57,869 research outputs found
Using an ontology for interoperability and browsing of museum, library and archive information
Ontologies play an important part in the development of the future ‘semantic web’; the CIDOC conceptual reference model (CRM) is an ontology aimed at the cultural heritage domain. This paper describes a Concept Browser, developed for the EU/IST-funded SCULPTEUR project (semantic and content-based multimedia exploitation for European benefit environment (programme IST-2001-no. 35372); May 2002 to May 2005), which is able to access different museum information systems through a common ontology, the CRM. The development of this Concept Browser has required mappings from the legacy museum database systems to the CRM. The crucial process of creating the mappings is described, using the C2RMF catalogue (EROS) and library databases as a case study
Seeing Star Formation Regions with Gravitational Microlensing
We qualitatively study the effects of gravitational microlensing on our view
of unresolved extragalactic star formation regions. Using a general
gravitational microlensing configuration, we perform a number of simulations
that reveal that specific imprints of the star forming region are imprinted,
both photometrically and spectroscopically, upon observations. Such
observations have the potential to reveal the nature and size of these star
forming regions, through the degree of variability observed in a monitoring
campaign, and hence resolve the star formation regions in distant galaxies
which are too small to be probed via more standard techniques.Comment: 7 pages, 8 figures, ApJ accepte
Preliminary design-lift/cruise fan research and technology airplane flight control system
This report presents the preliminary design of a stability augmentation system for a NASA V/STOL research and technology airplane. This stability augmentation system is postulated as the simplest system that meets handling qualities levels for research and technology missions flown by NASA test pilots. The airplane studied in this report is a T-39 fitted with tilting lift/cruise fan nacelles and a nose fan. The propulsion system features a shaft interconnecting the three variable pitch fans and three power plants. The mathematical modeling is based on pre-wind tunnel test estimated data. The selected stability augmentation system uses variable gains scheduled with airspeed. Failure analysis of the system illustrates the benign effect of engine failure. Airplane rate sensor failure must be solved with redundancy
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Radiative transfer modelling for the NOMAD-UVIS instrument on the ExoMars Trace Gas Orbiter mission
The NOMAD (Nadir and Occultation for MArs Discovery) instrument is a 3-channel (2 IR, 1 UV/Vis) spectrometer due to fly on the 2016 ExoMars Trace Gas Orbiter mission. A radiative transfer model for Mars has been developed providing synthetic spectra to simulate observations of the UVIS channel in both solar occultation and nadir viewing geometries. This will allow for the characterization and mitigation of the influence of dust on retrievals of ozone abundance
Microlensing of Broad Absorption Line Quasars: Polarization Variability
Roughly 10% of all quasars exhibit Broad Absorption Line (BAL) features which
appear to arise in material outflowing at high velocity from the active
galactic nucleus (AGN). The details of this outflow are, however, very poorly
constrained and the particular nature of the BAL material is essentially
unknown. Recently, new clues have become available through polarimetric studies
which have found that BAL troughs are more polarized than the quasar continuum
radiation. To explain these observations, models where the BAL material
outflows equatorially across the surface of the dusty torus have been
developed. In these models, however, several sources of the BAL polarization
are possible. Here, we demonstrate how polarimetric monitoring of
gravitationally lensed quasars, such as H 1413+117, during microlensing events
can not only distinguish between two currently popular models, but can also
provide further insight into the structure at the cores of BAL quasars.Comment: 17 pages, 3 figures, accepted to PAS
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