[1] Univ Minho, Phys Dept, CFUM UP, P-4800058 Guimaraes, Portugal
[2] Univ Coimbra, SEG CEMMPRE Ctr Mech Engn Mat & Proc, Dept Mech Engn, Rua Luis Reis Santos, P-3030788 Coimbra, Portugal
[3] Palbit SA, P-3850582 Branca, Albergaria A Ve, Portugal
[4] CETEF MG Fed Ctr Technol Educ Minas Gerais, BR-36700000 Leopoldina, MG, Brazil
[5] Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, IPN LED & MAT, Rua Pedro Nunes, P-3030199 Coimbra, Portugal
[6] Czech Tech Univ, Dept Control Engn, Tech 2, Prague 16627 6, Czech Republic