27,038 research outputs found
Automatic communication signal monitoring system
A system is presented for automatic monitoring of a communication signal in the RF or IF spectrum utilizing a superheterodyne receiver technique with a VCO to select and sweep the frequency band of interest. A first memory is used to store one band sweep as a reference for continual comparison with subsequent band sweeps. Any deviation of a subsequent band sweep by more than a predetermined tolerance level produces an alarm signal which causes the band sweep data temporarily stored in one of two buffer memories to be transferred to long-term store while the other buffer memory is switched to its store mode to assume the task of temporarily storing subsequent band sweeps
The Detailed Chemical Abundance Patterns of M31 Globular Clusters
We present detailed chemical abundances for 20 elements in 30
globular clusters in M31. These results have been obtained using high
resolution (24,000) spectra of their integrated
light and analyzed using our original method. The globular clusters have
galactocentric radii between 2.5 kpc and 117 kpc, and therefore provide
abundance patterns for different phases of galaxy formation recorded in the
inner and outer halo of M31. We find that the clusters in our survey have a
range in metallicity of [Fe/H]. The inner halo clusters cover
this full range, while the outer halo globular clusters at R20 kpc have a
small range in abundance of [Fe/H]. We also measure abundances
of alpha, r- and s-process elements. These results constitute the first
abundance pattern constraints for old populations in M31 that are comparable to
those known for the Milky Way halo.Comment: XII International Symposium on Nuclei in the Cosmos August 5-12, 2012
Cairns, Australia. To appear in Proceedings of Scienc
Globular Cluster Abundances from High-Resolution, Integrated-Light Spectroscopy. II. Expanding the Metallicity Range for Old Clusters and Updated Analysis Techniques
We present abundances of globular clusters in the Milky Way and Fornax from
integrated light spectra. Our goal is to evaluate the consistency of the
integrated light analysis relative to standard abundance analysis for
individual stars in those same clusters. This sample includes an updated
analysis of 7 clusters from our previous publications and results for 5 new
clusters that expand the metallicity range over which our technique has been
tested. We find that the [Fe/H] measured from integrated light spectra agrees
to 0.1 dex for globular clusters with metallicities as high as
[Fe/H]=, but the abundances measured for more metal rich clusters may be
underestimated. In addition we systematically evaluate the accuracy of
abundance ratios, [X/Fe], for Na I, Mg I, Al I, Si I, Ca I, Ti I, Ti II, Sc II,
V I, Cr I, Mn I, Co I, Ni I, Cu I, Y II, Zr I, Ba II, La II, Nd II, and Eu II.
The elements for which the integrated light analysis gives results that are
most similar to analysis of individual stellar spectra are Fe I, Ca I, Si I, Ni
I, and Ba II. The elements that show the greatest differences include Mg I and
Zr I. Some elements show good agreement only over a limited range in
metallicity. More stellar abundance data in these clusters would enable more
complete evaluation of the integrated light results for other important
elements.Comment: Accepted for publication in ApJ, 37 pages, 13 tables, 29 figure
Charged-Current Disappearance Measurements in the NuMI Off-Axis Beam
This article studies the potential of combining charged-current disappearance
measurements of \nu_{\mu} to \nu_{\tau} from MINOS and an off-axis beam. I find
that the error on \Delta m^2 from a 100 kt-yr off-axis measurement is a few
percent of itself. Further, I find little improvement to an off-axis
measurement by combining it with MINOS.Comment: Presented at NuFact'02. Four pages, three figure
Commutating brushes tested in dc motors in dry argon atmospheres
Test apparatus, procedures, and results are given for dc-motor brushes operating in dry argon. Minimum concentrations of argon impurities are also determined
- …