Search

Your search keyword '"Vadivasova, T."' showing total 159 results
Start Over Author "Vadivasova, T."
159 results on '"Vadivasova, T."'

3. Dynamics of a 2D lattice of van der Pol oscillators with nonlinear repulsive coupling

Author

Shepelev, I. A., Muni, S. S., and Vadivasova, T. E.

Subjects
Nonlinear Sciences - Adaptation and Self-Organizing Systems, Nonlinear Sciences - Pattern Formation and Solitons
Abstract

We describe spatiotemporal patterns in a network of identical van der Pol oscillators coupled in a two-dimensional geometry. In this study, we show that the system under study demonstrates a plethora of different spatiotemporal structures including chimera states when the coupling parameters are varied. Spiral wave chimeras are formed in the network when the coupling strength is rather large and the coupling range is short enough. Another type of chimeras is a target wave chimera. It is shown that solitary states play a crucial role in forming an incoherence cluster of this chimera state. They can also spread within the coherence cluster. Furthermore, when the coupling range increases, the target wave chimera evolves to the regime of solitary states which are randomly distributed in space. Growing the coupling strength leads to the attraction of solitary states to a certain spatial region, while the synchronous regime is set in the other part of the system. This spatiotemporal pattern represents a solitary state chimera, which is firstly found in the system of continuous-time oscillators. We offer the explanation of these phenomena and describe the evolution of the regimes in detail., Comment: 22 pages, 9 figures

Published
2020

6. Local sensitivity of spatiotemporal structures

Author

Shepelev, I. A., Bukh, A. V., Ruschel, S., Yanchuk, S., and Vadivasova, T. E.

Subjects
Mathematics - Dynamical Systems, Nonlinear Sciences - Chaotic Dynamics
Abstract

We present an index for the local sensitivity of spatiotemporal structures in coupled oscillatory systems based on the asymptotic scaling of local-in-space, finite-time Lyapunov Exponents. For a system of nonlocally-coupled R\"{o}ssler oscillators, we show that deviations of this index reflect the sensitivity to noise and the onset of spatial chaos for the patterns where coherence and incoherence regions coexist., Comment: 15 pages, 6 figures

Published
2017

7. Input signal accumulation capability of the FitzHugh–Nagumo neuron.

Author

Bukh, A. V., Shepelev, I. A., and Vadivasova, T. E.

Subjects
ARTIFICIAL neural networks, NEURONS
Abstract

We present numerical results on the effects of two presynaptic FitzHugh–Nagumo neurons on a postsynaptic neuron under unidirectional electrical coupling. The presynaptic neurons affect the postsynaptic neuron not simultaneously but with a certain time shift. We consider cases where the amplitudes of the presynaptic spikes can be both higher and lower than the excitation threshold level. The latter case receives the main attention in our work. We carefully examine the conditions under which the postsynaptic neuron is excited by the two asynchronous external spikes. With arbitrarily chosen parameters, the FitzHugh–Nagumo neuron is almost incapable of accumulating the energy of external signals, unlike, for example, the leaky integrate-and-fire neuron. In this case, the postsynaptic neuron only excites with a very short time delay between external impulses. However, we have discovered, for the first time, a parameter region where neuron excitation is possible even with significant time delays between presynaptic impulses with subthreshold amplitudes. We explain this effect in detail and describe the mechanism behind its occurrence. We identify the boundaries of this region in the parameter plane of time delay and coupling coefficient by varying the control parameter values of the neurons. The FitzHugh–Nagumo neuron has not previously been used as a node in spiking neural networks for training via spike-timing-dependent plasticity due to the lack of an integrate-and-fire effect. However, the detection of a certain range of parameters makes the potential application of this neuron for STDP training possible. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

8. Time-delayed feedback control of coherence resonance near subcritical Hopf bifurcation: theory versus experiment

Author

Semenov, V., Feoktistov, A., Vadivasova, T., Schöll, E., and Zakharova, A.

Subjects
Nonlinear Sciences - Chaotic Dynamics, Nonlinear Sciences - Adaptation and Self-Organizing Systems
Abstract

Using the model of a generalized Van der Pol oscillator in the regime of subcritical Hopf bifurcation we investigate the influence of time delay on noise-induced oscillations. It is shown that for appropriate choices of time delay either suppression or enhancement of coherence resonance can de achieved. Analytical calculations are combined with numerical simulations and experiments on an electronic circuit.

Published
2014
Full Text
View/download PDF

9. Classification of musical intervals by spiking neural networks: Perfect student in solfége classes.

Author

Bukh, A. V., Rybalova, E. V., Shepelev, I. A., and Vadivasova, T. E.

Subjects
ARTIFICIAL neural networks, AUDITORY neurons, MUSICALS
Abstract

We investigate a spike activity of a network of excitable FitzHugh–Nagumo neurons, which is under constant two-frequency auditory signals. The neurons are supplemented with linear frequency filters and nonlinear input signal converters. We show that it is possible to configure the network to recognize a specific frequency ratio (musical interval) by selecting the parameters of the neurons, input filters, and coupling between neurons. A set of appropriately configured subnetworks with different topologies and coupling strengths can serve as a classifier for musical intervals. We have found that the selective properties of the classifier are due to the presence of a specific topology of coupling between the neurons of the network. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

11. Stochastic Oscillators

Author

Anishchenko, V. S., Vadivasova, T. E., Feoktistov, A. V., Strelkova, G. I., Rubio, Ramon G., editor, Ryazantsev, Yuri S., editor, Starov, Victor M, editor, Huang, Guo-Xiang, editor, Chetverikov, Alexander P, editor, Arena, Paolo, editor, Nepomnyashchy, Alex A., editor, Ferrus, Alberto, editor, and Morozov, Eugene G., editor

Published
2013
Full Text
View/download PDF

34. Spectral and correlation analysis of spiral chaos

Author

Anishchenko, Vadim S., Vadivasova, T. E., Kopeikin, A. S., Strelkova, G. I., and Kurths, Jürgen (Prof. Dr.)

Subjects
Institut für Physik und Astronomie
Abstract

We study numerically the behavior of the autocorrelation function (ACF) and the power spectrum of spiral attractors without and in the presence of noise. It is shown that the ACF decays exponentially and has two different time scales. The rate of the ACF decrease is defined by the amplitude fluctuations on small time intervals, i.e., when tau < tau(cor), and by the effective diffusion coefficient of the instantantaneous phase on large time intervals. it is also demonstrated that the ACF in the Poincare map also decreases according to the exponential law exp(-lambda(+)k), where lambda(+) is the positive Lyapunov exponent. The obtained results are compared with the theory of fluctuations for the Van der Pol oscillator

Published
2003

42. Role of multistability in the transition to chaotic phase synchronization

Author

Postnov, D. E., Vadivasova, T. E., Sosnovtseva, Olga, Balanov, A. G., Anishchenko, V. S., Mosekilde, Erik, Postnov, D. E., Vadivasova, T. E., Sosnovtseva, Olga, Balanov, A. G., Anishchenko, V. S., and Mosekilde, Erik

Abstract

In this paper we describe the transition to phase synchronization for systems of coupled nonlinear oscillators that individually follow the Feigenbaum route to chaos. A nested structure of phase synchronized regions of different attractor families is observed. With this structure, the transition to nonsynchronous behavior is determined by the loss of stability for the most stable synchronous mode. It is shown that the appearance of hyperchaos and the transition from lag synchronization to phase synchronization are related to the merging of chaotic attractors from different families. Numerical examples using Rossler systems and model maps are given. (c) 1999 American Institute of Physics.

Published
1999

43. Loss of lag synchronization in coupled chaotic systems

Author

Sosnovtseva, Olga, Balanov, A G, Vadivasova, T E, Astakhov, V V, Mosekilde, Erik, Sosnovtseva, Olga, Balanov, A G, Vadivasova, T E, Astakhov, V V, and Mosekilde, Erik

Abstract

Lag synchronization denotes a particular form of synchronization in which the amplitudes of two interacting, nonidentical chaotic oscillators are correlated but there is a characteristic time delay between them. We study transitions to and between different forms of synchronization for the attractors defined as "in-phase" and "out-of-phase" and investigate the processes by which lag synchronization is lost in two coupled Rössler systems. With a small frequency mismatch between the two systems, these processes are related to the occurrence of a peculiar form of basin structure as more and more periodic orbits embedded into the synchronized chaotic state become unstable in a transverse direction.

Published
1999

46. Theoretical and experimental analysis of regularities of autocorrelation function decay of the Lorentz attractor.

Author

Okrokvertskhov, G. A., Vadivasova, T. E., Anishchenko, V. S., and Strelkova, G. I.

Subjects
*DIFFERENTIABLE dynamical systems, *AUTOCORRELATION (Statistics), *DISTRIBUTION (Probability theory), *POISSON distribution, *PHYSICAL sciences, *REGRESSION analysis
Abstract

In the present paper statistical properties of the Lorentz attractor are studied and general regularities of the temporal behavior of the autocorrelation function are determined. Using a symbolic dynamics the character of a random process of switchings between two symmetric areas of the attractor is investigated. It is shown that this process posseses the statistic of a telegraphic signal with a non Poisson distribution of impulses duration. It is demonstrated that the ACF of the Lorentz attractor decays with the linear law on small times. The theoretical and numerical results are compared with data of physical experimental data. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
Full Text
View/download PDF

47. Phase multistability and mutual chaotic synchronization.

Author

Balanov, A. G., Sosnovtseva, O. V., Vadivasova, T. E., Postnov, D. E., Astakhov, V. V., and Mosekilde, E.

Subjects
ELECTRIC oscillators, SYNCHRONIZATION, COMBINATORIAL dynamics
Abstract

We consider mutual phase synchronization of chaotic oscillators. Our approach is the investigation of development of coexisting synchronous regimes. Phase-locking regions are defined for each coexisting chaotic set and described through the coherence propeties of saddle periodic orbits embedded in a chaotic attractor. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

Catalog

Books, media, physical & digital resources
See catalog results