一种新的求解双曲型守恒律的三阶中心差分格式

本文提出了一种求解双曲型守恒律新的三阶中心差分格式，主要是引入了一种推广的三阶重构，并证明了这种重构在网格边界无振荡．所提的格式保持了中心差分格式简单的优点，不需用Riemann解算器，避免了进行特征解耦．数值试验结果表明本文格式是高精度、高分辨率的。     

双曲守恒律的几种新数值方法的比较研究

本文就一维线性双曲方程的光滑和间断两种初值问题的求解,对双曲守恒律的三种新数值方法,即,WENO方法、间断Galerkin方法和全局复合方法,进行了数值比较实验,在精度、计算速度等方面的比较上,对这三个方法有了一个较详细的了解,得到了一些有用的结论。     

Conservation Laws for Single-Server Fluid Networks

We consider single-server fluid networks with feedback and arbitrary input processes. The server has to be scheduled in order to minimize a linear holding cost. This model is the fluid analogue of the so-called Klimov problem. Using the achievable-region approach, we show that the Gittins index rule is optimal in a strong sense: it minimizes the linear holding cost for arbitrary input processes and for all time points t0.     

一个解KdV方程的满足两个守恒律的差分格式

Korteweg-de Vries(KdV)方程是人们在研究一些物理问题时得到的非线性波 动方程,其解满足无穷多个守恒律．本文为该方程设计了一种差分格式,其采用的是有限 体积法．但与传统的有限体积法不同的是,它的数值解同时满足两个相关的守恒律．这样 可以更好地保持解的物理上的守恒性质．数值例子表明这一算法是有效的．     

A New Class of Uniformly Second Order Accurate Difference Schemes for 2D Scalar Conservation Laws

In this paper, concerned with the Cauchy problem for 2D nonlinear hyperbolic conservation laws, we construct a class of uniformly second order accurate finite difference schemes, which are based on the E-schemes. By applying the convergence theorem of Coquel-Le Floch [1], the family of approximate solutions defined by the scheme is proven to converge to the unique entropy weak $L^{\infty}$-solution. Furthermore, some numerical experiments on the Cauchy problem for the advection equation and the Riemann problem for the 2D Burgers equation are given and the relatively satisfied result is obtained.     

Two-Dimensional Riemann Problem for Scalar Conservation Laws

Using the generalized characteristic analysis method, we study the two-dimensional Riemann problem for scalar conservation laws, which is nonconvex along the y direction, and interactions of its elementary waves, give the classification of initial discontinuities and construct all Riemann solutions, which Riemann data are two or three pieces of constants. All kinds of Guckenheimer structure appear in the solutions and the necessary and sufficient condition of appearance of it is given.     

Conservation Laws for CKdV and BSSK Systems

In current paper, the coupled KdV (CKdV) system and Bosonized Supersymmetric Sawada-Kotera (BSSK) system are considered. Some linearly independent conservation laws for the two systems are derived via the first homotopy approach and symbolic computation.     

Characteristics of Conservation Laws for Difference Equations

Each conservation law of a given partial differential equation is determined (up to equivalence) by a function known as the characteristic. This function is used to find conservation laws, to prove equivalence between conservation laws, and to prove the converse of Noether’s Theorem. Transferring these results to difference equations is nontrivial, largely because difference operators are not derivations and do not obey the chain rule for derivatives. We show how these problems may be resolved and illustrate various uses of the characteristic. In particular, we establish the converse of Noether’s Theorem for difference equations, we show (without taking a continuum limit) that the conservation laws in the infinite family generated by Rasin and Schiff are distinct, and we obtain all five-point conservation laws for the potential Lotka–Volterra equation.     

一类拟线性双曲守恒律的张弛现象

讨论了一类拟线性双曲守恒律的张弛现象，证明了张弛在保持“小解”光滑性意义下具有耗散效应．     

A Note on the Jump Conditions for Systems of Conservation Laws

In [ 1 ], the authors have demonstrated the effect on the Rankine–Hugoniot conditions for a system of conservation laws driven by a singular forcing function and have applied their results to a problem in water waves. We analyze here a similar problem in several space dimensions, in which the singularity in the forcing term involves a simple layer potential supported along the singularity locus. A classical theorem in electrostatics appears as a special case.     

一个新的可积广义超孤子族及其自相容源、守恒律

该文利用Lie超代数B(0,1)导出一个新的广义超孤子族,借助超迹恒等式将广义超孤子族写成超双-Hamilton结构形式.其次,建立了广义超孤子族的自相容源.最后,给出了广义超孤子族的无穷守恒律.     

Mixing Closures for Conservation Laws in Stratified Flows

A closure for shocks involving the mixing of the fluids in two-layer stratified flows is proposed. The closure maximizes the rate of mixing, treating the dynamical hydraulic equations and entropy conditions as constraints. This closure may also be viewed as yielding an upper bound on the mixing rate by internal shocks. It is shown that the maximal mixing rate is accomplished by a shock moving at the fastest allowable speed against the upstream flow. Depending on whether the active constraint limiting this speed is the Lax entropy condition or the positive dissipation of energy, we distinguish precisely between internal hydraulic jumps and bores. Maximizing entrainment is shown to be equivalent to maximizing a suitable entropy associated to mixing. By using the latter, one can describe the flow globally by an optimization procedure, without treating the shocks separately. A general mathematical framework is formulated that can be applied whenever an insufficient number of conservation laws is supplemented by a maximization principle.     

Essential Conservation Laws for Equations with Infinite Symmetries

We consider partial differential equations of variational problems with infinite symmetry groups. We study local conservation laws associated with arbitrary functions of one variable in the group generators. We show that only symmetries with arbitrary functions of dependent variables lead to an infinite number of conservation laws. We also calculate local conservation laws for the potential Zabolotskaya-Khokhlov equation for one of its infinite subgroups.__________Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 1, pp. 190–198, July, 2005.     

Construction of Autonomous Conservation Laws

In mathematical physics conservation laws are of very special importance. For variational problems they can be determined by means of Noether’s theorem, whereas for general differential equations a direct method by Anco and Bluman (Eur. J. Appl. Math., 13:545–566, 2002, Eur. J. Appl. Math., 13:567–585, 2002) is available. In this paper, a theorem mapping nonautonomous and nonhomogeneous quasilinear first order partial differential equations to autonomous and homogeneous quasilinear first order partial differential equations is used to obtain from a system of first order balance laws an autonomous system of conservation laws.     

Geometrical Conservation Laws for Maxwell and Elasticity Systems

The Maxwell system in inhomogeneous medium as well as the elasticity system are considered. We give a sharp form to the conservation laws of geometrical optics in the terms of the distribution theory. We show that the conservation laws keep to hold through any singular point of the wave front.     

A Note on Conservation Laws of Symplectic Difference Schemes for Hamiltonian Systems

In this paper we consider the necessary conditions of conservation laws of symplectic difference schemes for Hamiltonian systems and give an example which shows that there does not exist any centered symplectic difference scheme which preserves all Hamiltonian energy.     

带有微结构的连续统中新的能量守恒定律和C-D不等式

对带有微结构的连续统中现有的基本定律、均衡方程和Clausius-Duhem不等式进行了系统的再研究,发现所有的能量均衡方程和相关的C-D不等式都是不完整的.本文对现有的结果进行了评注,并提出新的能量均衡方程和相关的C-D不等式.     

不带微结构的连续统中新的能量守恒定律和C-D不等式

对连续统力学中的基本定律和均衡方程以及C-D不等式进行了认真的再研究.指出了现有的动量矩均衡定律和能量守恒定律以及Clausius-Duhem不等式的不完整性,并且提出了不带微结构的局部和非局部非对称连续统中新的而且更为普遍的能量守恒定律和相应的能量均衡方程以及C-D不等式.     

用WENO方法求解双曲型守恒律方程组的初(边)值问题

本文用WENO算法解决双曲型守恒律方程组初（边值）问题．给出一种满足熵条件、Sδ熵条件和边界熵条件的WENO算法．通过这个算法就能得到守恒律方程组的数值解，数值解和理论解是非常吻合的．