Tao Cui¹, Wenhao Liao¹ and Daren Yu ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.3, pp. 273-294, 2009, DOI:10.3970/cmes.2009.045.273

Abstract Aerodynamic hysteresis is of practical importance for the flying airfoils. Motivated by the problem of global description on the hysteresis behaviors, this paper proposes a topological approach to analyze and model the hysteresis behaviors exhibited in the airfoil flow from a viewpoint of dynamic system theory. The approach is based on the topological invariant rules of singular points under topological mapping. It is able to theoretically explain such discontinuous hysteresis phenomena, and make consistent and accurate predictions of the hysteresis behaviors in the airfoil flow. The model results have shown that the present model is More >

Moe M. S. Cheung¹, Zhenyuan Shen², Ben Y.B. Chan³

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.2, pp. 155-178, 2009, DOI:10.3970/cmes.2009.045.155

Abstract In view of the urgent need for an efficient and accurate structural analysis method in bridge design practice, this paper introduces a total integrated analytical solution for multi-span, continuous slab-on-girder and box girder bridges, by modeling the bridge deck and the piers together, using the finite strip method (FSM). FSM has been well accredited for its efficiency in the structural analysis of bridges, reducing the time required for data input and analysis without affecting the degree of accuracy. By using a continuously differentiable smooth series in the longitudinal direction, a complex 3D problem is reduced… More >

M. Trikha¹, S. Gopalakrishnan², D. Roy Mahapatra^2,1, R. Pandiyan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.2, pp. 97-140, 2009, DOI:10.3970/cmes.2009.045.097

Abstract A mechanics based linear analysis of the problem of dynamic instabilities in slender space launch vehicles is undertaken. The flexible body dynamics of the moving vehicle is studied in an inertial frame of reference, including velocity induced curvature effects, which have not been considered so far in the published literature. Coupling among the rigid-body modes, the longitudinal vibrational modes and the transverse vibrational modes due to asymmetric lifting-body cross-section are considered. The model also incorporates the effects of aerodynamic forces and the propulsive thrust of the vehicle. The effects of the coupling between the combustion… More >

Alexandre de Castro^1,2, Carlos Frederico Fronza², Domingos Alves^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.1, pp. 83-96, 2009, DOI:10.3970/cmes.2009.045.083

Abstract Immunological systems have been an abundant inspiration to contemporary computer scientists. Problem solving strategies, stemming from known immune system phenomena, have been successfully applied to chall enging problems of modern computing. Simulation systems and mathematical modeling are also beginning use to answer more complex immunological questions as immune memory process and duration of vaccines, where the regulation mechanisms are not still known sufficiently (Lundegaard, Lund, Kesmir, Brunak, Nielsen, 2007). In this article we studiedin machinaa approach to simulate the process of antigenic mutation and its implications for the process of memory. Our results have suggested More >

Francisco P. M. Oliveira¹, João Manuel R. S. Tavares¹

CMES-Computer Modeling in Engineering & Sciences, Vol.43, No.1, pp. 91-110, 2009, DOI:10.3970/cmes.2009.043.091

Abstract This paper presents a new methodology to establish the best global match of objects' contours in images. The first step is the extraction of the sets of ordered points that define the objects' contours. Then, by using the curvature value and its distance to the corresponded centroid for each point, an affinity matrix is built. This matrix contains information of the cost for all possible matches between the two sets of ordered points. Then, to determine the desired one-to-one global matching, an assignment algorithm based on dynamic programming is used. This algorithm establishes the global More >

E. J. Sellountos¹, A. Sequeira¹, D. Polyzos²

CMES-Computer Modeling in Engineering & Sciences, Vol.41, No.3, pp. 215-242, 2009, DOI:10.3970/cmes.2009.041.215

Abstract A Meshless Local Petrov-Galerkin (MLPG) method based on Local Boundary Integral Equation (LBIE) techniques is employed here for the solution of transient elastic problems with damping. The Radial Basis Functions (RBF) interpolation scheme is exploited for the meshless representation of displacements throughout the computational domain. On the intersections between the local domains and the global boundary, tractions are treated as independent variables via conventional boundary interpolation functions. The MLPG(LBIE)/RBF method is applied to both transient and steady-state Fourier transform elastodynamic domains. In both cases the LBIEs employ the simple elastostatic fundamental solution instead of the More >

Hung-Chang Lee¹, Chein-Shan Liu²

CMES-Computer Modeling in Engineering & Sciences, Vol.41, No.1, pp. 1-26, 2009, DOI:10.3970/cmes.2009.041.001

Abstract The group-preserving schemes developed by Liu (2001) for integrating ordinary differential equations system were adopted the Cayley transform and Padé approximants to formulate the Lie group from its Lie algebra. However, the accuracy of those schemes is not better than second-order. In order to increase the accuracy by employing the group-preserving schemes on ordinary differential equations, according to an efficient technique developed by Runge and Kutta to raise the order of accuracy from the Euler method, we combine the Runge-Kutta method on the group-preserving schemes to obtain the higher-order numerical methods of group-preserving type. They More >

X.G. Yuan^1,2, H.W. Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.40, No.3, pp. 201-224, 2009, DOI:10.3970/cmes.2009.040.201

Abstract The radially symmetric motion of the pre-existing micro-void centered at an incompressible hyperelastic sphere under the dynamic surface tensile loads relating to time is investigated in this paper. Some interesting conclusions are obtained by qualitatively analyzing the solutions of the motion equation of micro-void in detail; meanwhile, numerical simulations are used for understanding the obtained conclusions. In particular, it is proved that the motion of the micro-void with time would present a nonlinearly periodic oscillation if the values of the constant tensile load, the material and the structure parameters are given and that the oscillation More >

Chun-Lang Yeh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 179-200, 2009, DOI:10.3970/cmes.2009.039.179

Abstract In this research, the atomization process of a nanojet is investigated by molecular dynamics simulation. Liquid argon nanojet made of 44000 Lennard-Jones molecules is examined under various simulation parameters to study their influence on the nanojet atomization process. Snapshots of the molecules, evolution of the density field, and evolution of the intermolecular force are analyzed. The present simulation results can provide insight into the fundamental mechanism of the atomization process and will be helpful for the design of nanojet devices such as nano-printer or nano-sprayer. More >

D. S. Liu¹, C.Y. Tsai¹

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.1, pp. 29-48, 2009, DOI:10.3970/cmes.2009.039.029

Abstract Utilizing a thin copper substrate for illustration purposes, this study presents a novel numerical method for extracting the thermo-mechanical properties of a thin-film. In the proposed approach, molecular dynamics (MD) simulations are performed to establish the load-displacement response of a thin copper substrate nanoindented at temperatures ranging from 300~1400 K. The load data are then input to an artificial neural network (ANN), trained using a finite element model (FEM), in order to extract the material constants of the copper substrate. The material constants are then used to construct the corresponding stress-strain curve, from which the… More >