83,295 research outputs found
Adaptive and Online Health Monitoring System for Autonomous Aircraft
Good situation awareness is one of the key attributes required to maintain safe flight, especially for an Unmanned Aerial System (UAS). Good situation awareness can be achieved by incorporating an Adaptive Health Monitoring System (AHMS) to the aircraft. The AHMS monitors the flight outcome or flight behaviours of the aircraft based on its external environmental conditions and the behaviour of its internal systems. The AHMS does this by associating a health value to the aircraft's behaviour based on the progression of its sensory values produced by the aircraft's modules, components and/or subsystems. The AHMS indicates erroneous flight behaviour when a deviation to this health information is produced. This will be useful for a UAS because the pilot is taken out of the control loop and is unaware of how the environment and/or faults are affecting the behaviour of the aircraft. The autonomous pilot can use this health information to help produce safer and securer flight behaviour or fault tolerance to the aircraft. This allows the aircraft to fly safely in whatever the environmental conditions. This health information can also be used to help increase the endurance of the aircraft. This paper describes how the AHMS performs its capabilities
Sale the seven Cs: Teaching/training aid for the (e-)retail mix
The â4Psâ of the marketing mix have long been popular with students, tutors, trainers
and practitioners as a learning and teaching aid. The purpose of this paper is to present
an equivalent tool for retail and e-retail: âSale the 7Csâ. The approach is by reference
to other authorsâ versions of the marketing, retail and e-retail mixes, distilled into a
simplified framework: C1 Convenience; C2 Customer value and benefit; C3 Cost to
the customer; C4 Computing and category management; C5 Customer franchise; C6
Customer care and service; C7 Communication and customer relationships. This
simplified mnemonic is new for (e-)retail. Mini case examples are used to illustrate
the applicability. These have a practical value for trainers and educators as specimen
answers to activity exercises. Retailers may find the convenient 7Cs structure useful
when planning strategies and tactics
Data intensive scientific analysis with grid computing
At the end of September 2009, a new Italian GPS receiver for radio occultation was launched from the Satish Dhawan Space Center (Sriharikota, India) on the Indian Remote Sensing OCEANSAT-2 satellite. The Italian Space Agency has established a set of Italian universities and research centers to implement the overall processing radio occultation chain. After a brief description of the adopted algorithms, which can be used to characterize the temperature, pressure and humidity, the contribution will focus on a method for automatic processing these data, based on the use of a distributed architecture. This paper aims at being a possible application of grid computing for scientific research
Theoretical Transmission Spectra During Extrasolar Giant Planet Transits
The recent transit observation of HD 209458 b - an extrasolar planet orbiting
a sun-like star - confirmed that it is a gas giant and determined that its
orbital inclination is 85 degrees. This inclination makes possible
investigations of the planet atmosphere. In this paper we discuss the planet
transmission spectra during a transit. The basic tenet of the method is that
the planet atmosphere absorption features will be superimposed on the stellar
flux as the stellar flux passes through the planet atmosphere above the limb.
The ratio of the planet's transparent atmosphere area to the star area is
small, approximately 10^{-3} to 10^{-4}; for this method to work very strong
planet spectral features are necessary. We use our models of close-in
extrasolar giant planets to estimate promising absorption signatures: the
alkali metal lines, in particular the Na I and K I resonance doublets, and the
He I - triplet line at 1083.0 nm. If successful, observations
will constrain the line-of-sight temperature, pressure, and density. The most
important point is that observations will constrain the cloud depth, which in
turn will distinguish between different atmosphere models. We also discuss the
potential of this method for EGPs at different orbital distances and orbiting
non-solar-type stars.Comment: revised to agree with accepted paper, ApJ, in press. 12 page
Test particle acceleration in a numerical MHD experiment of an anemone jet
To use a 3D numerical MHD experiment representing magnetic flux emerging into
an open field region as a background field for tracing charged particles. The
interaction between the two flux systems generates a localised current sheet
where MHD reconnection takes place. We investigate how efficiently the
reconnection region accelerates charged particles and what kind of energy
distribution they acquire. The particle tracing is done numerically using the
Guiding Center Approximation on individual data sets from the numerical MHD
experiment. We derive particle and implied photon distribution functions having
power law forms, and look at the impact patterns of particles hitting the
photosphere. We find that particles reach energies far in excess of those seen
in observations of solar flares. However the structure of the impact region in
the photosphere gives a good representation of the topological structure of the
magnetic field.Comment: 9 pages, 7 figures, accepted for publication in A&
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