Design Of Wien-bridge Chaotic Circuit Based On Absolute Memristor And Its Encryption Application

As the fourth basic electrical component,memristor is essentially a nonlinear resistor with memory characteristics.Since the TiO2 physical memristor was first fabricated by Hewlett-Packard laboratory in 2008,the research on memristor has been widely concerned by academia.However,memristor has not been commercialized yet,which greatly hinders the research of memristor.Therefore,the significance of this thesis is to build a new memristor mathematical model and its circuit simulator according to electrical characteristics of memristor,design memristive chaotic circuit based on the memristor mathematical model,mine and analyze the characteristics of memristor and the complex dynamic behaviors of memristive chaotic circuit,and further realize the encryption application of memristive chaotic circuit.The research work of this thesis focuses on the mathematical modeling and design of equivalent analog circuit of memristor,the construction,dynamic analysis and application of memristive chaotic circuit.First,the concepts and basic circuit theories of memristor,and the related concepts of memristive chaotic circuit are briefly introduced in this thesis.According to the definition of the generalized memristor,a mathematical model of the absolute memristor is proposed,and the characteristics of the absolute memristor are analyzed in this thesis.The analysis result shows that the absolute memristor is locally active.The equivalent analog circuit of the absolute memristor is designed in this thesis,and the correctness of the numerical simulation results is verified by Multisim software.Then,the presented memristor is applied in chaotic circuit.A Wien-bridge chaotic circuit based on absolute memristor is constructed in this thesis.The dynamic characteristics of the presented Wien-bridge memristive chaotic system is analyzed with the help of phase trajectory diagrams,bifurcation diagrams,Poincare section mapping projection and Lyapunov exponent spectra.The analysis results show that the presented memristive chaotic circuit has multistability and constant chaos state.Furthermore,the equivalent analog circuit of Wien-bridge memristive chaotic circuit is designed and simulated by Multisim.The simulation results are consistent with the Matlab numerical analysis results,which verify the correctness of the numerical analysis.Then,the proposed Wien-bridge memristive chaotic system is realized by the digital system.The binary sequence is extracted from the Wien-bridge memristive chaotic system,and the extracted binary sequence is tested by random performance test.The test results show that the extracted sequence meets the randomness requirements and can be used as the key sequence for encryption,which lays the foundation for the application of Wien-bridge memristive chaotic system in the field of encryption.Finally,a memristive chaotic encryption system is designed based on the proposed Wien-bridge memristive chaotic circuit,which realizes the encryption application of memristive chaotic system.In this encryption system,the sequence extracted from the memristive chaotic system is used as the key,the chaos stream cipher algorithm and chaos AES algorithm are used to realize the encryption of text documents,Word documents and picture documents.