ZHANGWen-An Ph.D.candidate at Department of Automation,Zhejiang University of Technology.His research interest covers time-delay systems and networked control systems.E-mail:wazhg@hotmail.com YU Li Professor at Department of Automation,Zhejiang University of Technology.His research interest cavers robust control,time-delay systems,and networked control systems.Corresponding author of this paper.E-mail:lyu@zjut.edu.an