1. Mem. ASME Faculty of Arts, Computing, Engineering and Sciences, Department of Engineering and Mathematics, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, UK e-mail:
2. Faculty of Arts, Computing, Engineering and Sciences, Department of Engineering and Mathematics, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, UK e-mail:
3. Mem. ASME Dipartimento di Scienza e Metodi dell'Ingegneria, Università di Modena e Reggio Emilia, Via Amendola, 2, Reggio Emilia 42100, Italy e-mail:
4. Dipartimento di Scienza e Metodi dell'Ingegneria, Università di Modena e Reggio Emilia, Via Amendola, 2, Reggio Emilia 42100, Italy e-mail:
5. Mem. ASME Departamento de Engenharia Eletromecânica, Universidade da Beira Interior, Covilhã 6200, Portugal e-mail: