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As a new technique for authentication and key generation, physically unclonable function (PUF) has attracted considerable attentions, with extensive research results achieved already. To resist the popular machine learning modeling attacks, a framework to enhance the security of PUFs is proposed. The basic idea is to combine PUFs with a chaotic system of which the response is highly sensitive to initial conditions. For this framework, a specific construction which combines the common arbiter PUF circuit, a converter, and the Chua's circuit is given to implement a more secure PUF. Simulation experiments are presented to further validate the framework. Finally, some practical suggestions for the framework and specific construction are also discussed. [ABSTRACT FROM AUTHOR]

A Monte Carlo investigation is made in a dissipative bouncer model to describe some statistical properties for chaotic dynamics as a function of the control parameters. The dynamics of the system is described via a two dimensional mapping for the variables velocity of the particle and phase of the moving wall at the instant of the impact. A small stochastic noise is introduced in the time of flight of the particle as an attempt to investigate the evolution of the system without the need to solve transcendental equations. We show that average values along the chaotic dynamics do not strongly depend on the noise size. It allows us to propose a Monte Carlo like simulation that lead to calculate average values for the observables with great accuracy and fast simulations. [ABSTRACT FROM AUTHOR]

Abstract: This Letter aims at understanding the dynamical process that leads to the onset of chaos in the flow past a blunt-based axisymmetric bluff body. On the basis of direct numerical simulations, conducted for Reynolds numbers ranging from 100 to 900, we show that the flow undergoes multiple transitions, successively giving rise to the SS, , , and RSB wake states. In particular, the state, revealed in this work via long-term computations, is characterized by intermittent vortex stretching denoting the onset of chaos before the symmetry breaking and the occurrence of the RSB state. [Copyright &y& Elsevier]

Abstract: In this Letter, a differential evolution variant, called switching DE (SDE), has been employed to estimate the orders and parameters in incommensurate fractional-order chaotic systems. The proposed algorithm includes a switching population utilization strategy, where the population size is adjusted dynamically based on the solution-searching status. Thus, this adaptive control method realizes the identification of fractional-order Lorenz, Lü and Chen systems in both deterministic and stochastic environments, respectively. Numerical simulations are provided, where comparisons are made with five other State-of-the-Art evolutionary algorithms (EAs) to verify the effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: In this Letter, we propose a Hebbian learning rule with passive forgetting (HLRPF) for use in a chaotic neural network (CNN). We then define the indices based on the Euclidean distance to investigate the evolution of the weights in a simplified way. Numerical simulations demonstrate that, under suitable external stimulations, the CNN with the proposed HLRPF acts as a fuzzy-like pattern classifier that performs much better than an ordinary CNN. The results imply relationship between learning and recognition. [Copyright &y& Elsevier]

Abstract: In this Letter, a new lag projective synchronization for fractional-order chaotic (hyperchaotic) systems is proposed, which includes complete synchronization, anti-synchronization, lag synchronization, generalized projective synchronization. It is shown that the slave system synchronizes the past state of the driver up to a scaling factor. A suitable controller for achieving the lag projective synchronization is designed based on the stability theory of linear fractional-order systems and the pole placement technique. Two examples are given to illustrate effectiveness of the scheme, in which the lag projective synchronizations between fractional-order chaotic Rössler system and fractional-order chaotic Lü system, between fractional-order hyperchaotic Lorenz system and fractional-order hyperchaotic Chen system, respectively, are successfully achieved. Corresponding numerical simulations are also given to verify the analytical results. [Copyright &y& Elsevier]

Abstract: In this Letter, we propose a single control input approach for stabilizing three-dimensional chaotic systems in a finite time. The method is more general and is derived from the finite-time stability theory and adaptive control technique; and can stabilize almost all well-known three-dimensional chaotic systems without a prior knowledge of the feedback gain. To show the wider applicability of our method, we give illustrations using different chaotic systems with different structure. Numerical simulations are also used to verify the effectiveness of the technique. [ABSTRACT FROM AUTHOR]

Abstract: We apply an external feedback control technique to vibrating microcantilevers in atomic force microscopy. Here we have no difficulty in getting information on periodic orbits required for application of the external feedback control unlike controlling chaos since stable orbits are used as reference ones. This approach enables us not only to control vibrations of the cantilevers but also to measure the sample surfaces (surface topographies) simultaneously. The efficiency and validity of our approach is demonstrated by numerical simulations and a theoretical analysis with the assistance of numerical computations. [Copyright &y& Elsevier]

Abstract: Permanent Magnet Synchronous Motor (PMSM) experiences chaotic behavior for a certain range of its parameters. In this case, since the performance of the PMSM degrades, the chaos should be eliminated. In this Letter, the control of the undesirable chaos in PMSM using Lyapunov exponents (LEs) placement is proposed that is also improved by choosing optimal locations of the LEs in the sense of predefined cost function. Moreover, in order to provide the physical realization of the method, nonlinear parameter estimator for the system is suggested. Finally, to show the effectiveness of the proposed methodology, the simulation results for applying this control strategy are provided. [ABSTRACT FROM AUTHOR]

Abstract: This Letter investigates the problem of adaptive lag synchronization and parameters adaptive lag identification of chaotic systems. In comparison with those of existing parameters identification schemes, the unknown parameters are identified by adaptive lag laws, and the delay time is also identified in this Letter. Numerical simulations are also given to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: In this Letter, a novel method is developed for generating grid multi-scroll chaotic attractors using switching piecewise linear controller. First, a third-order linear system is designed to ensure that its unique equilibrium point belongs to a saddle-focus type with index 2 and the corresponding eigenvalues satisfy Shilnikov conditions. Then, by three different types of switching control strategies, the equilibrium point can be extended along both xy plane and z axis direction, so as to generate grid multi-scroll chaotic attractors. The dynamical behaviors are further analyzed. Moreover, an improved module-based circuit is designed for realizing and grid scroll chaotic attractors, and the experimental results are also obtained, which is consistent with the numerical simulations. [Copyright &y& Elsevier]

Abstract: This Letter investigates the stabilization of three-dimensional chaotic systems in a finite time. Based on the finite-time stability theory, a control law is proposed to realize finite-time chaos stabilization of three-dimensional chaotic systems. Several illustrative examples with numerical simulations are studied by using the results obtained in this Letter. Study of examples shows that our control methods work very well in stabilizing a class of chaotic systems in a finite time. [Copyright &y& Elsevier]

Abstract: The proposed anti-synchronization conditions of coupled chaotic systems are based, in this Letter, on the use of aggregation techniques for the stability study of the error dynamics. The schemes are, successfully, applied to coupled Rössler and Chen chaotic systems making the instantaneous characteristic matrix under the arrow form. Numerical simulations are performed to illustrate the efficiency of the proposed approach. [Copyright &y& Elsevier]

Abstract: This Letter investigates the stabilization and synchronization of Genesio–Tesi systems. Firstly, modifying the previous method, we stabilize the Genesio–Tesi system. Then, we synchronize two identical Genesio chaotic system by extending the obtained stabilization results. To the best of our knowledge, the above controllers obtained in this Letter are simpler than those obtained in the existing results. Finally, numerical simulations verify the effectiveness and the validity of the above theoretical results. [Copyright &y& Elsevier]

Abstract: The Letter develops an adaptive impulsive scheme that includes a sole restriction criterion to achieve synchronization of chaotic nonlinear systems with unknown parameters. The system is assumed to satisfy the local Lipschitz condition while a Lipschitz constant and the uncertain system parameters are estimated by augmented adaptation equations. Adaptation of all parameters is proven to converge exponentially. The significance of the related control parameters and their margins in the criterion is also discussed in detail. The Lorenz system has been simulated to illustrate the theoretical analysis. [Copyright &y& Elsevier]

Abstract: The modified function projective lag synchronization (MFPLS) is proposed in this Letter, in which the states of two chaotic systems are asymptotically lag synchronized up to a desired scaling function matrix. Based on Lyapunov stability theory, a general method of MFPLS is investigated. The scheme is successfully applied to two groups examples, which are the MFPLS between Lorenz system and Lü system, and two identical hyper-chaotic Chen system. Corresponding numerical simulations are performed to verify and illustrate the analytical results. [Copyright &y& Elsevier]

Abstract: This Letter investigates the stabilization of three-dimensional chaotic systems, and proposes a novel simple adaptive-feedback controller for chaos control. In comparison with previous methods, the present controller which only contains single state feedback, to our knowledge, is the simplest control scheme for controlling the three-dimensional chaotic system. The results are validated using numerical simulations. [Copyright &y& Elsevier]

Abstract: In this Letter, an output error feedback control scheme is addressed for synchronization of a class of non-autonomous chaotic systems based on the drive-response framework. A fuzzy disturbance observer is used to compensate for the difference between the structures of two different systems. To compensate for the uncertainty caused by the unknown phase difference between the drive and the response systems, an adaptive control scheme is employed that is based on the Lyapunov stability theory. Numerical simulations are presented to illustrate the effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: More and more attention has been payed to the hyperchaotic system for the huge potential applications of hyperchaotic system such as secure communication and more complex structure than chaotic system. So at present the controlling of the hyperchaotic system simply and effectively is a frontier topic of nonlinear science. In this Letter, for the latest hyperchaotic Lorenz system, four feedback control methods were studied with analytic solution and necessary numerical simulations. It is found that the enhancing feedback control approach is the best choice of the given four feedback control methods for its relatively simple external inputs and relatively small necessary feedback coefficient after comparison. The conclusion is a helpful for the choice of control methods of any other chaotic and hyperchaotic systems. [Copyright &y& Elsevier]

Abstract: This Letter focuses on the master–slave synchronization problem of the unified chaotic systems. Based on Lyapunov stability theory and linear matrix inequality (LMI) formulation, a simple linear feedback control law is obtained to make the state of two identical unified chaotic systems asymptotically synchronized. Simulation results have illustrated the effectiveness of the proposed chaos synchronization solution. [Copyright &y& Elsevier]

Abstract: In this Letter, an adaptive control scheme is developed to study the anti-synchronization behavior between two identical and different chaotic systems with unknown parameters. This adaptive anti-synchronization controller is designed based on Lyapunov stability theory and an analytic expression of the controller with its adaptive laws of parameters is shown. The adaptive anti-synchronization between two identical systems (Chen system) and different systems (Genesio and Lü systems) are taken as two illustrative examples to show the effectiveness of the proposed method. Theoretical analysis and numerical simulations are shown to verify the results. [Copyright &y& Elsevier]

Abstract: In virtue of techniques derived from nonlinear control system theory, we establish conditions under which one could obtain anticipating synchronization between two periodically driven deterministic ratchets that are able to exhibit directed transport with a finite velocity. Criteria are established in order to guarantee the anticipating synchronization property of such systems as well as characterize phase space dynamics of the ratchet transporting behaviors. These results allow one to predict the chaotic direct transport features of particles on a ratchet potential using a copy of the same system that performs as a slave, which are verified through numerical simulation. [Copyright &y& Elsevier]

Abstract: The stability conditions in fractional order hyperchaotic systems are derived. These conditions are applied to a novel fractional order hyperchaotic system. The proposed system is also shown to exhibit hyperchaos for orders less than 4. Based on the Routh–Hurwitz conditions, the conditions for controlling hyperchaos via feedback control are also obtained. A specific condition for controlling only fractional order hyperchaotic systems is achieved. Numerical simulations are used to verify the theoretical analysis. [Copyright &y& Elsevier]

Abstract: This work investigates function projective synchronization of two-cell Quantum-CNN chaotic oscillators using adaptive method. Quantum-CNN oscillators produce nano scale chaotic oscillations under certain conditions. By Lyapunove stability theory, the adaptive control law and the parameter update law are derived to make the state of two chaotic systems function projective synchronized. Numerical simulations are presented to demonstrate the effectiveness of the proposed adaptive controllers. [Copyright &y& Elsevier]

Abstract: A high precision fast projective synchronization method was proposed through introducing an impact factor. The numerical simulations indicate that the synchronization precision was increased three orders of magnitude higher than available methods in literature, under the same conditions of numerical method and hardware. The synchronization can achieved after first iteration. The synchronization speed has been increased by 13 484 times and 23 000 times when and , respectively, compared to general methods. [Copyright &y& Elsevier]

Abstract: In this Letter, we propose a new anti-synchronization scheme for a general class of chaotic systems. Based on Lyapunov theory and linear matrix inequality (LMI) approach, for the first time, the anti-synchronization controller is presented to not only guarantee stable anti-synchronization but also reduce the effect of external disturbance to an norm constraint. The proposed controller can be obtained by solving a convex optimization problem represented by the LMI. Simulation study is presented to demonstrate the effectiveness of the proposed anti-synchronization scheme. [Copyright &y& Elsevier]

Abstract: By introducing a control strength matrix, the active control theory in chaotic synchronization is developed. With this extended method, chaos complete synchronization can be achieved more easily, i.e., a much smaller control signal is enough to reach synchronization in most cases. Numerical simulations on Rossler, Liu''s four-scroll, and Chen system confirmed this and show that the synchronization result depends on the control strength significantly. Especially, in the case of Liu and Chen systems, the response systems'' largest Lyapunov exponents'' variation with the control strength is not monotone and there exist minima. It is novel for Chen system that the synchronization speed with a special small strength is higher than that of the usual active control which, as a special case of the extended method, has a much larger control strength. All these results indicate that the control strength is an important factor in the actual synchronization. So, with this extended active control, one can make a better and more practical synchronization scheme by adjusting the control strength matrix. [Copyright &y& Elsevier]

Abstract: The notion of chaotic phase synchronization (CPS) in the large-scale delayed scale-free network is discussed in this Letter. The amplitude death (AD) phenomenon is observed and analyzed in terms of energy. AD occurs when the time-delay becomes long enough. The adaptive coupling scheme has better performance in CPS and AD compared with the constant scheme, and simulation results confirm conclusions. [Copyright &y& Elsevier]

Abstract: Five interesting experiments have been done for a class of chaos synchronization systems with unknown parameters and unknown control directions. And three important conclusions about parameters identification have been made. First, a necessary and sufficient condition for parameters identification is obtained. Second, a Nussbaum method is proposed to solve the problem of unknown control direction. Third, the adaptive method is not infinitely effective considered for our current ability of computation and simulation algorithm. [Copyright &y& Elsevier]

Abstract: In this Letter we numerically investigate the dynamics of a system of two coupled chaotic multimode Nd:YAG lasers with two mode and three mode outputs. Unidirectional and bidirectional coupling schemes are adopted; intensity time series plots, phase space plots and synchronization plots are used for studying the dynamics. Quality of synchronization is measured using correlation index plots. It is found that for laser with two mode output bidirectional direct coupling scheme is found to be effective in achieving complete synchronization, control of chaos and amplification in output intensity. For laser with three mode output, bidirectional difference coupling scheme gives much better chaotic synchronization as compared to unidirectional difference coupling but at the cost of higher coupling strength. We also conclude that the coupling scheme and system properties play an important role in determining the type of synchronization exhibited by the system. [Copyright &y& Elsevier]

Abstract: In this Letter, a new chaos control scheme based on chaos prediction is proposed. To perform chaos prediction, a new neural network architecture for complex nonlinear approximation is proposed. And the difficulty in building and training the neural network is also reduced. Simulation results of Logistic map and Lorenz system show the effectiveness of the proposed chaos control scheme and the proposed neural network. [Copyright &y& Elsevier]

Abstract: This Letter addresses the function project synchronization problem of two Rössler hyperchaotic in the presence of unknown system parameters. Based on Lyapunov stability theory an adaptive control law is proposed to make the states of two identical Rössler hyperchaotic systems asymptotically synchronized. Numerical simulations are presented to show the effectiveness of the proposed schemes. [Copyright &y& Elsevier]

Abstract: Based on Baptista''s chaotic cryptosystem, we propose a secure and robust chaotic cryptographic scheme after investigating the problems found in this cryptosystem as well as its variants. In this proposed scheme, a subkey array generated from the key and the plaintext is adopted to enhance the security. Some methods are introduced to increase the efficiency. Theoretical analyses and numerical simulations indicate that the proposed scheme is secure and efficient for practical use. [Copyright &y& Elsevier]

Abstract: Strategies to design adaptive controllers using only part of the system states for the stabilization of one chaotic system and the synchronization of two chaotic systems are proposed for a general class of chaotic systems. The transient performance in terms of the norm of system states is quantified as an explicit function of the design parameters so that designers can tune the design parameters in an explicit way to obtain the required closed loop behavior. Simulation results also verify the effectiveness of the proposed control schemes. [Copyright &y& Elsevier]

Abstract: A new chaotic secure communication scheme is constructed. Unified chaotic system is used to encrypt the emitted signal. Different from the existing chaotic secure communication methods, the useful information is embodied in the parameter of chaotic systems in this Letter. The receiver is designed which can succeed in recovering the former signal. Finally computer simulations are done to verify the proposed methods, and the results show that the obtained theoretic results are feasible and efficient. [Copyright &y& Elsevier]

We study the control of a first-order continuous-time chaotic vector system with delay. With and without parameter uncertainties are discussed respectively. A system consisting of two cellular equations is taken as a simulation example. [Copyright &y& Elsevier]

Abstract: In this Letter we consider modified function projective synchronization of unidirectionally coupled multiple time-delayed Rossler chaotic systems using adaptive controls. Recently, delay differential equations have attracted much attention in the field of nonlinear dynamics. The high complexity of the multiple time-delayed systems can provide a new architecture for enhancing message security in chaos based encryption systems. Adaptive control can be used for synchronization when the parameters of the system are unknown. Based on Lyapunov stability theory, the adaptive control law and the parameter update law are derived to make the state of two chaotic systems are function projective synchronized. Numerical simulations are presented to demonstrate the effectiveness of the proposed adaptive controllers. [Copyright &y& Elsevier]