Existence Of Positive Solutions Of Periodic Boundary Value Problems For A Kind Of Fractional Differential Equations

In this thesis,we consider a class of periodic boundary value problems for frac-tional differential equations where ?<0,?>0.D0 ?+u is the Riemann-Liouville fractional derivative of u(t).and f:(0,1)×[0,+?)?[0.+?)is continuous.The main contents of this paper are arranged as follows:Section 1 Preparatory knowledge.Section 2 By using the Guo-Krasnosel'skii's fixed point theorem we study the existence of positive solutions with periodic boundary value problem for fractional differential equationsSection 3 By using the upper and lower solutions method and monotone iterative method,we study the existence of nonnegative solutions with periodic boundary value problem for fractional dmerential equations...