考虑泛函微分方程u′(t)=a(t)u(t)-λb(t)f(u(t-τ(t)))正周期解的存在性,其中λ〉0为参数,a∈C(R,[0,∞))为ω-周期的,且∫ω0a(t)dt〉0;b,τ∈C(R,R)为ω-周期的.f∈C([0,∞),R)且f(0)〉0.在函数b变号的情形下,本文运用Leray-Schauder不动点定理,建立了上述泛函微分方程正周期解的存在性结果.
We are concerned with the existence of positive periodic solutions of the following functional differential equation u′(t)=a(t)u(t)-λb(t)f(u(t-τ(t))) where λ0 is a parameter,a∈C(R,[0,∞)) is a ω-periodic and ∫ω0a(t)dt0;b,τ∈C(R,R) are ω-periodic.f∈C([0,∞),R) and f(0)0.By using Leray-Schauder fixed point theorem,we establish the existence results of positive periodic solutions for the above problem under the case that b may change its sign.