1. School of Business Administration, Shandong Technology and Business University, Yantai 264005, China
2. School of Electrical Engineering, Shandong University, Jinan 250061, China
3. Center for Mathematics and Physics, Weifang University of Science and Technology, Weifang 262700, China
4. Institute of Free Trade Zones, Shandong Technology and Business University, Yantai 264005, China