[1]Department of Electrical Engineering, Federal University of Ceará- UFC, Fortaleza, 60455-760, Brazil;
[2]Department of Mechanical Engineering, Federal University of Sergipe - UFS, Sao Cristovāo, Sergipe 49100-000, Brazil;
[3]Department of Engineering, Pedagogical University- UP, Km 1, Maputo, Mozambique;