Averaging of Singularly Perturbed Controlled Stochastic Differential Equations

An averaged system to approximate the slow dynamics of a two timescale nonlinear stochastic control system is introduced. Validity of the approximation is established. Special cases are considered to illustrate the general theory.     

二阶奇摄动边值问题

本文应用上下解方法研究了边值问题εy"=f(t,y,ε),L(y(0),y'(0),ε)=0,R(y(1),y'(1),ε)=0(含一般的Robin问题)的解的存在性,唯一性和估计.     

奇摄动半线性时滞微分方程边值问题

本文研究半线性时滞微分方程边值问题εx″(t) =f (t,x(t) ,x(t-ε) ,ε) ,t∈ (0 ,1 ) ,x(t) =φ(t,ε) ,t∈ [-ε,0 ],x(1 ) =A(ε) .利用不动点原理及微分不等式理论 ,我们证明了边值问题解的存在性 ,并给出了解的一致有效渐近展开式 .     

奇摄动非线性时滞微分方程边值问题

本文研究一类非线性时滞微分方程边值问题在条件f_y≤-m<0下,利用微分不等式理论证明了边值问题解的存在性,并给出了解的一致有效渐近展开式.     

具有内部层的奇摄动微分差分方程的渐近解

该文针对一类非线性奇摄动微分差分方程边值问题,用边界层函数法构造了一致有效的渐近解.由于偏差效因,边界层函数的确定困难很多.作者用缝接法不但证明了光滑解的存在性,而且给出了余项估计.     

一类奇摄动泛函微分方程边值问题

该文研究一类泛函微分方程边值问题,利用微分不等式理论证明了边值问题解的存在性,并给出了解的一致有效渐近展开式．     

Homoclinic Points for a Singularly Perturbed System of Differential Equations with Delay

We obtain a representation of the integral manifold of a system of singularly perturbed differential-difference equations with periodic right-hand side. We show that, under certain conditions imposed on the right-hand side, the Poincaré map for the perturbed system has a transversal homoclinic point.     

Singularly Perturbed Volterra Integro-differential Equations

Several investigations have been made on singularly perturbed integral equations. This paper aims at presenting an algorithm for the construction of asymptotic solutions and then provide a proof for asymptotic correctness to singularly perturbed systems of Volterra integro-differential equations.     

Strongly Regular Multi-level Solutions of Singularly Perturbed Linear Partial Differential Equations

We study the asymptotic behavior of the solutions related to a family of singularly perturbed partial differential equations in the complex domain. The analytic solutions are asymptotically represented by a formal power series in the perturbation parameter. The geometry of the problem and the nature of the elements involved in it give rise to different asymptotic levels related to the so-called strongly regular sequences. The result leans on a novel version of a multi-level Ramis–Sibuya theorem.     

四阶常微分方程奇异摄动问题的二阶精度差分解法

本文对一类四阶常微分方程边值问题建立了二阶一致精度的差分格式.本格式对步长h具有O(h2)阶的精度,大大改进了[1]的结果.     

Numerical Method for Singularly Perturbed Third Order Ordinary Differential Equations of Convection-Diffusion Type

In this paper, we have proposed a numerical method for Singularly Perturbed Boundary Value Problems (SPBVPs) of convection-diffusion type of third order Ordinary Differential Equations (ODEs) in which the SPBVP is reduced into a weakly coupled system of two ODEs subject to suitable initial and boundary conditions. The numerical method combines boundary value technique, asymptotic expansion approximation, shooting method and finite difference scheme. In order to get a numerical solution for the derivative of the solution, the domain is divided into two regions namely inner region and outer region. The shooting method is applied to the inner region while standard finite difference scheme (FD) is applied for the outer region. Necessary error estimates are derived for the method. Computational efficiency and accuracy are verified through numerical examples. The method is easy to implement and suitable for parallel computing.     

具非线性边界条件的泛函微分方程边值问题奇摄动(英文)

研究一类具非线性边界条件的泛函微分方程边值问题εx″( t) =f ( t,x( t) ,x( t-τ) ,x′( t) ,ε) ,　 t∈ ( 0 ,1 ) ,x( t) =φ( t,ε) ,　 t∈ [-τ,0 ],　 h( x( 1 ) ,x′( 1 ) ,ε) =A(ε) .我们利用微分不等式理论证明了边值问题解的存在性 ,并给出了解的一致有效渐近展开式     

Singularly Perturbed Equations with Impulse Action

We propose and justify an algorithm for the construction of asymptotic solutions of singularly perturbed differential equations with impulse action.     

非局部反应扩散方程奇摄动问题

本文研究了一类具有非局部奇摄动反应扩散初始边值问题.在适当的条件下,利用比较定理讨论了问题解的渐近性态.     

非局部奇摄动半线性椭圆型方程(英文)

本文讨论了半线性椭圆型方程非局部奇摄动问题 .在适当条件下 ,利用不动点原理 ,对边值问题解的存在性和渐近性态作了研究 .     

具有时滞的奇异扰动随机微分方程的均方指数稳定性

本文利用常数变易公式,随机过程数学期望的性质,矩阵范数,测度的相关理论以及不等式技巧,对一类具有时滞的奇异扰动随机微分方程的均方指数稳定性进行了讨论,得到了该类方程均方指数稳定的充分条件的代数判据.     

Runge-Kutta Discretizations of Singularly Perturbed Gradient Equations

We analyze Runge-Kutta discretizations applied to singularly perturbed gradient systems. It is shown in which sense the discrete dynamics preserve the geometric properties and the longtime behavior of the underlying ordinary differential equation. If the continuous system has an attractive invariant manifold then numerical trajectories started in some neighbourhood (the size of which is independent of the step-size and the stiffness parameter) approach an equilibrium in a nearby manifold. The proof combines invariant manifold techniques developed by Nipp and Stoffer for singularly perturbed systems with some recent results of the second author on the global behavior of discretized gradient systems. The results support the favorable behavior of ODE methods for stiff minimization problems.     

具非线性边界条件的半线性时滞微分方程边值问题奇摄动

利用微分不等式理论研究了一类具非线性边界条件的半线性时滞微分方程边值问题.采用新的方法构造上下解,得到了此边值问题解的存在性的充分条件,并给出了解的一致有效渐近展开式.     

非线性反应扩散方程奇摄动问题

研究了具有非线性反应扩散方程奇摄动问题。在适当的条件下，利用微分不等式理论，讨论了当退化问题具有两个相交解时，原初始边值问题解的渐近性态。 