1. Department of College of Computer Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, China
2. Interdisciplinary Centre for Security, Reliability and Trust, University of Luxembourg, Esch-Belval Esch-sur-Alzette, Luxembourg
3. Department of School of Mathematical Sciences, Peking University, Beijing, China
4. Department of Management Science and Information Systems, Rutgers University, New Brunswick, NJ, USA