具奇系数发展型p-Laplace不等方程整体解的不存在性

考虑两类带奇性系数发展型p-Laplace不等方程整体非负解的不存在性,也即要证明某些拟线性抛物型方程的非线性Liouville定理.通过先验估计,证明了整体解在某个带参数的函数空间中的不存在性.当只考虑连续整体解时,可选取不带参数的函数空间并证明整体解在其中的不存在性.     

在Radon测度给定下的一类退化椭圆型方程

此文研究一类在Ｒａｄｏｎ测度给定下二阶退化拟线性椭圆型方程．通过引入逼近子问题列并求解、先验估计和收敛性研究，证明了该方程广义解在带权Ｓｏｂｏｌｅｖ空间的存在性．     

一类广义层流方程初值问题的整体适定性

讨论了刻画层流问题中比重相近的层间相互作用的数学模型的初值问题.通过引进一类函数空间并证明该初值问题的解在所述空间上的一系列先验估计,得到了该初值问题在初值属于Hs(R)(s≥1)时的整体适定性.     

带线性坍塌项和竞争势的非线性波动方程柯西问题的稳定集和不稳定集(英文)

本文考虑带线性坍塌项和竞争势的非线性波动方程柯西问题,定义了新的稳定集和不稳定集,证明了如果初值进入不稳定集,则解在有限时间爆破;如果初值进入稳定集,则整体解存在.运用势井讨论,回答了当初值在多么小的时候,该柯西问题的整体解存在.     

超线性Duffing方程解的有界性和拟周期解的存在性

本文提供一类超线性函数,使得Duffing方程:在其轨道空间中有一系列不变环面,并且不变环面上的解均为拟周期的;进一步我们证明对任意一个初值问题的解都存在一个不变环面将其限制在里面,从而得到所有解在轨道空间中的有界性。     

双非线性抛物组解的有界性

本文考虑对角型双非线性抛物型方程组，在一般结构条件下，证明广义解局部有界和整体有界，并对一特殊情形，证明了如果解在抛物边界为零，那么它只能是零解．     

Laplace 方程的初值问题

Hadamard 曾证明,Laplaee 方程的初值问题的解对初值是不连续依赖的.在经典的意义下,唯一性是显然的.但可解性的条件似乎还没有人给出过.本文在广义函数的范围内讨论初值问题,给出了可解的充分必要条件,证明了唯一性.当初值是 C~m 函数或L_(loc)~p 函数时,解在广义函数的意义下收敛到初值等价于在 C~m 或 L_(loc)~p 的意义下收敛到初值.因此,我们也给出了经典意义下的初值问题可解的充分必要条件.我们还证明解在广义函数的意义下对初值也不连续依赖.     

具有惯性项和阻尼项的Cahn-Hilliard方程的整体吸引子

本文研究具有惯性项和阻尼项的亚三次非线性Cahn-Hilliard方程的初边值问题.在非线性弱正则的条件下,我们建立弱解的适定性,而不考虑非线性项的一阶导数的下界条件.接着利用弱解的渐近紧和能量解的严格Lyapunov函数的存在性,证明在空间(H~2(?)∩H_0~1(?))×L~2(?)上存在整体吸引子.     

一类广义Boussinesq型方程解的爆破

研究一类广义Boussinesq型方程的初边值问题,利用Galerkin方法证明问题局部广义解的存在性与唯一性．同时,通过使用凸性方法给出问题的解在有限时刻发生爆破的充分条件．     

C~2空间中广义解析函数的一个带位移带共轭值的非线性边值问题

讨论C2空间中广义解析函数的一个带位移带共轭的非线性边值问题.首先讨论解的形式,然后用积分方程的理论和Schauder不动点定理证明了解的存在性.     

On the nonexistence of global solutions of the Hamilton-Jacobi equation

Although examples of nonexistence of global solutions of Hamilton-Jacobi equations have long been known, the general theory of nonexistence of global solutions (unlike the general theory of existence of global viscous solutions) does not yet exist.In the present paper, we use examples of model Hamilton-Jacobi equations to demonstrate how simple methods for the analysis of the problem of nonexistence of global solutions (in the corresponding function class) can be applied.     

Existence and nonexistence results for reaction-diffusion equations in product of cones

Problems of existence and nonexistence of global nontrivial solutions to quasilinear evolution differential inequalities in a product of cones are investigated. The proofs of the nonexistence results are based on the test-function method developed, for the case of the whole space, by Mitidieri, Pohozaev, Tesei and Véron. The existence result is established using the method of supersolutions.     

SEMILINEAR DEGENERATE HEAT INEQUALITIES WITH SINGULAR POTENTIAL ON THE HEISENBERG GROUP

This article deals with the global existence and nonexistence of solutions to the degenerate heat inequalities with singular potential on the Heisenberg group. To prove the existence results, the authors adjust the method of supersolutions to their setting. The nonexistence results are obtained by means of the test function method.     

Global well-posedness for semilinear hyperbolic equations with dissipative term

We study the initial boundary value problem of semilinear hyperbolic equations with dissipative term. By introducing a family of potential wells we derive the invariant sets and vacuum isolating of solutions. Then we prove the global existence, nonexistence and asymptotic behaviour of solutions. In particular we obtain some sharp conditions for global existence and nonexistence of solutions.     

Critical Blowup for Systems of Semilinear Wave Equations in Low Space Dimensions

We consider the Cauchy problem for systems of semilinear wave equations in two and three space dimensions with small initial data. Del Santo et al. [“Geometric Optics and Related Topics” (F. Colombini and N. Lerner, Eds.), Progress in Nonlinear Differential Equations and Their Applications, Vol. 32, pp. 117–140, Birkhauser, Boston, 1997] have studied the existence and nonexistence of global classical solutions of the Cauchy problem except for the critical case. In this paper we study the critical case, and we show the nonexistence of global classical solutions and also give the upper bounds of the life span.     

On the existence and nonexistence of solutions of some quasilinear hyperbolic equations

We consider a special class of quasilinear hyperbolic equations of arbitrary order suggested by V.A. Galaktionov. For these equations, we prove the existence of solutions periodic in t > 0 and consider an initial-boundary value problem for which we derive sufficient conditions for the nonexistence of a global solution in the natural energy space of solutions.     

A global multiplicity result for two-point boundary value problems of p-Laplacian systems

In this paper,we consider the existence,nonexistence and multiplicity of positive solutions for two-point boundary value problems of p-Laplacian systems which have a singular indefinite weight and real multiparameters.For proofs,we mainly make use of the upper and lower solution method and the fixed point index theorem.To obtain a global multiplicity result,we construct a weighted space to benefit richer topology of the solution space than C 0-space.     

Some Notes on Reaction Diffusion Systems with Nonlinear Boundary Conditions

This paper deals with the existence and nonexistence of global positive solution to a semilinear reaction-diffusion system with nonlinear boundary conditions.For the heat diffusion case,the necessary and sufficient conditions on the global existence of all positive solutions are obtained.For the general fast diffusion case,we get some conditions on the global existence and nonexistence of positive solutions.The results of this paper fill the some gaps which were left in this field.     

Global nonexistence for logarithmic wave equations with nonlinear damping and distributed delay terms

This paper is concerned with global nonexistence of solutions for a logarithmic wave equation with nonlinear damping and distributed delay terms. Due to the simultaneous presence of nonlinear damping and logarithmic source terms, we have difficulty in use of the concavity method. Applying the energy estimates, we show the global nonexistence of solutions with not only non-positive initial energy but also positive initial energy.     

Existence and nonexistence of global positive solutions for a weakly coupled P-Laplacian system

In this paper, we deal with a weakly coupled evolution P-Laplacian system with inhomogeneous terms. We obtain a critical criterion concerning existence and nonexistence of its global positive solutions. Such a criterion is different from that of the weakly coupled evolution P-Laplacian system with homogeneous terms. Further, we demonstrate existence and nonexistence of its global positive solutions.