1. PGI-1, FZ Jülich, Jülich, Germany
2. Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology, Richard Birkelandsvei 2B, N-7491 Trondheim, Norway
3. The Yokohama Rubber Company, 2-1 Oiwake, Hiratsuka, Kanagawa 254-8601, Japan