30 research outputs found
Modeling noise induced resonance in an excitable system: An alternative approach
Recently, it is observed [Md. Nurujjaman et al, Phy. Rev. E \textbf{80},
015201 (R) (2009)] that in an excitable system, one can maintain noise induced
coherency in the coherence resonance by blocking the destructive effect of the
noise on the system at higher noise level. This phenomenon of constant
coherence resonance (CCR) cannot be explained by the existing way of simulation
of the model equations of an excitable system with added noise. In this paper,
we have proposed a general model which explains the noise induced resonance
phenomenon CCR as well as coherence resonance (CR) and stochastic resonance
(SR). The simulation has been carried out considering the basic mechanism of
noise induced resonance phenomena: noise only perturbs the system control
parameter to excite coherent oscillations, taking proper precautions so that
the destructive effect of noise does not affect the system. In this approach,
the CR has been obtained from the interference between the system output and
noise, and the SR has been obtained by adding noise and a subthreshold signal.
This also explains the observation of the frequency shift of coherent
oscillations in the CCR with noise level.Comment: 5 pages, 4 figure
Parametric investigation of nonlinear fluctuations in a dc glow discharge plasma
Glow discharge plasmas exhibit various types of self excited oscillations for
different initial conditions like discharge voltages and filling pressures. The
behavior of such oscillations associated with the anode glow have been
investigated using nonlinear techniques like correlation dimension, largest
Lyapunov exponent etc. It is seen that these oscillations go to an ordered
state from a chaotic state with increase in input energy i.e. with discharge
voltages implying occurrence of inverse bifurcations. These results are
different from the other observations wherein the fluctuations have been
observed to go from ordered to chaotic state.Comment: Submitted to Chao
Emergence of the stochastic resonance in glow discharge plasma
stochastic resonance, glow discharge plasma, excitable medium, absolute mean
differenceComment: St
Continuous wavelet transform based time-scale and multi-fractal analysis of the nonlinear oscillations in a hollow cathode glow discharge plasma
Continuous wavelet transform (CWT) based time-scale and multi-fractal
analyses have been carried out on the anode glow related nonlinear floating
potential fluctuations in a hollow cathode glow discharge plasma. CWT has been
used to obtain the contour and ridge plots. Scale shift (or inversely frequency
shift) which is a typical nonlinear behaviour, has been detected from the
undulating contours. From the ridge plots, we have identified the presence of
nonlinearity and degree of chaoticity. Using the wavelet transform modulus
maxima technique we have obtained the multi-fractal spectrum for the
fluctuations at different discharge voltages and the spectrum was observed to
become a monofractal for periodic signals. These multi-fractal spectra were
also used to estimate different quantities like the correlation and fractal
dimension, degree of multi-fractality and complexity parameters. These
estimations have been found to be consistent with the nonlinear time series
analysis.Comment: 6 pages, 5 figures, glow discharge plasma; Multifractal spectrum;
contour plots, ridge plots, correlation dimension, complexity paramete
Coherence resonance in an unijunction transistor relaxation oscillator
The phenomenon of coherence resonance (CR) is investigated in an unijunction
transistor relaxation oscillator (UJT-RO) and quantified by estimating the
normal variance (NV). Depending upon the measuring points two types of NV
curves have been obtained. We have observed that the degradations in coherency
at higher noise amplitudes in our system is probably the result of direct
interference of coherent oscillations and the stochastic perturbation.
Degradation of coherency may be minimal if this direct interference of noise
and coherent oscillations is eliminated.Comment: 4 pages, Coherence resonace, Uni junction relaxation oscillato