1. Department of Geography, Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, CT 06269.
2. Tongji University, 1239 Siping Road, Shanghai, China.
3. Department of Urban and Regional Planning, University of Florida, Gainesville, FL 32611.
4. Department of Computer Science, University of Wisconsin, 3200 North Cramer Street, Milwaukee, WI 53211.
5. College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.