Study of EMIC wave excitation using direct ion measurements

Correspondence between a plasma-based EMIC wave proxy and subauroral proton precipitation

[1] The loss of relativistic electrons from the Earth’s radiation belts as a result of resonant interactions with electromagnetic ion cyclotron waves (EMIC) waves has yet to be fully quantified, in part, due to the lack of global measurements of the wave distribution during individual storm events. Recent work has focused on augmenting direct wave measurements with proxy wave indicators. Here w...

Shear wave speed and dispersion measurements using crawling wave chirps.

This article demonstrates the measurement of shear wave speed and shear speed dispersion of biomaterials using a chirp signal that launches waves over a range of frequencies. A biomaterial is vibrated by two vibration sources that generate shear waves inside the medium, which is scanned by an ultrasound imaging system. Doppler processing of the acquired signal produces an image of the square of...

Direct torsional actuation of microcantilevers using magnetic excitation

Wave Measurements Using GPS Velocity Signals

This study presents the idea of using GPS-output velocity signals to obtain wave measurement data. The application of the transformation from a velocity spectrum to a displacement spectrum in conjunction with the directional wave spectral theory are the core concepts in this study. Laboratory experiments were conducted to verify the accuracy of the inversed displacement of the surface of the se...

Direct Lattice Parameter Measurements Using HAADF-STEM

Lattice strain is generated in crystal structures as a result of atomic size differences between host atom and solute elements during substitutional alloying. Extensive work has been performed to study lattice parameter variation with alloying elements, primarily using diffraction methods. The global information provided by reciprocal space analysis, however, limits access to local structural d...