拉普拉斯变换法求解超短脉冲方程

讨论一类超短脉冲方程,它描述超短脉冲在光纤中的传播现象,利用拉普拉斯变化法,证明了方程初边值问题古典解的存在唯一性,同时也分析了基函数的渐近性质.讨论内容既可为偏微分方程课程教学提供素材,同时也为其非线性方程的进一步研究奠定基础.     

非线性脉冲时滞抛物型偏微分方程的强迫振动性

考虑一类具强迫项的非线性脉冲时滞抛物型偏微分方程，利用脉冲时滞微分不等式，获得了该类方程的解强迫振动的若干充分判据。     

柱面上一类带有强迫项的二阶非线性方程周期解的存在性与稳定性

文献[1]对柱面上带有强迫项的二阶非线性方程作了定性分析,而要求g(φ)dφ=∞,但有些实际问题不满足此条件,因此取消这一限制,继续讨论是有意义的,本文研究以下形式的柱面上带有强迫项的二阶非线性方程:其中μ为参数,方程(H)在锁相技术中,进行二阶锁相环路的设计和理论探讨时常常出现,其它领域中也有应用.对于方程(H),我们得到解的有界性、周期解的存在性、局部唯一性、渐近稳定性的充     

高阶脉冲中立型偏泛函微分方程的强迫振动性

研究一类具高阶Laplace算子的高阶脉冲非线性中立型偏泛函微分方程的强迫振动性,利用Green公式和微分不等式方法将所讨论的脉冲中立型偏微分方程转化为脉冲中立型微分不等式的问题,获得了这类方程在三类不同边值条件下所有解强迫振动的若干充分条件.     

具非线性扩散项的脉冲抛物方程的强迫振动性

研究一类具非线性扩散项的脉冲抛物型方程解的强迫振动性问题,借助平均技巧和脉冲微分不等式,建立了该类方程在Dirichlet边值条件下所有解强迫振动的若干新的充分判据.结论充分表明振动是由脉冲效应引起的.     

一个非局部方程解的存在性

本文旨在讨论一个线性非局部方程和相应非线性方程解存在的条件，对非局部积分核作一定限制后，得到在积分核变号条件下解的存在唯一性结果。     

三个五阶非线性方程的精确解

为了得到三个五阶非线性方程的精确解,本文通过假设行波解将三个五阶非线性方程化为常微分方程并借助辅助方程法和Mathematica软件对其求解,最终获得了一系列精确解.     

非线性方程极限环的存在性

<正> 关于 Liénard 型方程(dx)/(dt)=y-F(x),(dy)/(dt)=-g(x)的极限环的存在性,已有很多工作.但对一般的非线性方程(?)有关的结果却还不多见.本文给出方程(1)存在极限环的一个充分性准则,所要求的条件比[3]的条件稍弱.同时把 Neumann 关于 Liénard 型方程极限环的个数、位置的有关结果推广到方程(1)的情况.对于更一般的非线性方程     

分析方程解的一个方法

运用动力系统定性理论,提出一种分析非线性方程解的方法,从而可以避免求解的繁琐过程,得到非线性方程解的几何形态.此方法特别适合于分析难以求出精确解的方程.     

变形色散水波方程的Auto-B(a)cklund变换、多孤子解和有理分式解

利用未知数变换并借助Mathematica软件,给出了变形色散水波方程的Auto-B(a)cklund变换以及它与热传导方程和线性方程之间的Darboux变换.进而用此变换,获得了变形色散水波方程的多孤子解、有理分式解及其他精确解.这种思路也适用于其他的非线性方程.     

Asymptotic Behavior of Forced Nonlinear Delay Differential Equations with Impulses

The purpose of this paper is to investigate the asymptotic behavior of solutions of the forced nonlinear delay differential equations with impulses Our results, which hold for linear and nonlinear equations, forced and unforced equations, impulsive and nonimpulsive equations, improve and generalize the known results recently obtained in [8]. Received September 7, 1997, Revised May 26, 1998, Accepted July 15, 1998     

均布载荷作用下波纹扁壳的非线性振动

应用轴对称旋转扁壳的非线性大挠度动力学方程,研究了波纹扁壳在均布载荷作用下的非线性受迫振动问题．采用格林函数方法,将扁壳的非线性偏微分方程组化为非线性积分微分方程组．再使用展开法求出格林函数,即将格林函数展开为特征函数的级数形式,积分微分方程就成为具有退化核的形式,从而容易得到关于时间的非线性常微分方程组．针对单模态振形,得到了谐和激励作用下的幅频响应．作为算例,研究了正弦波纹扁球壳的非线性受迫振动现象．该文的解答可供波纹壳的设计参考．     

Nonoscillation criteria for forced second order nonlinear equations

This paper is concerned with nonoscillation criteria and asymptotic behaviour for forced second order nonlinear differential equations. These results improve and include several well-known results.     

带强迫项高阶中立型微分方程的振动性和非振动性

我们给出一类强迫高阶非线性中立型时滞微分方程一切解振动的充分条件.而且,也研究了一类强迫一阶中立型方程非振动解的渐近性.     

Interval oscillation criteria for a forced second-order nonlinear differential equations with damping

In this paper, we are concerned with the oscillations in a class of forced second-order differential equations with nonlinear damping terms. By using classical variational principle and averaging technique, several new interval oscillation criteria for the equations are established, which improve and extend some known results. Example is also given to illustrate the results.     

Asymptotic behavior of solutions of forced nonlinear neutral delay differential equations with impulses

Sufficient conditions for asymptotic behavior of the solutions of nonlinear forced neutral delay differential equations with impulses are found. The results given in [2,4,6,7] are generalized and improved.     

带强迫项的高阶中立型微分方程的振动性

研究了一类强迫高阶非线性中立型时滞微分方程一切解振动的充分条件,建立了两个振动定理,推广和改进了已有结果.     

Oscillation criteria for forced second-order nonlinear differential equations with damping

In this paper, we are concerned with oscillations in a class of forced second-order differential equations with nonlinear damping terms. By using a classical variational principle and an averaging technique, several new interval oscillation criteria for the equations are established, which improve and extend some known results. An example is also given to illustrate the results.     

Nonintegrability of Parametrically Forced Nonlinear Oscillators

We discuss nonintegrability of parametrically forced nonlinear oscillators which are represented by second-order homogeneous differential equations with trigonometric coefficients and contain the Duffing and van der Pol oscillators as special cases. Specifically, we give sufficient conditions for their rational nonintegrability in the meaning of Bogoyavlenskij, using the Kovacic algorithm as well as an extension of the Morales–Ramis theory due to Ayoul and Zung. In application of the extended Morales–Ramis theory, for the associated variational equations, the identity components of their differential Galois groups are shown to be not commutative even if the differential Galois groups are triangularizable, i. e., they can be solved by quadratures. The obtained results are very general and reveal their rational nonintegrability for the wide class of parametrically forced nonlinear oscillators. We also give two examples for the van der Pol and Duffing oscillators to demonstrate our results.