This paper studies the Riemann problem for a system of nonlinear degenerate wave equations in elasticity. Since the stress function is neither convex nor concave, the shock condition is degenerate. By introducing a de...This paper studies the Riemann problem for a system of nonlinear degenerate wave equations in elasticity. Since the stress function is neither convex nor concave, the shock condition is degenerate. By introducing a degenerate shock under the generalized shock condition, the global solutions are constructively obtained case by case.展开更多
In this paper we consider the Riemann problem for the nonlinear degenerate wave equations. This problem has been studied by Sun and Sheng, however the so-called degenerate shock solutions did not satisfy the R-H condi...In this paper we consider the Riemann problem for the nonlinear degenerate wave equations. This problem has been studied by Sun and Sheng, however the so-called degenerate shock solutions did not satisfy the R-H condition. In the present paper, the Riemann solutions of twelve regions in the v - u plane are completely constructed by the Liu-entropy condition. Our Riemann solutions are very different to that one obtained by Sun and Sheng in some regions.展开更多
This paper is devoted to a study of the null controllability problems for one-dimensional linear degenerate wave equations through a boundary controller. First, the well-posedness of linear degenerate wave equations i...This paper is devoted to a study of the null controllability problems for one-dimensional linear degenerate wave equations through a boundary controller. First, the well-posedness of linear degenerate wave equations is discussed. Then the null controllability of some degenerate wave equations is established, when a control acts on the non-degenerate boundary. Different from the known controllability results in the case that a control acts on the degenerate boundary, any initial value in state space is controllable in this case. Also, an explicit expression for the controllability time is given. Furthermore, a counterexample on the controllability is given for some other degenerate wave equations.展开更多
In this paper,we study the existence and regularity of travelling wave front solutions for some degenerate parabolic equations (u^m/m)t=u_(xx)+u^nf(u),where m,n>0 and f(u)～1-u.We show that the existence and regula...In this paper,we study the existence and regularity of travelling wave front solutions for some degenerate parabolic equations (u^m/m)t=u_(xx)+u^nf(u),where m,n>0 and f(u)～1-u.We show that the existence and regularity of travelling wave front solutions depend on the parameters m,n and the wave speed c.展开更多
In this paper,the authors mainly consider the exact controllability for degenerate wave equation,which degenerates at the interior point,and boundary controls acting at only one of the boundary points.The main results...In this paper,the authors mainly consider the exact controllability for degenerate wave equation,which degenerates at the interior point,and boundary controls acting at only one of the boundary points.The main results are that,it is possible to control both the position and the velocity at every point of the body and at a certain time T for the wave equation with interior weakly degeneracy.Moreover,it is shown that the exact controllability fails for the wave equation with interior strongly degeneracy.In order to steer the system to a certain state,one needs controls to act on both boundary points for the wave equation with interior strongly degeneracy.The difficulties are addressed by means of spectral analysis.展开更多
基金Project supported by the National Natural Science Foundation of China(No.10971130)the Shanghai Leading Academic Dissipline Project(No.J50101)
文摘This paper studies the Riemann problem for a system of nonlinear degenerate wave equations in elasticity. Since the stress function is neither convex nor concave, the shock condition is degenerate. By introducing a degenerate shock under the generalized shock condition, the global solutions are constructively obtained case by case.
基金Supported by the National Natural Science Foundation of China (11171340)
文摘In this paper we consider the Riemann problem for the nonlinear degenerate wave equations. This problem has been studied by Sun and Sheng, however the so-called degenerate shock solutions did not satisfy the R-H condition. In the present paper, the Riemann solutions of twelve regions in the v - u plane are completely constructed by the Liu-entropy condition. Our Riemann solutions are very different to that one obtained by Sun and Sheng in some regions.
基金supported by the National Natural Science Foundation of China under Grant Nos.11371084,11471070 and 11171060the Fundamental Research Funds for the Central Universities under Grant Nos.14ZZ2222 and 2412015BJ011+1 种基金the National Basic Research Program of China(973 Program)under Grant No.2011CB808002the Fok Ying Tong Education Foundation under Grant No.141001
文摘This paper is devoted to a study of the null controllability problems for one-dimensional linear degenerate wave equations through a boundary controller. First, the well-posedness of linear degenerate wave equations is discussed. Then the null controllability of some degenerate wave equations is established, when a control acts on the non-degenerate boundary. Different from the known controllability results in the case that a control acts on the degenerate boundary, any initial value in state space is controllable in this case. Also, an explicit expression for the controllability time is given. Furthermore, a counterexample on the controllability is given for some other degenerate wave equations.
基金This project is supported by the Notional Natural Science Foundation of China
文摘In this paper,we study the existence and regularity of travelling wave front solutions for some degenerate parabolic equations (u^m/m)t=u_(xx)+u^nf(u),where m,n>0 and f(u)～1-u.We show that the existence and regularity of travelling wave front solutions depend on the parameters m,n and the wave speed c.
基金supported by the National Natural Science Foundation of China under Grant No.12271316the National Natural Science Foundation of China for the Youth under Grant No.11801339+1 种基金Shanxi Sciences Project for Selected Overseas Scholars under Grant No.2018–172the Technical Innovation Team of Jinzhong University under Grant No.202111。
文摘In this paper,the authors mainly consider the exact controllability for degenerate wave equation,which degenerates at the interior point,and boundary controls acting at only one of the boundary points.The main results are that,it is possible to control both the position and the velocity at every point of the body and at a certain time T for the wave equation with interior weakly degeneracy.Moreover,it is shown that the exact controllability fails for the wave equation with interior strongly degeneracy.In order to steer the system to a certain state,one needs controls to act on both boundary points for the wave equation with interior strongly degeneracy.The difficulties are addressed by means of spectral analysis.
