754 research outputs found
Apparatus for welding torch angle and seam tracking control Patent
Computer controlled apparatus for maintaining welding torch angle and velocity during seam trackin
Research rocket test RR-1 (Black Brant VC) and RR-2 (Aerobee 170A): Investigations of the stability of bubbles in plain and fiber-reinforced metal and solidified in a near-zero-g environment
The results of the first two of a series of research rocket flights are presented. The objectives of these flights were (1) to learn about the capabilities of these rockets, (2) to learn how to interface the payloads and rockets, and (3) to process some of the composite casting demonstration capsules intended originally for Apollo 15. The capsules contained experiments for investigating the stability of gas bubbles in plain and fiber-reinforced metal melted and solidified in a near-zero-g (0.0119g) environment. The characteristics of the two research rockets, an Aerobee 170A and a Black Brant VC, used to obtain the periods of near-zero-g and the temperature control unit used for processing the contents of the two experiment capsules are discussed
Random Vibration and Torque Tests of Fasteners Secured With Locking Cable, Room Temperature Vulcanized (RTV) Rubber, and Closed Cell Foam to Support the Launch of STS-82
During a walkdown of the Space Transportation System (STS) orbiter for the 82nd Space Shuttle flight (STS-82), technicians found several safety cables for bolts with missing or loose ferrules. Typically, two or three bolts are secured with a cable which passes through one of the holes in the head of each bolt and a ferrule is crimped on each end of the cable to prevent it from coming out of the holes. The purpose of the cable is to prevent bolts from rotating should they become untightened. Other bolts are secured with either a locking cable or wire which is covered with RTV and foam. The RTV and foam would have to be removed to inspect for missing or loose ferrules. To determine whether this was necessary, vibration and torque test fixtures and tests were made to determine whether or not bolts with missing or loose ferrules would unloosen. These tests showed they would not, and the RTV and foam was not removed
The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) Program. III. Optical Spectroscopy
We present the catalog of 477 spectra from the Serendipitous Extragalactic
X-ray Source Identification (SEXSI) program, a survey designed to probe the
dominant contributors to the 2-10 keV cosmic X-ray background. Our survey
covers 1 deg^2 of sky to 2-10 keV fluxes of 10^-14 erg cm^-2 s^-1, and 2 deg^2
for fluxes of 3 x 10^-14 erg cm^-2 s^-1. Our spectra reach to R <24 and have
produced redshifts for 438 hard X-ray sources. The vast majority of the 2-10
keV-selected sample are AGN with redshifts between 0.1 and 3. We find that few
sources at z<1 have high X-ray luminosities, reflecting a dearth of high-mass,
high-accretion-rate sources at low redshift, a result consistent with other
recent wide-area surveys. Half of our sources show significant obscuration,
with N_H>10^22 cm^-2, independent of unobscured luminosity. We classify 168
sources as emission-line galaxies; all are X-ray luminous objects with optical
spectra lacking both high-ionization lines and evidence of a non-stellar
continuum. The redshift distribution of these emission-line galaxies peaks at a
significantly lower redshift than does that of the sources we spectroscopically
identify as AGN. We conclude that few of these sources can be powered by
starburst activity. Stacking spectra for a subset of these sources, we detect
[Ne V] emission, a clear signature of AGN activity, confirming that the
majority of these objects are Seyfert 2s in which the high-ionization lines are
diluted by stellar emission. We find 33 objects lacking broad lines in their
optical spectra which have quasar X-ray luminosities (Lx>10^44 erg s^-1), the
largest sample of such objects identified to date. In addition, we explore 17
AGN associated with galaxy clusters and find that the cluster-member AGN sample
has a lower fraction of broad-line AGN than does the background sample.Comment: Accepted to ApJ; 57 pages, 25 figures, 5 table
Pion and Sigma Polarizabilities and Radiative Transitions
Fermilab E781 plans measurements of gamma-Sigma and -pion
interactions using a 600 GeV beam of Sigmas and pions, and a virtual photon
target. Pion polarizabilities and radiative transitions will be measured in
this experiment. The former can test a precise prediction of chiral symmetry;
the latter for a_1(1260) ----> pi + gamma is important for understanding the
polarizability. The experiment also measures polarizabilities and radiative
transitions for Sigma hyperons. The polarizabilities can test predictions of
baryon chiral perturbation theory. The radiative transitions to the
Sigma*(1385) provide a measure of the magnetic moment of the s-quark. Previous
experimental and theoretical results for gamma-pi and gamma-Sigma interactions
are given. The E781 experiment is described.Comment: 13 pages text (tex), Tel Aviv U. Preprint TAUP 2204-94, uses
Springer-Verlag TEX macro package lecproc.cmm (appended at end of tex file,
following \byebye), which requires extracting lecproc.cmm and putting this
file in your directory in addition to the tex file (mmcd.tex) before tex
processing. lecproc.cmm should be used following instructions and guidelines
available from Springer-Verlag. Submitted to the Proceedings of Workshop on
Chiral Dynamics, Massachusetts Institute of Technology, July 1994, Eds. A.
Bernstein, B. Holstein. Replaced Oct. 4 to add TAUP preprint number. Replaced
Oct. 12 to correct Pb target thickness from 1.3% interaction to 0.3
Ursinus College Alumni Journal, May 1952
President\u27s page • Dr. Paisley honored as layman-of-the-year • Dr. Creese to deliver commencement address • New students enroll for second semester • Dr. Lachman presents bust of Washington • Anne Hughes speaks at Ursinus Color Day • Jeanne Careless is Queen of the May • Summer sessions to open June 9, July 21 • F.B.I. applications • Alumni Day is Saturday, May 31, 1952 • Alumni to entertain seniors at dinner • Nominating committee names candidates • Philadelphia alumni group to reorganize • New York alumni to meet May 7 • Next journal to be mailed November 1952 • Webb enjoys Olympics • Rusty Garlock stars on court for Guam • S. S. Laucks president of York Bar Association • Women\u27s Club enjoys busy spring season • Miss Omwake accepts position at Yale • Bill Daniels returns from work in China • Lt. Col. Bare in Korea • Incidents in the life of a missionary • Sports review: Matmen win 3, lose 4; Alumni asked for Ursinus trophies; Veteran team aims at successful 1952 baseball; Courtmen end season with 7 wins, 10 losses; Badminton team tallies 3 wins, 3 losses; Tennis team faces strong opposition; Mermaids win 3, lose 4; 1952 track prospects look promising; Girls end successful basketball season • Alumni placement at Ursinus • News about ourselves • Necrologyhttps://digitalcommons.ursinus.edu/alumnijournal/1044/thumbnail.jp
rp-Process weak-interaction mediated rates of waiting-point nuclei
Electron capture and positron decay rates are calculated for
neutron-deficient Kr and Sr waiting point nuclei in stellar matter. The
calculation is performed within the framework of pn-QRPA model for rp-process
conditions. Fine tuning of particle-particle, particle-hole interaction
parameters and a proper choice of the deformation parameter resulted in an
accurate reproduction of the measured half-lives. The same model parameters
were used to calculate stellar rates. Inclusion of measured Gamow-Teller
strength distributions finally led to a reliable calculation of weak rates that
reproduced the measured half-lives well under limiting conditions. For the
rp-process conditions, electron capture and positron decay rates on Kr
and Sr are of comparable magnitude whereas electron capture rates on
Sr and Kr are 1--2 orders of magnitude bigger than the
corresponding positron decay rates. The pn-QRPA calculated electron capture
rates on Kr are bigger than previously calculated. The present
calculation strongly suggests that, under rp-process conditions, electron
capture rates form an integral part of weak-interaction mediated rates and
should not be neglected in nuclear reaction network calculations as done
previously.Comment: 13 pages, 4 figures, 4 tables; Astrophysics and Space Science (2012
Strong Coupling Constant from the Photon Structure Function
We extract the value of the strong coupling constant alpha_s from a
single-parameter pointlike fit to the photon structure function F_2^gamma at
large x and Q^2 and from a first five-parameter full (pointlike and hadronic)
fit to the complete F_2^gamma data set taken at PETRA, TRISTAN, and LEP. In
next-to-leading order and the MSbar renormalization and factorization schemes,
we obtain alpha_s(m_Z)=0.1183 +/- 0.0050(exp.)^+0.0029_-0.0028(theor.)
[pointlike] and alpha_s(m_Z)=0.1198 +/- 0.0028(exp.)^+0.0034_-0.0046(theor.)
[pointlike and hadronic]. We demonstrate that the data taken at LEP have
reduced the experimental error by about a factor of two, so that a competitive
determination of alpha_s from F_2^gamma is now possible.Comment: 11 pages, 2 tables, 2 figures. Version accepted for publication by
Phys. Rev. Let
SCUBA sub-millimeter observations of gamma-ray bursters IV. GRB 021004, 021211, 030115, 030226, 041006
We discuss our ongoing program of Target of Opportunity (ToO) sub-millimeter
observations of gamma-ray bursts (GRBs) using the Sub-millimetre Common-User
Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). In this
paper, we present the ToO observations of GRBs 021004, 021211, 030115, 030226,
and 041006. The observations of GRBs 021004, 021211, 030226, and 041006 all
started within ~1 day of the burst, but did not detect any significant
sub-millimeter emission from the reverse shock and/or afterglow. These
observations put some constraints on the models for the early emission,
although the generally poor observing conditions and/or the faintness of these
afterglows at other wavelengths limit the inferences that can be drawn from
these lack of detections. However, these observations demonstrate that SCUBA
can perform rapid observations of GRBs, and provide encouragement for future
observations in the Swift era. None of these GRBs had significant
sub-millimeter emission from their host galaxies. This adds to the indication
that GRBs are not closely linked to the most luminous dusty star-forming
galaxies.Comment: 10 pages, 1 color figure (no information lost if printed in black and
white
The Anomalous Early Afterglow of GRB 050801
The ROTSE-IIIc telescope at the H.E.S.S. site, Namibia, obtained the earliest
detection of optical emission from a Gamma-Ray Burst (GRB), beginning only 21.8
s from the onset of Swift GRB 050801. The optical lightcurve does not fade or
brighten significantly over the first ~250 s, after which there is an
achromatic break and the lightcurve declines in typical power-law fashion. The
Swift/XRT also obtained early observations starting at 69 s after the burst
onset. The X-ray lightcurve shows the same features as the optical lightcurve.
These correlated variations in the early optical and X-ray emission imply a
common origin in space and time. This behavior is difficult to reconcile with
the standard models of early afterglow emission.Comment: 5 pages, 1 figure. Accepted for publication in ApJ Letter
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