Affiliation: | 1. IRTES-M3M, UTBM, 90010, Belfort CEDEX, France 3. Department of Physics, Faculty of Science, University of Ngaoundéré, P.O. Box 454, Ngaoundere, Cameroon 2. Department of Industrial and Mechanical Engineering, Ecole Nationale Sup erieure Polytechnique University of Yaoundé I, P.O. Box 8390, Yaoundé, Cameroon
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