Nonlinear Dyn (2013) 71:469–478 DOI 10.1007/s11071-012-0673-y ORIGINAL PAPER Lag quasisynchronization of coupled delayed systems with parameter mismatch by periodically intermittent control Junjian Huang · Chuandong Li · Tingwen Huang · Qi Han Received: 14 August 2012 / Accepted: 4 November 2012 / Published online: 16 November 2012 © Springer Science+Business Media Dordrecht 2012 Abstract This paper further investigates the lag syn- chronization of coupled delayed systems with parame- ter mismatch. Different from the most existing results, we formulate the intermittent control system that gov- erns the dynamics of the synchronization error. As a result of parameter mismatch, complete lag synchro- nization cannot be achieved. In this paper, a lag qua- sisynchronization scheme is proposed to ensure that coupled systems are in a state of lag synchronization with an error level. We estimate the error bound of lag synchronization by rigorously theoretical analysis. Numerical simulations are presented to verify the the- oretical results. J. Huang ( ) · C. Li · Q. Han College of Computer Science, Chongqing University, Chongqing 400030, China e-mail: hmomu@sina.com C. Li e-mail: licd@cqu.edu.cn Q. Han e-mail: yiding1981@yahoo.com.cn J. Huang Department of Computer Science, Chongqing University of Education, Chongqing 400067, China T. Huang Texas A & M University at Qatar, 23874, Education City, Doha, Qatar e-mail: tingwen.huang@qatar.tamu.edu Keywords Chaotic systems · Intermittent control · Lag quasisynchronization · Parameter mismatch · Time delay 1 Introduction Since the pioneering works of Pecora and Carroll [1], the idea of synchronization of chaotic systems has received a great deal of interest. Over the past decades, many types of chaos synchronization have been presented, e.g., complete synchronization [1, 2], generalized synchronization [3], projective synchro- nization [4], phase synchronization [5], lag synchro- nization [6], and anticipating synchronization [7]. For complete synchronization, the master’s state x(t) and the slave’s state y(t) are identical, i.e., y(t) → x(t). Generalized synchronization is usually described as the presence of some function relation between the slave’s states and the master’s, i.e., there is a func- tion g such that y(t) → g(x(t)). For projective syn- chronization, there is a scale factor in the amplitude of the master’s state variable and that of the slave’s, i.e., y(t) → αx(t). Phase synchronization, which indicates the difference between the phase of the master’s state and that of the slave’s, is constant during interaction, but their amplitudes remain chaotic and uncorrelated, i.e., nφ x − mφ y = const (n and m are integers). For lag synchronization, the state of the slave system is re- tarded with time delay τ in compared to the state of the master system, i.e., y(t) ≈ x τ (t) ≡ x(t − τ) with