时间测度链上带有时滞的中立型动力方程的伪概周期解[英文]

本文研究时间测度链上伪概周期函数的性质.利用时间测度链上指数型二分性性质以及Banach不动点定理,我们得到时间测度链上带有时滞的中立型动力方程的伪概周期解存在性与唯一性的充分条件.并举例说明我们的结论     

弱几乎周期点和测度中心

在动力系统讨论中往往出现干扰或假象.为了排除它们,本文引进测度中心概念,而为了决定测度中心的结构,又引进弱几乎周期点的概念.我们完全决定了测度中心的结构,并给出例子说明,测度中心可以真包含于运动中心以及存在在非游荡集上紊动但有零熵的系统.     

Banach空间高阶周期边值问题正解的存在性

本文研究了Banach空间E中的高阶周期边值问题正解的存在性.利用非紧性测度的估计技巧与凝聚映射的不动点指数理论,获得了该问题正解的存在性结果,推广了某些已有的相应结果.     

动力系统中紧的指数吸引集的存在性

本文研究了一般形式的无穷维动力系统.利用非紧性测度理论,当非紧性测度指数衰减时,获得了紧的指数吸引集的存在性条件.同时给出了易于验证非紧性测度指数衰减的方法.     

无限滞后测度泛函微分方程的平均化

本文研究了无限滞后测度泛函微分方程的平均化.利用广义常微分方程的平均化方法,在无限滞后测度泛函微分方程可以转化为广义常微分方程的基础上,获得了这类方程的周期和非周期平均化定理,推广了一些相关的结果.     

高维带宽有限随机信号从平均过采样的指数阶逼近

本文中我们主要考虑利用有限的平均过采样值来重构高维带宽有限随机信号.我们给出了一个能够达到指数阶衰减逼近能力的重构算法.对于一般型和乘积型的采样测度,我们分别给出了对应的重构算法和指数阶衰减的重构误差估计.     

测度中心的Mα-跟踪性质

本文证明如果动力系统具有周期M_α-跟踪性质或者周期M_α-跟踪性质,则其测度中心的限制系统也具有相同的跟踪性质.反之,如果动力系统在其测度中心的限制系统具有周期M_α-跟踪性质(或者,周期M_α-跟踪性质),则该动力系统具有周期M_β-跟踪性质(相应地,周期M_β-跟踪性质),对任意β∈[0,α).同时得到对等度连续系统,众多跟踪性质都等价于动力系统具有平凡的测度中心.     

无限滞后测度泛函微分方程的平均化（英文）

本文研究了无限滞后测度泛函微分方程的平均化.利用广义常微分方程的平均化方法,在无限滞后测度泛函微分方程可以转化为广义常微分方程的基础上,获得了这类方程的周期和非周期平均化定理,推广了一些相关的结果.     

一簇Lorenz映射的混沌行为的符号动力学分析

首先从符号动力学的角度论证了一簇Lorenz映射且有的混沌性质:稠密的周期轨道,周期的集合,拓扑熵,几乎所有(关于Lebesgue测度)的点的Lyapunov指数;并从揉序列的分析给出了该簇映射的拓扑熵的一个下界及Lyapunov指数的一个下界与上界,在很大程度上反应了Lorenz系统的复杂程度.其次仍从符号动力学的角度论证了更一般的Lorenz映射,通过设立参数空间,穷尽了Lorenz映射中函数为直线段的所有情况,并得出同前述Lorenz映射相似的且较为复杂的性质.     

有序Banach空间中常微分方程正周期解的存在性

讨论了有序Banach空间E中的非线性常微分方程:u′(t)+Mu(t)=f(t,u(t)),(?)t∈R正ω-周期解的存在性,其中f:R×P→P连续,P为E中的正元锥.通过新的非紧性测度的估计技巧与凝聚映射的不动点指数理论获得了该问题正ω-周期解的存在性结果.     

Deviation property of periodic measures in C 1 non-uniformly hyperbolic systems with limit domination

In a C1 non-uniformly hyperbolic systems with limit domination, we consider the periodic measures that supported on the Pesin set and keep a distance at least δ to a hyperbolic ergodic measure μ given before. And then, we bound from top the exponential growth rate of such periodic measures by the supremum of measure theoretic entropy on a closed set.     

Positive pseudo almost periodic solutions for a delayed differential neoclassical growth model

This paper is concerned with a non-autonomous delayed differential neoclassical growth model with an oscillating death rate. Under proper conditions, we employ a novel argument to establish a criterion on the existence and global exponential stability of positive pseudo almost periodic solution, which improves and extends some known relevant results. Finally, we present an example along with its numerical simulations to demonstrate the validity of the proposed result.     

On the Robust Stability of Solutions to Periodic Systems of Neutral Type

Under consideration is some class of linear systems of neutral type with periodic coefficients. We obtain the conditions on perturbations of the coefficients which preserve the exponential stability of the zero solution. Using a special Lyapunov–Krasovskii functional, we establish some estimates that characterize the rate of exponential decay at infinity of the solutions of the perturbed systems.     

Periodic bi-directional Cohen–Grossberg neural networks with distributed delays

Some sufficient conditions are obtained for the global exponential stability of periodic solutions to periodic bi-directional Cohen–Grossberg neural networks involving distributed delays, by using the Lyapunov functional method and some analytical techniques. These results improve and generalize some previous works, and are helpful for designing a global exponential stable periodic bi-directional Cohen–Grossberg neural networks.     

Exponential periodic attractor of discrete-time BAM neural networks with transmission delays

In this paper, we investigate discrete-time bidirectional associative memory (BAM) neural networks with periodic coefficients and transmission delays. By using matrix measure, spectral theory, and contraction theory, some sufficient conditions are attained for the existence of a unique exponential periodic attractor. Finally, computer simulations illustrate the dynamic behavior of the unique exponential periodic attractor. Moreover, the unique exponential periodic attractor is also given precisely. The numerical simulation is performed to show our results.     

Infinite periodic words and almost nilpotent varieties

An almost nilpotent variety of linear growth is constructed in the paper for any infinite periodic word in an alphabet of two letters. A discrete series of different almost nilpotent varieties is also constructed. Only a few almost nilpotent varieties were studied previously and their existence was proved often under some additional assumptions. The existence of almost nilpotent varieties of arbitrary integer exponential growth with a fractional exponent is proved as well as the existence of a continual family of almost nilpotent varieties with not more than quadratic growth.     

New results of existence and stability of periodic solution for a delay multispecies Logarithmic population model

In this Letter, for a general class of delayed periodic multispecies Logarithmic population model, we prove some new results on the existence of positive periodic solutions by contraction principle. The global exponential stability of positive periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases.     

水平来流对扰动成长和对流周期性的影响

对Pr=0.0272的纯流体在矩形腔体外加水平来流时,进行二维流体力学基本方程组的数值模拟.研究了该纯流体Rayleigh-Benard对流的一维行波斑图的成长及时空的演化.发现对流成长过程可以划分为3个阶段,即对流发展、对流指数成长和周期变化。在对流指数成长阶段对不同相对Rayleigh(瑞利)数Ra_r的最大垂直流速场随时间变化的情况进行分析,获得了最大垂直流速场指数成长阶段的线性成长率γ_m和相对Rayleigh数Ra_r的关系公式.研究了行波周期受水平来流Reynolds(雷诺)数的影响,揭示了行波对流周期性及其对水平来流Reynolds数的依赖性.     

具有变时滞高阶细胞神经网络的振荡性分析

利用不动点理论和微分不等式分析等技巧,研究了变时滞高阶神经网络概周期解存在性与全局指数收敛性,并且给出了一些新的判别准则.     

The exponential characteristic of the Volterra integral operator with kernel depending on 2<Emphasis Type="Italic">N</Emphasis> variables

Exponential growth is estimated for integral operators with continuous periodic kernels of exponential type. The result is applied to the boundary-value problem for a general hyperbolic differential equation having periodic coefficients with Goursat boundary conditions. It is proved that the exponential characteristic for such a boundary-value problem has canonical form. __________ Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 38, Suzdal Conference-2004, Part 3, 2006.