共查询到20条相似文献,搜索用时 15 毫秒
1.
O.V. Gerashchenko S.L. Ginzburg M.A. Pustovoit 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(2):335-338
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 相似文献
2.
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
3.
4.
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
5.
V.I. Nekorkin V.B. Kazantsev M.G. Velarde 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(1):147-155
The dynamics of a system composed of two nonlinearly coupled, drastically different nonlinear and eventually oscillatory elements
is studied. The rich variety of attractors of the system is studied with the help of phase space analysis and Poincare maps.
Received 19 March 1999 and Received in final form 1 November 1999 相似文献
6.
J.M. Sancho A. Sánchez 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(1):127-131
We study the dynamics of fronts when both inertial effects and external fluctuations are taken into account. Stochastic fluctuations
are introduced as multiplicative white noise arising from a control parameter of the system. Contrary to the non-inertial
(overdamped) case, we find that important features of the system, such as the velocity selection picture, are not modified
by the noise. We then compute the overdamped limit of the underdamped dynamics in a more careful way, finding that it does
not exhibit any effect of noise either. Our result poses the question as to whether or not external noise sources can be measured
in physical systems of this kind.
Received 2 July 1999 and Received in final form 25 November 1999 相似文献
7.
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
8.
D. Valenti L. Schimansky-Geier X. Sailer B. Spagnolo 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):199-203
The dynamics of a spatially extended system of two competing
species in the presence of two noise sources is studied. A
correlated dichotomous noise acts on the interaction parameter and
a multiplicative white noise affects directly the dynamics of the
two species. To describe the spatial distribution of the species
we use a model based on Lotka-Volterra (LV) equations. By writing
them in a mean field form, the corresponding moment equations for
the species concentrations are obtained in Gaussian approximation.
In this formalism the system dynamics is analyzed for different
values of the multiplicative noise intensity. Finally by comparing
these results with those obtained by direct simulations of the
time discrete version of LV equations, that is coupled map lattice
(CML) model, we conclude that the anticorrelated oscillations of
the species densities are strictly related to non-overlapping
spatial patterns. 相似文献
9.
Y. Zhang G. Hu 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(2):253-256
The transient process of globally coupled bistable systems from an unstable state to metastable state (i.e, quenching process) is studied analytically for small noise intensity. The influences of noise intensity and system size
on the system evolution are investigated. The problem of a large number of coupled Langevin equations is reduced to a simple
problem of a one-dimensional ordinary differential equation, subject to a white noise with intensity explicitly given. The
analytical results are fully confirmed by direct numerical computations.
Received: 3 July 1997 / Revised: 4 December 1997 / Accepted: 15 January 1998 相似文献
10.
Y. Nakamura A.R. Ferchmin 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(2):305-312
A neural network model composed of two-state (1 and -1) and three-state (1, 0 and -1) neurons is proposed. The two-state neurons
are connected with the three-state ones only and vice versa. We derive dynamic equations for the model under the assumption of non-symmetrical dilution of connections. A zero-noise
phase diagram is obtained and a region in which two fixed point solutions can coexist is found. Basins of attraction for the
solutions are also investigated.
Received 26 October 1998 and Received in final form 12 February 1999 相似文献
11.
F. Volino G. Gebel H. Gérard 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(1):25-35
A simple lattice model based on generalised diffusion equations and Gaussian statistics, aimed at describing diffusive translational
and rotational motions, is presented. It is shown that it allows the generation of correlation functions relevant to spectroscopic
techniques that are very similar to those experimentally observed in a large variety of complex systems. For some ranges of
values of the model parameters, these functions, which can be expressed in closed mathematical forms, can be approximately
represented by the sum of two exponentials or by “stretched" exponentials.
Received 17 September 1999 and Received in final form 10 February 2000 相似文献
12.
S. Z. Ke D. J. Wu L. Cao 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(1):119-122
The colored noise problem is studied from the point of view of consistent Markovian approximations through extending unified
colored-noise approximation to the case of two-colored-noise driving systems. A bistable system simultaneously driven by multiplicative
and additive colored noise is investigated by means of the extended unified colored-noise approximation. It is found that,
for weak strength and color of the additive noise, the form of the stationary probability distribution changes from a unimodal
to a bimodal structure via a three modal one as the correlation time of the multiplicative colored noise increases, showing
the system undergoes a first order phase transition from a monostable to a bistable state. Numerical simulations support our
results.
Received 10 August 1998 and Received in final form 23 April 1999 相似文献
13.
Breakup of spiral wave in the Hindmarsh-Rose neurons with nearest-neighbour couplings is reported. Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gaussian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively. Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave. It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold. 相似文献
14.
M. Grifoni E. Paladino U. Weiss 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(4):719-729
The dynamics of the reduced density matrix of the driven dissipative two-state system is studied for a general diagonal/off-diagonal
initial state. We derive exact formal series expressions for the populations and coherences and show that they can be cast
into the form of coupled nonconvolutive exact master equations and integral relations. We show that neither the asymptotic
distributions, nor the transition temperature between coherent and incoherent motion, nor the dephasing rate and relaxation
rate towards the equilibrium state depend on the particular initial state chosen. However, in the underdamped regime, effects
of the particular initial preparation, e.g. in an off-diagonal state of the density matrix, strongly affect the transient dynamics. We find that an appropriately tuned external ac-field
can slow down decoherence and thus allow preparation effects to persist for longer times than in the absence of driving.
Received 23 October 1998 and Received in final form 26 February 1999 相似文献
15.
O.V. Gerashchenko S.L. Ginzburg M.A. Pustovoit 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(1):101-106
Recently we discovered the phenomenon of hypersensitivity to small time-dependent signals in a simple stochastic system, the
Kramers oscillator with multiplicative white noise. In the present work we study, theoretically and experimentally with analog
simulations, an influence of noise correlation time on hypersensitivity in a nonlinear oscillator with piecewise-linear current-voltage
characteristic and multiplicative colored dichotomous noise. We found that the region of hypersensitive behavior is defined
by universal scaling index, whereas the specifics of a particular system reveals itself only in the dependence of the above
index on system parameters. The dependence of gain factor on noise correlation time is of bell-shaped (resonant) type.
Received 27 April 2000 and Received in final form 2 November 2000 相似文献
16.
R. Gerami M.R. Ejtehadi 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(3):601-606
A non-Markovian stochastic predator-prey model is introduced in which the prey are immobile plants and predators are diffusing
herbivors. The model is studied by both mean-field approximation (MFA) and computer simulations. The MFA results a series
of bifurcations in the phase space of mean predator and prey densities, leading to a chaotic phase. Because of emerging correlations
between the two species distributions, the interaction rate alters and if it is chosen to be the value which is obtained from
the simulation, then the chaotic phase disappears.
Received 12 July 1999 相似文献
17.
We derive the life time and loss rate for a trapped atom that is coupled to fluctuating fields in the vicinity of a room-temperature
metallic and/or dielectric surface. Our results indicate a clear predominance of near-field effects over ordinary blackbody
radiation. We develop a theoretical framework for both charged ions and neutral atoms with and without spin. Loss processes
that are due to a transition to an untrapped internal state are included.
Received: 28 June 1999 / Revised version: 4 October 1999 / Published online: 10 November 1999 相似文献
18.
S.A. Hassan A.R. Vasconcellos R. Luzzi 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(1):131-139
We analyze in detail the nonlinear kinetics of a carrier system in a photoinjected plasma in semiconductors under the action
of constant illumination with ultraviolet light. We show that the spatially homogeneous steady-state becomes unstable, and
a charge density wave emerges after a critical intensity of the incident radiation is achieved. It is shown that this instability
can only follow in doped p-type materials. In bulk systems the critical intensity was found to be too high making the phenomenon not observable under
realistic experimental conditions. However, a more efficient electron excitation can be obtained in low dimensional p-type systems, like some molecular and biological polymers, where the interaction may follow by chemical interaction with
the medium. We show that for intensities beyond the critical threshold an increasing number of modes provide further contributions
(subharmonics) to the space inhomogeneity. It is conjectured that this process could lead the system to display chaotic-like
behavior.
Received 8 July 1998 and Received in final form 6 May 1999 相似文献
19.
Shakti N. Menon 《Physica D: Nonlinear Phenomena》2009,238(4):461-475
We study a one-dimensional filamental model of a chaotically stirred excitable medium. In a numerical simulation we systematically explore its rich bifurcation scenarios involving saddle-nodes, Hopf bifurcations and hysteresis loops. The bifurcations are described in terms of two parameters signifying the excitability of the reacting medium and the strength of the chaotic stirring, respectively. The solution behaviour, in particular at the bifurcation points, is analytically described by means of a nonperturbative variational method. Using this method we reduce the partial differential equations to either algebraic equations for stationary solutions and bifurcations, or to ordinary differential equations in the case of non-stationary solutions and bifurcations. We present numerical simulations corroborating our analytical results. 相似文献
20.
G. Abramson J.L. Vega 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(2):361-364
Multifractal critical phenomena with infinite-temperature critical point and with complex coexistence of the infinite and
finite temperature critical points are considered and it is shown that strange attractors generated by cascades of period-doubling
bifurcations (Feigenbaum scenario) as well as fields of velocity differences in fluid turbulence belong to the former subclass
of the multifractal critical phenomena, while the real traffic processes and real currency exchange processes belong to the
last (complex) subclass of the multifractal critical phenomena. Data obtained by different authors are used for this purpose.
Received 5 February 1999 相似文献