Project supported by the National Natural Science Foundation,China (No.91318301,61003019,61021062,61100039),the National Basic Research Program,China(No.2009CB320702),the Fund of State Key Laboratory for Novel Software Technology (Nanjing University),China(No.ZZKT2011B10),the Key Laboratory of Intelligent Perception and Systems for High-Dimensional Information (Nanjing University of Science and Technology),the Ministry of Education,China(No.30920130122005),and the Fundamental Research Funds for the Central Universities,China(No.021714340029).