时滞神经网络殆周期解的全局稳定性

具有随时间变化自抑制、联结权和输入的时滞神经网络的研究是一个重要的课题. 讨论一大类具有殆周期自抑制、联结权和输入的时滞动力系统. 其中, 不仅包括一般时滞系统,还包括分布时滞系统, 也可以同时具有这两种时滞.证明了在一些宽松的条件下,这个系统存在惟一的殆周期解,并且这个解是全局稳定的. 所使用的研究方法不同于其他研究殆周期解时用的方法.     

具有扩散和时滞的捕食系统的持续生存

本文研究具有一般功能性反应和时滞的周期捕食系统的持续生存和周期解,得到了系统永久持续生存的充要条件.在此条件下系统存在正的ω周期解,改进了一些已知结果.     

具有离散时滞和反馈控制的Lotka-Volterra合作系统的动力学行为研究

研究了具有离散时滞和反馈控制的两种群Lotka-Volterra合作系统的正周期解的存在性和全局吸引性.基于Gaines和Mawhin的叠合度定理和构造Lyapunov函数的方法,给出了具有离散时滞和反馈控制的两种群周期合作系统的正周期解的存在性和全局吸引性的充分条件.     

具有限时滞的非自治三种群扩散捕食系统的周期解

主要讨论了具有限时滞的非自治三种群扩散捕食系统的周期解的存在性.方法是运用Yoshizawa型周期解定理的推广,得出该系统至少有一个ω周期解.     

一类时滞微分系统的周期解和全局吸引性

本文考虑如下时滞高维微分周期系统的周期解.利用重合度理论中的延拓定理和Lyapunov泛函方法讨论了上述系统周期解的存在性和全局吸引性,得到了便于应用的新结果.     

具有脉冲和时滞的Logistic模型的持续生存和正周期解的全局吸引性(英文)

本文研究了具有脉冲和时滞效应的Logistic模型.利用脉冲微分方程的比较定理,BohlBrower不动点定理和Lyapunov函数法,获得了系统持续生存,正周期解存在、唯一以及全局吸引的充分条件.结果表明正周期解的全局吸引性与时滞有关.     

具有时滞的细胞神经网络周期解与稳定性

本文研究了具有时滞的细胞神经网络周期解存在性和平凡解的稳定性问题 .利用 Lyapunov函数法并结合不等式分析技巧 ,我们首先证明了时滞细胞神经网络的解是有界的 ,然后建立了时滞细胞神经网络的周期解的存在准则 ,最后在时滞细胞神经网络有平衡点时 ,给出了神经网络系统的平衡点指数稳定的充分条件 .其结果推广了文 [7,8]的相应结果 .     

一类具有时滞和捕获的捕食食饵系统周期解的全局存在性

通过利用Mawhin重合度理论讨论了一类具有时滞和捕获的捕食食饵系统的全局周期解的存在性,得到了周期解存在的充分条件.     

多种群生态时滞系统正周期解的全局吸引性

利用比较定理结合Liapunov泛函, 讨论一类具有多个周期时滞的多种群生态竞争 捕食系统正周期解的存在性和全局吸引性. 最后, 利用一致持久性理论, 讨论捕食 食饵系统正周期解存在的充要条件.     

一类非齐次时滞微分方程概周期解的存在性

该文研究一类非齐次时滞微分方程的概周期解, 结合运用指数二分法, 给出了系统存在概周期解的一组充分条件.     

Dynamic analysis of a turbidostat model with the feedback control

In this paper, a mathematical model with impulsive state feedback control is proposed for turbidostat system. The sufficient conditions of existence of positive order one periodic solution are obtained by using the existence criteria of periodic solution of a general planar impulsive autonomous system. It is shown that the system either tends to a stable state or has a periodic solution, which depends on the feedback state, the control parameter of the dilution rate and the initial concentration of microorganism and substrate. By investigating the periodic solution, the period and the initial point of the periodic solution are given. The results show that turbidostat with impulsive state feedback control tends to an order one periodic solution.     

一类时滞反应扩散方程的周期解和概周期解

通过构造上、下控制函数，结合上、下解方法及相应的单调迭代方法研究了一类时滞反应扩散方程，证明了在反应项非单调时，如果一雏边值问题存在一对周期（或概周期）上、下解，则方程一定存在唯一的周期（或概周期）解．并给出了二维边值问题周期（或概周期）解存在唯一性的充分条件．推广了已有的一些结果。     

On isolated periodic solutions of differential systems

Summary The concept of an isolated periodic solution of a periodic differential system is defined and it is proved that if the number 1 is not a characteristic multiplier of the variational system corresponding to the given periodic solution then this solution is isolated. The concept of a periodic solution with isolated path of an autonomous system is defined and it is proved that if the number 1 is a simple characteristic multiplier of the corresponding variational system then the periodic solution has an isolated path. An example is given showing that the conditions above are not necessary. Entrata in Redazione l’8 giugno 1974.     

A periodic predator–prey-chain system with impulsive perturbation

A periodic predator–prey-chain system with impulsive effects is considered. By using the global results of Rabinowitz and standard techniques of bifurcation theory, the existence of its trivial, semi-trivial and nontrivial positive periodic solutions is obtained. It is shown that the nontrivial positive periodic solution for such a system may be bifurcated from an unstable semi-trivial periodic solution. Furthermore, the stability of these periodic solutions is studied.     

Stable Periodic Solutions of Periodic Systems of Differential Equations

An infinitely differentiable periodic two-dimensional system of differential equations is considered. It is assumed that there is a hyperbolic periodic solution and there exists a homoclinic solution to the periodic solution. It is shown that, for a certain type of tangency of the stable manifold and unstable manifold, any neighborhood of the nontransversal homoclinic solution contains a countable set of stable periodic solutions such that their characteristic exponents are separated from zero.     

The Existence of Almost Periodic Solution and Periodic Solutions

In this paper, it is obtained that a periodic system has an almost periodic solution if it has a solution x=\phi(t) uniformly stable with respect to \Omega_\phi ,and has a periodic solution if x=\phi(t) is weakly uniformly asymptotically stable with respect to \Omega_\phi. Meanwhile, it is also obtained that a uniformly almost periodic system has an almost periodic solution if it has a solution x=\phi(t) uniformly asymptotically stable with respect to A_\phi^j.     

Periodic and almost periodic solution for a non-autonomous epidemic predator-prey system with time-delay

In this paper, we studied a non-autonomous predator-prey system with discrete time-delay, where there is epidemic disease in the predator. By using some techniques of the differential inequalities and delay differential inequalities, we proved that the system is permanent under some appropriate conditions. When all the coefficients of the system is periodic, we obtained the existence and global attractivity of the positive periodic solution by Mawhin’s continuation theorem and constructing a suitable Lyapunov functional. Furthermore, when the coefficients of the system are not absolutely periodic but almost periodic, sufficient conditions are also derived for the existence and asymptotic stability of the almost periodic solution.     

Global attractivity of a positive periodic solution for a nonautonomous stage structured population dynamics with time delay and diffusion

By employing the continuation theorem of coincidence degree theory, the existence of a positive periodic solution for a nonautonomous stage structured population dynamics with time delay and diffusion is established. Further, by constructing a Lyapunov functional and using the result of the existence of positive periodic solution, the attractivity of a positive periodic solution for above system is obtained.     

Periodic solution of a chemostat model with variable yield and impulsive state feedback control

In this paper, a chemostat model with variable yield and impulsive state feedback control is considered. We obtain sufficient conditions of the globally asymptotical stability of the system without impulsive state feedback control. We also obtain that the system with impulsive state feedback control has periodic solution of order one. Sufficient conditions for existence and stability of periodic solution of order one are given. In some cases, it is possible that the system exists periodic solution of order two. Our results show that the control measure is effective and reliable.