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1.
频域传递函数近似方法不仅是常用的 分数阶混沌系统相轨迹的数值分析方法之一, 而且也是设计分数阶混沌系统电路的主要方法. 应用该方法首先研究了分数阶Lorenz系统的混沌特性, 通过对Lyapunov指数图、分岔图和数值仿真分析, 发现了其较为丰富的动态特性, 即当分数阶次从0.7到0.9以步长0.1变化时, 该分数阶Lorenz系统既存在混沌特性, 又存在周期特性, 从数值分析上说明了在更低维的Lorenz系统中存在着混沌现象. 然后又基于该方法和整数阶混沌电路的设计方法, 设计了一个模拟电路实现了该分数阶Lorenz系统, 电路中的电阻和电容等数值是由系统参数和频域传递函数近似确定的. 通过示波器观测到了该分数阶Lorenz系统的混沌吸引子和周期吸引子的相轨迹图, 这些电路实验结果与数值仿真分析是一致的, 进一步从物理实现上说明了其混沌特性.
关键词:
分数阶系统
Lorenz系统
分岔分析
电路实现 相似文献
2.
为了研究混沌系统的性质及其应用,采用分立元件设计并实现了单参数Lorenz混沌系统,系统参数与电路元件参数一一对应.通过调节电路中的可变电阻,观察到了该单参数系统的极限环、叉式分岔、倍周期分岔和混沌等动力学现象,以及该系统由倍周期分岔进入混沌的过程.研究了分数阶单参数Lorenz系统存在混沌的必要条件,找出了分数阶单参数Lorenz系统出现混沌的最低阶数以及最低阶数随系统参数变化的一般规律.电路仿真与电路实现研究表明,单参数Lorenz系统具有物理可实现性、丰富的动力学特性以及理论分析与实验结果的一致性. 相似文献
3.
Circuit implementation and multiform intermittency in ahyper-chaotic model extended from Lorenz system
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<正>This paper presents a non-autonomous hyper-chaotic system,which is formed by adding a periodic driving signal to a four-dimensional chaotic model extended from the Lorenz system.The resulting non-autonomous hyper-chaotic system can display any dynamic behaviour among the periodic orbits,intermittency,chaos and hyper-chaos by controlling the frequency of the periodic signal.The phenomenon has been well demonstrated by numerical simulations,bifurcation analysis and electronic circuit realization.Moreover,the system is concrete evidence for the presence of Pomeau-Manneville Type-Ⅰintermittency and crisis-induced intermittency.The emergence of a different type of intermittency is similarly subjected to the frequency of periodic forcing.By statistical analysis,power scaling laws consisting in different intermittency are obtained for the lifetime in the laminar state between burst states. 相似文献
4.
The frequency and transfer characteristics of dual element ultrasonic transducers are theoretically and experimentally investigated in the long pulse radiation mode for the case where one of the piezoelectric elements is connected to a control circuit in the form of an inductance coil or a resistor. For the controlled damper and controlled layer cases, the characteristic features of radiation as functions of the control circuit parameters are determined, as well as the conditions for an increase in ultrasonic wave radiation power. With certain conditions being satisfied, we demonstrate the possibility of amplitude modulation of the emitted ultrasonic wave by periodic switching of control circuit elements. 相似文献
5.
A. Beyer D. Köther G. Richard 《International Journal of Infrared and Millimeter Waves》1986,7(10):1429-1438
The main purpose of this paper is to develope a procedure for the computer-aided determination of the equivalent circuit of Gunn-elements. In order to determine the equivalent circuit, the Gunne-element is first measured in a test oscillator. Varying the elements of the circuit the calculated frequency and power distribution is adjusted to the measured one by means of an iterative method. The equivalent circuit of Gunn-elements obtained in this way is used for the dimensioning of Gunn-element-oscillators in the X-band in finline technique. 相似文献
6.
This Letter is concerned with the problem of fuzzy modeling and synchronization of memristor-based Lorenz circuits with memristor-based Chua?s circuits. In this Letter, a memristor-based Lorenz circuit is set up, and illustrated by phase portraits and Lyapunov exponents. Furthermore, a new fuzzy model of memristor-based Lorenz circuit is presented to simulate and synchronize with the memristor-based Chua?s circuit. Through this new fuzzy model, two main advantages can be obtained as: (1) only two linear subsystems are needed; (2) fuzzy synchronization of these two different chaotic circuits with different numbers of nonlinear terms can be achieved with only two sets of gain K. Finally, numerical simulations are used to illustrate the effectiveness of these obtained results. 相似文献
7.
Chaos in fractional-order generalized Lorenz system and its synchronization circuit simulation 总被引:1,自引:0,他引:1
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The chaotic behaviours of a fractional-order generalized Lorenz
system and its synchronization are studied in this paper. A new
electronic circuit unit to realize fractional-order operator is
proposed. According to the circuit unit, an electronic circuit is
designed to realize a 3.8-order generalized Lorenz chaotic system.
Furthermore, synchronization between two fractional-order systems is
achieved by utilizing a single-variable feedback method. Circuit
experiment simulation results verify the effectiveness of the
proposed scheme. 相似文献
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在新的四维混沌系统中数值观察到四翼混沌吸引子,然而,通过进一步分析发现,该四翼吸引子并非真实的,实际上它是上、下两个共存的双翼混沌吸引子,他们各自有独立的混沌吸引域,由于其位置靠得太近和数值误差产生的一种假象.通过引入一个线性状态反馈控制项,系统的一些相似性被破坏,受控系统能产生穿越上下吸引域界限的对角双翼混沌吸引子,进一步,随着动力学模态的演化,上下混沌吸引子与对角混沌吸引子融合成一个真正的四翼混沌吸引子.最后,通过比较该四翼混沌吸引子的系统、Lorenz系统、Chua氏电路等混沌信号的频谱发现,四翼混沌吸引子的系统信号具有极宽的频谱带宽,该特性在通讯加密等工程应用中具有重要价值.
关键词:
四维混沌系统
双翼吸引子
四翼吸引子
频谱分析 相似文献
11.
In this paper, a new numerical simulation approach is proposed for the
study of open-loop frequency response of a chaotic masking system. Using
Chua's circuit and the Lorenz system as illustrative examples, we have shown
that one can employ chaos synchronization to separate the feedback network
from a chaotic masking system, and then use numerical simulation to obtain
the open-loop synchronization response, the phase response, and the
amplitude response of a chaotic masking system. Based on the analysis of the
frequency response, we have also proved that changing the amplitude of the
exciting (input) signal within normal working domain does not influence the
frequency response of the chaotic masking system. The new numerical
simulation method developed in this paper can be extended to consider the
open-loop frequency response of other systems described by differential or
difference equations. 相似文献
12.
针对超声波电源工作时负载状态改变,换能系统产生谐振漂移的问题,提出了一种基于STM32的频率自动跟踪超声波电源的设计。电源逆变电路采用带辅助网络的全桥结构,阻抗匹配电路选择了一种改进型的T型匹配网络,应用PWM移相调功技术控制电源的输出功率,通过数字鉴相技术得到电压电流的相位差作为电路谐振状态的反馈信号,结合STM32主控制器进行PI控制,调节PWM波的输出频率使电路始终工作于谐振状态,实现了谐振频率的自动跟踪。最后基于该设计方案,实际制作了一款应用于超声波清洗仪的电源,并通过实验验证了该电源具有输出功率稳定,负载适应性强,输出频率自动跟踪等特点。 相似文献
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The Lorenz model and the antisymmetric cubic map enjoy the same discrete symmetry. A careful study of a one-dimensional bifurcation diagram ob- tained numerically from the Lorenz model reveals that the systerriatics of periodic windows is closely related to that of the cubic map. In addition, we determined the drift of the fundamental frequency and thus proposed a nomenclature for the periodic windows by associating an absolute period to each window, which in turn agrees with the corresponding word made of three letters for most of the observed periods. 相似文献
15.
Amaresh Chandra Mishra Trilochan SahooV. Srinivas Awalendra K. Thakur 《Physica B: Condensed Matter》2011,406(3):645-651
In this report, inductance spectroscopy (IS) has been used as a tool to investigate the thickness dependence of magnetoimpedance (MI) on electrodeposited NiFe thin films. An MI value as high as 140% has been observed under an applied magnetic field of 76 Oe at 300 kHz frequency for a film thickness of 6.8 μm. This result is in sharp contrast to earlier reports in literature showing monotonous increase in MI as a function of thickness. Maximum of MI was found at an optimum film thickness whose position varies with frequency. These reports exhibiting strong frequency dependence of MI prompted us to investigate the underlying physics using IS. The origin of MI lies in the combined effect of domain wall motion and spin rotation, which contributes to permeability. A parallel inductance and resistance (LR) circuit in series with series LR circuit model has been proposed as an equivalent electrical model to describe the property of these coated wires. The circuit elements have been linked with the phenomenon of domain wall motion and spin rotation. The experimental results obtained appear to be consistent with the proposed equivalent circuit model. 相似文献
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In turbulent Rayleigh–Bénard convection one seeks the relationship between the heat transport, captured by the Nusselt number, and the temperature drop across the convecting layer, captured by the Rayleigh number. In experiments, one measures the Nusselt number for a given Rayleigh number, and the question of how close that value is to the maximal transport is a key prediction of variational fluid mechanics in the form of an upper bound. The Lorenz equations have traditionally been studied as a simplified model of turbulent Rayleigh–Bénard convection, and hence it is natural to investigate their upper bounds, which has previously been done numerically and analytically, but they are not as easily accessible in an experimental context. Here we describe a specially built circuit that is the experimental analogue of the Lorenz equations and compare its output to the recently determined upper bounds of the stochastic Lorenz equations [1]. The circuit is substantially more efficient than computational solutions, and hence we can more easily examine the system. Because of offsets that appear naturally in the circuit, we are motivated to study unique bifurcation phenomena that arise as a result. Namely, for a given Rayleigh number, we find a reentrant behavior of the transport on noise amplitude and this varies with Rayleigh number passing from the homoclinic to the Hopf bifurcation. 相似文献
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Sayat N. Akhtanov Zeinulla Zh. Zhanabaev Michael A. Zaks 《Physics letters. A》2013,377(25-27):1621-1626
We report on the experimental investigation of gluing bifurcations in the analog electronic circuit which models a dynamical system of the third order: Lorenz equations with an additional quadratic nonlinearity. Variation of one of the resistances in the circuit changes the coefficient at this nonlinearity and replaces the Lorenz route to chaos by a different scenario which leads, through the sequence of homoclinic bifurcations, from periodic oscillations of the voltage to the irregular ones. Every single bifurcation “glues” in the phase space two stable periodic orbits and creates a new one, with the doubled length: a sequence of such bifurcations results in the birth of the chaotic attractor. 相似文献
20.
对于一类同时存在扩散耦合和梯度耦合的非线性振子系统, 通过空间傅里叶变换,得到具有不同波矢的各运动模式的相互独立的运动方程. 计算各横截模的Lyapunov指数, 可在耦合参数平面上确定同步混沌的稳定区域. 在稳定区域边界, 一对共轭横截模式失稳,导致同步混沌的Hopf分岔. 对耦合Lorenz振子系统进行了数值模拟,并设计了耦合Lorenz振子系统的电路, 进行耦合振子系统同步混沌Hopf分岔的电路仿真实验. 计算和仿真的结果表明,Hopf分岔的特征频率等于失稳横截模式的振荡频率.
关键词:
耦合非线性振子
同步混沌
横截模式
电路仿真 相似文献