Comments on "Passive and Impulsive Synchronization of a New Four-Dimensional Chaotic System"(Nonlinear Analysis, doi:10.1016/j.na.2010.09.051)

Department of Mathematics, Faculty of Science, Sohag University, Sohag 82524, Egypt College of Applied Medical Sciences,Taif University,Turabah, Kingdom of Saudi Arabia emad_eluan@yahoo.com Kholod M. Abualnaja Department of Mathematics, Umm Al-Qura University, P.O. Box 14949, Makkah,Kingdom of Saudi Arabia. E-mail:kmaboualnaja@uqu.edu.sa bstract— The aim of this letter is to point out some comments on the article "Nonlinear Analysis 74 (2011) 1146-1154, doi:10.1016/j.na.2010.09.051". We hope to improve the results, published in the[1]. Based on the passivity theory the controllers are designed to synchronize two identical chaotic Qi systems with known parameters. We prove the error system between the two identical chaotic Qi systems with the controller is minimum phase. The analytical results of the controllers, which have been calculated, are tested numerically and good agreement is obtained.