1. Escuela Tcnica Superior de Ingeniera y Diseo Industrial, Universidad Politecnica de Madrid, 16771 Madrid, Spain, 28012 (e-mail: r.damato@upm.es)
2. University of Rome Tor Vergata, 9318 Roma, Lazio, Italy, 00133 (e-mail: amato@ing.uniroma2.it)
3. Department of Precision Mechanical Engineering, Shanghai University, 34747 Shanghai, Shanghai, China, 200444 (e-mail: chenwang@shu.edu.cn)
4. Department of Industrial Engineering, University of Salerno, 19028 Fisciano, Campania, Italy, 84084 (e-mail: ruggiero@unisa.it)