In this paper, we discuss the existence of the positive time periodic mild solutions for the evolution equation in an ordered Banach space E, u (t) + Au(t) = f (t, u(t)), t ∈ R, where A : D(A) ⊂ E → E is a closed linear operator and -A generates a positive compact semigroup T(t) (t ≥ 0) in E, the nonlinear function f : R × E → E is continuous and f (t, x) is ω-periodic in t. We apply the operator semigroup theory and the Leray-Schauder fixed point theorem to obtain the existence of a positive ω-periodic mild solution under the condition that the nonlinear function satisfies a linear growth condition concerning the growth exponent of the semigroup T(t) (t ≥ 0). In the end, an example is given to illustrate the applicability of our abstract results.
MSC: 34K30; 47H07; 47H08Keywords: abstract evolution equation; positive periodic mild solutions; positive compact semigroup; the growth exponent of the semigroup; fixed point theorem