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  • Open Access


    Dynamic Anti-plane Crack Analysis in Functional Graded Piezoelectric Semiconductor Crystals

    J. Sladek1,2, V. Sladek1, E. Pan3, D.L. Young4

    CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.4, pp. 273-296, 2014, DOI:10.3970/cmes.2014.099.273

    Abstract This paper presents a dynamic analysis of an anti-plane crack in functionally graded piezoelectric semiconductors. General boundary conditions and sample geometry are allowed in the proposed formulation. The coupled governing partial differential equations (PDEs) for shear stresses, electric displacement field and current are satisfied in a local weak-form on small fictitious subdomains. The derived local integral equations involve one order lower derivatives than the original PDEs. All field quantities are approximated by the moving least-squares (MLS) scheme. After performing spatial integrations, we obtain a system of ordinary differential equations for the involved nodal unknowns. It is noted that the stresses… More >

  • Open Access


    A Meshfree Method For Mechanics and Conformational Change of Proteins and Their Assemblies

    Ankush Aggarwal1, Jiun-Shyan Chen2, William S. Klug3

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.1, pp. 69-99, 2014, DOI:10.3970/cmes.2014.098.069

    Abstract Mechanical properties of proteins play an important role in their biological function. For example, microtubules carry large loads to transport organelles inside the cell, and virus shells undergo changes in shape and mechanical properties during maturation which affect their infectivity. Various theoretical models including continuum elasticity have been applied to study these structural properties, and a significant success has been achieved. But, the previous frameworks lack a connection between the atomic and continuum descriptions. Here this is accomplished through the development of a meshfree framework based on reproducing kernel shape functions for the large deformation mechanics of protein structures. The… More >

  • Open Access


    Vibration Control and Separation of a Device Scanning an Elastic Plate

    Shueei-Muh Lin1, Min-Jun Teng2

    CMES-Computer Modeling in Engineering & Sciences, Vol.103, No.3, pp. 189-213, 2014, DOI:10.3970/cmes.2014.103.189

    Abstract The control and separation of a scanning device moving along an arbitrary trajectory on an elastic plate is investigated. The system is a moving mass problem and is difficult to analyze directly. A semi-analytical method for the movingmass model is presented here. Without vibration control, the separation of a vehicle from a plate is likely to happen. The mechanism of separation of a vehicle from a plate is studied. Moreover, the effects of several parameters on vibration separation and the critical speed of system are studied. An effective control methodology is proposed for suppressing vibration and separation This model is… More >

  • Open Access


    Coupled ABC and Spline Collocation Approach for a Class of Nonlinear Boundary Value Problems over Semi-Infinite Domains

    S.A. Khuri1, A. Sayfy1

    CMES-Computer Modeling in Engineering & Sciences, Vol.101, No.2, pp. 81-96, 2014, DOI:10.3970/cmes.2014.101.081

    Abstract In this article, we introduce a numerical scheme to solve a class of nonlinear two-point BVPs on a semi-infinite domain that arise in engineering applications and the physical sciences. The strategy is based on replacing the boundary condition at infinity by an asymptotic boundary condition (ABC) specified over a finite interval that approaches the given value at infinity. Then, the problem complimented with the resulting ABC is solved using a fourth order spline collocation approach constructed over uniform meshes on the truncated domain. A number of test examples are considered to confirm the accuracy, efficient treatment of the boundary condition… More >

  • Open Access


    Numerical Approximate Solutions of Nonlinear Fredholm Integral Equations of Second Kind Using B-spline Wavelets and Variational Iteration Method

    P. K. Sahu1, S. Saha Ray1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.2, pp. 91-112, 2013, DOI:10.3970/cmes.2013.093.091

    Abstract In this paper, nonlinear integral equations have been solved numerically by using B-spline wavelet method and Variational Iteration Method (VIM). Compactly supported semi-orthogonal linear B-spline scaling and wavelet functions together with their dual functions are applied to approximate the solutions of nonlinear Fredholm integral equations of second kind. Comparisons are made between the variational Iteration Method (VIM) and linear B-spline wavelet method. Several examples are presented to compare the accuracy of linear B-spline wavelet method and Variational Iteration Method (VIM) with their exact solutions. More >

  • Open Access


    Electrostatic potential in a bent flexoelectric semiconductive nanowire

    Ying Xu1, Shuling Hu1, Shengping Shen1

    CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.5, pp. 397-408, 2013, DOI:10.3970/cmes.2013.091.397

    Abstract Flexoelectricity presents a strong size effect, and should not be ignored for nanodevices. In this paper, the flexoelectric effect is taken into account to investigate the electrostatic potential distribution in a bent flexoelectric semiconductive nanowire, and the numerical solution is obtained by using the finite difference method. The effect of donor concentration on the electrostatic potential are also investigated. The results show that, the flexoelectricity increases the value of the voltage on the cross section. The flexoelectric effect is varied with the size, i.e. when the radius of the nanowire is small the flexoelectric effect is significant. It is also… More >

  • Open Access


    Study on a Ranging System Based on Dual Solenoid Assemblies, for Determining the Relative Position of Two Adjacent Wells

    Binbin Diao1, Deli Gao1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.1, pp. 77-90, 2013, DOI:10.3970/cmes.2013.090.077

    Abstract The measurement of the relative position of two adjacent wells is one of the key technologies in the directional drilling of twin parallel horizontal wells, and the downhole intersection of two adjacent wells. A new electromagnetic ranging system and a guidance method are introduced for determining the relative position of two adjacent wells. The system mainly consists of two solenoid assemblies, improved surveying instrument for measurement while drilling (MWD), and a computational procedure for guidance. Also, the distribution of the magnetic field of each energized solenoid assembly is discussed, by regarding the solenoid assembly as two independent oscillating magnetic dipoles.… More >

  • Open Access


    An Analysis of the Bottomhole Assembly (BHA) in Directional Drilling, by Considering the Effects of the Axial Displacement

    Zonglu Guo1, Deli Gao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.1, pp. 65-76, 2013, DOI:10.3970/cmes.2013.090.065

    Abstract The modeling of the bottomhole assembly (BHA) is an essential problem in directional drilling. Some basic equations for predicting the performance of the BHA are presented in this paper. These equations take into account the effects of the axial displacement. The method of weighted residuals and the Newton-Raphson iterations are used to compute the nonlinear effects of the deformation of the BHA. A computer program is developed for the analysis of the BHA in order to quantitatively predict the performance of the BHA in directional drilling. In addition, a case study is presented to evaluate the effect of the axial… More >

  • Open Access


    On Appropriately Matching the Bottomhole Pendulum Assembly with the Anisotropic Drill Bit, to Control the Hole-Deviation

    Deli Gao1, Zhen Dong1, Hui Zhang1

    CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.2, pp. 111-122, 2012, DOI:10.3970/cmes.2012.089.111

    Abstract The bottom hole pendulum assembly is a type of bottom hole assembly (BHA) for controlling the hole deviation, and has been widely used in drilling engineering. Generally, the ability of the drill bit to penetrate laterally, is different from its ability to penetrate axially, so that the drill bit has an anisotropy which affects the hole-deviation-control characteristics of the BHA. The tilt angle and the side force of the drill bit are obtained by a BHA analysis based on the method of weighted residuals. Thus, the effective drilling force can be determined using the rock-bit interaction model. On this basis,… More >

  • Open Access


    Dynamic Modeling and Analysis of Arch Bridges Using Beam-Arch Segment Assembly

    Wei-Xin Ren1,2,3, Cong-Cong Su1, Wang-Ji Yan1

    CMES-Computer Modeling in Engineering & Sciences, Vol.70, No.1, pp. 67-92, 2010, DOI:10.3970/cmes.2010.070.067

    Abstract A beam-arch segment assembly procedure is presented in this paper for the dynamic modelling and analysis of arch bridges. Such a beam-arch segment assembly is composed of different structural elements of arch bridges such as arch ribs (curved beams), suspenders, girders and floor beams. Based on the energy principle in structural dynamics, the stiffness matrix and mass matrix of such an assembly are formulated. The proposed procedure is then implemented to carry out the free vibration analysis of the Jian concrete filled tubular arch bridge. It is demonstrated that the proposed beam-arch segment assembly procedure is efficient with the advantages… More >

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