1. Geomathematics Key Laboratory of Sichuan Province, Chengdu University of Technology, Chengdu 610059, China
2. Department of Basic Courses, Officers College of People’s Armed Police Force, Chengdu 610213, China
3. College of Information and Intelligent Engineering, Yunnan College of Business Management, Kunming 650304, China
4. Chengdu Gas Group Corporation Ltd., Chengdu 610041, China
5. Chengdu Municipal Bureau of Statistics, Chengdu 610095, China
6. College of Mathematics and Physics, Chengdu University of Technology, Chengdu 610059, China