83,295 research outputs found

    Adaptive and Online Health Monitoring System for Autonomous Aircraft

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    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

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    The ‘4Ps’ 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: ‘Sale the 7Cs’. The approach is by reference to other authors’ 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

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    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

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    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 23S2^3S - 23P2^3P 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

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    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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