1. Mathematics Laboratory, Djillali Liabes University of Sidi Bel Abbes, Sidi Bel Abbes, Algeria
2. Research Unit LaMOS (Modeling and Optimization of Systems), Faculty of Technology, University of Bejaia, Bejaia, Algeria
3. Laboratory of Stochastic Models, Statistic and Applications, University of Saida-Dr. Moulay Tahar, Saida, Algeria
4. Department of Basic Sciences, University of Engineering and Technology, Peshawar, Pakistan