1. School of Management Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
2. Ibn Zohr University, ENSA, BP 32/S, Agadir, Morocco
3. Mathematics Department, COMSATS Institute of Information Technology, Islamabad, Pakistan
4. Ecole Supérieure de Technologie de Salé, Mohamed 5 University, Agdal-Rabat, Morocco