Vanishing pressure limits of Riemann solutions to the isentropic relativistic Euler system for Chaplygin gas

The Riemann solutions to the isentropic relativistic Euler system for Chaplygin gas with a small parameter are considered. Unlike the polytropic or barotropic gas cases, we find that firstly, as the parameter decreases to a certain critical number, the two-shock solution converges to a delta shock wave solution of the same system. Moreover, as the parameter goes to zero, that is, the pressure vanishes, the solution is nothing but the delta shock wave solution to the zero-pressure relativistic Euler system. Meanwhile, the two-rarefaction wave solution tends to the vacuum solution to the zero-pressure relativistic system, and the solution containing one rarefaction wave and one shock wave tends to the contact discontinuity solution to the zero-pressure relativistic system as pressure vanishes.     

Direct transformation of variational problems into Cauchy systems. I. Scalar-quadratic case

This series of papers addresses three interrelated problems: the solution of a variational minimization problem, the solution of integral equations, and the solution of an initial-valued system of integro-differential equations. It will be shown that a large class of minimization problems requires the solution of linear Fredholm integral equations. It has also been shown that the solution of a linear Fredholm integral equation is identical to the solution of a Cauchy system. In this paper, we bypass the Fredholm integral equations and show that the minimization problem directly implies a solution of a Cauchy system. This first paper in the series looks only at quadratic functionals and scalar functions.This research was sponsored by the Air Force Office of Scientific Research, Air Force Systems Command, USAF, under Grant No. AFOSR-77-3383.     

On isolated periodic solutions of differential systems

Summary The concept of an isolated periodic solution of a periodic differential system is defined and it is proved that if the number 1 is not a characteristic multiplier of the variational system corresponding to the given periodic solution then this solution is isolated. The concept of a periodic solution with isolated path of an autonomous system is defined and it is proved that if the number 1 is a simple characteristic multiplier of the corresponding variational system then the periodic solution has an isolated path. An example is given showing that the conditions above are not necessary. Entrata in Redazione l’8 giugno 1974.     

机器人与其连带的安全装置构成的系统稳定性分析

本文用强连续算子半群理论证明了机器人与其连带的安全装置构成的系统存在唯一的非负动态依赖解 ,并表明在一定条件下 ,系统存在稳态正解 ,且系统的动态解在通常意义下 (空间范数意义下 )渐近收敛于稳态解     

Modelling and well-posed analysis for software system with rejuvenation

Software rejuvenation, as an effective policy to enhance the performance of software system, has been discussed broadly with the hypothesis that the software system being well posed. A system being well posed means that the dynamical solution not only exists and is unique but also is stable, which means the dynamical solution converges to steady solution as time tends to infinity. To enrich the theory basis of the software system, and to simulate the dynamical solution which is also an instantaneous availability of the software system with rejuvenation, this article models the behaviour of software system by a group of ordinary and partial equations. With the theory of strong continuous semigroup, this article proves that the system is well posed. As a result, the expression and simulation of instantaneous availability of the system is presented.     

Dynamic analysis of a turbidostat model with the feedback control

In this paper, a mathematical model with impulsive state feedback control is proposed for turbidostat system. The sufficient conditions of existence of positive order one periodic solution are obtained by using the existence criteria of periodic solution of a general planar impulsive autonomous system. It is shown that the system either tends to a stable state or has a periodic solution, which depends on the feedback state, the control parameter of the dilution rate and the initial concentration of microorganism and substrate. By investigating the periodic solution, the period and the initial point of the periodic solution are given. The results show that turbidostat with impulsive state feedback control tends to an order one periodic solution.     

Conditionally Periodic Solutions of an Inhomogeneous Linear System Of Differential Equations with Conditionally Periodic Coefficients

We study the existence of a conditionally periodic solution of a linear system with a Stepanov conditionally periodic inhomogeneity. We prove that if this system has a bounded solution, then almost every system in its H-class has a bounded Besicovitch conditionally periodic solution.     

具有二重抛物线解的二次系统

本文给出了具有二重抛物线解的二次系统的一般形状，并与具有并重抛物线解的二次系统相比较，证明了具有二重抛物线解的二次系统也有存在极限环的可能的，而且也是唯一的，但是二重抛物线解却是不可能成为二次系统的分界线不的。     

一类人为错误可修复系统的指数稳定性分析

随着科学技术的发展,特别是电子产品和网络的运用,系统的可靠性分析变得日益重要.在Dhillon B S和Yang N F(1993)中通过增补变量的方法建立了这类系统的数学模型并进行研究.在此基础上进一步讨论系统解的渐进稳定性和指数稳定性,证明了系统算子在Bnacha空间中可以转化为C_0半群,0是系统算子的简单本征值,而且是系统在虚轴上唯一的谱点.此外本文还分析了在系统扰动前后系统算子解的基本谱,结果显示系统的动态解以指数稳定性趋向于系统的稳态解,通过maple作图发现系统稳定解有时候不一定趋向于系统的实际解,这对实际运用有重要的指导意义.     

Nonresonance and Global Existence of Nonlinear Elastic Wave Equations with External Forces

This paper establishes the global existence of classical solution to the system of homogeneous,isotropic hyperelasticity with time-independent external force,provided that the nonlinear term obeys a ty...     

The global attractor of a competitor–competitor–mutualist reaction–diffusion system with time delays

The aim of this paper is to investigate the asymptotic behavior of time-dependent solutions of a three-species reaction–diffusion system in a bounded domain under a Neumann boundary condition. The system governs the population densities of a competitor, a competitor–mutualist and a mutualist, and time delays may appear in the reaction mechanism. It is shown, under a very simple condition on the reaction rates, that the reaction–diffusion system has a unique constant positive steady-state solution, and for any nontrivial nonnegative initial function the corresponding time-dependent solution converges to the positive steady-state solution. An immediate consequence of this global attraction property is that the trivial solution and all forms of semitrivial solutions are unstable. Moreover, the state–state problem has no nonuniform positive solution despite possible spatial dependence of the reaction and diffusion. All the conclusions for the time-delayed system are directly applicable to the system without time delays and to the corresponding ordinary differential system with or without time delays.     

常规故障和定期维修的冗余系统的指数稳定性

利用C_0-半群理论证明了具有常规故障和定期维修的冗余系统非负解的存在唯一性,并研究了相应算子的谱特征,通过分析本质谱界经过紧扰动后的变化,得到系统动态解以指数形式收敛于稳态解.     

The degenerate hyperbolic problem for the two-dimensional nonlinear wave system

This paper constructs a local classical solution of degenerate hyperbolic problem for the two-dimensional nonlinear wave system. To deal with the parabolic degeneracy, we introduce a new set of coordinates to transform the nonlinear wave system to a new system that has explicitly singularity-regularity structures. By constructing a weighted metric space, we establish the existence of solution for the new system. Returning the solution to the original variables, we obtain the existence of the classical solution for the nonlinear wave system with degenerate boundary value problem.     

A Uniformly-Valid Asymptotic Solution to a Matrix System of Ordinary Differential Equations and a Proof of its Validity

A new multiple-scale perturbation technique is employed to find the approximate solution to a fairly general matrix system of ordinary differential equations. This system includes a linear part given by a slowly-varying matrix and a small nonlinear part. The general proof of the method given in previous work is used to show rigorously that the present approximate solution is indeed asymptotic to the solution of the differential system. Some typical special cases of the general solution are also given.     

有两种修复方法的复杂可修复系统解的渐近稳定性

讨论了两种修复方法的系统解的渐近稳定性.证明了系统在Banach空间中生成正压缩c0半群,系统的非负稳定解恰是系统算子0本征值对应的本征向量,系统算子的谱点均位于复平面的左半平面且在虚轴上除0外无谱.     

Regularity for Certain Nonlinear Parabolic Systems

Abstract

By means of an inequality of Poincaré type, a weak Harnack inequality for the gradient of a solution and an integral inequality of Campanato type, it is shown that a solution to certain degenerate parabolic system is locally Hölder continuous. The system is a generalization of p-Laplacian system. Using a difference quotient method and Moser type iteration it is then proved that the gradient of a solution is locally bounded. Finally using the iteration and scaling it is shown that the gradient of the solution satisfies a Campanato type integral inequality and is locally Hölder continuous.     

二维浅水波方程的间断周期解和间断孤立波解讨论

本文讨论地球流体运动浅水波模式中间断周期解与间断孤立波解.在系统的非平衡点即奇点附近考虑轨线性质时,我们发现只要引入广义解的概念(分片光滑连续解),就会产生间断周期解并得到了间断周期解的条件.当系统在退化的过程中,发现系统此时会产生间断的孤立波解,与此同时其它物理量也产生了间断.这里我们发现,一般认为在超高速情况下解会产生间断,然而在非超高速时也会产生间断现象.本文讨论了上述一系列问题得到了间断解的解析解表达式,并把这一事实与飑线的实例进行比较,得到了不少类似之处.     

具有两个状态的修复系统的指数稳定性

利用C0-半群理论证明了具有两个状态的可修复系统非负解的存在唯一性,并研究了相应算子的谱特征,通过分析本质谱界经过扰动后的变化,得到系统动态解以指数形式收敛于稳态解.     

Stochastic equations for two-type continuous-state branching processes with immigration and competition

A class of two-type continuous-state branching processes with immigration and competition is constructed as the solution of a jump-type stochastic integral equation system. We first show that the stochastic equation system has a pathwise unique non-negative strong solution and then prove the comparison property of the solution.     

Stability of the nonconstant stationary solution to the Poisson–Nernst–Planck–Navier–Stokes equations

We study the three-dimensional Cauchy problem of the Poisson–Nernst–Planck–Navier–Stokes equations. We first show that the corresponding stationary system has a unique semi-trivial solution under a general doping profile. Under initial small perturbations around such the semi-trivial stationary solution and small doping profile, we obtain the unique global-in-time solution to the non-stationary system. Moreover, we prove the asymptotic convergence of the solution toward the semi-trivial stationary solution as time tends to infinity.