Affiliation: | 1. Department of Mechanical Engineering , Osaka University , 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan tarumi@mech.eng.osaka-u.ac.jp;3. Department of Mathematics , Okayama University , Tsushimanaka 3-1-1, Okayama 700-8530, Japan;4. PRESTO , JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan |