1. School of Software, Dalian University of Technology, Dalian, China
2. School of Computer Science and Engineering, Northeastern University, Shenyang, China
3. College of Information Technology, Incheon National University, Incheon, South Korea
4. School of Computer Systems Engineering, Universidad Politécnica de Madrid, Madrid, Spain
5. Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang, China