3,432 research outputs found

    Excellent daytime seeing at Dome Fuji on the Antarctic plateau

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    Context. Dome Fuji, the second highest region on the Antarctic plateau, is expected to have some of the best astronomical seeing on Earth. However, site testing at Dome Fuji is still in its very early stages. Aims. To investigate the astronomical seeing in the free atmosphere above Dome Fuji, and to determine the height of the surface boundary layer. Methods. A Differential Image Motion Monitor was used to measure the seeing in the visible (472 nm) at a height of 11 m above the snow surface at Dome Fuji during the austral summer of 2012/2013. Results. Seeing below 0.2'' has been observed. The seeing often has a local minimum of ~0.3'' near 18 h local time. Some periods of excellent seeing, 0.3'' or smaller, were also observed, sometimes extending for several hours at local midnight. The median seeing is higher, at 0.52''---this large value is believed to be caused by periods when the telescope was within the turbulent boundary layer. Conclusions. The diurnal variation of the daytime seeing at Dome Fuji is similar to that reported for Dome C, and the height of the surface boundary layer is consistent with previous simulations for Dome Fuji. The free atmosphere seeing is ~0.2'', and the height of the surface boundary layer can be as low as ~11 m.Comment: 4 pages, 6 figures, Submitted to Astronomy & Astrophysics (letter

    Real-time simulation of jet engines with digital computer. 1: Fabrication and characteristics of the simulator

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    The fabrication and performance of a real time jet engine simulator using a digital computer are discussed. The use of the simulator in developing the components and control system of a jet engine is described. Comparison of data from jet engine simulation tests with actual engine tests was conducted with good agreement

    Static and Dynamic Chain Structures in the Mean-Field Theory

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    We give a brief overview of recent work examining the presence of α\alpha-clusters in light nuclei within the Skyrme-force Hartree-Fock model. Of special significance are investigations into α\alpha-chain structures in carbon isotopes and 16^{16}O. Their stability and possible role in fusion reactions are examined in static and time-dependent Hartree-Fock calculations. We find a new type of shape transition in collisions and a centrifugal stabilization of the 4α4\alpha chain state in a limited range of angular momenta. No stabilization is found for the 3α3\alpha chain.Comment: Fusionn 11 Conference, St. Malo, France, 201
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