Sang-Ri Yi¹, Boyoung Kim², Jun Won Kang^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.2, pp. 77-104, 2015, DOI:10.3970/cmes.2015.106.077

Abstract This study is concerned with the development of new mixed unsplitfield perfectly matched layers (PMLs) for the simulation of plane electromagnetic waves in heterogeneous unbounded domains. To formulate the unsplit-field PML, a complex coordinate transformation is introduced to Maxwell's equations in the frequency domain. The transformed equations are converted back to the time domain via the inverse Fourier transform, to arrive at governing equations for transient electromagnetic waves within the PML-truncated computational domain. A mixed finite element method is used to solve the PML-endowed Maxwell equations. The developed PML method is relatively simple and straightforward More >

Ying Zhang¹, Lin Du¹, Xiaole Yue¹, Qun Han¹, Tong Fang²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.1, pp. 37-51, 2015, DOI:10.3970/cmes.2015.106.037

Abstract The symmetry breaking bifurcation (SBB) phenomenon in a deterministic parameter Duffing system (DP-DS) is well known, yet the problem how would SBB phenomenon happen in a Duffing system with random parameter (RP-DS) is still open. For comparison study, the results for DP-DS are summarized at first: in short, SBB in DP-DS is just a transition of response phase trajectories from a single self-symmetric one about the origin into two mutual symmetric once, or vice versa. However, in DP-DS case, the two mutual symmetric phase trajectories are never commutable. In view of every sample of RP-DS… More >

H.Q. Nguyen¹, C.-D. Tran¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.5, pp. 399-439, 2015, DOI:10.3970/cmes.2015.105.399

Abstract In this paper, dynamic behaviours of dilute polymer solutions of various bead-spring chain models in shear flow are studied using a coarse-grained method based on the Integrated Radial Basis Function Networks (IRBFNs) and stochastic technique. The velocity field governed by the macroscopic conservation equations is determined by the IRBFN-based method, whereas the evolution of configurations of polymer chains governed by the diffusion stochastic differential equations are captured by the Brownian Configuration Field (BCF) approach. The system of micro-macro equations is closed by the Kramers’ expression, which allows for the determination of the polymer stresses in More >

Delfim Soares Jr.¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.5, pp. 341-360, 2015, DOI:10.3970/cmes.2015.105.341

Abstract In this work, a second-order time-marching procedure for dynamics is discussed, in which enhanced accuracy is enabled. The new technique is unconditionally stable (according to its parameter selection), it has no amplitude decay or overshooting, and it provides reduced period elongation errors. The method is based on displacement-velocity relations, requiring no computation of accelerations. It is efficient, simple and very easy to implement. Numerical results are presented along the paper, illustrating the good performance of the proposed technique. As it is described here, the new method has no drawbacks when compared to the Trapezoidal Rule More >

C.M.T. Tien¹, N. Thai-Quang¹, N. Mai-Duy¹, C.-D. Tran¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.4, pp. 301-340, 2015, DOI:10.3970/cmes.2015.105.301

Abstract In this study, we present a numerical discretisation scheme, based on a direct fully coupled approach and compact integrated radial basis function (CIRBF) approximations, to simulate viscous flows in regular/irregular domains. The governing equations are taken in the primitive form where the velocity and pressure fields are solved in a direct fully coupled approach. Compact local approximations, based on integrated radial basis functions, over 3-node stencils are introduced into the direct fully coupled approach to represent the field variables. The present scheme is verified through the solutions of several problems including Poisson equations, Taylor-Green vortices More >

Foad Nazari¹, Mohammad Hossein Abolbashari^1,2, Seyed Mahmoud Hosseini³

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.4, pp. 271-299, 2015, DOI:10.3970/cmes.2015.105.271

Abstract Present study is concerned with three dimensional natural frequency analysis of functionally graded sandwich rectangular plates using Meshless Local Petrov-Galerkin (MLPG) method and Artificial Neural Networks (ANNs).The plate consists of two homogeneous face sheets and a power-law FGM core. Natural frequencies of the plate are obtained by 3D MLPG method and are verified with available references. Convergence study of the first four natural frequencies for different node numbers is the next step. Also, effects of two parameters of “FG core to plate thickness ratio” and “volume fraction index” on natural frequencies of plate are investigated. More >

Hai-Kun Wang^1,2, Robert Haynes³, Hong-Zhong Huang¹, Leiting Dong^2,4, Satya N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.1, pp. 1-24, 2015, DOI:10.3970/cmes.2015.105.001

Abstract In this paper, we propose an approach for diagnostics and prognostics of damaged aircraft structures, by combing high-performance fatigue mechanics with filtering theories. Fast & accurate deterministic analyses of fatigue crack propagations are carried out, by using the Finite Element Alternating Method (FEAM) for computing SIFs, and by using the newly developed Moving Least Squares (MLS) law for computing fatigue crack growth rates. Such algorithms for simulating fatigue crack propagations are embedded in the computer program Safe- Flaw, which is called upon as a subroutine within the probabilistic framework of filter theories. Both the extended… More >

Liming Yang¹, Yongping Gao², Qun Sun³

CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.6, pp. 493-506, 2015, DOI:10.3970/cmes.2015.104.493

Abstract Minimax probability machine (MPM) has been recently proposed and shown its advantage in pattern recognition. In this paper, we present a new minimax probabilistic approach (MPA),which can provide an explicit lower bound on prediction accuracy. Applying the Chebyshev-Cantelli inequality, the MPA is posed as a second order cone program formulation and solved effectively. Following that, this method is exploited directly to recognize the purity of hybrid seeds using near-infrared spectroscopic data. Experimental results in different spectral regions show that the proposed MPA is competitive with the existing minimax probability machine and support vector machine in More >

Wang Yang^1,2, Juanjuan Li¹, Jian Yang^1,3, Lin Wei⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.6, pp. 471-491, 2015, DOI:10.3970/cmes.2015.104.471

Abstract Harvesting is the most difficult and costly operation in cassava production. Currently, most cassava harvest still depends on manual tools. Effective mechanized harvesters are necessary to improve harvesting quality and reduce production cost. Therefore, it is very important to figure out key information for designing an effective tuber lifting system used in bionic “dig-pull” harvesters. A numerical simulation model of human-stem-tuber-soil system was developed to carry out numerical simulation of manually pulling tuber. Coupling algorithm of Lagrange and smoothed particle hydrodynamics (SPH) was used in the model. Lifting mechanism of experienced farmer was studied at… More >

C.M.T. Tien¹, N. Thai-Quang¹, N. Mai-Duy¹, C.-D. Tran¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.6, pp. 425-469, 2015, DOI:10.3970/cmes.2015.104.425

Abstract In this paper, we propose a three-point coupled compact integrated radial basis function (CCIRBF) approximation scheme for the discretisation of second-order differential problems in one and two dimensions. The CCIRBF employs integrated radial basis functions (IRBFs) to construct the approximations for its first and second derivatives over a three-point stencil in each direction. Nodal values of the first and second derivatives (i.e. extra information), incorporated into approximations by means of the constants of integration, are simultaneously employed to compute the first and second derivatives. The essence of the CCIRBF scheme is to couple the extra… More >