1. Department of Engineering, Shizuoka University, Hamamatsu 432-8561, Japan;
2. Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, 42122 Reggio Emilia, Italy;
3. DEI “Guglielmo Marconi”, Alma Mater Studiorum University of Bologna, 40126 Bologna, Italy;
4. Department of Mathematical Informatics, Nagoya University, Nagoya 464-8601, Japan