梁方程时间依赖全局吸引子的存在性

研究了梁方程时间依赖吸引子的存在性,在非线性项f满足临界增长条件时,基于时间依赖全局吸引子的存在性定理,应用先验估计和算子分解方法验证了系数参数与时间t有关时,梁方程对应的过程族{U(t,τ)}的渐近紧性,从而得到梁方程时间依赖全局吸引子的存在性及正则性.     

无界区域上具线性阻尼的二维 Navier-Stokes 方程的拉回吸引子

该文首先介绍拉回渐近紧非自治动力系统的概念, 给出非自治动力系统拉回吸引子存在定理. 最后证明了无界区域上具线性阻尼的二维Navier-Stokes 方程的拉回吸引子的存在性, 并给出了其Fractal维数估计.     

强阻尼半线性波动方程的全局吸引子

本文讨论一类带强阻尼项的半线性波动方程的全局吸引子的存在性．首先给出了方程解的存在唯一性定理，建立了解的C°-半群；然后运用Hale提出的a-收缩理论，证明了该类方程存在全局吸引子．     

（E0，E）型渐近光滑映射和耗散波方程

本文在无穷维空间引入（Ｅ_０，Ｅ）型渐近光滑映射的概念，研究了其基本性质和变为Ｅ中渐近光滑映射的条件，我们证明了（Ｅ_０，Ｅ）型吸引子存在性定理和（Ｅ_０，Ｅ）型吸引子转化为Ｅ中吸引子的条件定理，所有结果都应用于一类耗散波方程渐近性态的研究。映射，吸引子，耗散波     

具有双记忆项的热弹耦合梁方程的整体吸引子

研究了具有双记忆项的非线性热弹耦合梁方程,利用已知的研究结果给出解的适定性定理,其次通过先验估计并结合常用不等式证明系统存在有界吸收集,且利用标准方法验证半群的渐近紧性,得到整体吸引子的存在性.     

时变时滞粘弹性板方程的整体吸引子

本文研究内部反馈中具有历史和时变时滞的粘弹性板方程.首先利用Faedo-Galerkin方法证得方程在初边值条件下解的适定性定理;其次通过构造合适的能量泛函和Lyapunov泛函证明系统的梯度性;最后利用乘子泛函建立稳定不等式,证明系统的拟稳定性及渐近光滑性,从而得到整体吸引子的存在性,并证明了该吸引子具有有限分形维数.     

具有记忆项和非局部非线性项的板方程的整体吸引子

本文研究具有记忆项和非局部非线性项的板方程.首先利用近似的Faedo-Galerkin方法证得方程在初边值条件下解的适定性定理;其次通过先验估计并结合常用不等式证明该系统存在有界吸收集;最后利用Sobolev紧嵌入和收缩函数的方法证得解半群的渐近紧性,从而得到该系统整体吸引子的存在性.     

具衰退记忆的四阶拟抛物方程的长时间行为

该文主要研究带衰退记忆和临界非线性的四阶拟抛物方程的长时间行为.在过去历史框架下,利用解算子半群的分解技巧和紧性转移定理证明了对应的动力系统的整体吸引子存在性.     

KD-拉回吸引的非自治动力系统拉回吸引子的存在性及其应用

利用拉回吸引子的存在性理论,证明了具有KD-拉回吸引的非自治动力系统拉回吸引子的存在性,拉回吸引子是单点集,是不变的.对无解域上的非自治反映扩散方程,证明了拉回指数吸引子的存在性,是方程唯一拉回指数吸引的稳定解.     

非线性抛物型方程组的最大吸引子

利用能量积分、Sobolev空间的嵌入定理和不变区域,本文证明了一类具有"自然结构条件"的非线性抛物型方程组的最大吸引子的存在性,并给出了一定条件下解的衰减性估计。     

Pullback attractors of 2D Navier–Stokes equations with weak damping,distributed delay,and continuous delay

In this present paper, the existence of pullback attractors for the 2D Navier–Stokes equation with weak damping, distributed delay, and continuous delay has been considered, by virtue of classical Galerkin's method, we derived the existence and uniqueness of global weak and strong solutions. Using the Aubin–Lions lemma and some energy estimate in the Banach space with delay, we obtained the uniform bounded and existence of uniform pullback absorbing ball for the solution semi‐processes; we concluded the pullback attractors via verifying the pullback asymptotical compactness by the generalized Arzelà–Ascoli theorem. Copyright © 2016 John Wiley & Sons, Ltd.     

On uniform attractors of explicit approximations

We prove a theorem stating that the uniform attractors of a family of semiprocesses that do not necessarily have a common time semigroup depend on the parameter uppersemicontinuously. We consider an explicit finite-difference scheme for a nonautonomous system of ordinary differential equations and an explicit spectral-difference scheme for the vorticity equation with time-dependent bounded right-hand side on a sphere. We obtain theorems on the existence of uniform attractors of numerical schemes and their closeness to true attractors of the original differential problems.     

Bounds for attractors and the existence of homoclinic orbits in the lorenz system

Frequency estimates are derived for the Lyapunov dimension of attractors of non-linear dynamical systems. A theorem on the localization of global attractors is proved for the Lorenz system. This theorem is applied to obtain upper bounds for the Lyapunov dimension of attractors and to prove the existence of homoclinic orbits in the Lorenz system.     

Pullback attractors for the norm-to-weak continuous process and application to the nonautonomous reaction–diffusion equations

In this paper, we introduce the concept of norm-to-weak continuous process in a Banach space, and obtain the existence of pullback attractors for this kind of process. Then we give a new method for proving the existence of the pullback attractors. As an application, we obtain the existence of pullback attractors for nonautonomous reaction–diffusion equation in with exponential growth of the external force.     

The Global Attractors for the Dissipative Generalized Hasegawa-Mima Equation

The long time behavior of solutions of the generalized Hasegawa-Mima equation with dissipation term is considered. The existence of global attractors of the periodic initial value problem is proved, and the estimate of the upper bound of the Hausdorff and fractal dimensions for the global attractors is obtained by means of uniform a priori estimates method.     

Measure attractors and random attractors for stochastic partial differential equations

In the theory of stochastic differential equations we can distinguish between two kinds of attractors. The first one is the attractor (measure attractor) with respect to the Markov semigroup generated by a stochastic differential equation. The second meaning of attractors (random attractors) is to be understood with respect to each trajectory of the random equation. The aim of this paper is to bring together the two meanings of attractors. In particular, we show the existence of measure attractors if random attractors exist. We can also show the uniqueness of the stationary distributions of the stochastic Navier-Stokes equation if the viscosity is large     

Lyapunov functionals for reaction–diffusion equations with memory

We consider a reaction‐diffusion equation in which the usual diffusion term also depends on the past history of the diffusion itself. This equation has been analysed by several authors, with an emphasis on the longtime behaviour of the solutions. In this respect, the first results have been obtained by using the past history approach. They show that the equation, subject to a suitable boundary condition, defines a dissipative dynamical system which possesses a global attractor. A similar theorem has been recently proved by Chepyzhov and Miranville, using a different method based on the notion of trajectory attractors. In addition, those authors provide sufficient conditions that ensure the existence of a Lyapunov functional. Here we show that a similar result can be demonstrated within the past history approach, with less restrictive conditions. Copyright © 2005 John Wiley & Sons, Ltd.     

Attractors of Navier-Stokes systems and of parabolic equations,and estimates for their dimensions

One investigates the problem of the existence of an attractor α of the semi-group S_t, generated by the solutions of the nonlinear nonstationary equations $$\frac{{\partial u}}{{\partial t}} = A(u), u|_{t = 0} = u_0 (x); S_t u_0 \equiv u(t)$$ . One proves a very general theorem on the existence of an attractor α of the semigroup S_t for t→∞. One gives examples of differential equations having attractors: a second-order quasilinear parabolic equation, a two-dimensional Navier—Stokes system, a monotone parabolic equation of any order. One proves a theorem on the finiteness of the Hausdorff dimension of the attractor α. One gives an estimate for the Hausdorff dimension of the attractor α for a two-dimensional Navier—Stokes system.     

Well-posedness and dynamics for the fractional Ginzburg-Landau equation

This article studies the global well-posedness and long-time dynamics for the nonlinear complex Ginzburg–Landau equation involving fractional Laplacian. The global existence and some uniqueness criterion of weak solutions are given with compactness method. To study the strong solutions with the semigroup method, we generalize some pointwise estimates for the fractional Laplacian to the complex background and study carefully the linear evolution of the equation. Finally, the existence of global attractors is studied.