一类二阶微分差分方程边值问题的奇摄动解

本文利用两变量展开直接构造边界层项的方法,讨论了一类二阶微分差分方程边值问题的奇摄动解,构造了形式渐近解,作出了余项估计,从而证明了解的存在性.     

第五类Painlevé方程解的渐近性态分析

本文用比较直接的方法研究Painleve方程的渐近解和连同公式:(1)先求出数值解,然后用最小二乘法拟合出最佳渐近解;(2)根据最佳渐近解的表达形式,用谐波平衡法得到振荡渐近解与参数之间的依赖关系,即连同公式．当参数α,β,γ和δ满足一些条件时,对一般实的第五类Painleve方程,我们找出了振荡渐近解和连同公式．     

具有超抛物型极限方程的非线性奇摄动反应扩散问题

讨论了一类具有超抛物型方程的反应扩散问题.首先,证明了比较定理.其次,构造了形式渐近解.然后,利用微分不等式方法,研究了问题解的存在、唯一性和渐近性态.最后得到了原问题解的渐近展开式.     

Asymptotic Solution of a Boundary-Value Problem for Linear Singularly-Perturbed Functional Differential Equations Arising in Optimal Control Theory

The Hamiltonian boundary-value problem, associated with a singularly-perturbed linear-quadratic optimal control problem with delay in the state variables, is considered. A formal asymptotic solution of this boundary-value problem is constructed by application of the boundary function method. The justification of this asymptotic solution is done. The asymptotic solution of the Hamiltonian boundary-value problem is constructed and justified assuming boundary-layer stabilizability and detectability.     

Modeling of acoustic pulse signal propagation in deep sea using the Maslov canonical operator

An asymptotic solution to the problem of sound pulse propagation in deep sea is derived using the Maslov canonical operator. An example of a waveguide with the Munk sound speed profile and a point source is considered, and an asymptotic expression for the pulse signal time series at the receiver is obtained. The asymptotic solution is compared with the solution computed using the normal mode theory.     

Determining nodes for semilinear parabolic equations

We are concerned with the determination of the asymptotic behavior of strong solutions to the initial-boundary value problem for general semilinear parabolic equations by the asymptotic behavior of these strong solutions on a finite set. More precisely, if the asymptotic behavior of the strong solution is known on a suitable finite set which is called determining nodes, then the asymptotic behavior of the strong solution itself is entirely determined. We prove the above property by the energy method.     

On one model problem for the reaction–diffusion–advection equation

The asymptotic behavior of the solution with boundary layers in the time-independent mathematical model of reaction–diffusion–advection arising when describing the distribution of greenhouse gases in the surface atmospheric layer is studied. On the basis of the asymptotic method of differential inequalities, the existence of a boundary-layer solution and its asymptotic Lyapunov stability as a steady-state solution of the corresponding parabolic problem is proven. One of the results of this work is the determination of the local domain of the attraction of a boundary-layer solution.     

一类非线性对偶系统的渐近解及其可解性条件

利用渐近理论,讨论了一类非线性对偶系统.在适当的条件下,得出了这一类非线性系统解的存在性条件及其渐近解.将此结果用于二自由度陀螺系统,较简捷地得到了该系统的具有小而有限振幅的渐近解.     

ASYMPTOTIC ESTIMATION FOR SOLUTION OF A CLASS OF SEMI-LINEAR ROBIN PROBLEMS

A class of semi-linear Robin problem is considered. Under appropriate assumptions, the existence and asymptotic behavior of its solution are studied more carefully. Using stretched variables, the formal asymptotic expansion of solution for the problem is constructed and the uniform validity of the solution is obtained by using the method of upper and lower solution.     

Asymptotic solution of singularly perturbed linear-quadratic optimal control problems with discontinuous coefficients

An asymptotic solution of a singularly perturbed linear-quadratic optimal control problem with discontinuous coefficients is constructed by directly substituting an boundary-layer asymptotic expansion of the solution into the condition of the problem and considering a series of problems for finding the asymptotic terms. The error in the approximate solution is estimated. It is shown that the values of the minimized functional do not increase when the next approximations of the optimal control are used.     

一类奇摄动三阶系统边值问题的渐近解

本文获得了一类三阶系统边值问题解的存在性及其精确到任意精度的一致有效估计.     

二阶非线性奇摄动方程脉冲状空间对照结构

该文对一类二阶非线性奇摄动方程进行研究, 指出该方程在一定条件下可以产生脉冲状空间对照结构, 并用边界函数法构造该问题的渐近解, 证明解的存在性并得到渐近解的误差估计.     

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.     

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.     

A modification of Miller's recurrence algorithm

Miller's recurrence algorithm for tabulating the subdominant solution of a second-order difference equation is modified so as to take the asymptotic behaviour of the solution into account. The asymptotic solutions of various types of equations are listed, and a method is given for estimating the error in the tabulated solution.     

二阶拟线性方程边值问题的奇摄动

本文借助不动点原理 ,对二阶拟线性方程的边值问题的渐近解做了估计 ,得到了包括边界层在内的任意次近似的一致有效的渐近展开式     

含双参数的三阶非线性两点边值问题的套层解(英文)

对含双参数且有套层解的一类三阶非线性微分方程的边值问题的渐近解做了估计 ,得到了任意次近似的一致有效的渐近展开式 .     

Kolmogorov-Spieqel-Sivashinsky方程的渐近吸引子及维数估计

研究了周期边界条件下Kolmogorov-Spieqel-Sivashinsky方程的渐近吸引子,并给出了它的维数估计.首先利用正交分解法构造了一个有限维解序列,然后分两步证明该解序列收敛于方程的真实解.     

当极限方程有奇性时高阶线性常微分方程柯西问题解的渐近式*

本文研究当极限方程有奇性时,高阶线性常微分方程柯西问题解的渐近式.为了构造解的渐近式,我们把区域分为三个小区域,在每个小区域,微分方程的解是不同的.     

渐近法在一类强非线性系统中的应用

本文采用文[1、2]的渐近解形式,将渐近法推广到如下较为广泛一类的强非线性振动系统式中g和f为x,的非线性解析函数,ε>0为小参数,并假设对应于ε=0的派生系统有周期解.本文推得系统(0.1)的渐近解递推方法,并应用于实例.