1. Department of Engineering, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
2. Department of Manufacturing Systems Engineering and Management (MSEM), California State University, 18111 Nordhoff St., Northridge, CA 91330, USA
3. Fluing-Institute for Multidisciplinary Mathematics (IMM), Universitat Politècnica de València, Cno. de Vera s/n, 46022 Valencia, Spain