GaAs-Si photon-activated switch.
Light activated low level switch consisting of electroluminescent GaAs p-n diode and double emitter silicon transistor
SWITCHING ELEMENT↗
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Results for “ACTIVITY LEVELS”
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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Quenching of N sub 2
Rate coefficient for primary process in removing molecular nitrogen in high vibrational levels from active nitrogen by N atoms
Mannella, G. G.↗
Development of uniform and predictable battery materials for nickel-cadmium aerospace cells
The objective of this study was to analyze battery materials and manufacturing methods with the aim of developing uniform and predictable battery plates for nickel cadmium aerospace cells. The results are presented of an extensive factorially-designed experiment aimed at illuminating, in a comparative study, the effect of plaque preparation, plaque thickness, impregnation process, and loading level with active material. The following impregnation processes were investigated: (1) chemical conversion, (2) electrochemical conversion, and (3) high temperature electrochemical impregnation. The test parameter on which the conclusion regarding the manufacturing variables are based was the capacity change during a simulated near-earth orbit cycle regime. As operational variables, the effect of various charge and discharge rates was investigated. During the 100 test cycles, overall capacity changes of positive plates and the differences between the various plates were found to be small. Plates prepared by the high temperature electrochemical impregnation of slurry-coated plaque (at the conditions used) showed surface buildup of active material. They also retained slightly less of their capacity during cycling compared to other plate preparations.
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Aviation Forecasting in ICAO
Opinions or plans of qualified experts in the field are used for forecasting future requirements for air navigational facilities and services of international civil aviation. ICAO periodically collects information from Stators and operates on anticipated future operations, consolidates this information, and forecasts the future level of activity at different airports.
Mcmahon, J.↗
Electric fields in the magnetosphere.
Two techniques, tracking the motions of Ba(+) clouds and measuring the differences in floating potential between symmetric double probes, have been highly successful in: (1) demonstrating the basic convective nature of magnetospheric electric fields, (2) mapping the global patterns of convection at upper ionosphere levels, and (3) revealing the physics of electric currents in the ionosphere and the importance of magnetosphere-ionosphere feedback in altering the imposed convection. The basic pattern of anti-solar convection across the polar cap and night toward day convection in both the evening and morning sectors at auroral belt latitudes persists at all levels of activity. The dawn-dusk potential drop across the polar cap (anti-solar convection) ranges from 20 to 100 kilovolts with the most typical values in the center of this range. The sum of morning and evening (night toward day convection) potential drops in the adjacent auroral belts roughly equals the polar cap drop in the opposite sense as expected.
Heppner, J. P.↗
Studies of solar magnetic fields. II - The magnetic fluxes
Magnetic flux data from the Mount Wilson magnetograph are examined over the interval 1967-1973. The total flux in the north is greater than that in the south by about 7% over this interval, reflecting a higher level of activity in the northern hemisphere. Close to 95% of the total flux is confined to latitudes equatorward of 40 degrees, which means that close to 95% of the flux cancels with flux of opposite polarity before it can migrate poleward of 40 degrees. It is pointed out that a consequence of this flux distribution is that ephemeral regions must make a negligible contribution to the long-term large-scale magnetic flux distribution. A broad peak in the total flux may be seen centered about one year after activity maximum in the north below 40 degrees. In the south there is a very sharp increase in flux about the same time. In the north, several poleward migrations of flux may be seen.
Howard, R.↗
Evolution of the X-ray emitting corona preceding and after major solar events
Soft X-ray emission from the sun during STIP Interval II, observed with the Lockheed Mapping X-ray Heliometer on the NASA OSO-8 satellite, is presented. In examining the emission versus time for extended intervals around the times of the Class 1B flare on March 28, 1976, and the Class 1B flare on April 30, 1976, we find significantly more low level flare activity prior to the major flares than after. Twelve modest X-ray bursts are investigated and no compelling case of a preflare brightening phase is observed. Preliminary correlations with the time history of emitted solar particles are discussed.
Wolfson, C. J.↗
Modeling of the geosynchronous plasma environment
An analytic simulation of the geosynchronous environment in terms of local time and the daily A sub P index is presented. The simulation is compared with actual statistical data from approximately 50 days of ATS 5 plasma data and 50 days of ATS 6 plasma data. At low levels of activity the model adequately simulates the local time variations of the plasma parameters. At high values of geomagnetic activity, the predicted magnitudes of the plasma parameters agree with the statistical results but the effects of multiple injections are evident in both the data and the simulation, biasing the local time variations.
Garrett, H. B.↗
LACIE area, yield, and production estimate characteristics: U.S.S.R.
No estimates were generated for the U.S.S.R. during LACIE phase 1. Phase 2 effort was limited to two indicator regions: winter wheat areas where 385 segments were allocated, and spring wheat areas with 362 allocated segments. The level of activity for phase 3 was extended to the entire country which automatically increased the segment workload from 747 to 1947 segments. Production, area, and yield estimates, and their accuracy are discussed for phases 2 and 3 with emphasis on scope, sampling strategy, data base, LANDSAT data, yield analysis for winter and spring wheat, area and production analysis for winter and spring wheat, and technical issues and problems.
Hickman, J. R.↗
NASA's Role in Aeronautics: A Workshop. Volume 5: Rotorcraft
The potential roles for NASA relating to rotorcraft are reviewed. The agency's participation is delineated for each role, a rationale is provided, the current level of activity is summarized, and suggestions are given for the kinds of research still needed. In examining opportunities for the most beneficial deployment of its resources, NASA should consider societal benefits as well as the military and civil markets in formulating the role it can play to support the development of a stronger rotorcraft technology base.
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Evidence for solar wind control of Saturn radio emission
Using data collected by the Voyager 1 and 2 spacecraft in 1980 and 1981, strong evidence is presented for a direct correlation between variations in the solar wind at Saturn and the level of activity of Saturn's nonthermal radio emission. Correlation coefficients of 57 to 58% are reached at lag times of 0 to 1 days between the arrival at Saturn of high pressure solar wind streams and the onset of increased radio emission. The radio emission exhibits a long-term periodicity of 25 days, identical to the periodicity seen in the solar wind at this time and consistent with the solar rotation period. The energy coupling efficiency between the solar wind with the Saturn radio emission is estimated and compared with that for Earth.
Desch, M. D.↗
Model fitting of the Algol binaries
Energy distribution of the component stars of the Algol type semidetached binaries were studied by combining IUE low dispersion spectra with optical scans made with the same resolution. In most cases the flux distributions are matched by Kuruz model atmospheres with normal solar composition. Deviations from normal atmospheres which indicate a higher level of activity and interaction in the binaries are examined. Eclipse observations in U Cep and V356 Sgr reveal emission lines of the W serpentis type.
Dobias, J. J.↗
Shallow moonquakes - How they compare with earthquakes
Of three types of moonquakes strong enough to be detectable at large distances - deep moonquakes, meteoroid impacts and shallow moonquakes - only shallow moonquakes are similar in nature to earthquakes. A comparison of various characteristics of moonquakes with those of earthquakes indeed shows a remarkable similarity between shallow moonquakes and intraplate earthquakes: (1) their occurrences are not controlled by tides; (2) they appear to occur in locations where there is evidence of structural weaknesses; (3) the relative abundances of small and large quakes (b-values) are similar, suggesting similar mechanisms; and (4) even the levels of activity may be close. The shallow moonquakes may be quite comparable in nature to intraplate earthquakes, and they may be of similar origin.
Nakamura, Y.↗
Remote comets and related bodies - VJHK colorimetry and surface materials
VJHK colors for a number of asteroids and eight comets at various solar distances and levels of activity were obtained, and the observations are interpreted in terms of a two-component mixing model in which outer solar system interplanetary bodies are viewed as mixtures of ice and dark carbonaceous-type (RD and C) dirt. It is inferred that the observed comets have comae, and perhaps surfaces, of dirty ice or ice dirt grains colored by an RD-dirt component. This inference is supported by systematics of an 'alpha index' based on VJHK colors and empirically correlated with albedo and ice/dirt ratio. Among comets the alpha index correlates with solar distance in a way that suggests comets emit dirty ice grains which are stable at large solar distance but from which the ice component sublimes and leaves dirt grains at small solar distance.
Hartmann, W. K.↗
Implementation of Large Antennas for Deep Space Mission Support
The large antennas of the DSN support reception of low power telemetry signals from spacecraft (S/C), transmission of high power commands to S/C, and navigation of S/C by precision radiometric data. The specification and design of antennas were driven by the requirement to support those functions with high reliability. The number of antennas required in the DSN is determined by the number of S/C to be supported and their level of activity. A given size antenna aperture can be realized with a single element or by arraying smaller elements with the same total area. That approach can be applied to meeting many DSN requirements. There is a cost vs capability trade-off in arrayed vs single element designs. The operating microwave frequency is an important parameter for the antenna. Major radio astronomy antennas can be arrayed with DSN antennas to increase reception capability. The specification, design, and development of DSN antennas are examined.
Stevens, R.↗
Average and worst-case specifications of precipitating auroral electron environment
The precipitation electrons in the auroral environment are highly variable in their energy and intensity in both space and time. As such they are a source of potential hazard to the operation of the Space Shuttle and other large spacecraft operating in polar orbit. In order to assess these hazards both the average and extreme states of the precipitating electrons must be determined. Work aimed at such a specification is presented. First results of a global study of the average characteristics are presented. In this study the high latitude region was divided into spatial elements in magnetic local time and corrected geomagnetic latitude. The average electron spectrum was then determined in each spatial element for seven different levels of activity as measured by K sub p using an extremely large data set of auroral observations. Second a case study of an extreme auroral electron environment is presented, in which the electrons are accelerated through field aligned potential as high as 30,000 volts and in which the spacecraft is seen to charge negatively to a potential approaching .5 kilovolts.
Hardy, D. A.↗
Ongoing star formation in NGC 3310 - An infrared perspective
Infrared observations of NGC 3310 demonstrate that the extremely blue UBV colors and intense radio, ultraviolet, and X-ray emission of this galaxy are attributable to an exceptionally luminous burst of star formation. The flux at 1-20 microns is separable into contributions from young and old stars, ionized gas, and warm dust. Simple models imply that the starburst is very young (around 10 to the 7th yr) and that it will proceed at its present level of activity for a time which is only a small fraction of the age of the galaxy.
Telesco, C. M.↗
Aerospace Safety Advisory Panel report to the NASA acting administrator
The level of activity of the Aerospace Safety Advisory Panel was increased smewhat during 1985 in concert with the increased mission rate of the National Space Transportation System, the evolutionary changes in management and operation of that program, and the preparation of the Vandenberg Launch Site; the implementation of the Program Definition Phase of the Space Station Program; and the actual flight testing of the X-29 research aircraft. Impending payload STS missions and NASA's overall aircraft operations are reviewed. The safety aspects of the LEASAT salvage mission were assessed. The findings and recommendation of the committee are summerized.
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