1. Computer Sciences Research Laboratory, Department of Computer Science and Telecommunications, National Advanced School of Engineering of Maroua, The University of Maroua, P. O. Box 46, Maroua, Cameroun
2. School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, Henan 454000, P. R. China
3. Department of Electrical Engineering, Advanced Teachers’ Training College for Technical Education, The University of Douala, P. O. Box 1872, Douala, Cameroun
4. Department of Marine Engineering, Limbe Nautical Arts and Fisheries Institute, P. O. Box 854, Limbe, Cameroun
5. Department of Computer Engineering, Biruni University, Istanbul, Turkey
6. Department of Mathematics, Faculty of Sciences, Firat University, 23119 Elazig, Turkey
7. Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan, R. O. China