37,715 research outputs found
Coastal wave measurements during passage of tropical storm Amy
Aerial photographic and laser profilometer data of waves generated by tropical storm Amy are presented. The data mission consisted primarily of two legs, one in the direction of the wind waves, and the second along the direction of swell propagation, using Jennette's Pier at Nags Head, North Carolina, as a focal point. At flight time, Amy's center was 512 nmi from shore and had maximum winds of 60 knots. The storm's history is presented, along with a satellite photograph, showing the extent of the storm on the day of the flight. Flight ground tracks are presented along with sample aerial photographs of the wave conditions showing approximate wavelength and direction. Sample wave energy spectra are presented both from the laser profilometer onboard the aircraft, and from the Corps of Engineers Research Center (CERC) shore gauge at Nags Head, North Carolina
Polymerizable disilanols having in-chain perfluoroalkyl groups
Disilanols containing in-chain perfluoroalkyl and aromatic groups and the process by which they were prepared are discussed. The disilanols, when reacted with a diaminosilane and cured, produce polymeric material resistant to hydrocarbon fuels and stable at elevated temperatures
Network simulation using the simulation language for alternate modeling (SLAM 2)
The simulation language for alternate modeling (SLAM 2) is a general purpose language that combines network, discrete event, and continuous modeling capabilities in a single language system. The efficacy of the system's network modeling is examined and discussed. Examples are given of the symbolism that is used, and an example problem and model are derived. The results are discussed in terms of the ease of programming, special features, and system limitations. The system offers many features which allow rapid model development and provides an informative standardized output. The system also has limitations which may cause undetected errors and misleading reports unless the user is aware of these programming characteristics
Angle-of-attack analysis of a spinning slender cone with slight aerodynamic and mass asymmetries /reentry F/
Angle of attack analysis of spinning slender reentry cone with slight aerodynamic and mass asymmetrie
Turbid water measurements of remote sensing penetration depth at visible and near-infrared wavelength
Remote sensing of water quality is dicussed. Remote sensing penetration depth is a function both of water type and wavelength. Results of three tests to help demonstrate the magnitude of this dependence are presented. The water depth to which the remote-sensor data was valid was always less than that of the Secchi disk depth, although not always the same fraction of that depth. The penetration depths were wavelength dependent and showed the greatest variation for the water type with largest Secchi depth. The presence of a reflective plate, simulating a reflective subsurface, increased the apparent depth of light penetration from that calculated for water of infinite depth
12 New Galactic Wolf-Rayet Stars Identified via 2MASS+Spitzer/GLIMPSE
We report new results from our effort to identify obscured Wolf-Rayet stars
in the Galaxy. Candidates were selected by their near-infrared (2MASS) and
mid-infrared (Spitzer/GLIMPSE) color excesses, which are consistent with
free-free emission from ionized stellar winds and thermal excess from hot dust.
We have confirmed 12 new Wolf-Rayet stars in the Galactic disk, including 9 of
the nitrogen subtype (WN), and 3 of the carbon subtype (WC); this raises the
total number of Wolf-Rayet stars discovered with our approach to 27. We
classify one of the new stars as a possible dust-producing WC9d+OBI
colliding-wind binary, as evidenced by an infrared excess resembling that of
known WC9d stars, the detection of OBI features superimposed on the WC9
spectrum, and hard X-ray emission detected by XMM-Newton. A WC8 star in our
sample appears to be a member of the stellar cluster Danks 1, in contrast to
the rest of the confirmed Wolf-Rayet stars that generally do not appear to
reside within dense stellar clusters. Either the majority of the stars are
runaways from clusters, or they formed in relative isolation. We briefly
discuss prospects for the expansion and improvement of the search for
Wolf-Rayet stars throughout the Milky Way Galaxy.Comment: Submitted to PASP March 12, 2009; Accepted on May 14, 200
Computer program to generate attitude error equations for a gimballed platform
Computer program for solving attitude error equations related to gimballed platform is described. Program generates matrix elements of attitude error equations when initial matrices and trigonometric identities have been defined. Program is written for IBM 360 computer
Red Eyes on Wolf-Rayet Stars: 60 New Discoveries via Infrared Color Selection
We have spectroscopically identified 60 Galactic Wolf-Rayet (WR) stars,
including 38 nitrogen types (WN) and 22 carbon types (WC). Using photometry
from the Spitzer/GLIMPSE and 2MASS databases, the WRs were selected via a
method we have established that exploits their unique infrared colors, which is
mainly the result of excess radiation from free-free scattering within their
dense ionized winds. The selection criteria has been refined since our last
report, and now yields WRs at a rate of ~20% in spectroscopic follow-up of
candidates that comprise a broad color space defined by the color distribution
of all known WRs having B>14 mag. However, there are subregions within the
broad color space which yield WRs at a rate of >50%. Cross-correlation of WR
candidates with archival X-ray point-source catalogs increases the WR detection
rate of the broad color space to ~40%; ten new WR X-ray sources have been
found, in addition to a previously unrecognized X-ray counterpart to a known
WR. The extinction values, distances, and galactocentric radii of all new WRs
are calculated using the method of spectroscopic parallax. Although the
majority of the new WRs have no obvious association with stellar clusters, two
WC8 stars reside in a previously unknown massive-star cluster that lies near
the intersection of the Scutum-Centaurus Arm and the Galaxy's bar, in which
five OB supergiants were also identified. In addition, two WC and four WN stars
were identified in association with the stellar clusters Danks 1 and 2. A WN9
star has also been associated with the cluster [DBS2003] 179. This work brings
the total number of known Galactic WRs to 476, or ~7-8% of the total
empirically estimated population. An examination of their Galactic distribution
reveals a tracing of spiral arms and an enhanced WR surface density toward
several massive-star formation sites (abridged).Comment: Accepted to the Astronomical Journal on May 20, 2011. Document is 39
pages, including 20 figures and 8 table
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