129,760 research outputs found
Dynamic Doppler simulator Patent
Equipment for testing of ground station ranging equipment and spacecraft transponder
Improved elastomer for use with oxygen difluoride
Method improves resistance of CIS-1,4-poly(butadiene) elastomers to attack by oxygen difluoride at low temperatures by replacing silica reinforcement with less reactive substances. Improved elastomeric compound is utilized in bladders, diaphragms, valves, O-rings and seals
Arithmetic completely regular codes
In this paper, we explore completely regular codes in the Hamming graphs and
related graphs. Experimental evidence suggests that many completely regular
codes have the property that the eigenvalues of the code are in arithmetic
progression. In order to better understand these "arithmetic completely regular
codes", we focus on cartesian products of completely regular codes and products
of their corresponding coset graphs in the additive case. Employing earlier
results, we are then able to prove a theorem which nearly classifies these
codes in the case where the graph admits a completely regular partition into
such codes (e.g, the cosets of some additive completely regular code).
Connections to the theory of distance-regular graphs are explored and several
open questions are posed.Comment: 26 pages, 1 figur
On the Margulis constant for Kleinian groups, I curvature
The Margulis constant for Kleinian groups is the smallest constant such
that for each discrete group and each point in the upper half space
, the group generated by the elements in which move less
than distance c is elementary. We take a first step towards determining this
constant by proving that if is nonelementary and discrete
with parabolic or elliptic of order , then every point in
is moved at least distance by or where
. This bound is sharp
Segmented back-up bar Patent
Segmented back-up bar for butt welding large tubular structures such as rocket booster bodies or tank
Extraction of black hole coalescence waveforms from noisy data
We describe an independent analysis of LIGO data for black hole coalescence
events. Gravitational wave strain waveforms are extracted directly from the
data using a filtering method that exploits the observed or expected
time-dependent frequency content. Statistical analysis of residual noise, after
filtering out spectral peaks (and considering finite bandwidth), shows no
evidence of non-Gaussian behaviour. There is also no evidence of anomalous
causal correlation between noise signals at the Hanford and Livingston sites.
The extracted waveforms are consistent with black hole coalescence template
waveforms provided by LIGO. Simulated events, with known signals injected into
real noise, are used to determine uncertainties due to residual noise and
demonstrate that our results are unbiased. Conceptual and numerical differences
between our RMS signal-to-noise ratios (SNRs) and the published matched-filter
detection SNRs are discussed.Comment: 15 pages, 11 figures. Version accepted for publicatio
Communications link for SDS 900 series computers
High speed, self-clocking single channel control and data link apparatus interfaces between two computers. This combined system reduces data errors
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