Sound is created by vibrations, such as those produced by a guitar string, vocal cords, or a speaker cone. These vibrations move the air molecules near them, forcing molecules together, and as a result raising the air pressure slightly. The air molecules that are under pressure then push on the air molecules surrounding them, which push on the next set of air molecules, and so forth, causing a ...

in this work, the potential of auto-ignition of heavy oil during in-situ combustion (isc) process was studied. kinetic studies were carried out using thermo gravimetric analyzer (tga), differential scanning calorimetry (dsc) and accelerating rate calorimetric (arc) techniques. effects of oxygen partial pressure, reservoir pressure and clay on auto ignition condition were investigated on a numbe...

Pressure distribution patterns of the seating interface on the multi-cell air cushion (ROHO High Profile) of 36 adults with spinal cord injury (SCI) (Neurological level Th3 -L1) were measured at different air pressure levels by a pressure mat measurement system. Stress distribution relative to the inflated air pressure in the air cushion on the patients' wheelchairs was analyzed to determine th...

BACKGROUND Post-craniotomy intracranial air can be present in patients scheduled for air ambulance transport to their home hospital. We aimed to assess risk for in-flight intracranial pressure (ICP) increases related to observed intracranial air volumes, hypothetical sea level pre-transport ICP, and different potential flight levels and cabin pressures. METHODS A cohort of consecutive subdura...

air pollution is a problem in kathmandu, nepal. particulate matter concentrations often exceed threshold values at which human health is severely affected. the problem is serious since it is in the valley topography wherein the meteorological parameters role is significant. this study addresses the linkages between meteorological processes and air pollution in the lower atmosphere of the kathma...

AIMS To investigate the effect of total air pressure raise on cell growth and intracellular beta-galactosidase activity in batch cultures of Kluyveromyces marxianus CBS 7894. METHODS AND RESULTS A pressurized bioreactor was used for K. marxianus batch cultivation under increased air pressure from 1.2 to 6 bar. Under these conditions no inhibition of cell growth was observed. Moreover, the imp...

Table 1. Standard air density as a function of elevation above sea level (at 70F and 50% relative humidity). M echanical ventilation can be divided into three types: negative-, positive-, and neutral-pressure ventilation. Negativepressure systems use fans to exhaust air, thereby creating a slight partial vacuum that draws fresh air in from outdoors. Negative-pressure ventilation systems are use...

INTRODUCTION Continuous positive airway pressure (CPAP) is used in air ambulances to treat patients with impaired oxygenation. Differences in mechanical principles between CPAP devices may affect their performance at different ambient air pressures, as will occur in an air ambulance during flight. METHODS Two different CPAP systems, a threshold resistor device and a flow resistor device, at s...

The test method NBI 167/02 Radon membrane: Test of airtightness can be used for determining the airtightness of a radon barrier as a system solution. The test determines the air infiltration through the radon barrier for a number of levels of air pressure differences. The airflow through versus the difference in air pressure over the barrier is measured. The air pressure difference is kept cons...