Journal of Sensors https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Time Reversal Aided Bidirectional OFDM Underwater Cooperative Communication Algorithm with the Same Frequency Transmission Thu, 23 Feb 2017 08:02:03 +0000 http://www.hindawi.com/journals/js/2017/8242369/ In underwater acoustic channel, signal transmission may experience significant latency and attenuation that would degrade the performance of underwater communication. The cooperative communication technique can solve it but the spectrum efficiency is lower than traditional underwater communication. So we proposed a time reversal aided bidirectional OFDM underwater cooperative communication algorithm. The algorithm allows all underwater sensor nodes to share the same uplink and downlink frequency simultaneously to improve the spectrum efficiency. Since the same frequency transmission would produce larger intersymbol interference, we adopted the time reversal method to degrade the multipath interference at first; then we utilized the self-information cancelation module to remove the self-signal of OFDM block because it is known for sensor nodes. In the simulation part, we compare our proposed algorithm with the existing underwater cooperative transmission algorithms in respect of bit error ratio, transmission rate, and computation. The results show that our proposed algorithm has double spectrum efficiency under the same bit error ratio and has the higher transmission rate than the other underwater communication methods. Lingling Zhang, Jianguo Huang, Chengkai Tang, and Houbing Song Copyright © 2017 Lingling Zhang et al. All rights reserved. Recent Advances in Security and Privacy for Wireless Sensor Networks 2016 Thu, 23 Feb 2017 06:30:05 +0000 http://www.hindawi.com/journals/js/2017/3057534/ Fei Yu, Chin-Chen Chang, Jian Shu, Iftikhar Ahmad, Jun Zhang, and Jose Maria de Fuentes Copyright © 2017 Fei Yu et al. All rights reserved. Balanced Transmissions Based Trajectories of Mobile Sink in Homogeneous Wireless Sensor Networks Mon, 20 Feb 2017 13:08:28 +0000 http://www.hindawi.com/journals/js/2017/4281597/ Mobile Sink (MS) based routing strategies have been widely investigated to prolong the lifetime of Wireless Sensor Networks (WSNs). In this paper, we propose two schemes for data gathering in WSNs: (i) MS moves on random paths in the network (RMS) and (ii) the trajectory of MS is defined (DMS). In both the schemes, the network field is logically divided into small squares. The center point of each partitioned area is the sojourn location of the MS. We present three linear programming based models: (i) to maximize network lifetime, (ii) to minimize path loss, and (iii) to minimize end to end delay. Moreover, a geometric model is proposed to avoid redundancy while collecting information from the network nodes. Simulation results show that our proposed schemes perform better than the selected existing schemes in terms of the selected performance metrics. Mariam Akbar, Nadeem Javaid, Wadood Abdul, Sanaa Ghouzali, Abid Khan, Iftikhar Azim Niaz, and Manzoor Ilahi Copyright © 2017 Mariam Akbar et al. All rights reserved. SmartOntoSensor: Ontology for Semantic Interpretation of Smartphone Sensors Data for Context-Aware Applications Mon, 20 Feb 2017 08:36:58 +0000 http://www.hindawi.com/journals/js/2017/8790198/ The integration of cheap and powerful sensors in smartphones has enabled the emergence of several context-aware applications and frameworks. However, the available smartphone context-aware frameworks are static because of using relational data models having predefined usage of sensory data. Importantly, the frameworks lack the soft integration of new data types and relationships that appear with the emergence of new smartphone sensors. Furthermore, sensors generate huge data that intensifies the problem of too much data and not enough knowledge. Smarting of smartphone sensory data is essential for advanced analytical processing, integration, inferencing, and interpretation by context-aware applications. In order to achieve this goal, novel smartphone sensors ontology is required for semantic modeling of smartphones and sensory data, which is the main contribution of this paper. This paper presents SmartOntoSensor, a lightweight mid-level ontology that has been developed using NeOn methodology and Content Ontology Design pattern. The ontology describes smartphone and sensors from different aspects including platforms, deployments, measurement capabilities and properties, observations, data fusion, and context modeling. SmartOntoSensor has been developed using Protégé and evaluated using OntoQA, SPARQL, and experimental study. The ontology is also tested by integrating into ModeChanger application that leverages SmartOntoSensor for automatic changing of smartphone modes according to the varying contexts. We have obtained promising results that advocate for the improved ontological design and applications of SmartOntoSensor. Shaukat Ali, Shah Khusro, Irfan Ullah, Akif Khan, and Inayat Khan Copyright © 2017 Shaukat Ali et al. All rights reserved. A Mobile-Based High Sensitivity On-Field Organophosphorus Compounds Detecting System for IoT-Based Food Safety Tracking Mon, 20 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/8797435/ A mobile-based high sensitivity absorptiometer is presented to detect organophosphorus (OP) compounds for Internet-of-Things based food safety tracking. This instrument consists of a customized sensor front-end chip, LED-based light source, low power wireless link, and coin battery, along with a sample holder packaged in a recycled format. The sensor front-end integrates optical sensor, capacitive transimpedance amplifier, and a folded-reference pulse width modulator in a single chip fabricated in a 0.18 μm 1-poly 5-metal CMOS process and has input optical power dynamic range of 71 dB, sensitivity of 3.6 nW/cm2 (0.77 pA), and power consumption of 14.5 μW. Enabled by this high sensitivity sensor front-end chip, the proposed absorptiometer has a small size of 96 cm3, with features including on-field detection and wireless communication with a mobile. OP compound detection experiments of the handheld system demonstrate a limit of detection (LOD) of 0.4 μmol/L, comparable to that of a commercial spectrophotometer. Meanwhile, an android-based application (APP) is presented which makes the absorptiometer access to the Internet-of-Things (IoT). Han Jin, Yajie Qin, Hao Liang, Lei Wan, Hao Lan, Guoping Chen, Ran Liu, Li-rong Zheng, Patrick Chiang, and Zhi-liang Hong Copyright © 2017 Han Jin et al. All rights reserved. High Frequency InGaAs MOSFET with Nitride Sidewall Design for Low Power Application Mon, 20 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/4078240/ devices have been widely researched for low power high frequency applications due to the outstanding electron mobility and small bandgap of the materials. Regrown source/drain technology is highly appreciated in InGaAs MOSFET, since it is able to reduce the thermal budget induced by ion implantation, as well as reduce the source/drain resistance. However, regrown source/drain technology has problems such as high parasitic capacitance and high electric field at gate edge towards the drain side, which will lead to large drain leakage current and compromise the frequency performance. To alleviate the drain leakage current problem for low power applications and to improve the high frequency performance, a novel Si3N4 sidewall structure was introduced to the InGaAs MOSFET. Device simulation was carried out with different newly proposed sidewall designs. The results showed that both the drain leakage current and the source/drain parasitic capacitance were reduced by applying Si3N4 sidewall together with InP extended layer in InGaAs MOSFET. The simulation results also suggested that the newly created “recessed” sidewall was able to bring about the most frequency favorable characteristic with no current sacrifice. Jiongjiong Mo, Hua Chen, Zhiyu Wang, and Faxin Yu Copyright © 2017 Jiongjiong Mo et al. All rights reserved. A Lifetime Optimization Algorithm Limited by Data Transmission Delay and Hops for Mobile Sink-Based Wireless Sensor Networks Sun, 19 Feb 2017 07:28:53 +0000 http://www.hindawi.com/journals/js/2017/7507625/ To improve the lifetime of mobile sink-based wireless sensor networks and considering that data transmission delay and hops are limited in actual system, a lifetime optimization algorithm limited by data transmission delay and hops (LOA_DH) for mobile sink-based wireless sensor networks is proposed. In LOA_DH, some constraints are analyzed, and an optimization model is proposed. Maximum capacity path routing algorithm is used to calculate the energy consumption of communication. Improved genetic algorithm which modifies individuals to meet all constraints is used to solve the optimization model. The optimal solution of sink node’s sojourn grid centers and sojourn times which maximizes network lifetime is obtained. Simulation results show that, in three node distribution scenes, LOA_DH can find the movement solution of sink node which covers all sensor nodes. Compared with MCP_RAND, MCP_GMRE, and EASR, the solution improves network lifetime and reduces average amount of node discarded data and average energy consumption of nodes. Yourong Chen, Xiaowen Lv, Siyi Lu, and Tiaojuan Ren Copyright © 2017 Yourong Chen et al. All rights reserved. Soft-Sensor Modeling of PVC Polymerizing Process Based on F-GMDH-Type Neural Network Algorithm Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/7872030/ For predicting the conversion velocity of the vinyl chloride monomer (VCM) in the polymerization process of polyvinylchloride (PVC), an improved Group Method of Data Handling- (GMDH-) type neural network soft-sensor model is proposed. After analyzing the technique of PVC manufacturing process, the auxiliary variables for setting up the soft-sensor model are selected and the experimental data are normalized. Because the internal standard of the original GMDH-type neural cannot solve the problem of multiple-collinearity problem and the useful variables tend to be prematurely eliminated in the modeling process, a hybrid method combining the regression analysis method and the least squares method is proposed to solve the multiple-collinearity problem. On the same time, by adopting some optimization experiences in genetic algorithm (GA), the generational crossover combination variables method is proposed to solve the shortcoming of useful variable being eliminated prematurely. The simulation results show that the proposed soft-sensor model can significantly improve the prediction accuracy of economic and technical indicators in the PVC polymerization process and can meet the real time control requirements of polymerization reactor production process. Wei-zhen Sun, Jie-sheng Wang, and Shu-zhi Gao Copyright © 2017 Wei-zhen Sun et al. All rights reserved. Method for SLAM Based on Omnidirectional Vision: A Delayed-EKF Approach Sun, 19 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/7342931/ This work presents a method for implementing a visual-based simultaneous localization and mapping (SLAM) system using omnidirectional vision data, with application to autonomous mobile robots. In SLAM, a mobile robot operates in an unknown environment using only on-board sensors to simultaneously build a map of its surroundings, which it uses to track its position. The SLAM is perhaps one of the most fundamental problems to solve in robotics to build mobile robots truly autonomous. The visual sensor used in this work is an omnidirectional vision sensor; this sensor provides a wide field of view which is advantageous in a mobile robot in an autonomous navigation task. Since the visual sensor used in this work is monocular, a method to recover the depth of the features is required. To estimate the unknown depth we propose a novel stochastic triangulation technique. The system proposed in this work can be applied to indoor or cluttered environments for performing visual-based navigation when GPS signal is not available. Experiments with synthetic and real data are presented in order to validate the proposal. Rodrigo Munguía, Carlos López-Franco, Emmanuel Nuño, and Adriana López-Franco Copyright © 2017 Rodrigo Munguía et al. All rights reserved. Parallel Algorithm for Wireless Data Compression and Encryption Sun, 12 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/4209397/ As the wireless network has limited bandwidth and insecure shared media, the data compression and encryption are very useful for the broadcasting transportation of big data in IoT (Internet of Things). However, the traditional techniques of compression and encryption are neither competent nor efficient. In order to solve this problem, this paper presents a combined parallel algorithm named “CZ algorithm” which can compress and encrypt the big data efficiently. CZ algorithm uses a parallel pipeline, mixes the coding of compression and encryption, and supports the data window up to 1 TB (or larger). Moreover, CZ algorithm can encrypt the big data as a chaotic cryptosystem which will not decrease the compression speed. Meanwhile, a shareware named “ComZip” is developed based on CZ algorithm. The experiment results show that ComZip in 64 b system can get better compression ratio than WinRAR and 7-zip, and it can be faster than 7-zip in the big data compression. In addition, ComZip encrypts the big data without extra consumption of computing resources. Qin Jiancheng, Lu Yiqin, and Zhong Yu Copyright © 2017 Qin Jiancheng et al. All rights reserved. Pedestrian Stride Length Estimation from IMU Measurements and ANN Based Algorithm Thu, 09 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/6091261/ Pedestrian dead reckoning (PDR) can be used for continuous position estimation when satellite or other radio signals are not available, and the accuracy of the stride length measurement is important. Current stride length estimation algorithms, including linear and nonlinear models, consider a few variable factors, and some rely on high precision and high cost equipment. This paper puts forward a stride length estimation algorithm based on a back propagation artificial neural network (BP-ANN), using a consumer-grade inertial measurement unit (IMU); it then discusses various factors in the algorithm. The experimental results indicate that the error of the proposed algorithm in estimating the stride length is approximately 2%, which is smaller than that of the frequency and nonlinear models. Compared with the latter two models, the proposed algorithm does not need to determine individual parameters in advance if the trained neural net is effective. It can, thus, be concluded that this algorithm shows superior performance in estimating pedestrian stride length. Haifeng Xing, Jinglong Li, Bo Hou, Yongjian Zhang, and Meifeng Guo Copyright © 2017 Haifeng Xing et al. All rights reserved. Affine-Invariant Geometric Constraints-Based High Accuracy Simultaneous Localization and Mapping Thu, 09 Feb 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/1969351/ In this study we describe a new appearance-based loop-closure detection method for online incremental simultaneous localization and mapping (SLAM) using affine-invariant-based geometric constraints. Unlike other pure bag-of-words-based approaches, our proposed method uses geometric constraints as a supplement to improve accuracy. By establishing an affine-invariant hypothesis, the proposed method excludes incorrect visual words and calculates the dispersion of correctly matched visual words to improve the accuracy of the likelihood calculation. In addition, camera’s intrinsic parameters and distortion coefficients are adequate for this method. 3D measuring is not necessary. We use the mechanism of Long-Term Memory and Working Memory (WM) to manage the memory. Only a limited size of the WM is used for loop-closure detection; therefore the proposed method is suitable for large-scale real-time SLAM. We tested our method using the CityCenter and Lip6Indoor datasets. Our proposed method results can effectively correct the typical false-positive localization of previous methods, thus gaining better recall ratios and better precision. Gangchen Hua and Xu Tan Copyright © 2017 Gangchen Hua and Xu Tan. All rights reserved. Disposable Carbon Dots Modified Screen Printed Carbon Electrode Electrochemical Sensor Strip for Selective Detection of Ferric Ions Thu, 02 Feb 2017 09:44:10 +0000 http://www.hindawi.com/journals/js/2017/7576345/ A disposable electrochemical sensor strip based on carbon nanodots (C-Dots) modified screen printed carbon electrode (SPCE) was fabricated for selective detection of ferric ions (Fe3+) in aqueous solution. C-Dots of mean diameters within the range of 1–7 nm were synthesized electrochemically from spent battery carbon rods. The analytical performance of this electrochemical sensor strip was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The deposition of C-Dots had enhanced the electron-transfer kinetics and current intensity of the SPCE remarkably by 734% as compared to that of unmodified SPCE. Under optimized conditions, the electrochemical sensor strip exhibited a linear detection range of 0.5 to 25.0 ppm Fe3+ with a limit of detection (LOD) of  ppm (at ratio = 3). Validation of results by the electrochemical sensor strip was done by comparing analysis results obtained using an Atomic Absorption Spectrometer (AAS). Shao Chien Tan, Suk Fun Chin, and Suh Cem Pang Copyright © 2017 Shao Chien Tan et al. All rights reserved. A Nonlinear Transfer Function Based Receiver for Wideband Interference Suppression Tue, 31 Jan 2017 11:29:13 +0000 http://www.hindawi.com/journals/js/2017/2405942/ Wideband receivers for multistandards operation can simplify the system and lower the cost. In a wideband receiver, the tolerance of large interference signal within the operating band is important. Traditional frequency-domain filtering suffers from lacking in filtering capability for in-band interference signals. This paper describes a receiver system exploiting nonlinear transfer function. Based on the fundamental nonlinear theory, the receiver with nonlinear method can provide frequency-independent filtering for large blockers and linear amplification for weak desired signals simultaneously. The interference suppression performance depends on the amplitude discrimination between the envelope of the large and small signal. The operation of the nonlinear receiver is based on the amplitude of the interferer envelope. A feedforward path is designed to extract the envelope information of the interferer and a feedback path is added to keep track of the environment. With frequency-independent filtering, the nonlinear receiver system enhances both in-band and out-of-band linearity, thus enabling wideband multimode operation. Kuangyuan Ying, Hao Gao, Dusan Milosevic, and Peter Baltus Copyright © 2017 Kuangyuan Ying et al. All rights reserved. High-Accuracy AM-FM Radar with an Active Reflector Mon, 30 Jan 2017 08:29:13 +0000 http://www.hindawi.com/journals/js/2017/8589469/ An amplitude-modulated and frequency-modulated (AM-FM) radar with an active reflector to produce high-accuracy distance measurements is proposed and demonstrated in this paper. The proposed radar consists of an AM-FM base module and an active reflector. The combination of AM and FM modulations resolves ambiguity of the absolute distance in typical AM radars, while improving range accuracy in typical FM radars with narrow bandwidth. Also, the active reflector, which translates the frequency of the received signal, resolves the problem of phase detection interference due to the direct Tx-to-Rx leakage in AM radars. In this paper, the operating principle, experimental tests, and analysis are presented. The implemented AM-FM radar operates in X-band (Tx: 10.5 GHz, Rx: 8.5 GHz) with the 620 MHz bandwidth. The measured range accuracy of less than ±10 mm at a distance of 70 m is obtained. Mun Gak Choi, Dong Sik Woo, Hyun Chul Choi, and Kang Wook Kim Copyright © 2017 Mun Gak Choi et al. All rights reserved. A 7 μW Offset- and Temperature-Compensated pH-to-Digital Converter Sun, 29 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/6158689/ This paper demonstrates a micropower offset- and temperature-compensated smart pH sensor, intended for use in battery-powered RFID systems that monitor the quality of perishable products. Low operation power is essential in such systems to enable autonomous logging of environmental parameters, such as the pH level, over extended periods of time using only a small, low-cost battery. The pH-sensing element in this work is an ion-sensitive extended-gate field-effect transistor (EGFET), which is incorporated in a low-power sensor front-end. The front-end outputs a pH-dependent voltage, which is then digitized by means of a co-integrated incremental delta-sigma ADC. To compensate for the offset and temperature cross-sensitivity of the EGFET, a compensation scheme using a calibration process and a temperature sensor has been devised. A prototype chip has been realized in a 0.16 μm CMOS process. It occupies 0.35 × 3.9 mm2 of die area and draws only 4 μA from a 1.8 V supply. Two different types of custom packaging have been used for measurement purposes. The pH sensor achieves a linearity of better than ±0.1 for pH values ranging from 4 to 10. The calibration and compensation scheme reduces errors due to temperature cross-sensitivity to less than ±0.1 in the temperature range of 6°C to 25°C. Saleh Heidary Shalmany, Matthias Merz, Ali Fekri, Zu-yao Chang, Romano J. O. M. Hoofman, and Michiel A. P. Pertijs Copyright © 2017 Saleh Heidary Shalmany et al. All rights reserved. A 2 GSps, 8-Bit Folding and Interpolation ADC with Foreground Calibration in 90 nm CMOS Technology Thu, 26 Jan 2017 07:01:16 +0000 http://www.hindawi.com/journals/js/2017/3984526/ A single channel 2 GSps, 8-bit folding and interpolation (F&I) analog-to-digital converter (ADC) with foreground calibration in TSMC 90 nm CMOS technology is presented in this paper. The ADC utilizes cascaded folding, which incorporates an interstage sample-and-hold amplifier between the two stages of folding circuits to enhance the quantization time. A master-slave track-and-hold amplifier (THA) with bootstrapped switch is taken as the front-end circuit to improve ADC’s performance. The foreground digital assisted calibration has also been employed to correct the error of zero-crossing point caused by the circuit offset, thus improving the linearity of the ADC. Chip area of the whole ADC including pads is 930 μm × 930 μm. Postsimulation results demonstrate that, under a single supply of 1.2 volts, the power consumption is 210 mW. For the sampling rate of 2 GSps, the signal to noise and distortion ratio (SNDR) is 45.93 dB for Nyquist input signal. Yi Zhang, Qiao Meng, Changchun Zhang, Ying Zhang, Yufeng Guo, Youtao Zhang, Xiaopeng Li, and Lei Yang Copyright © 2017 Yi Zhang et al. All rights reserved. Semantical Markov Logic Network for Distributed Reasoning in Cyber-Physical Systems Tue, 24 Jan 2017 08:50:41 +0000 http://www.hindawi.com/journals/js/2017/4259652/ The challenges associated with developing accurate models for cyber-physical systems are attributable to the intrinsic concurrent and heterogeneous computations of these systems. Even though reasoning based on interconnected domain specific ontologies shows promise in enhancing modularity and joint functionality modelling, it has become necessary to build interoperable cyber-physical systems due to the growing pervasiveness of these systems. In this paper, we propose a semantically oriented distributed reasoning architecture for cyber-physical systems. This model accomplishes reasoning through a combination of heterogeneous models of computation. Using the flexibility of semantic agents as a formal representation for heterogeneous computational platforms, we define autonomous and intelligent agent-based reasoning procedure for distributed cyber-physical systems. Sensor networks underpin the semantic capabilities of this architecture, and semantic reasoning based on Markov logic networks is adopted to address uncertainty in modelling. To illustrate feasibility of this approach, we present a Markov logic based semantic event model for cyber-physical systems and discuss a case study of event handling and processing in a smart home. Abdul-Wahid Mohammed, Yang Xu, Ming Liu, and Haixiao Hu Copyright © 2017 Abdul-Wahid Mohammed et al. All rights reserved. Design of a Compact UWB Antenna with Triple Notched Bands Using Nonuniform Width Slots Tue, 24 Jan 2017 08:33:23 +0000 http://www.hindawi.com/journals/js/2017/7673168/ A compact printed UWB antenna with triple band-notched characteristics is proposed. Instead of conventional uniform width slots, two pairs of quarter-wavelength length nonuniform width slots are embedded into the radiating patch and the ground plane to achieve triple notched bands at 3.5, 5.5, and 8.1 GHz. A parameter study is performed to examine the effect of widths and lengths of the slots on the band-notched characteristics. It indicates that the centre frequencies and the bandwidth of notched bands can be controlled by tuning the physical parameters of the slots. Frequency domain measurements including return loss, antenna transfer function, group delay, and gain of the proposed antenna have been carried out. Corresponding results demonstrate that compact UWB antennas with multiple notched bands can be obtained by using nonuniform width slots. Xu Chen, Feng Xu, and Xu Tan Copyright © 2017 Xu Chen et al. All rights reserved. Improved KLT Algorithm for High-Precision Wavelength Tracking of Optical Fiber Bragg Grating Sensors Wed, 18 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/5412825/ Fiber Bragg Gratings (FBGs) are among the most popular optical fiber sensors. FBGs are well suited for direct detection of temperature and strain and can be functionalized for pressure, humidity, and refractive index sensing. Commercial setups for FBG interrogation are based on white-light sources and spectrometer detectors, which are capable of decoding the spectrum of an FBG array. Low-cost spectrometers record the spectrum on a coarse wavelength grid (typically 78–156 pm), whereas wavelength shifts of 1 pm or lower are required by most of the applications. Several algorithms have been presented for detection of small wavelength shift, even with coarse wavelength sampling; most notably, the Karhunen-Loeve Transform (KLT) was demonstrated. In this paper, an improved algorithm based on KLT is proposed, which is capable of further expanding the performances. Simulations show that, reproducing a commercial spectrometer with 156 pm grid, the algorithm estimates wavelength shift with accuracy well below 1 pm. In typical signal-to-noise ratio (SNR) conditions, the root mean square error is 22–220 fm, while the accuracy is 0.22 pm, despite the coarse sampling. Results have been also validated through experimental characterization. The proposed method allows achieving exceptional accuracy in wavelength tracking, beating the picometer level resolution proposed in most commercial and research software, and, due to fast operation (>5 kHz), is compatible also with structural health monitoring and acoustics. Daniele Tosi Copyright © 2017 Daniele Tosi. All rights reserved. AH-MAC: Adaptive Hierarchical MAC Protocol for Low-Rate Wireless Sensor Network Applications Tue, 17 Jan 2017 07:07:47 +0000 http://www.hindawi.com/journals/js/2017/8105954/ This paper proposes an adaptive hierarchical MAC protocol (AH-MAC) with cross-layer optimization for low-rate and large-scale wireless sensor networks. The main goal of the proposed protocol is to combine the strengths of LEACH and IEEE 802.15.4 while offsetting their weaknesses. The predetermined cluster heads are supported with an energy harvesting circuit, while the normal nodes are battery-operated. To prolong the network’s operational lifetime, the proposed protocol transfers most of the network’s activities to the cluster heads while minimizing the node’s activity. Some of the main features of this protocol include energy efficiency, self-configurability, scalability, and self-healing. The simulation results showed great improvement of the AH-MAC over LEACH protocol in terms of energy consumption and throughput. AH-MAC consumes eight times less energy while improving throughput via acknowledgment support. Adnan Ismail Al-Sulaifanie, Subir Biswas, and Bayez Khorsheed Al-Sulaifanie Copyright © 2017 Adnan Ismail Al-Sulaifanie et al. All rights reserved. Water Pollution Detection Based on Hypothesis Testing in Sensor Networks Mon, 16 Jan 2017 06:50:54 +0000 http://www.hindawi.com/journals/js/2017/3829894/ Water pollution detection is of great importance in water conservation. In this paper, the water pollution detection problems of the network and of the node in sensor networks are discussed. The detection problems in both cases of the distribution of the monitoring noise being normal and nonnormal are considered. The pollution detection problems are analyzed based on hypothesis testing theory firstly; then, the specific detection algorithms are given. Finally, two implementation examples are given to illustrate how the proposed detection methods are used in the water pollution detection in sensor networks and prove the effectiveness of the proposed detection methods. Xu Luo and Jun Yang Copyright © 2017 Xu Luo and Jun Yang. All rights reserved. Four-Terminal Square Piezoresistive Sensors for MEMS Pressure Sensing Wed, 11 Jan 2017 07:25:51 +0000 http://www.hindawi.com/journals/js/2017/6954875/ The sensitivity of four-terminal piezoresistive sensors commonly referred to as van der Pauw (VDP) structure is investigated. The VDP sensor is considered to be fabricated on (100) silicon due to its potential application in MEMS (microelectromechanical systems) pressure sensors. The sensitivity of the VDP sensor may be affected by misalignment during the etching/diffusion process, the nonuniformity of piezoresistive coefficients through the sensor thickness, and pad size with respect to the sensor size. For this particular analysis, the effect of VDP stress sensitivity on variations in pad sizes and through-the-thickness -coefficient variation are studied as the effect of misalignment has already been investigated by researchers. Two three-dimensional (3D) finite element analysis (FEA) models are first developed for both traditional VDP resistance and equivalent four-wire bridge measurements. Then, the FEA models are validated with the closed form analytical solutions for point contacts (“zero” pad size) under different biaxial loads. Once the FEA models are validated, additional simulations are conducted to understand the influence of different parameters on the voltage measurements for an equivalent four-wire bridge configuration. It is observed that pad size and through-the-thickness nonuniformity in piezoresistive constants adversely affect the sensor sensitivity. Awlad Hossain and Ahsan Mian Copyright © 2017 Awlad Hossain and Ahsan Mian. All rights reserved. Trajectory-Based Hierarchical Adaptive Forwarding in Vehicular Ad Hoc Networks Wed, 11 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/4236789/ This paper proposes a Trajectory-Based Hierarchical Adaptive Forwarding (THAF) scheme, tailored and optimized for the efficient multihop vehicle-to-vehicle (v2v) data delivery in vehicular ad hoc networks. We utilize the trajectories of vehicles provided by GPS-based navigation systems to predict forward delay and access area in a privacy-preserving manner. Different from existing trajectory-based forwarding schemes, we establish a hierarchical VANET topology to optimize forwarding path and adopt adaptive diffusion strategy to forward data in light-traffic situations. Through theoretical analysis and extensive simulation, it is shown that our design performs better than the existing schemes. Hao Wang, Liangyin Chen, Shijia Liu, Songtao Fu, Qian Luo, Feng Yin, Limin Sun, and Zhanghua Li Copyright © 2017 Hao Wang et al. All rights reserved. Polymethine Dye as Sensors of NH3 and CO Tue, 10 Jan 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/1320717/ We have investigated the properties of polymethine dyes (PMD) and the purpose of using them as sensors of hazardous gases presence. Research indicates that in case of utilizing PMD as a sensor of hazardous gases we need to use the monochromatic light which wavelength corresponds to the inflection point of the long-wave absorption edge of PMD. Such sensor of hazardous gases can detect changes in the optical density of the sensor layer or the light intensity transmitted through the layer. Petro O. Kondratenko, Yuriy M. Lopatkin, Vita V. Solomko, and Anna G. Malashenko Copyright © 2017 Petro O. Kondratenko et al. All rights reserved. Digital Fluxgate Magnetometer for Detection of Microvibration Thu, 05 Jan 2017 06:30:09 +0000 http://www.hindawi.com/journals/js/2017/6453243/ In engineering practice, instruments, such as accelerometer and laser interferometer, are widely used in vibration measurement of structural parts. A method for using a triaxial fluxgate magnetometer as a microvibration sensor to measure low-frequency pendulum microvibration (not translational vibration) is proposed in this paper, so as to detect vibration from low-frequency vibration sources, such as large rotating machine, large engineering structure, earthquake, and microtremor. This method provides vibration detection based on the environmental magnetic field signal to avoid increased measurement difficulty and error due to different relative positions of permanent magnet and magnetometer on the device under test (DUT) when using the original magnetic measurement method. After fixedly connecting the fluxgate probe with the DUT during the test, the angular displacement due to vibration can be deduced by measuring the geomagnetic field’s magnetic induction intensity change on the orthogonal three components during the vibration. The test shows that the microvibration sensor has angular resolution of over 0.05° and maximum measuring frequency of 64 Hz. As an exploring test aimed to detect the microvibration of earth-orbiting satellite in the in-orbit process, the simulation experiment successfully provides the real-time microvibration information for attitude and orbit control subsystem. Menghui Zhi, Liang Tang, Xin Cao, and Donghai Qiao Copyright © 2017 Menghui Zhi et al. All rights reserved. Detection of Aeromonas hydrophila Using Fiber Optic Microchannel Sensor Wed, 04 Jan 2017 14:22:14 +0000 http://www.hindawi.com/journals/js/2017/8365189/ This research focuses on the detection of Aeromonas hydrophila using fiber optic microchannel biosensor. Microchannel was fabricated by photolithography method. The fiber optic was chosen as signal transmitting medium and light absorption characteristic of different microorganisms was investigated for possible detection. Experimental results showed that Aeromonas hydrophila can be detected at the region of UV-Vis spectra between 352 nm and 354 nm which was comparable to measurement provided by UV spectrophotometer and also theoretical calculation by Beer-Lambert Absorption Law. The entire detection can be done in less than 10 minutes using a total volume of 3 μL only. This result promises good potential of this fiber optic microchannel sensor as a reliable, portable, and disposable sensor. Samla Gauri, Zurina Zainal Abidin, Mohd Firdaus Kamuri, Mohd Adzir Mahdi, and Nurul Amziah Md Yunus Copyright © 2017 Samla Gauri et al. All rights reserved. An Intelligent and Secure Health Monitoring Scheme Using IoT Sensor Based on Cloud Computing Tue, 03 Jan 2017 10:27:02 +0000 http://www.hindawi.com/journals/js/2017/3734764/ Internet of Things (IoT) is the network of physical objects where information and communication technology connect multiple embedded devices to the Internet for collecting and exchanging data. An important advancement is the ability to connect such devices to large resource pools such as cloud. The integration of embedded devices and cloud servers offers wide applicability of IoT to many areas of our life. With the aging population increasing every day, embedded devices with cloud server can provide the elderly with more flexible service without the need to visit hospitals. Despite the advantages of the sensor-cloud model, it still has various security threats. Therefore, the design and integration of security issues, like authentication and data confidentiality for ensuring the elderly’s privacy, need to be taken into consideration. In this paper, an intelligent and secure health monitoring scheme using IoT sensor based on cloud computing and cryptography is proposed. The proposed scheme achieves authentication and provides essential security requirements. Jin-Xin Hu, Chin-Ling Chen, Chun-Long Fan, and Kun-hao Wang Copyright © 2017 Jin-Xin Hu et al. All rights reserved. Online Estimation of the Adhesion Coefficient and Its Derivative Based on the Cascading SMC Observer Tue, 03 Jan 2017 08:53:15 +0000 http://www.hindawi.com/journals/js/2017/8419295/ The adhesion coefficient of wheel-rail surface cannot be directly measured, so a cascaded sliding-mode observer is proposed to observe adhesion coefficient and its derivative. A kinetic model for running heavy-duty locomotive is also established. The state equation of wheel adhesion control system is derived from the equation of traction motor torque balance, and adhesion coefficient is proposed to be calculated by load torque. Then, the cascaded sliding-mode observer is designed, and its stability is justified by Lyapunov stability. Based on the equivalence control principle for sliding-mode variable structure, an algorithm to estimate adhesion coefficient and its derivative is established. The simulation and experimental results are used to verify the effectiveness of the observer with load variations or wheel-rail status changes. Changfan Zhang, Jian Sun, Jing He, and Linfan Liu Copyright © 2017 Changfan Zhang et al. All rights reserved. Rapid Prototyping Human Interfaces Using Stretchable Strain Sensor Mon, 02 Jan 2017 09:53:05 +0000 http://www.hindawi.com/journals/js/2017/9893758/ In the modern society with a variety of information electronic devices, human interfaces increase their importance in a boundary of a human and a device. In general, the human is required to get used to the device. Even if the device is designed as a universal device or a high-usability device, the device is not suitable for all users. The usability of the device depends on the individual user. Therefore, personalized and customized human interfaces are effective for the user. To create customized interfaces, we propose rapid prototyping human interfaces using stretchable strain sensors. The human interfaces comprise parts formed by a three-dimensional printer and the four strain sensors. The three-dimensional printer easily makes customized human interfaces. The outputs of the interface are calculated based on the sensor’s lengths. Experiments evaluate three human interfaces: a sheet-shaped interface, a sliding lever interface, and a tilting lever interface. We confirm that the three human interfaces obtain input operations with a high accuracy. Tokiya Yamaji, Hiroyuki Nakamoto, Hideo Ootaka, Ichiro Hirata, and Futoshi Kobayashi Copyright © 2017 Tokiya Yamaji et al. All rights reserved.