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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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By generating short stress pulses with thick transducers, the pulse-echo method for determining sound velocities and acoustic attenuation can be applied to thin specimens. The stress pulses enter a specimen where one pulse is reflected several times before a succeeding pulse enters the specimen.
Ultrasonic method is used to determine the elastic moduli of materials used in components of high-temperature nuclear reactors. An ultrasonic, pulse-echo technique determines the velocity of sound waves propogating in a heated region of rod-shaped specimens. From these velocities, the elastic moduli are calculated.
Radial focusing of electrons in ion source produces greater ion densities, resulting in higher resolution and focus capability for a given source volume. Electron beam is focused near exit aperture by spherical fields. High density ions allow focusing ion beam to high density at echo, allowing high current through small aperture.
Sheaths for pulse-echo ultrasonic temperature sensor
Five-color multipurpose photometer development and observations on Echo 1 and 2, Explorer 19, and Pageos 1
Doppler echo from random rough surface, discussing average power return, frequencies, amplitudes, antenna beamwidth and radar data correlation
Radar echoes observed from clear atmosphere, discussing scattering mechanisms of thin stable inversions, convective thermals, Benard convection cells, breaking gravity waves, etc
Earth radar studies, relating echo behavior to rocket altitude and surface electrical characteristics
Digital method to produce radar reflectivity from analog audio frequency Doppler data extracted from terrain echo signal of CW scatterometer radar
Martian topography during rotation observed using radar round trip echo delay at 7840 MHz, discussing dark areas relation to elevation
Data reduction and analysis of Pageos 1 and Echo 1 observations for evaluating satellite materials by ground based photometry
Meteor trail measurements taken in New Zealand and Australia by radar echoes and application to wind measurement
Mercury surface features from spectrograms of depolarized radar echoes
Polarized and depolarized radar maps of moon, attributing anomalies and average diffuse component of echoes to scattering behavior of surface and subsurface rocks
CAT at subsidence inversion in presence of strong wind shear, noting radar echo pattern as Kelvin-Helmholtz instability indicator
Diffuse plasma resonance sequence observed on Alouette 2 ionograms, showing pattern similar to spread echo
Radar astronomical polarization measurements for lunar echoes by exploiting ionospheric Faraday rotation with linearly polarized antenna
Ultrasonic, pulse echo interferometric method for analyzing bolt preloads