Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Energy Analysis of Contention Tree-Based Access Protocols in Dense Machine-to-Machine Area Networks Wed, 22 Apr 2015 14:05:16 +0000 http://www.hindawi.com/journals/js/2015/685164/ Machine-to-Machine (M2M) area networks aim at connecting an M2M gateway with a large number of energy-constrained devices that must operate autonomously for years. Therefore, attaining high energy efficiency is essential in the deployment of M2M networks. In this paper, we consider a dense M2M area network composed of hundreds or thousands of devices that periodically transmit data upon request from a gateway or coordinator. We theoretically analyse the devices’ energy consumption using two Medium Access Control (MAC) protocols which are based on a tree-splitting algorithm to resolve collisions among devices: the Contention Tree Algorithm (CTA) and the Distributed Queuing (DQ) access. We have carried out computer-based simulations to validate the accuracy of the theoretical models and to compare the energy performance using DQ, CTA, and Frame Slotted-ALOHA (FSA) in M2M area networks with devices in compliance with the IEEE 802.15.4 physical layer. Results show that the performance of DQ is totally independent of the number of contending devices, and it can reduce the energy consumed per device in more than 35% with respect to CTA and in more than 80% with respect to FSA. Francisco Vázquez-Gallego, Luis Alonso, and Jesus Alonso-Zarate Copyright © 2015 Francisco Vázquez-Gallego et al. All rights reserved. Lifetime Optimization of a Multiple Sink Wireless Sensor Network through Energy Balancing Sun, 19 Apr 2015 09:58:31 +0000 http://www.hindawi.com/journals/js/2015/921250/ The wireless sensor network consists of small limited energy sensors which are connected to one or more sinks. The maximum energy consumption takes place in communicating the data from the nodes to the sink. Multiple sink WSN has an edge over the single sink WSN where very less energy is utilized in sending the data to the sink, as the number of hops is reduced. If the energy consumed by a node is balanced between the other nodes, the lifetime of the network is considerably increased. The network lifetime optimization is achieved by restructuring the network by modifying the neighbor nodes of a sink. Only those nodes are connected to a sink which makes the total energy of the sink less than the threshold. This energy balancing through network restructuring optimizes the network lifetime. This paper depicts this fact through simulations done in MATLAB. Tapan Kumar Jain, Davinder Singh Saini, and Sunil Vidya Bhooshan Copyright © 2015 Tapan Kumar Jain et al. All rights reserved. Efficient Multiway Relaying for Data Sharing in Energy Harvesting Sensor Networks Wed, 15 Apr 2015 13:08:12 +0000 http://www.hindawi.com/journals/js/2015/285056/ In a wireless sensor network (WSN), sensors often need to share their measurements for applications like distributed estimation and detection or data aggregation. Here, we suggest using multiway relaying (MWR) for data sharing between energy harvesting sensors that cannot directly communicate with each other. We first start by studying the achievable data rate of amplify-and-forward (AF) MWR for energy harvesting sensors. Then, we show that, by backing off the transmit power at the sensors, not only better energy efficiency and longer lifetime are achieved, but also the data sharing rate increases. Based on this result, we further improve the performance of AF MWR in the assumed WSN by smartly adjusting the transmit power at the sensors. Our power allocation is devised in a way to improve the energy efficiency of MWR and increase the sum rate of data sharing between the sensors over the network lifetime. Simulation results are presented to verify the enhancement achieved by using our proposed power allocation technique. Moslem Noori and Masoud Ardakani Copyright © 2015 Moslem Noori and Masoud Ardakani. All rights reserved. Locomotion Strategy Selection for a Hybrid Mobile Robot Using Time of Flight Depth Sensor Wed, 15 Apr 2015 11:38:55 +0000 http://www.hindawi.com/journals/js/2015/425732/ The performance of a mobile robot can be improved by utilizing different locomotion modes in various terrain conditions. This creates the necessity of having a supervisory controller capable of recognizing different terrain types and changing the locomotion mode of the robot accordingly. This work focuses on the locomotion strategy selection problem for a hybrid legged wheeled mobile robot. Supervisory control of the robot is accomplished by the terrain recognizer, which classifies depth images obtained from a commercial time of flight depth sensor and selects different locomotion mode subcontrollers based on the recognized terrain type. For the terrain recognizer, a database is generated consisting of five terrain classes (Uneven, Level Ground, Stair Up, Stair Down, and Nontraversable). Depth images are enhanced using confidence map based filtering. The accuracy of the terrain classification using Support Vector Machine classifier for the testing database in five-class terrain recognition problem is 97%. Real-world experiments assess the locomotion abilities of the quadruped and the capability of the terrain recognizer in real-time settings. The results of these experiments show depth images processed in real time using machine learning algorithms can be used for the supervisory control of hybrid robots with legged and wheeled locomotion capabilities. Artur Saudabayev, Farabi Kungozhin, Damir Nurseitov, and Huseyin Atakan Varol Copyright © 2015 Artur Saudabayev et al. All rights reserved. Fabrication of Porous Silicon Based Humidity Sensing Elements on Paper Thu, 09 Apr 2015 07:34:07 +0000 http://www.hindawi.com/journals/js/2015/927396/ A roll-to-roll compatible fabrication process of porous silicon (pSi) based sensing elements for a real-time humidity monitoring is described. The sensing elements, consisting of printed interdigitated silver electrodes and a spray-coated pSi layer, were fabricated on a coated paper substrate by a two-step process. Capacitive and resistive responses of the sensing elements were examined under different concentrations of humidity. More than a three orders of magnitude reproducible decrease in resistance was measured when the relative humidity (RH) was increased from 0% to 90%. A relatively fast recovery without the need of any refreshing methods was observed with a change in RH. Humidity background signal and hysteresis arising from the paper substrate were dependent on the thickness of sensing pSi layer. Hysteresis in most optimal sensing element setup (a thick pSi layer) was still noticeable but not detrimental for the sensing. In addition to electrical characterization of sensing elements, thermal degradation and moisture adsorption properties of the paper substrate were examined in connection to the fabrication process of the silver electrodes and the moisture sensitivity of the paper. The results pave the way towards the development of low-cost humidity sensors which could be utilized, for example, in smart packaging applications or in smart cities to monitor the environment. Tero Jalkanen, Anni Määttänen, Ermei Mäkilä, Jaani Tuura, Martti Kaasalainen, Vesa-Pekka Lehto, Petri Ihalainen, Jouko Peltonen, and Jarno Salonen Copyright © 2015 Tero Jalkanen et al. All rights reserved. Optimization of an Accelerometer and Gyroscope-Based Fall Detection Algorithm Thu, 09 Apr 2015 06:40:33 +0000 http://www.hindawi.com/journals/js/2015/452078/ Falling is a common and significant cause of injury in elderly adults (>65 yrs old), often leading to disability and death. In the USA, one in three of the elderly suffers from fall injuries annually. This study’s purpose is to develop, optimize, and assess the efficacy of a falls detection algorithm based upon a wireless, wearable sensor system (WSS) comprised of a 3-axis accelerometer and gyroscope. For this study, the WSS is placed at the chest center to collect real-time motion data of various simulated daily activities (i.e., walking, running, stepping, and falling). Tests were conducted on 36 human subjects with a total of 702 different movements collected in a laboratory setting. Half of the dataset was used for development of the fall detection algorithm including investigations of critical sensor thresholds and the remaining dataset was used for assessment of algorithm sensitivity and specificity. Experimental results show that the algorithm detects falls compared to other daily movements with a sensitivity and specificity of 96.3% and 96.2%, respectively. The addition of gyroscope information enhances sensitivity dramatically from results in the literature as angular velocity changes provide further delineation of a fall event from other activities that may also experience high acceleration peaks. Quoc T. Huynh, Uyen D. Nguyen, Lucia B. Irazabal, Nazanin Ghassemian, and Binh Q. Tran Copyright © 2015 Quoc T. Huynh et al. All rights reserved. Simple Design of Wireless Sensor Networks for Traffic Jams Avoidance Wed, 08 Apr 2015 08:10:21 +0000 http://www.hindawi.com/journals/js/2015/380794/ Intelligent transportation systems (ITS) are usually approached by exhaustive measuring and complex signal processing including medium-high cost hardware deployment. In this paper, a novel design of a wireless sensor network system using magnetometers and microphones for the detection and avoidance of traffic jams is described and analyzed. The system, which can also be used for traffic monitoring and surveillance, is simple, energy efficient, and accurate which allows to be implemented with a reduced hardware cost. In order to reduce the maintenance tasks, mini solar panels would also be installed for powering up the motes in the near future. Víctor P. Gil Jiménez and M. Julia Fernández-Getino García Copyright © 2015 Víctor P. Gil Jiménez and M. Julia Fernández-Getino García. All rights reserved. Fabrication of a Needle Microsensor and Its Applications in the Detection of Dissolved Oxygen Tue, 07 Apr 2015 08:58:52 +0000 http://www.hindawi.com/journals/js/2015/408458/ A novel needle microsensor measurement system was fabricated and applied to determine the concentration of dissolved oxygen. Platinum nanoparticles were employed to modify the surface of copper-core electrode in order to improve electrochemical response signal. The homemade electrode displayed efficient electrocatalytic reduction activity towards dissolved oxygen. The sensor responded linearly to dissolved oxygen in the range of 10 μM to 0.195 mM and had a remarkable sensitivity of 9.02 μA/mM. In addition, it showed an excellent reproducibility, stability, and selectivity. These results indicated that the needle microsensor when used, could yield good performance. Moreover, it is believed to be a potential tool for studying specific substances at a cellular level or in vivo in future. Yuxin Fang, Di Zhang, Qing Xia, Shouhai Hong, Yuan Xu, and Yi Guo Copyright © 2015 Yuxin Fang et al. All rights reserved. A New MEMS Stochastic Model Order Reduction Method: Research and Application Sun, 05 Apr 2015 13:51:39 +0000 http://www.hindawi.com/journals/js/2015/125621/ Modeling and simulation of MEMS devices is a very complex tasks which involve the electrical, mechanical, fluidic, and thermal domains, and there are still some uncertainties that need to be accounted for during the robust design of MEMS actuators caused by uncertain material and/or geometric parameters. According to these problems, we put forward stochastic model order reduction method under random input conditions to facilitate fast time and frequency domain analyses; the method makes use of polynomial chaos expansions in terms of the random input variables for the matrices of a finite element model of the system and then uses its transformation matrix to reduce the model; the method is independent of the MOR algorithm, so it is seamlessly compatible with MOR method used in popular finite element solvers. The simulation results verify the method is effective in large scale MEMS design process. Bian Xiangjuan, Youping Gong, Chen Guojin, and Lv Yunpeng Copyright © 2015 Bian Xiangjuan et al. All rights reserved. Analyzing Multimode Wireless Sensor Networks Using the Network Calculus Tue, 31 Mar 2015 08:06:11 +0000 http://www.hindawi.com/journals/js/2015/851608/ The network calculus is a powerful tool to analyze the performance of wireless sensor networks. But the original network calculus can only model the single-mode wireless sensor network. In this paper, we combine the original network calculus with the multimode model to analyze the maximum delay bound of the flow of interest in the multimode wireless sensor network. There are two combined methods A-MM and N-MM. The method A-MM models the whole network as a multimode component, and the method N-MM models each node as a multimode component. We prove that the maximum delay bound computed by the method A-MM is tighter than or equal to that computed by the method N-MM. Experiments show that our proposed methods can significantly decrease the analytical delay bound comparing with the separate flow analysis method. For the large-scale wireless sensor network with 32 thousands of sensor nodes, our proposed methods can decrease about 70% of the analytical delay bound. Xi Jin, Nan Guan, Jintao Wang, and Peng Zeng Copyright © 2015 Xi Jin et al. All rights reserved. Architecture and Implementation of a Scalable Sensor Data Storage and Analysis System Using Cloud Computing and Big Data Technologies Mon, 30 Mar 2015 11:23:43 +0000 http://www.hindawi.com/journals/js/2015/834217/ Sensors are becoming ubiquitous. From almost any type of industrial applications to intelligent vehicles, smart city applications, and healthcare applications, we see a steady growth of the usage of various types of sensors. The rate of increase in the amount of data produced by these sensors is much more dramatic since sensors usually continuously produce data. It becomes crucial for these data to be stored for future reference and to be analyzed for finding valuable information, such as fault diagnosis information. In this paper we describe a scalable and distributed architecture for sensor data collection, storage, and analysis. The system uses several open source technologies and runs on a cluster of virtual servers. We use GPS sensors as data source and run machine-learning algorithms for data analysis. Galip Aydin, Ibrahim Riza Hallac, and Betul Karakus Copyright © 2015 Galip Aydin et al. All rights reserved. Gesture Recognition from Data Streams of Human Motion Sensor Using Accelerated PSO Swarm Search Feature Selection Algorithm Mon, 30 Mar 2015 09:21:07 +0000 http://www.hindawi.com/journals/js/2015/205707/ Human motion sensing technology gains tremendous popularity nowadays with practical applications such as video surveillance for security, hand signing, and smart-home and gaming. These applications capture human motions in real-time from video sensors, the data patterns are nonstationary and ever changing. While the hardware technology of such motion sensing devices as well as their data collection process become relatively mature, the computational challenge lies in the real-time analysis of these live feeds. In this paper we argue that traditional data mining methods run short of accurately analyzing the human activity patterns from the sensor data stream. The shortcoming is due to the algorithmic design which is not adaptive to the dynamic changes in the dynamic gesture motions. The successor of these algorithms which is known as data stream mining is evaluated versus traditional data mining, through a case of gesture recognition over motion data by using Microsoft Kinect sensors. Three different subjects were asked to read three comic strips and to tell the stories in front of the sensor. The data stream contains coordinates of articulation points and various positions of the parts of the human body corresponding to the actions that the user performs. In particular, a novel technique of feature selection using swarm search and accelerated PSO is proposed for enabling fast preprocessing for inducing an improved classification model in real-time. Superior result is shown in the experiment that runs on this empirical data stream. The contribution of this paper is on a comparative study between using traditional and data stream mining algorithms and incorporation of the novel improved feature selection technique with a scenario where different gesture patterns are to be recognized from streaming sensor data. Simon Fong, Justin Liang, Iztok Fister Jr., Iztok Fister, and Sabah Mohammed Copyright © 2015 Simon Fong et al. 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.