages, 1745 KiB

Open AccessLetter

The Resistance–Amplitude–Frequency Effect of In–Liquid Quartz Crystal Microbalance

by Xianhe Huang^*, Qingsong Bai, Qi Zhou and Jianguo Hu

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

Sensors 2017, 17(7), 1476; https://doi.org/10.3390/s17071476 - 22 Jun 2017

Cited by 12 | Viewed by 7438

Abstract

Due to the influence of liquid load, the equivalent resistance of in-liquid quartz crystal microbalance (QCM) increases sharply, and the quality factor and resonant frequency decreases. We found that the change in the resonant frequency of in-liquid QCM consisted of two parts: besides [...] Read more.

Due to the influence of liquid load, the equivalent resistance of in-liquid quartz crystal microbalance (QCM) increases sharply, and the quality factor and resonant frequency decreases. We found that the change in the resonant frequency of in-liquid QCM consisted of two parts: besides the frequency changes due to the mass and viscous load (which could be equivalent to motional inductance), the second part of frequency change was caused by the increase of motional resistance. The theoretical calculation and simulation proved that the increases of QCM motional resistance may indeed cause the decreases of resonant frequency, and revealed that the existence of static capacitance was the root cause of this frequency change. The second part of frequency change (due to the increases of motional resistance) was difficult to measure accurately, and may cause great error for in-liquid QCM applications. A technical method to reduce the interference caused by this effect is presented. The study contributes to the accurate determination of the frequency and amplitude change of in-liquid QCM caused by liquid load, which is significant for the QCM applications in the liquid phase. Full article

(This article belongs to the Section Chemical Sensors)

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8 pages, 13451 KiB

Open AccessTechnical Note

Flexible Boron-Doped Diamond (BDD) Electrodes for Plant Monitoring

by Shoko Tago¹, Tsuyoshi Ochiai^1,2,3,*

, Seitaro Suzuki^1,4, Mio Hayashi¹, Takeshi Kondo³ and Akira Fujishima^1,3

¹ Photocatalyst Group, Research and Development Department, Local Independent Administrative Agency Kanagawa Institute of industrial Science and TEChnology (KISTEC), 407 East Wing, Innovation Center Building, KSP, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan

² Materials Analysis Group, Kawasaki Technical Support Department, KISTEC, Ground Floor East Wing, Innovation Center Building, KSP, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan

³ Photocatalysis International Research Centre, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan

⁴ Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro-machi, Minamisaitama-gun, Saitama 345-8501, Japan

Sensors 2017, 17(7), 1638; https://doi.org/10.3390/s17071638 - 15 Jul 2017

Cited by 16 | Viewed by 7526

Abstract

Detecting the bio-potential changes of plants would be useful for monitoring their growth and health in the field. A sensitive plant monitoring system with flexible boron-doped diamond (BDD) electrodes prepared from BDD powder and resin (Nafion or Vylon-KE1830) was investigated. The properties of [...] Read more.

Detecting the bio-potential changes of plants would be useful for monitoring their growth and health in the field. A sensitive plant monitoring system with flexible boron-doped diamond (BDD) electrodes prepared from BDD powder and resin (Nafion or Vylon-KE1830) was investigated. The properties of the electrodes were compared with those of small BDD plate-type electrodes by monitoring the bioelectric potentials of potted Aloe and hybrid species in the genus Opuntia. While flexible BDD electrodes have wide potential windows, their cyclic voltammograms are different from those of the BDD plate. Further, the potential gap between a pair of electrodes attached to the plants changes as the plants are stimulated artificially with a finger touch, suggesting that the bioelectric potentials in the plant also changed, manifesting as changes in the potential gap between the electrodes. The BDD electrodes were assessed for their response reproducibility to a finger stimulus for 30 days. It was concluded that the plant monitoring system worked well with flexible BDD electrodes. Further, the electrodes were stable, and as reliable as the BDD plate electrodes in this study. Thus, a flexible and inexpensive BDD electrode system was successfully fabricated for monitoring the bioelectric potential changes in plants. Full article

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

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