Large deviation properties of on-off intermittency

The large deviation property of on-off intermittency is investigated by introducing a two-dimensional piecewise linear map, which can be mapped to an infinite Markov chain. It is shown that nonanalyticity, in the q-weighted average of the portion of time spent in burst state, appears as a second-order phase transition for an interval of control parameter with the bifurcation point of on-off intermittency as its end point.     

Hypersensitivity to weak ac signals induced by colored multiplicative noise in a system with on-off intermittency

An experimental study is made of the effect of the finite correlation time of controlling multiplicative noise on the hypersensitivity to weak ac signals in systems with on-off intermittency. It is shown that the gain has a maximum for an optimal choice of correlation time and intensity of the controlling noise. Zh. éksp. Teor. Fiz. 116, 1477–1483 (October 1999)     

Generation of on-off intermittency based on RSssler chaotic system

In this paper, one-state on-off intermittency and two-state on-off intermittency are generated in two five- dimensional continuum systems respectively. In each system, a two-dimensional subsystem is driven by the Rossler chaotic system. The parameter conditions under which the on-off intermittency occurs are discussed in detail. The statistical property of the intermittency is investigated. It is shown that the distribution of the laminar phase duration time follows a power law with an exponent of -3/2, which is a signature of on-off intermittency. Moreover, the phenomenon of intermingled basins is observed when attractors in the two symmetric invariant subspaces are stable. We provide an effective way to generate on-off intermittency based on a chaotic system, which is important for application and theoretical study.     

Type-I intermittency with noise versus eyelet intermittency

In this Letter we compare the characteristics of two types of the intermittent behavior (type-I intermittency in the presence of noise and eyelet intermittency taking place in the vicinity of the chaotic phase synchronization boundary) supposed hitherto to be different phenomena. We show that these effects are the same type of dynamics observed under different conditions. The correctness of our conclusion is confirmed by the consideration of different sample systems, such as quadratic map, Van der Pol oscillator and Rössler system. Consideration of the problem concerning the upper boundary of the intermittent behavior also confirms the validity of the statement on the equivalence of type-I intermittency in the presence of noise and eyelet intermittency observed in the onset of phase synchronization.     

Coherent noise, scale invariance and intermittency in large systems

We introduce a new class of models in which a large number of “agents” organize under the influence of an externally imposed coherent noise. The model shows reorganization events whose size distribution closely follows a power law over many decades, even in the case where the agents do not interact with each other. In addition, the system displays “aftershock” events in which large disturbances are followed by a string of others at times which are distributed according to a t⁻¹ law. We also find that the lifetimes of the agents in the system possess a power-law distribution. We explain all these results using an approximate analytic treatment of the dynamics and discuss a number of variations on the basic model relevant to the study of particular physical systems.     

Experimental observation of noise-induced sensitivity to small signals in a system with on-off intermittency

An experimental (electronic circuit) realization and analytic studies of overdamped Kramers oscillator with an exponential nonlinearity under combined effect of a large multiplicative noise and a small periodic signal were performed. Under certain conditions, when the system exhibits on-off intermittency, it becomes sensitive to very small periodic signals, amplifying them greatly. Received 21 May 1999 and Received in final form 28 December 1999     

Low-frequency noise of an LSA generator

A model of the low-frequency fluctuations of the oscillations of an LSA generator produced by accumulation and distribution of space-charge perturbations which occur at local micrononuniformities in the structure of the working region of a Gunn diode is proposed. Flicker fluctuations of the parameters of the nonuniformities are regarded as the primary source of noise. Expressions are obtained for the power spectra of the amplitude-frequency noise of the output signal. The dependence of the noise level on the bias field applied to the diode is analyzed and numerical estimates are given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 27, No. 1, pp. 79–86, January, 1984.     

Type-II intermittency characteristics in the presence of noise

We consider a type of intermittent behavior that occurs as the result of the interplay between dynamical mechanisms giving rise to type-II intermittency and random dynamics. We analytically deduce the law for the distribution of the laminar phases, which has never been obtained hitherto. The already known dependence of the mean length of the laminar phases on the criticality parameter [Phys. Rev. E 68, 036203 (2003)] follows as a corollary of the carried out research. We also prove that this dependence obtained earlier under the assumption of the fixed form of the reinjection probability does not depend on the relaminarization properties, and, correspondingly, the obtained expression of the mean length of the laminar phases on the criticality parameter remains correct for different types of the reinjection probability.     

Low-frequency noise from large wind turbines

As wind turbines get larger, worries have emerged that the turbine noise would move down in frequency and that the low-frequency noise would cause annoyance for the neighbors. The noise emission from 48 wind turbines with nominal electric power up to 3.6 MW is analyzed and discussed. The relative amount of low-frequency noise is higher for large turbines (2.3-3.6 MW) than for small turbines (≤ 2 MW), and the difference is statistically significant. The difference can also be expressed as a downward shift of the spectrum of approximately one-third of an octave. A further shift of similar size is suggested for future turbines in the 10-MW range. Due to the air absorption, the higher low-frequency content becomes even more pronounced, when sound pressure levels in relevant neighbor distances are considered. Even when A-weighted levels are considered, a substantial part of the noise is at low frequencies, and for several of the investigated large turbines, the one-third-octave band with the highest level is at or below 250 Hz. It is thus beyond any doubt that the low-frequency part of the spectrum plays an important role in the noise at the neighbors.     

Low-frequency noise in Schottky-gate field-effect transistors

A three-section analytic model of a Schottky-gate field-effect transistor is used to calculate the drain-current modulation sensitivity to low-frequency fluctuations in various regions of the active layer. The examined noise sources in the conducting channel and in the gate depletion region are fluctuations of the carrier and bound-charge concentrations, whose spectra can include generation-recombination and flicker components. The theoretical results are compared with measurements of low-frequency current noise.Presented at All-Union Coordinating Conference Low-Frequency Noise in Semiconductor Devices (Chernogolovka, Moscow Region, June, 1991).St. Petersburg State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 12, pp. 1118–1127, December, 1993.     

Low-frequency wind noise correlation in microphone arrays

A three-axis orthogonal microphone array with ten sensors in each arm has been used to study wind noise in the frequency range from 0.05 to 50 Hz. Simultaneous measurements were made of the three components of the varying wind velocity. Measurements have been made for wind speeds from 4 to 7 m/s at three different sites. The frequency-dependent correlation of the wind noise over a range of wind velocities and atmospheric and environmental conditions in the downwind direction varies as exp(-3.2X)cos(27piX). For the crosswind and vertical directions, the correlation decays approximately as exp(-7Y), where X is the separation in wavelengths in the downwind direction and Y is this separation in the crosswind or vertical direction. Over a limited range of wave numbers, the power density spectra of the varying wind velocity varied as the wave number to the -(5/3) power and the pressure spectra as the -(7/3) power.     

Low-frequency noise of Gunn-oscillator first and second harmonics

The low-frequency modulation noise of a Gunn oscillator is analyzed assuming that the diode ac voltage contains the first and second harmonics. The requirements for stable operation with allowance for the mutual effect of the harmonics are examined. It is shown that the procedure for determination of external Q according to frequency pulling is not applicable to such an oscillator. The fluctuational characteristics of a Gunn oscillator with outputs at the first and second harmonics are investigated experimentally. The experimental data are in qualitative agreement with the analysis results.Presented at All-Union Coordinating Conference Low-Frequency Noise in Semiconductor Devices (Chernogolovka, Moscow Region, June, 1991).St. Petersburg State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 2, pp. 226–241, February, 1994.     

Pattern competition intermittency and selective flicker noise in spatiotemporal chaos

For a coupled map lattice with a medium strength of nonlinearity, pattern selection and competition occur. Intermittent collapse of the selected pattern is found as the increase of nonlinearity. The intermittency is studied through the spatial and spatio- temporal power spectra. The latter show a flicker-like noise at low frequency only for modes of wavenumbers corresponding to the selected patterns. The scaling analysis with the change of the wavenumber and the window size is performed.     

Low-frequency magnetic noise in micron-scale magnetic tunnel junctions

We have observed low-frequency noise due to quasiequilibrium thermal magnetization fluctuations in micron-scale magnetic tunnel junctions (MTJs). This strongly field-dependent magnetic noise occurs within the magnetic hysteresis loops, either as 1/f or Lorentzian (random telegraph) noise. We attribute it to the thermally excited hopping of magnetic domain walls between pinning sites. Our results show that magnetic stability is a crucial factor in reducing the low-frequency noise in small MTJs.