23,120 research outputs found

    Project Polaris: A Report

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    The project was proposed to meet the developing demands for higher resolution and accuracy polar motion and Earth rotation data to support modern geodynamic studies. The basis for the selection of radio interferometry, rather than lunar or artifical satellite laser ranging or Doppler satellite tracking, is described

    Hydrogeology of Closed Basins and Deserts of South America, ERTS-1 Interpretations

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    Hydrogeology of closed basins and deserts of South America (Bolivia, Argentina, Chile, and Peru), ERTS-1 interpretation

    Free-flight measurements of dynamic stability derivatives of a blunted 120 deg cone in helium at Mach number 15.4

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    Free flight measurements of dynamic stability derivatives of blunted 120 deg cone in helium compared to unmodified Newtonian theory prediction

    Recent developments in Vorton Theory

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    This article provides a concise overview of recent theoretical results concerning the theory of vortons, which are defined to be (centrifugally supported) equilibrium configurations of (current carrying) cosmic string loops. Following a presentation of the results of work on the dynamical evolution of small circular string loops, whose minimum energy states are the simplest examples of vortons, recent order of magnitude estimates of the cosmological density of vortons produced in various kinds of theoretical scenario are briefly summarised.Comment: 6 pages Latex. Contribution to 1996 Cosmology Meeting, Peyresq, Franc

    New concept in brazing metallic honeycomb panels

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    Aluminum oxide coating provides surface which will not be wetted by brazing alloy and which stops metallic diffusion welding of tooling materials to part being produced. This method eliminates loss of tooling materials and parts from braze wetting and allows fall-apart disassembly of tooling after brazing

    Renormalisation of gravitational self interaction for wiggly strings

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    It is shown that for any elastic string model with energy density UU and tension TT, the divergent contribution from gravitational self interaction can be allowed for by an action renormalisation proportional to (U−T)2(U-T)^2. This formula is applied to the important special case of a bare model of the transonic type (characterised by a constant value of the product UTUT) that represents the macroscopically averaged effect of shortwavelength wiggles on an underlying microscopic model of the Nambu-Goto type (characterised by U=TU=T).Comment: 11 pages, Latex; original 8 page version extended to include estimates of relevant orders of magnitude. To be published in Physical Review,

    Investigation of ground effects on large and small scale models of a three fan V/STOL aircraft configuration

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    Induced lift of a subsonic, three fan, lift/cruise, V/STOL aircraft configuration was investigated using scale modes of a multimission aircraft whose design incorporates a nose mounted lift fan and two lift/cruise units located over the wing. Configuration effects were assessed for lift improvement devices, lift/cruise nozzle rails, nozzle perimeter plates, and alternate nose fan exit hubs. Tests were conducted at four model heights (H/D = 0.95, 1.53, 3.06 and 6.45, where D is the average nozzle exit diameter equal to 0.997 m.) Results are presented and discussed

    B-R Colors of Globular Clusters in NGC 6166 (A2199)

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    We have analysed new R-band photometry of globular clusters in NGC 6166, the cD galaxy in the cooling flow cluster A2199. In combination with the earlier B photometry of Pritchet \& Harris (1990), we obtain B−-R colours for ∼\sim 40 globular clusters in NGC 6166. The mean B−-R is 1.26 ±\pm 0.11, corresponding to a mean [Fe/H] = −-1 ±\pm 0.4. Given that NGC 6166 is one of the most luminous cD galaxies studied to date, our result implies significant scatter in the relationship between mean cluster [Fe/H] and parent galaxy luminosity. We obtain a globular cluster specific frequency of SN_N ∼\sim 9, with a possible range between 5 and 18. This value is inconsistent with the value of SN_N ≤\leq 4 determined earlier by Pritchet \& Harris (1990) from B-band photometry, and we discuss possible reasons for the discrepancy. Finally, we reassess whether or not cooling flows are an important mechanism for forming globular clusters in gE/cD galaxies.Comment: 8 pages, uuencoded, gzipped tar file with latex file, 6 figures (Fig 1 omitted because of size), and mn.sty file. Figures will be embedded into the postscript file. Accepted (March 1996) for publication in MNRA

    Transonic Elastic Model for Wiggly Goto-Nambu String

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    The hitherto controversial proposition that a ``wiggly" Goto-Nambu cosmic string can be effectively represented by an elastic string model of exactly transonic type (with energy density UU inversely proportional to its tension TT) is shown to have a firm mathematical basis.Comment: 8 pages, plain TeX, no figure
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