794 research outputs found

    NNEP: The Navy NASA Engine Program

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    A computer code capable of simulating almost any conceivable turbine engine is described. This code uses stacked component maps and multiple flowpaths to simulate variable cycle engines with variable component geometry. It is capable of design and off-design (matching) calculations and can optimize free variables such as nozzle areas to minimize specific fuel consumption

    Computer optimization of reactor-thermoelectric space power systems

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    A computer simulation and optimization code that has been developed for nuclear space power systems is described. The results of using this code to analyze two reactor-thermoelectric systems are presented

    LIGO-Virgo-KAGRA's Oldest Black Holes:Probing Star Formation at Cosmic Noon With GWTC-3

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    In their third observing run, the LIGO-Virgo-KAGRA gravitational-wave (GW) observatory was sensitive to binary black hole (BBH) mergers out to redshifts zmerge ≈ 1. Because GWs are inefficient at shrinking the binary orbit, some of these BBH systems likely experienced long delay times τ between the formation of their progenitor stars at zform and their GW merger at zmerge. In fact, the distribution of delay times predicted by isolated binary evolution resembles a power law p(τ) ∝ τ ατ with slope −1 ≲ ατ ≲ −0.35 and a minimum delay time of τmin = 10 Myr . We use these predicted delay time distributions to infer the formation redshifts of the ∼70 BBH events reported in the third GW transient catalog GWTC-3 and the formation rate of BBH progenitors. For our default α τ = -1 delay time distribution, we find that GWTC-3 contains at least one system (with 90% credibility) that formed earlier than zform &gt; 4.4. Comparing our inferred BBH progenitor formation rate to the star formation rate, we find that at z form = 4, the number of BBH progenitor systems formed per stellar mass was 6.4+9.4-5.5 × 10−6 M ⊙− 1 and this yield dropped to 0.134+ 1.6-0.127 × 10−6 M⊙−1 by zform = 0. We discuss implications of this measurement for the cosmic metallicity evolution, finding that for typical assumptions about the metallicity dependence of the BBH yield, the average metallicity at zform = 4 was 〈 log 10 (Z/Z⊙ ) 〉= −0 .3+0.3-0.4 , although the inferred metallicity can vary by a factor of ≈3 for different assumptions about the BBH yield. Our results highlight the promise of current GW observatories to probe high-redshift star formation.</p

    A comparison of computerized MMPI reports of French-English bilingual Canadian students.

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    Dept. of Psychology. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1973 .F46. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.)--University of Windsor (Canada), 1973
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