一类具非线性边值条件的微分方程的奇摄动问题

研究了一类非线性三阶微分方程的奇摄动问题.运用合成展开法构造了问题的形式渐近解,并运用不动点原理证明了原问题解的存在性及所得形式渐近解的一致有效性.     

一类高阶方程的奇摄动边值问题

在适当条件下,对一类具非线性边界条件的高阶方程的奇摄动问题,通过引入非常规的渐近序列,运用合成展开法,构造问题的形式渐近解,再运用微分不等式理论证明原问题解的存在性及所得形式渐近解的一致有效性.     

一类具非线性边界条件的高阶方程的双参数奇摄动问题

研究了一类含双参数的非线性高阶微分方程的奇摄动问题.运用合成展开法构造了问题的形式渐近解,并运用微分不等式理论证明了原问题解的存在性及所得形式渐近解的一致有效性.     

一类具非线性边值条件的非线性方程的奇摄动问题

研究了一类具非线性边值条件的非线性方程的奇摄动问题,运用合成展开法构造了问题的形式渐近解,并用微分不等式理论证明了所得渐近解的一致有效性.     

一类具非线性边值条件的双参数奇摄动问题

运用合成展开法,构造了一类具非线性边值条件的双参数奇摄动问题的形式渐近解,并利用微分不等式理论,证明了该问题解的存在性和渐近解的一致有效性.     

二阶非线性奇摄动微分方程的渐近解

研究了二阶非线性奇摄动微分方程的边值问题.利用匹配原则和微分不等式原理,得到一阶非线性问题的渐近解,进而得到二阶奇摄动问题的解的渐近估计.     

A class of singular perturbed problems with nonlinear boundary value conditions for higher order equations

研究了一类非线性高阶微分方程的奇摄动问题.运用合成展开法构造了问题的形式渐进解,并运用了微分不等式理论证明了原问题解的存在性及所得形式渐近解的一致有效性,最后给出了一个例子说明结果的意义.     

一类非线性奇摄动方程的匹配解法和解的精度估计

利用匹配渐近展开法,研究了一类非线性奇异摄动方程.在适当的条件下,得出了该类问题解的渐近展开式.并将结果应用于例子,对渐近解与精确解和用两变量方法求得的解进行比较,可知所得到的渐近解达到了较高精度.     

四阶非线性系统的全局渐近稳定性

运用构造李雅普诺夫函数的方法 ,研究了一类四阶非线性系统的全局渐近稳定性 ,给出了该系统零解全局渐近稳定的充分条件     

一类非线性系统周期解的存在唯一性

运用Liapunov函数方法,研究了一类四阶非线性系统,得到了该非线性系统存在唯一渐近稳定的周期解的充分条件.     

Stationary internal layers in a reaction-advection-diffusion integro-differential system

A class of singularly perturbed nonlinear integro-differential problems with solutions involving internal transition layers (contrast structures) is considered. An asymptotic expansion of these solutions with respect to a small parameter is constructed, and the stability of stationary solutions to the associated integro-parabolic problems is investigated. The asymptotics are substantiated using the asymptotic method of differential inequalities, which is extended to the new class of problems. The method is based on well-known theorems about differential inequalities and on the idea of using formal asymptotics for constructing upper and lower solutions in singularly perturbed problems with internal and boundary layers.     

关于一类非线性微分方程组的边值问题的渐近解（Ⅰ）

应用新的方法 ,研究一类非线性微分方程组　　u″ =v,εv″ f(x ,u ,u′)v′ -g(x ,u ,u′)v =0　　 (0 <ε 1) ,的边值问题的解的渐近性质·　构造出解的渐近展开式 ,和估计了余项 ,改进并拓广了前人的工作·     

A remark on oscillatory results for neutral differential equations

We show by a series of counterexamples that a commonly used assumption in the study of asymptotic and oscillatory properties of solutions to neutral differential equations is not valid. Appearing consequences and related open problems are briefly discussed.     

The Cauchy problem for a singularly perturbed Volterra integro-differential equation

The Cauchy problem for a singularly perturbed Volterra integro-differential equation is examined. Two cases are considered: (1) the reduced equation has an isolated solution, and (2) the reduced equation has intersecting solutions (the so-called case of exchange of stabilities). An asymptotic expansion of the solution to the Cauchy problem is constructed by the method of boundary functions. The results are justified by using the asymptotic method of differential inequalities, which is extended to a new class of problems.     

关于具有转点的常微分方程的边值问题

本文研究下面形式的边值问题εy″-f(x,ε)y′ g(x,ε)y=0 (-α≤x≤b,0<ε≤1)y(-α)=α,y(b)=β其中f(x,0)在区间[-a,b]上具有多个和多重零点.给出了出现边界层和内部层的条件,并在相应的条件下,构造解的渐近展开式.     

A Comparison between Two Theories for Multi-Valued Semiflows and Their Asymptotic Behaviour

This paper presents a comparison between two abstract frameworks in which one can treat multi-valued semiflows and their asymptotic behaviour. We compare the theory developed by Ball (1997) to treat equations whose solutions may not be unique, and that due to Melnik and Valero (1998) tailored more for differential inclusions. Although they deal with different problems, the main ideas seem quite similar. We study their relationship in detail and point out some essential technical problems in trying to apply Ball's theory to differential inclusions.     

关于一类带有慢变系数的二阶微分方程的渐近解

本文研究一类带有慢变系数的二阶常微分方程解的渐近展开式.指出已有工作的不足,利用改进的多重尺度法改进和拓广了文献[1～4]的结果.     

具有高阶转向点的奇摄动二次问题的激波解

本文研究了一类具有高阶转向点的含有一阶导数平方项的奇摄动二次边值问题.在适当的条件下,用合成展开法构造出激波解的零次形式近似,并应用微分不等式理论证明了解的存在性及其渐近性质,从而推广了文献^[6]中有关拟线性问题的相应结果.     

二阶椭圆型方程奇摄动边值问题的渐近解

研究了一类二阶线性椭圆型方程的奇摄动边值问题.利用边界层函数法构造出问题的零次形式近似,并应用椭圆型算子的最大值原理对问题的解作出渐近估计.