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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 1,315 records · Page 73
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Compressional environment in the location and orientation of planetary dorsa and terrestrial earthquake fault structures

Lunar mare ridges are not pure compressional ridges but their locations and orientations are most likely controlled by shear zones as seen from their Riedel-shear-like arrangements. On the Moon the crustal shortening has mostly taken place within mare areas but some young terra ridges are also to be seen indicating some crustal shortening also outside mare areas. This shortening has, however, not reached the same intensity as in the case of lobate scarp overthrusts on Mercury.

Raitala, J.↗
NASA NTRS1985

Does orientation affect the smoothness of parsec-scale radio jets?

The compact, nonthermal radio sources which are studied with very-long-baseline interferometry (VLBI) are often found to have a linear structure with a bright, nearly unresolved component at one end. This asymmetric structure is usually referred to as a 'core-jet' morphology. In some sources there are bright bumps or knots - regions of enhanced radio emission - along the 'jets', while other sources have relatively smooth, featureless jets. This paper reports the result of a study of the differences between compact radio sources with bumpy and smooth jets. It is concluded that most, if not all, of the difference in jet smoothness can be attributed to the orientation of the radio axis with respect to the line of sight. Thus, the VLBI observations do not necessarily imply that there are intrinsic differences in the smoothness of parsec-scale radio jets.

Jones, D. L.↗
NASA NTRS1985

Orientations of AM Her stars from their polarization properties - The case of the missing AM Her stars

Observation of the polarization properties of the AM Her stars is used to determine their orientations. It is found that the AM Her stars are randomly distributed with respect to their inclination angle i but not with respect to their magnetic colatitude delta. The stars are concentrated along the semicircle cos-squared delta + cos-squared i = 1, where delta is the angle between the magnetic moment and the spin axis of the degenerate dwarf. This result implies that the discovery of AM Her stars is strongly affected by observational selection effects. It is suggested that these effects are a result of the way in which the AM Her stars have been identified observationally, and of the angular properties of high harmonic cyclotron emission. It is estimated that there are about three times as many AM Her stars as have been found so far.

Brainerd, J. J.↗
NASA NTRS1985

Mission-oriented requirements for updating MIL-H-8501: Calspan proposed structure and rationale

This report documents the effort by Arvin/Calspan Corporation to formulate a revision of MIL-H-8501A in terms of Mission-Oriented Flying Qualities Requirements for Military Rotorcraft. Emphasis is placed on development of a specification structure which will permit addressing Operational Missions and Flight Phases, Flight Regions, Classification of Required Operational Capability, Categorization of Flight Phases, and Levels of Flying Qualities. A number of definitions is established to permit addressing the rotorcraft state, flight envelopes, environments, and the conditions under which degraded flying qualities are permitted. Tentative requirements are drafted for Required Operational Capability Class 1. Also included is a Background Information and Users Guide for the draft specification structure proposed for the MIL-H-8501A revision. The report also contains a discussion of critical data gaps and attempts to prioritize these data gaps and to suggest experiments that should be performed to generate data needed to support formulation of quantitative design criteria for the additional Operational Capability Classes 2, 3, and 4.

Chalk, C. R.↗
NASA NTRS1985

The mission oriented terminal area simulation facility

The Mission Oriented Terminal Area Simulation (MOTAS) was developed to provide an ATC environment in which flight management and flight operations research studies can be conducted with a high degree of realism. This facility provides a flexible and comprehensive simulation of the airborne, ground-based and communication aspects of the airport terminal area environment. Major elements of the simulation are: an airport terminal area environment model, two air traffic controller stations, several aircraft models and simulator cockpits, four pseudo pilot stations, and a realistic air-ground communications network. MOTAS has been used for one study with the DC-9 simulator and a series of data link studies are planned in the near future.

Kaylor, J. T.↗
NASA NTRS1986

Effects of thickness and ply orientation on buckling of laminated plates

The buckling loads of laminated plates are predicted using a new theory which takes into account transverse shearing effects. This new theory assumes trigonometric terms through-the-thickness in the displacements to take into account transverse shearing effects in thick plates. Buckling loads predicted by the new theory and by traditional theories are compared for isotropic and laminated plates. The effect of ply orientation on the buckling loads predicted by each theory is demonstrated.

Jegley, D. C.↗
NASA NTRS1985

MAP-oriented research in the People's Republic of China

A brief accounting of MAP oriented research in the Republic of China is given. A stratosphere balloon launching facility and its capabilities are reviewed. Observations of the stratospheric aerosols with a balloon-borne aerosol computer were made. Long term monitoring of stratospheric aerosols induced by volcanic eruptions are made with a ruby lidar. The main parameters of an ST radar system are given. The ionospheric D region is investigated with the method of ionospheric absorption. And photochemical modeling and radiation parameterization of the middle atmosphere are made.

Lu, D.↗
NASA NTRS1986

Reconfiguration algorithms for tree architectures using sub-tree oriented fault tolerance

An approach to reconfiguration in tree architectures has been developed in which redundant processors are allocated at the leaves. The scheme is called sub-tree oriented fault tolerances (SOFT) and is capable of tolerating both link failures as well as multiple processor failures. In this paper, the SOFT scheme is examined from the perspective of reconfigurability. Specific algorithms are presented for reconfiguration.

Lowrie, M. B.↗
NASA NTRS1985

Assisting extrasolar planetary detection through the determination of stellar space orientations

Various methods outlined for indirect planetary detection would greatly benefit (in some cases require) the determination of the planetary orbital plane, which is theoretically equivalent to the stellar equatorial plane. Determining the stellar space orientation, therefore, would greatly benefit extrasolar planetary detection. Stellar rotation periods determined from short-term variations in Ca II H and K sunspot emission are utilized together with both stellar radii measurements and Doppler-broadened spectral line profiles to get the stellar inclination to the line of sight. The clocklike on-the-plane-of-the-sky component determination utilizes the concentration of sunspot-associated plage areas at central stellar latitudes when viewed in Ca II H or K emission. One can perform Ca II H and K emission speckle interferometry to measure the clocklike angle of this stellar Ca II H and K emission band, modeling it as an elliptical intensity distribution. Both components should be determinable to within 10 deg for at least the resolvable fifth magnitude stars.

Doyle, L. R.↗
NASA NTRS1986

Design for a goal-oriented telerobotic system

Robotic systems will play an increasingly important role in space operations. This paper describes the objective and design of a proposed goal-oriented telerobotic system for space operations. This design effort encompasses the elements of the system executive and user interface, and the distribution and general structure of the knowledge bases, the displays, and the task sequencing. The objective of the design effort is to provide an evolutionary structure for a telerobotic system, i.e., one that can progress from strictly teleoperated through phases of serving as an assistant, a colleague, and an expert, to eventually serve as a truly autonomous unit, requiring only minimal supervision. A preliminary design for such a system involving 'mixed initiative', or the flexible shared control between the human operator and the software system, is complete and described in this paper.

Will, R. W.↗
NASA NTRS1986

Pole orientation, sidereal period, and sense of rotation of asteroids

Pole orientations of asteroids were determined. The method, called photometric astrometry, takes precise epochs of lightcurves into account. Pole determination research on asteroids 532 Herculina, 45 Eugenia, and 3 Juno continues. Discrepancies between various pole determination techniques presently being used are analyzed. The study of asteroid shapes and creating a generalized master pole determination technique also continues which will incorporate the best features of several current methods.

Taylor, R. C.↗
NASA NTRS1986

Asteroid shapes and pole orientation from visual and infrared photometry

The shape and pole orientation of asteroid 16 Psyche was determined. New evidence supporting the shorter, five hour, period for 4 Vesta was presented. The first mutual eclipse event between Pluto and Charon was detected. The organization of an international campaign to obtain lightcurves and other data on the Pluto-Charon mutual events was started.

Tedesco, E. F.↗
NASA NTRS1987

Elevated temperature tension, compression and creep-rupture behavior of (001)-oriented single crystal superalloy PWA 1480

Tensile and compressive flow behavior at various temperatures and strain rates, and tensile creep rupture behavior at 850 and 1050 C and various stresses were studied for (001)-oriented single crystals of the Ni-base superalloy PWA 1480. At temperatures up to 760 C, the flow stress is insensitive to strain rate and of greater magnitude in tension than in compression. At temperatures of 800 C and above, the flow stress decreases continuously with decreasing strain rate and the tension/compression anisotropy diminishes. The second stage creep rate and rupture time exhibited power law relationships with the applied stress for both 850 and 1050 C, however with different stress dependencies. The stress exponent for the steady state creep rate was about 7 at 1050 C, but much higher at 850 C, about 12. Directional coarsening of the gamma' phase occurred during creep at 1050 C, but not at 850 C.

Hebsur, Mohan G.↗
NASA NTRS1987

Reconfigurable tree architectures using subtree oriented fault tolerance

An approach to the design of reconfigurable tree architecture is presented in which spare processors are allocated at the leaves. The approach is unique in that spares are associated with subtrees and sharing of spares between these subtrees can occur. The Subtree Oriented Fault Tolerance (SOFT) approach is more reliable than previous approaches capable of tolerating link and switch failures for both single chip and multichip tree implementations while reducing redundancy in terms of both spare processors and links. VLSI layout is 0(n) for binary trees and is directly extensible to N-ary trees and fault tolerance through performance degradation.

Lowrie, Matthew B.↗
NASA NTRS1986

The poleward edge of the mid-latitude trough - Its formation, orientation and dynamics

Data from the Advanced Ionospheric Sounder (AIS) deployed at Halley, Antarctica (76-deg S, 27-deg W; L = 4.2) and the Dynamics Explorer-2 spacecraft (DE-2) are used to investigate several aspects of the formation processes and dynamics of the poleward edge of the midlatitude electron density trough. These include a study of the flux and energy of charged particles precipitating into the F-region as a function of Magnetic Local Time. It is found that local energetic electron precipitation is a major source of ionization of the poleward edge in the evening sector, but only after magnetic midnight transport processes become more important. Occasionally a significant increase in the flux of conjugate photoelectrons is colocated with the poleward edge of the trough in the morning sector. The combination of AIS and DE-2 data has allowed identification of significant longitudinal structure on the poleward edge of the trough that may be the result of substorm activity. It is found that the orientation of the poleward edge of the trough and the locus of the plasmapause predicted from the 'tear-drop' model vary in rather a similar manner with local time, though no close physical link between the two features is inferred from this coincidence.

Rodger, A. S.↗
NASA NTRS1987

Effects of transverse shear deformation on buckling of laminated cylinders as a function of thickness and ply orientation

Buckling loads of thick-walled, orthotropic, simply-supported right circular cylinders are predicted using a new higher-order transverse shear deformation theory. The higher-order theory shows that, by more accurately accounting for transverse shear deformation effects, the predicted buckling load may be reduced by as much as 80 percent compared to predictions based on conventional transverse shear deformation theory. A parametric study of the effect of ply orientation on the buckling load of axially compressed cylinders indicates that laminates containing 0 deg plies are the most sensitive to transverse shear deformation effects. Interaction curves for buckling of cylinders with axial compressive and external pressure loadings indicate that buckling loads due to external pressure loadings are much less sensitive to transverse shear deformation effects than those due to axial compressive loadings.

Jegley, Dawn C.↗
NASA NTRS1986

The atmospheric excitation of earth orientation changes during MERIT

Geodetic estimates of earth orientation variations detected during the MERIT campaign (September 1983-November 1984) are compared with corresponding meteorological data. The geodetic data were obtained using VLBI, lunar laser ranging, and satellite laser ranging and the meteorological data were from the NMC in the U.S. and the European Centre for Medium Range Weather Forecasting (ECMRWF) in the U.K. The effects of changes in pressure, wind, and the inverted barometer ocean response on the excitation of the polar motion and the length of day are examined. The comparison between the meteorological and geodetic data reveals that the equatorial vector component of the atmospheric angular momentum (AAM) has significant annual and semiannual variations. Good correlation is detected between the geodetic polar motion data and the NMC pressure inverted barometer data combined with the ECMRWF wind estimates and semiannual agreement with the NMC pressure data is observed. There is also good correlation between the ECMRWF and NMC polar vector component of the AAM data and the geodetic length of day estimates, and good semiannual agreement with NMC pressure data is noted.

Eubanks, T. M.↗
NASA NTRS1986

Amphibian egg cytoplasm response to altered g-forces and gravity orientation

Elucidation of dorsal/ventral polarity and primary embryonic axis development in amphibian embryos requires an understanding of cytoplasmic rearrangements in fertile eggs at the biophysical, physiological, and biochemical levels. Evidence is presented that amphibian egg cytoplasmic components are compartmentalized. The effects of altered orientation to the gravitational vector (i.e., egg inversion) and alterations in gravity force ranging from hypergravity (centrifugation) to simulated microgravity (i.e., horizontal clinostat rotation) on cytoplasmic compartment rearrangements are reviewed. The behavior of yolk compartments as well as a newly defined (with monoclonal antibody) nonyolk cytoplasmic compartment, in inverted eggs and in eggs rotated on horizontal clinostats at their buoyant density, is discussed.

Neff, A. W.↗