Copyright © 2011 Zigen Ouyang et al. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Though boundary value problems for fractional differential equations have been
extensively studied, most of the studies focus on scalar equations and the fractional
order between 1 and 2. On the other hand, delay is natural in practical systems.
However, not much has been done for fractional differential equations with delays.
Therefore, in this paper, we consider a boundary value problem of a general delayed
nonlinear fractional system. With the help of some fixed point theorems and the
properties of the Green function, we establish several sets of sufficient conditions on
the existence of positive solutions. The obtained results extend and include some
existing ones and are illustrated with some examples for their feasibility.