参数未知的统一超混沌系统自适应反同步

文章研究了参数未知的统一超混沌系统的控制与同步问题.首先基于Lyapunov稳定性理论,设计了自适应控制器,证明了该控制器可使参数未知统一超混沌系统渐近稳定于不动点.其次使用自适应反同步方法,设计了自适应同步控制器,实现了参数未知统一超混沌系统的完全同步,最后数值仿真实验进一步验证了所提出方案的有效性. 关键词： 统一超混沌系统 自适应控制器 自适应反同步     

化学法制备低介电常数聚酰亚胺的研究进展

随着微电子工业的快速发展,为了提高大规模集成电路中芯片间的传输速度以满足高集成化的要求,需要层间绝缘材料具有较低的介电常数。聚酰亚胺已被广泛用于大规模集成电路的层间绝缘材料,降低其介电常数的研究在近年来受到了广泛关注。当采用化学方法降低介电常数时,调控聚酰亚胺的分子结构是基础;在聚酰亚胺中构建多孔结构则是进一步降低介电常数的有效手段。本文从调控分子结构和构建多孔结构的角度出发,综述了化学法制备低介电常数聚酰亚胺的研究进展,并对低介电常数聚酰亚胺的研究前景进行了展望。     

A one-time one-key encryption algorithm based on the ergodicity of chaos

In this paper, we propose a new one-time one-key encryption algorithm based on the ergodicity of a skew tent chaotic map. We divide the chaotic trajectory into sub-intervals and map them to integers, and use this scheme to encrypt plaintext and obtain ciphertext. In this algorithm, the plaintext information in the key is used, so different plaintexts or different total numbers of plaintext letters will encrypt different ciphertexts. Simulation results show that the performance and the security of the proposed encryption algorithm can encrypt plaintext effectively and resist various typical attacks.     

Competition between two kinds of information among random-walking individuals

A model is proposed to describe the competition between two kinds of information among N random-walking individuals in an L × L square, starting from a half-and-half mixture of two kinds of information. Individuals remain or change their information according to their neighbors’ information. When the moving speed of individuals v is zero, the two kinds of information typically coexist, and the ratio between them increases with L and decreases with N. In the dynamic case (v>0), only one information eventually remains, and the time required for one information being left scales as Td～vαLβNγ.     

Synchronization of spatiotemporal chaotic systems and application to secure communication of digital image

Coupled map lattices (CMLs) are taken as examples to study the synchronization of spatiotemporal chaotic systems.In this paper,we use the nonlinear coupled method to implement the synchronization of two coupled map lattices.Through the appropriate separation of the linear term from the nonlinear term of the spatiotemporal chaotic system,we set the nonlinear term as the coupling function and then we can achieve the synchronization of two coupled map lattices.After that,we implement the secure communication of digital image using this synchronization method.Then,the discrete characteristics of the nonlinear coupling spatiotemporal chaos are applied to the discrete pixel of the digital image.After the synchronization of both the communication parties,the receiver can decrypt the original image.Numerical simulations show the effectiveness and the feasibility of the proposed program.     

Cryptanalysis of a chaos-based cryptosystem with an embedded adaptive arithmetic coder

In this paper,we analyse a new chaos-based cryptosystem with an embedded adaptive arithmetic coder,which was proposed by Li Heng-Jian and Zhang J S (Li H J and Zhang J S 2010 Chin.Phys.B 19 050508).Although this new method has a better compression performance than its original version,it is found that there are some problems with its security and decryption processes.In this paper,it is shown how to obtain a great deal of plain text from the cipher text without prior knowledge of the secret key.After discussing the security and decryption problems of the Li Heng-Jian et al.algorithm,we propose an improved chaos-based cryptosystem with an embedded adaptive arithmetic coder that is more secure.     

An efficient adaptive arithmetic coding image compression technology

This paper proposes an efficient lossless image compression scheme for still images based on an adaptive arithmetic coding compression algorithm. The algorithm increases the image coding compression rate and ensures the quality of the decoded image combined with the adaptive probability model and predictive coding. The use of adaptive models for each encoded image block dynamically estimates the probability of the relevant image block. The decoded image block can accurately recover the encoded image according to the code book information. We adopt an adaptive arithmetic coding algorithm for image compression that greatly improves the image compression rate. The results show that it is an effective compression technology.     

Projective synchronization of a complex network with different fractional order chaos nodes

Based on the stability theory of the linear fractional order system, projective synchronization of a complex network is studied in the paper, and the coupling functions of the connected nodes are identified. With this method, the projective synchronization of the network with different fractional order chaos nodes can be achieved, besides, the number of the nodes does not affect the stability of the whole network. In the numerical simulations, the chaotic fractional order Lü system, Liu system and Coullet system are chosen as examples to show the effectiveness of the scheme.     

基于一阶时滞混沌系统参数辨识的保密通信方案

基于参数调制原理,针对一阶时滞Logistic混沌系统设计了相应的参数观测器,仅传递单路信号就可以成功辨识出系统中的未知参数,从而恢复出调制在参数中的模拟信号,并在此基础上采用不同频率信号代替“0”或“1”,设计出具体的数字保密通信方案.数值仿真验证了本方法的有效性. 关键词： 观测器 混沌保密通信 参数调制 滤波