1. School of Computer Science and Engineering, Central South University,Changsha,P.R. China
2. School of Information Technology, Carleton University,Ottawa,ON,Canada,K1S 5B6
3. University of Calgary,Department of Electrical and Software Engineering,Calgary,AB,Canada,T2N 1N4
4. Tsinghua University,Department of Computer Science and Technology,Beijing,P.R. China
5. University of Waterloo,Department of Electrical and Computer Engineering,Waterloo,Ontario,Canada