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The study of magnetohydrodynamics (MHD) and thermal radiation over‐stretching and shrinking sheets has significant applications in a wide range of fields, from chemical manufacturing to transport engine cooling systems, electronic chip cooling, plasma, the nuclear‐powered sector, saltwater, etc. The present study aims to numerically and theoretically analyze the movement of thermally magnetized Williamson nanofluid owing to an extended/contracting sheet. The regulating flow equations are converted to self‐similar equations through similarity transformation, and then numerically solved by bvp4c using MATLAB software. A comparison of the present numerical study with the published study is quite impressive. The investigation demonstrates that the self‐similar equations disclose the two branches for the limited shrinking factor range. For the stretching case, only one solution exists. As a result, the most fundamentally feasible solution has been determined by the linear assessment of temporal stability. For the aim of stability analysis, the lowest eigenvalue sign indicates the stability or instability of a solution. Through stability analysis, it is witnessed that the first solution (first branch) is stable. Due to the presence of the Lorentz force effect, it is perceived that the velocity curves decline in the whole channel. The point to be noted here is that the velocity of the lower branch compared to the upper branch is higher. The reduced Skin Friction is increased in the first branch and declines in the second branch for the two different values of magnetic factor.

This paper proposes a new robust adaptive sliding mode control (RASMC) technique and investigates the control of chaos in the two-dimensional uncertain spin-orbit problem of Enceladus (SOPE) in the presence of external disturbances and model uncertainties. The external disturbances, model uncertainties, and nonlinear terms of the system are bounded and unknown. The proposed RASMC technique: 1) accomplishes oscillation free and fast convergence of the state variables to the origin; 2) suppresses chattering in the control inputs. The Lyapunov stability theory verifies the convergence behaviour and guarantees the robust asymptotic stability of the equilibrium point at the origin. In the sense of Lyapunov function, this article also provides parameters adaptation laws that confirm the convergence of uncertain parameters to some constants. The computer simulation results verify the theoretical findings and provide comparative analysis. The results of this study could be beneficial in the area of space sciences.

This paper studies the adaptive combined synchronisation (ACS) of different unknown chaotic systems. In the proposed scheme, the state vectors of a response system synchronise with the corresponding state vectors of the combined dual drive systems. The Lyapunov stability theory proves the asymptotic stability of the closed loop system at the origin. This work provides parameter update laws that estimate the actual values of unknown parameters. Important numerical simulation is included to show the effectiveness of the propose synchronisation scheme.

•This work establishes global exponential multi switching combination synchronization (GEMSCS) of chaotic systems.•A time efficient nonlinear feedback controller is designed.•The proposed work enhances the security and complexity of the communication channel.•The GEMSCS accomplishes fast and oscillation free converges of the error signals to the zero state.

Abstract: In this paper, we investigate the reduced-order anti-synchronization of uncertain chaotic systems. Based upon the parameters modulation and the adaptive control techniques, we show that dynamical evolution of third-order chaotic system can be anti-synchronized with the canonical projection of a fourth-order chaotic system even though their parameters are unknown. The techniques are successfully applied to two examples: hyperchaotic Lorenz system (fourth-order) and Lorenz system (third-order); Lü hyperchaotic system (fourth-order) and Chen system (third-order). Theoretical analysis and numerical simulations are shown to verify the results. [Copyright &y& Elsevier]

Abstract: This paper brings attention to hyperchaos anti-synchronization between two identical and different hyperchaotic systems by using adaptive control. The sufficient conditions for achieving the anti-synchronization of two hyperchaotic systems are derived based on Lyapunov stability theory. An adaptive control law and a parameter update rule for unknown parameters are introduced such that the hyperchaotic Chen system is controlled to be the hyperchaotic Lü system. Theoretical analysis and numerical simulations are shown to verify the results. [Copyright &y& Elsevier]

Abstract: Based on the nonlinear control theory, the anti-synchronization between two different hyperchaotic systems is investigated. Through rigorous mathematical theory, the sufficient condition is drawn for the stability of the error dynamics, where the controllers are designed by using the sum of the relevant variables in hyperchaotic systems. Numerical simulations are performed for the hyperchaotic Chen system and the hyperchaotic Lü system to demonstrate the effectiveness of the proposed control strategy. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to investigate the accuracy of the Adomian decomposition method for solving the hyperchaotic Rössler system, which is a four-dimensional system of ODEs with quadratic nonlinearities. Comparisons between the decomposition solutions and the fourth-order Runge–Kutta (RK4) solutions are made. It is found that the comparable accuracy of the ADM with the RK4 for the chaotic Lorenz system does not carry to the hyperchaotic Rössler system. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to investigate the accuracy of the differential transformation method (DTM) for solving the hyperchaotic Rössler system, which is a four-dimensional system of ODEs with quadratic nonlinearities. Comparisons between the DTM solutions and the fourth-order Runge–Kutta (RK4) solutions are made. The DTM scheme obtained from the DTM yields an analytical solution in the form of a rapidly convergent series. The direct symbolic-numeric scheme is shown to be efficient and accurate. [Copyright &y& Elsevier]