Stochastic resonance in a bistable magnetic system

Theoretical model of magnetostochastic resonance is developed. It is shown that in the presence of noise the signal-to-noise ratio for a bistable uniaxial ferromagnetic can be a million times greater than that for a one-stable ferromagnetic. The phenomenon can be used for magnetic field measurements, detection of macroscopic quantum tunneling of magnetization and investigation of electron tunneling that depends upon magnetization     

Stochastic resonance in a bistable system driven by a chaotic signal

The behavior of a bistable oscillator under the action of a chaotic signal from a Rössler oscillator with a spiral attractor is considered. The influence of the width of the main spectral line of the chaotic drive signal on the signal to noise ratio at the response system’s output has been studied.     

Deterministic stochastic resonance in a bistable semiconductor system

The phenomenon of deterministic stochastic resonance has been experimentally observed and studied for the first time in a bistable semiconductor system with an S-shaped current-voltage characteristic exhibiting a transition to chaos via intermittency. Spectral regions featuring amplification of an external signal and phase locking are determined as dependent on the frequency and amplitude of the external signal and the control parameter.     

Stochastic transitions in a bistable reaction system on the membrane

Transitions between steady states of a multi-stable stochastic system in the perfectly mixed chemical reactor are possible only because of stochastic switching. In realistic cellular conditions, where diffusion is limited, transitions between steady states can also follow from the propagation of travelling waves. Here, we study the interplay between the two modes of transition for a prototype bistable system of kinase–phosphatase interactions on the plasma membrane. Within microscopic kinetic Monte Carlo simulations on the hexagonal lattice, we observed that for finite diffusion the behaviour of the spatially extended system differs qualitatively from the behaviour of the same system in the well-mixed regime. Even when a small isolated subcompartment remains mostly inactive, the chemical travelling wave may propagate, leading to the activation of a larger compartment. The activating wave can be induced after a small subdomain is activated as a result of a stochastic fluctuation. Such a spontaneous onset of activity is radically more probable in subdomains characterized by slower diffusion. Our results show that a local immobilization of substrates can lead to the global activation of membrane proteins by the mechanism that involves stochastic fluctuations followed by the propagation of a semi-deterministic travelling wave.     

非线性耦合双稳系统的振动共振与随机共振

单一双稳系统受到弱周期信号和噪声的作用能产生随机共振.而在高、低两种不同频率信号作用下则能产生振动共振,将两个双稳系统经非线性耦合而成为耦合双稳系统,并在低频、高频信号和噪声的作用下研究了耦合双稳系统对低频信号的响应特性,给出了高频信号参数和耦合系数对振动共振和随机共振的影响关系,结果表明通过调节高频信号幅值或耦合系数大小能产生振动共振或随机共振,并构建了耦合双稳系统原理框图,为随机共振的控制及其利用提供了新的理论方法,数值仿真结果与理论分析结论完全吻合.     

耦合双稳系统随机共振的轴承故障检测方法

耦合双稳系统由两个双稳系统经非线性方式耦合而成.分析了影响耦合双稳系统随机共振产生的Kramers逃逸率及平均跃迁频率与耦合系数的关系,提出了通过调节耦合系数大小来产生和增强随机共振的方法,并将该方法应用于轴承故障信号检测中.数值仿真和实验结果表明,在系统参数固定时,调节耦合系数能增强系统输出功率谱在特征频率处的谱值,可检测出单一双稳系统随机共振所不能检测出的微弱轴承故障信号频率,该方法在轴承故障信号检测中的应用是有效的.     

随机参数诱导交流积分器中的随机共振研究

研究了具有随机参数的交流积分器中的随机共振现象。基于线性系统理论,得到了系统输出信噪比的表达式。研究发现,输出信噪比是噪声强度、噪声相关率以及系统参数的非单调函数。信噪比随着激励信号频率的增大而增大,随着信号直流分量的增大而减小。     

Stochastic resonance of a multi-stable system and its application in bearing fault diagnosis

This paper investigates the stochastic resonance and mean-first passage time of a quad-stable potential in the presence of Gaussian white noise and periodic forcing. The analytical expressions of mean-first passage time and spectral amplification are obtained, respectively. It is found that even small noise intensity can lead to noise-assisted hopping between two adjacent potential wells for the case of small damping coefficient. For large noise intensity, the escape process of Brownian particles is accelerated in an underdamped nonlinear system. Moreover, the curve of spectral amplification displays a typical resonant peak at an optimal noise intensity, suggesting the onset of stochastic resonance. Meanwhile, with the decrease of periodic signal frequency, the peak value of spectral amplification is enhanced. Especially, an optimal quad-stable potential structure exists to maximize the stochastic resonance effect. The proposed multi-stable stochastic resonance method is applied to the fault diagnosis of inner and outer race bearing, and the quantum particle swarm optimization algorithm is used to optimize the system parameters and damping coefficient. The good agreement between fault frequency and theoretical value validates efficiency of the proposed method. Compared with the overdamped tri-stable stochastic resonance method, the performance of fault diagnosis is enhanced substantially by the proposed method.     

无理式系统的主共振分岔分析

研究了一类无理式系统的主共振分岔。该系统为一连杆系统模型,其动力学行为取决于光滑参数 ,当 时,其为正刚度系统;当 时,其为负刚度系统;当 时,其为线性系统。当 逐渐增加时,系统从弱非线性系统变成强非线性系统。研究结果表明,无理式系统的性质和多项式系统的性质是不同的。最后采用奇异性理论分析了共振解的演化过程     

Multiple surface-plasmon resonance in uniform-waist tapered optical fibers with an asymmetric double-layer deposition

Novel devices consisting of uniform-waist tapered optical fibers with asymmetric double-layer (metal plus dielectric) depositions have been recently proposed as refractive-index sensors. We study the properties of light transmission by use of this kind of devices, and we specifically perform a detailed study of the generation of surface-plasma waves in the structures. We show that multiple surface plasmons are excited for specific combinations of the constructive parameters of the devices and for specific ranges of the refractive index of the surrounding medium. The behavior also depends on the wavelength and the state of polarization of the incident light. The use of uniform-waist tapers allows for control of constructive parameters and an increase in the interaction length with the outer medium. We show how the plasmons are excited in the region of the taper waist by a coupling with the cladding modes guided in that area. This characterization shows the importance of the presence of a dielectric layer for selection of the operating range of the device. The results are useful for the design of new sensors.     

Saturation in asymmetric structures under internal resonance

In this paper, a novel model for a single-storey irregular-plan building, subjected to earthquake and harmonic translational excitation, is presented to consider non-linear inertial coupling terms, which are ignored in conventional linear models. Furthermore, the effect of internal resonance is investigated. The governing equations of motion for a model of this type of structure are achieved in a non-inertial rotational system of reference, attached to the centre of mass of the rigid diaphragm of its floor. Non-linearities are caused by non-linear inertial coupled lateral and torsional responses. Using the method of multiple scales, the non-linear equations are reduced to approximate linear equations, and subsequently the dynamic stability of the steady-state responses near a two-to-one ratio of internal resonant conditions is studied. The difference between the responses of the proposed non-linear model and the conventional linear one is shown in time history and frequency domain analyses. By inspecting the effects of amplitude and frequency detuning parameters in the responses, some non-linear phenomena, such as saturation, hysteretic and jumping, are observed.     

Stochastic resonance in a tunnel diode circuit

An experiment on the stochastic resonance in a bistable circuit with a tunnel diode is reported. In contrast to previous studies, the signal-to-noise ratio was measured across the load resistance. An additional narrow peak is observed in the signal-to-noise ratio plotted as function of the noise intensity. A brief explanation of the effect is given.     

Phase synchronization of switching processes in a stochastic bistable system with an aperiodic external influence

The synchronization of switching in a stochastic bistable system perturbed by a chaotic signal is analyzed. The effect is described in terms of the classical theory of phase synchronization. Pis’ma Zh. Tekh. Fiz. 24, 14–21 (September 26, 1998)     

基于级联双稳随机共振和多重分形的机械故障诊断方法研究

对级联双稳随机共振的滤波特性进行了对比和分析,利用这种特性,结合广义维数对信号非线性特征的度量能力,提出了基于级联双稳随机共振和多重分形的机械故障诊断方法。实验结果证明,该方法可以有效的消除高频噪声,增强低频段信号的能量,由此得到的分形维数比较准确,能够更加精确地度量机械振动信号的非线性特征,从而达到机械故障诊断的目的。     

外加周期信号控制下的随机共振及其应用

分析了双稳系统的Kramers逃逸率与外加周期信号参数的关系,揭示了外加周期信号通过调节Kramers逃逸率影响微弱周期信号的随机共振效应,从而人为地产生或增强随机共振,实现随机共振的有效控制.数值仿真和实验结果表明,外加周期信号控制下的随机共振,可以增强双稳系统输出功率谱在微弱周期信号频率处的谱值,检测出强噪声中的微弱信号,在涡街频率检测方面的应用是可行和有效的.     

相关偏置信号调制噪声和加性噪声驱动线性系统随机共振

研究了偏置信号调制噪声和加性噪声驱动线性系统的随机共振现象。根据线性系统理论,得到了系统输出信噪比的精确表达式。研究结果表明：系统输出信噪比是系统衰减常数、调制信号偏置参数、信号调制噪声强度和加性噪声强度的非单调函数。同时,系统输出信噪比随两种噪声的相关强度成非单调关系。     

Stochastic response of an exponentially hysteretic system through stochastic averaging

A method of predicting the response of randomly excited nonlinear systems, with nonlinearity both in damping and stiffness is presented. The method is based upon the stochastic average technique which is a generalization of the Krylov Bogoliubov deterministic averaging technique. The practical usefulness of the method is established through its application to the Bouc exponentially hysteretic model. It is observed that while the exponentially hysteretic system has some features in common with the bilinear hysteretical system, it also has some remarkable differences.     

空调双稳态四通阀性能匹配测试系统

设计了一套空调用双稳态四通阀性能匹配测试系统,该系统可测试直流双稳态四通阀和交流双稳态四通阀.其主要功能是实现对双稳态四通阀的驱动与控制,同时对四通阀线圈电阻、外接电阻、线圈工作电压和电流等匹配参数进行实时测量与分析.结果表明,该测试系统很好地实现了对双稳态四通阀各项性能指标的测量,以及对故障的初步判别,具有结构简单,工作可靠,使用方便,测量精度高等特点.     

Longitudinal multidomain structures formed in an optically bistable system under the action of a collimated annular beam

Several longitudinal domains may form under the action of a collimated annular beam propagating in an optically bistable cavity-free system. The computer simulation of this phenomenon indicates two possible pathways for the domain formation process.