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Results for “Measurement_method”

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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Experimental investigations of a uranium plasma pertinent to a self-sustaining plasma source

The research is pertinent to the realization of a self-sustained fissioning plasma for applications such as nuclear propulsion, closed cycle MHD power generation using a plasma core reactor, and heat engines such as the nuclear piston engine, as well as the direct conversion of fission energy into optical radiation (nuclear pumped lasers). Diagnostic measurement methods and experimental devices simulating plasma core reactor conditions are discussed. Studies on the following topics are considered: (1) ballistic piston compressor (U-235); (2) high pressure uranium plasma (natural uranium); (3) sliding spark discharge (natural uranium); (4) fission fragment interaction (He-3 and U-235); and (5) nuclear pumped lasers (He-3 and U-235).

Schneider, R. T.↗
NASA NTRS1972

Future techniques for tracking of synchronous satellites

A tracking system error analysis computer program is reported to study the feasibility of using range sum and range-rate sum measurements through a synchronous satellite to a user satellite, and range sum and range-rate sum measurements through a synchronous satellite to a ground based transponder for tracking of synchronous satellites. Error analysis transformed noise, bias, ground station location and orbit uncertainties into expected uncertainties in each of the orbits after tracking. Results show that both of the proposed measurement methods are feasible for determining and refining the orbits of future synchronous satellites.

Cooley, J. L.↗
NASA NTRS1972

STADAN antenna gain calibration using radio stars

An antenna gain measurement method was developed which utilizes a signal emitted from a radio star to determine absolute antenna gain at 136 MHz and 400 MHz for antennas in the STADAN network. An error analysis of the radio star method shows that the overall standard deviation uncertainty in antenna gain is + or - 0.6 db (1 sigma).

Taylor, R. E.↗
NASA NTRS1972

An investigation of geometry and noise corrections to San Marco-C neutral atmospheric composition experiment data

The problem of the calculation of ambient densities from San Marco-C neutral atmospheric composition experiment data is considered. A brief description is given of the data measurement method, followed by a description of both the theoretical and experimental data curves. Geometry, electrometer distortions, and noise effects are then studied in terms of their effects on the ideal data form. From these considerations two data reduction methods are evolved. The first is an iterative integration technique that exploits the symmetry of the experimental data about the minimum angle of attack. For the analysis of geometry effects, a second method using interval averaging was developed and studied.

Curtis, S. A.↗
NASA NTRS1972

Gain calibration of a horn antenna using pattern integration

Gain measurement of a horn antenna using three different techniques is discussed. The methods include a two-antenna insertion loss measurement, a pattern integration method, and a near-field measurement method. The application of the pattern integration method is considered, as well as the evaluation of the near-field gain correction factors for the horn, which are determined by a method based directly on measured data. This method involves a spherical wave expansion of the experimental radiation pattern of the specific antenna being tested, rather than evaluation of an assumed analytical model. The spherical wave expansion is also compared to experimental near-field pattern data.

Ludwig, A. C.↗
NASA NTRS1972

Lunar subsurface exploration with coherent radar.

The Apollo Lunar Sounder Experiment that is scheduled to orbit the moon on Apollo 17 consists of a three frequency coherent radar system and an optical recorder. The coherent radar can be used to measure both phase and amplitude characteristics of the radar echo. Measurement methods that are related to the phase and amplitude will be used to determine the surface profile, locate subsurface features and ascertain near surface electrical properties of the lunar surface. The key to the coherent radar measurement is a highly stable oscillator that preserves an accurate phase reference (2 or 3 electrical degrees) over a long period of time. This reference provides a means for reducing surface clutter so that subsurface features are more easily detected and also provides a means of measuring range to the surface to within a fraction of a wavelength.

Brown, W. E., Jr.↗
NASA NTRS1973

Sensitivity and comparison evaluation of Saturn 5 liquid penetrants

Results of a sensitivity and comparison evaluation performed on six liquid penetrants that were used on the Saturn 5 vehicle and other space hardware to detect surface discontinuities are described. The relationship between penetrant materials and crack definition capabilities, the optimum penetrant materials evaluation method, and the optimum measurement methods for crack dimensions were investigated. A unique method of precise developer thickness control was envolved, utilizing clear radiographic film and a densitometer. The method of evaluation included five aluminum alloy, 2219-T87, specimens that were heated and then quenched in cold water to produce cracks. The six penetrants were then applied, one at a time, and the crack indications were counted and recorded for each penetrant for comparison purposes. Measurements were made by determining the visual crack indications per linear inch and then sectioning the specimens for a metallographic count of the cracks present. This method provided a numerical approach for assigning a sensitivity index number to the penetrants. Of the six penetrants evaluated, two were not satisfactory (one was not sufficiently sensitive and the other was to sensitive, giving false indications). The other four were satisfactory with approximately the same sensitivity in the range of 78 to 80.5 percent of total cracks detected.

Jones, G. H.↗
NASA NTRS1973

Two frequency radar interferometry applied to the measurement of ocean wave height.

Description of a technique for measuring the rms wave height averaged over an area of the sea that is much greater than any horizontal scale of the surface waves. The measurement method involves a nadir looking radar that transmits and receives two continuous monochromatic signals simultaneously. Signal processing at the receiver requires the computation of a correlation function which is shown to depend only on the statistical rms surface elevation of specular points and not on the temporal or spatial frequency spectrum of the wave height or slope. Laboratory measurements have been conducted on wind driven waves, and the measured correlation function compares favorably with the underlying theory.

Weissman, D. E.↗
NASA NTRS1974

Differential phonograms

A new noise measuring method is outlined that is based on electronic analysis of the radiated noise. Non-relevant components are suppressed, while the differential phonogram displayed on the oscilloscope screen discloses the information carrying components. It allows low skilled operators to perform: (1) correct alignment of equipment; (2) detection of incipient failure; and (3) checking of prototypes.

Halpert, E.↗
NASA NTRS1974

Raman scattering applied to hypersonic air flow

The Raman scattering technique was applied to measure the local static temperature and gas number density over a sharp-edge flat-plate model in a Mach 5 nozzle of the Langley nozzle test chamber with air as the test gas. The angle of attack varied from -5 to 15 deg, and the stagnation temperature varied from 317 to 442 K, with stagnation pressures ranging from 170 kN to 2.8 MN/sq m. The measured values of static temperature and density ranged from 60 to 100 K and from 0.03 to 0.8 kg/cu m, respectively. A comparison with calculated values based on static pressure measurements along the model shows that the Raman scattering technique is a viable measurement method in applications to high-speed three-dimensional flows.

Hillard, M. E., Jr.↗
NASA NTRS1972

Multispectral photography for earth resources

A guide for producing accurate multispectral results for earth resource applications is presented along with theoretical and analytical concepts of color and multispectral photography. Topics discussed include: capabilities and limitations of color and color infrared films; image color measurements; methods of relating ground phenomena to film density and color measurement; sensitometry; considerations in the selection of multispectral cameras and components; and mission planning.

Wenderoth, S.↗
NASA NTRS1974

Experiments in determining the outgassing of spacecraft in the vacuum environment

As spacecraft become more sophisticated, their contamination becomes of increasing concern. The use of real-time monitors, such as the quartz crystal microbalance, and post-test methods such as the chemical analysis of residuals, has been combined with a number of analytical techniques in contamination-related investigations at the Goddard Space Flight Center. These include the establishment of the cause of an orbital failure, the determination of component outgassing rates, and the monitoring of contaminants in vacuum chambers and in orbit. Improved capabilities appear possible with measurement methods such as attenuated total reflectance and better analytical modeling of the contaminant flux environment.

Kruger, R.↗
NASA NTRS1975

Review of Terrestrial Photovoltaic Measurements Workshop

Measurement methods for terrestrial solar cells require calibration standards to set simulator irradiance levels or to monitor solar irradiance in outdoor measurements. Measurements of solar cell performance in terrestrial sunlight are the most acceptable, but an artificial light source can be used for laboratory measurements.

Brandhorst, H. W., Jr.↗
NASA NTRS1975

Metabolism and heat dissipation during Apollo EVA periods

The extravehicular activity life support equipment, suit temperature control, metabolic rate measurement methods, and energy production are discussed. The Apollo crewmen were able to perform planned extravehicular activities and to extend them to the maximum time allowable without medical problems. The metabolic rates experienced during the lunar surface extravehicular activities were lower than conservative premission estimates. A manually controlled liquid cooling garment was effectively used to minimize fatigue and water loss from sweating during lunar surface extravehicular activities. Gas cooling was adequate during the short zero-g extravehicular activities performed from the command module. The prediction of EVA workloads became more reliable as inflight data was accumulated. The prediction of the average metabolic cost of an EVA was more reliable than the cost of an individual short-term task.

J.M. Waligora↗
NASA NTRS1975

Preliminary design study. Shuttle modular scanning spectroradiometer

Fundamental concepts on which to base a detailed design for a Shuttle Modular Scanning Spectroradiometer were developed, and a preliminary design is presented. The recommended design features modularity and flexibility. It includes a 75-cm f/1.7-telescope assembly in an all-reflective Schmidt configuration, a solid state scan system (pushbroom) with high resolution over a 15 deg field of view, and ten detector channels covering the spectral range from 0.45 to 12.5 micrometers. It uses charge transfer device techniques to accommodate a large number of detector elements for earth observation measurements. Methods for in-flight radiometric calibration, for image motion compensation, and for data processing are described. Recommendations for ground support equipment are included, and interfaces with the shuttle orbiter vehicle are illustrated.

Source record↗
NASA NTRS1975

International Symposium on Remote Sensing of Environment, 10th, University of Michigan, Ann Arbor, Mich., October 6-10, 1975, Proceedings. Volumes 1 & 2

Topics treated include the application of a Fourier transform spectrometer to infrared remote sensing, the performance optimization of a satellite-borne thematic mapper, a data handling system to be integrated with a digital airborne multispectral scanner, infrared thermography for micro- and mesometeorological measurements, satellite interrogated data collection platforms for river and flood forecasting and the automatic measurement of sea surface temperature from a GOES satellite. Solar and atmospheric effects on satellite imagery derived from aircraft reflectance measurements, methods for determining haze levels from multispectral scanner data, restoration of Landsat images by discrete two-dimensional deconvolution and the automatic classification of aircraft and satellite multispectral images using mixed integer programming are also discussed. Individual items are announced in this issue.

Source record↗
NASA NTRS1975

Airborne laser bathymeter

A description is given of a program concerned with the development and the evaluation of techniques for the measurement of water depth with a pulsed laser. Airborne laser bathymetry makes use of a light pulse which is sent downward. Information concerning the water depth is provided by the time interval observed between the arrival of the light pulse reflected from the water surface and the arrival of the pulse coming from the ocean floor. Details concerning the instrumentation used for the developed measurement method are discussed. Attention is also given to field experiments and aspects of system performance.

Cervenka, P. O.↗