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At least 1,117 records · Page 62
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Landsat-1 imagery for geologic evaluation

The paper reviews the geologic evaluation of the North Carolina coastal plain using Landsat-1 imagery as related to a general study of the geomorphology to assess the imagery as a tool for upgrading the understanding of the coastal plain, along with recognition of subsurface structures. Among the more prominent features displayed on the Landsat imagery are the scarps and beach ridges associated with former positions of the shoreline. Compilations of various types of lineaments reveal two dominant trends, one northwest-southeast and the other northeast-southwest, which are significant in the tectonic development of the Atlantic Coastal Plain. The synoptic view recorded by the satellite allows a perspective that aids geologic studies of the Atlantic Coastal Plain.

Welby, C. W.↗
NASA NTRS1976

The revised 3C catalog of radio sources - A review of optical identifications and spectroscopy

We present a catalog of the important optical data for the radio sources in the Revised Third Cambridge Catalog. Optical positions, redshifts, magnitudes, and identifications have been included, as well as radio flux densities and spectral indices for the sample of 297 extragalactic 3CR sources. A bibliography of optical identifications, spectroscopy, and radio position/structure is also given. In addition to the literature compilation, we present new spectroscopic observations of 27 3CR radio galaxies, 25 of which do not have previously published redshifts.

Smith, H. E.↗
NASA NTRS1976

Crater dimensions from Apollo data and supplemental sources

A catalog of crater dimensions that were compiled mostly from the Apollo-based Lunar Topographic Orthophotomaps is presented in its entirety. Values of crater diameter, depth, rim height, flank width, circularity, and floor diameter (where applicable) are tabulated for a sample of 484 craters on the moon and 22 craters on earth. Systematic techniques of mensuration are detailed. The lunar craters range in size from 400 m to 300 km across and include primary impact craters of the main sequence, secondary impact craters, craterlets atop domes and cones, and dark-halo craters. The terrestrial craters are between 10 m and 22.5 km in diameter and were formed by meteorite impact.

Pike, R. J.↗
NASA NTRS1976

An algorithm for automatic reduction of complex signal flow graphs

A computer algorithm is developed that provides efficient means to compute transmittances directly from a signal flow graph or a block diagram. Signal flow graphs are cast as directed graphs described by adjacency matrices. Nonsearch computation, designed for compilers without symbolic capability, is used to identify all arcs that are members of simple cycles for use with Mason's gain formula. The routine does not require the visual acumen of an interpreter to reduce the topology of the graph, and it is particularly useful for analyzing control systems described for computer analyses by means of interactive graphics.

Young, K. R.↗
NASA NTRS1977

The Apollo 17 'melt sheet' - Chemistry, age and Rb/Sr systematics

Major, minor, and trace-element compositions, age data, and Rb/Sr systematics of Apollo 17 boulders have been compiled, and additional analyses performed on a norite breccia clast (77215) included in the Apollo 17, Station 7 boulder. The Apollo 17 boulders are found to be identical or nearly so in major, minor, and trace-element composition, suggesting that they all originated as an impact melt analogous to melt sheets found in larger terrestrial craters. The matrix dates (Ar-40/Ar-39) and Rb/Sr systematics available suggest that this impact melt formed by a single impact about 4 billion years ago. This impact excavated, shocked, brecciated, and melted norites, norite cumulates, and possibly anorthositic gabbros and dunites about 4.4 billion years old. The impact was likely a major one, possibly the Serenitatis basin-forming event.

Winzer, S. R.↗
NASA NTRS1977

Copernicus observations of the Ap star Epsilon Ursae Majoris

Spectral scans of the Ap star Epsilon UMa made with the Copernicus satellite show strong line blanketing from profuse Cr II and Fe II lines. In the spectral region covering 1900 to 3000 A, about 500 lines are present which suppress the apparent continuum by at least 15-30%. An accurate line-identification list is compiled showing Eu II present in addition to Mn II and Ni II. The identification of Eu II, however, rests on very stringent identification limits for Fe II. If these are relaxed, the existence of Eu II is dubious. There are no broad features in this spectral region which would suggest strong photoionization discontinuities by metals, but one feature near 2137 A might contain the photoionization edge due to Cr I 5S lying 0.94 eV above the ground level. However, a significant correlation between the line-blanketing strength and the amplitude of the OAO-2 ultraviolet light curves was found such that both monotonically increase in the same proportion toward shorter wavelengths. This gives additional strength to the suggestion that variations in the metal line-blanketing cause the observed photometric variations.

Mallama, A. D.↗
NASA NTRS1976

The geology of Mars

The book constitutes a topographic/geologic atlas of Mars compiled on the basis of data from the various Mariner missions. A large number of maps has been included which systematically describe the character and distribution of the principal landforms: craters, channels, volcanoes, and faults; also related properties such as albedo, elevation, and wind streaks. Pictures of all the important topographic features have been included. The discussion of the material is carried out with a minimum of technical detail, and Mars is examined within a context of interplanetary comparisons.

Mutch, T. A.↗
NASA NTRS1977

Airphoto assessment of changes in aquatic vegetation

Large scale, multiyear, color and color infrared aerial photographs were used to evaluate changes in aquatic vegetation that have accompanied a reduction in phosphorus inputs to a phosphorus-limited, eutrophic lake in New York State. The study showed that the distribution of emergent, floating and submersed vegetation could be determined with little or no concurrent ground data; that various emergent and floating types could be separated and, with limited field checks, identified; and that different submersed types are generally not separable. Major vegetative types are characterized by spectral and nonspectral features, and a classification is developed for compiling time-sequential vegetation maps.

Markham, B. L.↗
NASA NTRS1977

Nearest-neighbor doublets in protein-coding regions of MS2 RNA

'Nearest neighbor' base pairs ('doublets') in the protein-coding regions of MS2 RNA have been tabulated with respect to their positions in the first two bases of amino acid codons, in the second two bases, or paired by contact between adjoining codons. Considerable variation is evident between numbers of doublets in each of these three possible positions, but the totals of each of the 16 doublets in the coding regions of the MS2 RNA molecule show much less variation. Compilations of doublets in nucleic acid strands have no predictive value for the amino acid composition of proteins coded by such strands.

Jukes, T. H.↗
NASA NTRS1976

Ages of flow units in the lunar nearside maria based on Lunar Orbiter IV photographs

A map dividing the lunar nearside maria into six units each of uniform age was compiled from Lunar Orbiter IV photographs. Relative ages were determined using a crater morphology technique. Relative ages were then converted to absolute ages by comparison to a curve calibrated from Apollo and Luna sample data; three of the six units, including the two youngest (about 3.1 and 2.6 b.y. old), were not sampled by Apollo or Luna. Vast regions in the western maria are covered by these young flows. The old flows (about 3.75 b.y. in age) are found to occur mostly in the eastern maria. A comparison of the age units derived from these data with those units derived from other remote-sensing data provide good agreement in the location of unit boundaries. These data also indicate that the emplacement history of mare basalt types is more complex than was earlier thought.

Boyce, J. M.↗
NASA NTRS1976

The formulation of simulation models of aeronautical systems

Recent developments in formula-manipulation compilers have led to a significant reduction in the time spent in formulating models of complex multi-degrees-of-freedom dynamical systems. MACSYMA, a computer system that can be used to perform symbolic manipulations in an interactive mode, is applied to the problem of formulating models of aeronautical systems for simulation studies. An example demonstrates that once the procedure is established, the formulation and modification of the models can be reduced to a series of routine computer operations.

Howard, J. C.↗
NASA NTRS1977

A photometric study of the Orion OB 1 association. I - Observational data. II - Photometric analysis

A catalog of observational data is presented for stars in the region of the young stellar association Orion OB 1. Photoelectric observations obtained in the uvby-beta and UBV systems are compiled along with previous photoelectric and spectroscopic data for all these stars as well as for several bright members of the association with available photometric indices. Mean weighted values are computed for the photometric data and summarized in tables expected to be reasonably complete for association members earlier than spectral type A0. Membership criteria are derived, and qualitative membership probabilities summarized, for the 526 stars in the final program. The analytical procedures are discussed for association stars of B, intermediate, and AF types. Effects of the nebular environment and various calibrations of Balmer-line and four-color indices are considered for the determination of absolute magnitudes for the B-type stars.

Warren, W. H., Jr.↗
NASA NTRS1977

Gravimetric geoid in the Northwest Pacific Ocean

A total of 3708 1 x 1 deg free-air gravity anomaly averages have been used to construct a new 1 x 1 deg gravimetric geoid of the Northwest Pacific Ocean. The 1 x 1 deg averages are based on a compilation of 147,000 surface ship and pendulum gravity measurements. Difference geoid undulations range from a maximum of +19 m over the Hawaiian ridge to a minimum of -31 m over the junction of the Kuril and Aleutian trenches. The Hawaiian swell is associated with a geoidal high of up to +15 m with wavelengths of about 2200 km and the topographic rises seaward of deep-sea trenches are associated with geoidal highs of up to 4 m with wavelengths of about 220-900 km. The agreement between the gravimetric geoid and Skylab-4 and Geos-3 altimeter data is close for wavelengths greater than about 300 km but poor for shorter wavelengths.

Watts, A. B.↗
NASA NTRS1977

Discovery of a 7.68 second X-ray periodicity in 3U 1626-67

SAS-3 observations of the X-ray source 3U 1626-67 have revealed the presence of a stable 7.68-sec pulse period. This source was selected for study because of its hard X-ray spectrum. The compilation of source spectra used in the selection process is also presented. Pulse arrival times are analyzed for effects of possible binary orbital motion. Upper limits to the projected orbital radius are obtained which tend to exclude orbital periods in the range from about 0.5 to 35 days. Binary systems with either a very long orbit (at least 175 days) or a very short orbit (no more than about 0.3 day) are most probable

Rappaport, S.↗
NASA NTRS1972

Supercritical Wing Technology: A Progress Report on Flight Evaluations

The papers in this compilation were presented at the NASA Symposium on "Supercritical Wing Technology: A Progress Report on Flight Evaluation" held at the NASA Flight Research Center, Edwards, Calif., on February 29, 1972. The purpose of the symposium was to present timely information on flight results obtained with the F-8 and T-2C supercritical wing configurations, discuss comparisons with wind-tunnel predictions, and project [ ] flight programs planned for the F-8 and F-III (TACT) airplanes.

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NASA NTRS1978

Automated tester for MOS devices

Automated system rapidly diagnoses MOS integrated circuits. Its programed electronics investigate transistor and cell characteristics to compile data needed for screening. Program can be changed rapidly to alter test procedures, test duration, and precision.

Cockrum, R. H.↗
NASA NTRS1979

Problems encountered in solar heating and cooling systems

Report discussing various experiences of workers at Marshall Space Flight Center in developing solar heating and cooling systems is presented. Presents compilation of problems and their resolutions which can assist designers of solar-energy systems and prevent repetition of errors.

Cash, M.↗
NASA NTRS1979

Prototype residential solar-energy system-design package

Compilation includes documents and drawings for complete solar-heating system. It discussed system installed in residential building at Veterns' Administration Hospital in Togus, Maine. System can be adapted to other buildings without changing design.

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