Positive periodic solutions of singular systems
arXiv:1007.3302 · doi:10.1016/j.jde.2010.08.027
Abstract
The existence and multiplicity of positive periodic solutions for second order non-autonomous singular dynamical systems are established with superlinearity or sublinearity assumptions at infinity for an appropriately chosen parameter. Our results provide a unified treatment for the problem and significantly improve several results in the literature. The proof of our results is based on the Krasnoselskii fixed point theorem in a cone.
Journal of Differential Equations, 2010