1. Unité de Recherche de Matière Condensée, dElectronique et de Traitement du Signal (URMACETS), Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon
2. Unité de Recherche dAutomatique et Informatique Appliquée (LAIA), Department of Electrical Engineering, IUT-FV Bandjoun, University of Dschang, Dschang, Cameroon
3. Laboratory of Mechanics, Materials and Structures, Faculty of Science, Department of Physics, University of Yaounde 1, P. O. Box 812 Yaounde, Cameroon