1,721,087 research outputs found
A Dynamic Earth Observation System
No full textThe paper presents an overview of SARA/Digital Puglia (Synthetic Aperture Radar Atlas), a remote sensing environment that shows how grid technologies and high performance com- puting can be efficiently used to build dynamic earth observation systems for the management of huge quantities of data coming from space missions and for their on-demand processing and delivering to final users. SARA/Digital Puglia is a grid-enabled, high performance digital library of remote sensing images, developed in a joint research project with CACR/Caltech, ISI/USC and the Italian Space Agency
Early experiences with the EGrid testbed
No full textThe Testbed and Applications working group of the European Grid Forum (EGrid) is actively building and experimenting with a grid infrastructure connecting several research-based supercomputing sites located in Europe. The paper reports on our first feasibility study: running a self-migrating version of the Cactus simulation code across the European grid testbed, including “live” remote data visualization and steering from different demonstration booths at Supercomputing 2000, in Dallas, TX. We report on the problems that had to be resolved for this endeavour and identify open research challenges for building production-grade grid environments
Special Issue: 3rd International Workshop on Workflow Management and Applications in Grid Environments (WaGe2008)
No full textMerging Frequent Summaries
Full text linkRecently, an algorithm for merging counter-based data sum- maries which are the output of the Frequent algorithm (Frequent summaries) has been proposed by Agarwal et al. In this paper, we present a new algorithm for merging Frequent summaries. Our algorithm is fast and simple to implement, and retains the same computational complexity of the algorithm presented by Agarwal et al. while providing better frequency estimation
Parallel damage detection through finite frequency changes on multicore processors
No full textThis manuscript deals with a novel approach aimed at identifying multiple damaged sites in structural components through finite frequency changes. Natural frequencies, meant as a privileged set of modal data, are adopted along with a numerical model of the system. The adoption of finite changes efficiently allows challenging characteristic problems encountered in damage detection techniques such as unexpected comparison of possible shifted modes and the significance of modal data changes very often affected by experimental/environmental noise. The new procedure extends MDLAC and exploits parallel computing on modern multicore processors. Smart filters, aimed at reducing the potential damaged sites, are implemented in order to reduce the computational effort. Several use cases are presented in order to illustrate the potentiality of the new damage detection procedure
Early experiences with the GridFTP protocol using the GRB-GSIFTP library
No full textThe ISUFI/High Performance Computing Centre is actively experimenting with a grid infrastructure connecting sites located both in Europe and in the USA. This paper reports on our feasibility study related to the use of the GridFTP protocol for high performance data transfers. We also describe a client library we are developing to provide additional services beyond those provided by the Globus ftp client library and to ease code development
The Desktop Grid Environment Enabler
No full textThis paper describes our Desktop Grid Environment Enabler (DEGREE), a set of Web Services that provides advanced capabilities for grid computing. DEGREE services are based both on the Globus Toolkit and the Grid Resource Broker, a grid portal developed at the University of Lecce. Trusted users can develop innovative, grid-aware applications that seamlessly access computational resources and services exploiting our Web Services independently of platform and programming language
Preference-based Matchmaking of Grid Resources With CP-Nets
Full text linkWe deal with the problem of preference-based matchmaking of computational resources belonging to a grid. We introduce CP–Nets, a recent development in the field of Artificial Intelligence, as a means to deal with user’s preferences in the context of grid scheduling. We discuss CP–Nets from a theoretical perspective and then analyze, qualitatively and quantitatively, their impact on the matchmaking process, with the help of a grid simulator we developed for this purpose. Many different experiments have been setup and carried out, and we report here our main findings and the lessons learnt
A Parallel Space Saving Algorithm For Frequent Items and the Hurwitz zeta distribution
Full text linkWe present a message-passing based parallel version of the Space Saving
algorithm designed to solve the --majority problem. The algorithm determines
in parallel frequent items, i.e., those whose frequency is greater than a given
threshold, and is therefore useful for iceberg queries and many other different
contexts. We apply our algorithm to the detection of frequent items in both
real and synthetic datasets whose probability distribution functions are a
Hurwitz and a Zipf distribution respectively. Also, we compare its parallel
performances and accuracy against a parallel algorithm recently proposed for
merging summaries derived by the Space Saving or Frequent algorithms
Metodo e formalismo per inviare istruzioni a DataBase distribuiti realizzato mediante programma per computer
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