Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Applications of Smartphone-Based Sensors in Agriculture: A Systematic Review of Research Thu, 30 Jul 2015 15:56:24 +0000 http://www.hindawi.com/journals/js/2015/195308/ Smartphones have become a useful tool in agriculture because their mobility matches the nature of farming, the cost of the device is highly accessible, and their computing power allows a variety of practical applications to be created. Moreover, smartphones are nowadays equipped with various types of physical sensors which make them a promising tool to assist diverse farming tasks. This paper systematically reviews smartphone applications mentioned in research literature that utilize smartphone built-in sensors to provide agricultural solutions. The initial 1,500 articles identified through database search were screened based on exclusion criteria and then reviewed thoroughly in full text, resulting in 22 articles included in this review. The applications are categorized according to their agricultural functions. Those articles reviewed describe 12 farming applications, 6 farm management applications, 3 information system applications, and 4 extension service applications. GPS and cameras are the most popular sensors used in the reviewed papers. This shows an opportunity for future applications to utilize other sensors such as accelerometer to provide advanced agricultural solutions. Suporn Pongnumkul, Pimwadee Chaovalit, and Navaporn Surasvadi Copyright © 2015 Suporn Pongnumkul et al. All rights reserved. Oceanographic Multisensor Buoy Based on Low Cost Sensors for Posidonia Meadows Monitoring in Mediterranean Sea Thu, 30 Jul 2015 13:32:16 +0000 http://www.hindawi.com/journals/js/2015/920168/ There are some underwater areas with high ecological interest that should be monitored. Posidonia and seagrasses exert considerable work in protecting the coastline from erosion. In these areas, many animals and organisms live and find the grassland food and the protection against predators. It is considered a bioindicator of the quality of coastal marine waters. It is important to monitor them and maintain these ecological communities as clean as possible. In this paper, we present an oceanographic buoy for Posidonia meadows monitoring. It is based on a set of low cost sensors which are able to collect data from water such as salinity, temperature, and turbidity and from the weather as temperature, relative humidity, and rainfall, among others. The system is mounted in a buoy which keeps it isolated to possible oxidation problems. Data gathered are processed using a microcontroller. Finally the buoy is connected with a base station placed on the mainland through a wireless connection using a FlyPort module. The network performance is checked in order to ensure that no delays will be generated on the data transmission. This proposal could be used to monitor other areas with special ecological interest and for monitoring and supervising aquaculture activities. Sandra Sendra, Lorena Parra, Jaime Lloret, and José Miguel Jiménez Copyright © 2015 Sandra Sendra et al. All rights reserved. Experimental Assessment of a Variable Orifice Flowmeter for Respiratory Monitoring Thu, 30 Jul 2015 12:03:50 +0000 http://www.hindawi.com/journals/js/2015/752540/ Accurate measurement of gas exchanges is essential in mechanical ventilation and in respiratory monitoring. Among the large number of commercial flowmeters, only few kinds of sensors are used in these fields. Among them, variable orifice meters (VOMs) show some valuable characteristics, such as linearity, good dynamic response, and low cost. This paper presents the characterization of a commercial VOM intended for application in respiratory monitoring. Firstly, two nominally identical VOMs were calibrated within ±10 L·min−1, to assess their metrological properties. Furthermore, experiments were performed by humidifying the air, to evaluate the influence of vapor condensation on sensor’s performances. The condensation influence was investigated during two long lasting trials (i.e., 4 hours) by delivering 4 L·min−1 and 8 L·min−1. Data show that the two VOMs’ responses are linear and their response is comparable (sensitivity difference of 1.4%, RMSE of 1.50 Pa); their discrimination threshold is <0.5 L·min−1, and the settling time is about 66 ms. The condensation within the VOM causes a negligible change in sensor sensitivity and a very slight deterioration of precision. The good static and dynamic properties and the low influence of condensation on sensor’s response make this VOM suitable for applications in respiratory function monitoring. Giuseppe Tardi, Carlo Massaroni, Paola Saccomandi, and Emiliano Schena Copyright © 2015 Giuseppe Tardi et al. All rights reserved. Deep Convolutional Neural Networks for Hyperspectral Image Classification Thu, 30 Jul 2015 07:36:50 +0000 http://www.hindawi.com/journals/js/2015/258619/ Recently, convolutional neural networks have demonstrated excellent performance on various visual tasks, including the classification of common two-dimensional images. In this paper, deep convolutional neural networks are employed to classify hyperspectral images directly in spectral domain. More specifically, the architecture of the proposed classifier contains five layers with weights which are the input layer, the convolutional layer, the max pooling layer, the full connection layer, and the output layer. These five layers are implemented on each spectral signature to discriminate against others. Experimental results based on several hyperspectral image data sets demonstrate that the proposed method can achieve better classification performance than some traditional methods, such as support vector machines and the conventional deep learning-based methods. Wei Hu, Yangyu Huang, Li Wei, Fan Zhang, and Hengchao Li Copyright © 2015 Wei Hu et al. All rights reserved. Sensors for Robotics 2015 Thu, 30 Jul 2015 06:25:12 +0000 http://www.hindawi.com/journals/js/2015/412626/ Aiguo Song, Guangming Song, Daniela Constantinescu, Lei Wang, and Quanjun Song Copyright © 2015 Aiguo Song et al. All rights reserved. Determining the Optimum Exposure and Recovery Periods for Efficient Operation of a QCM Based Elemental Mercury Vapor Sensor Wed, 29 Jul 2015 12:15:26 +0000 http://www.hindawi.com/journals/js/2015/727432/ In recent years, mass based transducers such as quartz crystal microbalance (QCM) have gained huge interest as potential sensors for online detection of elemental mercury (Hg0) vapor from anthropogenic sources due to their high portability and robust nature enabling them to withstand harsh industrial environments. In this study, we determined the optimal Hg0 exposure and recovery times of a QCM based sensor for ensuring its efficient operation while monitoring low concentrations of Hg0 vapor (<400 ). The developed sensor was based on an AT-cut quartz substrate and utilized two gold (Au) films on either side of the substrate which functions as the electrodes and selective layer simultaneously. Given the temporal response mechanisms associated with mass based mercury sensors, the experiments involved the variation of Hg0 vapor exposure periods while keeping the recovery time constant following each exposure and vice versa. The results indicated that an optimum exposure and recovery periods of 30 and 90 minutes, respectively, can be utilized to acquire the highest response magnitudes and recovery rate towards a certain concentration of Hg0 vapor whilst keeping the time it takes to report an accurate reading by the sensor to a minimum level as required in real-world applications. K. M. Mohibul Kabir, Samuel J. Ippolito, Glenn I. Matthews, S. Bee Abd Hamid, Ylias M. Sabri, and Suresh K. Bhargava Copyright © 2015 K. M. Mohibul Kabir et al. All rights reserved. Kalman Filter Sensor Fusion for Mecanum Wheeled Automated Guided Vehicle Localization Wed, 29 Jul 2015 10:36:44 +0000 http://www.hindawi.com/journals/js/2015/347379/ The Mecanum automated guided vehicle (AGV), which can move in any direction by using a special wheel structure with a LIM-wheel and a diagonally positioned roller, holds considerable promise for the field of industrial electronics. A conventional method for Mecanum AGV localization has certain limitations, such as slip phenomena, because there are variations in the surface of the road and ground friction. Therefore, precise localization is a very important issue for the inevitable slip phenomenon situation. So a sensor fusion technique is developed to cope with this drawback by using the Kalman filter. ENCODER and StarGazer were used for sensor fusion. StarGazer is a position sensor for an image recognition device and always generates some errors due to the limitations of the image recognition device. ENCODER has also errors accumulating over time. On the other hand, there are no moving errors. In this study, we developed a Mecanum AGV prototype system and showed by simulation that we can eliminate the disadvantages of each sensor. We obtained the precise localization of the Mecanum AGV in a slip phenomenon situation via sensor fusion using a Kalman filter. Sang Won Yoon, Seong-Bae Park, and Jong Shik Kim Copyright © 2015 Sang Won Yoon et al. All rights reserved. Person Tracking System by Fusing Multicues Based on Patches Wed, 29 Jul 2015 08:17:32 +0000 http://www.hindawi.com/journals/js/2015/760435/ A person tracking algorithm by fusing multicues based on patches is proposed to solve the problem of distinguishing person, occlusion, and illumination variations. Kinect is mounted on the robot for providing color images and depth maps. A detector representing a person by using the fusion of multicues based on patches is proposed. The detector divides the person into many patches and then represents each patch by using depth-color histograms and depth-texture histograms. The appearance representation, considering depth, color, and texture information, has powerful discrimination ability to handle the problems of occlusion, illumination changes, and pose variations. Considering the motion of the robot and person, a tracker called motion extended Kalman filter (MEKF) is presented to predict the person’s position. The result of the tracker is treated as a candidate sample of the detector, and then the result of the detector is the previous knowledge of the tracker. The detector and tracker supplement each other and improve the tracking performance. To drive the robot towards the given person precisely, a fuzzy based intelligent gear control strategy (FZ-IGS) is implemented. Experiments demonstrate that the proposed approach can track a person in a complex environment and have an optimum performance. Song Min Jia, Li Jia Wang, Xiu Zhi Li, and Lin Feng Wen Copyright © 2015 Song Min Jia et al. All rights reserved. Urban Land Use and Land Cover Classification Using Remotely Sensed SAR Data through Deep Belief Networks Wed, 29 Jul 2015 08:15:59 +0000 http://www.hindawi.com/journals/js/2015/538063/ Land use and land cover (LULC) mapping in urban areas is one of the core applications in remote sensing, and it plays an important role in modern urban planning and management. Deep learning is springing up in the field of machine learning recently. By mimicking the hierarchical structure of the human brain, deep learning can gradually extract features from lower level to higher level. The Deep Belief Networks (DBN) model is a widely investigated and deployed deep learning architecture. It combines the advantages of unsupervised and supervised learning and can archive good classification performance. This study proposes a classification approach based on the DBN model for detailed urban mapping using polarimetric synthetic aperture radar (PolSAR) data. Through the DBN model, effective contextual mapping features can be automatically extracted from the PolSAR data to improve the classification performance. Two-date high-resolution RADARSAT-2 PolSAR data over the Great Toronto Area were used for evaluation. Comparisons with the support vector machine (SVM), conventional neural networks (NN), and stochastic Expectation-Maximization (SEM) were conducted to assess the potential of the DBN-based classification approach. Experimental results show that the DBN-based method outperforms three other approaches and produces homogenous mapping results with preserved shape details. Qi Lv, Yong Dou, Xin Niu, Jiaqing Xu, Jinbo Xu, and Fei Xia Copyright © 2015 Qi Lv et al. All rights reserved. Bayesian Information Criterion Based Feature Filtering for the Fusion of Multiple Features in High-Spatial-Resolution Satellite Scene Classification Wed, 29 Jul 2015 07:36:36 +0000 http://www.hindawi.com/journals/js/2015/142612/ This paper presents a novel classification method for high-spatial-resolution satellite scene classification introducing Bayesian information criterion (BIC)-based feature filtering process to further eliminate opaque and redundant information between multiple features. Firstly, two diverse and complementary feature descriptors are extracted to characterize the satellite scene. Then, sparse canonical correlation analysis (SCCA) with penalty function is employed to fuse the extracted feature descriptors and remove the ambiguities and redundancies between them simultaneously. After that, a two-phase Bayesian information criterion (BIC)-based feature filtering process is designed to further filter out redundant information. In the first phase, we gradually impose a constraint via an iterative process to set a constraint on the loadings for averting sparse correlation descending below to a lower confidence limit of the approximated canonical correlation. In the second phase, Bayesian information criterion (BIC) is utilized to conduct the feature filtering which sets the smallest loading in absolute value to zero in each iteration for all features. Lastly, a support vector machine with pyramid match kernel is applied to obtain the final result. Experimental results on high-spatial-resolution satellite scenes demonstrate that the suggested approach achieves satisfactory performance in classification accuracy. Da Lin, Xin Xu, and Fangling Pu Copyright © 2015 Da Lin et al. All rights reserved. A Control Strategy with Tactile Perception Feedback for EMG Prosthetic Hand Wed, 29 Jul 2015 07:35:44 +0000 http://www.hindawi.com/journals/js/2015/869175/ To improve the control effectiveness and make the prosthetic hand not only controllable but also perceivable, an EMG prosthetic hand control strategy was proposed in this paper. The control strategy consists of EMG self-learning motion recognition, backstepping controller with stiffness fuzzy observation, and force tactile representation. EMG self-learning motion recognition is used to reduce the influence on EMG signals caused by the uncertainty of the contacting position of the EMG sensors. Backstepping controller with stiffness fuzzy observation is used to realize the position control and grasp force control. Velocity proportional control in free space and grasp force tracking control in restricted space can be realized by the same controller. The force tactile representation helps the user perceive the states of the prosthetic hand. Several experiments were implemented to verify the effect of the proposed control strategy. The results indicate that the proposed strategy has effectiveness. During the experiments, the comments of the participants show that the proposed strategy is a better choice for amputees because of the improved controllability and perceptibility. Changcheng Wu, Aiguo Song, Yun Ling, Nan Wang, and Lei Tian Copyright © 2015 Changcheng Wu et al. All rights reserved. Pressure Sensor: State of the Art, Design, and Application for Robotic Hand Wed, 29 Jul 2015 07:09:32 +0000 http://www.hindawi.com/journals/js/2015/846487/ We survey the state of the art in a variety of force sensors for designing and application of robotic hand. Most of the force sensors are examined based on tactile sensing. For a decade, many papers have widely discussed various sensor technologies and transducer methods which are based on microelectromechanical system (MEMS) and silicon used for improving the accuracy and performance measurement of tactile sensing capabilities especially for robotic hand applications. We found that transducers and materials such as piezoresistive and polymer, respectively, are used in order to improve the sensing sensitivity for grasping mechanisms in future. This predicted growth in such applications will explode into high risk tasks which requires very precise purposes. It shows considerable potential and significant levels of research attention. Ahmed M. Almassri, W. Z. Wan Hasan, S. A. Ahmad, A. J. Ishak, A. M. Ghazali, D. N. Talib, and Chikamune Wada Copyright © 2015 Ahmed M. Almassri et al. All rights reserved. Automatic Change Detection Method of Multitemporal Remote Sensing Images Based on 2D-Otsu Algorithm Improved by Firefly Algorithm Wed, 29 Jul 2015 06:57:38 +0000 http://www.hindawi.com/journals/js/2015/327123/ This paper presents a new automatic change detection method of multitemporal remote sensing images based on 2D-Otsu algorithm improved by Firefly algorithm. The proposed method is designed to automatically extract the changing area between two temporal remote sensing images. First, two different temporal remote sensing images were acquired through difference value method of remote sensing images; then, the 2D-Otsu threshold segmentation principles are analyzed and the optimal threshold of 2D-Otsu threshold segmentation method is figured out by using the Firefly algorithm, where the difference images are conducted with binary classification to obtain the changing category and the nonchanging category; finally, the proposed method is used to carry out change detection experiments on the two selected areas, where a variety of methods are compared. Experimental results show that the proposed method can effectively and quickly extract the changing area between the two temporal remote sensing images; thus, it is an effective method of change detection for remote sensing images. Liang Huang, Yuanmin Fang, Xiaoqing Zuo, and Xueqin Yu Copyright © 2015 Liang Huang et al. All rights reserved. Automatic Fusion of Hyperspectral Images and Laser Scans Using Feature Points Tue, 28 Jul 2015 14:29:02 +0000 http://www.hindawi.com/journals/js/2015/415361/ Automatic fusion of different kinds of image datasets is so intractable with diverse imaging principle. This paper presents a novel method for automatic fusion of two different images: 2D hyperspectral images acquired with a hyperspectral camera and 3D laser scans obtained with a laser scanner, without any other sensor. Only a few corresponding feature points are used, which are automatically extracted from a scene viewed by the two sensors. Extraction method of feature points relies on SURF algorithm and camera model, which can convert a 3D laser scan into a 2D laser image with the intensity of the pixels defined by the attributes in the laser scan. Moreover, Collinearity Equation and Direct Linear Transformation are used to create the initial corresponding relationship of the two images. Adjustment is also used to create corrected values to eliminate errors. The experimental result shows that this method is successfully validated with images collected by a hyperspectral camera and a laser scanner. Xiao Zhang, Aiwu Zhang, and Xiangang Meng Copyright © 2015 Xiao Zhang et al. All rights reserved. Hybrid Motion Planning Method for Autonomous Robots Using Kinect Based Sensor Fusion and Virtual Plane Approach in Dynamic Environments Tue, 28 Jul 2015 14:18:57 +0000 http://www.hindawi.com/journals/js/2015/471052/ A new reactive motion planning method for an autonomous vehicle in dynamic environments is proposed. The new dynamic motion planning method combines a virtual plane based reactive motion planning technique with a sensor fusion based obstacle detection approach, which results in improving robustness and autonomy of vehicle navigation within unpredictable dynamic environments. The key feature of the new reactive motion planning method is based on a local observer in the virtual plane which allows the effective transformation of complex dynamic planning problems into simple stationary in the virtual plane. In addition, a sensor fusion based obstacle detection technique provides the pose estimation of moving obstacles by using a Kinect sensor and a sonar sensor, which helps to improve the accuracy and robustness of the reactive motion planning approach in uncertain dynamic environments. The performance of the proposed method was demonstrated through not only simulation studies but also field experiments using multiple moving obstacles even in hostile environments where conventional method failed. Doopalam Tuvshinjargal, Byambaa Dorj, and Deok Jin Lee Copyright © 2015 Doopalam Tuvshinjargal et al. All rights reserved. Applications of Polarimetric SAR Tue, 28 Jul 2015 11:48:49 +0000 http://www.hindawi.com/journals/js/2015/316391/ Jian Yang, Yoshio Yamaguchi, Jong-Sen Lee, Ridha Touzi, and Wolfgang-Martin Boerner Copyright © 2015 Jian Yang et al. All rights reserved. Smart Sensing Technologies and Their Applications in Civil Infrastructures Tue, 28 Jul 2015 06:37:54 +0000 http://www.hindawi.com/journals/js/2015/265106/ Hong-Hu Zhu, Fei Dai, Zhenhua Zhu, Tuan Guo, and Xiao-Wei Ye Copyright © 2015 Hong-Hu Zhu et al. All rights reserved. A Comparative Study on Frequency Sensitivity of a Transmission Tower Mon, 27 Jul 2015 14:02:50 +0000 http://www.hindawi.com/journals/js/2015/610416/ Sensitivity analysis can take structural parameters as variable and achieve the relationship only with one time analysis, which will dramatically reduce the analytical work especially for large scale structures. The comparative study on frequency sensitivity of a transmission tower is actively carried out in this study. The three-dimensional analytical model of a transmission tower is established by using the finite element (FE) method. The sensitivity coefficients to natural frequencies are deduced based on the equation of motion of the tower. In addition, the expression of the frequency sensitivity to Young’s modulus, density of material, the cross area of members, torsional stiffness, and bending moment inertia is proposed. A real transmission tower constructed in China is taken as an example to examine the feasibility and reliability of the proposed sensitivity computation approach. An intensive parametric study is conducted in detail in order to compare the sensitivity coefficients of different physical parameters. The work on an example structure indicated that the magnitudes of the sensitivity coefficients of Young’s modulus, the density, and the cross area are much larger than those of the torsional stiffness and the bending moment inertia. Peng-yun Li, Bo Chen, Wen-ping Xie, and Xiang Xiao Copyright © 2015 Peng-yun Li et al. All rights reserved. Distributed Measurement of Temperature for PCC Energy Pile Using BOFDA Mon, 27 Jul 2015 13:22:04 +0000 http://www.hindawi.com/journals/js/2015/610473/ PCC energy pile is a new technology for sustainable development of urban areas. Learning and understanding the temperature variation of PCC energy pile are very important to its development and application. In this study, the Brillouin optical frequency domain analysis (BOFDA) technology is firstly used to measure the temperature variation of PCC energy pile from a model test. The aim is to provide an optical fiber sensing method for monitoring the temperature distribution of PCC energy pile. When the temperatures of circulating water are 70°C, 60°C, 50°C, and 40°C, the result shows that the temperatures of PCC energy pile under different conditions are measured well by the optical fiber sensor. It will help to master the temperature distribution and thermomechanical characteristic of PCC energy pile. It can also provide the important scientific and theoretical basis for the design and application of PCC energy pile. Lei Gao, Baoquan Ji, Gangqiang Kong, Xu Huang, Mingkun Li, and Ali H. Mahfouz Copyright © 2015 Lei Gao et al. All rights reserved. Toward Collinearity-Avoidable Localization for Wireless Sensor Network Mon, 27 Jul 2015 12:48:42 +0000 http://www.hindawi.com/journals/js/2015/908956/ In accordance with the collinearity problem during computation caused by the beacon nodes used for location estimation which are close to be in the same line or same plane, two solutions are proposed in this paper: the geometric analytical localization algorithm based on positioning units and the localization algorithm based on the multivariate analysis method. The geometric analytical localization algorithm based on positioning units analyzes the topology quality of positioning units used to estimate location and provides quantitative criteria based on that; the localization algorithm based on the multivariate analysis method uses the multivariate analysis method to filter and integrate the beacon nodes coordinate matrixes during the process of location estimation. Both methods can avoid low estimation accuracy and instability caused by multicollinearity. Xiaoyong Yan, Aiguo Song, Jimin Yu, and Zhong Yang Copyright © 2015 Xiaoyong Yan et al. All rights reserved. Failure Mechanism of Rock Bridge Based on Acoustic Emission Technique Mon, 27 Jul 2015 12:34:01 +0000 http://www.hindawi.com/journals/js/2015/964730/ Acoustic emission (AE) technique is widely used in various fields as a reliable nondestructive examination technology. Two experimental tests were carried out in a rock mechanics laboratory, which include (1) small scale direct shear tests of rock bridge with different lengths and (2) large scale landslide model with locked section. The relationship of AE event count and record time was analyzed during the tests. The AE source location technology and comparative analysis with its actual failure model were done. It can be found that whether it is small scale test or large scale landslide model test, AE technique accurately located the AE source point, which reflected the failure generation and expansion of internal cracks in rock samples. Large scale landslide model with locked section test showed that rock bridge in rocky slope has typical brittle failure behavior. The two tests based on AE technique well revealed the rock failure mechanism in rocky slope and clarified the cause of high speed and long distance sliding of rocky slope. Guoqing Chen, Yan Zhang, Runqiu Huang, Fan Guo, and Guofeng Zhang Copyright © 2015 Guoqing Chen et al. All rights reserved. A Study on Distribution Measurement and Mechanism of Deformation due to Water Loss of Overburden Layer in Vertical Shaft Mon, 27 Jul 2015 12:33:19 +0000 http://www.hindawi.com/journals/js/2015/531428/ Based on FBG fiber Bragg grating technology and BOTDA distributed optical fiber sensing technology, this study uses fine sand to simulate overburden layer in vertical shaft model equipment. It studies the placing technique and test method for optical fiber sensors in the overburden layer, combined with MODFLOW software to simulate the change of the water head value when the overburden layer is losing water, and obtains the deformation features of overburden layer. The results show, at the beginning of water loss, the vertical deformation increases due to larger hydraulic pressure drop, while the deformation decreases gradually and tends to be stable with the hydraulic pressure drop reducing. The circumferential deformation is closely related to such factors as the distance between each drainage outlet, the variations of water head value, and the method of drainage. The monitoring result based on optical fiber sensing technology is consistent with the characteristics of water loss in overburden layer simulated by MODFLOW software, which shows that the optical fiber sensing technology applied to monitor shaft overburden layer is feasible. Chunde Piao, Jun Yuan, Dangliang Wang, and Pengtao Li Copyright © 2015 Chunde Piao et al. All rights reserved. Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam Mon, 27 Jul 2015 12:22:47 +0000 http://www.hindawi.com/journals/js/2015/470905/ Geomechanical model testing is an important method for studying the overall stability of high arch dams. The main task of a geomechanical model test is deformation monitoring. Currently, many types of deformation instruments are used for deformation monitoring of dam models, which provide valuable information on the deformation characteristics of the prototype dams. However, further investigation is required for assessing the overall stability of high arch dams through analyzing deformation monitoring data. First, a relationship for assessing the stability of dams is established based on the comprehensive model test method. Second, a stability evaluation system is presented based on the deformation monitoring data, together with the relationships between the deformation and overloading coefficient. Finally, the comprehensive model test method is applied to study the overall stability of the Jinping-I high arch dam. A three-dimensional destructive test of the geomechanical model dam is conducted under reinforced foundation conditions. The deformation characteristics and failure mechanisms of the dam abutments and foundation were investigated. The test results indicate that the stability safety factors of the dam abutments and foundation range from 5.2 to 6.0. These research results provide an important scientific insight into the design, construction, and operation stages of this project. Baoquan Yang, Lin Zhang, Enlong Liu, Jianhua Dong, Honghu Zhu, and Yuan Chen Copyright © 2015 Baoquan Yang et al. All rights reserved. Structural Health Monitoring of Wind Turbine Blades: Acoustic Source Localization Using Wireless Sensor Networks Mon, 27 Jul 2015 12:17:47 +0000 http://www.hindawi.com/journals/js/2015/139695/ Structural health monitoring (SHM) is important for reducing the maintenance and operation cost of safety-critical components and systems in offshore wind turbines. This paper proposes an in situ wireless SHM system based on an acoustic emission (AE) technique. By using this technique a number of challenges are introduced due to high sampling rate requirements, limitations in the communication bandwidth, memory space, and power resources. To overcome these challenges, this paper focused on two elements: (1) the use of an in situ wireless SHM technique in conjunction with the utilization of low sampling rates; (2) localization of acoustic sources which could emulate impact damage or audible cracks caused by different objects, such as tools, bird strikes, or strong hail, all of which represent abrupt AE events and could affect the structural health of a monitored wind turbine blade. The localization process is performed using features extracted from aliased AE signals based on a developed constraint localization model. To validate the performance of these elements, the proposed system was tested by testing the localization of the emulated AE sources acquired in the field. Omar Mabrok Bouzid, Gui Yun Tian, Kanapathippillai Cumanan, and David Moore Copyright © 2015 Omar Mabrok Bouzid et al. All rights reserved. Application of Distributed Optical Fiber Sensing Technology in the Anomaly Detection of Shaft Lining in Grouting Mon, 27 Jul 2015 12:06:41 +0000 http://www.hindawi.com/journals/js/2015/678634/ The rupture of the shaft lining caused by grouting has seriously undermined the safety in coal mining. Based on BOTDR distributed optical fiber sensing technology, this paper studied the layout method of optical fiber sensors and the anomaly detection method of the deformation and obtained the evolution law of shaft deformation triggered by grouting. The research results showed that the bonding problem of optical fiber sensors in damp environment could be effectively solved, by applying the binder consisting of sodium silicate and cement. Through BOTDR-based deformation detection, the real-time deformation of the shaft lining caused by grouting was immediately spotted. By comparing the respective strain of shaft lining deformation and concrete deformation, the risk range of shaft lining grouting was identified. With the additional strain increment of the shaft lining triggered by each process of grouting, the saturated condition of grouting volume in strata was analyzed, providing an important technical insight into the field construction and the safety of the shaft lining. Chunde Piao, Jun Yuan, Bin Shi, Haijun Lu, Guangqing Wei, and Chunsheng Gu Copyright © 2015 Chunde Piao et al. All rights reserved. Development and Application of Smart Geogrid Embedded with Fiber Bragg Grating Sensors Mon, 27 Jul 2015 11:23:14 +0000 http://www.hindawi.com/journals/js/2015/108209/ Smart geogrids embedded with fiber Bragg grating (FBG) for reinforcement as well as measurement of geotechnical structures have been developed. After the fabricating process of the geogrids is detailed, finite element (FE) simulations are conducted to analyze the strain distribution of geogrids and the strain transfer characteristics from geogrids to fiber optic. Results indicate that FBG should be deployed in the middle of the geogrids rib to make sure that uniform strain distribution along the FBG. Also, PVC protective sleeves, which are used to protect fiber optic when integrated with geogrids, have smaller strain transfer loss than nylon sleeves. Tensile experiments are conducted to test strain measurement performance of proposed geogrids, and the results demonstrate that proposed smart geogrids have good linearity and consistency. Temperature experiments show that FBG embedded in geogrids has higher temperature sensitivity, and the temperature induced error can be compensated by an extra FBG strain-independent sensor. Furthermore, designed smart geogrids are used in a geotechnical model test to monitor strain during tunnel excavation. The strain tendency measured by smart geogrids and traditional strain sensor agree very well. The results indicate that smart geogrids embedded with FBGs can be an effective method to measure strains for geological engineering related applications. Zheng-fang Wang, Jing Wang, Qing-mei Sui, Xun-mei Liang, Lei Jia, Shu-cai Li, and Shi-de Lu Copyright © 2015 Zheng-fang Wang et al. All rights reserved. Axis-Exchanged Compensation and Gait Parameters Analysis for High Accuracy Indoor Pedestrian Dead Reckoning Mon, 27 Jul 2015 11:07:29 +0000 http://www.hindawi.com/journals/js/2015/915837/ Pedestrian dead reckoning (PDR) is an effective way for navigation coupled with GNSS (Global Navigation Satellite System) or weak GNSS signal environment like indoor scenario. However, indoor location with an accuracy of 1 to 2 meters determined by PDR based on MEMS-IMU is still very challenging. For one thing, heading estimation is an important problem in PDR because of the singularities. For another thing, walking distance estimation is also a critical problem for pedestrian walking with randomness. Based on the above two problems, this paper proposed axis-exchanged compensation and gait parameters analysis algorithm to improve the navigation accuracy. In detail, an axis-exchanged compensation factored quaternion algorithm is put forward first to overcome the singularities in heading estimation without increasing the amount of computation. Besides, real-time heading is updated by R-adaptive Kalman filter. Moreover, gait parameters analysis algorithm can be divided into two steps: cadence detection and step length estimation. Thus, a method of cadence classification and interval symmetry is proposed to detect the cadence accurately. Furthermore, a step length model adjusted by cadence is established for step length estimation. Compared to the traditional PDR navigation, experimental results showed that the error of navigation reduces 32.6%. Honghui Zhang, Jinyi Zhang, Duo Zhou, Wei Wang, Jianyu Li, Feng Ran, and Yuan Ji Copyright © 2015 Honghui Zhang et al. All rights reserved. Study of Three-Component FBG Vibration Sensor for Simultaneous Measurement of Vibration, Temperature, and Verticality Mon, 27 Jul 2015 11:03:34 +0000 http://www.hindawi.com/journals/js/2015/382865/ To achieve simultaneous measurement of measurand vibration, temperature, and verticality, a three-component fiber Brag grating (TVFBG) vibration sensor is proposed in this paper. Polymer and metal diaphragm sensitization methods are utilized to improve this sensor measurement sensitivity. Project matrix theory is adopted to analyze this sensor. Theoretically, nonsingular measuring coefficient matrix of this TVFBG sensor made up by three measurand coefficient matrixes is established. In order to effectively extract measurand, Hilbert-Huang transform (HHT) is accepted to process this sensor’s center wavelength signals. Calibration experiments are carried out to verify the performance of this TVFBG sensor. Experiment data confirm that this sensor has excellent frequency response and show good linearity at temperature and verticality measurement. Wrist rotation angle measurement experiment is also implemented to further identify this sensor practical value. Through analyzing by HHT, experiment results show that the angle measurement sensitivities of three fiber Brag gratings which are included in this sensor are separately 25.2 pm/°, 38.2 pm/°, and 38.3 pm/°. Jiang Shan-chao, Wang Jing, Sui Qing-mei, Ye Qing-lin, and Wang Li-jun Copyright © 2015 Jiang Shan-chao et al. All rights reserved. Application of Method for Dynamic Analysis of Additional Strain and Fracture Warning in Shaft Lining Mon, 27 Jul 2015 10:37:20 +0000 http://www.hindawi.com/journals/js/2015/376498/ In the past few decades, enormous losses have been induced by hundreds of vertical shafts collapse. This study is based on long-term in situ monitoring data of several mines with overburden soil layers in East China in the past six years. modeling based on fractal theory was used to analyze the development of additional strains in shafts by using Hurst exponent. It can be found that from the monitoring results the Hurst effect is significant ranging from 0.5 to 1.0. Its trend also is in good agreement with forward-biased random distribution. Hence, method can be used to predict the additional strain along the shaft lining. In this paper, Hurst exponent shows an irregular phenomenon before cracking. It is proved that Hurst exponent can be used to predicate the progressive failure of shaft lining from abnormal state to normal state. This paper presents the prediction of shaft lining failures using strains measured by embedded strain gauges in the thick overburden soil layers in east China. Guangsi Zhao, Guoqing Zhou, and Jianzhou Wang Copyright © 2015 Guangsi Zhao et al. All rights reserved. Microseismic Signal Characterization and Numerical Simulation of Concrete Beam Subjected to Three-Point Bending Fracture Mon, 27 Jul 2015 10:28:34 +0000 http://www.hindawi.com/journals/js/2015/987232/ To study the generation mechanism and failure mode of cracks in mass concrete, microseismic monitoring is conducted on the fracture processes of the three-point bending roller compacted concrete (RCC) beam of Guanyinyan hydropower station. The spectrum characteristics of microseismic signals in different deformation and failure stages of the concrete beam are analyzed, and the identification method of the fracture stages and crack propagation precursors of concrete beam is established. Meanwhile, the Realistic Failure Process Analysis code (RFPA) is adopted to simulate and analyze the entire failure processes of concrete beam from its cracks initiation, development, propagation, and coalescence, until macroscopic fractures formation subjected to three-point bending test. The relation curve of the load, loaded displacement, and acoustic emission (AE) of concrete beam in the three-point bending test is also obtained. It is found that the failure characteristics of concrete beam obtained from numerical experiments agree well with the field physical test results. The heterogeneity of concrete is the major cause of zigzag propagation paths of beam cracks subjected to three-point bending tests. The results lay foundation for further exploring the formation mechanism of dam concrete cracks of Guanyinyan hydropower station. Nuwen Xu, Feng Dai, Chun Sha, Yingcheng Lei, and Biao Li Copyright © 2015 Nuwen Xu et al. All rights reserved.