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ON THE UNIQUENESS THEOREMS FOR THE UNBOUNDED CLASSICAL SOLUTION OF THE MAGNETIC BNARD SYSTEM

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Systems Science and Mathematical Sciences 2000年第3期13卷 277-284页

作者： MIAO Changxing(institute of applied {2. and computational Mathematics, Beijing 100088, china) 北京应用物理与计算数学所北京 100088

In this note we prove two theorems on the uniqueness of unbounded classical solutions of the magnetic Benard system which includes the classical Navier-Stokes equation, the Boussinesq equation and the magnetohydrodyna... 详细信息

关键词： The magnetic Bénard system classical solution uniqueness

Numerical and experimental investigation of the fracture behavior of shock loaded alumina

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Science china(physics,Mechanics & Astronomy) 2010年第2期53卷 244-252页

作者： REN HuiLan1,SHU XueFeng2.& LI Ping3 1 State Key Laboratory of Explosion Science and Technology,Beijing institute of Technology,Beijing 100081,china 2.institute of applied Mechanics and Biomedical Engineering,Taiyuan University of Technology,Taiyuan 03002.,china 3 Labroratory for Shock Wave and Detonation physics Research,institute of Fluid physics,CAEP,Mianyang 610059,china 1. State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China2. Institute of Applied Mechanics and Biomedical Engineering Taiyuan University of Technology Taiyuan 030024 China3. Labroratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics CAEP Mianyang 610059 China

Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A ve-locity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit and the free surface velocity profile,which consists of an elastic wave followed immediately by a dispersive inelastic wave. The stress histories under different impact velocities are measured by in-material manganin gauges. Based on the experimental data a Hugoniot curve is fitted,which shows the compressive characteristics that alumina changes typically from elastic to "plastic" ,and under higher pressure it will be transferred to similar-fluid state. The turning point of the Hugoniot curve from a high pressure region to a low pressure region is about 11.4 GPa. The fracture process of alumina is simulated by way of finite element code. After the analysis of the fracture mechanism,the numerical results show an important role played by the nucleation and the growth of the cracks in the macro-scopic fracture of the alumina target. The numerical predictions of stress histories are compared with the experimental results,which indicates consistency between them.

关键词： plate impact experiment hugoniot curve fracture characteristics numerical simulation

H^m-Modified Wave Operator for Nonlinear Hartree Equation in Space of Dimension n≥2

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Acta Mathematica Sinica,English Series 1997年第2期13卷 247-268页

作者： Miao Changxing (institute of applied {2. and computational Mathematics,Beijing 100088,china) institute of applied {2. and computational Mathematics

We consider the scattering problem for the Hartree equation with potential|x|-1in a space of dimension n≥*** prove the existence of Hm-modified wave operator for Hartree equation on a dense set of a neighborhood of zero in Hm（Rn）,meanwhile,we obtain also the global existence for the Cauchy problem of Hartree equation in a space of dimension n≥2.

关键词： Hartree equation Cauchy problem Modified wave operator

An eSnake model for medical image segmentation

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Progress in Natural Science:Materials International 2005年第5期15卷 424-429页

作者： Lv Hongyu1, YUAN Kehong2. BAO Shanglian1, ZU Donglin1 and DUAN Chaijie1*(1. The Research Center for Tumor Diagnosis and Therapeutical physics & Beijing Key Laboratory of Medical physics and Engineering, Beijing 100871,{2. 2. Key Laboratory of Pure and applied Mathematics, School of Mathematical Sciences, Peking University, Beijing 100871,{2.) The Research Center for Tumor Diagnosis and Therapeutical physics & Beijing Key Laboratory of Medical physics and Engineering Beijing 100871 China Key Laboratory of Pure and applied Mathematics School of Mathematical Sciences Peking University Beijing 100871 China

A novel scheme of external force for detecting the object boundary of medical image based on Snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our Snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent Snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.

关键词： image segmentation eSnake external force electrostatic field balloon force.

A SINGLESTEP CHARACTERISTIC FINITE DIFFERENCE METHOD FOR TWO-DIMENSIO NALNON LINEAR CONVECTION-DIFFUSIONPROBLEMS

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Systems Science and Mathematical Sciences 1999年第S1期12卷 110-121页

作者： YU Xijun(Laboratory of computational physics, {2. of applied physics and computationalMathematics, Beijing 100088, china)

A singlestep characteristic finite difference method is given based on the linear and quadratic interpolations for solving two-dimensional nonlinear convection-diffusionproblems. The convergence of approximate solutions is obtained in L2.under milder restrictions in the temporal stepsize and spatial stepsize than those required in [1].

关键词： Two-dimensional nonlinear convection-diffusion problems a singlestep characteristic difference method convergence error estimate.

The mechanism of breakdown in laminar-turbulent transition of a supersonic boundary layer on a flat plate-temporal mode

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Science china(physics,Mechanics & Astronomy) 2005年第5期48卷 614-625页

作者： HUANG Zhangfeng 1, CAO Wei 1,2.& ZHOU Heng 1,2.1. Department of Mechanics, Tianjin University, Tianjin 300072. china 2. Liu-Hui Center of applied Mathematics, Nankai University and Tianjin University, Tianjin 300072. china 1. Department of Mechanics Tianjin University 300072 Tianjin China 2. Liu-Hui Center of applied Mathematics Nankai University and Tianjin University 300072 Tianjin China

Temporal mode direction numerical simulation has been done for the transition of a supersonic boundary layer on a flat plate with Mach number 4.5. Analysis of the result showed that during the breakdown process in laminar-turbulent transition, the mechanism causing the mean flow profile to evolve swiftly from laminar to turbulent was that the modification of mean flow profile by the disturbances,when they became larger,led to a remarkable change of its stability characteristics. Though the most unstable T-S wave was of second mode for laminar flow, the first mode waves played the key role in the breakdown process in laminar-turbulent transition.

关键词： supersonic boundary layer, transition, breakdown.

A LAX-WENDROFF TYPE SCHEME WITH PREDICTOR-CORRECTOR

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计算物理 1991年第1期 95-101页

作者： Xu Guorong(institute of applied {2. and computational Mathematics. Beijing)

In this paper a Lax- Wendroff type scheme with predictor-corrector is presented for solving the hyperbolic equations of fluid flow. The predictor solutions without introducing nonphysical oscillation are obtained by the method of flux vector splitting. The numerical flux of the corrector step is an anti - diffusive term, on which contraints are imposed to decrease the oscillation. Numerical experiments are presented to illustrate the performance of our proposed scheme.

关键词： A LAX-WENDROFF TYPE SCHEME WITH PREDICTOR-CORRECTOR 一刁二川

Dynamic study of photosensitized one-electron oxidation of polyG by menadione

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Science china Chemistry 2005年第4期48卷 292-296页

作者： MA Jianhua1,LIN Weizhen2.DU Fuqiang2.HAN Zhenhui2.YAO Side2.& LIN Nianyun2.1.College of Biology Engineering,Jimei University,Xiamen 36102.,china 2.Laboratory of Nanobiomedicine & Laboratory of Radiation Chemistry,Shanghai institute of {2. physics,Chinese Acade Sciences,Shanghai 2.1800,china 1. College of Biology Engineering Jimei University 361021 Xiamen China 2. Laboratory of Nanobiomedicine & Laboratory of Radiation Chemistry Shanghai Institute of Applied Physics Chinese Academy of Sciences 201800 Shanghai China

The electron transfer reaction of triplet menadione (3MQ?) with polyguanylic acid (polyG) in CH3CN rich (97%) solution was investigated by 2.8 nm(KrF) laser flash *** transient absorption spectra and kinetics obtained from the interaction of 3MQ? with polyG demonstrated that the primary radical ion pair,radical cation of polyG and radical anion of me-nadione can be detected *** results demonstrated that the reaction rate con-stant of 3MQ? with polyG is almost equal to that of 3MQ? with dGMP.

关键词： menadione, polyG, laser flash photolysis, triplet state, one electron oxidation.

Long time behavior for damped generalized coupled nonlinear wave equations. Ⅱ.Unbounded domain

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Communications in Nonlinear Science and Numerical Simulation 2001年第2期6卷 107-110页

作者： Shaomei FANG and Boling GUO Department of Mathematics, Shaoguan University, Shaoguan 512.05, china Graduate School, china Academy of Engineering {2., Beijing 100088, china Center for Nonlinear Studies, institute of applied {2. and computational Department of Mathematics Shaoguan University Shaoguan 512005 China Graduate School China Academy of Engineering Physics Beijing 100088 China Center for Nonlinear Studies Institute of Applied Physics and Computational mathematics Beijing 100088 China

In this paper, by using a priori estimates in the weighted space, the existence of the global attractor for the damped generalized coupled nonlinear wave equations in an unbounded domain is obtained.

关键词： unbounded domain weighted space attractor