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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

On the relation of J sub I to work done per unit uncracked area - Total, or component 'due to crack'

The J sub I relation, introduced by Rice (1968), expresses the work done on a quasiplanar specimen of specified width (or depth) for a fixed uniform crack length when the displacement of the load is increased from zero to some given value. The relation remains the same if the work done and its logarithmic derivative are calculated in terms of the component of the displacement that is 'due to the crack' rather than the total displacement. J sub I is studied as a function of displacement for a precracked, three-point-loaded bend specimen and also in the extremes of linear-elastic, and rigid/perfectly plastic behavior.

Srawley, J. E.↗
NASA NTRS1993

MIL-STDS and PTTI: What's available and what needs to be done

The systems developer who needs Precise Time and Time Interval (PTTI) capability has relatively little guidance in the form of military standards, particularly for systems using atomic clocks or other sources of very precise time and frequency. The existing standards, including MIL-STD-188-115, MIL-F-2991(EC), and DOD-STD-1399 are discussed. These documents were written several years ago and do not always reflect current practice or take advantage of more recent technology improvements. User needs have also changed over the years and some of those needs such as more detailed time codes are not being met. We will summarize what's available and what's good and bad about it. The second part will make suggestions about what should be done in the future to promote and facilitate good PTTI design practice. Topics will include clock performance parameters, environmental considerations, time codes, signal isolation, and time dissemination.

Murray, James A.↗
NASA NTRS2002

What Has He Done For Me Lately?

I had a boss once who continually asked me what the purpose of my work was, who were my customers, and how was I keeping my customers informed about my team's work. At first I found these questions perplexing, as my customers should have known the answers. I had covered them in my monthly/quarterly reports or in my project meeting notes. Finally, I confronted him about his questions. He acknowledged that my customers had this information, but he was hearing some disturbing comments between when I submitted my reports, comments like, 'What has he done for me lately?' I decided to take this input to heart. My ideas about communications norms needed a major overhaul. The communication norms I was comfortable with were becoming outdated. I realized the written and verbal communications response time was suddenly being measured in days or minutes. People's perception of a project team based on monthly or quarterly meetings was no longer adequate. In the past, once the team's credibility was established it was hard to change. In a rapid-fire communications world, no news causes people to question what the team is doing to move the business/project ahead.

Cameron, W. Scott↗
NASA NTRS1961

THEORETICAL STUDY OF ATOMIC AND MOLECULAR GASES AND THEIR REACTIONS IN THE UPPER ATMOSPHERE. SUMMARY OF WORK DONE IN THE PERIOD NOV. 1, 1960 TO APR. 30, 1961

In the previous report it was stated that the major mathematical problems of computations were nearly solved and an attempt is being made to start application of "Tables of Integrals" to the computation of the different states of atoms and molecules. In this respect I like to report that the computation of a number of states of atoms and molecules has been carried out. The results are so far confined only to the equilibrium distance of molecules. We are extending the calculation to other distances so as to compute potential energy curves of different states of molecules. We are also developing Thomas Fermi Statistical model of the atom to verify our results of more accurate calculation. The results so far have been very encouraging and I hope to report some of these results in the next paper.

Gas↗
NASA NTRS1979

When day is done and shadows fall, we miss the airport most of all

Both the effectiveness of pilot training and the safety of flight can be influenced by the distribution of texture in the visual scene, the distance to which the eyes accommodate, and the associated shifts in the apparent size and distance of objects in central and peripheral vision. Studies reviewed and original results presented indicate that these factors are involved in various misjudgments and illusions experienced by pilots: (1) when searching for other airborne traffic or targets, (2) when making approaches to airports over water at night, (3) when breaking out of low clouds on a final approach to a landing by reference to head-up or head-down displays, and (4) when practicing simulated approaches and landings or air-to-surface weapon deliveries by reference to synthetically generated visual systems.

Roscoe, S. N.↗
NASA NTRS1980

The five-minute oscillations: What's left to be done

Current observational methods for studying these oscillations at large horizontal wavenumbers are discussed in detail and several two dimensional power spectra obtained with a CID camera on the main spectrograph of the McMath telescope at Kitt Peak National Observatory are described. The best-resolved observations of the p-mode obtained at chromospheric elevations are also presented. Recent progress in studies of the p-modes at low wavenumbers with full-disk velocity detection schemes is summarized. These full-disk observations of radial and low-degree non-radial modes were shown to place severe constraints on the theoretical calculation of solar interior structure. Progress in making fully-consistent solar models which fit both the high- and low-wave number observations is described. Finally, the observational and theoretical improvements that are necessary for further progress in solar seismology are summarized.

Rhodes, E. J., Jr.↗
NASA NTRS1985

What Is Being Done to Control Motion Sickness?

AFT (Autogenic Feedback Training) involves practicing a series of mental exercises to speed up or slow down the control of autonomic activity. This produces a reduced tendency for autonomic activity levels to diverge from baseline (at rest) under stressful motion-sickness-inducing conditions. Subjects conditions. Subjects engaged in applying AFT exercises are required to closely monitor their own bodily sensations during motion-sickness-eliciting tests. These tests include the Coriolis Sickness Susceptibility Index (CSSI), which consists of sitting a subject into a rotating chair that moves at various speeds while a visual background turns at differing speeds and directions, and the Vertical Acceleration Rotation Device (VARD) test, which involves the placing of a subject in a drum that moves in an upward and downward motion until he or she is sick, while simultaneously monitoring the subject's vital signs. These tests provide investigators with evidence of slight changes in autonomic activities such as increases in heart rate, skin temperature, and sweat. All of these symptoms occur in subjects that experience bodily weakness or discomfort with the onset of motion sickness.

Hall, Y. D.↗
NASA NTRS1987

Gas tungsten arc welding in a microgravity environment: Work done on GAS payload G-169

GAS payload G-169 is discussed. G-169 contains a computer-controlled Gas Tungsten Arc Welder. The equipment design, problem analysis, and problem solutions are presented. Analysis of data gathered from other microgravity arc welding and terrestrial Gas Tungsten Arc Welding (GTAW) experiments are discussed in relation to the predicted results for the GTAW to be performed in microgravity with payload G-169.

Welcher, Blake A.↗
NASA NTRS1985

Computer architectures for computational physics work done by Computational Research and Technology Branch and Advanced Computational Concepts Group

Slides are reproduced that describe the importance of having high performance number crunching and graphics capability. They also indicate the types of research and development underway at Ames Research Center to ensure that, in the near term, Ames is a smart buyer and user, and in the long-term that Ames knows the best possible solutions for number crunching and graphics needs. The drivers for this research are real computational physics applications of interest to Ames and NASA. They are concerned with how to map the applications, and how to maximize the physics learned from the results of the calculations. The computer graphics activities are aimed at getting maximum information from the three-dimensional calculations by using the real time manipulation of three-dimensional data on the Silicon Graphics workstation. Work is underway on new algorithms that will permit the display of experimental results that are sparse and random, the same way that the dense and regular computed results are displayed.

Source record↗
NASA NTRS1987

Application of vigilance research - Rare, medium, or well done?

In the years since Mackworth (1950) initiated research into problems of human vigilance, automated systems have become more complex and costly, with greater repercussions upon failure; this has led to a paradoxical enhancement of human monitoring's importance. Applications of vigilance research to well-designed systems that take human monitoring into account are rare, although the outlook for future systems is improving. Attention is presently given to problems encountered in considerations of signal rate, length of vigil, time decrements, and two examples of implementation from commercial aviation.

Wiener, Earl L.↗
NASA NTRS1991

Reinterpretation of reduction potential measurements done by linear sweep voltammetry in silicate melts

The equilibrium concentrations of Ni between silicate melt and Pt were determined experimentally as a function of oxygen fugacity. The results demonstrate that metallic species derived in linear sweep voltammetry experiments in silicate melts are diffusing into Pt electrodes and not into the melt, as was concluded by previoius studies. This requires reinterpretation of previous linear sweep voltammetry results and recalculation and correction of reported reduction potentials. This paper reports these corrected reduction potentials. Also reported are the activity coefficients for Ni in synthetic basalt and diopsidic melts and for Co in diopsidic melt.

Colson, R. O.↗
NASA NTRS1992

On-orbit deployment anamolies: What can be done?

Modern communications satellites rely heavily upon deployable appendage (i.e., solar arrays, communications antennas, etc.) to perform vital functions that enable the spacecraft to effectively conduct mission objectives. Communications and telemetry antennas provide the radio-frequency link between the spacecraft and the earth ground station, permitting data to be transmitted and received from the satellite. Solar arrays serve as the principle source of electrical energy to the satellite, and re-charge internal batteries during operation. However, since satellites cannot carry back-up systems, if a solar array fails to deploy, the mission is lost. The subject of on-orbit anomalies related to the deployment of spacecraft appendage, and possible causes of such failures are examined. Topics discussed include mechanical launch loading, on-orbit thermal and solar concerns, reliability of spacecraft pyrotechnics, and practical limitations of ground-based deployment testing. Of particular significance, the article features an in-depth look at the lessons learned from the successful recovery of the Telesat Canada Anik-E2 satellite in 1991.

Freeman, Michael↗