31,588 research outputs found

    Single-stage experimental evaluation of boundary layer blowing techniques for high lift stator blades. 1 - Compressor design

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    Boundary layer blowing techniques for high lift stator blades in axial flow compressor

    Comet Halley returns: A teachers' guide 1985-1986

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    This booklet has been put together as an aid for teachers in elementary and secondary schools. It is divided into two distinct parts. The first part is a brief tutorial which introduces some of the most important concepts about comets, including their historical significance. A list of selected readings is provided at the end of the booklet. The second part of the booklet contains a number of suggested activities, built around the comet. These include both classroom exercises and carefully described field work to observe the comet. Guidance is provided on where to look for the comet, how to observe it, and to photograph it

    Coherent spin mixing dynamics in a spin-1 atomic condensate

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    We study the coherent off-equilibrium spin mixing inside an atomic condensate. Using mean field theory and adopting the single spatial mode approximation (SMA), the condensate spin dynamics is found to be well described by that of a nonrigid pendulum, and displays a variety of periodic oscillations in an external magnetic field. Our results illuminate several recent experimental observations and provide critical insights into the observation of coherent interaction-driven oscillations in a spin-1 condensate.Comment: 6 pages, 5 eps figures, update the discussion of the experimental result

    Single-stage experimental evaluation of boundary layer bleed techniques for high lift stator blades. Compressors design

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    Design and evaluation of stator blades for use in boundary layer bleed techniques in axial flow compresso

    Dynamical instability and domain formation in a spin-1 Bose condensate

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    We interpret the recently observed spatial domain formation in spin-1 atomic condensates as a result of dynamical instability. Within the mean field theory, a homogeneous condensate is dynamically unstable (stable) for ferromagnetic (antiferromagnetic) atomic interactions. We find this dynamical instability naturally leads to spontaneous domain formation as observed in several recent experiments for condensates with rather small numbers of atoms. For trapped condensates, our numerical simulations compare quantitatively to the experimental results, thus largely confirming the physical insight from our analysis of the homogeneous case.Comment: RevTex4, 4 pages with 3 color eps figure, to appear in Phys. Rev. Let

    Seasonal abundance of small cladocerans in Lake Mangakaware, Waikato, New Zealand

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    The seasonal changes in the dynamics and life histories of the Cladocera in Lake Mangakaware, North Island, New Zealand, were studied over 19 months by sampling at weekly or 2-weekly intervals. Lake Mangakaware is a 13.3 ha polymictic lake with high nutrient status, low Secchi disc transparencies, and an unstable thermal regime. The four planktonic cladoceran species (Bosmina longirostris, B. meridionalis, Ceriodaphnia pulchella, and C. dubia) exhibited disjunct population maxima. Only B. longirostris was perennially present. All species exhibited low fecundities and low lipid content, indicating that food resources were limited and that competitive interactions and resistance to starvation were probably important in determining species success. Increases in body size in cooler seasons were unrelated to clutch size, giving further support for the view that available food was limited. These results are consistent with previous experimental findings that subtle differences in life history can determine seasonal success and the outcome of competition between similar species

    Are Financial Crashes Predictable?

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    We critically review recent claims that financial crashes can be predicted using the idea of log-periodic oscillations or by other methods inspired by the physics of critical phenomena. In particular, the October 1997 `correction' does not appear to be the accumulation point of a geometric series of local minima.Comment: LaTeX, 5 pages + 1 postscript figur

    Population polygons of tektite specific gravity for various localities in australasia

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    Comparison of specific gravity of tektites from australia, asia, texas, and czechoslovaki
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