The modelling and analysis of fractional-order control systems in   discrete domain
  This paper deals with fractional-order controlled systems and fractional-order controllers in the discrete domain. The mathematical description by the fractional difference equations and properties of these systems are presented. A practical example for modelling the fractional-order control loop is shown and obtained results are discussed in conclusion. 
I. Petras, L. Dorcak, I. Kostial (Technical University of Kosice)