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Results for “Electrical resistivity”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

High electrical resistivity carbon/graphite fibers

Carbon/graphite fibers were chemically oxidized in the liquid phase to fibers of graphite oxide. Resistivity increases as high as 10,000 times were obtained, the oxidized fiber decomposed on exposure to atmosphere. A factor of 1,000 remained as a stable increment. The largest change observed was 1,000,000 times. Best results were obtained on the most highly graphitized fibers. Electrochemical oxidation yielded a lower increase--about 10 times, but provided a controllable method of synthesis and insight to the mechanism of reaction. Tensile tests indicated that the strength of the fiber on oxidation was decreased by no more than 25 percent.

Vogel, F. L.↗
NASA NTRS1980

Use of an electrical resistance hygrometer to measure human sweat rates

The application of the resistance hygrometer as a tool to measure the localized sweat rate from the human body in both the active and passive sweat regions was studied. It was found that the physiological function of the skin membrane and fluid carrier transport phenomena from the outer skin have an indistinguishable effect on the observed findings from the instrument. The problems associated with the resistance hygrometer technique are identified and the usage of the instrument in the physiological experimentation from the engineering standpoint is evaluated.

Suga, T.↗
NASA NTRS1994

Development of radiation resistant electrical cable insulations

Two new polyethylene cable insulations have been formulated for nuclear applications and have been tested under gamma radiation. Both insulations are based on low density polyethylene, one with PbO and the other with Sb2O3 as additives. The test results show that the concept of using inorganic antioxidants to retard radiation initiated oxidation (RIO) is viable. PbO is more effective than Sb2O3 in minimizing RIO.

Lee, B. S.↗
NASA NTRS2009

Investigation of Thickness and Electrical Resistivity of the Current Sheets in Solar Eruptions

A discussion of the thickness of current sheets in solar eruptions led Lin et al. in 2007 to estimate very large values for the effective resistivity. This paper addresses some questions raised by that paper. The limb synoptic map technique is applied to find the current sheet thickness to be between 5.OE4 and 4.6E5 km, increasing with both time and altitude. The possibility that large apparent values result from projection effects is examined and rejected. Theoretical scaling laws corroborate this conclusion.

Lin, J.↗
DOE OSTI2023

Time-lapse electrical resistivity and induced polarization monitoring of a simulated ecosystem-scale coastal flooding experiment

Accurate estimation of the spatio-temporal variation in soil saturation and salt concentration is valuable for calibrating and evaluating Earth system models as well as detecting important eco-hydrological interactions. Such representative models play a vital role in investigating the stability of ecosystems facing changing hydrologic disturbance regimes. Ecosystem-scale field experiments are a useful way to capture hydrological disturbance and gain a deeper understanding of the complex mechanisms driving environmental changes. However, previous studies have not explored the use of quantitative imaging at a large spatial scale to reproduce breakthrough curves and inform system response and recovery following hydrologic disturbance events. Therefore, in this study, non-invasive geophysical methods were used to capture the spatio-temporal variation in subsurface saturation and salt concentrations during an ecosystem-scale coastal forest flooding experiment.

coastal↗