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    Application and Modeling of a Novel 4D Memristive Chaotic System for Communication Systems
    (Springer Birkhauser, 2020) Sahin, Muhammet Emin; Taskiran, Zehra Gulru Cam; Guler, Hasan; Hamamci, Serdar Ethem
    In this paper, a new four-dimensional (4D) chaotic system which contains an active flux-controlled memristor characterized with a smooth continuous cubic nonlinearity is introduced. The objective is to obtain a 4D chaotic system which contains quadratic terms by using the memristor model which is designed as a new cubic emulator. A new chaotic circuit equation is obtained by using this emulator. The chaotic behavior of the system is observed both theoretically and graphically. The fundamental dynamics of the chaotic system are examined by using equilibrium points, phase portraits, Lyapunov exponents and bifurcation diagrams. The proportional-integral-derivative (PID) control design obtained using optimization algorithms is presented for memristor-based chaotic system. Firefly algorithm and genetic algorithm are used in PID control design for obtaining optimal PID controller gains that provides optimization between master and slave circuits. To verify system performance, this proposed PID-based chaotic circuit is used to communicate communication systems. Experimental results of this system are obtained and presented in real time.
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    Design and Realization of a Hyperchaotic Memristive System for Communication System on FPGA
    (Int Information & Engineering Technology Assoc, 2020) Sahin, Muhammet Emin; Guler, Hasan; Hamamci, Serdar Ethem
    In this study, a memristor based hyperchaotic circuit is presented and implemented for communication systems on FPGA platform. Four dimensional hyperchaotic system, which contains active flux controlled memristor is designed by using a smooth continuous nonlinearity. Dynamical characteristics of designed hyperchaotic circuit are examined such as equilibrium points, chaotic attractors, Lyapunov exponents and bifurcation diagram. Furthermore, an electronic circuit model of hyperchaotic system has been modeled and results are submitted. Chaotic circuits are used in communication systems especially in secure communication due to their sensitive dependence on the initial conditions, not periodic, and having a spread spectrum. By using nonlinearity of memristor, the signals obtained from memristor based hyperchaotic system have been realized to analog and digital communication schemes on FPGA platform, which is suitable for re-programmable and reconfigurable systems. The success of memristor based hyperchaotic circuit with FPGA based communication is demonstrated by both simulation and experimental results.
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    Design of a hyperchaotic memristive circuit based on wien bridge oscillator
    (Pergamon-Elsevier Science Ltd, 2020) Sahin, M. Emin; Demirkol, A. Samil; Guler, Hasan; Hamamci, Serdar E.
    In this paper, a hyperchaotic memristive circuit that is based on a Wien bridge oscillator structure is introduced. The circuit contains an active flux-controlled memristor that is characterized with a smooth continuous cubic nonlinearity. Firstly, a floating implementation of the memristor is used in order to show the flexibility of the element and consequently, a typical application example is analyzed by employing it as the nonlinear element in Chua circuit. Later, the simulation and the experimental realization of the hyperchaotic memristive circuit are performed, resulting in a consistent match between them. Moreover, the dynamics of the proposed hyperchaotic system are theoretically examined in detail. When compared to similar work in the literature, the proposed hyperchaotic system demonstrates clear improvements such as non-clipping amplitude behavior and simplified circuit implementation along with rich chaotic dynamics. The proposed circuit can further be implemented for chaotic encryption, communication systems and synchronous control applications.
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    Use of memristor-based chaotic circuits in AM-DCSK and FM-DCSK modulation
    (Iop Publishing Ltd, 2023) Sahin, Muhammet Emin; Kolumban, Geza; Hamamci, Serdar Ethem; Guler, Hasan
    In this paper, digital communications systems are built by taking advantage of hyperchaotic circuits implemented with an active flux-controlled memristor. The signals produced by these hyperchaotic circuits with rich chaotic dynamics obtained by replacing the nonlinear element with the memristor in the Chua circuit and the Wien bridge oscillator are used as carriers in digital communications systems. The dynamic behavior of memristor-based hyperchaotic circuits has a high degree of disorder. Therefore, they offer better system performance in many practical applications such as broadband signal generation, encryption and secure communications compared to the already used ordinary chaotic systems. To demonstrate the excellent system performance of memristor-based chaotic circuits, they are applied to two variants of differential chaos shift keying (DCSK) communications schemes. Both the Amplitude Modulated Differential Chaos Shift Keying (AM-DCSK) and Frequency-modulated differential chaos shift keying (FM-DCSK) have been considered. The Bit Error Rate (BER) performances of the proposed AM-DCSK and FM-DCSK systems are evaluated in an Additive White Gaussian Noise (AWGN) channel.