23 research outputs found
Explosive crystallization mechanism of ultradisperse amorphous films
The explosive crystallization of germanium ultradisperse amorphous films is
studied experimentally. We show that crystallization may be initiated by local
heating at the small film thickness but it realizes spontaneously at the large
ones. The fractal pattern of the crystallized phase is discovered that is
inherent in the phenomena of diffusion limited aggregation. It is shown that in
contrast to the ordinary crystallization mode the explosive one is connected
with the instability which is caused by the self-heating. A transition from the
first mechanism to the second one is modelled by Lorenz system. The process of
explosive crystallization is represented on the basis of the self-organized
criticality conception. The front movement is described as the effective
diffusion in the ultrametric space of hierarchically subordinated avalanches,
corresponding to the explosive crystallization of elementary volumes of
ultradisperse powder. The expressions for the stationary crystallization heat
distribution and the steady-state heat current are obtained. The heat needed
for initiation of the explosive crystallization is obtained as a function of
the thermometric conductivity. The time dependence of the spontaneous
crystallization probability in a thin films is examined.Comment: 22 pages, 5 figures, LaTe
Multifractal spectrum of phase space related to generalized thermostatistics
We consider a self-similar phase space with specific fractal dimension
being distributed with spectrum function . Related thermostatistics is
shown to be governed by the Tsallis formalism of the non-extensive statistics,
where the non-additivity parameter is equal to , and the multifractal function is the
specific heat determined with multifractal parameter . In this
way, the equipartition law is shown to take place. Optimization of the
multifractal spectrum function derives the relation between the
statistical weight and the system complexity. It is shown the statistical
weight exponent can be modeled by hyperbolic tangent deformed in
accordance with both Tsallis and Kaniadakis exponentials to describe arbitrary
multifractal phase space explicitly. The spectrum function is proved to
increase monotonically from minimum value at to maximum one
at . At the same time, the number of monofractals increases with growth of
the phase space volume at small dimensions and falls down in the limit
.Comment: 16 pages, 7 figure
Self-organization of quasi-equilibrium stationary condensation in accumulative ion-plasma devices
We consider both theoretically and experimentally self-organization process
of quasi-equilibrium steady-state condensation of sputtered substance in
accumulative ion-plasma devices. The self-organization effect is shown to be
caused by self-consistent variations of the condensate temperature and the
supersaturation of depositing atoms. On the basis of the phase-plane method, we
find two different types of the self-organization process to be possible.
Experimental data related to aluminum condensates are discussed to confirm
self-organization nature of quasi-equilibrium steady-state condensation
process.Comment: 14 pages, 3 figure
Nonequilibrium phase transitions in stochastic systems with coloured fluctuations
We study the behaviour of a class of stochastic spatially extended systems exhibiting transition to absorbing
configurations, reentrant noise induced phase transitions and phase transitions induced by noise crosscorrelations.
We discuss the behaviour of the system in the presence of multiplicative fluctuations: a possibility
of escaping from the absorbing state and the nature of disordered phase appearing beyond the second critical
point of the reentrant phase transition. Making use of the mean field approach we have shown that noise
cross-correlations lead to continuous, discontinuous and reentrant phase transitions
Embedding a Native State into a Random Heteropolymer Model: The Dynamic Approach
We study a random heteropolymer model with Langevin dynamics, in the
supersymmetric formulation. Employing a procedure similar to one that has been
used in static calculations, we construct an ensemble in which the affinity of
the system for a native state is controlled by a "selection temperature" T0. In
the limit of high T0, the model reduces to a random heteropolymer, while for
T0-->0 the system is forced into the native state. Within the Gaussian
variational approach that we employed previously for the random heteropolymer,
we explore the phases of the system for large and small T0. For large T0, the
system exhibits a (dynamical) spin glass phase, like that found for the random
heteropolymer, below a temperature Tg. For small T0, we find an ordered phase,
characterized by a nonzero overlap with the native state, below a temperature
Tn \propto 1/T0 > Tg. However, the random-globule phase remains locally stable
below Tn, down to the dynamical glass transition at Tg. Thus, in this model,
folding is rapid for temperatures between Tg and Tn, but below Tg the system
can get trapped in conformations uncorrelated with the native state. At a lower
temperature, the ordered phase can also undergo a dynamical glass transition,
splitting into substates separated by large barriers.Comment: 19 pages, revtex, 6 figure
Lifetime distributions in the methods of non-equilibrium statistical operator and superstatistics
A family of non-equilibrium statistical operators is introduced which differ
by the system age distribution over which the quasi-equilibrium (relevant)
distribution is averaged. To describe the nonequilibrium states of a system we
introduce a new thermodynamic parameter - the lifetime of a system.
Superstatistics, introduced in works of Beck and Cohen [Physica A \textbf{322},
(2003), 267] as fluctuating quantities of intensive thermodynamical parameters,
are obtained from the statistical distribution of lifetime (random time to the
system degeneracy) considered as a thermodynamical parameter. It is suggested
to set the mixing distribution of the fluctuating parameter in the
superstatistics theory in the form of the piecewise continuous functions. The
distribution of lifetime in such systems has different form on the different
stages of evolution of the system. The account of the past stages of the
evolution of a system can have a substantial impact on the non-equilibrium
behaviour of the system in a present time moment.Comment: 18 page
Statistical theory of self-similar time series
Within Tsallis statistics, a picture is elaborated to treat self-similar time series as a thermodynamic system. Thermodynamic-type characteristics relevant to temperature, pressure, entropy, internal and free energies are introduced and tested. Predictability conditions of time series analysis are discussed on the basis of Van der Waals model. Maximal magnitude for time interval and minimal resolution scale of the value under consideration are found and analyzed in details. Time series statistics is shown to be governed by effective temperature being exponential measure of the fractal dimensionality of a phase space related to the time series.
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Theory of hierarchical coupling
The paper has been withdrawnComment: The paper has been withdraw