共查询到20条相似文献,搜索用时 62 毫秒
1.
We give a substantially simplified proof of the near-optimal estimate on the Kuramoto-Sivashinsky equation from a previous paper of the third author, at the same time slightly improving the result. That result relied on two ingredients: a regularity estimate for capillary Burgers and an a novel priori estimate for the inhomogeneous inviscid Burgers equation, which works out that in many ways the conservative transport nonlinearity acts as a coercive term. It is the proof of the second ingredient that we substantially simplify by proving a modified Kármán-Howarth-Monin identity for solutions of the inhomogeneous inviscid Burgers equation. We show that this provides a new interpretation of recent results obtained by Golse and Perthame. 相似文献
2.
Martina Chirilus-Bruckner Wolf-Patrick Düll Guido Schneider 《Journal of Mathematical Analysis and Applications》2014
Bethuel et al. and and Chiron and Rousset [3] gave very nice proofs of the fact that slow modulations in time and space of periodic wave trains of the NLS equation can approximately be described via solutions of the KdV equation associated with the wave train. Here we give a much shorter proof of a slightly weaker result avoiding the very detailed and fine analysis of , and . Our error estimates are based on a suitable choice of polar coordinates, a Cauchy–Kowalevskaya-like method, and energy estimates. 相似文献
3.
We obtain exact solutions U(x, y, z, t) of the three-dimensional sine-Gordon equation in a form that Lamb previously proposed
for integrating the two-dimensional sine-Gordon equation. The three-dimensional solutions depend on arbitrary functions F(α)
and ϕ(α,β), whose arguments are some functions α(x, y, z, t) and β(x, y, z, t). The ansatzes must satisfy certain equations. These
are an algebraic system of equations in the case of one ansatz. In the case of two ansatzes, the system of algebraic equations
is supplemented by first-order ordinary differential equations. The resulting solutions U(x, y, z, t) have an important property,
namely, the superposition principle holds for the function tan(U/4). The suggested approach can be used to solve the generalized sine-Gordon equation, which, in contrast to the classical equation,
additionally involves first-order partial derivatives with respect to the variables x, y, z, and t, and also to integrate
the sinh-Gordon equation. This approach admits a natural generalization to the case of integration of the abovementioned types
of equations in a space with any number of dimensions.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 158, No. 3, pp. 370–377, March, 2009. 相似文献
4.
5.
Ricardo Restrepo López 《Journal of Mathematical Analysis and Applications》2009,351(2):556-566
We investigate the existence of reflection formulas supported on a finite set. It is found that for solutions of the Laplace and Helmholtz equation there are no finitely supported reflection principles unless the support is a single point. This confirms that in order to construct a reflection formula that is not ‘point to point’, it is necessary to consider a continuous support. For solutions of the wave equation ∂2u/∂x∂y=0, there exist finitely supported reflection principles that can be constructed explicitly. For solutions of the telegraph equation ∂2u/∂x∂y+λ2u=0, we show that if a reflection principle is supported on less than five points then it is a point to point reflection principle. 相似文献
6.
Abdul-Majid Wazwaz 《Applied mathematics and computation》2009,212(1):120-134
In this work, the variational iteration method (VIM) is used for analytic treatment of the linear and nonlinear ordinary differential equations, homogeneous or inhomogeneous. The method is capable of reducing the size of calculations and handles both linear and nonlinear equations, homogeneous or inhomogeneous, in a direct manner. However, for concrete problems, a huge number of iterations are needed for a reasonable level of accuracy. 相似文献
7.
We obtain new gauge-invariant forms of two-dimensional integrable systems of nonlinear equations: the Sawada-Kotera and Kaup-Kuperschmidt
system, the generalized system of dispersive long waves, and the Nizhnik-Veselov-Novikov system. We show how these forms imply
both new and well-known twodimensional integrable nonlinear equations: the Sawada-Kotera equation, Kaup-Kuperschmidt equation,
dispersive long-wave system, Nizhnik-Veselov-Novikov equation, and modified Nizhnik-Veselov-Novikov equation. We consider
Miura-type transformations between nonlinear equations in different gauges.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 160, No. 1, pp. 35–48, July, 2009. 相似文献
8.
YoonMee Ham & Sang sup Yum 《偏微分方程(英文版)》1995,8(3):211-218
We consider a free boundary problem in a parabolic partial differential equation with multiple interfacial curves which is reduced to a reaction-diffusion equation. The forcing term of this problem is not continuously differentiable and thus we use Green's function to make a regular one. The existence, uniqueness and dependence. on initial conditions will be shown in this paper. 相似文献
9.
10.
Wael W. MOHAMMED 《数学年刊B辑(英文版)》2018,39(1):145-162
The main goal of this paper is to approximate the Kuramoto-Shivashinsky (K-S for short) equation on an unbounded domain near a change of bifurcation, where a band of dominant pattern is changing stability. This leads to a slow modulation of the dominant pattern. Here we consider PDEs with quadratic nonlinearities and derive rigorously the modulation equation, which is called the Ginzburg-Landau (G-L for short) equation, for the amplitudes of the dominating modes. 相似文献
11.
Abstract In [1], Ding et al. studied the nonhomogeneous Burgers equation ut uux = μuxx 4x.(1.1) This paper will prove that when μ → 0 the solution of (1.1) will approach the generalized solution of ut uux = 4x.(1.2) The authors notice that the equation (1.2) is beyond the scope of investigations by Oleinik O. in [2]. The solutions here are unbounded in general. The paper also studies the δ-wave phenomenon when (1.2) is jointed with some other equation. 相似文献
12.
Taeko Yamazaki 《Mathematical Methods in the Applied Sciences》2004,27(16):1893-1916
We consider the unique global solvability of initial (boundary) value problem for the Kirchhoff equations in exterior domains or in the whole Euclidean space for dimension larger than three. The following sufficient condition is known: initial data is sufficiently small in some weighted Sobolev spaces for the whole space case; the generalized Fourier transform of the initial data is sufficiently small in some weighted Sobolev spaces for the exterior domain case. The purpose of this paper is to give sufficient conditions on the usual Sobolev norm of the initial data, by showing that the global solvability for this equation follows from a time decay estimate of the solution of the linear wave equation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
13.
应用改进的简单方程法求得Cahn-Allen方程和Jimbo-Miwa方程的精确解,这些解包括双曲函数解、三角函数解.当对双曲函数解中的参数取特殊值时,可以得到了孤立波解.当对三角函数解中的参数取特殊值时,可以得到对应的周期波函数解.实践证明,简单方程法对于研究非线性数学物理方程具有非常广泛的应用意义. 相似文献
14.
本文提出方程f~(n)(x)=Af(n-k)((ax+b)/(cx-a)),证明它是可积的.所得结论是文献[1]中结论的推广. 相似文献
15.
《代数通讯》2013,41(3):1187-1202
Abstract Let M be a k-vector space and R ∈ Hom(M ?p , M ?q ), we present a general version of the FRT-construction, we provide a method for examining whether an FRT-bialgebra A(R) has a pre-braided structure and whether M can be regarded as an A(R)-dimodule. We show that the FRT-relation plays a fundamental role in determining the algebra structure on the FRT-bialgebra and the compatibility condition of relevant dimodule. As an example, we give a Hopf algebra approach for solving both homogeneous and non-homogeneous nonlinear (algebraic) equations. 相似文献
16.
Stevo Stevi 《Mathematical Methods in the Applied Sciences》2019,42(18):6315-6338
By using generalized invariants, we describe a method for solving a class of higher‐order nonautonomous difference equations. Solvability of the equations of order two, three, and four are studied in detail. Our results explain and extend some problems in the literature. As far as we know, the case when the order is four is considered for the first time in this paper. For the equations of second order, we also give an explanation how they can be obtained in a natural way. 相似文献
17.
Qi Yu Sun 《数学学报(英文版)》2001,17(1):1-14
Let A be a matrix with the absolute values of all eigenvalues strictly larger than one, and let Z
0 be a subset of Z such than n∈Z
0 implies n + 1 ∈Z
0. Denote the space of all compactly supported distributions by D′, and the usual convolution between two compactly supported distributions f and g by f*g. For any bounded sequence G
n
and H
n
, n∈Z
0, in D′, define the corresponding nonstationary nonhomogeneous refinement equation
Φ
n
=H
n
*Φ
n+1
(A·)+G
n
for all n∈Z
0
where Φ
n
, n∈Z
0, is in a bounded set of D′. The nonstationary nonhomogeneous refinement equation (*) arises in the construction of wavelets on bounded domain, multiwavelets,
and of biorthogonal wavelets on nonuniform meshes. In this paper, we study the existence problem of compactly supported distributional
solutions Φ
n
, n∈Z
0, of the equation (*). In fact, we reduce the existence problem to finding a bounded solution of the linear equations
for all n∈Z
0
where the matrices S
n
and the vectors , n∈Z
0, can be constructed explicitly from H
n
and G
n
respectively. The results above are still new even for stationary nonhomogeneous refinement equations.
Received December 30, 1999, Accepted June 15, 2000 相似文献
18.
Spectral discretization of Darcy equations coupled with Stokes equations by vorticity–velocity–pressure formulations 下载免费PDF全文
Yassine Mabrouki Saloua Mani Aouadi Jamil Satouri 《Numerical Methods for Partial Differential Equations》2017,33(5):1628-1651
We propose to make the numerical analysis of a model coupling the Darcy equations in a porous medium with the Stokes equations in the cracks. The coupling is provided by a pressure continuity on the interface. We describe a discretization by spectral element methods. We derive a priori optimal error estimates and we present some numerical experiments which confirm the results of the analysis.© 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 1628–1651, 2017 相似文献
19.
In this paper, we extend the work of Daripa et al. [14–16,7] to a larger class of elliptic problems in a variety of domains. In particular, analysis-based fast algorithms to solve inhomogeneous elliptic equations of three different types in three different two-dimensional domains are derived. Dirichlet, Neumann and mixed boundary value problems are treated in all these cases. Three different domains considered are: (i) interior of a circle, (ii) exterior of a circle, and (iii) circular annulus. Three different types of elliptic problems considered are: (i) Poisson equation, (ii) Helmholtz equation (oscillatory case), and (iii) Helmholtz equation (monotone case). These algorithms are derived from an exact formula for the solution of a large class of elliptic equations (where the coefficients of the equation do not depend on the polar angle when written in polar coordinates) based on Fourier series expansion and a one-dimensional ordinary differential equation. The performance of these algorithms is illustrated for several of these problems. Numerical results are presented. 相似文献
20.
Guang Yuan Zhang 《Proceedings of the American Mathematical Society》2007,135(9):2887-2891
We first generalize a classical iteration formula for one variable holomorphic mappings to a formula for higher dimensional holomorphic mappings. Then, as an application, we give a short and intuitive proof of a classical theorem, due to H. Poincaré, for the condition under which a singularity of a holomorphic vector field is an isochronous center.