51,035 research outputs found
High density matter
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
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
Safe transport of diborane in a dual refrigerant system: A concept
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
Flight service evaluation of advanced composite ailerons on the L-1011 transport aircraft
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
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
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
Flight service evaluation of Kevlar-49 epoxy composite panels in wide-bodies commercial transport aircraft
Kevlar-49 fairing panels, installed as flight service components on three L-1011s, were inspected after 9 years of service. There are six Kevlar-49 panels on each aircraft: a left hand and right hand set of a wing body sandwich fairing; a solid laminate under wing fillet panel; and a 422 K (300 F) service aft engine fairing. The fairings have accumulated a total of 70,000 hours, with one ship set having over 24,000 hours service. The Kevlar-49 components were found to be performing satisfactorily in service with no major problems, or any condition requiring corrective action. The only defects noted were minor impact damage, a few minor disbonds and a minor degree of fastener hole fraying and elongation. These are for the most part comparable to damage noted on fiberglass fairings. The service history to date indicates that Kevlar-49 epoxy composite materials have satisfactory service characteristics for use in aircraft secondary structure
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