1. Department of Automotive and Mechatronics Engineering, National Higher Polytechnic School of Douala, University of Douala, Box 24, Douala 2701, Cameroon
2. Department of Mechanical Engineering, College of Technology, University of Buea, P.O. Box 63, Buea, Cameroon
3. Department of Hydraulics and Water Management, National Advanced School of Engineering, University of Maroua, P.O. Box 46, Maroua, Cameroon
4. Department of Physics, College of Education, Nyala University, P.O. Box 155, Nyala, Sudan
5. Research Unit of Condensed Matter of Electronics and Signal Processing, Department of Physics, Faculty of Sciences, University of Dschang, P.O. Box 67, Dschang, Cameroon
6. Department of Physics, Faculty of Science, University of Maroua, P.O. Box 814, Maroua, Cameroon