Effect of various parameters on working of all-optical Schmitt trigger

Schmitt triggers (ST) are well known and very widely used in the field of communications and signal processing techniques. It is robust, less sensitive to noise and is a building block in analog to digital converters. This work concentrates on all-optical Schmitt trigger for the purpose of using it in the field of optical modulation and signal processing. As the size of ring lasers is small these devices are best to use on a single integrated photonic chip. In this paper various dynamic effects of a binary Schmitt trigger is simulated and discussed. Control on various properties such as size of the ring, gain of SOA of a Schmitt trigger enables one to use it in developing all-optical devices.     

Realizing reliable logic and memory function with noise-assisted Schmitt trigger circuits

Schmitt trigger is a comparator circuit with hysteresis, implemented by applying positive feedback to a noninverting input. Recently, it has been verified that noise under certain condition can help nonlinear circuit to realize reliable logical stochastic resonance (LSR). In this letter, we demonstrate that, without any modifications, Schmitt trigger can operate flexibly both as logic operation and latch operation in an optimal noise range. In traditional Schmitt trigger, the hysteresis is designed for resisting noise. In the new design, the hysteresis tends to enhance the LSR effect in Schmitt trigger with the help of noise and helps the system to perform better at higher noise levels. Thus, our results extend the application scope and generality of the traditional Schmitt trigger.     

Dynamic memory arrays and chaos in a spatial-light-modulator ring circuit

An optical ring circuit with two spatial light modulators is capable of supporting a variety of nonlinear spatio-temporal dynamics, including an array of bistable spots with novel Trigger-type flip-flop operation.     

改进蔡氏混沌电路的实现

设计了改进型的蔡氏电路装置.用Multisim软件对改进电路进行仿真实验后,搭建了此电路系统的装置.通过改变参数,得到了系统一周期、二周期、四周期到混沌的时间序列和二维相空间重构图,从而得到了丰富的混沌行为.     

Electronic circuit implementation of chaos synchronization

In this paper, an electronic circuit implementation of a robustly chaotic two-dimensional map is presented. Two such electronic circuits are realized. One of the circuits is configured as the driver and the other circuit is configured as the driven system. Synchronization of chaos between the driver and the driven system is demonstrated.     

Multiple time scale based reduction scheme for nonlinear chemical dynamics

A chemical reaction is often characterized by multiple time scales governing the kinetics of reactants, products and intermediates. We eliminate the fast relaxing intermediates in autocatalytic reaction by transforming the original system into a new one in which the linearized part is diagonal. This allows us to reduce the dynamical system by identifying the associated time scales and subsequent adiabatic elimination of the fast modes. It has been shown that the reduced system sustains the robust qualitative signatures of the original system and at times the generic form of the return map for the chaotic system from which complex dynamics stems out in the original system can be identified. We illustrate the scheme for a three-variable cubic autocatalytic reaction and four-variable peroxidase-oxidase reaction.     

Multiple time scale analysis of two models for the peroxidase-oxidase reaction

A multiple time scale analysis of two four-variable models of the peroxidase-oxidase reaction, the DOP, and the Olsen model, is carried out. It is shown that autonomous limit cycle oscillations are exhibited by the fast subsets of these two models, but only in certain regions of parameter space, confirming the prior suggestion that the slow variable (NADH) is not essential for oscillatory behavior. However, it is found that the slow variable is essential for oscillatory behavior over other ranges of parameter values, and is always essential for complex oscillatory and chaotic behavior. This latter conclusion is based on a study involving driving the fast subset with a sinusoidally varying (NADH). This study suggests the level of coupling between fast and slow variables of an autonomous system necessary to cause the chaos observed in the DOP model. Further study of the driven system allows for the identification of a natural period of the nonoscillatory but bistable fast subsystem and a set of rules for applying a parametric driving in such a way as to generate a more complete Farey sequence from a truncated Farey sequence. These conclusions are used to compare the very similar DOP and Olsen models, which, nevertheless, exhibit quite different Farey sequences and routes to chaos. (c) 1995 American Institute of Physics.     

变型蔡氏电路中混沌控制的实验研究

将变型蔡氏电路与线性二阶电路相耦合．进行线性二阶电路对变型蔡氏电路非反馈混沌控制的实验研究．实验结果表明：变型蔡氏电路比蔡氏电路具有更强的鲁棒性，更易实现混沌控制．     

Demonstration of a chaos generator with two time delays

We demonstrate a chaos generator involving two time delays and two nonlinear functions. Dynamic behaviors are numerically and experimentally observed. The complexity of the dynamics is discussed in terms of Lyapunov exponents and dimensions. The setup can provide a new architecture for enhancing message security in chaos encryption systems.     

Fractional q-Calculus on a time scale

Abstract

The study of fractional q-calculus in this paper serves as a bridge between the fractional q-calculus in the literature and the fractional q-calculus on a time scale , where to ∈ ? and 0 < q < 1. By use of time scale calculus notation, we find the proof of many results more straight forward. We shall develop some properties of fractional q-calculus, we shall develop some properties of a q-Laplace transform, and then we shall employ the q-Laplace transform to solve fractional q-difference equations.     

Characteristic modes and the transition to chaos of a resonant Josephson circuit

The periodic modes of a voltage-driven resonant small-junction Josephson circuit are studied by accurate numerical methods starting from large dissipation. As dissipation decreases, sections of the average current vs. voltage characteristic become unstable and new branches develop on those sections, corresponding to new modes which are exact subharmonics of the old mode. For low enough dissipation chaotic ranges of voltage occur, i.e., ranges with no stable periodic modes. This circuit is a component of many experimental circuits, e.g., finite junctions, DC and RF squids, etc., and so the behavior found here should occur widely.     

永磁同步电机的混沌分析及其电路实现

作为一个非线性动力学系统,在一定参数范围和外部输入下永磁同步电机可以呈现非常复杂的混沌运动或极限环,其混沌特性较为显著.在永磁同步电机的非线性数学模型基础上,分析其分叉图、Lyapunov指数图谱和平衡点性质等非线性运动特性,并通过数字仿真得到验证.最后基于该模型设计了相应的模拟电路,实验结果和数字仿真一致. 关键词： 永磁同步电机 混沌 分形分析 电路实现     

带陡化间隙的触发真空开关触发源研制

针对主电极间距20 mm以上的沿面击穿型多棒极触发真空开关（TVS）,研制了开关触发源。触发源利用脉冲变压器产生脉冲高压输出,在脉冲变压器高压侧并联小容值电容并在电容后串联陡化间隙。陡化间隙的加入可以使触发源输出不受触发沿面金属蒸气沉积的影响。通过调节间隙击穿电压也可以提高电容充电电压及储存能量,从而增加TVS触发沿面被击穿时注入到其中的触发能量。使用该触发源对TVS进行导通实验,结果表明,加入陡化间隙后的触发源输出能量大幅提高且不受触发沿面金属蒸气沉积的影响,能够实现TVS的100%可靠导通。     

带陡化间隙的触发真空开关触发源研制北大核心CSCD

针对主电极间距20mm以上的沿面击穿型多棒极触发真空开关(TVS),研制了开关触发源。触发源利用脉冲变压器产生脉冲高压输出,在脉冲变压器高压侧并联小容值电容并在电容后串联陡化间隙。陡化间隙的加入可以使触发源输出不受触发沿面金属蒸气沉积的影响。通过调节间隙击穿电压也可以提高电容充电电压及储存能量,从而增加TVS触发沿面被击穿时注入到其中的触发能量。使用该触发源对TVS进行导通实验,结果表明,加入陡化间隙后的触发源输出能量大幅提高且不受触发沿面金属蒸气沉积的影响,能够实现TVS的100%可靠导通。     

大规模富社团网络的时空混沌同步

以Plankton时空混沌系统作为网络节点,通过非线性耦合构成富社团(rich-club,RC)网络,研究其时空混沌同步规律.首先给出了RC网络中连接节点之间的非线性耦合函数的一般性选取原则.进而基于Lyapunov稳定性定理,理论分析了实现网络同步的条件.最后,通过仿真模拟检验了网络的时空混沌同步效果.仿真研究表明,RC网络中各富节点之间以及这些富节点各自星形连接的子网络中的所有节点均实现了完全同步。     

Controlling and synchronizing space time chaos

Control and synchronization of continuous space-extended systems is realized by means of a finite number of local tiny perturbations. The perturbations are selected by an adaptive technique, and they are able to restore each of the independent unstable patterns present within a space time chaotic regime, as well as to synchronize two space time chaotic states. The effectiveness of the method and the robustness against external noise is demonstrated for the amplitude and phase turbulent regimes of the one-dimensional complex Ginzburg-Landau equation. The problem of the minimum number of local perturbations necessary to achieve control is discussed as compared with the number of independent spatial correlation lengths.     

一类关联混沌系统的分时切换混沌同步

提出关联混沌系统分时切换混沌同步的思想.利用线性反馈控制方法实现一类关联混沌系统中各个子系统与其复制系统间的分时切换混沌同步.根据时变系统的稳定性理论，得到了使各子系统都能实现混沌同步的反馈控制增益的取值范围.数值仿真实验证明了理论分析的正确性和可行性.     

一类关联混沌系统的分时切换混沌同步

提出关联混沌系统分时切换混沌同步的思想.利用线性反馈控制方法实现一类关联混沌系统中各个子系统与其复制系统间的分时切换混沌同步.根据时变系统的稳定性理论,得到了使各子系统都能实现混沌同步的反馈控制增益的取值范围.数值仿真实验证明了理论分析的正确性和可行性. 关键词： 分时切换混沌同步 线性反馈 关联混沌系统     

Relaxation time of a chiral quantum R-L circuit

We report on the GHz complex admittance of a chiral one-dimensional ballistic conductor formed by edge states in the quantum Hall regime. The circuit consists of a wide Hall bar (the inductor L) in series with a tunable resistor (R) formed by a quantum point contact. Electron interactions between edges are screened by a pair of side gates. Conductance steps are observed on both real and imaginary parts of the admittance. Remarkably, the phase of the admittance is transmission independent. This shows that the relaxation time of a chiral R -L circuit is resistance independent. A current and charge conserving scattering theory is presented that accounts for this observation with a relaxation time given by the electronic transit time in the circuit.