2,071 research outputs found
The State of Self-Organized Criticality of the Sun During the Last 3 Solar Cycles. I. Observations
We analyze the occurrence frequency distributions of peak fluxes , total
fluxes , and durations of solar flares over the last three solar cycles
(during 1980--2010) from hard X-ray data of HXRBS/SMM, BATSE/CGRO, and RHESSI.
From the synthesized data we find powerlaw slopes with mean values of
for the peak flux, for the total
flux, and for flare durations. We find a systematic
anti-correlation of the powerlaw slope of peak fluxes as a function of the
solar cycle, varying with an approximate sinusoidal variation
, with a
mean of , a variation of , a solar cycle
period yrs, and a cycle minimum time . The
powerlaw slope is flattest during the maximum of a solar cycle, which indicates
a higher magnetic complexity of the solar corona that leads to an
overproportional rate of powerful flares.Comment: subm. to Solar Physic
A UML Profile for the Design, Quality Assessment and Deployment of Data-intensive Applications
Big Data or Data-Intensive applications (DIAs) seek to mine, manipulate, extract or otherwise exploit the potential intelligence hidden behind Big Data. However, several practitioner surveys remark that DIAs potential is still untapped because of very difficult and costly design, quality assessment and continuous refinement. To address the above shortcoming, we propose the use of a UML domain-specific modeling language or profile specifically tailored to support the design, assessment and continuous deployment of DIAs. This article illustrates our DIA-specific profile and outlines its usage in the context of DIA performance engineering and deployment. For DIA performance engineering, we rely on the Apache Hadoop technology, while for DIA deployment, we leverage the TOSCA language. We conclude that the proposed profile offers a powerful language for data-intensive software and systems modeling, quality evaluation and automated deployment of DIAs on private or public clouds
On the Exact Evaluation of Certain Instances of the Potts Partition Function by Quantum Computers
We present an efficient quantum algorithm for the exact evaluation of either
the fully ferromagnetic or anti-ferromagnetic q-state Potts partition function
Z for a family of graphs related to irreducible cyclic codes. This problem is
related to the evaluation of the Jones and Tutte polynomials. We consider the
connection between the weight enumerator polynomial from coding theory and Z
and exploit the fact that there exists a quantum algorithm for efficiently
estimating Gauss sums in order to obtain the weight enumerator for a certain
class of linear codes. In this way we demonstrate that for a certain class of
sparse graphs, which we call Irreducible Cyclic Cocycle Code (ICCC_\epsilon)
graphs, quantum computers provide a polynomial speed up in the difference
between the number of edges and vertices of the graph, and an exponential speed
up in q, over the best classical algorithms known to date
Calibration of Smearing and Cooling Algorithms in SU(3)-Color Gauge Theory
The action and topological charge are used to determine the relative rates of
standard cooling and smearing algorithms in pure SU(3)-color gauge theory. We
consider representative gauge field configurations on lattices
at and lattices at . We find the
relative rate of variation in the action and topological charge under various
algorithms may be succinctly described in terms of simple formulae. The results
are in accord with recent suggestions from fat-link perturbation theory.Comment: RevTeX, 25 pages, 22 figures, full resolution jpeg version of Fig. 22
can be obtained from
http://www.physics.adelaide.edu.au/cssm/papers_etc/SmearingComp.jp
Relative Equilibria in the Four-Vortex Problem with Two Pairs of Equal Vorticities
We examine in detail the relative equilibria in the four-vortex problem where
two pairs of vortices have equal strength, that is, \Gamma_1 = \Gamma_2 = 1 and
\Gamma_3 = \Gamma_4 = m where m is a nonzero real parameter. One main result is
that for m > 0, the convex configurations all contain a line of symmetry,
forming a rhombus or an isosceles trapezoid. The rhombus solutions exist for
all m but the isosceles trapezoid case exists only when m is positive. In fact,
there exist asymmetric convex configurations when m < 0. In contrast to the
Newtonian four-body problem with two equal pairs of masses, where the symmetry
of all convex central configurations is unproven, the equations in the vortex
case are easier to handle, allowing for a complete classification of all
solutions. Precise counts on the number and type of solutions (equivalence
classes) for different values of m, as well as a description of some of the
bifurcations that occur, are provided. Our techniques involve a combination of
analysis and modern and computational algebraic geometry
A New Recursion Relation for the 6j-Symbol
The 6j-symbol is a fundamental object from the re-coupling theory of SU(2)
representations. In the limit of large angular momenta, its asymptotics is
known to be described by the geometry of a tetrahedron with quantized lengths.
This article presents a new recursion formula for the square of the 6j-symbol.
In the asymptotic regime, the new recursion is shown to characterize the
closure of the relevant tetrahedron. Since the 6j-symbol is the basic building
block of the Ponzano-Regge model for pure three-dimensional quantum gravity, we
also discuss how to generalize the method to derive more general recursion
relations on the full amplitudes.Comment: 10 pages, v2: title and introduction changed, paper re-structured;
Annales Henri Poincare (2011
Instantons and Condensate
We argue that the is similar to .Comment: 6 pages, 1 fig., 1 tab., RevTeX to be use
Precision charging of microparticles in plasma via the Rayleigh instability for evaporating charged liquid droplets
In this paper we describe a novel method for delivering a precise, known amount of electric charge to a micron-sized solid target. Aerosolised microparticles passed through a plasma discharge will acquire significant electric charge. The fluid stability under evaporative stress is a key aspect that is core to the research. Initially stable charged aerosols subject to evaporation (i.e. a continually changing radius) may encounter the Rayleigh stability limit. This limit arises from the electrostatic and surface tension forces and determines the maximum charge a stable droplet can retain, as a function of radius. We demonstrate that even if the droplet charge is initially much less than the Rayleigh limit, the stability limit will be encountered as the droplet evaporates. The instability emission mechanism is strongly linked to the final charge deposited on the target, providing a mechanism that can be used to ensure a predictable charge deposit on a known encapsulated microparticle
The First VERITAS Telescope
The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic
Radiation Imaging Telescope Array System) has been in operation since February
2005. We present here a technical description of the instrument and a summary
of its performance. The calibration methods are described, along with the
results of Monte Carlo simulations of the telescope and comparisons between
real and simulated data. The analysis of TeV -ray observations of the
Crab Nebula, including the reconstructed energy spectrum, is shown to give
results consistent with earlier measurements. The telescope is operating as
expected and has met or exceeded all design specifications.Comment: Accepted by Astroparticle Physic
Abelian Monopole and Center Vortex Views at the Multi-Instanton Gas
We consider full non-Abelian, Abelian and center projected lattice field
configurations built up from random instanton gas configurations in the
continuum. We study the instanton contribution to the force with
respect to ({\it i}) instanton density dependence, ({\it ii}) Casimir scaling
and ({\it iii}) whether various versions of Abelian dominance hold. We check
that the dilute gas formulation for the interaction potential gives an reliable
approximation only for densities small compared to the phenomenological value.
We find that Casimir scaling does not hold, confirming earlier statements in
the literature. We show that the lattice used to discretize the instanton gas
configurations has to be sufficiently coarse ( compared
with the instanton size ) such that maximal Abelian gauge
projection and center projection as well as the monopole gas contribution to
the force reproduce the non-Abelian instanton-mediated force in the
intermediate range of linear quasi-confinement. We demonstrate that monopole
clustering also depends critically on the discretization scale confirming
earlier findings based on monopole blocking.Comment: 21 pages, 22 Postscript figure
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