11,470 research outputs found
Fixture tests bellows reliability through repetitive pressure/temperature cycling
Fixture explores the reliability of bellows used in precision in inertial systems. The fixture establishes the ability of the bellows to withstand repetitive over-stress pressure cycling at elevated temperatures. It is applicable in quality control and reliability programs
Reliability assessment of the GEOS A power supply
Reliability assessment of geodetic satellite A power suppl
Neutrino flux predictions for known Galactic microquasars
It has been proposed recently that Galactic microquasars may be prodigious
emitters of TeV neutrinos that can be detected by upcoming km^2 neutrino
telescopes. In this paper we consider a sample of identified microquasars and
microquasar candiates, for which available data enables rough determination of
the jet parameters. By employing the parameters inferred from radio
observations of various jet ejection events, we determine the neutrino fluxes
that should have been produced during these events by photopion production in
the jet. Despite the large uncertainties in our analysis, we demonstrate that
in several of the sources considered, the neutrino flux at Earth, produced in
events similar to those observed, would exceed the detection threshold of a
km^2 neutrino detector. The class of microquasars may contain also sources with
bulk Lorentz factors larger than those characteristic of the sample considered
here, directed along our line of sight. Such sources, which may be very
difficult to resolve at radio wavelengths and hence may be difficult to
identify as microqusar candidates, may emit neutrinos with fluxes significantly
larger than typically obtained in the present analysis. These sources may
eventually be identified through their neutrino and gamma-ray emission.Comment: 17 pages. Submitted to Ap
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Effects of natural soiling and weathering on cool roof energy savings for dormitory buildings in Chinese cities with hot summers
Roofs with high-reflectance (solar reflectance) coating, commonly known as cool roofs, can stay cool in the sun, thereby reducing building energy consumption and mitigating the urban heat island. However, chemical-physical degradation and biological growth can decrease their solar reflectance and the ability to save energy. In this study, the solar spectral reflectance of 12 different roofing products with an initial albedo of 0.56–0.90 was measured before exposure and once every three months over 32 months. Specimens were exposed on the roofs of dormitory buildings in Xiamen and Chengdu, each major urban areas with hot summers. The albedos of high and medium-lightness coatings stabilized in the ranges 0.45–0.62 and 0.36–0.59 in both cities, respectively. This study yielded albedo loss exceeded those reported in the latest Chinese standard by 0.08–0.15. Finally, DesignBuilder (EnergyPlus) simulations estimate that a new cool roof with albedo 0.78 on a six-story dormitory building will yield annual site energy savings (heating and cooling) for the top floor, which are 8.01 kWh/m2 (24.2%) and 9.12 kWh/m2 (26.3%) per unit floor area in Xiamen and Chengdu, respectively; while an aged cool roof with albedo 0.45 and 0.56 will yield the annual savings by 5.12 kWh/m2 (15.4%) and 2.47 kWh/m2 (10.5%) in these two cities
A Grammar of Yélî Dnye
This is a comprehensive description of a language spoken offshore from Papua New Guinea, remarkable for its phonological, morphological and syntactic complexity. As the sole surviving member of its language family, it provides unique evidence for the kind of languages spoken in this part of the world before the Austronesian expansion. The grammar provides detailed information on phoneme inventory, morphology, syntax and select semantic fields
The Strong Levinson Theorem for the Dirac Equation
We consider the Dirac equation in one space dimension in the presence of a
symmetric potential well. We connect the scattering phase shifts at E=+m and
E=-m to the number of states that have left the positive energy continuum or
joined the negative energy continuum respectively as the potential is turned on
from zero.Comment: Submitted to Physical Review Letter
Sensitivity of the NEMO telescope to neutrinos from microquasars
We present the results of Monte Carlo simulation studies of the capability of
the proposed NEMO telescope to detect TeV muon neutrinos from Galactic
microquasars. In particular we determined the number of the detectable events
from each known microquasar together with the expected atmospheric neutrino and
muon background events. We also discuss the detector sensitivity to neutrino
fluxes expected from microquasars, optimizing the event selection in order to
reject the atmospheric background, and we show the number of events surviving
the event selection.Comment: To be published on CRIS06 proceedings (Catania, Italy, May 29 - June
2, 2006
Thermal performance and energy savings of white and sedum-tray garden roof: A case study in a Chongqing office building
This study presents the experimental measurement of the energy consumption of three top-floor air-conditioned rooms in a typical office building in Chongqing, which is a mountainous city in the hot-summer and cold-winter zone of China, to examine the energy performance of white and sedum-tray garden roofs. The energy consumption of the three rooms was measured from September 2014 to September 2015 by monitoring the energy performance (temperature distributions of the roofs, evaporation, heat fluxes, and energy consumption) and indoor air temperature. The rooms had the same construction and appliances, except that one roof top was black, one was white, and one had a sedum-tray garden roof. This study references the International Performance Measurement and Verification Protocol (IPMVP) to calculate and compare the energy savings of the three kinds of roofs. The results indicate that the energy savings ratios of the rooms with the sedum-tray garden roof and with the white roof were 25.0% and 20.5%, respectively, as compared with the black-roofed room, in the summer; by contrast, the energy savings ratios were −9.9% and −2.7%, respectively, in the winter. Furthermore, Annual conditioning energy savings of white roof (3.9 kWh/m2) were 1.6 times the energy savings for the sedum-tray garden roof. It is evident that white roof is a preferable choice for office buildings in Chongqing. Additionally, The white roof had a reflectance of 0.58 after natural aging owing to the serious air pollution worsened its thermal performance, and the energy savings reduced by 0.033 kWh/m2·d. Evaporation was also identified to have a significant effect on the energy savings of the sedum-tray garden roof
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