N=2 超对称KdV 方程的双线性形研究

利用双线性方法研究$N=2$超对称KdV方程. 通过适当的相关变换, 将$N=2, a=4$和$N=2, a=1$超对称KdV方程转化成双线性形式, 由此构造了相应方程的解. 对于$N=2, a=1$ 超对称KdV方程, 还得到了它的双线性B\"acklund变换和Lax 表示.     

(2+1)维广义Burgers 方程的Lie点对称, 相似约化和精确解

讨论了(2+1)维广义Burgers方程.通过Lie群方法求出了该方程的李点对称,并利用李点对称将方程进行相似约化,求出了(2+1)维广义Burgers方程的几种精确解.该方法可以用于研究更高阶的偏微分方程.     

(2+1)-维破裂孤子方程的群叶状方法和显式解

利用等变活动标架理论,研究(2+1)-维破裂孤子方程的群叶状方法和显式解.原方程的对称群的无穷维部分被用来产生整个解空间的叶状结构,于是分解系统就继承了对称群的有限维部分.求解的过程完全符号化和算法化.利用群叶状方法,破裂孤子方程的一些显式精确解被得到,这些解关于无穷维对称子群封闭.     

(2+1)维色散长波方程的非局域对称及相容Riccati展开可积性

研究了(2+1)维色散长波方程的非局域对称性和相容Riccati展开(CRE)可积性.首先,通过Painleve分析中的留数对称,将(2+1)维色散长波方程留数对称局域化,得到了与Schwartzian变量相对应的对称群;其次,基于CRE方法,证明了(2+1)维色散长波方程在CRE条件下是可积的;最后,通过求解相容性方程,构造了该方程的孤立波与椭圆周期波的相互作用解.     

矩阵方程aX2+bX+cE=O的正定解和实对称解

给出了矩阵方程aX2+bX+cE=O,a,b,c∈R,a≠0有正定解,实对称解的充分必要条件及解的一般形式.     

超对称柱KdV方程的孤子解

利用直接法将柱KdV方程超对称化.通过适当的变换,利用双线性方法将超对称柱KdV方程双线性化,由超对称Hirota双线性导数法构造出超对称柱KdV方程的单孤子解、双孤子解、三孤子解以及n孤子解的具体表达形式.     

(2+1)维Kadomtsev-Petviashvili方程的留数对称及其相互作用解

运用Painlevé截断展开方法得到(2+1)维Kadomtsev-Petviashvili(KP)方程的非局域留数对称和B?cklund变换.由于非局域对称不能直接对(2+1)维KP方程进行约化求解,因此,需要将非局域对称局域化.然后,利用相容的Riccati展开(CRE)可解的概念证明(2+1)维KP方程的CRE可解性,从而求出(2+1)维KP方程的新的相互作用解.     

矩阵方程AXB+CXD=F对称解的迭代算法

在共轭梯度思想的启发下,本文给出了迭代算法求解约束矩阵方程AXB+CXD=F的对称解及其最佳逼近.应用迭代算法,矩阵方程AXB+CXD=F的相容性可以在迭代过程中自动判断.当矩阵方程AXB+CXD=F有对称解时,在有限的误差范围内,对任意初始对称矩阵X1,运用迭代算法,经过有限步可得到矩阵方程的对称解;选取合适的初始迭代矩阵,还可以迭代出极小范数对称解.而且,对任意给定的矩阵X0,矩阵方程AXB+CXD=F的最佳逼近对称解可以通过迭代求解新的矩阵方程A(X)B+C(X)D=(F)的极小范数对称解得到.文中的数值例子证实了该算法的有效性.     

一类超线性Hill型对称碰撞方程的周期运动

本文考虑一类超线性Hill型对称碰撞方程的对称碰撞周期解的存在性、重性和分布问题.通过坐标变换的方法把碰撞相平面转化为全平面进行研究,在一类关于时间映射的超线性条件下证明有外力方程无穷多个对称碰撞调和解和对称碰撞次调和解的存在性;同时研究在没有外力时方程的对称碰撞周期解的稠密性分布.本文还给出对称碰撞方程对称碰撞周期解存在的充分条件.     

(2+1)维广义破裂孤子方程的非局域对称及相互作用解

根据截断的Painlevé分析展开法及相容Riccati展开(CRE)法,研究了(2+1)维广义破裂孤子方程的非局域对称.利用非局域对称局域化的方法,得到了与Schwarzian变量相对应的对称群.同时,证明了这个方程是CRE可积的,并给出了它的孤立波与椭圆周期波之间的相互作用解.     

Approximate additive mappings in 2-Banach spaces and related topics

In this paper, we investigate approximate additive mappings, approximate Jensen mappings and approximate quadratic mappings in 2-Banach spaces. That is, we prove the generalized Hyers-Ulam stability of the Cauchy functional equation, the Jensen functional equation and the quadratic functional equation in 2-Banach spaces.     

广义Pell方程Ax^2-By^2=4的通解公式

主要运用 Lucas 数的奇偶性,讨论了当 A, B 是适合 A〉1,2-AB 且 AB 非平方数的正整数时,广义 Pell 方程的整数解（x, y）,即给出了方程 Ax^2 -By^2=4适合gcd（x, y）=1的整数解（x, y）的通解公式。     

A study on the (2+1)-dimensional and the (2+1)-dimensional higher-order Burgers equations

The (2 + 1)-dimensional Burgers equation and the (2 + 1)-dimensional higher-order Burgers equation are investigated. The Cole–Hopf transformation method is used to carry out this study. Multiple-kink solutions are formally derived for each equation.     

Lump solutions of the 2D Toda equation

In this research, the lump solution, which is rationally localized and decays along the directions of space variables, of a 2D Toda equation is studied. The effective method of constructing the lump solutions of this 2D Toda equation is derived, and the constraint conditions that make the lump solutions analytical and positive are obtained as well. Finally, three classes of lump solutions are constructed, 3D plots, density plots, and contour plots are given to illustrate this proposed method.     

The Time-Periodic Solution to a 2D Generalized Ginzburg-Landau Equation

In this paper, we study a 2D generalized Ginzburg-Landau equation with a periodic boundary condition. The existence and uniqueness of a time-periodic solution to this equation is proved.     

Diophantine方程y~2=px(x~2+2)

设p是大于3的奇素数.本文证明了:当p≡5或7(mod 8)时,方程y~2=px(x~2+2)无正整数解(x,y);当p≡1(mod 8)时,该方程至多有1组解;当p≡3(mod 8)时,该方程至多有2组解.     

Wave propagation through a 2D lattice

Nonlinear wave propagation through a 2D lattice is investigated. Using reductive perturbation method, we show that this can be described by Kadomtsev–Petviashvili (KP) equation for quadratic nonlinearity and modified KP equation for cubic nonlinearity, respectively. With quadratic and cubic nonlinearities together, the system is governed by an integro-differential equation. We have also checked the integrability of these equations using singularity analysis and obtained solitary wave solutions.     

BOUNDARY LAYER ESTIMATION OF A SINGULAR PROBLEM WITH LIMIT EQUATION OF ORDER 2

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2+1维Ginzburg-Landau方程的精确波解

分析研究了一个具有三次增益效应和五次耗散项的2+1维Ginzburg-Landau方程.利用同解变型法并结合一个高阶辅助方程的解,成功地取得了该方程的一些新的精确行波解.     

L2-boundary integral equations for the robin problem

In this paper we study an integral equation method for the exterior Robin problem for the Helmholtz equation where the boundary condition is interpreted in the L²-sense. In particular, we derive a composite integral equation from Green's theorem which is uniquely solvable for all wave numbers.