1. Life and Industrial Systems Thermal Engineering-Team (LISTE-T), Research Unit of Mechanics and Physical Systems Modeling (UR-2MSP), Department of Physics, Faculty of Sciences, University of Dschang , P.O. Box 67, Dschang, Cameroon
2. Department of Physics, Higher Teacher Training College Bambili, University of Bamenda , P.O. Box. 39 Bamenda, Bambili, Cameroon