Mathematical Problems in Engineering The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Fractional-Order Controller Design for Oscillatory Fractional Time-Delay Systems Based on the Numerical Inverse Laplace Transform Algorithms Tue, 21 Apr 2015 07:00:40 +0000 Fractional-order time-delay system is thought to be a kind of oscillatory complex system which could not be controlled efficaciously so far because it does not have an analytical solution when using inverse Laplace transform. In this paper, a type of fractional-order controller based on numerical inverse Laplace transform algorithm INVLAP was proposed for the mentioned systems by searching for the optimal controller parameters with the objective function of ITAE index due to the verified nature that fractional-order controllers were the best means of controlling fractional-order systems. Simulations of step unit tracking and load-disturbance responses of the proposed fractional-order optimal controller (FOPID) and corresponding conventional optimal PID (OPID) controller have been done on three typical kinds of fractional time-delay system with different ratio between time delay () and time constant () and a complex high-order fractional time delay system to verify the availability of the presented control method. Lu Liu, Feng Pan, and Dingyu Xue Copyright © 2015 Lu Liu et al. All rights reserved. Deteriorating Inventory Model for Chilled Food Mon, 20 Apr 2015 13:49:31 +0000 With many aspects that affect inventory policy, product perishability is a critical aspect of inventory policy. Most goods will deteriorate during storage and their original value will decline or be lost. Therefore, deterioration should be taken into account in inventory practice. Chilled food products are very common consumer goods that are, in fact, perishable. If the chilled food quality declines over time customers are less likely to buy it. The value the chilled food retains is, however, closely dependent on its quality. From the vendor’s point of view, quantifying quality and remaining value should be a critical business issue. In consequence, we combined the traditional deterioration model and quality prediction model to develop a new deteriorating inventory model for chilled food products. This new model quantifies food quality and remaining value. The model we propose uses real deterioration rate data, and we regard deterioration rate as temperature-dependent. We provide a numerical example to illustrate the solution. Our model demonstrates that high storage temperatures reduce profits and force shorter order cycles. Ming-Feng Yang and Wei-Chung Tseng Copyright © 2015 Ming-Feng Yang and Wei-Chung Tseng. All rights reserved. Multicriteria Decision Model to Support the Assignment of Storage Location of Products in a Warehouse Mon, 20 Apr 2015 13:12:45 +0000 The storage of products has a strategic role in the supply chain: an efficient organization of products in appropriate locations enables these products to be moved faster inside the warehouse and logistics channel, which increases the speed of delivery and the competitiveness of enterprises. The aim of this paper is to propose a multicriteria decision support model for ranking products and assigning them to warehouse storage locations. During the structuring of the model, the nature of the problem was defined as multicriteria; therefore, the SMARTER and lexicographic methods were applied. The results showed an ordering of products that allowed their strategic location in a hypothetical nonautomated warehouse. Denilson Dimas da Silva, Natália Veloso Caldas de Vasconcelos, and Cristiano Alexandre Virginio Cavalcante Copyright © 2015 Denilson Dimas da Silva et al. All rights reserved. Integrated Supply Chain Cooperative Inventory Model with Payment Period Being Dependent on Purchasing Price under Defective Rate Condition Mon, 20 Apr 2015 12:19:10 +0000 In most commercial transactions, the buyer and vendor may usually agree to postpone payment deadline. During such delayed period, the buyer is entitled to keep the products without having to pay the sale price. However, the vendor usually hopes to receive full payment as soon as possible, especially when the transaction involves valuable items; yet, the buyer would offer a higher purchasing price in exchange of a longer postponement. Therefore, we assumed such permissible delayed period is dependent on the purchasing price. As for the manufacturing side, defective products are inevitable from time to time, and not all of those defective products can be repaired. Hence, we would like to add defective production and repair rate to our proposed model and discuss how these factors may affect profits. In addition, holding cost, ordering cost, and transportation cost will also be considered as we develop the integrated inventory model with price-dependent payment period under the possible condition of defective products. We would like to find the maximum of the joint expected total profit for our model and come up with a suitable inventory policy accordingly. In the end, we have also provided a numerical example to clearly illustrate possible solutions. Ming-Feng Yang, Jun-Yuan Kuo, Wei-Hao Chen, and Yi Lin Copyright © 2015 Ming-Feng Yang et al. All rights reserved. Hand Gesture Recognition Using Modified 1$ and Background Subtraction Algorithms Mon, 20 Apr 2015 12:12:29 +0000 Computers and computerized machines have tremendously penetrated all aspects of our lives. This raises the importance of Human-Computer Interface (HCI). The common HCI techniques still rely on simple devices such as keyboard, mice, and joysticks, which are not enough to convoy the latest technology. Hand gesture has become one of the most important attractive alternatives to existing traditional HCI techniques. This paper proposes a new hand gesture detection system for Human-Computer Interaction using real-time video streaming. This is achieved by removing the background using average background algorithm and the 1$ algorithm for hand’s template matching. Then every hand gesture is translated to commands that can be used to control robot movements. The simulation results show that the proposed algorithm can achieve high detection rate and small recognition time under different light changes, scales, rotation, and background. Hazem Khaled, Samir G. Sayed, El Sayed M. Saad, and Hossam Ali Copyright © 2015 Hazem Khaled et al. All rights reserved. A Multiple Attribute Group Decision Making Approach for Solving Problems with the Assessment of Preference Relations Mon, 20 Apr 2015 12:07:58 +0000 A number of theoretical approaches to preference relations are used for multiple attribute decision making (MADM) problems, and fuzzy preference relations is one of them. When more than one person is interested in the same MADM problem, it then becomes a multiple attribute group decision making (MAGDM) problem. For both MADM and MAGDM problems, consistency among the preference relations is very important to the result of the final decision. The research reported in this paper is based on a procedure that uses a fuzzy preference relations matrix which satisfies additive consistency. This matrix is used to solve multiple attribute group decision making problems. In group decision problems, the assessment provided by different experts may diverge considerably. Therefore, the proposed procedure also takes a heterogeneous group of experts into consideration. Moreover, the methods used to construct the decision matrix and determine the attribution of weight are both introduced. Finally a numerical example is used to test the proposed approach; and the results illustrate that the method is simple, effective, and practical. Taho Yang, Yiyo Kuo, David Parker, and Kuan Hung Chen Copyright © 2015 Taho Yang et al. All rights reserved. A Reversible Steganography Scheme of Secret Image Sharing Based on Cellular Automata and Least Significant Bits Construction Mon, 20 Apr 2015 10:09:00 +0000 Secret image sharing schemes have been extensively studied by far. However, there are just a few schemes that can restore both the secret image and the cover image losslessly. These schemes have one or more defects in the following aspects: (1) high computation cost; (2) overflow issue existing when modulus operation is used to restore the cover image and the secret image; (3) part of the cover image being severely modified and the stego images having worse visual quality. In this paper, we combine the methods of least significant bits construction (LSBC) and dynamic embedding with one-dimensional cellular automata to propose a new lossless scheme which solves the above issues and can resist differential attack and support parallel computing. Experimental results also show that this scheme has the merit of big embedding capacity. Wei-Tong Hu, Ming-Chu Li, Cheng Guo, and Li-Feng Yuan Copyright © 2015 Wei-Tong Hu et al. All rights reserved. Research and Application of Improved AGP Algorithm for Structural Optimization Based on Feedforward Neural Networks Mon, 20 Apr 2015 09:47:29 +0000 The adaptive growing and pruning algorithm (AGP) has been improved, and the network pruning is based on the sigmoidal activation value of the node and all the weights of its outgoing connections. The nodes are pruned directly, but those nodes that have internal relation are not removed. The network growing is based on the idea of variance. We directly copy those nodes with high correlation. An improved AGP algorithm (IAGP) is proposed. And it improves the network performance and efficiency. The simulation results show that, compared with the AGP algorithm, the improved method (IAGP) can quickly and accurately predict traffic capacity. Ruliang Wang, Huanlong Sun, Benbo Zha, and Lei Wang Copyright © 2015 Ruliang Wang et al. All rights reserved. Complex Networks: Statistical Properties, Community Structure, and Evolution Mon, 20 Apr 2015 09:29:12 +0000 We investigate the function for different networks based on complex network theory. In this paper, we choose five data sets from various areas to study. In the study of Chinese network, scale-free effect and hierarchical structure features are found in this complex system. These results indicate that the discovered features of Chinese character structure reflect the combination nature of Chinese characters. In addition, we study the community structure in Chinese character network. We can find that community structure is always considered as one of the most significant features in complex networks, and it plays an important role in the topology and function of the networks. Furthermore, we cut all the nodes in the different networks from low degree to high degree and then obtain many networks with different scale. According to the study, two interesting results have been obtained. First, the relationship between the node number of the maximum communities and the number of communities in the corresponding networks is studied and it is linear. Second, when the number of nodes in the maximum communities is increasing, the increasing tendency of the number of its edges slows down; we predict the complex networks have sparsity. The study effectively explains the characteristic and community structure evolution on different networks. Lei Zhang, Jianxiang Cao, and Jianyu Li Copyright © 2015 Lei Zhang et al. All rights reserved. Emergency Vehicle Scheduling Problem with Time Utility in Disasters Mon, 20 Apr 2015 09:18:35 +0000 This paper presents a flexible emergency rescue system which is chiefly composed of three parts, namely, disaster assistance center, relief vehicles, and disaster areas. A novel objective of utility maximization is used to evaluate the entire system in disasters. Considering the uncertain road conditions in the relief distribution, we implement triangular fuzzy number to calculate the vehicle velocity. As a consequence, a fuzzy mathematical model is built to maximize the utility of emergency rescue system and then converted to the crisp counterpart. Finally, the results of numerical experiments obtained by particle swarm optimization (PSO) prove the validity of this proposed mathematical model. Xiaobing Gan, Yan Wang, Junbiao Kuang, Ye Yu, and Ben Niu Copyright © 2015 Xiaobing Gan et al. All rights reserved. A Novel Artificial Bee Colony Algorithm for Function Optimization Mon, 20 Apr 2015 08:30:14 +0000 It is known that both exploration and exploitation are important in the search equations of ABC algorithms. How to well balance the two abilities in the search process is still a challenging problem in ABC algorithms. In this paper, we propose a novel artificial bee algorithm named as “NABC,” by incorporating the information of the global best solution into the solution search equation of the onlookers stage to improve the exploitation. At the same time, we improve the search equation of the employed bees to keep the exploration. The experimental results of NABC tested on a set of 11 numerical benchmark functions show good performance and fast convergence in solving function optimization problems, compared with variant ABC, DE, and PSO algorithms. The application of NABC on solving five standard knapsack problems shows its effectiveness and practicability. Song Zhang and Sanyang Liu Copyright © 2015 Song Zhang and Sanyang Liu. All rights reserved. A Convex-Risk-Measure Based Model and Genetic Algorithm for Portfolio Selection Mon, 20 Apr 2015 08:24:16 +0000 A convex risk measure called weighted expected shortfall (briefly denoted as WES (Chen and Yang, 2011)) is adopted as the risk measure. This measure can reflect the reasonable risk in the stock markets. Then a portfolio optimization model based on this risk measure is set up. Furthermore, a genetic algorithm is proposed for this portfolio optimization model. At last, simulations are made on randomly chosen ten stocks for 60 days (during January 2, 2014 to April 2, 2014) from Wind database (CFD) in Shenzhen Stock Exchange, and the results indicate that the proposed model is reasonable and the proposed algorithm is effective. Weijia Wang, Jie Hu, and Ning Dong Copyright © 2015 Weijia Wang et al. All rights reserved. Joint Optimization Approach of Maintenance and Production Planning for a Multiple-Product Manufacturing System Mon, 20 Apr 2015 07:24:37 +0000 This paper deals with the problem of maintenance and production planning for randomly failing multiple-product manufacturing system. The latter consists of one machine which produces several types of products in order to satisfy random demands corresponding to every type of product. At any given time, the machine can only produce one type of product and then switches to another one. The purpose of this study is to establish sequentially an economical production plan and an optimal maintenance strategy, taking into account the influence of the production rate on the system’s degradation. Analytical models are developed in order to find the production plan and the preventive maintenance strategy which minimizes sequentially the total production/inventory cost and then the total maintenance cost. Finally, a numerical example is presented to illustrate the usefulness of the proposed approach. Lahcen Mifdal, Zied Hajej, and Sofiene Dellagi Copyright © 2015 Lahcen Mifdal et al. All rights reserved. KPCA-ESN Soft-Sensor Model of Polymerization Process Optimized by Biogeography-Based Optimization Algorithm Mon, 20 Apr 2015 07:15:36 +0000 For solving the problem that the conversion rate of vinyl chloride monomer (VCM) is hard for real-time online measurement in the polyvinyl chloride (PVC) polymerization production process, a soft-sensor modeling method based on echo state network (ESN) is put forward. By analyzing PVC polymerization process ten secondary variables are selected as input variables of the soft-sensor model, and the kernel principal component analysis (KPCA) method is carried out on the data preprocessing of input variables, which reduces the dimensions of the high-dimensional data. The -means clustering method is used to divide data samples into several clusters as inputs of each submodel. Then for each submodel the biogeography-based optimization algorithm (BBOA) is used to optimize the structure parameters of the ESN to realize the nonlinear mapping between input and output variables of the soft-sensor model. Finally, the weighted summation of outputs of each submodel is selected as the final output. The simulation results show that the proposed soft-sensor model can significantly improve the prediction precision of conversion rate and conversion velocity in the process of PVC polymerization and can satisfy the real-time control requirement of the PVC polymerization process. Wen-hua Cui, Jie-sheng Wang, and Shu-xia Li Copyright © 2015 Wen-hua Cui et al. All rights reserved. Sampled-Data Control of Nonlinear Systems with Quantization Sun, 19 Apr 2015 14:52:36 +0000 This paper is concerned with sampled-data control problem for a class of nonlinear systems with input quantization. The nonlinear system is converted into a linear-like system with modeling error by using partition of unity method. A time-dependent Lyapunov functional is introduced to capture the characteristic of nonlinear sampled-data systems and the exponential stability conditions are derived by the use of inequality techniques. The desired sampled-data controller is then synthesized. An example is provided to illustrate the effectiveness and benefits of the proposed scheme. Liu Cui and Dengping Duan Copyright © 2015 Liu Cui and Dengping Duan. All rights reserved. A Line-Based Adaptive-Weight Matching Algorithm Using Loopy Belief Propagation Sun, 19 Apr 2015 12:25:50 +0000 In traditional adaptive-weight stereo matching, the rectangular shaped support region requires excess memory consumption and time. We propose a novel line-based stereo matching algorithm for obtaining a more accurate disparity map with low computation complexity. This algorithm can be divided into two steps: disparity map initialization and disparity map refinement. In the initialization step, a new adaptive-weight model based on the linear support region is put forward for cost aggregation. In this model, the neural network is used to evaluate the spatial proximity, and the mean-shift segmentation method is used to improve the accuracy of color similarity; the Birchfield pixel dissimilarity function and the census transform are adopted to establish the dissimilarity measurement function. Then the initial disparity map is obtained by loopy belief propagation. In the refinement step, the disparity map is optimized by iterative left-right consistency checking method and segmentation voting method. The parameter values involved in this algorithm are determined with many simulation experiments to further improve the matching effect. Simulation results indicate that this new matching method performs well on standard stereo benchmarks and running time of our algorithm is remarkably lower than that of algorithm with rectangle-shaped support region. Hui Li, Xiao-Guang Zhang, and Zheng Sun Copyright © 2015 Hui Li et al. All rights reserved. A Well-Balanced and Fully Coupled Noncapacity Model for Dam-Break Flooding Sun, 19 Apr 2015 11:58:51 +0000 The last two decades have seen great progress in mathematical modeling of fluvial processes and flooding in terms of either approximation of the physical processes or dealing with the numerical difficulties. Yet attention to simultaneously taking advancements of both aspects is rarely paid. Here a well-balanced and fully coupled noncapacity model is presented of dam-break flooding over erodible beds. The governing equations are based on the complete mass and momentum conservation laws, implying fully coupled interactions between the dam-break flow and sediment transport. A well-balanced Godunov-type finite volume method is used to solve the governing equations, facilitating satisfactory representation of the complex flow phenomena. The well-balanced property is attained by using the divergence form of matrix related to the static force for the bottom slope source term. Existing classical tests, including idealized dam-break flooding over irregular topography and experimental dam-break flooding with/without sediment transport, are numerically simulated, showing a satisfactory quantitative performance of this model. Zhiyuan Yue, Huaihan Liu, Youwei Li, Peng Hu, and Yanyan Zhang Copyright © 2015 Zhiyuan Yue et al. All rights reserved. Derivation of Diagonally Implicit Block Backward Differentiation Formulas for Solving Stiff Initial Value Problems Sun, 19 Apr 2015 09:23:26 +0000 The diagonally implicit 2-point block backward differentiation formulas (DI2BBDF) of order two, order three, and order four are derived for solving stiff initial value problems (IVPs). The stability properties of the derived methods are investigated. The implementation of the method using Newton iteration is also discussed. The performance of the proposed methods in terms of maximum error and computational time is compared with the fully implicit block backward differentiation formulas (FIBBDF) and fully implicit block extended backward differentiation formulas (FIBEBDF). The numerical results show that the proposed method outperformed both existing methods. Iskandar Shah Mohd Zawawi, Zarina Bibi Ibrahim, and Khairil Iskandar Othman Copyright © 2015 Iskandar Shah Mohd Zawawi et al. All rights reserved. Robust Adaptive PID Controller for a Class of Uncertain Nonlinear Systems: An Application for Speed Tracking Control of an SI Engine Sun, 19 Apr 2015 07:49:07 +0000 The sliding mode control (SMC) technique with a first-order low-pass filter (LPF) is incorporated with a new adaptive PID controller. It is proposed for tracking control of an uncertain nonlinear system. In the proposed control scheme, the adaptation law is able to update the PID controller online during the control process within a short period. The chattering phenomenon of the SMC can be alleviated by incorporation of a first-order LPF, while the robustness of the control system is similar to that of the sliding mode. In the closed-loop control analysis, the convergence condition in the reaching phase and the existence condition of the sliding mode were analyzed. The stability of the closed-loop control is guaranteed in the sense of Lyapunov’s direct method. The simulations and experimental applications of a speed tracking control of a spark ignition (SI) engine via electronic throttle valve control architecture are provided to verify the effectiveness and the feasibility of the proposed control scheme. Tossaporn Chamsai, Piyoros Jirawattana, and Thana Radpukdee Copyright © 2015 Tossaporn Chamsai et al. All rights reserved. Optimal Sizing of a Photovoltaic-Hydrogen Power System for HALE Aircraft by means of Particle Swarm Optimization Sun, 19 Apr 2015 07:49:01 +0000 Over the last decade there has been a growing interest in the research of feasibility to use high altitude long endurance (HALE) aircrafts in order to provide mobile communications. The use of HALEs for telecommunication networks has the potential to deliver a wide range of communication services (from high-quality voice to high-definition videos, as well as high-data-rate wireless channels) cost effectively. One of the main challenges of this technology is to design its power supply system, which must provide the enough energy for long time flights in a reliable way. In this paper a photovoltaic/hydrogen system is proposed as power system for a HALE aircraft due its high power density characteristic. In order to obtain the optimal sizing for photovoltaic/hydrogen system a particle swarm optimizer (PSO) is used. As a case study, theoretical design of the photovoltaic/hydrogen power system for three different HALE aircrafts located at 18° latitude is presented. At this latitude, the range of solar radiation intensity was from 310 to 450 Wh/sqm/day. The results obtained show that the photovoltaic/hydrogen systems calculated by PSO can operate during one year with efficacies ranging between 45.82% and 47.81%. The obtained sizing result ensures that the photovoltaic/hydrogen system supplies adequate energy for HALE aircrafts. Victor M. Sanchez, Romeli Barbosa, J. C. Cruz, F. Chan, and J. Hernandez Copyright © 2015 Victor M. Sanchez et al. All rights reserved. Spectral Clustering with Local Projection Distance Measurement Sun, 19 Apr 2015 06:57:41 +0000 Constructing a rational affinity matrix is crucial for spectral clustering. In this paper, a novel spectral clustering via local projection distance measure (LPDM) is proposed. In this method, the Local-Projection-Neighborhood (LPN) is defined, which is a region between a pair of data, and other data in the LPN are projected onto the straight line among the data pairs. Utilizing the Euclidean distance between projective points, the local spatial structure of data can be well detected to measure the similarity of objects. Then the affinity matrix can be obtained by using a new similarity measurement, which can squeeze or widen the projective distance with the different spatial structure of data. Experimental results show that the LPDM algorithm can obtain desirable results with high performance on synthetic datasets, real-world datasets, and images. Chen Diao, Ai-Hua Zhang, and Bin Wang Copyright © 2015 Chen Diao et al. All rights reserved. Effects of Upstream Water Level on Dynamic Response of Earth Dam Thu, 16 Apr 2015 13:44:18 +0000 The island of Taiwan is located between the boundaries of the Eurasia and the Philippines Plates and thus earthquakes occurred frequently. The excitation of earthquake affects the integrity of earth dams situated in the mountainous area of the island. A study was conducted to evaluate the dynamic response and safety of one of the earthquake dams. The computer program and soil model used were calibrated for their appropriate use for the subject dam against a well-instrumented centrifuge model. Numerical simulation was then conducted to examine the influence of upstream water storage level on the response of the earth dam. The numerical results identified three locations in the dam where attentions are required because these locations were found susceptible to liquefaction. Shong-Loong Chen, Chun-Fu Lin, James C. Ni, and Meen-Wah Gui Copyright © 2015 Shong-Loong Chen et al. All rights reserved. On the Analytical Approach to Present Engineering Problems: Photovoltaic Systems Behavior, Wind Speed Sensors Performance, and High-Speed Train Pressure Wave Effects in Tunnels Thu, 16 Apr 2015 12:41:54 +0000 At present, engineering problems required quite a sophisticated calculation means. However, analytical models still can prove to be a useful tool for engineers and scientists when dealing with complex physical phenomena. The mathematical models developed to analyze three different engineering problems: photovoltaic devices analysis; cup anemometer performance; and high-speed train pressure wave effects in tunnels are described. In all cases, the results are quite accurate when compared to testing measurements. Santiago Pindado, Javier Cubas, and Félix Sorribes-Palmer Copyright © 2015 Santiago Pindado et al. All rights reserved. Controlled Passage through Resonance for Flexible Vibration Units Thu, 16 Apr 2015 12:22:20 +0000 The problem of controlled passage through resonance zone for mechanical systems with several degrees of freedom is studied. Control algorithm design is based on speed-gradient method and estimate for the frequency of the slow motion near resonance (Blekhman frequency). The simulation results for two-rotor flexible vibration units illustrating efficiency of the proposed algorithms and fractal dependence of the passage time on the initial conditions are presented. The novelty of the results is in demonstration of good behavior of the closed loop system if flexibility is taken into account. Dmitry A. Tomchin, Olga P. Tomchina, and Alexander L. Fradkov Copyright © 2015 Dmitry A. Tomchin et al. All rights reserved. Rational Quadratic Trigonometric Interpolation Spline for Data Visualization Thu, 16 Apr 2015 08:21:07 +0000 A new piecewise rational quadratic trigonometric spline with four local positive shape parameters in each subinterval is constructed to visualize the given planar data. Constraints are derived on these free shape parameters to generate shape preserving interpolation curves for positive and/or monotonic data sets. Two of these shape parameters are constrained while the other two can be set free to interactively control the shape of the curves. Moreover, the order of approximation of developed interpolant is investigated as . Numeric experiments demonstrate that our method can construct nice shape preserving interpolation curves efficiently. Shengjun Liu, Zhili Chen, and Yuanpeng Zhu Copyright © 2015 Shengjun Liu et al. All rights reserved. Lunar CubeSat Impact Trajectory Characteristics as a Function of Its Release Conditions Thu, 16 Apr 2015 07:57:26 +0000 As a part of early system design activities, trajectory characteristics for a lunar CubeSat impactor mission as a function of its release conditions are analyzed. The goal of this mission is to take measurements of surface magnetic fields to study lunar magnetic anomalies. To deploy the CubeSat impactor, a mother-ship is assumed to have a circular polar orbit with inclination of 90 degrees at a 100 km altitude at the Moon. Both the in- and out-of-plane direction deploy angles as well as delta-V magnitudes are considered for the CubeSat release conditions. All necessary parameters required at the early design phase are analyzed, including CubeSat flight time to reach the lunar surface, impact velocity, cross ranges distance, and associated impact angles, which are all directly affected by the CubeSat release conditions. Also, relative motions between these two satellites are analyzed for communication and navigation purposes. Although the current analysis is only focused on a lunar impactor mission, the methods described in this work can easily be modified and applied to any future planetary impactor missions with CubeSat-based payloads. Young-Joo Song, Ho Jin, and Ian Garick-Bethell Copyright © 2015 Young-Joo Song et al. All rights reserved. Computation of Program Source Code Similarity by Composition of Parse Tree and Call Graph Thu, 16 Apr 2015 07:33:38 +0000 This paper proposes a novel method to compute how similar two program source codes are. Since a program source code is represented as a structural form, the proposed method adopts convolution kernel functions as a similarity measure. Actually, a program source code has two kinds of structural information. One is syntactic information and the other is the dependencies of function calls lying on the program. Since the syntactic information of a program is expressed as its parse tree, the syntactic similarity between two programs is computed by a parse tree kernel. The function calls within a program provide a global structure of a program and can be represented as a graph. Therefore, the similarity of function calls is computed with a graph kernel. Then, both structural similarities are reflected simultaneously into comparing program source codes by composing the parse tree and the graph kernels based on a cyclomatic complexity. According to the experimental results on a real data set for program plagiarism detection, the proposed method is proved to be effective in capturing the similarity between programs. The experiments show that the plagiarized pairs of programs are found correctly and thoroughly by the proposed method. Hyun-Je Song, Seong-Bae Park, and Se Young Park Copyright © 2015 Hyun-Je Song et al. All rights reserved. Hybrid Biogeography Based Optimization for Constrained Numerical and Engineering Optimization Thu, 16 Apr 2015 07:18:13 +0000 Biogeography based optimization (BBO) is a new competitive population-based algorithm inspired by biogeography. It simulates the migration of species in nature to share information. A new hybrid BBO (HBBO) is presented in the paper for constrained optimization. By combining differential evolution (DE) mutation operator with simulated binary crosser (SBX) of genetic algorithms (GAs) reasonably, a new mutation operator is proposed to generate promising solution instead of the random mutation in basic BBO. In addition, DE mutation is still integrated to update one half of population to further lead the evolution towards the global optimum and the chaotic search is introduced to improve the diversity of population. HBBO is tested on twelve benchmark functions and four engineering optimization problems. Experimental results demonstrate that HBBO is effective and efficient for constrained optimization and in contrast with other state-of-the-art evolutionary algorithms (EAs), the performance of HBBO is better, or at least comparable in terms of the quality of the final solutions and computational cost. Furthermore, the influence of the maximum mutation rate is also investigated. Zengqiang Mi, Yikun Xu, Yang Yu, Tong Zhao, Bo Zhao, and Liqing Liu Copyright © 2015 Zengqiang Mi et al. All rights reserved. Time- or Space-Dependent Coefficient Recovery in Parabolic Partial Differential Equation for Sensor Array in the Biological Computing Thu, 16 Apr 2015 06:11:55 +0000 This study presents numerical schemes for solving a parabolic partial differential equation with a time- or space-dependent coefficient subject to an extra measurement. Through the extra measurement, the inverse problem is transformed into an equivalent nonlinear equation which is much simpler to handle. By the variational iteration method, we obtain the exact solution and the unknown coefficients. The results of numerical experiments and stable experiments imply that the variational iteration method is very suitable to solve these inverse problems. Guanglu Zhou, Boying Wu, Wen Ji, and Seungmin Rho Copyright © 2015 Guanglu Zhou et al. All rights reserved. The Active Fractional Order Control for Maglev Suspension System Thu, 16 Apr 2015 06:00:48 +0000 Maglev suspension system is the core part of maglev train. In the practical application, the load uncertainties, inherent nonlinearity, and misalignment between sensors and actuators are the main issues that should be solved carefully. In order to design a suitable controller, the attention is paid to the fractional order controller. Firstly, the mathematical model of a single electromagnetic suspension unit is derived. Then, considering the limitation of the traditional PD controller adaptation, the fractional order controller is developed to obtain more excellent suspension specifications and robust performance. In reality, the nonlinearity affects the structure and the precision of the model after linearization, which will degrade the dynamic performance. So, a fractional order controller is addressed to eliminate the disturbance by adjusting the parameters which are added by the fractional order controller. Furthermore, the controller based on LQR is employed to compare with the fractional order controller. Finally, the performance of them is discussed by simulation. The results illustrated the validity of the fractional order controller. Peichang Yu, Jie Li, and Jinhui Li Copyright © 2015 Peichang Yu et al. All rights reserved.