title: Comment on "Generalized projective synchronization in time-delayed systems: nonlinear observer approach" [Chaos 19, 013102 (2009); 20, 029902 (2010)].
abstract: In Chaos 19, 013102 (2009), the author proposed generalized projective synchronization for time delay systems using nonlinear observer and obtained sufficient condition to ensure projective synchronization for modulated time varying delay. There are concerns with the obtained conditions as the result was applicable only to trivial case of time varying delay τ[over dot](1)(t)=dτ(1)(t)/dt<1. In this paper, we note the drawbacks of the proposed sufficient condition. The new improved sufficient condition for ensuring the projective synchronization of time varying delayed systems is presented. The proposed new criteria have been verified by adopting the Ikeda system.
authors.affiliation: Department of Mathematics, Gandhigram Rural University, Gandhigram 624302, Tamilnadu, India.
authors.forename: S Jeeva Sathya
authors.initials: SJ
authors.lastname: Theesar
authors.forename: P
authors.initials: P
authors.lastname: Balasubramaniam
authors.forename: Santo
authors.initials: S
authors.lastname: Banerjee