Pressure oscillation high-frequency

Dynamic Acoustic oscillations High frequencies related to time required for pressure wave propagation in system -... 

Electrons from a spark are accelerated backward and forward rapidly in the oscillating electromagnetic field and collide with neutral atoms. At atmospheric pressure, the high collision frequency of electrons with atoms induces chaotic electron motion. The electrons gain rapidly in kinetic energy until they have sufficient energy to cause ionization of some gas atoms. 

According to Haber (loc. cit., p. 131) the results of Langen are probably correct to 3 per cent, even at 2,000°. Pier, in his recent explosion experiments, has shown, however, that the maximum pressures were not obtained by the previous observers, on account of the oscillations of their manometers, He used a steel plate with very high frequency of vibration, and registered the distortion by reflecting a beam of light from a mirror attached to the manometer disc on to a revolving drum of sensitised paper. The recorded curves show a well-defined maximum pressure, and his results are probably accurate to 1 per cent. Values of Gv ... 

Several devices are also available to promote airway clearance. Flutter valve devices employ oscillating positive expiratory pressure (OPEP) to cause vibratory air flow obstruction and an internal percussive effect to mobilize secretions. Intrapulmonary percussive ventilation (IPV) provides continuous oscillating pressures during inhalation and exhalation. Finally the most commonly used technique is high-frequency chest compression (HFCC) with an inflatable vest that provides external oscillation. Vest therapy is often preferred by patients because they can independently perform the therapy even from an early age.5,14... 

High-frequency pressure oscillations (10-100 Hz) related to time required for pressure wave propagation in system Low-frequency oscillations (-1 Hz) related to transit time of a mass-continuity wave Occurs close to film boiling... 

Sound waves provide a periodic oscillation of pressure and temperature. In water, the pressure perturbation is most important in non-aqueous solution, the temperature effect is paramount. If cu (= 2 nf, where/is the sound frequency in cps) is very much larger than t (t, relaxation time of the chemical system), then the chemical system will have no opportunity to respond to the very high frequency of the sound waves, and will remain sensibly unaffected. 

Combustion of a propellant in a rocket motor accompanied by high-frequency pressure oscillation is one of the most harmful phenomena in rocket motor operation. There have been numerous theoretical and experimental studies on the acoustic mode of oscillation, concerning both the medium-frequency range of 100 Hz-1 kHz and the high-frequency range of 1 kHz-30 kHz. The nature of oscillatory combustion instability is dependent on various physicochemical parameters, such... 

In Fig. 3 the pressure and concentration (n) variations in the wave are shown. The diffuse structure in this case may be explained qualitatively by the fact that the high-frequency waves necessary to generate a steep front propagate with a speed greater than D and, moving forward away from the wave, are damped (absorbed). As Einstein showed, waves with an oscillation period less than t decrease in amplitude by e times at a distance of order cr. 

Microwave discharge This operates at very high frequencies (e.g., 2.45 GHz) in the range of microwaves, within which only light electrons can follow the oscillations of the electric field. Therefore, this discharge is far from the local thermodynamic equilibrium, and can be operated over a wide pressure range. The performance of a microwave discharge depends heavily on the type of microwave power applicator (detailed information on this subject is available elsewhere [6, 7]). 

One technique that addresses both container reaction and impurity inclusions is a high pressure, RF, melt growth process. With this process, the material is inductively heated by RF energy, oscillating at frequencies between 450 kHz and 4 MHz. Power levels up to 100 kW are available to produce melt temperatures of the order of 2600°C. To prevent decomposition, the chaige is contained in a nitrogen over-pressure of 10 to 100 atm. The liquid aluminium nitride is self-contained in a water-cooled skin, which prevents both container reaction and deleterious inclusions. 

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