20,010 research outputs found
Using the Mass Storage System at ZIB within I3HP
In the framework of I3HP there are two Transnational Access Activities
related to Computational Hadron Physics. One of these activities is access to
the mass storage system at Konrad-Zuse-Zentrum fuer Informationstechnik Berlin
(ZIB). European lattice physics collaborations can apply for mass storage
capacity in order to store and share their configurations or other data (see
http://www.zib.de/i3hp/). In this paper formal and technical aspects of usage
as well as the conformance to the International Lattice DataGrid (ILDG) are
explained.Comment: Talk given at the Workshop on Computational Hadron Physics, Nicosia,
Cyprus, 14--17 September 200
Projet: Jet Cross Sections in Deeply Inelastic Electron Proton Scattering (VERSION 4.1)
PROJET is a parton level Monte Carlo program for the calculation of jet cross
sections in deeply inelastic electron proton scattering. In its present version
it contains the Born level diagrams for the production of (1+1), (2+1) and
(3+1) jets and the next-to-leading order corrections for the production cross
sections of (1+1) and (2+1) jets for all polarisations of the exchanged virtual
photon. In particular, the full angular correlations between the lepton and jet
momenta are implemented. The program permits the application of acceptance cuts
on all external momenta. For this purpose, the program creates an event record
accessible to the user program with all momenta in the laboratory frame and in
the center of momentum frame of the proton and the virtual photon. This option
is indispensable for phenomenological studies because of the strong dependence
of cross sections on phase space restrictions and the large uncertainty of
fragmentation corrections in the proton direction. Since PROJET uses the Monte
Carlo integration method for the evaluation of phase space integrals, the
weights of the generated events can be used to produce distributions of
observables related to jet momenta.Comment: 28 pages (LaTeX), CERN-TH.7420/9
Phenomenology Tools on Cloud Infrastructures using OpenStack
We present a new environment for computations in particle physics
phenomenology employing recent developments in cloud computing. On this
environment users can create and manage "virtual" machines on which the
phenomenology codes/tools can be deployed easily in an automated way. We
analyze the performance of this environment based on "virtual" machines versus
the utilization of "real" physical hardware. In this way we provide a
qualitative result for the influence of the host operating system on the
performance of a representative set of applications for phenomenology
calculations.Comment: 25 pages, 12 figures; information on memory usage included, as well
as minor modifications. Version to appear in EPJ
The AliEn system, status and perspectives
AliEn is a production environment that implements several components of the
Grid paradigm needed to simulate, reconstruct and analyse HEP data in a
distributed way. The system is built around Open Source components, uses the
Web Services model and standard network protocols to implement the computing
platform that is currently being used to produce and analyse Monte Carlo data
at over 30 sites on four continents. The aim of this paper is to present the
current AliEn architecture and outline its future developments in the light of
emerging standards.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 10 pages, Word, 10 figures. PSN
MOAT00
The Fractured Memory of a Mind’s Eye
The work I create is informed by questioning reality/identity, the fractalizing planes
of existence our essence occupies, and the artifacts of memory experience navigating
through space time. While existing in this realm of oversaturated media and neon
glow, I question the effects of pervasive data systems overloading or programming the
mental software we possess. My work includes humor as a means of exploring these
conventions while also displaying psychedelic surrealist imagery to help break away
from the conscious prison this existence births our concept apparatuses within
IVOA Recommendation: VOTable Format Definition Version 1.3
This document describes the structures making up the VOTable standard. The
main part of this document describes the adopted part of the VOTable standard;
it is followed by appendices presenting extensions which have been proposed
and/or discussed, but which are not part of the standard
Optimal Compression of Floating-point Astronomical Images Without Significant Loss of Information
We describe a compression method for floating-point astronomical images that
gives compression ratios of 6 -- 10 while still preserving the scientifically
important information in the image. The pixel values are first preprocessed by
quantizing them into scaled integer intensity levels, which removes some of the
uncompressible noise in the image. The integers are then losslessly compressed
using the fast and efficient Rice algorithm and stored in a portable FITS
format file. Quantizing an image more coarsely gives greater image compression,
but it also increases the noise and degrades the precision of the photometric
and astrometric measurements in the quantized image. Dithering the pixel values
during the quantization process can greatly improve the precision of
measurements in the images. This is especially important if the analysis
algorithm relies on the mode or the median which would be similarly quantized
if the pixel values are not dithered. We perform a series of experiments on
both synthetic and real astronomical CCD images to quantitatively demonstrate
that the magnitudes and positions of stars in the quantized images can be
measured with the predicted amount of precision. In order to encourage wider
use of these image compression methods, we have made available a pair of
general-purpose image compression programs, called fpack and funpack, which can
be used to compress any FITS format image.Comment: Accepted PAS
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