724 research outputs found
Toward the automation of business process ontology generation
Semantic Business Process Management (SBPM) utilises semantic technologies (e.g., ontology) to model and query process representations. There are times in which such models must be reconstructed from existing textual documentation. In this scenario the automated generation of ontological models would be preferable, however current methods and technology are still not capable of automatically generating accurate semantic process models from textual descriptions. This research attempts to automate the process as much as possible by proposing a method that drives the transformation through the joint use of a foundational ontology and lexico-semantic analysis. The method is presented, demonstrated and evaluated. The original dataset represents 150 business activities related to the procurement processes of a case study company. As the evaluation shows, the proposed method can accurately map the linguistic patterns of the process descriptions to semantic patterns of the foundational ontology to a high level of accuracy, however further research is required in order to reduce the level of human intervention, expand the method so as to recognise further patterns of the foundational ontology and develop a tool to assist the business process modeller in the semi-automated generation of process models
Probing the Intergalactic Medium with Fast Radio Bursts
The recently discovered fast radio bursts (FRBs), presumably of
extra-galactic origin, have the potential to become a powerful probe of the
intergalactic medium (IGM). We point out a few such potential applications. We
provide expressions for the dispersion measure and rotation measure as a
function of redshift, and we discuss the sensitivity of these measures to the
HeII reionization and the IGM magnetic field. Finally we calculate the
microlensing effect from an isolate, extragalctic stellar-mass compact object
on the FRB spectrum. The time delays between the two lensing images will induce
constructive and destructive interference, leaving a specific imprint on the
spectra of FRBs. With a high all-sky rate, a large statistical sample of FRBs
is expected to make these applications feasible.Comment: 4 pages, 1 figure; Typos for the variable x in Eq.6 corrected;
Published in ApJ; Originally the Appendix E of arXiv:1402.4766; Separated
from the main paper upon the referee's reques
Numerical simulation of super-square patterns in Faraday waves
We report the first simulations of the Faraday instability using the full
three-dimensional Navier-Stokes equations in domains much larger than the
characteristic wavelength of the pattern. We use a massively parallel code
based on a hybrid Front-Tracking/Level-set algorithm for Lagrangian tracking of
arbitrarily deformable phase interfaces. Simulations performed in rectangular
and cylindrical domains yield complex patterns. In particular, a
superlattice-like pattern similar to those of [Douady & Fauve, Europhys. Lett.
6, 221-226 (1988); Douady, J. Fluid Mech. 221, 383-409 (1990)] is observed. The
pattern consists of the superposition of two square superlattices. We
conjecture that such patterns are widespread if the square container is large
compared to the critical wavelength. In the cylinder, pentagonal cells near the
outer wall allow a square-wave pattern to be accommodated in the center
PoliMedia - Improving Analyses of Radio, TV & Newspaper Coverage of Political Debates
Abstract. Analysing media coverage across several types of media-outlets is a
challenging task for academic researchers. The PoliMedia project aimed to
showcase the potential of cross-media analysis by linking the digitised transcriptions
of the debates at the Dutch Parliament (Dutch Hansard) with three
media-outlets: 1) newspapers in their original layout of the historical newspaper
archive at the National Library, 2) radio bulletins of the Dutch National Press
Agency (ANP) and 3) newscasts and current affairs programs from the Netherlands
Institute for Sound and Vision. In this paper we describe generally how
these links were created and we introduce the PoliMedia search user interface
developed for scholars to navigate the links. In evaluation it was found that the
linking algorithm had a recall of 67% and precision of 75%. Moreover, in an
eye tracking evaluation we found that the interface enabled scholars to perform
known-item and exploratory searches for qualitative analysis
Evolution of Giant Planets in Eccentric Disks
We investigate the interaction between a giant planet and a viscous
circumstellar disk by means of high-resolution, two-dimensional hydrodynamical
simulations. We consider planet masses that range from 1 to 3 Jupiter masses
(Mjup) and initial orbital eccentricities that range from 0 to 0.4. We find
that a planet can cause eccentricity growth in a disk region adjacent to the
planet's orbit, even if the planet's orbit is circular. Disk-planet
interactions lead to growth in a planet's orbital eccentricity. The orbital
eccentricities of a 2 Mjup and a 3 Mjup planet increase from 0 to 0.11 within
about 3000 orbits. Over a similar time period, the orbital eccentricity of a 1
Mjup planet grows from 0 to 0.02. For a case of a 1 Mjup planet with an initial
eccentricity of 0.01, the orbital eccentricity grows to 0.09 over 4000 orbits.
Radial migration is directed inwards, but slows considerably as a planet's
orbit becomes eccentric. If a planet's orbital eccentricity becomes
sufficiently large, e > ~0.2, migration can reverse and so be directed
outwards. The accretion rate towards a planet depends on both the disk and the
planet orbital eccentricity and is pulsed over the orbital period. Planet mass
growth rates increase with planet orbital eccentricity. For e~0.2 the mass
growth rate of a planet increases by approximately 30% above the value for e=0.
For e > ~0.1, most of the accretion within the planet's Roche lobe occurs when
the planet is near the apocenter. Similar accretion modulation occurs for flow
at the inner disk boundary which represents accretion toward the star.Comment: 20 pages 16 figures, 3 tables. To appear in The Astrophysical Journal
vol.652 (December 1, 2006 issue
Kappa-deformed Snyder spacetime
We present Lie-algebraic deformations of Minkowski space with undeformed
Poincare algebra. These deformations interpolate between Snyder and
kappa-Minkowski space. We find realizations of noncommutative coordinates in
terms of commutative coordinates and derivatives. Deformed Leibniz rule, the
coproduct structure and star product are found. Special cases, particularly
Snyder and kappa-Minkowski in Maggiore-type realizations are discussed. Our
construction leads to a new class of deformed special relativity theories.Comment: 12 pages, no figures, LaTeX2e class file, accepted for publication in
Modern Physics Letters
Multiple-Planet Scattering and the Origin of Hot Jupiters
Exoplanets show a pile-up of Jupiter-size planets in orbits with a 3-day
period. A fraction of these hot Jupiters have retrograde orbits with respect to
the parent star's rotation. To explain these observations we performed a series
of numerical integrations of planet scattering followed by the tidal
circularization. We considered planetary systems having 3 and 4 planets
initially. We found that the standard Kozai migration is an inefficient
mechanism for the formation of hot Jupiters.
Our results show the formation of two distinct populations of hot Jupiters.
The inner population of hot Jupiters with semimajor axis a < 0.03 AU formed in
the systems where no planetary ejections occurred. This group contained a
significant fraction of highly inclined and retrograde orbits, with
distributions largely independent of the initial setup. However, our follow-up
integrations showed that this populations was transient with most planets
falling inside the Roche radius of the star in <1 Gyr. The outer population of
hot Jupiters formed in systems where at least one planet was ejected. This
population survived the effects of tides over >1 Gyr. The semimajor axis
distribution of Population II fits nicely the observed 3-day pile-up.
The inclination distribution of the outer hot planets depends on the number
of planets in the initial systems and the 4-planet case showed a larger
proportion (up to 10%), and a wider spread in inclination values. As the later
results roughly agrees with observations, this may suggest that the planetary
systems with observed hot Jupiters were originally rich in the number of
planets, some of which were ejected. In a broad perspective, our work therefore
hints on an unexpected link between the hot Jupiters and recently discovered
free floating planets.Comment: submitted to Ap
Color-Induced Displacement double stars in SDSS
We report the first successful application of the astrometric color-induced
displacement technique (CID, the displacement of the photocenter between
different bandpasses due to a varying contribution of differently colored
components to the total light), originally proposed by Wielen (1996) for
discovering unresolved binary stars. Using the Sloan Digital Sky Survey (SDSS)
Data Release 1 with 2.5 million stars brighter than 21m in the u and g bands,
we select 419 candidate binary stars with CID greater than 0.5 arcsec. The SDSS
colors of the majority of these candidates are consistent with binary systems
including a white dwarf and any main sequence star with spectral type later
than ~K7. The astrometric CID method discussed here is complementary to the
photometric selection of binary stars in SDSS discussed by Smolcic et al.
(2004), but there is considerable overlap (15%) between the two samples of
selected candidates. This overlap testifies both to the physical soundness of
both methods, as well as to the astrometric and photometric quality of SDSS
data.Comment: submitted to A&A, 13 pages, 6 figure
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