1. Mines Saint-Etienne, CNRS, UMR 6158 LIMOS, Institut Henri Fayol, University Clermont Auvergne, 42023 Saint-Etienne, France
2. Department of Applied Mathematics, Faculty of Sciences, Lebanese University, Beirut 2038 1003, Lebanon
3. EHESP Rennes and Institut Élie Cartan de Lorraine, CEDEX, 54506 Vandoeuvre-lès-Nancy, France