1. Laboratory of Modelling and Simulation in Engineering, Biomimetics and Prototypes and TWAS Research Unit, Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon;
2. Department of Physics, University of Lagos, Akoka-Yaba, Lagos, Nigeria
3. Department of Physics, University of Lagos, Akoka-Yaba, Lagos, Nigeria e-mail:
4. Laboratory of Modelling and Simulation in Engineering, Biomimetics and Prototypes and TWAS Research Unit, Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon