2,526 research outputs found
Interoperability and Standards: The Way for Innovative Design in Networked Working Environments
Organised by: Cranfield UniversityIn today’s networked economy, strategic business partnerships and outsourcing has become the dominant
paradigm where companies focus on core competencies and skills, as creative design, manufacturing, or
selling. However, achieving seamless interoperability is an ongoing challenge these networks are facing,
due to their distributed and heterogeneous nature. Part of the solution relies on adoption of standards for
design and product data representation, but for sectors predominantly characterized by SMEs, such as the
furniture sector, implementations need to be tailored to reduce costs. This paper recommends a set of best
practices for the fast adoption of the ISO funStep standard modules and presents a framework that enables
the usage of visualization data as a way to reduce costs in manufacturing and electronic catalogue design.Mori Seiki – The Machine Tool Compan
Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters II. Berkeley 23, King 1, NGC 559, NGC 6603 and NGC 7245
Context: Open clusters are key to studying the formation and evolution of the
Galactic disc. However, there is a deficiency of radial velocity and chemical
abundance determinations for open clusters in the literature. Aims: We intend
to increase the number of determinations of radial velocities and metallicities
from spectroscopy for open clusters. Methods: We acquired medium-resolution
spectra (R~8000) in the infrared region Ca II triplet lines (~8500 AA) for
several stars in five open clusters with the long-slit IDS spectrograph on the
2.5~m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain).
Radial velocities were obtained by cross-correlation fitting techniques. The
relationships available in the literature between the strength of infrared Ca
II lines and metallicity were also used to derive the metallicity for each
cluster. Results: We obtain = 48.6+/-3.4, -58.4+/-6.8, 26.0+/-4.3 and
-65.3+/-3.2 km s-1 for Berkeley 23, NGC 559, NGC 6603 and NGC 7245,
respectively. We found [Fe/H] =-0.25+/-0.14 and -0.15+/-0.18 for NGC 559 and
NGC 7245, respectively. Berkeley 23 has a low metallicity, [Fe/H]
=-0.42+/-0.13, similar to other open clusters in the outskirts of the Galactic
disc. In contrast, we derived a high metallicity ([Fe/H] =+0.43+/-0.15) for NGC
6603, which places this system among the most metal rich known open clusters.
To our knowledge, this is the first determination of radial velocities and
metallicities from spectroscopy for these clusters, except NGC 6603, for which
radial velocities had been previously determined. We have also analysed ten
stars in the line of sight to King 1. Because of the large dispersion obtained
in both radial velocity and metallicity, we cannot be sure that we have sampled
true cluster members.Comment: 10 pages, 5 figures, accepted for publication in A&A (minor
modifications
Photometric reverberation mapping of 3C120
We present the results of a five month monitoring campaign of the local
active galactic nuclei (AGN) 3C120. Observations with a median sampling of two
days were conducted with the robotic 15cm telescope VYSOS-6 located near Cerro
Armazones in Chile. Broad band (B,V) and narrow band (NB) filters were used in
order to measure fluxes of the AGN and the H_beta broad line region (BLR)
emission line. The NB flux is constituted by about 50% continuum and 50% H_beta
emission line. To disentangle line and continuum flux, a synthetic H_beta light
curve was created by subtracting a scaled V-band light curve from the NB light
curve. Here we show that the H_beta emission line responds to continuum
variations with a rest frame lag of 23.6 +/- 1.69 days. We estimate a virial
mass of the central black hole M_BH = 57 +/- 27 * 10^6 solar masses, by
combining the obtained lag with the velocity dispersion of a single
contemporaneous spectrum. Using the flux variation gradient (FVG) method, we
determined the host galaxy subtracted rest frame 5100A luminosity at the time
of our monitoring campaign with an uncertainty of 10% (L_AGN = 6.94 +/- 0.71*
10^43 ergs^-1). Compared with recent spectroscopic reverberation results, 3C120
shifts in the R_BLR - L_AGN diagram remarkably close to the theoretically
expected relation of R-L^0.5. Our results demonstrate the performance of
photometric AGN reverberation mapping, in particular for efficiently
determining the BLR size and the AGN luminosityComment: 11 pages, 11 figures, Published in Astronomy and Astrophysic
Circumstellar Disks revealed by / Flux Variation Gradients
The variability of young stellar objects (YSO) changes their brightness and
color preventing a proper classification in traditional color-color and color
magnitude diagrams. We have explored the feasibility of the flux variation
gradient (FVG) method for YSOs, using and band monitoring data of the
star forming region RCW\,38 obtained at the University Observatory Bochum in
Chile. Simultaneous multi-epoch flux measurements follow a linear relation
for almost all YSOs with large variability
amplitude. The slope gives the mean color temperature of
the varying component. Because is hotter than the dust sublimation
temperature, we have tentatively assigned it to stellar variations. If the
gradient does not meet the origin of the flux-flux diagram, an additional non-
or less-varying component may be required. If the variability amplitude is
larger at the shorter wavelength, e.g. , this component is cooler
than the star (e.g. a circumstellar disk); vice versa, if , the
component is hotter like a scattering halo or even a companion star. We here
present examples of two YSOs, where the FVG implies the presence of a
circumstellar disk; this finding is consistent with additional data at and
. One YSO shows a clear -band excess in the color-color diagram,
while the significance of a -excess in the other YSO depends on the
measurement epoch. Disentangling the contributions of star and disk it turns
out that the two YSOs have huge variability amplitudes (\,mag). The
FVG analysis is a powerful complementary tool to analyze the varying
components of YSOs and worth further exploration of monitoring data at other
wavelengths.Comment: 5 pages, 5 figures, accepted for publication in Astronomy and
Astrophysic
Probing Split Supersymmetry with Cosmic Rays
A striking aspect of the recently proposed split supersymmetry is the
existence of heavy gluinos which are metastable because of the very heavy
squarks which mediate their decay. In this paper we correlate the expected flux
of these particles with the accompanying neutrino flux produced in inelastic
collisions in distant astrophysical sources. We show that an event rate at
the Pierre Auger Observatory of approximately 1 yr for gluino masses of
about 500 GeV is consistent with existing limits on neutrino fluxes. The
extremely low inelasticity of the gluino-containing hadrons in their collisions
with the air molecules makes possible a distinct characterization of the
showers induced in the atmosphere. Should such anomalous events be observed, we
show that their cosmogenic origin, in concert with the requirement that they
reach the Earth before decay, leads to a lower bound on their proper lifetime
of the order of 100 years, and consequently, to a lower bound on the scale of
supersymmetry breaking, GeV. Obtaining
such a bound is not possible in collider experiments.Comment: Version to be published in Phys. Rev.
Formación inicial de profesores de educación media de ciencia mediante la teoría de enseñanza y aprendizaje basada en modelos mentales
Este estudio describe cómo se aplica la Teoría de los Modelos Mentales en la formación inicial del profesor de Ciencias de enseñanza media en la Facultad de Educación de la Universidad de Concepción. Esta nueva modalidad de formación, se introdujo a partir del año 2004, en las asignaturas de Didáctica III y IV y en el desarrollo de la tesis de pregrado. Los sesenta estudiantes participantes de la experiencia generaron más de treinta planificaciones de unidades sobre diferentes temas científicos, en las que se utiliza la Teoría de los Modelos Mentales, y que han aplicado a alumnos de enseñanza media. Los dos estudios pilotos que midieron la efectividad de estas planificaciones, indican que el uso de esta perspectiva genera auspiciosos resultados en el aprendizaje de los estudiantes de enseñanza media y en la organización del quehacer en el aula del futuro docente
Modelling photometric reverberation data -- a disk-like broad-line region and a potentially larger black hole mass for 3C120
We consider photometric reverberation mapping, where the nuclear continuum
variations are monitored via a broad-band filter and the echo of emission line
clouds of the broad line region (BLR) is measured with a suitable narrow-band
(NB) filter. We investigate how an incomplete emission-line coverage by the NB
filter influences the BLR size determination. This includes two basic cases: 1)
a symmetric cut of the blue and red part of the line wings, and 2) the filter
positioned asymmetrically to the line centre so that essentially a complete
half of the emission line is contained in the NB filter. Under the assumption
that the BLR size is dominated by circular Keplerian orbits, we find that
symmetric cutting of line wings may lead to overestimating the BLR size by less
than 5%. The case of asymmetric half-line coverage, similar as for our data of
the Seyfert 1 galaxy 3C120, yields the BLR size with a bias of less than 1%.
Our results suggest that any BLR size bias due to narrow-band line cut in
photometric reverberation mapping is small and in most cases negligible. We
used well sampled photometric reverberation mapping light curves with sharp
variation features in both the continuum and the Hbeta light curves to
determine the geometry type of the Hbeta BLR for 3C120. Modelling of the light
curve, under the assumption that the BLR is essentially virialised, argues
against a spherical geometry and favours a nearly face-on disk-like geometry
with inclination i = 10 +/- 4 deg and extension from 22 to 28 light days. The
low inclination may lead to a larger black hole mass than the derived when
using the average geometry scaling factor f=5.5. We discuss deviations of
Seyfert 1 galaxies from the M_BH - sigma relation.Comment: 9 pages, 11 figures, accepted for publication in Astronomy and
Astrophysic
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