Combined synchronization of time-delayed chaotic systems with uncertain parameters

The article presents combined synchronization among time delayed chaotic systems in the presence of uncertain parameters using nonlinear control method. Control functions are designed to achieve combined synchronization using Lyapunov-Krasovskii function for stability analysis. The synchronization among three and four time delayed chaotic systems have been shown as examples of combined synchronization. Double delay Rossler system, the advanced Lorenz system, time delay Liu and Chen systems have been taken to show the combined synchronization. Numerical simulation and graphical results are carried out using Runge-Kutta method for delay-differential equations, which show that the designing of control functions are very effective and reliable and can be applied for combined synchronization among time-delayed chaotic systems.