Mathematical Problems in Engineering http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Parameter Sensitivity Analysis on Deformation of Composite Soil-Nailed Wall Using Artificial Neural Networks and Orthogonal Experiment Wed, 23 Apr 2014 14:11:18 +0000 http://www.hindawi.com/journals/mpe/2014/502362/ Based on the back-propagation algorithm of artificial neural networks (ANNs), this paper establishes an intelligent model, which is used to predict the maximum lateral displacement of composite soil-nailed wall. Some parameters, such as soil cohesive strength, soil friction angle, prestress of anchor cable, soil-nail spacing, soil-nail diameter, soil-nail length, and other factors, are considered in the model. Combined with the in situ test data of composite soil-nail wall reinforcement engineering, the network is trained and the errors are analyzed. Thus it is demonstrated that the method is applicable and feasible in predicting lateral displacement of excavation retained by composite soil-nailed wall. Extended calculations are conducted by using the well-trained intelligent forecast model. Through application of orthogonal table test theory, 25 sets of tests are designed to analyze the sensitivity of factors affecting the maximum lateral displacement of composite soil-nailing wall. The results show that the sensitivity of factors affecting the maximum lateral displacement of composite soil nailing wall, in a descending order, are prestress of anchor cable, soil friction angle, soil cohesion strength, soil-nail spacing, soil-nail length, and soil-nail diameter. The results can provide important reference for the same reinforcement engineering. Jianbin Hao and Banqiao Wang Copyright © 2014 Jianbin Hao and Banqiao Wang. All rights reserved. A Highly Accurate Regular Domain Collocation Method for Solving Potential Problems in the Irregular Doubly Connected Domains Wed, 23 Apr 2014 13:34:24 +0000 http://www.hindawi.com/journals/mpe/2014/397327/ Embedding the irregular doubly connected domain into an annular regular region, the unknown functions can be approximated by the barycentric Lagrange interpolation in the regular region. A highly accurate regular domain collocation method is proposed for solving potential problems on the irregular doubly connected domain in polar coordinate system. The formulations of regular domain collocation method are constructed by using barycentric Lagrange interpolation collocation method on the regular domain in polar coordinate system. The boundary conditions are discretized by barycentric Lagrange interpolation within the regular domain. An additional method is used to impose the boundary conditions. The least square method can be used to solve the overconstrained equations. The function values of points in the irregular doubly connected domain can be calculated by barycentric Lagrange interpolation within the regular domain. Some numerical examples demonstrate the effectiveness and accuracy of the presented method. Zhao-Qing Wang, Shuchen Li, Yang Ping, Jian Jiang, and Teng-Fei Ma Copyright © 2014 Zhao-Qing Wang et al. All rights reserved. A Hybrid GRASP+VND Heuristic for the Two-Echelon Vehicle Routing Problem Arising in City Logistics Wed, 23 Apr 2014 11:54:46 +0000 http://www.hindawi.com/journals/mpe/2014/517467/ The two-echelon vehicle routing problem (2E-VRP) is a variant of the classical vehicle routing problem (VRP) arising in two-level transportation systems such as those encountered in the context of city logistics. In the 2E-VRP, freight from a depot is compulsorily delivered through intermediate depots, named satellites. The first echelons are routes that distribute freight from depot to satellites, and the second are those from satellites to customers. This problem is solved by a hybrid heuristic which is composed of a greedy randomized adaptive search procedure (GRASP) with a route-first cluster-second procedure embedded and a variable neighborhood descent (VND), called GRASP+VND hereafter. Firstly, an extended split algorithm in the GRASP continuously splits randomly generated permutations of all customers and assigns customers to satellites reasonably until a feasible assignment appears, and a complete 2E-VRP feasible solution is obtained by solving the first echelon problem subsequently and, secondly, a VND phase attempts to improve this solution until no more improvements can be found. The process above is iterated until the maximum number of iterations is reached. Computational tests conducted on three sets of benchmark instances from the literature show that our algorithm is both effective and efficient and outperforms the best existing heuristics for the 2E-VRP. Zheng-yang Zeng, Wei-sheng Xu, Zhi-yu Xu, and Wei-hui Shao Copyright © 2014 Zheng-yang Zeng et al. All rights reserved. Approximate Periodic Solutions for Oscillatory Phenomena Modelled by Nonlinear Differential Equations Wed, 23 Apr 2014 11:46:33 +0000 http://www.hindawi.com/journals/mpe/2014/513473/ We apply the Fourier-least squares method (FLSM) which allows us to find approximate periodic solutions for a very general class of nonlinear differential equations modelling oscillatory phenomena. We illustrate the accuracy of the method by using several significant examples of nonlinear problems including the cubic Duffing oscillator, the Van der Pol oscillator, and the Jerk equations. The results are compared to those obtained by other methods. Constantin Bota, Bogdan Căruntu, and Olivia Bundău Copyright © 2014 Constantin Bota et al. All rights reserved. Coordination of Supply Chain with a Dominant Retailer under Demand Disruptions Wed, 23 Apr 2014 11:43:17 +0000 http://www.hindawi.com/journals/mpe/2014/854681/ We develop a coordination model of a one-manufacturer multi-retailers supply chain with a dominant retailer. We consider the impact of a dominant retailer on the market retail price and his sales promotion opportunity and examine how the manufacturer can coordinate such a supply chain by revenue-sharing contract after demand disruptions. We address the following important research questions in this paper. (i) How do we design an appropriate revenue-sharing contract to coordinate the supply chain with a dominant retailer without demand disruptions? (ii) When demand is disrupted with variations in market scale and price sensitive coefficient, can the original contract still be valid? (iii) How do the demand disruptions affect the coordination mechanism under different disruption scenarios and how should the new contract change? Finally, we generate important insights by both analytical and numerical examples. Jian Li, Xiaofang Liu, Jun Wu, and Fengmei Yang Copyright © 2014 Jian Li et al. All rights reserved. Average and Small Signal Modeling of Negative-Output KY Boost Converter in CCM Operation Wed, 23 Apr 2014 10:00:04 +0000 http://www.hindawi.com/journals/mpe/2014/810956/ Negative-output KY Boost converter, which can obtain the negative output voltage and could be driven easily, is a good topology to overcome traditional Boost and Buck-Boost converters and it is believed that this converter will be widely used in engineering applications in the future. In this study, by using the averaging method and geometrical technique, the average and small signal model of the negative-output KY Boost converter are established. The DC equilibrium point and transfer functions of the system are derived and analyzed. Finally, the effectiveness of the established model and the correctness of the theoretical analysis are confirmed by the circuit experiment. Faqiang Wang, Jing Li, and Xikui Ma Copyright © 2014 Faqiang Wang et al. All rights reserved. Improvement of Energy Density in Single Stator Interior Permanent Magnet Using Double Stator Topology Wed, 23 Apr 2014 09:29:24 +0000 http://www.hindawi.com/journals/mpe/2014/787382/ The paper presents the energy density improvement using magnetic circuit analysis of the interior permanent magnet motor. The leakage flux from the conventional structure is improved with modified magnetic circuit to improve the energy and thereby the torque value. This is approached with a double stator structure design. The proposed structure is investigated with two design variations, namely, the double stator with thin pole shoe and the double stator with thick pole shoe motors. Variations in the mechanical parameters of the all the developed models are analyzed through the finite element analysis tool. In all investigations the magnetic source is fixed in both the permanent magnet volume and coil magnetomotive force, respectively, as 400 mm3 per each pole and 480 Ampere turns per pole. From the analysis the best fit magnetic structure based on the torque characteristics is derived and is fabricated for the same volume as that of the conventional structure for performance evaluations. It is found out that there is improvement on the motor constant square density for the proposed improved magnetic circuit through the best fit double stator with thick pole shoe by about 83.66% greater than that of the conventional structure. Raja Nor Firdaus, Norhisam Misron, Chockalingam Aravind Vaithilingam, Masami Nirei, and Hiroyuki Wakiwaka Copyright © 2014 Raja Nor Firdaus et al. All rights reserved. Selecting Large Portfolios of Social Projects in Public Organizations Wed, 23 Apr 2014 09:10:44 +0000 http://www.hindawi.com/journals/mpe/2014/654293/ We address the portfolio selection of social projects in public organizations considering interdependencies (synergies) affecting project funds requirements and tasks. A mixed integer linear programming model is proposed incorporating the most relevant aspects of the problem found in the literature. The model supports both complete (all or nothing) and partial (a certain amount from a given interval of funding) resource allocation policies. Numerical results for large-scale problem instances are presented. Igor Litvinchev, Fernando Lopez-Irarragorri, Nancy Maribel Arratia-Martínez, and José Antonio Marmolejo Copyright © 2014 Igor Litvinchev et al. All rights reserved. Nonlinear Modeling and Analysis of Pressure Wave inside CEUP Fuel Pipeline Wed, 23 Apr 2014 09:04:02 +0000 http://www.hindawi.com/journals/mpe/2014/521859/ Operating conditions dependent large pressure variations are one of the working characteristics of combination electronic unit pump (CEUP) fuel injection system for diesel engines. We propose a precise and accurate nonlinear numerical model of pressure inside HP fuel pipeline of CEUP using wave equation (WE) including both viscous and frequency dependent frictions. We have proved that developed hyperbolic approximation gives more realistic description of pressure wave as compared to classical viscous damped wave equation. Frictional effects of various frequencies on pressure wave have been averaged out across valid frequencies to represent the combined effect of all frequencies on pressure wave. Dynamic variations of key fuel properties including density, acoustic wave speed, and bulk modulus with varying pressures have also been incorporated. Based on developed model we present analysis on effect of fuel pipeline length on pressure wave propagation and variation of key fuel properties with both conventional diesel and alternate fuel rapeseed methyl ester (RME) for CEUP pipeline. Qaisar Hayat, Liyun Fan, Enzhe Song, Xiuzhen Ma, Bingqi Tian, and Naeim Farouk Copyright © 2014 Qaisar Hayat et al. All rights reserved. Application of D-S Evidence Fusion Method in the Fault Detection of Temperature Sensor Wed, 23 Apr 2014 08:20:05 +0000 http://www.hindawi.com/journals/mpe/2014/395057/ Due to the complexity and dangerousness of drying process, the fault detection of temperature sensor is very difficult and dangerous in actual working practice and the detection effectiveness is not satisfying. For this problem, in this paper, based on the idea of information fusion and the requirements of D-S evidence method, a D-S evidence fusion structure with two layers was introduced to detect the temperature sensor fault in drying process. The first layer was data layer to establish the basic belief assignment function of evidence which could be realized by BP Neural Network. The second layer was decision layer to detect and locate the sensor fault which could be realized by D-S evidence fusion method. According to the numerical simulation results, the working conditions of sensors could be described effectively and accurately by this method, so that it could be used to detect and locate the sensor fault. Zheng Dou, Xiaochun Xu, Yun Lin, and Ruolin Zhou Copyright © 2014 Zheng Dou et al. All rights reserved. Method of Multiobject Detecting and Tracking Based on DM643 Wed, 23 Apr 2014 08:09:44 +0000 http://www.hindawi.com/journals/mpe/2014/365480/ The technology of moving objects detection has become an important research subject for its extensive application prospect. In this paper, it is presented that interframe difference algorithm and background difference algorithm are combined to update the background. The algorithm can deal with the flaw of background difference algorithm. The mathematical morphology method is employed to denoise the image, which may be helpful to improve the accuracy of the detection. The Pyramid algorithm is used to compress each frame data of video sequence. Then, the detecting and tracking of moving objects are tested on the hardware platform (DM643) and the software frame (RF5). The running speed is about 3 times faster than before. The result shows that the accuracy demanded by the detection is met. This method can provide a useful reference for similar application. Yitao Liang, Deshan Zhang, Feng Wang, Yonggang Li, and Meng Zhang Copyright © 2014 Yitao Liang et al. All rights reserved. Research on Energy-Saving Design of Overhead Travelling Crane Camber Based on Probability Load Distribution Wed, 23 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/484635/ Crane is a mechanical device, used widely to move materials in modern production. It is reported that the energy consumptions of China are at least 5–8 times of other developing countries. Thus, energy consumption becomes an unavoidable topic. There are several reasons influencing the energy loss, and the camber of the girder is the one not to be neglected. In this paper, the problem of the deflections induced by the moving payload in the girder of overhead travelling crane is examined. The evaluation of a camber giving a counterdeflection of the girder is proposed in order to get minimum energy consumptions for trolley to move along a nonstraight support. To this aim, probabilistic payload distributions are considered instead of fixed or rated loads involved in other researches. Taking 50/10 t bridge crane as a research object, the probability loads are determined by analysis of load distribution density functions. According to load distribution, camber design under different probability loads is discussed in detail as well as energy consumptions distribution. The research results provide the design reference of reasonable camber to obtain the least energy consumption for climbing corresponding to different ; thus energy-saving design can be achieved. Tong Yifei, Tang Zhaohui, Mei Song, Shen Guomin, and Gu Feng Copyright © 2014 Tong Yifei et al. All rights reserved. Fluid-Thermal-Structural Coupled Analysis of a Radial Inflow Micro Gas Turbine Using Computational Fluid Dynamics and Computational Solid Mechanics Wed, 23 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/640560/ A three-dimensional fluid-thermal-structural coupled analysis for a radial inflow micro gas turbine is conducted. First, a fluid-thermal coupled analysis of the flow and temperature fields of the nozzle passage and the blade passage is performed by using computational fluid dynamics (CFD). The flow and heat transfer characteristics of different sections are analyzed in detail. The thermal load and the aerodynamic load are then obtained from the temperature field and the pressure distribution. The stress distributions of the blade are finally studied by using computational solid mechanics (CSM) considering three cases of loads: thermal load, aerodynamics load combined with centrifugal load, and all the three types of loads. The detailed parameters of the flow, temperature, and the stress are obtained and analyzed. The numerical results obtained provide a useful knowledge base for further exploration of radial gas turbine design. Yonghui Xie, Kun Lu, Le Liu, and Gongnan Xie Copyright © 2014 Yonghui Xie et al. All rights reserved. Development of Educational Platform for Experiments of Electric Machines Tue, 22 Apr 2014 14:22:47 +0000 http://www.hindawi.com/journals/mpe/2014/984638/ An educational platform to improve the test and the evaluation of the experimental data in electric machine laboratory is developed. The system is complement to the course taught of electric machines to undergraduate students. The proposed system can automatically acquire the experimental data from data acquisition device on the personal computer and transfer the data through interface card to the host server. The host sever performs the essential calculations of the obtained parameters. After the students enter their computational value through system interface, the host server could record, compare, estimate, and chart the result in real time. The system not only improves the efficiency of the experimental data evaluation but also provides the online comments including experimental purposes, principles, necessary instrument equipment, special notes, operation procedures, and results recording. Yuan-Chieh Chin Copyright © 2014 Yuan-Chieh Chin. All rights reserved. Reliability Analysis of a Cold Standby System with Imperfect Repair and under Poisson Shocks Tue, 22 Apr 2014 14:21:15 +0000 http://www.hindawi.com/journals/mpe/2014/507846/ This paper considers the reliability analysis of a two-component cold standby system with a repairman who may have vacation. The system may fail due to intrinsic factors like aging or deteriorating, or external factors such as Poisson shocks. The arrival time of the shocks follows a Poisson process with the intensity . Whenever the magnitude of a shock is larger than the prespecified threshold of the operating component, the operating component will fail. The paper assumes that the intrinsic lifetime and the repair time on the component are an extended Poisson process, the magnitude of the shock and the threshold of the operating component are nonnegative random variables, and the vacation time of the repairman obeys the general continuous probability distribution. By using the vector Markov process theory, the supplementary variable method, Laplace transform, and Tauberian theory, the paper derives a number of reliability indices: system availability, system reliability, the rate of occurrence of the system failure, and the mean time to the first failure of the system. Finally, a numerical example is given to validate the derived indices. Yutian Chen, Xianyun Meng, and Shengqiang Chen Copyright © 2014 Yutian Chen et al. All rights reserved. Force Control for a Pneumatic Cylinder Using Generalized Predictive Controller Approach Tue, 22 Apr 2014 14:20:12 +0000 http://www.hindawi.com/journals/mpe/2014/261829/ Pneumatic cylinder is a well-known device because of its high power to weight ratio, easy use, and environmental safety. Pneumatic cylinder uses air as its power source and converts it to a possible movement such as linear and rotary movement. In order to control the pneumatic cylinder, controller algorithm is needed to control the on-off solenoid valve with encoder and pressure sensor as the feedback inputs. In this paper, generalized predictive controller (GPC) is proposed as the control strategy for the pneumatic cylinder force control. To validate and compare the performance, proportional-integral (PI) controller is also presented. Both controllers algorithms GPC and PI are developed using existing linear model of the cylinder from previous research. Results are presented in simulation and experimental approach using MATLAB-Simulink as the platform. The results show that the GPC is capable of fast response with low steady state error and percentage overshoot compared to PI. Ahmad ’Athif Mohd Faudzi, Nu’man Din Mustafa, and Khairuddin Osman Copyright © 2014 Ahmad ’Athif Mohd Faudzi et al. All rights reserved. A Constrained Power Method for Community Detection in Complex Networks Tue, 22 Apr 2014 14:19:35 +0000 http://www.hindawi.com/journals/mpe/2014/804381/ For an undirected complex network made up with vertices and edges, we developed a fast computing algorithm that divides vertices into different groups by maximizing the standard “modularity” measure of the resulting partitions. The algorithm is based on a simple constrained power method which maximizes a quadratic objective function while satisfying given linear constraints. We evaluated the performance of the algorithm and compared it with a number of state-of-the-art solutions. The new algorithm reported both high optimization quality and fast running speed, and thus it provided a practical tool for community detection and network structure analysis. Wenye Li Copyright © 2014 Wenye Li. All rights reserved. A Comparison of Online Social Networks and Real-Life Social Networks: A Study of Sina Microblogging Tue, 22 Apr 2014 14:01:55 +0000 http://www.hindawi.com/journals/mpe/2014/578713/ Online social networks appear to enrich our social life, which raises the question whether they remove cognitive constraints on human communication and improve human social capabilities. In this paper, we analyze the users' following and followed relationships based on the data of Sina Microblogging and reveal several structural properties of Sina Microblogging. Compared with real-life social networks, our results confirm some similar features. However, Sina Microblogging also shows its own specialties, such as hierarchical structure and degree disassortativity, which all mark a deviation from real-life social networks. The low cost of the online network forms a broader perspective, and the one-way link relationships make it easy to spread information, but the online social network does not make too much difference in the creation of strong interpersonal relationships. Finally, we describe the mechanisms for the formation of these characteristics and discuss the implications of these structural properties for the real-life social networks. Dayong Zhang and Guang Guo Copyright © 2014 Dayong Zhang and Guang Guo. All rights reserved. A Multiagent Evolutionary Algorithm for the Resource-Constrained Project Portfolio Selection and Scheduling Problem Tue, 22 Apr 2014 13:36:43 +0000 http://www.hindawi.com/journals/mpe/2014/302684/ A multiagent evolutionary algorithm is proposed to solve the resource-constrained project portfolio selection and scheduling problem. The proposed algorithm has a dual level structure. In the upper level a set of agents make decisions to select appropriate project portfolios. Each agent selects its project portfolio independently. The neighborhood competition operator and self-learning operator are designed to improve the agent’s energy, that is, the portfolio profit. In the lower level the selected projects are scheduled simultaneously and completion times are computed to estimate the expected portfolio profit. A priority rule-based heuristic is used by each agent to solve the multiproject scheduling problem. A set of instances were generated systematically from the widely used Patterson set. Computational experiments confirmed that the proposed evolutionary algorithm is effective for the resource-constrained project portfolio selection and scheduling problem. Yongyi Shou, Wenwen Xiang, Ying Li, and Weijian Yao Copyright © 2014 Yongyi Shou et al. All rights reserved. Mehar Methods for Fuzzy Optimal Solution and Sensitivity Analysis of Fuzzy Linear Programming with Symmetric Trapezoidal Fuzzy Numbers Tue, 22 Apr 2014 12:38:14 +0000 http://www.hindawi.com/journals/mpe/2014/697085/ The drawbacks of the existing methods to obtain the fuzzy optimal solution of such linear programming problems, in which coefficients of the constraints are represented by real numbers and all the other parameters as well as variables are represented by symmetric trapezoidal fuzzy numbers, are pointed out, and to resolve these drawbacks, a new method (named as Mehar method) is proposed for the same linear programming problems. Also, with the help of proposed Mehar method, a new method, much easy as compared to the existing methods, is proposed to deal with the sensitivity analysis of the same type of linear programming problems. Sukhpreet Kaur Sidhu, Amit Kumar, and S. S. Appadoo Copyright © 2014 Sukhpreet Kaur Sidhu et al. All rights reserved. Mathematical Methods Applied to Digital Image Processing Tue, 22 Apr 2014 12:20:59 +0000 http://www.hindawi.com/journals/mpe/2014/480523/ Yi-Hung Liu, Chung-Hao Chen, and Paul C.-P. Chao Copyright © 2014 Yi-Hung Liu et al. All rights reserved. A Modified SPH Method for Dynamic Failure Simulation of Heterogeneous Material Tue, 22 Apr 2014 12:02:12 +0000 http://www.hindawi.com/journals/mpe/2014/808359/ A modified smoothed particle hydrodynamics (SPH) method is applied to simulate the failure process of heterogeneous materials. An elastoplastic damage model based on an extension form of the unified twin shear strength (UTSS) criterion is adopted. Polycrystalline modeling is introduced to generate the artificial microstructure of specimen for the dynamic simulation of Brazilian splitting test and uniaxial compression test. The strain rate effect on the predicted dynamic tensile and compressive strength is discussed. The final failure patterns and the dynamic strength increments demonstrate good agreements with experimental results. It is illustrated that the polycrystalline modeling approach combined with the SPH method is promising to simulate more complex failure process of heterogeneous materials. G. W. Ma, Q. S. Wang, X. W. Yi, and X. J. Wang Copyright © 2014 G. W. Ma et al. All rights reserved. Energy Efficient Design for OFDM-Based Underlay Cognitive Radio Networks Tue, 22 Apr 2014 11:50:22 +0000 http://www.hindawi.com/journals/mpe/2014/431878/ Conventional designs on OFDM-based underlay cognitive radio (CR) networks mainly focus on interference avoidance and spectral efficiency (SE) improvement. As green radio becomes increasingly important, this paper investigates energy efficient power allocation. Our aim is to maximize energy efficiency (EE), subject to the constraints on the total transmit power, the peak interference power, and the minimum data rate requirement. We first analyze the relationship between SE and EE and solve this optimization problem with the help of bisection search technique. However, the accuracy of the power allocation solution is dependent on the number of iterations. In order to achieve the exact optimal solution, a new energy efficient power allocation scheme is proposed to balance the tradeoff between SE and EE. Simulation results are provided to demonstrate the effectiveness of the proposed schemes. Yunli Chen, Zhengguang Zheng, Yibin Hou, and Yong Li Copyright © 2014 Yunli Chen et al. All rights reserved. Oscillatory Free Convection about a Horizontal Circular Cylinder in the Presence of Heat Generation Tue, 22 Apr 2014 09:29:15 +0000 http://www.hindawi.com/journals/mpe/2014/946495/ The oscillatory free convection about a horizontal circular cylinder in a Newtonian fluid in the presence of heat generation is investigated numerically by using the finite difference method. The surface temperature of the cylinder oscillates harmonically about the temperature of the surrounding medium. Heat is generated internally within the Newtonian fluid at a rate proportional to a power of the temperature difference. It is found that the presence of heat generation significantly increases the temperature and velocity distribution. The effects of the heat generation parameter and the Prandtl number on the surface rate of heat transfer, in terms of the local Nusselt number, and the surface shear stress, in terms of the local skin friction, are shown graphically from the stagnation point of the circular cylinder. Najahulfazliah Zainuddin, Muhaimin Ismoen, Rozaini Roslan, and Ishak Hashim Copyright © 2014 Najahulfazliah Zainuddin et al. All rights reserved. Robust -Stability Controller Design for a Ducted Fan Unmanned Aerial Vehicle Tue, 22 Apr 2014 09:28:33 +0000 http://www.hindawi.com/journals/mpe/2014/746379/ This paper deals with the aerodynamic modeling of a small ducted fan UAV and the problem of attitude stabilization when the parameter of the vehicle is varied. The main aerodynamic model of the hovering flight UAV is first presented. Then, an attitude control is designed from a linearization of the dynamic model around the hovering flight, which is based on the output feedback control theory with D-stability. Simulation results show that such method has good robustness to the attitude system. They can meet the requirements of attitude control and verify further the feasibility of such a control strategy. Xiao-lu Ren, Chang-hong Wang, and Guo-xing Yi Copyright © 2014 Xiao-lu Ren et al. All rights reserved. An Improved Task Scheduling Algorithm for Intelligent Control in Tiny Mechanical System Tue, 22 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/307869/ Wireless sensor network (WSN) has been already widely used in many fields in terms of industry, agriculture, and military, and so forth. The basic composition is WSN nodes that are capable of performing processing, gathering information, and communicating with other connected nodes in the network. The main components of a WSN node are microcontroller, transceiver, and some sensors. Undoubtedly, it also can be added with some actuators to form a tiny mechanical system. Under this case, the existence of task preemption while executing operating system will not only cost more energy for WSN nodes themselves, but also bring unacceptable system states caused by vibrations. However for these nodes, task I/O delays are inevitable due to the existence of task preemption, which will bring extra overhead for the whole system, and even bring unacceptable system states caused by vibrations. This paper mainly considers the earliest deadline first (EDF) task preemption algorithm executed in WSN OS and proposes an improved task preemption algorithm so as to lower the preemption overhead and I/O delay and then improve the system performance. The experimental results show that the improved task preemption algorithm can reduce the I/O delay effectively, so the real-time processing ability of the system is enhanced. Jialiang Wang, Hai Zhao, Yuanguo Bi, Xingchi Chen, Ruofan Zeng, and Yu Wang Copyright © 2014 Jialiang Wang et al. All rights reserved. A Cross-Efficiency Based Ranking Method for Finding the Most Efficient DMU Tue, 22 Apr 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/269768/ In many applications of DEA, ranking of DMUs and finding the most efficient DMU are desirable, as reported by Toloo (2013). In this paper, after introducing an improvement to the measure of cross-efficiency by Jahanshahloo et al. (2011), we develop a new ranking method under the condition of variable returns to scale (VRS). Numerical example illustrates the effectiveness of the proposed cross-efficiency based ranking method and demonstrates the advantages of our proposal, against the other ranking approaches. S. Sadeghi Gavgani and M. Zohrehbandian Copyright © 2014 S. Sadeghi Gavgani and M. Zohrehbandian. All rights reserved. A New Dataset Size Reduction Approach for PCA-Based Classification in OCR Application Thu, 17 Apr 2014 15:02:30 +0000 http://www.hindawi.com/journals/mpe/2014/537428/ A major problem of pattern recognition systems is due to the large volume of training datasets including duplicate and similar training samples. In order to overcome this problem, some dataset size reduction and also dimensionality reduction techniques have been introduced. The algorithms presently used for dataset size reduction usually remove samples near to the centers of classes or support vector samples between different classes. However, the samples near to a class center include valuable information about the class characteristics and the support vector is important for evaluating system efficiency. This paper reports on the use of Modified Frequency Diagram technique for dataset size reduction. In this new proposed technique, a training dataset is rearranged and then sieved. The sieved training dataset along with automatic feature extraction/selection operation using Principal Component Analysis is used in an OCR application. The experimental results obtained when using the proposed system on one of the biggest handwritten Farsi/Arabic numeral standard OCR datasets, Hoda, show about 97% accuracy in the recognition rate. The recognition speed increased by 2.28 times, while the accuracy decreased only by 0.7%, when a sieved version of the dataset, which is only as half as the size of the initial training dataset, was used. Mohammad Amin Shayegan and Saeed Aghabozorgi Copyright © 2014 Mohammad Amin Shayegan and Saeed Aghabozorgi. All rights reserved. A Systematic Evaluation Model for Solar Cell Technologies Thu, 17 Apr 2014 15:00:03 +0000 http://www.hindawi.com/journals/mpe/2014/542351/ Fossil fuels, including coal, petroleum, natural gas, and nuclear energy, are the primary electricity sources currently. However, with depletion of fossil fuels, global warming, nuclear crisis, and increasing environmental consciousness, the demand for renewable energy resources has skyrocketed. Solar energy is one of the most popular renewable energy resources for meeting global energy demands. Even though there are abundant studies on various solar technology developments, there is a lack of studies on solar technology evaluation and selection. Therefore, this research develops a model using interpretive structural modeling (ISM), benefits, opportunities, costs, and risks concept (BOCR), and fuzzy analytic network process (FANP) to aggregate experts' opinions in evaluating current available solar cell technology. A case study in a photovoltaics (PV) firm is used to examine the practicality of the proposed model in selecting the most suitable technology for the firm in manufacturing new products. Chang-Fu Hsu, Rong-Kwei Li, He-Yau Kang, and Amy H. I. Lee Copyright © 2014 Chang-Fu Hsu et al. All rights reserved. A Real-Time Location-Based Services System Using WiFi Fingerprinting Algorithm for Safety Risk Assessment of Workers in Tunnels Thu, 17 Apr 2014 14:59:11 +0000 http://www.hindawi.com/journals/mpe/2014/371456/ This paper investigates the feasibility of a real-time tunnel location-based services (LBS) system to provide workers’ safety protection and various services in concrete dam site. In this study, received signal strength- (RSS-) based location using fingerprinting algorithm and artificial neural network (ANN) risk assessment is employed for position analysis. This tunnel LBS system achieves an online, real-time, intelligent tracking identification feature, and the on-site running system has many functions such as worker emergency call, track history, and location query. Based on ANN with a strong nonlinear mapping, and large-scale parallel processing capabilities, proposed LBS system is effective to evaluate the risk management on worker safety. The field implementation shows that the proposed location algorithm is reliable and accurate (3 to 5 meters) enough for providing real-time positioning service. The proposed LBS system is demonstrated and firstly applied to the second largest hydropower project in the world, to track workers on tunnel site and assure their safety. The results show that the system is simple and easily deployed. Peng Lin, Qingbin Li, Qixiang Fan, Xiangyou Gao, and Senying Hu Copyright © 2014 Peng Lin et al. All rights reserved.