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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Improved laser ranging accuracy through dynamic threshold compensation

During a polar motion experiment (in which two laser ranging systems on a north-south line simultaneously tracked a satellite to determine motion of the pole), techniques for improving both the range noise and range bias were demonstrated. The corrections to the measured ranges (based on received signal levels relative to a fixed correction that would have been applied if pulse height information was not available) are given. It was shown that even existing long pulse systems (20 to 40 nsec duration) can be improved to the 20 to 30 cm level of precision without major or expensive changes to the system.

Johnson, T. S.↗
NASA NTRS1972

Post-threshold energy dependence of the cross section for endoergic processes - Vibrational excitation and reactive scattering.

The essential features of the translational energy dependence or excitation function for two types of endoergic collisional processes are deduced on the basis of information on the inverse, exoergic processes. Microreversibility is conveniently exploited via the symmetric field function, Y(E), which is uniquely determined at a given total energy, E. In the case of the vibrational excitation of diatomic molecules by atomic or molecular impact, use is made of the abundant data on the temperature dependence of the relaxation time.

Levine, R. D.↗
NASA NTRS1972

An advanced stochastic model for threshold crossing studies of rotor blade vibrations.

A stochastic model to analyze turbulence-excited rotor blade vibrations, previously described by Gaonkar et al. (1971), is generalized to include nonuniformity of the atmospheric turbulence velocity across the rotor disk in the longitudinal direction. The results of the presented analysis suggest that the nonuniformity of the vertical turbulence over the rotor disk is of little influence on the random blade flapping response, at least as far as longitudinal nonuniformity is concerned.

Gaonkar, G. H.↗