1. School of Information Science and Technology, North China University of Technology, Beijing, P.R. China
2. School of Software, Beihang University, Beijing, P.R. China
3. Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, P.R. China
4. Department of Engineering & Environmental Science, City University of New York/CSI, Staten Island, NY, USA