1. Department of Quality, Health, Safety and Industrial Environment Engineering, National Advanced School of Engineering, University of Douala, P.O. Box 2701, Douala, Cameroon
2. Laboratory of Energy, Materials, Modelling and Methods, Doctorate School of Fundamental and Applied Sciences, University of Douala, Douala, Cameroon
3. Faculty of Science, University of Douala, P.O. Box 24157, Douala, Cameroon