Broer-Kaup系统的达布变换和新的精确解

利用Broer-Kaup系统Lax对的两个基本解，构造了该系统一个新的达布变换，并利用该变换求出了Broer-Kaup系统一组新的双向孤子解. 关键词： Lax对 达布变换 孤子解     

Multi-soliton solutions of a two-component Camassa–Holm system:Darboux transformation approach

We propose and develop another approach to constructing multi-soliton solutions of an integrable two-component Camassa–Holm(CH2)system.With the help of a reciprocal transformation and a gauge transformation,we relate the CH2 system to a negative flow of the Broer–Kaup or twoboson hierarchy.The solutions of this negative flow are given in terms of Wronskians via Darboux transformation.Then the multi-soliton solutions of the CH2 system are recovered in parametric form by inverting the reciprocal transformation and the gauge transformation.     

Painleve Analysis and Darboux Transformation for a Variable-Coefficient Boussinesq System in Fluid Dynamics with Symbolic Computation

The new soliton solutions for the variable-coefficient Boussinesq system, whose applications are seen in fluid dynamics, are studied in this paper with symbolic computation. First, the Painleve analysis is used to investigate its integrability properties. For the identified case we give, the Lax pair of the system is found, and then the Darboux transformation is constructed. At last, some new soliton solutions are presented via the Darboux method. Those solutions might be of some value in fluid dynamics.     

Darboux transformation and novel solutions for the long wave-short wave model

Firstly, we establish the relation between the loop group method and gauge transformation method for 3×3 spectral problem. Some novel solutions of long wave-short wave model are obtained by Darboux transformation method. Besides, we give the analysis and classification of solution in detail.     

The Nth-order Darboux transformation,vector dark solitons and breathers for the coupled defocusing Hirota system in a birefringent nonlinear fiber

Under investigation in this paper is the coupled defocusing Hirota system, which describes the propagation of ultra-short pulses in a birefringent nonlinear fiber. With respect to the amplitudes of the pulse envelopes, we construct the Nth-order Darboux transformation, which is different from those in the existing literatures, where N is a positive integer. The first- and second-order solutions are obtained via the Darboux transformation. Pulse envelopes including the gray-gray/antidark-gray/dark-bright solitons, vector Akhmediev breathers, temporal cavity solitons and (time, space)-periodic breathers are acquired. As the relative width of the spectrum that arises due to the quasi monochromocity decreases, we find that: the velocity and width of the dark-bright solitons increase; the width of the temporal cavity soliton decreases; the temporal period of the vector (time, space)-periodic breather becomes longer while its spacial period becomes shorter. Relative width of the spectrum that arises due to the quasi monochromocity does not affect the amplitudes of the pulse envelopes obtained. Elastic interactions between the breathers and solitons, and inelastic interactions between the two gray-gray solitons are obtained.     

Darboux Transformation and Explicit Solutions for Drinfel＇d-Sokolov-Wilson Equation

A generalized Drinfel＇d Sokolov-Wilson （DSW） equation and its Lax pair are proposed. A Daorboux transformation for the generalized DSW equation is constructed with the help of the gauge transformation between spectral problems, from which a Darboux transformation for the DSW equation is obtained through a reduction technique. As an application of the Darboux transformations, we give some explicit solutions of the generalized DSW equation and DEW equation such as rational solutions, soliton solutions, periodic solutions.     

Darboux transformation for two‐level system

We develop the Darboux procedure for the case of the two‐level system. In particular, it is demonstrated that one can construct the Darboux intertwining operator that does not violate the specific structure of the equations of the two‐level system, transforming only one real potential into another real potential. We apply the obtained Darboux transformation to known exact solutions of the two‐level system. Thus, we find three classes of new solutions for the two‐level system and the corresponding new potentials that allow such solutions.     

Darboux transformation and exact multisolitons for a matrix coupled dispersionless system

We present a matrix coupled dispersionless(CD) system. A Lax pair for the matrix CD system is proposed and Darboux transformation is constructed on the solutions of the matrix CD system and the associated Lax pair. We express an N soliton formula for the solutions of the matrix CD system in terms of quasideterminants. By using properties of the quasideterminants, we obtain some exact solutions, including bright and dark-type solitons, rogue wave and breather solutions of the matrix CD system. Furthermore, it has been shown that the solutions of the matrix CD system are expressed in terms of solutions to the usual CD system, sine-Gordon equation and Maxwell-Bloch system.     

Darboux transformation and explicit solutions for the derivative versions of Toda equation

The derivative versions of Toda equation are produced from the Lax triad composed of the Kaup-Newell and negative Kaup-Newell spectral problems and a new discrete eigenvalue problem. With the help of decomposition and the Darboux transformation, explicit solutions of these derivative Toda equations are obtained.     

(2+1)维Boussinesq方程的Backlund变换与精确解

借助于符号计算软件Maple，对方程的种子解作适当的未知函数替换，然后利用Backlund 变 换通过具体的符号演算获得了(2+1)维Boussinesq方程的一系列精确解.这些解包括类孤子解 和有理解,其中有的解中含有任意函数，当任意函数取特殊函数时，这些解具有丰富的结构 ，有些结构可能对物理现象的研究是有意义的. 关键词： (2+1)维Boussinesq方程 Backlund 变换 精确解 类孤子解     

Integrability,multi-soliton and rational solutions,and dynamical analysis for a relativistic Toda lattice system with one perturbation parameter

Under investigation in this paper is a relativistic Toda lattice system with one perturbation parameter α abbreviated as RTL_(α) system by Suris, which may describe the motions of particles in lattices interacting through an exponential interaction force. First of all, an integrable lattice hierarchy associated with an RTL_(α) system is constructed, from which some relevant integrable properties such as Hamiltonian structures, Liouville integrability and conservation laws are investigated. Secondly, the discrete generalized(m, 2 N-m)-fold Darboux transformation is constructed to derive multi-soliton solutions, higher-order rational and semirational solutions, and their mixed solutions of an RTL_(α) system. The soliton elastic interactions and details of rational solutions are analyzed via the graphics and asymptotic analysis. Finally, soliton dynamical evolutions are investigated via numerical simulations,showing that a small noise has very little effect on the soliton propagation. These results may provide new insight into nonlinear lattice dynamics described by RTL_(α) system.     

Darboux Transformation and Explicit Solutions for Discretized Modified Korteweg-de Vries Lattice Equation

The modified Korteweg-de Vries （mKdV） typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.     

Darboux transformation and soliton solutions of the semi-discrete massive Thirring model

A one-fold Darboux transformation between solutions of the semi-discrete massive Thirring model is derived using the Lax pair and the dressing method. This transformation is used to find the exact expressions for soliton solutions on zero and nonzero backgrounds. It is shown that the discrete solitons have the same properties as their continuous counterparts.     

Darboux transformation and elementary exact solutions of the Schrödinger equation

Darboux transformation is applied to three classical potentials, namely the harmonic oscillator, effective Coulomb and Morse potentials to generate exactly solvable potentials of elementary form. For every potential, the isospectral families of potentials are constructed. For almost all potentials, a set of normalized discrete spectrum wave functions is given.     

Searching for new conditions for fermion N-representability

New elements of the dual cone of the set of fermion N-representable 2-density operators are proposed. So far, the explicit form of the corresponding necessary conditions for N-representability is obtained for N = 3. In this case the new condition is stronger than the known B- and C-conditions for 3-representability. The results provide evidence that in the spectral decomposition of the N-representable 2-density operator there exists an intrinsic relation between the eigenvalue and the corresponding eigenfunction.     

A Unified and Explicit Construction of N-Soliton Solutions for the Nonlinear Schrfdinger Equation

An explicit N-fold Darboux transformation with multiparameters for nonlinear Schrodinger equation is constructed with the help of its Lax pairs and a reduction technique. According to this Darboux transformation, the solutions of the nonlinear Schrfdinger equation are reduced to solving a linear algebraic system, from which a unified and explicit formulation of N-soliton solutions with multiparameters for the nonlinear Schrfdinger equation is given.``     

An improved method for Darboux transformation for the coupled inhomogeneous nonlinear Schrödinger system from plasma physics and nonlinear optics

The coupled inhomogeneous nonlinear Schrödinger-type system which can be used to control soliton propagation and interaction in certain plasmas and optical fibers is investigated. An improved method for Darboux transformation (DT) is presented in more general forms by constructing an improved Γ$\Gamma$-Riccati-type Bäcklund transformation (Γ$\Gamma$-R BT). With the N$N$th-iterated Γ$\Gamma$-R BT or the N$N$th-iterated DT, which is a compact representation for the N$N$-soliton-like solutions and can generate a series of analytic solutions from a pair of the seed solutions through algebraic manipulations, the analytic one-/two-soliton-like solutions are provided. With the choice of parameters for the soliton solutions, the dynamical characteristics of the influences of the inhomogeneous parameters on the propagation of the soliton pulses are discussed graphically.     

N-Fold Darboux Transformation and Bidirectional Solitons for Whitham-Broer-Kaup Model in Shallow Water

Under investigation in this paper is the Whitham Broer-Kaup （WBK） system, which describes the dispersive long wave in shallow water. Through a variable transformation, the WBK system is casted into a general Broer-Kaup system whose Lax pair can be derived by the Ablowitz-Kaup Newell-Segur technology. With symbolic computation, based on the aforementioned Lax pair, the N-fold Darboux transformation is constructed with a gauge transformation and the multi-soliton solutions are obtained. Finally, the elastic interactions of the two-soliton solutions （including the head-on and overtaking collisions） for the WBK system are graphically studied. Those multi-soliton collisions can be used to illustrate the bidirectional propagation of the waves in shallow water.