具有快慢层的非光滑奇异摄动问题的空间对照结构

该文研究了具有快慢层的非光滑奇异摄动问题的空间对照结构.利用边界层函数法构造了该问题的形式渐近解,并运用"缝接法"证明了问题光滑解的存在性以及渐近解的一致有效性.最后,通过例子验证了所得结果的有效性.     

一类拟线性奇异摄动方程组的空间对照结构

本文研究带慢变量的右边不连续的拟线性奇异摄动方程组的空间对照结构.利用边界层函数法构造了该方程组的形式渐近解,并运用"缝接法"证明问题解的存在性以及渐近解的一致有效性.最后,通过例子验证了所得结果的有效性.     

一类具奇异右端项的伪抛物方程的摄动问题

本文讨论了一类具奇异右端项的伪抛物方程的初边值问题的摄动,证明了摄动问题广义解的存在性及极限性态,并得到了当ε趋于零时,摄动问题的解在一定意义下收敛于原问题的解.     

一类具有转点的右端不连续奇摄动边值问题

研究了一类具有转点的右端不连续二阶半线性奇摄动边值问题解的渐近性.首先,在间断处将原问题分为左右两个问题,通过修正左问题退化问题的正则化方程,提高了左问题渐近解的精度,并利用Nagumo定理证明了左问题光滑解的存在性.其次,证明了右问题具有空间对照结构的解,并通过在间断点的光滑缝接,得到了原问题的渐近解.最后,通过一个算例验证了结果的正确性.     

一类脉冲微分方程的光滑多尺度解

利用奇异摄动方法,提供了一种以光滑的多尺度解的观点来研究一类脉冲微分方程.通过引入适当的奇异摄动项,定义了相应的奇异摄动边值问题,其对应的退化方程即为原脉冲微分方程.利用边界层函数法和缝接法,构造了该奇异摄动边值问题的光滑多尺度解,并有效地刻画原脉冲微分方程的不连续解,同时也证明了多尺度解的存在性及余项估计.最后,通过...     

具有积分边界条件的二阶半线性奇摄动方程脉冲状对照结构(英文)

本文讨论了带有积分边界条件的二阶半线性奇摄动方程的脉冲状对照结构.借助于边界函数法,在一定条件下,构造了该问题的形式渐近解.利用缝接法证明了该问题解的存在性和形式渐近解的一致有效性.     

关于n阶微分方程边值问题（Ⅲ）——奇摄动的渐近展开

本文研究n阶非线性过值问题(NB)的奇异摄动。在较一般的条件下,应用高阶微分不等式理论证明了摄动解的存在性,并给出了摄动解直到n阶导函数的一致有效渐近展开式,推广和改进了已有的结果。     

具有非局部反应的时滞扩散Nicholson方程的行波解

对具有扩散项的时滞Mcholson方程的行波解进行了研究.特别是考虑到生物个体在空间位置上的迁移,研究了具有非局部反应的时滞扩散模型.对于弱生成时滞核,运用几何奇异摄动理论,在时滞充分小的情况下,证明了行波解的存在性.     

奇异摄动理论研究的一些新动态和热点方向

简要介绍了《奇异摄动丛书》和奇异摄动研究的几个热点方向:几何奇异摄动、空间对照结构理论、高阶微分方程和非线性微分方程奇异摄动边值问题等.     

随机广义耦合微分Riccati方程解的存在性（英文）

本文研究利用奇异值分解方法,获得了随机广义耦合微分Riccati方程解的存在性.另外,作为应用,我们将解的存在性结论应用到了,带马尔可夫跳的线性随机奇异系统最优控制问题,并得到有限时区上的最优控制问题中最优控制的显式表示形式.     

ASYMPTOTIC SOLUTION OF SINGULARLY PERTURBED HYBRID DYNAMICAL SYSTEMS

In this paper, we consider a class of optimal control problem for the singularly perturbed hybrid dynamical systems. By means of variational method, we obtain the necessary conditions of the hybrid dynamical systems. Meanwhile, the existence of solution for the hybrid dynamical system is proved by the sewing method and the uniformly valid asymptotic expansion of the optimal trajectory is constructed by the boundary function method. Finally,an example is presented to illustrate the result.     

奇摄动问题中阶梯状解的缝接法

In view of singularly perturbed problems with complex inner layer phenomenon,including contrast structures(step-step solution and spike-type solution),corner layer behavior and right-hand side discontinuity,we carry out the process with sewing connection.The presented method of sewing connection for singularly perturbed equations is based on the two points singularly perturbed simple boundary problems.By means of sewing orbit smoothness,we get the uniformly valid solution in the whole interval.It is easy to prove the existence of solutions and deal with the high dimensional singularly perturbed problems.     

On higher-dimensional contrast structure of singularly perturbed Dirichlet problem

In this paper,we address the existence and asymptotic analysis of higher-dimensional contrast structure of singularly perturbed Dirichlet problem.Based on the existence,an asymptotical analysis of a steplike contrast structure (i.e.,an internal transition layer solution) is studied by the boundary function method via a proposed smooth connection.In the framework of this paper,we propose a first integral condition,under which the existence of a heteroclinic orbit connecting two equilibrium points is ensured in a higher-dimensional fast phase space.Then,the step-like contrast structure is constructed,and the internal transition time is determined.Meanwhile,the uniformly valid asymptotical expansion of such an available step-like contrast structure is obtained.Finally,an example is presented to illustrate the result.     

Step-like contrast structure for a quasilinear system of singularly perturbed differential equations with a zero characteristic number

We consider a system of singularly perturbed first-order differential equations with a zero characteristic number. The solution of such a problem is characterized by the presence of a contrast structure, that is, of an internal transition layer on a given interval. We prove the existence of an exact solution with a step-like contrast structure and construct its uniform asymptotic expansion. An example is given.     

On the internal layer for a singularly perturbed system of second-order delay differential equations

We consider a nonlinear singularly perturbed boundary value problem with delay. By using the method of boundary functions and the theory of contrast structures, we prove the existence of a smooth solution with an internal transition layer and construct its uniform asymptotic expansion in a small parameter.     

Spike-layered solutions of singularly perturbed quasilinear Dirichlet problems

In this paper we study the existence and structure of a least-energy solution for a class of singularly perturbed quasilinear Dirichlet problems. Using the moving plane method we show that this least-energy solution develops to a spike-layer solution on convex domains.     

Asymptotic properties of solutions of parametric optimal control problems with varying index of the singular arcs

We consider a family of parametric linear-quadratic optimal control problems with terminal and control constraints. This family has the specific feature that the class of optimal controls is changed for an arbitrarily small change in the parameter. In the perturbed problem, the behavior of the corresponding trajectory on noncritical arcs of the optimal control is described by solutions of singularly perturbed boundary value problems. For the solutions of these boundary value problems, we obtain an asymptotic expansion in powers of the small parameter ?. The asymptotic formula starts from a term of the order of 1/? and contains boundary layers. This formula is used to justify the asymptotic expansion of the optimal control for a perturbed problem in the family. We suggest a simple method for constructing approximate solutions of the perturbed optimal control problems without integrating singularly perturbed systems. The results of a numerical experiment are presented.     

Step-like contrast structure for a nonlinear system of singularly perturbed differential equations in the critical case

For an n-dimensional singularly perturbed system of differential equations, we construct the asymptotics of a solution with a step-like contrast structure in the critical case. We prove the existence of a solution and obtain an estimate for the remainder terms of the asymptotic representation of this solution.     

Solution with an internal transition layer for a singularly perturbed second-order equation with an advancing and a retarded argument

We consider a singularly perturbed boundary value problem for a differential equation with a retarded and a deviating argument. By using the method of boundary functions and the sewing method, we find not only a continuous but also a smooth solution of the problem. We prove the existence of a solution with an internal transition layer. A graphical numerical example is presented.