1. China University of Mining and Technology, Xuzhou, Jiangsu 221116, P.R.C.; Kokushikan University, 4-28-1 Setagaya, Setagaya-ku, Tokyo 154-8515, Japan
2. China University of Mining and Technology, Xuzhou, Jiangsu 221116, P.R.C.
3. Kokushikan University, 4-28-1 Setagaya, Setagaya-ku, Tokyo 154-8515, Japan