带有偏差变元的广义Hamilton系统周期解的存在性

应用变分方法与Morse理论,本文讨论下面含有时滞的广义Hamilton系统的周期解,J*du-dt=g(t,u(t-r1),…,u(t-rs))其中J*是非奇异2n×2n反对称矩阵.在一定条件下,本文得到上述方程至少存在两个非平凡2π-周期解而对于一般的微分系统,本文给出其具有变分结构的判定性准则.     

一类具变参数的p-Laplacian中立型泛函微分方程反周期解的存在性

应用Leray Schauder 不动点定理,研究了一类具变参数的p-Laplacian中立型泛函微分方程(φp(x′(t)-c(t)x′(t-r)))′=f(x′(t))+β(t)g(x(t-τ(t)))+e(t)的反周期解问题,得到了反周期解存在的新的结果.     

具有无限时滞的中立型高维周期微分系统的周期解

本文考虑中立型高维周期微分系统d/dt(x(t)+cx(t-r))=A(t,x(t-r(t)))x(t)+ ∫t-∞C(t,s)x(s)ds+f(t,xt)+b(t)的T-周期解的存在性问题,利用线性系统的指数型 二分性和Krasnoselskii不动点定理,建立了保证系统存在T-周期解的充分条件.     

非线性中立型时滞微分方程的解的性态

本文证明了中立型时滞微分方程当时滞趋于零时,解的一致收敛性是其解关于时滞连续的自然结果;也证明了如果方程x(t)=f(t,x(t),x(t-r),x(t-r))的所有解当t→∞时趋于零且当|r(t)-r|≤s≥t_o≥o),δ为充分小,则方程x(t)=f(t,x(t),x(t-r(t)),x-r(t)))的所有解当t→∞时也趋于零,其中f(t,x,y,u)连续且满足Liscphitz条件。     

一类具复杂偏差变元的中立型微分方程的周期解

本文研究了一类具复杂偏差变元的中立型泛函微分方程■(t)=θ■(t-r) α(t)f(x(t)) β(t)g(x(x(t))) p(t)的周期解的存在性,得到了周期解存在的充分条件,并给出了所得结论的几个简单应用．     

一类二阶n-维中立型泛函微分系统周期解存在性问题

利用Fourier级数理论和重合度理论研究了一类二阶n-维中立型泛函微分系统d2/dt2(x(t)-Cx(t-r))+d/dt gradF(x(t))+gradG(x(t-τ(t)))=p(t)的周期解问题,得到了周期解存在性的新结论,有意义的是本文的矩阵C仅为一般的实方阵,不必为实对称阵,因而本文的结果改进和推广了已有工作.此外,本文周期解先验界估计方法与已有工作也不同.     

中立型对数种群模型的正周期解存在性

本文利用k-集压缩算子的拓朴度抽象连续定理和某些分析技巧,研究了一类中立型对数种群模型dN/dt=N(t)[r(t)-a(t)lnN(t-σ)-b(t)d/dtlnN(t-r)]的正周期解存在性问题。得到了正周期解存在性的新结果。     

含时滞导数项的二阶中立型泛函微分方程的正周期解

研究了非线性项中含有时滞导数项的二阶中立型泛函微分方程(u(t)-cu(t-δ))″+a(t)u(t)=f(t,u(t),u(t-(?)(t)),u′(t-γ(t)))正周期解的存在性,获得了该方程存在正周期解和不存在正周期解的本质条件.这些条件是由系数函数a(t)与非线性项f(t,x,y,z)的关系描述的.我们的讨论基于正算子扰动方法与锥上的不动点指数理论.     

二阶非线性变系数奇异微分方程的周期解

利用拓扑度理论和不动点指数理论,研究了二阶非线性变系数奇异微分方程u″(t)+a(t)u(t)=r(t)f(u(t))的周期解的存在性.特别地,本文没有假设a(t)和f(u)的非负性.     

一类中立型泛函微分系统周期解存在性问题

首先对线性差分算子M:[Mx](t)=z(t)-Cx(t-r)的性质进行了研究,在此基础上利用Mawhin重合度拓展定理研究了一类具偏差变元的中立型泛函微分系统的周期解问题,得到了周期解存在性的新结论.本文的矩阵C仅为一般的实方阵,不必为实对称阵,因而结果改进和推广了已有工作.此外,本文周期解先验界估计方法与已有工作也不相同.     

具有混合时滞的中立型Hopfield神经网络的概周期解

研究一类具有混合时滞的中立型Hopfield神经网络概周期解.通过运用指数二分性及不动点定理,获得了其概周期解的存在性与全局指数稳定性的充分条件,所得结果是新的,并且推广和改进了已有文献的相关结果.     

A Study on Oscillatory and Asymptotic Nature of Impulsive Neutral Differential Equations of Order Three

In this paper, we consider a class of third-order neutral impulsive differential equations. An equivalent class of neutral differential equations is obtained by using a suitable substitution. Some new oscillation results are proved. Moreover, we discuss the asymptotic behavior of the solution. The results presented here are illustrated via examples.     

Asymptotic behaviour of bounded solutions of a class of higher-order neutral dynamic equations

In this paper, necessary and sufficient conditions for the asymptotic behaviour of all bounded solutions of a class of nonlinear higher-order neutral dynamic equations are stated related to various ranges of the coefficient associated with the neutral part, in one of which the coefficient is allowed to oscillate and not tend to zero asymptotically. The new results improve and generalize the known results stated for difference equations and differential equations, and answer some problems left open for the case for arbitrary time scales. Some certain examples, which the results in the literature fail to deliver an answer to, are given to illustrate the applicability and significance of the new results.     

Attracting and quasi-invariant sets of stochastic neutral partial functional differential equations

In this article, we investigate a class of stochastic neutral partial functional differential equations. By establishing new integral inequalities, the attracting and quasi-invariant sets of stochastic neutral partial functional differential equations are obtained. The results in [15, 16] are generalized and improved.     

非线性脉冲中立型时滞抛物方程解的振动性质

研究一类非线性脉冲中立型时滞抛物方程,借助于一阶脉冲中立型微分不等式,获得了该类方程在Robin,Dirichlet边值条件下所有解振动的若干新的充分性判据.所得结果充分反映了脉冲和时滞在振动中的影响作用.     

非线性中立型泛函微分方程Runge-Kutta 法的稳定性和收敛性

本文涉及Runge-Kutta 法变步长求解非线性中立型泛函微分方程(NFDEs) 的稳定性和收敛性.为此, 基于Volterra 泛函微分方程Runge-Kutta 方法的B- 理论, 引入了中立型泛函微分方程Runge-Kutta 方法的EB (expanded B-theory)-稳定性和EB-收敛性概念. 之后获得了Runge-Kutta 方法变步长求解此类方程的EB - 稳定性和EB- 收敛性. 这些结果对中立型延迟微分方程和中立型延迟积分微分方程也是新的.     

一类中立型积分方程的正的概周期解

通过构建锥中一个新的不动点定理,讨论了一类中立型积分方程正的概周期的存在性,得到了一些新的结果.     

Comparison theorems on the oscillation of even order nonlinear mixed neutral differential equations

This study purposes to present some new comparison theorems that guarantee the oscillation of all solutions of even order functional differential equations with a neutral term including both advanced and delayed arguments. The obtained results are based on comparisons with associated first-order delay differential inequalities and first-order delay differential equations, and they are applicable to the both cases where the neutral coefficients are unbounded and/or bounded. In the last section, several examples showing the applicability of the results are provided.