29,180 research outputs found
Corrosion resistant thermal barrier coating
A thermal barrier coating system for protecting metal surfaces at high temperature in normally corrosive environments is described. The thermal barrier coating system includes a metal alloy bond coating, the alloy containing nickel, cobalt, iron, or a combination of these metals. The system further includes a corrosion resistant thermal barrier oxide coating containing at least one alkaline earth silicate. The preferred oxides are calcium silicate, barium silicate, magnesium silicate, or combinations of these silicates
Information retrieval system
Generalized information storage and retrieval system capable of generating and maintaining a file, gathering statistics, sorting output, and generating final reports for output is reviewed. File generation and file maintenance programs written for the system are general purpose routines
Detection of Prolonged Diapause of Northern Corn Rootworm in Michigan (Coleoptera: Chrysomelidae)
Prolonged diapause of northern corn rootworm, while known from other Midwestern states, has not previously been reported in Michigan. Populations of northern corn rootworm, (Diabrotica barberi) from two first-year corn fields in Genesee County, Michigan were examined for prolonged egg diapause. Pro- longed diapause was suspected in these populations due to an unusually high proportion of northern versus western corn rootworms in these fields. Eggs obtained from females collected at these sites were reared in the laboratory for two years. The presence of the prolonged diapause trait was confirmed in one population by eggs which hatched following two simulated winters (7.3%). None of the eggs m the second population hatched following the second chill period, however, some eggs in this population remained in apparent diapause at the end of two years. The potential for using observed population shifts in favor of D. barberi as an early warning of the expansion of prolonged diapause in a population is discussed
Production of Millisecond Dips in Sco X-1 Count Rates by Dead Time Effects
Chang et al. (2006) reported millisecond duration dips in the X-ray intensity
of Sco X-1 and attributed them to occultations of the source by small
trans-Neptunian objects (TNOs). We have found multiple lines of evidence that
these dips are not astronomical in origin, but rather the result of high-energy
charged particle events in the RXTE PCA detectors. Our analysis of the RXTE
data indicates that at most 10% of the observed dips in Sco X-1 could be due to
occultations by TNOs, and, furthermore, we find no positive or supporting
evidence for any of them being due to TNOs. We therefore believe that it is a
mistake to conclude that any TNOs have been detected via occultation of Sco
X-1.Comment: Submitted to ApJ; uses emulateapj.cls, 8 pages with 8 figure
Suboptimal filtering. Part 2 - Compensation for modeling errors in orbit determination problems Final report
Compensation for dynamic and measurement model errors in real time orbit determination system
The Stellar and Gas Kinematics of Several Irregular Galaxies
We present long-slit spectra of three irregular galaxies from which we
determinethe stellar kinematics in two of the galaxies (NGC 1156 and NGC 4449)
and ionized-gas kinematics in all three (including NGC 2366). We compare this
to the optical morphology and to the HI kinematics of the galaxies. In the
ionized gas, we see a linear velocity gradient in all three galaxies. In NGC
1156 we also detect a weak linear velocity gradient in the stars of (5+/-1/sin
i) km/s/kpc to a radius of 1.6 kpc. The stars and gas are rotating about the
same axis, but this is different from the major axis of the stellar bar which
dominates the optical light of the galaxy. In NGC 4449 we do not detect
organized rotation of the stars and place an upper limit of (3/sin i) km/s/kpc
to a radius of 1.2 kpc. For NGC 4449, which has signs of a past interaction
with another galaxy, we develop a model to fit the observed kinematics of the
stars and gas. In this model the stellar component is in a rotating disk seen
nearly face-on while the gas is in a tilted disk with orbits whose planes
precess in the gravitational potential. This model reproduces the apparent
counter-rotation of the inner gas of the galaxy. The peculiar orbits of the gas
are presumed due to acquisition of gas in the past interaction.Comment: To be published in ApJ, November 20, 200
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