三阶非自治微分方程的不稳定性定理

本文运用构造李雅普诺夫函致的方法，给出了一类三阶非自治微分方程零解不稳定的充分条件。     

关于线性规划基本定理的一点注记

本就线性规划基本定理的证明方法及过程提出一点修改意见。     

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):     

一类Volterra积分微分系统的稳定性

本文应用大系统的定性分析方法,通过作二次型加积分项的 Liapunov 泛函,讨论了一类 Volterra 积分微分系统平凡解的稳定性与一致渐近稳定性,由于作了一些更为细致的处理,我们得到了比文[1—2]的相应结果适应性更为广泛的充分性准则,并扩充了以往的研究工作。     

一类二阶非线性常微分方程零解的全局稳定性

本用变量分离法研究了二阶非线性微分方程x φ(x)p(x) g(x)f(x)=0零解的全局稳定性．     

微分方程渐近稳定性定理的推广及应用

在 Liapunov 稳定性的基本定理中,为了保证系统的渐近稳定性,一般均要求存在定正、具无穷小上界的 V 函数,使沿系统的解其导数定负.为了减弱定理的条件使其应用范围更为广泛,很多人作出了不懈的努力并取得了富有意义的成果.1940年,Marchkov证明了对渐近稳定性而言,V 具无穷小上界的条件可用方程右端的函数为有界(当状态变量 x 有界时)来代替.1979年,T.A.Burton([2])用更宽的条件将 Marchkov 的工作推广到泛函微分方程.1952年,Barbashin 和 Krasovskii 从另一个方面将渐近稳定性理论大大地推进了一步.他们证明了对自治系统而言,(?)只需为常负.只要在(?)=0的集合 E 中不含系统的整条轨线仍可保证渐近稳定性,这样就突破了对(?)定负的要求.遗憾的是,他们的结果仅适用于自治的或周期的系统,且由于直接涉及系统解的性质,对     

渐近稳定性定理的推广

本文讨论了较一般的非线性微分方程组零解的渐近稳定性，推广了文［１］及文［２］的证明方法和其中的一些结果．特别是去掉了Ｌｉａｐｕｎｏｖ函数具有无穷小上界的条件。最后举例说明作者所得的新结果有效且优于前人的有关结果．     

二阶向量常微分方程周期解的存在唯一定理

本文采用指数二分技术和 Sehauder 不动点定理,给出了一个关于二阶向量常微分方程 x″=f(t,x,x＇)周期解的存在唯一性定理。     

非线性非定常系统的稳定性

本文研究一般情形的非线性非定常系统的稳定性,给出了一个广泛而又实用指数稳定性定理。即使是线性时变系统的情形,我们的结果也具一般性,且有应用方便,简捷等优点。     

稳定性理论中几个基本定理的推广

本文推广了经典的稳定性,有界性定理及关于渐近稳定的充分条件。去掉了原始定理中,函数的导数在其定义域内常负或定负的要求,并应用于集合稳定性判定.     

On the Partial Equiasymptotic Stability in Functional Differential Equations

A system of functional differential equations with delay dz/dt = Z(t, z_t), where Z is the vector-valued functional is considered. It is supposed that this system has a zero solution z = 0. Definitions of its partial stability, partial asymptotical stability, and partial equiasymptotical stability are given. Theorems on the partial equiasymptotical stability are formulated and proved.     

常微分方程数值方的法稳定性(英)

本文针对常微分方程数值方法稳定性问题，证明了一般方法的绝对稳定性定理，同时也指出了绝对稳定性条件的局限性．为了克服这种局限性，本文绘出了Jordan稳定性的概念，并建立了一个相应的判别定理．     

Preconditioners Based on Fundamental Solutions

We consider a new preconditioning technique for the iterative solution of linear systems of equations that arise when discretizing partial differential equations. The method is applied to finite difference discretizations, but the ideas apply to other discretizations too. If E is a fundamental solution of a differential operator P, we have E*(Pu) = u. Inspired by this, we choose the preconditioner to be a discretization of an approximate inverse K, given by a convolution-like operator with E as a kernel. We present analysis showing that if P is a first order differential operator, KP is bounded, and numerical results show grid independent convergence for first order partial differential equations, using fixed point iterations. For the second order convection-diffusion equation convergence is no longer grid independent when using fixed point iterations, a result that is consistent with our theory. However, if the grid is chosen to give a fixed number of grid points within boundary layers, the number of iterations is independent of the physical viscosity parameter. AMS subject classification (2000) 65F10, 65N22     

脉冲泛函微分方程实用稳定性的一个比较定理

考虑一类脉冲泛函微分方程的实用稳定性,利用锥值李亚普诺夫函数方法,建立了脉冲泛函数微分方程与脉冲常微分方程的实用稳定性之间的比较定理。     

Stability of a system of Volterra integro-differential equations

Using new and known forms of Lyapunov functionals, this paper proposes new stability criteria for a system of Volterra integro-differential equations.     

Stabilization of Linear Nonautonomous Systems with Norm-Bounded Controls

In this paper, we study the stabilization problem for a class of linear nonautonomous systems with norm-bounded controls. Using the Lyapunov function technique, we establish simple verifiable stabilizability conditions without solving any Riccati differential equation. Numerical examples are given to illustrate the results.Communicated by F. E. UdwadiaThis work was supported by the National Basic Program in Natural Sciences, Vietnam and by a Thailand Research Fund Grant. The authors thank the anonymous referees for valuable comments and remarks which have improved the paper.     

On the stability and boundedness of solutions of a kind of third order delay differential equations

In this paper, we study Eq. (1.1) for asymptotic stability of the zero solution when and uniformly bounded and uniformly ultimate bounded of all solutions when