1. Department of Management and Engineering; University of Padua; Stradella S. Nicola 3 36100 Vicenza Italy
2. Department of Mechanical Engineering; Ibaraki University; Nakanarusawa-cho 4-12-1 Hitachi 316-8511 Japan
3. Department of Material Processing; Tohoku University; Aoba-yama 6-6-02 Sendai 980-8579 Japan