50,341 research outputs found

    High density matter

    Full text link
    The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has lead to the necessary reliance on theoretical models. However, there remains great uncertainty in these models, which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this review the latest developments in construction of the Equation of State (EoS) of high-density matter at zero and finite temperature assuming different composition of the matter are surveyed. Critical comparison of model EoS with available observational data on neutron stars, including gravitational masses, radii and cooling patterns is presented. The effect of changing rotational frequency on the composition of neutron stars during their lifetime is demonstrated. Compatibility of EoS of high-density, low temperature compact objects and low density, high temperature matter created in heavy-ion collisions is discussed.Comment: 10 pages, 6 figures, Invited talk at Nuclei in Cosmos 2012, accepted for publication on PoS. arXiv admin note: text overlap with arXiv:1201.0950 by other author

    Thermal control for storage of cryogenic propellants in a common-bulkhead tank: A concept

    Get PDF
    Simple, reliable ground-hold refrigeration system for common-bulkhead tank meets design criteria and objectives for ground-hold of oxygen difluoride and diborane. System is failsafe and malfunctions can be rectified without interruption of basic system functions

    In Honor of Justice William J. Brennan, Jr.: Constitutional Vision

    Get PDF

    Safe transport of diborane in a dual refrigerant system: A concept

    Get PDF
    Mobile transport system, that can be carried by truck and parked in storage area, consists of an inner container capable of holding 363 kg of diborane and an external, dual refrigeration unit which uses liquid nitrogen and Freon-14

    Incompressibility in finite nuclei and nuclear matter

    Full text link
    The incompressibility (compression modulus) K0K_{\rm 0} of infinite symmetric nuclear matter at saturation density has become one of the major constraints on mean-field models of nuclear many-body systems as well as of models of high density matter in astrophysical objects and heavy-ion collisions. We present a comprehensive re-analysis of recent data on GMR energies in even-even 112124^{\rm 112-124}Sn and 106,100116^{\rm 106,100-116}Cd and earlier data on 58 \le A \le 208 nuclei. The incompressibility of finite nuclei KAK_{\rm A} is expressed as a leptodermous expansion with volume, surface, isospin and Coulomb coefficients KvolK_{\rm vol}, KsurfK_{\rm surf}, KτK_\tau and KcoulK_{\rm coul}. \textit{Assuming} that the volume coefficient KvolK_{\rm vol} is identified with K0K_{\rm 0}, the KcoulK_{\rm coul} = -(5.2 ±\pm 0.7) MeV and the contribution from the curvature term Kcurv_{\rm curv}A2/3^{\rm -2/3} in the expansion is neglected, compelling evidence is found for K0K_{\rm 0} to be in the range 250 <K0< < K_{\rm 0} < 315 MeV, the ratio of the surface and volume coefficients c=Ksurf/Kvolc = K_{\rm surf}/K_{\rm vol} to be between -2.4 and -1.6 and KτK_{\rm \tau} between -840 and -350 MeV. We show that the generally accepted value of K0K_{\rm 0} = (240 ±\pm 20) MeV can be obtained from the fits provided cc \sim -1, as predicted by the majority of mean-field models. However, the fits are significantly improved if cc is allowed to vary, leading to a range of K0K_{\rm 0}, extended to higher values. A self-consistent simple (toy) model has been developed, which shows that the density dependence of the surface diffuseness of a vibrating nucleus plays a major role in determination of the ratio Ksurf/Kvol_{\rm surf}/K_{\rm vol} and yields predictions consistent with our findings.Comment: 26 pages, 13 figures; corrected minor typos in line with the proof in Phys. Rev.

    Flight service evaluation of advanced composite ailerons on the L-1011 transport aircraft

    Get PDF
    This report covers flight evaluation of composite inboard ailerons on the L-1011 under Contract NAS 1-15069 for a period of five years. This is the fourth annual report of the maintenance evaluation program, and covers the period from May 1985 when the third yearly inspections were completed, through July 1986. Four shipsets of graphite/epoxy composite inboard ailerons were installed on L-1011 aircraft for this maintenance evaluation program. These include two Delta aircraft and two TWA aircraft. A fifth shipset of composite ailerons was installed in 1980 on Lockheed's flight test L-1011. One instance of minor damage was observed on one of the composite ailerons and was repaired. No other maintenance actions have occurred on any of the composite parts except for repainting of areas with paint loss. Flight hours on the airline components at the time of inspection ranged from 12,051]en1] to 14,046 hours, after approximately 4 years of service

    On the effects of flight on jet engine exhaust noise

    Get PDF
    Differences between flight data and predictions of jet engine exhaust noise were reconciled by considering the combined effects of jet mixing noise and internally generated engine exhaust noise. The source strength of the internally generated noise was assumed to be unaffected by flight, as experiments demonstrated. The directivity of the internally generated noise was assumed to be the same statically as that given in the NASA interim prediction method for core engine noise. However, it was assumed that in flight internally generated noise is subject to the convective amplification effect of a simple source. The absolute levels of internally generated noise were obtained from an empirical fit of some typical engine data. The static and flight jet noise were predicted using the above prediction method. It was shown that in many cases much of the flyover noise signature is dominated by internally generated noise

    An empirical model for inverted-velocity-profile jet noise prediction

    Get PDF
    An empirical model for predicting the noise from inverted-velocity-profile coaxial or coannular jets is presented and compared with small-scale static and simulated flight data. The model considered the combined contributions of as many as four uncorrelated constituent sources: the premerged-jet/ambient mixing region, the merged-jet/ambient mixing region, outer-stream shock/turbulence interaction, and inner-stream shock/turbulence interaction. The noise from the merged region occurs at relatively low frequency and is modeled as the contribution of a circular jet at merged conditions and total exhaust area, with the high frequencies attenuated. The noise from the premerged region occurs at high frequency and is modeled as the contribution of an equivalent plug nozzle at outer stream conditions, with the low frequencies attenuated
    corecore