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Search Results: 1 - 10 of 525388 matches for " G. M. Zaslavsky "
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Superdiffusion in the Dissipative Standard Map
G. M. Zaslavsky,M. Edelman
Physics , 2008, DOI: 10.1063/1.2967851
Abstract: We consider transport properties of the chaotic (strange) attractor along unfolded trajectories of the dissipative standard map. It is shown that the diffusion process is normal except of the cases when a control parameter is close to some special values that correspond to the ballistic mode dynamics. Diffusion near the related crisises is anomalous and non-uniform in time: there are large time intervals during which the transport is normal or ballistic, or even superballistic. The anomalous superdiffusion seems to be caused by stickiness of trajectories to a non-chaotic and nowhere dense invariant Cantor set that plays a similar role as cantori in Hamiltonian chaos. We provide a numerical example of such a sticky set. Distribution function on the sticky set almost coincides with the distribution function (SRB measure) of the chaotic attractor.
G. M. Zaslavsky,M. Edelman
Physics , 2001,
Abstract: A family of the billiard-type systems with zero Lyapunov exponent is considered as an example of dynamics which is between the regular one and chaotic mixing. This type of dynamics is called ``pseudochaos''. We demonstrate how the fractional kinetic equation can be introduced for the pseudochaos and how the main critical exponents of the fractional kinetics can be evaluated from the dynamics. Problems related to pseudochaos are discussed: Poincare recurrences, continued fractions, log-periodicity, rhombic billiards, and others. Pseudochaotic dynamics and fractional kinetics can be applied to streamlines or magnetic field lines behavior.
Stickiness of Trajectories in a Perturbed Anosov System
G. M. Zaslavsky,M. Edelman
Physics , 2005,
Abstract: We consider a perturbation of the Anosov-type system, which leads to the appearance of a hierarchical set of islands-around-islands. We demonstrate by simulation that the boundaries of the islands are sticky to trajectories. This phenomenon leads to the distribution of Poincare recurrences with power-like tails in contrast to the exponential distribution in the Anosov-type systems.
Anomalous transport and quantum-classical correspondence
Bala Sundaram,G. M. Zaslavsky
Physics , 1999, DOI: 10.1103/PhysRevE.59.7231
Abstract: We present evidence that anomalous transport in the classical standard map results in strong enhancement of fluctuations in the localization length of quasienergy states in the corresponding quantum dynamics. This generic effect occurs even far from the semiclassical limit and reflects the interplay of local and global quantum suppression mechanisms of classically chaotic dynamics. Possible experimental scenarios are also discussed.
Space-Time Complexity in Hamiltonian Dynamics
V. Afraimovich,G. M. Zaslavsky
Physics , 2003, DOI: 10.1063/1.1566171
Abstract: New notions of the complexity function C(epsilon;t,s) and entropy function S(epsilon;t,s) are introduced to describe systems with nonzero or zero Lyapunov exponents or systems that exhibit strong intermittent behavior with ``flights'', trappings, weak mixing, etc. The important part of the new notions is the first appearance of epsilon-separation of initially close trajectories. The complexity function is similar to the propagator p(t0,x0;t,x) with a replacement of x by the natural lengths s of trajectories, and its introduction does not assume of the space-time independence in the process of evolution of the system. A special stress is done on the choice of variables and the replacement t by eta=ln(t), s by xi=ln(s) makes it possible to consider time-algebraic and space-algebraic complexity and some mixed cases. It is shown that for typical cases the entropy function S(epsilon;xi,eta) possesses invariants (alpha,beta) that describe the fractal dimensions of the space-time structures of trajectories. The invariants (alpha,beta) can be linked to the transport properties of the system, from one side, and to the Riemann invariants for simple waves, from the other side. This analog provides a new meaning for the transport exponent mu that can be considered as the speed of a Riemann wave in the log-phase space of the log-space-time variables. Some other applications of new notions are considered and numerical examples are presented.
Some Applications of Fractional Equations
H. Weitzner,G. M. Zaslavsky
Physics , 2002, DOI: 10.1016/S1007-5704(03)00049-2
Abstract: We present two observations related to theapplication of linear (LFE) and nonlinear fractional equations (NFE). First, we give the comparison and estimates of the role of the fractional derivative term to the normal diffusion term in a LFE. The transition of the solution from normal to anomalous transport is demonstrated and the dominant role of the power tails in the long time asymptotics is shown. Second, wave propagation or kinetics in a nonlinear media with fractal properties is considered. A corresponding fractional generalization of the Ginzburg-Landau and nonlinear Schrodinger equations is proposed.
Statistics of quantum recurrences in the Hilbert space
A. Iomin,G. M. Zaslavsky
Physics , 2005,
Abstract: This paper has been withdrawn by the authors due to a crucial error.
Quantum manifestation of Levy-type flights in a chaotic system
A. Iomin,G. M. Zaslavsky
Physics , 2000,
Abstract: Semi--classical dynamics of quantum wave packets spreading is studied for a kicked rotor. Quantum flights are established for a specific, "magic" value of a chaos control parameter when the classical stickiness of trajectories is most effective. By studying of survival probability and distribution of the accelerations we identify the presence of quantum Levy-type flights.
Sensitivity of ray paths to initial condition
A. Iomin,G. M. Zaslavsky
Physics , 2007,
Abstract: Using a parabolic equation, we consider ray propagation in a waveguide with the sound speed profile that corresponds to the dynamics of a nonlinear oscillator. An analytical consideration of the dependence of the travel time on the initial conditions is presented. Using an exactly solvable model and the path integral representation of the travel time, we explain the step-like behavior of the travel time (T) as a function of the starting momentum (p_0) (related to the starting ray grazing angle (\chi_0) by (p_0=\tan\chi_0)). A periodic perturbation of the waveguide along the range leads to wave and ray chaos. We explain an inhomogeneity of distribution of the chaotic ray travel times, which has obvious maxima. These maxima lead to the clustering of rays and each maximum relates to a ray identifier, {\em i.e.} to the number of ray semi--cycles along the ray path.
Chaotic Advection near 3-Vortex Collapse
X. Leoncini,L. Kuznetsov,G. M. Zaslavsky
Physics , 2000, DOI: 10.1103/PhysRevE.63.036224
Abstract: Dynamical and statistical properties of tracer advection are studied in a family of flows produced by three point-vortices of different signs. A collapse of all three vortices to a single point is then possible. Tracer dynamics is analyzed by numerical construction of Poincar\'{e} sections, and is found to be strongly chaotic: advection pattern in the region around the center of vorticity is dominated by a well developed stochastic sea, which grows as the vortex system approaches the collapse; at the same time, the islands of regular motion around vortices, known as vortex cores, shrink. An estimation of the core's radii from the minimum distance of vortex approach to each other is obtained. Tracer transport was found to be anomalous: for all of the three numerically investigated cases, the variance of the tracer distribution grows faster than a linear function of time, corresponding to a super-diffusive regime. The transport exponent varies with time decades, implying the presence of multi-fractal transport features. Yet, its value is never too far from 3/2, indicating some kind of universality. Statistics of Poincar\'{e} recurrences is non-Poissonian: distributions have long power-law tails. The anomalous properties of tracer statistics are the result of the complex structure of the advection phase space, in particular, of strong stickiness on the boundaries between the regions of chaotic and regular motion. The role of the different phase space structures involved in this phenomenon is analyzed. Based on this analysis, a kinetic description is constructed, which takes into account different time and space scalings by using a fractional equation.
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