Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “trough”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Mars: Troughed terrain

One of the spectacular revelations of the Mariner 9 pictures was the assemblage of huge troughs in the Tithonius Lacus-Coprates region of equatorial Mars. These features represent a significant phase in the planet's evolution, and their interpretation although necessarily highly speculative is justified by the potential for indicating something of the nature of surficial and internal conditions and processes of Mars.

Sharp, R. P.↗
NASA NTRS1975

Faults on Skylab imagery of the Salton Trough area, Southern California

The author has identified the following significant results. Large segments of the major high angle faults in the Salton Trough area are readily identifiable in Skylab images. Along active faults, distinctive topographic features such as scarps and offset drainage, and vegetation differences due to ground water blockage in alluvium are visible. Other fault-controlled features along inactive as well as active faults visible in Skylab photography include straight mountain fronts, linear valleys, and lithologic differences producing contrasting tone, color or texture. A northwestern extension of a fault in the San Andreas set, is postulated by the regional alignment of possible fault-controlled features. The suspected fault is covered by Holocene deposits, principally windblown sand. A northwest trending tonal change in cultivated fields across Mexicali Valley is visible on Skylab photos. Surface evidence for faulting was not observed; however, the linear may be caused by differences in soil conditions along an extension of a segment of the San Jacinto fault zone. No evidence of faulting could be found along linears which appear as possible extensions of the Substation and Victory Pass faults, demonstrating that the interpretation of linears as faults in small scale photography must be corroborated by field investigations.

Merifield, P. M.↗
NASA NTRS1975

Auroral N2 vibrational excitation and the electron density trough

Through various processes molecular nitrogen within the nocturnal auroral oval is vibrationally excited, substantially increasing the rate at which O(+) is lost via the reaction O(+) + N2* yields NO(+) + N. Owing to the action of thermospheric winds and diffusion, N2* does not remain at its point of origin but is transported to regions outside the auroral oval where it can act to substantially reduce the F-region electron density. For an equatorward transport speed of 100 m/sec, N2* can travel 3 to 4 deg of latitude before quenching with atomic oxygen substantially reduces the N2* density. This process may contribute significantly to the formation of the midlatitude F-region electron density trough.

Schunk, R. W.↗
NASA NTRS1975

SLAR reconnaissance, Mimika-Eilanden Basin, Southern Trough of Irian Jaya

The SLAR was obtained in early April 1973 by means of an AN/APQ-97 K-band brute-force system. The flight strips are all north-look, with ground-range display, and 60% overlap. The interpretation was compiled on a 1/100,000-scale mosaic, but the actual mapping of contacts, dips, lineaments, and the like, was done on 1/100,000-scale stereo-strips. Initial regional mapping was intended as an aid in determining that part of the Southern Trough most likely to be underlain by relatively unmetamorphosed paralic Kembelangan sandstones ideally interdigitated with marine source and cape shales. SLAR reconnaissance mapping met a subsequent need to rapidly and inexpensively narrow the search to that part of the "fairway' coincident with a favorable structure. The SLAR mosaic clearly displays the Irian mountains, strongly and gently folded foothills belts, and the southern front of the fold belt south of which is a large complex of alluvial fans.

Wing, R. S.↗
NASA NTRS1977

Mariner 10 data analysis. 1: Scarps, ridges, troughs, and other lineaments on Mercury. 2: Geologic significance of photometric variations on Mercury

Volcanic and tectonic implications of the surface morphology of Mercury are discussed. Mercurian scarps, ridges, troughs, and other lineaments are described and classified as planimetrically linear, arcuate, lobate, or irregular. A global pattern of lineaments is interpreted to reflect modification of linear crustal joints formed in response to stresses induced by tidal spindown. Large arcuate scarps on Mercury most likely record a period of compressional tectonism near the end of heavy bombardment. Shrinkage owing to planetary cooling is the mechanism preferred for their production. Measurements of local normal albedo are combined with computer-generated photometric maps of Mercury to provide constraints on the nature of surface materials and processes. If the mercurian surface obeys the average lunar photometric function, its normal albedo at 554 nm is .16 + or - .03.

Dzurisin, D.↗
NASA NTRS1977

Experimental evaluation of a fixed collector employing vee-trough concentrator and vacuum tube receivers

A test bed for experimental evaluation of a fixed solar collector which combines an evacuated glass tube solar receiver with a flat plate/black chrome plated copper absorber and an asymmetric vee-trough concentrator was designed and constructed. Earlier predictions of thermal performance were compared with test data acquired for a bare vacuum tube receiver; and receiver tubes with Alzak aluminum, aluminized FEP Teflon film laminated sheet metal and second surface ordinary mirror reflectors. Test results and system economics as well as objectives of an ongoing program to obtain long-term performance data are discussed.

Selcuk, M. K.↗
NASA NTRS1978

Flat-sided rectilinear trough as a solar concentrator - An analytical study

Formulas are derived for the concentration factor and irradiance distribution at the base of the flat-sided linear trough. Performance is affected by the number of reflections the solar rays undergo before reaching the base, the cone apex angle, and the coefficient of reflection. Results are presented graphically in such a way that one can choose the optimum configuration, which is the minimum material required, to achieve a given concentration factor. Practical concentration factors range from 1.5 to 4 depending on the geometry and coefficient of reflection.

Burkhard, D. G.↗
NASA NTRS1978

Detached auroral arcs in the trough region

In a previous paper, Moshupi et al. (1977) have reported on the occurrence of rare auroral 'patches' equatorward of the normally well-defined boundary of diffuse aurora. Some less spectacular but more common arclike features were observed in the same 'trough' region (between the plasmapause and the auroral oval) during the period 1972-1975. These 'detached' arcs show some similarities to stable auroral red arcs in terms of their location and occurrence, but are completely different spectroscopically in that the stable auroral red arcs produce almost pure atomic oxygen red line emissions, whereas the detached arcs are deficient in red line emission - a feature implying totally different production mechanisms. The characteristics of the detached lines are described, including their unusual local time/longitude dependence.

Anger, C. D.↗
NASA NTRS1978

The tectonic and volcanic history of Mercury as inferred from studies of scarps, ridges, troughs, and other lineaments

Tectonic and volcanic modification of the Mercurian surface is discussed, and nine landform classes are defined. An evolutionary chronology, based on reported interpretations of scarp, ridge, trough, and other lineament features, is presented, and the roles (in chronological order) of accretion and differentiation, tidal spindown, plains volcanism, heavy bombardment, cooling/contraction, Caloris impact, intense surface modification, basin subsidence, local plains volcanism, isostatic basin uplift, and light cratering are considered. The observational data were obtained by Mariner 10.

Dzurisin, D.↗
NASA NTRS1979

Characteristics of trough region auroral patches and detached arcs observed by Isis 2

All of the data presented in this paper were obtained from the Isis 2 satellite, which was launched into a 1400-km near-circular polar orbit in April 1971. Instruments used in this study include the topside sounder for providing vertical profiles of the electron density, the Langmuir probe for measuring electron temperature and concentration, and the auroral scanning photometer for detecting optical emissions at 5577 A and 3914 A. Two distinct types of auroras (east-west-aligned oval-shaped 'patches', and isolated east-west 'detached arcs') are observed in the trough region (almost exclusively in the Northern Hemisphere) equatorward of the diffuse auroral boundary. Attention is given to comparison of patches and detached arcs, relation to magnetic indices, and relation to detached plasma and ELF hiss.

Moshupi, M. C.↗
NASA NTRS1979

Recombination of NO/+/ in the mid-latitude trough and the polar ionization hole

The dissociative recombination of NO(+) with electrons is further examined using a sample of Atmosphere Explorer data from the midlatitude ionization trough. The electron temperature for this data sample covered a range of 2500 K, thus allowing an accurate determination of the temperature dependence of the rate coefficient. The results confirm earlier determinations which were made from a large data base, and the rate coefficient alpha is found to be inversely proportional to the electron temperature. The possibility of a neglected process in the NO(+) chemistry is investigated which, if it were included, might result in a smaller temperature dependence of alpha. Such a source would require a direct dependence on electron temperature. A possible candidate is associative recombination of energetic N(D-2) with O. The results confirm recent measurements which find that this process cannot be significant. The NO(+) chemistry is a very sensitive indicator of chemical equilibrium conditions. By using measurements of the relevant parameters made in the polar ionization hole it is found that horizontal drifts do not appear to be significant in this region.

Torr, M. R.↗
NASA NTRS1979

Observations of warm plasma in the dayside plasma trough at geosynchronous orbit

Positive ions in the energy range E = 3-50 eV have been measured on the dayside at geosynchronous orbit with the University of California at San Diego auroral particles experiment on ATS 6. It is found that the near-equatorial plasma trough contains a warm plasma component with a relatively stable temperature 11 eV and a low 'isotropic component' of density typically in the range 0.1-0.4 ion/cc. The pitch angle distributions of these warm ions are typically field-aligned, indicating an ionospheric origin, and have pitch angle half widths in the range 20-40 deg. Pancake and conical distributions are also observed. Abrupt enhancements of the plasma density to 1-10 ions/cc, or more, are seen in the late afternoon and last from several minutes to a few hours.

Horwitz, J. L.↗