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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

An energetic particle perspective of the magnetopause

The present analysis deals with energetic (above 24 keV) particle data from the Isee satellites during a series of magnetopause crossings. The primary energetic particle data employed in the analysis are the three-dimensional distributions from the Isee A satellite. Correlative magnetic field measurements are used to relate the particle behavior to magnetic field characteristics at and earthward of the magnetopause. It is shown that, to first order, the magnetopause may be regarded as a perfectly absorbing boundary for the trapped energetic particles, that it is nearly always in motion, and that boundary waves are often present. The observed dayside magnetopause motion is consistent with a large-scale radial motion having an approximately 10-min period plus superimposed boundary waves with a 90- to 150-sec period.

Williams, D. J.↗
NASA NTRS1980

The Seasat microwave instruments in historical perspective

The R&D history of the four remote sensing instruments on Seasat: the scatterometer, radiometer, altimeter, and synthetic aperture radar (SAR) is reviewed. The characteristics and capabilities of each instrument are outlined. The successful performance of these instruments made possible the organization of a major new operational-demonstration satellite for the 1980s called NOSS (National Oceanic Satellite System).

Barrick, D. E.↗
NASA NTRS1980

The Einstein Observatory - New perspectives in astronomy

The impact of high-resolution, high-sensitivity X-ray measurements obtained by the Einstein Observatory (HEAO-2) on various areas of astronomical research is discussed. Following a review of the Einstein instruments based on grazing incidence focusing X-ray optics, including the telescope, imaging detectors and spectrometers, consideration is given to observations of X-ray emission from stellar systems, galaxies, and clusters of galaxies. Einstein results concerning the X-ray luminosities of young O, B and A stars and late K and M stars, the temperature, composition and distribution of material ejected in supernova explosions and comprising the interstellar medium, the formation and evolution of stellar systems and galaxies, the energy source of quasars and active galactic nuclei and the mass distribution in galactic clusters are indicated. Substantial progress made possible by the high-resolution observations of the diffuse X-ray background in cosmological research is also noted.

Giacconi, R.↗
NASA NTRS1980

Evaluation of a computer-generated perspective tunnel display for flight path following

The display was evaluated by monitoring pilot performance in a fixed base simulator with the vehicle dynamics of a CH-47 tandem rotor helicopter. Superposition of the predicted future vehicle position on the tunnel image was also investigated to determine whether, and to what extent, it contributes to better system performance (the best predicted future vehicle position was sought). Three types of simulator experiments were conducted: following a desired trajectory in the presence of disturbances; entering the trajectory from a random position, outside the trajectory; detecting and correcting failures in automatic flight. The tunnel display with superimposed predictor/director symbols was shown to be a very successful combination, which outperformed the other two displays in all three experiments. A prediction time of 4 to 7 sec. was found to optimize trajectory tracking for the given vehicle dynamics and flight condition. Pilot acceptance of the tunnel plus predictor/director display was found to be favorable and the time the pilot needed for familiarization with the display was found to be relatively short.

Grunwald, A. J.↗
NASA NTRS1980

Improvements to satellite retrieval systems. The operational perspective

Operational weather satellites are built as a series of nearly identical instruments which are flown for 5 to 7 years. Minor improvements are made during the life of the series. However, major improvements and changes in design are made with the initiation of a new series of instruments. Similarly, procedures used to process the data are characterized by frequent changes early in the life of a satellite series as user experience is gained with the new instrument. Later the changes become less frequent, both because the processing system becomes well tuned to that particular set of instruments and because, at the end of a series, resources are devoted to generating the processing system for the next set of instruments. Past and present systems are considered with emphasis on the vertical temperature profile radiometer and a procedure for deriving clear radiances in partly cloudy areas.

Mcmillin, L.↗
NASA NTRS1980

Deepening perspective: A new look at the old world

The development space satellites is examined with particular reference to their contributions to scientific research. The accomplishments in the fields of geodesy and the magnetosphere are reviewed in some detail.

Source record↗
NASA NTRS1981

Blade loss transient dynamics analysis, volume 1. Task 1: Survey and perspective

An analytical technique was developed to predict the behavior of a rotor system subjected to sudden unbalance. The technique is implemented in the Turbine Engine Transient Rotor Analysis (TETRA) computer program using the component element method. The analysis was particularly aimed toward blade-loss phenomena in gas turbine engines. A dual-rotor, casing, and pylon structure can be modeled by the computer program. Blade tip rubs, Coriolis forces, and mechanical clearances are included. The analytical system was verified by modeling and simulating actual test conditions for a rig test as well as a full-engine, blade-release demonstration.

Gallardo, V. C.↗
NASA NTRS1981

Performance deterioration: An airline perspective

Certain features of engine design and installation are clearly demonstrating important advantages in engine performance retention. Bearing arrangement no doubt has an important role in performance retention. Four bearings seem to be insufficient while six are probably more than are required. A well designed five-bearing system would seem to be an optimum configuration. Bearings with over-hung components such as fans, should be designed to minimize such over-hang to limit associated wobble, which in turn leads to shroud rub, or to allow closer running clearances. Almost any effort to improve stiffness and generally reduce flexing of the engine structure will pay off significantly in performance retention, even at a weight penalty. For this reason cowl load sharing to provide additional rigidity at a low cost in additional weight and complexity is favored.

Andersen, N. B.↗
NASA NTRS1981

An industrial perspective of the LANDSAT opportunity

The feasibility of enhancing LANDSAT products to provide the greatest usability low cost data possible can be determined through government sponsorship and finance of one or more task forces composed of a critical number of experts in multiple disciplines from many industries and academia. The synergism of multiple minds addressing singular problems without the creation of permanent or perpetual structures must yield output in the form of implementable specifications, even if presented as alternatives. Changes are needed within the spacecraft in order to account for Sun angle changes. The use of pointing accuracy to make geometric corrections (and possible radiometric corrections, is needed more than onboard data reduction and information extraction, which assume a proper knowledge of application and reduce potential utilization. Multilinear arrays need to be investigated and methods for sensor calibration and for determining the effects of atmospheric inversion, as well as the best way to back out the modulation transfer function must be determined.

Williams, B. F.↗
NASA NTRS1981

Perspectives on jet noise

Jet noise is a byproduct of turbulence. Until recently turbulence was assumed to be known statistically, and jet noise was computed therefrom. As a result of new findings though on the behavior of vortices and instability waves, a more integrated view of the problem has been accepted lately. After presenting a simple view of jet noise, the paper attempts to resolve the apparent differences between Lighthill's and Lilley's interpretations of mean-flow shear, and examines a number of ad hoc approaches to jet noise suppression.

Ribner, H. S.↗
NASA NTRS1981

Upper atmosphere of Jupiter - A post Voyager perspective

Some significant upper atmosphere features of Jupiter are discussed with reference to the Voyager observations of 1979. From the time of Pioneer observations in 1973-1974, the Jovian upper atmospheric temperature has increased by about 30%, the eddy diffusion coefficient at the homopause decreased by a factor of 100, the equatorial disk Lyman alpha intensity increased by a factor of 30, and the equatorial ionosphere became more extensive and showed diurnal variation. Important potential candidates for upper atmosphere energetics are thought to be the penetration of the magnetospheric soft electrons, Joule heating mechanism, and auroral electrons.

Atreya, S. K.↗
NASA NTRS1981

Evaluating a Scientific and Technical Information program - The user perspective

The project concerned with the evaluation of the Scientific and Technical Information (STI) program of the NASA Langley Research Center utilizes both survey research and system analysis techniques, includes all elements of the STI program, discloses the strengths and weaknesses of the STI program, and identifies ways in which the program could be modified to improve its overall efficiency and effectiveness. Phase I of the project employed survey research to assess the adequacy of the Langley STI program in meeting the information needs of Langley engineers and scientists. The results of the user survey provided information to aid management in choosing the services and processes which are likely to produce a high degree of user satisfaction and the most efficient use of resources.

Pinelli, T. E.↗
NASA NTRS1981

A Voyager attitude control perspective on fault tolerant systems

In current spacecraft design, a trend can be observed to achieve greater fault tolerance through the application of on-board software dedicated to detecting and isolating failures. Whether fault tolerance through software can meet the desired objectives depends on very careful consideration and control of the system in which the software is imbedded. The considered investigation has the objective to provide some of the insight needed for the required analysis of the system. A description is given of the techniques which have been developed in this connection during the development of the Voyager spacecraft. The Voyager Galileo Attitude and Articulation Control Subsystem (AACS) fault tolerant design is discussed to emphasize basic lessons learned from this experience. The central driver of hardware redundancy implementation on Voyager was known as the 'single point failure criterion'.

Rasmussen, R. D.↗
NASA NTRS1981

Tropospheric chemistry - A global perspective

Processes that affect the concentration of tropospheric OH are considered, taking into account linkages between the chemistry of OH and the chemistry of H, HO2, and H2O2. A review is presented of observational data of special relevance to OH, notably the distributions of CO, CH4, O3, H2O, HNO3, NO, and NO2. Most of the results presented in connection with the description of the model were obtained by solving time-dependent continuity equations. Rates for photolytic processes were allowed to vary diurnally with insolation. It is found that a well-calibrated and reliable model for OH places important constraints on global budgets for a variety of gases including CH4, H2, and CH3Cl in addition to CO. Accurate measurements of species such as CH3CCl3 can provide valuable checks on global models that must integrate over a variety of atmospheric conditions. However, emission rates for the relevant gases must be adequately quantified.

Logan, J. A.↗
NASA NTRS1981

The Space Shuttle in perspective

Commercial aspects of the Space Shuttle are examined, with attention given to charges to users, schedule of launches and reimbursement, kinds of payload and their selection, NASA authority, space allocation, and risk, liability, and insurance. It is concluded that insurance to reduce the risk, incentives that NASA is willing to make available to U.S. industry, and the demonstrated willingness of industry and the financial community to invest their funds in space ventures indicate that the new Shuttle capabilities will exponentially increase commercial activities in space during the 1980s.

Hosenball, S. N.↗
NASA NTRS1981

Technical Communication: Perspectives for the Eighties, Part 1. Proceedings of the Technical Communications Sessions at the 32Nd Annual Meeting of the Conference on College Composition and Communication

Proceeding of the technical communication sessions at the 32nd annual meeting of the Conference on College Composition and Communication held in Dallas, Texas, March 26-28, 1981 are summarized. The proceeding suggest that technical communication has become an important subfield and is becoming an intrinsic part of many undergraduate curricula. Technical communication as a separate discipline, however, is relatively new. For that reason, proceedings that can make current research available as quickly as possible are suggested for preparation. The following topics were addressed: (1) a history and definition of technical writing, (2) the case method is technical communication (3) teaching technical writing (4) oral communication and rhetorical theory, and (5) new approaches in and practical applications of technical writing.

Mathes, J. C.↗
NASA NTRS1981

Clinical report writing: Process and perspective

Clinical report writing in psychology and psychiatry is addressed. Audience/use analysis and the basic procedures of information gathering, diagnosis, and prognosis are described. Two interlinking processes are involved: the process of creation and the process of communication. Techniques for good report writing are presented.

Ewald, H. R.↗