5,022 research outputs found
Development of a silver-zinc battery system
Summary report is described of historical documentation and detailed design data for development of silver-zinc battery for use on Surveyor spacecraft. Electrical and physical characteristics of battery models are included, along with data on qualification, acceptance, solar-thermal-vacuum, mission simulation testing, and actual flight performance
Shelf and cycle life evaluation of silver-zinc cells
Silver-zinc cells having a separator system of cross-linked high-density polyethylene with a methacrylic acid graft withstand corrosion when subjected to thermal sterilization treatments
Flat Spectrum X-ray Emission from the Direction of a Molecular Cloud Associated with SNR RX J1713.7-3946
We report on the discovery of a hard X-ray source with ASCA from a molecular
cloud in the vicinity of the SNR RX J1713.7-3946. The energy spectrum (1--10
keV) shows a flat continuum which is described by a power-law with photon index
1.0 +-0.4. We argue that this unusually flat spectrum can be best interpreted
in terms of characteristic bremsstrahlung emission from the
ionization-loss-flattened distribution of either sub-relativistic protons or
mildly-relativistic electrons. The strong shock of the SNR RX J1713.7-3946,
which presumably interacts with the molecular cloud, as evidenced by
observations of CO-lines, seems to be a natural site of acceleration of such
sub- or mildly-relativistic nonthermal particles. However, the observed X-ray
luminosity of 1.7 10^35 erg/s (for 6 kpc distance) requires that a huge kinetic
energy of about 10^50 erg be released in the form of nonthermal particles to
illuminate the cloud. The shock-acceleration at RX J1713.7-3946 can barely
satisfy this energetic requirement, unless (i) the source is located much
closer than 6 kpc and/or (ii) the mechanical energy of the explosion
essentially exceeds 10^51 erg. Another possibility would be that an essential
part of the "lost" energy is somehow converted to plasma waves, which return
this energy to nonthermal particles through their turbulent reacceleration on
plasma waves. Irrespective of mechanisms responsible for production of
high-energy particles, the flat X-ray emission seems to be a signature of a new
striking energetic phenomenon in molecular clouds.Comment: 6 pages, 2 figures, Accepted for publication in PAS
Mechanical quality factor of a sapphire fiber at cryogenic temperatures
A mechanical quality factor of was obtained for the 199
Hz bending vibrational mode in a monocrystalline sapphire fiber at 6 K.
Consequently, we confirm that pendulum thermal noise of cryogenic mirrors used
for gravitational wave detectors can be reduced by the sapphire fiber
suspension.Comment: To be published to Physiscs Letters A. Number of pages: 10 Number of
figures: 5 Number of tables:
Nongassing NiCd battery cell
Method of constructing nickel cadmium batteries prevents excessive gas buildup and allows hermetic sealing of battery for increased service life and reduced maintenance cost
Force measurements of a superconducting-film actuator for a cryogenic interferometric gravitational-wave detector
We measured forces applied by an actuator with a YBCO film at near 77 K for
the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An
actuator consisting of both a YBCO film of 1.6 micrometers thickness and 0.81
square centimeters area and a solenoid coil exerted a force of up to 0.2 mN on
a test mass. The presented actuator system can be used to displace the mirror
of LCGT for fringe lock of the interferometer.Comment: 9 pages, 3 figure
Crystals for Demazure Modules of Classical Affine Lie Algebras
We study, in the path realization, crystals for Demazure modules of affine
Lie algebras of types . We find a special sequence of
affine Weyl group elements for the selected perfect crystal, and show if the
highest weight is l\La_0, the Demazure crystal has a remarkably simple
structure.Comment: Latex, 28 page
Fine-structure in the nonthermal X-ray emission of SNR RX J1713.7-3946 revealed by Chandra
We present morphological and spectroscopic studies of the northwest rim of
the supernova remnant RX J1713.7-3946 based on observations by the Chandra
X-ray observatory. We found a complex network of nonthermal (synchrotron) X-ray
filaments, as well as a 'void' type structure -- a dim region of a circular
shape -- in the northwest rim. It is remarkable that despite distinct
brightness variations, the X-ray spectra everywhere in this region can be well
fitted with a power-law model with photon index around 2.3. We briefly discuss
some implications of these results and argue that the resolved X-ray features
in the northwest rim may challenge the perceptions of standard (diffusive
shock-acceleration) models concerning the production, propagation and radiation
of relativistic particles in supernova remnants.Comment: 8 pages, 9 figures; accepted for publication in A&A; significant
additions for publication in Main journal (previous version was for A&A
Letter); a manuscript (as a single PDF file, 501kb) including all figures is
available at http://www.astro.isas.ac.jp/~uchiyama/publication/h4106.pd
Ab initio study of reflectance anisotropy spectra of a sub-monolayer oxidized Si(100) surface
The effects of oxygen adsorption on the reflectance anisotropy spectrum (RAS)
of reconstructed Si(100):O surfaces at sub-monolayer coverage (first stages of
oxidation) have been studied by an ab initio DFT-LDA scheme within a
plane-wave, norm-conserving pseudopotential approach. Dangling bonds and the
main features of the characteristic RAS of the clean Si(100) surface are mostly
preserved after oxidation of 50% of the surface dimers, with some visible
changes: a small red shift of the first peak, and the appearance of a distinct
spectral structure at about 1.5 eV. The electronic transitions involved in the
latter have been analyzed through state-by-state and layer-by-layer
decompositions of the RAS. We suggest that new interplay between present
theoretical results and reflectance anisotropy spectroscopy experiments could
lead to further clarification of structural and kinetic details of the Si(100)
oxidation process in the sub-monolayer range.Comment: 21 pages, 8 figures. To be published in Physical Rev.
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