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
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
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
Recommended from our members
Detection of Walls, Floors, and Ceilings in Point Cloud Data
This is the author accepted manuscript. The final version is available from the American Society of Civil Engineers via http://dx.doi.org/10.1061/9780784479827.229The successful implementation of Building Information Models (BIMs) for facility management, maintenance and operation is highly dependent on the ability to generate such models for existing assets. Generating such BIMs typically requires laser scanning to acquire point clouds and significant post-processing to register the clouds, replace the points with BIM objects, assign semantic relationships and add any additional properties, such as materials. Several research efforts have attempted to reduce the post-processing manual effort by classifying the structural elements and clutter in isolated rooms. They have not however examined the complexity of a whole building. In this paper, we propose a robust framework that can automatically process the point cloud of an entire building, possibly with multiple floors, and classify the points belonging to floors, walls and ceilings.. We first extract the planar surfaces by segmenting the point cloud, and then we use contextual reasoning, such as height, orientation, relation to other objects, and local statistics like point density in order to classify them into objects. Experiments were conducted on a registered point cloud of an office building. The results indicated that almost all of the walls and floors/ceilings were correctly clustered in the point cloud.The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreements n° 247586 ("BIMAutoGen") and n° 334241 ("INFRASTRUCTUREMODELS")
Characteristics of <u>></u> 290 keV magnetosheath ions
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
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
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
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 specifying a particular
social context, each player aims at optimizing a linear combination of the
payoffs of all the players in the game, where, for each player , the
multiplicative coefficient is given by the value . 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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