Active attenuation of tunnel pressure wave with negative pressure gradient generated by positive pressure.

High Pressure Shock Wave Attenuation

The attenuation of high pressure shock waves has been investigated. High purity copper, 6061-T6 aluminum, 6A1-4V and a phase titanium, an uranium alloy and two alloys of beryllium were examined experimentally at pressures as high as 3 megabars. Low pressure experiments were instrumented with a velocity laser interferometer. Intermediate pressures (to several hundred kilobars) were instrumented ...

Evaluation of Pressure Generated by Resistors From Different Positive Expiratory Pressure Devices.

BACKGROUND Breathing exercises with positive expiratory pressure (PEP) are used to improve pulmonary function and airway clearance. Different PEP devices are available, but there have been no studies that describe the pressure generated by different resistors. The purpose of this study was to compare pressures generated from the proprietary resistor components of 4 commercial flow-dependent PEP...

Active noise barrier minimizing pressure gradient

Active noise barrier minimizing pressure gradient" (2010). Architectural Engineering-Faculty Publications. 96. Minimization of the sound pressure field within the shadow zone of a noise barrier is achieved by reducing the pressure gradient along a line, at the top of a barrier, via active noise control. The noise control effectiveness of a barrier is increased by this strategy, especially for s...

Analytical analysis of ultimate ground pressure on tunnel support system

The ground reaction curve (GRC) is a vital component of the convergence-confinement method, which possesses many applications in the underground space designs. It defines a relation between the tunnel wall deformations and the ground pressure acting on the tunnel walls. Generally, GRC includes descending and ascending branches. According to many researchers, the descending branch trend for the ...

Intraocular Pressure during Continuous Positive Airway Pressure