一类高阶非线性波动方程解的存在性

研究一类高阶非线性波动方程的初边值问题 ,证明问题局部广义解的存在性、唯一性 ,并用凸性方法证明解爆破的充分条件 .     

一类高阶非线性双曲型方程初边值问题解的爆破

本文研究一类高阶非线性双曲型方程的初边值问题，证明问题局部广义解的存在性与唯一性，同时给出解爆破的充分条件。     

半线性退化发展方程的混合初边值问题

本文研究一类高阶多维退化和非退化半线性发展方程的混合初边值问题:利用Galerkin方法和能量积分估计,我们建立了该问题的正则解的整体存在性和唯一性。     

一类反应扩散方程解的熄灭现象

利用能量估计方法讨论了下述反应扩散方程的初边值问题解的渐近性态,分别给出解熄灭的充分条件和必要条件。这里λ>0,γ>0,β>0为常数,Ω?RN为有界域。文末给出说明文中方法处理高阶方程的例子。     

半线性退化发展方程的混合初边值问题

本文研究一类高阶多维退化和非退化半线性发展方程的混合初边值问题:利用 Galerkin 方法和能量积分估计,我们建立了该问题的正则解的整体存在性和唯一性.     

一类高阶多维非线性伪双曲方程

本文研究了一类高阶多维非线性伪双曲方程，通过先验估计结合Ｓｏｂｏｌｅｖ嵌入定理及Ｌｃａｒｙ－Ｓｃｈａｕｄｅｒ不动点定现证明了初边值问题整体广义解的存在性和唯一性。     

扇形域上高阶Schwarz边值问题（英文）

本文主要讨论一类角度为θ=π/α,α≥1/2的扇形域上高阶多解析方程的Schwarz边值问题.通过构造适当的高阶-Schwarz算子和Pompeiu算子,我们给出了详细的解表达式.本文把边值问题进一步推广到高阶情形,丰富了扇形域上边值问题的发展.     

双参数半线性高阶椭圆型方程的奇摄动解

讨论了一类具有双参数的半线性高阶椭圆型方程边值问题.利用微分不等式理论,研究了边值问题解的存在性和渐近性态.     

高阶非齐次GBBM方程

本文研究了高阶非齐次ＧＢＢＭ方程的Ｃａｕｃｈｙ问题和初边值问题。对任意的有界或无界光滑区域Ω，采用Ｂａｎａｃｈ不动点原理及一系列的积分估计，建立了高阶非齐次ＧＢＢＭ方程的Ｃａｕｃｈｙ问题和初边值问题在Ｗ＾２ｍ，ｐ（Ω）上整体强解的存在唯一性，这些结果改进并完善了ＢＢＭ方程的已有结果，与此同时，我们还讨论了强解的正则性。     

板弯曲问题的具两组高阶基本解序列的MRM方法

讨论了双参数地基上薄板弯曲问题.利用两组高阶基本解序列,即调和及重调和基本解序列,采用多重替换方法(MRM方法),得到了板弯曲问题的MRM边界积分方程.证明了该方程与边值问题的常规边界积分方程是一致的.因此由常规边界积分方程的误差估计即可得到板弯曲问题MRM方法的收敛性分析.此外该方法还可推广到具多组高阶基本解序列的情形.     

非紧空间上折现Hamilton-Jacobi方程粘性解的存在性讨论*

当底空间紧时, 初始函数为连续函数的Lax-Oleinik型粘性解是局部半凹的,所以是相应的Hamilton-Jacobi\ (以下简称为H-J) 演化方程(简称为接触H-J方程)的粘性解.当底空间非紧时, 对于H-J方程和接触H-J方程, 其Lax-Oleinik型解的下确界未必能取到.文章将探讨在非紧空间上, 折现H-J方程粘性解有限性的条件, 并给出了在此假设下粘性解的表达式.     

关于KdV方程孤子解的研究

KdV方程的多孤子解很难直接验证，本文通过证明GLM反散射变换方程导出的Jost解满足两个Lax方程的方法，解决了这个问题．     

不通过Poisson公式解调和方程在球上的一类Dirichlet问题

得到了一个解调和方程在球上的一类Dirichlet问题的简单方法,即不通过Poisson公式而实际上只解一个Euler方程,从而较容易地求出其解.     

On the stability and the attraction domain of the stationary solution of a singularly perturbed parabolic equation with a multiple root of the degenerate equation

We construct and justify the asymptotics of a boundary layer solution of a boundary value problem for a singularly perturbed second-order ordinary differential equation for the case in which the degenerate (finite) equation has an identically double root. A specific feature of the asymptotics is the presence of a three-zone boundary layer. The solution of the boundary value problem is a stationary solution of the corresponding parabolic equation. We prove the asymptotic stability of this solution and find its attraction domain.     

Numerical solution of the differential equation describing the behavior of the zeroth-order boundary function

The asymptotic solution of the integro-differential plasma-sheath equation is considered. This equation is singularly perturbed because of the small coefficient multiplying the highest order (second) derivative. The asymptotic solution is obtained by the boundary function method. Equations are derived for the first two coefficients in the form of both a regular series expansion and an expansion in boundary functions. The equation for the first coefficient of the regular series has only a trivial solution. A numerical algorithm is considered for the solution of the second-order differential equation describing the behavior of the zeroth-order boundary function. The proposed algorithm efficiently solves the boundary-value problem and produces a well-behaved solution of the Cauchy problem. __________ Translated from Prikladnaya Matematika i Informatika, No. 23, pp. 24–35, 2006.     

Maslov-Poisson measure and Feynman formulas for the solution of the Dirac equation

As the main step, the method used by V. P. Maslov for representing a solution of the initial-value problem for the classical Schrödinger equation and admitting an application to the Dirac equation includes the construction of a cylindrical countably additive measure (that is an analog of the Poisson distribution) on a certain space of functions (= trajectories in the impulse space) whose Fourier transform coincides with the factor in the formula for representation of the solution of the Schrödinger equation by the integral in the so-called cylindrical Feynman (pseudo) measure (in the trajectory space of the configurational space for the classical system). On the other hand, in the Maslov formula for the solution of the Schrödinger equation, the exponential factor is (with accuracy up to a shift) the Fourier transform of the Feynman pseudomeasure. In the case of the Dirac equation, historically, for the first time, there arose formulas for the impulse representation that use countably additive functional distributions of the Poisson-Maslov measure type but with noncommuting (matrix) values. The paper finds generalized measures whose Fourier transforms coincide with an analog of the exponential factor under the integral sign in the Maslov-type formula for the Dirac equation and integrals with respect to which yield solutions of the Cauchy problem for this equation in the configurational space.     

Nonexistence of the periodic peaked traveling wave solutions for rotation-Camassa–Holm equation

Recently, Zhu et al. (2020) proposed a kind of rotation-Camassa–Holm equation. In this paper, we study the question of nonexistence of periodic peaked traveling wave solution for rotation-Camassa–Holm equation. Indeed, rotation-Camassa–Holm equation has no nontrivial periodic Camassa–Holm peaked solution unlike Camassa–Holm equation, modified Camassa–Holm equation, Novikov equation.     

Three dimensional elastodynamics of 2D quasicrystals: The derivation of the time-dependent fundamental solution

The time-dependent differential equations of elasticity for 2D quasicrystals with general structure of anisotropy (dodecagonal, octagonal, decagonal, pentagonal, hexagonal, triclinic) are considered in the paper. These equations are written in the form of a vector partial differential equation of the second order with symmetric matrix coefficients. The fundamental solution (matrix) is defined for this vector partial differential equation. A new method of the numerical computation of values of the fundamental solution is suggested. This method consists of the following: the Fourier transform with respect to space variables is applied to vector equation for the fundamental solution. The obtained vector ordinary differential equation has matrix coefficients depending on Fourier parameters. Using the matrix computations a solution of the vector ordinary differential equation is numerically computed. Finally, applying the inverse Fourier transform numerically we find the values of the fundamental solution. Computational examples confirm the robustness of the suggested method for 2D quasicrystals with arbitrary type of anisotropy.     

利用齐次平衡法求GP方程的Jacobi椭圆函数解

描述玻色-爱因斯坦凝聚（BEC）的有效而方便的方程是著名的Gross-Pitaevskii（GP）方程。本文在将GP方程变换为非线性薛定谔方程（NLS）的基础上，利用齐次平衡法求出了Gross-Pitaevskii（GP）方程的一系列Jacobi椭圆函数解。     

Viscosity solutions for the dynamic programming equations

In a previous paper the author has introduced a new notion of a (generalized) viscosity solution for Hamilton-Jacobi equations with an unbounded nonlinear term. It is proved here that the minimal time function (resp. the optimal value function) for time optimal control problems (resp. optimal control problems) governed by evolution equations is a (generalized) viscosity solution for the Bellman equation (resp. the dynamic programming equation). It is also proved that the Neumann problem in convex domains may be viewed as a Hamilton-Jacobi equation with a suitable unbounded nonlinear term.