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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Predicting Stellar Angular Sizes

Reliable prediction of stellar diameters, particularly angular diameters, is a useful and necessary tool for the increasing number of milliarcsecond resolution studies being carried out in the astronomical community.

interferometry angular sizes stars↗
NASA NTRS2001

Modulation of the seasonal cycle in length-of-day and atmospheric angular momentum

Global warming, by definition, changes the atmospheric temperature field. This temperature change is not expected to be uniform, either geographically, or with height in the atmosphere. By the thermal wind equation. changes in the pole-to-equator temperature gradient will cause changes in the atmospheric zonal winds. Numerous previous studies have shown that observed length-of-day (LOD) variations on time scales of a few days to a few years are largely caused by atmospheric zonal wind fluctuations. In particular, seasonal variations in LOD have been previously shown to be dominantly caused by seasonal variations in the atmospheric zonal winds. Here, observed changes in the strength of seasonal LOD and wind-driven atmospheric angular momentum signals during 1962 to 2000 are analyzed and shown to be significantly correlated with each other and with the Southern Oscillation Index.

length of day↗
NASA NTRS2019

Determination of the solar angular dependence of the NOAA-20 VIIRS solar diffuser BRDF change factor

When fully illuminated by the Sun, the solar diffuser (SD) onboard of the NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) instrument provides a radiance source to allow for radiometric calibration of the VIIRS’s reflective solar bands (RSBs). Once on-orbit, due to solar bombardment and the space environment, the SD’s bidirectional reflectance distribution function (BRDF) changes its value. The change is denoted by a factor, known as the H-factor, that is time and wavelength dependent, as well as both incident and out-going angle dependent. Here, we use regular on-orbit solar diffuser stability monitor (SDSM) data to determine the solar angular dependence for the H-factor along the SD-to-SDSM direction. We compare the dependence with that for the VIIRS on the Suomi National Polar-orbiting Partnership satellite and apply the dependence ratio to obtain the N20 VIIRS SD H-factor along the SD-telescope direction.

N20 VIIRS↗
NASA NTRS1965

Universal bellows joint restraint permits angular and offset movement

Universal joint-type restraint that employs ball joints permits maximum angular and lateral offset movement in a bellows joint without danger of rupture or pressure drop in the line. It is used in high pressure and high temperature applications in refineries, steam plants, or stationary power plants.

Kuhn, R. F., Jr.↗
NASA NTRS1966

Angular acceleration measured by deflection in sensing ring

Small, lightweight angular accelerometer performs reliably when subjected to harsh temperature and vibration environments. The device uses strain gages to measure the amount of deflection in a metal ring caused by movement of inertial masses mounted through the ring. Range of the instrument is varied by varying the value of inertial masses.

Richard, R. R.↗