| 1. |
- Ratynskaia, Svetlana, et al.
(author)
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Grain transport in three-dimensional soft dusty plasma states
- 2010
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In: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 17:3, s. 034502-
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Journal article (peer-reviewed)abstract
- Three-dimensional molecular dynamics simulations of aggregates of dust grains interacting via repulsive Yukawa forces, and subject to heating by neutrals and realistic boundary conditions, suggest that grain transport is ubiquitously anomalous for soft states at the transition between liquid and solid. These anomalies include self-similar, stretched-Gaussian, probability density distributions of grain displacements and superdiffusive displacement scaling on the short time scales for which the mean displacements sigma(tau) are less than the interparticle distance Delta. However, the details of the anomalous transport on these shorter time scales depend on system stiffness and confinement conditions. On time scales for which sigma(tau) >= Delta, humps can develop on the distribution at integer multiples of Delta, an effect of cooperative hopping of grains on the lattice. Relaxation toward Gaussian displacement distributions and normal diffusion takes place on time scales for which sigma(tau) > Delta. The simulations indicate that qualitative features previously found for hexatic states of two-dimensional aggregates by simulation and experiment are also present in three-dimensional configurations. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3334377]
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| 2. |
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| 3. |
- Zivkovic, Tatjana, et al.
(author)
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ENSO dynamics : Low-dimensional-chaotic or stochastic?
- 2013
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In: Journal of Geophysical Research-Atmospheres. - : American Geophysical Union (AGU). - 2169-897X. ; 118:5, s. 2161-2168
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Journal article (peer-reviewed)abstract
- We apply a test for deterministic, low-dimensional, and nonlinear dynamics to the Nino 3 time series for the El Nino Southern Oscillation (ENSO). The test is positive if the time series includes the seasonal variation, but negative if it only represents the anomaly, i.e., the deviation from the seasonal cycle. The results indicate that deterministic, low-dimensional, and nonlinear dynamics in ENSO is associated with the seasonal cycle, and that the dynamics determining the interannual timing and strength of El Nino/La Nina episodes is high-dimensional/stochastic. Application of stochastic forcing to a time-delay equation for equatorial-wave dynamics can reproduce stochastic dynamics and other important aspects of ENSO. Without such stochastic forcing, this model yields deterministic, low-dimensional dynamics. With stochastic forcing, our test still yields such dynamics if the seasonal cycle is retained, but does not if the annual cycle is subtracted before the test is applied. The model results illustrate that the seasonal variability can be governed by low-dimensional nonlinear dynamics, while the interannual variability associated with ENSO is dominated by the stochastic forcing.
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| 4. |
- Zivkovic, Tatjana, et al.
(author)
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Organization of the magnetosphere during substorms
- 2012
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 117, s. A05212-
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Journal article (peer-reviewed)abstract
- The change in degree of organization of the magnetosphere during substorms is investigated by analyzing various geomagnetic indices, as well as interplanetary magnetic field z-component and solar wind velocity x-component. We conclude that the magnetosphere self-organizes globally during substorms, but neither the magnetosphere nor the solar wind become more predictable in the course of a substorm. This conclusion is based on analysis of substorms in the period from 2000 to 2002. A minimal dynamic-stochastic model of the driven magnetosphere that reproduces many statistical features of substorm indices is discussed.
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