41,418 research outputs found
Evaluation of radar imagery of highly faulted volcanic terrain in southeast Oregon
Aerial radar imagery of highly faulted volcanic terrain in southeast Orego
Space environmental work simulator Patent
Space environmental work simulator with portions of space suit mounted to vacuum chamber wal
National and international freight transport models: overview and ideas for further development
This paper contains a review of the literature on freight transport models, focussing on the types of models that have been developed since the nineties for forecasting, policy simulation and project evaluation at the national and international level. Models for production, attraction, distribution, modal split and assignment are discussed in the paper. Furthermore, the paper also includes a number of ideas for future development, especially for the regional and urban components within national freight transport models
Effects of Nitrogen Quenching Gas on Spin-Exchange Optical Pumping of He-3
We consider the degree of conservation of nuclear spin polarization in the
process of optical pumping under typical spin-exchange optical pumping
conditions. Previous analyses have assumed that negligible nuclear spin
precession occurs in the brief periods of time the alkali-metal atoms are in
the excited state after absorbing photons and before undergoing quenching
collisions with nitrogen molecules. We include excited-state hyperfine
interactions, electronic spin relaxation in collisions with He and N_2,
spontaneous emission, quenching collisions, and a simplified treatment of
radiation trapping
Bayesian analysis of resolved stellar spectra: application to MMT/Hectochelle Observations of the Draco dwarf spheroidal
We introduce a Bayesian method for fitting faint, resolved stellar spectra in
order to obtain simultaneous estimates of redshift and stellar-atmospheric
parameters. We apply the method to thousands of spectra---covering 5160-5280
Angs. at resolution R~20,000---that we have acquired with the MMT/Hectochelle
fibre spectrograph for red-giant and horizontal branch candidates along the
line of sight to the Milky Way's dwarf spheroidal satellite in Draco. The
observed stars subtend an area of ~4 deg^2, extending ~3 times beyond Draco's
nominal `tidal' radius. For each spectrum we tabulate the first four
moments---central value, variance, skewness and kurtosis---of posterior
probability distribution functions representing estimates of the following
physical parameters: line-of-sight velocity v_los, effective temperature
(T_eff), surface gravity (logg) and metallicity ([Fe/H]). After rejecting
low-quality measurements, we retain a new sample consisting of 2813 independent
observations of 1565 unique stars, including 1879 observations for 631 stars
with (as many as 13) repeat observations. Parameter estimates have median
random errors of sigma_{v_los}=0.88 km/s, sigma_{T_eff}=162 K, sigma_logg=0.37
dex and sigma_[Fe/H]=0.20 dex. Our estimates of physical parameters distinguish
~470 likely Draco members from interlopers in the Galactic foreground.Comment: published in Monthly Notices of the Royal Astronomical Society, all
data are publicly available at the following address:
http://www.andrew.cmu.edu/user/mgwalker/hectochelle
Cork-resin ablative insulation for complex surfaces and method for applying the same
A method of applying cork-resin ablative insulation material to complex curved surfaces is disclosed. The material is prepared by mixing finely divided cork with a B-stage curable thermosetting resin, forming the resulting mixture into a block, B-stage curing the resin-containing block, and slicing the block into sheets. The B-stage cured sheet is shaped to conform to the surface being insulated, and further curing is then performed. Curing of the resins only to B-stage before shaping enables application of sheet material to complex curved surfaces and avoids limitations and disadvantages presented in handling of fully cured sheet material
A simple model of proton damage in GaAs solar cells
A simple proton damage model for GaAs solar cells is derived and compared to experimental values of change in short circuit currents. The recombination cross section associated with the defects was determined from the experimental comparison to be approximately 1.2 x 10 to the -13th power sq cm in fair agreement with values determined from the deep level transient spectroscopy technique
Systemic Proper Motions of Milky Way Satellites from Stellar Redshifts: the Carina, Fornax, Sculptor and Sextans Dwarf Spheroidals
The transverse motions of nearby dwarf spheroidal (dSph) galaxies contribute
line-of-sight components that increase with angular distance from the dSph
centers, inducing detectable gradients in stellar redshift. In the absence of
an intrinsic velocity gradient (e.g., due to rotation or streaming), an
observed gradient in the heliocentric rest frame (HRF) relates simply to a
dSph's systemic proper motion (PM). Kinematic samples for the Milky Way's
brightest dSph satellites are now sufficiently large that we can use stellar
redshifts to constrain systemic PMs independently of astrometric data. Data
from our Michigan/MIKE Fiber System (MMFS) Survey reveal significant HRF
velocity gradients in Carina, Fornax and Sculptor, and no significant gradient
in Sextans. Assuming there are no intrinsic gradients, the data provide a
relatively tight constraint on the PM of Fornax,
(mu_{alpha}^{HRF},mu_{delta}^{HRF})=(+48 +/- 15,-25 +/- 14) mas/century, that
agrees with published HST astrometric measurements. Smaller data sets yield
weaker constraints in the remaining galaxies, but our Carina measurement,
(mu_{alpha}^{HRF},mu_{delta}^{HRF})=(+25 +/- 36,+16 +/- 43) mas/century, agrees
with the published astrometric value. The disagreement of our Sculptor
measurement, (mu_{alpha}^{HRF},mu_{delta}^{HRF})= (-40 +/- 29, -69 +/- 47)
mas/century, with astrometric measurements is expected if Sculptor has a
rotational component as reported by Battaglia et al. (2008). For Sextans, which
at present lacks an astrometric measurement, we measure
(mu_{alpha}^{HRF},mu_{delta}^{HRF})=(-26 +/- 41, +10 +/- 44) mas/century.Comment: Accepted for Publication by ApJ Letter
Wolf Creek Dam: Instrumentation & Monitoring
Wolf Creek Dam was designed and constructed between 1932 and 1952. The approximate 1 mile long combination concrete gravity and earth fill structure is located on the Cumberland River near Jamestown, KY and stores up to six million ac-ft at the maximum flood pool storage level. In 1967-1968, seepage in the foundation of the embankment section was evidenced by sinkholes and muddy flows identified on the downstream side of the dam and Instruments identified seepage through the dam foundation. A concrete barrier wall was constructed in 1975-1979, however dam monitoring in 2004 indicated that seepage persisted through the foundation. Currently, a new barrier wall is under construction to penetrate deeper into the foundation than the previous barrier. Additional instrumentation was installed to monitor construction and ensure the new barrier wall is effective. The purpose of this paper is to document the history of Wolf Creek Dam, the current barrier wall construction, and the extensive instrumentation monitoring implemented throughout the project life. In addition, the paper will highlight common instrumentation data errors, their implications, and ways to identify and prevent them in future projects
- …