1. College of Geomatics, Xi’an University of Science and Technology, Xi’an 710054, China
2. State Key Laboratory of Efficient Utilization of Arid and Semi-Arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
3. School of Urban Economics and Public Administration, Capital University of Economics and Business, Beijing 100070, China
4. College of Marxism, Xi’an University of Science and Technology, Xi’an 710054, China