Global, continuous, low-latency, and high performance surveillance of aircraft via Space-Based ADS-B (Automatic Dependent Surveillance Broadcast) is an emerging technology for the aviation industry. The Iridium-NEXT Low Earth Orbit (LEO) satellites, which will host the Aireon ADS-B receiver payloads, will begin launching in 2015 with all 66 operational satellites in their mission orbit by 2017, gradually replacing the current Iridium satellite constellation and enabling the global ADS-B surveillance services of Aireon [1-3].Prior to launch, a series of system and receiver models, simulations, and studies were produced in order to estimate metrics of this unique surveillance system such as the expected ADS-B aircraft position update interval. To assess whether the required update intervals for providing aircraft separation services will be achievable, the density of aircraft and other 1090 MHz in-band transmitters must be taken into account with respect to the large satellite beam footprints as a function of time and space (particularly near coastal areas where air traffic is most dense). This work describes a model for calculating the expected impact of aircraft density, mixed avionics equipage, and satellite motion on the ADS-B update interval performance for wide area space-based receiver systems. Additionally, several examples of expected performance based on the model are characterized in various Flight Information Regions (FIRs).
In this work, we explore the possible formation of ordered phases in hadronic
matter, related to the presence of hyperons at high densities. We analyze a
microscopic mechanism which can lead to the crystallization of the hyperonic
sector by the confinement of the hyperons on the nodes of a lattice. For this
purpose, we introduce a simplified model of the hadronic plasma, in which the
nuclear interaction between protons, neutrons and hyperons is mediated by meson
fields. We find that, for some reasonable sets of values of the model
parameters, such ordered phases are energetically favoured as density increases
beyond a threshold value.Comment: 16 pages, 14 figures, submitted to NP
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