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  • Articles  (9,573)
  • 2010-2014  (9,573)
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  • 1
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    Identification of Protein Pupylation Sites Using Bi-Profile Bayes Feature Extraction and Ensemble Learning (2013)
    Hindawi
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    Publication Date: 2013-09-10
    Description: Pupylation, one of the most important posttranslational modifications of proteins, typically takes place when prokaryotic ubiquitin-like protein (Pup) is attached to specific lysine residues on a target protein. Identification of pupylation substrates and their corresponding sites will facilitate the understanding of the molecular mechanism of pupylation. Comparing with the labor-intensive and time-consuming experiment approaches, computational prediction of pupylation sites is much desirable for their convenience and fast speed. In this study, a new bioinformatics tool named EnsemblePup was developed that used an ensemble of support vector machine classifiers to predict pupylation sites. The highlight of EnsemblePup was to utilize the Bi-profile Bayes feature extraction as the encoding scheme. The performance of EnsemblePup was measured with a sensitivity of 79.49%, a specificity of 82.35%, an accuracy of 85.43%, and a Matthews correlation coefficient of 0.617 using the 5-fold cross validation on the training dataset. When compared with other existing methods on a benchmark dataset, the EnsemblePup provided better predictive performance, with a sensitivity of 80.00%, a specificity of 83.33%, an accuracy of 82.00%, and a Matthews correlation coefficient of 0.629. The experimental results suggested that EnsemblePup presented here might be useful to identify and annotate potential pupylation sites in proteins of interest. A web server for predicting pupylation sites was developed.
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  • 2
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    Partial Refactorization in Sparse Matrix Solution: A New Possibility for Faster Nonlinear Finite Element Analysis (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: This paper proposes a partial refactorization for faster nonlinear analysis based on sparse matrix solution, which is nowadays the default solution choice in finite element analysis and can solve finite element models up to millions degrees of freedom. Among various fill-in’s reducing strategies for sparse matrix solution, the graph partition is in general the best in terms of resultant fill-ins and floating-point operations and furthermore produces a particular graph of sparse matrix that prevents local change of entries from wide spreading in factorization. Based on this feature, an explicit partial triangular refactorization with local change is efficiently constructed with limited additional storage requirement in row-sparse storage scheme. The partial refactorization of the changed stiffness matrix inherits a big percentage of the original factor and is carried out only on partial factor entries. The proposed method provides a new possibility for faster nonlinear analysis and is mainly suitable for material nonlinear problems and optimization problems. Compared to full factorization, it can significantly reduce the factorization time and can make nonlinear analysis more efficient.
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  • 3
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    A Novel Framework Based on ACO and PSO for RNA Secondary Structure Prediction (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: Prediction of RNA structure is a useful process for creating new drugs and understanding genetic diseases. In this paper, we proposed a particle swarm optimization (PSO) and ant colony optimization (ACO) based framework (PAF) for RNA secondary structure prediction. PAF consists of crucial stem searching (CSS) and global sequence building (GSB). In CSS, a modified ACO (MACO) is used to search the crucial stems, and then a set of stems are generated. In GSB, we used a modified PSO (MPSO) to construct all the stems in one sequence. We evaluated the performance of PAF on ten sequences, which have length from 122 to 1494. We also compared the performance of PAF with the results obtained from six existing well-known methods, SARNA-Predict, RnaPredict, ACRNA, PSOfold, IPSO, and mfold. The comparison results show that PAF could not only predict structures with higher accuracy rate but also find crucial stems.
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  • 4
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    A Virtual Channels Scheduling Algorithm with Broad Applicability Based on Movable Boundary (2013)
    Hindawi
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    Publication Date: 2013-09-13
    Description: A virtual channels scheduling algorithm with broad applicability based on movable boundary is proposed. According to the types of date sources, transmission time slots are divided into synchronous ones and asynchronous ones with a movable boundary between them. During the synchronous time slots, the virtual channels are scheduled with a polling algorithm; during the asynchronous time slots, the virtual channels are scheduled with an algorithm based on virtual channel urgency and frame urgency. If there are no valid frames in the corresponding VC at a certain synchronous time slot, a frame of the other synchronous VCs or asynchronous VCs will be transmitted through the physical channel. Only when there are no valid frames in all VCs would an idle frame be generated and transmitted. Experiments show that the proposed algorithm yields much lower scheduling delay and higher channel utilization ratio than those based on unmovable boundary or virtual channel urgency in many kinds of sources. Therefore, broad applicability can be achieved by the proposed algorithm.
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  • 5
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    An Adaptive Unscented Particle Filter Algorithm through Relative Entropy for Mobile Robot Self-Localization (2013)
    Hindawi
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    Publication Date: 2013-09-13
    Description: Self-localization is a basic skill for mobile robots in the dynamic environments. It is usually modeled as a state estimation problem for nonlinear system with non-Gaussian noise and needs the real-time processing. Unscented particle filter (UPF) can handle the state estimation problem for nonlinear system with non-Gaussian noise; however the computation of UPF is very high. In order to reduce the computation cost of UPF and meanwhile maintain the accuracy, we propose an adaptive unscented particle filter (AUPF) algorithm through relative entropy. AUPF can adaptively adjust the number of particles during filtering to reduce the necessary computation and hence improve the real-time capability of UPF. In AUPF, the relative entropy is used to measure the distance between the empirical distribution and the true posterior distribution. The least number of particles for the next step is then decided according to the relative entropy. In order to offset the difference between the proposal distribution, and the true distribution the least number is adjusted thereafter. The ideal performance of AUPF in real robot self-localization is demonstrated.
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  • 6
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    A New Method for Parameter Sensitivity Analysis of Lorenz Equations (2013)
    Hindawi
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    Publication Date: 2013-09-17
    Description: A new method for parameter sensitivity analysis of Lorenz equations is presented. The sensitivity equations are derived based on the staggered methods. Experimental results indicate that it is possible to determine effects of parameters on model variables so that we can eliminate the less effective ones. Robustness can also be verified in some confidence intervals by simply looking at the corresponding phase portraits. This enables us to control the system. Although the stability properties of the Lorenz equations are studied extensively, to the best knowledge of the authors, the PSA of Lorenz equations has not been considered which is the main goal of this paper.
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  • 7
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    New Developments in Time-Delay Systems and Its Applications in Engineering (2013)
    Hindawi
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    Publication Date: 2013-09-17
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  • 8
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    Online Identification of Multivariable Discrete Time Delay Systems Using a Recursive Least Square Algorithm (2013)
    Hindawi
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    Publication Date: 2013-09-17
    Description: This paper addresses the problem of simultaneous identification of linear discrete time delay multivariable systems. This problem involves both the estimation of the time delays and the dynamic parameters matrices. In fact, we suggest a new formulation of this problem allowing defining the time delay and the dynamic parameters in the same estimated vector and building the corresponding observation vector. Then, we use this formulation to propose a new method to identify the time delays and the parameters of these systems using the least square approach. Convergence conditions and statistics properties of the proposed method are also developed. Simulation results are presented to illustrate the performance of the proposed method. An application of the developed approach to compact disc player arm is also suggested in order to validate simulation results.
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  • 9
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    Analytical Solution of Flow and Heat Transfer over a Permeable Stretching Wall in a Porous Medium (2013)
    Hindawi
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    Publication Date: 2013-09-17
    Description: Boundary layer flow through a porous medium over a stretching porous wall has seen solved with analytical solution. It has been considered two wall boundary conditions which are power-law distribution of either wall temperature or heat flux. These are general enough to cover the isothermal and isoflux cases. In addition to momentum, both first and second laws of thermodynamics analyses of the problem are investigated. The governing equations are transformed into a system of ordinary differential equations. The transformed ordinary equations are solved analytically using homotopy analysis method. A comprehensive parametric study is presented, and it is shown that the rate of heat transfer increases with Reynolds number, Prandtl number, and suction to the surface.
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  • 10
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    Assessment of Prestress Force in Bridges Using Structural Dynamic Responses under Moving Vehicles (2013)
    Hindawi
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    Publication Date: 2013-09-17
    Description: This study carries out numerical simulations to identify the magnitude of prestress force in a highway bridge by making use of the dynamic responses from moving vehicular loads. The prestressed bridges are modeled using four-node isoparametric flat shell element taking into account the transverse shearing deformation in the finite element model. The vehicle is modeled as a multiple degrees-of-freedom system. An approach based on dynamic response sensitivity-based finite element model updating is proposed to identify the elemental prestress force. The identified results are obtained iteratively with the penalty function method with regularization from the measured structural dynamic responses. A single-span prestressed Tee beam and two-span prestressed box-girder bridge are studied as two numerical examples. The effects of road surface roughness, measurement noise, and speed of moving vehicle on the identification results are investigated. Studies indicate that the proposed method is efficient and robust for prestress force identification. Good identified results can be obtained from several measured acceleration responses.
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  • 11
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    Study on the Explicit Formula of the Triangular Flat Shell Element Based on the Analytical Trial Functions for Anisotropy Material (2013)
    Hindawi
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    Publication Date: 2013-09-17
    Description: This paper presents a novel way to formulate the triangular flat shell element. The basic analytical solutions of membrane and bending plate problem for anisotropy material are studied separately. Combining with the conforming displacement along the sides and hybrid element strategy, the triangular flat shell elements based on the analytical trial functions (ATF) for anisotropy material are formulated. By using the explicit integral formulae of the triangular element, the matrices used in proposed shell element are calculated efficiently. The benchmark examples showed the high accuracy and high efficiency.
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  • 12
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    Numerical and Soft Computing Methods for Characteristic Value Problems of ODE and ODEs Systems (2013)
    Hindawi
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    Publication Date: 2013-09-17
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  • 13
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    Mathematical Modeling of Heat and Mass Transfer in Energy Science and Engineering (2013)
    Hindawi
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    Publication Date: 2013-09-17
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  • 14
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    Multiple Model Adaptive Nonlinear Observer of Dynamic Positioning Ship (2013)
    Hindawi
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    Publication Date: 2013-09-17
    Description: Considering the filtering problem of dynamic positioning (DP) ship for the slowly varying sea state, a multiple model adaptive observer (MMAO) for dynamic positioning ship is presented. The MMAO consists of a bank of nonlinear subobserver and a dynamic weighting signal generator, in which each sub-observer is designed based on different peak frequency of wave spectrum model. To improve the performance of the observer, subobserver using the measurement of position, velocity, and acceleration is used to update the estimated velocity of ship. The observer parameters are optimized using particle swarm optimization (PSO). Finally, the method is verified effective by the computer simulation.
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  • 15
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    The Extrapolation-Accelerated Multilevel Aggregation Method in PageRank Computation (2013)
    Hindawi
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    Publication Date: 2013-09-18
    Description: An accelerated multilevel aggregation method is presented for calculating the stationary probability vector of an irreducible stochastic matrix in PageRank computation, where the vector extrapolation method is its accelerator. We show how to periodically combine the extrapolation method together with the multilevel aggregation method on the finest level for speeding up the PageRank computation. Detailed numerical results are given to illustrate the behavior of this method, and comparisons with the typical methods are also made.
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  • 16
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    A New Numerical Approach of MHD Flow with Heat and Mass Transfer for the UCM Fluid over a Stretching Surface in the Presence of Thermal Radiation (2013)
    Hindawi
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    Publication Date: 2013-09-18
    Description: This paper numerically investigates the magnetohydrodynamic boundary layer flow with heat and mass transfer of an incompressible upper-convected Maxwell fluid over a stretching sheet in the presence of viscous dissipation and thermal radiation as well as chemical reaction. The governing partial differential equations are transformed into a system of ordinary differential equations by using suitable similarity transformations. The resultant highly nonlinear ordinary differential equations are then solved using spectral relaxation method. The results are obtained for velocity, temperature, concentration, skin friction, and Nusselt number. The effects of various material parameters on the flow with heat and mass transfer and the dimensionless variables are illustrated graphically and briefly discussed.
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  • 17
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    LGMS-FOA: An Improved Fruit Fly Optimization Algorithm for Solving Optimization Problems (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: Recently, a new fruit fly optimization algorithm (FOA) is proposed to solve optimization problems. In this paper, we empirically study the performance of FOA. Six different nonlinear functions are selected as testing functions. The experimental results illustrate that FOA cannot solve complex optimization problems effectively. In order to enhance the performance of FOA, an improved FOA (named LGMS-FOA) is proposed. Simulation results and comparisons of LGMS-FOA with FOA and other metaheuristics show that LGMS-FOA can greatly enhance the searching efficiency and greatly improve the searching quality.
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  • 18
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    Coupled Hydromechanical Model of Two-Phase Fluid Flow in Deformable Porous Media (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: A model of solid-water-air coupling in triphasic mixtures is compared with solid-water coupling in biphasic mixtures with an application to partially saturated porous media. Based on thermodynamics, the mathematical framework governing the behavior of a partially saturated soil is derived using balance equations, and the numerical implementation and drainage tests of a soil column are carried out to validate the obtained formulations. The role of the air phase in the hydro-mechanical behavior of triphasic mixtures can be analyzed from the interactions among multiple phases for the constitutive behavior of a solid skeleton, and the triphasic mixture model can be applied in geotechnical engineering problems, such as sequestration and air storage in aquifers.
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  • 19
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    A Multiobjective Optimization Model in Automotive Supply Chain Networks (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: In the new decade, green investment decisions are attracting more interest in design supply chains due to the hidden economic benefits and environmental legislative barriers. In this paper, a supply chain network design problem with both economic and environmental concerns is presented. Therefore, a multiobjective optimization model that captures the trade-off between the total logistics cost and CO2 emissions is proposed. With regard to the complexity of logistic networks, a new multiobjective swarm intelligence algorithm known as a multiobjective Gravitational search algorithm (MOGSA) has been implemented for solving the proposed mathematical model. To evaluate the effectiveness of the model, a comprehensive set of numerical experiments is explained. The results obtained show that the proposed model can be applied as an effective tool in strategic planning for optimizing cost and CO2 emissions in an environmentally friendly automotive supply chain.
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    Sampled-Data Control of Spacecraft Rendezvous with Discontinuous Lyapunov Approach (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: This paper investigates the sampled-data stabilization problem of spacecraft relative positional holding with improved Lyapunov function approach. The classical Clohessy-Wiltshire equation is adopted to describe the relative dynamic model. The relative position holding problem is converted into an output tracking control problem using sampling signals. A time-dependent discontinuous Lyapunov functionals approach is developed, which will lead to essentially less conservative results for the stability analysis and controller design of the corresponding closed-loop system. Sufficient conditions for the exponential stability analysis and the existence of the proposed controller are provided, respectively. Finally, a simulation result is established to illustrate the effectiveness of the proposed control scheme.
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    An Analytical Framework of a Deployment Strategy for Cloud Computing Services: A Case Study of Academic Websites (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: Cloud computing has become a popular topic for exploration in both academic and industrial research in recent years. In this paper, network behavior is analyzed to assess and compare the costs and risks associated with traditional local servers versus those associated with cloud computing to determine the appropriate deployment strategy. An analytic framework of a deployment strategy that involves two mathematical models and the analytical hierarchy process is proposed to analyze the costs and service level agreements of services involving using traditional local servers and platform as service platforms in the cloud. Two websites are used as test sites to analyze the costs and risks of deploying services in Google App Engine (GAE) (1) the website of Information and Finance of Management (IFM) at the National Chiao Tung University (NCTU) and (2) the NCTU website. If the examined websites were deployed in GAE, NCTU would save over 83.34% of the costs associated with using a traditional local server with low risk. Therefore, both the IFM and NCTU websites can be served appropriately in the cloud. Based on this strategy, a suggestion is proposed for managers and professionals.
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    An Efficient Mesh Generation Method for Fractured Network System Based on Dynamic Grid Deformation (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: Meshing quality of the discrete model influences the accuracy, convergence, and efficiency of the solution for fractured network system in geological problem. However, modeling and meshing of such a fractured network system are usually tedious and difficult due to geometric complexity of the computational domain induced by existence and extension of fractures. The traditional meshing method to deal with fractures usually involves boundary recovery operation based on topological transformation, which relies on many complicated techniques and skills. This paper presents an alternative and efficient approach for meshing fractured network system. The method firstly presets points on fractures and then performs Delaunay triangulation to obtain preliminary mesh by point-by-point centroid insertion algorithm. Then the fractures are exactly recovered by local correction with revised dynamic grid deformation approach. Smoothing algorithm is finally applied to improve the quality of mesh. The proposed approach is efficient, easy to implement, and applicable to the cases of initial existing fractures and extension of fractures. The method is successfully applied to modeling of two- and three-dimensional discrete fractured network (DFN) system in geological problems to demonstrate its effectiveness and high efficiency.
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    Pricing Models of e-Books When Competing with p-Books (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: With the rise in popularity of e-books, there is a growing need to reexamine the pricing strategy in the e-book supply chain. In this paper, we study two forms of pricing models widely used in the book industry: wholesale and agency pricing models. We first assume a stylized deterministic demand model in which the demand depends on the price, the degree of substitution, and the overall market potential. Subsequently, we employ the game theory to determine the price equilibriums and profit distribution under different pricing models. Finally, we explore the behavior of the publisher and the retailer under different preferences and degrees of substitution through a computational study. Our findings indicate that the e-book price will be lower under the agency pricing model than under the wholesale pricing model, which is counterintuitive. The publishers have higher incentives to adopt the agency pricing model than the wholesale pricing model. The agency pricing model benefits the whole system and can provide readers with books at lower prices. The degree of substitution between the two forms of books and the readers’ preference toward e-book will affect the books’ price and the profit distribution between the publisher and the retailers.
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    Numerical Simulation of Transient Free Convection Flow and Heat Transfer in a Porous Medium (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: The coupled momentum and heat transfer in unsteady, incompressible flow along a semi-infinite vertical porous moving plate adjacent to an isotropic porous medium with viscous dissipation effect are investigated. The Darcy-Forchheimer nonlinear drag force model which includes the effects of inertia drag forces is employed. The governing differential equations of the problem are transformed into a system of nondimensional differential equations which are solved numerically by the finite element method (FEM). The non-dimensional velocity and temperature profiles are presented for the influence of Darcy number, Forchheimer number, Grashof number, Eckert number, Prandtl number, plate velocity, and time. The Nusselt number is also evaluated and compared with finite difference method (FDM), which shows excellent agreement.
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    Influence Mechanism of Grouting on Mechanical Characteristics of Rock Mass (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: Grouting technology has been widely used in all fields of geotechnical and civil engineering. Prospective engineering objectives including reinforcement of rock mass and groundwater leakage treatment can be achieved by grouting which will change the mechanical parameters of rock mass such as strength, elastic modulus, and coefficient of permeability. In this paper, rock mass is assumed as a composite material consisting of rock particles and random microcracks initially. Since part or all of the cracks will be filled with cement slurry after grouting, rock mass consists of rock particles, grout condensate, and some or no random microcracks after grouting. The damage constitutional law of the mesoscopic element is established based on the theory of mesoscopic damage mechanics. With the heterogeneity of the components of rock mass considered, the variation of mechanical characteristics of rock mass is studied before and after grouting. And the influence mechanism of grouting on rock mass is investigated at mesoscale level.
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    An Integral Equations Method for the Cauchy Problem Connected with the Helmholtz Equation (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: We are concerned with the Cauchy problem connected with the Helmholtz equation. We propose a numerical method, which is based on the Helmholtz representation, for obtaining an approximate solution to the problem, and then we analyze the convergence and stability with a suitable choice of regularization method. Numerical experiments are also presented to show the effectiveness of our method.
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    Observer-Based Robust Tracking Control for a Class of Switched Nonlinear Cascade Systems (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: This paper is devoted to robust output feedback tracking control design for a class of switched nonlinear cascade systems. The main goal is to ensure the global input-to-state stable (ISS) property of the tracking error nonlinear dynamics with respect to the unknown structural system uncertainties and external disturbances. First, a nonlinear observer is constructed through state transformation to reconstruct the unavailable states, where only one parameter should be determined. Then, by virtue of the nonlinear sliding mode control (SMC), a discontinuous nonlinear output feedback controller is designed using a backstepping like design procedure to ensure the ISS property. Finally, an example is provided to show the effectiveness of the proposed approach.
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    A Kinetic Model for Predicting the Relative Humidity in Modified Atmosphere Packaging and Its Application in Lentinula edodes Packages (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: Adjusting and controlling the relative humidity (RH) inside package is crucial for ensuring the quality of modified atmosphere packaging (MAP) of fresh produce. In this paper, an improved kinetic model for predicting the RH in MAP was developed. The model was based on heat exchange and gases mass transport phenomena across the package, gases heat convection inside the package, and mass and heat balances accounting for the respiration and transpiration behavior of fresh produce. Then the model was applied to predict the RH in MAP of fresh Lentinula edodes (one kind of Chinese mushroom). The model equations were solved numerically using Adams-Moulton method to predict the RH in model packages. In general, the model predictions agreed well with the experimental data, except that the model predictions were slightly high in the initial period. The effect of the initial gas composition on the RH in packages was notable. In MAP of lower oxygen and higher carbon dioxide concentrations, the ascending rate of the RH was reduced, and the RH inside packages was saturated slowly during storage. The influence of the initial gas composition on the temperature inside package was not much notable.
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    Analytical and Semianalytical Treatment of the Collinear Points in the Photogravitational Relativistic RTBP (2013)
    Hindawi
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    Publication Date: 2013-09-23
    Description: The problem of restricted three bodies is considered. The treatment is carried out within the framework of the post-Newtonian approximation. The primaries also are assumed to be radiant sources. The locations of the collinear points are computed. Series forms of these locations are obtained as new results. A Mathematica program is constructed so as to draw the locations of collinear points versus the whole range of the mass ratio taking into account the photo-gravitational effects and/or the relativistic corrections. Analyses of these figures are addressed.
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    Active Tension Control for WT Wheelchair Robot by Using a Novel Control Law for Holonomic or Nonholonomic Systems (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: Interactional characteristics between WT wheelchair robot and stair environment are analyzed, and possible patterns of WT wheelchair robot during the stair-climbing process are summarized, with the criteria of the wheelchair robot for determining the pattern proposed. Aiming at WT wheelchair robot's complicated mechanism with holonomic constraints and combined with the computed torque method, a novel control law that is called active tension control is presented for holonomic or nonholonomic robotic systems, by which the wheelchair robot with a holonomic or nonholonomic mechanism can track the reference input of the constraint forces of holonomic or nonholonomic constraints as well as tracking the reference input of the generalized coordinate of each joint. A stateflow module of Matlab is used to simulate the entire stair-climbing process for WT wheelchair robot. A comparison of output curve with the reference input curve of each joint is made, with the effectiveness of the presented control law verified.
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    Synchronization of Complex Dynamical Networks with Nonidentical Nodes and Derivative Coupling via Distributed Adaptive Control (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: Adaptive synchronization control is proposed for a new complex dynamical network model with nonidentical nodes and nonderivative and derivative couplings. The distributed adaptive learning laws of periodically time-varying and constant parameters and distributed adaptive control are designed. The new method which can obtain the synchronization error of closed-loop complex network system is asymptotic convergence in the sense of square error norm. What is more, the coupling matrix is not assumed to be symmetric or irreducible. Finally, a simulation example shows the feasibility and effectiveness of the approach.
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    Study on Seismic Control of Power Transmission Tower-Line Coupled System under Multicomponent Excitations (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: The seismic control of power transmission tower-line coupled system subjected to multicomponent excitations is studied in this paper. The schematic of tuned mass damper is introduced, and equations of motion of a system with tuned mass damper under multi-component excitations are proposed. Three-dimensional finite tower-line system models are created based on practical engineering in studying the response of this system without and with control. The time domain analysis takes into account geometric nonlinearity due to finite deformation. The optimal design of the transmission tower-line system with tuned mass damper is obtained according to different mass ratio. The effects of wave travel, coherency loss, and different site conditions on the system without and with control are investigated, respectively.
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    Content-Based Image Retrial Based on Hadoop (2013)
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    Publication Date: 2013-09-30
    Description: Generally, time complexity of algorithms for content-based image retrial is extremely high. In order to retrieve images on large-scale databases efficiently, a new way for retrieving based on Hadoop distributed framework is proposed. Firstly, a database of images features is built by using Speeded Up Robust Features algorithm and Locality-Sensitive Hashing and then perform the search on Hadoop platform in a parallel way specially designed. Considerable experimental results show that it is able to retrieve images based on content on large-scale cluster and image sets effectively.
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    Vibration Suppression of an Axially Moving String with Transverse Wind Loadings by a Nonlinear Energy Sink (2013)
    Hindawi
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    Publication Date: 2013-09-29
    Description: Nonlinear targeted energy transfer (TET) is applied to suppress the excessive vibration of an axially moving string with transverse wind loads. The coupling dynamic equations used are modeled by a nonlinear energy sink (NES) attached to the string to absorb vibrational energy. By a two-term Galerkin procedure, the equations are discretized, and the effects of vibration suppression by numerical methods are demonstrated. Results show that the NES can effectively suppress the vibration of the axially moving string with transverse wind loadings, thereby protecting the string from excessive movement.
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    A Parameter Matching Method of the Parallel Hydraulic Hybrid Excavator Optimized with Genetic Algorithm (2013)
    Hindawi
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    Publication Date: 2013-09-29
    Description: This paper proposed a parameter matching method based on the energy storage unit, the accumulator in the parallel hydraulic hybrid excavator (PHHE). The working condition, system structure, and control strategy of the excavator were all considered. It took the 20-ton series PHHE as the example and displayed the parameter matching course of the main components: engine, accumulator, and hydraulic secondary regulatory pump. Their installed powers were reduced after the matching course. Furthermore, the parameters of the PHHE system were optimized with the genetic algorithm to get the most suitable values for system initialization. By analyzing the simulation results, it could be concluded that the parameter matching method had an impressive improvement of the energy saving under the same working condition and brought obscure influence to the mechanism dynamics.
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    Coordinated Control for a Group of Interconnected Pairwise Subsystems (2013)
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    Publication Date: 2013-09-29
    Description: The implementation of pairwise decomposition is discussed on an interconnected system with uncertainties. Under the concept of system inclusion, two systems with the same expanded system achieved by the same expand transformation are considered as approximations. It is proven that a coordinated controller can be found to stabilize both the two systems. This controller is contracted from the coordinated controller of expanded system, with each pairwise subsystem having information structure constraint taken into consideration. At last, this controller design process is applied on a four-area power system treated as a group of subsystems with information structure constraints.
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    Using Software Dependency to Bug Prediction (2013)
    Hindawi
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    Publication Date: 2013-10-02
    Description: Software maintenance, especially bug prediction, plays an important role in evaluating software quality and balancing development costs. This study attempts to use several quantitative network metrics to explore their relationships with bug prediction in terms of software dependency. Our work consists of four main steps. First, we constructed software dependency networks regarding five dependency scenes at the class-level granularity. Second, we used a set of nine representative and commonly used metrics—namely, centrality, degree, PageRank, and HITS, as well as modularity—to quantify the importance of each class. Third, we identified how these metrics were related to the proneness and severity of fixed bugs in Tomcat and Ant and determined the extent to which they were related. Finally, the significant metrics were considered as predictors for bug proneness and severity. The result suggests that there is a statistically significant relationship between class’s importance and bug prediction. Furthermore, betweenness centrality and out-degree metric yield an impressive accuracy for bug prediction and test prioritization. The best accuracy of our prediction for bug proneness and bug severity is up to 54.7% and 66.7% (top 50, Tomcat) and 63.8% and 48.7% (top 100, Ant), respectively, within these two cases.
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    Applications of Discontinuous Galerkin Finite Element Method in Thermomechanical Coupling Problems with Imperfect Thermal Contact (2013)
    Hindawi
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    Publication Date: 2013-10-02
    Description: Thermomechanical coupling problems with imperfect thermal contact are analyzed in the present paper with discontinuous Galerkin finite element method. The imperfect thermal contact condition is characterized by thermal contact resistance. The whole thermomechanical coupling problem is solved alternatively with the thermal subproblem and mechanical subproblem. Thermal contact resistance is introduced directly with the interface numerical flux of the present discontinuous Galerkin finite element method without using interface element as traditional continuous Galerkin finite element method does. Numerical results show the accuracy and feasibility of the present discontinuous Galerkin finite element method in solving thermomechanical coupling problems with imperfect thermal contact.
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    Unsteady Analyses of a Control Valve due to Fluid-Structure Coupling (2013)
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    Publication Date: 2013-10-02
    Description: Control valves play important roles in the control of the mixed-gas pressure in the combined cycle power plants (CCPP). In order to clarify the influence of coupling between the structure and the fluid system at the control valve, the coupling mechanism was presented, and the numerical investigations were carried out. At the same operating condition in which the pressure oscillation amplitude is greater when considering the coupling, the low-order natural frequencies of the plug assembly of the valve decrease obviously when considering the fluid-structure coupling action. The low-order natural frequencies at 25% valve opening, 50% valve opening, and 75% valve opening are reduced by 11.1%, 7.0%, and 3.8%, respectively. The results help understand the processes that occur in the valve flow path leading to the pressure control instability observed in the control valve in the CCPP.
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    A Multilayer Hidden Markov Models-Based Method for Human-Robot Interaction (2013)
    Hindawi
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    Publication Date: 2013-10-02
    Description: To achieve Human-Robot Interaction (HRI) by using gestures, a continuous gesture recognition approach based on Multilayer Hidden Markov Models (MHMMs) is proposed, which consists of two parts. One part is gesture spotting and segment module, the other part is continuous gesture recognition module. Firstly, a Kinect sensor is used to capture 3D acceleration and 3D angular velocity data of hand gestures. And then, a Feed-forward Neural Networks (FNNs) and a threshold criterion are used for gesture spotting and segment, respectively. Afterwards, the segmented gesture signals are respectively preprocessed and vector symbolized by a sliding window and a K-means clustering method. Finally, symbolized data are sent into Lower Hidden Markov Models (LHMMs) to identify individual gestures, and then, a Bayesian filter with sequential constraints among gestures in Upper Hidden Markov Models (UHMMs) is used to correct recognition errors created in LHMMs. Five predefined gestures are used to interact with a Kinect mobile robot in experiments. The experimental results show that the proposed method not only has good effectiveness and accuracy, but also has favorable real-time performance.
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    Global Exponential Stability of a Unique Almost Periodic Solution for Neutral-Type Cohen-Grossberg Neural Networks with Time Delays (2013)
    Hindawi
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    Publication Date: 2013-10-03
    Description: This paper is concerned with the problem of the existence, uniqueness, and global exponential stability of almost periodic solution for neutral-type Cohen-Grossberg neural networks with time delays. Based on fixed point theory and Lyapunov functional, several sufficient conditions are established for the existence, uniqueness, and global exponential stability of almost periodic solution for the above system. Finally, an example and numerical simulations are given to illustrate the feasibility and effectiveness of our main results.
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    Attitude Control of a Single Tilt Tri-Rotor UAV System: Dynamic Modeling and Each Channel's Nonlinear Controllers Design (2013)
    Hindawi
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    Publication Date: 2013-10-03
    Description: This paper has implemented nonlinear control strategy for the single tilt tri-rotor aerial robot. Based on Newton-Euler’s laws, the linear and nonlinear mathematical models of tri-rotor UAVs are obtained. A numerical analysis using Newton-Raphson method is chosen for finding hovering equilibrium point. Back-stepping nonlinear controller design is based on constructing Lyapunov candidate function for closed-loop system. By imitating the linguistic logic of human thought, fuzzy logic controllers (FLCs) are designed based on control rules and membership functions, which are much less rigid than the calculations computers generally perform. Effectiveness of the controllers design scheme is shown through nonlinear simulation model on each channel.
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    Golden Ratio Phenomenon of Random Data Obeying von Karman Spectrum (2013)
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    Publication Date: 2013-10-03
    Description: von Karman originally deduced his spectrum of wind speed fluctuation based on the Stokes-Navier equation. Taking into account, the practical issues of measurement and/or computation errors, we suggest that the spectrum can be described from the point of view of the golden ratio. We call it the golden ratio phenomenon of the von Karman spectrum. To depict that phenomenon, we derive the von Karman spectrum based on fractional differential equations, which bridges the golden ratio to the von Karman spectrum and consequently provides a new outlook of random data following the von Karman spectrum in turbulence. In addition, we express the fractal dimension, which is a measure of local self-similarity, using the golden ratio, of random data governed by the von Karman spectrum.
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    Inner-Resonance Conditions for Honeycomb Paperboard Cushioning Packaging System with Critical Component (2013)
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    Publication Date: 2013-10-04
    Description: A dynamic model was proposed for a honeycomb paperboard cushioning packaging system with critical component. Then the coupled equations of the system were solved by the variational iteration method, from which the conditions for inner-resonance were obtained, which should be avoided in the cushioning packaging design.
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    Variable Structure Control and Applications (2013)
    Hindawi
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    Publication Date: 2013-10-04
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    Study of Railway Track Irregularity Standard Deviation Time Series Based on Data Mining and Linear Model (2013)
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    Publication Date: 2013-10-04
    Description: Good track geometry state ensures the safe operation of the railway passenger service and freight service. Railway transportation plays an important role in the Chinese economic and social development. This paper studies track irregularity standard deviation time series data and focuses on the characteristics and trend changes of track state by applying clustering analysis. Linear recursive model and linear-ARMA model based on wavelet decomposition reconstruction are proposed, and all they offer supports for the safe management of railway transportation.
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    Design of Magnetic Flux Feedback Controller in Hybrid Suspension System (2013)
    Hindawi
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    Publication Date: 2013-10-04
    Description: Hybrid suspension system with permanent magnet and electromagnet consumes little power consumption and can realize larger suspension gap. But realizing stable suspension of hybrid magnet is a tricky problem in the suspension control sphere. Considering from this point, we take magnetic flux signal as a state variable and put this signal back to suspension control system. So we can get the hybrid suspension mathematical model based on magnetic flux signal feedback. By application of MIMO feedback linearization theory, we can further realize linearization of the hybrid suspension system. And then proportion, integral, differentiation, magnetic flux density B (PIDB) controller is designed. Some hybrid suspension experiments have been done on CMS04 magnetic suspension bogie of National University of Defense Technology (NUDT) in China. The experiments denote that the new hybrid suspension control algorithm based on magnetic flux signal feedback designed in this paper has more advantages than traditional position-current double cascade control algorithm. Obviously, the robustness and stability of hybrid suspension system have been enhanced.
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    Exponential Stability in Mean Square of Singular Markovian Jump System with Saturating Actuators and Time-Varying Delay (2013)
    Hindawi
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    Publication Date: 2013-09-09
    Description: This paper investigates exponential stability in mean square of singular Markovian jump systems with saturating actuators and time-varying delay. The statistical property of the Markov process is fully used to derive the differential of the function. By using a delay decomposition method, a mode-dependent Lyapunov-Krasovskii function is established. A sufficient condition is proposed for exponential stability in mean square of the system designing the memoryless state feedback. A numerical example shows that the approach proposed is effective.
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    Application of Three Bioinspired Optimization Methods for the Design of a Nonlinear Mechanical System (2013)
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    Publication Date: 2013-09-12
    Description: The present work focuses on the optimal design of nonlinear mechanical systems by using heuristic optimization methods. In this context, the nonlinear optimization problem is devoted to a two-degree-of-freedom nonlinear damped system, constituted of a primary mass attached to the ground by a linear spring and a secondary mass attached to the primary system by a nonlinear spring. This arrangement forms a nonlinear dynamic vibration absorber (nDVA), which is used in this contribution as a representative example of a nonlinear mechanical system. The sensitivity analysis of the suppression bandwidth, namely, the frequency range over which the ratio of the main mass displacement amplitude to the amplitude of the forcing function is less than unity, with respect to the design variables that characterize the nonlinear system based on the first order finite differences is presented. For illustration purposes the optimization problem is written as to maximize the suppression bandwidth by using three recent bioinspired optimization methods: Bees Colony Algorithm, Firefly Colony Algorithm, and Fish Swarm Algorithm. The results are compared with other evolutionary strategies.
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    Design of the Microsatellite Attitude Control System Using the Mixed Method via LMI Optimization (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: Due to the space missions limited budget, small satellite cluster or constellation would be an economical choice. From risk-sharing viewpoint, a number of smaller satellites have a significant reliability advantage over a bigger one. Generally, one satellite is subject to two types of uncertainties: structured uncertainty that represents some satellite parameter variation and the unstructured uncertainty that represents some kind of the satellite model error. On the other hand, the Satellite Attitude Control (SAC) design becomes more vulnerable to uncertainty disturbances like model error and moment-of-inertia variation as the satellite has great decrease in size and weight. This is the case for a microsatellite with mass less than 100 kg where the ACS performance and robustness become very sensitive to both kinds of uncertainties. As a result, the design of the SAC has to deal with both types of uncertainties which is associated with the drawback between controller performance and robustness. The purpose of this work is to model a microsatellite taking into account the uncertainties and to perform the Control System Design based on the mixed methodology via LMI optimization.
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    A Note on a Fully Polynomial-Time Approximation Scheme for Minimizing Makespan of Deteriorating Jobs (2013)
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    Publication Date: 2013-09-12
    Description: In (1998), Kovalyov and Kubiak studied the problem of scheduling deteriorating jobs on a single machine to minimize makespan. They presented a fully polynomial-time approximation scheme which is based on a dynamic programming. Unfortunately, their dynamic programming is incorrect. So the fully polynomial-time approximation scheme is also invalid. In this paper, we construct an instance to show how their dynamic programming does not work and provide a correct dynamic programming, based on which a new fully polynomial-time approximation scheme is derived.
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    Windowed Least Square Algorithm Based PMSM Parameters Estimation (2013)
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    Publication Date: 2013-09-12
    Description: Stator resistance and inductances in -axis and -axis of permanent magnet synchronous motors (PMSMs) are important parameters. Acquiring these accurate parameters is usually the fundamental part in driving and controlling system design, to guarantee the performance of driver and controller. In this paper, we adopt a novel windowed least algorithm (WLS) to estimate the parameters with fixed value or the parameter with time varying characteristic. The simulation results indicate that the WLS algorithm has a better performance in fixed parameters estimation and parameters with time varying characteristic identification than the recursive least square (RLS) and extended Kalman filter (EKF). It is suitable for engineering realization in embedded system due to its rapidity, less system resource possession, less computation, and flexibility to adjust the window size according to the practical applications.
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    Simulations of Transformer Inrush Current by Using BDF-Based Numerical Methods (2013)
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    Publication Date: 2013-09-12
    Description: This paper describes three different ways of transformer modeling for inrush current simulations. The developed transformer models are not dependent on an integration step, thus they can be incorporated in a state-space form of stiff differential equation systems. The eigenvalue propagations during simulation time cause very stiff equation systems. The state-space equation systems are solved by using A- and L-stable numerical differentiation formulas (NDF2) method. This method suppresses spurious numerical oscillations in the transient simulations. The comparisons between measured and simulated inrush and steady-state transformer currents are done for all three of the proposed models. The realized nonlinear inductor, nonlinear resistor, and hysteresis model can be incorporated in the EMTP-type programs by using a combination of existing trapezoidal and proposed NDF2 methods.
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    Oscillation on a Class of Differential Equations of Fractional Order (2013)
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    Publication Date: 2013-09-13
    Description: Based on Riccati transformation and certain inequality technique, some new oscillatory criteria are established for the solutions of a class of sequential differential equations with fractional order defined in the modified Riemann-Liouville derivative. The oscillatory criteria established are of new forms compared with the existing results so far in the literature. For illustrating the validity of the results established, we present some examples for them.
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    A Nonlinear Robust Controller Design of Lower-Triangular Systems Based on Dissipation Theory (2013)
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    Publication Date: 2013-09-13
    Description: Based on dissipation theory, a novel robust control is proposed for the lower-triangular nonlinear systems, which include strict-feedback systems and high-order lower-triangular systems. Some important concepts in dissipation theory are integrated into the recursive design, which are used to dominate the uncertain disturbance and construct the robust controller. The gotten controller renders the closed-loop system finite-gain stable in the presence of disturbance and asymptotically stable in the absence of disturbance. Especially, the controller has its advantage in regulating large disturbance. Finally, one example and one application are given to show the effectiveness of the design method. Moreover, by comparing with another robust controller, the characteristic of the proposed controller is illustrated in the simulations.
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    Nighttime Fire/Smoke Detection System Based on a Support Vector Machine (2013)
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    Publication Date: 2013-09-13
    Description: Currently, video surveillance-based early fire smoke detection is crucial to the prevention of large fires and the protection of life and goods. To overcome the nighttime limitations of video smoke detection methods, a laser light can be projected into the monitored field of view, and the returning projected light section image can be analyzed to detect fire and/or smoke. If smoke appears within the monitoring zone created from the diffusion or scattering of light in the projected path, the camera sensor receives a corresponding signal. The successive processing steps of the proposed real-time algorithm use the spectral, diffusing, and scattering characteristics of the smoke-filled regions in the image sequences to register the position of possible smoke in a video. Characterization of smoke is carried out by a nonlinear classification method using a support vector machine, and this is applied to identify the potential fire/smoke location. Experimental results in a variety of nighttime conditions demonstrate that the proposed fire/smoke detection method can successfully and reliably detect fires by identifying the location of smoke.
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    A Multidimensional and Multimembership Clustering Method for Social Networks and Its Application in Customer Relationship Management (2013)
    Hindawi
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    Publication Date: 2013-09-15
    Description: Community detection in social networks plays an important role in cluster analysis. Many traditional techniques for one-dimensional problems have been proven inadequate for high-dimensional or mixed type datasets due to the data sparseness and attribute redundancy. In this paper we propose a graph-based clustering method for multidimensional datasets. This novel method has two distinguished features: nonbinary hierarchical tree and the multi-membership clusters. The nonbinary hierarchical tree clearly highlights meaningful clusters, while the multimembership feature may provide more useful service strategies. Experimental results on the customer relationship management confirm the effectiveness of the new method.
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    Improved SpikeProp for Using Particle Swarm Optimization (2013)
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    Publication Date: 2013-09-16
    Description: A spiking neurons network encodes information in the timing of individual spike times. A novel supervised learning rule for SpikeProp is derived to overcome the discontinuities introduced by the spiking thresholding. This algorithm is based on an error-backpropagation learning rule suited for supervised learning of spiking neurons that use exact spike time coding. The SpikeProp is able to demonstrate the spiking neurons that can perform complex nonlinear classification in fast temporal coding. This study proposes enhancements of SpikeProp learning algorithm for supervised training of spiking networks which can deal with complex patterns. The proposed methods include the SpikeProp particle swarm optimization (PSO) and angle driven dependency learning rate. These methods are presented to SpikeProp network for multilayer learning enhancement and weights optimization. Input and output patterns are encoded as spike trains of precisely timed spikes, and the network learns to transform the input trains into target output trains. With these enhancements, our proposed methods outperformed other conventional neural network architectures.
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    Differential Evolution-Based PID Control of Nonlinear Full-Car Electrohydraulic Suspensions (2013)
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    Publication Date: 2013-09-18
    Description: This paper presents a differential-evolution- (DE-) optimized, independent multiloop proportional-integral-derivative (PID) controller design for full-car nonlinear, electrohydraulic suspension systems. The multiloop PID control stabilises the actuator via force feedback and also improves the system performance. Controller gains are computed using manual tuning and through DE optimization to minimise a performance index, which addresses suspension travel, road holding, vehicle handling, ride comfort, and power consumption constraints. Simulation results showed superior performance of the DE-optimized PID-controlled active vehicle suspension system (AVSS) over the manually tuned PID-controlled AVSS and the passive vehicle suspension system (PVSS).
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    XFEM-Based Analysis for Crack Growth Characteristics of Diffusion Bonded Laminates of Titanium Alloy with Localized Nonwelded Zone (2013)
    Hindawi
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    Publication Date: 2013-09-18
    Description: Titanium-alloy laminates fabricated by sheet materials using diffusion bonding process have drawn more and more attention in the recent years. Proper placement of nonwelded zones on the diffusion bonding (DB) interface within titanium-alloy laminates as crack arrest zones can improve damage tolerance. To achieve the optimal damage tolerance via designing non-welded zones, it is necessary to study fatigue crack growth characteristics for this type of laminates by adjusting all the relevant parameters such as geometrical sizes, locations, and the number of the nonwelded zones, which is highly time consuming. Therefore it is essential to develop a reliable and quick method to analyze the fatigue crack growth characteristics for titanium-alloy laminates with non-welded zones. In this paper, the extended finite element method (XFEM) which was employed to simulate the fatigue crack growth process and the applicability of this method to capture fatigue crack growth characteristics of titanium-alloy laminates with localized non-welded zones was also studied. The numerical results were compared with the experiment data, and the agreement on numerical and experimental results illustrated that the specific crack growth characteristics can be captured by using XFEM, thereby verifying the applicability of XFEM in the analysis of fatigue crack growth of the laminates with non-welded zones. The influence of non-welded zones on the fatigue crack growth was then discussed.
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    Studying Close Approaches for a Cloud of Particles Considering Atmospheric Drag (2013)
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    Publication Date: 2013-09-18
    Description: The present paper has the goal of studying close approaches between a planet and a group of particles. The mathematical model includes the presence of the atmosphere of the planet. This cloud is assumed to be created by the passage of the spacecraft in the atmosphere of the planet, which can cause the explosion of the spacecraft. The system is assumed to be formed by the Sun, the planet, and the spacecraft that explodes and becomes a cloud of particles. The Sun and the planet are assumed to be in circular orbits and the motion is planar. The equations of motion are the ones given by the circular planar restricted three-body problem combined with the forces given by the atmospheric drag. In the numerical simulations, the planet Jupiter is the celestial body used for the close approaches. The initial positions and velocities of the spacecraft and the particles are specified at the periapsis, because it is assumed that this is the point where the explosion occurs.
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    Stability and Bifurcation in Magnetic Flux Feedback Maglev Control System (2013)
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    Publication Date: 2013-09-19
    Description: Nonlinear properties of magnetic flux feedback control system have been investigated mainly in this paper. We analyzed the influence of magnetic flux feedback control system on control property by time delay and interfering signal of acceleration. First of all, we have established maglev nonlinear model based on magnetic flux feedback and then discussed hopf bifurcation’s condition caused by the acceleration’s time delay. The critical value of delayed time is obtained. It is proved that the period solution exists in maglev control system and the stable condition has been got. We obtained the characteristic values by employing center manifold reduction theory and normal form method, which represent separately the direction of hopf bifurcation, the stability of the period solution, and the period of the period motion. Subsequently, we discussed the influence maglev system on stability of by acceleration’s interfering signal and obtained the stable domain of interfering signal. Some experiments have been done on CMS04 maglev vehicle of National University of Defense Technology (NUDT) in Tangshan city. The results of experiments demonstrate that viewpoints of this paper are correct and scientific. When time lag reaches the critical value, maglev system will produce a supercritical hopf bifurcation which may cause unstable period motion.
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    A Second-Order Sliding Mode Controller Design for Spacecraft Tracking Control (2013)
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    Publication Date: 2013-09-19
    Description: For spacecraft attitude tracking system, there exists the chattering phenomenon. In this paper, the spacecraft motion is decomposed into three-channel subsystems, and a second-order sliding mode control is proposed. This method has been proved to have good convergence and robustness. Combined with the proposed sliding surface, the three-channel controllers are designed. The control performance is confirmed by the simulation results, the approaching process is improved effectively, and a smooth transition is achieved without overshoot and buffeting.
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    Optimal Control Strategy for Traffic Driven Epidemic Spreading Based on Community Structure (2013)
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    Publication Date: 2013-09-19
    Description: It is shown that community structure has a great impact on traffic transportation and epidemic spreading. The density of infected nodes and the epidemic threshold have been proven to have significant relationship with the node betweenness in traffic driven epidemic spreading method. In this paper, considering the impact of community structure on traffic driven epidemic spreading, an effective and novel strategy to control epidemic spreading in scale-free networks is proposed. Theoretical analysis shows that the new control strategy will obviously increase the ratio between the first and the second moments of the node betweenness distribution in scale-free networks. It is also found that the more accurate the community is identified, the stronger community structure the network has and the more efficient the control strategy is. Simulations on both computer-generated and real-world networks have confirmed the theoretical results.
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    A Frequency Compensation Algorithm of Four-Wheel Coherence Random Road (2013)
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    Publication Date: 2013-09-19
    Description: The road surface roughness is the main source of kinematic excitation of a moving vehicle, which has an important influence on vehicle performance. In recent decades, random road models have been widely studied, and a four-wheel random road time domain model is usually generated based on the correlation of the four-wheel input, in which a coherence function is used to describe the coherence of the road input between the left and right wheels usually. However, during our research, there are some conditions that show that the road PSD (power spectral density) of one wheel is smaller than the other one on the same axle. Actually, it is caused by the uncorrelation between the left- and right-wheel road surface roughness. Hence, a frequency compensation algorithm is proposed to correct the deviation of the PSD of the road input between two wheels on the same axle, and it is installed in a 7-DOF vehicle dynamic study. The simulation result demonstrates the applicability of the proposed algorithm such that two-wheel road input deviation compensation has an important influence on vehicle performances, and it can be used for a control system installed in the vehicle to compensate road roughness for damper tuning in the future.
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    Hybrid DE-SQP Method for Solving Combined Heat and Power Dynamic Economic Dispatch Problem (2013)
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    Publication Date: 2013-09-22
    Description: Combined heat and power dynamic economic dispatch (CHPDED) plays a key role in economic operation of power systems. CHPDED determines the optimal heat and power schedule of committed generating units by minimizing the fuel cost under ramp rate constraints and other constraints. Due to complex characteristics, heuristic and evolutionary based optimization approaches have became effective tools to solve the CHPDED problem. This paper proposes hybrid differential evolution (DE) and sequential quadratic programming (SQP) to solve the CHPDED problem with nonsmooth and nonconvex cost function due to valve point effects. DE is used as a global optimizer and SQP is used as a fine tuning to determine the optimal solution at the final. The proposed hybrid DE-SQP method has been tested and compared to demonstrate its effectiveness.
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    Behavior-Based Fuzzy Control for Mobile Robot Navigation (2013)
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    Publication Date: 2013-09-22
    Description: A new behavior-based fuzzy control method for mobile robot navigation is presented. It is based on behavioral architecture which can deal with uncertainties in unknown environments and has the ability to accommodate different behaviors. Basic behaviors are controlled by specific fuzzy logic controllers, respectively. The proposed approach qualifies for driving a robot to reach a target while avoiding obstacles in the environment. Simulation and experiments are performed to verify the correctness and feasibility of the proposed method.
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    Generalized Neumann Expansion and Its Application in Stochastic Finite Element Methods (2013)
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    Publication Date: 2013-09-24
    Description: An acceleration technique, termed generalized Neumann expansion (GNE), is presented for evaluating the responses of uncertain systems. The GNE method, which solves stochastic linear algebraic equations arising in stochastic finite element analysis, is easy to implement and is of high efficiency. The convergence condition of the new method is studied, and a rigorous error estimator is proposed to evaluate the upper bound of the relative error of a given GNE solution. It is found that the third-order GNE solution is sufficient to achieve a good accuracy even when the variation of the source stochastic field is relatively high. The relationship between the GNE method, the perturbation method, and the standard Neumann expansion method is also discussed. Based on the links between these three methods, quantitative error estimations for the perturbation method and the standard Neumann method are obtained for the first time in the probability context.
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    Nonlocal Variational Model for Saliency Detection (2013)
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    Publication Date: 2013-09-24
    Description: We present a nonlocal variational model for saliency detection from still images, from which various features for visual attention can be detected by minimizing the energy functional. The associated Euler-Lagrange equation is a nonlocal -Laplacian type diffusion equation with two reaction terms, and it is a nonlinear diffusion. The main advantage of our method is that it provides flexible and intuitive control over the detecting procedure by the temporal evolution of the Euler-Lagrange equation. Experimental results on various images show that our model can better make background details diminish eventually while luxuriant subtle details in foreground are preserved very well.
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    Wild Fluctuations of Random Functions with the Pareto Distribution (2013)
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    Publication Date: 2013-09-24
    Description: This paper provides the fluctuation analysis of random functions with the Pareto distribution. By the introduced concept of wild fluctuations, we give an alternative way to classify the fluctuations from those with light-tailed distributions. Moreover, the suggested term wildest fluctuation may be used to classify random functions with infinite variance from those with finite variances.
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    Artificial Hydrocarbon Networks Fuzzy Inference System (2013)
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    Publication Date: 2013-09-24
    Description: This paper presents a novel fuzzy inference model based on artificial hydrocarbon networks, a computational algorithm for modeling problems based on chemical hydrocarbon compounds. In particular, the proposed fuzzy-molecular inference model (FIM-model) uses molecular units of information to partition the output space in the defuzzification step. Moreover, these molecules are linguistic units that can be partially understandable due to the organized structure of the topology and metadata parameters involved in artificial hydrocarbon networks. In addition, a position controller for a direct current (DC) motor was implemented using the proposed FIM-model in type-1 and type-2 fuzzy inference systems. Experimental results demonstrate that the fuzzy-molecular inference model can be applied as an alternative of type-2 Mamdani’s fuzzy control systems because the set of molecular units can deal with dynamic uncertainties mostly present in real-world control applications.
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    Bearing Capacity Factors for Eccentrically Loaded Strip Footings Using Variational Analysis (2013)
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    Publication Date: 2013-09-24
    Description: Bearing capacity factors for eccentrically loaded strip smooth footings on homogenous cohesive frictional material are deduced by the variational limit equilibrium method and by assuming general shear failure along continuous curved slip surface. From the calculated results, the effective width rule suggested by Meyerhof for bearing capacity factors due to cohesion of soil is justified, and the superposition principle of bearing capacity for eccentrically loaded strip smooth footings is derived together with the bearing capacity factors for cohesion and unit weight of soil. The two factors are represented by soil strength parameters and eccentricity of load. The bearing capacity factor related to unit weight for cohesionless soil is less than that for cohesive frictional soil. The reason for this discrepancy lies in the existence of the soil cohesion, for the shape of the critical rupture surface of footing soil depends on both soil strength parameters rather than on friction angle alone in the previous limit equilibrium solutions. The contact between footing and soil is decided by both the load and the mechanical properties of soil. Under conditions of higher eccentricity and less strength properties of soil, part of the footing will separate from the underlying soil.
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    Fuzzy ARTMAP Ensemble Based Decision Making and Application (2013)
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    Publication Date: 2013-09-24
    Description: Because the performance of single FAM is affected by the sequence of sample presentation for the offline mode of training, a fuzzy ARTMAP (FAM) ensemble approach based on the improved Bayesian belief method is supposed to improve the classification accuracy. The training samples are input into a committee of FAMs in different sequence, the output from these FAMs is combined, and the final decision is derived by the improved Bayesian belief method. The experiment results show that the proposed FAMs’ ensemble can classify the different category reliably and has a better classification performance compared with single FAM.
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    Observer-Based Sliding Mode Control for Uncertain Stochastic Systems with Time-Varying Delays (2013)
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    Publication Date: 2013-09-24
    Description: The paper is concerned with sliding mode control for uncertain time-delay systems subjected to input nonlinearity and stochastic perturbations. Using the sliding mode control, a robust law is derived to guarantee the reachability of the sliding surface in a finite time interval. The sufficient conditions on asymptotic stability of the error system and sliding mode dynamics with disturbance attenuation level are presented in terms of linear matrix inequalities (LMIs). Finally, an example is provided to illustrate the efficiency and effectiveness of the proposed method.
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    Weighted Essentially Nonoscillatory Method for Two-Dimensional Population Balance Equations in Crystallization (2013)
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    Publication Date: 2013-09-24
    Description: Population balance equations (PBEs) are the main governing equations to model the processes of crystallization. Two-dimensional PBEs refer to the crystals that grow anisotropically with the change of two internal coordinates. Since the PBEs are hyperbolic equations, it is necessary to build up high resolution schemes to avoid numerical diffusion and numerical dispersion in order to obtain the accurate crystal size distribution (CSD). In this work, a 5th order weighted essentially nonoscillatory (WENO) method is introduced to compute the two-dimensional PBEs. Several numerical benchmark examples from literatures are carried out; it is found that WENO method has higher resolution than HR method which is well established. Therefore, WENO method is recommended in crystallization simulation when the crystal size distributions are sharp and higher accuracy is needed.
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    Robust Quadratic Regression and Its Application to Energy-Growth Consumption Problem (2013)
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    Publication Date: 2013-09-24
    Description: We propose a robust quadratic regression model to handle the statistics inaccuracy. Unlike the traditional robust statistic approaches that mainly focus on eliminating the effect of outliers, the proposed model employs the recently developed robust optimization methodology and tries to minimize the worst-case residual errors. First, we give a solvable equivalent semidefinite programming for the robust least square model with ball uncertainty set. Then the result is generalized to robust models under - and -norm critera with general ellipsoid uncertainty sets. In addition, we establish a robust regression model for per capital GDP and energy consumption in the energy-growth problem under the conservation hypothesis. Finally, numerical experiments are carried out to verify the effectiveness of the proposed models and demonstrate the effect of the uncertainty perturbation on the robust models.
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    A Multilabel Texture Segmentation Based on Local Entropy Signature (2013)
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    Publication Date: 2013-09-26
    Description: We propose a multilabel segmentation that aims to partition a texture image into multiple regions based on a homogeneity condition using local entropy measured at varying scales. For multi-label segmentation, a bipartitioning segmentation scheme is recursively applied to confined regions obtained by previous segmentation steps. The empirical entropy is measured in the local neighbourhoods at varying scales, which is used as a characteristic feature in determining the spatial regularity of elementary texture structures. The experimental results on a variety of texture images demonstrate the efficiency and robustness of the proposed algorithm.
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    Application of Base Force Element Method to Mesomechanics Analysis for Recycled Aggregate Concrete (2013)
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    Publication Date: 2013-09-26
    Description: The base force element method (BFEM) on potential energy principle is used to analyze recycled aggregate concrete (RAC) on mesolevel. The model of BFEM with triangular element is derived. The recycled aggregate concrete is taken as five-phase composites consisting of natural coarse aggregate, new mortar, new interfacial transition zone (ITZ), old mortar, and old ITZ on meso-level. The random aggregate model is used to simulate the mesostructure of recycled aggregate concrete. The mechanics properties of uniaxial compression and tension tests for RAC are simulated using the BFEM, respectively. The simulation results agree with the test results. This research method is a new way for investigating fracture mechanism and numerical simulation of mechanics properties for recycled aggregate concrete.
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    Robust Control for Discrete-Time Stochastic Interval System with Time Delay (2013)
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    Publication Date: 2013-09-26
    Description: The robust control problem for discrete-time stochastic interval system (DTSIS) with time delay is investigated in this paper. The stochastic interval system is equivalently transformed into a kind of stochastic uncertain time-delay system firstly. By constructing the appropriate Lyapunov-Krasovskii functional, the sufficient conditions for the existence of the robust controller for DTSIS are obtained in terms of linear matrix inequality (LMI) form, and the robust controller is designed. Finally, a numerical example with simulation is given to show the effectiveness and correctness of the designed robust controller.
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    Analysis of Sandwich Plates by Generalized Differential Quadrature Method (2013)
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    Publication Date: 2013-09-26
    Description: We combine a layer-wise formulation and a generalized differential quadrature technique for predicting the static deformations and free vibration behaviour of sandwich plates. Through numerical experiments, the capability and efficiency of this strong-form technique for static and vibration problems are demonstrated, and the numerical accuracy and convergence are thoughtfully examined.
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    An Alternating Direction Implicit Method for Solving Projected Generalized Continuous-Time Sylvester Equations (2013)
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    Publication Date: 2013-09-27
    Description: We present the generalized low-rank alternating direction implicit method and the low-rank cyclic Smith method to solve projected generalized continuous-time Sylvester equations with low-rank right-hand sides. Such equations arise in control theory including the computation of inner products and norms and the model reduction based on balanced truncation for descriptor systems. The requirements of these methods are moderate with respect to both computational cost and memory. Numerical experiments presented in this paper show the effectiveness of the proposed methods.
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    MHD Slip Flow of Newtonian Fluid past a Stretching Sheet with Thermal Convective Boundary Condition, Radiation, and Chemical Reaction (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: An analysis is carried out to study the problem of heat and mass transfer flow over a moving permeable flat stretching sheet in the presence of convective boundary condition, slip, radiation, heat generation/absorption, and first-order chemical reaction. The viscosity of fluid is assumed to vary linearly with temperature. Also the diffusivity is assumed to vary linearly with concentration. The governing partial differential equations have been reduced to the coupled nonlinear ordinary differential equations by using Lie group point of transformations. The system of transformed nonlinear ordinary differential equations is solved numerically using shooting techniques with fourth-order Runge-Kutta integration scheme. Comparison between the existing literature and the present study was carried out and found to be in excellent agreement. The effects of the various interesting parameters on the flow, heat, and mass transfer are analyzed and discussed through graphs in detail. The values of the local Nusselt number, the local skin friction, and the local Sherwood number for different physical parameters are also tabulated.
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    The Flow of a Variable Viscosity Fluid down an Inclined Plane with a Free Surface (2013)
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    Publication Date: 2013-09-27
    Description: The effect of a temperature dependent variable viscosity fluid flow down an inclined plane with a free surface is investigated. The fluid film is thin, so that lubrication approximation may be applied. Convective heating effects are included, and the fluid viscosity decreases exponentially with temperature. In general, the flow equations resulting from the variable viscosity model must be solved numerically. However, when the viscosity variation is small, then an asymptotic approximation is possible. The full solutions for the temperature and velocity profiles are derived using the Runge-Kutta numerical method. The flow controlling parameters such as the nondimensional viscosity variation parameter, the Biot and the Brinkman numbers, are found to have a profound effect on the resulting flow profiles.
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    Soft Rough Approximation Operators on a Complete Atomic Boolean Lattice (2013)
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    Publication Date: 2013-09-27
    Description: The concept of soft sets based on complete atomic Boolean lattice, which can be seen as a generalization of soft sets, is introduced. Some operations on these soft sets are discussed, and new types of soft sets such as full, keeping infimum, and keeping supremum are defined and supported by some illustrative examples. Two pairs of new soft rough approximation operators are proposed and the relationship among soft set is investigated, and their related properties are given. We show that Järvinen's approximations can be viewed as a special case of our approximation. If , then our soft approximations coincide with crisp soft rough approximations (Feng et al. 2011).
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    State-Feedback Control for LPV System Using T-S Fuzzy Linearization Approach (2013)
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    Publication Date: 2013-10-01
    Description: This paper discusses the linear parameter varying (LPV) gain scheduling control problem based on the Takagi-Sugeno (T-S) fuzzy linearization approach. Firstly, the affine nonlinear parameter varying (ANPV) description of a class of nonlinear dynamic processes is defined; that is, at any scheduling parameter, the corresponding system is affine nonlinear as usual. For such a class of ANPV systems, a kind of developed T-S fuzzy modeling procedure is proposed to deal with the nonlinearity, instead of the traditional Jacobian linearization approach. More concretely, the evaluation system for the approximation ability of the novelly developed T-S fuzzy modeling procedure is established. Consequently, the LPV T-S fuzzy system is obtained which can approximate the ANPV system with required accuracy. Secondly, the notion of piecewise parameter-dependent Lyapunov function is introduced, and then the stabilization problem and the state-feedback control problem of the LPV T-S fuzzy system are studied. The sufficient conditions are given in linear matrix inequalities (LMIs) form. Finally, a numerical example is provided to demonstrate the availability of the above approaches. The simulation results show the high approximation accuracy of the LPV T-S fuzzy system to the ANPV system and the effectiveness of the LPV T-S fuzzy gain scheduling control.
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    An Image Filter Based on Multiobjective Genetic Algorithm and Shearlet Transformation (2013)
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    Publication Date: 2013-10-01
    Description: Rician noise pollutes magnetic resonance imaging (MRI) data, making data’s postprocessing difficult. In order to remove this noise and avoid loss of details as much as possible, we proposed a filter algorithm using both multiobjective genetic algorithm (MOGA) and Shearlet transformation. Firstly, the multiscale wavelet decomposition is applied to the target image. Secondly, the MOGA target function is constructed by evaluation methods, such as signal-to-noise ratio (SNR) and mean square error (MSE). Thirdly, MOGA is used with optimal coefficients of Shearlet wavelet threshold value in a different scale and a different orientation. Finally, the noise-free image could be obtained through inverse wavelet transform. At the end of the paper, experimental results show that this proposed algorithm eliminates Rician noise more effectively and yields better peak signal-to-noise ratio (PSNR) gains compared with other traditional filters.
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    Legendre Wavelets Method for Solving Fractional Population Growth Model in a Closed System (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: A new operational matrix of fractional order integration for Legendre wavelets is derived. Block pulse functions and collocation method are employed to derive a general procedure for forming this matrix. Moreover, a computational method based on wavelet expansion together with this operational matrix is proposed to obtain approximate solution of the fractional population growth model of a species within a closed system. The main characteristic of the new approach is to convert the problem under study to a nonlinear algebraic equation.
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    Integral Sliding Mode Control Strategy of D-STATCOM for Unbalanced Load Compensation under Various Disturbances (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: Control strategies of D-STATCOM for unbalanced load compensation under internal and external disturbances were discussed. Linear control strategies do not have a satisfactory dynamic performance and become invalid under internal or external disturbances. To guarantee a good precision and robustness, a control strategy combining input-output feedback linearization technique with integral sliding mode control (ISMC) method was applied to D-STATCOM for unbalanced load compensation. The strategy has features of simple structure and is easy to implement. A 10 MVar/10 kV D-STATCOM simulation system was built in PSCAD/EMTDC to verify the effectiveness and robustness of the control strategy proposed. Simulation results show that the control strategy can compensate reactive power and eliminate unbalance simultaneously under various disturbances.
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    An Analysis and Design for Nonlinear Quadratic Systems Subject to Nested Saturation (2013)
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    Publication Date: 2013-10-01
    Description: This paper considers the stability problem for nonlinear quadratic systems with nested saturation input. The interesting treatment method proposed to nested saturation here is put into use a well-established linear differential control tool. And the new conclusions include the existing conclusion on this issue and have less conservatism than before. Simulation example illustrates the effectiveness of the established methodologies.
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    An Efficient Patch Dissemination Strategy for Mobile Networks (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: Mobile phones and personal digital assistants are becoming increasingly important in our daily life since they enable us to access a large variety of ubiquitous services. Mobile networks, formed by the connection of mobile devices following some relationships among mobile users, provide good platforms for mobile virus spread. Quick and efficient security patch dissemination strategy is necessary for the update of antivirus software so that it can detect mobile virus, especially the new virus under the wireless mobile network environment with limited bandwidth which is also large scale, decentralized, dynamically evolving, and of unknown network topology. In this paper, we propose an efficient semi autonomy-oriented computing (SAOC) based patch dissemination strategy to restrain the mobile virus. In this strategy, some entities are deployed in a mobile network to search for mobile devices according to some specific rules and with the assistance of a center. Through experiments involving both real-world networks and dynamically evolving networks, we demonstrate that the proposed strategy can effectively send security patches to as many mobile devices as possible at a considerable speed and lower cost in the mobile network. It is a reasonable, effective, and secure method to reduce the damages mobile viruses may cause.
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    Selection Method for Kernel Function in Nonparametric Extrapolation Based on Multicriteria Decision-Making Technology (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: Selecting the most appropriate kernel function to extrapolate a load set is the paramount step in compiling load spectrum, as it affects the results of nonparametric extrapolation largely. Aiming at this issue, this paper provides a new approach in selecting kernel function for the nonparametric extrapolation. To solve the complexity and uncertainty of nonparametric extrapolation, characteristics of four kernel functions and their effects on the results are explained in the “from-to” diagram obtained by rainflow counting. Multicriteria decision-making (MCDM) is then applied to solve the selection problem of kernel function. To evaluate the dispersion degrees of the mean and amplitude of a load set accurately, their range, standard deviation, and interquartile range are selected as the evaluation criteria. The weight of each criterion, which represents the impact degree on the selection of the kernel function, is calculated separately using the eigenvector and entropy method. The comprehensive weights are obtained by applying the optimization theory and Jaynes’ maximum entropy principle. Finally, the importance of each criterion is discussed according to their calculated comprehensive weights, and the selection method for kernel functions is obtained, which is illustrated by extrapolating the output torque of the power split device of hybrid electrical vehicles.
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    A Novel Approach to - Filter Design for T-S Fuzzy Systems with Multiple Time-Varying Delays (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: This paper investigates the - filtering problem of T-S fuzzy systems with multiple time-varying delays. First, by the Lyapunov-Krasovskii functional approach and free-weighting matrix method, a delay-dependent sufficient condition on --disturbance attenuation is presented, in which both stability and prescribed - performance are required to be achieved for the filtering-error systems. Then, based on the condition, the full-order and reduced-order delay-dependent - filter design schemes for T-S fuzzy multiple time-varying delays systems are developed in terms of linear matrix inequality (LMI). Finally, an example is given to illustrate the effectiveness of the result.
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    Approximate Bisimulation and Optimization of Software Programs Based on Symbolic-Numeric Computation (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: To achieve behavior and structure optimization for a type of software program whose data exchange processes are represented by nonlinear polynomial systems, this paper establishes a novel formal description called a nonlinear polynomial transition system to represent the behavior and structure of the software program. Then, the notion of bisimulation for software programs is proposed based on the equivalence relation of corresponding nonlinear polynomial systems in their nonlinear polynomial transition systems. However, the exact equivalence is too strict in application. To enhance the flexibility of the relation among the different software systems, the notion of approximate bisimulation within a controllable error range and the calculation algorithm of approximate bisimulation based on symbolic-numeric computation are given. In this calculation, an approximate relation is represented as a MAX function that is resolved with the full filled method. At the same time, the actual error is calculable. An example on a multithreading program indicates that the approximate bisimulation relation is feasible and effective in behavior and structure optimization.
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    A Multiple Attribute Decision Making Method Based on Uncertain Linguistic Heronian Mean (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: The Heronian mean is a useful aggregation operator which can capture the interrelationship of the input arguments. In this paper, we develop some Heronian means based on uncertain linguistic variables, such as the generalized uncertain linguistic Heronian mean (GULHM) and uncertain linguistic geometric Heronian mean (ULGHM), and some of their desirable properties are also investigated. Considering the different importance of the input arguments, we define the generalized uncertain linguistic weighted Heronian mean (GULWHM) and uncertain linguistic weighted geometric Heronian mean (ULWGHM). Then, a method of multiple attribute decision making under uncertain linguistic environment is presented based on the GULWHM or the ULWGHM. In the end, an example is given to demonstrate the effectiveness and feasibility of the proposed method.
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    Seeking the Important Nodes of Complex Networks in Product R&D Team Based on Fuzzy AHP and TOPSIS (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: How to seek the important nodes of complex networks in product research and development (R&D) team is particularly important for companies engaged in creativity and innovation. The previous literature mainly uses several single indicators to assess the node importance; this paper proposes a multiple attribute decision making model to tentatively solve these problems. Firstly, choose eight indicators as the evaluation criteria, four from centralization of complex networks: degree centrality, betweenness centrality, closeness centrality, and eigenvector centrality and four from structural holes of complex networks: effective size, efficiency, constraint, and hierarchy. Then, use fuzzy analytic hierarchy process (AHP) to obtain the weights of these indicators and use technique for order preference by similarity to an ideal solution (TOPSIS) to assess the importance degree of each node of complex networks. Finally, taking a product R&D team of a game software company as a research example, test the effectiveness, operability, and efficiency of the method we established.
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    Residual ISI Obtained by Nonblind Adaptive Equalizers and Fractional Noise (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: Recently, a closed-form approximated expression was derived by the same author for the achievable residual intersymbol interference (ISI) case that depends on the step-size parameter, equalizer's tap length, input signal statistics, signal to noise ratio (SNR), and channel power and is valid for fractional Gaussian noise (fGn) input where the Hurst exponent is in the region of . But this expression was obtained for the blind adaptive case and cannot be applied to the nonblind adaptive version. Up to now, the achievable residual ISI for the non-blind adaptive case could be obtained only via simulation. In this paper, we derive a closed-form approximated expression (or an upper limit) for the residual ISI obtained by non-blind adaptive equalizers valid for fractional Gaussian noise (fGn) input where the Hurst exponent is in the region of . This new obtained expression depends on the step-size parameter, equalizer's tap length, input signal statistics, SNR, channel power, and the Hurst exponent parameter. Simulation results indicate that there is a high correlation between the calculated results (obtained from the new obtained expression for the residual ISI) and those obtained from simulating the system.
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    On the Use of Time-Limited Information for Maintenance Decision Support: A Predictive Approach under Maintenance Constraints (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: This paper deals with a gradually deteriorating system operating under an uncertain environment whose state is only known on a finite rolling horizon. As such, the system is subject to constraints. Maintenance actions can only be planned at imposed times called maintenance opportunities that are available on a limited visibility horizon. This system can, for example, be a commercial vehicle with a monitored critical component that can be maintained only in some specific workshops. Based on the considered system, we aim to use the monitoring data and the time-limited information for maintenance decision support in order to reduce its costs. We propose two predictive maintenance policies based, respectively, on cost and reliability criteria. Classical age-based and condition-based policies are considered as benchmarks. The performance assessment shows the value of the different types of information and the best way to use them in maintenance decision making.
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    A Nonlinear Consensus Protocol of Multiagent Systems Considering Measuring Errors (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: In order to avoid a potential waste of energy during consensus controls in the case where there exist measurement uncertainties, a nonlinear protocol is proposed for multiagent systems under a fixed connected undirected communication topology and extended to both the cases with full and partial access a reference. Distributed estimators are utilized to help all agents agree on the understandings of the reference, even though there may be some agents which cannot access to the reference directly. An additional condition is also considered, where self-known configuration offsets are desired. Theoretical analyses of stability are given. Finally, simulations are performed, and results show that the proposed protocols can lead agents to achieve loose consensus and work effectively with less energy cost to keep the formation, which have illustrated the theoretical results.
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    He Chengtian’s Inequalities for a Coupled Tangent Nonlinear System Arisen in Packaging System (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: He Chengtian’s inequalities from ancient Chinese algorithm are applied to strong tangent nonlinear packaging system. The approximate solution is obtained and compared with the solution yielded by computer simulation, showing a great high accuracy of this method. The suggested approach provides a novel method to solve some essential problems in packaging engineering.
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    Low-Complexity Compression Algorithm for Hyperspectral Images Based on Distributed Source Coding (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: A low-complexity compression algorithm for hyperspectral images based on distributed source coding (DSC) is proposed in this paper. The proposed distributed compression algorithm can realize both lossless and lossy compression, which is implemented by performing scalar quantization strategy on the original hyperspectral images followed by distributed lossless compression. Multilinear regression model is introduced for distributed lossless compression in order to improve the quality of side information. Optimal quantized step is determined according to the restriction of the correct DSC decoding, which makes the proposed algorithm achieve near lossless compression. Moreover, an effective rate distortion algorithm is introduced for the proposed algorithm to achieve low bit rate. Experimental results show that the compression performance of the proposed algorithm is competitive with that of the state-of-the-art compression algorithms for hyperspectral images.
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