1. School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
2. Shaanxi Provincial Key Laboratory of Industrial Automation, Shaanxi University of Technology, Hanzhong, Shaanxi 723000, China
3. Major Public Information Research Center of Shaanxi Province, Northwestern Polytechnical University, Xi’an, China
4. School of Marxism, Northwestern Polytechnical University, Xi’an, China