%0 Journal Article
%T Periodic Solutions to Non-Autonomous Second-Order Dynamical Systems
%A An-Min Mao
%A Miao-Miao Yang
%J Advances in Pure Mathematics
%P 90-94
%@ 2160-0384
%D 2011
%I Scientific Research Publishing
%R 10.4236/apm.2011.13020
%X We study the multiple existence of periodic solutions for a second-order non-autonomous dynamical systems  (1). Using the method of invariant sets of descending flow and chain of rings theorem, we obtain the existence of seven  -periodic solutions.
%K Critical Point
%K Invariant Sets of Descending Flow
%K (PS) Condition
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=5198