KK方程和改进的Boussinesq方程的新精确解

应用改进的Fan's代数方法,得到了KK方程和改进的Boussinesq方程的一系列新精确解,包括孤立波解、类孤立波解、纽结波解、奇异纽结波解和三角函数周期解.     

非线性波方程的精确孤立波解

立了一种求解非线性波方程精确孤立波解的双曲函数方法,并在计算机代数系统上加以实现,推导出了一大批非线性波方程的精确孤立波解.方法的基本原理是利用非线性波方程孤立波解的局部性特点,将方程的孤立波解表示为双曲函数的多项式,从而将非线性波方程的求解问题转化为非线性代数方程组的求解问题.利用吴消元法或Gröbner基方法在计算机代数系统上求解非线性代数方程组, 最终获得非线性波方程的精确孤立波解,其中有很多新的精确孤立波解.     

一类广义Zakharov方程的精确行波解

本文研究了一类广义Zakharov方程的精确解行波解的问题.利用改进的G/G展开方法,借助于计算机代数系统Mathematica,获得了具有重要物理背景的广义Zakharov方程一系列新的含有多个参数的精确行波解,这些解包括孤立波解,双曲函数解,三角函数解,以及有理函数解.     

若干强非线性问题的近似解析解

本文采用作者提出的修正的完全近似法,分析几个强非线性振动和波动问题。首先研究一类虽非线性振动问题,并对修正的van der Pol振子,较为简捷地给出了它的极限环解的二阶近似表达式,与文献[3]中用推广的平均法得出的结果一致。接着分析修正的KdV方程,得到了孤立波的正确的二阶渐近解。最后,对于有五阶色散项的推广的KdV方程,在三阶近似下,导得了孤立波的渐近解,解析地给出了振荡型孤立波解的形式。这些结果表明,修正的完全近似法可以有效地应用于一些强非线性数学问题的研究。     

具有N-peakon的新可积模型与孤子方程的代数几何解

在孤立子理论中, 寻找新的可积系统是最基础而重要的内容之一. 而如何有效的求得一类孤子方程的精确解, 并研究该精确解的性质, 一直是一个基本而又富有挑战性的课题. 本文便是从这两个方面展开, 一方面构造了两个具有N-peakon 的新可积系统, 为目前并不丰富的具有尖孤子解的可积非线性家族提供了极为重要的可积动力模型; 另一方面, 基于超椭圆代数曲线理论, 本文对Lax 对的有限展开法进行了改进, 并将其拓广到求解相联系的孤子方程可积形变后的代数几何解, 给出了著名的KdV(Korteweg de Vries) 6 方程的解. 进一步, 通过研究与孤子方程族相应的亚纯函数、Baker-Akhiezer 函数和超椭圆曲线的渐近性质和代数几何特征, 本文摆脱了现有代数几何方法中使用Riemann 定理的限制, 构造了mKdV (modified Korteweg de Vries) 型方程和混合AKNS (Ablowitz Kaup Newell Segur)方程等孤子方程的代数几何解. 为构造高阶矩阵谱问题所对应的孤子方程族的代数几何解提供了有力的工具.     

一些非线性发展方程的有界钟状代数孤立波解

本文以非线性发展方程的有界钟状代数孤波解为研究对象,以Kolmogorov-Petrovskii-Piskunov(简称KPP)方程、组合KdV-mKdV方程和mKdV方程为例,利用平面动力系统知识,分析有界钟状代数孤立波解出现的条件,提出求解的方法,称之为代数孤波解解法(简称ASW解法),分别获得这三个方程的代数孤立波解.     

自治广义非线性泛函微分方程在奇异点附近解的结构性质

本文讨论一类自治广义非线性泛函微分方程在孤立奇异点附近解的结构性质．首先给出点则形式及标准奇异点的定义，然后讨论横截解的存在性及个数，得到了这类方程的初值问题在孤立奇异点处要么无解，要么仅有两个横截解的结果，最后论述了孤立奇异点具有吸引或排斥的性质，并通过例子，发现了某种类似分支的现象．     

一类非线性奇异积分方程的离散近似解及其误差估计

当函数f(x,t,u)满足一些[1]中常假定的条件时,我们可借助算子S~(N)和不等式证明非线性奇异积分方程有唯一的离散近似解,这个解可用关于距离的逐次逼近法得到.     

非线性波方程准确孤立波解的符号计算

该文将机械化数学方法应用于偏微分方程领域，建立了构造一类非线性发展方程孤立波解的一种统一算法，并在计算机数学系统上加以实现，推导出了一批非线性发展方程的精确孤立波解．算法的基本原理是利用非线性发展方程孤立波解的局部性特点，将孤立波表示为双曲正切函数的多项式．从而将非线性发展方程（组）的求解问题转化为非线性代数方程组的求解问题．利用吴文俊消元法在计算机代数系统上求解非线性代数方程组，最终获得非线性发展方程（组）的准确孤立波解.     

带位移非线性奇异积分方程的离散近似解

将积分区间划分为2N 等分后,我们定义了带位移的离散奇异算子■~(N).对于广义 Hilder 空间 H_(α,β,γ)中的函数 u(x),被带位移奇异算子作用后与■(N)_u 的差在分点处是 O((ln N)/(Nγ)).算子■(N)是一致有界的。利用它,我们给出了一类带位移的非线性奇异积分(哥西核)方程的离散近似解     

Explicit Traveling Wave Solutions and Their Dynamical Behaviors for the Coupled Higgs Field Equation

In this paper, we focus on the traveling wave solutions of the coupled Higgs field equation from the perspective of dynamical systems. Through the phase portraits, in addition to periodic wave solutions and solitary wave solutions, we also obtain explicit periodic singular wave solutions, singular wave solutions and kink wave solutions, which were not found in the previous works. The dynamical behavior of these solutions and their internal relations are revealed through asymptotic analysis. The results will help supplement the study of field equation.     

关于奇异二阶微分方程（Φ（X’））’＋f（t，X）＝0的某些可解准则

本文讨论了一类右端具有奇异性的二阶常微分方程的边值问题，证明了当ｆ（ｔ，ｘ）关于ｔ的奇异程度大于某值时，边值问题无解，而当奇异程度小于某值时，边值问题有解．关于ｕ在ｕ＝０的奇异程度没有限制．     

Optimal system and approximate solutions of nonlinear dissipative media

In this paper, the problem of approximate symmetries of a class of nonlinear wave equations with a small nonlinear dissipation has been investigated. In order to compute the first-order approximate symmetry, we have applied the method that was proposed by Valenti basically based on the expansion of the dependent variables in perturbation series but removing the drawback of the impossibility to work in hierarchy in calculating symmetries. The algebraic structure of the approximate symmetries is discussed, an optimal system of one-dimensional subalgebras is defined and constructed, and, finally, some invariant solutions corresponding to the resulted symmetries are obtained.     

Overdetermined systems of first order partial differential equations with singular solution

We study overdetermined systems of first order partial differential equations with singular solutions. The main result gives a characterization of such systems and asserts that the singular solution is equal to the contact singular set.     

Bäcklund transformations and abundant exact explicit solutions of the Sharma-Tasso-Olver equation

By using an extension of the homogeneous balance method and Maple, the Bäcklund transformations for the Sharma-Tasso-Olver equation are derived. The connections between the Sharma-Tasso-Olver equation and some linear partial differential equations are found. With the aid of the transformations given here and the computer program Maple 12, abundant exact explicit special solutions to the Sharma-Tasso-Olver equation are constructed. In addition to all known solutions re-deriving in a systematic way, several entirely new and more general exact explicit solitary wave solutions can also be obtained. These solutions include (a) the algebraic solitary wave solution of rational function, (b) single-soliton solutions, (c) double-soliton solutions, (d) N-soliton solutions, (e) singular traveling solutions, (f) the periodic wave solutions of trigonometric function type, and (g) many non-traveling solutions. By using the Airy’s function and the Bäcklund transformations obtained here, the exact explicit solution of the initial value problem for the STO equation is presented. The variety of the structure of the solutions for the Sharma-Tasso-Olver equation is illustrated.     

p-Laplacian算子系统奇异边值问题的正解

综合利用锥上的不动点指数理论和上下解方法,讨论了一类含两个参数的p- Laplacian算子系统奇异边值问题正解的存在性、非存在性和多解性,得到了一条由参数决定的连续曲线,它决定了解的分布情况,从而获得了新的结论.     

广义系统的Hamilton矩阵与H\-2代数Riccati方程的稳定化解

研究线性连续广义系统的Hamilton矩阵及H\-2代数Riccati方程.　提出一个标准的广义H\-2代数Riccati方程及对应的Hamilton矩阵，给出该Hamilton矩阵的几个重要性质. 在此基础上，得到该广义H\-2代数Riccati方程的稳定化解存在的一个充分条件并给出求解方法.此条件具有一般性, 主要定理是正常系统相应结果的推广.     

Uniform convergence of the rectangle method for singular integral equation with the Hölder density

We study an approximate method for solving singular integral equations. It implies an approximation of a singular operator by means of a compound quadrature formula similar to the rectangle one. The corresponding systems of linear algebraic equations are solvable if so is the integral equation, while its coefficients satisfy the strong ellipticity condition. Under these restrictions we obtain a bound for the rate of convergence of solutions of systems of linear equations to the solution of the considered integral equation in the uniform vector norm.     

Collocation Trefftz methods for the stokes equations with singularity

This study explores the boundary methods for the two‐dimensional homogeneous Stokes equations and investigates the particular solutions (PS) satisfying the Stokes equations. Smooth solutions for the Stokes equations are provided by explicit fundamental solutions (FS) and PS in this study, and singular corner solutions are also provided from linear elastostatics given in Li et al. ([Eng. Anal. Bound. Elem. 34 (2009), 533‐648, 2009). A new singularity model with an interior crack is proposed and solved by the collocation Trefftz method (CTM). The proposed method achieves highly accurate solutions with the first leading coefficient having 10 significant digits. These solutions may be used as a benchmark for testing results obtained by other numerical methods. Error bounds are derived for the CTM solutions using the PS. For a general corner, the exponent ν_k in r can only be obtained by numerical solutions of a system of nonlinear algebraic equations. Therefore, the combined method using many FS plus a few singular solutions is inevitable in most applications. For singularity problems, combining a few singular solutions with the FS is an advanced topic and is successfully implemented in Lee et al. (Eng. Anal. Bound. Elem. 24 (2010), 632–654); however, combining a few singular solutions with the smooth PS fails to converge in the first leading coefficient. As a result, the aforementioned method is not applicable to the singularity problems addressed in this article. With the help of particular and singular solutions, the hybrid Trefftz method with Lagrange multipliers can be developed for the Stokes equations. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013