1. Department of Product and Systems Design Engineering, University of the Aegean, Syros, Greece
2. Department of Informatics, Aristotle University of Thessaloniki, Thessaloniki, Greece
3. School of Science and Technology, Hellenic Open University, Patras, Greece
4. Department of Information & Communication Systems Engineering, University of the Aegean, Samos, Greece
5. Department of Computer Science and Engineering, University of Bologna, Bologna, Italy
6. Department of Communication and Internet Studies, Cyprus University of Technology, Limassol, Cyprus
7. School of Computer Science, Northwestern Polytechnical University, Xi’an, Shaanxi, China