Covert cavitation: Spectral peak suppression in the acoustic emissions from spatially configured nucleations

Dual laser-nucleation is used to precisely configure two cavitation bubbles within a focused ultrasound field of f0 = 692 kHz, in proximity to the tip of a needle hydrophone. With both bubbles responding in the f0/2 sub-harmonic regime, confirmed via ultra-high speed shadowgraphic imaging, an emission spectrum with no sub-harmonic content is demonstrated, for an inter-bubble spacing ≈λ0. A spectral model for periodic shock waves from multiple nucleations demonstrates peak suppressions at nf0/2 when applied to the experiment, via a windowing effect in the frequency domain. Implications for single-element passive detection of cavitation are discussed

Reinforced carbon-carbon oxidation behavior in convective and radiative environments

Reinforced carbon-carbon, which is used as thermal protection on the space shuttle orbiter wing leading edges and nose cap, was tested in both radiant and plasma arcjet heating test facilities. The test series was conducted at varying temperatures and pressures. Samples tested in the plasma arcjet facility had consistently higher mass loss than those samples tested in the radiant facility. A method using the mass loss data is suggested for predicting mission mass loss for specific locations on the Orbiter

A Cephalopod Approach to Rethinking about the Importance of the Bohr and Haldane Effects

This study concerns the physiological implications of the Bohr and Haldane effects and the buffer values in the blood from the cephalopods Nautilus pompilius, Octopus macropus, Sepia latimanus, Nototodarus sloani philippinensis, and Sepioteuthis lessoniana. All species studied except one (Nautilus) have Bohr and Haldane coefficients numerically higher than unity, and the two effects were found to be nearly identical in all cases, in accord with the theoretical prediction of Wyman (1964). However, the functional Haldane coefficient was significantly lower than the Haldane coefficient in two cases (Sepia and Sepioteuthis). Buffer values were highest in the two species with the lowest oxygen requirement (Nautilus and Octopus), whereas the three fast swimmers studied (Nototodarus, Sepia, and Sepioteuthis) display comparatively low buffer values. It is concluded that the large Bohr effects seen in four of the five species may have their primary effect on oxygen loading in the gills

Uncertainty estimation via preflight test procedures for a space stabilized inertial navigation system

Preflight operation and alignment of space stabilized inertial navigation system for vertical takeoff aircraf