N-S方程一般近似惯性流形构造和逼近

1．引言为了用有限维常微分方程来研究Navier七lobes（N七）方程的长时间动力学行为,Foias,Sell和Temaml］引入了耗散系统惯性流形的概念．但惯性流形存在的一个相当苛刻的条件一谱间隔条件一是包括N习方程在内的很多耗散系统无法满足的．因此,Foias,Manlea和TemamZ］随后又提出了近似惯性流形的概念．近似惯性流形也是一个光滑的Lipschitz流形,所有原方程的解在时间充分大时,将被吸引进入该流形的一个三邻域中．因其存在性不需要谱间隔条件来保证,从而可证明包括N－S方程在内的一大类耗散系统存在近似惯性流形．利用近似惯性…     

用Hadamard方法构造惯性流形

本文用Ｈａｄａｍａｒｄ方法为一类带有非线性项Ｒ：Ｄ（Ａ）→Ｈ的无限维耗散动力系统建立惯性流形．在建立惯性流形的过程中，系统的一种“不变锥性质”被充分利用着．这里，对惯性流形存在性至关紧要的谱间隙条件是．     

具有拟周期外力的非自治发展方程的惯性流形

本文主要研究了非自治发展方程的长时间性态,利用谱间断条件和广义锥性质,证明具有拟周期外力的非自治发展方程的惯性流形的存在性,其惯性形式是具有拟周期外力的非自治有限维常微分方程.特别对拟周期外力的反应扩散方程,证明了其惯性流形的存在性.     

Stochastic inertial manifold of dissipative wave equations with time delays

利用修正的Lyapunov-Perron方法研究随机耗散时滞波方程不变流形的存在性,证明了当谱间隙条件成立和时滞适当小时,随机耗散时滞波方程存在随机惯性流形,并且谱间隙条件与确定型时滞耗散波方程的一致.     

关于无限维耗散动力系统的逼近惯性流形

[1]中提出了逼近惯性流形(approximate inertial manifold)以及相应产生的非线性Galerkin方法.本文主要是把[2]中对Navier-Stokes方程构造逼近惯性流形的方法以及一系列误差分析运用到一般框架下的发展方程上去,得到了类似的结果.耗散动力系统的长期行为是由吸引子(global attractor)决定的.惯性流形是含吸引子的一个指数吸引轨线的Lipshiz不交流形.惯性流形的存在取决于耗散算子至少有一对相邻的特征值,其差应足够大,以致无法知道2维Navier-Stokes方程有无惯性流     

广义同步化流形的Hlder连续性

证明了两个不同的混沌系统线性耦合时能实现广义同步化,在一定条件下广义同步化流形是Hlder连续的.采用的思想是Temam的无穷维动力系统的惯性流形理论的改进.在线性耦合下两个混沌系统具有吸收集和吸引子的基础上,通过定义在一个函数类上的映射满足Schauder不动点定理,从而得到广义同步化流形,该广义同步化流形具有不变性.又证明了存在分数维的指数吸引子,指数吸引子与广义同步流形的交集具有指数吸引性.数值仿真证实了理论的正确性.在驱动系统和响应系统外引入辅助系统,辅助系统与响应系统的完全同步化表明了驱动系统和响应系统的广义同步化.     

具有拟周期外力的非自治发展方程的惯性流形

本文主要研究了非自治发展方程的长时间性态,利用谱间断条件和广义雄性质,证明具有拟周期外 力的非自治发展方程的惯性流形的存在性,其惯性形式是具有拟周期外力的非自治有限维常微分方程． 特别对拟周期外力的反应扩散方程,证明了其惯性流形的存在性．     

弱阻尼KdV方程中长期动力学行为研究*

证明了周期边界条件下弱阻尼KdV方程存在近似惯性流形．该流形使吸引子被确切定义的有限维光滑流形逼近．并由此概念引出新的数值方法很好地用于研究动力系统长期行为．     

广义同步化流形的Holder连续性

证明了两个不同的混沌系统线性耦合时能实现广义同步化,在一定条件下广义同步化流形是Holder连续的.采用的思想是Temam的无穷维动力系统的惯性流形理论的改进.在线性耦合下两个混沌系统具有吸收集和吸引子的基础上,通过定义在一个函数类上的映射满足Schauder不动点定理,从而得到广义同步化流形,该广义同步化流形具有不变性.又证明了存在分数维的指数吸引子,指数吸引子与广义同步流形的交集具有指数吸引性.数值仿真证实了理论的正确性.在驱动系统和响应系统外引入辅助系统,辅助系统与响应系统的完全同步化表明了驱动系统和响应系统的广义同步化.     

时滞惯性流形及近似时滞惯性流形族

时滞惯性流形是对耗散系统惯性流形、近似惯性流形的最新发展,它基于对 大小涡分量间相互作用更细致的观察,即改变了惯性流形和近似惯性流形方法中大小 涡分量间相互作用为瞬时行为的隐含假定,而认为这种作用与系统的历史相关的．本 文结出了一类耗散系统时滞惯性流形的存在性证明,由于其存在性不需要“谱间隔条 件”保证,因而时滞惯性流形是广泛存在的．随后我们引出了一类离散的时滞惯性流 形,并在此基础上构造了一种近似时滞惯性流形族,分别给出了它们近似时滞惯性流 形的误差估计,结果显示这种新方法为构造稳定和高精度的算法提供了可能．     

Global Dynamics of a Nonlinear Beam Equation with Strong Structural Damping

In this paper, the global attractor, exponential attractor and flat inertial manifold are obtained for a nonlinear beam equation with strong structural damping.     

On the existence of an inertial manifold for a deconvolution model of the 2D mean Boussinesq equations

We show the existence of an inertial manifold (ie, a globally invariant, exponentially attracting, finite‐dimensional manifold) for the approximate deconvolution model of the 2D mean Boussinesq equations. This model is obtained by means of the Van Cittern approximate deconvolution operators, which is applied to the 2D filtered Boussinesq equations.     

一类非线性抛物型变分不等方程的全局吸引子及弱近似惯性流形

对由一类非线性抛物型变分不等方程所描述的无穷维动力系统，给出了存在全局吸引子及弱近似惯性流形的充分条件．     

Stochastic inertial manifold

A nonlinear stochastic evolution equation in Hilbert space with generalized additive white noise is considered. A concept of stochastic mertial manifold is introduced, defined as a random manifold depending on time, which is finite dimensional, invariant for the dynamic, and attracts exponentially fast all the trajectories as t → ∞. Under the classical spectral gap condition of the deterministic theory, the existence of a stochastic inertial manifold is proved. It is obtained as the solution of a stochastic partial differential equation of degenerate parabolic type, studied by a variant of Bernstein method. A result of existence and uniqueness of a stationary inertial manifold is also proved; the stationary inertial manifold contains the random attractor, introduced in previous works.     

GEVREY CLASS REGULARITY AND APPROXIMATE INERTIAL MANIFOLDS FOR THE NEWTON-BOUSSINESQ EQUATIONS

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＡｐｐｒｏｘｉｍａｔｅｉｎｅｒｔｉａｌｍａｎｉｆｏｌｄｓａｒｅｒｅｌａｔｅｄｔｏｔｈｅｓｔｕｄｙｏｆｌｏｎｇｔｉｍｅｂｅｈａｖｉｏｕｒｏｆｓｏｌｕｔｉｏｎｓｏｆｄｉｓｉｐａｔｉｖｅｐａｒｔｉａｌｄｉｆｅｒｅｎｔｉａｌｅｑ...     

A mollification method for ill-posed problems

Summary. A mollification method for a class of ill-posed problems is suggested. The idea of the method is very simple and natural: if the data are given inexactly then we try to find a sequence of ``mollification operators" which map the improper data into well-posedness classes of the problem (mollify the improper data). Within these mollified data our problem becomes well-posed. And when these facts are in hand we try to obtain error estimates and optimal or ``quasi-optimal" mollification parameters. The method is working not only for problems in Hilbert spaces, but also for problems in Banach spaces. Applications of the method to concrete problems, like numerical differentiation, parabolic equations backwards in time, the Cauchy problem for the Laplace equation, one- and multidimensional non-characteristic Cauchy problems for parabolic equations (in infinite or finite domains),... give us very sharp stability estimates of H\"older continuous type. In these cases the method is optimal in the sense that it gives the same order of H\"older continuous dependence on the data as for the regularized problems. Furthermore, the method may be implemented numerically using fast Fourier transforms. For the first time a uniform stability estimate of H\"older continuous type of the solution of the heat equation backwards in time in the space for all could be established by our mollification method. A new simple sharp pointwise estimate of H\"older type for the weak solution of a non-characteristic Cauchy problem for parabolic equations in a finite domain is established. Received June 25, 1993 / Revised version received February 18, 1994     

Center manifolds for periodic functional differential equations of mixed type

We study the behaviour of solutions to nonlinear functional differential equations of mixed type (MFDEs), that remain sufficiently close to a prescribed periodic solution. Under a discreteness condition on the Floquet spectrum, we show that all such solutions can be captured on a finite dimensional invariant center manifold, that inherits the smoothness of the nonlinearity. This generalizes the results that were obtained previously in [H.J. Hupkes, S.M. Verduyn Lunel, Center manifold theory for functional differential equations of mixed type, J. Dynam. Differential Equations 19 (2007) 497-560] for bifurcations around equilibrium solutions to MFDEs.