99,993 research outputs found
Bibliography of remote sensing of resources
Bibliography on remote sensing of resources related to space flights, and aerospace science
High-temperature, long-life thyratron
Thallium and xenon filled thyratron was developed that operates at tube envelope temperatures up to 750 C. This tube performs at peak voltage ratings of 2000 V forward and reverse and at an average current rating of 15 A for up to 11,000 hours
Development of high-temperature, gas-filled, ceramic rectifiers, thyratrons, and voltage-reference tubes Final report, Dec. 15, 1964 - Jan. 26, 1966
Development of high temperature gas filled ceramic rectifiers, thyratrons, and voltage-regulator tube
Self-healing fuse
Fast-acting current limiting device provides current overload protection for vulnerable circuit elements and then re-establishes conduction path within milliseconds. Fuse can also perform as fast-acting switch to clear transient circuit overloads. Fuse takes advantage of large increase in electrical resistivity that occurs when liquid metal vaporizes
Nonlinear Development of the Secular Bar-mode Instability in Rotating Neutron Stars
We have modelled the nonlinear development of the secular bar-mode
instability that is driven by gravitational radiation-reaction (GRR) forces in
rotating neutron stars. In the absence of any competing viscous effects, an
initially uniformly rotating, axisymmetric polytropic star with a ratio
of rotational to gravitational potential energy is driven by
GRR forces to a bar-like structure, as predicted by linear theory. The pattern
frequency of the bar slows to nearly zero, that is, the bar becomes almost
stationary as viewed from an inertial frame of reference as GRR removes energy
and angular momentum from the star. In this ``Dedekind-like'' state, rotational
energy is stored as motion of the fluid in highly noncircular orbits inside the
bar. However, in less than 10 dynamical times after its formation, the bar
loses its initially coherent structure as the ordered flow inside the bar is
disrupted by what appears to be a purely hydrodynamical, short-wavelength,
``shearing'' type instability. The gravitational waveforms generated by such an
event are determined, and an estimate of the detectability of these waves is
presented.Comment: 25 pages, 9 figures, accepted for publication in ApJ, refereed
version, updated, for quicktime movie, see
http://www.phys.lsu.edu/~ou/movie/fmode/new/fmode.b181.om4.2e5.mo
Effect of exhaust nozzle configuration on aerodynamic and acoustic performance of an externally blown flap system with a quiet 6:1 bypass ratio engine
A highly suppressed TF-34 engine was used to investigate engine and flap interaction noise associated with an externally blown flap STOL powered lift system. Noise, efficiency, and velocity decay characteristics of mixed and separate flow exhaust systems including convergent, co-annular, and lobed designs were determined with the engine operating alone. Noise data were then obtained for several of the exhaust configurations with the engine blowing a wing-flap segment. Noise for both the engine alone and the engine with blown flaps showed substantial differences for the various exhaust configurations tested. The differences in observed noise are related primarily to nozzle effective exhaust velocity, flap impingement velocity, and noise spectral shape
Self-healing fuse development
The mercury-filled self-healing fuses developed for this program afford very good protection from circuit faults with rapid reclosure. Fuse performance and design parameters have been characterized. Life tests indicate a capability of 500 fuse operations. Fuse ratings are 150 v at 5, 15, 25 and 50 circuit A. A series of sample fuses using alumina and beryllia insulation have been furnished to NASA for circuit evaluation
Bulk Viscosity in Neutron Stars from Hyperons
The contribution from hyperons to the bulk viscosity of neutron star matter
is calculated. Compared to previous works we use for the weak interaction the
one-pion exchange model rather than a current-current interaction, and include
the neutral current process. Also the sensitivity
to details of the equation of state is examined. Compared to previous works we
find that the contribution from hyperons to the bulk viscosity is about two
orders of magnitude smaller.Comment: 18 pages, to appear in Physical Review
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