259,308 research outputs found
Terrestrial applications: An intelligent Earth-sensing information system
For Abstract see A82-2214
Information reuse in dynamic spectrum access
Dynamic spectrum access (DSA), where the permission to use slices of radio spectrum is dynamically shifted (in time an in different geographical areas) across various communications services and applications, has been an area of interest from technical and public policy perspectives over the last decade. The underlying belief is that this will increase spectrum utilization, especially since many spectrum bands are relatively unused, ultimately leading to the creation of new and innovative services that exploit the increase in spectrum availability. Determining whether a slice of spectrum, allocated or licensed to a primary user, is available for use by a secondary user at a certain time and in a certain geographic area is a challenging task. This requires 'context information' which is critical to the operation of DSA. Such context information can be obtained in several ways, with different costs, and different quality/usefulness of the information. In this paper, we describe the challenges in obtaining this context information, the potential for the integration of various sources of context information, and the potential for reuse of such information for related and unrelated purposes such as localization and enforcement of spectrum sharing. Since some of the infrastructure for obtaining finegrained context information is likely to be expensive, the reuse of this infrastructure/information and integration of information from less expensive sources are likely to be essential for the economical and technological viability of DSA. © 2013 IEEE
Remote sensing in the coastal and marine environment. Proceedings of the US North Atlantic Regional Workshop
Presentations were grouped in the following categories: (1) a technical orientation of Earth resources remote sensing including data sources and processing; (2) a review of the present status of remote sensing technology applicable to the coastal and marine environment; (3) a description of data and information needs of selected coastal and marine activities; and (4) an outline of plans for marine monitoring systems for the east coast and a concept for an east coast remote sensing facility. Also discussed were user needs and remote sensing potentials in the areas of coastal processes and management, commercial and recreational fisheries, and marine physical processes
Optimal scan strategies for future CMB satellite experiments
The B-mode polarisation power spectrum in the Cosmic Microwave Background
(CMB) is about four orders of magnitude fainter than the CMB temperature power
spectrum. Any instrumental imperfections that couple temperature fluctuations
to B-mode polarisation must therefore be carefully controlled and/or removed.
We investigate the role that a scan strategy can have in mitigating certain
common systematics by averaging systematic errors down with many crossing
angles. We present approximate analytic forms for the error on the recovered
B-mode power spectrum that would result from differential gain, differential
pointing and differential ellipticity for the case where two detector pairs are
used in a polarisation experiment. We use these analytic predictions to search
the parameter space of common satellite scan strategies in order to identify
those features of a scan strategy that have most impact in mitigating
systematic effects. As an example we go on to identify a scan strategy suitable
for the CMB satellite proposed for the ESA M5 call. considering the practical
considerations of fuel requirement, data rate and the relative orientation of
the telescope to the earth. Having chosen a scan strategy we then go on to
investigate the suitability of the scan strategy.Comment: 21 pages, 11 figures, Comments welcom
E3D, The Euro3D Visualization Tool I: Description of the program and its capabilities
We present the first version of E3D, the Euro3D visualization tool for data
from integral field spectroscopy. We describe its major characteristics, based
on the proposed requirements, the current state of the project, and some
planned future upgrades. We show examples of its use and capabilities.Comment: 4 pages, 6 figures, accepted for publishing in AN (ref.proc. of
Euro3D Science workshop, IoA Cambridge, May 2003
The Planck mission
These lecture from the 100th Les Houches summer school on "Post-planck
cosmology" of July 2013 discuss some aspects of the Planck mission, whose prime
objective was a very accurate measurement of the temperature anisotropies of
the Cosmic Microwave Background (CMB). We announced our findings a few months
ago, on March 21, 2013. I describe some of the relevant steps we took to
obtain these results, sketching the measurement process, how we processed the
data to obtain full sky maps at 9 different frequencies, and how we extracted
the CMB temperature anisotropies map and angular power spectrum. I conclude by
describing some of the main cosmological implications of the statistical
characteristics of the CMB we found. Of course, this is a very much shortened
and somewhat biased view of the \Planck\ 2013 results, written with the hope
that it may lead some of the students to consult the original papers.Comment: 53 p.-34 fig; for spacetime consideration, the file here is not
paying justice to the actual thing; a closer approximation of it can be found
at
https://www.researchgate.net/profile/Francois_Bouchet/publication/262004262_The_Planck_Mission/file/e0b495363b042e81dd.pd
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