Electronic Journal of Differential Equations,
Vol. 2012 (2012), No. 80, pp. 1-10.

Title: Positive solutions for fractional differential equations
       with variable coefficients 

Authors: Yi Chen (Central South Univ., Hunan, China)
         Zhanmei Lv (Central South Univ., Hunan, China)

Abstract:  
 In this article, we study the existence of the positive solutions
 for a class of differential equations of fractional order with variable
 coefficients. The equation of this type plays an important role in the
 description and modeling of control systems, such as $PD^{\mu}$-controller.
 The differential operator is taken in the Riemann-Liouville sense.
 Our analysis relies on the Leggett-Williams fixed point theorem.
 
Submitted April 3, 2012. Published May 18, 2012.
Math Subject Classifications: 26A33, 34A08, 34A12.
Key Words: Fractional differential equations;  fixed point theorem; 
           positive solution; multiplicity solution.