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15 pages, 2535 KiB

Open AccessArticle

A Method for Remotely Sensing Vital Signs of Human Subjects Outdoors

by Chuantao Li¹, Fuming Chen¹

, Jingxi Jin¹, Hao Lv¹, Sheng Li¹, Guohua Lu^1,*

and Jianqi Wang^1,2,*

¹ Department of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China

² Shaanxi University of Technology, Hanzhong 723001, China

Sensors 2015, 15(7), 14830-14844; https://doi.org/10.3390/s150714830 - 24 Jun 2015

Cited by 39 | Viewed by 8118

Abstract

After chemical or nuclear leakage or explosions, finding survivors is a huge challenge. Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way. This paper [...] Read more.

After chemical or nuclear leakage or explosions, finding survivors is a huge challenge. Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way. This paper describes a continuous wave radar sensor for remotely sensing the vital signs of human subjects. Firstly, a compact and portable 24 GHz Doppler radar system is designed to conduct non-contact detection of respiration signal. Secondly, in order to improve the quality of the respiration signals, the self-correlation and adaptive line enhancer (ALE) methods are proposed to minimize the interferences of any moving objects around the human subject. Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors. The method provided in this paper will be a promising way to search for human subjects outdoors. Full article

(This article belongs to the Section Remote Sensors)

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19 pages, 1916 KiB

Open AccessArticle

Creating TUIs Using RFID Sensors—A Case Study Based on the Literacy Process of Children with Down Syndrome

by Janio Jadán-Guerrero^1,*, Luis Guerrero¹, Gustavo López¹

, Doris Cáliz² and José Bravo³

¹ Research Center for Communication and Information Technologies, Universidad de Costa Rica CITIC-UCR, Ciudad Universitaria Rodrigo Facio, San José 2060, Costa Rica

² Universidad Politécnica de Madrid, Campus de Montegancedo, Madrid 28660, Spain

³ MAmI Research Lab, Universidad de Castilla La Mancha, Ciudad Real 13071, Spain

Sensors 2015, 15(7), 14845-14863; https://doi.org/10.3390/s150714845 - 24 Jun 2015

Cited by 17 | Viewed by 9902

Abstract

Teaching children with intellectual disabilities is a big challenge for most parents and educators. Special education teachers use learning strategies to develop and enhance motivation for complex learning tasks. Literacy acquisition is an essential and life-long skill for a child with intellectual disabilities. [...] Read more.

Teaching children with intellectual disabilities is a big challenge for most parents and educators. Special education teachers use learning strategies to develop and enhance motivation for complex learning tasks. Literacy acquisition is an essential and life-long skill for a child with intellectual disabilities. In this context, technology can support specific strategies that will help children learn to read. This paper introduces a Tangible User Interface (TUI) system based on Radio Frequency Identification (RFID) technology to support literacy for children with Down syndrome. Our proposed system focuses on the integration of RFID tags in 3D printed objects and low cost toys. The paper describes the experience of using some materials covering the tags and the different problems related to the material and distance of radio wave propagation. The results of a preliminary evaluation in a special education institution showed that the system helps to improve the interaction between teachers and children. The use of a TUI seems to give a physical sensory experience to develop literacy skills in children with Down syndrome. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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16 pages, 1495 KiB

Open AccessArticle

Mass and Force Sensing of an Adsorbate on a Beam Resonator Sensor

by Yin Zhang^* and Ya-Pu Zhao

State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

Sensors 2015, 15(7), 14871-14886; https://doi.org/10.3390/s150714871 - 24 Jun 2015

Cited by 19 | Viewed by 6082

Abstract

The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of [...] Read more.

The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors, such as position and axial force, can also cause the shifts of resonant frequencies. The in situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as small as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated, and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of a mechanical resonator sensor for two reasons: reducing extra experimental equipment and achieving better mass sensing by considering more factors. Full article

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

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15 pages, 5418 KiB

Open AccessArticle

Low-Light Image Enhancement Using Adaptive Digital Pixel Binning

by Yoonjong Yoo¹, Jaehyun Im² and Joonki Paik^1,*

¹ Image Processing and Intelligent Systems Laboratory Graduate School of Advanced Imaging Science, Multimedia, and Film Chung-Ang University, Seoul 156-756, Korea

² CIS Division, SK Hynix, Gyeonggi-do 463-844, Korea

Sensors 2015, 15(7), 14917-14931; https://doi.org/10.3390/s150714917 - 25 Jun 2015

Cited by 29 | Viewed by 10266

Abstract

This paper presents an image enhancement algorithm for low-light scenes in an environment with insufficient illumination. Simple amplification of intensity exhibits various undesired artifacts: noise amplification, intensity saturation, and loss of resolution. In order to enhance low-light images without undesired artifacts, a novel [...] Read more.

This paper presents an image enhancement algorithm for low-light scenes in an environment with insufficient illumination. Simple amplification of intensity exhibits various undesired artifacts: noise amplification, intensity saturation, and loss of resolution. In order to enhance low-light images without undesired artifacts, a novel digital binning algorithm is proposed that considers brightness, context, noise level, and anti-saturation of a local region in the image. The proposed algorithm does not require any modification of the image sensor or additional frame-memory; it needs only two line-memories in the image signal processor (ISP). Since the proposed algorithm does not use an iterative computation, it can be easily embedded in an existing digital camera ISP pipeline containing a high-resolution image sensor. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4382 KiB

Open AccessArticle

MEMS Microphone Array Sensor for Air-Coupled Impact-Echo

by Robin Groschup^* and Christian U. Grosse

Technische Universität München (TUM), Chair of Non-destructive Testing, Baumbachstr. 7, 81245 Munich, Germany

Sensors 2015, 15(7), 14932-14945; https://doi.org/10.3390/s150714932 - 25 Jun 2015

Cited by 31 | Viewed by 13251

Abstract

Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing [...] Read more.

Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved. The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation. The proposed sensing strategy is justified with findings from numerical simulations, showing that the IE resonance in plate like structures causes coherent surface displacements on the specimen under test in an area around the impact location. Therefore, by placing several MEMS microphones on a sensor array board, the IE resonance is easier to be identified in the recorded spectra than with single point microphones or contact type transducers. A comparative measurement between the array sensor, a conventional accelerometer and a measurement microphone clearly shows the suitability of MEMS type microphones and the advantages of using these microphones in an array arrangement for IE. The MEMS microphone array will make air-coupled IE measurements faster and more reliable. Full article

(This article belongs to the Special Issue Novel Sensors for Non-Destructive Testing and Structural Health Monitoring)

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14 pages, 3601 KiB

Open AccessArticle

Eco Assist Techniques through Real-time Monitoring of BEV Energy Usage Efficiency

by Younsun Kim, Ingeol Lee and Sungho Kang^*

Department of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea

Sensors 2015, 15(7), 14946-14959; https://doi.org/10.3390/s150714946 - 25 Jun 2015

Cited by 10 | Viewed by 6077

Abstract

Energy efficiency enhancement has become an increasingly important issue for battery electric vehicles. Even if it can be improved in many ways, the driver’s driving pattern strongly influences the battery energy consumption of a vehicle. In this paper, eco assist techniques to simply [...] Read more.

Energy efficiency enhancement has become an increasingly important issue for battery electric vehicles. Even if it can be improved in many ways, the driver’s driving pattern strongly influences the battery energy consumption of a vehicle. In this paper, eco assist techniques to simply implement an energy-efficient driving assistant system are introduced, including eco guide, eco control and eco monitoring methods. The eco guide is provided to control the vehicle speed and accelerator pedal stroke, and eco control is suggested to limit the output power of the battery. For eco monitoring, the eco indicator and eco report are suggested to teach eco-friendly driving habits. The vehicle test, which is done in four ways, consists of federal test procedure (FTP)-75, new european driving cycle (NEDC), city and highway cycles, and visual feedback with audible warnings is provided to attract the driver’s voluntary participation. The vehicle test result shows that the energy usage efficiency can be increased up to 19.41%. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 496 KiB

Open AccessArticle

Efficient and Secure Temporal Credential-Based Authenticated Key Agreement Using Extended Chaotic Maps for Wireless Sensor Networks

by Tian-Fu Lee

Department of Medical Informatics, Tzu Chi University, No. 701, Zhongyang Road, Sec. 3, Hualien 97004, Taiwan

Sensors 2015, 15(7), 14960-14980; https://doi.org/10.3390/s150714960 - 25 Jun 2015

Cited by 11 | Viewed by 4950

Abstract

A secure temporal credential-based authenticated key agreement scheme for Wireless Sensor Networks (WSNs) enables a user, a sensor node and a gateway node to realize mutual authentication using temporal credentials. The user and the sensor node then negotiate a common secret key with [...] Read more.

A secure temporal credential-based authenticated key agreement scheme for Wireless Sensor Networks (WSNs) enables a user, a sensor node and a gateway node to realize mutual authentication using temporal credentials. The user and the sensor node then negotiate a common secret key with the help of the gateway node, and establish a secure and authenticated channel using this common secret key. To increase efficiency, recent temporal credential-based authenticated key agreement schemes for WSNs have been designed to involve few computational operations, such as hash and exclusive-or operations. However, these schemes cannot protect the privacy of users and withstand possible attacks. This work develops a novel temporal credential-based authenticated key agreement scheme for WSNs using extended chaotic maps, in which operations are more efficient than modular exponential computations and scalar multiplications on an elliptic curve. The proposed scheme not only provides higher security and efficiency than related schemes, but also resolves their weaknesses. Full article

(This article belongs to the Section Sensor Networks)

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25 pages, 1797 KiB

Open AccessArticle

Observed Thermal Impacts of Wind Farms Over Northern Illinois

by Lauren M. Slawsky¹, Liming Zhou^1,*, Somnath Baidya Roy², Geng Xia¹, Mathias Vuille¹ and Ronald A. Harris¹

¹ Department of Atmospheric and Environmental Sciences, SUNY at Albany, Albany, NY 12222, USA

² Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India

Sensors 2015, 15(7), 14981-15005; https://doi.org/10.3390/s150714981 - 25 Jun 2015

Cited by 34 | Viewed by 7097

Abstract

This paper assesses impacts of three wind farms in northern Illinois using land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites for the period 2003–2013. Changes in LST between two periods (before and [...] Read more.

This paper assesses impacts of three wind farms in northern Illinois using land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites for the period 2003–2013. Changes in LST between two periods (before and after construction of the wind turbines) and between wind farm pixels and nearby non-wind-farm pixels are quantified. An areal mean increase in LST by 0.18–0.39 °C is observed at nighttime over the wind farms, with the geographic distribution of this warming effect generally spatially coupled with the layout of the wind turbines (referred to as the spatial coupling), while there is no apparent impact on daytime LST. The nighttime LST warming effect varies with seasons, with the strongest warming in winter months of December-February, and the tightest spatial coupling in summer months of June-August. Analysis of seasonal variations in wind speed and direction from weather balloon sounding data and Automated Surface Observing System hourly observations from nearby stations suggest stronger winds correspond to seasons with greater warming and larger downwind impacts. The early morning soundings in Illinois are representative of the nighttime boundary layer and exhibit strong temperature inversions across all seasons. The strong and relatively shallow inversion in summer leaves warm air readily available to be mixed down and spatially well coupled with the turbine. Although the warming effect is strongest in winter, the spatial coupling is more erratic and spread out than in summer. These results suggest that the observed warming signal at nighttime is likely due to the net downward transport of heat from warmer air aloft to the surface, caused by the turbulent mixing in the wakes of the spinning turbine rotor blades. Full article

(This article belongs to the Section Remote Sensors)

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27 pages, 1433 KiB

Open AccessArticle

Optimal Parameter Design of Coarse Alignment for Fiber Optic Gyro Inertial Navigation System

by Baofeng Lu^1,*, Qiuying Wang², Chunmei Yu^3,4 and Wei Gao¹

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

² College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China

³ Aerospace and Materials Engineering, National University of Defense Technology, Changsha 410000, China

⁴ National Aerospace Intelligence Control Technology Laboratory, Beijing Aerospace Automatic Control Institute, Beijing 100854, China

Sensors 2015, 15(7), 15006-15032; https://doi.org/10.3390/s150715006 - 25 Jun 2015

Cited by 12 | Viewed by 5253

Abstract

Two different coarse alignment algorithms for Fiber Optic Gyro (FOG) Inertial Navigation System (INS) based on inertial reference frame are discussed in this paper. Both of them are based on gravity vector integration, therefore, the performance of these algorithms is determined by integration [...] Read more.

Two different coarse alignment algorithms for Fiber Optic Gyro (FOG) Inertial Navigation System (INS) based on inertial reference frame are discussed in this paper. Both of them are based on gravity vector integration, therefore, the performance of these algorithms is determined by integration time. In previous works, integration time is selected by experience. In order to give a criterion for the selection process, and make the selection of the integration time more accurate, optimal parameter design of these algorithms for FOG INS is performed in this paper. The design process is accomplished based on the analysis of the error characteristics of these two coarse alignment algorithms. Moreover, this analysis and optimal parameter design allow us to make an adequate selection of the most accurate algorithm for FOG INS according to the actual operational conditions. The analysis and simulation results show that the parameter provided by this work is the optimal value, and indicate that in different operational conditions, the coarse alignment algorithms adopted for FOG INS are different in order to achieve better performance. Lastly, the experiment results validate the effectiveness of the proposed algorithm. Full article

(This article belongs to the Section Sensor Networks)

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34 pages, 1116 KiB

Open AccessArticle

A Novel Two-Tier Cooperative Caching Mechanism for the Optimization of Multi-Attribute Periodic Queries in Wireless Sensor Networks

by ZhangBing Zhou^1,4,*, Deng Zhao¹, Lei Shu²

and Kim-Fung Tsang³

¹ School of Information Engineering, China University of Geosciences (Beijing), Beijing 100083, China

² Guangdong Provincial Key Lab. of Petrochemical Equipment Fault Diagnosis, Guangdong University of Petrochemical Technology, Maoming 525000, China

³ Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China

⁴ Computer Science Department, TELECOM SudParis, Evry 91011, France

Sensors 2015, 15(7), 15033-15066; https://doi.org/10.3390/s150715033 - 26 Jun 2015

Cited by 16 | Viewed by 5604

Abstract

Wireless sensor networks, serving as an important interface between physical environments and computational systems, have been used extensively for supporting domain applications, where multiple-attribute sensory data are queried from the network continuously and periodically. Usually, certain sensory data may not vary significantly within [...] Read more.

Wireless sensor networks, serving as an important interface between physical environments and computational systems, have been used extensively for supporting domain applications, where multiple-attribute sensory data are queried from the network continuously and periodically. Usually, certain sensory data may not vary significantly within a certain time duration for certain applications. In this setting, sensory data gathered at a certain time slot can be used for answering concurrent queries and may be reused for answering the forthcoming queries when the variation of these data is within a certain threshold. To address this challenge, a popularity-based cooperative caching mechanism is proposed in this article, where the popularity of sensory data is calculated according to the queries issued in recent time slots. This popularity reflects the possibility that sensory data are interested in the forthcoming queries. Generally, sensory data with the highest popularity are cached at the sink node, while sensory data that may not be interested in the forthcoming queries are cached in the head nodes of divided grid cells. Leveraging these cooperatively cached sensory data, queries are answered through composing these two-tier cached data. Experimental evaluation shows that this approach can reduce the network communication cost significantly and increase the network capability. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 863 KiB

Open AccessArticle

An Efficient Biometric-Based Algorithm Using Heart Rate Variability for Securing Body Sensor Networks

by Sandeep Pirbhulal^1,2,3,†, Heye Zhang^1,2,†, Subhas Chandra Mukhopadhyay⁴, Chunyue Li^1,2, Yumei Wang⁵, Guanglin Li^1,2,6, Wanqing Wu^1,2,* and Yuan-Ting Zhang^1,2,7

¹ Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

² Key Laboratory for Health Informatics of the Chinese Academy of Sciences (HICAS), Shenzhen Institutes of Advanced Technology, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen 518055, China

⁴ School of Engineering and Advanced Technology, Massey University, Palmerston North 4442, New Zealand

⁵ Shenzhen Nanshan District Xili Hospital, Shenzhen 518055, China

⁶ Key Laboratory of Human-Machine-Intelligence Synergic System, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences (CAS), Shenzhen 518055, Guangdong, China

⁷ Joint Research Centre for Biomedical Engineering, Chinese University of Hong Kong, Shatin N.T., Hong Kong, China

^† These authors contributed equally to this work.

³ Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, China

Sensors 2015, 15(7), 15067-15089; https://doi.org/10.3390/s150715067 - 26 Jun 2015

Cited by 76 | Viewed by 9709

Abstract

Body Sensor Network (BSN) is a network of several associated sensor nodes on, inside or around the human body to monitor vital signals, such as, Electroencephalogram (EEG), Photoplethysmography (PPG), Electrocardiogram (ECG), etc. Each sensor node in BSN delivers major information; therefore, it is [...] Read more.

Body Sensor Network (BSN) is a network of several associated sensor nodes on, inside or around the human body to monitor vital signals, such as, Electroencephalogram (EEG), Photoplethysmography (PPG), Electrocardiogram (ECG), etc. Each sensor node in BSN delivers major information; therefore, it is very significant to provide data confidentiality and security. All existing approaches to secure BSN are based on complex cryptographic key generation procedures, which not only demands high resource utilization and computation time, but also consumes large amount of energy, power and memory during data transmission. However, it is indispensable to put forward energy efficient and computationally less complex authentication technique for BSN. In this paper, a novel biometric-based algorithm is proposed, which utilizes Heart Rate Variability (HRV) for simple key generation process to secure BSN. Our proposed algorithm is compared with three data authentication techniques, namely Physiological Signal based Key Agreement (PSKA), Data Encryption Standard (DES) and Rivest Shamir Adleman (RSA). Simulation is performed in Matlab and results suggest that proposed algorithm is quite efficient in terms of transmission time utilization, average remaining energy and total power consumption. Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 1178 KiB

Open AccessArticle

A Double Transducer for High Precision Ultrasonic Time-Domain Reflectometry Measurements

by Sam Stade^1,*, Tuomas Hakkarainen², Mari Kallioinen¹, Mika Mänttäri¹

and Tuure Tuuva²

¹ Laboratory of Separation Technology, School of Engineering Science, Lappeenranta University of Technology, P.O. Box 20, Lappeenranta FI-53851, Finland

² Laboratory of Physics, School of Engineering Science, Lappeenranta University of Technology, P.O. Box 20, Lappeenranta FIN-53851, Finland

Sensors 2015, 15(7), 15090-15100; https://doi.org/10.3390/s150715090 - 26 Jun 2015

Cited by 4 | Viewed by 5397

Abstract

Membrane fouling, where unwanted particles accumulate on the membrane surface and reduce its permeability, causes problems in membrane filtration processes. With ultrasonic time-domain reflectometry (UTDR) it is possible to measure the extent of membrane fouling and hence take actions to minimize it. However, [...] Read more.

Membrane fouling, where unwanted particles accumulate on the membrane surface and reduce its permeability, causes problems in membrane filtration processes. With ultrasonic time-domain reflectometry (UTDR) it is possible to measure the extent of membrane fouling and hence take actions to minimize it. However, the usability of UTDR is very limited to constant filtration conditions if the sonic velocity, which has a great impact on UTDR measurement accuracy, is unknown. With a reference transducer the actual sonic velocity can be measured. This requires another transducer to be installed in the module, where there may be only limited space or the module dimensions may not be suitable for the reference transducer. A double transducer described in this study eliminates the need for a separate reference transducer because in the double transducer the reference measurement is included in the design of the transducer holder. Two sensors in the same holder require less space. Other advantage is that the double transducer can be placed near the measurement target and hence the local sonic velocity can be determined. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 4594 KiB

Open AccessArticle

Using Wireless Sensor Networks and Trains as Data Mules to Monitor Slab Track Infrastructures

by Eduardo Cañete^*, Jaime Chen, Manuel Díaz, Luis Llopis, Ana Reyna and Bartolomé Rubio

Department of Languages and Computer Science, University of Málaga, Boulevar Louis Pasteur 35, Málaga 29071, Spain

Sensors 2015, 15(7), 15101-15126; https://doi.org/10.3390/s150715101 - 26 Jun 2015

Cited by 11 | Viewed by 10012

Abstract

Recently, slab track systems have arisen as a safer and more sustainable option for high speed railway infrastructures, compared to traditional ballasted tracks. Integrating Wireless Sensor Networks within these infrastructures can provide structural health related data that can be used to evaluate their [...] Read more.

Recently, slab track systems have arisen as a safer and more sustainable option for high speed railway infrastructures, compared to traditional ballasted tracks. Integrating Wireless Sensor Networks within these infrastructures can provide structural health related data that can be used to evaluate their degradation and to not only detect failures but also to predict them. The design of such systems has to deal with a scenario of large areas with inaccessible zones, where neither Internet coverage nor electricity supply is guaranteed. In this paper we propose a monitoring system for slab track systems that measures vibrations and displacements in the track. Collected data is transmitted to passing trains, which are used as data mules to upload the information to a remote control center. On arrival at the station, the data is stored in a database, which is queried by an application in order to detect and predict failures. In this paper, different communication architectures are designed and tested to select the most suitable system meeting such requirements as efficiency, low cost and data accuracy. In addition, to ensure communication between the sensing devices and the train, the communication system must take into account parameters such as train speed, antenna coverage, band and frequency. Full article

(This article belongs to the Section Physical Sensors)

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32 pages, 831 KiB

Open AccessArticle

A Secure Routing Protocol for Wireless Sensor Networks Considering Secure Data Aggregation

by Triana Mugia Rahayu, Sang-Gon Lee^* and Hoon-Jae Lee

Department of Ubiquitous IT, Dongseo University, Busan 617-716, South Korea

Sensors 2015, 15(7), 15127-15158; https://doi.org/10.3390/s150715127 - 26 Jun 2015

Cited by 29 | Viewed by 7597

Abstract

The commonly unattended and hostile deployments of WSNs and their resource-constrained sensor devices have led to an increasing demand for secure energy-efficient protocols. Routing and data aggregation receive the most attention since they are among the daily network routines. With the awareness of [...] Read more.

The commonly unattended and hostile deployments of WSNs and their resource-constrained sensor devices have led to an increasing demand for secure energy-efficient protocols. Routing and data aggregation receive the most attention since they are among the daily network routines. With the awareness of such demand, we found that so far there has been no work that lays out a secure routing protocol as the foundation for a secure data aggregation protocol. We argue that the secure routing role would be rendered useless if the data aggregation scheme built on it is not secure. Conversely, the secure data aggregation protocol needs a secure underlying routing protocol as its foundation in order to be effectively optimal. As an attempt for the solution, we devise an energy-aware protocol based on LEACH and ESPDA that combines secure routing protocol and secure data aggregation protocol. We then evaluate its security effectiveness and its energy-efficiency aspects, knowing that there are always trade-off between both. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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20 pages, 27272 KiB

Open AccessArticle

Tool for Semiautomatic Labeling of Moving Objects in Video Sequences: TSLAB

by Carlos Cuevas^*, Eva María Yáñez and Narciso García

Grupo de Tratamiento de Imágenes, Universidad Politécnica de Madrid (UPM), E-28040 Madrid, Spain

Sensors 2015, 15(7), 15159-15178; https://doi.org/10.3390/s150715159 - 29 Jun 2015

Cited by 13 | Viewed by 6051

Abstract

An advanced and user-friendly tool for fast labeling of moving objects captured with surveillance sensors is proposed, which is available to the public. This tool allows the creation of three kinds of labels: moving objects, shadows and occlusions. These labels are created at [...] Read more.

An advanced and user-friendly tool for fast labeling of moving objects captured with surveillance sensors is proposed, which is available to the public. This tool allows the creation of three kinds of labels: moving objects, shadows and occlusions. These labels are created at both the pixel level and object level, which makes them suitable to assess the quality of both moving object detection strategies and tracking algorithms. The labeling can be performed easily and quickly thanks to a very friendly graphical user interface that allows one to automatize many common operations. This interface also includes some semiautomatic advanced tools that simplify the labeling tasks and drastically reduce the time required to obtain high-quality results. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 4827 KiB

Open AccessArticle

Recognition of a Phase-Sensitivity OTDR Sensing System Based on Morphologic Feature Extraction

by Qian Sun, Hao Feng^*, Xueying Yan and Zhoumo Zeng

Tianjin University, State Key Laboratory of Precision Measurement Technology & Instruments, 92 Weijin Road, Nankai District, Tianjin 300072, China

Sensors 2015, 15(7), 15179-15197; https://doi.org/10.3390/s150715179 - 29 Jun 2015

Cited by 136 | Viewed by 9493

Abstract

This paper proposes a novel feature extraction method for intrusion event recognition within a phase-sensitive optical time-domain reflectometer (Φ-OTDR) sensing system. Feature extraction of time domain signals in these systems is time-consuming and may lead to inaccuracies due to noise disturbances. The recognition [...] Read more.

This paper proposes a novel feature extraction method for intrusion event recognition within a phase-sensitive optical time-domain reflectometer (Φ-OTDR) sensing system. Feature extraction of time domain signals in these systems is time-consuming and may lead to inaccuracies due to noise disturbances. The recognition accuracy and speed of current systems cannot meet the requirements of Φ-OTDR online vibration monitoring systems. In the method proposed in this paper, the time-space domain signal is used for feature extraction instead of the time domain signal. Feature vectors are obtained from morphologic features of time-space domain signals. A scatter matrix is calculated for the feature selection. Experiments show that the feature extraction method proposed in this paper can greatly improve recognition accuracies, with a lower computation time than traditional methods, i.e., a recognition accuracy of 97.8% can be achieved with a recognition time of below 1 s, making it is very suitable for Φ-OTDR system online vibration monitoring. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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20 pages, 1560 KiB

Open AccessArticle

A Novel Feature Extraction Approach Using Window Function Capturing and QPSO-SVM for Enhancing Electronic Nose Performance

by Xiuzhen Guo¹, Chao Peng¹, Songlin Zhang¹, Jia Yan^1,*

, Shukai Duan¹, Lidan Wang¹, Pengfei Jia¹ and Fengchun Tian²

¹ College of Electronics and Information Engineering, Southwest University, Chongqing 400715, China

² College of Communication Engineering, Chongqing University, Chongqing 400044, China

Sensors 2015, 15(7), 15198-15217; https://doi.org/10.3390/s150715198 - 29 Jun 2015

Cited by 23 | Viewed by 7591

Abstract

In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved [...] Read more.

In this paper, a novel feature extraction approach which can be referred to as moving window function capturing (MWFC) has been proposed to analyze signals of an electronic nose (E-nose) used for detecting types of infectious pathogens in rat wounds. Meanwhile, a quantum-behaved particle swarm optimization (QPSO) algorithm is implemented in conjunction with support vector machine (SVM) for realizing a synchronization optimization of the sensor array and SVM model parameters. The results prove the efficacy of the proposed method for E-nose feature extraction, which can lead to a higher classification accuracy rate compared to other established techniques. Meanwhile it is interesting to note that different classification results can be obtained by changing the types, widths or positions of windows. By selecting the optimum window function for the sensor response, the performance of an E-nose can be enhanced. Full article

(This article belongs to the Section Chemical Sensors)

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28 pages, 16677 KiB

Open AccessArticle

Articulated Non-Rigid Point Set Registration for Human Pose Estimation from 3D Sensors

by Song Ge and Guoliang Fan^*

School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK 74078, USA

Sensors 2015, 15(7), 15218-15245; https://doi.org/10.3390/s150715218 - 29 Jun 2015

Cited by 13 | Viewed by 10076

Abstract

We propose a generative framework for 3D human pose estimation that is able to operate on both individual point sets and sequential depth data. We formulate human pose estimation as a point set registration problem, where we propose three new approaches to address [...] Read more.

We propose a generative framework for 3D human pose estimation that is able to operate on both individual point sets and sequential depth data. We formulate human pose estimation as a point set registration problem, where we propose three new approaches to address several major technical challenges in this research. First, we integrate two registration techniques that have a complementary nature to cope with non-rigid and articulated deformations of the human body under a variety of poses. This unique combination allows us to handle point sets of complex body motion and large pose variation without any initial conditions, as required by most existing approaches. Second, we introduce an efficient pose tracking strategy to deal with sequential depth data, where the major challenge is the incomplete data due to self-occlusions and view changes. We introduce a visible point extraction method to initialize a new template for the current frame from the previous frame, which effectively reduces the ambiguity and uncertainty during registration. Third, to support robust and stable pose tracking, we develop a segment volume validation technique to detect tracking failures and to re-initialize pose registration if needed. The experimental results on both benchmark 3D laser scan and depth datasets demonstrate the effectiveness of the proposed framework when compared with state-of-the-art algorithms. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1913 KiB

Open AccessArticle

A Novel 2D-to-3D Video Conversion Method Using Time-Coherent Depth Maps

by Shouyi Yin^*, Hao Dong, Guangli Jiang, Leibo Liu and Shaojun Wei

Institute of Microelectronics, Tsinghua University, Beijing 100084, China

Sensors 2015, 15(7), 15246-15264; https://doi.org/10.3390/s150715246 - 29 Jun 2015

Cited by 9 | Viewed by 8258

Abstract

In this paper, we propose a novel 2D-to-3D video conversion method for 3D entertainment applications. 3D entertainment is getting more and more popular and can be found in many contexts, such as TV and home gaming equipment. 3D image sensors are a new [...] Read more.

In this paper, we propose a novel 2D-to-3D video conversion method for 3D entertainment applications. 3D entertainment is getting more and more popular and can be found in many contexts, such as TV and home gaming equipment. 3D image sensors are a new method to produce stereoscopic video content conveniently and at a low cost, and can thus meet the urgent demand for 3D videos in the 3D entertaiment market. Generally, 2D image sensor and 2D-to-3D conversion chip can compose a 3D image sensor. Our study presents a novel 2D-to-3D video conversion algorithm which can be adopted in a 3D image sensor. In our algorithm, a depth map is generated by combining global depth gradient and local depth refinement for each frame of 2D video input. Global depth gradient is computed according to image type while local depth refinement is related to color information. As input 2D video content consists of a number of video shots, the proposed algorithm reuses the global depth gradient of frames within the same video shot to generate time-coherent depth maps. The experimental results prove that this novel method can adapt to different image types, reduce computational complexity and improve the temporal smoothness of generated 3D video. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 349 KiB

Open AccessArticle

Coded Cooperation for Multiway Relaying in Wireless Sensor Networks

by Zhongwei Si^1,*, Junyang Ma¹ and Ragnar Thobaben²

¹ Key Lab of Universal Wireless Communications, Ministry of Education, Beijing University of Posts and Telecommunications (BUPT), 100876 Beijing, China

² School of Electrical Engineering and ACCESS Linnaeus Center, KTH Royal Institute of Technology, 10044 Stockholm, Sweden

Sensors 2015, 15(7), 15265-15284; https://doi.org/10.3390/s150715265 - 29 Jun 2015

Cited by 2 | Viewed by 5228

Abstract

Wireless sensor networks have been considered as an enabling technology for constructing smart cities. One important feature of wireless sensor networks is that the sensor nodes collaborate in some manner for communications. In this manuscript, we focus on the model of multiway relaying [...] Read more.

Wireless sensor networks have been considered as an enabling technology for constructing smart cities. One important feature of wireless sensor networks is that the sensor nodes collaborate in some manner for communications. In this manuscript, we focus on the model of multiway relaying with full data exchange where each user wants to transmit and receive data to and from all other users in the network. We derive the capacity region for this specific model and propose a coding strategy through coset encoding. To obtain good performance with practical codes, we choose spatially-coupled LDPC (SC-LDPC) codes for the coded cooperation. In particular, for the message broadcasting from the relay, we construct multi-edge-type (MET) SC-LDPC codes by repeatedly applying coset encoding. Due to the capacity-achieving property of the SC-LDPC codes, we prove that the capacity region can theoretically be achieved by the proposed MET SC-LDPC codes. Numerical results with finite node degrees are provided, which show that the achievable rates approach the boundary of the capacity region in both binary erasure channels and additive white Gaussian channels. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 607 KiB

Open AccessArticle

Location Privacy for Mobile Crowd Sensing through Population Mapping

by Minho Shin^1,*, Cory Cornelius², Apu Kapadia³, Nikos Triandopoulos⁴ and David Kotz⁵

¹ Myongji University, Myongjiro 116, Yongin 449-728, Korea

² Intel Labs, Hillsboro, OR 97124, USA

³ Indiana University, Bloomington, IN 47408, USA

⁴ Boston University, 111 Cummington Mall, Boston, MA 02215, USA

⁵ Dartmouth College, Hanover, NH 03755, USA

Sensors 2015, 15(7), 15285-15310; https://doi.org/10.3390/s150715285 - 29 Jun 2015

Cited by 18 | Viewed by 8275

Abstract

Opportunistic sensing allows applications to “task” mobile devices to measure context in a target region. For example, one could leverage sensor-equipped vehicles to measure traffic or pollution levels on a particular street or users’ mobile phones to locate (Bluetooth-enabled) objects in their vicinity. [...] Read more.

Opportunistic sensing allows applications to “task” mobile devices to measure context in a target region. For example, one could leverage sensor-equipped vehicles to measure traffic or pollution levels on a particular street or users’ mobile phones to locate (Bluetooth-enabled) objects in their vicinity. In most proposed applications, context reports include the time and location of the event, putting the privacy of users at increased risk: even if identifying information has been removed from a report, the accompanying time and location can reveal sufficient information to de-anonymize the user whose device sent the report. We propose and evaluate a novel spatiotemporal blurring mechanism based on tessellation and clustering to protect users’ privacy against the system while reporting context. Our technique employs a notion of probabilistic k-anonymity; it allows users to perform local blurring of reports efficiently without an online anonymization server before the data are sent to the system. The proposed scheme can control the degree of certainty in location privacy and the quality of reports through a system parameter. We outline the architecture and security properties of our approach and evaluate our tessellation and clustering algorithm against real mobility traces. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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15 pages, 1233 KiB

Open AccessArticle

Sensorless FOC Performance Improved with On-Line Speed and Rotor Resistance Estimator Based on an Artificial Neural Network for an Induction Motor Drive

by Jose M. Gutierrez-Villalobos^*, Juvenal Rodriguez-Resendiz

, Edgar A. Rivas-Araiza and Moisés A. Martínez-Hernández

Laboratorio de Mecatrónica, Universidad Autónoma de Querétaro, Cerro de las Campanas, Col. Las Campanas, S/N, Queretaro 76010, Mexico

Sensors 2015, 15(7), 15311-15325; https://doi.org/10.3390/s150715311 - 29 Jun 2015

Cited by 14 | Viewed by 8722

Abstract

Three-phase induction motor drive requires high accuracy in high performance processes in industrial applications. Field oriented control, which is one of the most employed control schemes for induction motors, bases its function on the electrical parameter estimation coming from the motor. These parameters [...] Read more.

Three-phase induction motor drive requires high accuracy in high performance processes in industrial applications. Field oriented control, which is one of the most employed control schemes for induction motors, bases its function on the electrical parameter estimation coming from the motor. These parameters make an electrical machine driver work improperly, since these electrical parameter values change at low speeds, temperature changes, and especially with load and duty changes. The focus of this paper is the real-time and on-line electrical parameters with a CMAC-ADALINE block added in the standard FOC scheme to improve the IM driver performance and endure the driver and the induction motor lifetime. Two kinds of neural network structures are used; one to estimate rotor speed and the other one to estimate rotor resistance of an induction motor. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 7232 KiB

Open AccessArticle

A Novel Machine Vision System for the Inspection of Micro-Spray Nozzle

by Kuo-Yi Huang^1,* and Yu-Ting Ye²

¹ Department of Bio-Industrial Mechatronics Engineering, National Chung Hsing University, Tai-Chung 402, Taiwan

² Department of Mechatronic Engineering, Huafan University, New Taipei City 223, Taiwan

Sensors 2015, 15(7), 15326-15338; https://doi.org/10.3390/s150715326 - 29 Jun 2015

Cited by 14 | Viewed by 6333

Abstract

In this study, we present an application of neural network and image processing techniques for detecting the defects of an internal micro-spray nozzle. The defect regions were segmented by Canny edge detection, a randomized algorithm for detecting circles and a circle inspection (CI) [...] Read more.

In this study, we present an application of neural network and image processing techniques for detecting the defects of an internal micro-spray nozzle. The defect regions were segmented by Canny edge detection, a randomized algorithm for detecting circles and a circle inspection (CI) algorithm. The gray level co-occurrence matrix (GLCM) was further used to evaluate the texture features of the segmented region. These texture features (contrast, entropy, energy), color features (mean and variance of gray level) and geometric features (distance variance, mean diameter and diameter ratio) were used in the classification procedures. A back-propagation neural network classifier was employed to detect the defects of micro-spray nozzles. The methodology presented herein effectively works for detecting micro-spray nozzle defects to an accuracy of 90.71%. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 4493 KiB

Open AccessArticle

A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension

by Jincheng Li¹, Jie Chen¹, Wei Liu²

, Pengbo Wang^1,* and Chunsheng Li¹

¹ School of Electronic and Information Engineering, Beihang University, Beijing 100191, China

² Electronic and Electronic Engineering Department, University of Sheffield, Sheffield S1-3JD, UK

Sensors 2015, 15(7), 15339-15362; https://doi.org/10.3390/s150715339 - 29 Jun 2015

Cited by 18 | Viewed by 6374

Abstract

The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the [...] Read more.

The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus)-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach. Full article

(This article belongs to the Section Remote Sensors)

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21 pages, 619 KiB

Open AccessArticle

Diversity Performance Analysis on Multiple HAP Networks

by Feihong Dong^1,2,*, Min Li², Xiangwu Gong^1,2, Hongjun Li^1,2 and Fengyue Gao^1,2

¹ College of Communications Engineering, PLA University of Science and Technology, 88 Houbiaoying Rd., Nanjing 210007, China

² Institute of China Electronic System Engineering Corporation, 13 Dacheng Rd., Beijing 100141, China

Sensors 2015, 15(7), 15398-15418; https://doi.org/10.3390/s150715398 - 30 Jun 2015

Cited by 24 | Viewed by 6642

Abstract

One of the main design challenges in wireless sensor networks (WSNs) is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP) is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO) techniques provide the [...] Read more.

One of the main design challenges in wireless sensor networks (WSNs) is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP) is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO) techniques provide the diversity and multiplexing gain, which can improve the network performance effectively. In this paper, a virtual MIMO (V-MIMO) model is proposed by networking multiple HAPs with the concept of multiple assets in view (MAV). In a shadowed Rician fading channel, the diversity performance is investigated. The probability density function (PDF) and cumulative distribution function (CDF) of the received signal-to-noise ratio (SNR) are derived. In addition, the average symbol error rate (ASER) with BPSK and QPSK is given for the V-MIMO model. The system capacity is studied for both perfect channel state information (CSI) and unknown CSI individually. The ergodic capacity with various SNR and Rician factors for different network configurations is also analyzed. The simulation results validate the effectiveness of the performance analysis. It is shown that the performance of the HAPs network in WSNs can be significantly improved by utilizing the MAV to achieve overlapping coverage, with the help of the V-MIMO techniques. Full article

(This article belongs to the Section Sensor Networks)

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24 pages, 2180 KiB

Open AccessArticle

Robust and Accurate Modeling Approaches for Migraine Per-Patient Prediction from Ambulatory Data

by Josué Pagán^1,2,*, M. Irene De Orbe², Ana Gago³, Mónica Sobrado³, José L. Risco-Martín¹, J. Vivancos Mora³, José M. Moya² and José L. Ayala¹

¹ Computer Architecture and Automation Department, Complutense University of Madrid, Madrid 28040, Spain

² Electronic Engineering Department, Technical University of Madrid, Madrid 28040, Spain

³ Neurology Service, Sanitary Research Institute, University Hospital La Princesa, Madrid 28006, Spain

Sensors 2015, 15(7), 15419-15442; https://doi.org/10.3390/s150715419 - 30 Jun 2015

Cited by 38 | Viewed by 11683

Abstract

Migraine is one of the most wide-spread neurological disorders, and its medical treatment represents a high percentage of the costs of health systems. In some patients, characteristic symptoms that precede the headache appear. However, they are nonspecific, and their prediction horizon is unknown [...] Read more.

Migraine is one of the most wide-spread neurological disorders, and its medical treatment represents a high percentage of the costs of health systems. In some patients, characteristic symptoms that precede the headache appear. However, they are nonspecific, and their prediction horizon is unknown and pretty variable; hence, these symptoms are almost useless for prediction, and they are not useful to advance the intake of drugs to be effective and neutralize the pain. To solve this problem, this paper sets up a realistic monitoring scenario where hemodynamic variables from real patients are monitored in ambulatory conditions with a wireless body sensor network (WBSN). The acquired data are used to evaluate the predictive capabilities and robustness against noise and failures in sensors of several modeling approaches. The obtained results encourage the development of per-patient models based on state-space models (N4SID) that are capable of providing average forecast windows of 47 min and a low rate of false positives. Full article

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

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25 pages, 773 KiB

Open AccessArticle

On the Design of Smart Parking Networks in the Smart Cities: An Optimal Sensor Placement Model

by Antoine Bagula^1,*, Lorenzo Castelli²

and Marco Zennaro³

¹ Intelligent Systems and Advanced Telecommunication Laboratory Laboratory, Department of Computer Science, University of the Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa

² Dipartimento di Ingegneria e Architettura, Università degli Studi di Trieste, Via A.Valerio 10, 34127 Trieste, Italy

³ ICT4D Laboratory, The Abdus Salam International Centre for Theoretical Physics, Via Beirut 7, 34151 Trieste, Italy

Sensors 2015, 15(7), 15443-15467; https://doi.org/10.3390/s150715443 - 30 Jun 2015

Cited by 117 | Viewed by 23909

Abstract

Smart parking is a typical IoT application that can benefit from advances in sensor, actuator and RFID technologies to provide many services to its users and parking owners of a smart city. This paper considers a smart parking infrastructure where sensors are laid [...] Read more.

Smart parking is a typical IoT application that can benefit from advances in sensor, actuator and RFID technologies to provide many services to its users and parking owners of a smart city. This paper considers a smart parking infrastructure where sensors are laid down on the parking spots to detect car presence and RFID readers are embedded into parking gates to identify cars and help in the billing of the smart parking. Both types of devices are endowed with wired and wireless communication capabilities for reporting to a gateway where the situation recognition is performed. The sensor devices are tasked to play one of the three roles: (1) slave sensor nodes located on the parking spot to detect car presence/absence; (2) master nodes located at one of the edges of a parking lot to detect presence and collect the sensor readings from the slave nodes; and (3) repeater sensor nodes, also called “anchor” nodes, located strategically at specific locations in the parking lot to increase the coverage and connectivity of the wireless sensor network. While slave and master nodes are placed based on geographic constraints, the optimal placement of the relay/anchor sensor nodes in smart parking is an important parameter upon which the cost and efficiency of the parking system depends. We formulate the optimal placement of sensors in smart parking as an integer linear programming multi-objective problem optimizing the sensor network engineering efficiency in terms of coverage and lifetime maximization, as well as its economic gain in terms of the number of sensors deployed for a specific coverage and lifetime. We propose an exact solution to the node placement problem using single-step and two-step solutions implemented in the Mosel language based on the Xpress-MPsuite of libraries. Experimental results reveal the relative efficiency of the single-step compared to the two-step model on different performance parameters. These results are consolidated by simulation results, which reveal that our solution outperforms a random placement in terms of both energy consumption, delay and throughput achieved by a smart parking network. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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10 pages, 3155 KiB

Open AccessArticle

Highly Sensitive H₂S Sensor Based on the Metal-Catalyzed SnO₂ Nanocolumns Fabricated by Glancing Angle Deposition

by Kwang Soo Yoo^1,*,†, Soo Deok Han^2,3,†

, Hi Gyu Moon², Seok-Jin Yoon² and Chong-Yun Kang^2,3,*

¹ Department of Materials Science and Engineering, University of Seoul, 163, Seoulsiripdae-ro, Dongdaemun-gu, Seoul 130-743, Korea

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

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

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 15468-15477; https://doi.org/10.3390/s150715468 - 30 Jun 2015

Cited by 48 | Viewed by 7100

Abstract

As highly sensitive H₂S gas sensors, Au- and Ag-catalyzed SnO₂ thin films with morphology-controlled nanostructures were fabricated by using e-beam evaporation in combination with the glancing angle deposition (GAD) technique. After annealing at 500 °C for 40 h, the sensors [...] Read more.

As highly sensitive H₂S gas sensors, Au- and Ag-catalyzed SnO₂ thin films with morphology-controlled nanostructures were fabricated by using e-beam evaporation in combination with the glancing angle deposition (GAD) technique. After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure. The gas sensitivities (S = R_gas/R_air) of Au and Ag-catalyzed SnO₂ sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H₂S at 300 °C, and the 90% response time was approximately 5 s. These sensors showed excellent sensitivities compared with the SnO₂ thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48). Full article

(This article belongs to the Special Issue Gas Sensors—Designs and Applications)

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16 pages, 1204 KiB

Open AccessArticle

GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling

by Fuhong Wang, Xinghan Chen^* and Fei Guo^*

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

Sensors 2015, 15(7), 15478-15493; https://doi.org/10.3390/s150715478 - 30 Jun 2015

Cited by 11 | Viewed by 6606

Abstract

Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate [...] Read more.

Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1–7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%–40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 3065 KiB

Open AccessArticle

UAV-Based Photogrammetry and Integrated Technologies for Architectural Applications—Methodological Strategies for the After-Quake Survey of Vertical Structures in Mantua (Italy)

by Cristiana Achille, Andrea Adami, Silvia Chiarini, Stefano Cremonesi, Francesco Fassi

, Luigi Fregonese^* and Laura Taffurelli

Department of Architecture, Built Environment and Construction Engineering, ABC, Politecnico di Milano, via Ponzio, Milano 31-20133, Italy

Sensors 2015, 15(7), 15520-15539; https://doi.org/10.3390/s150715520 - 30 Jun 2015

Cited by 157 | Viewed by 13438

Abstract

This paper examines the survey of tall buildings in an emergency context like in the case of post-seismic events. The after-earthquake survey has to guarantee time-savings, high precision and security during the operational stages. The main goal is to optimize the application of [...] Read more.

This paper examines the survey of tall buildings in an emergency context like in the case of post-seismic events. The after-earthquake survey has to guarantee time-savings, high precision and security during the operational stages. The main goal is to optimize the application of methodologies based on acquisition and automatic elaborations of photogrammetric data even with the use of Unmanned Aerial Vehicle (UAV) systems in order to provide fast and low cost operations. The suggested methods integrate new technologies with commonly used technologies like TLS and topographic acquisition. The value of the photogrammetric application is demonstrated by a test case, based on the comparison of acquisition, calibration and 3D modeling results in case of use of a laser scanner, metric camera and amateur reflex camera. The test would help us to demonstrate the efficiency of image based methods in the acquisition of complex architecture. The case study is Santa Barbara Bell tower in Mantua. The applied survey solution allows a complete 3D database of the complex architectural structure to be obtained for the extraction of all the information needed for significant intervention. This demonstrates the applicability of the photogrammetry using UAV for the survey of vertical structures, complex buildings and difficult accessible architectural parts, providing high precision results. Full article

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

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22 pages, 2695 KiB

Open AccessArticle

Improving Localization Accuracy: Successive Measurements Error Modeling

by Najah Abu Ali^1,* and Mervat Abu-Elkheir²

¹ College of Information Technology, United Arab Emirates University, Al-Ain 15551, Abu Dhabi

² Faculty of Computer and Information Sciences, Mansoura University, Mansoura 35516, Egypt

Sensors 2015, 15(7), 15540-15561; https://doi.org/10.3390/s150715540 - 1 Jul 2015

Cited by 9 | Viewed by 6596

Abstract

Vehicle self-localization is an essential requirement for many of the safety applications envisioned for vehicular networks. The mathematical models used in current vehicular localization schemes focus on modeling the localization error itself, and overlook the potential correlation between successive localization measurement errors. In [...] Read more.

Vehicle self-localization is an essential requirement for many of the safety applications envisioned for vehicular networks. The mathematical models used in current vehicular localization schemes focus on modeling the localization error itself, and overlook the potential correlation between successive localization measurement errors. In this paper, we first investigate the existence of correlation between successive positioning measurements, and then incorporate this correlation into the modeling positioning error. We use the Yule Walker equations to determine the degree of correlation between a vehicle’s future position and its past positions, and then propose a -order Gauss–Markov model to predict the future position of a vehicle from its past positions. We investigate the existence of correlation for two datasets representing the mobility traces of two vehicles over a period of time. We prove the existence of correlation between successive measurements in the two datasets, and show that the time correlation between measurements can have a value up to four minutes. Through simulations, we validate the robustness of our model and show that it is possible to use the first-order Gauss–Markov model, which has the least complexity, and still maintain an accurate estimation of a vehicle’s future location over time using only its current position. Our model can assist in providing better modeling of positioning errors and can be used as a prediction tool to improve the performance of classical localization algorithms such as the Kalman filter. Full article

(This article belongs to the Special Issue Sensors in New Road Vehicles)

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16 pages, 1194 KiB

Open AccessArticle

A Sensitive and Selective Label-Free Electrochemical DNA Biosensor for the Detection of Specific Dengue Virus Serotype 3 Sequences

by Natália Oliveira^1,*, Elaine Souza², Danielly Ferreira¹, Deborah Zanforlin¹, Wessulla Bezerra¹, Maria Amélia Borba¹, Mariana Arruda¹, Kennya Lopes³, Gustavo Nascimento¹, Danyelly Martins^1,4, Marli Cordeiro⁴ and José Lima-Filho^1,4

¹ Laboratório de Imunopatologia Keizo Asami (LIKA), Universidade Federal de Pernambuco-UFPE, Av. Prof. Moraes Rego, s/n, Campus da UFPE, 50670-901 Recife, PE, Brazil

² Universidade Federal de Alagoas (UFAL), Campus Arapiraca, Av. Manoel Severino Barbosa, s/n, Bom Sucesso, 57.309-005 Arapiraca, AL, Brazil

³ Departamento de Virologia e Terapia Experimental (LAVITE), Centro de Pesquisas Aggeu Magalhães (CPqAM), Fundação Oswaldo Cruz (Fiocruz)—Pernambuco, Av. Professor Moraes Rego, s/n, Campus da UFPE, 50.670-420 Recife, PE, Brazil

⁴ Departamento de Bioquímica, Universidade Federal de Pernambuco-UFPE, Av. Professor Moraes Rego, s/n, Campus da UFPE, CEP: 50670-901 Recife, PE, Brazil

Sensors 2015, 15(7), 15562-15577; https://doi.org/10.3390/s150715562 - 1 Jul 2015

Cited by 70 | Viewed by 14130

Abstract

Dengue fever is the most prevalent vector-borne disease in the world, with nearly 100 million people infected every year. Early diagnosis and identification of the pathogen are crucial steps for the treatment and for prevention of the disease, mainly in areas where the [...] Read more.

Dengue fever is the most prevalent vector-borne disease in the world, with nearly 100 million people infected every year. Early diagnosis and identification of the pathogen are crucial steps for the treatment and for prevention of the disease, mainly in areas where the co-circulation of different serotypes is common, increasing the outcome of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Due to the lack of fast and inexpensive methods available for the identification of dengue serotypes, herein we report the development of an electrochemical DNA biosensor for the detection of sequences of dengue virus serotype 3 (DENV-3). DENV-3 probe was designed using bioinformatics software and differential pulse voltammetry (DPV) was used for electrochemical analysis. The results showed that a 22-m sequence was the best DNA probe for the identification of DENV-3. The optimum concentration of the DNA probe immobilized onto the electrode surface is 500 nM and a low detection limit of the system (3.09 nM). Moreover, this system allows selective detection of DENV-3 sequences in buffer and human serum solutions. Therefore, the application of DNA biosensors for diagnostics at the molecular level may contribute to future advances in the implementation of specific, effective and rapid detection methods for the diagnosis dengue viruses. Full article

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

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17 pages, 3063 KiB

Open AccessArticle

Spectral and Image Integrated Analysis of Hyperspectral Data for Waxy Corn Seed Variety Classification

by Xiaoling Yang, Hanmei Hong, Zhaohong You and Fang Cheng^*

College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China

Sensors 2015, 15(7), 15578-15594; https://doi.org/10.3390/s150715578 - 1 Jul 2015

Cited by 125 | Viewed by 11455

Abstract

The purity of waxy corn seed is a very important index of seed quality. A novel procedure for the classification of corn seed varieties was developed based on the combined spectral, morphological, and texture features extracted from visible and near-infrared (VIS/NIR) hyperspectral images. [...] Read more.

The purity of waxy corn seed is a very important index of seed quality. A novel procedure for the classification of corn seed varieties was developed based on the combined spectral, morphological, and texture features extracted from visible and near-infrared (VIS/NIR) hyperspectral images. For the purpose of exploration and comparison, images of both sides of corn kernels (150 kernels of each variety) were captured and analyzed. The raw spectra were preprocessed with Savitzky-Golay (SG) smoothing and derivation. To reduce the dimension of spectral data, the spectral feature vectors were constructed using the successive projections algorithm (SPA). Five morphological features (area, circularity, aspect ratio, roundness, and solidity) and eight texture features (energy, contrast, correlation, entropy, and their standard deviations) were extracted as appearance character from every corn kernel. Support vector machines (SVM) and a partial least squares–discriminant analysis (PLS-DA) model were employed to build the classification models for seed varieties classification based on different groups of features. The results demonstrate that combining spectral and appearance characteristic could obtain better classification results. The recognition accuracy achieved in the SVM model (98.2% and 96.3% for germ side and endosperm side, respectively) was more satisfactory than in the PLS-DA model. This procedure has the potential for use as a new method for seed purity testing. Full article

(This article belongs to the Special Issue Agriculture and Forestry: Sensors, Technologies and Procedures)

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16 pages, 1708 KiB

Open AccessArticle

Assigning Main Orientation to an EOH Descriptor on Multispectral Images

by Yong Li^1,*, Xiang Shi¹, Lijun Wei¹, Junwei Zou¹ and Fang Chen²

¹ Beijing University of Posts and Teles., School of Electronic Engineering, Rd. Xitucheng 10#, Beijing 100876, China

² Beijing Anzhen Hospital, Capital Medical University and Beijing Institute of Heart Lung and BloodVessel Disease, Beijing 100029, China

Sensors 2015, 15(7), 15595-15610; https://doi.org/10.3390/s150715595 - 1 Jul 2015

Cited by 11 | Viewed by 5085

Abstract

This paper proposes an approach to compute an EOH (edge-oriented histogram) descriptor with main orientation. EOH has a better matching ability than SIFT (scale-invariant feature transform) on multispectral images, but does not assign a main orientation to keypoints. Alternatively, it tends to assign [...] Read more.

This paper proposes an approach to compute an EOH (edge-oriented histogram) descriptor with main orientation. EOH has a better matching ability than SIFT (scale-invariant feature transform) on multispectral images, but does not assign a main orientation to keypoints. Alternatively, it tends to assign the same main orientation to every keypoint, e.g., zero degrees. This limits EOH to matching keypoints between images of translation misalignment only. Observing this limitation, we propose assigning to keypoints the main orientation that is computed with PIIFD (partial intensity invariant feature descriptor). In the proposed method, SIFT keypoints are detected from images as the extrema of difference of Gaussians, and every keypoint is assigned to the main orientation computed with PIIFD. Then, EOH is computed for every keypoint with respect to its main orientation. In addition, an implementation variant is proposed for fast computation of the EOH descriptor. Experimental results show that the proposed approach performs more robustly than the original EOH on image pairs that have a rotation misalignment. Full article

(This article belongs to the Section Remote Sensors)

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29 pages, 1825 KiB

Open AccessArticle

Preserving Smart Objects Privacy through Anonymous and Accountable Access Control for a M2M-Enabled Internet of Things

by José L. Hernández-Ramos^*, Jorge Bernal Bernabe

, M. Victoria Moreno and Antonio F. Skarmeta

Department of Information and Communications Engineering, Computer Science Faculty, University of Murcia, Murcia 30100, Spain

Sensors 2015, 15(7), 15611-15639; https://doi.org/10.3390/s150715611 - 1 Jul 2015

Cited by 19 | Viewed by 7409

Abstract

As we get into the Internet of Things era, security and privacy concerns remain as the main obstacles in the development of innovative and valuable services to be exploited by society. Given the Machine-to-Machine (M2M) nature of these emerging scenarios, the application of [...] Read more.

As we get into the Internet of Things era, security and privacy concerns remain as the main obstacles in the development of innovative and valuable services to be exploited by society. Given the Machine-to-Machine (M2M) nature of these emerging scenarios, the application of current privacy-friendly technologies needs to be reconsidered and adapted to be deployed in such global ecosystem. This work proposes different privacy-preserving mechanisms through the application of anonymous credential systems and certificateless public key cryptography. The resulting alternatives are intended to enable an anonymous and accountable access control approach to be deployed on large-scale scenarios, such as Smart Cities. Furthermore, the proposed mechanisms have been deployed on constrained devices, in order to assess their suitability for a secure and privacy-preserving M2M-enabled Internet of Things. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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21 pages, 652 KiB

Open AccessArticle

A Software Product Line Process to Develop Agents for the IoT

by Inmaculada Ayala^*

, Mercedes Amor, Lidia Fuentes and José M. Troya

Departamento de Lenguajes y Ciencias de la Computación, Andalucía Tech, Universidad de Málaga, Campus de Teatinos s/n, 29071 Málaga, Spain

Sensors 2015, 15(7), 15640-15660; https://doi.org/10.3390/s150715640 - 1 Jul 2015

Cited by 37 | Viewed by 7374

Abstract

One of the most important challenges of this decade is the Internet of Things (IoT), which aims to enable things to be connected anytime, anyplace, with anything and anyone, ideally using any path/network and any service. IoT systems are usually composed of heterogeneous [...] Read more.

One of the most important challenges of this decade is the Internet of Things (IoT), which aims to enable things to be connected anytime, anyplace, with anything and anyone, ideally using any path/network and any service. IoT systems are usually composed of heterogeneous and interconnected lightweight devices that support applications that are subject to change in their external environment and in the functioning of these devices. The management of the variability of these changes, autonomously, is a challenge in the development of these systems. Agents are a good option for developing self-managed IoT systems due to their distributed nature, context-awareness and self-adaptation. Our goal is to enhance the development of IoT applications using agents and software product lines (SPL). Specifically, we propose to use Self-StarMASMAS, multi-agent system) agents and to define an SPL process using the Common Variability Language. In this contribution, we propose an SPL process for Self-StarMAS, paying particular attention to agents embedded in sensor motes. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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23 pages, 2299 KiB

Open AccessArticle

New Hybrid Algorithms for Estimating Tree Stem Diameters at Breast Height Using a Two Dimensional Terrestrial Laser Scanner

by Jianlei Kong, Xiaokang Ding, Jinhao Liu^*, Lei Yan^* and Jianli Wang

School of Technology, Beijing Forestry University, Beijing 100083, China

Sensors 2015, 15(7), 15661-15683; https://doi.org/10.3390/s150715661 - 2 Jul 2015

Cited by 13 | Viewed by 5760

Abstract

In this paper, a new algorithm to improve the accuracy of estimating diameter at breast height (DBH) for tree trunks in forest areas is proposed. First, the information is collected by a two-dimensional terrestrial laser scanner (2DTLS), which emits laser pulses to generate [...] Read more.

In this paper, a new algorithm to improve the accuracy of estimating diameter at breast height (DBH) for tree trunks in forest areas is proposed. First, the information is collected by a two-dimensional terrestrial laser scanner (2DTLS), which emits laser pulses to generate a point cloud. After extraction and filtration, the laser point clusters of the trunks are obtained, which are optimized by an arithmetic means method. Then, an algebraic circle fitting algorithm in polar form is non-linearly optimized by the Levenberg-Marquardt method to form a new hybrid algorithm, which is used to acquire the diameters and positions of the trees. Compared with previous works, this proposed method improves the accuracy of diameter estimation of trees significantly and effectively reduces the calculation time. Moreover, the experimental results indicate that this method is stable and suitable for the most challenging conditions, which has practical significance in improving the operating efficiency of forest harvester and reducing the risk of causing accidents. Full article

(This article belongs to the Section Remote Sensors)

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21 pages, 5481 KiB

Open AccessArticle

UAV Deployment Exercise for Mapping Purposes: Evaluation of Emergency Response Applications

by Piero Boccardo¹, Filiberto Chiabrando^2,*, Furio Dutto³, Fabio Giulio Tonolo⁴ and Andrea Lingua²

¹ Politecnico di Torino—Interuniversity Department of Regional and Urban Studies and Planning (DIST), Viale Mattioli 39, 10125 Torino, Italy

² Politecnico di Torino—Department of Environment, Land and Infrastructure Engineering (DIATI), C.so Duca degli Abruzzi 24, 10129 Torino, Italy

³ Città Metropolitana di Torino—Servizio Protezione Civile, Via Alberto Sordi 13, 10095 Grugliasco (TO), Italy

⁴ Information Technology for Humanitarian Assistance, cooperation and Action (ITHACA), Via P.C. Boggio 31, 10138 Torino, Italy

Sensors 2015, 15(7), 15717-15737; https://doi.org/10.3390/s150715717 - 2 Jul 2015

Cited by 148 | Viewed by 12201

Abstract

Exploiting the decrease of costs related to UAV technology, the humanitarian community started piloting the use of similar systems in humanitarian crises several years ago in different application fields, i.e., disaster mapping and information gathering, community capacity building, logistics and even transportation [...] Read more.

Exploiting the decrease of costs related to UAV technology, the humanitarian community started piloting the use of similar systems in humanitarian crises several years ago in different application fields, i.e., disaster mapping and information gathering, community capacity building, logistics and even transportation of goods. Part of the author’s group, composed of researchers in the field of applied geomatics, has been piloting the use of UAVs since 2006, with a specific focus on disaster management application. In the framework of such activities, a UAV deployment exercise was jointly organized with the Regional Civil Protection authority, mainly aimed at assessing the operational procedures to deploy UAVs for mapping purposes and the usability of the acquired data in an emergency response context. In the paper the technical features of the UAV platforms will be described, comparing the main advantages/disadvantages of fixed-wing versus rotor platforms. The main phases of the adopted operational procedure will be discussed and assessed especially in terms of time required to carry out each step, highlighting potential bottlenecks and in view of the national regulation framework, which is rapidly evolving. Different methodologies for the processing of the acquired data will be described and discussed, evaluating the fitness for emergency response applications. Full article

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

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17 pages, 4486 KiB

Open AccessArticle

Sorting Olive Batches for the Milling Process Using Image Processing

by Daniel Aguilera Puerto¹, Diego Manuel Martínez Gila^2,*

, Javier Gámez García² and Juan Gómez Ortega²

¹ ANDALTEC, Plastic Technological Center, Martos, Jaén 23600, Spain

² Group of Robotics, Automation and Computer Vision, University of Jaén, Agrifood Campus of International Excellence (ceiA3), Jaén 23071, Spain

Sensors 2015, 15(7), 15738-15754; https://doi.org/10.3390/s150715738 - 2 Jul 2015

Cited by 38 | Viewed by 7385

Abstract

The quality of virgin olive oil obtained in the milling process is directly bound to the characteristics of the olives. Hence, the correct classification of the different incoming olive batches is crucial to reach the maximum quality of the oil. The aim of [...] Read more.

The quality of virgin olive oil obtained in the milling process is directly bound to the characteristics of the olives. Hence, the correct classification of the different incoming olive batches is crucial to reach the maximum quality of the oil. The aim of this work is to provide an automatic inspection system, based on computer vision, and to classify automatically different batches of olives entering the milling process. The classification is based on the differentiation between ground and tree olives. For this purpose, three different species have been studied (Picudo, Picual and Hojiblanco). The samples have been obtained by picking the olives directly from the tree or from the ground. The feature vector of the samples has been obtained on the basis of the olive image histograms. Moreover, different image preprocessing has been employed, and two classification techniques have been used: these are discriminant analysis and neural networks. The proposed methodology has been validated successfully, obtaining good classification results. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 2203 KiB

Open AccessArticle

Using Hand Grip Force as a Correlate of Longitudinal Acceleration Comfort for Rapid Transit Trains

by Beiyuan Guo^*, Weide Gan and Weining Fang

State Key Laboratory of Rail Trafﬁc Control and Safety, Beijing Jiaotong University, No.3 Shang Yuan Cun, Beijing 100044, China

Sensors 2015, 15(7), 15755-15771; https://doi.org/10.3390/s150715755 - 2 Jul 2015

Cited by 5 | Viewed by 5393

Abstract

Longitudinal acceleration comfort is one of the essential metrics used to evaluate the ride comfort of train. The aim of this study was to investigate the effectiveness of using hand grip force as a correlate of longitudinal acceleration comfort of rapid transit trains. [...] Read more.

Longitudinal acceleration comfort is one of the essential metrics used to evaluate the ride comfort of train. The aim of this study was to investigate the effectiveness of using hand grip force as a correlate of longitudinal acceleration comfort of rapid transit trains. In the paper, a motion simulation system was set up and a two-stage experiment was designed to investigate the role of the grip force on the longitudinal comfort of rapid transit trains. The results of the experiment show that the incremental grip force was linearly correlated with the longitudinal acceleration value, while the incremental grip force had no correlation with the direction of the longitudinal acceleration vector. The results also show that the effects of incremental grip force and acceleration duration on the longitudinal comfort of rapid transit trains were significant. Based on multiple regression analysis, a step function model was established to predict the longitudinal comfort of rapid transit trains using the incremental grip force and the acceleration duration. The feasibility and practicably of the model was verified by a field test. Furthermore, a comparative analysis shows that the motion simulation system and the grip force based model were valid to support the laboratory studies on the longitudinal comfort of rapid transit trains. Full article

(This article belongs to the Section Physical Sensors)

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27 pages, 2031 KiB

Open AccessArticle

GUDM: Automatic Generation of Unified Datasets for Learning and Reasoning in Healthcare

by Rahman Ali¹, Muhammad Hameed Siddiqi¹, Muhammad Idris¹, Taqdir Ali¹, Shujaat Hussain¹, Eui-Nam Huh¹, Byeong Ho Kang² and Sungyoung Lee^1,*

¹ Department of Computer Engineering, Kyung Hee University, Seocheon-dong, Giheung-gu Yongin-si, Gyeonggi-do 446-701, Korea

² Department of Computing and Information Systems, University of Tasmania, Hobart Tasmania 7005, Australia

Sensors 2015, 15(7), 15772-15798; https://doi.org/10.3390/s150715772 - 2 Jul 2015

Cited by 14 | Viewed by 6861

Abstract

A wide array of biomedical data are generated and made available to healthcare experts. However, due to the diverse nature of data, it is difficult to predict outcomes from it. It is therefore necessary to combine these diverse data sources into a single [...] Read more.

A wide array of biomedical data are generated and made available to healthcare experts. However, due to the diverse nature of data, it is difficult to predict outcomes from it. It is therefore necessary to combine these diverse data sources into a single unified dataset. This paper proposes a global unified data model (GUDM) to provide a global unified data structure for all data sources and generate a unified dataset by a “data modeler” tool. The proposed tool implements user-centric priority based approach which can easily resolve the problems of unified data modeling and overlapping attributes across multiple datasets. The tool is illustrated using sample diabetes mellitus data. The diverse data sources to generate the unified dataset for diabetes mellitus include clinical trial information, a social media interaction dataset and physical activity data collected using different sensors. To realize the significance of the unified dataset, we adopted a well-known rough set theory based rules creation process to create rules from the unified dataset. The evaluation of the tool on six different sets of locally created diverse datasets shows that the tool, on average, reduces 94.1% time efforts of the experts and knowledge engineer while creating unified datasets. Full article

(This article belongs to the Section Physical Sensors)

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31 pages, 14170 KiB

Open AccessArticle

Augmented Robotics Dialog System for Enhancing Human–Robot Interaction

by Fernando Alonso-Martín^*, Aĺvaro Castro-González

, Francisco Javier Fernandez de Gorostiza Luengo and Miguel Ángel Salichs

Robotics Lab, Universidad Carlos III de Madrid, Av. de la Universidad 30, Leganés, Madrid 28911, Spain

Sensors 2015, 15(7), 15799-15829; https://doi.org/10.3390/s150715799 - 3 Jul 2015

Cited by 18 | Viewed by 13642

Abstract

Augmented reality, augmented television and second screen are cutting edge technologies that provide end users extra and enhanced information related to certain events in real time. This enriched information helps users better understand such events, at the same time providing a more satisfactory [...] Read more.

Augmented reality, augmented television and second screen are cutting edge technologies that provide end users extra and enhanced information related to certain events in real time. This enriched information helps users better understand such events, at the same time providing a more satisfactory experience. In the present paper, we apply this main idea to human–robot interaction (HRI), to how users and robots interchange information. The ultimate goal of this paper is to improve the quality of HRI, developing a new dialog manager system that incorporates enriched information from the semantic web. This work presents the augmented robotic dialog system (ARDS), which uses natural language understanding mechanisms to provide two features: (i) a non-grammar multimodal input (verbal and/or written) text; and (ii) a contextualization of the information conveyed in the interaction. This contextualization is achieved by information enrichment techniques that link the extracted information from the dialog with extra information about the world available in semantic knowledge bases. This enriched or contextualized information (information enrichment, semantic enhancement or contextualized information are used interchangeably in the rest of this paper) offers many possibilities in terms of HRI. For instance, it can enhance the robot’s pro-activeness during a human–robot dialog (the enriched information can be used to propose new topics during the dialog, while ensuring a coherent interaction). Another possibility is to display additional multimedia content related to the enriched information on a visual device. This paper describes the ARDS and shows a proof of concept of its applications. Full article

(This article belongs to the Special Issue HCI In Smart Environments)

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23 pages, 7738 KiB

Open AccessArticle

Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity

by Taekjun Oh, Donghwa Lee, Hyungjin Kim and Hyun Myung^*

Urban Robotics Laboratory (URL), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro (373-1 Guseong-dong), Yuseong-gu, Daejeon 305-701, Korea

Sensors 2015, 15(7), 15830-15852; https://doi.org/10.3390/s150715830 - 3 Jul 2015

Cited by 23 | Viewed by 9230

Abstract

Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping) algorithms exploiting a laser scanner may not estimate the robot [...] Read more.

Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping) algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

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15 pages, 1483 KiB

Open AccessArticle

Energy Harvesting from Upper-Limb Pulling Motions for Miniaturized Human-Powered Generators

by Jeongjin Yeo¹, Mun-ho Ryu² and Yoonseok Yang^2,*

¹ Healthcare Engineering, Chonbuk National University, Deokjin-dong Jeonju 664-14, Korea

² Biomedical Engineering, Chonbuk National University, Deokjin-dong Jeonju 664-14, Korea

Sensors 2015, 15(7), 15853-15867; https://doi.org/10.3390/s150715853 - 3 Jul 2015

Cited by 6 | Viewed by 6574

Abstract

The human-powered self-generator provides the best solution for individuals who need an instantaneous power supply for travel, outdoor, and emergency use, since it is less dependent on weather conditions and occupies less space than other renewable power supplies. However, many commercial portable self-generators [...] Read more.

The human-powered self-generator provides the best solution for individuals who need an instantaneous power supply for travel, outdoor, and emergency use, since it is less dependent on weather conditions and occupies less space than other renewable power supplies. However, many commercial portable self-generators that employ hand-cranking are not used as much as expected in daily lives although they have enough output capacity due to their intensive workload. This study proposes a portable human-powered generator which is designed to obtain mechanical energy from an upper limb pulling motion for improved human motion economy as well as efficient human-mechanical power transfer. A coreless axial-flux permanent magnet machine (APMM) and a flywheel magnet rotor were used in conjunction with a one-way clutched power transmission system in order to obtain effective power from the pulling motion. The developed prototype showed an average energy conversion efficiency of 30.98% and an average output power of 0.32 W with a maximum of 1.89 W. Its small form factor (50 mm × 32 mm × 43.5 mm, 0.05 kg) and the substantial electricity produced verify the effectiveness of the proposed method in the utilization of human power. It is expected that the developed generator could provide a mobile power supply. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 903 KiB

Open AccessArticle

A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching

by Xiaoguang Mei¹, Yong Ma^2,*, Chang Li¹, Fan Fan¹, Jun Huang² and Jiayi Ma²

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

² Electronic Information School, Wuhan University, Wuhan 430072, China

Sensors 2015, 15(7), 15868-15887; https://doi.org/10.3390/s150715868 - 3 Jul 2015

Cited by 4 | Viewed by 5307

Abstract

The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for [...] Read more.

The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM), which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 514 KiB

Open AccessArticle

Foot Pose Estimation Using an Inertial Sensor Unit and Two Distance Sensors

by Pham Duy Duong and Young Soo Suh^*

Department of Electrical Engineering, University of Ulsan, Namgu, Ulsan 680-749, Korea

Sensors 2015, 15(7), 15888-15902; https://doi.org/10.3390/s150715888 - 3 Jul 2015

Cited by 27 | Viewed by 6436

Abstract

There are many inertial sensor-based foot pose estimation algorithms. In this paper, we present a methodology to improve the accuracy of foot pose estimation using two low-cost distance sensors (VL6180) in addition to an inertial sensor unit. The distance sensor is a time-of-flight [...] Read more.

There are many inertial sensor-based foot pose estimation algorithms. In this paper, we present a methodology to improve the accuracy of foot pose estimation using two low-cost distance sensors (VL6180) in addition to an inertial sensor unit. The distance sensor is a time-of-flight range finder and can measure distance up to 20 cm. A Kalman filter with 21 states is proposed to estimate both the calibration parameter (relative pose of distance sensors with respect to the inertial sensor unit) and foot pose. Once the calibration parameter is obtained, a Kalman filter with nine states can be used to estimate foot pose. Through four activities (walking, dancing step, ball kicking, jumping), it is shown that the proposed algorithm significantly improves the vertical position estimation. Full article

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

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18 pages, 4222 KiB

Open AccessArticle

An Electromagnetic Sensor with a Metamaterial Lens for Nondestructive Evaluation of Composite Materials

by Adriana Savin^1,*

, Rozina Steigmann^1,2, Alina Bruma^3,4 and Roman Šturm⁵

¹ Nondestructive Testing Department, National Institute of R&D for Technical Physics, 47 D. Mangeron Blvd, 700050 Iasi, Romania

² Faculty of Physics, Alexandru Ioan Cuza University, 11 Carol I Blvd, 700506 Iasi, Romania

³ CRISMAT Laboratory, National Graduate School of Engineering, University of Caen on Normandy, 6 Marechal Juin Blvd, Caen 14050, France

⁴ Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA

⁵ Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia

Sensors 2015, 15(7), 15903-15920; https://doi.org/10.3390/s150715903 - 3 Jul 2015

Cited by 42 | Viewed by 9754

Abstract

This paper proposes the study and implementation of a sensor with a metamaterial (MM) lens in electromagnetic nondestructive evaluation (eNDE). Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR) has been proposed. These structures can serve as electromagnetic [...] Read more.

This paper proposes the study and implementation of a sensor with a metamaterial (MM) lens in electromagnetic nondestructive evaluation (eNDE). Thus, the use of a new type of MM, named Conical Swiss Rolls (CSR) has been proposed. These structures can serve as electromagnetic flux concentrators in the radiofrequency range. As a direct application, plates of composite materials with carbon fibers woven as reinforcement and polyphenylene sulphide as matrix with delaminations due to low energy impacts were examined. The evaluation method is based on the appearance of evanescent modes in the space between carbon fibers when the sample is excited with a transversal magnetic along z axis (TMz) polarized electromagnetic field. The MM lens allows the transmission and intensification of evanescent waves. The characteristics of carbon fibers woven structure became visible and delaminations are clearly emphasized. The flaws can be localized with spatial resolution better than λ/2000. Full article

(This article belongs to the Special Issue Novel Sensors for Non-Destructive Testing and Structural Health Monitoring)

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31 pages, 2599 KiB

Open AccessArticle

H2RM: A Hybrid Rough Set Reasoning Model for Prediction and Management of Diabetes Mellitus

by Rahman Ali, Jamil Hussain

, Muhammad Hameed Siddiqi, Maqbool Hussain and Sungyoung Lee^*

Department of Computer Engineering, Kyung Hee University, Seocheon-dong, Giheung-gu Yongin-si, Gyeonggi-do 446-701, Korea

Sensors 2015, 15(7), 15921-15951; https://doi.org/10.3390/s150715921 - 3 Jul 2015

Cited by 46 | Viewed by 10224

Abstract

Diabetes is a chronic disease characterized by high blood glucose level that results either from a deficiency of insulin produced by the body, or the body’s resistance to the effects of insulin. Accurate and precise reasoning and prediction models greatly help physicians to [...] Read more.

Diabetes is a chronic disease characterized by high blood glucose level that results either from a deficiency of insulin produced by the body, or the body’s resistance to the effects of insulin. Accurate and precise reasoning and prediction models greatly help physicians to improve diagnosis, prognosis and treatment procedures of different diseases. Though numerous models have been proposed to solve issues of diagnosis and management of diabetes, they have the following drawbacks: (1) restricted one type of diabetes; (2) lack understandability and explanatory power of the techniques and decision; (3) limited either to prediction purpose or management over the structured contents; and (4) lack competence for dimensionality and vagueness of patient’s data. To overcome these issues, this paper proposes a novel hybrid rough set reasoning model (H2RM) that resolves problems of inaccurate prediction and management of type-1 diabetes mellitus (T1DM) and type-2 diabetes mellitus (T2DM). For verification of the proposed model, experimental data from fifty patients, acquired from a local hospital in semi-structured format, is used. First, the data is transformed into structured format and then used for mining prediction rules. Rough set theory (RST) based techniques and algorithms are used to mine the prediction rules. During the online execution phase of the model, these rules are used to predict T1DM and T2DM for new patients. Furthermore, the proposed model assists physicians to manage diabetes using knowledge extracted from online diabetes guidelines. Correlation-based trend analysis techniques are used to manage diabetic observations. Experimental results demonstrate that the proposed model outperforms the existing methods with 95.9% average and balanced accuracies. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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22 pages, 1239 KiB

Open AccessArticle

Secure Data Aggregation with Fully Homomorphic Encryption in Large-Scale Wireless Sensor Networks

by Xing Li¹, Dexin Chen², Chunyan Li¹ and Liangmin Wang^1,*

¹ School of Computer Science and Communication Engineering, Jiangsu University, Zhenjiang 212013, China

² College of Computer Science, Sichuan University, Chengdu 610065, China

Sensors 2015, 15(7), 15952-15973; https://doi.org/10.3390/s150715952 - 3 Jul 2015

Cited by 41 | Viewed by 7833

Abstract

With the rapid development of wireless communication technology, sensor technology, information acquisition and processing technology, sensor networks will finally have a deep influence on all aspects of people’s lives. The battery resources of sensor nodes should be managed efficiently in order to prolong [...] Read more.

With the rapid development of wireless communication technology, sensor technology, information acquisition and processing technology, sensor networks will finally have a deep influence on all aspects of people’s lives. The battery resources of sensor nodes should be managed efficiently in order to prolong network lifetime in large-scale wireless sensor networks (LWSNs). Data aggregation represents an important method to remove redundancy as well as unnecessary data transmission and hence cut down the energy used in communication. As sensor nodes are deployed in hostile environments, the security of the sensitive information such as confidentiality and integrity should be considered. This paper proposes Fully homomorphic Encryption based Secure data Aggregation (FESA) in LWSNs which can protect end-to-end data confidentiality and support arbitrary aggregation operations over encrypted data. In addition, by utilizing message authentication codes (MACs), this scheme can also verify data integrity during data aggregation and forwarding processes so that false data can be detected as early as possible. Although the FHE increase the computation overhead due to its large public key size, simulation results show that it is implementable in LWSNs and performs well. Compared with other protocols, the transmitted data and network overhead are reduced in our scheme. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 1829 KiB

Open AccessArticle

Smart City Mobility Application—Gradient Boosting Trees for Mobility Prediction and Analysis Based on Crowdsourced Data

by Ivana Semanjski^*

and Sidharta Gautama

Department of Telecommunications and Information Processing, Gent University, St-Pietersnieuwstraat 41, Gent B-9000, Belgium

Sensors 2015, 15(7), 15974-15987; https://doi.org/10.3390/s150715974 - 3 Jul 2015

Cited by 53 | Viewed by 8893

Abstract

Mobility management represents one of the most important parts of the smart city concept. The way we travel, at what time of the day, for what purposes and with what transportation modes, have a pertinent impact on the overall quality of life in [...] Read more.

Mobility management represents one of the most important parts of the smart city concept. The way we travel, at what time of the day, for what purposes and with what transportation modes, have a pertinent impact on the overall quality of life in cities. To manage this process, detailed and comprehensive information on individuals’ behaviour is needed as well as effective feedback/communication channels. In this article, we explore the applicability of crowdsourced data for this purpose. We apply a gradient boosting trees algorithm to model individuals’ mobility decision making processes (particularly concerning what transportation mode they are likely to use). To accomplish this we rely on data collected from three sources: a dedicated smartphone application, a geographic information systems-based web interface and weather forecast data collected over a period of six months. The applicability of the developed model is seen as a potential platform for personalized mobility management in smart cities and a communication tool between the city (to steer the users towards more sustainable behaviour by additionally weighting preferred suggestions) and users (who can give feedback on the acceptability of the provided suggestions, by accepting or rejecting them, providing an additional input to the learning process). Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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18 pages, 857 KiB

Open AccessArticle

Using Open Geographic Data to Generate Natural Language Descriptions for Hydrological Sensor Networks

by Martin Molina^*

, Javier Sanchez-Soriano and Oscar Corcho

Department of Artificial Intelligence, Technical University of Madrid, Campus de Montegancedo S/N, 28660 Boadilla del Monte, Madrid, Spain

Sensors 2015, 15(7), 16009-16026; https://doi.org/10.3390/s150716009 - 3 Jul 2015

Cited by 5 | Viewed by 5981

Abstract

Providing descriptions of isolated sensors and sensor networks in natural language, understandable by the general public, is useful to help users find relevant sensors and analyze sensor data. In this paper, we discuss the feasibility of using geographic knowledge from public databases available [...] Read more.

Providing descriptions of isolated sensors and sensor networks in natural language, understandable by the general public, is useful to help users find relevant sensors and analyze sensor data. In this paper, we discuss the feasibility of using geographic knowledge from public databases available on the Web (such as OpenStreetMap, Geonames, or DBpedia) to automatically construct such descriptions. We present a general method that uses such information to generate sensor descriptions in natural language. The results of the evaluation of our method in a hydrologic national sensor network showed that this approach is feasible and capable of generating adequate sensor descriptions with a lower development effort compared to other approaches. In the paper we also analyze certain problems that we found in public databases (e.g., heterogeneity, non-standard use of labels, or rigid search methods) and their impact in the generation of sensor descriptions. Full article

(This article belongs to the Section Sensor Networks)

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Graphical abstract

13 pages, 1072 KiB

Open AccessArticle

Optimal Sensor Selection for Classifying a Set of Ginsengs Using Metal-Oxide Sensors

by Jiacheng Miao, Tinglin Zhang, You Wang^* and Guang Li

State Key Laboratory of Industrial Control Technology, Institute of Cyber Systems and Control, Zhejiang University, Hangzhou 310027, Zhejiang, China

Sensors 2015, 15(7), 16027-16039; https://doi.org/10.3390/s150716027 - 3 Jul 2015

Cited by 14 | Viewed by 5066

Abstract

The sensor selection problem was investigated for the application of classification of a set of ginsengs using a metal-oxide sensor-based homemade electronic nose with linear discriminant analysis. Samples (315) were measured for nine kinds of ginsengs using 12 sensors. We investigated the classification [...] Read more.

The sensor selection problem was investigated for the application of classification of a set of ginsengs using a metal-oxide sensor-based homemade electronic nose with linear discriminant analysis. Samples (315) were measured for nine kinds of ginsengs using 12 sensors. We investigated the classification performances of combinations of 12 sensors for the overall discrimination of combinations of nine ginsengs. The minimum numbers of sensors for discriminating each sample set to obtain an optimal classification performance were defined. The relation of the minimum numbers of sensors with number of samples in the sample set was revealed. The results showed that as the number of samples increased, the average minimum number of sensors increased, while the increment decreased gradually and the average optimal classification rate decreased gradually. Moreover, a new approach of sensor selection was proposed to estimate and compare the effective information capacity of each sensor. Full article

(This article belongs to the Section Chemical Sensors)

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20 pages, 627 KiB

Open AccessArticle

Traffic Behavior Recognition Using the Pachinko Allocation Model

by Thien Huynh-The¹, Oresti Banos¹, Ba-Vui Le¹, Dinh-Mao Bui¹, Yongik Yoon² and Sungyoung Lee^1,*

¹ Department of Computer Engineering, Kyung Hee University, Suwon 446-701, Korea

² Department of Multimedia Science, Sookmyung's Women University, Seoul 140-742, Korea

Sensors 2015, 15(7), 16040-16059; https://doi.org/10.3390/s150716040 - 3 Jul 2015

Cited by 9 | Viewed by 7767

Abstract

CCTV-based behavior recognition systems have gained considerable attention in recent years in the transportation surveillance domain for identifying unusual patterns, such as traffic jams, accidents, dangerous driving and other abnormal behaviors. In this paper, a novel approach for traffic behavior modeling is presented [...] Read more.

CCTV-based behavior recognition systems have gained considerable attention in recent years in the transportation surveillance domain for identifying unusual patterns, such as traffic jams, accidents, dangerous driving and other abnormal behaviors. In this paper, a novel approach for traffic behavior modeling is presented for video-based road surveillance. The proposed system combines the pachinko allocation model (PAM) and support vector machine (SVM) for a hierarchical representation and identification of traffic behavior. A background subtraction technique using Gaussian mixture models (GMMs) and an object tracking mechanism based on Kalman filters are utilized to firstly construct the object trajectories. Then, the sparse features comprising the locations and directions of the moving objects are modeled by PAMinto traffic topics, namely activities and behaviors. As a key innovation, PAM captures not only the correlation among the activities, but also among the behaviors based on the arbitrary directed acyclic graph (DAG). The SVM classifier is then utilized on top to train and recognize the traffic activity and behavior. The proposed model shows more flexibility and greater expressive power than the commonly-used latent Dirichlet allocation (LDA) approach, leading to a higher recognition accuracy in the behavior classification. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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23 pages, 1153 KiB

Open AccessArticle

CoAP-Based Mobility Management for the Internet of Things

by Seung-Man Chun

, Hyun-Su Kim and Jong-Tae Park^*

School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 702-701, Korea

Sensors 2015, 15(7), 16060-16082; https://doi.org/10.3390/s150716060 - 3 Jul 2015

Cited by 19 | Viewed by 8958

Abstract

Most of the current mobility management protocols such as Mobile IP and its variants standardized by the IETF may not be suitable to support mobility management for Web-based applications in an Internet of Things (IoT) environment. This is because the sensor nodes have [...] Read more.

Most of the current mobility management protocols such as Mobile IP and its variants standardized by the IETF may not be suitable to support mobility management for Web-based applications in an Internet of Things (IoT) environment. This is because the sensor nodes have limited power capacity, usually operating in sleep/wakeup mode in a constrained wireless network. In addition, sometimes the sensor nodes may act as the server using the CoAP protocol in an IoT environment. This makes it difficult for Web clients to properly retrieve the sensing data from the mobile sensor nodes in an IoT environment. In this article, we propose a mobility management protocol, named CoMP, which can effectively retrieve the sensing data of sensor nodes while they are moving. The salient feature of CoMP is that it makes use of the IETF CoAP protocol for mobility management, instead of using Mobile IP. Thus CoMP can eliminates the additional signaling overhead of Mobile IP, provides reliable mobility management, and prevents the packet loss. CoMP employs a separate location management server to keep track of the location of the mobile sensor nodes. In order to prevent the loss of important sensing data during movement, a holding mode of operation has been introduced. All the signaling procedures including discovery, registration, binding and holding have been designed by extending the IETF CoAP protocol. The numerical analysis and simulation have been done for performance evaluation in terms of the handover latency and packet loss. The results show that the proposed CoMP is superior to previous mobility management protocols, i.e., Mobile IPv4/v6 (MIPv4/v6), Hierarchical Mobile IPv4/v6 (HMIPv4/v6), in terms of the handover latency and packet loss. Full article

(This article belongs to the Special Issue Cyber-Physical Systems)

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22 pages, 12123 KiB

Open AccessArticle

Providing IoT Services in Smart Cities through Dynamic Augmented Reality Markers

by David Chaves-Diéguez^1,*, Alexandre Pellitero-Rivero¹, Daniel García-Coego², Francisco Javier González-Castaño¹, Pedro Salvador Rodríguez-Hernández¹, Óscar Piñeiro-Gómez², Felipe Gil-Castiñeira² and Enrique Costa-Montenegro¹

¹ AtlantTIC, Universidade de Vigo, Rúa Maxwell S/N, 36310 Vigo, Spain

² Galician Research and Development Center in Advanced Telecommunications (GRADIANT), Edif. CITEXVI local 14, Campus Universitario de Vigo, 36310 Vigo, Spain

Sensors 2015, 15(7), 16083-16104; https://doi.org/10.3390/s150716083 - 3 Jul 2015

Cited by 28 | Viewed by 9900

Abstract

Smart cities are expected to improve the quality of life of citizens by relying on new paradigms, such as the Internet of Things (IoT) and its capacity to manage and interconnect thousands of sensors and actuators scattered across the city. At the same [...] Read more.

Smart cities are expected to improve the quality of life of citizens by relying on new paradigms, such as the Internet of Things (IoT) and its capacity to manage and interconnect thousands of sensors and actuators scattered across the city. At the same time, mobile devices widely assist professional and personal everyday activities. A very good example of the potential of these devices for smart cities is their powerful support for intuitive service interfaces (such as those based on augmented reality (AR)) for non-expert users. In our work, we consider a scenario that combines IoT and AR within a smart city maintenance service to improve the accessibility of sensor and actuator devices in the field, where responsiveness is crucial. In it, depending on the location and needs of each service, data and commands will be transported by an urban communications network or consulted on the spot. Direct AR interaction with urban objects has already been described; it usually relies on 2D visual codes to deliver object identifiers (IDs) to the rendering device to identify object resources. These IDs allow information about the objects to be retrieved from a remote server. In this work, we present a novel solution that replaces static AR markers with dynamic markers based on LED communication, which can be decoded through cameras embedded in smartphones. These dynamic markers can directly deliver sensor information to the rendering device, on top of the object ID, without further network interaction. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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31 pages, 1101 KiB

Open AccessArticle

SNR Wall Effect Alleviation by Generalized Detector Employed in Cognitive Radio Networks

by Modar Safir Shbat^† and Vyacheslav Tuzlukov^*,†

¹ School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu 702-701, Korea

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 16105-16135; https://doi.org/10.3390/s150716105 - 3 Jul 2015

Cited by 18 | Viewed by 7125

Abstract

The most commonly used spectrum sensing techniques in cognitive radio (CR) networks, such as the energy detector (ED), matched filter (MF), and others, suffer from the noise uncertainty and signal-to-noise ratio (SNR) wall phenomenon. These detectors cannot achieve the required signal [...] Read more.

The most commonly used spectrum sensing techniques in cognitive radio (CR) networks, such as the energy detector (ED), matched filter (MF), and others, suffer from the noise uncertainty and signal-to-noise ratio (SNR) wall phenomenon. These detectors cannot achieve the required signal detection performance regardless of the sensing time. In this paper, we explore a signal processing scheme, namely, the generalized detector (GD) constructed based on the generalized approach to signal processing (GASP) in noise, in spectrum sensing of CR network based on antenna array with the purpose to alleviate the SNR wall problem and improve the signal detection robustness under the low SNR. The simulation results confirm our theoretical issues and effectiveness of GD implementation in CR networks based on antenna array. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 2043 KiB

Open AccessArticle

A Novel Permanent Magnetic Angular Acceleration Sensor

by Hao Zhao^1,2 and Hao Feng^1,3,*

¹ College of Information Engineering, Zhejiang University of Technology, Hangzhou 310023, China

² Nanhu College, Jiaxing University, Jiaxing 314001, China

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

Sensors 2015, 15(7), 16136-16152; https://doi.org/10.3390/s150716136 - 3 Jul 2015

Cited by 16 | Viewed by 8472

Abstract

Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. [...] Read more.

Angular acceleration is an important parameter for status monitoring and fault diagnosis of rotary machinery. Therefore, we developed a novel permanent magnetic angular acceleration sensor, which is without rotation angle limitations and could directly measure the instantaneous angular acceleration of the rotating system. The sensor rotor only needs to be coaxially connected with the rotating system, which enables convenient sensor installation. For the cup structure of the sensor rotor, it has a relatively small rotational inertia. Due to the unique mechanical structure of the sensor, the output signal of the sensor can be directed without a slip ring, which avoids signal weakening effect. In this paper, the operating principle of the sensor is described, and simulated using finite element method. The sensitivity of the sensor is calibrated by torsional pendulum and angle sensor, yielding an experimental result of about 0.88 mV/(rad·s⁻²). Finally, the angular acceleration of the actual rotating system has been tested, using both a single-phase asynchronous motor and a step motor. Experimental result confirms the operating principle of the sensor and indicates that the sensor has good practicability. Full article

(This article belongs to the Special Issue Magnetic Sensor Device-Part 1)

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9 pages, 766 KiB

Open AccessArticle

A Time Difference Method for Measurement of Phase Shift between Distributed Feedback Laser Diode (DFB-LD) Output Wavelength and Intensity

by Yongning Liu, Jun Chang^*, Jie Lian, Zhaojun Liu, Qiang Wang and Cunguang Zhu

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

Sensors 2015, 15(7), 16153-16161; https://doi.org/10.3390/s150716153 - 6 Jul 2015

Cited by 9 | Viewed by 7107

Abstract

A time difference method to conveniently measure the phase shift between output wavelength and intensity of distributed feedback laser diodes (DFB-LDs) was proposed. This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in [...] Read more.

A time difference method to conveniently measure the phase shift between output wavelength and intensity of distributed feedback laser diodes (DFB-LDs) was proposed. This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation. For its practical implementation, a measurement example of phase shift was demonstrated by measuring a time difference between the first time and the second time attendances of the same gas absorption line in the intensity-time curve during one sine or triangle modulation circle. The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π. As the modulation frequency increased the shift value increased with a slowed growth rate. Full article

(This article belongs to the Special Issue Optical Sensors for Chemical, Biological and Industrial Applications)

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34 pages, 1630 KiB

Open AccessArticle

Modular Energy-Efficient and Robust Paradigms for a Disaster-Recovery Process over Wireless Sensor Networks

by Abdul Razaque^*

and Khaled Elleithy

Department of Computer Science, University of Bridgeport, 126 Park Avenue, Bridgeport, CT 06604, USA

Sensors 2015, 15(7), 16162-16195; https://doi.org/10.3390/s150716162 - 6 Jul 2015

Cited by 10 | Viewed by 5967

Abstract

Robust paradigms are a necessity, particularly for emerging wireless sensor network (WSN) applications. The lack of robust and efficient paradigms causes a reduction in the provision of quality of service (QoS) and additional energy consumption. In this paper, we introduce modular energy-efficient and [...] Read more.

Robust paradigms are a necessity, particularly for emerging wireless sensor network (WSN) applications. The lack of robust and efficient paradigms causes a reduction in the provision of quality of service (QoS) and additional energy consumption. In this paper, we introduce modular energy-efficient and robust paradigms that involve two archetypes: (1) the operational medium access control (O-MAC) hybrid protocol and (2) the pheromone termite (PT) model. The O-MAC protocol controls overhearing and congestion and increases the throughput, reduces the latency and extends the network lifetime. O-MAC uses an optimized data frame format that reduces the channel access time and provides faster data delivery over the medium. Furthermore, O-MAC uses a novel randomization function that avoids channel collisions. The PT model provides robust routing for single and multiple links and includes two new significant features: (1) determining the packet generation rate to avoid congestion and (2) pheromone sensitivity to determine the link capacity prior to sending the packets on each link. The state-of-the-art research in this work is based on improving both the QoS and energy efficiency. To determine the strength of O-MAC with the PT model; we have generated and simulated a disaster recovery scenario using a network simulator (ns-3.10) that monitors the activities of disaster recovery staff; hospital staff and disaster victims brought into the hospital. Moreover; the proposed paradigm can be used for general purpose applications. Finally; the QoS metrics of the O-MAC and PT paradigms are evaluated and compared with other known hybrid protocols involving the MAC and routing features. The simulation results indicate that O-MAC with PT produced better outcomes. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 1041 KiB

Open AccessArticle

Inertial Sensing Based Assessment Methods to Quantify the Effectiveness of Post-Stroke Rehabilitation

by Hsin-Ta Li¹, Jheng-Jie Huang¹, Chien-Wen Pan², Heng-I. Chi¹ and Min-Chun Pan^1,3,*

¹ Graduate Institute of Biomedical Engineering, National Central University, Jhongli 320, Taiwan

² Hsinchu Air Base, Hsinchu City 300, Taiwan

³ Department of Mechanical Engineering, National Central University, Jhongli 320, Taiwan

Sensors 2015, 15(7), 16196-16209; https://doi.org/10.3390/s150716196 - 6 Jul 2015

Cited by 19 | Viewed by 7318

Abstract

In clinical settings, traditional stroke rehabilitation evaluation methods are subjectively scored by occupational therapists, and the assessment results vary individually. To address this issue, this study aims to develop a stroke rehabilitation assessment system by using inertial measurement units. The inertial signals from [...] Read more.

In clinical settings, traditional stroke rehabilitation evaluation methods are subjectively scored by occupational therapists, and the assessment results vary individually. To address this issue, this study aims to develop a stroke rehabilitation assessment system by using inertial measurement units. The inertial signals from the upper extremities were acquired, from which three quantitative indicators were extracted to reflect rehabilitation performance during stroke patients’ movement examination, i.e., shoulder flexion. Both healthy adults and stroke patients were recruited to correlate the proposed quantitative evaluation indices and traditional rehab assessment scales. Especially, as a unique feature of the study the weight for each of three evaluation indicators was estimated by the least squares method. The quantitative results demonstrate the proposed method accurately reflects patients’ recovery from pre-rehabilitation, and confirm the feasibility of applying inertial signals to evaluate rehab performance through feature extraction. The implemented assessment scheme appears to have the potential to overcome some shortcomings of traditional assessment methods and indicates rehab performance correctly. Full article

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

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15 pages, 697 KiB

Open AccessArticle

User Expectations for Media Sharing Practices in Open Display Networks

by Rui Jose^1,*

, Jorge C. S. Cardoso²

and Jason Hong³

¹ Centro Algoritmi, University of Minho, Guimarães 4800-058, Portugal

² CITAR/School of Arts, Portuguese Catholic University, Porto 4169-005, Portugal

³ Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh 15213, PA, USA

Sensors 2015, 15(7), 16210-16224; https://doi.org/10.3390/s150716210 - 6 Jul 2015

Viewed by 4773

Abstract

Open Display Networks have the potential to allow many content creators to publish their media to an open-ended set of screen displays. However, this raises the issue of how to match that content to the right displays. In this study, we aim to [...] Read more.

Open Display Networks have the potential to allow many content creators to publish their media to an open-ended set of screen displays. However, this raises the issue of how to match that content to the right displays. In this study, we aim to understand how the perceived utility of particular media sharing scenarios is affected by three independent variables, more specifically: (a) the locativeness of the content being shared; (b) how personal that content is and (c) the scope in which it is being shared. To assess these effects, we composed a set of 24 media sharing scenarios embedded with different treatments of our three independent variables. We then asked 100 participants to express their perception of the relevance of those scenarios. The results suggest a clear preference for scenarios where content is both local and directly related to the person that is publishing it. This is in stark contrast to the types of content that are commonly found in public displays, and confirms the opportunity that open displays networks may represent a new media for self-expression. This novel understanding may inform the design of new publication paradigms that will enable people to share media across the display networks. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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23 pages, 689 KiB

Open AccessArticle

Bearing Fault Diagnosis Based on Statistical Locally Linear Embedding

by Xiang Wang^1,2,*

, Yuan Zheng³, Zhenzhou Zhao³ and Jinping Wang¹

¹ College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China

² School of Energy and Power Engineering, Nanjing Institute of Technology, Nanjing 211167, China

³ College of Energy and Electrical Engineering, Hohai University, Nanjing 210098, China

Sensors 2015, 15(7), 16225-16247; https://doi.org/10.3390/s150716225 - 6 Jul 2015

Cited by 140 | Viewed by 9713

Abstract

Fault diagnosis is essentially a kind of pattern recognition. The measured signal samples usually distribute on nonlinear low-dimensional manifolds embedded in the high-dimensional signal space, so how to implement feature extraction, dimensionality reduction and improve recognition performance is a crucial task. In this [...] Read more.

Fault diagnosis is essentially a kind of pattern recognition. The measured signal samples usually distribute on nonlinear low-dimensional manifolds embedded in the high-dimensional signal space, so how to implement feature extraction, dimensionality reduction and improve recognition performance is a crucial task. In this paper a novel machinery fault diagnosis approach based on a statistical locally linear embedding (S-LLE) algorithm which is an extension of LLE by exploiting the fault class label information is proposed. The fault diagnosis approach first extracts the intrinsic manifold features from the high-dimensional feature vectors which are obtained from vibration signals that feature extraction by time-domain, frequency-domain and empirical mode decomposition (EMD), and then translates the complex mode space into a salient low-dimensional feature space by the manifold learning algorithm S-LLE, which outperforms other feature reduction methods such as PCA, LDA and LLE. Finally in the feature reduction space pattern classification and fault diagnosis by classifier are carried out easily and rapidly. Rolling bearing fault signals are used to validate the proposed fault diagnosis approach. The results indicate that the proposed approach obviously improves the classification performance of fault pattern recognition and outperforms the other traditional approaches. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 6265 KiB

Open AccessArticle

A Meliorated Multi-Frequency Band Pyroelectric Sensor

by Chun-Ching Hsiao^1,*

, Sheng-Yi Liu¹ and An-Shen Siao²

¹ Department of Mechanical Design Engineering, National Formosa University, No. 64, Wunhua Rd., Huwei Township, Yunlin County 632, Taiwan

² Department of Mechanical Engineering, National Taiwan University of Science and Technology, No. 43, Keelung Rd., Sec. 4, Taipei 10607, Taiwan

Sensors 2015, 15(7), 16248-16264; https://doi.org/10.3390/s150716248 - 6 Jul 2015

Cited by 10 | Viewed by 5149

Abstract

This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker [...] Read more.

This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 4434 KiB

Open AccessArticle

Curved Microneedle Array-Based sEMG Electrode for Robust Long-Term Measurements and High Selectivity

by Minjae Kim, Taewan Kim, Dong Sung Kim and Wan Kyun Chung^*

Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea

Sensors 2015, 15(7), 16265-16280; https://doi.org/10.3390/s150716265 - 6 Jul 2015

Cited by 55 | Viewed by 10004

Abstract

Surface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a [...] Read more.

Surface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode. Full article

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

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22 pages, 1845 KiB

Open AccessArticle

A Smart City Lighting Case Study on an OpenStack-Powered Infrastructure

by Giovanni Merlino^1,2,*, Dario Bruneo¹, Salvatore Distefano^3,4, Francesco Longo¹, Antonio Puliafito¹ and Adnan Al-Anbuky⁵

¹ Mobile and Distributed Systems Lab, Dipartimento di Ingegneria, Università di Messina, Contrada di Dio, 98166 Messina, Italy

² Dipartimento DIEEI, Università di Catania, Viale Andrea Doria 6, 98166 Catania, Italy

³ Social and Urban Computing Group, Higher Institute of Information Technologies and Information Systems, Kazan Federal University, 35 Kremlevskaya street, 420008 Kazan, Russia

⁴ Dipartimento DEIB, Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano, Italy

⁵ Sensor Network & Smart Environment Research Lab, School of Engineering, Auckland University of Technology, 34 St Paul Street (City Campus), Auckland 1010, New Zealand

Sensors 2015, 15(7), 16314-16335; https://doi.org/10.3390/s150716314 - 6 Jul 2015

Cited by 28 | Viewed by 9445

Abstract

The adoption of embedded systems, mobile devices and other smart devices keeps rising globally, and the scope of their involvement broadens, for instance, in smart city-like scenarios. In light of this, a pressing need emerges to tame such complexity and reuse as much [...] Read more.

The adoption of embedded systems, mobile devices and other smart devices keeps rising globally, and the scope of their involvement broadens, for instance, in smart city-like scenarios. In light of this, a pressing need emerges to tame such complexity and reuse as much tooling as possible without resorting to vertical ad hoc solutions, while at the same time taking into account valid options with regard to infrastructure management and other more advanced functionalities. Existing solutions mainly focus on core mechanisms and do not allow one to scale by leveraging infrastructure or adapt to a variety of scenarios, especially if actuators are involved in the loop. A new, more flexible, cloud-based approach, able to provide device-focused workflows, is required. In this sense, a widely-used and competitive framework for infrastructure as a service, such as OpenStack, with its breadth in terms of feature coverage and expanded scope, looks to fit the bill, replacing current application-specific approaches with an innovative application-agnostic one. This work thus describes the rationale, efforts and results so far achieved for an integration of IoT paradigms and resource ecosystems with such a kind of cloud-oriented device-centric environment, by focusing on a smart city scenario, namely a park smart lighting example, and featuring data collection, data visualization, event detection and coordinated reaction, as example use cases of such integration. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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22 pages, 2114 KiB

Open AccessArticle

Evaluation of a Cubature Kalman Filtering-Based Phase Unwrapping Method for Differential Interferograms with High Noise in Coal Mining Areas

by Wanli Liu¹, Zhengfu Bian^2,*, Zhenguo Liu¹ and Qiuzhao Zhang¹

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

² State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China

Sensors 2015, 15(7), 16336-16357; https://doi.org/10.3390/s150716336 - 6 Jul 2015

Cited by 18 | Viewed by 6350

Abstract

Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced [...] Read more.

Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 1488 KiB

Open AccessArticle

Phase Difference Optimization of Dual-Wavelength Excitation for the CW-Photoacoustic-Based Noninvasive and Selective Investigation of Aqueous Solutions of Glucose

by Serge Camou

NTT Device Technology Laboratories, NTT Corporation, Atsugi 243-0198, Japan

Sensors 2015, 15(7), 16358-16371; https://doi.org/10.3390/s150716358 - 7 Jul 2015

Cited by 3 | Viewed by 5770

Abstract

Towards the noninvasive and continuous monitoring of blood glucose levels, we chose the continuous-wave photoacoustic (CW-PA) technique and developed the optical power balance shift (OPBS) method. However, operating with optical wavelengths in the near-infrared (NIR) region ensures deep penetration inside human soft-tissue, but [...] Read more.

Towards the noninvasive and continuous monitoring of blood glucose levels, we chose the continuous-wave photoacoustic (CW-PA) technique and developed the optical power balance shift (OPBS) method. However, operating with optical wavelengths in the near-infrared (NIR) region ensures deep penetration inside human soft-tissue, but also leads to two serious issues: strong background level noise from water molecules in this wavelength range and small differences between the absorbance spectra of diluted compounds. To resolve them, the OPBS method relies on simultaneous optical excitation at two wavelengths for differential measurements. However, the first validation in vitro with calibrated aqueous solutions of glucose and albumin revealed strong dependence on the phase difference between the two lights sources. In this paper, we report a systematic investigation of this parameter, from PA-based measurements over a wide range of phase differences and an extensive characterization in the frequency domain. The process of maintaining the phase quadrature of the two optical signals is demonstrated in real time through an analysis of the PA signal and therefore does not require any additional equipment. Finally, a comparison of aqueous glucose solution characterizations at high concentration levels with the two methods was performed and consistent results were obtained. Full article

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

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16 pages, 925 KiB

Open AccessArticle

Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition

by Fu-Tai Wang¹, Hsiao-Lung Chan^2,*, Chun-Li Wang³, Hung-Ming Jian² and Sheng-Hsiung Lin²

¹ Department of Electrical Engineering, Hwa Hsia University of Technology, 111, Gongzhuan Rd., Zhonghe, New Taipei City 23568, Taiwan

² Department of Electrical Engineering, Chang Gung University, 259 Wenhwa 1st Road, Kweishan, Taoyuan 33302, Taiwan

³ Department of Cardiology, Chang Gung Memorial Hospital, 5 Fu-Hsing Street, Kweishan, Taoyuan 33305, Taiwan

Sensors 2015, 15(7), 16372-16387; https://doi.org/10.3390/s150716372 - 7 Jul 2015

Cited by 39 | Viewed by 6738

Abstract

Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments [...] Read more.

Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD) can decompose a signal into several intrinsic mode functions (IMFs) that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 2272 KiB

Open AccessArticle

PARAFAC Decomposition for Ultrasonic Wave Sensing of Fiber Bragg Grating Sensors: Procedure and Evaluation

by Rencheng Zheng^1,*

, Kimihiko Nakano², Rui Ohashi¹, Yoji Okabe¹, Mamoru Shimazaki³, Hiroki Nakamura⁴ and Qi Wu¹

¹ Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan

² Interfaculty Initiative in Information Studies, The University of Tokyo, Tokyo 153-8505, Japan

³ Tokyo Metropolitan College of Industrial Technology, Shinagawa 140-0011, Japan

⁴ Graduate school of Engineering, Kanagawa University, Yokohama 221-8686, Japan

Sensors 2015, 15(7), 16388-16411; https://doi.org/10.3390/s150716388 - 7 Jul 2015

Cited by 4 | Viewed by 5323

Abstract

Ultrasonic wave-sensing technology has been applied for the health monitoring of composite structures, using normal fiber Bragg grating (FBG) sensors with a high-speed wavelength interrogation system of arrayed waveguide grating (AWG) filters; however, researchers are required to average thousands of repeated measurements to [...] Read more.

Ultrasonic wave-sensing technology has been applied for the health monitoring of composite structures, using normal fiber Bragg grating (FBG) sensors with a high-speed wavelength interrogation system of arrayed waveguide grating (AWG) filters; however, researchers are required to average thousands of repeated measurements to distinguish significant signals. To resolve this bottleneck problem, this study established a signal-processing strategy that improves the signal-to-noise ratio for the one-time measured signal of ultrasonic waves, by application of parallel factor analysis (PARAFAC) technology that produces unique multiway decomposition without additional orthogonal or independent constraints. Through bandpass processing of the AWG filter and complex wavelet transforms, ultrasonic wave signals are preprocessed as time, phase, and frequency profiles, and then decomposed into a series of conceptual three-way atoms by PARAFAC. While an ultrasonic wave results in a Bragg wavelength shift, antiphase fluctuations can be observed at two adjacent AWG ports. Thereby, concentrating on antiphase features among the three-way atoms, a fitting atom can be chosen and then restored to three-way profiles as a final result. An experimental study has revealed that the final result is consistent with the conventional 1024-data averaging signal, and relative error evaluation has indicated that the signal-to-noise ratio of ultrasonic waves can be significantly improved. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 772 KiB

Open AccessArticle

An Autonomous Star Identification Algorithm Based on One-Dimensional Vector Pattern for Star Sensors

by Liyan Luo, Luping Xu^* and Hua Zhang^*

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

Sensors 2015, 15(7), 16412-16429; https://doi.org/10.3390/s150716412 - 7 Jul 2015

Cited by 13 | Viewed by 6157

Abstract

In order to enhance the robustness and accelerate the recognition speed of star identification, an autonomous star identification algorithm for star sensors is proposed based on the one-dimensional vector pattern (one_DVP). In the proposed algorithm, the space geometry information of the observed stars [...] Read more.

In order to enhance the robustness and accelerate the recognition speed of star identification, an autonomous star identification algorithm for star sensors is proposed based on the one-dimensional vector pattern (one_DVP). In the proposed algorithm, the space geometry information of the observed stars is used to form the one-dimensional vector pattern of the observed star. The one-dimensional vector pattern of the same observed star remains unchanged when the stellar image rotates, so the problem of star identification is simplified as the comparison of the two feature vectors. The one-dimensional vector pattern is adopted to build the feature vector of the star pattern, which makes it possible to identify the observed stars robustly. The characteristics of the feature vector and the proposed search strategy for the matching pattern make it possible to achieve the recognition result as quickly as possible. The simulation results demonstrate that the proposed algorithm can effectively accelerate the star identification. Moreover, the recognition accuracy and robustness by the proposed algorithm are better than those by the pyramid algorithm, the modified grid algorithm, and the LPT algorithm. The theoretical analysis and experimental results show that the proposed algorithm outperforms the other three star identification algorithms. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 8967 KiB

Open AccessArticle

Impact of Data Processing and Antenna Frequency on Spatial Structure Modelling of GPR Data

by Daniela De Benedetto^1,2,*, Ruggiero Quarto¹, Annamaria Castrignanò² and Domenico A. Palumbo²

¹ Dipartimento di Scienze della Terra e Geoambientali, University of Bari, Aldo Moro, Bari 70125, Italy

² Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Unità di Ricerca per i Sistemi Colturali degli Ambienti Caldo-Aridi (SCA), Bari 70125, Italy

Sensors 2015, 15(7), 16430-16447; https://doi.org/10.3390/s150716430 - 8 Jul 2015

Cited by 10 | Viewed by 5974

Abstract

Over the last few years high-resolution geophysical techniques, in particular ground-penetrating radar (GPR), have been used in agricultural applications for assessing soil water content variation in a non-invasive way. However, the wide use of GPR is greatly limited by the data processing complexity. [...] Read more.

Over the last few years high-resolution geophysical techniques, in particular ground-penetrating radar (GPR), have been used in agricultural applications for assessing soil water content variation in a non-invasive way. However, the wide use of GPR is greatly limited by the data processing complexity. In this paper, a quantitative analysis of GPR data is proposed. The data were collected with 250, 600 and 1600 MHz antennas in a gravelly soil located in south-eastern Italy. The objectives were: (1) to investigate the impact of data processing on radar signals; (2) to select a quick, efficient and error-effective data processing for detecting subsurface features; (3) to examine the response of GPR as a function of operating frequency, by using statistical and geostatistical techniques. Six data processing sequences with an increasing level of complexity were applied. The results showed that the type and range of spatial structures of GPR data did not depend on data processing at a given frequency. It was also evident that the noise tended to decrease with the complexity of processing, then the most error-effective procedure was selected. The results highlight the critical importance of the antenna frequency and of the spatial scale of soil/subsoil processes being investigated. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 3937 KiB

Open AccessArticle

An Inertial and Optical Sensor Fusion Approach for Six Degree-of-Freedom Pose Estimation

by Changyu He¹, Peter Kazanzides², Hasan Tutkun Sen², Sungmin Kim² and Yue Liu^1,*

¹ Beijing Engineering Research Center of Mixed Reality and Advanced Display, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China

² Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA

Sensors 2015, 15(7), 16448-16465; https://doi.org/10.3390/s150716448 - 8 Jul 2015

Cited by 45 | Viewed by 10193

Abstract

Optical tracking provides relatively high accuracy over a large workspace but requires line-of-sight between the camera and the markers, which may be difficult to maintain in actual applications. In contrast, inertial sensing does not require line-of-sight but is subject to drift, which may [...] Read more.

Optical tracking provides relatively high accuracy over a large workspace but requires line-of-sight between the camera and the markers, which may be difficult to maintain in actual applications. In contrast, inertial sensing does not require line-of-sight but is subject to drift, which may cause large cumulative errors, especially during the measurement of position. To handle cases where some or all of the markers are occluded, this paper proposes an inertial and optical sensor fusion approach in which the bias of the inertial sensors is estimated when the optical tracker provides full six degree-of-freedom (6-DOF) pose information. As long as the position of at least one marker can be tracked by the optical system, the 3-DOF position can be combined with the orientation estimated from the inertial measurements to recover the full 6-DOF pose information. When all the markers are occluded, the position tracking relies on the inertial sensors that are bias-corrected by the optical tracking system. Experiments are performed with an augmented reality head-mounted display (ARHMD) that integrates an optical tracking system (OTS) and inertial measurement unit (IMU). Experimental results show that under partial occlusion conditions, the root mean square errors (RMSE) of orientation and position are 0.04° and 0.134 mm, and under total occlusion conditions for 1 s, the orientation and position RMSE are 0.022° and 0.22 mm, respectively. Thus, the proposed sensor fusion approach can provide reliable 6-DOF pose under long-term partial occlusion and short-term total occlusion conditions. Full article

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

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18 pages, 1225 KiB

Open AccessArticle

Design and Realization of an Electromagnetic Guiding System for Blind Running Athletes

by Marco Pieralisi¹, Valerio Petrini¹, Valentina Di Mattia^1,*, Giovanni Manfredi¹, Alfredo De Leo¹, Lorenzo Scalise²

, Paola Russo¹ and Graziano Cerri¹

¹ Department of Information Engineering, Università Politecnica delle Marche, via Brecce Bianche, Ancona 60131, Italy

² Department of Industrial Engineering and Mathematical Science, Università Politecnica delle Marche, via Brecce Bianche, Ancona 60131, Italy

Sensors 2015, 15(7), 16466-16483; https://doi.org/10.3390/s150716466 - 8 Jul 2015

Cited by 16 | Viewed by 7757

Abstract

Nowadays the technologies aimed at improving the quality of life of people affected by visual diseases are quite common; e.g., devices to support walking or reading. Surprisingly, there is a lack of innovative technologies aimed at helping visually impaired athletes during physical activities. [...] Read more.

Nowadays the technologies aimed at improving the quality of life of people affected by visual diseases are quite common; e.g., devices to support walking or reading. Surprisingly, there is a lack of innovative technologies aimed at helping visually impaired athletes during physical activities. An example is represented by blind runners who need to be physically linked to a sighted guide by means of non-stretchable tethers during races; with consequent limitations in terms of performance and independence. This paper wants to investigate the possibility of realizing a system able to guide blind runners along a complex path, paving the way for the realization of an innovative device designed to improve their independence during training or competitions. The system consists of: (1) a mobile unit, which is placed before the runner and generates two “electromagnetic walls” delimiting the way; (2) a receiving unit (worn by the athlete) that provides vibro-tactile warnings every time the user is going outside the safe area so as to encourage him to move toward the central position. The feasibility and the utility of the system proposed are demonstrated by means of tests carried out thanks to the collaboration of a blind volunteer. Full article

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19 pages, 4319 KiB

Open AccessArticle

HyperCube: A Small Lensless Position Sensing Device for the Tracking of Flickering Infrared LEDs

by Thibaut Raharijaona^*, Paul Mignon, Raphaël Juston, Lubin Kerhuel and Stéphane Viollet

Aix-Marseille Université, ISM UMR 7287, 13288, Marseille Cedex 09, France

Sensors 2015, 15(7), 16484-16502; https://doi.org/10.3390/s150716484 - 8 Jul 2015

Cited by 6 | Viewed by 8793

Abstract

An innovative insect-based visual sensor is designed to perform active marker tracking. Without any optics and a field-of-view of about 60°, a novel miniature visual sensor is able to locate flickering markers (LEDs) with an accuracy much greater than the one dictated by [...] Read more.

An innovative insect-based visual sensor is designed to perform active marker tracking. Without any optics and a field-of-view of about 60°, a novel miniature visual sensor is able to locate flickering markers (LEDs) with an accuracy much greater than the one dictated by the pixel pitch. With a size of only 1 cm3 and a mass of only 0.33 g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. Only three photosensors are placed on each side of the cubic configuration of the sensing device, making this sensor very inexpensive and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at a high frequency (>1 kHz) with a precision of 0.5°. The minimalistic design in terms of small size, low mass and low power consumption of this visual sensor makes it suitable for many applications in the field of the cooperative flight of unmanned aerial vehicles and, more generally, robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative position between the sensor and the flickering infrared markers. Full article

(This article belongs to the Special Issue Frontiers in Infrared Photodetection)

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13 pages, 1792 KiB

Open AccessArticle

Application of 3D Printing Technology in Increasing the Diagnostic Performance of Enzyme-Linked Immunosorbent Assay (ELISA) for Infectious Diseases

by Harpal Singh^1,2, Masayuki Shimojima², Tomomi Shiratori¹, Le Van An³, Masami Sugamata^3,4 and Ming Yang^1,*

¹ Department of Intelligent Mechanical Systems, Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo 191-0065, Japan

² Department of Virology 1, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan

³ Department of Microbiology, Hue University of Medicine and Pharmacy, 6 Ngo Quyen St., Hue 47000, Vietnam

⁴ Department of Hygiene and Public Health, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan

Sensors 2015, 15(7), 16503-16515; https://doi.org/10.3390/s150716503 - 8 Jul 2015

Cited by 31 | Viewed by 7553

Abstract

Enzyme-linked Immunosorbent Assay (ELISA)-based diagnosis is the mainstay for measuring antibody response in infectious diseases and to support pathogen identification of potential use in infectious disease outbreaks and clinical care of individual patients. The development of laboratory diagnostics using readily available 3D printing [...] Read more.

Enzyme-linked Immunosorbent Assay (ELISA)-based diagnosis is the mainstay for measuring antibody response in infectious diseases and to support pathogen identification of potential use in infectious disease outbreaks and clinical care of individual patients. The development of laboratory diagnostics using readily available 3D printing technologies provides a timely opportunity for further expansion of this technology into immunodetection systems. Utilizing available 3D printing platforms, a ‘3D well’ was designed and developed to have an increased surface area compared to those of 96-well plates. The ease and rapidity of the development of the 3D well prototype provided an opportunity for its rapid validation through the diagnostic performance of ELISA in infectious disease without modifying current laboratory practices for ELISA. The improved sensitivity of the 3D well of up to 2.25-fold higher compared to the 96-well ELISA provides a potential for the expansion of this technology towards miniaturization and Lab-On-a-Chip platforms to reduce time, volume of reagents and samples needed for such assays in the laboratory diagnosis of infectious and other diseases including applications in other disciplines. Full article

(This article belongs to the Section Biosensors)

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20 pages, 2251 KiB

Open AccessArticle

FBG Interrogation Method with High Resolution and Response Speed Based on a Reﬂective-Matched FBG Scheme

by Jiwen Cui^*,†, Yang Hu^†, Kunpeng Feng^†

, Junying Li and Jiubin Tan

¹ Institute of Ultra-precision Optoelectronic Instrument Engineering, Science Park, Harbin Institute of Technology, No. 2 Yikuang Street, Nangang District, Harbin 150080, China

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 16516-16535; https://doi.org/10.3390/s150716516 - 8 Jul 2015

Cited by 49 | Viewed by 8074

Abstract

In this paper, a high resolution and response speed interrogation method based on a reﬂective-matched Fiber Bragg Grating (FBG) scheme is investigated in detail. The nonlinear problem of the reﬂective-matched FBG sensing interrogation scheme is solved by establishing and optimizing the mathematical model. [...] Read more.

In this paper, a high resolution and response speed interrogation method based on a reﬂective-matched Fiber Bragg Grating (FBG) scheme is investigated in detail. The nonlinear problem of the reﬂective-matched FBG sensing interrogation scheme is solved by establishing and optimizing the mathematical model. A mechanical adjustment to optimize the interrogation method by tuning the central wavelength of the reference FBG to improve the stability and anti-temperature perturbation performance is investigated. To satisfy the measurement requirements of optical and electric signal processing, a well- designed acquisition circuit board is prepared, and experiments on the performance of the interrogation method are carried out. The experimental results indicate that the optical power resolution of the acquisition circuit border is better than 8 pW, and the stability of the interrogation method with the mechanical adjustment can reach 0.06%. Moreover, the nonlinearity of the interrogation method is 3.3% in the measurable range of 60 pm; the influence of temperature is significantly reduced to 9.5%; the wavelength resolution and response speed can achieve values of 0.3 pm and 500 kHz, respectively. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 5747 KiB

Open AccessArticle

Real-Time Impact Visualization Inspection of Aerospace Composite Structures with Distributed Sensors

by Liang Si^* and Horst Baier

Institute of Lightweight Structures, Faculty of Mechanical Engineering, Technische Universität München, Boltzmannstr. 15, Garching 85748, Germany

Sensors 2015, 15(7), 16536-16556; https://doi.org/10.3390/s150716536 - 8 Jul 2015

Cited by 17 | Viewed by 5865

Abstract

For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor [...] Read more.

For the future design of smart aerospace structures, the development and application of a reliable, real-time and automatic monitoring and diagnostic technique is essential. Thus, with distributed sensor networks, a real-time automatic structural health monitoring (SHM) technique is designed and investigated to monitor and predict the locations and force magnitudes of unforeseen foreign impacts on composite structures and to estimate in real time mode the structural state when impacts occur. The proposed smart impact visualization inspection (IVI) technique mainly consists of five functional modules, which are the signal data preprocessing (SDP), the forward model generator (FMG), the impact positioning calculator (IPC), the inverse model operator (IMO) and structural state estimator (SSE). With regard to the verification of the practicality of the proposed IVI technique, various structure configurations are considered, which are a normal CFRP panel and another CFRP panel with “orange peel” surfaces and a cutout hole. Additionally, since robustness against several background disturbances is also an essential criterion for practical engineering demands, investigations and experimental tests are carried out under random vibration interfering noise (RVIN) conditions. The accuracy of the predictions for unknown impact events on composite structures using the IVI technique is validated under various structure configurations and under changing environmental conditions. The evaluated errors all fall well within a satisfactory limit range. Furthermore, it is concluded that the IVI technique is applicable for impact monitoring, diagnosis and assessment of aerospace composite structures in complex practical engineering environments. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 3060 KiB

Open AccessArticle

A Vision-Based Sensor for Noncontact Structural Displacement Measurement

by Dongming Feng^*

, Maria Q. Feng, Ekin Ozer and Yoshio Fukuda

Department of Civil Engineering and Engineering Mechanics, Columbia University, New York, NY 10027, USA

Sensors 2015, 15(7), 16557-16575; https://doi.org/10.3390/s150716557 - 9 Jul 2015

Cited by 405 | Viewed by 16930

Abstract

Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for [...] Read more.

Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1009 KiB

Open AccessArticle

Application of Visible and Near-Infrared Hyperspectral Imaging to Determine Soluble Protein Content in Oilseed Rape Leaves

by Chu Zhang

, Fei Liu^*

, Wenwen Kong and Yong He^*

College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China

Sensors 2015, 15(7), 16576-16588; https://doi.org/10.3390/s150716576 - 9 Jul 2015

Cited by 82 | Viewed by 8558

Abstract

Visible and near-infrared hyperspectral imaging covering spectral range of 380–1030 nm as a rapid and non-destructive method was applied to estimate the soluble protein content of oilseed rape leaves. Average spectrum (500–900 nm) of the region of interest (ROI) of each sample was [...] Read more.

Visible and near-infrared hyperspectral imaging covering spectral range of 380–1030 nm as a rapid and non-destructive method was applied to estimate the soluble protein content of oilseed rape leaves. Average spectrum (500–900 nm) of the region of interest (ROI) of each sample was extracted, and four samples out of 128 samples were defined as outliers by Monte Carlo-partial least squares (MCPLS). Partial least squares (PLS) model using full spectra obtained dependable performance with the correlation coefficient (r_p) of 0.9441, root mean square error of prediction (RMSEP) of 0.1658 mg/g and residual prediction deviation (RPD) of 2.98. The weighted regression coefficient (Bw), successive projections algorithm (SPA) and genetic algorithm-partial least squares (GAPLS) selected 18, 15, and 16 sensitive wavelengths, respectively. SPA-PLS model obtained the best performance with r_p of 0.9554, RMSEP of 0.1538 mg/g and RPD of 3.25. Distribution of protein content within the rape leaves were visualized and mapped on the basis of the SPA-PLS model. The overall results indicated that hyperspectral imaging could be used to determine and visualize the soluble protein content of rape leaves. Full article

(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)

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25 pages, 10953 KiB

Open AccessArticle

An Ambulatory System for Gait Monitoring Based on Wireless Sensorized Insoles

by Iván González

, Jesús Fontecha^*

, Ramón Hervás

and José Bravo

MAmI Research Lab, University of Castilla-La Mancha, Esc. Sup. de Informática, Paseo de la Universidad, 4, 13071 Ciudad Real, Spain

Sensors 2015, 15(7), 16589-16613; https://doi.org/10.3390/s150716589 - 9 Jul 2015

Cited by 90 | Viewed by 12091

Abstract

A new gait phase detection system for continuous monitoring based on wireless sensorized insoles is presented. The system can be used in gait analysis mobile applications, and it is designed for real-time demarcation of gait phases. The system employs pressure sensors to assess [...] Read more.

A new gait phase detection system for continuous monitoring based on wireless sensorized insoles is presented. The system can be used in gait analysis mobile applications, and it is designed for real-time demarcation of gait phases. The system employs pressure sensors to assess the force exerted by each foot during walking. A fuzzy rule-based inference algorithm is implemented on a smartphone and used to detect each of the gait phases based on the sensor signals. Additionally, to provide a solution that is insensitive to perturbations caused by non-walking activities, a probabilistic classifier is employed to discriminate walking forward from other low-level activities, such as turning, walking backwards, lateral walking, etc. The combination of these two algorithms constitutes the first approach towards a continuous gait assessment system, by means of the avoidance of non-walking influences. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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18 pages, 2626 KiB

Open AccessArticle

Electrochemical Co-Reduction Synthesis of AuPt Bimetallic Nanoparticles-Graphene Nanocomposites for Selective Detection of Dopamine in the Presence of Ascorbic Acid and Uric Acid

by Zongya Zhao^1,2, Mingming Zhang^1,2, Xiang Chen^1,2, Youjun Li^1,2 and Jue Wang^1,2,*

¹ The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Institute of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China

² National Engineering Research Center of Health Care and Medical Devices, Xi'an Jiaotong University Branch, Xi'an 710049, China

Sensors 2015, 15(7), 16614-16631; https://doi.org/10.3390/s150716614 - 9 Jul 2015

Cited by 28 | Viewed by 8048

Abstract

In this paper, AuPt bimetallic nanoparticles-graphene nanocomposites were obtained by electrochemical co-reduction of graphene oxide (GO), HAuCl₄ and H₂PtCl₆. The as-prepared AuPt bimetallic nanoparticles-graphene nanocomposites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and other [...] Read more.

In this paper, AuPt bimetallic nanoparticles-graphene nanocomposites were obtained by electrochemical co-reduction of graphene oxide (GO), HAuCl₄ and H₂PtCl₆. The as-prepared AuPt bimetallic nanoparticles-graphene nanocomposites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and other electrochemical methods. The morphology and composition of the nanocomposite could be easily controlled by adjusting the HAuCl₄/H₂PtCl₆ concentration ratio. The electrochemical experiments showed that when the concentration ratio of HAuCl₄/H₂PtCl₆ was 1:1, the obtained AuPt bimetallic nanoparticles-graphene nanocomposite (denoted as Au1Pt1NPs-GR) possessed the highest electrocatalytic activity toward dopamine (DA). As such, Au1Pt1NPs-GR nanocomposites were used to detect DA in the presence of ascorbic acid (AA) and uric acid (UA) using the differential pulse voltammetry (DPV) technique and on the modified electrode, there were three separate DPV oxidation peaks with the peak potential separations of 177 mV, 130 mV and 307 mV for DA and AA, DA and UA, AA and UA, respectively. The linear range of the constructed DA sensor was from 1.6 μM to 39.7 μM with a detection limit of 0.1 μM (S/N = 3). The obtained DA sensor with good stability, high reproducibility and excellent selectivity made it possible to detect DA in human urine samples. Full article

(This article belongs to the Special Issue Electrochemical Sensors and Biosensors: From Bench-Top to Point-of-Care)

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10 pages, 1232 KiB

Open AccessArticle

Fiber Optic Fabry-Perot Current Sensor Integrated with Magnetic Fluid Using a Fiber Bragg Grating Demodulation

by Ji Xia^1,†, Qi Wang^2,3,*,†

, Xu Liu² and Hong Luo¹

¹ Academy of Ocean Science and Engineering, National University of Defense Technology, Changsha 410073, China

² College of Information Science and Engineering, Northeastern University, Shenyang 110819, China

³ State Key Laboratory of Synthetical Automation for Process Industries, Northeastern University, Shenyang 110819, China

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 16632-16641; https://doi.org/10.3390/s150716632 - 9 Jul 2015

Cited by 10 | Viewed by 7252

Abstract

An optical fiber current sensor based on Fabry-Perot interferometer using a fiber Bragg grating demodulation is proposed. Magnetic fluid is used as a sensitive medium in fiber optical Fabry-Perot (F-P) cavity for the optical characteristic of magnetic-controlled refractive index. A Fiber Bragg grating [...] Read more.

An optical fiber current sensor based on Fabry-Perot interferometer using a fiber Bragg grating demodulation is proposed. Magnetic fluid is used as a sensitive medium in fiber optical Fabry-Perot (F-P) cavity for the optical characteristic of magnetic-controlled refractive index. A Fiber Bragg grating (FBG) is connected after the F-P interferometer which is used to reflect the optical power at the Bragg wavelength of the interference transmission spectrum. The corresponding reflective power of the FBG will change with different external current intensity, due to the shift on the interference spectrum of the F-P interferometer. The sensing probe has the advantages of convenient measurement for its demodulation, low cost and high current measurement accuracy on account of its sensing structure. Experimental results show that an optimal sensitivity of 0.8522 nw/A and measurement resolution of 0.001 A is obtained with a FBG at 1550 nm with 99% reflectivity. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 3290 KiB

Open AccessArticle

Expansion of Smartwatch Touch Interface from Touchscreen to Around Device Interface Using Infrared Line Image Sensors

by Soo-Chul Lim, Jungsoon Shin, Seung-Chan Kim and Joonah Park^*

Device & System Research Center, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, Korea

Sensors 2015, 15(7), 16642-16653; https://doi.org/10.3390/s150716642 - 9 Jul 2015

Cited by 27 | Viewed by 16696

Abstract

Touchscreen interaction has become a fundamental means of controlling mobile phones and smartwatches. However, the small form factor of a smartwatch limits the available interactive surface area. To overcome this limitation, we propose the expansion of the touch region of the screen to [...] Read more.

Touchscreen interaction has become a fundamental means of controlling mobile phones and smartwatches. However, the small form factor of a smartwatch limits the available interactive surface area. To overcome this limitation, we propose the expansion of the touch region of the screen to the back of the user’s hand. We developed a touch module for sensing the touched finger position on the back of the hand using infrared (IR) line image sensors, based on the calibrated IR intensity and the maximum intensity region of an IR array. For complete touch-sensing solution, a gyroscope installed in the smartwatch is used to read the wrist gestures. The gyroscope incorporates a dynamic time warping gesture recognition algorithm for eliminating unintended touch inputs during the free motion of the wrist while wearing the smartwatch. The prototype of the developed sensing module was implemented in a commercial smartwatch, and it was confirmed that the sensed positional information of the finger when it was used to touch the back of the hand could be used to control the smartwatch graphical user interface. Our system not only affords a novel experience for smartwatch users, but also provides a basis for developing other useful interfaces. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 602 KiB

Open AccessArticle

Fabrication and Characterization of a CMOS-MEMS Humidity Sensor

by John-Ojur Dennis^1,†, Abdelaziz-Yousif Ahmed^2,* and Mohd-Haris Khir^2,†

¹ Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak Darul Ridzuan 32610, Malaysia

² Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak Darul Ridzuan 32610, Malaysia

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 16674-16687; https://doi.org/10.3390/s150716674 - 10 Jul 2015

Cited by 42 | Viewed by 9671

Abstract

This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on [...] Read more.

This paper reports on the fabrication and characterization of a Complementary Metal Oxide Semiconductor-Microelectromechanical System (CMOS-MEMS) device with embedded microheater operated at relatively elevated temperatures (40 °C to 80 °C) for the purpose of relative humidity measurement. The sensing principle is based on the change in amplitude of the device due to adsorption or desorption of humidity on the active material layer of titanium dioxide (TiO₂) nanoparticles deposited on the moving plate, which results in changes in the mass of the device. The sensor has been designed and fabricated through a standard 0.35 µm CMOS process technology and post-CMOS micromachining technique has been successfully implemented to release the MEMS structures. The sensor is operated in the dynamic mode using electrothermal actuation and the output signal measured using a piezoresistive (PZR) sensor connected in a Wheatstone bridge circuit. The output voltage of the humidity sensor increases from 0.585 mV to 30.580 mV as the humidity increases from 35% RH to 95% RH. The output voltage is found to be linear from 0.585 mV to 3.250 mV as the humidity increased from 35% RH to 60% RH, with sensitivity of 0.107 mV/% RH; and again linear from 3.250 mV to 30.580 mV as the humidity level increases from 60% RH to 95% RH, with higher sensitivity of 0.781 mV/% RH. On the other hand, the sensitivity of the humidity sensor increases linearly from 0.102 mV/% RH to 0.501 mV/% RH with increase in the temperature from 40 °C to 80 °C and a maximum hysteresis of 0.87% RH is found at a relative humidity of 80%. The sensitivity is also frequency dependent, increasing from 0.500 mV/% RH at 2 Hz to reach a maximum value of 1.634 mV/% RH at a frequency of 12 Hz, then decreasing to 1.110 mV/% RH at a frequency of 20 Hz. Finally, the CMOS-MEMS humidity sensor showed comparable response, recovery, and repeatability of measurements in three cycles as compared to a standard sensor that directly measures humidity in % RH. Full article

(This article belongs to the Special Issue Gas Sensors—Designs and Applications)

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22 pages, 3240 KiB

Open AccessArticle

Towards the Development of a Smart Flying Sensor: Illustration in the Field of Precision Agriculture

by Andres Hernandez^*, Harold Murcia, Cosmin Copot and Robin De Keyser

Department of Electrical Energy, Systems and Automation (EeSA), Ghent University, 9000 Ghent, Belgium

Sensors 2015, 15(7), 16688-16709; https://doi.org/10.3390/s150716688 - 10 Jul 2015

Cited by 33 | Viewed by 9388

Abstract

Sensing is an important element to quantify productivity, product quality and to make decisions. Applications, such as mapping, surveillance, exploration and precision agriculture, require a reliable platform for remote sensing. This paper presents the first steps towards the development of a smart flying [...] Read more.

Sensing is an important element to quantify productivity, product quality and to make decisions. Applications, such as mapping, surveillance, exploration and precision agriculture, require a reliable platform for remote sensing. This paper presents the first steps towards the development of a smart flying sensor based on an unmanned aerial vehicle (UAV). The concept of smart remote sensing is illustrated and its performance tested for the task of mapping the volume of grain inside a trailer during forage harvesting. Novelty lies in: (1) the development of a position-estimation method with time delay compensation based on inertial measurement unit (IMU) sensors and image processing; (2) a method to build a 3D map using information obtained from a regular camera; and (3) the design and implementation of a path-following control algorithm using model predictive control (MPC). Experimental results on a lab-scale system validate the effectiveness of the proposed methodology. Full article

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

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19 pages, 2463 KiB

Open AccessArticle

LiDAR Scan Matching Aided Inertial Navigation System in GNSS-Denied Environments

by Jian Tang^1,2, Yuwei Chen^2,*

, Xiaoji Niu¹, Li Wang¹, Liang Chen³, Jingbin Liu², Chuang Shi¹ and Juha Hyyppä²

¹ GNSS Research Center, Wuhan University, 129 Luoyu Road, Wuhan 430079, Hubei, China

² Department of Remote Sensing and Photogrammetry, Finnish Geospatial Institute, Kirkkonummi FI-02431, Finland

³ Department of Navigation and Positioning, Finnish Geospatial Research Institute, Geodeetinrine 2, Kirkkonummi FI-02431, Finland

Sensors 2015, 15(7), 16710-16728; https://doi.org/10.3390/s150716710 - 10 Jul 2015

Cited by 128 | Viewed by 13769

Abstract

A new scan that matches an aided Inertial Navigation System (INS) with a low-cost LiDAR is proposed as an alternative to GNSS-based navigation systems in GNSS-degraded or -denied environments such as indoor areas, dense forests, or urban canyons. In these areas, INS-based Dead [...] Read more.

A new scan that matches an aided Inertial Navigation System (INS) with a low-cost LiDAR is proposed as an alternative to GNSS-based navigation systems in GNSS-degraded or -denied environments such as indoor areas, dense forests, or urban canyons. In these areas, INS-based Dead Reckoning (DR) and Simultaneous Localization and Mapping (SLAM) technologies are normally used to estimate positions as separate tools. However, there are critical implementation problems with each standalone system. The drift errors of velocity, position, and heading angles in an INS will accumulate over time, and on-line calibration is a must for sustaining positioning accuracy. SLAM performance is poor in featureless environments where the matching errors can significantly increase. Each standalone positioning method cannot offer a sustainable navigation solution with acceptable accuracy. This paper integrates two complementary technologies—INS and LiDAR SLAM—into one navigation frame with a loosely coupled Extended Kalman Filter (EKF) to use the advantages and overcome the drawbacks of each system to establish a stable long-term navigation process. Static and dynamic field tests were carried out with a self-developed Unmanned Ground Vehicle (UGV) platform—NAVIS. The results prove that the proposed approach can provide positioning accuracy at the centimetre level for long-term operations, even in a featureless indoor environment. Full article

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

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11 pages, 1018 KiB

Open AccessArticle

A Wireless Passive LC Resonant Sensor Based on LTCC under High-Temperature/Pressure Environments

by Li Qin^1,2, Dandan Shen^1,2, Tanyong Wei^1,2, Qiulin Tan^1,2,3,*, Tao Luo^1,2, Zhaoying Zhou³ and Jijun Xiong^1,2,*

¹ Key Laboratory of Instrumentation Science & Dynamic Measurement, Ministry of Education, North University of China, Tai Yuan 030051, China

² Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Tai Yuan 030051, China

³ State Key Laboratory of Transducer Technology, Department of Precision Instrument and Mechanology, Tsinghua University, Beijing 10084, China

Sensors 2015, 15(7), 16729-16739; https://doi.org/10.3390/s150716729 - 10 Jul 2015

Cited by 25 | Viewed by 7675

Abstract

In this work, a wireless passive LC resonant sensor based on DuPont 951 ceramic is proposed and tested in a developed high-temperature/pressure complex environment. The test results show that the measured resonant frequency varies approximately linearly with the applied pressure; simultaneously, high temperature [...] Read more.

In this work, a wireless passive LC resonant sensor based on DuPont 951 ceramic is proposed and tested in a developed high-temperature/pressure complex environment. The test results show that the measured resonant frequency varies approximately linearly with the applied pressure; simultaneously, high temperature causes pressure signal drift and changes the response sensitivity. Through the theoretical analysis of the sensor structure model, it is found that the increase in the dielectric constant and the decrease in the Young’s modulus of DuPont 951 ceramic are the main causes that affect the pressure signal in high-temperature measurement. Through calculations, the Young’s modulus of DuPont 951 ceramic is found to decrease rapidly from 120 GPa to 65 GPa within 400 °C. Therefore, the LC resonant pressure sensor needs a temperature compensation structure to eliminate the impact of temperature on pressure measurement. Finally, a temperature compensation structure is proposed and fabricated, and the pressure response after temperature compensation illustrates that temperature drift is significantly reduced compared with that without the temperature compensation structure, which verifies the feasibility the proposed temperature compensation structure. Full article

(This article belongs to the Special Issue Sensors for Harsh Environments)

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23 pages, 2421 KiB

Open AccessArticle

Non-Destructive Current Sensing for Energy Efficiency Monitoring in Buildings with Environmental Certification

by Lia Toledo Moreira Mota, Alexandre De Assis Mota^* and Lorenzo Campos Coiado

Pontifical Catholic University of Campinas, CEATEC, Campus I, Rod. Dom Pedro I, Km136, CEP 13086-900, Campinas, São Paulo, Brazil

Sensors 2015, 15(7), 16740-16762; https://doi.org/10.3390/s150716740 - 10 Jul 2015

Cited by 3 | Viewed by 5554

Abstract

Nowadays, buildings environmental certifications encourage the implementation of initiatives aiming to increase energy efficiency in buildings. In these certification systems, increased energy efficiency arising from such initiatives must be demonstrated. Thus, a challenge to be faced is how to check the increase in [...] Read more.

Nowadays, buildings environmental certifications encourage the implementation of initiatives aiming to increase energy efficiency in buildings. In these certification systems, increased energy efficiency arising from such initiatives must be demonstrated. Thus, a challenge to be faced is how to check the increase in energy efficiency related to each of the employed initiatives without a considerable building retrofit. In this context, this work presents a non-destructive method for electric current sensing to assess implemented initiatives to increase energy efficiency in buildings with environmental certification. This method proposes the use of a sensor that can be installed directly in the low voltage electrical circuit conductors that are powering the initiative under evaluation, without the need for reforms that result in significant costs, repair, and maintenance. The proposed sensor consists of three elements: an air-core transformer current sensor, an amplifying/filtering stage, and a microprocessor. A prototype of the proposed sensor was developed and tests were performed to validate this sensor. Based on laboratory tests, it was possible to characterize the proposed current sensor with respect to the number of turns and cross-sectional area of the primary and secondary coils. Furthermore, using the Least Squares Method, it was possible to determine the efficiency of the air core transformer current sensor (the best efficiency found, considering different test conditions, was 2%), which leads to a linear output response. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 953 KiB

Open AccessArticle

Node Deployment Algorithm Based on Connected Tree for Underwater Sensor Networks

by Peng Jiang^1,*, Xingmin Wang¹ and Lurong Jiang²

¹ Key Lab for IOT and Information Fusion Technology of Zhejiang, Hangzhou Dianzi University, Hangzhou 310018, China

² School of Information Science and Technology, Zhejiang Sci-Tech University, Hangzhou 310018, China

Sensors 2015, 15(7), 16763-16785; https://doi.org/10.3390/s150716763 - 10 Jul 2015

Cited by 35 | Viewed by 5763

Abstract

Designing an efficient deployment method to guarantee optimal monitoring quality is one of the key topics in underwater sensor networks. At present, a realistic approach of deployment involves adjusting the depths of nodes in water. One of the typical algorithms used in such [...] Read more.

Designing an efficient deployment method to guarantee optimal monitoring quality is one of the key topics in underwater sensor networks. At present, a realistic approach of deployment involves adjusting the depths of nodes in water. One of the typical algorithms used in such process is the self-deployment depth adjustment algorithm (SDDA). This algorithm mainly focuses on maximizing network coverage by constantly adjusting node depths to reduce coverage overlaps between two neighboring nodes, and thus, achieves good performance. However, the connectivity performance of SDDA is irresolute. In this paper, we propose a depth adjustment algorithm based on connected tree (CTDA). In CTDA, the sink node is used as the first root node to start building a connected tree. Finally, the network can be organized as a forest to maintain network connectivity. Coverage overlaps between the parent node and the child node are then reduced within each sub-tree to optimize coverage. The hierarchical strategy is used to adjust the distance between the parent node and the child node to reduce node movement. Furthermore, the silent mode is adopted to reduce communication cost. Simulations show that compared with SDDA, CTDA can achieve high connectivity with various communication ranges and different numbers of nodes. Moreover, it can realize coverage as high as that of SDDA with various sensing ranges and numbers of nodes but with less energy consumption. Simulations under sparse environments show that the connectivity and energy consumption performances of CTDA are considerably better than those of SDDA. Meanwhile, the connectivity and coverage performances of CTDA are close to those depth adjustment algorithms base on connected dominating set (CDA), which is an algorithm similar to CTDA. However, the energy consumption of CTDA is less than that of CDA, particularly in sparse underwater environments. Full article

(This article belongs to the Section Sensor Networks)

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18 pages, 1349 KiB

Open AccessArticle

A New Perspective on Fault Geometry and Slip Distribution of the 2009 Dachaidan Mw 6.3 Earthquake from InSAR Observations

by Yang Liu^1,2,3,*, Caijun Xu^1,2,3

, Yangmao Wen^1,2,3

and Hok Sum Fok^1,2

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

² Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, Wuhan 430079, China

³ Collaborative Innovation Center for Geospatial Technology, Wuhan 430079, China

Sensors 2015, 15(7), 16786-16803; https://doi.org/10.3390/s150716786 - 10 Jul 2015

Cited by 9 | Viewed by 5491

Abstract

On 28 August 2009, the northern margin of the Qaidam basin in the Tibet Plateau was ruptured by an Mw 6.3 earthquake. This study utilizes the Envisat ASAR images from descending Track 319 and ascending Track 455 for capturing the coseismic deformation resulting [...] Read more.

On 28 August 2009, the northern margin of the Qaidam basin in the Tibet Plateau was ruptured by an Mw 6.3 earthquake. This study utilizes the Envisat ASAR images from descending Track 319 and ascending Track 455 for capturing the coseismic deformation resulting from this event, indicating that the earthquake fault rupture does not reach to the earth’s surface. We then propose a four-segmented fault model to investigate the coseismic deformation by determining the fault parameters, followed by inverting slip distribution. The preferred fault model shows that the rupture depths for all four fault planes mainly range from 2.0 km to 7.5 km, comparatively shallower than previous results up to ~13 km, and that the slip distribution on the fault plane is complex, exhibiting three slip peaks with a maximum of 2.44 m at a depth between 4.1 km and 4.9 km. The inverted geodetic moment is 3.85 × 10¹⁸ Nm (Mw 6.36). The 2009 event may rupture from the northwest to the southeast unilaterally, reaching the maximum at the central segment. Full article

(This article belongs to the Section Remote Sensors)

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27 pages, 2069 KiB

Open AccessArticle

Integral Images: Efficient Algorithms for Their Computation and Storage in Resource-Constrained Embedded Vision Systems

by Shoaib Ehsan^1,*, Adrian F. Clark¹, Naveed Ur Rehman² and Klaus D. McDonald-Maier¹

¹ School of Computer Science and Electronic Engineering, University of Essex, Colchester CO4 3SQ, UK

² Department of Electrical Engineering, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan

Sensors 2015, 15(7), 16804-16830; https://doi.org/10.3390/s150716804 - 10 Jul 2015

Cited by 36 | Viewed by 6627

Abstract

The integral image, an intermediate image representation, has found extensive use in multi-scale local feature detection algorithms, such as Speeded-Up Robust Features (SURF), allowing fast computation of rectangular features at constant speed, independent of filter size. For resource-constrained real-time embedded vision systems, [...] Read more.

The integral image, an intermediate image representation, has found extensive use in multi-scale local feature detection algorithms, such as Speeded-Up Robust Features (SURF), allowing fast computation of rectangular features at constant speed, independent of filter size. For resource-constrained real-time embedded vision systems, computation and storage of integral image presents several design challenges due to strict timing and hardware limitations. Although calculation of the integral image only consists of simple addition operations, the total number of operations is large owing to the generally large size of image data. Recursive equations allow substantial decrease in the number of operations but require calculation in a serial fashion. This paper presents two new hardware algorithms that are based on the decomposition of these recursive equations, allowing calculation of up to four integral image values in a row-parallel way without significantly increasing the number of operations. An efficient design strategy is also proposed for a parallel integral image computation unit to reduce the size of the required internal memory (nearly 35% for common HD video). Addressing the storage problem of integral image in embedded vision systems, the paper presents two algorithms which allow substantial decrease (at least 44.44%) in the memory requirements. Finally, the paper provides a case study that highlights the utility of the proposed architectures in embedded vision systems. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 1308 KiB

Open AccessArticle

Performance Evaluation and Requirements Assessment for Gravity Gradient Referenced Navigation

by Jisun Lee^1,2, Jay Hyoun Kwon^1,*

and Myeongjong Yu³

¹ Department of Geoinformatics, University of Seoul, Seoul 130-743, Korea

² Department of Civil, Environmental and Geodetic Engineering, Ohio State University, Columbus, OH 43210, USA

³ Agency for Defense Development, Daejeon 151-742, Korea

Sensors 2015, 15(7), 16833-16847; https://doi.org/10.3390/s150716833 - 13 Jul 2015

Cited by 29 | Viewed by 5037

Abstract

In this study, simulation tests for gravity gradient referenced navigation (GGRN) are conducted to verify the effects of various factors such as database (DB) and sensor errors, flight altitude, DB resolution, initial errors, and measurement update rates on the navigation performance. Based on [...] Read more.

In this study, simulation tests for gravity gradient referenced navigation (GGRN) are conducted to verify the effects of various factors such as database (DB) and sensor errors, flight altitude, DB resolution, initial errors, and measurement update rates on the navigation performance. Based on the simulation results, requirements for GGRN are established for position determination with certain target accuracies. It is found that DB and sensor errors and flight altitude have strong effects on the navigation performance. In particular, a DB and sensor with accuracies of 0.1 E and 0.01 E, respectively, are required to determine the position more accurately than or at a level similar to the navigation performance of terrain referenced navigation (TRN). In most cases, the horizontal position error of GGRN is less than 100 m. However, the navigation performance of GGRN is similar to or worse than that of a pure inertial navigation system when the DB and sensor errors are 3 E or 5 E each and the flight altitude is 3000 m. Considering that the accuracy of currently available gradiometers is about 3 E or 5 E, GGRN does not show much advantage over TRN at present. However, GGRN is expected to exhibit much better performance in the near future when accurate DBs and gravity gradiometer are available. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 6608 KiB

Open AccessArticle

Monocular Vision System for Fixed Altitude Flight of Unmanned Aerial Vehicles

by Kuo-Lung Huang¹, Chung-Cheng Chiu^1,*, Sheng-Yi Chiu¹, Yao-Jen Teng² and Shu-Sheng Hao¹

¹ Department of Electrical and Electronic Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan 33551, Taiwan

² School of Defense Science, Chung Cheng Institute of Technology, National Defense University, Taoyuan 33551, Taiwan

Sensors 2015, 15(7), 16848-16865; https://doi.org/10.3390/s150716848 - 13 Jul 2015

Cited by 5 | Viewed by 7288

Abstract

The fastest and most economical method of acquiring terrain images is aerial photography. The use of unmanned aerial vehicles (UAVs) has been investigated for this task. However, UAVs present a range of challenges such as flight altitude maintenance. This paper reports a method [...] Read more.

The fastest and most economical method of acquiring terrain images is aerial photography. The use of unmanned aerial vehicles (UAVs) has been investigated for this task. However, UAVs present a range of challenges such as flight altitude maintenance. This paper reports a method that combines skyline detection with a stereo vision algorithm to enable the flight altitude of UAVs to be maintained. A monocular camera is mounted on the downside of the aircraft’s nose to collect continuous ground images, and the relative altitude is obtained via a stereo vision algorithm from the velocity of the UAV. Image detection is used to obtain terrain images, and to measure the relative altitude from the ground to the UAV. The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images. A forward-looking camera is mounted on the upside of the aircraft’s nose. In combination with the skyline detection algorithm, this helps the aircraft to maintain a stable flight pattern. Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path. Full article

(This article belongs to the Section Physical Sensors)

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29 pages, 5597 KiB

Open AccessArticle

Nonintrusive Finger-Vein Recognition System Using NIR Image Sensor and Accuracy Analyses According to Various Factors

by Tuyen Danh Pham, Young Ho Park, Dat Tien Nguyen, Seung Yong Kwon and Kang Ryoung Park^*

Division of Electronics and Electrical Engineering, Dongguk University, 26 Pil-dong 3-ga, Jung-gu, Seoul 100-715, Korea

Sensors 2015, 15(7), 16866-16894; https://doi.org/10.3390/s150716866 - 13 Jul 2015

Cited by 23 | Viewed by 8635

Abstract

Biometrics is a technology that enables an individual person to be identified based on human physiological and behavioral characteristics. Among biometrics technologies, face recognition has been widely used because of its advantages in terms of convenience and non-contact operation. However, its performance is [...] Read more.

Biometrics is a technology that enables an individual person to be identified based on human physiological and behavioral characteristics. Among biometrics technologies, face recognition has been widely used because of its advantages in terms of convenience and non-contact operation. However, its performance is affected by factors such as variation in the illumination, facial expression, and head pose. Therefore, fingerprint and iris recognitions are preferred alternatives. However, the performance of the former can be adversely affected by the skin condition, including scarring and dryness. In addition, the latter has the disadvantages of high cost, large system size, and inconvenience to the user, who has to align their eyes with the iris camera. In an attempt to overcome these problems, finger-vein recognition has been vigorously researched, but an analysis of its accuracies according to various factors has not received much attention. Therefore, we propose a nonintrusive finger-vein recognition system using a near infrared (NIR) image sensor and analyze its accuracies considering various factors. The experimental results obtained with three databases showed that our system can be operated in real applications with high accuracy; and the dissimilarity of the finger-veins of different people is larger than that of the finger types and hands. Full article

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

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15 pages, 851 KiB

Open AccessArticle

Medium to Long Range Kinematic GPS Positioning with Position-Velocity-Acceleration Model Using Multiple Reference Stations

by Chang-Ki Hong¹

, Chi Ho Park², Joong-hee Han³ and Jay Hyoun Kwon^3,*

¹ Department of Geoinformatics Engineering, Kyungil University, 50 Gamasilgil, Kyeongsan, Gyeongbuk 712-701, Korea

² Division of IoT and Robotics Convergence Research, Daegu Gyeongbuk Institute of Science & Technology, 333 Techno jungang-daero, Hyeonpung-myeon, Dalseong-gun, Dagegu 711-873, Korea

³ Department of Geoinformatics, University of Seoul, 163 Seoulsiripdaero, Dongdaemun-gu, Seoul 130-743, Korea

Sensors 2015, 15(7), 16895-16909; https://doi.org/10.3390/s150716895 - 13 Jul 2015

Cited by 14 | Viewed by 5012

Abstract

In order to obtain precise kinematic global positioning systems (GPS) in medium to large scale networks, the atmospheric effects from tropospheric and ionospheric delays need to be properly modeled and estimated. It is also preferable to use multiple reference stations to improve the [...] Read more.

In order to obtain precise kinematic global positioning systems (GPS) in medium to large scale networks, the atmospheric effects from tropospheric and ionospheric delays need to be properly modeled and estimated. It is also preferable to use multiple reference stations to improve the reliability of the solutions. In this study, GPS kinematic positioning algorithms are developed for the medium to large-scale network based on the position-velocity-acceleration model. Hence, the algorithm can perform even in cases where the near-constant velocity assumption does not hold. In addition, the estimated kinematic accelerations can be used for the airborne gravimetry. The proposed algorithms are implemented using Kalman filter and are applied to the in situ airborne GPS data. The performance of the proposed algorithms is validated by analyzing and comparing the results with those from reference values. The results show that reliable and comparable solutions in both position and kinematic acceleration levels can be obtained using the proposed algorithms. Full article

(This article belongs to the Section Remote Sensors)

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19 pages, 2317 KiB

Open AccessArticle

Sol-Gel Thin Films for Plasmonic Gas Sensors

by Enrico Della Gaspera¹ and Alessandro Martucci^2,*

¹ CSIRO Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168, Australia

² Dipartimento di Ingegneria Industriale ,Universita' di Padova, Via Marzolo 9, Padova 35131, Italy

Sensors 2015, 15(7), 16910-16928; https://doi.org/10.3390/s150716910 - 13 Jul 2015

Cited by 38 | Viewed by 7969

Abstract

Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of [...] Read more.

Plasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors. Full article

(This article belongs to the Special Issue Sol-Gel Based Sensors and Devices)

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27 pages, 2280 KiB

Open AccessArticle

Design and Analysis of a Novel Fully Decoupled Tri-axis Linear Vibratory Gyroscope with Matched Modes

by Dunzhu Xia^*, Lun Kong and Haiyu Gao

Key Laboratory of Micro Inertial Instruments and Advanced Navigation Technology of the Ministry of Education, School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

Sensors 2015, 15(7), 16929-16955; https://doi.org/10.3390/s150716929 - 13 Jul 2015

Cited by 17 | Viewed by 5953

Abstract

We present in this paper a novel fully decoupled silicon micromachined tri-axis linear vibratory gyroscope. The proposed gyroscope structure is highly symmetrical and can be limited to an area of about 8.5 mm × 8.5 mm. It can differentially detect three axes’ angular [...] Read more.

We present in this paper a novel fully decoupled silicon micromachined tri-axis linear vibratory gyroscope. The proposed gyroscope structure is highly symmetrical and can be limited to an area of about 8.5 mm × 8.5 mm. It can differentially detect three axes’ angular velocities at the same time. By elaborately arranging different beams, anchors and sensing frames, the drive and sense modes are fully decoupled from each other. Moreover, the quadrature error correction and frequency tuning functions are taken into consideration in the structure design for all the sense modes. Since there exists an unwanted in-plane rotational mode, theoretical analysis is implemented to eliminate it. To accelerate the mode matching process, the particle swam optimization (PSO) algorithm is adopted and a frequency split of 149 Hz is first achieved by this method. Then, after two steps of manual adjustment of the springs’ dimensions, the frequency gap is further decreased to 3 Hz. With the help of the finite element method (FEM) software ANSYS, the natural frequencies of drive, yaw, and pitch/roll modes are found to be 14,017 Hz, 14,018 Hz and 14,020 Hz, respectively. The cross-axis effect and scale factor of each mode are also simulated. All the simulation results are in good accordance with the theoretical analysis, which means the design is effective and worthy of further investigation on the integration of tri-axis accelerometers on the same single chip to form an inertial measurement unit. Full article

(This article belongs to the Section Physical Sensors)

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25 pages, 4475 KiB

Open AccessArticle

Real-Time Personalized Monitoring to Estimate Occupational Heat Stress in Ambient Assisted Working

by Pablo Pancardo^1,*, Francisco D. Acosta¹, José Adán Hernández-Nolasco¹

, Miguel A. Wister¹ and Diego López-de-Ipiña²

¹ Juarez Autonomous University of Tabasco, Carr. Cunduacan-Jalpa Km. 0.5, C.P. 86690, Cunduacan,Tabasco, Mexico

² DeustoTech - Deusto Institute of Technology, University of Deusto, Avda Universidades 24, Bilbao 48007, Spain

Sensors 2015, 15(7), 16956-16980; https://doi.org/10.3390/s150716956 - 13 Jul 2015

Cited by 29 | Viewed by 8522

Abstract

Ambient Assisted Working (AAW) is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers’ comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. [...] Read more.

Ambient Assisted Working (AAW) is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers’ comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. Occupational heat stress (OHS) happens when a worker is in an uninterrupted physical activity and in a hot environment. OHS can produce strain on the body, which leads to discomfort and eventually to heat illness and even death. Related ISO standards contain methods to estimate OHS and to ensure the safety and health of workers, but they are subjective, impersonal, performed a posteriori and even invasive. This paper focuses on the design and development of real-time personalized monitoring for a more effective and objective estimation of OHS, taking into account the individual user profile, fusing data from environmental and unobtrusive body sensors. Formulas employed in this work were taken from different domains and joined in the method that we propose. It is based on calculations that enable continuous surveillance of physical activity performance in a comfortable and healthy manner. In this proposal, we found that OHS can be estimated by satisfying the following criteria: objective, personalized, in situ, in real time, just in time and in an unobtrusive way. This enables timely notice for workers to make decisions based on objective information to control OHS. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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19 pages, 5094 KiB

Open AccessArticle

Visual Contrast Enhancement Algorithm Based on Histogram Equalization

by Chih-Chung Ting¹

, Bing-Fei Wu², Meng-Liang Chung^2,*, Chung-Cheng Chiu³ and Ya-Ching Wu³

¹ School of Defense Science, Chung Cheng Institute of Technology, National Defense University, Taoyuan 33551, Taiwan

² Institute of Electrical and Control Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

³ Department of Electrical and Electronic Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan 33551, Taiwan

Sensors 2015, 15(7), 16981-16999; https://doi.org/10.3390/s150716981 - 13 Jul 2015

Cited by 23 | Viewed by 8436

Abstract

Image enhancement techniques primarily improve the contrast of an image to lend it a better appearance. One of the popular enhancement methods is histogram equalization (HE) because of its simplicity and effectiveness. However, it is rarely applied to consumer electronics products because it [...] Read more.

Image enhancement techniques primarily improve the contrast of an image to lend it a better appearance. One of the popular enhancement methods is histogram equalization (HE) because of its simplicity and effectiveness. However, it is rarely applied to consumer electronics products because it can cause excessive contrast enhancement and feature loss problems. These problems make the images processed by HE look unnatural and introduce unwanted artifacts in them. In this study, a visual contrast enhancement algorithm (VCEA) based on HE is proposed. VCEA considers the requirements of the human visual perception in order to address the drawbacks of HE. It effectively solves the excessive contrast enhancement problem by adjusting the spaces between two adjacent gray values of the HE histogram. In addition, VCEA reduces the effects of the feature loss problem by using the obtained spaces. Furthermore, VCEA enhances the detailed textures of an image to generate an enhanced image with better visual quality. Experimental results show that images obtained by applying VCEA have higher contrast and are more suited to human visual perception than those processed by HE and other HE-based methods. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 798 KiB

Open AccessArticle

Ultrasonic Lateral Displacement Sensor for Health Monitoring in Seismically Isolated Buildings

by Iwao Matsuya^*

, Fumiya Matsumoto and Ikuo Ihara

Department of Mechanical Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka 940-2188, Niigata, Japan

Sensors 2015, 15(7), 17000-17012; https://doi.org/10.3390/s150717000 - 13 Jul 2015

Cited by 5 | Viewed by 6926

Abstract

An ultrasonic lateral displacement sensor utilizing air-coupled ultrasound transducers is proposed. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for measuring lateral displacement. The measurement system is composed of several air-coupled ultrasound transducers as a [...] Read more.

An ultrasonic lateral displacement sensor utilizing air-coupled ultrasound transducers is proposed. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for measuring lateral displacement. The measurement system is composed of several air-coupled ultrasound transducers as a receiver and several transmitters. The transmitters are immobilized at a fixed point, whereas the receiver set-up is separately arranged on the opposite side. In order to improve measurement accuracy, a correction method that utilizes polynomial approximation is introduced. The difference between the corrected lateral displacement and the reference displacement is estimated to be 0.2 mm at maximum for the two transmitters system. A good responsiveness is demonstrated by conducting a dynamic response experiment. When five transmitters are arranged, their measurement range is easily extended up to ±60 mm with an accuracy of 0.7 mm. In both cases, the fluctuations to the measurement ranges show less than 1%. These results indicate that the developed sensor system is useful for measuring relative lateral displacement of a seismically isolated building in the field of structural health monitoring. Full article

(This article belongs to the Special Issue Novel Sensors for Non-Destructive Testing and Structural Health Monitoring)

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23 pages, 1149 KiB

Open AccessArticle

Contextual Sensing: Integrating Contextual Information with Human and Technical Geo-Sensor Information for Smart Cities

by Günther Sagl^1,*, Bernd Resch^2,3,4

and Thomas Blaschke²

¹ Department of Geoinformation and Environmental Technologies, Carinthia University of Applied Sciences, Europastrasse 4, A-9524 Villach, Austria

² Department of Geoinformatics—Z_GIS, University of Salzburg, Schillerstrasse 30, A-5020 Salzburg, Austria

³ Department of Geography–Chair of GIScience, Heidelberg University, Berliner Strasse 48, D-69120 Heidelberg, Germany

⁴ Center for Geographic Analysis, Harvard University, 1737 Cambridge Street, Cambridge, MA 02138, USA

Sensors 2015, 15(7), 17013-17035; https://doi.org/10.3390/s150717013 - 14 Jul 2015

Cited by 72 | Viewed by 12914

Abstract

In this article we critically discuss the challenge of integrating contextual information, in particular spatiotemporal contextual information, with human and technical sensor information, which we approach from a geospatial perspective. We start by highlighting the significance of context in general and spatiotemporal context [...] Read more.

In this article we critically discuss the challenge of integrating contextual information, in particular spatiotemporal contextual information, with human and technical sensor information, which we approach from a geospatial perspective. We start by highlighting the significance of context in general and spatiotemporal context in particular and introduce a smart city model of interactions between humans, the environment, and technology, with context at the common interface. We then focus on both the intentional and the unintentional sensing capabilities of today’s technologies and discuss current technological trends that we consider have the ability to enrich human and technical geo-sensor information with contextual detail. The different types of sensors used to collect contextual information are analyzed and sorted into three groups on the basis of names considering frequently used related terms, and characteristic contextual parameters. These three groups, namely technical in situ sensors, technical remote sensors, and human sensors are analyzed and linked to three dimensions involved in sensing (data generation, geographic phenomena, and type of sensing). In contrast to other scientific publications, we found a large number of technologies and applications using in situ and mobile technical sensors within the context of smart cities, and surprisingly limited use of remote sensing approaches. In this article we further provide a critical discussion of possible impacts and influences of both technical and human sensing approaches on society, pointing out that a larger number of sensors, increased fusion of information, and the use of standardized data formats and interfaces will not necessarily result in any improvement in the quality of life of the citizens of a smart city. This article seeks to improve our understanding of technical and human geo-sensing capabilities, and to demonstrate that the use of such sensors can facilitate the integration of different types of contextual information, thus providing an additional, namely the geo-spatial perspective on the future development of smart cities. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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12 pages, 2793 KiB

Open AccessArticle

Top-Down CMOS-NEMS Polysilicon Nanowire with Piezoresistive Transduction

by Eloi Marigó¹, Marc Sansa², Francesc Pérez-Murano², Arantxa Uranga¹ and Núria Barniol^1,*

¹ Department of Electronics Engineering, Universitat Autònoma de Barcelona (UAB), Barcelona 08193, Spain

² Instituto de Microelectrónica de Barcelona (IMB-CNM-CSIC), Campus UAB, Barcelona 08193, Spain

Sensors 2015, 15(7), 17036-17047; https://doi.org/10.3390/s150717036 - 14 Jul 2015

Cited by 2 | Viewed by 5625

Abstract

A top-down clamped-clamped beam integrated in a CMOS technology with a cross section of 500 nm × 280 nm has been electrostatic actuated and sensed using two different transduction methods: capacitive and piezoresistive. The resonator made from a single polysilicon layer has a [...] Read more.

A top-down clamped-clamped beam integrated in a CMOS technology with a cross section of 500 nm × 280 nm has been electrostatic actuated and sensed using two different transduction methods: capacitive and piezoresistive. The resonator made from a single polysilicon layer has a fundamental in-plane resonance at 27 MHz. Piezoresistive transduction avoids the effect of the parasitic capacitance assessing the capability to use it and enhance the CMOS-NEMS resonators towards more efficient oscillator. The displacement derived from the capacitive transduction allows to compute the gauge factor for the polysilicon material available in the CMOS technology. Full article

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

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9 pages, 1424 KiB

Open AccessArticle

Integrating Paper Chromatography with Electrochemical Detection for the Trace Analysis of TNT in Soil

by Patrick Ryan¹, Daniel Zabetakis², David A. Stenger² and Scott A. Trammell^2,*

¹ Science and Engineering Apprenticeship Program, Naval Research Laboratory, Washington, DC 20375, USA

² Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375, USA

Sensors 2015, 15(7), 17048-17056; https://doi.org/10.3390/s150717048 - 14 Jul 2015

Cited by 20 | Viewed by 6835

Abstract

We report on the development of an electrochemical probe for the trace analysis of 2,4,6-trinitrotoluene (TNT) in soil samples. The probe is a combination of graphite electrodes, filter paper, with ethylene glycol and choline chloride as the solvent/electrolyte. Square wave chromatovoltammograms show the [...] Read more.

We report on the development of an electrochemical probe for the trace analysis of 2,4,6-trinitrotoluene (TNT) in soil samples. The probe is a combination of graphite electrodes, filter paper, with ethylene glycol and choline chloride as the solvent/electrolyte. Square wave chromatovoltammograms show the probes have a sensitivity for TNT of 0.75 nA/ng and a limit of detection of 100 ng. In addition, by taking advantage of the inherent paper chromatography step, TNT can be separated in both time and cathodic peak potential from 4-amino-dinitrotolene co-spotted on the probe or in soil samples with the presence of methyl parathion as a possible interferent. Full article

(This article belongs to the Section Chemical Sensors)

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19 pages, 967 KiB

Open AccessArticle

A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks

by Huifang Chen^1,2,*

, Linlin Ge¹ and Lei Xie^1,2

¹ Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China

² Zhejiang Provincial Key Laboratory of Information Network Technology, Hangzhou 310027, China

Sensors 2015, 15(7), 17057-17075; https://doi.org/10.3390/s150717057 - 14 Jul 2015

Cited by 20 | Viewed by 6457

Abstract

The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate [...] Read more.

The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 1323 KiB

Open AccessArticle

A Single-Chip CMOS Pulse Oximeter with On-Chip Lock-In Detection

by Diwei He¹, Stephen P. Morgan¹

, Dimitrios Trachanis², Jan Van Hese², Dimitris Drogoudis², Franco Fummi³, Francesco Stefanni³, Valerio Guarnieri³ and Barrie R. Hayes-Gill^1,*

¹ Electrical System and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK

² Keysight Technologies Belgium NV, Kortrijksesteenweg 1093 B, 9051 Sint Denijs Westrem, Belgium

³ EDALab-Networked Embedded Systems, Ca Vignal, 2-Strada Le Grazie, 15-37134 Verona, Italy

Sensors 2015, 15(7), 17076-17088; https://doi.org/10.3390/s150717076 - 14 Jul 2015

Cited by 17 | Viewed by 16457

Abstract

Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, [...] Read more.

Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations. With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise. In a breath hold and release experiment the single chip sensor demonstrates consistent and comparable performance to commercial pulse oximetry devices with a mean of 1.2% difference. The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring. Full article

(This article belongs to the Special Issue On-Chip Sensors)

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17 pages, 3130 KiB

Open AccessArticle

Intensity Variation Normalization for Finger Vein Recognition Using Guided Filter Based Singe Scale Retinex

by Shan Juan Xie¹, Yu Lu^2,*, Sook Yoon³, Jucheng Yang⁴ and Dong Sun Park²

¹ Institute of Remote Sensing and Earth Science, College of Science, Hangzhou Normal University, Hangzhou 311121, China

² Division of Electronic and Information Engineering, Chonbuk National University, Jeonju561-756, Korea

³ Department of Multimedia Engineering, Mokpo National University, Jeonnam534-729, Korea

⁴ College of Computer Science and Information Engineering, Tianjin University of Science and Technology, Tianjin 300222, China

Sensors 2015, 15(7), 17089-17105; https://doi.org/10.3390/s150717089 - 14 Jul 2015

Cited by 61 | Viewed by 8600

Abstract

Finger vein recognition has been considered one of the most promising biometrics for personal authentication. However, the capacities and percentages of finger tissues (e.g., bone, muscle, ligament, water, fat, etc.) vary person by person. This usually causes poor quality of finger vein [...] Read more.

Finger vein recognition has been considered one of the most promising biometrics for personal authentication. However, the capacities and percentages of finger tissues (e.g., bone, muscle, ligament, water, fat, etc.) vary person by person. This usually causes poor quality of finger vein images, therefore degrading the performance of finger vein recognition systems (FVRSs). In this paper, the intrinsic factors of finger tissue causing poor quality of finger vein images are analyzed, and an intensity variation (IV) normalization method using guided filter based single scale retinex (GFSSR) is proposed for finger vein image enhancement. The experimental results on two public datasets demonstrate the effectiveness of the proposed method in enhancing the image quality and finger vein recognition accuracy. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 3034 KiB

Open AccessArticle

An Exposed-Core Grapefruit Fibers Based Surface Plasmon Resonance Sensor

by Xianchao Yang, Ying Lu^*, Mintuo Wang and Jianquan Yao

College of Precision Instrument and Opto-Electronics Engineering, Key Laboratory of Opto-electronics Information Technology, Ministry of Education, Tianjin University, Tianjin 300072, China

Sensors 2015, 15(7), 17106-17114; https://doi.org/10.3390/s150717106 - 14 Jul 2015

Cited by 55 | Viewed by 6089

Abstract

To solve the problem of air hole coating and analyte filling in microstructured optical fiber-based surface plasmon resonance (SPR) sensors, we designed an exposed-core grapefruit fiber (EC-GFs)-based SPR sensor. The exposed section of the EC-GF is coated with a SPR, supporting thin silver [...] Read more.

To solve the problem of air hole coating and analyte filling in microstructured optical fiber-based surface plasmon resonance (SPR) sensors, we designed an exposed-core grapefruit fiber (EC-GFs)-based SPR sensor. The exposed section of the EC-GF is coated with a SPR, supporting thin silver film, which can sense the analyte in the external environment. The asymmetrically coated fiber can support two separate resonance peaks (x- and y-polarized peaks) with orthogonal polarizations and x-polarized peak, providing a much higher peak loss than y-polarized, also the x-polarized peak has higher wavelength and amplitude sensitivities. A large analyte refractive index (RI) range from 1.33 to 1.42 is calculated to investigate the sensing performance of the sensor, and an extremely high wavelength sensitivity of 13,500 nm/refractive index unit (RIU) is obtained. The silver layer thickness, which may affect the sensing performance, is also discussed. This work can provide a reference for developing a high sensitivity, real-time, fast-response, and distributed SPR RI sensor. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 3175 KiB

Open AccessArticle

Infrared and Visual Image Fusion through Fuzzy Measure and Alternating Operators

by Xiangzhi Bai^1,2

¹ Image Processing Center, Beijing University of Aeronautics and Astronautics, Beijing 100191, China

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

Sensors 2015, 15(7), 17149-17167; https://doi.org/10.3390/s150717149 - 15 Jul 2015

Cited by 9 | Viewed by 4846

Abstract

The crucial problem of infrared and visual image fusion is how to effectively extract the image features, including the image regions and details and combine these features into the final fusion result to produce a clear fused image. To obtain an effective fusion [...] Read more.

The crucial problem of infrared and visual image fusion is how to effectively extract the image features, including the image regions and details and combine these features into the final fusion result to produce a clear fused image. To obtain an effective fusion result with clear image details, an algorithm for infrared and visual image fusion through the fuzzy measure and alternating operators is proposed in this paper. Firstly, the alternating operators constructed using the opening and closing based toggle operator are analyzed. Secondly, two types of the constructed alternating operators are used to extract the multi-scale features of the original infrared and visual images for fusion. Thirdly, the extracted multi-scale features are combined through the fuzzy measure-based weight strategy to form the final fusion features. Finally, the final fusion features are incorporated with the original infrared and visual images using the contrast enlargement strategy. All the experimental results indicate that the proposed algorithm is effective for infrared and visual image fusion. Full article

(This article belongs to the Section Physical Sensors)

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27 pages, 1096 KiB

Open AccessArticle

MagicFinger: 3D Magnetic Fingerprints for Indoor Location

by Daniel Carrillo^*, Victoria Moreno, Benito Úbeda and Antonio F. Skarmeta

Department of Information and Communications Engineering, University of Murcia, 30100 Murcia, Spain

Sensors 2015, 15(7), 17168-17194; https://doi.org/10.3390/s150717168 - 15 Jul 2015

Cited by 23 | Viewed by 7411

Abstract

Given the indispensable role of mobile phones in everyday life, phone-centric sensing systems are ideal candidates for ubiquitous observation purposes. This paper presents a novel approach for mobile phone-centric observation applied to indoor location. The approach involves a location fingerprinting methodology that takes [...] Read more.

Given the indispensable role of mobile phones in everyday life, phone-centric sensing systems are ideal candidates for ubiquitous observation purposes. This paper presents a novel approach for mobile phone-centric observation applied to indoor location. The approach involves a location fingerprinting methodology that takes advantage of the presence of magnetic field anomalies inside buildings. Unlike existing work on the subject, which uses the intensity of magnetic field for fingerprinting, our approach uses all three components of the measured magnetic field vectors to improve accuracy. By using adequate soft computing techniques, it is possible to adequately balance the constraints of common solutions. The resulting system does not rely on any infrastructure devices and therefore is easy to manage and deploy. The proposed system consists of two phases: the offline phase and the online phase. In the offline phase, magnetic field measurements are taken throughout the building, and 3D maps are generated. Then, during the online phase, the user’s location is estimated through the best estimator for each zone of the building. Experimental evaluations carried out in two different buildings confirm the satisfactory performance of indoor location based on magnetic field vectors. These evaluations provided an error of (11.34 m, 4.78 m) in the (x; y) components of the estimated positions in the first building where the experiments were carried out, with a standard deviation of (3.41 m, 4.68 m); and in the second building, an error of (4 m, 2.98 m) with a deviation of (2.64 m, 2.33 m). Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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14 pages, 1062 KiB

Open AccessArticle

Robust Indoor Human Activity Recognition Using Wireless Signals

by Yi Wang^*, Xinli Jiang, Rongyu Cao and Xiyang Wang

School of Software, Dalian University of Technology, Dalian 116620, China

Sensors 2015, 15(7), 17195-17208; https://doi.org/10.3390/s150717195 - 15 Jul 2015

Cited by 67 | Viewed by 8187

Abstract

Wireless signals–based activity detection and recognition technology may be complementary to the existing vision-based methods, especially under the circumstance of occlusions, viewpoint change, complex background, lighting condition change, and so on. This paper explores the properties of the channel state information (CSI) of [...] Read more.

Wireless signals–based activity detection and recognition technology may be complementary to the existing vision-based methods, especially under the circumstance of occlusions, viewpoint change, complex background, lighting condition change, and so on. This paper explores the properties of the channel state information (CSI) of Wi-Fi signals, and presents a robust indoor daily human activity recognition framework with only one pair of transmission points (TP) and access points (AP). First of all, some indoor human actions are selected as primitive actions forming a training set. Then, an online filtering method is designed to make actions’ CSI curves smooth and allow them to contain enough pattern information. Each primitive action pattern can be segmented from the outliers of its multi-input multi-output (MIMO) signals by a proposed segmentation method. Lastly, in online activities recognition, by selecting proper features and Support Vector Machine (SVM) based multi-classification, activities constituted by primitive actions can be recognized insensitive to the locations, orientations, and speeds. Full article

(This article belongs to the Section Remote Sensors)

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23 pages, 724 KiB

Open AccessArticle

Marginalised Stacked Denoising Autoencoders for Robust Representation of Real-Time Multi-View Action Recognition

by Feng Gu^1,*, Francisco Flórez-Revuelta²

, Dorothy Monekosso¹ and Paolo Remagnino¹

¹ School of Computing and Information Systems, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UK

² Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road, Kingston upon Thames KT1 2EE, UK

Sensors 2015, 15(7), 17209-17231; https://doi.org/10.3390/s150717209 - 16 Jul 2015

Cited by 10 | Viewed by 7074

Abstract

Multi-view action recognition has gained a great interest in video surveillance, human computer interaction, and multimedia retrieval, where multiple cameras of different types are deployed to provide a complementary field of views. Fusion of multiple camera views evidently leads to more robust decisions [...] Read more.

Multi-view action recognition has gained a great interest in video surveillance, human computer interaction, and multimedia retrieval, where multiple cameras of different types are deployed to provide a complementary field of views. Fusion of multiple camera views evidently leads to more robust decisions on both tracking multiple targets and analysing complex human activities, especially where there are occlusions. In this paper, we incorporate the marginalised stacked denoising autoencoders (mSDA) algorithm to further improve the bag of words (BoWs) representation in terms of robustness and usefulness for multi-view action recognition. The resulting representations are fed into three simple fusion strategies as well as a multiple kernel learning algorithm at the classification stage. Based on the internal evaluation, the codebook size of BoWs and the number of layers of mSDA may not significantly affect recognition performance. According to results on three multi-view benchmark datasets, the proposed framework improves recognition performance across all three datasets and outputs record recognition performance, beating the state-of-art algorithms in the literature. It is also capable of performing real-time action recognition at a frame rate ranging from 33 to 45, which could be further improved by using more powerful machines in future applications. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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9 pages, 1412 KiB

Open AccessArticle

On-Chip Sensing of Thermoelectric Thin Film’s Merit

by Zhigang Xiao^1,* and Xiaoshan Zhu²

¹ Department of Electrical Engineering, Alabama A&M University, Normal, AL 35762, USA

² Department of Electrical and Biomedical Engineering, University of Nevada, Reno, NV 89557, USA

Sensors 2015, 15(7), 17232-17240; https://doi.org/10.3390/s150717232 - 16 Jul 2015

Cited by 12 | Viewed by 7003

Abstract

Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based [...] Read more.

Thermoelectric thin films have been widely explored for thermal-to-electrical energy conversion or solid-state cooling, because they can remove heat from integrated circuit (IC) chips or micro-electromechanical systems (MEMS) devices without involving any moving mechanical parts. In this paper, we report using silicon diode-based temperature sensors and specific thermoelectric devices to characterize the merit of thermoelectric thin films. The silicon diode temperature sensors and thermoelectric devices were fabricated using microfabrication techniques. Specifically, e-beam evaporation was used to grow the thermoelectric thin film of Sb₂Te₃ (100 nm thick). The Seebeck coefficient and the merit of the Sb₂Te₃ thin film were measured or determined. The fabrication of silicon diode temperature sensors and thermoelectric devices are compatible with the integrated circuit fabrication. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 3542 KiB

Open AccessArticle

Stimulating the Comfort of Textile Electrodes in Wearable Neuromuscular Electrical Stimulation

by Hui Zhou^1,2, Yi Lu³, Wanzhen Chen^1,2,4, Zhen Wu^1,2,5, Haiqing Zou⁶, Ludovic Krundel^1,2,7 and Guanglin Li^1,2,*

¹ Key Laboratory of Human-Machine Intelligence-Synergy Systems of Chinese Academy of Sciences, Shenzhen 518055, China

² Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

³ Shenzhen Engineering Lab for Brain Activity Mapping Technologies, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

⁴ Shenzhen Key Laboratory of Electromagnetic Control, Shenzhen University, Shenzhen 518060, China

⁵ Nanshan Hospital of Guangdong Medical College, Shenzhen 518052, China

⁶ Shenzhen Yingda Strong Technology Co., Ltd, Shenzhen 518112, China

⁷ Electronic Systems Design Laboratory, School of Electronic, Electrical, and Systems Engineering, Loughborough University, Loughborough LE11 3TU, UK

Sensors 2015, 15(7), 17241-17257; https://doi.org/10.3390/s150717241 - 16 Jul 2015

Cited by 59 | Viewed by 12666

Abstract

Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and [...] Read more.

Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and then its impedance spectroscopy, stimulation thresholds, and stimulation comfort were quantitatively assessed and compared with those of a wet textile electrode and a hydrogel electrode on healthy subjects. The equivalent circuit models and the finite element models of different types of electrode were built based on the measured impedance data of the electrodes to reveal the possible mechanism of electrical stimulation pain. Our results showed that the wet textile electrode could achieve similar stimulation performance as the hydrogel electrode in motor threshold and stimulation comfort. However, the dry textile electrode was found to have very low pain threshold and induced obvious cutaneous painful sensations during stimulation, in comparison to the wet and hydrogel electrodes. Indeed, the finite element modeling results showed that the activation function along the z direction at the depth of dermis epidermis junction of the dry textile electrode was significantly larger than that of the wet and hydrogel electrodes, thus resulting in stronger activation of pain sensing fibers. Future work will be done to make textile electrodes have similar stimulation performance and comfort as hydrogel electrodes. Full article

(This article belongs to the Section Biosensors)

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16 pages, 796 KiB

Open AccessArticle

Infrared Thermography to Evaluate Heat Tolerance in Different Genetic Groups of Lambs

by Concepta McManus^1,2, Eliandra Bianchini^1,†, Tiago Do Prado Paim^3,*,†, Flavia Gontijo De Lima^4,†, José Braccini Neto^2,†, Marlos Castanheira^4,†, Geisa Isilda Ferreira Esteves^1,†, Caio Cesar Cardoso^1,† and Vanessa Calderaro Dalcin^2,†

¹ Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília 70910-900, DF, Brasil

² Departamento de Zootecnia, Universidade Federal do Rio Grande do Sul, Porto Alegre 91540-000, Brasil

³ Instituto Federal de Educação, Ciência e Tecnologia Goiano–Campus Iporá, Iporá 76200-000, Brasil

⁴ Escola de Veterinária, Universidade Federal de Goiás, Goiânia, Goiás Paulo 74690-900, Brasil

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 17258-17273; https://doi.org/10.3390/s150717258 - 16 Jul 2015

Cited by 36 | Viewed by 6661

Abstract

Heat stress is considered a limiting factor for sheep production. We used information from physiological characteristics linked to heat tolerance to determine whether infrared thermography temperatures were able to separate groups of animals and determine the most important variables in this differentiation. Forty-eight [...] Read more.

Heat stress is considered a limiting factor for sheep production. We used information from physiological characteristics linked to heat tolerance to determine whether infrared thermography temperatures were able to separate groups of animals and determine the most important variables in this differentiation. Forty-eight four-month-old male lambs from eight genetic groups were used. Physiological (rectal temperature–RT, heart rate–HR, respiratory rate–RR) and blood traits, infrared thermography temperatures, heat tolerance indices, body measurements, weight and carcass traits were measured. Statistical analyses included variance, correlations, factor, discrimination and regression. Observing the correlations between physiological characteristics (RT, RR and HR) with temperatures measured by infrared thermography, regions for further studies should include the mean temperature of flank, nose and rump. Results show that there are strong relationships between thermograph measurements and RR, RT and HR in lambs, which are suggested to be directly correlated with heat tolerance capacity of the different genetic groups evaluated in this study. The assessment of body surface temperature measured by the thermograph could be used as a noninvasive tool to assess heat tolerance of the animals. Full article

(This article belongs to the Special Issue Frontiers in Infrared Photodetection)

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26 pages, 2026 KiB

Open AccessArticle

VisitSense: Sensing Place Visit Patterns from Ambient Radio on Smartphones for Targeted Mobile Ads in Shopping Malls

by Byoungjip Kim^1,†, Seungwoo Kang^2,*, Jin-Young Ha³ and Junehwa Song¹

¹ School of Computing, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong, Daejeon 305-338, Korea

² School of Computer Science and Engineering, Korea University of Technology and Education (KOREATECH), 1600 Chungjeol-ro, Cheonan, Chungcheong 330-708, Korea

³ Department of Computer and Communications Engineering, Kangwon National University (KNU), 1 Kangwondaehak-gil, Chuncheon, Gangwon 200-701, Korea

^† Dr. Byoungjip Kim is now with Samsung Electronics.

Sensors 2015, 15(7), 17274-17299; https://doi.org/10.3390/s150717274 - 16 Jul 2015

Cited by 6 | Viewed by 7348

Abstract

In this paper, we introduce a novel smartphone framework called VisitSense that automatically detects and predicts a smartphone user’s place visits from ambient radio to enable behavioral targeting for mobile ads in large shopping malls. VisitSense enables mobile app developers to adopt visit-pattern-aware [...] Read more.

In this paper, we introduce a novel smartphone framework called VisitSense that automatically detects and predicts a smartphone user’s place visits from ambient radio to enable behavioral targeting for mobile ads in large shopping malls. VisitSense enables mobile app developers to adopt visit-pattern-aware mobile advertising for shopping mall visitors in their apps. It also benefits mobile users by allowing them to receive highly relevant mobile ads that are aware of their place visit patterns in shopping malls. To achieve the goal, VisitSense employs accurate visit detection and prediction methods. For accurate visit detection, we develop a change-based detection method to take into consideration the stability change of ambient radio and the mobility change of users. It performs well in large shopping malls where ambient radio is quite noisy and causes existing algorithms to easily fail. In addition, we proposed a causality-based visit prediction model to capture the causality in the sequential visit patterns for effective prediction. We have developed a VisitSense prototype system, and a visit-pattern-aware mobile advertising application that is based on it. Furthermore, we deploy the system in the COEX Mall, one of the largest shopping malls in Korea, and conduct diverse experiments to show the effectiveness of VisitSense. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

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13 pages, 2358 KiB

Open AccessArticle

Design and Optimization of SiON Ring Resonator-Based Biosensors for Aflatoxin M1 Detection

by Romain Guider^1,*,†, Davide Gandolfi^1,†, Tatevik Chalyan¹

, Laura Pasquardini²

, Alina Samusenko^1,3, Georg Pucker³, Cecilia Pederzolli² and Lorenzo Pavesi¹

¹ Nanoscience Laboratory, Department of Physics, University of Trento, Via Sommarive 14, Povo (TN) 38123, Italy

² LaBSSAH, Fondazione Bruno Kessler, Via Sommarive 18, Povo (TN) 38123, Italy

³ Centre for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, Povo (TN) 38123, Italy

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 17300-17312; https://doi.org/10.3390/s150717300 - 16 Jul 2015

Cited by 45 | Viewed by 8031

Abstract

In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10⁻⁶ refractive index units (RIU). We tested various samples [...] Read more.

In this article, we designed and studied silicon oxynitride (SiON) microring-based photonic structures for biosensing applications. We designed waveguides, directional couplers, and racetrack resonators in order to measure refractive index changes smaller than 10⁻⁶ refractive index units (RIU). We tested various samples with different SiON refractive indexes as well as the waveguide dimensions for selecting the sensor with the best performance. Propagation losses and bending losses have been measured on test structures, along with a complete characterization of the resonator’s performances. Sensitivities and limit of detection (LOD) were also measured using glucose-water solutions and compared with expected results from simulations. Finally, we functionalized the resonator and performed sensing experiments with Aflatoxin M1 (AFM1). We were able to detect the binding of aflatoxin for concentrations as low as 12.5 nm. The results open up the path for designing cost-effective biosensors for a fast and reliable sensitive analysis of AFM1 in milk. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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16 pages, 1818 KiB

Open AccessArticle

Design of a High-Performance Micro Integrated Surface Plasmon Resonance Sensor Based on Silicon-On-Insulator Rib Waveguide Array

by Dengpeng Yuan, Ying Dong^*

, Yujin Liu and Tianjian Li

Graduate School at Shenzhen, Tsinghua University, J209A, Tsinghua Campus, University Town of Shenzhen, Shenzhen 518055, China

Sensors 2015, 15(7), 17313-17328; https://doi.org/10.3390/s150717313 - 16 Jul 2015

Cited by 21 | Viewed by 7417

Abstract

Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. [...] Read more.

Based on silicon-on-insulator (SOI) rib waveguide with large cross-section, a micro integrated surface plasmon resonance (SPR) biochemical sensor platform is proposed. SPR is excited at the deeply etched facet of the bend waveguide by the guiding mode and a bimetallic configuration is employed. With the advantages of SOI rib waveguide and the silicon microfabrication technology, an array of the SPR sensors can be composed to implement wavelength interrogation of the sensors’ output signal, so the spectrometer or other bulky and expensive equipment are not necessary, which enables the SPR sensor to realize the miniaturization and integration of the entire sensing system. The performances of the SPR sensor element are verified by using the two-dimensional finite-different time-domain method. The parameters of the sensor element and the array are optimized for the achievement of high performance for biochemical sensing application. As a typical example, a single bimetallic SPR sensor with 3 nm Au over 32 nm Al possesses a high sensitivity of 3.968 × 10⁴ nm/RIU, a detection-accuracy of 14.7 μm⁻¹. For a uniparted SPR sensor, it can achieve a detection limit of 5.04 × 10⁻⁷ RIU. With the relative power measurement accuracy of 0.01 dB, the refractive index variation of 1.14 × 10⁻⁵ RIU can be detected by the SPR sensor array. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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21 pages, 5257 KiB

Open AccessArticle

NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models

by Li-Ta Hsu^*, Yanlei Gu

and Shunsuke Kamijo

Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Sensors 2015, 15(7), 17329-17349; https://doi.org/10.3390/s150717329 - 17 Jul 2015

Cited by 106 | Viewed by 10351

Abstract

Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method [...] Read more.

Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively. Full article

(This article belongs to the Section Remote Sensors)

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Graphical abstract

16 pages, 798 KiB

Open AccessArticle

Heterogeneous Multiple Sensors Joint Tracking of Maneuvering Target in Clutter

by Panlong Wu¹, Xingxiu Li², Jianshou Kong^1,* and Jiale Liu¹

¹ Department of Automation, Nanjing University of Science and Technology, No.200, Xiaolingwei Street, Xuanwu District, Nanjing 210094, China

² Department of Science, Nanjing University of Science and Technology, No.200, Xiaolingwei Street, Xuanwu District, Nanjing 210094, China

Sensors 2015, 15(7), 17350-17365; https://doi.org/10.3390/s150717350 - 17 Jul 2015

Cited by 15 | Viewed by 5508

Abstract

To solve the problem of tracking maneuvering airborne targets in the presence of clutter, an improved interacting multiple model probability data association algorithm (IMMPDA-MDCM) using radar/IR sensors fusion is proposed. Under the architecture of the proposed algorithm, the radar/IR centralized fusion tracking scheme [...] Read more.

To solve the problem of tracking maneuvering airborne targets in the presence of clutter, an improved interacting multiple model probability data association algorithm (IMMPDA-MDCM) using radar/IR sensors fusion is proposed. Under the architecture of the proposed algorithm, the radar/IR centralized fusion tracking scheme of IMMPDA-MDCM is designed to guarantee the observability of the target state. The interacting multiple model (IMM) deals with the model switching. The modified debiased converted measurement (MDCM) filter accounts for non-linearity in the dynamic system models, and reduces the effect of measurement noise on the covariance effectively. The probability data association (PDA) handles data association and measurement uncertainties in clutter. The simulation results show that the proposed algorithm can improve the tracking precision for maneuvering target in clutters, and has higher tracking precision than the traditional IMMPDA based on EKF and IMMPDA based on DCM algorithm. Full article

(This article belongs to the Section Physical Sensors)

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31 pages, 1325 KiB

Open AccessArticle

AF-DHNN: Fuzzy Clustering and Inference-Based Node Fault Diagnosis Method for Fire Detection

by Shan Jin^1,2,5,*, Wen Cui^3,4, Zhigang Jin^1,5,*

and Ying Wang¹

¹ School of Electronic Information Engineering, Tianjin University, Tianjin 300072, China

² Fire Brigade of Hexi District, Tianjin 300222, China

³ School of Management, Tianjin Polytechnic University, Tianjin 300387, China

⁴ Nankai Hospital of Traditional Chinese Medicine, Tianjin 300102, China

⁵ Guangxi Experiment Center of Information Science, Guilin 541004, China

Sensors 2015, 15(7), 17366-17396; https://doi.org/10.3390/s150717366 - 17 Jul 2015

Cited by 5 | Viewed by 6724

Abstract

Wireless Sensor Networks (WSNs) have been utilized for node fault diagnosis in the fire detection field since the 1990s. However, the traditional methods have some problems, including complicated system structures, intensive computation needs, unsteady data detection and local minimum values. In this paper, [...] Read more.

Wireless Sensor Networks (WSNs) have been utilized for node fault diagnosis in the fire detection field since the 1990s. However, the traditional methods have some problems, including complicated system structures, intensive computation needs, unsteady data detection and local minimum values. In this paper, a new diagnosis mechanism for WSN nodes is proposed, which is based on fuzzy theory and an Adaptive Fuzzy Discrete Hopfield Neural Network (AF-DHNN). First, the original status of each sensor over time is obtained with two features. One is the root mean square of the filtered signal (FRMS), the other is the normalized summation of the positive amplitudes of the difference spectrum between the measured signal and the healthy one (NSDS). Secondly, distributed fuzzy inference is introduced. The evident abnormal nodes’ status is pre-alarmed to save time. Thirdly, according to the dimensions of the diagnostic data, an adaptive diagnostic status system is established with a Fuzzy C-Means Algorithm (FCMA) and Sorting and Classification Algorithm to reducing the complexity of the fault determination. Fourthly, a Discrete Hopfield Neural Network (DHNN) with iterations is improved with the optimization of the sensors’ detected status information and standard diagnostic levels, with which the associative memory is achieved, and the search efficiency is improved. The experimental results show that the AF-DHNN method can diagnose abnormal WSN node faults promptly and effectively, which improves the WSN reliability. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 7494 KiB

Open AccessArticle

Formation Flight of Multiple UAVs via Onboard Sensor Information Sharing

by Chulwoo Park, Namhoon Cho, Kyunghyun Lee and Youdan Kim^*

Department of Mechanical & Aerospace Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744, Korea

Sensors 2015, 15(7), 17397-17419; https://doi.org/10.3390/s150717397 - 17 Jul 2015

Cited by 37 | Viewed by 9919

Abstract

To monitor large areas or simultaneously measure multiple points, multiple unmanned aerial vehicles (UAVs) must be flown in formation. To perform such flights, sensor information generated by each UAV should be shared via communications. Although a variety of studies have focused on the [...] Read more.

To monitor large areas or simultaneously measure multiple points, multiple unmanned aerial vehicles (UAVs) must be flown in formation. To perform such flights, sensor information generated by each UAV should be shared via communications. Although a variety of studies have focused on the algorithms for formation flight, these studies have mainly demonstrated the performance of formation flight using numerical simulations or ground robots, which do not reflect the dynamic characteristics of UAVs. In this study, an onboard sensor information sharing system and formation flight algorithms for multiple UAVs are proposed. The communication delays of radiofrequency (RF) telemetry are analyzed to enable the implementation of the onboard sensor information sharing system. Using the sensor information sharing, the formation guidance law for multiple UAVs, which includes both a circular and close formation, is designed. The hardware system, which includes avionics and an airframe, is constructed for the proposed multi-UAV platform. A numerical simulation is performed to demonstrate the performance of the formation flight guidance and control system for multiple UAVs. Finally, a flight test is conducted to verify the proposed algorithm for the multi-UAV system. Full article

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

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13 pages, 1517 KiB

Open AccessArticle

A New Method to Evaluate Surface Defects with an Electromagnetic Acoustic Transducer

by Kang Zhang¹, Pengxing Yi^1,*, Yahui Li¹, Bing Hui¹ and Xuming Zhang²

¹ School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074, China

² School of Life Science & Technology, Huazhong University of Science & Technology, Wuhan 430074, China

Sensors 2015, 15(7), 17420-17432; https://doi.org/10.3390/s150717420 - 17 Jul 2015

Cited by 11 | Viewed by 5431

Abstract

Characterizing a surface defect is very crucial in non-destructive testing (NDT). We employ an electromagnetic acoustic transducer (EMAT) to detect the surface defect of a nonmagnetic material. An appropriate feature that can avoid the interference of the human factor is vital for evaluating [...] Read more.

Characterizing a surface defect is very crucial in non-destructive testing (NDT). We employ an electromagnetic acoustic transducer (EMAT) to detect the surface defect of a nonmagnetic material. An appropriate feature that can avoid the interference of the human factor is vital for evaluating the crack quantitatively. Moreover, it can also reduce the influence of other factors, such as the lift-off, during the testing. In this paper, we conduct experiments at various depths of surface cracks in an aluminum plate, and a new feature, lift-off slope (LOS), is put forward for the theoretical and experimental analyses of the lift-off effect on the receiving signals. Besides, by changing the lift-off between the receiving probe and the sample for testing, a new method is adopted to evaluate surface defects with the EMAT. Compared with other features, the theoretical and experimental results show that the feature lift-off slope has many advantages prior to the other features for evaluating the surface defect with the EMAT. This can reduce the lift-off effect of one probe. Meanwhile, it is not essential to measure the signal without defects. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 1383 KiB

Open AccessArticle

A Method for Oscillation Errors Restriction of SINS Based on Forecasted Time Series

by Lin Zhao^1,*, Jiushun Li¹, Jianhua Cheng¹, Chun Jia¹ and Qiufan Wang²

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

² Beijing Institute of Automatic Control Equipment, Beijing 100074, China

Sensors 2015, 15(7), 17433-17452; https://doi.org/10.3390/s150717433 - 17 Jul 2015

Cited by 9 | Viewed by 8087

Abstract

Continuity, real-time, and accuracy are the key technical indexes of evaluating comprehensive performance of a strapdown inertial navigation system (SINS). However, Schuler, Foucault, and Earth periodic oscillation errors significantly cut down the real-time accuracy of SINS. A method for oscillation error restriction of [...] Read more.

Continuity, real-time, and accuracy are the key technical indexes of evaluating comprehensive performance of a strapdown inertial navigation system (SINS). However, Schuler, Foucault, and Earth periodic oscillation errors significantly cut down the real-time accuracy of SINS. A method for oscillation error restriction of SINS based on forecasted time series is proposed by analyzing the characteristics of periodic oscillation errors. The innovative method gains multiple sets of navigation solutions with different phase delays in virtue of the forecasted time series acquired through the measurement data of the inertial measurement unit (IMU). With the help of curve-fitting based on least square method, the forecasted time series is obtained while distinguishing and removing small angular motion interference in the process of initial alignment. Finally, the periodic oscillation errors are restricted on account of the principle of eliminating the periodic oscillation signal with a half-wave delay by mean value. Simulation and test results show that the method has good performance in restricting the Schuler, Foucault, and Earth oscillation errors of SINS. Full article

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

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17 pages, 4560 KiB

Open AccessArticle

A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters

by Hanlun Li¹, Aiwu Zhang^1,* and Shaoxing Hu²

¹ Key Laboratory of 3D Information Acquisition and Application of Ministry, Capital Normal University, Beijing 100048, China

² School of Mechanical Engineering & Automation, Beihang University, Beijing 100083, China

Sensors 2015, 15(7), 17453-17469; https://doi.org/10.3390/s150717453 - 20 Jul 2015

Cited by 12 | Viewed by 6954

Abstract

This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and [...] Read more.

This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels. Full article

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

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13 pages, 823 KiB

Open AccessArticle

A Geospatial Semantic Enrichment and Query Service for Geotagged Photographs

by Andrew Ennis^1,*, Chris Nugent¹

, Philip Morrow², Liming Chen³, George Ioannidis⁴, Alexandru Stan⁴ and Preslav Rachev⁴

¹ School of Computing and Mathematics, University of Ulster, Coleraine BT370QB, UK

² School of Computing and Information Engineering, University of Ulster, Coleraine BT521SA, UK

³ School of Computer Science and Informatics, De Montfort University, Leicester LE19BH, UK

⁴ IN2 Search Interfaces Development Ltd., 22 Forth Street, Edinburgh EH13LH, UK

Sensors 2015, 15(7), 17470-17482; https://doi.org/10.3390/s150717470 - 20 Jul 2015

Cited by 4 | Viewed by 6112

Abstract

With the increasing abundance of technologies and smart devices, equipped with a multitude of sensors for sensing the environment around them, information creation and consumption has now become effortless. This, in particular, is the case for photographs with vast amounts being created and [...] Read more.

With the increasing abundance of technologies and smart devices, equipped with a multitude of sensors for sensing the environment around them, information creation and consumption has now become effortless. This, in particular, is the case for photographs with vast amounts being created and shared every day. For example, at the time of this writing, Instagram users upload 70 million photographs a day. Nevertheless, it still remains a challenge to discover the “right” information for the appropriate purpose. This paper describes an approach to create semantic geospatial metadata for photographs, which can facilitate photograph search and discovery. To achieve this we have developed and implemented a semantic geospatial data model by which a photograph can be enrich with geospatial metadata extracted from several geospatial data sources based on the raw low-level geo-metadata from a smartphone photograph. We present the details of our method and implementation for searching and querying the semantic geospatial metadata repository to enable a user or third party system to find the information they are looking for. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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12 pages, 1628 KiB

Open AccessArticle

Self-Balancing Position-Sensitive Detector (SBPSD)

by Ryan Porrazzo^*, Leigh Lydecker, Suhasini Gattu, Hassaram Bakhru, Natalya Tokranova and James Castracane

Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12222, USA

Sensors 2015, 15(7), 17483-17494; https://doi.org/10.3390/s150717483 - 20 Jul 2015

Cited by 6 | Viewed by 6647

Abstract

Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light [...] Read more.

Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light spot. An innovative type of optical position sensor was developed using two back-to-back connected photodiodes. These so called self-balancing position-sensitive detectors (SBPSDs) eliminate the need for external readout circuitry entirely. Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device. PSDs are commercially available only up to a length of 37 mm. Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 849 KiB

Open AccessArticle

Low Power Resistive Oxygen Sensor Based on Sonochemical SrTi_0.6Fe_0.4O_2.8 (STFO40)

by Alisa Stratulat¹, Bogdan-Catalin Serban^1,*, Andrea De Luca²

, Viorel Avramescu¹, Cornel Cobianu¹, Mihai Brezeanu¹, Octavian Buiu¹, Lucian Diamandescu³, Marcel Feder³, Syed Zeeshan Ali⁴ and Florin Udrea^2,4

¹ Honeywell Romania SRL, Sensors and Wireless Laboratory Bucharest (SWLB), Bucharest 020339, Romania

² Centre for Advanced Photonics and Electronics (CAPE), University of Cambridge, Cambridge CB3 0FA, UK

³ National Institute of Materials Physics, Bucharest-Magurele, P.O. Box. MG-7, Magurele 77125, Romania

⁴ Cambridge CMOS Sensors Ltd., Cambridge CB4 0DL, UK

Sensors 2015, 15(7), 17495-17506; https://doi.org/10.3390/s150717495 - 20 Jul 2015

Cited by 15 | Viewed by 6918

Abstract

The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi_0.6Fe_0.4O_2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results [...] Read more.

The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi_0.6Fe_0.4O_2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results are compared with commercially available SrTi_0.4Fe_0.6O_2.8 (STFO60) powder. In order to manufacture resistive oxygen sensors, both Sono-STFO40 and STFO60 are deposited, by dip-pen nanolithography (DPN) method, on an SOI (Silicon-on-Insulator) micro-hotplate, employing a tungsten heater embedded within a dielectric membrane. Oxygen detection tests are performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 16% (v/v), at a constant heater temperature of 650 °C. The oxygen sensor, based on the Sono-STFO40 sensing layer, shows good sensitivity, low power consumption (80 mW), and short response time (25 s). These performance are comparable to those exhibited by state-of-the-art O₂ sensors based on STFO60, thus proving Sono-STFO40 to be a material suitable for oxygen detection in harsh environments. Full article

(This article belongs to the Section Chemical Sensors)

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27 pages, 4855 KiB

Open AccessArticle

Evaluation of Fear Using Nonintrusive Measurement of Multimodal Sensors

by Jong-Suk Choi, Jae Won Bang, Hwan Heo and Kang Ryoung Park^*

Division of Electronics and Electrical Engineering, Dongguk University, 26 Pil-dong 3-ga, Jung-gu, Seoul 100-715, Korea

Sensors 2015, 15(7), 17507-17533; https://doi.org/10.3390/s150717507 - 20 Jul 2015

Cited by 29 | Viewed by 8880

Abstract

Most previous research into emotion recognition used either a single modality or multiple modalities of physiological signal. However, the former method allows for limited enhancement of accuracy, and the latter has the disadvantages that its performance can be affected by head or body [...] Read more.

Most previous research into emotion recognition used either a single modality or multiple modalities of physiological signal. However, the former method allows for limited enhancement of accuracy, and the latter has the disadvantages that its performance can be affected by head or body movements. Further, the latter causes inconvenience to the user due to the sensors attached to the body. Among various emotions, the accurate evaluation of fear is crucial in many applications, such as criminal psychology, intelligent surveillance systems and the objective evaluation of horror movies. Therefore, we propose a new method for evaluating fear based on nonintrusive measurements obtained using multiple sensors. Experimental results based on the t-test, the effect size and the sum of all of the correlation values with other modalities showed that facial temperature and subjective evaluation are more reliable than electroencephalogram (EEG) and eye blinking rate for the evaluation of fear. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 4871 KiB

Open AccessArticle

Collaborative WiFi Fingerprinting Using Sensor-Based Navigation on Smartphones

by Peng Zhang¹, Qile Zhao^1,*, You Li^1,2, Xiaoji Niu¹, Yuan Zhuang² and Jingnan Liu¹

¹ GNSS Research Center, Wuhan University, No.129 Luoyu Road, Wuhan 430079, China

² Department of Geomatics Engineering, University of Calgary, Calgary, AB T2N1N4, Canada

Sensors 2015, 15(7), 17534-17557; https://doi.org/10.3390/s150717534 - 20 Jul 2015

Cited by 31 | Viewed by 7968

Abstract

This paper presents a method that trains the WiFi fingerprint database using sensor-based navigation solutions. Since micro-electromechanical systems (MEMS) sensors provide only a short-term accuracy but suffer from the accuracy degradation with time, we restrict the time length of available indoor navigation trajectories, [...] Read more.

This paper presents a method that trains the WiFi fingerprint database using sensor-based navigation solutions. Since micro-electromechanical systems (MEMS) sensors provide only a short-term accuracy but suffer from the accuracy degradation with time, we restrict the time length of available indoor navigation trajectories, and conduct post-processing to improve the sensor-based navigation solution. Different middle-term navigation trajectories that move in and out of an indoor area are combined to make up the database. Furthermore, we evaluate the effect of WiFi database shifts on WiFi fingerprinting using the database generated by the proposed method. Results show that the fingerprinting errors will not increase linearly according to database (DB) errors in smartphone-based WiFi fingerprinting applications. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 3464 KiB

Open AccessArticle

Potentiometric NO₂ Sensors Based on Thin Stabilized Zirconia Electrolytes and Asymmetric (La_0.8Sr_0.2)_0.95MnO₃ Electrodes

by Jie Zou^1,2, Yangong Zheng¹, Junliang Li², Zhongliang Zhan^2,* and Jiawen Jian^1,*

¹ Gas Sensors & Sensing Technology Laboratory, College of Information Science and Engineering, Ningbo University, Ningbo 315211, China

² CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS), Shanghai 200050, China

Sensors 2015, 15(7), 17558-17571; https://doi.org/10.3390/s150717558 - 20 Jul 2015

Cited by 12 | Viewed by 7965

Abstract

Here we report on a new architecture for potentiometric NO₂ sensors that features thin 8YSZ electrolytes sandwiched between two porous (La_0.8Sr_0.2)_0.95MnO₃ (LSM95) layers—one thick and the other thin—fabricated by the tape casting and co-firing techniques. [...] Read more.

Here we report on a new architecture for potentiometric NO₂ sensors that features thin 8YSZ electrolytes sandwiched between two porous (La_0.8Sr_0.2)_0.95MnO₃ (LSM95) layers—one thick and the other thin—fabricated by the tape casting and co-firing techniques. Measurements of their sensing characteristics show that reducing the porosity of the supporting LSM95 reference electrodes can increase the response voltages. In the meanwhile, thin LSM95 layers perform better than Pt as the sensing electrode since the former can provide higher response voltages and better linear relationship between the sensitivities and the NO₂ concentrations over 40–1000 ppm. The best linear coefficient can be as high as 0.99 with a sensitivity value of 52 mV/decade as obtained at 500 °C. Analysis of the sensing mechanism suggests that the gas phase reactions within the porous LSM95 layers are critically important in determining the response voltages. Full article

(This article belongs to the Special Issue Gas Sensors—Designs and Applications)

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28 pages, 476 KiB

Open AccessArticle

Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks

by M. Isabel Vara and Celeste Campo^*

Department of Telematic Engineering, University Carlos III of Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid, Spain

Sensors 2015, 15(7), 17621-17648; https://doi.org/10.3390/s150717621 - 20 Jul 2015

Cited by 9 | Viewed by 6776

Abstract

Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering [...] Read more.

Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. Full article

(This article belongs to the Section Sensor Networks)

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27 pages, 3957 KiB

Open AccessArticle

Multiscale Trend Analysis for Pampa Grasslands Using Ground Data and Vegetation Sensor Imagery

by Fernando C. Scottá^* and Eliana L. Da Fonseca

Department of Geography, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, RS, Brazil

Sensors 2015, 15(7), 17666-17692; https://doi.org/10.3390/s150717666 - 21 Jul 2015

Cited by 22 | Viewed by 7468

Abstract

This study aimed to evaluate changes in the aboveground net primary productivity (ANPP) of grasslands in the Pampa biome by using experimental plots and changes in the spectral responses of similar vegetation communities obtained by remote sensing and to compare both datasets with [...] Read more.

This study aimed to evaluate changes in the aboveground net primary productivity (ANPP) of grasslands in the Pampa biome by using experimental plots and changes in the spectral responses of similar vegetation communities obtained by remote sensing and to compare both datasets with meteorological variations to validate the transition scales of the datasets. Two different geographic scales were considered in this study. At the local scale, an analysis of the climate and its direct influences on grassland ANPP was performed using data from a long-term experiment. At the regional scale, the influences of climate on the grassland reflectance patterns were determined using vegetation sensor imagery data. Overall, the monthly variations of vegetation canopy growth analysed using environmental changes (air temperature, total rainfall and total evapotranspiration) were similar. The results from the ANPP data and the NDVI data showed the that variations in grassland growth were similar and independent of the analysis scale, which indicated that local data and the relationships of local data with climate can be considered at the regional scale in the Pampa biome by using remote sensing. Full article

(This article belongs to the Section Remote Sensors)

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22 pages, 1460 KiB

Open AccessArticle

Fast T Wave Detection Calibrated by Clinical Knowledge with Annotation of P and T Waves

by Mohamed Elgendi^1,2,*

, Bjoern Eskofier³ and Derek Abbott⁴

¹ Electrical and Computer Engineering in Medicine Group, University of British Columbia and BC Children's Hospital, Vancouver, BC V6H 3N1, Canada

² Department of Computing Science, University of Alberta, Edmonton, AB T6G 2E8, Canada

³ Pattern Recognition Lab, Friedrich-Alexander University Erlangen-Nuernbeg, Haberstr. 2, 91058 Erlangen, Germany

⁴ School of Electrical and Electronic Engineering, University of Adelaide, Adelaide SA 5005, Australia

Sensors 2015, 15(7), 17693-17714; https://doi.org/10.3390/s150717693 - 21 Jul 2015

Cited by 45 | Viewed by 7853

Abstract

Background: There are limited studies on the automatic detection of T waves in arrhythmic electrocardiogram (ECG) signals. This is perhaps because there is no available arrhythmia dataset with annotated T waves. There is a growing need to develop numerically-efficient algorithms that can accommodate [...] Read more.

Background: There are limited studies on the automatic detection of T waves in arrhythmic electrocardiogram (ECG) signals. This is perhaps because there is no available arrhythmia dataset with annotated T waves. There is a growing need to develop numerically-efficient algorithms that can accommodate the new trend of battery-driven ECG devices. Moreover, there is also a need to analyze long-term recorded signals in a reliable and time-efficient manner, therefore improving the diagnostic ability of mobile devices and point-of-care technologies. Methods: Here, the T wave annotation of the well-known MIT-BIH arrhythmia database is discussed and provided. Moreover, a simple fast method for detecting T waves is introduced. A typical T wave detection method has been reduced to a basic approach consisting of two moving averages and dynamic thresholds. The dynamic thresholds were calibrated using four clinically known types of sinus node response to atrial premature depolarization (compensation, reset, interpolation, and reentry). Results: The determination of T wave peaks is performed and the proposed algorithm is evaluated on two well-known databases, the QT and MIT-BIH Arrhythmia databases. The detector obtained a sensitivity of 97.14% and a positive predictivity of 99.29% over the first lead of the validation databases (total of 221,186 beats). Conclusions: We present a simple yet very reliable T wave detection algorithm that can be potentially implemented on mobile battery-driven devices. In contrast to complex methods, it can be easily implemented in a digital filter design. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 2718 KiB

Open AccessArticle

Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO₃ in Selected Growing Media

by Seyed Alireza Ghaffari^1,†, William-O. Caron^2,†, Mathilde Loubier², Charles-O. Normandeau², Jeff Viens³, Mohammed S. Lamhamedi⁴, Benoit Gosselin¹ and Younes Messaddeq^2,3,5,*

¹ Department of Electrical and Computer Engineering, Laval University, Quebec, QC G1V 0A6, Canada

² Department of Chemistry, Laval University, Quebec, QC G1V 0A6, Canada

³ Centre for Optics, Photonics and Lasers (COPL), Laval University, Quebec, QC G1V 0A6, Canada

⁴ Ministère des Forêts, de la Faune et des Parcs. Quebec, G1P 3W8, Canada

⁵ JIRU Instituto de Quimica, Araraquara-SP 14800-060, Brazil

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 17715-17727; https://doi.org/10.3390/s150717715 - 21 Jul 2015

Cited by 16 | Viewed by 7968

Abstract

With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance [...] Read more.

With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO₃⁻ in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

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20 pages, 6797 KiB

Open AccessArticle

Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites

by Hongbo Dai^1,3, Erik T. Thostenson^2,3,† and Thomas Schumacher^1,3,*,†

¹ Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA

² Mechanical Engineering and Materials Science & Engineering, University of Delaware, Newark, DE 19716, USA

³ Center for Composite Materials, University of Delaware, Newark, DE 19716, USA

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 17728-17747; https://doi.org/10.3390/s150717728 - 21 Jul 2015

Cited by 66 | Viewed by 10911

Abstract

This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM). This novel strain sensor is fabricated using a [...] Read more.

This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM). This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT) onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity. Full article

(This article belongs to the Special Issue Novel Sensors for Non-Destructive Testing and Structural Health Monitoring)

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19 pages, 1207 KiB

Open AccessArticle

Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor

by Zhongyu Wang¹, Qiang Li^1,*, Zhuoran Wang¹ and Hu Yan²

¹ School of Instrument Science and Opto-Electronic Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China

² Beijing Changcheng Institute of Metrology and Measurement, Beijing 100095, China

Sensors 2015, 15(7), 17748-17766; https://doi.org/10.3390/s150717748 - 21 Jul 2015

Cited by 17 | Viewed by 7959

Abstract

Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true [...] Read more.

Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1252 KiB

Open AccessArticle

Discrimination of Rice with Different Pretreatment Methods by Using a Voltammetric Electronic Tongue

by Li Wang^1,*, Qunfeng Niu¹, Yanbo Hui¹ and Huali Jin²

¹ School of Electrical Engineering, Henan University of Technology, Zhengzhou 450007, China

² School of Food Science and Engineering, Henan University of Technology, Zhengzhou 450007, China

Sensors 2015, 15(7), 17767-17785; https://doi.org/10.3390/s150717767 - 22 Jul 2015

Cited by 20 | Viewed by 6525

Abstract

In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice [...] Read more.

In this study, an application of a voltammetric electronic tongue for discrimination and prediction of different varieties of rice was investigated. Different pretreatment methods were selected, which were subsequently used for the discrimination of different varieties of rice and prediction of unknown rice samples. To this aim, a voltammetric array of sensors based on metallic electrodes was used as the sensing part. The different samples were analyzed by cyclic voltammetry with two sample-pretreatment methods. Discriminant Factorial Analysis was used to visualize the different categories of rice samples; however, radial basis function (RBF) artificial neural network with leave-one-out cross-validation method was employed for prediction modeling. The collected signal data were first compressed employing fast Fourier transform (FFT) and then significant features were extracted from the voltammetric signals. The experimental results indicated that the sample solutions obtained by the non-crushed pretreatment method could efficiently meet the effect of discrimination and recognition. The satisfactory prediction results of voltammetric electronic tongue based on RBF artificial neural network were obtained with less than five-fold dilution of the sample solution. The main objective of this study was to develop primary research on the application of an electronic tongue system for the discrimination and prediction of solid foods and provide an objective assessment tool for the food industry. Full article

(This article belongs to the Section Physical Sensors)

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22 pages, 1670 KiB

Open AccessArticle

Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

by Drago Strle^1,*,†, Uroš Nahtigal¹, Graciele Batistell², Vincent Chi Zhang³, Erwin Ofner², Andrea Fant³ and Johannes Sturm^2,†

¹ University of Ljubljana, Electrical Engineering Department, Tržaška 25, Ljubljana 1000, Slovenia

² Carinthia University of Applied Sciences, Europastrasse 4, Villach 9585, Austria

³ Infineon Technologies Austria AG, Siemensstrae 2, Villach 9500, Austria

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 17786-17807; https://doi.org/10.3390/s150717786 - 22 Jul 2015

Cited by 6 | Viewed by 8572

Abstract

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP [...] Read more.

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm²of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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19 pages, 1503 KiB

Open AccessArticle

Real-Time PPP Based on the Coupling Estimation of Clock Bias and Orbit Error with Broadcast Ephemeris

by Shuguo Pan^1,*, Weirong Chen², Xiaodong Jin², Xiaofei Shi² and Fan He²

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

² School of Transportation, Southeast University, Nanjing 210096, China

Sensors 2015, 15(7), 17808-17826; https://doi.org/10.3390/s150717808 - 22 Jul 2015

Cited by 16 | Viewed by 6756

Abstract

Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance. However, real-time positioning service [...] Read more.

Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance. However, real-time positioning service will be the dominant mode in the future. IGS is providing such an operational service (RTS) and there are also commercial systems like Trimble RTX in operation. On the basis of the regional Continuous Operational Reference System (CORS), a real-time PPP algorithm is proposed to apply the coupling estimation of clock bias and orbit error. The projection of orbit error onto the satellite-receiver range has the same effects on positioning accuracy with clock bias. Therefore, in satellite clock estimation, part of the orbit error can be absorbed by the clock bias and the effects of residual orbit error on positioning accuracy can be weakened by the evenly distributed satellite geometry. In consideration of the simple structure of pseudorange equations and the high precision of carrier-phase equations, the clock bias estimation method coupled with orbit error is also improved. Rovers obtain PPP results by receiving broadcast ephemeris and real-time satellite clock bias coupled with orbit error. By applying the proposed algorithm, the precise orbit products provided by GNSS analysis centers are rendered no longer necessary. On the basis of previous theoretical analysis, a real-time PPP system was developed. Some experiments were then designed to verify this algorithm. Experimental results show that the newly proposed approach performs better than the traditional PPP based on International GNSS Service (IGS) real-time products. The positioning accuracies of the rovers inside and outside the network are improved by 38.8% and 36.1%, respectively. The PPP convergence speeds are improved by up to 61.4% and 65.9%. The new approach can change the traditional PPP mode because of its advantages of independence, high positioning precision, and real-time performance. It could be an alternative solution for regional positioning service before global PPP service comes into operation. Full article

(This article belongs to the Section Remote Sensors)

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Review

Jump to: Research, Other

30 pages, 928 KiB

Open AccessReview

Vision and Control for UAVs: A Survey of General Methods and of Inexpensive Platforms for Infrastructure Inspection

by Koppány Máthé^* and Lucian Buşoniu

Automation Department, Technical University of Cluj-Napoca, Memorandumului Street no. 28, 400114 Cluj-Napoca, Romania

Sensors 2015, 15(7), 14887-14916; https://doi.org/10.3390/s150714887 - 25 Jun 2015

Cited by 183 | Viewed by 15670

Abstract

Unmanned aerial vehicles (UAVs) have gained significant attention in recent years. Low-cost platforms using inexpensive sensor payloads have been shown to provide satisfactory flight and navigation capabilities. In this report, we survey vision and control methods that can be applied to low-cost UAVs, [...] Read more.

Unmanned aerial vehicles (UAVs) have gained significant attention in recent years. Low-cost platforms using inexpensive sensor payloads have been shown to provide satisfactory flight and navigation capabilities. In this report, we survey vision and control methods that can be applied to low-cost UAVs, and we list some popular inexpensive platforms and application fields where they are useful. We also highlight the sensor suites used where this information is available. We overview, among others, feature detection and tracking, optical flow and visual servoing, low-level stabilization and high-level planning methods. We then list popular low-cost UAVs, selecting mainly quadrotors. We discuss applications, restricting our focus to the field of infrastructure inspection. Finally, as an example, we formulate two use-cases for railway inspection, a less explored application field, and illustrate the usage of the vision and control techniques reviewed by selecting appropriate ones to tackle these use-cases. To select vision methods, we run a thorough set of experimental evaluations. Full article

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

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35 pages, 1361 KiB

Open AccessReview

Fruit and Vegetable Quality Assessment via Dielectric Sensing

by Dalia El Khaled^1,2,†

, Nuria Novas^1,2,†

, Jose A. Gazquez^1,2,†

, Rosa M. Garcia^1,2,†

and Francisco Manzano-Agugliaro^1,2,*,†

¹ Departmentof Engineering, University of Almería, 04120 Almería, Spain

² BITAL (Research Center on Agricultural and Food Biotechnology), University of Almeria, 04120 Almeria, Spain

^† These authors contributed equally to this work.

Sensors 2015, 15(7), 15363-15397; https://doi.org/10.3390/s150715363 - 29 Jun 2015

Cited by 81 | Viewed by 22688

Abstract

The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits [...] Read more.

The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose. Moreover, a focused study of dielectric spectroscopy and advanced dielectric sensing is a highly interesting topic. This review explains the dielectric property basics and classifies the dielectric spectroscopy measurement techniques. It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions. An in-depth definition of dielectric spectroscopy and its usefulness in the electric characterization of food materials is presented, along with the various sensor techniques used for dielectric measurements. The collective data are tabulated in a summary of the dielectric findings in horticultural field investigations, which will facilitate more advanced and focused explorations in the future. Full article

(This article belongs to the Special Issue Sensors for Food Safety and Quality)

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26 pages, 1824 KiB

Open AccessReview

Optical Fiber Sensors for Aircraft Structural Health Monitoring

by Iker García^1,*

, Joseba Zubia¹

, Gaizka Durana¹, Gotzon Aldabaldetreku¹

, María Asunción Illarramendi² and Joel Villatoro^1,3

¹ Department of Communications Engineering, E.T.S.I. of Bilbao, University of the Basque Country UPV/EHU, Alda. Urquijo s/n Bilbao 48013, Spain

² Department of Applied Physics I, E.T.S.I. of Bilbao, University of the Basque Country UPV/EHU, Alda. Urquijo s/n Bilbao 48013, Spain

³ IKERBASQUE—Basque Foundation for Science, E-48011 Bilbao, Spain

Sensors 2015, 15(7), 15494-15519; https://doi.org/10.3390/s150715494 - 30 Jun 2015

Cited by 195 | Viewed by 15064

Abstract

Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber [...] Read more.

Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel. Full article

(This article belongs to the Section Physical Sensors)

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33 pages, 2977 KiB

Open AccessReview

Localized Surface Plasmon Resonance Biosensing: Current Challenges and Approaches

by Sarah Unser, Ian Bruzas, Jie He and Laura Sagle^*

Department of Chemistry, College of Arts and Sciences, University of Cincinnati, 301 West Clifton Court, Cincinnati, OH 45221-0172, USA

Sensors 2015, 15(7), 15684-15716; https://doi.org/10.3390/s150715684 - 2 Jul 2015

Cited by 476 | Viewed by 26987

Abstract

Localized surface plasmon resonance (LSPR) has emerged as a leader among label-free biosensing techniques in that it offers sensitive, robust, and facile detection. Traditional LSPR-based biosensing utilizes the sensitivity of the plasmon frequency to changes in local index of refraction at the nanoparticle [...] Read more.

Localized surface plasmon resonance (LSPR) has emerged as a leader among label-free biosensing techniques in that it offers sensitive, robust, and facile detection. Traditional LSPR-based biosensing utilizes the sensitivity of the plasmon frequency to changes in local index of refraction at the nanoparticle surface. Although surface plasmon resonance technologies are now widely used to measure biomolecular interactions, several challenges remain. In this article, we have categorized these challenges into four categories: improving sensitivity and limit of detection, selectivity in complex biological solutions, sensitive detection of membrane-associated species, and the adaptation of sensing elements for point-of-care diagnostic devices. The first section of this article will involve a conceptual discussion of surface plasmon resonance and the factors affecting changes in optical signal detected. The following sections will discuss applications of LSPR biosensing with an emphasis on recent advances and approaches to overcome the four limitations mentioned above. First, improvements in limit of detection through various amplification strategies will be highlighted. The second section will involve advances to improve selectivity in complex media through self-assembled monolayers, “plasmon ruler” devices involving plasmonic coupling, and shape complementarity on the nanoparticle surface. The following section will describe various LSPR platforms designed for the sensitive detection of membrane-associated species. Finally, recent advances towards multiplexed and microfluidic LSPR-based devices for inexpensive, rapid, point-of-care diagnostics will be discussed. Full article

(This article belongs to the Special Issue Resonant Sensors and Sensor Fusion)

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21 pages, 1011 KiB

Open AccessReview

Evolution of RFID Applications in Construction: A Literature Review

by Enrique Valero^1,*

, Antonio Adán² and Carlos Cerrada³

¹ School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, UK

² Visual Computing and Robotics Lab, Universidad de Castilla-La Mancha, Paseo de la Universidad, 4, 13071 Ciudad Real, Spain

³ Escuela Técnica Superior de Ingeniería Informática, Universidad Nacional de Educación a Distancia, Juan del Rosal, 16, 28040 Madrid, Spain

Sensors 2015, 15(7), 15988-16008; https://doi.org/10.3390/s150715988 - 3 Jul 2015

Cited by 121 | Viewed by 17185

Abstract

Radio frequency identification (RFID) technology has been widely used in the field of construction during the last two decades. Basically, RFID facilitates the control on a wide variety of processes in different stages of the lifecycle of a building, from its conception to [...] Read more.

Radio frequency identification (RFID) technology has been widely used in the field of construction during the last two decades. Basically, RFID facilitates the control on a wide variety of processes in different stages of the lifecycle of a building, from its conception to its inhabitance. The main objective of this paper is to present a review of RFID applications in the construction industry, pointing out the existing developments, limitations and gaps. The paper presents the establishment of the RFID technology in four main stages of the lifecycle of a facility: planning and design, construction and commission and operation and maintenance. Concerning this last stage, an RFID application aiming to facilitate the identification of pieces of furniture in scanned inhabited environments is presented. Conclusions and future advances are presented at the end of the paper. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

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33 pages, 2089 KiB

Open AccessReview

Nucleic Acid Aptamers: An Emerging Tool for Biotechnology and Biomedical Sensing

by Ti-Hsuan Ku¹, Tiantian Zhang², Hua Luo^1,3,4, Tony M. Yen⁵, Ping-Wei Chen⁶, Yuanyuan Han¹ and Yu-Hwa Lo^1,*

¹ Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093-0407, USA

² Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093-0418, USA

³ College of Basic Medicine and Forensic Medicine, Sichuan University, Chengdu 610041, China

⁴ College of Manufacturing Science and Engineering, Sichuan University, Chengdu 610041, China

⁵ Department of Bioengineering, University of California San Diego, La Jolla, CA 92093-0412, USA

⁶ Chemical Engineering Program, University of California San Diego, La Jolla, CA 92093-0448, USA

Sensors 2015, 15(7), 16281-16313; https://doi.org/10.3390/s150716281 - 6 Jul 2015

Cited by 160 | Viewed by 15402

Abstract

Detection of small molecules or proteins of living cells provides an exceptional opportunity to study genetic variations and functions, cellular behaviors, and various diseases including cancer and microbial infections. Our aim in this review is to give an overview of selected research activities [...] Read more.

Detection of small molecules or proteins of living cells provides an exceptional opportunity to study genetic variations and functions, cellular behaviors, and various diseases including cancer and microbial infections. Our aim in this review is to give an overview of selected research activities related to nucleic acid-based aptamer techniques that have been reported in the past two decades. Limitations of aptamers and possible approaches to overcome these limitations are also discussed. Full article

(This article belongs to the Special Issue Resonant Sensors and Sensor Fusion)

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20 pages, 473 KiB

Open AccessReview

Sparse Recovery Optimization in Wireless Sensor Networks with a Sub-Nyquist Sampling Rate

by Davide Brunelli^1,*

and Carlo Caione²

¹ University of Trento, Via Sommarive 9, Trento I-38122, Italy

² University of Bologna, Viale Risorgimento 2, Bologna I-40136, Italy

Sensors 2015, 15(7), 16654-16673; https://doi.org/10.3390/s150716654 - 10 Jul 2015

Cited by 40 | Viewed by 5414

Abstract

Compressive sensing (CS) is a new technology in digital signal processing capable of high-resolution capture of physical signals from few measurements, which promises impressive improvements in the field of wireless sensor networks (WSNs). In this work, we extensively investigate the effectiveness of compressive [...] Read more.

Compressive sensing (CS) is a new technology in digital signal processing capable of high-resolution capture of physical signals from few measurements, which promises impressive improvements in the field of wireless sensor networks (WSNs). In this work, we extensively investigate the effectiveness of compressive sensing (CS) when real COTSresource-constrained sensor nodes are used for compression, evaluating how the different parameters can affect the energy consumption and the lifetime of the device. Using data from a real dataset, we compare an implementation of CS using dense encoding matrices, where samples are gathered at a Nyquist rate, with the reconstruction of signals sampled at a sub-Nyquist rate. The quality of recovery is addressed, and several algorithms are used for reconstruction exploiting the intra- and inter-signal correlation structures. We finally define an optimal under-sampling ratio and reconstruction algorithm capable of achieving the best reconstruction at the minimum energy spent for the compression. The results are verified against a set of different kinds of sensors on several nodes used for environmental monitoring. Full article

(This article belongs to the Section Sensor Networks)

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34 pages, 1178 KiB

Open AccessReview

Optical Fibre Pressure Sensors in Medical Applications

by Sven Poeggel^1,*, Daniele Tosi²

, DineshBabu Duraibabu¹

, Gabriel Leen¹

, Deirdre McGrath³ and Elfed Lewis^1,*

¹ Optical Fibre Sensors Research Centre, University of Limerick, Limerick, Ireland

² School of Engineering, Nazarbayev University, Astana 010000, Kazakhstan

³ Graduate Entry Medical School, University of Limerick, Limerick, Ireland

Sensors 2015, 15(7), 17115-17148; https://doi.org/10.3390/s150717115 - 15 Jul 2015

Cited by 185 | Viewed by 25168

Abstract

This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of [...] Read more.

This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

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49 pages, 3638 KiB

Open AccessReview

Wireless Sensor Network Optimization: Multi-Objective Paradigm

by Muhammad Iqbal¹, Muhammad Naeem^1,2, Alagan Anpalagan^2,*, Ashfaq Ahmed¹ and Muhammad Azam¹

¹ Department of Electrical Engineering, COMSATS Institute of Information Technology, Wah Campus, Wah Cantt 47040, Pakistan

² Department of Electrical and Computer Engineering, Ryerson University, Toronto,ON M5B 2K3, Canada

Sensors 2015, 15(7), 17572-17620; https://doi.org/10.3390/s150717572 - 20 Jul 2015

Cited by 120 | Viewed by 17225

Abstract

Optimization problems relating to wireless sensor network planning, design, deployment and operation often give rise to multi-objective optimization formulations where multiple desirable objectives compete with each other and the decision maker has to select one of the tradeoff solutions. These multiple objectives may [...] Read more.

Optimization problems relating to wireless sensor network planning, design, deployment and operation often give rise to multi-objective optimization formulations where multiple desirable objectives compete with each other and the decision maker has to select one of the tradeoff solutions. These multiple objectives may or may not conflict with each other. Keeping in view the nature of the application, the sensing scenario and input/output of the problem, the type of optimization problem changes. To address different nature of optimization problems relating to wireless sensor network design, deployment, operation, planing and placement, there exist a plethora of optimization solution types. We review and analyze different desirable objectives to show whether they conflict with each other, support each other or they are design dependent. We also present a generic multi-objective optimization problem relating to wireless sensor network which consists of input variables, required output, objectives and constraints. A list of constraints is also presented to give an overview of different constraints which are considered while formulating the optimization problems in wireless sensor networks. Keeping in view the multi facet coverage of this article relating to multi-objective optimization, this will open up new avenues of research in the area of multi-objective optimization relating to wireless sensor networks. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 3300 KiB

Open AccessReview

Interferometric Reflectance Imaging Sensor (IRIS)—A Platform Technology for Multiplexed Diagnostics and Digital Detection

by Oguzhan Avci¹, Nese Lortlar Ünlü^2,3, Ayça Yalçın Özkumur³ and M. Selim Ünlü^1,2,*

¹ Department of Electrical and Computer Engineering, Boston University, 8 St. Mary's Street, Boston, MA 02215, USA

² Department of Biomedical Engineering, Boston University, 8 St. Mary's Street, Boston, MA 02215, USA

³ Department of Electrical and Electronics Engineering and School of Medicine, Bahcesehir University, Ciragan Caddesi, No:4-6, Besiktas, Istanbul 34353, Turkey

Sensors 2015, 15(7), 17649-17665; https://doi.org/10.3390/s150717649 - 20 Jul 2015

Cited by 91 | Viewed by 15570

Abstract

Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can [...] Read more.

Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can lay the foundations for future generation diagnostics by providing means to detect biomarkers in a highly sensitive, specific, quantitative and multiplexed fashion. Here, we review an optical sensing technology, Interferometric Reflectance Imaging Sensor (IRIS), and the relevant features of this multifunctional platform for quantitative, label-free and dynamic detection. We discuss two distinct modalities for IRIS: (i) low-magnification (ensemble biomolecular mass measurements) and (ii) high-magnification (digital detection of individual nanoparticles) along with their applications, including label-free detection of multiplexed protein chips, measurement of single nucleotide polymorphism, quantification of transcription factor DNA binding, and high sensitivity digital sensing and characterization of nanoparticles and viruses. Full article

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

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7 pages, 1480 KiB

Open AccessBrief Report

Non-Invasive Optical Sensor Based Approaches for Monitoring Virus Culture to Minimize BSL3 Laboratory Entry

by Viswanath Ragupathy¹, Mohan Kumar Hayuri Giri Setty¹, Yordan Kostov², Xudong Ge², Shaunak Uplekar², Indira Hewlett^1,* and Govind Rao^2,*

¹ LMV/DETTD/OBRR/CBER/FDA, Silver Spring, MD 20993, USA

² Center for Advanced Sensor Technology and Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, MD 21250, USA

Sensors 2015, 15(7), 14864-14870; https://doi.org/10.3390/s150714864 - 24 Jun 2015

Cited by 1 | Viewed by 5151

Abstract

High titers of infectious viruses for vaccine and diagnostic reference panel development are made by infecting susceptible mammalian cells. Laboratory procedures are strictly performed in a Bio-Safety Level-3 (BSL3) laboratory and each entry and exit involves the use of disposable Personnel Protective Equipment [...] Read more.

High titers of infectious viruses for vaccine and diagnostic reference panel development are made by infecting susceptible mammalian cells. Laboratory procedures are strictly performed in a Bio-Safety Level-3 (BSL3) laboratory and each entry and exit involves the use of disposable Personnel Protective Equipment (PPE) to observe cell culture conditions. Routine PPE use involves significant recurring costs. Alternative non-invasive optical sensor based approaches to remotely monitor cell culture may provide a promising and cost effective approach to monitor infectious virus cultures resulting in lower disruption and costs. We report here the monitoring of high titer cultures of Human Immunodeficiency Virus-1 (HIV-1) and Herpes Simplex Virus-2 (HSV-2) remotely with the use of optical oxygen sensors aseptically placed inside the cell culture vessel. The replacement of culture media for cell and virus propagation and virus load monitoring was effectively performed using this fluorescent sensor and resulted in half the number of visits to the BSL3 lab (five versus ten). Full article

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

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1 pages, 602 KiB

Open AccessAddendum

Addendum: Pardo, J.; Zamora-Martínez, F.; Botella-Rocamora, P. Online Learning Algorithm for Time Series Forecasting Suitable for Low Cost Wireless Sensor Networks Nodes. Sensors 2015, 15, 9277–9304

by Juan Pardo^*, Francisco Zamora-Martínez and Paloma Botella-Rocamora

ESAI—Embedded Systems and Artificial Intelligence Group, Escuela Superior de Enseñanzas Técnicas, Universidad CEU Cardenal Herrera, C/San Bartolomé, 46115 Alfara del Patriarca, Valencia, Spain

Sensors 2015, 15(7), 16831; https://doi.org/10.3390/s150716831 - 13 Jul 2015

Viewed by 3585

Abstract

This work has been supported by the Consolidación de indicadores CEU-UCH2014-15 program of the Vicerrectorado de Investigación at Universidad CEU-Cardenal Herrera and financed by Generalitat Valenciana through Conselleria de Educación, Cultura y Deporte under project GV/2015/088. [...] Full article

1 pages, 601 KiB

Open AccessAddendum

Addendum: Pinto, M.; Gámez, N.; Fuentes, L.; Amor, M.; Horcas, J.M.; Ayala, I. Dynamic Reconfiguration of Security Policies in Wireless Sensor Networks. Sensors 2015, 15, 5251–5280

by Mónica Pinto^*, Nadia Gámez, Lidia Fuentes, Mercedes Amor, José Miguel Horcas and Inmaculada Ayala

Departamento de Lenguajes y Ciencias de la Computación, University of Málaga, Andalucía Tech, Málaga 29071, Spain

Sensors 2015, 15(7), 16832; https://doi.org/10.3390/s150716832 - 13 Jul 2015

Viewed by 3724

Abstract

The authors wish to update the Acknowledgments in their paper published in Sensors [1], doi:10.3390/s150305251, website: https://www.mdpi.com/1424-8220/15/3/5251. [...] Full article

(This article belongs to the Section Sensor Networks)

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Sensors, Volume 15, Issue 7 (July 2015) – 152 articles , Pages 14830-17826

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