The existence of positive !-periodic solutions for order differential equations u′(t) + Mu(t) = f(t, u(t)), ∀ t ∈ R in an ordered Banach spaces E is discussed, where f : R × P → P is continuous, and P is the cone of positive elements in E. An existence result of positive !-periodic solutions is obtained by employing a new estimate of noncompactness measure and the fixed point index theory of condensing mapping.
LI Xiaolong.
EXISTENCE OF POSITIVE PERIODIC SOLUTIONS FOR ORDER DIFFERENTIAL EQUATIONS IN ORDERED BANACH SPACES. Journal of Systems Science and Mathematical Sciences, 2012, 32(2): 190-196 https://doi.org/10.12341/jssms11822