Electronic Journal of Differential Equations,
Vol. 2014 (2014), No. 94, pp. 1-10.

Title: Necessary and sufficient conditions for the existence of periodic 
       solution to singular problems with impulses

Authors: Juntao Sun (Shandong Univ. of Technology, Zibo, Shandong, China)
         Jifeng Chu (Hohai Univ., Nanjing, Jiangsu, China)

Abstract:
 In this article we give a necessary sufficient conditions for the existence
 of periodic solutions to impulsive periodic solution for a singular differential
 equation. The proof is based on the variational method.

Submitted  October 30, 2013. Published April 10, 2014.
Math Subject Classifications: 34B15.
Key Words: Positive periodic solution; singular differential equations; 
           impulses; variational methods.