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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 523 records · Page 29

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NASA NTRS1985

Aeronautical facilities catalogue. Volume 2: Airbreathing propulsion and flight simulators

Volume two of the facilities catalogue deals with Airbreathing Propulsion and Flight Simulation Facilities. Data pertinent to managers and engineers are presented. Each facility is described on a data sheet that shows the facility's technical parameters on a chart and more detailed information in narratives. Facilities judged comparable in testing capability are noted and grouped together. Several comprehensive cross-indexes and charts are included.

Penaranda, F. E.↗

NASA NTRS1986

Avionics electromagnetic interference immunity and environment

Aircraft electromagnetic spectrum and radio frequency (RF) field strengths are charted, profiling the higher levels of electromagnetic voltages encountered by the commercial aircraft wiring. Selected military, urban, and rural electromagnetic field levels are plotted and provide a comparison of radiation amplitudes. Low frequency magnetic fields and electric fields from 400 H(Z) power systems are charted versus frequency and wire separation to indicate induced voltages on adjacent or neighboring circuits. Induced EMI levels and attenuation characteristics of electric, magnetic, RF fields, and transients are plotted and graphed for common types of wire circuits. The significance of wire circuit returns and shielding is emphasized to highlight the techniques that help block the paths of electromagnetic interference and maintain avionic interface signal quality.

Clarke, C. A.↗

NASA NTRS1987

Large-scale structure of the sun's corona from radio observations using the Clark Lake Radioheliograph

Meterwave maps of the solar corona made with the Clark Lake Radioheliograph at 30.9, 50, and 73.8 MHz for one solar rotation are presented. They are compared and contrasted with optical data: 10,830 A maps, white-light coronagraph images (SOLWIND and Mauna Loa K coronameter), and forbidden line scans. Most of the sources in the radio maps persist for two days or more, and appear to rotate approximately with the solar rate. A coronal hole seen against the disk at all three frequencies shows interesting similarities and significant differences with the optical signatures of the hole. Elongated features of the 50 MHz corona correspond rather well to the azimuthal position of white light streamers seen in SOLWIND images. Synoptic charts made from the radio maps show overall similarities to synoptic charts constructed from (limb) coronagraph data. Some of the differences may result from the different weightings given by the radio and optical data to density and temperature, or by the different sensitivities to nonradial geometries. It is shown that the combined use of meter wave and optical images provides considerable new insights into the three-dimensional structure of the low to middle corona.

Kundu, M. R.↗

NASA NTRS1987

Radio studies of large scale structures of the Sun's corona and transient activity

The use of meter-decimeter wavelength imaging observations for four different kinds of studies of solar coronal activity is discussed. (1) Large scale structure of the upper corona; daily imaging observations permit comparison of radio images with white light images from space and ground observation, generation of synoptic charts similar to white light coronagraph synoptic charts, and comparison of radio brightness enhancements and deficiencies with bright coronal streamers and coronal holes. (2) Relative positions of type III burst sources and coronal streamers as observed by Solwind experiment on the P-78-1 satellite and by the HAO C/P experiment aboard the SMM; infer the paths of type III emitting electrons in dense coronal streamers, and from multifrequency observations derive electron density distributions above active regions near the limb. (3) Non-flare associated type II/type IV bursts associated with coronal streamer disruption events; such type IV sources have a rather slow velocity (approx = to or less than 100 km/s) CMEs. (4) Meter-decimeter microbursts; these are short duration (2-10 sec) weak-type III-like bursts, produced at the fundamental plasma frequency by plasma radiation processes which have important differences from the standard mechanisms used to explain the strong type III bursts.

Kundu, Mukul R.↗

NASA NTRS1987

Northwest Airlines flight experiments

An experiment was conducted in which real-time Total Ozone Mapping Spectrometer (TOMS) data was compared with Northwest Airlines upper air charts. It was demonstrated that the regions of steep gradient in total ozone corresponded with fronts in the upper troposphere, specifically breaks in the tropopause associated with jet streams. Other small scale structures in the ozone could be related to minor trough and ridge lines. This suggests that the relation between total ozone and tropopause height might apply even on relatively small scales, and an analysis produced high correlation coefficients provided that the air mass origin was considered. In a second test, cabin ozone mixing at 37,000 ft. varied from less than 100 ppb (300 DU total ozone) to greater than 300 ppb in a trough (400 DU total ozone). A third analysis showed that clear air turbulence was located where upper air fronts were in rapid motion as suggested by comparison of the 1200 UT synoptic charts and the ozone map taken about six hours later.

Krueger, Arlin J.↗

NASA NTRS1989

Dynamic loading of spur gears with linear or parabolic tooth profile modification

A computer simulation was conducted to investigate the effects of both linear and parabolic tooth profile modification on the dynamic response of low-contact-ratio spur gears. The effect of the total amount of modification and the length of the modification zone were studied at various loads and speeds to find the optimal profile modification for minimal dynamic loading. Design charts consisting of normalized maximum dynamic load curves were generated for gear systems operated at various loads and with different tooth profile modification. An optimum profile modification can be determined from these design charts to minimize the dynamic loads of spur gear systems.

Lin, Hsiang Hsi↗

NASA NTRS1988

Dexterity analysis and robot hand design

Understanding about a dexterous robot hand's motion ranges is important to the precision grasping and precision manipulation. A planar robot hand is studied for object orientation, including ranges of motion, measures with respect to the palm, position reaching of a point in the grasped object, and rotation of the object about the reference point. The rotational dexterity index and dexterity chart are introduced and an analysis procedure is developed for calculating these quantities. A design procedure for determining the hand kinematic parameters based on a desired partial or complete dexterity chart is also developed. These procedures have been tested in detail for a planar robot hand with two 2- or 3-link fingers. The derived results are shown to be useful to performance evaluation, kinematic parameter design, and grasping motion planning for a planar robot hand.

Li, LU↗

NASA NTRS1989

Common Graphics Library (CGL). Volume 2: Low-level user's guide

The intent is to instruct the users of the Low-Level routines of the Common Graphics Library (CGL). The Low-Level routines form an application-independent graphics package enabling the user community to construct and design scientific charts conforming to the publication and/or viewgraph process. The Low-Level routines allow the user to design unique or unusual report-quality charts from a set of graphics utilities. The features of these routines can be used stand-alone or in conjunction with other packages to enhance or augment their capabilities. This library is written in ANSI FORTRAN 77, and currently uses a CORE-based underlying graphics package, and is therefore machine-independent, providing support for centralized and/or distributed computer systems.

Taylor, Nancy L.↗

NASA NTRS1990

Computer-aided design of high-contact-ratio gears for minimum dynamic load and stress

A computer aided design procedure is presented for minimizing dynamic effects on high contact ratio gears by modification of the tooth profile. Both linear and parabolic tooth profile modifications of high contact ratio gears under various loading conditions are examined and compared. The effects of the total amount of modification and the length of the modification zone were systematically studied at various loads and speeds to find the optimum profile design for minimizing the dynamic load and the tooth bending stress. Parabolic profile modification is preferred over linear profile modification for high contact ratio gears because of its lower sensitivity to manufacturing errors. For parabolic modification, a greater amount of modification at the tooth tip and a longer modification zone are required. Design charts are presented for high contact ratio gears with various profile modifications operating under a range of loads. A procedure is illustrated for using the charts to find the optimum profile design.

Lin, Hsiang Hsi↗

NASA NTRS1989

Dynamic loading of spur gears with linear or parabolic tooth profile modifications

Lin, H. H.↗

NASA NTRS1989

Echo asymmetry and its impact on NEXRAD storm identification

The effects of echo shape and radar viewing angle on the detections of cells are investigated. A chart representing the probability of detection of a storm is derived. Case studies from Florida and Alabama are analyzed in order to assess the performance of NEXRAD. It is noted that the current thresholds for storm identification for NEXRAD are inadequate for identifying small lightning-producing storms. Time-history and radar-reflectivity charts for the storms are provided.

Buechler, Dennis E.↗

NASA NTRS1991

The space exploration initiative

A number of view graph charts are presented which outline the presentation. Outlined are reasons for going to Mars, why it is necessary to go to the Moon first, and the presidential decision on the space exploration initiative. Other representative charts are entitled: Lunar transportation system requirement drivers; Mars transportation system requirement drivers; National space policy goals; Exploration hardware needed; Mars mission profile; Science on the Moon and Mars; and Two independent reviews.

Priest, Pete↗

NASA NTRS1990

Five basic steps to problem trending

Five basic steps to problem trending evolved from experience in trending problems on Space Shuttle hardware are discussed: extracting data; constructing a Pareto chart of all failure modes; constructing normalized subsystem, component, and failure-mode trend charts; identifying trend direction; and providing a summary assessment. The five-step method has been useful for identifying failure modes of concern, evaluating the effectiveness of corrective actions, and determining funding allocation.

Bombara, Elwood L.↗

NASA NTRS1992

Buckling behavior of long symmetrically laminated plates subjected to combined loadings

A parametric study is presented of the buckling behavior of infinitely long, symmetrically laminated anisotropic plates subjected to combined loadings. The loading conditions considered are axial tension and compression transverse tension and compression, and shear. Results obtained using a special-purpose analysis, well-suited for parametric studies, are presented for clamped and simply supported plates. Moreover, results are presented for some common laminate constructions, and generic buckling design charts are presented for a wide range of parameters. The generic design charts are presented in terms of useful nondimensional parameters, and the dependence of the nondimensional parameters on laminate fiber orientation, stacking sequence, and material properties is discussed. An important finding of the study is that the effects of anisotropy are much more pronounced in shear-loaded plates than in compression-loaded plates. In addition, the effects of anisotropy on plates subjected to combined loadings are generally manifested as a phase shift of self-similar buckling interaction curves. A practical application of this phase shift is that the buckling resistance of long plates can be improved by applying a shear loading with a specific orientation. In all cases considered in the study, the buckling coefficients of infinitely long plates are found to be independent of the bending stiffness ratio (D sub 11/D sub 22)(1/4).

Nemeth, Michael P.↗

NASA NTRS1992

Triton stellar occultation candidates - 1992-1994

A search for Triton stellar occultation candidates for the period 1992-1994 has been completed with CCD strip-scanning observations. The search reached an R magnitude of about 17.4 and found 129 candidates within 1.5 arcsec of Triton's ephemeris during this period. Of these events, around 30 occultations are expected to be visible from the earth, indicating that a number of Triton occultation events should be visible from major observatories. Even the faintest of the present candidate events could produce useful occultation data if observed with a large enough telescope. The present astrometric accuracy is inadequate to identify which of these appulse events will produce occultations on the earth; further astrometry is needed to refine the predictions for positive occultation identification. To aid in selecting candidates for additional astrometric and photometric studies, finder charts and earth-based visibility charts for each event are included.

Mcdonald, S. W.↗

NASA NTRS1992

Flight-test guidance for airbreathing hypersonic vehicles

A guidance solution for aerospace planes is given based on a family of energy-heading extremal solutions that can be used for feedback implementations. Test conditions are developed as steady-cruise solutions by means of energy-heading extremal solutions to a time/fuel-range flight-optimization problem. Feedback charts are derived that give control as a function of energy and heading-to-go, and the reduced-order model is compared to numerically optimized point-mass solutions for flight optimization. The energy-heading model is shown to provide feedback-control charts that yield fuel-efficient turn/acceleration maneuvers with significant weight-change as compared to the point-mass solutions. Such variables as Mach number, dynamic pressure, and lift are found to influence the solutions significantly.

Cliff, Eugene M.↗

NASA NTRS1993

Measuring Inhomogeneities In Thermocouple Wires

Spools rotated to pull thermocouple wires through liquid nitrogen, while output voltage of thermocouple recorded on strip chart. Wires exposed to severe temperature gradients, amounting to overall change of 200 degrees C, where they enter and leave liquid nitrogen. If wires homogeneous, net output voltage zero. If inhomogeneity passes through liquid-nitrogen/air interface, resulting deviation of output voltage from zero seen immediately on strip chart. If inhomogeneity greater than allowable, reels stopped temporarily so inhomogeneity tagged before wound onto takeup reel.

Burkett, Cecil G., Jr.↗

NASA NTRS1992

OAST space research and technology applications: Technology transfer successes

The ultimate measure of success in the Space Research and Technology Program is the incorporation of a technology into an operational mission. Charts are presented that describe technology products which OAST has helped support that (1) have been used in a space mission, (2) have been incorporated into the baseline design of a flight system in the development phase, or (3) have been picked up by a commercial or other non-NASA user. We hope that these examples will demonstrate the value of investment in technology. Pictured on the charts are illustrations of the technology product, the mission or user which has incorporated the technology, and where appropriate, results from the mission itself.

Reck, Gregory M.↗