17,125 research outputs found
Publications of the Jet Propulsion Laboratory July 1965 through July 1966
Bibliography on Jet Propulsion Laboratory technical reports and memorandums, space programs summary, astronautics information, and literature searche
Publications of the Jet Propulsion Laboratory, July 1964 through June 1965
JPL publications bibliography with abstracts - reports on DSIF, Mariner program, Ranger project, Surveyor project, and other space programs, and space science
Investigation of real-gas and viscous effects on the aerodynamic characteristics of a 40 deg half-cone with suggested correlations for the shuttle orbiter
Parameters were evaluated that might be used to correlate shuttle orbiter aerodynamic data to be used in extrapolating from wind-tunnel to flight conditions. Preliminary calculations indicate that the lee-side forces will have an insignificant influence on the aerodynamic characteristics of the orbiter for moderate angle-of-attack entries; therefore, this work is focused on phenomena which have an overriding influence on windward forces, namely, real-gas (equilibrium and nonequilibrium) and viscous-interaction effects. Analytically determined flow fields previously obtained on 40 deg blunted cones were used as a data source to evaluate various correlation parameters. Inviscid effects were found to be the dominant contributor to the aerodynamic coefficients in the altitude range of 64 to 76.2 km. The most suitable correlation of the aerodynamic forces on these cones is based on local dynamic pressure and local Mach number
Launch vehicle effluent measurements during the May 12, 1977, Titan 3 launch at Air Force Eastern Test Range
Airborne effluent measurements and cloud physical behavior for the May 21, 1977, Titan 3 launch from the Air Force Eastern Test Range, Fla. are presented. The monitoring program included airborne effluent measurements in situ in the launch cloud, visible and infrared photography of cloud growth and physical behavior, and limited surface collection of rain samples. Airborne effluent measurements included concentrations of HCl, NO, NOx, and aerosols as a function of time in the exhaust cloud. For the first time in situ particulate mass concentration and aerosol number density were measured as a function of time and size in the size range of 0.05 to 25 micro meters diameter. Measurement results were similar to those of earlier launch monitorings. Maximum HCl and NOx concentrations ranged from 10 ppm and 500 ppb, respectively, several minutes after launch to about 1 ppm and 100 ppb at 45 minutes after launch
Publications of the Jet Propulsion Laboratory, July 1966 - June 1967 - A bibliography
Bibliography with abstracts of official reports in sciences and engineering as released by Jet Propulsion Laboratory, July 1966 - June 196
Population synthesis of accreting white dwarfs: II. X-ray and UV emission
Accreting white dwarfs (WDs) with non-degenerate companions are expected to
emit in soft X-rays and the UV, if accreted H-rich material burns stably. They
are an important component of the unresolved emission of elliptical galaxies,
and their combined ionizing luminosity may significantly influence the optical
line emission from warm ISM. In an earlier paper we modeled populations of
accreting WDs, first generating WD with main-sequence, Hertzsprung gap and red
giant companions with the population synthesis code \textsc{BSE}, and then
following their evolution with a grid of evolutionary tracks computed with
\textsc{MESA}. Now we use these results to estimate the soft X-ray
(0.3-0.7keV), H- and He II-ionizing luminosities of nuclear burning WDs and the
number of super-soft X-ray sources for galaxies with different star formation
histories. For the starburst case, these quantities peak at Gyr and
decline by orders of magnitude by the age of 10 Gyr. For stellar
ages of ~10 Gyr, predictions of our model are consistent with soft X-ray
luminosities observed by Chandra in nearby elliptical galaxies and He II
4686 line ratio measured in stacked SDSS spectra of retired
galaxies, the latter characterising the strength and hardness of the UV
radiation field. However, the soft X-ray luminosity and
He~II~4686 ratio are significantly overpredicted for stellar
ages of Gyr. We discuss various possibilities to resolve this
discrepancy and tentatively conclude that it may be resolved by a modification
of the typically used criteria of dynamically unstable mass loss for giant
stars.Comment: 13 pages, 12 figures, MNRAS accepte
Next generation population synthesis of accreting white dwarfs: I. Hybrid calculations using BSE + MESA
Accreting, nuclear-burning white dwarfs have been deemed to be candidate
progenitors of type Ia supernovae, and to account for supersoft X-ray sources,
novae, etc. depending on their accretion rates. We have carried out a binary
population synthesis study of their populations using two algorithms. In the
first, we use the binary population synthesis code \textsf{BSE} as a baseline
for the "rapid" approach commonly used in such studies. In the second, we
employ a "hybrid" approach, in which we use \textsf{BSE} to generate a
population of white dwarfs (WD) with non-degenerate companions on the verge of
filling their Roche lobes. We then follow their mass transfer phase using the
detailed stellar evolution code \textsf{MESA}. We investigate the evolution of
the number of rapidly accreting white dwarfs (RAWDs) and stably nuclear-burning
white dwarfs (SNBWDs), and estimate the type Ia supernovae (SNe Ia) rate
produced by "single-degenerate" systems (SD). We find significant differences
between the two algorithms in the predicted numbers of SNBWDs at early times,
and also in the delay time distribution (DTD) of SD SNe Ia. Such differences in
the treatment of mass transfer may partially account for differences in the SNe
Ia rate and DTD found by different groups. Adopting 100\% efficiency for helium
burning, the rate of SNe Ia produced by the SD-channel in a Milky-way-like
galaxy in our calculations is , more than an
order of magnitude below the observationally inferred value. In agreement with
previous studies, our calculated SD DTD is inconsistent with observations.Comment: 13 pages,11 figures, accepted by MNRA
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