45,033 research outputs found
Application of redundancy in the Saturn 5 guidance and control system
The Saturn launch vehicle's guidance and control system is so complex that the reliability of a simplex system is not adequate to fulfill mission requirements. Thus, to achieve the desired reliability, redundancy encompassing a wide range of types and levels was employed. At one extreme, the lowest level, basic components (resistors, capacitors, relays, etc.) are employed in series, parallel, or quadruplex arrangements to insure continued system operation in the presence of possible failure conditions. At the other extreme, the highest level, complete subsystem duplication is provided so that a backup subsystem can be employed in case the primary system malfunctions. In between these two extremes, many other redundancy schemes and techniques are employed at various levels. Basic redundancy concepts are covered to gain insight into the advantages obtained with various techniques. Points and methods of application of these techniques are included. The theoretical gain in reliability resulting from redundancy is assessed and compared to a simplex system. Problems and limitations encountered in the practical application of redundancy are discussed as well as techniques verifying proper operation of the redundant channels. As background for the redundancy application discussion, a basic description of the guidance and control system is included
Boundary layer separation on a liquid sphere
Boundary layer separation on liquid spher
Catalog of meteorites in the collections of Arizona State University, including the Nininger Meteorite Collection
Catalog of meteorites in Arizona State University collectio
Comments on the nature of the outside boundary layer on a liquid sphere in a steady, uniform stream
Nature of outside boundary layer on liquid sphere in steady, uniform strea
Use of Remote Surface Based Tools for Visualizing Integrated Brain Imaging Data
We describe a surface-based approach to 3D visualization of integrated neuroimaging data. Our web-enabled software allows researchers to use these visualization tools over the Internet. We present examples of brain imaging studies where such remote surface-based visualization techniques have proven to be quite effective
Brain Visualization in Java3D
BrainJ3D is a cross-platform Java/Java3D software toolkit for processing and visualizing brain imaging data, which 1) contains general purpose tools for reconstructing, mapping and visualizing integrated structural and functional images and 2) leverages Java's Remote Method Invocation to provide both a standalone and a client/server mode
Resolving the Structure of Cold Dark Matter Halos
We examine the effects of mass resolution and force softening on the density
profiles of cold dark matter halos that form within cosmological N-body
simulations. As we increase the mass and force resolution, we resolve
progenitor halos that collapse at higher redshifts and have very high
densities. At our highest resolution we have nearly 3 million particles within
the virial radius, several orders of magnitude more than previously used and we
can resolve more than one thousand surviving dark matter halos within this
single virialised system. The halo profiles become steeper in the central
regions and we may not have achieved convergence to a unique slope within the
inner 10% of the virialised region. Results from two very high resolution halo
simulations yield steep inner density profiles, . The
abundance and properties of arcs formed within this potential will be different
from calculations based on lower resolution simulations. The kinematics of
disks within such a steep potential may prove problematic for the CDM model
when compared with the observed properties of halos on galactic scales.Comment: Final version, to be published in the ApJLetter
RTCC requirements for mission G - Trajectory computers for TLI and MCC processors, part 1 Final report
Functional properties of trajectory computers for translunar injection and midcourse correction procedures on lunar orbit
5D Black Rings and 4D Black Holes
It has recently been shown that the M theory lift of a IIA 4D BPS Calabi-Yau
black hole is a 5D BPS black hole spinning at the center of a Taub-NUT-flux
geometries, and a certain linear relation between 4D and 5D BPS partition
functions was accordingly proposed. In the present work we fortify and enrich
this proposal by showing that the M-theory lift of the general 4D multi-black
hole geometry are 5D black rings in a Taub-NUT-flux geometry.Comment: 8 pages; version 2, with additional references and explanation
Percolation Analysis of a Wiener Reconstruction of the IRAS 1.2 Jy Redshift Catalog
We present percolation analyses of Wiener Reconstructions of the IRAS 1.2 Jy
Redshift Survey. There are ten reconstructions of galaxy density fields in real
space spanning the range to , where
, is the present dimensionless density and
is the bias factor. Our method uses the growth of the largest cluster
statistic to characterize the topology of a density field, where Gaussian
randomized versions of the reconstructions are used as standards for analysis.
For the reconstruction volume of radius, Mpc,
percolation analysis reveals a slight `meatball' topology for the real space,
galaxy distribution of the IRAS survey.
cosmology-galaxies:clustering-methods:numericalComment: Revised version accepted for publication in The Astrophysical
Journal, January 10, 1997 issue, Vol.47
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