SchoolofElectricalandElectronicEngineering;
SingaporePolytechnic;
Singapore139651;
ComputerScienceDepartment;
OceanUniversityof(Qingdao;
(Qingdao266003;
P.R.China;
StateKeyLaboratoryofIntelligentSystemsandTechnologiesinTsinghuaUniversity;
Beijing100084;
P.R.China;