1. Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081, P.R.China;2. Department of Mathematics, Beijing Institute of Bussiness, Beijing 100037, P.R.China
Abstract:
In this paper, by using of the theory of coincidence degree ,we obtain the new conditions which guarantee the existence of harmonic solutions for Lienard Systems our resuls do not require that the damping must be positire.