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  • Open AccessOpen Access

    ARTICLE

    Nonlinear Activation Functions in CNN Based on Fluid Dynamics and Its Applications

    Kazuhiko Kakuda1,*, Tomoyuki Enomoto1, Shinichiro Miura2
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 1-14, 2019, DOI:10.31614/cmes.2019.04676
    Abstract The nonlinear activation functions in the deep CNN (Convolutional Neural Network) based on fluid dynamics are presented. We propose two types of activation functions by applying the so-called parametric softsign to the negative region. We use significantly the well-known TensorFlow as the deep learning framework. The CNN architecture consists of three convolutional layers with the max-pooling and one fully-connected softmax layer. The CNN approaches are applied to three benchmark datasets, namely, MNIST, CIFAR-10, and CIFAR-100. Numerical results demonstrate the workability and the validity of the present approach through comparison with other numerical performances. More >

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    1703

  • Open AccessOpen Access

    ARTICLE

    Efficient Solution of 3D Solids with Large Numbers of Fluid-Filled Pores Using Eigenstrain BIEs with Iteration Procedure

    Donghong He1, Hang Ma2, *
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 15-40, 2019, DOI:10.31614/cmes.2019.04327
    Abstract To deal with the problems encountered in the large scale numerical simulation of three dimensional (3D) elastic solids with fluid-filled pores, a novel computational model with the corresponding iterative solution procedure is developed, by introducing Eshelby’s idea of eigenstrain and equivalent inclusion into the boundary integral equations (BIE). Moreover, by partitioning all the fluid-filled pores in the computing domain into the near- and the far-field groups according to the distances to the current pore and constructing the local Eshelby matrix over the near-field group, the convergence of iterative procedure is guaranteed so that the problem… More >

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    1127

  • Open AccessOpen Access

    ARTICLE

    Development of Non-Dissipative Direct Time Integration Method for Structural Dynamics Application

    Sun-Beom Kwon1, Jae-Myung Lee1,*
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 41-89, 2019, DOI:10.31614/cmes.2019.03879
    Abstract A direct time integration scheme based on Gauss-Legendre quadrature is proposed to solve problems in linear structural dynamics. The proposed method is a one-parameter non-dissipative scheme. Improved stability, accuracy, and dispersion characteristics are achieved using appropriate values of the parameter. The proposed scheme has second-order accuracy with and without physical damping. Moreover, its stability, accuracy, and dispersion are analyzed. In addition, its performance is demonstrated by the two-dimensional scalar wave problem, the single-degree-of-freedom problem, two degrees-of-freedom spring system, and beam with boundary constraints. The wave propagation problem is solved in the high frequency wave regime More >

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    1552

  • Open AccessOpen Access

    ARTICLE

    A Trajectory Planning-Based Energy-Optimal Method for an EMVT System

    Jiayu Lu1, Siqin Chang1,*
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 91-109, 2019, DOI:10.31614/cmes.2019.04190
    Abstract In this paper, a trajectory planning-based energy-optimal method is proposed to reduce the energy consumption of novel electromagnetic valve train (EMVT). Firstly, an EMVT optimization model based on state equation was established. Then, the Gauss pseudospectral method (GPM) was used to plan energy-optimal trajectory. And a robust feedforward-feedback tracking controller based on inverse system method is proposed to track the energy-optimal trajectory. In order to verify the effectiveness of the energy-optimal trajectory, a test bench was established. Finally, co-simulations based on MATLAB Simulink and AVL Boost were carried out to illustrate the effect of energy-optimal More >

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    3150

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    1162

  • Open AccessOpen Access

    ARTICLE

    LiToTac: An Interactive-Interface Software for Finite Element Analysis of Multiple Contact Dynamics

    Lei Peng1,2, Zhiqiang Feng1,2,*, Pierre Joli2, Christine Renaud2
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 111-137, 2019, DOI:10.31614/cmes.2018.04556
    Abstract In order to investigate the mechanical behavior of systems with complex architecture and a large number of contacting bodies, a finite element software, named LiToTac, has been developed by using the object-oriented programming technique. This software, with an interactive graphical user interface, is able to handle highly non-linear problems including multiple contacts and large deformation. More importantly, the contact detection based on a hybrid three-stages methodology can be performed automatically, which is more efficient than the common strategies of pre-defining contact zones in commercial FEM software like ANSYS, ABAQUS, etc. In addition, the contact solver More >

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    1626

  • Open AccessOpen Access

    ARTICLE

    Centrifuge Model Tests and Numerical Simulations of the Impact of Underwater Explosion on an Air-Backed Steel Plate

    Zhijie Huang1,2,3, Zuyu Chen1,2,3, Xiaodan Ren4,*, Jing Hu3, Xuedong Zhang3, Lu Hai4
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 139-155, 2019, DOI:10.31614/cmes.2019.04596
    Abstract Damage and threats to hydraulic and submarine structures by underwater explosions (UNDEXs) have raised much attention. The centrifuge model test, compared to prototype test, is a more promising way to examine the problem while reducing cost and satisfying the similitude requirements of both Mach and Froude numbers simultaneously. This study used a systematic approach employing centrifuge model tests and numerical simulations to investigate the effects of UNDEXs on an air-backed steel plate. Nineteen methodical centrifuge tests of UNDEXs were conducted. The shock wave pressure, bubble oscillation pressure, acceleration and the strain of the air-backed steel More >

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    1362

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    ARTICLE

    Model of CEL for 3D Elements in PDMs of Unidirectional Composite Structures

    Tianliang Qin1, Libin Zhao2,3,*, Jifeng Xu1, Fengrui Liu2,3,4, Jianyu Zhang5
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 157-176, 2019, DOI:10.31614/cmes.2019.04379
    Abstract Progressive damage models (PDMs) have been increasingly used to simulate the failure process of composite material structures. To accurately simulate the damage in each ply, 3D PDMs of composite materials have received more attention recently. A characteristic element length (CEL), which is an important dimensional parameter of PDMs for composite materials, is quite difficult to obtain for 3D elements, especially considering the crack directions during damage propagation. In this paper, CEL models for 3D elements in PDMs of unidirectional composite structures are presented, and their approximate formulae are deduced. The damage in unidirectional composite materials… More >

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    3149

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    1197

  • Open AccessOpen Access

    ARTICLE

    Effects of the Convex Topography on Railway Environmental Vibrations

    Huaxi Lu1,*, Zhicheng Gao1, Luyao Xu1, Bitao Wu1
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 177-205, 2019, DOI:10.31614/cmes.2019.04169
    Abstract The railway environmental vibration caused by high-speed railways is harmful to the human health, the structural safety of adjacent buildings, and the normal use of precision instruments. At the same time, it occurs frequently. In this case, the railway environmental vibration has drawn much attention with the rapid development of high-speed railways. Studies in Earthquake Engineering show that a convex topography has a great impact on ground vibrations, however, there is no consideration about the convex topographic effect in the study of the railway environmental vibration when the convex topography is near the roadway. In… More >

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    3496

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    1093

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    ARTICLE

    Estimating the Properties of Ground-Waste-Brick Mortars Using DNN and ANN

    Abdulkadir Karaci1,*, Hasbi Yaprak2, Osman Ozkaraca3, Ilhami Demir4, Osman Simsek5
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 207-228, 2019, DOI:10.31614/cmes.2019.04216
    Abstract In this study, deep-neural-network (DNN)- and artificial-neural-network (ANN)-based models along with regression models have been developed to estimate the pressure, bending and elongation values of ground-brick (GB)-added mortar samples. This study is aimed at utilizing GB as a mineral additive in concrete in the ratios 0.0%, 2.5%, 5.0%, 7.5%, 10.0%, 12.5% and 15.0%. In this study, 756 mortar samples were produced for 84 different series and were cured in tap water (W), 5% sodium sulphate solution (SS5) and 5% ammonium nitrate solution (AN5) for 7 days, 28 days, 90 days and 180 days. The developed… More >

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    3995

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    1256

  • Open AccessOpen Access

    ARTICLE

    A Novel Spacetime Collocation Meshless Method for Solving Two-Dimensional Backward Heat Conduction Problems

    Chihyu Liu1, Chengyu Ku1,2,*, Jingen Xiao1, Weichung Yeih1,2
    CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 229-252, 2019, DOI:10.31614/cmes.2019.04376
    Abstract In this article, a meshless method using the spacetime collocation for solving the two-dimensional backward heat conduction problem (BHCP) is proposed. The spacetime collocation meshless method (SCMM) is to derive the general solutions as the basis functions for the two-dimensional transient heat equation using the separation of variables. Numerical solutions of the heat conduction problem are expressed as a series using the addition theorem. Because the basis functions are the general solutions of the governing equation, the boundary points may be collocated on the spacetime boundary of the domain. The proposed method is verified by More >

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