29,833 research outputs found

    FORTRAN program flow chart is automatically produced

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    Computer under control of the flo-tran program automatically produces and updates flowcharts of fortran program source decks fed to it. The flowcharts are produced on either 35mm film or paper

    Constraints on short, hard gamma-ray burst beaming angles from gravitational wave observations

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    The first detection of a binary neutron star merger, GW170817, and an associated short gamma-ray burst confirmed that neutron star mergers are responsible for at least some of these bursts. The prompt gamma-ray emission from these events is thought to be highly relativistically beamed. We present a method for inferring limits on the extent of this beaming by comparing the number of short gamma-ray bursts (SGRBs) observed electromagnetically with the number of neutron star binary mergers detected in gravitational waves. We demonstrate that an observing run comparable to the expected Advanced LIGO (aLIGO) 2016–2017 run would be capable of placing limits on the beaming angle of approximately \theta \in (2\buildrel{\circ}\over{.} 88,14\buildrel{\circ}\over{.} 15), given one binary neutron star detection, under the assumption that all mergers produce a gamma-ray burst, and that SGRBs occur at an illustrative rate of Rgrb=10 Gpc−3 yr−1{{ \mathcal R }}_{\mathrm{grb}}=10\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}. We anticipate that after a year of observations with aLIGO at design sensitivity in 2020, these constraints will improve to \theta \in (8\buildrel{\circ}\over{.} 10,14\buildrel{\circ}\over{.} 95), under the same efficiency and SGRB rate assumptions

    Nested Radar Systems for Remote Coastal Observations

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    Advances in radar technology now allow the observation of sea surface features at multiple scales, from kilometers, down to metres. In the same manner that nested models are used at different resolutions, nested radars of different frequencies can be used to provide data on sea surface features at various resolutions. A new radar system in the millimeter wave-band has now been demonstrated with a resolution of <1m. This MMW-radar was deployed in a nested configuration with an X-band marine radar from a beach near Faro in Portugal. The results from the two systems show how the MMW-radar can image fine detail surf zone and swash processes to a range of O(200m), while the marine radar provides lower resolution images of O(10m) to longer ranges of O(2km). Data from the two nested radars are shown from a recent deployment on a barrier beach in the Ria Formosa region of the Algarve, Portugal. The data from these nested radars are analysed to map wavelengths in 2-D and a non-linear bathymetric inversion is used on both sets of data to estimate the bathymetry of the imaged area. Comparisons with in-situ surveys demonstrate the accuracy of this technique
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