192,658 research outputs found
GATE simulation for medical physics with genius Web portal
présenté par C. ThiamPCSV team of the LPC laboratory in Clermont-Ferrand is involved in the deployment of biomedical applications on the grid architecture. One of these applications deals with the deployment of GATE (Geant4 Application for Tomographic Emission) for medical physics application. The aim of the developments actually performed is to enable an application of the GATE platform in clinical routine. However, this perspective is only possible if the computing time and user time are highly reduced. The new grid architecture, developed within the framework of the European project Enabling Grid for E-sciencE (EGEE) is there to answer this requirement. The use of the grid resources must be transparent easy and rapid for the medical physicists. For this perpose, we adapted the GENIUS web portal in order to facilitate the GATE simulations planning on the grid. We will present a demonstration of the GENIUS portal which integrates all the functionalities of EGEE: to create, to submit and manage GATE jobs on the grid architecture. Our GATE activities for dosimetry application entered in to direct phase of evaluation by the cancer treatment center of Clermont Ferrand (Centre Jean perrin).A work station is currently available in this center to test the use of GATE application on the grid through GENIUS. This portal will allow in a long term to use GATE application in brachytherapy and radiotherapy treatment planning using medical data (medical images, DICOM, binary data dose calculation in the heterogeneous mediums) and to analyze the results obtained in visual form. Other functionalities are under development and will make possible to register medical data on grid storages elements and to manage them. However, these data must be anonymised before their recording on the grid. Their access via the GENIUS portal must be made safe and fast (compared simulation computing time). In order to be sure that the medical data are accessible for calculations, their replication on various storage element (SE) should be possible. The grid services give the possibility of managing this information in a free way and transparently. Operations of data handling and catalogues on the grid are ensured by the Replica Manager system which integrates all tools making it possible to manage data on the grid. The computing grid give promising results and meet a definite need: reach acceptable computing time for a future use of Monte Carlo simulations for treatment planning in brachytherapy and radiotherapy
Replica Selection in the Globus Data Grid
The Globus Data Grid architecture provides a scalable infrastructure for the
management of storage resources and data that are distributed across Grid
environments. These services are designed to support a variety of scientific
applications, ranging from high-energy physics to computational genomics, that
require access to large amounts of data (terabytes or even petabytes) with
varied quality of service requirements. By layering on a set of core services,
such as data transport, security, and replica cataloging, one can construct
various higher-level services. In this paper, we discuss the design and
implementation of a high-level replica selection service that uses information
regarding replica location and user preferences to guide selection from among
storage replica alternatives. We first present a basic replica selection
service design, then show how dynamic information collected using Globus
information service capabilities concerning storage system properties can help
improve and optimize the selection process. We demonstrate the use of Condor's
ClassAds resource description and matchmaking mechanism as an efficient tool
for representing and matching storage resource capabilities and policies
against application requirements.Comment: 8 pages, 6 figure
AstroGrid-D: Grid Technology for Astronomical Science
We present status and results of AstroGrid-D, a joint effort of
astrophysicists and computer scientists to employ grid technology for
scientific applications. AstroGrid-D provides access to a network of
distributed machines with a set of commands as well as software interfaces. It
allows simple use of computer and storage facilities and to schedule or monitor
compute tasks and data management. It is based on the Globus Toolkit middleware
(GT4). Chapter 1 describes the context which led to the demand for advanced
software solutions in Astrophysics, and we state the goals of the project. We
then present characteristic astrophysical applications that have been
implemented on AstroGrid-D in chapter 2. We describe simulations of different
complexity, compute-intensive calculations running on multiple sites, and
advanced applications for specific scientific purposes, such as a connection to
robotic telescopes. We can show from these examples how grid execution improves
e.g. the scientific workflow. Chapter 3 explains the software tools and
services that we adapted or newly developed. Section 3.1 is focused on the
administrative aspects of the infrastructure, to manage users and monitor
activity. Section 3.2 characterises the central components of our architecture:
The AstroGrid-D information service to collect and store metadata, a file
management system, the data management system, and a job manager for automatic
submission of compute tasks. We summarise the successfully established
infrastructure in chapter 4, concluding with our future plans to establish
AstroGrid-D as a platform of modern e-Astronomy.Comment: 14 pages, 12 figures Subjects: data analysis, image processing,
robotic telescopes, simulations, grid. Accepted for publication in New
Astronom
A Practical Searchable Symmetric Encryption Scheme for Smart Grid Data
Outsourcing data storage to the remote cloud can be an economical solution to
enhance data management in the smart grid ecosystem. To protect the privacy of
data, the utility company may choose to encrypt the data before uploading them
to the cloud. However, while encryption provides confidentiality to data, it
also sacrifices the data owners' ability to query a special segment in their
data. Searchable symmetric encryption is a technology that enables users to
store documents in ciphertext form while keeping the functionality to search
keywords in the documents. However, most state-of-the-art SSE algorithms are
only focusing on general document storage, which may become unsuitable for
smart grid applications. In this paper, we propose a simple, practical SSE
scheme that aims to protect the privacy of data generated in the smart grid.
Our scheme achieves high space complexity with small information disclosure
that was acceptable for practical smart grid application. We also implement a
prototype over the statistical data of advanced meter infrastructure to show
the effectiveness of our approach
Managing community membership information in a small-world grid
As the Grid matures the problem of resource discovery across communities,
where resources now include computational services, is becoming more
critical. The number of resources available on a world-wide grid is set to grow
exponentially in much the same way as the number of static web pages on
the WWW. We observe that the world-wide resource discovery problem can
be modelled as a slowly evolving very-large sparse-matrix where individual
matrix elements represent nodes’ knowledge of one another. Blocks in the
matrix arise where nodes offer more than one service. Blocking effects also
arise in the identification of sub-communities in the Grid. The linear algebra
community has long been aware of suitable representations of large, sparse
matrices. However, matrices the size of the world-wide grid potentially number
in the billions, making dense solutions completely intractable. Distributed
nodes will not necessarily have the storage capacity to store the addresses of
any significant percentage of the available resources. We discuss ways of modelling
this problem in the regime of a slowly changing service base including
phenomena such as percolating networks and small-world network effects
HEP Applications Evaluation of the EDG Testbed and Middleware
Workpackage 8 of the European Datagrid project was formed in January 2001
with representatives from the four LHC experiments, and with experiment
independent people from five of the six main EDG partners. In September 2002
WP8 was strengthened by the addition of effort from BaBar and D0. The original
mandate of WP8 was, following the definition of short- and long-term
requirements, to port experiment software to the EDG middleware and testbed
environment. A major additional activity has been testing the basic
functionality and performance of this environment. This paper reviews
experiences and evaluations in the areas of job submission, data management,
mass storage handling, information systems and monitoring. It also comments on
the problems of remote debugging, the portability of code, and scaling problems
with increasing numbers of jobs, sites and nodes. Reference is made to the
pioneeering work of Atlas and CMS in integrating the use of the EDG Testbed
into their data challenges. A forward look is made to essential software
developments within EDG and to the necessary cooperation between EDG and LCG
for the LCG prototype due in mid 2003.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
Conference (CHEP03), La Jolla, CA, USA, March 2003, 7 pages. PSN THCT00
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