泛函微分方程波形松弛方法的收敛稳定北大核心

目前对泛函微分方程波形松弛方法的研究,集中于收敛性.众所周知不稳定的近似方法没有意义,然而罕见关于泛函微分方程松弛方法稳定性的研究工作.首先给出了泛函微分方程波形松弛方法收敛稳定的定义,然后估计波形松弛方法和它的扰动系统生成的两个近似解的差,在常规条件下,推导出差的一个估计.最后利用该估计,得到了泛函微分方程波形松弛方法收敛稳定的充分条件.     

气体动力学燃烧模型的广义Riemann问题

考察了在(x,t)平面上原点(t＞0)的邻域内气体动力学燃烧模型的广义Riemann问题．在改进的熵条件下构造了此问题的唯一解．它们是自相似ZND燃烧模型的极限．发现对某些情形,广义Riemann问题的解与相应的Riemann问题的解有本质的不同．特别地,扰动会使得相应Riemann问题的强爆轰波转化为由预压激波点燃的弱爆燃波．在一些情形,尽管相应的Riemann解中不含燃烧波,扰动后燃烧波会出现．这反映了未燃气体的不稳定性．     

泛函微分方程波形松弛方法的收敛稳定

目前对泛函微分方程波形松弛方法的研究,集中于收敛性.众所周知不稳定的近似方法没有意义,然而罕见关于泛函微分方程松弛方法稳定性的研究工作.首先给出了泛函微分方程波形松弛方法收敛稳定的定义,然后估计波形松弛方法和它的扰动系统生成的两个近似解的差,在常规条件下,推导出差的一个估计.最后利用该估计,得到了泛函微分方程波形松弛方法收敛稳定的充分条件.     

Minkowski空间中定向曲面上的第二类松弛弹性线

在Minkowski空间中,定义了定向曲面上的第二类松弛弹性线,推导了在定向曲面上的第二类松弛弹性线的Euler-Lagrange方程．进一步阐明了,这些曲线是否落在曲率线上,最后给出相关的实例．     

单向拉伸镍钛合金带从奥氏体到马氏体的相变分析

单向拉伸镍钛合金带中从奥氏体到马氏体的相变已在实验中观测到,并被看作为局部变形进行了数值模拟．该文采用相变理论对其进行分析,考虑了两相界面处变形梯度的跳跃以及Maxwell关系,导出了相变的控制方程．相变分析归结为寻求载荷的最小值,使在该值下控制方程具有唯一的、物理上可以接受的实数解．控制方程被数值求解,证明了该唯一解确实存在．相变的Maxwell 应力,马氏体相与奥氏体相内的应力与应变,以及相边界的倾角都可求出,并与实验所观测到的结果相吻合．     

激波管中动态相变的数值研究

用松弛模型研究了范德瓦流体中的激波管问题．当松弛参数趋于0时模型存在一个确定的黎曼解．在数值方面推导了松弛格式（relaxing）和完全松弛格式（relaxed）．在一维问题中,对于不同的剖面,数值模拟显示结果趋向于黎曼解,在理论上和数值上研究了参数的影响．对于特定的初始激波剖面,观察到了非经典的反射波．在二维问题中,研究了曲面波前的数值演化,得到一些有趣的波斑图．     

统计力学格点模型的数值方法

相变是自然界普遍发生的一种突变现象.自上一世纪以来,这一现象的研究便引起了科学工作者的极大注意,其焦点集中在诸如气-液相变、铁磁性相变等与临界点有关的现象上. 当一个系统经受相变时,描述系统状态的某些物理量会产生奇性,这种现象是与微观粒子间的相互作用和热运动二者密切相关的.然而试图利用数学物理的方法,对相变现     

关于多重网格并行计算中拟边界Jacobi成份的影响

1．引言分布式存储并行计算环境中,高效率的获取一般通过区域分解或数据分割实现大粒度并行[4]．因此,对于有效求解偏微分方程的多重网格算法[1,6],并行计算均采用网格划分进行任务分配[5],实现大粒度并行．其中,松弛算子并行度是影响算法并行效率的关键因素．Gauss－SeidellGS）点或块松弛、ILU松弛和适合于方程组的分布式GS松弛（DGS）[1,6]为多重网格算法的有效松弛算子,但本质上都是串行的．尽管采用红黑（RB）序可增强并行度,但每次松弛在每层网格上仍需两次数据交换门（即所有子网格相互交换拟边界数据）．为了减少通…     

一类具有Taylor阻尼的Klein-Gordon方程解的稳定性分析

研究了一类具有Taylor阻尼的Klein-Gordon方程解的稳定性.通过对松弛函数及初始值进行适当的限制,首先基于位势井理论,得到了整体解的存在性,然后构造新的能量函数,利用凸函数的性质及扰动能量方法,得到了显式的能量衰减估计.研究过程中弱化了对松弛函数的限制,同时得到了更广泛的能量衰减速率估计.     

二层规划的神经网络解法

本文研究了基于神经网络的二层规划问题.利用互补松弛条件的扰动,获得了二层规划问题局部最优解的充分条件,克服了互补松弛条件不满足约束规格的局限性,并给出了相应的神经网络求解方法,从而求解原二层规划问题,数值实验表明算法有效.     

On a class of self-similar processes with stationary increments in higher order Wiener chaoses

We study a class of self-similar processes with stationary increments belonging to higher order Wiener chaoses which are similar to Hermite processes. We obtain an almost sure wavelet-like expansion of these processes. This allows us to compute the pointwise and local Hölder regularity of sample paths and to analyse their behaviour at infinity. We also provide some results on the Hausdorff dimension of the range and graphs of multidimensional anisotropic self-similar processes with stationary increments defined by multiple Wiener–Itô integrals.     

A REPRESENTATION FORMULA RELATED TO SCHR(O)DINGER OPERATORS

Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V.     

Qualitative Analysis of Bifurcating Solutions in the Lengyel-Epstein Model

One of the most fundamental problems in theoretical biology is to explain the mechanisms by which patterns and forms are created in the＇living world. In his seminal paper ＂The Chemical Basis of Morphogenesis＂, Turing showed that a system of coupled reaction-diffusion equations can be used to describe patterns and forms in biological systems. However, the first experimental evidence to the Turing patterns was observed by De Kepper and her associates（1990） on the CIMA reaction in an open unstirred reactor, almost 40 years after Turing＇s prediction. Lengyel and Epstein characterized this famous experiment using a system of reaction-diffusion equations. The Lengyel-Epstein model is in the form as follows     

On a class of Riemann surfaces

It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary.     

(0,1 ;0)-INTERPOLATION ON INFINITE INTERVAL (-∞, +∞)

In this paper, we study the explicit representation and convergence of (0, 1; 0)-interpolation on infinite interval, which means to determine a polynomial of degree ≤ 3n - 2 when the function values are prescribed at two set of points namely the zeros of Hn(x) and H′n(x) and the first derivatives at the zeros of H′n(x).     

CONTENTS OF VOLUME 30

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Instructions for contributions

正Applied Mathematics-A Journal of Chinese Universities,Series B(Appl.Math.J.Chinese Univ.,Ser.B)is a comprehensive applied mathematics journal jointly sponsored by Zhejiang University,China Society for Industrial and Applied Mathematics,and Springer-Verlag.It is a quarterly journal with     

Journal of Mathematical Research with Applications Guide for Authors

正Journal overview:Journal of Mathematical Research with Applications(JMRA),formerly Journal of Mathematical Research and Exposition(JMRE)created in 1981,one of the transactions of China Society for Industrial and Applied Mathematics,is a home for original research papers of the highest quality in all areas of mathematics with applications.The target audience comprises:pure and applied mathematicians,graduate students in broad fields of sciences and technology,scientists and engineers interested in mathematics.     

Staircase transportation problems with superadditive rewards and cumulative capacities

A cumulative-capacitated transportation problem is studied. The supply nodes and demand nodes are each chains. Shipments from a supply node to a demand node are possible only if the pair lies in a sublattice, or equivalently, in a staircase disjoint union of rectangles, of the product of the two chains. There are (lattice) superadditive upper bounds on the cumulative flows in all leading subrectangles of each rectangle. It is shown that there is a greatest cumulative flow formed by the natural generalization of the South-West Corner Rule that respects cumulative-flow capacities; it has maximum reward when the rewards are (lattice) superadditive; it is integer if the supplies, demands and capacities are integer; and it can be calculated myopically in linear time. The result is specialized to earlier work of Hoeffding (1940), Fréchet (1951), Lorentz (1953), Hoffman (1963) and Barnes and Hoffman (1985). Applications are given to extreme constrained bivariate distributions, optimal distribution with limited one-way product substitution and, generalizing results of Derman and Klein (1958), optimal sales with age-dependent rewards and capacities.To our friend, Philip Wolfe, with admiration and affection, on the occasion of his 65th birthday.Research was supported respectively by the IBM T.J. Watson and IBM Almaden Research Centers and is a minor revision of the IBM Research Report [6].