Memristor-based Chaotic Systems Research Articles

Analysis of a time-dependent memristor-based chaotic system and its application in image encryption

Abstract Compared with ordinary chaotic systems, memristor-based chaotic systems have more complex dynamic behaviors and are more suitable for image encryption algorithms. In this paper, a four-dimensional chaotic system is constructed by introducing a cubic nonlinear memristor into a three-dimensional chaotic system. Firstly, the dynamic characteristics of the constructed memristor-based chaotic system are analyzed in detail, and the simulation results show that the system has different attractors with different topological structures at different simulation times. Within a fixed simulation time, the system has 15 attractors with different topological structures under different parameter values, and there is a phenomenon of multiple stability in the system, indicating high complexity. Based on the above discoveries, a color image encryption algorithm including scrambling and diffusion is designed. Experimental results show that this algorithm can perfectly hide the information of the plaintext image, and the decrypted image is consistent with the plaintext image. Finally, the security of the algorithm is analyzed by using key space and so on. The analysis results indicate that the encryption algorithm designed in this paper can effectively resist external attacks and has high security.

A physical memristor-based chaotic system and its application in colour image encryption scheme

This work proposes a physical memristor (TaOx) based new 4D chaotic system with 3D multi-scroll, no equilibrium point, spiking behaviour, coexistence bursting oscillation and multistability. Using this physical memristor-based chaotic system, a novel and efficient colour image encryption algorithm has been developed using a unique box scrambling method and bit-wise XOR operations. Many interesting and new dynamics of a material-based memristive chaotic system are reported here, like 3D multi-scroll chaotic attractors, bursting characteristics, multistability, a neuronal system like spiking behaviours etc using Lyapunov spectrum and bifurcation plots. It is observed that the number of scrolls is changed with the total simulation time. This novel memristive chaotic system has limit cycles with controllable spikes and bursting oscillation. In addition, the system shows chaotic bursting oscillation under a different set of parameters and initial conditions. The coexistence of the bursting phenomena is studied here. The bursting and spiking characteristic is important for material-based memristors in neuromorphic applications. 3D Chaotic multi-scroll and multistability properties make the image encryption method more efficient and secure. Such characteristics are rare in physical memristor-based chaotic systems and using this, the image encryption algorithm is also rare in recent findings. Therefore, a new secure image encryption algorithm for colour images is proposed here, based on the unique box scrambling method, bitwise XOR operation and pseudo-random number generation using the proposed memristive chaotic system. Various tests like NPCR, UACI, histogram analysis, correlation study, information entropy analysis, robustness against external noise, etc have been performed to check the algorithm’s robustness and efficiency and test the capability to resist statistical and differential attacks.

Nonlinear analysis and chaos synchronization of a memristive-based chaotic system using adaptive control technique in noisy environments

The behavior of memristor-based chaotic systems under the influence of external noise is the subject of recent work. In this paper, the nonlinear behavior of a new memristive chaotic system based on memcapacitor and meminductor is considered in noisy environments. The nonlinear behavior of the proposed memristive chaotic system in the presence of white Gaussian noise is viewed through a time series of dynamical analyses, Lyapunov exponent analysis, and phase diagram analysis. Then, chaos synchronization of two memristive chaotic systems in the presence of white gaussian noise is considered. For this purpose, adaptive feedback control laws are derived from achieving global chaos synchronization of identical new memristive chaotic systems. To confirm the validity of the proposed method, some numerical simulations follow identical synchronizations. Numerical simulations are performed to show the effectiveness of the proposed method.

Memristor-Based Lozi Map with Hidden Hyperchaos

Recently, the application of memristors to improve chaos complexity in discrete chaotic systems has been paid more and more attention to. To enrich the application examples of discrete memristor-based chaotic systems, this article proposes a new three-dimensional (3-D) memristor-based Lozi map by introducing a discrete memristor into the original two-dimensional (2-D) Lozi map. The proposed map has no fixed points but can generate hidden hyperchaos, so it is a hidden hyperchaotic map. The dynamical effects of the discrete memristor on the memristor-based Lozi map and two types of coexisting hidden attractors boosted by the initial conditions are demonstrated using some numerical methods. The numerical results clearly show that the introduced discrete memristor allows the proposed map to have complicated hidden dynamics evolutions and also exhibit heterogeneous and homogeneous hidden multistability. Finally, a digital platform is used to realize the memristor-based Lozi map, and its experimental phase portraits are obtained to confirm the numerical ones.

Parameter Identification of Memristor-Based Chaotic Systems via the Drive-Response Synchronization Method

Memristor-based chaotic systems have been received great attention from researchers in the last decade. This brief investigates parameter identification of a memristor-based chaotic system (proposed by Muthuswamy in 2010). Uncertain parameter identification has not been studied yet for memristor-based chaotic systems. Using the Lyapunov stability theory and Barbălat lemma, two theorems are established to identify uncertain parameters of the system under the following two cases: i) the memductance is unknown; ii) capacitances and inductances are unknown. Finally, numerical simulations are carried out and the results show that the proposed parameter identification methods are effective.

Synchronization of memristor-based chaotic systems by a simplified control and its application to image en-/decryption using DNA encoding

In this paper, a simplified control is proposed to realize chaotic synchronization based on two identical memristor-based chaotic systems. Firstly, by using a cubic function model of memristor, a memristor-based chaotic system is realized by circuit emulation. Secondly, based on the minimum phase system and Routh–Hurwitz criterion, the state trajectories of two identical chaotic systems can be asymptotically synchronized by the proposed simplified control. The simulation results illustrate that the designed simplified control is effective to chaotic synchronization. Finally, an encryption scheme of color image using DNA encoding is proposed based on chaotic synchronization, and the results of statistical analysis are given to show the effectiveness of the proposed scheme in image processing.

Dynamic analysis of symmetric behavior in flux-controlled memristor circuit based on field programmable gate array

<sec> The lack of the relationship between flux and charge has been made up for by the memristor which is suitable to constructing chaotic circuits as a nonlinear element. Commonly, the memristor-based chaotic systems are constructed by introducing the model of memristor into various classical nonlinear circuits, and more special and abundant dynamic behaviors are existent in these memristive systems. With the deepening of research, several novel nonlinear phenomena of memristor circuits have been found, such as hidden attractors, self-excited attractors and anti-monotonic characteristic. Meanwhile, multistability of a memristor-based circuit explained by the coexistence of multiple attractors with different topological structures is a typical phenomenon in a nonlinear system, and it is also one of the hotspots in this field. In addition, the chaotic sequences generated by the memristive circuits are used as additional signals for information transmission or image encryption. Therefore, the study of modeling memristor systems and analyzing various nonlinear behaviors is of certain valuable.</sec><sec> In this paper, a four-dimensional flux-controlled memeristive circuit is constructed by introducing an active memristor with absolute value into an improved Chua’s circuit, and the special dynamic behaviors are observed. Through the bifurcation diagrams and Lyapunov exponent spectra, the symmetric bifurcations are shown, and the symmetric system states in parameter mappings are found. Besides, the distribution maps of memristive circuit are used to analyze the multistability in a symmetrical attraction domain, and the corresponding phase diagrams are depicted to confirm the existence of multistability. Furthermore, the circuit experiments of the flux-controlled memeristive circuit are implemented by the field programmable gate array simulation, and the experimental results are obtained on a digital oscilloscope, which proves the physical implementability of the memristor-based system.</sec>

Variable Impulsive Synchronization of Memristor-Based Chaotic Systems With Actuator Saturation

This paper is concerned with the synchronization of memristor-based chaotic system subject to actuator saturation via variable impulsive control. Firstly, a memristor-based circuit model is considered, and an impulsive controller subject to actuator saturation is designed. Based on the Lyapunov stability theory and some inequality techniques, some sufficient conditions are derived to guarantee the asymptotic synchronization of the memristor-based chaotic systems. Compared with the common fixed impulsive control, the variable impulsive control used in this paper is more reliable in practical application. Finally, the numerical simulations are given to verify the effectiveness of the proposed method.

Multiple coexisting attractors of the serial–parallel memristor-based chaotic system and its adaptive generalized synchronization

The nonlinear circuit with serial–parallel memristors shows special internal characteristics and external performance, which indicates that the serial–parallel memristors can greatly change the dynamic characteristics of the nonlinear system. Mathematical model of the system is established to analyze the influence of the serial–parallel memristors on the dynamical behaviors with the change of system parameters, and then the basin of attraction is used to exhibit the coexisting multiple attractors with different initial conditions and the serial–parallel memristors, which can reveal that the serial–parallel flux-controlled or charge-controlled memristors have different effects on the generation of chaos and multistability phenomenon. Moreover, the hardware description of memristor-based system through FPGA is realized by Verilog language and the experimental results are observed from digital oscilloscope. Finally, based on the Lyapunov stability theory and adaptive control law, a nonlinear controller is designed to achieve the adaptive generalized synchronization between five memristor-based chaotic systems, and numerical results of the adaptive generalized synchronization are presented to prove the correctness and effectiveness of the proposed method.

Modeling and Analysis of a Fractional-Order Generalized Memristor-Based Chaotic System and Circuit Implementation

Memristor is a nonlinear “missing circuit element”, that can easily achieve chaotic oscillation. Memristor-based chaotic systems have received more and more attention. Research shows that fractional-order systems are more close to real systems. As an important parameter, the order can increase the flexibility and degree of freedom of the system. In this paper, a fractional-order generalized memristor, which consists of a diode bridge and a parallel circuit with an equivalent unit circuit and a linear resistance, is proposed. Frequency and electrical characteristics of the fractional-order memristor are analyzed. A chain structure circuit is used to implement the fractional-order unit circuit. Then replacing the conventional Chua’s diode by the fractional-order generalized memristor, a fractional-order memristor-based chaotic circuit is proposed. A large amount of research work has been done to investigate the influence of the order on the dynamical behaviors of the fractional-order memristor-based chaotic circuit. Varying with the order, the system enters the chaotic state from the periodic state through the Hopf bifurcation and period-doubling bifurcation. The chaotic state of the system has two types of attractors: single-scroll and double-scroll attractor. The stability theory of fractional-order systems is used to determine the minimum order occurring Hopf bifurcation. And the influence of the initial value on the system is analyzed. Circuit simulations are designed to verify the results of theoretical analysis and numerical simulation.

Dynamical analysis and FPGA implementation of a chaotic oscillator with fractional-order memristor components

Memristor-based chaotic and hyperchaotic systems are of great interest in the recent years, and addition of meminductor and memcapacitors to the family has widened the applications. In this paper, we propose a new chaotic system with fractional-order memristor and memcapacitor components. Nonlinear chaotic properties of the proposed system are investigated with equilibrium points, eigenvalues, Lyapunov exponents, bifurcation and bicoherence plots. We show that a small model disturbance can make the system to show self-excited and hidden attractors. We use the Adomian Decomposition method for implementing the proposed system in Field Programmable Gate Arrays.

Adaptive Modified Function Projective Lag Synchronization of Memristor-Based Five-Order Chaotic Circuit Systems

The modified function projective lag synchronization of the memristor-based five-order chaotic circuit system with unknown bounded disturbances is investigated. Based on the LMI approach and Lyapunov stability theorem, an adaptive control law is established to make the states of two different memristor-based five-order chaotic circuit systems asymptotically synchronized up to a desired scaling function matrix, while the parameter controlling strength update law is designed to estimate the parameters well. Finally, the simulation is put forward to demonstrate the correctness and effectiveness of the proposed methods. The control method involved is simple and practical.

Impulsive synchronization for TS fuzzy model of memristor-based chaotic systems with parameter mismatches

In this paper, the effect of parameter mismatch on the impulsive synchronization for TS fuzzy model of memristor-based chaotic system is investigated and some new and useful criteria are derived. Moreover, using the linear decomposition and comparison system methods, the global quasisynchronization for memristor-based chaotic systems based on the TS fuzzy model in the presence of parameter mismatch is discussed. Finally, numerical simulation results are presented to illustrate the effectiveness of the theoretical results.

Modeling of memristor-based chaotic systems using nonlinear Wiener adaptive filters based on backslash operator

Memristor-based chaotic systems have complex dynamical behaviors, which are characterized as nonlinear and hysteresis characteristics. Modeling and identification of their nonlinear model is an important premise for analyzing the dynamical behavior of the memristor-based chaotic systems. This paper presents a novel nonlinear Wiener adaptive filtering identification approach to the memristor-based chaotic systems. The linear part of Wiener model consists of the linear transversal adaptive filters, the nonlinear part consists of nonlinear adaptive filters based on the backslash operator for the hysteresis characteristics of the memristor. The weight update algorithms for the linear and nonlinear adaptive filters are derived. Final computer simulation results show the effectiveness as well as fast convergence characteristics. Comparing with the adaptive nonlinear polynomial filters, the proposed nonlinear adaptive filters have less identification error.

Parameter estimation of unknown fractional-order memristor-based chaotic systems by a hybrid artificial bee colony algorithm combined with differential evolution

In this paper, parameter estimation of unknown fractional-order memristor-based chaotic systems is concerned. Firstly, the parameter estimation is transformed into a multi-dimensional optimization problem, where the fractional orders are treated as independent variables. Then, a hybrid artificial bee colony algorithm combined with differential evolution and other searching mechanisms is put forward to solve the optimization problem. Finally, to demonstrate the effectiveness of the proposed method, numerical simulations based on two typical fractional-order memristor-based chaotic systems are conducted. The simulation results shows that the proposed approach for parameter estimation of unknown chaotic systems is a successful and promising method with higher calculation accuracy, faster convergence speed, and stronger robustness.

Adaptive Synchronization of Memristor - based Chaotic Neural Systems

Adaptive Synchronization of Memristor - based Chaotic Neural Systems

Impulsive synchronization and initial value effect for a memristor-based chaotic system

Taking Chua's circuit with a smooth cubic flux-controlled memristor as an example, the impulsive control synchronization method for two identical memristor-based chaotic systems is studied. Based on the Lyapunov stability theory, the asymptotic stability condition for the impulsive synchronization of the memristor-based chaotic systems is given. Combining with the maximum conditional Lyapunov exponent spectrum of the error system, effects of the system initial values on the performances of impulsive synchronization are discussed, and corresponding simulation experiments are performed. Results indicate that using impulsive synchronization for the two identical memristor-based chaotic systems is feasible and effective with appropriate impulsive control parameters; the initial values of the memristor-based chaotic systems have some effects on the performances of impulsive synchronization, which can be inhibited by increasing the impulsive coupling strength.

Impulsive Control of Memristive Chaotic Systems with Impulsive Time Window

The problem of impulsive control for memristor-based chaotic circuit systems with impulsive time windows is investigated. Based on comparison principle, several novel criteria which guarantee the asymptotic stabilization of the memristor-based chaotic circuit systems are obtained. In comparison with previous results, the present results are easily verified. Numerical simulations are given to further illustrate the effectiveness of the theoretical results.

Synchronization of fractional-order different memristor-based chaotic systems using active control

In this article, synchronization of two different fractional-order memristor-based chaotic systems is considered. To achieve synchronization, an active control technique is used. The main proof is concerned with the problem of synchronization of memristor-based Lorenz systems with memristor-based Chua’s circuits. Numerical simulations of fractional-order memristor-based chaotic systems are performed by using the Caputo version and a predictor–corrector algorithm for fractional-order differential equations, which is a generalization of the Adams–Bashforth–Moulton method. From the simulations, it will be verified that the proposed control method is effective in achieving synchronization.

RECONFIGURABLE HARDWARE PLATFORM FOR EXPERIMENTAL TESTING AND VERIFYING OF MEMRISTOR-BASED CHAOTIC SYSTEMS

Although the memristor is produced physically, it is not commercially available yet. For this reason the testing and verifying of memristor-based systems are performed only by using simulation tools and emulator circuits composed of generally discrete components. In this study, field programmable analog array (FPAA) as a reconfigurable hardware platform is introduced for the experimental testing and verifying of memristor-based chaotic systems. By using this platform, it is possible to implement several memristor-based chaotic systems characterized with different nonlinear functions on a unique hardware in a reconfigurable and programmable manner without the need for different emulators. For this purpose, three memristor-based chaotic systems were constructed on this platform and their behaviors were verified experimentally.