[1] Univ Bamenda, Fac Sci, Dept Phys, POB 39, Bamenda, Cameroon
[2] Chennai Inst Technol, Ctr Nonlinear Syst, Chennai 600069, Tamil Nadu, India
[3] Univ Bamenda, Higher Teacher Training Coll, Dept Phys, POB 39, Bamenda, Cameroon
[4] Univ Dschang, Fac Sci, Dept Phys, Lab Mech & Modelling Phys Syst L2MPS, POB 67, Dschang, Cameroon
[5] Univ Maroua, Natl Adv Sch Mines & Petr Ind, Dept Mech Petr & Gas Engn, POB 46, Maroua, Cameroon
[6] Univ Bamenda, Natl Higher Polytech Inst, Dept Mech & Ind Engn, POB 39, Bamenda, Cameroon