Affiliation: | Faculty of Science and Engineering, Tokyo Institute of Technology, O-okayama, Meguro-Ku, Tokyo 152, Japan;Nagaoka Technical College, 888 Nishikatagai-cho, Nagaoka-city, Niigata 940, Japan;Trolley Laboratory, Railway Technical Research Institute, Hikari-cho, Kokubunji-city, Tokyo 185, Japan |