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Chen J.,Chinese Academy of Sciences | Chen J.,University of California at Santa Barbara | Ming P.,Institute of Computational Mathematics and Scientific Engineering Computing | Yang J.Z.,Wuhan University
Communications in Computational Physics | Year: 2014

We introduce a newmultigrid method to study the lattice staticsmodel arising from nanoindentation. A constrained Cauchy-Born elasticity model is used as the coarse-grid operator. This method accelerates the relaxation process and considerably reduces the computational cost. In particular, it saves quite a bit when dislocations nucleate and move, as demonstrated by the simulation results. ©2014 Global-Science Press. Source

Li X.,Pennsylvania State University | Ming P.,Institute of Computational Mathematics and Scientific Engineering Computing
Multiscale Modeling and Simulation | Year: 2014

We study three quasi-continuum approximations of a lattice model for crack propagation. The influence of the approximation on the bifurcation patterns is investigated. The estimate of the modeling error is applicable to near and beyond bifurcation points, which enables us to evaluate the approximation over a finite range of loading and multiple mechanical equilibria. © 2014 Society for Industrial and Applied Mathematics Source

Huang X.,CAS Institute of Automation | Gong L.,Institute of Computational Mathematics and Scientific Engineering Computing
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

Separating a foreground layer from stereo video in real-time is used in many applications such as live background substitution. Conventional separating models using stereo, contrast or color alone are usually not accurate enough to be satisfactory. Furthermore, the powerful tool of graph cut which is well suited for segmentation is known to be not efficient enough especially for high resolution images. In this paper, we conquer these difficulties by fusing stereo with color and contrast to model the segmentation problem as an minimum cut problem of a planar graph and solving it by a specialized algorithm, parametric shortest paths [8] with a dynamic tree structure, in O(nlogn) time. Experimental results demonstrate the high accuracy and efficiency of the algorithm. © 2011 Springer-Verlag Berlin Heidelberg. Source

Ma Y.,Jiangxi Normal University | Kong L.,Jiangxi Normal University | Hong J.,Institute of Computational Mathematics and Scientific Engineering Computing | Cao Y.,Jiangxi Normal University
Computers and Mathematics with Applications | Year: 2011

In this paper, we develop a new kind of multisymplectic integrator for the coupled nonlinear Schrdinger (CNLS) equations. The CNLS equations are cast into multisymplectic formulation. Then it is split into a linear multisymplectic formulation and a nonlinear Hamiltonian system. The space of the linear subproblem is approximated by a high-order compact (HOC) method which is new in multisymplectic context. The nonlinear subproblem is integrated exactly. For splitting and approximation, we utilize an HOCSMS integrator. Its stability and conservation laws are investigated in theory. Numerical results are presented to demonstrate the accuracy, conservation laws, and to simulate various solitons as well, for the HOCSMS integrator. They are consistent with our theoretical analysis. © 2010 Elsevier Ltd. All rights reserved. Source

Ren H.-R.,Zhejiang University | Huang G.-H.,Institute of Computational Mathematics and Scientific Engineering Computing | Wang H.-Z.,Tongji University | Chen S.-C.,Zhejiang University
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2013

In this paper, we summarize the influence of Hessian operator in seismic inversion methods and review the mathematical and physical meanings of the Hessian operator in the seismic inversion imaging. Hessian operator is the second derivation of the misfit function to the seismic model parameters. It can be seen by analyzing its Green's function formulation under the acoustic wave approximation that the Hessian reflects the effects of the seismic acquisition system and wavelet frequency band during the projection of information from the data spaces to the model spaces. We propose two pseudo-Hessian forms for the least-squares migration and the full waveform inversion separately. The application of plane-wave Hessian operator can lead to an amplitude-preserved migration result. The sub-offset Hessian can be used to the full waveform inversion to enhance the efficiency of inversion. At last, we discuss and evaluate the Hessian operator in seismic inversion imaging. Source

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