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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 685 records · Page 38
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NASA NTRS1977

An experimental investigation of airframe component interference noise

Measurements of noise produced by a model of a wheel well (rectangular cavity), landing gear (wheel and strut), and flap at Mach numbers of 0.18 and 0.40 have been made in an anechoic flow facility. Individual component noise and component interference noise are described in terms of the OASPL, spectra, and streamwise or flyover directivity patterns. Areas of significant sound generation are illuminated and causes of these noise sources are suggested. Results from an acoustic imaging technique are used to point out other source regions not discernible by simple far-field measurements.

Block, P. J. W.↗
NASA NTRS1976

Surface and atmosphere parameter maps from earth-orbiting radiometers

Earlier studies have shown that an earth-orbiting electrically scanned microwave radiometer (ESMR) is capable of inferring the extent, concentration, and age of sea ice; the extent, concentration, and thickness of lake ice; rainfall rates over oceans; surface wind speeds over open water; particle size distribution in the deep snow cover of continental ice sheets; and soil moisture content in unvegetated fields. Most other features of the surface of the earth and its atmosphere require multispectral imaging techniques to unscramble the combined contributions of the atmosphere and the surface. Multispectral extraction of surface parameters is analyzed on the basis of a pertinent equation in terms of the observed brightness temperature, the emissivity of the surface which depends on wavelength and various parameters, the sensible temperature of the surface, and the total atmospheric opacity which is also wavelength dependent. Implementation of the multispectral technique is examined. Properties of the surface of the earth and its atmosphere to be determined from a scanning multichannel microwave radiometer are tabulated.

Gloersen, P.↗
NASA NTRS1977

Usefulness of LANDSAT data for monitoring plant development and range conditions in California's annual grassland

A network of sampling sites throughout the annual grassland region was established to correlate plant growth in stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. Data were analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site, and changing growth conditions.

Carneggie, D. M.↗
NASA NTRS1978

Viking Orbiter stereophotogrammetry

Orbit characteristics of the two Viking Orbiter spacecraft made possible the acquisition of high-resolution imagery of the Martian surface, resulting in many excellent convergent stereopairs. Evaluation of these stereopairs presented a few unconventional problems because the routine relative orientation was not feasible, mainly due to a lack of good passpoints and to the technical peculiarities of TV vidicon imaging techniques. One of the ways to circumvent these problems is to use the orbital and navigational parameters of the spacecraft for an external 'forced' relative orientation. This approach requires a number of rotations and counter-rotations between various coordinate systems, which may make the involved mathematics look rather complicated, but its computational applications become very simple, fast, accurate, and inexpensive.

Benesh, M.↗
NASA NTRS1979

Far-infrared observations of H 2 regions and associated galactic and extragalactic sources

Using imaging techniques maps were made at 50 and 100 micrometers with one foot resolution of a region around the galactic center about one-half degree in extent. Higher resolution maps were made of the central portion of the galaxy at 30, 50, and 100 micrometers. Resolution maps of a reflection nebula were also made. Infrared sources associated with molecular clouds were investigated.

Source record↗
NASA NTRS1979

Remote sensing

Various imaging techniques are outlined for use in mapping, land use, and land management in Mexico. Among the techniques discussed are pattern recognition and photographic processing. The utilization of information from remote sensing devices on satellites are studied. Multispectral band scanners are examined and software, hardware, and other program requirements are surveyed.

Jinich, A.↗
NASA NTRS1978

Synthetic Aperture Radar Technology Conference, New Mexico State University, Las Cruces, N. Mex., March 8-10, 1978, Proceedings

The following aspects of SAR development are discussed: calibration techniques, image simulation and interpretability, antennas, data processing, and system design. Papers are presented on such topics as a postlaunch calibration experiment for the Seasat-A SAR, computer simulation of an orbital SAR system, definition study of the Shuttle Imaging Radar, custom LSI circuits for spaceborne SAR processors, and random sampling adaptively focusing SAR.

Source record↗
NASA NTRS1979

The diameter of Pallas from its occultation of SAO 85009

The May 29, 1978, occultation of SAO 85009 by Pallas was observed photoelectrically at seven widely spaced sites. The observations are well represented by an elliptical apparent limb profile having semimajor and semiminor axes of 279.5 + or - 2.9 and 262.7 + or - 4.5 km, respectively. Combining these results with published information on the light curve and rotational pole position, Pallas's mean diameter is found to be 538 + or - 12 km, which yields a mean density for Pallas of 2.8 + or - 0.5 g/cu cm and a visual geometric albedo of 0.103 + or - 0.005. The diameter of Pallas as determined from this occultation is significantly smaller than the values derived by radiometric, polarimetric, and double-image techniques.

Wasserman, L. H.↗
NASA NTRS1980

Application of a magnetograph and X-ray telescope to the study of coronal structure variations

The application of magnetographs and X-ray imaging techniques to determine the magnitude, structure, origin, and evolution of the solar coronal magnetic field is examined. The spatial and temporal resolution of the X-ray telescope is discussed and a comparison of ground based magnetogram sequences versus a magnetograph in space is presented. Skylab photographs of the evolution of transient coronal holes are provided.

Rust, D. M.↗
NASA NTRS1980

AMTV headway sensor and safety design

A headway sensing system for an automated mixed traffic vehicle (AMTV) employing an array of optical proximity sensor elements is described, and its performance is presented in terms of object detection profiles. The problem of sensing in turns is explored experimentally and requirements for future turn sensors are discussed. A recommended headway sensor configuration, employing multiple source elements in the focal plane of one lens operating together with a similar detector unit, is described. Alternative concepts including laser radar, ultrasonic sensing, imaging techniques, and radar are compared to the present proximity sensor approach. Design concepts for an AMTV body which will minimize the probability of injury to pedestrians or passengers in the event of a collision are presented.

Johnston, A. R.↗
NASA NTRS1976

A low light level television system

A proposal was submitted in response to the announcement of opportunities for Skylab 1 involving low light level imaging techniques. While the observational objectives are not necessarily pertinent to cometary experimentation and observation the instrumentation possibly would be, and is potentially available if the proposal is successful. The proposed observations are of natural and induced atmospheric glows and near vehicle aerosol distribution.

Duncan, B. J.↗
NASA NTRS1982

Ordered mixed-layer structures in the Mighei carbonaceous chondrite matrix

High resolution transmission electron microscopy of the Mighei carbonaceous chondrite matrix has revealed the presence of a new mixed layer structure material. This mixed-layer material consists of an ordered arrangement of serpentine-type (S) and brucite-type (B) layers in the sequence SBBSBB. Electron diffraction and imaging techniques show that the basal periodicity is approximately 17 A. Discrete crystals of SBB-type material are typically curved, of small size (less than 1 micron) and show structural variations similar to the serpentine group minerals. Mixed-layer material also occurs in association with planar serpentine. Characteristics of SBB-type material are not consistent with known terrestrial mixed-layer clay minerals. Evidence for formation by a condensation event or by subsequent alteration of pre-existing material is not yet apparent.

Mackinnon, I. D. R.↗
NASA NTRS1982

Effect of Fluid Flow on Zinc Electrodeposits from Acid Chloride Electrolytes

Zinc was deposited potentiostatically from acid chloride baths. Once bath chemistry and electrochemistry were controlled, the study was focused on convective mass transfer at horizontal electrodes and its effect on cell performance. A laser schlieren imaging technique allowed in situ observations of flow patterns and their correlation with current transients. Convection was turbulent and mass transfer as a function of Rayleigh number was well correlated by: Sh = 0.14 R to the 1/3 power. Similarly, convection initiation time was correlated by DT/d squared = 38 Ra to the -2/3 power. Time scale of fluctuations was about half the initiation time. Taking the boundary layer thickness as a characteristic length, a critical Rayleigh number for the onset of convection was deduced: Ra sub CR = 5000. Placing the anode on the top of the cathode completely changed the flow pattern but kept the I-t curves identical whereas the use of a cathode grid doubled the limiting current. A well defined plateau in the current voltage curves suggested that hydrogen evolution has been successfully inhibited. Finally, long time deposition showed that convection at horizontal electrodes increased the induction time for dentrite growth by at least a factor of 2 with respect to a vertical wire.

Abdelmassir, A. A.↗
NASA NTRS1984

Search for solar signals in GOES imagery and cloud climatology analysis

The digitization and analysis of 16mm GOES IR imagery to identify spatial and temporal variation in clouds is discussed, along with a cloud climatology analysis. Recently added to the Interactive Graphics Package was a Computer Image Analysis System. This system allows many new imaging techniques. One of the possibilities is the analysis of overall light intensity variations in six 10 degree square boxes across the intertropical convergence zone. This technique is discussed, as is a preliminary analysis of unnormalized data.

Markson, R. J.↗
NASA NTRS1983

Digital images of combined oceanic and continental data sets and their use in tectonic studies

It is shown how crustal and lithospheric studies can benefit when continental and oceanic data sets are combined. It is also shown how digital imaging techniques provide an effective means for displaying the information contained in these combined data sets. The region of Australia, New Zealand, and the surrounding ocean is chosen for illustrating the advantages of combining continental and oceanic data sets. Here, the tectonic setting of Australia, a relatively stable continent in an intraplate environment, can be contrasted with New Zealand, which is traversed by one of the world's major plate boundaries. Simultaneous display and analysis of complementary data sets make possible a rapid geologic and tectonic interpretation of regional areas. It is shown, by way of example, that the relationship between topography and gravity anomalies in central Australia gives important new information concerning the state of isostasy of thrust terrains and their related sedimentary basins and hence provides a means of understanding the mechanical properties of the continental lithosphere.

Haxby, W. F.↗