1. CNR Institute
of Nanoscience, S3 Center, Via Campi
213/A, I-41125 Modena, Italy
2. SEG-CEMUC,
Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra, Portugal
3. Department
of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, I-41125 Modena, Italy
4. Department
of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, Prague 6, Czech Republic
5. nCATS,
Faculty of Engineering and Environment, University of Southampton, Highfield
Campus, Southampton SO17 1BJ, U.K.