14 research outputs found
Propeller performance and weight predictions appended to the Navy/NASA engine program
The Navy/NASA Engine Performance (NNEP) is a general purpose computer program currently employed by government, industry and university personnel to simulate the thermodynamic cycles of turbine engines. NNEP is a modular program which has the ability to evaluate the performance of an arbitrary engine configuration defined by the user. In 1979, a program to calculate engine weight (WATE-2) was developed by Boeing's Military Division under NASA contract. This program uses a preliminary design approach to determine engine weights and dimensions. Because the thermodynamic and configuration information required by the weight code was available in NNEP, the weight code was appended to NNEP. Due to increased emphasis on fuel economy, a renewed interest has developed in propellers. This report describes the modifications developed by NASA to both NNEP and WATE-2 to determine the performance, weight and dimensions of propellers and the corresponding gearbox. The propeller performance model has three options, two of which are based on propeller map interpolation. Propeller and gearbox weights are obtained from empirical equations which may easily be modified by the user
Photoluminescence spectroscopy of YVO:Eu nanoparticles with aromatic linker molecules: a precursor to biomedical functionalization
Photoluminescence spectra of YVO:Eu nanoparticles are
presented,with and without the attachment of of organic linker molecules that
are proposed for linking to biomolecules. YVO:Eu nanoparticles
with 5% dopant concentration were synthesized by wet chemical synthesis. X-ray
diffraction and transmission electron microscopy show the expected wakefieldite
structure of tetragonal particles with an average size of 17 nm.
Fourier-transform infrared spectroscopy determines that metal-carboxylate
coordination is successful in replacing the native metal-hydroxyl bonds with
three organic linkers, namely benzoic acid, 3-nitro 4-chloro-benzoic acid and
3,4-dihydroxybenzoic acid, in separate treatments. UV-excitation
photoluminescence spectra show that the position and intensity of dominant
electric-dipole transition at 619 nm is unaffected by the
benzoic acid and 3-nitro 4-chloro-benzoic acid treatments. Attachment of the
3,4-dihydroxybenzoic acid produces an order-of-magnitude quenching of the
photoluminescence, due to the presence of high-frequency modes in the linker.
Ratios of the dominant electric- and magnetic-dipole transitions confirm
infrared measurements, which indicate that the bulk crystal of the nanoparticle
is unchanged by all three treatments.Comment: 9 pages, 5 figures, journal articl
Arecibo pulsar survey using ALFA. III. precursor survey and population synthesis
The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam receiver to search both inner and outer Galactic sectors visible from Arecibo (32° ≲ ℓ ≲ 77°and 168°≲ ℓ ≲ 214°) close to the Galactic plane (|b| ≲ 5°) for pulsars. The PALFA survey is sensitive to sources fainter and more distant than have previously been seen because of Arecibo\u27s unrivaled sensitivity. In this paper we detail a precursor survey of this region with PALFA, which observed a subset of the full region (slightly more restrictive in ℓ and |b| ≲ 1°) and detected 45 pulsars. Detections included 1 known millisecond pulsar and 11 previously unknown, long-period pulsars. In the surveyed part of the sky that overlaps with the Parkes Multibeam Pulsar Survey (36°≲ ℓ ≲ 50°), PALFA is probing deeper than the Parkes survey, with four discoveries in this region. For both Galactic millisecond and normal pulsar populations, we compare the survey\u27s detections with simulations to model these populations and, in particular, to estimate the number of observable pulsars in the Galaxy. We place 95% confidence intervals of 82,000 to 143,000 on the number of detectable normal pulsars and 9000 to 100,000 on the number of detectable millisecond pulsars in the Galactic disk. These are consistent with previous estimates. Given the most likely population size in each case (107,000 and 15,000 for normal and millisecond pulsars, respectively), we extend survey detection simulations to predict that, when complete, the full PALFA survey should have detected 1000+330-230normal pulsars and 30 +200-20millisecond pulsars. Identical estimation techniques predict 490+160-115 that normal pulsars and 12+70-5 millisecond pulsars would be detected by the beginning of 2014; at the time, the PALFA survey had detected 283 normal pulsars and 31 millisecond pulsars, respectively. We attribute the deficiency in normal pulsar detections predominantly to the radio frequency interference environment at Arecibo and perhaps also scintillation - both effects that are currently not accounted for in population simulation models. © 2014. The American Astronomical Society. All rights reserved
Missing anterior teeth: orthodontic closure and transplantation as viable options to conventional replacements
Lückenschluß in der Front — eine ästhetische, parodontologische und okklusologische Überprüfung behandelter Fälle
Arecibo Pulsar Survey Using ALFA. III. Precursor Survey and Population Synthesis
The Pulsar Arecibo L-band Feed Array (PALFA) Survey uses the ALFA 7-beam
receiver to search both inner and outer Galactic sectors visible from Arecibo
( and ) close to the Galactic plane ()
for pulsars. In this paper we detail a precursor survey of this region with
PALFA, which observed a subset of the full region (slightly more restrictive in
and ) and detected 45 pulsars. For both Galactic
millisecond and normal pulsar populations, we compare the survey's detections
with simulations to model these populations and, in particular, to estimate the
number of observable pulsars in the Galaxy. We place 95\% confidence intervals
of 82,000 to 143,000 on the number of detectable normal pulsars and 9,000 to
100,000 on the number of detectable millisecond pulsars in the Galactic disk.
These are consistent with previous estimates. Given the most likely population
size in each case (107,000 and 15,000 for normal and millisecond pulsars,
respectively) we extend survey detection simulations to predict that, when
complete, the full PALFA survey should have detected normal pulsars and millisecond pulsars.
Identical estimation techniques predict that
normal pulsars and millisecond pulsars would be
detected by the beginning of 2014; at the time, the PALFA survey had detected
283 normal pulsars and 31 millisecond pulsars, respectively.Comment: 10 pages, 5 figure