119,021 research outputs found
Deep reconditioning of batteries during DSCS 3 flight operations
Deep reconditioning of batteries is defined as discharge below the 1.0 volt/cell level to a value of about 1.0 volt/battery. This type of reconditioning was investigated for use on the Defense Satellite Communications System (DSCS) spacecraft, and has been used during the first year of orbital operation. Prior to launch of the spacecraft, the deep reconditioning was used during the battery life test, which has now complete fourteen eclipse periods. Reconditioning was performed prior to each eclipse period of the life test, and is scheduled to be used prior to each eclipse period in orbit. The battery data for discharge and recharge is presented for one of the life test reconditioning cycles, and for each of the three batteries during the reconditioning cycles between eclipse period no.1 and eclipse period no.2 in Earth orbit
Use of thermal inertia determined by HCMM to predict nocturnal cold prone areas in Florida
The HCMM transparency scenes for the available winter of 1978-1979 were evaluated; scenes were identified on processed magnetic tapes; other remote sensing information was identified; and a soil heat flux model with variable-depth thermal profile was developed. The Image 100 system was used to compare HCMM and GOES transparent images of surface thermal patterns. Excellent correspondence of patterns was found, with HCMM giving the greater resolution. One image shows details of thermal patterns in Florida that are attributable to difference in near surface water contents. The wide range of surface temperatures attributable to surface thermal inertia that exist in the relatively flat Florida topography is demonstrated
Use of thermal inertia determined by HCMM to predict nocturnal cold prone areas in Florida
Transparencies, prints, and computer compatible tapes of temperature differential and thermal inertia for the winter of 1978 to 1979 were obtained. Thermal inertial differences in the South Florida depicted include: drained organic soils of the Everglades agricultural area, undrained organic soils of the managed water conservation areas of the South Florida water management district, the urbanized area around Miami, Lake Okeechobee, and the mineral soil west of the Everglades agricultural area. The range of wetlands and uplands conditions within the Suwanee River basin was also identified. It is shown that the combination of wetlands uplands surface features of Florida yield a wide range of surface temperatures related to wetness of the surface features
Use of thermal inertia determined by HCMM to predict nocturnal cold prone areas in Florida
Surface temperatures derived from HCMM data were compared with to those obtained by GOES satellite and the apparent thermal inertia (ATI) calculated. For two dates, the HCMM temperatures appear to be about 5 C lower than the GOES temperatures. The ATI for excessively-drained to well-drained mineral soils was greater than for drained organic soils possibly because of long periods of low rainfall during late 1980 and early 1981. Organic soils cropped to sugar cane showed lower ATI after a severe killing freeze. With dead leaves, there was less transpiration and more solar radiation probably reached the dark soil surface. This would explain the larger diurnal temperature amplitude observed
Development and demonstration of manufacturing processes for fabricating graphite/LARC 160 polyimide structural elements
The development and demonstration of manufacturing technologies for the structural application of Celion graphite/LARC-160 polyimide composite material is discussed. Process development and fabrication of demonstration components are discussed. Process development included establishing quality assurance of the basic composite material and processing, nondestructive inspection of fabricated components, developing processes for specific structural forms, and qualification of processes through mechanical testing. Demonstration components were fabricated. The demonstration components consisted of flat laminates, skin/stringer panels, honeycomb panels, chopped fiber compression moldings, and a technology demonstrator segment (TDS) representative of the space shuttle aft body flap
Single microwave photon detection in the micromaser
High efficiency single photon detection is an interesting problem for many
areas of physics, including low temperature measurement, quantum information
science and particle physics. For optical photons, there are many examples of
devices capable of detecting single photons with high efficiency. However
reliable single photon detection of microwaves is very difficult, principally
due to their low energy. In this paper we present the theory of a cascade
amplifier operating in the microwave regime that has an optimal quantum
efficiency of 93%. The device uses a microwave photon to trigger the stimulated
emission of a sequence of atoms where the energy transition is readily
detectable. A detailed description of the detector's operation and some
discussion of the potential limitations of the detector are presented.Comment: 8 pages, 5 figure
The brightest pure-H ultracool white dwarf
We report the identification of LSR J0745+2627 in the United Kingdom InfraRed
Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool
white dwarf with kinematics and age compatible with the thick-disk/halo
population. LSR J0745+2627 has a high proper motion (890 mas/yr) and a high
reduced proper motion value in the J band (H_J=21.87). We show how the
infrared-reduced proper motion diagram is useful for selecting a sample of cool
white dwarfs with low contamination. LSR J0745+2627 is also detected in the
Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer
(WISE). We have spectroscopically confirmed this object as a cool white dwarf
using X-Shooter on the Very Large Telescope. A detailed analysis of its
spectral energy distribution reveals that its atmosphere is compatible with a
pure-H composition model with an effective temperature of 3880+-90 K. This
object is the brightest pure-H ultracool white dwarf (Teff<4000 K) ever
identified. We have constrained the distance (24-45 pc), space velocities and
age considering different surface gravities. The results obtained suggest that
LSR J0745+2627 belongs to the thick-disk/halo population and is also one of the
closest ultracool white dwarfs.Comment: 5 pages, 7 figures, accepted for publication in A&A Letter
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