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.     

复合欧拉函数方程φ(φ(n-φ(φ(n))))=4,6的正整数解

研究了复合欧拉函数方程φ(φ(n-φ(φ(n))))=4,6的可解性问题,其中φ(n)为欧拉函数.利用初等数论内容及计算方法分别得到了两个方程的所有正整数解.求解方法简洁有效,避免繁琐的求解过程,方法可用以求解其他类似复合欧拉函数方程.     

变系数耦合KdV方程组的复合型新解

通过函数变换与第二种椭圆方程相结合的方法,构造变系数耦合KdV方程组的复合型新解.步骤一、给出第二种椭圆方程的几种新解.步骤二、利用函数变换与第二种椭圆方程相结合的方法,在符号计算系统Mathematica的帮助下,构造变系数耦合KdV方程组的由Riemannθ函数、Jacobi椭圆函数、双曲函数、三角函数和有理函数组合的复合型新解,这里包括了孤子解与周期解复合的解、双孤子解和双周期解.     

寻找具有三个任意函数的变系数KdV-MKdV方程的类孤波解的新方法

给出了求具有三个任意函数的变系数非线性演化方程的类孤波解的截断展开方法.这种方法的关键是首先把形式解设为几个待定函数的截断展开形式,从而可将变系数非线性演化方程转化为一组待定函数的代数方程,然后进一步给出容易积分的待定函数的常微分方程组,从而构造出相应的类孤波解.     

保费随机复合二项模型的Gerber-shiu折现罚金函数

考虑保费随机收取的复合二项模型.得到了其Gerber-shiu折现罚金函数满足的递推公式,瑕疵更新方程及其渐近解,并且通过构造一个相关的复合几何分布函数,得到了这个更新方程的解析解.相应的也得到了一些相关精算量的渐近表示和分布函数,如破产前瞬时盈余分布的渐近解,导致破产的索赔额的分布函数.     

一类动力学中非线性偏微分方程解的研究与分析

通过Ibragimov新守恒定理的基本思想,构造了动力学Drinfel’d-Sokolov-Wilson(DSW)方程的局部守恒定律.并且利用Hirota双线性形式推导出该方程的双线性Backlund变换,在双线性Backlund变换的基础上,获得该方程的行波解.然后构造DSW方程的正四次函数、二次函数及指数函数所组合的形式解,另外构造了正四次函数、二次函数、三角函数和双曲函数组合的形式解,通过计算求解出DSW方程相应的高阶Lump解与Kink解、高阶Lump解与周期波解的相互作用解,同时验证了该方程解的存在性.     

(2+1)维modified Zakharov-Kuznetsov方程的复合型新解

给出函数变换,变量分离形式解与第一种椭圆方程相结合的方法,构造了(2+1)维modified Zakharov-Kuznetsov(m ZK)方程的多种复合型新解.步骤一,给出两种函数变换,将(2+1)维m ZK方程转化为能够获得变量分离解的非线性发展方程.步骤二,给出非线性发展方程的变量分离形式解,通过第一种椭圆方程及其相关结论,构造了(2+1)维m ZK方程的双孤子解和双周期解等复合型新解.     

广田双线性方法与(3+1)维Jimbo-Miwa-Like方程的几种新解

基于广田双线性方法,将(3+1)维Jimbo-Miwa-Like方程化为双线性形式,在此基础上,首先利用试探函数法与符号计算系统Mathematica,获得了方程的由指数函数、三角函数和双曲函数形式的单函数解;另外,获得了由三角函数、指数函数与双曲函数两两组合的复合型解.最后通过选取适当的参数,做出一部分精确解的图形来说明它们的性质.     

非线性耦合KdV方程组的一种新求解法

本文研究了构造非线性耦合Kd V方程组的无穷序列复合型新解的问题.利用函数变换与辅助方程相结合的方法,获得了非线性耦合Kd V方程组的自由Riemannθ函数、Jacobi椭圆函数、双曲函数和三角函数两两组合的无穷序列复合型新解.这些解包括了双弧子解、双周期解和弧子解与周期解复合的解.     

应用拓展双曲函数方法求KP方程的新精确解

本文引入行波解,并应用拓展双曲函数方法,求得（2＋1）维Kadomtsev-Petviashvili（KP）方程的精确解.通过应用拓展双曲函数方法,可以得到关于方程的一类有理函数形式的孤立波,行波以及三角函数周期波的精确解,并且此方法适用于求解一大类非线性偏微分进化方程.     

Solving the Korteweg-de Vries equation by its bilinear form: Wronskian solutions

A broad set of sufficient conditions consisting of systems of linear partial differential equations is presented which guarantees that the Wronskian determinant solves the Korteweg-de Vries equation in the bilinear form. A systematical analysis is made for solving the resultant linear systems of second-order and third-order partial differential equations, along with solution formulas for their representative systems. The key technique is to apply variation of parameters in solving the involved non-homogeneous partial differential equations. The obtained solution formulas provide us with a comprehensive approach to construct the existing solutions and many new solutions including rational solutions, solitons, positons, negatons, breathers, complexitons and interaction solutions of the Korteweg-de Vries equation.

     

Novel composite function solutions of the modified KdV equation

A Wronskian form expansion method is proposed to construct novel composite function solutions to the modified Korteweg-de Vries (mKdV) equation. The method takes advantage of the forms and structures of Wronskian solutions to the mKdV equation, and Wronskian entries do not satisfy linear partial differential equations. The method can be automatically carried out in computer algebra (for example, Maple).     

Symmetry classification of the Gardner equation with time-dependent coefficients arising in stratified fluids

We perform symmetry classification of a variable-coefficient combined KdV-mKdV equation. That is, the equation combining the Korteweg-de Vries (KdV) and modified Korteweg-de Vries (mKdV) equations, or also known as the Gardner equation. The direct method of group classification is utilized to specify the forms of these time-dependent coefficients.     

A modified tanh–coth method for solving the KdV and the KdV–Burgers’ equations

In this work we use a modified tanh–coth method to solve the Korteweg-de Vries and Korteweg-de Vries–Burgers’ equations. The main idea is to take full advantage of the Riccati equation that the tanh-function satisfies. New multiple travelling wave solutions are obtained for the Korteweg-de Vries and Korteweg-de Vries–Burgers’ equations.     

Three types of exact solutions to Wick-type generalized stochastic Korteweg-de Vries equation

A Wick-type generalized stochastic Korteweg-de Vries equation is researched. By means of Hermite transformation, white noise theory and Riccati equation mapping method, three types of exact solutions to the generalized stochastic Korteweg-de Vries equation, which include the functional solutions of hyperbolic-exponential type, trigonometric-exponential type and exponential type, are derived.     

Higher Painlevé transcendents as special solutions of some nonlinear integrable hierarchies

It is well known that the self-similar solutions of the Korteweg-de Vries equation and the modified Korteweg-de Vries equation are expressed via the solutions of the first and second Painlevé equations. In this paper we solve this problem for all equations from the Korteveg-de Vries, modified Korteweg-de Vries, Kaup-Kupershmidt, Caudrey-Dodd-Gibbon and Fordy-Gibbons hierarchies. We show that the self-similar solutions of equations corresponding to hierarchies mentioned above can be found by means of the general solutions of higher-order Painlevé hierarchies introduced more than ten years ago.     

A finite difference method for the Korteweg-de Vries and the Kadomtsev-Petviashvili equations

A linearized implicit finite difference method for the Korteweg-de Vries equation is proposed and straightforwardly extended to the Kadomtsev-Petviashvili equation. We investigate the order of accuracy of the method and prove the method to be unconditionally linearly stable. The numerical experiments for the Korteweg-de Vries and the Kadomtsev-Petviashvili equations are carried out with various conditions. Numerical results for the collision of two lump type solitary wave solutions to the Kadomtsev-Petviashvili equation are also reported.     

Non dispersive solutions of the generalized Korteweg-de Vries equations are typically multi-solitons

We consider solutions of the generalized Korteweg-de Vries equations (gKdV) which are non dispersive in some sense and which remain close to multi-solitons. We show that these solutions are necessarily pure multi-solitons. For the Korteweg-de Vries equation (KdV) and the modified Korteweg-de Vries equation (mKdV) in particular, we obtain a characterization of multi-solitons and multi-breathers in terms of non dispersion.     

Symmetry reductions for a dissipation-modified KdV equation

In this paper we give a group classification for a dissipation-modified Korteweg-de Vries equation by means of the Lie method of the infinitesimals. We prove that, by using the nonclassical method, we get several new solutions which are unobtainable by Lie classical symmetries. We obtain nonclassical symmetries that reduce the dissipation-modified Korteweg-de Vries equation to ordinary equations with the Painlevé property. These solutions have not been derived elsewhere by the singular manifold method.     

Exact travelling wave solutions of the dissipative coupled Korteweg-de Vries equation

This paper employs the theory of planar dynamical systems and undetermined coefficient method to study travelling wave solutions of the dissipative coupled Korteweg-de Vries equation. The possible kink profile solitary wave solutions and approximate damped oscillatory solutions of the equation are obtained by using undetermined coefficient method. Error estimates indicate that the approximate solutions are meaningful.