Chen系统和一类统一混沌系统的同步控制

本文利用Lyapunov方法讨论了Chen系统的同步问题以及一类包含Chen系统与Lorenz系统的统一混沌系统的同步问题，所构造的状态反馈同步控制器仅需要一个状态变量，并进行了数值模拟。     

新型多翼统一混沌系统

通过引入多个线性状态反馈控制项和非线性状态反馈控制项,提出了一个新型多翼统一混沌系统。在不同的系统参数下均能产生关于原点对称的真实四翼混沌吸引子,还能产生蝴蝶吸引子、蝙蝠形吸引子和新型多翼混沌吸引子。采用常规的动力学分析方法研究了产生新型多翼混沌吸引子系统的基本动力学特性,例如相图、耗散性分析、李雅普诺夫指数谱和分岔图。结果表明系统可以产生丰富的混沌行为,该新型多翼混沌吸引子可以随参数的变化实现关于x轴对称的双翼混沌吸引子和关于原点对称的真实四翼混沌吸引子。     

单参数统一混沌系统的自适应控制同步

研究了单参数统一混沌系统的同步问题,提出了参数自适应控制同步方法;通过构造适当的控制函数和设计参数的自适应控制律,实现了两个不同参数的统一混沌系统的同步;根据Lyapunov稳定性定理,导出了两不同参数混沌系统能实现同步的充分条件,无论驱动系统处于何种状态,该方法都可使响应系统按照驱动系统给定的轨道演化。数值仿真表明了该方法的有效性。     

Novel unified chaotic system with multi-parameter invariable Lyapunov exponent spectrum

Based on the traditional Qi chaotic system,a novel unified chaotic system with the complex chaotic characteristics was constructed by adding the control parameters and modifying the nonlinear terms.Firstly,basic dynamical characteristics of chaotic system were analyzed,and phase portrait,time domain waveform diagram,Poincare mapping and power spectrum diagram were numerically simulated.Secondly,system parameters influence on chaotic system was discussed through Lyapunov exponent spectrum,bifurcation diagrams and chaotic signal amplitude.It was found that the unified chaotic system can generate the four new types of two-wing chaotic attractors with the multi-parameter invariable Lyapunov exponent spectrum characteristics.Meanwhile,there exist the functions of the global and local nonlinear amplitude modulation parameters.Thirdly,taking the first chaotic attractor of system as an example by introducing the two new types of nonlinear functions,the expansion of grid multi-wing attractor was realized.Finally,the hardware circuit of novel unified chaotic system was constructed.The four new types of chaotic attractors are observed experimentally,which is consistent with numerical simulation results and verified the feasibility of the proposed system.     

具有噪声扰动的统一混沌系统的同步控制

研究了一类具有噪声扰动的统一混沌系统的同步控制问题。基于滑模变结构控制理论,提出了利用不确定性观测器估计扰动噪声,用噪声的观测值来设计控制器的新方法,而且适当选取观测器反馈增益可以使观测误差充分的小,从而可得到几乎没有受到扰动时的控制效果。和常规滑模变结构控制方法相比,所设计的控制器既能有效地抑制抖振,又能降低控制器参数设计的保守性。最后,基于Matlab 6.5软件对Lorenz混沌系统进行分析和数值模拟,验证了该滑模控制方法在混沌同步中的优良性能。     

基于超稳定性理论的统一混沌系统的混合同步

研究了统一混沌系统的混合同步问题。利用超稳定性理论，给具有扇形有界输入、有界参数和有界外部扰动的统一混沌系统设计了一个混合同步控制方案。所提方案对非线性输入和扰动都是稳定的，数值仿真说明了它的有效性。     

基于径向基函数神经网络的混沌系统控制

考虑到不同神经网络模型误差对混沌控制效果的影响，提出了采用一种改进的递阶遗传算法对径向基函数（RBF）神经网络进行训练，针对连续的Lorenz系统进行了仿真，并且与其它神经网络训练算法结果进行了比较，仿真结果证明所采用的训练算法具有更加理想的混沌控制效果。     

一种新的混沌方程及其超混沌网络模型

考虑器件实现方面的简单性,提出一种新的混沌方程模型,并通过单向耦合法构成超混沌网络。通过微机模拟表明网络具有丰富的混沌、超混沌现象。进而在单向耦合法基础上,提出参数耦合法,利用此方法,构造成的二维混沌网络具有超混沌动力学特性。网络具有高效、灵活、易于器件实现的特点。这种新的混沌方程及超混沌网络模型可望在提高激光器的输出功率、保密通信等领域获得广泛应用     

基于统一混沌系统的参数调制新方法

本文提出一种基于统一参数混沌系统的参数调制新方法.该方法根据统一参数混沌系统的特点,在发送端,用数字信息连续调制统一混沌系统的一个参数,使混沌系统的吸引子不断变化,数字信息信号直接隐藏在混沌系统的状态变量中.信道中传输混沌系统的状态变量.在接收端,对接收到的混沌状态变量进行间歇采样,并与接收端的混沌系统的状态变量进行误...     

Electronic simulation and microcontroller real implementation of an autonomous chaotic and hyperchaotic system made of a Colpitts-Josephson junction like circuit

Most of the simple Josephson junction (JJ) based circuits with chaotic behavior found in the literature are nonautonomous. Hyperchaotic JJ-based circuits are often either driven by an external force or result from coupling chaotic circuits. An autonomous simple circuit based on Josephson junction active element (JJ), with exactly three physical energy storage tanks, is proposed and analyzed in this paper. This Colpitts-like CLC circuit, though operating at low frequencies, can generate hyperchaotic signals when its nonlinear element is a resistive–capacitive–inductance shunted junction (LRCLSJ) model. Two equilibrium points are found, and their stability analysis is investigated. The proposed circuit displays Hopf bifurcation, periodic oscillations, chaotic and hyperchaotic attractors. The electronic implementation of the proposed circuit using OrCAD-PSpice software is presented to confront the numerical simulations results. A good qualitative agreement is revealed by comparing the analog and numerical simulations results. At last, the microcontroller real implementation is presented using Arduino UNO board. The results obtained are in good agreement with the numerical simulation results.

     

文氏桥超混沌电路时滞反馈混沌控制

混沌镇定控制的应用范围很广,所采用的方法很多。本文研究了文氏桥超混沌电路的时滞反馈混沌镇定控制方法,利用模拟时滞反馈控制器将系统状态变量延时后接入原系统,实现了运行状态从超混沌态到单周期态的转变。设计了时滞反馈控制器电路,并进行了平衡点稳定性分析。电路实验结果验证了数值仿真结果,说明了时滞反馈控制器可以有效实现超混沌电路的混沌镇定控制。     

超混沌视频加密系统的FPGA设计与实现

随着多媒体技术的不断发展,视频信息安全愈发受到人们的关注。为解决视频信息的安全问题,提出了一种基于现场可编程门阵列(FPGA)技术的超混沌视频加密方法。在加密过程中,一方面FPGA控制数字摄像头实现实时彩色视频信息的采集;另一方面,在计算机密钥指令下,利用FPGA使超混沌系统产生有效的伪随机序列,实现对所采集视频信息的数据和地址的双重超混沌加密。给出了具体的超混沌视频加密算法和设计流程以及FPGA实现结果。安全性分析表明,明密文主观视觉对比显著不同,密钥空间大,视频图像统计特性的相关性弱,说明基于FPGA的超混沌视频加密系统加密效果良好可靠。     

基于Lorenz超混沌系统模糊渐近同步的保密通信系统

研究了一种基于Lorenz超混沌系统渐近同步的保密通信系统设计方法。首先采用T-S模糊模型对Lorenz超混沌系统进行精确描述,进而基于模糊混沌同步理论,利用Lorenz超混沌系统设计信号发射器和接收器,实现混沌保密通信。最后利用Matlab软件进行仿真研究。     

Design and experimental confirmation of a novel switched hyperchaotic system

To generate complex pseudo-noise (PN) sequences for chaos-based communications, this article presents a novel switched hyperchaotic model, which is constructed based on a modified Chen system by introducing a dynamical controller. The system consists of two different hyperchaotic subsystems and can change its behavior randomly via a switching function. Basic dynamical behaviors of the hyperchaotic system are further investigated. Furthermore, the switched system is confirmed by its positive Lyapunov exponents and laboratory measurements by an electronic circuit.     

四翼超混沌系统的动力学特性分析及其电路实现

为了提高混沌系统的复杂性,本文基于最新提出的简化Lorenz系统,采用正弦函数扰动方法和非奇异变换,设计了一个具有四翼吸引子结构的超混沌系统。通过计算Lyapunov指数、分岔图、相图和Poincaré截面等方法分析了该系统的动力学特性,分析表明该系统具有丰富的动力学行为。采用分立元件,设计了该系统的模拟电路,电路实验结果与数值仿真结果相吻合,为构建具有高性能的混沌保密通信系统奠定了基础。     

一个新的四维超混沌系统的动力学分析及混沌反同步

提出了一个新的四维Chen-Qi-like混沌系统.通过计算该系统的时间序列的Lyapunov指数谱、Lyapunov 维数、分岔图、Poincaré截面图等分析了控制参数变化时,系统的非线性动力学特征.结果表明该新系统不但和Chen-Qi 系统族有类似的性质,而且又呈现不同的非线性特征.在微分方程不变性原理基础上,运...     

A unified multimedia database system to support telemedicine

A unified approach to managing multimedia medical databases in a telemedicine system is proposed. In order to manage, search, and display patient information more efficiently, we define a patient information package (PIP) as a concise data set of a patient's medical information from each visit. By means of PIPs, both patient-oriented and problem-oriented query strategies, which are most frequently used in daily clinical practice and medical education, can be accommodated. We also provide a unified methodology for accessing various types of patient medical records as well as design two types of user interfaces, high-quality data display and web-based interface, for different medical service purposes. The PIP-based management of databases has been successfully implemented between the National Taiwan University (NTUH), Taipei, and the Chinshan health care center, Chinshan, Taiwan, for teleconsultation, telediagnosis, and tele-education     

一个超混沌Lorenz系统设计与FPGA电路实现

采用增加并改变系统非线性特性的方法对Lorenz系统进行变形,在此基础上,通过在三阶Lorenz系统中引入一个外加的状态变量构造了一个新的超混沌系统;对系统的一些基本特性,如耗散性、平衡点、稳定性进行了详细分析,系统超混沌的存在性通过Lyapunov指数谱得到了验证。还设计了一个数字电路进行实验,从电路实验中观察到了各种超混沌吸引子。     

Controlling chaotic behavior of heavy to light hole mixingtunneling by external electric fields

Oscillatory and chaotic motion of heavy to light hole mixing tunneling in asymmetric coupled quantum-well structures can be controlled by an external electric field. Chaotic behavior occurs if the heavy-hole state in the first well is aligned with the light-hole state in the second well under a significant in-plane vector k_∥. Oscillatory motion is recovered if the external electric field disrupts the alignment between the heavy-hole state in the first well and the light-hole state in the second well     

A no-equilibrium memristive system with four-wing hyperchaotic attractor

A new memristive system is proposed in this paper which can have no equilibrium and a line of equilibrium based on the value of its controlling parameter. Also, changing that parameter can cause the system having both chaotic and hyperchaotic solutions. This system has a multi-wing strange attractor. Dynamical properties of this system such as Lyapunov exponents and bifurcation diagram are calculated. This system belongs to the category of systems with hidden and multistable attractors. A system with all the above-mentioned properties is not common in the literature. Finally, an adaptive sliding mode control method is applied to synchronize this chaotic system.