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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Status of the DOE/NASA critical gas turbine R & T Project

The purpose of the DOE/NASA CRT (Critical Research and Technology) Project at the Lewis Research Center is to provide an R&T data base for utility gas turbine systems burning coal-derived fuels. Coal-derived fuels present difficult problems in combustion (because of the high organically-bound nitrogen in the fuel), and materials (because of the trace metal contaminant levels in the fuels, leading to corrosion and deposition in the turbine hot section). The combustion task includes (1) an effort to model the rich-lean combustion process, to predict NOx emissions; (2) a two-stage flame tube experiment to study the effects of combustion operating conditions and fuel properties on NOx conversion; and (3) scaled combustor tests to evaluate the NOx-reduction potential of several staged-combustion concepts. The materials-corrosion resistance effort attacks the problem on three sides.

Clark, J. S.↗
NASA NTRS1980

An observational H-R diagram for early-type stars

An observational H-R diagram for the O and B stars is discussed and compared with the predicted positions of massive model stars for the case of no mass loss and the case of mass loss. It is shown that the flux effective temperatures of O and B supergiants and of early O stars are less than the effective temperatures which might be inferred from the relative intensities of lines from two stages of ionization of an element.

Underhill, A. B.↗
NASA NTRS1981

IUE high-dispersion spectrum of R Aquarii

Emission-line spectra of several ions were observed in R Aqr in the wavelength range 1900-3000 A. C II diagnostics gives an electron density of about 400,000/cu cm and an electron temperature of about 10,000 K. The Mg II doublet profiles are grossly asymmetric, of a P Cygni type with terminal ejection velocity of at least 200 km/s. This is like Mg II behavior in Omicron Cet, Zeta Aur, and 32 Cyg, but unlike smaller UV shifts of the Mg II self-absorptions reported so far in other red giants and supergiants.

Johnson, H. M.↗
NASA NTRS1980

The NASA communications R & D program

About two years ago, NASA decided to reactivate its communications R&D Program, which had been phased down in 1973. The new program focuses on three major areas: (1) technology development in the 30 and 20 GHz bands for wideband communications; (2) system definition for an integrated terrestrial and satellite-aided system for land mobile communications in the 860 MHz band; and (3) development of system concepts and pilot networks for applications data services. The paper summarizes the new activities in the three areas and describes their status and plans.

Durrani, S. H.↗
NASA NTRS1982

International Ultraviolet Explorer observations of the R Aquarii jet

Ultraviolet spectra were obtained with the International Ultraviolet Explorer of the newly discovered optical-radio jet feature in the symbiotic variable R Aquarii. The far-UV continuum of the jet is characterized by strong continuum which rises with decreasing wavelength in the 1200-2000 A wavelength range and is considerably different in appearance from the relatively flat continuum exhibited by ionized nebulosity in the central star. Prominent Si III semi-forbidden lines and Si II emission lines seen in the central region are virtually absent in the jet. This could reflect the depletion of silicon in the feature, the result of grain formation in material that has been ejected by the central star. Consistent with this interpretation is the overall excitation of the jet that suggests it is cooler than the nebulosity that engulfs the central UV object.

Michalitsianos, A. G.↗
NASA NTRS1984

Development of improved low-strain creep strength in Cabot alloy R-41 sheet

The feasibility of improving the low-strain creep properties of a thin gauge nickel base sheet alloy through modified heat treatment or through development of a preferred crystal-lographic texture was investigated. The basic approach taken to improve the creep strength of the material by heat treatment was to increase grain size by raising the solution treatment temperature for the alloy to the range of 1420 K to 1475 K (2100 F to 2200 F). The key technical issue involved was maintenance of adequate tensile ductility following the solutioning of M6C primary carbides during the higher temperature solution treatment. The approach to improve creep properties by developing a sheet texture involved varying both annealing temperatures and the amount of prior cold work. Results identified a heat treatment for alloy R-14 sheet which yields a substantial creep-life advantage at temperatures above 1090 K (1500 F) when compared with material given the standard heat treatment. At the same time, this treatment provides reasonable tensile ductility over the entire temperature range of interest. The mechanical properties of the material given the new heat treatment are compared with those for material given the standard heat treatment. Attempts to improve creep strength by developing a sheet texture were unsuccessful.

Rothman, M. F.↗
NASA NTRS1983

The NASA SETI Program - Objectives of the R&D activity

The current activity in NASA's SETI Program is a research and development program jointly carried out by the NASA Ames Research Center and the Jet Propulsion Laboratory. The purpose of this R&D phase is to develop all prerequisites for a well defined microwave observing program. The specific objectives include the development of a prototype search system which will ultimately be capable of processing data rates up to 10 gigabytes/second. Specialized signal detection algorithms and automated search procedures will be developed and tested with the prototype hardware. A series of field tests will be carried out with the NASA Deep Space Network facilities at Goldstone, CA and with the 305-m radio telescope at the Arecibo Ionospheric Observatory in Puerto Rico.

Klein, M. J.↗
NASA NTRS1984

First-flight escape from spheres with R(-2) density distribution

Energy-independent first-flight transport kernels are evaluated for a spherical region with an R(-2) density distribution. The uncollided angular-flux distribution is obtained and integrated for a source distribution that is proportional to the density to give the uncollided emitted particle flux and current density. These are useful for the calculation of mass, energy, and momentum carried away by fast particles born in the medium. The data are relevant to estimate escape from weakly bound atmospheres such as comet comae, dilute circumstellar envelopes, and some unconfined laboratory plasmas.

Huebner, W. F.↗
NASA NTRS1984

Space commercialization: Analysis of R and D investments with long time horizons

By following a single hypothetical example through a series of variations, the way different potential investors might look at the opportunity to participate in space commercialization is described. The example itself is fairly typical of commercial opportunities in space. The chief characteristics are a steadily increasing requirement for capital infusion over an 8 year period, followed by a very generous stream of profits running another decade or more beyond. There is a decision point at 3 years, at the conclusion of laboratory R&D; and another at 6 years, following 2 initial space flights.

Sheahen, T. P.↗
NASA NTRS1983

NSSDC and WDC-A-R and S document availability and distribution services

Documents available from the national space science data center (NSSDC) and the world data center A for rockets and satellites (WDC-A-R&S), are described. The availability, costs, ordering procedures for documents presently available, and the procedures for obtaining future documents are given.

Source record↗
NASA NTRS1985

Variable, optically thick plasma in the interacting binaries R Arae and HD 207739

Attention is given to observational evidence for the presence of variable and optically thick extrastellar gas in two binary stars, R Arae and HD 207739, which appear to be in the evolutionary phase immediately preceding or following the short lived supercritical mass transfer phase. In both binaries, spectral lines and energy distributions are variable outside eclipse.

Kondo, Y.↗
NASA NTRS1985

R and D productivity improvement at Honeywell: A case study

The problems encountered when computer-aided-design/documentation was applied to a large design program at Honeywell; how a study team was established to solve the problem; the techniques used by the team and the resulting solutions are described. The techniques used in this instance may be applied to other problem areas in the R&D process to improve productivity.

Lyons, W. E.↗
NASA NTRS1985

Effect of R(3+) ions on the structure and properties of lanthanum borate glasses

The present investigation of glass formation in the (mole percent) systems 25La2O3 (x)R2O3 (75-x)B2O3, where R = Al, Ga, and (25-x)La2O3 (x)Ln2O3 75B2O3, where Ln = Gd, Er, Y, notes that up to 25 mol pct Al2O3 or Ga2O3 can be substituted for B2O3, while no more than about 5 mol pct Ln2O3, substituted for La2O3, caused macro-phase separation. The substitution of either R2O3 or Ln2O3 in the lanthanum borate system changes the separation distance between adjacent B3O6 chains. The effect of this structural change on the molar volume, transformation temperature, thermal expansion coefficient, and transformation-range viscosity is discussed.

Chakraborty, I. N.↗
NASA NTRS1986

The R Aquarii-jet at UV and radio wavelengths

The jet and central star of the peculiar symbiotic variable R Aquarii was monitored with IUE low resolution SWP 1200 to 2000 A spectra, in order to detect possible temporal variations. The absolute line intensities of N V, C IV and He II, as well as numerous other ionic species in the jet are found to vary on a timescale of 1.5 yr. High spatial resolution radio VLA maps and SiO maser millimeter interferometer observations of the star are quoted.

Michalitsianos, A. G.↗
NASA NTRS1986

Sub-arc second 2 centimeter continuum and SiO spectral line observations of R Aquarii

VLA observations with a limiting spatial resolution of about 0.15 arcsec were attempted along with complementary observations of SiO emission using the three-element Hat Creek interferometer to determine an accurate position of the long-period variable (LPV) of the R Aquarii binary system. The observations indicate that the LPV wind is distorted by the photoionization of the hot campanion's accretion disk, that precession of the accretion disk may occur, and that the observed v = 1, J = 2-1 transition emanates from a circumbinary layer far removed from the position of the LPV itself.

Hollis, J. M.↗
NASA NTRS1986

IRAS observations of R Coronae Borealis - Detection and study of a fossil shell

IRAS observations of the extreme hydrogen-deficient supergiant R CrB are presented and discussed. The star is surrounded by an enormous cool dust cloud which is tentatively identified as a fossil remnant of the hydrogen-rich envelope of the star. The angular extent of the emission corresponds to a linear extent of 8 pc, 20 times larger than the largest previously known shell around a late-type star. The radiating material is distributed very symmetrically over a wide range of radial distances from the star. The dust temperature is nearly constant throughout the extended shell. The total mass in the shell is about 0.3 solar mass. The ejection process appears to have occurred in a spherically symmetric fashion with a nearly constant mass loss rate and expansion velocity over a period of about 150,000 yr, terminating about 26,000 yr ago.

Gillett, F. C.↗
NASA NTRS1987

The fading of R Coronae Borealis

Using the International Ultraviolet Explorer (IUE) low-resolution spectra were obtained of R CrB, the prototype of its class of variable stars, shortly after the beginning of its 1983-84 minimum and during its rise to maximum again. The behavior of the spectra during the rise to maximum is similar to the behavior of the spectra of RY Sgr during a similar phase in 1979-80. The extinction data have been analyzed using Mie theory and are consistent with the stellar photosphere being obscured by 20-nm glassy carbon particles. The observations during the decline to minimum show substantial spectral variations which cannot be explained in terms of simple continuum absorption. An interpretation of the observed behavior in terms of a model incorporating an occulting cloud and circumstellar emission is offered.

Holm, A. V.↗
NASA NTRS1988

Cold-Worked Inconel(R) 718 Bars

Cold working and double aging yield high strength without sacrifice of resistance to corrosion. Report presents data on mechanical properties and stress-corrosion resistance of triple-melted, solution-treated, work-strengthened, direct-double-aged Inconel(R) 718 alloy. Triple melting consists of vacuum induction melting, electro-slag remelting, and vacuum arm remelting. Data indicate advance in processing of large-diameter bars. New process increases yield strength without reducing the elongation, reduction of area, and grain size.

Montano, J. W.↗