具无限时滞线性中立型泛函微分方程周期解

本文证明了具无限时滞D算子型线性中立型泛函微分方程存在周期解当且仅当存在有界解,推广了MasseraJ．L,ChowS．N．和MakayM．的结果．     

具非线性对流项扩散方程的源型解

研究主部为热传导算子的拟线性抛物型方程Cauchy问题:u_t=u_(xx) (u~n)_x,(x,t)∈S=R×(0,∞),u(x,0)=δ(x),x∈■在一维情形下源型解的存在性,唯一性,不存在性,解的渐近性和相似源型解等问题.在研究过程中,找到了一个n的临界值,即n_0=3.当0≤n相似文献   

具非线性对流项扩散方程的源型解

研究主部为热传导算子的拟线性抛物型方程Cauchy问题ut=uxx+(un)x, (x,t)∈S=R×(0,∞),u(x,0)=δ(x), x∈R在一维情形下源型解的存在性,唯一性,不存在性,解的渐近性和相似源型解等问题.在研究过程中,找到了一个n的临界值,即n0=3.当0≤n＜n0时,方程源型解存在且唯一;当n≥n0时,方程不存在源型解;当0≤n＜2时,方程的源型解在原点附近渐近行为恰似热传导方程的基本解;应用量纲分析技巧,证明了当且仅当n=2时,方程存在唯一相似源型解,并求出了其解析表达式.研究结果表明了这类抛物型方程对流项的存在对扩散项产生重要影响的物理事实.     

一个反应扩散方程整体解的存在性

对一个由反应扩散方程推出的抛物型自由边界问题进行了研究,该问题含有参数γ和τ,已证明了当γ充分大时,该问题存在唯一稳定解.现在主要证明γ,τ均充分大时,该问题存在整体解,即当0＜t＜+∞时,该问题的解存在.     

一个反应扩散方程整体解的存在性

对一个由反应扩散方程推出的抛物型自由边界问题进行了研究,该问题含有参数γ和τ,已证明了当γ充分大时,该问题存在唯一稳定解．现在主要证明γ,τ均充分大时,该问题存在整体解,即当0＜t＜ ∞时,该问题的解存在．     

复变量热传导方程的动力系统

探讨一个复变量热方程的Cauchy问题,其中的非线性项是倒数型的.先提出一些全局解的存在性与不存在性的判定准则,然后采用解平面的不变子集的变换,证明了当初始值渐近于常数时,解是否会在无穷远处消失或在任意时间内全局存在,均依赖于初始值的渐近极限值.     

带色散项的高阶非线性Schrdinger方程的精确解

对一类带色散项的高阶非线性Schrdinger方程的精确解进行研究.通过行波约化,将一类带色散项的高阶非线性Schrdinger方程化为一个高阶非线性常微分方程.再借助于计算机代数系统Mathematica通过构造非线性常微分方程的精确解,成功获得了一系列含有多个参数的包络型精确解,当精确解中参数取特殊值时可以得到两种新型的复合孤子解.并讨论了这两种孤子解存在的参数条件.     

含奇异项的平均曲率型方程的狄氏问题

考虑一类含非线性奇异项和正参数ε的平均曲率型方程的Dirichlet问题.证明了当ε充分小时上述问题至少存在一个古典解;而当ε充分大时这一问题没有古典解.     

具有无穷时滞泛函微分方程的周期解

讨论具有无穷时滞中立型泛函微分方程的周期解问题.利用矩阵测度和Krasnoselskii不动点定理得到了周期解的存在性和唯一性定理;特别地,当Q（s）为零矩阵,A（t,x）=A（t）时给出了存在唯一稳定的周期解的条件.     

时滞脉冲抛物型微分方程解的存在性及其在种群动力学中的应用

本文研究了一类具有时滞的脉冲抛物型方程在Neumann边值条件下解的存在性问题,利用定义上下解对的方法,给出了一个新的解的存在性定理和比较原理.作为例子,当把这种方法应用到一种群模型中时,得到了该系统正平衡点全局吸引的新结果.     

Global fast and slow solutions of a localized problem with free boundary

In this paper,we consider a localized problem with free boundary for the heat equation in higher space dimensions and heterogeneous environment.For simplicity,we assume that the environment and solution are radially symmetric.First,by using the contraction mapping theorem,we prove that the local solution exists and is unique.Then,some sufficient conditions are given under which the solution will blow up in finite time.Our results indicate that the blowup occurs if the initial data are sufficiently large.Finally,the long time behavior of the global solution is discussed.It is shown that the global fast solution does exist if the initial data are sufficiently small,while the global slow solution is possible if the initial data are suitably large.     

A REMARK ON HOFER-ZEHNDER SYMPLECTIC CAPACITY IN SYMPLECTIC MANIFOLDS M×R~(2n)

ＡＲＥＭＡＲＫＯＮＨＯＦＥＲＺＥＨＮＤＥＲＳＹＭＰＬＥＣＴＩＣＣＡＰＡＣＩＴＹＩＮＳＹＭＰＬＥＣＴＩＣＭＡＮＩＦＯＬＤＳＭ×Ｒ２ｎＭＡＲＥＮＹＩＡｂｓｔｒａｃｔＴｈｅａｕｔｈｏｒｓｔｕｄｉｅｓｔｈｅＨｏｆｅｒＺｅｈｎｄｅｒｃａｐａｃｉｔｙａ...     

Analyticity of classical steady needle crystals

This paper is a continuation of our previous work “Rigorous results in selection of steady needle crystals, J. Differential Equations 197 (2004) 349-426”. It concerns analyticity of a classical steadily translating needle crystal. It is proved that any classical solution to the needle crystal problem with sufficiently small but nonzero surface tension, if its slope deviation is close to some Ivantsov zero-surface-tension solution and if its curvature satisfies some algebraic decay conditions at ∞, must belong to the analytic function space A₀ defined in §1 and chosen in the previous study mentioned above. The analyticity result implies that there can be no classical steady needle crystal solution when anisotropy is zero.     

大气运动基本方程组的解析解

在已知大气运动基本方程于光滑函数类中具有最好的稳定性前提下,讨论了它的局部解的解空间构造．根据它的解空间构造,分析了这个方程具有代表性和应用性的第三初值问题,在解析函数类中给出了适定的第三初值问题的解析解的计算方法以及具体的关系表达式,在局部解意义下完整的解决了这一点初值问题的解析解所涉及的理论与计算问题．指出其它类型定解问题都可以仿照文中的计算方法和步骤,求出所需要的稳定的解析解．     

Blowup,Global Fast and Slow Solutions for a Semilinear Combustible System

In this paper, we investigate a semilinear combustible system $u_t-du_{xx}=v^p, v_t-dv_{xx}=u^q$ with double fronts free boundary, where p ≥ 1, q ≥ 1. For such a problem, we use the contraction mapping theorem to prove the local existence and uniqueness of the solution. Also we study the blowup and global existence property of the solution. Our results show that when pq › 1 blowup occurs if the initial datum is large enough and the solution is global and slow, whose decay rate is at most polynomial if the initial value is suitably large, while when p › 1, q › 1 there is a global and fast solution, which decays uniformly at an exponential rate if the initial datum is small.     

Global regular solutions for Landau-Lifshitz equation

In this note, we prove that there exists a unique global regular solution for multidimensional Landau-Lifshitz equation if the gradient of solutions can be bounded in space L ²(0, T; L ^∞). Moreover, for the two-dimensional radial symmetric Landau-Lifshitz equation with Neumann boundary condition in the exterior domain, this hypothesis in space L ²(0, T; L ^∞) can be cancelled.     

Existence of solutions and Gevrey class regularity for Leray-alpha equations

In this paper we consider some equations similar to Navier-Stokes equations, the three-dimensional Leray-alpha equations with space periodic boundary conditions. We establish the regularity of the equations by using the classical Faedo-Galerkin method. Our argument shows that there exist an unique weak solution and an unique strong solution for all the time for the Leray-alpha equations, furthermore, the strong solutions are analytic in time with values in the Gevrey class of functions (for the space variable). The relations between the Leray-alpha equations and the Navier-Stokes equations are also considered.     

A Free Boundary Problem of a Semilinear Combustible System with Higher Dimension and Heterogeneous Environment

In this paper, we investigate a free boundary problem of a semilinear combustible system with higher dimension and heterogeneous environment. Such a problem is usually used as a model to describe heat propagation in a two-component combustible mixture in which the free boundary is described by Stefan-like condition. For simplicity, we assume that the environment and solutions are radially symmetric. We use the contraction mapping theorem to prove the local existence and uniqueness of the solution. Also we study the blowup property and the long time behavior of the solution. Our results show that when pq › 1 blowup occurs if the initial datum is large enough and the solution is global and slow, whose decay rate is at most polynomial if the initial value is suitably large, while when p › 1, q › 1 there is a global and fast solution, which decays uniformly at an exponential rate if the initial datum is small.     

热传导方程小波解的点态收敛

本文主要考虑热传导方程uxx=ut,0≤x<1,t≥0;u(1,t)=g(t),其中边界条件g(t)为已知函数．此定解问题为一不适定问题,也就是说当边界条件有微小扰动时,将会引起解大的扰动．本文将利用多分辨率分析构造一小波解,且证明此解是适定的,并给出所定义小波解与定解问题的真正解在点态意义下的误差估计．