共查询到20条相似文献,搜索用时 30 毫秒
1.
E. V. Pankratova V. N. Belykh E. Mosekilde 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):529-536
The present paper examines the influence of the forcing frequency on the
response of a randomly perturbed Hodgkin-Huxley system in the realm
of suprathreshold amplitudes. Our results show that, in the presence
of noise, the choice of driving frequency can seriously affect the
precision of the external information transmission. At the same
level of noise the precision can either decrease or increase
depending on the driving frequency. We demonstrate that the
destructive influence of noise on the interspike interval can be
effectively reduced. That is, with driving signals in certain
frequency ranges, the system can show stable periodic spiking even
for relatively large noise intensities. Here, the most accurate
transmission of an external signal occurs. Outside these frequency
ranges, noise of the same intensity destroys the regularity of the
spike trains by suppressing the generation of some spikes. On the
other hand, we show that noise can have a reconstructive role for
certain driving frequencies. Here, increasing noise intensity
enhances the coherence of the neuronal response. 相似文献
2.
M. L. Deng W. Q. Zhu 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(3):391-397
The energy diffusion controlled reaction rate of a reacting particle with linear weak damping and broad-band noise excitation
is studied by using the stochastic averaging method. First, the stochastic averaging method for strongly nonlinear oscillators
under broad-band noise excitation using generalized harmonic functions is briefly introduced. Then, the reaction rate of the
classical Kramers' reacting model with linear weak damping and broad-band noise excitation is investigated by using the stochastic
averaging method. The averaged It? stochastic differential equation describing the energy diffusion and the Pontryagin equation
governing the mean first-passage time (MFPT) are established. The energy diffusion controlled reaction rate is obtained as
the inverse of the MFPT by
solving the Pontryagin equation. The results of two special cases of
broad-band noises, i.e. the harmonic noise and the exponentially corrected noise, are discussed in details. It is demonstrated
that the general expression of reaction rate derived by the authors can be reduced to the classical ones via linear approximation
and high potential barrier approximation. The good agreement with the results of the Monte Carlo simulation verifies that
the reaction rate can be well predicted using the stochastic averaging method. 相似文献
3.
We investigate a drive-response system by considering the impacts of noise on generalized synchronization (GS). It is found that a small amount of noise can turn the system from desynchronization to the GS state in the resonant case no matter how noise is injected into the system. In the non-resonant case, noise with intensity in a certain range is helpful in building GS only when the noise is injected to the driving system. The mechanism behind the observed phenomena is discussed. 相似文献
4.
Detection of Mechanism of Noise-Induced Synchronization between Two Identical Uncoupled Neurons
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We investigate the noise-induced synchronization between two identical uncoupled Hodgkin-Huxley neurons with sinusoidal stimulations. The numerical results confirm that the value of critical noise intensity for synchronizing two systems is much less than the magnitude of mean size of the attractor in the original system, and the deterministic feature of the attractor in the original system remains unchanged. This finding is significantly different from the previous work [Phys. Rev. E 67 (2003) 027201] in which the value of the critical noise intensity for synchronizing two systems was found to be roughly equal to the magnitude of mean size of the attractor in the original system, and at this intensity, the noise swamps the qualitative structure of the attractor in the original deterministic systems to synchronize to their stochastic dynamics. Further investigation shows that the critical noise intensity for synchronizing two neurons induced by noise may be related to the structure of interspike intervals of the original systems. 相似文献
5.
6.
Pattern synchronization in a two-layer neuronal network is studied. For a single-layer network of Rulkov map neurons, there are three kinds of patterns induced by noise. Additive noise can induce ordered patterns at some intermediate noise intensities in a resonant way; however, for small and large noise intensities there exist excitable patterns and disordered patterns, respectively. For a neuronal network coupled by two single-layer networks with noise intensity differences between layers, we find that the two-layer network can achieve synchrony as the interlayer coupling strength increases. The synchronous states strongly depend on the interlayer coupling strength and the noise intensity difference between layers. 相似文献
7.
F. Curbis A. Antoniazzi G. De Ninno D. Fanelli 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(4):527-533
Single-pass free-electron lasers constitute an example of systems with
long-range interactions. The light-particle interplay leading to the
power growth and successive relaxation towards a quasi-stationary state
is governed by the Vlasov equation. A maximum entropy principle inspired to Lynden-Bell's theory of
“violent relaxation" for the Vlasov equation can be invoked
to analytically
characterize the behaviour of the saturated system.
In particular, we here concentrate on the case of
coherent harmonic generation obtained from an externally seeded
free-electron laser and provide a simple strategy to predict the
laser intensity as well as the final electron-beam
energy distribution. 相似文献
8.
A. Fiasconaro W. Ebeling E. Gudowska-Nowak 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(3):403-414
We give an overview over recent studies on the model of Active Brownian Motion (ABM) coupled to reservoirs providing free
energy which may be converted into kinetic energy of motion. First, we present an introduction to a general concept of active
Brownian particles which are capable to take up energy from the source and transform part of it in order to perform various
activities. In the second part of our presentation we consider applications of ABM to ratchet systems with different forms
of differentiable potentials. Both analytical and numerical evaluations are discussed for three cases of sinusoidal, staircaselike
and Mateos ratchet potentials, also with the additional loads modelled by tilted potential structure. In addition, stochastic
character of the kinetics is investigated by considering perturbation by Gaussian white noise which is shown to be responsible
for driving the directionality of the asymptotic flux in the ratchet. This stochastically driven directionality effect is visualized as a strong nonmonotonic dependence of the statistics of the right versus left trajectories of motion
leading to a net current of particles. Possible applications of the ratchet systems to molecular motors are also briefly discussed. 相似文献
9.
Stability Analysis of an Inverted Pendulum Subjected to Combined High Frequency Harmonics and Stochastic Excitations
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Stability of vertical upright position of an inverted pendulum with its suspension point subjected to high frequency harmonics and stochastic excitations is investigated. Two classes of excitations, i.e., combined high frequency harmonic excitation and Gaussian white noise excitation, and high frequency bounded noise excitation, respectively, are considered. Firstly, the terms of high frequency harmonic excitations in the equation of motion of the system can be set equivalent to nonlinear stiffness terms by using the method of direct separation of motions. Then the stochastic averaging method of energy envelope is used to derive the averaged Ito stochastic differential equation for system energy. Finally, the stability with probability 1 of the system is studied by using the largest Lyapunov exponent obtained from the averaged Ito stochastic differential equation. The effects of system parameters on the stability of the system are discussed, and some examples are given to illustrate the efficiency of the proposed procedure. 相似文献
10.
F. Pétrélis S. Aumaître 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(3):357-362
We study two dynamical systems submitted to white and Gaussian random noise acting multiplicatively. The first system is an
imperfect pitchfork bifurcation with a noisy departure from onset. The second system is a pitchfork bifurcation in which the
noise acts multiplicatively on the non-linear term of lowest order. In both cases noise suppresses some solutions that exist
in the deterministic regime. Besides, for the first system, the imperfectness of the bifurcation reduces the regime of on-off
intermittency. For the second system, the unstable mode can achieve a jump of finite amplitude at instability but without
hysteresis. We finally identify a generic property that is verified by the stationary probability density function of the
dynamical variable when a control parameter is varied. 相似文献
11.
In this Letter, an electrical circuit is built for realizing the multi-state intermittency generated by a simple force-driven chaotic system. The intermittency phenomenon and its underlaying mechanism are analyzed, and the experimental results are discussed. It is shown that, with two classes of invariant subspaces, the number of the laminar states and the distance between the adjacent laminar states of the created multi-state on-off intermittency can be arbitrarily changed by manipulating the control parameters. 相似文献
12.
P. H. Chavanis 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):487-501
Systems with long-range interactions can reach a Quasi
Stationary State (QSS) as a result of a violent collisionless
relaxation. If the system mixes well (ergodicity), the QSS can be
predicted by the statistical theory of Lynden-Bell (1967) based on
the Vlasov equation. When the initial condition takes only two
values, the Lynden-Bell distribution is similar to the Fermi-Dirac
statistics. Such distributions have recently been observed in
direct numerical simulations of the HMF model (Antoniazzi et al. 2006). In this paper, we determine the caloric curve
corresponding to the Lynden-Bell statistics in relation with the
HMF model and analyze the dynamical and thermodynamical stability
of spatially homogeneous solutions by using two general criteria
previously introduced in the literature. We express the critical
energy and the critical temperature as a function of a degeneracy
parameter fixed by the initial condition. Below these critical
values, the homogeneous Lynden-Bell distribution is not a maximum
entropy state but an unstable saddle point. Known stability
criteria corresponding to the Maxwellian distribution and the
water-bag distribution are recovered as particular limits of our
study. In addition, we find a critical point below which the
homogeneous Lynden-Bell distribution is always stable. We apply
these results to the situation considered in Antoniazzi et
al. For a given energy, we find a critical initial
magnetization above which the homogeneous Lynden-Bell distribution
ceases to be a maximum entropy state. For an energy U=0.69, this
transition occurs above an initial magnetization Mx=0.897. In
that case, the system should reach an inhomogeneous Lynden-Bell
distribution (most mixed) or an incompletely mixed state (possibly
fitted by a Tsallis distribution). Thus, our theoretical study
proves that the dynamics is different for small and large initial
magnetizations, in agreement with numerical results of Pluchino et
al. (2004). This new dynamical phase transition may reconcile the
two communities by showing that they study different regimes. 相似文献
13.
We study the phenomenon of stochastic resonance on
small-world networks consisting of bistable genetic regulatory units,
whereby the external subthreshold periodic forcing is introduced as a
pacemaker trying to impose its rhythm on the whole network through the
single unit to which it is introduced. Without the addition of additive
spatiotemporal noise, however, the whole network remains forever trapped in
one of the two stable steady states of the local dynamics. We show that the
correlation between the frequency of subthreshold pacemaker activity and the
response of the network is resonantly dependent on the intensity of additive
noise. The reported pacemaker driven stochastic resonance depends
significantly on the asymmetry of the two potential wells characterizing the
bistable dynamics, which can be tuned via a single system parameter. In
particular, we show that the ratio between the clustering coefficient and
the characteristic path length is a suitable quantity defining the ability
of a small-world network to facilitate the outreach of the pacemaker-emitted
subthreshold rhythm, but only if the asymmetry between the potentials is
practically negligible. In case of substantially asymmetric potentials the
impact of the small-world topology is less profound and cannot warrant an
enhancement of stochastic resonance by units that are located far from the
pacemaker. 相似文献
14.
We examine how noise interacts with encoding mechanisms of neuronal stimulus in a cold receptor. From ISI series and bifurcation diagrams it is shown that there are considerable differences in interval distributions and impulse patterns caused by purely deterministic simulations and noisy simulations. The ISI-distance can be used as an effective and powerful way to measure the noise effects on spike trains of the cold receptor quantitatively. It is also found that spike trains observed in cold receptors can be more strongly affected by noise for low temperatures than for high temperatures in some aspects; meanwhile, the spike train has greater variability with increasing noise intensity. 相似文献
15.
By introducing a new type of solutions, called the multiple-mode wave solutions which can be expressed in nonlinear superposition of single-mode waves with different speeds, we investigate the two-mode wave solutions in Degasperis-Procesi equation and two cases are derived. The explicit expressions for the two-mode waves as well as the existence conditions are presented. It is shown that the two-mode waves may be the nonlinear combinations of many types of single-mode waves, such as periodic waves, solJtons, compactons, etc., and more complicated multiple-mode waves can be obtained if higher order or more single-mode waves are taken into consideration. It is pointed out that the two-mode wave solutions can be employed to display the typical mechanism of the interactions between different single-mode waves. 相似文献
16.
This Letter presents a synchronization method for Lur'e systems with sector and slope restricted nonlinearities. A static error feedback controller based on the Lyapunov stability theory is proposed for asymptotic synchronization. The Lyapunov function candidate is chosen as a quadratic form of the error states and nonlinear functions of the systems. The nonlinearities are expressed as convex combinations of sector and slope bounds by using convex properties of the nonlinear function so that equality constraints are converted into inequality constraints. Then, the feedback gain matrix is derived through a linear matrix inequality (LMI) formulation. Finally, a numerical example shows the effectiveness of the proposed method. 相似文献
17.
Characterizing dynamical transitions in bistable systems using a non-equilibrium measurement of work
Pulak Kumar Ghosh 《Physica A》2008,387(26):6443-6451
We show how the Jarzynski relation can be exploited to analyze the nature of order-disorder, and a bifurcation type dynamical transition in terms of a response function derived on the basis of work distribution over non-equilibrium paths between two thermalized states. The validity of the response function extends over a linear as well as a nonlinear regime, and far from equilibrium situations. 相似文献
18.
S. Morfu 《Physics letters. A》2009,373(29):2438-2444
We propose a new algorithm inspired by the properties of diffusion processes for image filtering. We show that purely nonlinear diffusion processes ruled by Fisher equation allows contrast enhancement and noise filtering, but involves a blurry image. By contrast, anisotropic diffusion, described by Perona and Malik algorithm, allows noise filtering and preserves the edges. We show that combining the properties of anisotropic diffusion with those of nonlinear diffusion provides a better processing tool which enables noise filtering, contrast enhancement and edge preserving. 相似文献
19.
Noise color and asymmetry in stochastic resonance with silicon nanomechanical resonators 总被引:1,自引:1,他引:0
T. Dunn D. N. Guerra P. Mohanty 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):5-10
Stochastic resonance with white noise has been well established as a potential signal amplification mechanism in nanomechanical
two-state systems. While white noise represents the archetypal stimulus for stochastic resonance, typical operating environments
for nanomechanical devices often contain different classes of noise, particularly colored noise with a 1/f spectrum. As a
result, improved understanding of the effects of noise color will be helpful in maximizing device performance. Here we report
measurements of stochastic resonance in a silicon nanomechanical resonator using 1/f noise and Ornstein-Uhlenbeck noise types.
Power spectral densities and residence time distributions provide insight into asymmetry of the bistable amplitude states,
and the data sets suggest that 1/fα noise spectra with increasing noise color (i.e. α) may lead to increasing asymmetry in the system, reducing the achievable
amplification. Furthermore, we explore the effects of correlation time τ on stochastic resonance with the use of exponentially
correlated noise. We find monotonic suppression of the spectral amplification as the correlation time increases. 相似文献
20.
G. Tang G. Hu 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):109-114
Spatiotemporal chaos control is considered by taking a
one-dimensional driven/damped nonlinear drift-wave equation as a
model. We apply an additional sinusoidal wave to suppress
spatiotemporal chaos, and the system becomes a two-sinusoidal-wave driven system
(the original driving wave with frequency ω and an
additional controlling wave with frequency Ω).
Numerical simulations show that when the frequency of the
controlling wave is in the proper range, spatiotemporal chaos can be
modified into a regular state where the amplitudes of all
modes vary periodically with frequency Ω-ω while the
phases of all modes evolve quasi-periodically with a running
frequency Ω overlapped by a small modulation of frequency
Ω-ω. The physical reason for this peculiar phenomenon is
attributed to a frequency entrainment in the competition of the two external waves. 相似文献