1. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin, Milwaukee, P.O. Box 784, Milwaukee, WI 53201 (corresponding author).
2. Ph.D. Candidate, School of Control Science and Engineering, Shandong Univ., No. 17923, Jingshi Rd., Jinan, Shandong 250061, China.
3. Research Associate, School of Control Science and Engineering, Shandong Univ., No. 17923, Jingshi Rd., Jinan, Shandong 250061, China.
4. Lecturer, School of Transportation, Inner Mongolia Univ., No. 24, Zhaojun Rd., Yuquan District, Hohhot, Inner Mongolia 010020, China.