College of Automation, Northwestern Polytechnical University,Xi'an 710072, P.R. China;
Center for Biometrics and Security Research and National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing 100080,P. R. China;
College of Automation, Northwestern Polytechnical University,Xi'an 710072, P.R. China;
College of Automation, Northwestern Polytechnical University,Xi'an 710072, P.R. China;
College of Automation, Northwestern Polytechnical University,Xi'an 710072, P.R. China;
College of Automation, Northwestern Polytechnical University,Xi'an 710072, P.R. China;