116,069 research outputs found
Enhancing Energy Production with Exascale HPC Methods
High Performance Computing (HPC) resources have become the key actor for achieving more ambitious challenges in many disciplines. In this step beyond, an explosion on the available parallelism and the use of special purpose
processors are crucial. With such a goal, the HPC4E project applies new exascale HPC techniques to energy industry simulations, customizing them if necessary, and going beyond the state-of-the-art in the required HPC exascale
simulations for different energy sources. In this paper, a general overview of these methods is presented as well as some specific preliminary results.The research leading to these results has received funding from the European Union's Horizon 2020 Programme (2014-2020) under the HPC4E Project (www.hpc4e.eu), grant agreement n° 689772, the Spanish Ministry of
Economy and Competitiveness under the CODEC2 project (TIN2015-63562-R), and
from the Brazilian Ministry of Science, Technology and Innovation through Rede
Nacional de Pesquisa (RNP). Computer time on Endeavour cluster is provided by the
Intel Corporation, which enabled us to obtain the presented experimental results in
uncertainty quantification in seismic imagingPostprint (author's final draft
Multiscale Discriminant Saliency for Visual Attention
The bottom-up saliency, an early stage of humans' visual attention, can be
considered as a binary classification problem between center and surround
classes. Discriminant power of features for the classification is measured as
mutual information between features and two classes distribution. The estimated
discrepancy of two feature classes very much depends on considered scale
levels; then, multi-scale structure and discriminant power are integrated by
employing discrete wavelet features and Hidden markov tree (HMT). With wavelet
coefficients and Hidden Markov Tree parameters, quad-tree like label structures
are constructed and utilized in maximum a posterior probability (MAP) of hidden
class variables at corresponding dyadic sub-squares. Then, saliency value for
each dyadic square at each scale level is computed with discriminant power
principle and the MAP. Finally, across multiple scales is integrated the final
saliency map by an information maximization rule. Both standard quantitative
tools such as NSS, LCC, AUC and qualitative assessments are used for evaluating
the proposed multiscale discriminant saliency method (MDIS) against the
well-know information-based saliency method AIM on its Bruce Database wity
eye-tracking data. Simulation results are presented and analyzed to verify the
validity of MDIS as well as point out its disadvantages for further research
direction.Comment: 16 pages, ICCSA 2013 - BIOCA sessio
Fast and Accurate Simulation Technique for Large Irregular Arrays
A fast full-wave simulation technique is presented for the analysis of large
irregular planar arrays of identical 3-D metallic antennas. The solution method
relies on the Macro Basis Functions (MBF) approach and an interpolatory
technique to compute the interactions between MBFs. The Harmonic-polynomial
(HARP) model is established for the near-field interactions in a modified
system of coordinates. For extremely large arrays made of complex antennas, two
approaches assuming a limited radius of influence for mutual coupling are
considered: one is based on a sparse-matrix LU decomposition and the other one
on a tessellation of the array in the form of overlapping sub-arrays. The
computation of all embedded element patterns is sped up with the help of the
non-uniform FFT algorithm. Extensive validations are shown for arrays of
log-periodic antennas envisaged for the low-frequency SKA (Square Kilometer
Array) radio-telescope. The analysis of SKA stations with such a large number
of elements has not been treated yet in the literature. Validations include
comparison with results obtained with commercial software and with experiments.
The proposed method is particularly well suited to array synthesis, in which
several orders of magnitude can be saved in terms of computation time.Comment: The paper was submitted to IEEE Transaction on Antennas and
Propagation on 01 - Feb.- 2017. The paper is 12 pages with 18 figure
ATK-ForceField: A New Generation Molecular Dynamics Software Package
ATK-ForceField is a software package for atomistic simulations using
classical interatomic potentials. It is implemented as a part of the Atomistix
ToolKit (ATK), which is a Python programming environment that makes it easy to
create and analyze both standard and highly customized simulations. This paper
will focus on the atomic interaction potentials, molecular dynamics, and
geometry optimization features of the software, however, many more advanced
modeling features are available. The implementation details of these algorithms
and their computational performance will be shown. We present three
illustrative examples of the types of calculations that are possible with
ATK-ForceField: modeling thermal transport properties in a silicon germanium
crystal, vapor deposition of selenium molecules on a selenium surface, and a
simulation of creep in a copper polycrystal.Comment: 28 pages, 9 figure
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