1. Yanshan University, Qinhuangdao 066004, P. R. China
2. Ningbo Institute of Dalian University of Technology, No.26 Yucai Road, Jiangbei District, Ningbo 315016, P. R. China
3. Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, P. R. China