一类Burgers方程的孤立波解

Burgers方程在工程上有着重要的应用,它可以用来描述湍流、车队的交通流、氏族的随机迁移、化学工程中的分离等现象,对Burgers方程求解方法的研究有着重要的现实意义.对Burgers方程求解主要是应用差分和微分两方面的方法来展开求解的,1/G展开法是近年来发展起来的求解非线性偏微分方程的一种较为有效的微分解法.采用...     

大气中点源重力波的求导法计算机模式

本文首先给出了等温大气中点源重力波的解析解.然后,在此基础上建立了水平等温分层大气中点源重力波的计算机模式.从而解决了在真实大气中对点源重力波传播的数值计算问题.对大气中点源声波的传播过程也可以借助本计算机模式进行数值计算.     

非线性波方程的精确孤立波解

立了一种求解非线性波方程精确孤立波解的双曲函数方法,并在计算机代数系统上加以实现,推导出了一大批非线性波方程的精确孤立波解.方法的基本原理是利用非线性波方程孤立波解的局部性特点,将方程的孤立波解表示为双曲函数的多项式,从而将非线性波方程的求解问题转化为非线性代数方程组的求解问题.利用吴消元法或Gröbner基方法在计算机代数系统上求解非线性代数方程组, 最终获得非线性波方程的精确孤立波解,其中有很多新的精确孤立波解.     

一类广义KdV方程的孤立波精确解

本文给出求一类广义ＫｄＶ方程的孤立波精确解的方法．     

浅水中度振幅孤立波解的分支

利用平面动力系统分支方法研究浅水中度振幅方程的定性行为和孤立波解.给出了系统在不同参数条件下的相图.获得了光滑孤立波、cuspon解和周期波解的隐式表达式.对方程的光滑孤立波解、cuspon解和周期波解进行了数值模拟.获得的结果完善了相关文献已有的结果.     

一类5阶KdV方程的孤立波解

近年来,关于3阶KdV方程的孤立波解得到迅速发展,而对于5阶KdV方程的孤立波解文献报道较少.本文主要采用Sine-Cosine展开法得到了一类5阶KdV方程的孤立波解;然后利用Matlab计算软件,获得了孤立波解的图形,其结果展示了孤立子与系数之间的相互关系;最后,应用所得的结果分别得到了Lax方程, SK方程, CDG方程的孤立波解.     

微结构固体中孤立波的演变及非光滑孤立波

给出了包含宏观应变和微形变的全部二次项以及宏观应变三次项的一种新的自由能函数.利用新自由能函数并根据Mindlin微结构理论，建立了描述微结构固体中纵波传播的一种新模型.利用近来发展的奇行波系统的动力系统理论，分析了系统的所有相图分支，并给出了周期波解、孤立波解、准孤立尖波解、孤立尖波解以及紧孤立波解.孤立尖波解和紧孤立波解的得到，有效地证明了在一定条件下，微结构固体中可以形成和存在孤立尖波和紧孤立波等非光滑孤立波.此结果进一步推广了微结构固体中只存在光滑孤立波的已有结论.     

Zhiber-Shabat方程的孤立波解与周期波解

结合齐次平衡法原理并利用F展开法,再次研究了Zhiber-Shabat方程的各种椭圆函数周期解.当椭圆函数的模m分别趋于1或0时,利用这些椭圆函数周期解,得到了Zhiber-Shabat方程的各种孤子解和三角函数周期解,从而丰富了相关文献中关于Zhiber-Shabat波方程的解的类型.     

非线性波方程准确孤立波解的符号计算

该文将机械化数学方法应用于偏微分方程领域，建立了构造一类非线性发展方程孤立波解的一种统一算法，并在计算机数学系统上加以实现，推导出了一批非线性发展方程的精确孤立波解．算法的基本原理是利用非线性发展方程孤立波解的局部性特点，将孤立波表示为双曲正切函数的多项式．从而将非线性发展方程（组）的求解问题转化为非线性代数方程组的求解问题．利用吴文俊消元法在计算机代数系统上求解非线性代数方程组，最终获得非线性发展方程（组）的准确孤立波解.     

几个非线性发展方程的精确孤立波解

用行波方法研究了几个非线性发展方程，求出了这些方程的显式精确解。     

一类求行波解的线性方法

基于齐次平衡法和李志斌的 tanh函数法 ,本文得到一类简单有效的求解非线性发展方程的线性方法 .这类方法利用非线性发展方程孤立波的局部性特点 ,适当地选取函数 f 和 g,将孤波表示为 f,g的多项式 ,从而将非线性发展方程求解问题转化为非线性代数方程组的求解问题 ,再利用吴消元法求解方程组从而得到非线性发展方程的行波解     

Perturbation Theory for the Solitary Wave Solutions to a Sasa‐Satsuma Model Describing Nonlinear Internal Waves in a Continuously Stratified Fluid

The adiabatic evolution of perturbed solitary wave solutions to an extended Sasa‐Satsuma (or vector‐valued modified Korteweg–de Vries) model governing nonlinear internal gravity propagation in a continuously stratified fluid is considered. The transport equations describing the evolution of the solitary wave parameters are determined by a direct multiple‐scale asymptotic expansion and independently by phase‐averaged conservation relations for an arbitrary perturbation. As an example, the adiabatic evolution associated with a dissipative perturbation is explicitly determined. Unlike the case with the dissipatively perturbed modified Korteweg–de Vries equation, the adiabatic asymptotic expansion for the Sasa‐Satsuma model considered here is not exponentially nonuniform and no shelf region emerges in the lee‐side of the propagating solitary wave.     

Conservation Laws,Hamiltonian Structure,Modulational Instability Properties and Solitary Wave Solutions for a Higher‐Order Model Describing Nonlinear Internal Waves

Recent theoretical advances in connecting the wave‐induced mean flow with the conserved pseudomomentum per unit mass has permitted the first rational derivation of a model that describes the weakly nonlinear propagation of internal gravity plane waves in a continuously stratified fluid. Depending on the particular parameter regime examined the new model corresponds to an extended bright or dark derivative nonlinear Schrödinger equation or an extended complex‐valued modified Korteweg‐de Vries or Sasa–Satsuma equation. Mass, momentum, and energy conservation laws are derived. A noncanonical infinite‐dimensional Hamiltonian formulation of the model is introduced. The modulational stability characteristics associated with the Stokes wave solution of the model are described. The bright and dark solitary wave solutions of the model are obtained.     

Rossby惯性重力孤立波与东、西太平洋副高活动的遥相关

根据季内西太平洋副高活动异常的观测事实，考虑夏季北太平洋地区500hPa层以下的有限纬带区域，应用非线性浅水模式得到了一种孤立波。该波的产生、维持及传播与中、东太平洋副高主体的活动关系密切。 通过对这类孤立波传播特征的讨论和模式大气计算分析，发现它与夏季北太平洋副热带地区存在的位势中心的传播路径和范围比较一致，太平洋中、东部副高主体位置和强度的变化通过这种孤立波的传播可能导致西太平洋副高出现相应的变化。     

非线性演化方程的孤立波解

用齐次平衡原则和辅助微分方程方法得到了6个重要的n次非线性演化方程的孤立波解.辅助微分方程方法的主要思想是借助简单的可解微分方程的解去构造复杂的非线性演化方程的行进波解.这里简单的可解微分方程称为辅助微分方程.本文使用的辅助方程有双曲正割幂型解或双曲正切幂型解.     

Calculation of Some Integrals Describing Wave Fields

Two methods of calculating the scattering amplitude f(, ₀) of a wave scattered by the vertex of an arbitrarily shaped cone are justified. It is shown that the approximation f _d (, ₀,t) obtained by a method similar to the AbelPoisson method of summation converges uniformly in the regularity region for f. Also, the possibility of calculating f(, ₀) for N ₁( ₀) with the help of rapidly convergent integrals is proved. Bibliography: 7 titles.     

A New Kind of Schemes for the Operator Equations

This paper provides a new kind of three-layer explicit schemes for solving the operator equation. It has good stability, and suits particularly the semidiscrete problems arising from solving multi-dimensional parabolic-type equations by the finite element method. The amount of its computation time is far less than that of various economical schemes of the difference method. If the accuracy of the nonstandard finite element schemes (2.7) is not enough, it can be improved using extrapolations.     

A Multiphasic Model Describing the CO2 Injection Problem

According to the annual data, the portion of ejected carbon dioxide (CO₂) into the atmosphere is much higher in comparison to other greenhouse gases. Therefore, the development of various scenarios in order to reduce the CO₂ concentration in the atmosphere is nowadays a challenge and a relevant subject in research. The current investigation is dedicated to the modelling of a CO₂ injection into a water-saturated aquifer as the most capable reservoir, where its upward migration is blocked by a dense cap-rock layer. The major part of the study is focused on two specific processes taking place in the stored reservoir: the phase transfer phenomenon of the supercritical CO₂ which occurs under changeable surrounding conditions and the sequestration-driven deformation of the solid skeleton acting under the pressure of the pumped CO₂. For the numerical simulations within a continuum-mechanical framework, a multiphasic model based on the Theory of Porous Media is introduced. Moreover, the main principles of developing a constitutive equation for the mass production term for the mass balance equation are discussed here. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)