142,741 research outputs found
Static tests of excess ground attenuation at Wallops Flight Center
An extensive experimental measurement program which evaluated the attenuation of sound for close to horizontal propagation over the ground was designed to replicate, under static conditions, results of the flight measurements carried out earlier by NASA at the same site (Wallops Flight Center). The program consisted of a total of 41 measurement runs of attenuation, in excess of spreading and air absorption losses, for one third octave bands over a frequency range of 50 to 4000 Hz. Each run consisted of measurements at 10 locations up to 675 m, from a source located at nominal elevations of 2.5, or 10 m over either a grassy surface or an adjacent asphalt concrete runway surface. The tests provided a total of over 8100 measurements of attenuation under conditions of low wind speed averaging about 1 m/s and, for most of the tests, a slightly positive temperature gradient, averaging about 0.3 C/m from 1.2 to 7 m. The results of the measurements are expected to provide useful experimental background for the further development of prediction models of near grazing incidence sound propagation losses
Flight investigation to evaluate the roll-rate stabilization system of the Naval Ordnance Test Station Sidewinder missile at Mach numbers from 0.9 to 2.3
Rigorous theory of nuclear fusion rates in a plasma
Real-time thermal field theory is used to reveal the structure of plasma
corrections to nuclear reactions. Previous results are recovered in a fashion
that clarifies their nature, and new extensions are made. Brown and Yaffe have
introduced the methods of effective quantum field theory into plasma physics.
They are used here to treat the interesting limiting case of dilute but very
highly charged particles reacting in a dilute, one-component plasma. The highly
charged particles are very strongly coupled to this background plasma. The
effective field theory proves that this mean field solution plus the one-loop
term dominate; higher loop corrections are negligible even though the problem
involves strong coupling. Such analytic results for very strong coupling are
rarely available, and they can serve as benchmarks for testing computer models.Comment: 4 pages and 2 figures, presented at SCCS 2005, June 20-25, Moscow,
Russi
Understanding voluntary organizations : guidelines for donors
Voluntary development organizations have demonstrated substantial comparatiave advantage in developing countries - especially in their ability to innovate, adapt to local conditions, and reach and work with poor and difficult to reach populations. These capabilities are a function of their values, special skills, small size, limited resources, flexibility, and freedom from political constraints. Their weaknesses are a function of many of the same characteristics - particularly their value commitments, small size, independence, and lack of administrative rigidity. The authors explain that the strongest Voluntary Organizations (VOs) and People's Organizations (POs) respond to more than financial incentives. Their strength lies in the fact that they are not the same as government organizations or businesses. At the same time, they are not immune to financial incentives, which if wrongly applied can destroy the voluntarism of all but the most strongly aware of VOs and POs.Environmental Economics&Policies,Early Child and Children's Health,Health Economics&Finance,Health Monitoring&Evaluation,Poverty Assessment
Atmospheric environment for Space Shuttle (STS-2) launch
Selected atmospheric conditions observed near Space Shuttle STS-2 launch time on November 12, 1981, or Kennedy Space Center, Florida are summarized. Values of ambient pressure, temperature, moisture, ground winds, visual observations (cloud), and winds aloft are included. The sequence of prelaunch Jimsphere measured vertical wind profiles is given in this report. Wind and thermodynamic parameters measured at the surface and aloft in the SRB descent/impact ocean area are also presented. Final meteorological tapes, which consist of wind and thermodynamic parameters versus altitude, for STS-2 vehicle ascent and SRB descent have been constructed. The STS-2 ascent meteorological data tape was constructed
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