Computer Science
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ISSN 1508-2806
e-ISSN: 2300-7036
Issue Date
2015
Volume
Vol. 16
Number
No. 1
Description
Reviewed by: Enrique Costa Montenegro, Rodolfo Villarroel, Ouanes Aissaoui, Diego Casadei, Jacek Kitowski, Mariusz Sterzel, Michele Floris, Roberto Preghenella, Manuj Darbari, Jocelyn Simmonds, Mikhail Moshkov, Jan Kucwaj, Mariusz Flasiński, Piotr Gawron, Ali JavadiAbhari
Journal Volume
Computer Science
Vol. 16 (2015)
Projects
Pages
Articles
Model of reconfiguration in component environments
(Wydawnictwa AGH, 2015) Grzesiak, Jakub; Jędrychowski, Łukasz
The significance of component-based software and component platforms has increased over the last twenty years. To achieve full flexibility, a reconfiguration process is needed that allows us to change system parameters without rebuilding or restarting. In terms of components, such a process should be executed with extraordinary care, since the contracts between components must be preserved. In this article, a model of reconfiguration (including the roles of the components to be used in this process) is proposed. The provided solution is general and could be applied to many component platforms.
Confronting theoretical predictions with experimental data, a fitting strategy for multi-dimensional distributions
(Wydawnictwa AGH, 2015) Przedziński, Tomasz; Roig Garcés, Pablo; Šehovcova, Ol'ga; Wąs, Zbigniew; Zaremba, Jakub
After developing a Resonance Chiral Lagrangian (R?L) model to describe hadronic ? lepton decays, the model was confronted with experimental data. This was accomplished by using a fitting framework that was developed to take into account the complexity of the model and to ensure numerical stability for the algorithms used in the fitting. Since the model used in the fit contained 15 parameters and there were only three one-dimensional distributions available, we could expect multiple local minima or even whole regions of equal potential to appear. Our methods had to thoroughly explore the whole parameter space and ensure (as well as possible) that the result is a global minimum. This paper is focused on the technical aspects of the fitting strategy used. The first approach was based on a re-weighting algorithm published in article Shekhovtsova et al. and produced results in about two weeks. A later approach, with an improved theoretical model and a simple parallelization algorithm based on Inter-Process Communication (IPC) methods of UNIX system, reduced computation time down to 2–3 days. Additional approximations were introduced to the model, decreasing the necessary time to obtain the preliminary results down to 8 hours. This allowed us to better validate the results, leading to a more robust analysis published in article Nugent et al.
Computational challenges in the measurement of heavy-ion collision event characteristics with the atlas experiment at the LHC
(Wydawnictwa AGH, 2015) Maj, Klaudia; Bołd, Tomasz; Grabowska-Bołd, Iwona
Heavy-ion collisions at extreme energies are expected to recreate conditions present in the early universe, producing a state of matter called the Quark Gluon Plasma (QGP). This state is characterized by very low viscosity resembling the properties of a perfect fluid. In such a medium, density fluctuations can easily propagate. In experimental practice, the size of these fluctuations is estimated by measuring the angular correlation of the particles produced. The aim of this paper is to present results of the measurements of the azimuthal anisotropy of charged particles produced in heavy-ion collisions with the ATLAS detector using the LHC Grid infrastructure for bulk processing of the data and resources available at the Tier-2 computing center for the final analysis stage.
Distributed Web service repository
(Wydawnictwa AGH, 2015) Nawrocki, Piotr; Mamla, Aleksander
The increasing availability and popularity of computer systems has resulted in a demand for new language- and platform-independent ways of data exchange. This demand has, in turn, led to significant growth in the importance of systems based on Web services. Alongside the growing number of systems accessible via Web services came the need for specialized data repositories that could offer effective means of searching the available services. The development of mobile systems and wireless data transmission technologies has allowed us to use distributed devices and computer systems on a greater scale. The accelerating growth of distributed systems might be a good reason to consider the development of distributed Web service repositories with built-in mechanisms for data migration and synchronization.
Hypergrammar-based parallel multi-frontal solver for Grids with point singularities
(Wydawnictwa AGH, 2015) Gurgul, Piotr; Paszyński, Maciej; Paszyńska, Anna
This paper describes the application of hypergraph grammars to drive a linear computational cost solver for grids with point singularities. Such graph grammar productions are the first mathematical formalisms used to describe solver algorithms, and each indicates the smallest atomic task that can be executed in parallel, which is very useful in the case of parallel execution. In particular, the partial order of execution of graph grammar productions can be found, and the sets of independent graph grammar productions can be localized. They can be scheduled set by set into a shared memory parallel machine. The graphgrammar-based solver has been implemented with NVIDIA CUDA for GPU. Graph grammar productions are accompanied by numerical results for a 2D case. We show that our graph-grammar-based solver with a GPU accelerator is, by order of magnitude, faster than the state-of-the-art MUMPS solver.