1. Southwest Jiaotong University,School of Information Science and Technology,Chengdu,Sichuan,China
2. Pontosense Inc.,Toronto,ON,Canada,M3J 0G7
3. Mercku Inc.,Toronto,ON,Canada,M3J 0G7
4. Southwest Jiaotong University,School of Economics and Management,Chengdu,Sichuan,China
5. Southwest Jiaotong University,Chengdu,Sichuan,China
6. Hosei University,Faculty of Computer and Information Sciences,Tokyo,Japan,184-8584