对一种五维混沌图像加密算法的破译与改进

根据选择明文攻击原理,对一种基于五维混沌系统的图像加密算法进行了分析,结果表明该算法不能抵抗选择明文攻击,进而提出了一种基于五维混沌系统的图像加密改进算法,并对改进算法进行了安全性分析和实验测试.理论分析及实验结果表明,改进算法不仅克服了原算法不能抵御选择明文攻击的缺陷,且在相邻像素相关性、信息熵和密钥空间等方面具有更好的密码学特性.     

一个新四维超混沌系统及其混沌同步

在一个新三维混沌系统的基础上增加一维状态,提出了一个新的四维自治超混沌系统,分析了系统的超混沌吸引子相图、平衡点的性质、Lyapunov指数和分形维数等非线性动力学特性．基于线性系统的稳定性分析准则,通过对系统线性项和非线性项的适当分离,构造了混沌同步系统,实现了该同步系统与新超混沌系统的完全同步．Matlab数值仿真结果表明,所设计的同步系统能有效地实现混沌同步．     

MLC电路的混合混沌信号耦合同步方法及同步条件

利用混合混沌信号的单向耦合方法,研究了MLC(Murali-Lakshmanan-Chua)电路混沌同步问题;基于Lyapunov稳定性理论,分析并给出了MLC电路混沌同步的一个充分条件     

实现蔡氏电路族的两种新的规范电路

本文介绍了两种新的规范电路。导出了计算这两种规范电路参数的显式公式,还推广了两位学者的有关定理,使之也适用于新的规范电路。本文设计的规范电路表明,实现蔡氏电路族的规范电路不是唯一的。而其中改造的蔡氏电路也许是最好的一种。     

Rattling系统的一种随机模型

研究了一个叠加噪声的Rattling系统.代替常用的数值分析方法,采用非高斯截断技术导出一个由平均映射描述的离散随机模型．实例指出该模型能揭示浑沌随机性质,可用于模拟齿轮箱噪声源     

Clean numerical simulation for some chaotic systems using the parallel multiple-precision Taylor scheme

An improved parallel multiple-precision Taylor （PMT） scheme is developed to obtain clean numerical simulation （CNS） solutions of chaotic ordinary differential equations （ODEs）. The new version program is about 500 times faster than the reported solvers developed in the MATHEMATICA, and also 2-3 times faster than the older version （PMT-1.0） of the scheme. This solver has the ability to yield longer solutions of Lorenz equations [up to 5000 TU （time unit）]. The PMT-1. I scheme is applied to a selection of chaotic systems including the Chen, Rossler, coupled Lorenz and Lti systems. The Tc-M and Tc-K diagrams for these chaotic systems are presented and used to analyze the computation parameters for long-term solutions. The reliable computation times of these chaotic equations are obtained for single- and double-precision computation.     

一个新四维混沌系统的电路设计与仿真

提出了一个新四维自治混沌系统,并在Multisim软件平台下对该新四维混沌系统进行电路设计与仿真,仿真结果与数值计算一致。     

具有混沌搜索策略的萤火虫优化算法

萤火虫算法是一种新颖的仿生群智能优化算法,分析了算法的仿生原理和局限,提出一种改进萤火虫局部搜索能力的优化算法。通过逻辑自映射函数产生混沌序列,引入到萤火虫算法中对精英个体进行混沌优化,同时动态收缩搜索空间以加快收敛速度。改进算法有效结合了基本萤火虫算法的局部搜索能力和混沌算法全局优化能力,对典型函数的仿真测试表明,改进算法显著提高了优化性能,在收敛速度和寻优精度方面优于基本萤火虫算法,适合复杂函数优化问题。     

Construction of Periodic Orbits and Chaos

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A Novel Concatenated Chaotic Communication System

A strategy for a novel concatenated chaotic communication system is presented. The transmitter system comprises chaotic turbo encoder and logistic CSK block in a serially concatenated form. Chaotic turbo code is capable of reducing bit error rate (BER) of the chaotic system in the AWGN channel. Through the chaotic turbo encoder, the coded sequence, which has quasi-chaotic properties, will be transmitted into the logistic CSK block. Having a very sensitive dependence on initial conditions of the map, the logistic CSK block can also be taken as the chaotic authentication method. The receiver, which has logistic demodulation block and chaotic decoder, is a linear asymptotic approximation to the inverse of the transmitter system. A chaotic iterative soft-decision decoding algorithm is also developed based on conventional maximum A posteriori decoding algorithm. At last, a two-step authentication method of this chaotic system is also presented.