1. Electromechanical Engineering Department, University of Beira Interior, Rua Fonte do Lameiro-Edifício 1 das Engenharias, 6201-001 Covilhã, Portugal
2. Mechanical Engineering Department, Polytechnic Institute of Guarda, High School of Technology and Management, Avenida Dr. Francisco Sá Carneiro No. 50, 6300-559 Guarda, Portugal