Home / Journals / CMES / Vol.81, No.3&4, 2011
Table of Content
  • Open Access

    ARTICLE

    Numerical Analysis of Concrete Composites at the Mesoscale Based on 3D Reconstruction Technology of X-ray CT Images

    C.B. Du1,2, S.Y Jiang2, W. Qin3, Y.M. Zhang2
    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 229-248, 2011, DOI:10.3970/cmes.2011.081.229
    Abstract A numerical analysis of concrete composites at the mesoscale based on three-dimensional (3D) reconstruction technology of X-ray computed tomography (CT) images is presented in this paper. For X-ray CT images of concrete, morphology processing was used to recover complete image information, including borders, and the median filtering method was applied to eliminate potential impurities in the images. The final X-ray CT images obtained after processing for a concrete section were composed of three-value pixels that indicated aggregate particles, mortar matrix and air voids, and the 3D structure of the concrete specimen was reconstructed using the volume data method. The mapping… More >

  • Open Access

    ARTICLE

    Unified Dispersion Characteristics of Structural Acoustic Waveguides

    Abhijit Sarkar1, M. V. Kunte2, Venkata R. Sonti2
    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 249-268, 2011, DOI:10.3970/cmes.2011.081.249
    Abstract In this article, we show with some formalism that infinite flexible structural acoustic waveguides have a general form for the dispersion equation. The dispersion equation of all such waveguides should conform to a generic form. This allows us to bring out the common features of structural acoustic waveguides. We take three examples to demonstrate this fact, namely, the rectangular, the circular cylindrical and the elliptical geometries. Where necessary, the equations are simplified for applicability to a particular frequency-regime before demonstrating the conformance to the generic form of the dispersion relation. It is then shown that the coupled wavenumber solutions of… More >

  • Open Access

    ARTICLE

    A Hybrid of Interval Wavelets and Wavelet Finite Element Model for Damage Detection in Structures

    Jiawei Xiang1, Toshiro Matsumoto2, Yanxue Wang3, Zhansi Jiang4
    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 269-294, 2011, DOI:10.3970/cmes.2011.081.269
    Abstract Damages occurred in a structure will lead to changes in modal parameters (natural frequencies and modal shapes). The relationship between modal parameters and damage parameters (locations and depths) is very complicated. Single detection method using natural frequencies or modal shapes can not obtain robust damage detection results from the inevitably noise-contaminated modal parameters. To eliminate the complexity, a hybrid approach using both of wavelets on the interval (interval wavelets) method and wavelet finite element model-based method is proposed to detect damage locations and depths. To avoid the boundary distortion phenomenon, Interval wavelets are employed to analyze the finite-length modal shape… More >

  • Open Access

    ARTICLE

    Computation of the time-dependent Green's function of three dimensional elastodynamics in 3D quasicrystals

    V.G. Yakhno1, H.Çerdik Yaslan2
    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 295-310, 2011, DOI:10.3970/cmes.2011.081.295
    Abstract The time-dependent differential equations of elasticity for 3D quasicrystals are considered in the paper. These equations are written in the form of a vector partial differential equation of the second order with symmetric matrix coefficients. The Green's function is defined for this vector partial differential equation. A new method of the numerical computation of values of the Green's function is proposed. This method is based on the Fourier transformation and some matrix computations. Computational experiments confirm the robustness of our method for the computation of the time-dependent Green's function in icosahedral quasicrystals. More >

  • Open Access

    ARTICLE

    On application of the Stochastic Finite Volume Method in Navier-Stokes problems

    Marcin Kamiński1, Rafał Leszek Ossowski1
    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 311-334, 2011, DOI:10.3970/cmes.2011.081.311
    Abstract The main aim of this article is numerical solution of the fully coupled Navier-Stokes equations with Gaussian random parameters. It is provided thanks to the specially adopted Finite Volume Method, modified using the generalized stochastic perturbation technique. This Stochastic Finite Volume Method is applied to model 3D problem with uncertainty in liquid viscosity and a coefficient of the heat conduction, separately. Probabilistic moments and characteristics of up to the fourth order are determined with the use of the Response Function Method realized numerically via the polynomial inpterpolation. Although mathematical formulation of the SFVM has been proposed in addition to the… More >

  • Open Access

    ARTICLE

    Iterative Solution of a System of Nonlinear Algebraic Equations F(x) = 0, Using x· = λ[αR + βP] or x· = λ[αF + βP] R is a Normal to a Hyper-Surface Function of F, P Normal to R, and P* Normal to F

    Chein-Shan Liu1,2, Hong-Hua Dai1, Satya N. Atluri1
    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 335-363, 2011, DOI:10.3970/cmes.2011.081.335
    Abstract To solve an ill- (or well-) conditioned system of Nonlinear Algebraic Equations (NAEs): F(x) = 0, we define a scalar hyper-surface h(x,t) = 0 in terms of x, and a monotonically increasing scalar function Q(t) where t is a time-like variable. We define a vector R which is related to ∂h / ∂x, and a vector P which is normal to R. We define an Optimal Descent Vector (ODV): u = αR + βP where α and β are optimized for fastest convergence. Using this ODV [x· = λu], we derive an Optimal Iterative Algorithm (OIA) to solve F(x)More >

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