8,580 research outputs found
Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere Program
We describe the parallel implementation of our generalized stellar atmosphere
and NLTE radiative transfer computer program PHOENIX. We discuss the parallel
algorithms we have developed for radiative transfer, spectral line opacity, and
NLTE opacity and rate calculations. Our implementation uses a MIMD design based
on a relatively small number of MPI library calls. We report the results of
test calculations on a number of different parallel computers and discuss the
results of scalability tests.Comment: To appear in ApJ, 1997, vol 483. LaTeX, 34 pages, 3 Figures, uses
AASTeX macros and styles natbib.sty, and psfig.st
Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
Quantum ESPRESSO is an integrated suite of computer codes for
electronic-structure calculations and materials modeling, based on
density-functional theory, plane waves, and pseudopotentials (norm-conserving,
ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn
Source Package for Research in Electronic Structure, Simulation, and
Optimization". It is freely available to researchers around the world under the
terms of the GNU General Public License. Quantum ESPRESSO builds upon
newly-restructured electronic-structure codes that have been developed and
tested by some of the original authors of novel electronic-structure algorithms
and applied in the last twenty years by some of the leading materials modeling
groups worldwide. Innovation and efficiency are still its main focus, with
special attention paid to massively-parallel architectures, and a great effort
being devoted to user friendliness. Quantum ESPRESSO is evolving towards a
distribution of independent and inter-operable codes in the spirit of an
open-source project, where researchers active in the field of
electronic-structure calculations are encouraged to participate in the project
by contributing their own codes or by implementing their own ideas into
existing codes.Comment: 36 pages, 5 figures, resubmitted to J.Phys.: Condens. Matte
Implementing and Running a Workflow Application on Cloud Resources
Scientist need to run applications that are time and resource consuming, but, not all of them, have the requires knowledge to run this applications in a parallel manner, by using grid, cluster or cloud resources. In the past few years many workflow building frameworks were developed in order to help scientist take a better advantage of computing resources, by designing workflows based on their applications and executing them on heterogeneous resources. This paper presents a case study of implementing and running a workflow for an E-bay data retrieval application. The workflow was designed using Askalon framework and executed on the cloud resources. The purpose of this paper is to demonstrate how workflows and cloud resources can be used by scientists in order to achieve speedup for their application without the need of spending large amounts of money on computational resources.Workflow, Cloud Resource
A pencil distributed finite difference code for strongly turbulent wall-bounded flows
We present a numerical scheme geared for high performance computation of
wall-bounded turbulent flows. The number of all-to-all communications is
decreased to only six instances by using a two-dimensional (pencil) domain
decomposition and utilizing the favourable scaling of the CFL time-step
constraint as compared to the diffusive time-step constraint. As the CFL
condition is more restrictive at high driving, implicit time integration of the
viscous terms in the wall-parallel directions is no longer required. This
avoids the communication of non-local information to a process for the
computation of implicit derivatives in these directions. We explain in detail
the numerical scheme used for the integration of the equations, and the
underlying parallelization. The code is shown to have very good strong and weak
scaling to at least 64K cores
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