Electronic Journal of Differential Equations,
Vol. 2019 (2019), No. 47, pp. 1-12.

Title: Periodic solutions of second-order non-autonomous dynamical systems with
       vanishing Green's functions

Author: Yongxin Jiang (Hohai Univ., Nanjing, China)
 
Abstract:
 In this article, we study the existence and multiplicity of positive
 periodic solutions for second-order non-autonomous dynamical systems
 when Green's functions are non-negative. The proofs are based on a nonlinear
 alternative principle of Leray-Schauder and the fixed point theorem in cones.
 Some recent results in the literature are generalized and  improved.

Submitted March 18, 2018. Published April 10, 2019.
Math Subject Classifications: 34C25, 34B15, 34A25.
Key Words: Vanishing Green's function; Leray-Schauder alternative;
           fixed point theorem in cones