1. Faculty of Sciences of Bizerta, Department of Mathematics, GAMA Laboratory LR21ES10, University of Carthage, Bizerta, Tunisia
2. Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
3. XLIM (UMR CNRS 7252), Universite de Poitiers, Futuroscope Chasseneuil Cedex, France