Models Of Memristor And Its Application In Chaos Circuit And Image Watermarking

Since HP Labs has realized the TiO2memristor in2008, study of it has received the attentionof scholars both at home and abroad. TiO2memristor is a nonlinear resistor with memory ofnanometer scale structure, there are potential applications in nonvolatile memory, artificial neuralnetwork, large scale integrated circuit and other fields, but until now the TiO2memristor has notyet been marketization. In this background, in order to know the circuit characteristic of TiO2memristor well, this paper studied the circuit characteristics of TiO2memristor, and itsmathematic model and an emulator which imitates the behavior of a TiO2memristor werepresented, on the basis of TiO2memristor models, we designed a new chaotic oscillator, and triedto combine TiO2memristor oscillator with the digital watermarking, proposed a watermarkingalgorithm based on HVS and DWT, and evaluated its invisibility and robustness. The mainresearch contents of this paper are shown as follows:(1) Under the condition of that there is no TiO2memristor in the market, in order to providean alternative hardware model (or an emulator) for TiO2memristor circuit experiment, anequivalent circuit was designed by integrated operational amplifier based on the volt-amperecharacteristics which was proposed by HP Laps. Under different frequency sine and triangularwave excitation, the port properties of the model were simulated by Multism, and the result wasconsistent with theoretical features. According to the load control model of TiO2memristor, amathematical model of TiO2memristor was derived in theory, providing a base for the design ofchaotic circuit.(2) In order to explore the dynamical characteristics of TiO2memristor in nonlinear circuits,based on Chua’s circuit with Chua’s diode replaced by the conduction model of TiO2memristor, anovel memristor oscillator was obtained. At first, in order to understand the changing dynamicalbehaviors, some basic properties, including equilibrium set, Lyapunov exponent spectrum andbifurcation with respect to various circuit parameters, were investigated theoretically andnumerically. Secondly, we adopt DSP (Digital Signal Processor) to simulate and confirm theproposed memristor oscillator. At last, the way of generating chaotic sequences was described andtested by NIST (National Institute of Standard and Technology). The results showed goodperformance. So it can be used for later applications.(3)TiO2memristor’s another practical application was studied, that the digital imagewatermarking, and a watermarking algorithm based on HVS and DWT was proposed bycombining TiO2memristor oscillator with the digital watermarking. First of all, the way of generating chaotic sequences mentioned above can be used for watermark image encrypting ingood performance. Secondly, the watermarking algorithm was experimented by Matlab, and itsinvisibility and robustness were analyzed. In the meantime, the normal attack was tested, and itsrobustness was analyzed by extracting the watermark. In the end, the concealment and security ofthe way was analyzed.