Journal of Sensors https://www.hindawi.com The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Close Range Photogrammetry for Direct Multiple Feature Positioning Measurement without Targets Mon, 29 May 2017 06:26:17 +0000 http://www.hindawi.com/journals/js/2017/1605943/ The main objective of this study is to present a new method to carry out measurements so as to improve the positioning verification step in the wind hub part dimensional validation process. This enhancement will speed up the measuring procedures for these types of parts. An industrial photogrammetry based system was applied to take advantage of its results, and new functions were added to existing capabilities. In addition to a new development based on photogrammetry modelling and image processing, a measuring procedure was defined based on optical and vision system considerations. A validation against a certified procedure by means of a laser-tracker has also been established obtaining deviations of ±0.125 μm/m. Gorka Kortaberria, Aitor Olarra, Alberto Tellaeche, and Rikardo Minguez Copyright © 2017 Gorka Kortaberria et al. All rights reserved. An Automatic Assembling System for Sealing Rings Based on Machine Vision Wed, 24 May 2017 08:42:55 +0000 http://www.hindawi.com/journals/js/2017/4207432/ In order to grab and place the sealing rings of battery lid quickly and accurately, an automatic assembling system for sealing rings based on machine vision is developed in this paper. The whole system is composed of the light sources, cameras, industrial control units, and a 4-degree-of-freedom industrial robot. Specifically, the sealing rings are recognized and located automatically with the machine vision module. Then industrial robot is controlled for grabbing the sealing rings dynamically under the joint work of multiple control units and visual feedback. Furthermore, the coordinates of the fast-moving battery lid are tracked by the machine vision module. Finally the sealing rings are placed on the sealing ports of battery lid accurately and automatically. Experimental results demonstrate that the proposed system can grab the sealing rings and place them on the sealing port of the fast-moving battery lid successfully. More importantly, the proposed system can improve the efficiency of the battery production line obviously. Mingyu Gao, Xiao Li, Zhiwei He, and Yuxiang Yang Copyright © 2017 Mingyu Gao et al. All rights reserved. Read Range Enhancement of a Sensing RFID Tag by Photovoltaic Panel Tue, 23 May 2017 09:59:55 +0000 http://www.hindawi.com/journals/js/2017/7264703/ An RFID tag with energy harvesting and sensing capabilities is presented in this paper. This RFID tag is based on an integrated circuit (SL900A) that incorporates a sensor front-end interface capable of measuring voltages, currents, resistances, and capacitances. The aim of this work is to improve the communication distance from the reader to the tag using energy harvesting techniques. Once the energy source and harvester are chosen according to the environment of work, the conditioning circuit for energy management has to be appropriately designed with respect to the nature of the transductor. As a proof of concept, a photovoltaic panel is used in this work to collect the energy from the environment that is managed by a DC-DC converter and stored in a capacitor acting as battery. Such energy is used to support the power system of the tag, giving autonomy to the device and allowing data logging. In particular, the developed tag monitors the ambient temperature and the power voltage. It would be possible to add external sensors without changing the architecture. An increase in the read range of more than 200% is demonstrated. This feature is especially interesting in environments where the access could be difficult. B. Molina-Farrugia, A. Rivadeneyra, J. Fernández-Salmerón, F. Martínez-Martí, J. Banqueri, and M. A. Carvajal Copyright © 2017 B. Molina-Farrugia et al. All rights reserved. Finger and Palm Dynamic Pressure Monitoring for Basketball Shooting Tue, 23 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/9352410/ This study verified general inferences on the finger and palm pressure distribution of a basketball player in the moment before that player shoots a basketball through a scientific qualitative testing method. We mounted the sensor on the hands of college basketball players and monitored the dynamic pressure of each player’s hand while the player threw a basketball. The dynamic pressure distribution of the fingers and palm of a basketball player throwing a ball can be verified. According to the experimental results, college basketball players typically use the index finger to control the direction and power of force in the moment before shooting a basketball. This study successfully used a scientific qualitative test method to monitor the dynamic pressure of the fingers and palms of basketball players and verified the general inference that a typical basketball player mainly uses the index finger to control the direction and power of force in the moment before throwing a ball. In the future, this study, measuring the dynamic pressure distribution of the fingers and palm, can be applied to simulate hand manipulation in many biomedical and robotic applications. Chiao-Fang Hung, Chung-Chiang Chen, Shin-Hung Lin, and Tien-Kan Chung Copyright © 2017 Chiao-Fang Hung et al. All rights reserved. Significant Remote Sensing Vegetation Indices: A Review of Developments and Applications Tue, 23 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/1353691/ Vegetation Indices (VIs) obtained from remote sensing based canopies are quite simple and effective algorithms for quantitative and qualitative evaluations of vegetation cover, vigor, and growth dynamics, among other applications. These indices have been widely implemented within RS applications using different airborne and satellite platforms with recent advances using Unmanned Aerial Vehicles (UAV). Up to date, there is no unified mathematical expression that defines all VIs due to the complexity of different light spectra combinations, instrumentation, platforms, and resolutions used. Therefore, customized algorithms have been developed and tested against a variety of applications according to specific mathematical expressions that combine visible light radiation, mainly green spectra region, from vegetation, and nonvisible spectra to obtain proxy quantifications of the vegetation surface. In the real-world applications, optimization VIs are usually tailored to the specific application requirements coupled with appropriate validation tools and methodologies in the ground. The present study introduces the spectral characteristics of vegetation and summarizes the development of VIs and the advantages and disadvantages from different indices developed. This paper reviews more than 100 VIs, discussing their specific applicability and representativeness according to the vegetation of interest, environment, and implementation precision. Predictably, research, and development of VIs, which are based on hyperspectral and UAV platforms, would have a wide applicability in different areas. Jinru Xue and Baofeng Su Copyright © 2017 Jinru Xue and Baofeng Su. All rights reserved. Estimation of Individual Muscular Forces of the Lower Limb during Walking Using a Wearable Sensor System Mon, 22 May 2017 06:00:30 +0000 http://www.hindawi.com/journals/js/2017/6747921/ Although various kinds of methodologies have been suggested to estimate individual muscular forces, many of them require a costly measurement system accompanied by complex preprocessing and postprocessing procedures. In this research, a simple wearable sensor system was developed, combined with the inverse dynamics-based static optimization method. The suggested method can be set up easily and can immediately convert motion information into muscular forces. The proposed sensor system consisted of the four inertial measurement units (IMUs) and manually developed ground reaction force sensor to measure the joint angles and ground reaction forces, respectively. To verify performance, the measured data was compared with that of the camera-based motion capture system and a force plate. Based on the motion data, muscular efforts were estimated in the nine muscle groups in the lower extremity using the inverse dynamics-based static optimization. The estimated muscular forces were qualitatively analyzed in the perspective of gait functions and compared with the electromyography signal. Suin Kim, Kyongkwan Ro, and Joonbum Bae Copyright © 2017 Suin Kim et al. All rights reserved. A Survey of Routing Issues and Associated Protocols in Underwater Wireless Sensor Networks Mon, 22 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/7539751/ Underwater wireless sensor networks are a newly emerging wireless technology in which small size sensors with limited energy and limited memory and bandwidth are deployed in deep sea water and various monitoring operations like tactical surveillance, environmental monitoring, and data collection are performed through these tiny sensors. Underwater wireless sensor networks are used for the exploration of underwater resources, oceanographic data collection, flood or disaster prevention, tactical surveillance systems, and unmanned underwater vehicles. Sensor nodes consist of a small memory, a central processing unit, and an antenna. Underwater networks are much different from terrestrial sensor networks as radio waves cannot be used in underwater wireless sensor networks. Acoustic channels are used for communication in deep sea water. Acoustic signals have many limitations, such as limited bandwidth, higher end-to-end delay, network path loss, higher propagation delay, and dynamic topology. Usually, these limitations result in higher energy consumption with a smaller number of packets delivered. The main aim nowadays is to operate sensor nodes having a smaller battery for a longer time in the network. This survey has discussed the state-of-the-art localization based and localization-free routing protocols. Routing associated issues in the area of underwater wireless sensor networks have also been discussed. Muhammad Khalid, Zahid Ullah, Naveed Ahmad, Muhammad Arshad, Bilal Jan, Yue Cao, and Awais Adnan Copyright © 2017 Muhammad Khalid et al. All rights reserved. A Study for Optimum Survey Method of Underwater Structure Using the Dual Sonar Sensor Mon, 22 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/9206898/ We have developed dual sonar equipment and an improved operating method for improving resolution in order to solve the problems of limitations of the optical equipment and the application method of SSS (side scan sonar) in the investigation of damage of underwater structures. We analyzed the influence factors of the resolution of sonar data through the comparison of resolution and data quality in indoor test. Also we confirmed the problems about the overlapping area of the dual sonar. Depth and distance were analyzed as major influencing factors for survey angle. Specimens were scanned while adjusting distance and towfish angle according to depth change in order to verify applicability of the developed dual sonar in the field experiment. Optimal resolution was found to be 3 cm in specimen spacing, and 20 sample data items were extracted. We developed the regression model based on the multiple regression analysis and developed the RealDualSONAR-DAQ tool, the dual sonar optimum operating method program based on proposed correlation equations. We can use the developed tools to get the value of the major influencing factors for dual sonar operation and obtain high quality sonar data to analyze damage of underwater structures. Youngseok Kim, Heungsu Lee, Chul Park, and Sangsik Choi Copyright © 2017 Youngseok Kim et al. All rights reserved. Modular Middleware for Gestural Data and Devices Management Thu, 18 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/9196070/ In the last few years, the use of gestural data has become a key enabler for human-computer interaction (HCI) applications. The growing diffusion of low-cost acquisition devices has thus led to the development of a class of middleware aimed at ensuring a fast and easy integration of such devices within the actual HCI applications. The purpose of this paper is to present a modular middleware for gestural data and devices management. First, we describe a brief review of the state of the art of similar middleware. Then, we discuss the proposed architecture and the motivation behind its design choices. Finally, we present a use case aimed at demonstrating the potential uses as well as the limitations of our middleware. Fabrizio Milazzo, Vito Gentile, Giuseppe Vitello, Antonio Gentile, and Salvatore Sorce Copyright © 2017 Fabrizio Milazzo et al. All rights reserved. An Innovative Serious Game for the Detection and Rehabilitation of Oral-Facial Malfunction in Children: A Pilot Study Wed, 17 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/8745437/ We present SONRIE, a serious game based on virtual reality and comprising four games which act as tests where children must perform gestures in order to progress through several screens (raising eyebrows, kissing, blowing, and smiling). The aims of this pilot study were to evaluate the overall acceptance of the game and the capacity for detecting anomalies in motor execution and, lastly, to establish motor control benchmarks in orofacial muscles. For this purpose, tests were performed in school settings with 96 typically developing children aged between five and seven years. Regarding the different games, in the kissing game, children were able to execute the correct movement at six years of age and a precise movement at the age of seven years. Blowing actions required more maturity, starting from the age of five and achievable by the age of six years. The smiling game was performed correctly among all ages evaluated. The percentage of children who mastered this gesture with both precision and speed was progressively greater reaching more than 75% of values above 100 for children aged seven years. SONRIE was accepted enthusiastically among the population under study. In the future, SONRIE could be used as a tool for detecting difficulties regarding self-control and for influencing performance and the ability to produce fine-tuned facial movements. Nuria Máximo-Bocanegra and María-Luisa Martín-Ruiz Copyright © 2017 Nuria Máximo-Bocanegra and María-Luisa Martín-Ruiz. All rights reserved. Enhanced Measurement of Paper Basis Weight Using Phase Shift in Terahertz Time-Domain Spectroscopy Tue, 16 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/3520967/ THz time-domain spectroscopy has evolved as a noncontact, safe, and efficient technique for paper characterization. Our previous work adopted peak amplitude and delay time as features to determine paper basis weight using terahertz time-domain spectroscopy. However, peak amplitude and delay time tend to suffer from noises, resulting in degradation of accuracy and robustness. This paper proposes a noise-robust phase-shift based method to enhance measurements of paper basis weight. Based on Fresnel Formulae, the physical relationship between phase shift and paper basis weight is formulated theoretically neglecting multiple reflections in the case of normal incidence. The established formulation indicates that phase shift correlates linearly with paper basis weight intrinsically. Subsequently, paper sheets were stacked to fabricate the samples with different basis weights, and experimental results verified the developed mathematical formulation. Moreover, a comparison was made between phase shift, peak amplitude, and delay time with respect to linearity, accuracy, and noise robustness. The results show that phase shift is superior to the others. Mengbao Fan, Binghua Cao, and Guiyun Tian Copyright © 2017 Mengbao Fan et al. All rights reserved. Comparison between a Machine-Learning-Based Method and a Water-Index-Based Method for Shoreline Mapping Using a High-Resolution Satellite Image Acquired in Hwado Island, South Korea Sun, 14 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/8245204/ Shoreline-mapping tasks using remotely sensed image sources were carried out using the machine learning techniques or using water indices derived from image sources. This research compared two different methods for mapping accurate shorelines using the high-resolution satellite image acquired in Hwado Island, South Korea. The first shoreline was generated using a water-index-based method proposed in previous research, and the second shoreline was generated using a machine-learning-based method proposed in this research. The statistical results showed that both shorelines had high accuracies in the well-identified coastal zones while the second shoreline had better accuracy than the first shoreline in the coastal zones with irregular shapes and the shaded areas not identified by the water-index-based method. Both shorelines, however, had low accuracies in the coastal zones with the shaded areas not identified by both methods. Yun-Jae Choung and Myung-Hee Jo Copyright © 2017 Yun-Jae Choung and Myung-Hee Jo. All rights reserved. Fabrication and Characterization of High-Sensitivity Underwater Acoustic Multimedia Communication Devices with Thick Composite PZT Films Sun, 14 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/7326919/ This paper presents a high-sensitivity hydrophone fabricated with a Microelectromechanical Systems (MEMS) process using epitaxial thin films grown on silicon wafers. The evaluated resonant frequency was calculated through finite-element analysis (FEA). The hydrophone was designed, fabricated, and characterized by different measurements performed in a water tank, by using a pulsed sound technique with a sensitivity of −190 dB ± 2 dB for frequencies in the range 50–500 Hz. These results indicate the high-performance miniaturized acoustic devices, which can impact a variety of technological applications. Jeng-Cheng Liu, Yuang-Tung Cheng, Sheng-Yun Ho, Hsien-Sen Hung, and Shun-Hsyung Chang Copyright © 2017 Jeng-Cheng Liu et al. All rights reserved. The Differential Method for Force Measurement Based on Electrostatic Force Thu, 11 May 2017 07:10:16 +0000 http://www.hindawi.com/journals/js/2017/1857920/ The small force measurement is very important with development of the technology. The electrostatic force is adopted, in which a pair of coaxial cylindrical capacitors generate the electrostatic force when a voltage is applied across the inner and outer electrodes. However, the measured force will be covered by noise (creep, ground vibration, and air flow) and could not be measured accurately. In this paper, we introduce the differential method to reduce the effect of noise. Two identical parallelogram mechanisms (PM) serve as the mechanical spring. One of the PM serves as the reference and another serves as the force sensor. The common signal will be offset, and the difference signal will serve as output. In this way, the effect of the creep will be reduced. The measurement system of the electrostatic force was characterized by applying mechanical forces of known magnitude via loading weights of calibrated masses. The uncertainty from voltage, laser interferometer, and capacitance gradient was estimated. For the measured force, the relative uncertainty is less than 4% . Peiyuan Sun, Meirong Zhao, Jile Jiang, Yelong Zheng, Yaqian Han, and Le Song Copyright © 2017 Peiyuan Sun et al. All rights reserved. A Fast SINS Initial Alignment Method Based on RTS Forward and Backward Resolution Wed, 10 May 2017 08:43:01 +0000 http://www.hindawi.com/journals/js/2017/7161858/ For the strapdown inertial navigation system (SINS), the procedure of initial alignment is a necessity before the navigation can commence. On the quasi-stationary base, the self-alignment can be fulfilled with the high quality inertial sensors, and the fine alignment is usually executed to improve the alignment performance. Generally, fast estimating of heading misalignment is still a challenge due to the existence of gyro errors. An innovative data processing strategy called forward and backward resolution is proposed for INS initial alignment. The Rauch-Tung-Striebel (RTS) smoothing is applied to obtain the smoothed attitude estimates with the filter information provided by the forward data processing. The obtained attitudes are then treated as aiding measurements to implement the forward resolution with the repeated data set, the converged sensor biases are used as constraints, and the iterative processing is conducted to obtain the updated attitudes. Simulation studies have been conducted to validate the proposed algorithm. The results have shown that the alignment accuracy and convergence rate have been improved with the added RTS aided forward and backward resolution; more stable heading estimates can be obtained by calibrating with estimated gyro bias. A real test with a high quality inertial sensor was also carried out to validate the effectiveness of the proposed algorithm. Houzeng Han, Jian Wang, and Mingyi Du Copyright © 2017 Houzeng Han et al. All rights reserved. A Study on the Effects of Heavy Backpack and Development of a Preventative Prototype Tue, 09 May 2017 09:19:05 +0000 http://www.hindawi.com/journals/js/2017/9419373/ Posture is a bigger concern than most think. With growing workload for school children, the weight of this issue is increasing every day. It can not only affect a child in the present but also have long-term effects on their body and render their spine vulnerable to injuries. Therefore the solutions can be either to decrease their workload, that is, decrease the weight of their backpack, or to constantly guide them to a better posture for the betterment of their spinal shape and thus their health. The aim of this paper is to find which part of the spine is affected the most by the heavy load and develop a prototype: a monitoring system that is effective in guiding a child to constantly keep their posture in check and is also simple enough to be worn every day. F. M. A. Hossain and Masuda A. Tonima Copyright © 2017 F. M. A. Hossain and Masuda A. Tonima. All rights reserved. QoS Based Cooperative Communications and Security Mechanisms for Ad Hoc Sensor Networks Tue, 09 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/9768421/ Shafiullah Khan, Jaime Lloret, Houbing Song, and Qinghe Du Copyright © 2017 Shafiullah Khan et al. All rights reserved. Ensemble Learning for Short-Term Traffic Prediction Based on Gradient Boosting Machine Thu, 04 May 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/7074143/ Short-term traffic prediction is vital for intelligent traffic systems and influenced by neighboring traffic condition. Gradient boosting decision trees (GBDT), an ensemble learning method, is proposed to make short-term traffic prediction based on the traffic volume data collected by loop detectors on the freeway. Each new simple decision tree is sequentially added and trained with the error of the previous whole ensemble model at each iteration. The relative importance of variables can be quantified in the training process of GBDT, indicating the interaction between input variables and response. The influence of neighboring traffic condition on prediction performance is identified through combining the traffic volume data collected by different upstream and downstream detectors as the input, which can also improve prediction performance. The relative importance of input variables for 15 GBDT models is different, and the impact of upstream traffic condition is not balanced with that of downstream. The prediction accuracy of GBDT is generally higher than SVM and BPNN for different steps ahead, and the accuracy of multi-step-ahead models is lower than 1-step-ahead models. For 1-step-ahead models, the prediction errors of GBDT are smaller than SVM and BPNN for both peak and nonpeak hours. Senyan Yang, Jianping Wu, Yiman Du, Yingqi He, and Xu Chen Copyright © 2017 Senyan Yang et al. All rights reserved. Automated Recognition of a Wall between Windows from a Single Image Wed, 03 May 2017 07:30:05 +0000 http://www.hindawi.com/journals/js/2017/7051931/ To avoid the time-consuming, costly, and expert-dependent traditional assessment of earthquake damaged structures, image-based automatic methods have been developed recently. Since automated recognition of structure elements is the basis by which these methods achieve automatic detection, this study proposes a method to recognize the wall between windows from a single image automatically. It begins from detection of line segments with further selection and linking to obtain longer line segments. The color features of the two sides of each long line segment are employed to pick out line segments as candidate window edges and then label them. Finally, the images are segmented into several subimages, window regions are located, and then the wall between the windows is located. Real images are tested to verify the method. The results indicate that walls between windows can be successfully recognized. Yaowen Zhang, Linsheng Huo, and Hongnan Li Copyright © 2017 Yaowen Zhang et al. All rights reserved. Robust Relay in Narrow-Band Communications for Ubiquitous IoT Access Thu, 27 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/9270907/ We propose a robust wireless relay scheme in narrow-band communications for IoT access, which matches the typical features of IoT often carrying relatively low data rate with limited bandwidth. This framework is towards offering robustness in QoS guarantees with emphases on security and/or reliability, and we use the security-assured network as the typical scenario. In particular, we consider a dual-hop relay network including a transmitter, a receiver, an amplify-and-forward (AF) untrusted relay, and a jamming node. The jamming node is treated as a helper. Specifically, the jammer broadcasts artificial noise (AN), which in fact pollutes both the untrusted relay and the destination node’s signals. However, we show that such AN can be effectively mitigated after the destination node obtains the forwarded signal from the relay, while the untrusted relay node cannot do so. The core idea for robustness assurance is to exploit higher signal dimensions at the receiver over the untrusted relay node. Simulations and analyses are also conducted to demonstrate that our proposed scheme can make the performance at the untrusted relay an interference-limited manner while completely removing the interferences at the receiver, therefore corroborating our claim in robustness in terms of security and reliability. Qinghe Du, Nan Lu, Li Sun, Xuelin Zhang, and Bo Sun Copyright © 2017 Qinghe Du et al. All rights reserved. A Distributed Tactile Sensor for Intuitive Human-Robot Interfacing Thu, 27 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/1357061/ Safety of human-robot physical interaction is enabled not only by suitable robot control strategies but also by suitable sensing technologies. For example, if distributed tactile sensors were available on the robot, they could be used not only to detect unintentional collisions, but also as human-machine interface by enabling a new mode of social interaction with the machine. Starting from their previous works, the authors developed a conformable distributed tactile sensor that can be easily conformed to the different parts of the robot body. Its ability to estimate contact force components and to provide a tactile map with an accurate spatial resolution enables the robot to handle both unintentional collisions in safe human-robot collaboration tasks and intentional touches where the sensor is used as human-machine interface. In this paper, the authors present the characterization of the proposed tactile sensor and they show how it can be also exploited to recognize haptic tactile gestures, by tailoring recognition algorithms, well known in the image processing field, to the case of tactile images. In particular, a set of haptic gestures has been defined to test three recognition algorithms on a group of users. The paper demonstrates how the same sensor originally designed to manage unintentional collisions can be successfully used also as human-machine interface. Andrea Cirillo, Pasquale Cirillo, Giuseppe De Maria, Ciro Natale, and Salvatore Pirozzi Copyright © 2017 Andrea Cirillo et al. All rights reserved. A State-of-the-Art Review on Mapping and Localization of Mobile Robots Using Omnidirectional Vision Sensors Mon, 24 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/3497650/ Nowadays, the field of mobile robotics is experiencing a quick evolution, and a variety of autonomous vehicles is available to solve different tasks. The advances in computer vision have led to a substantial increase in the use of cameras as the main sensors in mobile robots. They can be used as the only source of information or in combination with other sensors such as odometry or laser. Among vision systems, omnidirectional sensors stand out due to the richness of the information they provide the robot with, and an increasing number of works about them have been published over the last few years, leading to a wide variety of frameworks. In this review, some of the most important works are analysed. One of the key problems the scientific community is addressing currently is the improvement of the autonomy of mobile robots. To this end, building robust models of the environment and solving the localization and navigation problems are three important abilities that any mobile robot must have. Taking it into account, the review concentrates on these problems; how researchers have addressed them by means of omnidirectional vision; the main frameworks they have proposed; and how they have evolved in recent years. L. Payá, A. Gil, and O. Reinoso Copyright © 2017 L. Payá et al. All rights reserved. Fabricating 90 nm Resolution Structures in Sol-Gel Silica Optical Waveguides for Biosensor Applications Sun, 23 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/4198485/ Bragg grating structure in a sol-gel silica waveguide is fabricated on the basis of nanoimprint lithography for biophotonic applications. The process realizes nonstandardized lithography in sol-gel silica at a high resolution for a relatively large area in the range of several micrometers with a resolution in the order of several nanometers. Here we demonstrate structures of 250 and 90 nm resolutions in a sol-gel silica optical waveguide for a large area that is not optimized to date. Bragg grating of a 250 nm periodic structure is realized for a 1 mm long area. Yasufumi Enami Copyright © 2017 Yasufumi Enami. All rights reserved. Indoor Dead Reckoning Localization Using Ultrasonic Anemometer with IMU Wed, 19 Apr 2017 06:43:33 +0000 http://www.hindawi.com/journals/js/2017/3542354/ Dead reckoning is an important aspect of estimating the instantaneous position of a mobile robot. An inertial measurement unit (IMU) is generally used for dead reckoning because it measures triaxis acceleration and triaxis angular velocities in order to estimate the position of the mobile robot. Positioning with inertial data is reasonable for a short period of time. However, the velocity, position, and attitude errors increase over time. Much research has been conducted in ways to reduce these errors. To position a mobile robot, an absolute positioning method can be combined with dead reckoning. The performance of a combined positioning method can be improved based on improvement in dead reckoning. In this paper, an ultrasonic anemometer is used to improve the performance of dead reckoning when indoors. A new approach to the equation of an ultrasonic anemometer is proposed. The ultrasonic anemometer prevents divergence of the mobile robot’s velocity. To position a mobile robot indoors, the ultrasonic anemometer measures the relative movement of air while the robot moves through static air. Velocity data from the ultrasonic anemometer and the acceleration and angular velocity data from the IMU are combined via Kalman filter. Finally we show that the proposed method has the performance with a positioning method using encoders on a good floor condition. Woojin Seo and Kwang-Ryul Baek Copyright © 2017 Woojin Seo and Kwang-Ryul Baek. All rights reserved. Urban Expansion Assessment in Huaihe River Basin, China, from 1998 to 2013 Using Remote Sensing Data Thu, 13 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/9281201/ Urbanization reflects the overall behavior of human society; thus, characterization of its associated spatial and temporal trends has been extensively researched. This study examines the process of urban expansion in the Huaihe River Basin (HRB) which is a key transition region within China’s urban system. In order to grasp the urban expansion process in different temporal sequences objectively, rapidly, and accurately, we used remote sensing data to assess the urban expansion in time and space. Urban expansion rules were defined for the urban area, urbanization intensification, extended dynamic degree, and spatial pattern. The research findings show that the urban area expansion speed was at medium level throughout the entire HRB and within each province. Presently, the formation of a whole urban agglomeration or urban system is not complete in the HRB; urban expansion in the HRB displayed space-time disequilibrium tendencies during 1998–2013. Yong Fan, Xi Zhu, Zongyi He, Shengdi Zhang, Junbo Gao, Feiyan Chen, Xiaolin Peng, and Junli Li Copyright © 2017 Yong Fan et al. All rights reserved. Data Transmission and Access Protection of Community Medical Internet of Things Thu, 13 Apr 2017 00:00:00 +0000 http://www.hindawi.com/journals/js/2017/7862842/ On the basis of Internet of Things (IoT) technologies, Community Medical Internet of Things (CMIoT) is a new medical information system and generates massive multiple types of medical data which contain all kinds of user identity data, various types of medical data, and other sensitive information. To effectively protect users’ privacy, we propose a secure privacy data protection scheme including transmission protection and access control. For the uplink transmission data protection, bidirectional identity authentication and fragmented multipath data transmission are used, and for the downlink data protection, fine grained access control and dynamic authorization are used. Through theoretical analysis and experiment evaluation, it is proved that the community medical data can be effectively protected in the transmission and access process without high performance loss. Xunbao Wang, Fulong Chen, Heping Ye, Jie Yang, Junru Zhu, Ziyang Zhang, and Yakun Huang Copyright © 2017 Xunbao Wang et al. All rights reserved. Review and Comparison of High-Dynamic Range Three-Dimensional Shape Measurement Techniques Wed, 12 Apr 2017 09:26:05 +0000 http://www.hindawi.com/journals/js/2017/9576850/ In the last decade, a significant number of techniques for three-dimensional (3D) shape measurement have been proposed. There are a large number of measurement demands for metallic workpieces with shiny surfaces in industrial applications; however, such shiny surfaces cannot be directly measured using the conventional structured light method. Therefore, various techniques have been investigated to solve this problem over the last few years. Some reviews summarize the different 3D imaging techniques; however, no comprehensive review exists that provides an insight into high-dynamic range (HDR) 3D shape measurement techniques used for shiny surfaces. We present a survey of recent HDR techniques for the digitization of shiny surfaces and classify and discuss the advantages and drawbacks of different techniques with respect to each other. Hui Lin, Jian Gao, Guanjin Zhang, Xin Chen, Yunbo He, and Yan Liu Copyright © 2017 Hui Lin et al. All rights reserved. Mechanical Characterization of PDMS Films for the Optimization of Polymer Based Flexible Capacitive Pressure Microsensors Wed, 12 Apr 2017 08:02:32 +0000 http://www.hindawi.com/journals/js/2017/8235729/ This paper reports on the optimization of flexible PDMS-based normal pressure capacitive microsensors dedicated to wearable applications. The operating principle and the fabrication process of such microsensors are presented. Then, the deformations under local pressure of PDMS thin films of thicknesses ranging from 100 μm to 10 mm are studied by means of numerical simulations in order to foresee the sensitivity of the considered microsensors. The study points out that, for a given PDMS type, the sensor form ratio plays a major role in its sensitivity. Indeed, for a given PDMS film, the expected capacitance change under a 10 N load applied on a 1.7 mm radius electrode varies from a few percent to almost 40% according to the initial PDMS film thickness. These observations are validated by experimental characterizations carried out on PDMS film samples of various thicknesses (10 μm to 10 mm) and on actual microsensors. Further computations enable generalized sensor design rules to be highlighted. Considering practical limitations in the fabrication and in the implementation of the actual microsensors, design rules based on computed form ratio optimization lead to the elaboration of flexible pressure microsensors exhibiting a sensitivity which reaches up to . T.-H.-N. Dinh, E. Martincic, E. Dufour-Gergam, and P.-Y. Joubert Copyright © 2017 T.-H.-N. Dinh et al. All rights reserved. Estimating Snow Depth and Snow Water Equivalence Using Repeat-Pass Interferometric SAR in the Northern Piedmont Region of the Tianshan Mountains Wed, 12 Apr 2017 07:44:56 +0000 http://www.hindawi.com/journals/js/2017/8739598/ Snow depth and Snow Water Equivalence (SWE) are important parameters for hydrological applications. In this application, a theoretical method of snow depth estimation with repeat-pass InSAR measurements was proposed, and a preliminary sensitivity analysis of snow phase changes versus the incident angle and snow density was developed. Moreover, the snow density and incident angle parameters were analyzed and calibrated, and the local incident angle was used as a substitute for the satellite incident angle to improve the snow depth estimation. From the results, the coherence images showed that a high degree of coherence can be found for dry snow, and, apart from the effect of snow, land use/cover change due to a long temporal baseline and geometric distortion due to the rugged terrain were the main constraints for InSAR technique to measure snow depth and SWE in this area. The result of snow depth estimation between July 2008 and February 2009 demonstrated that the average snow depth was about 20 cm, which was consistent with the field survey results. The areal coverage of snow distribution estimated from the snow depth and SWE results was consistent with snow cover obtained from HJ-1A CCD optical data at the same time. Hui Li, Zuo Wang, Guangjun He, and Wang Man Copyright © 2017 Hui Li et al. All rights reserved. Geometry Based Approach to Obstacle Avoidance of Triomnidirectional Wheeled Mobile Robotic Platform Tue, 11 Apr 2017 07:14:30 +0000 http://www.hindawi.com/journals/js/2017/2849537/ Mobile robots undergo a collision-free autonomous motion by using the information obtained from a suitable combination of multiple sensors of same or different families. These sensors are often configured around the chassis of the robotic platform. However, little to no information is available as to how these sensors are configured on mobile robotic platforms and how many of these sensors to place on such platforms. Instead, an empirical approach is adopted. That is, the number of sensors of the same family or any type as well as combination of sensors for detecting obstacles is determined by experiment or information obtained from external sensors. This approach is often seen to be iterative and time consuming. In this paper, an approach for determining the minimum number of sensors and their spacing on the robotic platform is proposed so that mobile robots undergo collision-free motion. The effectiveness of the developed approach is experimentally tested by examining the obstacle avoidance capability of the triomnidirectional wheeled robotic platform based on a motion triggering signal obtained from a skirt of ultrasonic sensors only. It was observed that the newly developed approach allows this robotic platform to avoid obstacles effectively. Tesfaye Wakessa Gussu and Chyi-Yeu Lin Copyright © 2017 Tesfaye Wakessa Gussu and Chyi-Yeu Lin. All rights reserved.