High frequency oscillating devices

Another prototype device, which has been demonstrated by researchers at Pacific Wave, is that of a high frequency oscillator (see Fig. 9). In this oscillator, the stability of the oscillator is determined by the length (Q) of the optical circuit (loop) and can thus be very high indeed. 

Negative differential resistance and the related high-frequency oscillations in magnetoconcentration InSb structures was theoretically predicted by Guga et al. [396], and experimentally confirmed by Akopyan [395, 402]. These oscillations were observed in photodetectors by Piotrowski, Nowak et al. in mercury cadmium teUuride devices [351]. 

The differential transformer is a compact, highly. sensitive, linear device which is commercially available. The most satisfactory instrument. system for the differential transformer is a high-frequency oscillator-amplifier phase-sensitive demodulator carrier. system which provides the neces.sary sensitivity and stalrility and eliminates phase-motion ambiguity a.ssociatod with the null voltage. 

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... 

Atomic filter A sort of device with an ultra-high Q obtained by using the vibrations of atoms. These systems employ the microwave amplification by stimulated emission of radiation (maser) of substances such as cesium or ruby to stabilize the primary oscillator of extremely precise devices that work at high frequency values [i]. 

Josephson junctions are superconducting devices that are capable of generating voltage oscillations of extraordinarily high frequency, typically 1O —10" cycles... 

In order to use this technique, a mechanical device with exceptionally good stability must be used to maintain the probe position. A small-amplitude ( 10 nm), high-frequency ( 30 to 130 kHz) feedback resonant oscillation method has been successfully used to keep the tip positioned on a irregular... 

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