1. Associate Professor, College of Traffic, Northeast Forestry Univ., 26 Hexing Rd., Xiangfang District, Harbin 150040, P.R. China.
2. Lecturer, Faculty of Applied Sciences, Univ. of Sunderland, St. Peters Way, Sunderland SR60DD, U.K.
3. Professor, College of Traffic, Northeast Forestry Univ., 26 Hexing Rd., Xiangfang District, Harbin 150040, P.R. China.
4. Associate Professor, College of Mechanical and Electrical Engineering, Northeast Forestry Univ., 26 Hexing Rd., Xiangfang District, Harbin 150040, P.R. China (corresponding author).