Mathematical Problems in Engineering http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Approximate Dual Averaging Method for Multiagent Saddle-Point Problems with Stochastic Subgradients Tue, 02 Sep 2014 11:01:37 +0000 http://www.hindawi.com/journals/mpe/2014/202737/ This paper considers the problem of solving the saddle-point problem over a network, which consists of multiple interacting agents. The global objective function of the problem is a combination of local convex-concave functions, each of which is only available to one agent. Our main focus is on the case where the projection steps are calculated approximately and the subgradients are corrupted by some stochastic noises. We propose an approximate version of the standard dual averaging method and show that the standard convergence rate is preserved, provided that the projection errors decrease at some appropriate rate and the noises are zero-mean and have bounded variance. Deming Yuan and Yang Yang Copyright © 2014 Deming Yuan and Yang Yang. All rights reserved. Optimal Control with Time Delays via the Penalty Method Tue, 02 Sep 2014 05:29:48 +0000 http://www.hindawi.com/journals/mpe/2014/250419/ We prove necessary optimality conditions of Euler-Lagrange type for a problem of the calculus of variations with time delays, where the delay in the unknown function is different from the delay in its derivative. Then, a more general optimal control problem with time delays is considered. Main result gives a convergence theorem, allowing us to obtain a solution to the delayed optimal control problem by considering a sequence of delayed problems of the calculus of variations. Mohammed Benharrat and Delfim F. M. Torres Copyright © 2014 Mohammed Benharrat and Delfim F. M. Torres. All rights reserved. Fault Tolerant Mechanism for Multimedia Flows in Wireless Ad Hoc Networks Based on Fast Switching Paths Tue, 02 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/361543/ Multimedia traffic can be forwarded through a wireless ad hoc network using the available resources of the nodes. Several models and protocols have been designed in order to organize and arrange the nodes to improve transmissions along the network. We use a cluster-based framework, called MWAHCA architecture, which optimizes multimedia transmissions over a wireless ad hoc network. It was proposed by us in a previous research work. This architecture is focused on decreasing quality of service (QoS) parameters like latency, jitter, and packet loss, but other network features were not developed, like load balance or fault tolerance. In this paper, we propose a new fault tolerance mechanism, using as a base the MWAHCA architecture, in order to recover any multimedia flow crossing the wireless ad hoc network when there is a node failure. The algorithm can run independently for each multimedia flow. The main objective is to keep the QoS parameters as low as possible. To achieve this goal, the convergence time must be controlled and reduced. This paper provides the designed protocol, the analytical model of the algorithm, and a software application developed to test its performance in a real laboratory. Juan R. Diaz, Jaime Lloret, Jose M. Jimenez, Sandra Sendra, and Joel J. P. C. Rodrigues Copyright © 2014 Juan R. Diaz et al. All rights reserved. Flower Pollination Algorithm with Dimension by Dimension Improvement Mon, 01 Sep 2014 10:37:49 +0000 http://www.hindawi.com/journals/mpe/2014/481791/ Flower pollination algorithm (FPA) is a new nature-inspired intelligent algorithm which uses the whole update and evaluation strategy on solutions. For solving multidimension function optimization problems, this strategy may deteriorate the convergence speed and the quality of solution of algorithm due to interference phenomena among dimensions. To overcome this shortage, in this paper a dimension by dimension improvement based flower pollination algorithm is proposed. In the progress of iteration of improved algorithm, a dimension by dimension based update and evaluation strategy on solutions is used. And, in order to enhance the local searching ability, local neighborhood search strategy is also applied in this improved algorithm. The simulation experiments show that the proposed strategies can improve the convergence speed and the quality of solutions effectively. Rui Wang and Yongquan Zhou Copyright © 2014 Rui Wang and Yongquan Zhou. All rights reserved. Development of Highly Interactive Service Platform for Social Learning via Ubiquitous Media Mon, 01 Sep 2014 10:30:24 +0000 http://www.hindawi.com/journals/mpe/2014/395295/ Several emerging issues concerning the development of interactive learning environment were left unsolved although e-learning has been applied for years. With several studies indicate that more interaction between students and systems increases students’ level of interest and allows them to focus on learning support. Due to the way current interactive learning tools are designed, users have to wear or operate actual tools in order to carry out the required learning procedures. The use of tools for long durations of time results in user fatigue. Hence, this study incorporates the Microsoft Kinect as interactive tool for detecting gestures in the e-learning process. This study also uses the interaction method that we had developed on Facebook to interact with the proposed learning system. The experiments in this study are divided into five parts: system performance of the 3D web engine, gesture accuracy, system and gesture usability, system and gesture satisfaction, and learning satisfaction of the learner. Also, the gesture design was accepted by learners when they interacted with the learning system. Our research shows that our concept as well as the features of our system can fully support social learning and enhance interaction between users in learning environments. Gangman Yi and Neil Y. Yen Copyright © 2014 Gangman Yi and Neil Y. Yen. All rights reserved. Detecting Local Community Structures in Networks Based on Boundary Identification Mon, 01 Sep 2014 08:58:50 +0000 http://www.hindawi.com/journals/mpe/2014/682015/ Detecting communities within networks is of great importance to understand the structure and organizations of real-world systems. To this end, one of the major challenges is to find the local community from a given node with limited knowledge of the global network. Most of the existing methods largely depend on the starting node and require predefined parameters to control the agglomeration procedure, which may cause disturbing inference to the results of local community detection. In this work, we propose a parameter-free local community detecting algorithm, which uses two self-adaptive phases in detecting the local community, thus comprehensively considering the external and internal link similarity of neighborhood nodes in each clustering iteration. Based on boundary nodes identification, our self-adaptive method can effectively control the scale and scope of the local community. Experimental results show that our algorithm is efficient and well-behaved in both computer-generated and real-world networks, greatly improving the performance of local community detection in terms of stability and accuracy. Liu Yang, Ji Xin-sheng, Liu Caixia, and Wang Ding Copyright © 2014 Liu Yang et al. All rights reserved. Stability of Delayed Hopfield Neural Networks with Variable-Time Impulses Mon, 01 Sep 2014 06:34:46 +0000 http://www.hindawi.com/journals/mpe/2014/154036/ In this paper the globally exponential stability criteria of delayed Hopfield neural networks with variable-time impulses are established. The proposed criteria can also be applied in Hopfield neural networks with fixed-time impulses. A numerical example is presented to illustrate the effectiveness of our theoretical results. Yangjun Pei, Chao Liu, and Qi Han Copyright © 2014 Yangjun Pei et al. All rights reserved. FDIR for the IMU Component of AOCS Systems Mon, 01 Sep 2014 05:39:26 +0000 http://www.hindawi.com/journals/mpe/2014/302716/ The main objective of this paper is the study of a FDIR for an IMU aiming at space applications with focus on the gyro signal analysis and the tests of the filtering algorithms. The algorithms have been tested by using lab data provided by the DMC LABSIM (Physical’s Simulation Laboratory of the Space Mechanics and Control Division of INPE). The results have demonstrated good agreement with the concepts applied in this study. Automatic detection procedures are very important in the characterization of occurrence, definition of criteria, and device types in the scenario of AOCS FDIR. An IMU comprised of four gyros in a tetrahedral configuration is one of the assumed components for the AOCS (attitude and orbit control subsystem) considered in this work. The types of failures considered in this paper are the step abrupt change, ramp/drift/slow, stuck, cyclic, erratic, spike, and finally the stuck for variance alteration noise. An appropriate algorithm for the automatic detection of each type of fault is developed. The approach includes the mapping capability of fault event indicators to the IMU. This mapping is very important in the characterization of the occurrence, definition of criteria, and device types as well as associated fault identification for an AOCS. Maurício N. Pontuschka and Ijar M. da Fonseca Copyright © 2014 Maurício N. Pontuschka and Ijar M. da Fonseca. All rights reserved. Hybrid Structure Based Tracking and Consensus for Multiple Motors Mon, 01 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/967578/ This paper investigates a hybrid structure based synchronous control strategy for multimotor system of shaftless-driven printing press. Many existing algorithms can obtain a stable synchronous system; however, the obtained stable system may encounter a large enough disturbance that can destroy the synchronization. Focusing on this challenging technological problem about how to receive more robust synchronization during steady-state process, this paper first proposes a state-dependent-switching based leader-following control approach, in which synchronization includes two parts, one associated with tracking control for all members, and the other one associated with consensus maintained among followers in the case that one follower loses synchronization with the leader during steady-state motion. By employing the algebra graph theory, matrix theory, and Lyapunov analysis, the convergence and stability of the given multimotor system are proved. Finally, simulation examples are presented to demonstrate the effectiveness and robustness of the theoretical results. Changfan Zhang, Han Wu, Bin Liu, Jing He, and Baiyan Li Copyright © 2014 Changfan Zhang et al. All rights reserved. An MPCA/LDA Based Dimensionality Reduction Algorithm for Face Recognition Sun, 31 Aug 2014 11:22:15 +0000 http://www.hindawi.com/journals/mpe/2014/393265/ We proposed a face recognition algorithm based on both the multilinear principal component analysis (MPCA) and linear discriminant analysis (LDA). Compared with current traditional existing face recognition methods, our approach treats face images as multidimensional tensor in order to find the optimal tensor subspace for accomplishing dimension reduction. The LDA is used to project samples to a new discriminant feature space, while the K nearest neighbor (KNN) is adopted for sample set classification. The results of our study and the developed algorithm are validated with face databases ORL, FERET, and YALE and compared with PCA, MPCA, and PCA + LDA methods, which demonstrates an improvement in face recognition accuracy. Jun Huang, Kehua Su, Jamal El-Den, Tao Hu, and Junlong Li Copyright © 2014 Jun Huang et al. All rights reserved. The Application of the SCT and the ANP Model to Refine the Most Critical ICT Determinants in Minimizing the Digital Divide Sun, 31 Aug 2014 11:10:48 +0000 http://www.hindawi.com/journals/mpe/2014/309675/ This research cross-employed the social cognition theory (SCT) and the analytical network process (ANP) model in qualitative analyses and the multiple criteria decision making (MCDM) methodology in quantitative measurements to comprehensively re-identify the most critical information communication technology (ICT) determinants in minimizing the digital divide (DD). After measuring the complete importance of related priority weight (eigenvector) from the survey results given to various experts, the complete synthetically comparative index numbers (SCIN) from the evaluation model used conveyed two distinct consequences. First, the highest SCIN scores for the ANP, F-ANP, and G-ANP models are 0.5516, 0.3771, and 0.4791, respectively, and are located in the “ICT can positively minimize the level of DD” (ICTCPMDD) column in the summarized results table. Secondly, the highest evaluated weighted score of assessed criteria of 0.5801 is located in the Diversified Mobile Applications (DMAPP) column. From these results, there are two contributive findings that can be deduced. First, ICT indeed proved the determinative influences and interplays in the level of DD which means that the undeveloped, developing, and emerging regions are apparently able to minimize the level of DD by means of the ICT development. Second, the Diversified Mobile Applications (DMAPP) is the most critical determinant of ICT in minimizing the level of digital divide. Ming-Yuan Hsieh Copyright © 2014 Ming-Yuan Hsieh. All rights reserved. Stochastic Dominance under the Nonlinear Expected Utilities Sun, 31 Aug 2014 10:46:49 +0000 http://www.hindawi.com/journals/mpe/2014/713738/ In 1947, von Neumann and Morgenstern introduced the well-known expected utility and the related axiomatic system (see von Neumann and Morgenstern (1953)). It is widely used in economics, for example, financial economics. But the well-known Allais paradox (see Allais (1979)) shows that the linear expected utility has some limitations sometimes. Because of this, Peng proposed a concept of nonlinear expected utility (see Peng (2005)). In this paper we propose a concept of stochastic dominance under the nonlinear expected utilities. We give sufficient conditions on which a random choice stochastically dominates a random choice under the nonlinear expected utilities. We also provide sufficient conditions on which a random choice strictly stochastically dominates a random choice under the sublinear expected utilities. Xinling Xiao Copyright © 2014 Xinling Xiao. All rights reserved. Design of Information System for Milking Dairy Cattle and Detection of Mastitis Sun, 31 Aug 2014 09:22:12 +0000 http://www.hindawi.com/journals/mpe/2014/759019/ A novel information system for detecting mastitis in dairy cattle and managing their milking processes in the milking parlor is designed. The system comprises three major subsystems—the mastitis detection device, the information display device, and the cloud database. The mastitis detection device can detect and evaluate the degree of mastitis immediately before the milking operations are carried out. The information display device shows information on the health of the dairy cattle obtained from a cloud database to manage the milk production of a dairy farm. Importantly, the proposed system utilizes a wireless sensor network (WSN) with low power consumption that connects the information display device with the remote management system. Experimental results reveal that our proposed system can reduce the risk of milking cattle with mastitis and improve efficiency of milk production. Ming-Chih Chen, Chien-Hsing Chen, and Chong-Yu Siang Copyright © 2014 Ming-Chih Chen et al. All rights reserved. Batch Delivery Scheduling with Multiple Decentralized Manufacturers Sun, 31 Aug 2014 09:04:03 +0000 http://www.hindawi.com/journals/mpe/2014/321513/ This paper addresses an integrated decision on production scheduling and delivery operations, which is one of the most important issues in supply chain scheduling. We study a model in which a set of jobs ordered by only one customer and a set of decentralized manufacturers located at different locations are considered. Specifically, each job must be assigned to one of the decentralized manufacturers to process on its single machine facility. Then, the job is delivered to the customer directly in batch without intermediate inventory. The objective is to find a joint schedule of production and distribution to optimize the customer service level and delivery cost. In our work, we discuss this problem considering two different situations in terms of the customer service level. In the first one, the customer service is measured by the maximum arrival time, while the customer service is measured by the total arrival time in the second one. For each situation, we develop a dynamic programming algorithm to solve, respectively. Moreover, we identify a special case for the latter situation by introducing its corresponding solutions. Shi Li, Xueling Zhong, Hong Li, and Sujian Li Copyright © 2014 Shi Li et al. All rights reserved. Clock Synchronization in Wireless Sensor Networks: A New Model and Analysis Approach Based on Networked Control Perspective Sun, 31 Aug 2014 08:48:29 +0000 http://www.hindawi.com/journals/mpe/2014/731980/ Motivated by the importance of the clock synchronization in wireless sensor networks (WSNs), this paper proposes a new research approach and model approach, which quantitatively analyzes clock synchronization from the perspective of modern control theory. Two kinds of control strategies are used as examples to analyze the effect of the control strategy on clock synchronization from different perspectives, namely, the single-step optimal control and the LQG global optimal control. The proposed method establishes a state space model for clock relationship, thus making dimension extension and parameter identification easier, and is robust to changes under the condition of node failures and new nodes. And through the design of different control strategies and performance index functions, the method can satisfy various requirements of the synchronization precision, convergence speed, energy consumption and the computational complexity, and so on. Finally, the simulations show that the synchronization accuracy of the proposed method is higher than that of the existing protocol, and the former convergence speed of the synchronization error is faster. Wang Ting, Cai Chun-yang, Guo Di, Tang Xiao-ming, and Wang Heng Copyright © 2014 Wang Ting et al. All rights reserved. An Empirical Study of Parameter Estimation for Stated Preference Experimental Design Sun, 31 Aug 2014 08:45:18 +0000 http://www.hindawi.com/journals/mpe/2014/292608/ The stated preference experimental design can affect the reliability of the parameters estimation in discrete choice model. Some scholars have proposed some new experimental designs, such as D-efficient, Bayesian D-efficient. But insufficient empirical research has been conducted on the effectiveness of these new designs and there has been little comparative analysis of the new designs against the traditional designs. In this paper, a new metro connecting Chengdu and its satellite cities is taken as the research subject to demonstrate the validity of the D-efficient and Bayesian D-efficient design. Comparisons between these new designs and orthogonal design were made by the fit of model and standard deviation of parameters estimation; then the best model result is obtained to analyze the travel choice behavior. The results indicate that Bayesian D-efficient design works better than D-efficient design. Some of the variables can affect significantly the choice behavior of people, including the waiting time and arrival time. The D-efficient and Bayesian D-efficient design for MNL can acquire reliability result in ML model, but the ML model cannot develop the theory advantages of these two designs. Finally, the metro can handle over 40% passengers flow if the metro will be operated in the future. Fei Yang, Lin Chen, Yang Cheng, Xia Luo, and Bin Ran Copyright © 2014 Fei Yang et al. All rights reserved. Computational Experiment Study on Selection Mechanism of Project Delivery Method Based on Complex Factors Sun, 31 Aug 2014 08:12:30 +0000 http://www.hindawi.com/journals/mpe/2014/701652/ Project delivery planning is a key stage used by the project owner (or project investor) for organizing design, construction, and other operations in a construction project. The main task in this stage is to select an appropriate project delivery method. In order to analyze different factors affecting the PDM selection, this paper establishes a multiagent model mainly to show how project complexity, governance strength, and market environment affect the project owner’s decision on PDM. Experiment results show that project owner usually choose Design-Build method when the project is very complex within a certain range. Besides, this paper points out that Design-Build method will be the prior choice when the potential contractors develop quickly. This paper provides the owners with methods and suggestions in terms of showing how the factors affect PDM selection, and it may improve the project performance. Xiang Ding, Zhaohan Sheng, Jianguo Du, and Qian Li Copyright © 2014 Xiang Ding et al. All rights reserved. Developing Blue Ocean Strategy of Sustainable Product Design and Development for Business Opportunities of BOP Groups in Taiwan Sun, 31 Aug 2014 07:53:27 +0000 http://www.hindawi.com/journals/mpe/2014/297524/ This study expands the definition of the poor group and attempts to delve into and make known the phenomenon of poverty in Taiwan and aims to explore the goals and possibilities of the BOP consumer market. Through a questionnaire survey and expert interviews, this research adopts the concept of sustainability to discuss the lifestyle and consumption characteristics of the BOP group and establishes a design strategic norm of the sustainable products. The findings show that the BOP group in Taiwan is new poverty or working poor and high quality and common prices are the main requirements; these should be introduced into the development model of sustainable design. Jui-Che Tu, Min-Chieh Shih, Chuan-Ying Hsu, and Jian-Hao Lin Copyright © 2014 Jui-Che Tu et al. All rights reserved. The Dynamic Model Embed in Augmented Graph Cuts for Robust Hand Tracking and Segmentation in Videos Sun, 31 Aug 2014 07:44:59 +0000 http://www.hindawi.com/journals/mpe/2014/320141/ Segmenting human hand is important in computer vision applications, for example, sign language interpretation, human computer interaction, and gesture recognition. However, some serious bottlenecks still exist in hand localization systems such as fast hand motion capture, hand over face, and hand occlusions on which we focus in this paper. We present a novel method for hand tracking and segmentation based on augmented graph cuts and dynamic model. First, an effective dynamic model for state estimation is generated, which correctly predicts the location of hands probably having fast motion or shape deformations. Second, new energy terms are brought into the energy function to develop augmented graph cuts based on some cues, namely, spatial information, hand motion, and chamfer distance. The proposed method successfully achieves hand segmentation even though the hand passes over other skin-colored objects. Some challenging videos are provided in the case of hand over face, hand occlusions, dynamic background, and fast motion. Experimental results demonstrate that the proposed method is much more accurate than other graph cuts-based methods for hand tracking and segmentation. Jun Wan, Qiuqi Ruan, Gaoyun An, Wei Li, Yanyan Liang, and Ruizhen Zhao Copyright © 2014 Jun Wan et al. All rights reserved. Development and Analysis of Double-Faced Radial and Cluster-Arranged CMP Diamond Disk Sun, 31 Aug 2014 07:04:50 +0000 http://www.hindawi.com/journals/mpe/2014/913812/ In semiconductor manufacturing, diamond disks are indispensable for dressing chemical mechanical polishing (CMP) pads. Recently, 450 mm (18 inch) diameter wafers have been used to improve output and reduce wafer production cost. To polish 450 mm diameter wafers, the diameter of polishing pads must be increased to 1050 mm. In particular, because diamond disks are limited to 100 mm diameters, a much greater number of working crystals will be required for dressing a 1050 mm diameter pad. Consequently, new diamond disks must be developed. In this study, novel arrangements are made using a braze in diamond patterns, which are radial with a cluster arrangement of 3-4 grits per cluster. Furthermore, a double-faced combined diamond disk is developed. The polishing pad surface was characterized, and the effect of different diamond conditioners on wafer removal rate was studied. This research aims to develop a more suitable diamond disk for dressing 1050 mm diameter polishing pads. M. Y. Tsai, C. H. Chen, J. H. Chiang, and T. S. Yeh Copyright © 2014 M. Y. Tsai et al. All rights reserved. Topological Embedding Feature Based Resource Allocation in Network Virtualization Sun, 31 Aug 2014 07:01:17 +0000 http://www.hindawi.com/journals/mpe/2014/271493/ Virtualization provides a powerful way to run multiple virtual networks on a shared substrate network, which needs accurate and efficient mathematical models. Virtual network embedding is a challenge in network virtualization. In this paper, considering the degree of convergence when mapping a virtual network onto substrate network, we propose a new embedding algorithm based on topology mapping convergence-degree. Convergence-degree means the adjacent degree of virtual network’s nodes when they are mapped onto a substrate network. The contributions of our method are as below. Firstly, we map virtual nodes onto the substrate nodes with the maximum convergence-degree. The simulation results show that our proposed algorithm largely enhances the network utilization efficiency and decreases the complexity of the embedding problem. Secondly, we define the load balance rate to reflect the load balance of substrate links. The simulation results show our proposed algorithm achieves better load balance. Finally, based on the feature of star topology, we further improve our embedding algorithm and make it suitable for application in the star topology. The test result shows it gets better performance than previous works. Hongyan Cui, Shaohua Tang, Fangfang Sun, Yue Xu, and Xiaoli Yang Copyright © 2014 Hongyan Cui et al. All rights reserved. Stable Hovering Flight for a Small Unmanned Helicopter Using Fuzzy Control Sun, 31 Aug 2014 06:59:39 +0000 http://www.hindawi.com/journals/mpe/2014/208253/ Stable hover flight control for small unmanned helicopter under light air turbulent environment is presented. Intelligent fuzzy logic is chosen because it is a nonlinear control technique based on expert knowledge and is capable of handling sensor created noise and contradictory inputs commonly encountered in flight control. The fuzzy nonlinear control utilizes these distinct qualities for attitude, height, and position control. These multiple controls are developed using two-loop control structure by first designing an inner-loop controller for attitude angles and height and then by establishing outer-loop controller for helicopter position. The nonlinear small unmanned helicopter model used comes from X-Plane simulator. A simulation platform consisting of MATLAB/Simulink and X-Plane© flight simulator was introduced to implement the proposed controls. The main objective of this research is to design computationally intelligent control laws for hovering and to test and analyze this autopilot for small unmanned helicopter model on X-Plane under ideal and mild turbulent condition. Proposed fuzzy flight controls are validated using an X-Plane helicopter model before being embedded on actual helicopter. To show the effectiveness of the proposed fuzzy control method and its ability to cope with the external uncertainties, results are compared with a classical PD controller. Simulated results show that two-loop fuzzy controllers have a good ability to establish stable hovering for a class of unmanned rotorcraft in the presence of light turbulent environment. Arbab Nighat Khizer, Dai Yaping, Syed Amjad Ali, and Xu Xiangyang Copyright © 2014 Arbab Nighat Khizer et al. All rights reserved. On Perturbation Solutions for Axisymmetric Bending Boundary Values of a Deep Thin Spherical Shell Sun, 31 Aug 2014 05:27:54 +0000 http://www.hindawi.com/journals/mpe/2014/903861/ On the basis of the general theory of elastic thin shells and the Kirchhoff-Love hypothesis, a fundamental equation for a thin shell under the moment theory is established. In this study, the author derives Reissner’s equation with a transverse shear force and the displacement component . These basic unknown quantities are derived considering the axisymmetry of the deep, thin spherical shell and manage to constitute a boundary value question of axisymmetric bending of the deep thin spherical shell under boundary conditions. The asymptotic solution is obtained by the composite expansion method. At the end of this paper, to prove the correctness and accuracy of the derivation, an example is given to compare the numerical solution by ANSYS and the perturbation solution. Meanwhile, the effects of material and geometric parameters on the nonlinear response of axisymmetric deep thin spherical shell under uniform external pressure are also analyzed in this paper. Rong Xiao, Danhui Dan, and Wei Cheng Copyright © 2014 Rong Xiao et al. All rights reserved. An Automatic Decision-Making Mechanism for Virtual Machine Live Migration in Private Clouds Sun, 31 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/mpe/2014/328536/ Due to the increasing number of computer hosts deployed in an enterprise, automatic management of electronic applications is inevitable. To provide diverse services, there will be increases in procurement, maintenance, and electricity costs. Virtualization technology is getting popular in cloud computing environment, which enables the efficient use of computing resources and reduces the operating cost. In this paper, we present an automatic mechanism to consolidate virtual servers and shut down the idle physical machines during the off-peak hours, while activating more machines at peak times. Through the monitoring of system resources, heavy system loads can be evenly distributed over physical machines to achieve load balancing. By integrating the feature of load balancing with virtual machine live migration, we successfully develop an automatic private cloud management system. Experimental results demonstrate that, during the off-peak hours, we can save power consumption of about 69 W by consolidating the idle virtual servers. And the load balancing implementation has shown that two machines with 80% and 40% CPU loads can be uniformly balanced to 60% each. And, through the use of preallocated virtual machine images, the proposed mechanism can be easily applied to a large amount of physical machines. Ming-Tsung Kao, Yu-Hsin Cheng, and Shang-Juh Kao Copyright © 2014 Ming-Tsung Kao et al. All rights reserved. A Hybrid Metaheuristic-Based Approach for the Aerodynamic Optimization of Small Hybrid Wind Turbine Rotors Thu, 28 Aug 2014 13:02:41 +0000 http://www.hindawi.com/journals/mpe/2014/746319/ This work presents a novel framework for the aerodynamic design and optimization of blades for small horizontal axis wind turbines (WT). The framework is based on a state-of-the-art blade element momentum model, which is complemented with the XFOIL 6.96 software in order to provide an estimate of the sectional blade aerodynamics. The framework considers an innovative nested-hybrid solution procedure based on two metaheuristics, the virtual gene genetic algorithm and the simulated annealing algorithm, to provide a near-optimal solution to the problem. The objective of the study is to maximize the aerodynamic efficiency of small WT (SWT) rotors for a wide range of operational conditions. The design variables are (1) the airfoil shape at the different blade span positions and the radial variation of the geometrical variables of (2) chord length, (3) twist angle, and (4) thickness along the blade span. A wind tunnel validation study of optimized rotors based on the NACA 4-digit airfoil series is presented. Based on the experimental data, improvements in terms of the aerodynamic efficiency, the cut-in wind speed, and the amount of material used during the manufacturing process were achieved. Recommendations for the aerodynamic design of SWT rotors are provided based on field experience. José F. Herbert-Acero, Jaime Martínez-Lauranchet, Oliver Probst, Santos Méndez-Díaz, Krystel K. Castillo-Villar, Manuel Valenzuela-Rendón, and Pierre-Elouan Réthoré Copyright © 2014 José F. Herbert-Acero et al. All rights reserved. Quantum Behaved Particle Swarm Optimization Algorithm Based on Artificial Fish Swarm Thu, 28 Aug 2014 11:36:43 +0000 http://www.hindawi.com/journals/mpe/2014/592682/ Quantum behaved particle swarm algorithm is a new intelligent optimization algorithm; the algorithm has less parameters and is easily implemented. In view of the existing quantum behaved particle swarm optimization algorithm for the premature convergence problem, put forward a quantum particle swarm optimization algorithm based on artificial fish swarm. The new algorithm based on quantum behaved particle swarm algorithm, introducing the swarm and following activities, meanwhile using the adaptive parameters, to avoid it falling into local extremum of population. The experimental results show the improved algorithm to improve the optimization ability of the algorithm. Dong Yumin and Zhao Li Copyright © 2014 Dong Yumin and Zhao Li. All rights reserved. Dictionary-Based Image Denoising by Fused-Lasso Atom Selection Thu, 28 Aug 2014 11:34:01 +0000 http://www.hindawi.com/journals/mpe/2014/368602/ We proposed an efficient image denoising scheme by fused lasso with dictionary learning. The scheme has two important contributions. The first one is that we learned the patch-based adaptive dictionary by principal component analysis (PCA) with clustering the image into many subsets, which can better preserve the local geometric structure. The second one is that we coded the patches in each subset by fused lasso with the clustering learned dictionary and proposed an iterative Split Bregman to solve it rapidly. We present the capabilities with several experiments. The results show that the proposed scheme is competitive to some excellent denoising algorithms. Ao Li and Hayaru Shouno Copyright © 2014 Ao Li and Hayaru Shouno. All rights reserved. Research of Ant Colony Optimized Adaptive Control Strategy for Hybrid Electric Vehicle Thu, 28 Aug 2014 09:38:55 +0000 http://www.hindawi.com/journals/mpe/2014/239130/ Energy management control strategy of hybrid electric vehicle has a great influence on the vehicle fuel consumption with electric motors adding to the traditional vehicle power system. As vehicle real driving cycles seem to be uncertain, the dynamic driving cycles will have an impact on control strategy’s energy-saving effect. In order to better adapt the dynamic driving cycles, control strategy should have the ability to recognize the real-time driving cycle and adaptively adjust to the corresponding off-line optimal control parameters. In this paper, four types of representative driving cycles are constructed based on the actual vehicle operating data, and a fuzzy driving cycle recognition algorithm is proposed for online recognizing the type of actual driving cycle. Then, based on the equivalent fuel consumption minimization strategy, an ant colony optimization algorithm is utilized to search the optimal control parameters “charge and discharge equivalent factors” for each type of representative driving cycle. At last, the simulation experiments are conducted to verify the accuracy of the proposed fuzzy recognition algorithm and the validity of the designed control strategy optimization method. Linhui Li, Haiyang Huang, Jing Lian, Baozhen Yao, Yafu Zhou, Jing Chang, and Ning’an Zheng Copyright © 2014 Linhui Li et al. All rights reserved. Erratum to “Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring” Thu, 28 Aug 2014 08:45:14 +0000 http://www.hindawi.com/journals/mpe/2014/608179/ Zheng Zuo, Yu Hu, Qingbin Li, and Liyuan Zhang Copyright © 2014 Zheng Zuo et al. All rights reserved. Workload-Aware and CPU Frequency Scaling for Optimal Energy Consumption in VM Allocation Thu, 28 Aug 2014 08:42:53 +0000 http://www.hindawi.com/journals/mpe/2014/906098/ In the problem of VMs consolidation for cloud energy saving, different workloads will ask for different resources. Thus, considering workload characteristic, the VM placement solution will be more reasonable. In the real world, different workload works in a varied CPU utilization during its work time according to its task characteristics. That means energy consumption related to both the CPU utilization and CPU frequency. Therefore, only using the model of CPU frequency to evaluate energy consumption is insufficient. This paper theoretically verified that there will be a CPU frequency best suit for a certain CPU utilization in order to obtain the minimum energy consumption. According to this deduction, we put forward a heuristic CPU frequency scaling algorithm VP-FS (virtual machine placement with frequency scaling). In order to carry the experiments, we realized three typical greedy algorithms for VMs placement and simulate three groups of VM tasks. Our efforts show that different workloads will affect VMs allocation results. Each group of workload has its most suitable algorithm when considering the minimum used physical machines. And because of the CPU frequency scaling, VP-FS has the best results on the total energy consumption compared with the other three algorithms under any of the three groups of workloads. Zhen Liu, Yongchao Xiang, and Xiaoya Qu Copyright © 2014 Zhen Liu et al. All rights reserved.