618 research outputs found
Positioning and Scheduling of Wireless Sensor Networks - Models, Complexity, and Scalable Algorithms
Gaia: Organisation and challenges for the data processing
Gaia is an ambitious space astrometry mission of ESA with a main objective to
map the sky in astrometry and photometry down to a magnitude 20 by the end of
the next decade. While the mission is built and operated by ESA and an
industrial consortium, the data processing is entrusted to a consortium formed
by the scientific community, which was formed in 2006 and formally selected by
ESA one year later. The satellite will downlink around 100 TB of raw telemetry
data over a mission duration of 5 years from which a very complex iterative
processing will lead to the final science output: astrometry with a final
accuracy of a few tens of microarcseconds, epoch photometry in wide and narrow
bands, radial velocity and spectra for the stars brighter than 17 mag. We
discuss the general principles and main difficulties of this very large data
processing and present the organisation of the European Consortium responsible
for its design and implementation.Comment: 7 pages, 2 figures, Proceedings of IAU Symp. 24
Gaia Data Processing Architecture
Gaia is ESA's ambitious space astrometry mission the main objective of which
is to astrometrically and spectro-photometrically map 1000 Million celestial
objects (mostly in our galaxy) with unprecedented accuracy. The announcement of
opportunity for the data processing will be issued by ESA late in 2006. The
Gaia Data Processing and Analysis Consortium (DPAC) has been formed recently
and is preparing an answer. The satellite will downlink close to 100 TB of raw
telemetry data over 5 years. To achieve its required accuracy of a few 10s of
Microarcsecond astrometry, a highly involved processing of this data is
required.
In addition to the main astrometric instrument Gaia will host a Radial
Velocity instrument, two low-resolution dispersers for multi-color photometry
and two Star Mappers. Gaia is a flying Giga Pixel camera. The various
instruments each require relatively complex processing while at the same time
being interdependent. We describe the overall composition of the DPAC and the
envisaged overall architecture of the Gaia data processing system. We shall
delve further into the core processing - one of the nine, so-called,
coordination units comprising the Gaia processing system.Comment: 10 Pages, 2 figures. To appear in ADASS XVI Proceeding
Effective Verification for Low-Level Software with Competing Interrupts
Interrupt-driven software is difficult to test and debug, especially when interrupts can be nested and subject
to priorities. Interrupts can arrive at arbitrary times, leading to an exponential blow-up in the number of
cases to consider. We present a new formal approach to verifying interrupt-driven software based on symbolic
execution. The approach leverages recent advances in the encoding of the execution traces of interacting,
concurrent threads. We assess the performance of our method on benchmarks drawn from embedded systems
code and device drivers, and experimentally compare it to conventional approaches that use source-to-source
transformations. Our results show that our method significantly outperforms these techniques. To the best
of our knowledge, our work is the first to demonstrate effective verification of low-level embedded software
with nested interrupt
Aphasia and the Diagram Makers Revisited: an Update of Information Processing Models
Aphasic syndromes from diseases such as stroke and degenerative disorders are still common and disabling neurobehavioral disorders. Diagnosis, management and treatment of these communication disorders are often dependent upon understanding the neuropsychological mechanisms that underlie these disorders. Since the work of Broca it has been recognized that the human brain is organized in a modular fashion. Wernicke realized that the types of signs and symptoms displayed by aphasic patients reflect the degradation or disconnection of the modules that comprise this speech-language network. Thus, he was the first to propose a diagrammatic or information processing model of this modular language-speech network. Since he first published this model many new aphasic syndromes have been discovered and this has led to modifications of this model. This paper reviews some of the early (nineteenth century) models and then attempts to develop a more up-to-date and complete model
Gaia: organisation and challenges for the data processing
Gaia is an ambitious space astrometry mission of ESA with a main objective to map the sky in astrometry and photometry down to a magnitude 20 by the end of the next decade. While the mission is built and operated by ESA and an industrial consortium, the data processing is entrusted to a consortium formed by the scientific community, which was formed in 2006 and formally selected by ESA one year later. The satellite will downlink around 100 TB of raw telemetry data over a mission duration of 5 years from which a very complex iterative processing will lead to the final science output: astrometry with a final accuracy of a few tens of microarcseconds, epoch photometry in wide and narrow bands, radial velocity and spectra for the stars brighter than 17 mag. We discuss the general principles and main difficulties of this very large data processing and present the organization of the European Consortium responsible for its design and implementatio
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