[1] Department of Basic Science, National Advanced School of Mines and Petroleum Industries, University of Maroua, P.O. Box 08, Kaélé, Cameroon
[2] Laboratory of Mechanics, Materials and Structures, Department of Physics, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaoundé, Cameroon
[3] Department of Physics, Faculty of Science, University of Maroua, P.O. Box 814, Maroua, Cameroon
[4] Department of Marine Engineering, Limbe Nautical Arts and Fisheries Institute, P.O. Box 485, Limbe, Cameroon
[5] Department of Mathematics, Lafayette College, Easton,PA, United States
[6] Biruni University, Department of Computer Engineering, Istanbul, Turkey
[7] Fırat University, Science Faculty, Department of Mathematics, Elazig,23119, Turkey
[8] Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
[9] National Advanced School of Engineering, University of Yaounde I, Cameroon