No review has been posted.
No open issue.
This work was supported by National Basic Research Program of China under grant No. 2010CB227104, the National Natural Science Foundation of China under grants No. 31100954, No. 61272380 and No. 61173118, the Open Research Fund Program of Shanghai Key Laboratory of Intelligent Information Processing, Fudan University (No. IIPL-2010-011), and PhD Program Scholarship Fund of Changzhou University (No. CCZUPY1001).