2,361 research outputs found
An experimental investigation of the flow field for double-wedge configurations in a Mach 4.97 stream
The viscous-inviscid interactions which perturb the flow around the wing leading edge are discussed. The flow field perturbation results when the fuselage-generated shock wave interacts with the wing-generated shock wave. Three types of shock interference patterns are possible for the wing leading edge of the orbiter
Small carbon chains in circumstellar envelopes
Observations were made for a number of carbon-rich circumstellar envelopes
using the Phoenix spectrograph on the Gemini South telescope to determine the
abundance of small carbon chain molecules. Vibration-rotation lines of the
antisymmetric stretch of C near 2040 cm (4.902 m)
have been used to determine the column density for four carbon-rich
circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We
additionally calculate the column density of C for IRC +10216, and
provide an upper limit for 5 more objects. An upper limit estimate for the
C column density is also provided for IRC+10216. A comparison of these
column densities suggest a revision to current circumstellar chemical models
may be needed
FORMS AND "TYPES" IN THE STUDY OF HUMAN BEHAVIOR: An Examination of the Generalizing Concepts of Mead and Schutz
http://web.ku.edu/~starjrn
Fluorine in the solar neighborhood - is it all produced in AGB-stars?
The origin of 'cosmic' fluorine is uncertain, but there are three proposed
production sites/mechanisms: AGB stars, nucleosynthesis in Type II
supernovae, and/or the winds of Wolf-Rayet stars. The relative importance of
these production sites has not been established even for the solar
neighborhood, leading to uncertainties in stellar evolution models of these
stars as well as uncertainties in the chemical evolution models of stellar
populations.
We determine the fluorine and oxygen abundances in seven bright, nearby
giants with well-determined stellar parameters. We use the 2.3 m
vibrational-rotational HF line and explore a pure rotational HF line at 12.2
m. The latter has never been used before for an abundance analysis. To be
able to do this we have calculated a line list for pure rotational HF lines. We
find that the abundances derived from the two diagnostics agree.
Our derived abundances are well reproduced by chemical evolution models only
including fluorine production in AGB-stars and therefore we draw the conclusion
that this might be the main production site of fluorine in the solar
neighborhood. Furthermore, we highlight the advantages of using the 12 m
HF lines to determine the possible contribution of the -process to the
fluorine budget at low metallicities where the difference between models
including and excluding this process is dramatic
How Environmental Litigation Has Turned Pipelines Into Pipe Dreams
Proposed oil and gas pipelines have faced a myriad of legal challenges in the past several years. Even where pipeline proponents have prevailed, the cost and delay of protracted litigation has often caused cancellation of pipeline projects. In addition, presidential transitions have led to abrupt reversals of pipeline policies, which courts have often reviewed skeptically. This Article explores the regulatory framework for pipeline construction and analyzes recent lawsuits, describing the legal requirements that agencies must follow to change policies and discussing policies of the Obama and Trump Administrations in context of the legal challenges. It concludes by analyzing the approaches taken by pipeline opponents and discussing implications for future projects
The time variation in infrared water-vapour bands in Mira variables
The time variation in the water-vapour bands in oxygen-rich Mira variables
has been investigated using multi-epoch ISO/SWS spectra of four Mira variables
in the 2.5-4.0 micron region. All four stars show H2O bands in absorption
around minimum in the visual light curve. At maximum, H2O emission features
appear in the ~3.5-4.0 micronm region, while the features at shorter
wavelengths remain in absorption. These H2O bands in the 2.5-4.0 micron region
originate from the extended atmosphere.
The analysis has been carried out with a disk shape, slab geometry model. The
observed H2O bands are reproduced by two layers; a `hot' layer with an
excitation temperature of 2000 K and a `cool' layer with an excitation
temperature of 1000-1400 K. The radii of the `hot' layer (R_hot) are ~1 R_* at
visual minimum and 2 R_* at maximum, where R_* is a radius of background source
of the model. The time variation of R_hot/R_* from 1 to 2 is attributed to the
actual variation in the radius of the H2O layer. A high H2O density shell
occurs near the surface of the star around minimum, and moves out with the
stellar pulsation. This shell gradually fades away after maximum, and a new
high H2O density shell is formed in the inner region again at the next minimum.
Due to large optical depth of H2O, the near-infrared variability is dominated
by the H2O layer, and the L'-band flux correlates with the area of the H2O
shell. The infrared molecular bands trace the structure of the extended
atmosphere and impose appreciable effects on near-infrared light curve of Mira
variables.Comment: 15 pages, 16 figures, accepted by A&
A computer program for hydrostatic bearings including the effects of non-uniform film thickness and relative velocity for various methods of lubricant supply final technical report
Computer program for hydrostatic bearing - effects of nonuniform film thickness and lubricant suppl
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