Burgers方程的精确解

引入一个变换,将二阶非线性偏微分方程—Burgers方程降阶为一阶的非线性方程,再直接求解该方程,得出了Burgers方程精确解的新形式,并与已有结果完全吻合.这种方法也适合于求解其他非线性偏微分方程.     

(2+1)维AKNS方程的可积性研究

运用Bell多项式定理研究了一个(2+1)维AKNS方程的可积性,得到双线性方程、B?cklund变换以及运用B?cklund变换求得其孤子解,最后运用Bell多项式得出Lax对.     

(2+1)维Bogoyavlenskii-Schiff方程的精确解

应用简单方程法求得(2+1)维Bogoyavlenskii-Schiff方程的精确解,这种方法对于研究非线性发展方程具有非常广泛的应用意义.     

(3+1)维修正KdV-Zakharov-Kuznetsov方程的行波解

结合动力系统分支理论,对一个非线性(3+1)维修正KdV-Zakharov-Kuznetsov方程进行理论上的研究.首先,根据不同参数值和三次方程判别式分别定性分析了平衡点的类型和相应轨线情况.其次,利用Ja-cobi椭圆函数,从形式上给出了若干有界行波解和同宿轨的公式,这一结论扩展了已有文献的工作.最后,利用Hami...     

用微分求积法分析轴向加速粘弹性梁的非线性动力学行为

用微分求积数值方法求解了轴向加速粘弹性梁的横向振动控制方程,其方程是一复杂的非线性偏微分方程.并在数值结果的基础上利用分叉图分析了轴向定常加速度以及轴向加速度变化幅值对轴向加速粘弹性梁的非线性动力学行为的影响.     

(2+1)维破裂孤立子方程组的精确解

本文针对(2+1)维破裂孤立子方程组,采用指数函数法,借助于数学工具Maple软件得到了该方程的两个新的孤立波解。     

求一类非线性偏微分方程精确解的简化试探函数法

利用试探函数法,将一个难于求解的非线性偏微分方程化为一个易于求解的代数方程,然后用待定系数法确定相应的常数,简洁地求得了一类非线性偏微分方程的精确解．将此方法应用到Burgers方程、KdV方程和KdV—Burgers方程,所得结果与已有结果完全吻合．本方法可望进一步推广用于求解其它非线性偏微分方程．     

浅析孤子求解的微扰理论

实际问题中孤子方程通常并不以标准形式出现,而是含有阻尼项、增益项、三阶色散项等一些较小的附加项,将这些附加项当作微扰来处理进而求解各种非线性偏微分方程,发展出了多种孤子微扰理论。本文结合KdV方程详细介绍了两种应用范围最广的基于逆散射变换(IST)的微扰理论和基于线性编微分方程理论的直接微扰理论。     

计算q~(l_1)×q~(l_2)二维DCT的快速算法

离散余弦变换 (DCT)广泛应用于信号处理的许多领域 ,多维 DCT(MD- DCT)是图像处理和视频信号处理的重要工具 .通常 ,多维 DCT采用行列法用一维算法实现 ,实现效率较低 .近年来虽然出现了一些多维 DCT直接实现算法 ,但大多要求变换为 2 n× 2 n,限制了适用范围 .该文研究较一般的二维 DCT快速算法 ,将 ql1 × ql2 (q为奇素数 ;l1 ,l2 分别为两个不同的整数 )二维 DCT转化为多项式变换和一维简化余弦变换 ,通过特别设计的快速多项式变换算法和 1D- RDCT递归分解算法 ,提出了一种计算复杂性较低且具有规则运算结构的 ql1 × ql2 二维 DCT算法 .本算法的设计方法可以方便地推广到多维 (>2 )的情况 .     

单向耦合Lorenz-R(o)ssler系统的多参数分岔

深入研究了单向耦合Lorenz-R(o)ssler系统的动力学行为,首先定性地分析了该系统,找出了该系统所有平衡点及平衡点存在和稳定的条件.再对该系统的分岔行为做了理论分析,得到该系统发生fold和Hopf 分岔的条件.最后利用分岔软件对前面的理论进行验证,而且针对三个单向耦合参数的不同取值情况,从数值的角度研究了该系统的多参数分岔,结果表明不同的耦合强度对于系统的动力学行为有较大的影响.     

Exact solutions of a KdV equation hierarchy with variable coefficients

In this paper, a nonisospectral and variable-coefficient KdV equation hierarchy with self-consistent sources is derived from the related linear spectral problem. Exact solutions of the KdV equation hierarchy are obtained through the inverse scattering transformation (IST). It is shown that the IST is an effective mathematical tool for solving the whole hierarchy of nonisospectral nonlinear partial differential equations with self-consistent sources.     

Wick类型的随机广义Kdv方程的精确解

在Kondratiev分布空间(S)-1中通过埃尔米特变换和Painleve′分析导出了Wick-类型的随机广义Kdv方程的Backlund变换,并且把Wick-类型的随机广义Kdv方程变成广义系数Kdv-方程,再利用Backlund变换求出广义系数Kdv方程的精确解,最后通过埃尔米特逆变换求出随机广义Kdv方程在系数取不同白色噪音泛函条件下的精确解.     

New exact solutions of the (n+1)-dimensional sine-Gordon equation using double elliptic equation method

In this paper, the (n+1)-dimensional sine-Gordon equation is studied using double elliptic equation method. With the aid of Maple, more exact solutions expressed by Jacobi elliptic functions are obtained. When the modulus m of Jacobi elliptic function is driven to the limit 1 and 0, some exact solutions expressed by hyperbolic function solutions and trigonometric functions can also be obtained, respectively.     

Rational solutions and their interaction solutions of the (2+1)-dimensional modified dispersive water wave equation

A bilinear form for the modified dispersive water wave (mDWW) equation is presented by the truncated Painlevé series, which does not lead to lump solutions. In order to get lump solutions, a pair of quartic–linear forms for the mDWW equation is constructed by selecting a suitable seed solution of the mDWW equation in the truncated Painlevé series. Rational solutions are then computed by searching for positive quadratic function solutions. A regular nonsingular rational solution can describe a lump in this model. By combining quadratic functions with exponential functions, some novel interaction solutions are founded, including interaction solutions between a lump and a one-kink soliton, a bi-lump and a one-stripe soliton, and a bi-lump and a two-stripe soliton. Concrete lumps and their interaction solutions are illustrated by 3d-plots and contour plots.     

L1 adaptive control for general partial differential equation (PDE) systems

This paper addresses the L₁ adaptive control problem for general Partial Differential Equation (PDE) systems. Since direct computation and analysis on PDE systems are difficult and time-consuming, it is preferred to transform the PDE systems into Ordinary Differential Equation (ODE) systems. In this paper, a polynomial interpolation approximation method is utilized to formulate the infinite dimensional PDE as a high-order ODE first. To further reduce its dimension, an eigenvalue-based technique is employed to derive a system of low-order ODEs, which is incorporated with unmodeled dynamics described as bounded-input, bounded-output (BIBO) stable. To establish the equivalence with original PDE, the reduced-order ODE system is augmented with nonlinear time-varying uncertainties. On the basis of the reduced-order ODE system, a dynamic state predictor consisting of a linear system plus adaptive estimated parameters is developed. An adaptive law will update uncertainty estimates such that the estimation error between predicted state and real state is driven to zero at each time-step. And a control law is designed for uncertainty handling and good tracking delivery. Simulation results demonstrate the effectiveness of the proposed modeling and control framework.     

The solution of a nonclassic problem for one-dimensional hyperbolic equation using the decomposition procedure

In this article, we propose a new approach for solving an initial–boundary value problem with a non-classic condition for the one-dimensional wave equation. Our approach depends mainly on Adomian's technique. We will deal here with new type of nonlocal boundary value problems that are the solution of hyperbolic partial differential equations with a non-standard boundary specification. The decomposition method of G. Adomian can be an effective scheme to obtain the analytical and approximate solutions. This new approach provides immediate and visible symbolic terms of analytic solution as well as numerical approximate solution to both linear and nonlinear problems without linearization. The Adomian's method establishes symbolic and approximate solutions by using the decomposition procedure. This technique is useful for obtaining both analytical and numerical approximations of linear and nonlinear differential equations and it is also quite straightforward to write computer code. In comparison to traditional procedures, the series-based technique of the Adomian decomposition technique is shown to evaluate solutions accurately and efficiently. The method is very reliable and effective that provides the solution in terms of rapid convergent series. Several examples are tested to support our study.     

Lump-type solutions and lump solutions for the (2+1)-dimensional generalized Bogoyavlensky–Konopelchenko equation

In this paper, a (2+1)-dimensional generalized Bogoyavlensky–Konopelchenko equation is investigated. Lump-type solutions and lump solutions are obtained with aid of symbolic computation via Hirota bilinear method and the ansatz technique. By taking the function $f$ in the Hirota bilinear form of the (2+1)-dimensional generalized Bogoyavlensky–Konopelchenko equation as the general quadratic polynomial function, a kind of lump-type solution which contains eleven parameters with six arbitrary independent parameters and two non-zero conditions is obtained. Lump solutions are found from the lump-type solutions via taking a special set of parameters, and the motion track of the lump is also described both theoretically and graphically.     

Distributed feedback design for systems governed by the wave equation

This article deals with the geometric control of a one-dimensional non-autonomous linear wave equation. The idea consists in reducing the wave equation to a set of first-order linear hyperbolic equations. Then, based on geometric control concepts, a distributed control law that enforces the exponential stability and output tracking in the closed-loop system is designed. The presented control approach is applied to obtain a distributed control law that brings a stretched uniform string, modelled by a wave equation with Dirichlet boundary conditions, to rest in infinite time by considering the displacement of the middle point of the string as the controlled output. The controller performances have been evaluated in simulation by considering both tracking and disturbance rejection problems. The robustness of the controller has also been studied when the string tension is subjected to sudden variations.     

一类捕食-食饵模型平衡解的整体分歧

利用分歧理论和谱分析的方法研究了一类捕食-食饵模型平衡解的整体分歧,得到了在以[d]为分歧参数的条件下,系统在半平凡解[(θ,0)]附近出现分歧现象,得到了该模型正解存在的充分条件。