1. College of Computer Science, South-Central University for Nationalities, Wuhan 430074, China
2. School of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798
3. Simula Research Laboratory, 1325 Lysaker, Norway
4. School of Engineering and IT, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600, Australia