78,453 research outputs found

    The balanced Voronoi formulas for GL(n)

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    In this paper we show how the GL(N) Voronoi summation formula of [MiSc2] can be rewritten to incorporate hyper-Kloosterman sums of various dimensions on both sides. This generalizes a formula for GL(4) with ordinary Kloosterman sums on both sides that was considered by Xiaoqing Li and the first-named author, and later by the second-named author in [Zho]

    Using multiple metrics for rate adaptation algorithms in IEEE 802.11 WLANs

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    Chinese peasant entrepreneurs: an examination of township and village

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    One of the greatest achievements in China's economic reform is the development of rural township and village enterprises (TVEs). Their importance in the national economy can be seen from the fact that by the end of 1993, TVEs accounted for nearly one third of the agricultural labour force, and one fifth of the total labour force nationwide. Despite some research attention being given to Chinese TVEs, the peasant entrepreneurs, owners and /or managers of these enterprises have remained largely unknown in the West. Who are they? Where are they from? What are their unique characteristics which distinguish them from both managers in the state-owned Chinese enterprises (SOEs) and small business owners /entrepreneurs in the West? What environmental factors contribute to the shaping of these characteristics? What are the problems faced by them and the possible solutions? This paper addresses these questions

    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

    The Ultraviolet flash accompanying GRBs from neutron-rich internal shocks

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    In the neutron-rich internal shocks model for Gamma-ray Burts (GRBs), the Lorentz factors (LFs) of ions shells are variable, so are the LFs of accompanying neutron shells. For slow neutron shells with a typical LF tens, the typical beta-decay radius reads R_{\beta,s} several 10^{14} cm, which is much larger than the typical internal shocks radius 10^{13} cm, so their impact on the internal shocks may be unimportant. However, as GRBs last long enough (T_{90}>20(1+z) s), one earlier but slower ejected neutron shell will be swept successively by later ejected ion shells in the range 10^{13}-10^{15} cm, where slow neutrons have decayed significantly. We show in this work that ion shells interacting with the beta-decay products of slow neutron shells can power a ultraviolet (UV) flash bright to 12th magnitude during the prompt gamma-ray emission phase or slightly delayed, which can be detected by the upcoming Satellite SWIFT in the near future.Comment: 6 pages (2 eps figures), accepted for publication in ApJ

    Lick Slit Spectra of Thirty-Eight Objective Prism QSO Candidates and Low Metallicity Halo Stars

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    We present Lick Observatory slit spectra of 38 objects which were claimed to have pronounced ultraviolet excess and emission lines by Zhan \& Chen. Most of our spectra have FWHM spectral resolutions of about 4~\AA , and relatively high S/N of about 10 -- 50, although some have FWHM 15\simeq 15~\AA ~or lower S/N. We find eleven QSOs, four galaxies at z0.1z \simeq 0.1, twenty-two stars and one unidentified object with a low S/N spectrum. Six of the QSOs show absorption systems, including Q0000+027A with a relatively strong associated C~IV absorption system, and Q0008+008 (V18.9\simeq 18.9) with a damped Lyα\alpha system with an H~I column density of 102110^{21} cm2^{-2}. The stars include a wide variety of spectral types. There is one new DA4 white dwarf at 170~pc, one sdB at 14~kpc, and three M stars. The rest are of types F, G and K. We have measured the equivalent widths of the Ca~II~K line, the G-band and the Balmer lines in ten stars with the best spectra, and we derive metallicities. Seven of them are in the range 2.5-2.5 \leq~[Fe/H]~1.7\leq -1.7, while the others are less metal poor. If the stars are dwarfs, then they are at distances of 1 to 7~kpc, but if they are giants, typical distances will be about 10~kpc.Comment: (Plain Tex, 21 pages, including tables. Send email to 'travell_oir%[email protected]' for 12 pages of figures) To appear in the %%Astronomical Journal, August, 199
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