Burgers方程的一类自相似解

利用李群理论中的伸缩变换群,将二阶非线性偏微分方程-Burgers方程化为一类Riccati方程和三类二阶非线性常微分方程,从而Riccati方程和这三类二阶非线性常微分方程给出了Burgers方程的自相似解的表现形式.     

带随机初值的随机偏微分方程整体解的存在性

研究了一类带随机初值并且由分数次Brownian运动驱动的随机偏微分方程.借助于Kolmogorov准则,建立了整体Lipschitz条件下此类随机偏微分方程的一个解.同时证明了局部Lipschitz条件下整体解的存在性.     

Lin- Reissner-Tsien方程的自相似解

Lin-Reissner-Tsien方程描述了在跨音速近似下的不稳定跨音速流动.通过相似变换,将Lin-Reissner-Tsien方程简化为一个常微分方程.然后解析求解所得到的方程,并在某些情况下得到的正好是精确解.上述情况下无法得到精确解时,给出了数值模拟.还得到了行波解.     

非线性边界条件下二阶奇异差分方程的正解

本文我们考虑如下二阶奇异差分边值问题\begin{equation*}\begin{cases}-\Delta^{2} u(t-1)=\lambda g(t)f(u) ,\ t\in [1,T]_\mathbb{Z},\\u(0)=0,\\ \Delta u(T)+c(u(T+1))u(T+1)=0,\end{cases}\end{equation*}正解的存在性. 其中, $\lambda>0$, $f:(0,\infty)\rightarrow \mathbb{R}$ 是连续的,且允许在~$0$ 处奇异.通过引入一个新的全连续算子, 我们建立正解的存在性.     

一类拟线性偏微分方程组的Laplace空间解的形式相似性

本作研究了一类拟线性偏微分方程组在不同的外边界条件(无穷大外边界，封闭外边界，定值外边界)和随机时间变化的内边界条件下的初值问题在Laplace空间的解的形式相似性，它能很好地帮助我们认识模型遵从的内在规律及设计相应的应用软件．     

Large-Time Behavior of Periodic Solutions to Fractal Burgers Equation with Large Initial Data

The asymptotic behavior of periodic solutions to fractal nonlinear Burgers equation is considered and the initial data are allowed to be arbitrarily large.The exponential decay estimates of the solutio...     

Regularity for Almost Convex Viscosity Solutions of the Sigma-2 Equation

We establish interior regularity for almost convex viscosity solutions of thesigma-2 equation.     

二阶非线性摄动微分方程解的振动性与渐近性

研究了一类二阶非线性摄动微分方程解的振动性与渐近性,建立了四个新的振动性与渐近性定理,推广和改进了已知的一些结果.     

Exact Solutions of the Wick-typ e KdV-Burgers Equation

In this paper, we consider the wick-type KdV-Burgers equation with variable coe?cients. By using Tanh method with the aid of Hermite transformation, we deduce the exact solutions which include hyperbolic-exponential, trigonometric-exponential and expo-nential function solutions for the considered equation.     

Traveling-Wave Solutions of the Calogero-Degasperis-Fokas Equation in 2+1 Dimensions

Soliton solutions are among the more interesting solutions of the (2+1)-dimensional integrable Calogero-Degasperis-Fokas (CDF) equation. We previously derived a complete group classiffication for the CDF equation in 2+1 dimensions. Using classical Lie symmetries, we now consider traveling-wave reductions with a variable velocity depending on an arbitrary function. The corresponding solutions of the (2+1)-dimensional equation involve up to three arbitrary smooth functions. The solutions consequently exhibit a rich variety of qualitative behaviors. Choosing the arbitrary functions appropriately, we exhibit solitary waves and bound states.__________Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 1, pp. 44–55, July, 2005.     

具非线性扩散系数的中立双曲型阻尼偏微分方程组解的振动性

研究一类具非线性扩散系数的中立双曲型阻尼偏微分方程组的振动性.通过利用R iccati变换、微积分技巧,获得了该方程组在两类边值条件下解振动的一些充分条件.     

Traveling-Wave Solutions of the Schwarz–Korteweg–de Vries Equation in 2+1 Dimensions and the Ablowitz–Kaup–Newell–Segur Equation Through Symmetry Reductions

One of the more interesting solutions of the (2+1)-dimensional integrable Schwarz–Korteweg–de Vries (SKdV) equation is the soliton solutions. We previously derived a complete group classification for the SKdV equation in 2+1 dimensions. Using classical Lie symmetries, we now consider traveling-wave reductions with a variable velocity depending on the form of an arbitrary function. The corresponding solutions of the (2+1)-dimensional equation involve up to three arbitrary smooth functions. Consequently, the solutions exhibit a rich variety of qualitative behaviors. In particular, we show the interaction of a Wadati soliton with a line soliton. Moreover, via a Miura transformation, the SKdV is closely related to the Ablowitz–Kaup–Newell–Segur (AKNS) equation in 2+1 dimensions. Using classical Lie symmetries, we consider traveling-wave reductions for the AKNS equation in 2+1 dimensions. It is interesting that neither of the (2+1)-dimensional integrable systems considered admit Virasoro-type subalgebras.     

On the equivalence of non‐iterative transformation methods based on scaling and spiral groups

The non‐iterative numerical solution of nonlinear boundary value problems is a subject of great interest. The present paper is concerned with the theory of non‐iterative transformation methods (TMs). These methods are defined within group invariance theory. Here we prove the equivalence between two non‐iterative TMs defined by the scaling group and the spiral group, respectively. Then, we report on numerical results concerning the steady state temperature space distribution in a non‐linear heat generation model. These results improve the ones, available in the literature, obtained by using the invariance with respect to a spiral group. Copyright © 2009 John Wiley & Sons, Ltd.     

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 .     

Viscosity dominated flows with temperature‐dependent thermal conductivity

In this paper we formulate a non‐isothermal, non‐Newtonian Hele–Shaw flow with nonlinear thermal conductivity from the injection molding. Then we study the existence of the resulting nonlinear system. Copyright © 2005 John Wiley & Sons, Ltd.     

低模态下弱阻尼KdV方程约化形式的数值分析

给出了低模态下弱阻尼KdV方程近似惯性流形的约化形式,并在五模态下作数值分析,有关数值分析结果与非线性谱分析结果相类似     

Comparison between variational iteration method and homotopy perturbation method for linear and nonlinear partial differential equations with the nonhomogeneous initial conditions

In this study, linear and nonlinear partial differential equations with the nonhomogeneous initial conditions are considered. We used Variational iteration method (VIM) and Homotopy perturbation method (HPM) for solving these equations. Both methods are used to obtain analytic solutions for different types of differential equations. Four examples are presented to show the application of the present techniques. In these schemes, the solution takes the form of a convergent series with easily computable components. The present methods perform extremely well in terms of efficiency and simplicity. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010     

具变指数非线性拟抛物方程弱解的存在性

虑一类变指数的非线性拟抛物方程的初值问题.在一些初值的假定下,基于时间离散化方法构造逼近解.通过对逼近解的一致性估计,证明了弱解的存在性.     

Gaussian Scenario for the Heat Equation with Quadratic Potential and Weakly Dependent Data with Applications

For a suitable scaling of the solution to the one-dimensional heat equation with spatial-dependent coefficients and weakly dependent random initial conditions, the convergence to the Gaussian limiting distribution is proved. The scaling proposed and methodology followed allow us to obtain Gaussian scenarios for related equations such as the one-dimensional Burgers equation as well as for the multidimensional formulation of both the heat and Burgers equations. Furthermore, the investigation of non-Gaussian scenarios is opened with a different proposed scaling, proving the convergence of the second-order moments.      

Effective Boundary Conditions for the Heat Equation with Interior Inclusion

Of concern is the scenario of a heat equation on a domain that contains a thin layer, on which the thermal conductivity is drastically different from that in the bulk. The multi-scales in the spatial variable and the thermal conductivity lead to computational difficulties, so we may think of the thin layer as a thickless surface, on which we impose effective boundary conditions(EBCs). These boundary conditions not only ease the computational burden, but also reveal the effect of the inclusion. In this paper, by considering the asymptotic behavior of the heat equation with interior inclusion subject to Dirichlet boundary condition, as the thickness of the thin layer shrinks, we derive, on a closed curve inside a two-dimensional domain, EBCs which include a Poisson equation on the curve, and a non-local one. It turns out that the EBCs depend on the magnitude of the thermal conductivity in the thin layer,compared to the reciprocal of its thickness.