标题：Birkhoffnormal forms for the wave equations with nonlinear terms depending on the time and space variables
作者机构：[Wang, Yi ] School of Mathematics and Quantitative Economic, Shandong University of Finance and Economics, Jinan, Shandong 250014, China
来源：Computer Modelling and New Technologies
摘要：The one-dimensional (1D) quasi-periodically forced nonlinear wave equation with periodic boundary conditions is considered. It is proved that there is a real analytic and symplectic change of coordinates, which can transform the Hamiltonian to the Birkhoffnormal form.