Study On Memristor And Memcapacitor Based Chaotic Circuit And Its Application In Network Cloud Storage File

In 1971,Chua proposed the concept of the memristor.Until 2008,HP lab was firstly fabricated the physical model of memristor by nano-scale TiO₂ film,confirming the real existence of memristor.And in 2009 Chua enriched the concept of memory devices based on memristor and put forward the concepts of memcapacitor and meminductor.Then the researches of memory devices were rapidly becoming a hot topic of scholars at home and abroad.However,due to the limitations of the material and production process,these memory devices do not appear in the market,including HP memristor,as well as memcapacitor and meminductor.So the research of the memcapacitor is currently only in the modeling stage,and the pre-research of memcapacitor by using the model is important and perspective.This paper studies the definition of memcapacitor,and the mathematical models of charge controlled memcapacitor and flux controlled memcapacitor are proposed respectively.We establish their equivalent circuits,and design a chaotic oscillation circuit using the charge controlled memcapacitor and the HP TiO₂ memristor.Then we analysis its dynamic characteristics and the randomness.Finally it is applied to the network cloud storage file encryption.The innovative works of this paper mainly include the following aspects:?1?Based on HP memristor we propose two mathematical models for a charge controlled memcapacitor and a flux controlled memcapacitor,and analysis their port characteristics.According to the mathematical model of the memcapacitor,we present its equivalent circuit models.Through the circuit simulation,their v-q characteristics fully meet the hysteretic behavior of the memcapacitor under a sinusoidal excitation,and nonlinear characteristics of the memcapacitor model are verified further.?2?The basic chaotic theory is studied,and the characteristics of some common chaotic systems are analyzed.Based on the traditional two-dimensional discrete Henon mapping,an optimized discrete mapping is proposed.Then the dynamic characteristics such as bifurcation and Lyapunov exponents,of the proposed mapping are analyzed.We find that the mapping has bigger parameter region,therefore increasing the chaotic key space and the security.Finally,A simple application of the mapping in image encryption is given.?3?To further explore nonlinear characteristics of memory devices,we design a chaotic oscillator circuit containing a charge controlled memcapacitor and a HP TiO₂ memristor,and analyze its complex dynamic characteristics.Its complex dynamical characteristics including equilibrium point,bifurcation diagram,Laypunov exponent spectrum,time domain waveform,and Poincare mapping etc.are analyzed in detail.It is found that this chaotic system exhibits the phenomena of hyperchaos,coexisting attractors and abrupt chaos etc.According to the state equations of the chaotic system,an equivalent circuit is designed.The circuit is simulated by Multisim and the experimental results are in agreement with the theoretical analysis.The chaotic sequence of the chaotic system is discretized and quantified by DSP technology.Finally we also test the randomness of the chaotic sequences by NIST test software.Compare with the well-know Lorenz system,the chaotic sequence has good randomness.?4?A network cloud storage file encryption system is proposed,which is a practical application of the designed chaotic system.The system mainly uses a chaos-AES hybrid algorithm to encrypt the information.In the Windows operating system,JAVA is used to design a web page system for the file encryption and decryption.Finally,the security of the encryption algorithm is analyzed,and we can find that the algorithm is very sensitive to the key,and has a very large key space,which makes the encrypted file has better security.