Affiliation: | 1. School of Management Science and Engineering, Nanjing University, Nanjing, P.R. China.;2. ENSA, Ibn Zohr University, Agadir, Morocco.a.bnouhachem@uiz.ac.ma;4. Department of Mathematics, Statistics and Physics College of Arts and Sciences Qatar University, Doha, Qatar.;5. School of Mathematics and Physics, Changzhou University, Changzhou, P.R. China. |