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At least 1,315 records · Page 73

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NASA NTRS1984

Interplanetary flow systems associated with cosmic ray modulation in 1977-1980

The hydromagnetic flow configurations associated with the cosmic ray modulation in 1977-1980 were determined using solar wind plasma and magnetic field data from Voyager 1 and 2 and Helios 1. The modulation was related to two types of large-scale systems of flows: one containing a number of transients such as shocks and postshock flows, the other consisting primarily of a series of quasi-stationary flows following interaction regions containing a stream interface and often bounded by a forward-reverse shock pair. Each of three major episodes of cosmic ray modulation was associated with the passage of a system of transient flows. Plateaus in the cosmic ray intensity-time profile were associated with the passage of systems of corotating streams.

Burlaga, L. F.↗

NASA NTRS1984

Development and testing of a rural credit supervision system at the level of counties and rural properties utilizing remote sensing techniqes

Remote sensing techniques for supporting the rural credit supervision system were developed and tested. The test area comprised the counties of Aracatuba and Guararapes, located in the State of Sao Paulo. Aerial photography, LANDSAT images and topographic charts were used. Aerial photographs were extremely useful for the out lining of properties boundaries with financing of sugarcane plantations by the Banco do Brasil S.A.. The percentage of correctly interpreted sugarcane on LANDSAT images, considering the 85 analyzed properties, was of 63.12%. The occurrence of atypical conditions such as excessive raining, sugarcane in bloom, and wind damaged sugarcane and sugarcane not harvested due to planning failures verified during the period the images were obtained, were some of the contributing factors associated with a low interpretation performance. An alternative approach was developed using several LANDSAT overpasses and auxiliary field data, which resulted in 91.77 percent correct.

Batista, G. T.↗

NASA NTRS1984

Shuttle Experimental Radar for Geological Exploration (SERGE) project: Field work relating to the Shuttle Experimental Radar A (SIR-A) in Brazil (phase 2)

The ground observations undertaken over the northern position of Minas Gerais State, and part of Distrito Federal from 7 to 12 December 1982, along the Space Shuttle 2 flying orbit 22 of November 1981 are described. Field data related mostly with lithology, geological structures and forest cover, and specific geomorphological and pedological aspects were collected. Ground data are applied to evaluate the SIR-A Experiment, developed in the Space Shuttle-2 mission for natural resources mapping and prospecting.

Balieiro, M. G.↗

NASA NTRS1985

Development of large, horizontal-axis wind turbines

A program to develop large, horizontal-axis wind turbines is discussed. The program is directed toward developing the technology for safe, reliable, environmentally acceptable large wind turbines that can generate a significant amount of electricity at costs competitive with those of conventional electricity-generating systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Several ongoing projects in large-wind-turbine development are directed toward meeting the technology requirements for utility applications. The machines based on first-generation technology (Mod-OA and Mod-1) successfully completed their planned periods of experimental operation in June, 1982. The second-generation machines (Mod-2) are in operation at selected utility sites. A third-generation machine (Mod-5) is under contract. Erection and initial operation of the Mod-5 in Hawaii should take place in 1986. Each successive generation of technology increased reliability and energy capture while reducing the cost of electricity. These advances are being made by gaining a better understanding of the system-design drivers, improving the analytical design tools, verifying design methods with operating field data, and incorporating new technology and innovative designs. Information is given on the results from the first- and second-generation machines (Mod-OA, - 1, and -2), the status of the Department of Interior, and the status of the third-generation wind turbine (Mod-5).

Baldwin, D. H.↗

NASA NTRS1985

The Introduction of New Cockpit Technology: A Human Factors Study

A joint Airline/NASA field study of B-767 training and operations was conducted during the period this aircraft was being introduced into line service. The objectives of the study were: (1) to identify any adverse reactions to the new technology; (2) to provide a clearing house of information for the airlines and pilots during the introductory period; (3) to provide feedback on airline training programs for the new aircraft; and (4) to provide field data to NASA and other researchers to help them develop principles of human interaction with automated systems. It is concluded that: (1) a large majority of pilots enjoy flying the B-767 more than the older aircraft; (2) pilots accept new cockpit technology and find it useful; (3) pilots are aware of the potential loss of flying skills because of automation, and take steps to prevent this from happening; (4) autopilot/autothrottle interactions and FMS operations were sometimes confusing or surprising to pilots, and they desired more training in this area; and (5) highly automated cockpits can result in a loss of effective monitoring performance.

Curry, R. E.↗

NASA NTRS1985

Incident beam polarization for laser Doppler velocimetry employing a sapphire cylindrical window

For laser Doppler velocimetry studies employing sapphire windows as optical access ports, the birefringency of sapphire produces an extra beam intersection volume which serves to effectively smear the acquired velocity flow field data. It is shown that for a cylindrical window geometry, the extra beam intersection volume may be eliminated with minimal decrease in the fringe visibility of the remaining intersection volume by suitably orienting the polarizations of the initial laser beams. For horizontally incident beams, these polarizations were measured at three intersection locations within the cylinder. It was found that the measured polarization angles agreed with the theoretical predictions.

Lock, J. A.↗

NASA NTRS1985

A three-dimensional turbulent separated flow and related mesurements

The applicability of and the limits on the applicability of 11 near wall similarity laws characterizing three-dimensional turbulent boundary layer flows were determined. A direct force sensing local wall shear stress meter was used in both pressure-driven and shear-driven three-dimensional turbulent boundary layers, together with extensive mean velocity field and wall pressure field data. This resulted in a relatively large number of graphical comparisons of the predictive ability of 10 of these 11 similarity models relative to measured data over a wide range of flow conditions. Documentation of a complex, separated three-dimensional turbulent flow as a standard test case for evaluating the predictive ability of numerical codes solving such flows is presented.

Pierce, F. J.↗

NASA NTRS1985

Improving the geological interpretation of magnetic and gravity satellite anomalies

Current limitations in the quantitative interpretation of satellite-elevation geopotential field data and magnetic anomaly data were investigated along with techniques to overcome them. A major result was the preparation of an improved scalar magnetic anomaly map of South America and adjacent marine areas directly from the original MAGSAT data. In addition, comparisons of South American and Euro-African data show a strong correlation of anomalies along the Atlantic rifted margins of the continents.

Hinze, W. J.↗

NASA NTRS1985

Low energy proton bidirectional anisotropies and their relation to transient interplanetary magnetic structures: ISEE-3 observations

It is known that the interplanetary medium in the period approaching solar maximum is characterized by an enhancement in the occurrence of transient solar wind streams and shocks and that such systems are often associated with looplike magnetic structures or clouds. There is observational evidence that bidirectional, field aligned flows of low energy particles could be a signature of such looplike structures, although detailed models for the magnetic field configuration and injection mechanisms do not exist at the current time. Preliminary results of a survey of low energy proton bidirectional anisotropies measured on ISEE-3 in the interplanetary medium between August 1978 and May 1982, together with magnetic field data from the same spacecraft are presented.

Marsden, R. G.↗

NASA NTRS1984

A high performance magnetoplasmadynamic thruster

A flared-anode MPD thruster has been modified to permit injection of propellant through the backplate near the anode wall. At 6 g/sec argon, this thruster displays an onset current of 41.4 kA, almost double the value observed for propellant injection at the cathode and intermediate radial positions. A magnetic field survey of the interelectrode region shows current density is highest at the upstream and downstream ends of the chamber. The operating efficiency at onset current inferred from magnetic field data exceeds 50 percent, but swinging-gate thrust stand measurements reveal a progressive divergence between inferred and actual thrust with increasing power. Near onset, the measured thrust is approximately 20 percent lower than that inferred from magnetic probing. Explanations for this behavior have been explored with viscous drag emerging as the most probable cause of performance degradation.

Wolff, M.↗

NASA NTRS1985

Interplanetary magnetic field enhancements in the solar wind Statistical properties at 1 AU

The present investigation is concerned with interplanetary magnetic field (IMF) enhancements which do not resemble any of the previously reported amplifications in the IMF. The magnetic field enhacements observed increase slowly at first and then more rapidly to a peak followed by a symmetrical decay. Interplanetary magnetic field enhacement observed by ISEE-3 on various dates are considered, giving attention to observations on June 5, 1979; September 8-9, 1980; February 5, 1981; and June 14-15, 1981. Interplanetary magnetic field enhancement observed with the aid of IMP-8 are also considered. A total of 45 events is found in surveying a 9-year period of magnetic field data.

Arghavani, M. R.↗

NASA NTRS1985

Incident beam polarization for laser Doppler velocimetry employing a sapphire cylindrical window

Lock, J. A.↗

NASA NTRS1984

Substorm electric fields in the earth's magnetotail

A survey has been made of all the electric field data from the University of California, Berkeley, double probe experiment on ISEE-1 (apogee approximately 22 earth radii) during 1980 when the satellite was in the magnetotail. This study was restricted to the 74 events where E cross B flows could be calculated and were equal to or greater than 100 km/s. Substorm times were determined by examining the Ae index for peaks equal to or greater than 250 gamma. In association with substorms, approximately 70 percent of the flows were earthward, and approximately 20 percent had a signature called 'near satellite reconnection' (first described by Nishida et al. (1983) of tailward flow followed by earthward flow which can be interpreted in terms of a model where the x-line forms earthward of the satellite and subsequently propagates tailward of X(GSM) = -21 earth radii and within the absolute value of Y(GSM) equal to or less than 4.5 earth radii. These data suggest that the near earth x-line usually forms tailward of X(GSM) approximately -20 earth radii.

Cattell, C. A.↗

NASA NTRS1985

Magnetic field properties of Jupiter's tail at distances from 80 to 7500 Jovian radii

The results of a detailed study of the magnetic field data on the near and distant Jovian magnetotail from both Voyager 1 and 2 are presented. The spacecraft trajectories and the data are reviewed, and four distant tail encounters are examined and compared with the corresponding Voyager 1 interplanetary data sets. A power spectral analysis of both the near and distant tail intervals is given, and some of the differences between the tail encounters and the power spectra of these control data sets are discussed. Two solar wind or magnetosheath data sets obtained when Voyager 2 was not in the distant tail are analyzed. These more 'normal' solar wind conditions are contrasted with those reflected in both the Voyager 2 distant tail encounters and the conditions monitored by Voyager 1 farther downstream.

Goldstein, M. L.↗

NASA NTRS1985

Structural Mapping of Folded Sedimentary Environments from Satellite Images: an Example from Central Asia

In the Tadjik Depression, in Soviet Central Asia, in the absence of existing geologic or topographic maps, an enhanced LANDSAT multispectral scanner image was used in combination with field data to produce a 1:250000 geologic map of the Vakhsh fold-and-thrust belt and adjacent autochthon. Several structural conclusions are reached as a result of this mapping. Deformation of the Cretaceous and Tertiary strata of the fold-and-thrust belt is, in the central Tadjik Depression, conspicuously absent north of a buried basement fault that marks the hinge-zone of the Late Mesozoic passive margin. But, in the eastern half of the depression, thrusting has moved coherent sheets northward, over the block fault, these sheets now lie flat atop the autochthon to the north. The crustal structure inherited from the Mesozoic extensional phase has strongly influenced the Late Cenozoic pattern of deformation, producing the fold-and-thrust belt that is markedly asymmetric. The development of the thrust system has included the progressive overlapping of thrust: the later thrusts apparently formed internal to the older thrusts, and subsequently overrode them.

Leith, W.↗

NASA NTRS1986

Extensions of the concept of suction analogy to prediction of vortex lift effect

Flow field data for a double delta wing at low speed were used to determine the location of a vortex action point. The result was found to be consistent with what was determined for a delta wing. In supersonic flow, the action point location was determined empirically. For a wing with rounded leading edges, an assumption for initial vortex separation was shown to be equivalent to initial leading edge bubble separation for airfoils. A theoretical formulation by the section analogy to determine the delayed vortex separation on a cambered wing with rounded leading edges was presented. The method of suction analogy was further shown to be applicable to predicting the body vortex lift.

Lan, C. E.↗

NASA NTRS1986

Department of Geology/NASA-GSFC geobotanical investigation

Geobotanical mapping in the southern Appalachians and soil metal associated changes in vegatation spectral responses in the reflective and emissive portions of the electromagnetic spectrum (EMS) is studied. It is determined whether deciduous forest vegetation reflection and emission characteristics show detectable changes that can be related to residual soil characteristics. Analyses of such related characteristics enhances the ability to discriminate underlying lithologies as well as variances within lithologies associated with natural heavy metal occurences. An understanding is developed of the factors which contribute to the differing spectral signatures of various lithology/soil types. A combination of field data and remote spectral analysis is studied.

Source record↗

NASA NTRS1985

Evaluation of EHD film thickness for cryogenic fluids

Some aerospace rocket engine applications require that bearings operate at high speeds with cryogenic rocket fuel as the only liquid lubricant. Analyses and field data on these bearings indicate that life would be limited to a few minutes if they operated unlubricated. The extent to which cryogenic fluids are capable of generating elastohydrodynamic films is, therefore, an area of concern and is investigated in this paper. Results from experimental and analytical work at the authors' laboratories indicate sufficient films are not generated to lubricate the bearing reliably. This conclusion is supported by experimental data and analysis which show liquid nitrogen, the cryogenic fluid tested, to be isoviscous.

Merriman, T. L.↗