22,746 research outputs found
Design requirements for high-efficiency high concentration ratio space solar cells
A miniaturized Cassegrainian concentrator system concept was developed for low cost, multikilowatt space solar arrays. The system imposes some requirements on solar cells which are new and different from those imposed for conventional applications. The solar cells require a circular active area of approximately 4 mm in diameter. High reliability contacts are required on both front and back surfaces. The back area must be metallurgically bonded to a heat sink. The cell should be designed to achieve the highest practical efficiency at 100 AMO suns and at 80 C. The cell design must minimize losses due to nonuniform illumination intensity and nonnormal light incidence. The primary radiation concern is the omnidirectional proton environment
The Dog on the Ship: The "Canis Major Dwarf Galaxy" as an Outlying Part of the Argo Star System
Overdensities in the distribution of low latitude, 2MASS giant stars are
revealed by systematically peeling away from sky maps the bulk of the giant
stars conforming to ``isotropic'' density laws generally accounting for known
Milky Way components. This procedure, combined with a higher resolution
treatment of the sky density of both giants and dust allows us to probe to
lower Galactic latitudes than previous 2MASS giant star studies. While the
results show the swath of excess giants previously associated with the
Monoceros ring system in the second and third Galactic quadrants at distances
of 6-20 kpc, we also find a several times larger overdensity of giants in the
same distance range concentrated in the direction of the ancient constellation
Argo. Isodensity contours of the large structure suggest that it is highly
elongated and inclined by about 3 deg to the disk, although details of the
structure -- including the actual location of highest density, overall extent,
true shape -- and its origin, remain unknown because only a fraction of it lies
outside highly dust-obscured, low latitude regions. Nevertheless, our results
suggest that the 2MASS M giant overdensity previously claimed to represent the
core of a dwarf galaxy in Canis Major (l ~ 240 deg) is an artifact of a dust
extinction window opening to the overall density rise to the more significant
Argo structure centered at larger longitude (l ~ 290 +- 10 deg, b ~ -4 +- 2
deg).Comment: 4 pages, 4 figure
Radial honeycomb core
Core alleviates many limitations of conventional nacelle construction methods. Radical core, made of metals or nonmetals, is fabricated either by joining nodes and then expanding, or by performing each layer and then joining nodes. Core may also be produced from ribbons or strips with joined nodes or ribbons oriented in longitudinal planes
Band structures of rare gas solids within the GW approximation
Band structures for solid rare gases (Ne, Ar) have been calculated using the
GW approximation. All electron and pseudopotential ab initio calculations were
performed using Gaussian orbital basis sets and the dependence of particle-hole
gaps and electron affinities on basis set and treatment of core electrons is
investigated. All electron GW calculations have a smaller particle-hole gap
than pseudopotential GW calculations by up to 0.2 eV. Quasiparticle electron
and hole excitation energies, valence band widths and electron affinities are
generally in very good agreement with those derived from optical absorption and
photoemission measurements.Comment: 7 pages 1 figur
Development and evaluation of an impedance cardiographic system to measure cardiac output and other cardiac parameters Final progress report 1 Jul. 1969 - 31 Dec. 1970
Performance of impedance cardiograph for measuring heart rate and body fluid
Development and Evaluation of an Impedance Cardiographic System to Measure Cardiac Output and Other Cardiac Parameters, 1 July 1968 - 30 June 1969
Impedance cardiographic system to measure cardiac output and cardiovascular function
Search for Lorentz Invariance and CPT Violation with the MINOS Far Detector
We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be
a consequence of Lorentz and CPT violation as described by the standard-model extension framework. It
also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We
found no evidence for this sidereal signature, and the upper limits placed on the magnitudes of the Lorentz
and CPT violating coefficients describing the theory are an improvement by factors of 20–510 over the
current best limits found by using the MINOS near detector
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