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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 1,729 records · Page 96

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NASA NTRS1974

Correlation and registration of ERTS multispectral imagery

Examples of automatic digital processing demonstrate the feasibility of registering one ERTS multispectral scanner (MSS) image with another obtained on a subsequent orbit, and automatic matching, correlation, and registration of MSS imagery with aerial photography (multisensor correlation) is demonstrated. Excellent correlation was obtained with patch sizes exceeding 16 pixels square. Qualities which lead to effective control point selection are distinctive features, good contrast, and constant feature characteristics. Results of the study indicate that more than 300 degrees of freedom are required to register two standard ERTS-1 MSS frames covering 100 by 100 nautical miles to an accuracy of 0.6 pixel mean radial displacement error. An automatic strip processing technique demonstrates 600 to 1200 degrees of freedom over a quater frame of ERTS imagery. Registration accuracies in the range of 0.3 pixel to 0.5 pixel mean radial error were confirmed by independent error analysis. Accuracies in the range of 0.5 pixel to 1.4 pixel mean radial error were demonstrated by semi-automatic registration over small geographic areas.

Bonrud, L. O.↗

NASA NTRS1975

An interdisciplinary analysis of multispectral satellite data for selected cover types in the Colorado Mountains, using automatic data processing techniques

The author has identified the following significant results. MSS data on the area near Lake Hope and San Miguel on the Ophir and Mt. Wilson quadrangles were classified. Two vein-like areas of alteration were apparent, along with the hill wash composed primarily of altered rock. These areas were quite delineated. A small oval patch of shadowed alteration was classified in a location in which alteration was previously unnoticed during an airphoto study.

Hoffer, R. M.↗

NASA NTRS1975

Real-time simulation of F100-PW-100 turbofan engine using the hybrid computer

A real-time hybrid computer simulation of the F100-PW-100 augmented turbofan is presented. The digital portion of the hybrid computer is used to perform the bivariate function generation associated with modeling the performance of the engine's rotating components. The remaining calculations are performed on the analog computer. Steady state simulation data along with sea level, static, transient data are presented to show that the real-time simulation matches baseline digital simulation results over a wide range of power settings and flight conditions. Steady state simulation data are compared with sea level, experimental data to show that the real-time hybrid and baseline digital simulations do adequately predict the performance of the actual engine. FORTRAN listings and analog patching diagrams are provided.

Szuch, J. R.↗

NASA NTRS1975

Prepared to launch

The verification of the interface between the preflight prepare-to-launch and flight program, targeting load, and flight program initialization was described. This is done using the digital command system coupled with a flight program patch and a memory dump command, the 6D/LVDC simulator, and a program trace through phase 1 initialization.

Source record↗

NASA NTRS1974

Optimum adaptive imaging through atmospheric turbulence

Recent results for the atmospheric mode decomposition are applied to an idealized imaging problem in which the receiver has a priori knowledge of the channel impulse response and mode decomposition. It is shown that a channel-matched filter receiver is essentially optimum and, on the average, achieves diffraction-limited performance. Furthermore, when the transmitting aperture lies within a single isoplanatic patch, this system may be realized without a priori channel knowledge by transmitted reference techniques.

Shapiro, J. H.↗

NASA NTRS1975

Preliminary imaging results from the second Mercury encounter

The second Mercury encounter has resulted in the acquisition of about 360 pictures of the south polar regions which provide a reliable cartographic and geologic tie between the two sides of the planet photographed on the first encounter. Stereoscopic coverage of large areas of the southern hemisphere was obtained by combining Mercury 1 and 2 pictures taken at different viewing angles. The south polar regions consist of heavily cratered terrain and intercrater plains interspersed with patches of smooth plains. No large areas of smooth plains similar to those surrounding Caloris occur in the south polar regions. No new types of terrain have been recognized, but lobate scarps are common. The second largest basin seen by Mariner 10 has been confirmed on the new photography. At high solar elevations the surface displays an abundance of rays and rayed craters.

Strom, R. G.↗

NASA NTRS1974

Orange material in the Sulpicius Gallus formation at the southwestern edge of Mare Serenitatis

Orange and red materials were observed and photographed in the dark mantle of the Sulpicius Gallus Formation on the southwestern rim of the Serenitatis basin. These materials occur only within the dark mantle that overlies old rilled mare and highland units and are absent on the younger mare unit in this area. Orange and red materials occur predominantly as halos, patches, or rays around fresh impact craters ranging in diameter from less than 50 to 250 m and in layers exposed at the base of the dark mantle deposit in the steep walls of a depression and a graben. Red material is present in the highland subsurface, possibly as dikes. We conclude that orange material, locally underlain by red material, occurs in the dark mantle to a depth of about 50 m as locally stratified but discontinuous pyroclastic deposits and that it may have been produced by multiple 'fire foundation' eruptions during the later stages of accumulation of the older mare basalt units.

Lucchitta, B. K.↗

NASA NTRS1975

The global characteristics of atmospheric emissions in the lower thermosphere and their aeronomic implications

The green line (555.7 nm) of atomic oxygen and the Herzberg bands of molecular oxygen (measured between 250 and 280 nm) as observed from the Ogo 4 airglow photometer from August 1967 through January 1968 are discussed in terms of their spatial and temporal distributions and their relation to the atomic oxygen content in the lower thermosphere. Daily maps of the distribution of emissions show considerable structure (cells, patches, and bands) with appreciable changes from day to day. When data are averaged over periods of several days in length, the resulting patterns have only occasional tendencies to follow geomagnetic parallels. The seasonal variation is characterized by maxima in both the Northern and Southern Hemispheres in October, the Northern Hemisphere having substantially higher emission rates. These maxima tend to move toward the poles, leaving very low values of emission at low latitudes in December and January. Noting the similarity of the atomic oxygen profiles in the lower thermosphere to the profile of a Chapman distribution, formulae are derived relating the vertical column emission rates of the green line and the Herzberg bands to the atomic oxygen peak density.

Reed, E. I.↗

NASA NTRS1975

Boundary-layer theory for blast waves

It is profitable to consider the blast wave as a flow field consisting of two regions: the outer, which retains the properties of the inviscid solution, and the inner, which is governed by flow equations including terms expressing the effects of heat transfer and, concomitantly, viscosity. The latter region thus plays the role of a boundary layer. Reported here is an analytical method developed for the study of such layers, based on the matched asymptotic expansion technique combined with patched solutions.

Kim, K. B.↗

NASA NTRS1977

Paddle-pin alinement test

Segmented insulated test bar speeds up patch distributor paddle-pin test. Device eliminates need to disconnect cables or remove distributor. Printed circuit cable and connector reduces weight on bar, adding to tester portability.

Gilliam, D. M.↗

NASA NTRS1975

Skylab altimeter observations over terrain

The author has identified the following significant results. Data obtained by Skylab radar altimeter (S193) over the continental U.S.A. for pass 1 of SL-3 were analyzed to relate radar return signal parameters such as range, power, and waveform to ground track terrain features. The altimeter, which was originally designed for ocean observations, performed predictably well over terrain with moderate to low relief. The maximum return from more complex areas corresponded usually to the lower flatter regions within the seven kilometer diameter footprint. Altimeter measured heights correlated with map topography with an rms deviation of + or - 30 m for terrain topography with large height dispersion (passes 1 and 28) and + or - 5 m for slowly varying terrain (passes 16, 17, and 18). Analysis of the waveform and statistical characteristics of the individual signals indicated that larger signal power was usually related to dominantly specular reflections from patches 100 m or larger. Results established the capability of a spacecraft altimeter system to observe characteristic radar signatures for different types of terrain within the bandwidth restrictions of the AGC and range tracker loops.

Shapiro, A.↗

NASA NTRS1975

Interactive computer aided technology, evolution in the design/manufacturing process

A powerful computer-operated three dimensional graphic system and associated auxiliary computer equipment used in advanced design, production design, and manufacturing was described. This system has made these activities more productive than when using older and more conventional methods to design and build aerospace vehicles. With the use of this graphic system, designers are now able to define parts using a wide variety of geometric entities, define parts as fully surface 3-dimensional models as well as "wire-frame" models. Once geometrically defined, the designer is able to take section cuts of the surfaced model and automatically determine all of the section properties of the planar cut, lightpen detect all of the surface patches and automatically determine the volume and weight of the part. Further, his designs are defined mathematically at a degree of accuracy never before achievable.

English, C. H.↗

NASA NTRS1975

Sikorsky interactive graphics surface design/manufacturing system

An interactive graphics system conceived to be used in the design, analysis, and manufacturing of aircraft components with free form surfaces was described. In addition to the basic surface definition and viewing capabilities inherent in such a system, numerous other features are present: surface editing, automated smoothing of control curves, variable milling patch boundary definitions, surface intersection definition and viewing, automatic creation of true offset surfaces, digitizer and drafting machine interfaces, and cutter path optimization. Documented costs and time savings of better than six to one are being realized with this system. The system was written in FORTRAN and GSP for use on IBM 2250 CRT's in conjunction with an IBM 370/158 computer.

Robbins, R.↗

NASA NTRS1975

Mariner 6 and 7 picture analysis

Analysis of Mariner 6 and 7 far-encounter (FE) pictures is discussed. The purpose of the studies was to devise ways to combine digital data from the full set of FE pictures so as to improve surface resolution, distinguish clouds and haze patches from permanent surface topographic markings, deduce improved values for radius, oblateness, and spin-axis orientation, and produce a composite photographic map of Mars. Attempts to measure and correct camera distortions, locate each image in the frame, and convert image coordinates to martian surface coordinates were highly successful; residual uncertainties in location were considerably less than one pixel. However, analysis of the data to improve the radius, figure, and axial tilt and to produce a composite map was curtailed because of the superior data provided by Mariner 9. The data, programs, and intermediate results are still available (1976), and the project could be resumed with little difficulty.

Leighton, R. B.↗

NASA NTRS1976

Ocean foam generation and modeling

A laboratory investigation was conducted to determine the physical and microwave properties of ocean foam. Special foam generators were designed and fabricated, using porous glass sheets, known as glass frits, as the principal element. The glass frit was sealed into a water-tight vertical box, a few centimeters from the bottom. Compressed air, applied to the lower chamber, created ocean foam from sea water lying on the frit. Foam heights of 30 cm were readily achieved, with relatively low air pressures. Special photographic techniques and analytical procedures were employed to determine foam bubble size distributions. In addition, the percentage water content of ocean foam was determined with the aid of a particulate sampling procedure. A glass frit foam generator, with pore diameters in the range 70 - 100 micrometers, produced foam with bubble distributions very similar to those found on the surface of natural ocean foam patches.

Porter, R. A.↗

NASA NTRS1976

Propagation of aircraft noise

The major tasks undertaken were (1) analytical and laboratory experiments on the propagation of sound from sources near a flat surface of finite acoustic impedance; (2) laboratory experiments dealing with the reflection of sound from finite sized plane patches; and (3) the diffraction of sound by wedge-and trapezoidal-shape barriers. In addition, a series of measurements were made of the background noise levels for various jet flow conditions in the Anechoic Noise Facility of the Langley Research Center's Acoustic and Noise Reduction Laboratory.

Pierce, A. D.↗

NASA NTRS1976

Lodestone: Nature's own permanent magnet

Magnetic hysteresis and microstructural details are presented which explain why the class of magnetic iron ores defined as proto-lodestones, can behave as permanent magnets, i.e. lodestones. Certain of these proto-lodestones which are not permanent magnets can be made into permanent magnets by charging in a field greater than 1000 oersted. This fact, other experimental observations, and field evidence from antiquity and the middle ages, which seems to indicate that lodestones are found as localized patches within massive ore bodies, suggests that lightning might be responsible for the charging of lodestones. The large remanent magnetization, high values of coercive force, and good time stability for the remanent magnetization are all characteristics of proto-lodestone iron ores which behave magnetically as fine scale ( 10 micrometer) intergrowths when subjected to magnetic hysteresis analysis. The magnetic results are easily understood by analysis of the complex proto lodestone microstructural patterns observable at the micrometer scale and less.

Wasilewski, P.↗

NASA NTRS1976

Natural resources inventory and land evaluation in Switzerland

The author has identified the following significant results. Using MSS channels 5 and 7 and a supervised classification system with a PPD classification algorithm, it was possible to map the exact areal extent of the snow cover and of the transition zone with melting snow patches and snow free parts of various sizes over a large area under different aspects such as relief, exposure, shadows etc. A correlation of the data from ground control, areal underflights and earth resources satellites provided a very accurate interpretation of the melting procedure of snow in high mountains.

Haefner, H.↗