Attractors and approximations for lattice dynamical systems

We present a sufficient condition for the existence of a global attractor for general lattice dynamical systems, then consider the existence of attractors and their approximation for second-order and first-order lattice systems which, in particular case, can be regarded as the spatial discretizations of corresponding wave equations and reaction-diffusion equations in R^k.     

Global Attractors for the One-dimensional Model of Thermodiffusion with Second Sound

In this paper we investigate the global attractors for the one-dimensional linear model of thermodiffusion with second sound. Using the method of contractive functions, we obtain the asymptotically compact of the semigroup and the existence of the global attractors Key words： thermodiffusion~ second sound; globat attractors, asymptotically compact     

A General Approximation Scheme for Attractors of Abstract Parabolic Problems

We consider semilinear problems of the form u′ = Au + f(u), where A generates an exponentially decaying compact analytic C ₀-semigroup in a Banach space E, f:E ^α → E is differentiable globally Lipschitz and bounded (E ^α = D((?A)^α) with the graph norm). Under a very general approximation scheme, we prove that attractors for such problems behave upper semicontinuously. If all equilibrium points are hyperbolic, then there is an odd number of them. If, in addition, all global solutions converge as t → ±∞, then the attractors behave lower semicontinuously. This general approximation scheme includes finite element method, projection and finite difference methods. The main assumption on the approximation is the compact convergence of resolvents, which may be applied to many other problems not related to discretization.     

一类反应扩散方程组最大吸引子的正则性和维数估计

反应扩散方程组的最大吸引子通常是在不变区域内研究,如果不具有不变区域,或者去掉不变区域的限制而在全空间考虑这类问题,其结果如何？本文将证明一类反应扩散方程组在全空间最大吸引子的存在性,并对该吸引子的正则性进行了详细讨论,还给出了该吸引子的维数估计．     

A Multinomial Approximation Approach for the Finite Time Survival Probability Under the Markov-modulated Risk Model

In this paper, we consider the problem of computing different types of finite time survival probabilities for a Markov-Modulated risk model and a Markov-Modulated risk model with reinsurance, both with varying premium rates. We use the multinomial approximation scheme to derive an efficient recursive algorithm to compute finite time survival probabilities and finite time draw-down survival probabilities. Numerical results show that by comparing with MCMC approximation, discretize approximation and diffusion approximation methods, the proposed scheme performs accurate results in all the considered cases and with better computation efficiency.

     

The Global Attractors for the Periodic Initial Value Problem For a Coupled Non-linear Wave Equation

The existence of global attractors of the periodic initial value problem for a coupled non-linear wave equation is proved. We also get the estimates of the upper bounds of Hausdorff and fractal dimensions for the global attractors by means of uniform a priori estimates for time.     

The Attractors for Landau-Lifshitz-Maxwell Equations

The existence of the attractors of the periodic initial value problem for the Landau-Lifshitz-Maxwell equations in one and two space dimensions is proved. We also get accurate estimates of the upper bounds of Hausdorff and fractal dimensions for the attractors by means of uniform a priori estimates for time and Lyapunov functional method.     

Random Point Attractors Versus Random Set Attractors

The notion of an attractor for a random dynamical system withrespect to a general collection of deterministic sets is introduced.This comprises, in particular, global point attractors and globalset attractors. After deriving a necessary and sufficient conditionfor existence of the corresponding attractors it is proved thata global set attractor always contains all unstable sets ofall of its subsets. Then it is shown that in general randompoint attractors, in contrast to deterministic point attractors,do not support all invariant measures of the system. However,for white noise systems it holds that the minimal point attractorsupports all invariant Markov measures of the system.     

The Optimal Feedback Control Problem for Voigt Model with Variable Density

The work is devoted to the study of weak solvability of the optimal feedback control problem for the Voigt model with variable density. The proof is based on the approximation-topological approach. First, the solvability of the approximation problem is proved, and then, based on a priori estimates that are independent of the approximation parameter, it is shown that from the sequence of solutions of the approximation problem, a subsequence converging to the solution of the original problem can be chosen. Then it is shown that among weak solutions to the problem there is at least one that gives a minimum to a given cost functional.

     

复杂地形情况下大气动态模型的弱解和吸引子的存在性

该文研究了一个适合应用于天气预报的大气模型,模型考虑到地形对大气的动力强迫作用,保留了大气气流的辐散效应.首先采用了适当的函数空间,引入了合理的算子表达形式,将复杂的大气动态方程组用一个简单的抽象的算子方程表示,由此给出了模型弱解的定义.然后利用Galerkin方法证明了弱解的存在性.通过构造大气动态方程组轨道吸引集证明相应的轨道吸引子的存在性.     

Regularity of Weak Solutions and Their Attractors for a Parabolic Feedback Control Problem

We investigate additional regularity properties of all globally defined weak solutions, their global and trajectory attractors for a class of autonomous differential inclusion with upper semi-continuous interaction function, when initial data $u_{\tau}\in L^2(\Omega)$ . The main contributions of this paper are: (i) additional regularity and new topological properties of all weak solutions of parabolic feedback control problem with upper semi-continuous interaction function, (ii) a sufficient condition for regularity of global and trajectory attractors, and (iii) new a priory estimates for all weak solutions.     

Attractors for Weak Solutions of a Regularized Model of Viscoelastic Mediums Motion With Memory in Non-Autonomous Case

We study existence of attractors for weak solutions of the regularized model for viscoelastic medium motion with memory in non-autonomous case. We apply the theory of trajectory attractors for non-invariant trajectory spaces and prove the existence of trajectory attractor, global attractor, uniform trajectory attractor, and uniform global attractor for this system.     

发展超导问题的局部耗散性和吸引子

本文得到了在Lorentz规范下一类发展超导问题解的整体存在性、局部耗散 性和吸引子的存在性.     

Exponential Attractors for the Generalized Ginzburg-Landau Equation

Abstract In this paper, we establish the global fast dynamics for the derivative Ginzburg-Landau equation in two spatial dimensions. We show the squeezing property and the existence of finite dimensional exponential attractors for this equation * The author is supported by the Postdoctoral Foundation of China     

The Global Attractors for the Periodic Initial Value Problem of Generalized Kuramoto-Sivashinsky Type Equations in Multi-dimensions

The existence of global attractors for the periodic initial value problem of generalized Kuramoto-Sivashinsky type equations in multi-dimensions is proved. We also get the estimates of the upper bounds of Hausdorff and fractal dimensions for the global attractors by means of a uniform priori estimates for time.     

The Global Attractors for Damped Generalized Coupled Nonlinear Wave Equations

The existence of global attractors for the periodic initial value problem of damped generalized coupled nonlinear wave equations is proved. We also get the estimates of the upper bounds of Hausdorff and fractal dimensions for the global attractors by means of a uniformly priori estimates for time.     

Local Dissipativity and Attractors for the Evolutionary Superconductivity Problem

In this paper, under the Lorentz gauge, the global existence, local dissipativity and attractors of the evolutionary superconductivity problem which is a parabolic-hyperbolic system are obtained. Received March 4, 1998, Revised October 9, 1998, Accepted March 25, 1999     

Attractors for discrete periodic dynamical systems

A mathematical framework is introduced to study attractors of discrete, nonautonomous dynamical systems which depend periodically on time. A structure theorem for such attractors is established which says that the attractor of a time-periodic dynamical system is the union of attractors of appropriate autonomous maps. If the nonautonomous system is a perturbation of an autonomous map, properties that the nonautonomous attractor inherits from the autonomous attractor are discussed. Examples from population biology are presented.     

Existence of an attractor for three-dimensional model of the Bingham fluid motion

We prove the existence of trajectory and global attractors for weak solutions to equations of the motion of Bingham fluid.