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At least 343 records · Page 19

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NASA NTRS1980

Community reactions to aircraft noise in the vicinity of airport: A comparative study of the social surveys using interview method

A comparative study was performed on the reports of community reactions to aircraft noise. The direct and immediate reactions to aircraft noise such as perceived noisiness, interference with conversations, etc. and various emotional influences were most remarkable; indirect and long term influences such as disturbance of mental work and physical symptoms were less remarkable.

Osada, Y.↗

NASA NTRS1979

Comparative study of solar optics for paraboloidal concentrators

Different analytical methods for computing the flux distribution on the focal plane of a paraboloidal solar concentrator are reviewed. An analytical solution in algebraic form is also derived for an idealized model. The effects resulting from using different assumptions in the definition of optical parameters used in these methodologies are compared and discussed in detail. These parameters include solar irradiance distribution (limb darkening and circumsolar), reflector surface specular spreading, surface slope error, and concentrator pointing inaccuracy. The type of computational method selected for use depends on the maturity of the design and the data available at the time the analysis is made.

Wen, L.↗

NASA NTRS1979

Experimental shock metamorphism of mono- and polycrystalline olivine - A comparative study

The paper reports on a series of controlled shock recovery experiments which have been performed on over 40 samples including monocrystalline, polycrystalline, dunite, and porous particulate olivine-bearing targets. Results of the mineralogical and petrological analyses of these samples are used to establish a general and comparative diagnosis of shock effects generated in various olivine-bearing materials. Finally, some experiments are conducted under different ambient pO2 conditions so that information on the distribution of observed impact features is derived as a function not only of peak pressure and texture of the target sample, but also of specific environmental conditions.

Bauer, J. F.↗

NASA NTRS1980

A comparative study of cosmic ray intensity variations during 1972-1977 using spacecraft and ground-based observations

A study of cosmic ray intensity variations using data registered by Detector C on Pioneer 10 and the Sulphur Mountain neutron monitor is presented. The spacecraft data were corrected for temperature, Radioisotope Thermoelectric Generator background, and contamination by energetic solar particle events. A consistent long-term solar cycle variation intensity is observed, but additional contribution is observed in the neighborhood of 5.1 AU which is attributed to energetic electrons of Jovian origin. The spectral variation in long-term changes of the cosmic ray intensity is studied by comparing the low-energy and high-energy data, and an average value of their ratio during 1972-1977 was found to agree with the value for the 1965-1972 interval.

Venkatesan, D.↗

NASA NTRS1980

Comparative rocket observations of ionospheric electric fields in the auroral oval

The ion drift technique of measuring ionospheric electric fields is compared to two other simultaneous measurements. Rocket measurements in the evening auroral oval are checked against a dual probe, also in situ, and the ground based STARE auroral radar. The technique is explained thoroughly as well as tested for its dependence on mass. Two evening auroral oval conditions were observed from Andoya, Norway in January and February 1977. The first flight, 18:1005, measured electric fields over a quiet pre-midnight discrete arc. An interesting plasma convection reversal was observed poleward of the arc. The subsequent 18:1004, samples a breakup phase aurora nearer local midnight.

Zanetti, L. J., Jr.↗

NASA NTRS1982

Fast Holographic Comparator

Comparator is integrated-optical system constructed on a LiNb03sub. waveguide chip. Only the laser, lens and detector are external to chip. Aluminized surface gratings serve as input coupler and beam splitter. Light beams striking edges are returned by ordinary total internal reflection. Three operating modes are possible: A "screening" mode, an "identification" mode and a novel "self-subtraction" mode.

Vahey, D. W.↗

NASA NTRS1982

Precise Phase Comparator for Nearly Equal Frequencies

New circuit precisely compares phases of two RF signals nearly equal in frequency, such as two hydrogen-maser frequency standards. Measuring circuit minimizes interactions between two sources. Also stabilized against thermal effects and against noise that could produce erroneous readings. Heat sinking, buffer amplifiers, and low-noise zero-crossing detector make picosecond precision possible.

Reinhardt, V. S.↗

NASA NTRS1981

A comparative statistical study of long-term agroclimatic conditions affecting the growth of US winter wheat: Distributions of regional monthly average precipitation on the Great Plains and the state of Maryland and the effect of agroclimatic conditions on yield in the state of Kansas

A histogram analysis of average monthly precipitation over 30 and 84 year periods for both Maryland and Kansas was made and the results compared. A second analysis, a statistical assessment of the effect of average monthly precipitation on Kansas winter wheat yield was made. The data sets covered the three periods of 1941-1970, 1887-1970, and 1887-1921. Analyses of the limited data sets used (only the average monthly precipitation and temperature were correlated against yield) indicated that fall precipitation values, especially those of September and October, were more important to winter wheat yield than were spring values, particularly for the period 1941-1970.

Welker, J.↗

NASA NTRS1980

Comparative energy spectra of z equals 3-8 nuclei in the energy range 200 MeV/nuc to 3 GeV/nuc

The energy spectra and charge ratios of Li, Be, B, C, N, and O nuclei in the energy range 200 MeV/nuc to 3 GeV/nuc are examined with measurements obtained during a 50 hour balloon flight in 1977 from a telescope containing several scintillation and Cerenkov counters. The ratios Li/C, Be/C, and B/C are compared with predictions based on the leaky box interstellar propagation model showing that the ratios steadily increase in the apparent interstellar matter path length down to energies of about 400 to 600 MeV/nuc, where it is between 6.5 and 7.5 g/square cm. The effects of solar modulation upon the ratios are considered for energies less than about 1 GeV/nuc as well as for a modulation parameters of phi not less than 400 MV. By examining the ratios Li/Be, Li/B, and Be/B as a function of energy, it is shown that the Li/Be ratio is most sensitive to the solar modulation effects, and that the observed changes in this ratio with energy can be explained by a relatively large modulation consistent with a phi equal to 400 MV in 1977.

Webber, W. R.↗

NASA NTRS1980

A study of the comparative effects of various means of motion cueing during a simulated compensatory tracking task

NASA's Langley Research Center conducted a simulation experiment to ascertain the comparative effects of motion cues (combinations of platform motion and g-seat normal acceleration cues) on compensatory tracking performance. In the experiment, a full six-degree-of-freedom YF-16 model was used as the simulated pursuit aircraft. The Langley Visual Motion Simulator (with in-house developed wash-out), and a Langley developed g-seat were principal components of the simulation. The results of the experiment were examined utilizing univariate and multivariate techniques. The statistical analyses demonstrate that the platform motion and g-seat cues provide additional information to the pilot that allows substantial reduction of lateral tracking error. Also, the analyses show that the g-seat cue helps reduce vertical error.

Mckissick, B. T.↗

NASA NTRS1983

Document Update and Compare

Document Update and Compare programs provide simple computerized documentmaintenance system on Data General NOVA 840 computer. Document Update program allows user to update document either by batch or terminal input. Documents are modified and lists of modifications printed out.

Knoch, C. F.↗

NASA NTRS1981

A comparative study of the Harris-Priester, Jacchia-Roberts, and MSIS atmospheric density models in the context of satellite orbit determination

The comparisons are summarized. The quantities compared include Bayesian weighted least squares differential correction statistics and orbit solution consistency and accuracy.

Shanklin, R. E., Jr.↗

NASA NTRS1980

SCATHA SSPM charging response: NASCAP predictions compared with data

Models for the satellite surface potential monitor (SSPM) units constructed in the NASCAP code and the results of comparing predictions to surface voltage and baseplate current data are reported. Several peculiarities in the test data are noted. Preliminary results from space simulations of a SCATHA model with environments representative of the day 87, 1979, eclipse injection event are presented, and their implications for predicting space response are discussed.

Purvis, C. K.↗

NASA NTRS1981

Comparing dry aerosol size measurements

Two instruments were used to size dry aerosols for the CCN experiments: the Naval Research Laboratory (NRL) instrument which uses an electrical mobility analyzer to separate the aerosol size fractions and a diffusion chamber to grow and count the particles and the University of Wyoming (WYO) aerosol monitoring system. Measurements from these two systems were usually found to be in agreement during the CCN Workshop. Two examples are presented to compare aerosol size distribution measurements of the two instruments: experiment 8 (monodisperse NaCl) and experiment 27 (polydisperse AgI). Differential (dN/dR) and cumulative plots are shown for both instruments for experiment 8 and experiment 27; also shown are Aitken particle measurements for comparison.

Rogers, D. C.↗

NASA NTRS1981

Advanced general aviation comparative engine/airframe integration study

The NASA Advanced Aviation Comparative Engine/Airframe Integration Study was initiated to help determine which of four promising concepts for new general aviation engines for the 1990's should be considered for further research funding. The engine concepts included rotary, diesel, spark ignition, and turboprop powerplants; a conventional state-of-the-art piston engine was used as a baseline for the comparison. Computer simulations of the performance of single and twin engine pressurized aircraft designs were used to determine how the various characteristics of each engine interacted in the design process. Comparisons were made of how each engine performed relative to the others when integrated into an airframe and required to fly a transportation mission.

Huggins, G. L.↗

NASA NTRS1980

Comparative health and safety assessment of the SPS and alternative electrical generation systems

A comparative analysis of health and safety risks is presented for the Satellite Power System and five alternative baseload electrical generation systems: a low-Btu coal gasification system with an open-cycle gas turbine combined with a steam topping cycle; a light water fission reactor system without fuel reprocessing; a liquid metal fast breeder fission reactor system; a central station terrestrial photovoltaic system; and a first generation fusion system with magnetic confinement. For comparison, risk from a decentralized roof-top photovoltaic system with battery storage is also evaluated. Quantified estimates of public and occupational risks within ranges of uncertainty were developed for each phase of the energy system. The potential significance of related major health and safety issues that remain unquantitied are also discussed.

Habegger, L. J.↗

NASA NTRS1981

Steam reforming of n-hexane on pellet and monolithic catalyst beds. A comparative study on improvements due to heat transfer

Monolithic catalysts with higher available active surface areas and better thermal conductivity than conventional pellets beds, making possible the steam reforming of fuels heavier than naphtha, were examined. Performance comparisons were made between conventional pellet beds and honeycomb monolith catalysts using n-hexane as the fuel. Metal-supported monoliths were examined. These offer higher structural stability and higher thermal conductivity than ceramic supports. Data from two metal monoliths of different nickel catalyst loadings were compared to pellets under the same operating conditions. Improved heat transfer and better conversion efficiencies were obtained with the monolith having higher catalyst loading. Surface-gas interaction was observed throughout the length of the monoliths.

Source record↗

NASA NTRS1981

Veiling glare reduction methods compared for ophthalmic applications

Veiling glare in ocular viewing was simulated by viewing the retina of an eye model through a sheet of light-scattering material lit from the front. Four methods of glare reduction were compared, namely, optical scanning, polarized light, viewing and illumination paths either coaxial or intersecting at the object, and closed circuit TV. Photographs show the effect of these methods on visibility. Polarized light was required to eliminate light specularly reflected from the instrument optics. The greatest glare reduction was obtained when the first three methods were utilized together. Glare reduction using TV was limited by nonuniform distribution of scattered light over the image.

Buchele, D. R.↗