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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 73 records · Page 4

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NASA NTRS1976

Structure of Mars' atmosphere up to 100 kilometers from the entry measurements of Viking 2

Viking 2 entry data on the structure of Mars' atmosphere up to 100 kilometers define a morning atmosphere with an isothermal region near the surface; a surface pressure 10% greater than that recorded simultaneously at the Viking 1 site; and a thermal structure to 100 kilometers at least qualitatively consistent with pre-Viking modeling of thermal tides. The temperature profile exhibits waves whose amplitude grows with altitude, to about 25 K at 90 kilometers. The atmosphere is stable against convection, except possibly in some very local regions. Temperature is everywhere appreciably above the carbon dioxide condensation boundary at both landing sites, precluding the occurrence of carbon dioxide hazes in northern summer at latitudes to at least 50 deg N. Thus, ground-level mists seen in these latitudes would appear to be condensed water vapor.

Seiff, A.↗

NASA NTRS1977

The total hemispherical emittance of silicon-carbide coated reinforced carbon composites in the temperature range 100 K to 450 K

This paper deals with the measurement of the total hemispherical emittance of a silicon carbide coated carbon composite which is the thermal control material of the nose cone and leading edges of the Space Shuttle. In order to effect the thermal design of the spacecraft, it is desirable to have emittance data available for the temperature range 100 K to 2000 K to encompass the thermal extremes associated with orbiting and reentry conditions. Since the multiple thermal cycling associated with fifty to one hundred missions might result in substantial property changes, the data to be presented are for the low temperature regime 100 K to 450 K for both virgin material and material which was thermally treated to simulate multiple reentries. The discussion emphasizes the identification of possible sources of error in the measurement of equilibrium temperatures and the extent to which these measurement errors or uncertainties would alter the derived emittance values.

Mcgrath, J. J.↗

NASA NTRS1977

Experimental data and theoretical analysis of an operating 100 kW wind turbine

Part of the cooperative effort between NASA and ERDA has been the design and the erection of an experimental wind turbine by the NASA-Lewis Research Center. This 100 kW turbine, designated the Mod-O, is located at the NASA Plum Brook site near Sandusky, Ohio. Experimental test data have been correlated with analyses of turbine loads and complete system behavior of the 100 kW Mod-O wind turbine generator over a broad range of steady state conditions, as well as during transient conditions. The deficit in the ambient wind field due to the upwind tower turbine support structure was found to be very significant in exciting higher harmonic loads associated with the flapping response of the blade in bending.

Linscott, B. S.↗

NASA NTRS1977

Instrument to average 100 data sets

An instrumentation system is currently under development which will measure many of the important parameters associated with the operation of an internal combustion engine. Some of these parameters include mass-fraction burn rate, ignition energy, and the indicated mean effective pressure. One of the characteristics of an internal combustion engine is the cycle-to-cycle variation of these parameters. A curve-averaging instrument has been produced which will generate the average curve, over 100 cycles, of any engine parameter. the average curve is described by 2048 discrete points which are displayed on an oscilloscope screen to facilitate recording and is available in real time. Input can be any parameter which is expressed as a + or - 10-volt signal. Operation of the curve-averaging instrument is defined between 100 and 6000 rpm. Provisions have also been made for averaging as many as four parameters simultaneously, with a subsequent decrease in resolution. This provides the means to correlate and perhaps interrelate the phenomena occurring in an internal combustion engine. This instrument has been used successfully on a 1975 Chevrolet V8 engine, and on a Continental 6-cylinder aircraft engine. While this instrument was designed for use on an internal combustion engine, with some modification it can be used to average any cyclically varying waveform.

Tuma, G. B.↗

NASA NTRS1977

The 100 MSPS symbol synchronizer

The functional characteristics and design of the 100 Mega Symbol per Second (MSPS) symbol synchronizer are described, and test data obtained from the brassboard are presented. It was shown that symbol rates to 100 MSPS can be properly synchronized and detected at signal to noise ratios down to -2 db with detection degradation less than 1.5 db.

Source record↗

NASA NTRS1978

Strainrange partitioning behavior of the nickel-base superalloys, Rene' 80 and in 100

A study was made to assess the ability of the method of Strainrange Partitioning (SRP) to both correlate and predict high-temperature, low cycle fatigue lives of nickel base superalloys for gas turbine applications. The partitioned strainrange versus life relationships for uncoated Rene' 80 and cast IN 100 were also determined from the ductility normalized-Strainrange Partitioning equations. These were used to predict the cyclic lives of the baseline tests. The life predictability of the method was verified for cast IN 100 by applying the baseline results to the cyclic life prediction of a series of complex strain cycling tests with multiple hold periods at constant strain. It was concluded that the method of SRP can correlate and predict the cyclic lives of laboratory specimens of the nickel base superalloys evaluated in this program.

Halford, G. R.↗

NASA NTRS1978

Strainrange partitioning behavior of the nickel-base superalloys, Rene 80 and 100

A study has been made to assess the ability of the method of Strainrange Partitioning (SRP) to both correlate and predict high-temperature low-cycle fatigue lives of nickel-base superalloys for gas turbine applications. SRP is shown to correlate the cyclic lives of the baseline tests to within factors of nearly two. The partitioned strainrage versus life relationships for uncoated Rene 80 and cast IN 100 have also been determined from the ductility normalized-strainrange partitioning equations. These were used to predict the cyclic lives of the baseline tests. Predicted and observed cyclic lives agreed to within factors of nearly three. The life predictability of the method is also verified for cast IN 100 by applying the baseline results to the cyclic-life prediction of a series of complex strain-cycling tests with multiple hold periods at constant strain. It is concluded that the method of SRP can correlate and predict the cyclic lives of laboratory specimens of the nickel-base superalloys evaluated in this program.

Halford, G. R.↗

NASA NTRS1979

Utilization of 100 mb midlatitude height fields as an indicator of sampling effects on total ozone variations

Midlatitude 100-mb height fields are employed to determine the effects of ground based sampling locations on measurements of variations in the total ozone content of the atmosphere. The precision of the zonal average heights computed by the technique of Angell and Korshover (1978) from data over ozone sampling areas at 50 deg N is compared to the zonal average computed from the entire data set. Linear regressions of ozone contents determined by an analysis of backscatter UV satellite data with respect to 100 mb heights are utilized to transform zonal differences in height to ozone levels. The zonal average total ozone sampling error is found to be on the order of 2% for midlatitudes of the Northern hemisphere, indicating that the general shape of ozone trends determined by ground-based observations appears to be real and the increase of ozone from the mid-1960's to the early 1970's may be greater than previously suggested.

Miller, A. J.↗

NASA NTRS1980

Energy spectra of cosmic-ray nuclei to above 100 GeV per nucleon

Energy spectra of cosmic-ray nuclei boron to iron have been measured from 2 GeV per nucleon to beyond 100 GeV per nucleon. The data were obtained using an ionization calorimeter flown on a balloon from Palestine, Texas. The 3450 kg payload floated at 7 g/sq cm for almost 24 hours. The results are in excellent agreement with those of other workers where overlaps exist. The spectra are not consistent with single power laws, and demonstrate the power of using a single technique sensitive over a large dynamic range. The data are consistent with the leaky box model of cosmic-ray propagation. The boron data indicate that the cosmic-ray escape length decreases with increasing energy as E to the -(0.4 + or - 0.1) up to 100 GeV per nucleon. Secondary nuclei from iron are also consistent with this dependence. Predicted changes in the energy dependence of the ratios of primary nuclei O/C and (Fe + Ni)/(C + O) are also observed.

Simon, M.↗

NASA NTRS1981

Observations of supernova 1979c in M 100

The IUE observations of supernova 1979c in M 100 are presented and discussed. The main results are: (1) the bulk of the energy is in the form of continuous emission which is radiated by the main SN envelope; (2) the absorption features originate mostly in both the disks and the haloes of our Galaxy and M 100; and (3) the emission lines are produced in a highly ionized shell which has a radius greater than twice the radius of the main envelope and consists of compressed circumstellar material in which the abundance ratio N/C is about 30 times higher than solar.

Panagia, N.↗

NASA NTRS1981

Lightning amplitude spectra in the interval from 100 kHz to 20 MHz

The electric radiation fields produced by lightning return strokes, stepped leaders, and intracloud discharge processes have been Fourier-analyzed to determine amplitude spectra for these processes from about 100 kHz to 20 MHz. The fields were recorded under conditions where the lightning locations were known and where the field propagation from the lightning sources to the recording site was entirely over salt water. The spectra for return strokes show an f exp -1 frequency dependence from 100 kHz to 2 MHz, an f exp -2 dependence between 2 and 10 MHz, and an f exp -5 decrease above 10 MHz. In the 1 to 20 MHz range, the spectra of the initial fast transition in return strokes, the initial fast-rising portion of leader steps and the fast transitions in positive intracloud pulses are surprisingly similar.

Weidman, C. D.↗

NASA NTRS1984

Optimal design of GaAs-based concentrator space solar cells for 100 AMO, 80 deg C operation

Using a detailed computer code and reasonable values of electrical and optical material parameters from current published literature, parameter optimization studies were performed on three configurations of GaAs-based concentrator solar cells for 100 AMO, 80 C operation. These studies show the possibility of designing GaAs-based solar cells with efficiencies exceeding 22% at 100 AMO 80 C and probable efficiency degradation of less than 15% after a 70% reduction in diffusion length in each cell region.

Goradia, C.↗

NASA NTRS1984

The dissociation of H2 on the Ni(100) surface

The dissociation of H2 on the (100) surface of Ni is investigated using a cluster model. The mechanism for dissocation of H2 directly above a Ni atom has little to no barrier and involves the Ni 3d electrons; elimination of the Ni 3d interaction with the H2 increases the barrier to more than 50 kcal/mol. The dissociation at the bridge site, treated without the Ni 3d interaction, leads to a barrier of about 30 kcal/mol, leading to the conclusion that the dissociation of H2 at any site on a Ni(100) surface requires strong 3d participation. The results are quantitatively different if the Ni 4p orbitals are not included. The effects of cluster size on the results are also discussed.

Siegbahn, P. E. M.↗

NASA NTRS1984

Tunable Heterodyne Receiver from 100 Micron to 1,000 Micron for Airborne Observations

Interest in high resolution spectrometers for the submillimeter wavelength range from 100 micron to 1,000 micron is mostly stimulated by molecular spectroscopy in radioastronomy and atmospheric physics, and by plasma diagnostic experiments. Schottky diodes in waveguide mixer technology and InSb-hot electron bolometers are successfully used in the 0.5 to a few millimeter range whereas tandem Fabry-Perot spectrometers combined with photoconductive detectors (Ge:Sb and Ge:Ga) are used for the 100 micron range. Recent research on heterodyne spectrometers, with Schottky diodes in an open structure mixer and a molecular laser as local oscillators, which can be used over the whole wavelength range is summarized.

Roeser, H. P.↗

NASA NTRS1985

Texture etching of (100) silicon for solar cells

A chemical means of creating the proper kind of light collection texture on (100) silicon slices is discussed. Texturing of (100) silicon surfaces in sodium or potassium hydroxides occurs by the growth of a reaction product in a random array of surface sites, which leads to pyramids remaining at the sites after other parts of the surface dissolve away. A new texture-promoting influence, a proximity effect, was discovered in this work. An attempt was made to quantify the various promotional effects. The purpose of the present paper is to: (1) explain in detail the attempt at understanding and quantifying texturing; (2) give an experimental description with observations on the proximity effect and the effect of additions of water glass that were discovered during this work; and (3) show that the precipitate or growth models account for almost all of the known promotional effects.

Dyer, L. D.↗

NASA NTRS1985

AES and LEED study of the zinc blende SiC(100) surface

Auger and LEED measurements have been carried out on the (100) surface of zinc blende SiC. Two different phases of the clean surface, in addition to two kinds of oxygen-covered surfaces, have been obtained, identified, and discussed. In the oxygen-covered surface, the oxygen is bonded to the Si. The carbon-rich phase is reconstructed (2 x 1), similar to the (100) clean surfaces of Si, Ge, and diamond. The Si-topped surface is reconstructed. A model of alternating Si dimers is suggested for this surface.

Dayan, M.↗

NASA NTRS1986

Short-lived solar burst spectral component at f approximately 100 GHz

A new kind of burst emission component was discovered, exhibiting fast and distinct pulses (approx. 60 ms durations), with spectral peak emission at f approx. 100 GHz, and onset time coincident to hard X-rays to within approx. 128 ms. These features pose serious constraints for the interpretation using current models. One suggestion assumes the f approx. 100 GHz pulses emission by synchrotron mechanism of electrons accelerated to ultrarelativistic energies. The hard X-rays originate from inverse Compton scattering of the electrons on the synchrotron photons. Several crucial observational tests are needed for the understanding of the phenomenon, requiring high sensitivity and high time resolution (approx. 1 ms) simultaneous to high spatial resolution (0.1 arcsec) at f approx. 110 GHz and hard X-rays.

Kaufmann, P.↗

NASA NTRS1985

Evolution of systems concepts for a 100 kWe class Space Nuclear Power System

Conceptual designs for the SP-100 Space Nuclear Power System have been prepared that meet baseline, backup and growth program scenarios. Near-term advancement in technology was considered in the design of the Baseline Concept. An improved silicon-germanium thermoelectric technique is used to convert the heat from a fast-spectrum, liquid lithium cooled reactor. This system produces a net power of 100 kWe with a 10-year end of life, under the specific constraints of area and volume. Output of the Backup Concept is estimated to be 60 kWe for a 10-year end of life. This system differs from the Baseline Concept because currently available thermoelectric conversion is used from energy supplied by a liquid sodium cooled reactor. The Growth Concept uses Stirling engine conversion to produce 100 kWe within the constraints of mass and volume. The Growth Concept can be scaled up to produce a 1 MWe output that uses the same type reactor developed for the Baseline Concept. Assessments made for each of the program scenarios indicate the key development efforts needed to initiate detailed design and hardware program phases. Development plans were prepared for each scenario that detail the work elements and show the program activities leading to a state of flight readiness.

Katucki, R.↗