流体力学中的强迫孤立波

简要讨论了８０年代发现的以先驱孤立波和非传播孤立波为代表的流体力学中的强迫孤立波．介绍了这些孤立波产生的方法、力学模型、控制方程、研究现状及有待解决的问题．      

微结构固体中钟型与扭结孤立波的演化

根据Mindlin理论和Murnaghan模型,首先建立了描述耗散、频散及非线性微结构固体中一维纵波传播的一种简单模型.然后利用有限差分方法,数值模拟了微结构效应对钟型与扭结孤立波演化的影响. 结果表明,随着微结构效应的减弱,钟型孤立波的幅度衰减以及非对称特征变得越来越明显;随着微结构效应的增强,扭结孤立波顶部出现的“帽子”状变化以及由此产生的非对称特征变得越来越明显.      

非传播孤立波和表面张力

讨论关于表面张力的实验与理论分析之间的矛盾．把表面张力的能量当作高阶小量、导出了非传播孤立波的基本方程，得到的解与实验结果相符．     

考虑表面张力的非传播孤立波

本文考虑了表面张力,用多重尺度法导出了与立方 Schrodinger 方程相类似的非传播孤立波的基本方程,得到了非传播孤立波解。用毛细重力波理论解释了非传播孤立波横向谐振中波峰尖、波谷平的原因。在σ～kh 平面上首次给出了可产生非传播孤立波的二个参数区,但现有的实验点都在区域(1)中。     

孤立波与孤子

简要介绍了孤立波和孤子研究中的一些关键过程,以及基本方程和研究方法.     

位移浅水内孤立波

研究两层浅水系统中的内孤立波,该系统由两层常密度不可压缩无黏性水组成。利用Lagrange坐标和Hamilton原理,推导了两层浅水系统的位移浅水内波方程,并进一步导出了两层浅水系统的位移内孤立波解。数值实验表明,位移内孤立波与经典的KdV内孤立波吻合很好,说明Lagrange坐标和Hamilton方法适用于内波分析,可以为构造内波分析的保辛方法提供一种途径。     

基础力学课程考试改革应充分反映课程的教学要求

通过对现行基础力学课程考试中存在的问题和近年来基础力学考试改革现状的分析,根据基础力学课程内容多、课时多、修课人数多的特点, 提出了基础力学考试改革的新理念和操作方法, 指出基础力学考试改革应充分反映课程的教学要求, 而且应有利于对课程教与学的良性促进.     

非传播孤立波和表面张力

本文讨论了关于表面张力的实验与理论分析之间的矛盾把表面张力的能量当作高阶小量、导出了非传播孤立波的基本方程，得到的解与实验结果相符。     

Solitary wave interaction

The interaction between solitary wave solutions to a double sine-Gordon equation is examined numerically. Depending on the velocity, formation of breather-like modes or quasi solitonic behaviour are observed when a 2δ-kink interact with a 2π-antikink. As a result of collision between a (2π-2δ)-kink and a (2π-2δ)-antikink two 2δ-kink-antikink pairs always appear.     

Solitary wave interactions and reshaping in coupled systems

The interaction of the components of composite solitary waves governed by nonlinear coupled equations is studied numerically. It is shown how predictions of the known exact traveling wave solutions may help in understanding and explaining the process of reshaping seen as head-on and take-over collisions of individual solitary waves. The most interesting results concern the switch in the sign or the periodic modulation of the amplitude of the solitary wave and the direction of its propagation due to collisions.     

Solitary wave propagation in a two-dimensional lattice

We construct a family of exact planar solitary wave solutions in a two-dimensional lattice. The system under consideration is a scalar two-dimensional extension of a nonintegrable Fermi–Pasta–Ulam problem with a piecewise quadratic potential. The constructed solutions exhibit an anisotropic dependence on the angle of propagation. Through a detailed analysis of explicit solutions, we show that conventional quasicontinuum models fail to fully describe this dependence. However, a truncated series approximation of the constructed solution that includes sufficiently short wavelengths captures this effect quite well.     

Solitary wave decay in non-linear faraday resonance

This investigation studies possible mechanisms by which localised disturbances in a vertically oscillating long channel undergo transition to instability. Modulated cross-waves with a carrier frequency close to natural are considered. The channel is subjected to oscillations with the frequency shifted slightly below twice the natural value. The waves are considered to be described by the Miles equation (Miles, 1984). We report here numerical investigations of the instability of various solitary wave disturbances for a range of controlling parameters. Certain mechanisms describing such transitions have been predicted theoretically by Il'ichev (1998).     

Solitary wave trains in a cold plasma

The existence of traveling solitary waves, the products of modulation instability in a cold quasi-neutral plasma, is considered. Solitary waves of this type (solitary wave trains) are formed as a result of bifurcation from a nonzero wave number of the linear wave spectrum. It is shown that the complete system of equations describing the wave process in a cold plasma has solutions of the solitary wave train type, at least when the undisturbed magnetic field is perpendicular to the wave front. Sufficient conditions of existence of solitary wave trains in weakly dispersive media are also formulated.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 5, pp. 154–161, September–October, 1996.     

Nonautonomous bright soliton solutions on continuous wave and cnoidal wave backgrounds in blood vessels

We discuss the dissipative nonlinear Schrödinger equation (NLSE) with a variable coefficient in blood vessels via a NLSE-based constructive method and obtain exact nonautonomous soliton solutions including bright soliton solutions on continuous wave (cw) and cnoidal wave (cnw) backgrounds. Moreover, the dynamical behaviors of these soliton solutions are studied. The impact of the cw background on the separating and interactive soliton behaviors is investigated. These behaviors of the soliton can be modulated by adjusting the amplitude of background wave. The propagation behaviors of solitons on the cnw background in different dispersion systems are also studied. These results are potentially useful for future experiments in various blood vessels.     

Solitary wave packets beneath a compressed ice cover

A family of plane solitary wave packets of a small (but finite) amplitude on the surface of an ideal incompressible fluid of finite depth beneath an ice cover is described. The solitary wave trains correspond to solutions of the two-dimensional system of Euler’s equations of an ideal incompressible fluid of the type of a traveling wave which decreases at infinity and has identical phase and group velocities. The ice cover is simulated by an elastic Kirchhoff-Love plate freely floating on the fluid surface in the compressed state.     

Solitary wave and similarity solutions of the combined KdV equation

In this paper, we discuss a property of solitary wave solutions of the combined KdV equation. Meantime, we point out that the combined KdV equation can be reduced to the Painlevé equation. Furthermore, utilizing special transformations of similarity variables, we derive a kind of new partial differential equations.