81,382 research outputs found

    Payload/burned-out motor case separation system Patent

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    Payload/spent rocket engine case separation syste

    A Non-Zeeman Interpretation for Polarized Maser Radiation and the Magnetic Field at the Atmospheres of Late-Type Giants

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    The linear polarization that is observed, together with likely changes in the orientation of the magnetic field along the line of sight and hence of the optical axes of the medium, can lead to the circular polarization that is observed in the radiation of the circumstellar SiO masers. A magnetic field greater than only about 30 mG is required, in contrast to 10-100 G that would be implied by the Zeeman interpretation. To assess quantitatively the likely changes in orientation of the magnetic field, calculations are performed with representative field configurations that are created by statistical sampling using a Kolmogorov-like power spectrum.Comment: 7 pages Latex (aaspp4.sty), 3 ps-figures. Accepted for publication in Astrophysical Journal Letter

    Leeds Met Library Facebook application

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    At the Leeds Met staff development festival in 2008 a library graduate trainee, Anna Hepworth, took part in a ‘Dragons’ Den’ event which saw staff propose new, innovative ideas to a panel of senior managers. Anna’s suggestion was to develop a Facebook application (or ‘app’) for the library and it was one of the competition winners. Anna’s initial proposal was to create a Leeds Met library catalogue application, but after discussions with members of the library’s ‘technologies for learning’ team it was decided to take the application a stage further, creating a mash-up using data from the library management system (Sirsi-Dynix Symphony). The Facebook application would send a library catalogue search box to a Facebook profile, but would also add value by delivering customised user data, including library record details such as number of issues, reservations and overdues. There would also be links to the library website and online self-service functions from the application

    The metallicity of gamma-ray burst environments from high energy observations

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    Gamma-ray bursts (GRBs) and their early afterglows ionise their circumburst material. Only high-energy spectroscopy therefore, allows examination of the matter close to the burst itself. Soft X-ray absorption allows an estimate to be made of the total column density in metals. The detection of the X-ray afterglow can also be used to place a limit on the total gas column along the line of sight based on the Compton scattering opacity. Such a limit would enable, for the first time, the determination of lower limits on the metallicity in the circumburst environments of GRBs. In this paper, we determine the limits that can be placed on the total gas column density in the vicinities of GRBs based on the Compton scattering. We simulate the effects of Compton scattering on a collimated beam of high energy photons passing through a shell of high column density material to determine the expected lightcurves, luminosities, and spectra. We compare these predictions to observations, and determine what limits can realistically be placed on the total gas column density. The smearing out of pulses in the lightcurve from Compton scattering is not likely to be observable, and its absence does not place strong constraints on the Compton depth for GRBs. However, the distribution of observed luminosities of bursts allows us to place statistical, model-dependent limits that are typically <~1e25 cm^{-2} for less luminous bursts, and as low as ~1e24 cm$^{-2} for the most luminous. Using the shape of the high-energy broadband spectrum, however, in some favourable cases, limits as low as ~5e24 cm^{-2} can placed on individual bursts, implying metallicity lower limits from X- and gamma-rays alone from 0 up to 0.01 Z/Zsun. At extremely high redshifts, this limit would be at least 0.02 Z/Z_sun, enough to discriminate population III from non-primordial GRBs.Comment: 4 pages, 4 figures, submitted to A&A letter

    Productivity of Federally Financed Research and Development Final Report, May 15, 1963 - May 14, 1966

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    Research project on federal and industrial patent acquisition and economic implications - NASA PROGRA

    Scalability Analysis of Parallel GMRES Implementations

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    Applications involving large sparse nonsymmetric linear systems encourage parallel implementations of robust iterative solution methods, such as GMRES(k). Two parallel versions of GMRES(k) based on different data distributions and using Householder reflections in the orthogonalization phase, and variations of these which adapt the restart value k, are analyzed with respect to scalability (their ability to maintain fixed efficiency with an increase in problem size and number of processors).A theoretical algorithm-machine model for scalability is derived and validated by experiments on three parallel computers, each with different machine characteristics

    A super-ductile alloy for the die-casting of aluminium automotive body structural components

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    Super-ductile die-cast aluminium alloys are critical to future light-weighting of automotive body structures. This paper introduces a die-cast aluminium alloy that can satisfy the requirements of these applications. After a review of currently available alloys, the requirement of a die-cast aluminium alloy for automotive body structural parts is proposed and an Al-Mg-Si system is suggested. The effect of the alloying elements, in the composition, has been investigated on the microstructure and mechanical properties, in particular the yield strength, the ultimate tensile strength and elongation. © (2014) Trans Tech Publications, Switzerland.The EPSRC and JLR U

    Executive computer program for linking independent computer programs: ODINEX

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    Program controls sequence of execution of network of program elements and maintains data base of common information which forms communication link among them. Approach is applicable to any multiple-program task
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