Global regularity and uniqueness of weak solution for the 2-D liquid crystal flows

We prove the global existence and regularity of weak solution for the 2-D liquid crystal flows with the large initial velocity. The uniqueness of weak solution is also proved by using the Littlewood–Paley analysis.     

MKdV-Burgers方程的边界控制

在区域上利用反馈控制律研究MKdV-Burgers方程的边界控制问题．首先给出MKdV-Burgers方程在边界条件下存在局部经典解,在此基础上给出方程的解先验性估计,随后利用反馈控制律证明MKdV-Burgers方程的弱解的存在性以及解的全局指数稳定性、渐进稳定性．     

Pullback attractors for a model of weakly concentrated aqueous polymer solution motion with a rheological relation satisfying the objectivity principle

The qualitative dynamics of weak solutions to a nonautonomous model of polymer solution motion (with a rheological relation satisfying the objectivity principle) is studied using the theory of pullback attractors of trajectory spaces. For this purpose, the existence of weak solutions is proved for the model under study, a family of trajectory spaces is defined, trajectory and minimal pullback attractors are introduced, and their existence is proved.     

Optimal control of the viscous Dullin–Gottwalld–Holm equation

This paper studies the problem for optimal control of the viscous DGH equation. The existence and uniqueness of weak solution to the equation are proved in a short interval. The optimal control of the viscous DGH equation under boundary condition is given and the existence of optimal solution to the equation is proved.     

Weak solution to hyperbolic Stefan problems with memory

A model for Stefan problems in materials with memory is considered. This model is mainly characterized by a nonlinear Volterra integrodifferential equation of hyperbolic type. Colli and Grasselli proved the uniqueness of a weak solution under the natural assumptions on data and the existence of a strong solution for smoother data. Taking advantage of these two results and assuming just the hypotheses ensuring uniqueness, the existence of a weak solution is here shown. Received October 19, 1995     

一类广义Boussinesq方程的整体弱解和整体弱吸引子

本文证明了一类广义Boussinesq方程的整体弱解和整体弱吸引子的存在性。     

The Existence and Long-Time Behavior of Weak Solution to Bipolar Quantum Drift-Diffusion Model

The authors study the existence and long-time behavior of weak solutions to the bipolar transient quantum drift-diffusion model,a fourth order parabolic system.Using semi-discretization in time and entropy estimate,the authors get the global existence of nonnegative weak solutions to the one-dimensional model with nonnegative initial and homogenous Neumann(or periodic)boundary conditions.Furthermore,by a logarithmic Sobolev inequality,it is proved that the periodic weak solution exponentially approaches its mean value as time increases to infinity.     

A linear wave equation with a nonlinear boundary condition of viscoelastic type

The paper is devoted to the study of a linear wave equation with a nonlinear boundary condition of viscoelastic type. The existence of a weak solution is proved by using the Faedo–Galerkin method. The uniqueness, regularity and asymptotic expansion of the solution are also discussed.     

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.     

Steady subsonic potential flows through infinite multi-dimensional largely-open nozzles

We proved existence, regularity and uniqueness of steady subsonic potential flows in n-dimensional (n ≥ 3) infinite nozzles with largely-open convergent and divergent parts when the total mass flux is less than a certain value. Such nozzles consist of two cones with arbitrary open angles and an arbitrary smooth bounded tubular part. The existence of a weak solution is proved by applying the direct method of calculus of variation to a carefully chosen functional defined on a Hilbert space based upon Hardy inequality. Hölder gradient regularity of weak solution is shown by using Moser iteration to quasilinear elliptic equations in divergence form. Also, the obtained solution is unique in the class of functions with finite kinetic energy by modulo a constant.     

Ginzburg-Landau方程的非齐次初边值问题

研究具非线性边界条件的一类广义Ginzburg-Landau方程解的整体存在性．推导了Ginzburg-Landau方程的非齐次初边值问题光滑解的几个积分恒等式,由此得到了解的法向导数在边界上的平方模以及解的平方模和导数的平方模估计;通过逼近技巧、先验估计和取极限方法证明了Ginzburg-Landau方程的非齐次初边值问题整体弱解的存在性．     

Euler-Bernoulli粘弹性方程初边值问题整体解的存在性

本文利用 Faedo- Galerkin方法证明了一类具记忆项的 Euler- Bernoulli粘弹性方程初边值问题整体解的存在性 .     

The semiclassical limit in the quantum drift-diffusion model

Semiclassical limit to the solution of isentropic quantum drift-diffusion model in semicon- ductor simulation is discussed. It is proved that the semiclassical limit of this solution satisfies the classical drift-diffusion model. In addition, we also proved the global existence of weak solutions.     

关于弱非线性、弱涨落的Boltzmann方程链的经典解的存在性问题

本文按照Grad~([6])指出的方法具体地证明了弱非线性、弱涨落的Boltzmann方程链的经典解的存在性.     

On a generalization of nonlinear pseudoparabolic variational inequalities

The paper studies a generalization of the pseudoparabolic variational inequalities. The existence and uniqueness of the solution of the corresponding weak problem and the regularity of the obtained solution are proved.     

Steady-state problem of complex heat transfer

The problem of radiative-conductive-convective heat transfer in a three-dimensional domain is studied. The existence of a weak solution of the problem is proved, and sufficient conditions for the uniqueness of a solution are found. The temperature distribution in a three-dimensional channel is determined in numerical experiments.     

Existence of optimal controls for systems governed by parabolic partial differential equations with Cauchy boundary conditions

Summary This paper considers the existence of optimal controls for systems governed by a second order parabolic partial differential equation in divergence form with Cauchy conditions. As preliminary results, theorems concerning the convergence of the sequence of weak solutions corresponding to a sequence of admissible controls are proved. Two general forms of criteria are considered. The first one is taken as a function of the weak solution of the system, and the other is taken as a function of the solution of the system and control. Several theorems and corollaries on the existence of optimal controls are then presented.     

On Majda' Model For Dynamic Combustion

Majda's model of dynamic combustion, consists of the system,

In this paper the Cauchy problem is considered. A weak entropy solution for this system is defined, existence, uniqueness and continuous dependence on initial data are proved, as well as finite propagation speed, for initial data in . The existence is proved via the "vanishing viscosity method". Furthermore it is proved that the solution to the Riemann problem converges as to the Z–N–D traveling wave solution. In the appendices, a second order numerical scheme for the model is described, and some numerical results are presented.     

Solvability of Langevin differential inclusions with set-valued diffusion terms on Riemannian manifolds

The existence of weak solution is proved for a Langevin type second-order stochastic differential inclusion on a complete Riemannian manifold, having both drift and diffusion terms set-valued. The construction of solution involves integral operators with Riemannian parallel translation and a special sequence of continuous ?-approximations for an upper semicontinuous set-valued mapping with convex bounded closed values, that is proved to converge point-wise to a Borel measurable selection.     

FREE BOUNDARY PROBLEM ARISING FROM EVAPORATION FROM POROUS MEDIUM

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