Positive Periodic Solutions of Second-Order Singular Coupled Systems with Damping Terms

摘要

We establish the existence of positive periodic solutions of the second-order singular coupled systems {x" + p1(t)x'+ q1(t)x =f1(t,y(t)) + c1(t),y" + p2(t)y'+ q2 (t)y =f2 (t,x(t)) + c2(t),where pi,qi,ci ∈ C(R/TZ;R),i =1,2;f1,f2 ∈ C(R/TZ × (0,oo),R) and may be singular near the zero.The proof relies on Schauder's fixed point theorem and anti-maximum principle.Our main results generalize and improve those available in the literature.