Charpit System of Partial Differential Equations with Algebraic Constraints

In this paper the Charpit system of partial differential equations with algebraic constraints is considered. So, first the compatibility conditions of a system of algebraic equations and also of the Charpit system of partial differential equations are separately considered. For the combined system of equations of both types sufficient conditions for the existence of a solution are found. They lead to an algorithm for reducing the combined system to a Charpit system of partial differential equations of dimension less than the initial system and without algebraic constraints. Moreover, it is proved that this system identically satisfies the compatibility conditions if so does the initial system.     

具有反馈控制和功能反应的两种群竞争系统的解的渐近性

讨论了具有反馈控制和功能反应的两种群竞争系统的解的渐近性质,获得了在一定条件下该种群持续生存的充分条件,以及该系统为周期系统时,存在全局渐近稳定的正周期解。     

二次多项式微分系统的反射函数

本文给出了二次多项式微分系统的反射函数的第一分量不依赖第二分量的充要条件，以及此时第二分量的表示式，及该系统存在周期解的条件。     

一类广义Liénard系统解的有界性

研究了一类广义 Liénard系统dxdt=p(y) -F(x) ,　 dydt=-g(x) (E)解的有界性 .首先获得了系统 (E)存在无界解的两个新的充分条件 ,然后获得系统 (E)所有解正向有界的若干充分条件和充要条件 ,所获结果改进和扩展了文 [1 -2 ]中的相应结果 .     

Isochronicity of centers in a switching Bautin system

In this paper isochronicity of centers is discussed for a class of discontinuous differential system, simply called switching system. We give some sufficient conditions for the system to have a regular isochronous center at the origin and, on the other hand, construct a switching system with an irregular isochronous center at the origin. We give a computation method for periods of periodic orbits near the center and use the method to discuss a switching Bautin system for center conditions and isochronous center conditions. We further find all of those systems which have an irregular isochronous center.     

关于求解弹性力学平面问题的功的互等定理法

本文推广功的互等定理法于求解具有复杂边界条件矩形板的弹性力学平面问题.首先,我们给出了作为基本系统的四边固定矩形板平面问题的基本解,然后基于在具有复杂边界条件的实际系统与基本系统之间应用功的互等定理,从而求得实际系统的位移表达式.当只存在位移边界条件时,用功的互等定理法求得的位移表达式就是真实的.但是在另一些情况下,当有静力边界条件或混合边界条件时,所求得的位移是容许的.为求得真实位移.必须应用最小势能原理.一些计算表明.对于求解具有复杂边界条件的矩形板弹性力学平面问题,功的互等定理法是一简便通用的方法.显然,这是一个新方法.     

一类具有阶段结构和时滞的捕食系统的持续生存和稳定性

我们提出和研究一类带有阶段结构和时滞的捕食模型,得到了种群持续生存的充分条件.研究了阶段结构和时滞对系统稳定性的影响,获得了系统发生Hopf分支和稳定性的条件以及轨道渐进稳定的周期解的存在性.     

具有三个成长阶段的单种群时滞模型的永久持续生存和全局稳定性

该文研究具有分布时滞和三个成长阶段的单种群模型,得到了系统永久持续生存的充分条件;同时通过构造Lyapunov 函数得到了系统全局渐近稳定的充分条件;最后建立具体模型说明所得结果的可行性.     

Nonlocal problem with integral conditions for a system of hyperbolic equations in characteristic rectangle

We consider a nonlocal problem with integral conditions for a system of hyperbolic equations in rectangular domain. We investigate the questions of existence of unique classical solution to the problemunder consideration and approaches of its construction. Sufficient conditions of unique solvability to the investigated problem are established in the terms of initial data. The nonlocal problem with integral conditions is reduced to an equivalent problem consisting of the Goursat problem for the system of hyperbolic equations with functional parameters and functional relations. We propose algorithms for finding a solution to the equivalent problem with functional parameters on the characteristics and prove their convergence. We also obtain the conditions of unique solvability to the auxiliary boundary-value problem with an integral condition for the system of ordinary differential equations. As an example, we consider the nonlocal boundary-value problem with integral conditions for a two-dimensional system of hyperbolic equations.     

EFFECT OF TOXIC SUBSTANCE ON A NONAUTONOMOUS COMPETITIVE SYSTEM

In this paper, we consider a nonautonomous competitive system which is also affected by toxic substances. Some averaged conditions for the permanence of this system are obtained. Our result shows that under some suitable assumption on the coefficients of the system, the toxic has no influence on the permanence of the system. Also, by using a suitable Lyapunov function, sufficient conditions which guarantee the attractivity of any two positive solutions of the system are obtained.     

Persistence and Global Stability in a Delayed Gause-Type Predator-Prey System without Dominating Instantaneous Negative Feedbacks

A delayed Gause-type predator-prey system without dominating instantaneous negative feedbacks is investigated. It is proved that the system is uniformly persistent under some appropriate conditions. By means of constructing a suitable Lyapunov functional, sufficient conditions are derived for the local and global asymptotic stability of the positive equilibrium of the system.     

具有Crowley-Martin功能反应函数和反馈控制的时滞改进Leslie捕食被捕食系统的动力学行为(英文)

本文考虑了一个具有Crowley-Martin功能反应函数和反馈控制的时滞改进Leslie捕食被捕食系统.应用比较原理,给出了系统具有持久性的条件.也给出了系统的正平衡点的局部稳定和全局稳定的充分条件.     

扩散的具有时滞的非自治捕食-食饵系统的持久性和全局吸引性

讨论当系数满足一定的条件时,具有连续时滞和Ho llingII类功能性反应的非自治扩散捕食-食饵系统的持久性,并给出系统周期解全局吸引的充分条件.     

具有连续时滞和基于比率的非自治捕食扩散系统的持续生存

研究具有连续时滞和基于比率的非自治捕食扩散系统.证明了该系统一致持久性及任何正解全局渐近稳定性的充分条件.     

An inclusion principle for hereditary systems

Given two hereditary dynamic systems having different dimensions, the conditions are provided under which a part of the motion of the larger system is reproduced by the smaller system, that is, the larger system “includes” the smaller one. The conditions for inclusion are useful in applying the concept of vector Liapunov functions to stability analysis of systems composed of overlapping subsystems. By expanding the systems into a larger space the overlapping subsystems appear as disjoint and standard methods can be used to conclude stability of the expanded system. Under the inclusion conditions, stability of the expansion implies stability of the original system. An example is provided to show stability where the standard disjoint decompositions fail.     

离散型Lurie控制系统绝对稳定的充分必要条件

本文研究了离散型Lurie控制系统(1)在非线性函数f(σ)满足f(0)=0,σf(σ)>0(σ≠0)(2)或f(0)=0,0≤k₁≤f(σ)/σ≤k₂<+∞(σ≠0)(3)时,零解的绝对稳定性。给出了系统(1)在满足条件(2)时零解绝对稳定的构造性充要条件,并得到了系统(1)的简化系统在满足条件(3)时,绝对稳定的充分及充要判据。     

MULTIPLICITY OF SOLUTIONS TO ASYMPTOTICALLY LINEAR SECOND-ORDER ORDINARY DIFFERENTIAL SYSTEM

In this paper,we consider an asymptotically linear second-order ordinary differential system with Dirchlet boundary value conditions. Under some conditions,we show the multiplicity of solutions to the system by the Morse theory and an index theory.     

PERSISTENCE AND GLOBAL STABILITY FOR A THREE-SPECIES RATIO-DEPENDENT PREDATOR-PREY SYSTEM WITH TIME DELAYS IN TWO-PATCH ENVIRONMENTS

A three-species ratio-dependent predator-prey diffusion model with time de-lays is investigated. It is shown that the system is uniformly persistent under some ap-propriate conditions, and sufficient conditions are obtained for the global stability of the positive equilibrium of the system.     

Instability criteria for impulsive hybrid state dependent delay integrodifferential systems

In this paper, we present the sufficient conditions ensuring the instability of the zero solution of an impulsive state dependent delay integrodifferential system for different conditions on the delay function. We assume the instability of the associated linear impulsive system and apply the idea of dichotomies together with Schauder–Tychonoff theorem to establish the sufficient conditions for the unstable solution of the problem.