503 research outputs found
Kolmogorov turbulence in a random-force-driven Burgers equation: anomalous scaling and probability density functions
High-resolution numerical experiments, described in this work, show that
velocity fluctuations governed by the one-dimensional Burgers equation driven
by a white-in-time random noise with the spectrum exhibit a biscaling behavior: All moments of velocity differences
, while with for real
(Chekhlov and Yakhot, Phys. Rev. E {\bf 51}, R2739, 1995). The
probability density function, which is dominated by coherent shocks in the
interval , is with
.Comment: 12 pages, psfig macro, 4 figs in Postscript, accepted to Phys. Rev. E
as a Brief Communicatio
1,4,10,13-Tetraoxa-7,16-diazoniacyclooctadecane bis[tetrachloridoaurate(III)] dihydrate
The asymmetric unit of the title compound, (C12H28N2O4)[AuCl4]2·2H2O, contains one half-cation, one anion and one water molecule; the cation is centrosymmetric. The Au ion has a square-planar coordination. In the crystal structure, intramolecular N—H⋯O and O—H⋯O, and intermolecular N—H⋯O, O—H⋯Cl and N—H⋯Cl hydrogen bonds link the ions and water molecules, forming a supramolecular structure
On the maximum drawdown during speculative bubbles
A taxonomy of large financial crashes proposed in the literature locates the
burst of speculative bubbles due to endogenous causes in the framework of
extreme stock market crashes, defined as falls of market prices that are
outlier with respect to the bulk of drawdown price movement distribution. This
paper goes on deeper in the analysis providing a further characterization of
the rising part of such selected bubbles through the examination of drawdown
and maximum drawdown movement of indices prices. The analysis of drawdown
duration is also performed and it is the core of the risk measure estimated
here.Comment: 15 pages, 7 figure
Direct Numerical Simulation Tests of Eddy Viscosity in Two Dimensions
Two-parametric eddy viscosity (TPEV) and other spectral characteristics of
two-dimensional (2D) turbulence in the energy transfer sub-range are calculated
from direct numerical simulation (DNS) with 512 resolution. The DNS-based
TPEV is compared with those calculated from the test field model (TFM) and from
the renormalization group (RG) theory. Very good agreement between all three
results is observed.Comment: 9 pages (RevTeX) and 5 figures, published in Phys. Fluids 6, 2548
(1994
Turbulence without pressure
We develop exact field theoretic methods to treat turbulence when the effect
of pressure is negligible. We find explicit forms of certain probability
distributions, demonstrate that the breakdown of Galilean invariance is
responsible for intermittency and establish the operator product expansion. We
also indicate how the effects of pressure can be turned on perturbatively.Comment: 12 page
On commutator fully transitive Abelian groups
Abstract
There are two rather natural questions which arise in connection with the endomorphism ring of an
Abelian group: when is the ring generated
by its commutators, and
when is the ring additively generated by
its commutators?
The current work explores these two problems
for arbitrary Abelian groups.
This leads in a standard way to consideration of
two improved versions of
Kaplansky's notion of full transitivity,
which we call
commutator full transitivity
and strongly commutator full transitivity.
We establish, inter alia,
that these notions are strictly stronger
than the classical concept of full transitivity,
but there are nonetheless many parallels between
these things.</jats:p
Weakly fully and characteristically inert socle-regular Abelian p-groups
In regard to two recent publications in the Mediterranean J. Math. (2021) and Forum Math. (2021) related to fully and characteristically inert socleregularity, respectively, we define and study the so-called weakly characteristically inert socle-regular groups. In that aspect, as a culmination of the investigations of this sort, some more global results are obtained and, moreover, some new concrete results concerning the weakly fully inert socle-regular groups, defined as in the firstly mentioned above paper, are also established. In particular, we prove that all torsion-complete groups are characteristically inert socle-regular, which encompasses an achievement from the secondly mentioned paper and completely settles the problem posed there about this class of groups
The Non-local Kardar-Parisi-Zhang Equation With Spatially Correlated Noise
The effects of spatially correlated noise on a phenomenological equation
equivalent to a non-local version of the Kardar-Parisi-Zhang equation are
studied via the dynamic renormalization group (DRG) techniques. The correlated
noise coupled with the long ranged nature of interactions prove the existence
of different phases in different regimes, giving rise to a range of roughness
exponents defined by their corresponding critical dimensions. Finally
self-consistent mode analysis is employed to compare the non-KPZ exponents
obtained as a result of the long range -long range interactions with the DRG
results.Comment: Plain Latex, 10 pages, 2 figures in one ps fil
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