换元Newton型方法的计算效能和最佳换元周期

考虑非线性方程组: F(x)=0, (1.1)其中F:R~n→R~n是二次连续可微函数.一般地说,解方程组(1.1)的拟Newton法较Newton法更为有效.我们可以将拟Newton法解释为逐次在R~n的子空间上构造F′(x)的近似(割线近似)得到的算法.按照这种思想,如果将子空间依次循环取成F′(x)的例     

解非线性方程组的并行多重分裂区间AOR方法

解线性方程组与非线性方程组的并行分裂算法是适合于并行计算的一类很有效算法,Frommer和Mayer将它用于求解线性区间方程组。本文将并行多重分裂方法与求解非线性方程组的区间松弛法结合,得到了一类适合并行计算的区间松弛法,称为并行多重分裂区间AOR方法(简称PMI—AOR方法)。文中构造的并行多重分裂Krawczyk型区间     

全空间中带时滞的反应扩散方程组

文应用上下解的方法以及单调迭代序列的积分表达式,证明了在半空间R~n中耦合的时滞反应扩散方程组全局解的存在唯一性,并且用它解决了一类特殊的、Volterra-Lotka模型的解的存在性问题．     

一类具有p-Laplacian算子和积分边界条件的分数阶微分方程解的存在性

研究了一类具有p-Laplacian算子和积分边界条件的分数阶微分方程解的存在性.当限定f(t,u(t))在两个不同区间上的范围以及满足"变异"的Lipschitz条件时,利用退化方程构造的Green函数及其性质,结合Guo-Krasnosel’skii不动点定理以及Banach压缩映射原理,分别证明了所研究问题的解的存在唯一性.     

偏序下的区间松弛法

§1. 引言 本文给出了求解非线性方程组 f(x)=0,f:D?R~n→R~m (1.1)在偏序下的区间松弛法,它是在[1]的基础上将区间迭代与Newton-SOR 迭代结合得到的一种便于计算且收敛较快的序区间N-SOR松弛法,也是单调N-SOR迭代法的推广.§2给出了偏序下的区间Krawczyk算子,它是区间 Newton算子的推广,同样具     

偏序下的区间松弛法

§1. 引言 本文给出了求解非线性方程组 f(x)=0,f:D?R~n→R~m (1.1)在偏序下的区间松弛法,它是在[1]的基础上将区间迭代与Newton-SOR 迭代结合得到的一种便于计算且收敛较快的序区间N-SOR松弛法,也是单调N-SOR迭代法的推广.§2给出了偏序下的区间Krawczyk算子,它是区间 Newton算子的推广,同样具     

不连续一阶微分系统广义解的存在唯一性定理和迭代逼近

本文利用混合单调技巧,得到了不连续一阶微分系统初值问题广义解的存在唯一性定理;构造了一致收敛于广义解的迭代序列,且得到了收敛速度的估计式。本文考虑R~n中不连续一阶常微分方程初值问题。     

一类抽象算子方程组的迭代解及其应用

在Banach空间中, 利用半序方法讨论了一类抽象算子方程组解的存在唯一性, 推广和统一了以前的一些结果. 然后应用到 Banach 空间非线性积分方程组, 得到了方程组的唯一解, 构造了收敛于方程组唯一解的迭代序列并给出了相应的误差估计.     

常微分方程若干周期解存在定理

我们考虑如下微分系统:其中X∈R~n,f关于(t,X)连续且保证解的存在唯一性,f(t+T,X)=f(t.X)(T>0) 再考虑(1)的特例(2):     

退化的抛物方程组解的全局存在及爆破

本文讨论了退化抛物方程组初边值问题解的性质 ,通过构造上、下解 ,证明了古典解的存在唯一性 ,利用特征函数以及最大值原理 ,得出了解全局存在以及爆破的若干条件 .     

一类模糊非线性方程组及解法

模糊非线性方程组 ,在模糊控制和现实生活中很普遍 .本文考虑一类模糊非线性方程组的性质 ,然后给出一种解法 .首先把模糊非线性方程组转变成非线性规划 ,再用非线性规划中的方法或软件来解 .     

Correspondence between frame shrinkage and high-order nonlinear diffusion

Nonlinear diffusion filtering and wavelet/frame shrinkage are two popular methods for signal and image denoising. The relationship between these two methods has been studied recently. In this paper we investigate the correspondence between frame shrinkage and nonlinear diffusion.We show that the frame shrinkage of Ron-Shen?s continuous-linear-spline-based tight frame is associated with a fourth-order nonlinear diffusion equation. We derive high-order nonlinear diffusion equations associated with general tight frame shrinkages. These high-order nonlinear diffusion equations are different from the high-order diffusion equations studied in the literature. We also construct two sets of tight frame filter banks which result in the sixth- and eighth-order nonlinear diffusion equations.The correspondence between frame shrinkage and diffusion filtering is useful to design diffusion-inspired shrinkage functions with competitive performance. On the other hand, the study of such a correspondence leads to a new type of diffusion equations and helps to design frame-inspired diffusivity functions. The denoising results with diffusion-inspired shrinkages provided in this paper are promising.     

Invariant subspaces and conditional Lie-Bäcklund symmetries of inhomogeneous nonlinear diffusion equations

The inhomogeneous nonlinear difusion equation is studied by invariant subspace and conditional Lie-Bcklund symmetry methods.It is shown that the equations admit a class of invariant subspaces governed by the nonlinear ordinary diferential equations,which is equivalent to a kind of higher-order conditional Lie-Bcklund symmetries of the equations.As a consequence,a number of new solutions to the inhomogeneous nonlinear difusion equations are constructed explicitly or reduced to solving fnite-dimensional dynamical systems.     

A Note on Some Sub-Equation Methods and New Types of Exact Travelling Wave Solutions for Two Nonlinear Partial Differential Equations

Sub-equation methods are used for constructing exact travelling wave solutions of nonlinear partial differential equations. The key idea of these methods is to take full advantage of all kinds of special solutions of sub-equation, which is usually a nonlinear ordinary differential equation. We present a function transformation which not only gives us a clear relation among these sub-equation methods, but also can be used to obtain the general solutions of these sub-equations. And then new exact travelling wave solutions of the CKdV-MKdV equation and the CKdV equations as applications of this transformation are obtained, and the approach presented in this paper can be also applied to other nonlinear partial differential equations.      

High order nonlinear parabolic equations

The basic results and methods of the theory of high order nonlinear parabolic equations are described. In the first chapter boundary problems for quasilinear parabolic equations having divergent form are considered. In the second chapter nonlinear parabolic equations of general form are considered. Attention is mainly paid to methods of study of nonlinear parabolic problems. In particular, the methods of monotonicity and compactness, the method of a priori estimates, the functional-analytic method, etc. are described.Translated from Itogi Nauki i Tekhniki, Seriya Sovremennye Problemy Matematiki, Noveishie Dostizheniya, Vol. 37, pp. 89–166, 1990.     

A global method for solution of complex systems

This paper is intended as a tutorial paper for a general scientific audience to introduce to users a unique methodology for accurately and realistically solving dynamical systems which may be strongly nonlinear and involve stochastic processes in inputs, coefficients, or initial or boundary conditions and special cases such as linear, weakly nonlinear, deterministic, etc., as well. It has distinct advantages over perturbative or hierarchy methods and methods of numerical analysis and is applicable to algebraic equations (polynomial, transcendental, matrix), differential equations, systems of coupled (nonlinear and/or stochastic) differential equations, and (nonlinear and/ or stochastic) partial differential equations. Because the methods are applicable to a very wide class of problems in physics, economics, biology and medicine, engineering and technology, the presentation is intended to be accesible to all rather than for applied mathematicians only.     

On the Unique Solvability of the Nonlinear Systems in MDBM

1.IntroductionConsiderthefollowinginitialva1ueprobleminordinarydifferentialequationsy,(t)=f(t,y(t)),y(to)=Yo,(1'1)whereyoER',f:RxR'toR',iscontinuous.Theapproximatesolutionto(1.1)canbeobtainedbythemultiderivativeblockmethod(MDBM)withsecondorderderivatives:wherei=1,'9k,ynER',fn:=f(t.,y.)ER',andf;'):=df(t.,y.)/dteR'areknownvectors.Itisprovedthatthereexistaijjbij,oliandd2i,i,j=1,2,'1k,suchthat(1.2)convergeswithorderp=2k 2(see[l]),andisA-stablefork55(see[5]).Tocomputetheapproxin1atesolut…     

On HSS-based iteration methods for weakly nonlinear systems

Based on separable property of the linear and the nonlinear terms and on the Hermitian and skew-Hermitian splitting of the coefficient matrix, we present the Picard-HSS and the nonlinear HSS-like iteration methods for solving a class of large scale systems of weakly nonlinear equations. The advantage of these methods over the Newton and the Newton-HSS iteration methods is that they do not require explicit construction and accurate computation of the Jacobian matrix, and only need to solve linear sub-systems of constant coefficient matrices. Hence, computational workloads and computer memory may be saved in actual implementations. Under suitable conditions, we establish local convergence theorems for both Picard-HSS and nonlinear HSS-like iteration methods. Numerical implementations show that both Picard-HSS and nonlinear HSS-like iteration methods are feasible, effective, and robust nonlinear solvers for this class of large scale systems of weakly nonlinear equations.     

Meromorphic solutions of nonlinear ordinary differential equations

Exact solutions of some popular nonlinear ordinary differential equations are analyzed taking their Laurent series into account. Using the Laurent series for solutions of nonlinear ordinary differential equations we discuss the nature of many methods for finding exact solutions. We show that most of these methods are conceptually identical to one another and they allow us to have only the same solutions of nonlinear ordinary differential equations.