New exact travelling wave solutions for some famous nonlinear partial differential equations using the improved tanh-function method

The improved tanh-function method is a powerful tool for obtaining exact travelling wave solutions. The method is used for constructing exact travelling wave solutions and new kinds of solutions for the modified dispersive water wave equation, the Abrahams–Tsuneto reaction diffusion system, and for a class of reaction diffusion models. The solutions obtained are different from those reported in the literature.     

New soliton-like solutions and compacton-like periodic wave solutions of parametric type to a nonlinear dispersive equation

In this paper, by using the integral bifurcation method, we study a nonlinear dispersive equation. Some new soliton-like solutions and some compacton-like periodic wave solutions are obtained. Their dynamic characters are investigated and the profiles are given by the mathematical software Maple. From the graphs of some soliton-like solutions, we find that their profiles are transformable.     

一类捕食-食饵系统的新的行波解

利用改进的[(G/G)-]展开法,借助软件的符号计算功能,求出了一类用来描述捕食-食饵群落时空动力性且食饵的平均生长率具有Allee效应的非线性偏微分方程组的新的行波解,这些解的性质合理地反映了生物入侵问题与参数值之间的相互依赖关系。     

Exact travelling wave solutions for a diffusion-convection equation in two and three spatial dimensions

The modified extended tanh-function method were applied to the general class of nonlinear diffusion-convection equations where the concentration-dependent diffusivity, D(u), was taken to be a constant while the concentration-dependent hydraulic conductivity, K(u) were taken to be in a power law. The obtained solutions include rational-type, triangular-type, singular-type, and solitary wave solutions. In fact, the profile of the obtained solitary wave solutions resemble the characteristics of a shock-wave like structure for an arbitrary m (where m>1 is the power of the nonlinear convection term).     

Burgers方程的精确孤立波解的符号计算

借助于符号计算Maple,给出了一种构造非线性波动方程行波解的直接代数方法,该方法的主要特点是充分利用Riccati方程.使用此方法得到Burgers方程的多组精确行波解,其中包括一些新的孤立波解,这种方法也适用于求解其它的非线性波动方程（组）.     

New complex solutions for some special nonlinear partial differential systems

In this present work, we explore new applications of direct algebraic method for some special nonlinear partial differential systems and equations. Then new types of complex travelling wave solutions are obtained to the Davey-Stewartson system, the coupled Higgs system and the perturbed nonlinear Schrodinger’s equation; the balance number of it is not a positive integer.     

分数阶非线性方程精确解的新方法

将分数阶复变换方法和[(G/G)]方法相结合得到了一种辅助方程方法,用来求解分数阶非线性微分方程。利用该方法并借助于软件Mathematica的符号计算功能求解了分数阶Calogero KDV方程,得到了该方程新的精确解。     

Solitary wave solutions for a higher order nonlinear Schrödinger equation

We consider a higher order nonlinear Schrödinger equation with third- and fourth-order dispersions, cubic–quintic nonlinearities, self steepening, and self-frequency shift effects. This model governs the propagation of femtosecond light pulses in optical fibers. In this paper, we investigate general analytic solitary wave solutions and derive explicit bright and dark solitons for the considered model. The derived analytical dark and bright wave solutions are expressed in terms of the model coefficients. These exact solutions are useful to understand the mechanism of the complicated nonlinear physical phenomena which are related to wave propagation in a higher-order nonlinear and dispersive Schrödinger system.     

A numerical comparison of partial solutions in the decomposition method for linear and nonlinear partial differential equations

In this study, the decomposition method for solving the linear heat equation and nonlinear Burgers equation is implemented with appropriate initial conditions. The application of the method demonstrated that the partial solution in the x-direction requires more computational work when compared with the partial solution developed in the t-direction but the numerical solution in the x-direction are performed extremely well in terms of accuracy and efficiency.     

Simplest equation method for some time-fractional partial differential equations with conformable derivative

The conformable fractional derivative was proposed by R. Khalil et al. in 2014, which is natural and obeys the Leibniz rule and chain rule. Based on the properties, a class of time-fractional partial differential equations can be reduced into ODEs using traveling wave transformation. Then the simplest equation method is applied to find exact solutions of some time-fractional partial differential equations. The exact solutions (solitary wave solutions, periodic function solutions, rational function solutions) of time-fractional generalized Burgers equation, time-fractional generalized KdV equation, time-fractional generalized Sharma–Tasso–Olver (FSTO) equation and time-fractional fifth-order KdV equation, $(3+1)$-dimensional time-fractional KdV–Zakharov–Kuznetsov (KdV–ZK) equation are constructed. This method presents a wide applicability to solve some nonlinear time-fractional differential equations with conformable derivative.     

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．     

一类非线性波方程尖波解及其动力学性质的分析

应用动力系统分岔理论和定性理论研究了一类非线性DegasperisProcesi方程的行波解及其动力学性质,并结合可积系统的特点,利用哈密尔顿系统的能量特征,通过Maple软件绘出其相轨图,再根据行波与相轨道间的对应关系,揭示了不同类型的行波解间的转变与参数变化的关系,并且给出了不同行波间相互转换的参数分岔值,从根本上解释了Peakon产生的原因.数值模拟验证了该方法的正确性.最后给出了相应行波解的表达式.     

同伦扰动法求解分数阶非线性扩散方程近似解

将Caputo分数阶微分算子引入到带有初值条件的扩散方程中,建立了时空分数阶方程。利用同伦扰动法并借助于Mathematica软件的符号计算功能,求解了分数阶非线性扩散方程的近似解,整数阶方程的结果作为特例被包含。     

Solving biharmonic equation using the localized method of approximate particular solutions

Some localized numerical methods, such as finite element and finite difference methods (FDMs), have encountered difficulties when solving fourth or higher order differential equations. Localized methods, which use radial basis functions, are considered the generalized FDMs and, thus, inherit the similar difficulties when solving higher order differential equations. In this paper, we deal with the use of the localized method of approximate particular solutions (LMAPS), a recently developed localized radial basis function collocation method, in solving two-dimensional biharmonic equation in a bounded region. The technique is based on decoupling the biharmonic problem into two Poisson equations, and then the LMAPS is applied to each Poisson's problem to compute numerical solutions. Furthermore, the influence of the shape parameter and different radial basis functions on the numerical solution is discussed. The effectiveness of the proposed method is demonstrated by solving three examples in both regular and irregular domains.     

Variable-coefficient auxiliary equation method for exact solutions of non-linear evolution equations

In this paper, a variable-coefficient auxiliary equation method is proposed to seek more general exact solutions of non-linear evolution equations. Being concise and straightforward, this method is applied to the Kawahara equation, Sawada–Kotera equation and (2+1)-dimensional Korteweg–de Vries equations. As a result, many new and more general exact solutions are obtained including Jacobi elliptic, hyperbolic and trigonometric function solutions. It is shown that the proposed method provides a straightforward and effective method for non-linear evolution equations in mathematical physics.     

Quasi-wavelet method for time-dependent fractional partial differential equation

In this decade, many new applications in engineering and science are governed by a series of fractional partial differential equations. In this paper, we propose a novel numerical method for a class of time-dependent fractional partial differential equations. The time variable is discretized by using the second order backward differentiation formula scheme, and the quasi-wavelet method is used for spatial discretization. The stability and convergence properties related to the time discretization are discussed and theoretically proven. Numerical examples are obtained to investigate the accuracy and efficiency of the proposed method. The comparisons of the present numerical results with the exact analytical solutions show that the quasi-wavelet method has distinctive local property and can achieve accurate results.     

Non-polynomial splines method for numerical solutions of the regularized long wave equation

In this paper, we construct a numerical method based on cubic splines in tension for solving regularized long wave equation. The truncation error is analysed and the method shows that by choosing suitably parameters we can obtain various accuracy schemes. Numerical stability of the method has been studied by using a linearized stability analysis. Test problems are dealt with. The numerical simulations can validate and demonstrate the advantages of the method.     

An adaptive method of fundamental solutions for solving the Laplace equation

In this paper, we propose a residual-type adaptive method of fundamental solutions (AMFS) for solving the two-dimensional Laplace equation. An error estimator is defined only on the boundary of the domain. Initial distributions of source points and collocation points are determined by using approaches proposed in Chen et al. (2006). The adding, removing, and stopping strategies are designed so that the required accuracy can be satisfied within finite steps. Numerical experiments reveal that AMFS improves the accuracy of the MFS approximation obtained from uniformly distributed sources and collocation points, which makes the MFS more practical for non-harmonic and non-smooth boundary conditions. Moreover, it is shown that the error estimator becomes equidistributed after an adaptive iteration. A detailed comparison between AMFS and MFS using uniformly distributed points is also presented for each numerical example.     

On the control of the navier- stokes equation with the extended conjugate gradient method

The paper formulates and solves an optimal control problem of the Navier-Stokes equation for an incompressible fluid, employing an Extended Conjugate Gradient algorithm, with computer simulations for the optimal velocity fields.     

A bifurcation method for solving multiple positive solutions to the boundary value problem of the Henon equation on a unit disk

Three algorithms based on the bifurcation theory are proposed to compute the O(2) symmetric positive solutions to the boundary value problem of the Henon equation on the unit disk. Taking l in the Henon equation as a bifurcation parameter, the symmetry-breaking bifurcation point on the branch of the O(2) symmetric positive solutions is found via the extended systems. Finally, other symmetric positive solutions are computed by the branch switching method based on the Lyapunov-Schmidt reduction.