14,455 research outputs found
Study and interpretation of lunar close-up stereo photography
The lunar close-up steroscopic camera was used successfully on Apollo 11, 12, and 14 flights. It functioned without any technical faults and was judged convenient to use by all three crews. It recorded a variety of surface textures in the lunar soil, both disturbed and undisturbed, a number of rock surfaces in the undisturbed condition, and a number of surface samples of materials brought to the moon whose interaction with the lunar soil was to be tested. A resolution of approximately 80 microns was aimed for in the design of the camera and was indeed obtained on all pictures. Stereoscopy played a major part in interpreting surface textures and small scale structure
Erosion, transportation and the nature of the Maria
Lunar Orbiter and Apollo photographs of the moon and laboratory simulations of a surface transportation mechanism are discussed. Studies of shoulders at junctions of old mountains with flat mare surfaces show that the crater density in the shoulder is lower than that in the neighboring ground. The crisscross pattern is very pronounced on the mountain slope, is on the shoulder in a smaller scale, and is absent on the mare surface. It is concluded that the material forming the shoulders came there as a consequence of a surface transportation mechanism, and that the shoulders reached their present configuration later than the final shaping of the mare surface. Seismic signal transmission and mascon distribution data indicate that the filling of mare basins did not occur in a similar manner. An electrostatic mechanism for surface transportation was studied experimentally by bombarding material with electrons. An electric field resulted which was capable of dislodging and moving grains. It was also found that the junction line between different materials remains sharp, and materials do not mix even when the junction line itself moves
Evolution of mare surface
Techniques for determining evolution of lunar mare surface
The implications of the ranger moon pictures
Lunar surface erosion evidence - implications of Ranger moon picture
Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane Magnetoresistance in High-Mobility (100) Si Inversion Layers
Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane
Magnetoresistance in High-Mobility (100) Si Inversion LayersComment: 1 page, submitted to PR
Physical properties of the Apollo 12 lunar fines
Optical and radio frequency electrical properties and grain size analyses of Apollo 11 and 12 lunar soil sample
Magnetoresistance of a two-dimensional electron gas in a parallel magnetic field
The conductivity of a two-dimensional electron gas in a parallel magnetic
field is calculated. We take into account the magnetic field induced
spin-splitting, which changes the density of states, the Fermi momentum and the
screening behavior of the electron gas. For impurity scattering we predict a
positive magnetoresistance for low electron density and a negative
magnetoresistance for high electron density. The theory is in qualitative
agreement with recent experimental results found for Si inversion layers and Si
quantum wells.Comment: 4 pages, figures included, PDF onl
Incentives in peer-to-peer and grid networking
Today, most peer-to-peer networks are based on the assumptionthat the participating nodes are cooperative. Thisworks if the nodes are indifferent or ignorant about the resourcesthey offer, but limits the usability of peer-to-peernetworks to very few scenarios. It specifically excludes theirusage in any non-cooperative peer-to-peer environment, beit Grid networks or mobile ad-hoc networks. By introducingsoft incentives to offer resources to other nodes, we seean overall performance gain in traditional file-sharing networks.We also see soft incentives promoting the convergenceof peer-to-peer and Grid networks, as they increasethe predictability of the participating nodes, and thereforethe reliability of the services provided by the system as awhole. Reliability is what is required by Grid networks, butmissing in peer-to-peer networks
On the Disalignment of Interstellar Grains
Several mechanisms have been proposed to explain the alignment of grains with
the interstellar magnetic field, including paramagnetic dissipation, radiative
torques, and supersonic gas-grain streaming. These must compete with
disaligning processes, including randomly directed torques arising from
collisions with gas atoms. I describe a novel disalignment mechanism for grains
that have a time-varying electric dipole moment and that drift across the
magnetic field. Depending on the drift speed, this mechanism may yield a much
shorter disalignment timescale than that associated with random gas atom
impacts. For suprathermally rotating grains, the new disaligning process may be
more potent for carbonaceous dust than for silicate dust. This could result in
efficient alignment for silicate grains but poor alignment for carbonaceous
grains.Comment: 19 pages, 3 figures, submitted to Ap
Chemical species and chemical reactions of importance in nonequilibrium performance calculations
Computer programs to determine inviscid one dimensional and axisymmetric nonequilibrium nozzle flow field
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