Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Fibre Tip Sensor with Embedded FBG-LPG for Temperature and Refractive Index Determination by means of the Simple Measurement of the FBG Characteristics Thu, 26 Mar 2015 13:20:47 +0000 http://www.hindawi.com/journals/js/2015/491391/ A novel optical fibre sensing system based on a hybrid long period grating (LPG) and Bragg grating (FBG) configuration is proposed and demonstrated experimentally. The hybrid configuration, which uses the difference in temperature and refractive index (RI) different response of a Bragg grating and a long period grating, makes it possible to discriminate simultaneously the temperature and the refractive index of different aqueous solutions. RI (1.33 RIU–1.40 RIU) and temperature (21°C–28°C) working ranges have been experimentally determined. Experimental results show that the maximum accuracy in the refractive index measurement (0.004 RIU) with temperature compensation has been achieved within the working ranges. C. Berrettoni, C. Trono, V. Vignoli, and F. Baldini Copyright © 2015 C. Berrettoni et al. All rights reserved. Combination of Evidence with Different Weighting Factors: A Novel Probabilistic-Based Dissimilarity Measure Approach Thu, 26 Mar 2015 07:37:13 +0000 http://www.hindawi.com/journals/js/2015/509385/ To solve the invalidation problem of Dempster-Shafer theory of evidence (DS) with high conflict in multisensor data fusion, this paper presents a novel combination approach of conflict evidence with different weighting factors using a new probabilistic dissimilarity measure. Firstly, an improved probabilistic transformation function is proposed to map basic belief assignments (BBAs) to probabilities. Then, a new dissimilarity measure integrating fuzzy nearness and introduced correlation coefficient is proposed to characterize not only the difference between basic belief functions (BBAs) but also the divergence degree of the hypothesis that two BBAs support. Finally, the weighting factors used to reassign conflicts on BBAs are developed and Dempster’s rule is chosen to combine the discounted sources. Simple numerical examples are employed to demonstrate the merit of the proposed method. Through analysis and comparison of the results, the new combination approach can effectively solve the problem of conflict management with better convergence performance and robustness. Mengmeng Ma and Jiyao An Copyright © 2015 Mengmeng Ma and Jiyao An. All rights reserved. Modelling and Numerical Simulations of In-Air Reverberation Images for Fault Detection in Medical Ultrasonic Transducers: A Feasibility Study Wed, 25 Mar 2015 10:06:33 +0000 http://www.hindawi.com/journals/js/2015/796439/ A simplified two-dimensional finite element model which simulates the in-air reverberation image produced by medical ultrasonic transducers has been developed. The model simulates a linear array consisting of 128 PZT-5A crystals, a tungsten-epoxy backing layer, an Araldite matching layer, and a Perspex lens layer. The thickness of the crystal layer is chosen to simulate pulses centered at 4 MHz. The model is used to investigate whether changes in the electromechanical properties of the individual transducer layers (backing layer, crystal layer, matching layer, and lens layer) have an effect on the simulated in-air reverberation image generated. Changes in the electromechanical properties are designed to simulate typical medical transducer faults such as crystal drop-out, lens delamination, and deterioration in piezoelectric efficiency. The simulations demonstrate that fault-related changes in transducer behaviour can be observed in the simulated in-air reverberation image pattern. This exploratory approach may help to provide insight into deterioration in transducer performance and help with early detection of faults. W. Kochański, M. Boeff, Z. Hashemiyan, W. J. Staszewski, and P. K. Verma Copyright © 2015 W. Kochański et al. All rights reserved. A Survey on Spectrum Utilization in Wireless Sensor Networks Mon, 23 Mar 2015 11:17:10 +0000 http://www.hindawi.com/journals/js/2015/624610/ In recent years, the industrial, scientific, and medical (ISM) bands have been intensively shared with unlicensed wireless communications applications such as wireless sensor networks (WSNs). With flourishing popularity of sensor devices and increasing installation of wireless sensor nodes, the cross technology interference (CTI) has become a considerable real-world problem. Because of CTI, wireless devices suffer significant communication dilemma. Moreover, ISM band, as the main communication medium of WSN, should be reasonably utilized in an efficient and effective manner. Extensive approaches have been proposed to explore spectrum utilization in WSN. However, there is no such one, which systematically organizes these works. In this paper, we present a comprehensive survey on spectrum utilization in WSNs. To achieve this goal, We first illustrate the background of WSN and spectrum utilization. Our concern on CTI is then noted. Later we demonstrate the importance of efficient spectrum utilization. Eventually, through classification and summary of recent related works, we provide an essential structure of research in titled field and detailed intellectual merits of published works. Our survey covers more than 80 studies in the scope of spectrum utilization in WSN. Hongyao Luo, Zhichuan Huang, and Ting Zhu Copyright © 2015 Hongyao Luo et al. All rights reserved. Differentiation of Eight Commercial Mushrooms by Electronic Nose and Gas Chromatography-Mass Spectrometry Thu, 19 Mar 2015 09:13:38 +0000 http://www.hindawi.com/journals/js/2015/374013/ Volatile profiles of eight mushrooms were characterized by gas chromatography-mass spectrometry and electronic nose analysis. Volatile compounds including 11 alcohols, 11 ketones, 15 aldehydes, 3 sulfur compounds and alkenes, 8 terpenes, 7 acid and esters, 5 heterocyclic compounds, 20 aromatic compounds, and 4 other compounds were identified. The overall aroma properties of the mushrooms were analyzed by the electronic nose. Results indicated that the e-nose sensors have the ability to accurately respond to different mushrooms with similar fingerprint chromatograms. The relationship between the GC-MS data and e-nose responses of different mushrooms was modeled by principal component analysis and partial least squares regression. This combination for the volatile analysis with chemometric methods can be applied to distinguish different mushrooms successfully. Furthermore, it is concluded that the volatile composition of commercial mushrooms could benefit a finger spectrum by e-nose to identify the species of edible fungi. Jinjie Zhou, Tao Feng, and Ran Ye Copyright © 2015 Jinjie Zhou et al. All rights reserved. Internet of Vehicles for E-Health Applications in View of EMI on Medical Sensors Tue, 17 Mar 2015 07:37:16 +0000 http://www.hindawi.com/journals/js/2015/315948/ Wireless technologies are pervasive to support ubiquitous healthcare applications. However, RF transmission in wireless technologies can lead to electromagnetic interference (EMI) on medical sensors under a healthcare scenario, and a high level of EMI may lead to a critical malfunction of medical sensors. In view of EMI to medical sensors, we propose a joint power and rate control algorithm under game theoretic framework to schedule data transmission at each of wireless sensors. The objective of such a game is to maximize the utility of each wireless user subject to the EMI constraints for medical sensors. We show that the proposed game has a unique Nash equilibrium and our joint power and rate control algorithm would converge to the Nash equilibrium. Numerical results illustrate that the proposed algorithm can achieve robust performance against the variations of mobile hospital environments. Di Lin, Xuanli Wu, Fabrice Labeau, and Athanasios Vasilakos Copyright © 2015 Di Lin et al. All rights reserved. Toxicity Biosensor for Sodium Dodecyl Sulfate Using Immobilized Green Fluorescent Protein Expressing Escherichia coli Tue, 17 Mar 2015 07:21:39 +0000 http://www.hindawi.com/journals/js/2015/809065/ Green fluorescent protein (GFP) is suitable as a toxicity sensor due to its ability to work alone without cofactors or substrates. Its reaction with toxicants can be determined with fluorometric approaches. GFP mutant gene (C48S/S147C/Q204C/S65T/Q80R) is used because it has higher sensitivity compared to others GFP variants. A novel sodium dodecyl sulfate (SDS) toxicity detection biosensor was built by immobilizing GFP expressing Escherichia coli in k-Carrageenan matrix. Cytotoxicity effect took place in the toxicity biosensor which leads to the decrease in the fluorescence intensity. The fabricated E. coli GFP toxicity biosensor has a wide dynamic range of 4–100 ppm, with LOD of 1.7 ppm. Besides, it possesses short response time (<1 min), high reproducibility (0.76% RSD) and repeatability (0.72% RSD, ), and long-term stability (46 days). E. coli GFP toxicity biosensor has been applied to detect toxicity induced by SDS in tap water, river water, and drinking water. High recovery levels of SDS indicated the applicability of E. coli GFP toxicity biosensor in real water samples toxicity evaluation. Lia Ooi, Lee Yook Heng, and Asmat Ahmad Copyright © 2015 Lia Ooi et al. All rights reserved. A Bilinear Pairing-Based Dynamic Key Management and Authentication for Wireless Sensor Networks Sun, 15 Mar 2015 08:12:40 +0000 http://www.hindawi.com/journals/js/2015/534657/ In recent years, wireless sensor networks have been used in a variety of environments; a wireless network infrastructure, established to communicate and exchange information in a monitoring area, has also been applied in different environments. However, for sensitive applications, security is the paramount issue. In this paper, we propose using bilinear pairing to design dynamic key management and authentication scheme of the hierarchical sensor network. We use the dynamic key management and the pairing-based cryptography (PBC) to establish the session key and the hash message authentication code (HMAC) to support the mutual authentication between the sensors and the base station. In addition, we also embed the capability of the Global Positioning System (GPS) to cluster nodes to find the best path of the sensor network. The proposed scheme can also provide the requisite security of the dynamic key management, mutual authentication, and session key protection. Our scheme can defend against impersonation attack, replay attack, wormhole attack, and message manipulation attack. Chin-Ling Chen, Tzay-Farn Shih, Yu-Ting Tsai, and De-Kui Li Copyright © 2015 Chin-Ling Chen et al. All rights reserved. A System of Driving Fatigue Detection Based on Machine Vision and Its Application on Smart Device Sun, 15 Mar 2015 07:15:51 +0000 http://www.hindawi.com/journals/js/2015/548602/ Driving fatigue is one of the most important factors in traffic accidents. In this paper, we proposed an improved strategy and practical system to detect driving fatigue based on machine vision and Adaboost algorithm. Kinds of face and eye classifiers are well trained by Adaboost algorithm in advance. The proposed strategy firstly detects face efficiently by classifiers of front face and deflected face. Then, candidate region of eye is determined according to geometric distribution of facial organs. Finally, trained classifiers of open eyes and closed eyes are used to detect eyes in the candidate region quickly and accurately. The indexes which consist of PERCLOS and duration of closed-state are extracted in video frames real time. Moreover, the system is transplanted into smart device, that is, smartphone or tablet, due to its own camera and powerful calculation performance. Practical tests demonstrated that the proposed system can detect driver fatigue with real time and high accuracy. As the system has been planted into portable smart device, it could be widely used for driving fatigue detection in daily life. Wanzeng Kong, Lingxiao Zhou, Yizhi Wang, Jianhai Zhang, Jianhui Liu, and Shenyong Gao Copyright © 2015 Wanzeng Kong et al. All rights reserved. A Novel Variable Index and Excision CFAR Based Ship Detection Method on SAR Imagery Thu, 12 Mar 2015 13:35:00 +0000 http://www.hindawi.com/journals/js/2015/437083/ When applying the constant false alarm rate (CFAR) detector to ship detection on synthetic aperture radar (SAR) imagery, multiple interferers such as upwelling, breaking waves, ambiguities, and neighboring ships in a dense traffic area will degrade the probability of detection. In this paper, we propose a novel variable index and excision CFAR (VIE-CFAR) based ship detection method to alleviate the masking effect of multiple interferers. Firstly, we improve the variable index (VI) CFAR with an excision procedure, which censors the multiple interferers from the reference cells. And then, the paper integrates the novel CFAR concept into a ship detection scheme on SAR imagery, which adopts the VIE-CFAR to screen reference cells and the distribution to derive detection threshold. Finally, we analyze the performances of the VIE-CFAR under different environments and validate the proposed method on both ENVISAT and TerraSAR-X SAR data. The results demonstrate that the proposed method outperforms other existing detectors, especially in the presence of multiple interferers. Kefeng Ji, Xiangwei Xing, Huanxin Zou, and Jixiang Sun Copyright © 2015 Kefeng Ji et al. All rights reserved. A Novel Approach for Interest Point Detection via Laplacian-of-Bilateral Filter Mon, 09 Mar 2015 08:32:14 +0000 http://www.hindawi.com/journals/js/2015/685154/ Scale-invariant feature transform (SIFT) algorithm, one of the most famous and popular interest point detectors, detects extrema by using difference-of-Gaussian (DoG) filter which is an approximation to the Laplacian-of-Gaussian (LoG) for improving speed. However, DoG filter has a strong response along edge, even if the location along the edge is poorly determined and therefore is unstable to small amounts of noise. In this paper, we propose a novel interest point detection algorithm, which detects scale space extrema by using a Laplacian-of-Bilateral (LoB) filter. The LoB filter, which is produced by Bilateral and Laplacian filter, can preserve edge characteristic by fully utilizing the information of intensity variety. Compared with the SIFT algorithm, our algorithm substantially improves the repeatability of detected interest points on a very challenging benchmark dataset, in which images were generated under different imaging conditions. Extensive experimental results show that the proposed approach is more robust to challenging problems such as illumination and viewpoint changes, especially when encountering large illumination change. Mingming Huang, Zhichun Mu, Hui Zeng, and Hongbo Huang Copyright © 2015 Mingming Huang et al. All rights reserved. Light Path Model of Fiber Optic Liquid Level Sensor Considering Residual Liquid Film on the Wall Sun, 08 Mar 2015 13:00:45 +0000 http://www.hindawi.com/journals/js/2015/729507/ The working principle of the refractive-type fiber optic liquid level sensor is analyzed in detail based on the light refraction principle. The optic path models are developed in consideration of common simplification and the residual liquid film on the glass tube wall. The calculating formulae for the model are derived, constraint conditions are obtained, influencing factors are discussed, and the scopes and skills of application are analyzed through instance simulations. The research results are useful in directing the correct usage of the fiber optic liquid level sensor, especially in special cases, such as those involving viscous liquid in the glass tube monitoring. Zhijun Zhang and Shiwei Zhang Copyright © 2015 Zhijun Zhang and Shiwei Zhang. All rights reserved. Impact of Dynamic Path Loss Models in an Urban Obstacle Aware Ad Hoc Network Environment Sun, 08 Mar 2015 12:53:45 +0000 http://www.hindawi.com/journals/js/2015/286270/ This study highlights the importance of the physical layer and its impact on network performance in Mobile Ad Hoc Networks (MANETs). This was demonstrated by simulating various MANET scenarios using Network Simulator-2 (NS-2) with enhanced capability by adding propagation loss models (e.g., modified Two-Ray Ground model, ITU Line of Sight and Nonline of Sight (ITU-LoS and NLoS) model into street canyons and combined path loss and shadowing model (C-Shadowing)). The simulation results were then compared with the original Two-Ray Ground (TRG) model already available into NS-2. The scenario primarily simulated was that of a mobile environment using Random Way Point (RWP) mobility model with a variable number of obstacles in the simulation field (such as buildings, etc., causing variable attenuation) in order to analyze the extent of communication losses in various propagation loss models. Performance of the Ad Hoc On-demand Distance Vector (AODV) routing protocol was also analyzed in an ad hoc environment with 20 nodes. Kashif Amjad, Muhammad Ali, Sohail Jabbar, Majid Hussain, Seungmin Rho, and Mucheol Kim Copyright © 2015 Kashif Amjad et al. All rights reserved. Efficient and Rapid Detection of Salmonella Using Microfluidic Impedance Based Sensing Sun, 08 Mar 2015 07:57:59 +0000 http://www.hindawi.com/journals/js/2015/293461/ We present a low cost, easy to fabricate biosensor, which can quickly and accurately detect Salmonella typhimurium. This study also compares the advantages of the microfluidic biosensor over a nonmicrofluidic biosensor. High density interdigitated electrode array was used to detect Salmonella cells inside a microfluidic chip. Monoclonal anti-Salmonella antibodies were allowed to be immobilized on the surface of the electrode array for selective detection of Salmonella typhimurium. An impedance analyzer was used to measure and record the response signal from the biosensor. The biosensor provides qualitative and quantitative results in 3 hours without any enrichment steps. The microfluidic biosensor’s lower detection limit was found to be  CFU/mL compared to the  CFU/mL of the nonmicrofluidic biosensor, which shows that the microfluidic biosensor has 10-fold increased sensitivity. The impedance response of microfluidic biosensor was also significantly higher (2 to 2.9 times) compared to the nonmicrofluidic biosensor. Shibajyoti Ghosh Dastider, Syed Barizuddin, Nuh S. Yuksek, Majed Dweik, and Mahmoud F. Almasri Copyright © 2015 Shibajyoti Ghosh Dastider et al. All rights reserved. Human Respiration Localization Method Using UWB Linear Antenna Array Sat, 28 Feb 2015 08:42:18 +0000 http://www.hindawi.com/journals/js/2015/601926/ Human respiration is the basic vital sign in remote monitoring. There has been remarkable progress in this area, but some challenges still remain to obtain the angle-of-arrival (AOA) and distinguish the individual signals. This paper presents a 2D noncontact human respiration localization method using Ultra-Wideband (UWB) 1D linear antenna array. The imaging reconstruction based on beamforming is used to estimate the AOA of the human chest. The distance-slow time 2D matrix at the estimated AOA is processed to obtain the distance and respiration frequency of the vital sign. The proposed method can be used to isolate signals from individual targets when more than one human object is located in the surveillance space. The feasibility of the proposed method is demonstrated via the simulation and experiment results. Yuan Liu, Shiyou Wu, Jie Chen, Guangyou Fang, and Hejun Yin Copyright © 2015 Yuan Liu et al. All rights reserved. 3D Palmprint Recognition Using Dempster-Shafer Fusion Theory Thu, 26 Feb 2015 10:04:36 +0000 http://www.hindawi.com/journals/js/2015/252086/ This paper proposed a novel 3D palmprint recognition algorithm by combining 3D palmprint features using D-S fusion theory. Firstly, the structured light imaging is used to acquire the 3D palmprint data. Secondly, two types of unique features, including mean curvature feature and Gaussian curvature feature, are extracted. Thirdly, the belief function of the mean curvature recognition and the Gaussian curvature recognition was assigned, respectively. Fourthly, the fusion belief function from the proposed method was determined by the Dempster-shafer (D-S) fusion theory. Finally, palmprint recognition was accomplished according to the classification criteria. A 3D palmprint database with 1000 range images from 100 individuals was established, on which extensive experiments were performed. The results show that the proposed method 3D palmprint recognition is much more robust to illumination variations and condition changes of palmprint than MCR and GCR. Meanwhile, by fusing mean curvature and Gaussian curvature feature, the experimental results are promising (the average equal error rate of 0.404%). In the future, imaging technique needs further improvement for a better recognition performance. Jianyun Ni, Jing Luo, and Wubin Liu Copyright © 2015 Jianyun Ni et al. All rights reserved. Significance of the Nanograin Size on the H2S-Sensing Ability of CuO-SnO2 Composite Nanofibers Tue, 24 Feb 2015 15:36:52 +0000 http://www.hindawi.com/journals/js/2015/387641/ CuO-SnO2 composite nanofibers with various nanograin sizes were synthesized for investigating their sensing properties with respect to H2S gas. The nanograin size in the CuO-SnO2 composite nanofibers was controlled by changing the thermal treatment duration under isothermal conditions. The nanograin size was found to be critical for the sensing ability of the composite nanofibers. The CuO-SnO2 composite nanofibers comprised of small-sized nanograins were more sensitive to H2S than those with larger-sized nanograins. The superior sensing properties of the CuO-SnO2 composite nanofibers with the smaller nanograins were attributed to the formation of the larger number of p-CuO-n-SnO2 junctions and their transformation to metallic-CuS-n-SnO2 contacts upon exposure to H2S gas. The results suggest that smaller nanograins are conducive to obtaining superior H2S-sensing properties in CuO-SnO2 composite nanofibers. Akash Katoch, Jae-Hun Kim, and Sang Sub Kim Copyright © 2015 Akash Katoch et al. All rights reserved. Gas Sensors Based on Locally Heated Multiwall Carbon Nanotubes Decorated with Metal Nanoparticles Sun, 22 Feb 2015 12:36:25 +0000 http://www.hindawi.com/journals/js/2015/260382/ We report the design and fabrication of microreactors and sensors based on metal nanoparticle-decorated carbon nanotubes. Titanium adhesion layers and gold films were sputtered onto Si/SiO2 substrates for obtaining the electrical contacts. The gold layers were electrochemically thickened until 1 m and the electrodes were patterned using photolithography and wet chemical etching. Before the dielectrophoretic deposition of the nanotubes, a gap 1 m wide and 5 m deep was milled in the middle of the metallic line by focused ion beam, allowing the fabrication of sensors based on suspended nanotubes bridging the electrodes. Subsequently, the sputtering technique was used for decorating the nanotubes with metallic nanoparticles. In order to test the as-obtained sensors, microreactors (100 L volume) were machined from a single Kovar piece, being equipped with electrical connections and 1/4′′ Swagelok-compatible gas inlet and outlets for controlling the atmosphere in the testing chamber. The sensors, electrically connected to the contact pins by wire-bonding, were tested in the 10−5 to 10−2 W working power interval using oxygen as target gas. The small chamber volume allowed the measurement of fast characteristic times (response/recovery), with the sensors showing good sensitivity. R. Savu, J. V. Silveira, A. Alaferdov, E. Joanni, A. L. Gobbi, M. A. Canesqui, D. S. de Lara, A. G. Souza Filho, and S. A. Moshkalev Copyright © 2015 R. Savu et al. All rights reserved. Noncontact Detection and Analysis of Respiratory Function Using Microwave Doppler Radar Tue, 17 Feb 2015 13:26:43 +0000 http://www.hindawi.com/journals/js/2015/548136/ Real-time respiratory measurement with Doppler Radar has an important advantage in the monitoring of certain conditions such as sleep apnoea, sudden infant death syndrome (SIDS), and many other general clinical uses requiring fast nonwearable and non-contact measurement of the respiratory function. In this paper, we demonstrate the feasibility of using Doppler Radar in measuring the basic respiratory frequencies (via fast Fourier transform) for four different types of breathing scenarios: normal breathing, rapid breathing, slow inhalation-fast exhalation, and fast inhalation-slow exhalation conducted in a laboratory environment. A high correlation factor was achieved between the Doppler Radar-based measurements and the conventional measurement device, a respiration strap. We also extended this work from basic signal acquisition to extracting detailed features of breathing function (I : E ratio). This facilitated additional insights into breathing activity and is likely to trigger a number of new applications in respiratory medicine. Yee Siong Lee, Pubudu N. Pathirana, Robin J. Evans, and Christopher L. Steinfort Copyright © 2015 Yee Siong Lee et al. All rights reserved. Sensing of Tooth Microleakage Based on Dental Optical Coherence Tomography Sun, 15 Feb 2015 08:36:58 +0000 http://www.hindawi.com/journals/js/2015/984627/ This study describes microleakage sensing based on swept-source optical coherence tomography (SS-OCT). With a handheld scanning probe, the SS-OCT system can provide portable real-time imaging for clinical diagnosis. Radiography is the traditional clinical imaging instrument used for dentistry; however, it does not provide good contrast images between filling material and the enamel of treated teeth with microleakage. The results of this study show that microleakage can be detected with oral probing using SS-OCT in vivo. The calculated microleakage length was 401 μm and the width is 148 μm, which is consistent with the related histological biopsy measurements. The diagnosis of microleakage in teeth could be useful for prevention of secondary caries in the clinical treatment plans developed in the field of oral medicine. Chia-Wei Sun, Yi-Ching Ho, and Shyh-Yuan Lee Copyright © 2015 Chia-Wei Sun et al. All rights reserved. Self-Noise of the MET Angular Motion Seismic Sensors Tue, 10 Feb 2015 14:25:56 +0000 http://www.hindawi.com/journals/js/2015/512645/ Interest to angular motion seismic sensors is generated by an expectation that direct measurement of the rotations, associated with seismic signals, would allow obtaining more detailed and accurate information from them. Due to the seismic signals low intensity a self-noise of the sensors is one of the most crucial parameters, characterizing their performance. In seismic applications the molecular-electronic transfer (MET) technology is considered as one of the most promising technologies for the rotations measurements. In this research we have developed a noise model for the MET angular sensors. The experimental part of the research which fully agrees with theoretical data includes the instrument self-noise measurement in quite locations. Based on the modelling we have revealed the directions of further research to improve the MET angular sensors performance. Egor V. Egorov, Ivan V. Egorov, and Vadim M. Agafonov Copyright © 2015 Egor V. Egorov et al. All rights reserved. An eHealth System for Pressure Ulcer Risk Assessment Based on Accelerometer and Pressure Data Tue, 10 Feb 2015 07:43:53 +0000 http://www.hindawi.com/journals/js/2015/106537/ Pressure ulcers are a common skin disease which is associated with pain, reduced autonomy, social isolation, and reduced quality of life. There are several systems for monitoring of pressure ulcer-related risk factors on the market, but up to now no satisfactory solution is available, especially for people with medium pressure ulcer risk. We present a novel pressure ulcer risk assessment and prevention system, which combines the advantages of accelerometer and pressure sensors for monitoring pressure ulcer risk factors. Sensors are used for detection of repositionings of the person lying on the mattress. Sensor data are sent to a tablet where they are analysed and presented graphically. The system was evaluated in a long-term test at the homes of people of the target group. Results indicate that the system is able to detect movements of persons while lying in bed. Weak correlation in between mobility and Braden pressure ulcer risk was found (correlation factor = 0.31). From our data, long-term trends could be visualized as well as 24 h mobility profiles. Such graphical illustrations might be helpful for caregivers in order to optimize care of people with medium to high pressure ulcer risk. Dieter Hayn, Markus Falgenhauer, Jürgen Morak, Karin Wipfler, Viktoria Willner, Walter Liebhart, and Günter Schreier Copyright © 2015 Dieter Hayn et al. All rights reserved. Developing an Ontology-Based Cold Chain Logistics Monitoring and Decision System Tue, 10 Feb 2015 06:17:49 +0000 http://www.hindawi.com/journals/js/2015/231706/ Nowadays the cold chain logistics for perishable goods is increasingly complex, while most of the research works are focusing on the monitoring of temperature and humidity but seldom on the assessment and decision support for the monitored cold chain quality. In this context, a monitoring and decision system based on wireless sensor networks (WSN) and ontology is proposed in this paper which consists of sensing layer, network layer, and application layer. Ontology, as a shared concept model, can describe the objective world better with its own syntax and provides the general understanding of the specialized knowledge in a domain. Therefore, cold chain quality assessment software based on ontology has been developed; consequently, assessment and diagnosis for cold chain quality can be achieved, which can provide constructive advice and suggestions for its treatment. A demonstration of the system along a rabies vaccine logistics chain is validated in this paper. These results proved that this system presents important advantages such as effective regulation, low power consumption, and accurate ontology-based analysis. Yujun Wang, Jianjun Yi, Xiaomin Zhu, Jinlong Luo, and Baiyang Ji Copyright © 2015 Yujun Wang et al. All rights reserved. Microwave Sensors Based on Symmetry Properties of Resonator-Loaded Transmission Lines Mon, 09 Feb 2015 10:08:21 +0000 http://www.hindawi.com/journals/js/2015/741853/ This review paper is focused on the design of microwave sensors using symmetry properties of transmission lines loaded with symmetric resonators. The operating principle of these sensors is presented and then several prototype devices are reported, including linear and angular displacement sensors and rotation speed sensors. The main advantage of the proposed sensors is the robustness against changing environmental conditions. Jordi Naqui and Ferran Martín Copyright © 2015 Jordi Naqui and Ferran Martín. All rights reserved. Multiobjective Dynamic Vehicle Routing Problem and Time Seed Based Solution Using Particle Swarm Optimization Mon, 02 Feb 2015 13:21:35 +0000 http://www.hindawi.com/journals/js/2015/189832/ A multiobjective dynamic vehicle routing problem (M-DVRP) has been identified and a time seed based solution using particle swarm optimization (TS-PSO) for M-DVRP has been proposed. M-DVRP considers five objectives, namely, geographical ranking of the request, customer ranking, service time, expected reachability time, and satisfaction level of the customers. The multiobjective function of M-DVRP has four components, namely, number of vehicles, expected reachability time, and profit and satisfaction level. Three constraints of the objective function are vehicle, capacity, and reachability. In TS-PSO, first of all, the problem is partitioned into smaller size DVRPs. Secondly, the time horizon of each smaller size DVRP is divided into time seeds and the problem is solved in each time seed using particle swarm optimization. The proposed solution has been simulated in ns-2 considering real road network of New Delhi, India, and results are compared with those obtained from genetic algorithm (GA) simulations. The comparison confirms that TS-PSO optimizes the multiobjective function of the identified problem better than what is offered by GA solution. Omprakash Kaiwartya, Sushil Kumar, D. K. Lobiyal, Pawan Kumar Tiwari, Abdul Hanan Abdullah, and Ahmed Nazar Hassan Copyright © 2015 Omprakash Kaiwartya et al. All rights reserved. ACO-Based Sweep Coverage Scheme in Wireless Sensor Networks Sun, 01 Feb 2015 09:42:21 +0000 http://www.hindawi.com/journals/js/2015/484902/ Coverage problem is one of the major issues in wireless sensor networks (WSN). In order to optimize the network coverage, different coverage formulations have been proposed. Recently, a newly emerging coverage scheme in wireless sensor networks, sweep coverage, which uses mobile sensors to monitor certain points of interest (POIs), is proposed. However, the data delivery to sink, an important problem in WSN, is not considered in original sweep coverage and many of the existing works did not consider it yet. In this work, a novel algorithm named ACOSC (ACO-based sweep coverage) to solve the sweep coverage problem considering periodical coverage of POIs and delivery of data simultaneously is proposed. The evaluation results show that our algorithm has better performance than existing schemes. Peng Huang, Feng Lin, Chang Liu, Jian Gao, and Ji-liu Zhou Copyright © 2015 Peng Huang et al. All rights reserved. Ultrasensitive NO2 Gas Sensor Based on Epitaxial Graphene Thu, 29 Jan 2015 15:29:24 +0000 http://www.hindawi.com/journals/js/2015/108581/ We report about technology of fabrication and optimization of a gas sensor based on epitaxial graphene. Optimized graphene/metal contact configuration exhibited low contact resistance. Complementary annealing of graphene sensor after each gas exposure led to significant improvement in the sensing performance. The response of the annealed sensor to the nitrogen dioxide (NO2) was tenfold higher than that of an as-fabricated graphene sensor. NO2 concentration as low as 0.2 parts per billion (ppb) was easily detectable. Devices have high signal-to-noise ratio. The detection limit of the graphene sensor was estimated to be 0.6 ppt (parts per trillion). The present technology with additional annealing improves the performance of the graphene based sensor and makes it suitable for the environmental nitrogen dioxide gas monitoring. S. Novikov, N. Lebedeva, and A. Satrapinski Copyright © 2015 S. Novikov et al. All rights reserved. Self-Referenced Plasmon Waveguide Resonance Sensor Using Different Waveguide Modes Wed, 28 Jan 2015 07:11:55 +0000 http://www.hindawi.com/journals/js/2015/945908/ We report a plasmon waveguide resonance (PWR) sensing structure supporting two waveguide modes for self-referenced measurement. We show theoretically the dual mode PWR sensing structure owns unique opportunities for self-referenced measurement, and the accuracy and cross sensitivity can be optimized by simply varying the gold film thickness or dielectric layer thickness or dielectric film refractive index. This structure may provide an approach owning good compatibility with the surface plasmon resonance and PWR biosensors for self-referenced biosensing. Pengfei Zhang, Le Liu, Yonghong He, Yanhong Ji, and Hui Ma Copyright © 2015 Pengfei Zhang et al. All rights reserved. Resolution Enhancement Method Used for Force Sensing Resistor Array Tue, 27 Jan 2015 12:01:16 +0000 http://www.hindawi.com/journals/js/2015/647427/ Tactile sensors are one of the major devices that enable robotic systems to interact with the surrounding environment. This research aims to propose a mathematical model to describe the behavior of a tactile sensor based on experimental and statistical analyses and moreover to develop a versatile algorithm that can be applied to different tactile sensor arrays to enhance the limited resolution. With the proposed algorithm, the resolution can be increased up to twenty times if multiple measurements are available. To verify if the proposed algorithm can be used for tactile sensor arrays that are used in robotic system, a force sensing array (FSR) is adopted. The acquired two-dimensional measurements were processed by a resolution enhancement method (REM) to enhance the resolution, which can be used to improve the resolution for single image or multiple measurements. As a result, the resolution of the sensor is increased and it can be used as synthetic skin to identify accurate shapes of objects and applied forces. Karen Flores De Jesus, Marvin H. Cheng, Lei Jiang, and Ezzat G. Bakhoum Copyright © 2015 Karen Flores De Jesus et al. All rights reserved. Rate Allocation for Wireless Multimedia Sensor Networks Using Pricing Mechanism Thu, 22 Jan 2015 10:43:46 +0000 http://www.hindawi.com/journals/js/2015/738565/ A bandwidth allocation algorithm for wireless multimedia sensor networks is proposed in this paper. On the premise of Initial allocation algorithm based on distortion and congestion model to provide an efficient system performance, the allocation algorithm based on pricing mechanism we proposed balances the real-time requirement of different users by adjusting the bandwidth price in each network and each slot. Simulation results show that the proposed algorithm balances the bandwidth ratio of different users according to the video complexity, and it can provide a good system performance guaranteeing the fairness among the users. Zhang Jian Ming, Wang YI, Xie Ze Ming, Tang Shi Yi, and Ou Hao Yuan Copyright © 2015 Zhang Jian Ming et al. All rights reserved.