1. School of Economics, Ocean University of China, 266100 Qingdao Shandong, China; Ocean Development Research Institute, Major Research Base of Humanities and Social Sciences of Ministry of Education, Ocean University of China, 266100 Qingdao Shandong, China
2. School of Economics, Ocean University of China, 266100 Qingdao Shandong, China
3. School of Management Science and Engineering, Shandong University of Finance and Economics, 250014 Jinan Shandong, China