1,129 research outputs found

    The large-scale energetic ion layer in the high latitude Jovian magnetosphere as revealed by Ulysses/HI-SCALE cross-field intensity-gradient measurements

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    Ulysses investigated the high latitude Jovian magnetosphere for a second time after Pioneer 11 mission and gave us the opportunity to search the structure and the dynamics of this giant magnetosphere above the magnetodisc. Kivelson(1976) and Kennel & Coroniti(1979) reported that Pioneer 11 observed energetic particle intensities at high latitudes at the same level with those measured in the plasma sheet and inferred that they were not consistent with the magnetodisc model. Ulysses observations supported the idea about a large-scale layer of energetic ions and electrons in the outer high latitude Jovian magnetosphere (Cowley et al.1996; Anagnostopoulos et al. 2001). This study perform a number of further tests for the existence of the large scale layer of energetic ions in the outer high latitude Jovian magnetosphere by studying appropriate cross-B field anisotropies in order to monitor the ion northward/southward intensity gradients. In particular, we examined Ulysses/HI-SCALE observations of energetic ions with large gyro-radius (0.5-1.6MeV protons and >2.5MeV heavy(Z>5) ions) in order to compare instant intensity changes with remote sensing intensity gradients. Our analysis confirms the existence of an energetic particle layer in the north hemisphere, during the inbound trajectory of Ulysses traveling at moderate latitudes, and in the south high-latitude duskside magnetosphere, during the outbound segment of the spacecraft trajectory. Our Ulysses/HI-SCALE data analysis also provides evidence for the detection of an energetic proton magnetopause boundary layer during the outbound trajectory of the spacecraft. During Ulysses flyby of Jupiter the almost permanent appearance of alternative northward and southward intensity gradients suggests that the high latitude layer appeared to be a third major area of energetic particles, which coexisted with the radiation belts and the magnetodisc.Comment: 37 pages, 11 figures, 1 tabl

    Visual Information Retrieval in Endoscopic Video Archives

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    In endoscopic procedures, surgeons work with live video streams from the inside of their subjects. A main source for documentation of procedures are still frames from the video, identified and taken during the surgery. However, with growing demands and technical means, the streams are saved to storage servers and the surgeons need to retrieve parts of the videos on demand. In this submission we present a demo application allowing for video retrieval based on visual features and late fusion, which allows surgeons to re-find shots taken during the procedure.Comment: Paper accepted at the IEEE/ACM 13th International Workshop on Content-Based Multimedia Indexing (CBMI) in Prague (Czech Republic) between 10 and 12 June 201

    Characteristics of <u>></u> 290 keV magnetosheath ions

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    International audienceWe performed a statistical analysis of 290-500 keV ion data obtained by IMP-8 during the years 1982-1988 within the earth's magnetosheath and analysed in detail some time periods withdistinct ion bursts. These studies reveal the following characteristics for magnetosheath 290-500 keV energetic ions: (a) the occurrence frequency and the flux of ions increase with increasing geomagnetic activity as indicated by the Kp index; the occurrence frequency was found to be as high as P > 42% for Kp > 2, (b) the occurrence frequency in the dusk magnetosheath was found to be slightly dependent on the local time and ranged between ~30% and ~46% for all Kp values; the highest occurrence frequency was detected near the dusk magnetopause (21 LT), (c) the high energy ion bursts display a dawn-dusk asymmetry in their maximum fluxes, with higher fluxes appearing in the dusk magnetosheath, and (d) the observations in the dusk magnetosheath suggest that there exist intensity gradients of energetic ions from the bow shock toward the magnetopause. The statistical results are consistent with the concept that leakage of magnetospheric ions from the dusk magnetopause is a semi-permanent physical process often providing the magnetosheath with high energy (290-500 keV) ions

    Time-Optimized Contextual Information Flow on Unmanned Vehicles

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    Nowadays, the domain of robotics experiences a significant growth. We focus on Unmanned Vehicles intended for the air, sea and ground (UxV). Such devices are typically equipped with numerous sensors that detect contextual parameters from the broader environment, e.g., obstacles, temperature. Sensors report their findings (telemetry) to other systems, e.g., back-end systems, that further process the captured information while the UxV receives control inputs, such as navigation commands from other systems, e.g., commanding stations. We investigate a framework that monitors network condition parameters including signal strength and prioritizes the transmission of control messages and telemetry. This framework relies on the Theory of Optimal Stopping to assess in real-time the trade-off between the delivery of the messages and the network quality statistics and optimally schedules critical information delivery to back-end systems

    CONTROL OF RELIABILITY OF A GENERALISED LINEAR MODEL FOR THE GENERATION OF STOCHASTIC RAINFALL SERIES

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    ΠΕΡΙΛΗΨΗΗ έλλειψη δεδομένων βροχόπτωσης σε μία περιοχή είναι μια κατάσταση που αντιμετωπίζεται συχνά, τόσο στην έρευνα, όσο και στις εφαρμοσμένες μελέτες. Σε προηγούμενη εργασία (Ιορδανίδης και Αναγνωστόπουλος, 2009) είχε χρησιμοποιηθεί ένα Γενικευμένο Γραμμικό Μοντέλο για τη δημιουργία στοχαστικών χρονοσειρών βροχόπτωσης στην περιοχή της πεδιάδας της Δράμας, με τη χρήση δεδομένων από σταθμούς στη γειτονική κοιλάδα του ποταμού Νέστου. Στην παρούσα εργασία χρησιμοποιούνται και τα δεδομένα από τον τηλεμετρικό σταθμό της Προσοτσάνης εντός της πεδιάδας της Δράμας, με σκοπό να εξεταστεί κατά πόσον η προηγούμενη προσομοίωση, η οποία χρησιμοποίησε εξολοκλήρου δεδομένα από την γειτονική περιοχή, είναι αξιόπιστη, ώστε να μπορεί να χρησιμοποιηθεί σαν εργαλείο από τους ερευνητές και μελετητές.ABSTRACTThe lack of rainfall data in an area is a situation encountered frequently, both in research and in design projects. In a previous work (Iordanidis and Anagnostopoulos, 2009), a Generalised Linear Model was employed for the generation of stochastic rainfall series in the area of the plain of Drama, by the use of data from stations in the adjacent Nestos river valley. In the present study, data from the telemetric station of Prosotsani inside the area of the plain of Drama are also used, in order to examine whether the previous simulation, which used exclusively data outside the study area, is reliable, and consequently can be used as a research tool by investigators and practitioners

    On Linear Congestion Games with Altruistic Social Context

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    We study the issues of existence and inefficiency of pure Nash equilibria in linear congestion games with altruistic social context, in the spirit of the model recently proposed by de Keijzer {\em et al.} \cite{DSAB13}. In such a framework, given a real matrix Γ=(γij)\Gamma=(\gamma_{ij}) specifying a particular social context, each player ii aims at optimizing a linear combination of the payoffs of all the players in the game, where, for each player jj, the multiplicative coefficient is given by the value γij\gamma_{ij}. We give a broad characterization of the social contexts for which pure Nash equilibria are always guaranteed to exist and provide tight or almost tight bounds on their prices of anarchy and stability. In some of the considered cases, our achievements either improve or extend results previously known in the literature
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