K. Kuramoto¹, M. Furuichi², K. Kakuda²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 169-186, 2015, DOI:10.3970/cmes.2015.106.169

Abstract This paper describes a scheme to improve efficiency of multi-agent simulation system (MAS) on single computer that has multiple processor cores. Simulation technology is applied for broad usage in the world, and MAS gathers attention from the fields that treat complicated and non-numeric issues such as traffic analysis, analyzing evacuation from a building, and defense training. Since the requirements of simulation scale and fidelity are growing, the importance of their performance is also increasing. However, CPU clock speedup is slowing, and improvement of computer performance has come to depend on the number of processors, cores,… More >

S. Masuri¹, K. K. Tamma²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.3, pp. 147-168, 2015, DOI:10.3970/cmes.2015.106.147

Abstract The objective in this paper is to extend the previously developed twoparameter GS4-1 (Generalized Single System Single Solve for 1st order transient systems) computational framework from parabolic to hyperbolic type of applications pertaining to first order linear transient systems. In particular, attention is paid to the selective control feature inherit in the framework, which is the new feature that enables different amounts of high frequency damping for the primary variable and its time derivative, allowing for physically accurate solutions of all variables in the system. This is in contrast to having only limited, often indiscriminate, More >

J. E. Sebold¹, L. A. Lacerda², J. A. M. Carrer³

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.2, pp. 127-145, 2015, DOI:10.3970/cmes.2015.106.127

Abstract This paper deals with a Finite Element Method (FEM) for the approximation of the Helmholtz equation for two dimensional problems. The acoustic boundary conditions are weakly posed and an auxiliary problem with homogeneous boundary conditions is defined. This auxiliary approach allows for the formulation of a general solution method. Second order finite elements are used along with a discretization parameter based on the fixed wave vector and the imposed error tolerance. An explicit formula is defined for the mesh size control parameter based on Padé approximant. A parametric analysis is conducted to validate the rectangular More >

T. Lahmer¹, J. Ilg², R. Lerch²

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.2, pp. 105-126, 2015, DOI:10.3970/cmes.2015.106.105

Abstract In the recent years many publications appeared putting emphasis on the simulation-based identification of piezoelectric material parameters from electrical or mechanical measurements and combinations of them. By experience, one is aware of the importance of a single input parameter. However, it is not yet fully understood and in particular quantified to which extend missing knowledge in the single parameters (parameter uncertainty) influences the quality of the model's prognosis. In this paper, we adapt and apply variance-based sensitivity measures to models describing the piezoelectric effect in the linear case and derive global information about the single More >

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 >

Juan Blandon¹, Shinji Takaba², Toru Omae², Naoki Osawa¹, Hidekazu Murakawa³

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.1, pp. 53-75, 2015, DOI:10.3970/cmes.2015.106.053

Abstract Bending deformation of U-rib by gas heating is investigated using Thermal Elastic Plastic FEA employing an accurate heat source model. To validate our computational model, comparison between numerical analysis and experimental measurements are carried out. Good agreement is obtained for both temperature and deformation measurements. Inherent deformation method is employed to evaluate the overall behavior of U-rib under the influence of heating location and heating speed. Based on the prediction by FEA and using the inherent deformation method a new mathematical model describing the deformation of the U-rib is developed and evaluated for different combinations 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 >

Guochun Xu¹, S Yan², Q.W. Ma^1,2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.1, pp. 1-35, 2015, DOI:10.3970/cmes.2015.106.001

Abstract In the Meshless Local Petrove-Galerkin based on Rankine source solution (MLPG-R), a simplified finite difference interpolation (SFDI) scheme was developed for numerical interpolation and gradient calculation (CMES, Vol. 23(2), pp. 75-89). Numerical tests concluded that the SFDI is generally as accurate as the linear moving least square method (MLS) but requires less CPU time. In this paper, a modified SFDI is proposed for numerically modelling of nonlinear water waves, considering the typical feature of the spatial variation of the wave-related parameters. Systematic numerical investigations are carried out and the results indicate that the modification considerably More >

Chia-Ming Fan^1,2, Yu-Kai Huang¹, Po-Wei Li¹, Ying-Te Lee¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.6, pp. 491-515, 2015, DOI:10.3970/cmes.2015.105.491

Abstract In this paper, the boundary knot method (BKM) is adopted for accurately analyzing two-dimensional Stokes flows, dominated by viscous force and pressure gradient force. The Stokes flows, which denoted the flow fields with extremely viscous fluid or with very small velocity, appear in various engineering applications, such that it is very important to develop an efficient and accurate numerical method to solve the Stokes equations. The BKM, which can avoid the controversial fictitious boundary for sources, is an integral-free boundary-type meshless method and its solutions are expressed as linear combinations of nonsingular general solutions for More >

B. J. Zhu^1,2, Z. X. Hou¹, Y. F. Lu¹, S. Q. Shan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.6, pp. 467-490, 2015, DOI:10.3970/cmes.2015.105.467

Abstract This paper mainly analyzes the dynamic soaring of UAV utilizing gradient wind. Dynamic soaring is an efficient path in which UAV absorbs energy from environment to enhance its flight endurance. A set of three-dimensional point dynamic equations for a soaring aircraft in three degrees of freedom is used in calculations. To simplify the calculation, the gradient wind’s direction is taken into decomposition. The notion of trajectory subsection analysis is applied to account for the energy transformation mechanism during the dynamic soaring, and the zone of direction is converted into cutting-in angle, which is regarded as More >