α-Fe中刃型位错与空洞相互作用的分子动力学模拟

本文通过分子动力学方法（MD）,采用嵌入原子势法（EAM）,沿[111]方向插入一层（0-11）半原子面形成位错,然后在模型中插入空洞,模拟了BCC 铁中刃型位错与空洞相互作用,研究了空洞对位错运动的影响机理。模拟结果表明,当温度设定为10K时,位错运动速度快,但空洞直径的大小对位错运动速度的影响不太明显,当高温设定为100K时,由于位错线密度增大并随着空洞直径的增加位错运动速度减小,临界剪切应力也随着减小。最后将模拟计算结果与Osetsky的研究数据及连续体理论模型进行了对比分析。     

EXPANSION OF STEP-TRANSITION OPERATOR OF MULTI-STEP METHOD AND ITS APPLICATIONS (Ⅱ)

We give some formulae for calculation of the expansions for (1) composition of step-transition operators (STO) of any two difference schemes (DS) for ODE's, (2) inverse operator of STO of any DS, and (3) conjugate operator of STO of any DS.     

A CLOSEDNESS CRITERION FOR THE DIFFERENCE OF TWO CLOSED CONVEX SETS IN GENERAL BANACH SPACES

1.IntroductionInthispaperwewillgivesomesuitablesufficientconditionswhichassuretheclosednesspropertyofthedifferenceoftwoclosedconvexsetsingeneralBanachspaces,notnecessarilyrenekive.Theclosednessproblemweareconcernedwithisfrequentlyencounteredindifferentbranchesofappliedmathematics;forexample,thesolvabilityoflinearsystemsoverconeandthedualitytheoryofabstractmathematicalprogramming.OurmotivationcomesfromaBaiocchi-Gastaldi-TomarelliIsresult13]concernedwiththecaseofHilbertspace.FurlhermorelK5th.…     

Geodesic connectedness and conjugate points in GRW space–times

Given two points of a generalized Robertson–Walker space–time, the existence, multiplicity and causal character of geodesics connecting them is characterized. Conjugate points of such geodesics are related to conjugate points of geodesics on the fiber, and Morse-type relations are obtained. Applications to bidimensional space–times and to GRW space–times satisfying the timelike convergence condition are also found.     

一种混合的HS-DY共轭梯度法

本文在HS方法和DY方法的基础上,综合两者的优势,提出了一种求解无约束优化问题的新的混合共轭梯度法.在Wolfe线搜索下,不需给定下降条件,证明了算法的全局收敛性.数值试验表明,新算法较之HS方法和PR方法更加有效.     

A REVISED CONJUGATE GRADIENT PROJECTION ALGORITHM FOR INEQUALITY CONSTRAINED OPTIMIZATIONS

A revised conjugate gradient projection method for nonlinear inequality constrained optimization problems is proposed in the paper, since the search direction is the combination of the conjugate projection gradient and the quasi-Newton direction. It has two merits. The one is that the amount of computation is lower because the gradient matrix only needs to be computed one time at each iteration. The other is that the algorithm is of global convergence and locally superlinear convergence without strict complementary condition under some mild assumptions. In addition the search direction is explicit.