拟线性抛物方程的弱解

该文给出了拟线性退化抛物方程pa_t{u}+pa_x{f(u)}=pa_xx{A(u(x,t))}∈R^2_+×(0,+∞) ,u(x,0)=u_0(x),x∈R 一种弱解的新定义, 利用Div Curl引理证明了解的存在性．     

拟线性退化抛物型方程组解的整体存在性和爆破

该文研究光滑有界区域Ω( R^N (N≥ 1) 上具有齐次Dirichlet边界条件的拟线性退化抛物型方程组 u_t-div(|▽u|^p-2 ▽u) =av^α, v_t-div(|▽v|^q-2 ▽v) =bu^β 的非负解的性质, 其中p, q>2, α, β ≥ 1, a, b> 0是常数. 该文指出上述方程组的解是否在有限时刻爆破依赖于初值、系数 a 与 b以及 αβ 和 (p-1)(q-1)之间的关系.     

一个拟线性抛物型方程组的研究

该文研究如下柯西问题：　此方程组类似于外力依赖于速度的Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程组．研究它是为研究一般Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程组作准备。另一方面，它也可以看作一个高维双曲型方程组　加上粘性项．而（＊）是一个一般高维守恒律的模型．当ｎ＝２，ｆ（ｕ）＝０时，张同等曾经详细研究过它们的Ｒｉｅｍａｎｎ问题．     

一类缺乏紧性的拟线性椭圆型方程组多重弱解的存在性

本文在一定条件下讨论了一类被两个p-Laplacian算子控制的拟线性椭圆型方程组Dirichlet问题多重弱解的存在性.     

拟线性退化抛物型方程的弱解的唯一性

<正> 多年来,由于在热传导、渗流、扩散等一系列实际问题中,提出了以上类型的拟线性退化抛物型方程的定解问题,引起了很多人的兴趣和重视,经过研究已取得了很多成果,如文[1]—[5]等.到目前为止,对弱解的存在性的研究成果较好,而关于解的正则性研究目前还在不断深入,令人遗憾的是关于解的唯一性的研究近年来进展甚少.已有的研究对唯一性都加了较强的条件,如在[1][2]中,讨论 b(u)≡0的特殊情形,以后,Gilding     

非局部退化拟线性抛物型方程组解的爆破和整体存在性

该文采用弱上下解方法和正则化技巧,研究了一类非局部退化抛物型方程组解的爆破和整体存在性,给出了爆破指标,并对非退化情形m=n=1,p_1=q_1=0,p_2q_21给出了一致爆破速率.     

具有奇异项的拟线性椭圆型方程组无穷多弱解的存在性

本文在一定条件下讨论了一类具有奇异项的,被两个pLaplacian算子控制的拟线性椭圆型方程组Dirichlet问题无穷多弱解的存在性.     

退化抛物型方程弱解的存在性

讨论初值为u_0,v_0∈L_+~4(Ω),w∈W~(1,p)(Ω)(p≥2)时退化抛物型方程弱解的存在性.首先利用截断的方法将原问题正则化,化为u_0,v_0∈L_+~∞(Ω)的退化问题,接着对正则化问题的解做估计(这里的估计与具体的截断无关),最后利用弱收敛性,通过取极限的方法证明了原问题解的存在性.     

二阶退化拟线性抛物型方程解的存在性

本文研究二阶退化拟线性抛物型方程的初－边值问题．在适当带权的Ｓｏｂｏｌｅｖ空间,我们利用伪单调算子理论证明了解的存在性．     

EXISTENCE AND UNIQUENESS OFWEAK SOLUTIONS OF UNIFORMLY DEGENERATE QUASILINEAR PARABOLIC EQUATIONS

In this paper we deal with the quasilinear parabolic equation u/t=/x_i[a_(ij)(x, t, u))u/x_j]+b_i(x, t, u)u/x_i+c(x, t, u) which is uniformly degenerate at u=O. Under some assumptions we prove existence anduniqueness of nonnegative weak solutions to the Cauchy problem and the first boundary valueproblem for this equation. Furthermore, the weak solutions are globally Holder continuous.     

Existence and Asymptotic Behavior of Solutions for Quasilinear Parabolic Systems

This paper is concerned with the existence, uniqueness and asymptotic behavior of solutions for the quasilinear parabolic systems with mixed quasimonotone reaction functions endowed with Dirichlet boundary condition, in which the elliptic operators are allowed to be degenerate. By the method of the coupled upper and lower solutions and its monotone iterations, it is shown that a pair of coupled upper and lower solutions ensures that the unique positive solution exists and is globally stable if the quasisolutions are equal. Moreover, we study the asymptotic behavior of solutions to the Lotka-Volterra predator-prey model with the density-dependent diffusion.     

一类带扰动项的拟线性抛物型方程解的存在性

主要利用算子的性质证明了一类带扰动项的拟线性方程的L~2(Ω)初值和狄立克莱边值问题解的存在性和唯一性.     

Existence and Uniqueness of Weak Solutions to the $p$-Biharmonic Parabolic Equation

We consider an initial-boundary value problem for a $p$-biharmonic parabolic equation. Under some assumptions on the initial value, we construct approximate solutions by the discrete-time method. By means of uniform estimates on solutions of the time-difference equations, we establish the existence of weak solutions, and also discuss the uniqueness.     

Existence and Uniqueness of Bounded Weak Solutions of a Semilinear Parabolic PDE

This paper has two parts. In part I, the existence and uniqueness are established for Sobolev solutions of a class of semilinear parabolic partial differential equations. Moreover, a probabilistic interpretation of the solutions in terms of backward stochastic differential equations is obtained. In part II, the existence for viscosity solutions of PDEs with obstacle and Neumann boundary condition is proved.     

Existence Uniqueness and Decay of the Global Weak Solutions for a Class of Parabolic Systems with Nonlinear Boundary Conditions

In this paper, a class of parabolic systems with nonlinear boundary conditions is discussed. By introducing a complete metric space with decay of W^s_p-norm, we obiain the existence uniqueness of global weak solutions, our method is simpler than before. A decay estimate of the global weak solutions is obtained simultaneously.     

Existence and Uniqueness of Positive Radial Solutions for a Class of Quasilinear Elliptic Systems

This article is concerned with the existence and uniqueness of positive radial solutions for a class of quasilinear elliptic system. With some reasonable assumptions on the nonlinear source functions and their coefficients, the existence and the upper and lower bounds of the positive solutions will be provided by using the fixed point theorem and the maximum principle for the quasilinear elliptic system.     

Uniqueness of Generalized Solutions for a Quasilinear Degenerate Parabolic System

In this paper we study the uniqueness of generalized solutions for a class of quasilinear degenerate parabolic systems arising from dynamics of biological groups. The results obtained give an answer to a problem posed by A.S. Kalashnikov [1].     

Continuity of Weak Solutions for Quasilinear Parabolic Equations with Strong Degeneracy

The aim of this paper is to study the continuity of weak solutions for quasilinear degenerate parabolic equations of the form U_t-Δφ(u)=O, whereφ■C~1(R~1)is a strictly monotone increasing function.Clearly,the above equation has strong degeneracy,i.e.,the set of zero points ofφ′(·)is permitted to have zero measure. This is an answer to an open problem in[13,p.288].     

一类拟线性次椭圆方程弱解的局部唯一性

In this note,we obtain some a-priori estimates for gradient of weak solutions to a class of subelliptic quasilinear equations constructed by Ho¨rmander’s vector fields,and then prove local uniqueness of weak solutions.A key ingredient is the estimated about kernel on metirc ＂annulus＂.