Vectorial Darboux Transformations for the Kadomtsev-Petviashvili Hierarchy

Summary. We consider the vectorial approach to the binary Darboux transformations for the Kadomtsev-Petviashvili hierarchy in its Zakharov-Shabat formulation. We obtain explicit formulae for the Darboux transformed potentials in terms of Grammian type determinants. We also study the n -th Gel'fand-Dickey hierarchy introducing spectral operators and obtaining similar results. We reduce the above-mentioned results to the Kadomtsev-Petviashvili I and II real forms, obtaining corresponding vectorial Darboux transformations. In particular for the Kadomtsev-Petviashvili I hierarchy, we get the line soliton, the lump solution, and the Johnson-Thompson lump, and the corresponding determinant formulae for the nonlinear superposition of several of them. For Kadomtsev-Petviashvili II apart from the line solitons, we get singular rational solutions with its singularity set describing the motion of strings in the plane. We also consider the I and II real forms for the Gel'fand-Dickey hierarchies obtaining the vectorial Darboux transformation in both cases. Received June 4, 1997; final revision received March 6, 1998; accepted March 23, 1998     

On the Derivation of the Modified Kadomtsev-Petviashvili Equation

It is well known that the Kadomtsev-Petviashvili (KP) equation is the two-dimensional analogue of the Korteweg—de Vries (KdV) equation. We reconsider the derivation of the KP equation, modified to include the effects of rotation, in order to determine the nature of the initial conditions. The motivation for this is that if the solutions of the modified KP equation are assumed to be locally confined, then they satisfy a certain constraint, which appears to restrict considerably the class of allowed initial conditions. The outcome of the analysis presented here is that in general it is not permissible to assume that solutions of the modified KP equation are locally confined, and hence the constraint cannot be applied. The reason for this is the radiation of Poincaré waves, which appear behind the main part of the solution described by the modified KP equation.     

Inverse Spectral Transform for the Modified Kadomtsev-Petviashvili Equation

The 2 + 1-modified Kadomtsev-Petviashvili (mKP) equation is studied by the inverse-spectral-transform method. The initial-value problems for the mKP-1 and mKP-11 equations are solved by the nonlocal Riemann-Hilbert and techniques for initial data decaying sufficiently rapidly at infinity. The lump solutions for the mKP-I equation are found explicitly. Wide classes of the exact solutions for the mKP equation—namely, the rational solutions, including the plane lumps for the mKP-I equation; solutions with functional parameters; the plane solitons; and breathers—are constructed by the use of the method based on the nonlocal . The Miura transformation between the mKP and KP equations is discussed.     

扩展形式的修正的Kadomtsev-Petviashvili方程的多重峰波

研究修正的Kadomtsev-Petviashvili(mKP)方程的一个扩展形式.使用由Hereman和Nuseir提出的、一个可以信赖的、Hirota双线性法的简化形式.由该方程(这里称为mKP方程)直接导出多重峰波解.研究还表明,扩展项并不会破坏mKP方程的可积性.     

(2+1)-维耦合的mKP方程的代数几何解

提出一个(2+1)-维耦合的mKP(CMKP)方程,通过其Lax对,实现了该方程的分解.进一步借助代数曲线理论,给出其代数几何解.     

Hierarchy of the Kadomtsev-Petviashvili equations under nonlocal constraints: Many-dimensional generalizations and exact solutions of reduced system

We present a spatially two-dimensional generalization of the hierarchy of Kadomtsev-Petviashvili equations under nonlocal constraints (the so-called 2-dimensionalk-constrained KP-hierarchy, briefly called the 2d k-c-hierarchy). As examples of (2+1)-dimensional nonlinear models belonging to the 2d k-c KP-hierarchy, both generalizations of already known systems and new nonlinear systems are presented. A method for the construction of exact solutions of equations belonging to the 2d k-c KP-hierarchy is proposed. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 51, No. 1, pp. 78–97, January, 1999.     

Modified Moments and Matrix Orthogonal Polynomials

In the scalar case, computation of recurrence coefficients of polynomials orthogonal with respect to a nonnegative measure is done via the modified Chebyshev algorithm. Using the concept of matrix biorthogonality, we extend this algorithm to the vector case.     

秩2修正矩阵的秩

In this paper,the authors discuss the relationship in detail between the rank of M in the modified matrix M=A BC~* and the rank of matrix A.The authors do believe the results are useful tools in the modified matrices.     

Kadomtsev-Petviashvili方程的精确解

齐次平衡法是把非线性偏微分方程转换成带约束条件的线性偏微分方程的一种很好的方法 .本文在齐次平衡法的基础上具体讨论了KP方程的精确解 ,包括孤波解 ,一般的行波解 ,有理函数解和一种新类型的解 .     

修正AHP中判断矩阵的近似加速算法

作为系统工程中典型的定性定量综合集成方法,层次分析法(AHP)在各种复杂系统综合评价和多目标决策中具有广泛的应用价值.为加速修正AHP中判断矩阵的一致性,通过构造修正特征值与步长函数,得到最优修正步长的近似加速算法(AAA).理论分析和实例分析的初步结果说明:近似加速算法结果稳定,精度高,修正速度快,在系统工程中具有推广应用价值.     

Complete integrability of the Kadomtsev-Petviashvili equation

The total hierarchy of the Kadomtsev-Petviashvili (KP) equation is transformed to the system of linear partial differential equations with constant coefficients. The complete integrability of the KP equation is proved by using this linear system. The existence and uniqueness theorem of the Cauchy problem of the KP hierarchy is obtained.     

Multiple periodic-soliton solutions to Kadomtsev-Petviashvili equation

Based on the extended homoclinic test technique, we introduce two new ansätz functions to construct multiple periodic-soliton solutions of Kadomtsev-Petviashvili (KP) equation by the Hirota’s bilinear method. Some entirely new periodic-soliton solutions are obtained. The obtained results show that there exist multiple-periodic solitary waves in the different directions for the KP equation, which differ from complexiton. The employed approach is powerful and can be also applied to solve other nonlinear differential equations.     

矩阵填充的硬阈值修正算法

提出了使用硬阈值进行矩阵填充的修正算法.算法通过对迭代矩阵进行对角修正来完成矩阵填充,并给出了算法的收敛性分析.最后通过数值实验比较了修正算法与硬阈值算法填充的数值结果,显示出了新算法的优越性.     

Pfaffianization of the generalized variable-coefficient Kadomtsev-Petviashvili equation

In this paper, the pfaffianization procedure is applied to the generalized variable-coefficient Kadomtsev-Petviashvili (vcKP) equation which can describe the realistic nonlinear phenomena in the fluid dynamics and plasmas. Using the pfaffianization procedure, the coupled system for the generalized vcKP equation is derived together with the Wronski-type pfaffian solution for this generalized coupled vcKP system under certain coefficient constraint. Furthermore, the Gramm-type pfaffian solution for such a coupled system is presented and verified by virtue of the pfaffian identities.     

Solitary waves of the generalized Kadomtsev-Petviashvili equations

In this paper, we consider the existence of solitary waves of the generalized Kadomtsev-Petviashvili equations by using variational methods.