周期系数三种群Lotka－Volterra混合模型分析

考虑三种群Ｌｏｔｋａ－Ｖｏｌｔｅｒｒａ周期系数模型，种群间既有捕食关系又有竞争关系，得到唯一存在全局渐近稳定周期解的条件，并举例说明条件的可行性．     

一般KdV方程的群分析

对于一般KdV方程(0,1)给出统一的相似约化,利用所得的三参数Lie点变换群,从已知解产生新的单参数解族,对于非可积情形(n=2,4,σ=-1)给出一系列的精确解或解的渐近态。     

周期系数三种群Lotka—Volterra混合模型分析

考虑三种群Ｌｏｔｋａ－Ｖｏｌｔｅｒｒａ周期系数模型，种群间既有捕食关系又有竞争关系，得到唯一存在全局渐近稳定周期解的条件，并举例文明条件的可行性。     

具有反馈控制和功能反应的两种群竞争系统的解的渐近性

讨论了具有反馈控制和功能反应的两种群竞争系统的解的渐近性质,获得了在一定条件下该种群持续生存的充分条件,以及该系统为周期系统时,存在全局渐近稳定的正周期解。     

Volteera型积分微分方程组边值问题的奇摄动

该文研究二阶积分微分方程组边值问题奇摄动，在适当的条件下，利用渐近分析方法和对角化技巧，还得解的存在性和给出解的渐近展开式与相应的余项估计．然后，应用这些结果到三阶常微分方程组边值问题的奇摄动，最后也得到解的一致有效的渐近展开式．     

三种群食饵系统的概周期解

本文研究了一类三种群概周期食饵系统 ,并给出了其存在唯一的全局渐近稳定的正概周期解的充分条件。     

二次方程Robin问题奇摄动群的估计

本文讨论了形如εy″=u（x，Y，ε）（y′）^2＋v（x，Y，ε），0＜X＜1，y（0,ε）-P1y′（0，ε）=A（ε），y（1，ε）＋P2y′（1，ε）=B（ε）的二次方程Robin问题奇摄动问题．通过引入不同量级的伸长变量，利用外部解和校正项相结合方法构造了本问题形式上的任意阶的渐近解，并利用微分不等式这一工具对所求得的解作出估计，得出一致有效的肯定结论．     

一类具有常数脉冲投放的三种群捕食系统

考虑了一类两食饵种群具有密度制约和常数脉冲投放的三种群捕食系统,证明了当无捕食者时系统存在一个正周期解,并讨论了这个正周期解的全局渐近稳定性及其条件.     

具有反馈控制的离散两种群竞争系统的概周期解

对于具有反馈控制的离散概周期两种群竞争系统的概周期解问题,进行了深入的讨论,得到了该系统存在唯一的一致渐近稳定概周期解的充分条件.     

具有时滞的N种群Lotka-Volterra竞争系统的周期解

讨论了具有时滞的N种群Lotka—Voltterra竞争系统，利用重合度理论和Lyapunov泛函方法．得到了该系统至少存在一个严格正周期解及其全局渐近稳定性的充分条件，推广和改进了一些已知结果．     

常微分方程中的反问题

研究某函数或函数组是什么常微分方程的通解或特解,这可以称为常微分方程中的反问题.这类问题,可以用"微分法"来解决.研究这类问题的意义在于通过利用"微分法"及"逆向思维方法"解决反问题的过程来加强对常微分方程理论内涵的深刻理解.     

两参数非线性反应扩散积分微分方程的内层激波渐近解

研究了一类两参数非线性反应扩散积分微分奇摄动问题.利用奇摄动方法,构造了问题的外部解、内部激波层、边界层及初始层校正项,由此得到了问题解的形式渐近展开式.最后利用积分微分方程的比较定理证明了该问题解的渐近展开式的一致有效性.     

Symmetries and Large Time Asymptotics of Compressible Euler Flows with Damping

Large time asymptotics of compressible Euler equations for a polytropic gas with and without the porous media equation are constructed in which the Barenblatt solution is embedded. Invariance analysis for these governing equations are carried out using the classical and the direct methods. A new second order nonlinear partial differential equation is derived and is shown to reduce to an Euler–Painlevé equation. A regular perturbation solution of a reduced ordinary differential equation is determined. And an exact closed form solution of a system of ordinary differential equations is derived using the invariance analysis.     

On the solution of the non-local parabolic partial differential equations via radial basis functions

In this paper, the problem of solving the one-dimensional parabolic partial differential equation subject to given initial and non-local boundary conditions is considered. The approximate solution is found using the radial basis functions collocation method. There are some difficulties in computing the solution of the time dependent partial differential equations using radial basis functions. If time and space are discretized using radial basis functions, the resulted coefficient matrix will be very ill-conditioned and so the corresponding linear system cannot be solved easily. As an alternative method for solution, we can use finite-difference methods for discretization of time and radial basis functions for discretization of space. Although this method is easy to use but an accurate solution cannot be provided. In this work an efficient collocation method is proposed for solving non-local parabolic partial differential equations using radial basis functions. Numerical results are presented and are compared with some existing methods.     

奇摄动时滞反应扩散方程

研究了一类带有小延迟的微分-差分反应扩散方程初值边值问题．在适当的条件下,利用伸长变量法,构造了问题的形式渐近解．再用微分不等式理论证明了解的一致有效性．     

A New Generalized Gronwall Inequality with a Double Singularity and Its Applications to Fractional Stochastic Differential Equations

Abstract

In many cases, the existence and uniqueness of the solution of a differential equation are proved using fixed point theory. In this paper, we utilize the theory of operators and ingenious techniques to investigate the well-posedness of mild solution to semilinear fractional stochastic differential equations. We first discuss some properties of a class of Volterra integral operators and then establish a new generalized Gronwall integral inequality with a double singularity. Finally, we use the properties and integral inequality to study the well-posedness of mild solution to the semilinear fractional stochastic differential equations. One sees that it is concise and effectiveness using the previous results to investigate the well-posedness of the mild solution.     

一阶多参数模糊微分方程及定解问题

在单参数模糊微分方程基础上研究了一阶多参数模糊微分方程和模糊初值问题,利用刻画方程的解与刻画参数的关系给出了多参数模糊微分方程解存在的条件,最后给出了具体算例.表明,多参数模糊微分方程具有广泛的工程应用背景.     

具非线性边界条件的Volterra型泛函微分方程边值问题奇摄动

首先利用微分不等式理论和一些分析技巧,探讨了一类具非线性边界条件的二阶Volterra型泛函微分方程边值问题解的存在性问题.然后通过对右端边界层函数和外部解的构造,进一步研究了一类具小参数的二阶Votterra型非线性边值问题.利用微分中值定理和上、下解方法得到了边值问题解的存在性,并给出了解的关于小参数的一致有效渐近展开式.     

Semicommuting and Commuting Operators for the Heun Family

We derive the most general families of first- and second-order differential operators semicommuting with the Heun class differential operators. Among these families, we classify all the families that commute with the Heun class. In particular, we find that a certain generalized Heun equation commutes with the Heun differential operator, which allows constructing a general solution of a complicated fourth-order linear differential equation with variable coefficients whose solution cannot be obtained using Maple 16.