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  • Open Access

    ARTICLE

    A Reduction Algorithm of Contact Problems for Core Seismic Analysis of Fast Breeder Reactors

    Ryuta Imai1, Masatoshi Nakagawa2

    CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.3, pp. 253-282, 2012, DOI:10.3970/cmes.2012.084.253

    Abstract In order to evaluate seismic response of fast breeder reactors, finite element analysis for core vibration with contact/impact is performed so far. However a full model analysis of whole core vibration requires huge calculation times and memory sizes. In this research, we propose an acceleration method of reducing the number of degrees of freedom to be solved until converged for nonlinear contact problems. Furthermore we show a sufficient condition for the algorithm to work well and discuss its efficiency and a generalization of the algorithm. In particular we carry out the full model analysis to More >

  • Open Access

    ARTICLE

    Boundary Integral Computation of Elastic Water Resisting Key Strata under the Condition of Discontinuous Load

    Dan Ma, Xianbiao Mao, Chong Li, Feng Du

    CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.6, pp. 561-574, 2012, DOI:10.3970/cmes.2012.083.561

    Abstract Water resisting key strata (WRKS) is one of the most important structures in green coal mining engineering, which has the functions of water-preserved mining and disaster prevention of water inrush, while elastic WRKS is treated as one of the problems for elastic plates in this paper. The existing literatures on elastic plates have largely restricted to different engineering but minority in coal mining engineering. Based on the mechanical models of clamped circular plate with sub-uniform load and simply supported by a concentrated force for elastic WRKS, using the boundary integral equations which is obtained by More >

  • Open Access

    ABSTRACT

    The Coupling Method with the Natural Boundary Reduction on an Ellipse for Exterior Anisotropic Problems

    Quan Zheng, Jing Wang, Jing-ya Li

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 101-102, 2011, DOI:10.3970/icces.2011.017.101

    Abstract This paper investigates the coupling method of the finite element and the natural boundary element using an elliptic artificial boundary for solving exterior anisotropic problems, and obtains new error estimate that depends on the mesh size, the location of the elliptic artificial boundary, the number of terms after truncating from the infinite series in the integral. Numerical examples are presented to demonstrate the effectiveness and accuracy of this method. More >

  • Open Access

    ARTICLE

    First Principles Computations of the Oxygen Reduction Reaction on Solid Metal Clusters

    Cheng-Hung San1, Chuang-Pin Chiu1, Che-Wun Hong1,2

    CMC-Computers, Materials & Continua, Vol.26, No.3, pp. 167-186, 2011, DOI:10.3970/cmc.2011.026.167

    Abstract An improvement in the catalytic process of oxygen reduction reactions is of prime importance for further progress in low temperature fuel cell performance. This paper intends to investigate this problem from a fundamental quantum mechanics viewpoint. For this purpose, a hybrid density functional theory is employed to analyze the catalytic mechanism of the oxygen reduction at the fuel cell cathode. Major steps in the oxygen reduction that include the oxygen adsorption on solid metal clusters (e.g. Cu and Pt) and complete four proton transfer steps are simulated. Proton transfer processes from hydroniums to the adsorbed More >

  • Open Access

    ARTICLE

    The Coupling FEM and Natural BEM for a Certain Nonlinear Interface Problem with Non-Matching Grids

    Ju’e Yang1, Dehao Yu2

    CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.3, pp. 311-330, 2011, DOI:10.3970/cmes.2011.073.311

    Abstract In this paper, we introduce a domain decomposition method with non-matching grids for a certain nonlinear interface problem in unbounded domains. To solve this problem, we discuss a new coupling of finite element method(FE) and natural boundary element(NBE). We first derive the optimal energy error estimate of finite element approximation to the coupled FEM-NBEM problem. Then we use a dual basis multipier on the interface to provide the numerical analysis with non-matching grids.Finally, we give some numerical examples further to confirm our theoretical results. More >

  • Open Access

    ARTICLE

    The Coupling Method with the NaturalBoundary Reduction on an Ellipse for Exterior Anisotropic Problems

    Quan Zheng2, Jing Wang2, Jing-ya Li2

    CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.2, pp. 103-114, 2011, DOI:10.3970/cmes.2011.072.103

    Abstract This paper investigates the coupling method of the finite element and the natural boundary element using an elliptic artificial boundary for solving exterior anisotropic problems, and obtains a new error estimate that depends on the mesh size, the location of the elliptic artificial boundary, the number of terms after truncating from the infinite series in the integral. Numerical examples are presented to demonstrate the effectiveness and the properties of this method. More >

  • Open Access

    ARTICLE

    Efficient Cohomology Computation for Electromagnetic Modeling

    Paweł Dłotko1, Ruben Specogna2

    CMES-Computer Modeling in Engineering & Sciences, Vol.60, No.3, pp. 247-278, 2010, DOI:10.3970/cmes.2010.060.247

    Abstract The systematic potential design is of high importance in computational electromagnetics. For example, it is well known that when the efficient eddy-current formulations based on a magnetic scalar potential are employed in problems which involve conductive regions with holes, the so-calledthick cutsare needed to make the boundary value problem well defined. Therefore, a considerable effort has been invested over the past twenty-five years to develop fast and general algorithms to compute thick cuts automatically. Nevertheless, none of the approaches proposed in literature meet all the requirements of being automatic, computationally efficient and general. In this More >

  • Open Access

    ARTICLE

    Error Reduction in Gauss-Jacobi-Nyström Quadraturefor Fredholm Integral Equations of the Second Kind

    M. A. Kelmanson1 and M. C. Tenwick1

    CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.2, pp. 191-210, 2010, DOI:10.3970/cmes.2010.055.191

    Abstract A method is presented for improving the accuracy of the widely used Gauss-Legendre Nyström method for determining approximate solutions of Fredholm integral equations of the second kind on finite intervals. The authors' recent continuous-kernel approach is generalised in order to accommodate kernels that are either singular or of limited continuous differentiability at a finite number of points within the interval of integration. This is achieved by developing a Gauss-Jacobi Nyström method that moreover includes a mean-value estimate of the truncation error of the Hermite interpolation on which the quadrature rule is based, making it particularly More >

  • Open Access

    ABSTRACT

    A Post-processing for the reduction of blocking artifact in mobile devices

    Dae-Hyun Park1, Hyun-Hee Park2, Yoon Kim1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.4, pp. 113-114, 2009, DOI:10.3970/icces.2009.011.113

    Abstract In this paper, we propose a post-processing visual enhancement technique to reduce the blocking artifacts in block based DCT decoded image for mobile devices that has allocation of the restricted resource. This algorithm uses the adaptive deblocking filter to remove grid noise and ringing noise in monotone areas. To decide whether monotone region or not, we introduce a notion of Flatness. Also, a new directional filter is utilized to get rid of staircase noise and preserve the original edge component. The directional filter is applied according to the direction of edge, which is corrected in More >

  • Open Access

    ARTICLE

    Compact Modelling of Electric Arc Furnace Electrodes for Vibration Analysis, Detection and Suppression

    E. Brusa1, E. Franceschinis2, S. Morsut2

    CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.2, pp. 75-106, 2009, DOI:10.3970/cmes.2009.042.075

    Abstract Electrodes motion and positioning are critical issues of the Electric Arc Furnace (EAF) operation in steelmaking process. During the melting process electrode is exposed to some impulsive and harmonic forces, superimposing to the structure's static loading. Unfortunately, structural vibration may interact with the electric arc regulation, because of the dynamic resonance. Instability in the furnace power supplying and dangerous electrode breakage may occur as a consequence of those dynamic effects. In this paper the dynamic behaviour of a real EAF structure is discussed and some numerical models are proposed. Available experimental data, collected by a… More >

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