Firing pulse

The thyristor is a semiconductor device made of germanium or silicon wafers and comprises three or more Junctions, which can be switched from the OFF state to the ON state or vice versa. Basically it is a ptipn junction, as shown in Figure 6.20(a) and can be considered as composed of two transistors with npn and pnpjunctions, as illustrated in Figure 6.20(b). It does not turn ON when it is forward biased, unlike a diode, unless there is a gate firing pulse. Thyristors are forced commutated (a technique... 

Since the early 1990s, however, the use of a powerful laser to fire pulses of increasing intensity at the back of an electrode in the form of a thin plate (Velev, 1991) has allowed reaction rates at a series of increasing temperatures to be measured in a few minutes. Such measurement times may be short enough (in systems where good control is practiced to reduce impurities) to make values of i0 independent of changes in the electrode surface that occur with time. The more meaningful data on temperature effects measured with this technique will stimulate attention to clear up the effects of the inclusion of A/7 ev in Eq. (7.89), which seeks to get only at AHox. 

Although the laser is repetitively charged for firing on its own internal cycle (currently 55 seconds), the actual firing pulse of the laser is synchronized to the internal clock of the OMA. This is to enable the streaked image on the camera phosphor to appear during the 768 usees retrace interval between OMA target scans. 

For reasons of safety, the short-circuit device of UR 1/400 as given in Fig. 12.6 (V1-V3) may be replaced by a bridge-connected rectifier (Fig. 12.9) V1-V3 and V4-V6, followed by two thyristors V7 and V8 fired in parallel. The lack of any current zero passage at the output of V1-V3/V4-V6 ensures a short-circuit time not affected by the availability of firing pulses for the thyristors. They return to their non-conducting state with neglectable current. 

The conventional HE warhead, when armed, can be detonated in one of three ways (1) when it penetrates a metal object a firing pulse is generated (2) when it decelerates on contact with a solid object and (3) it destroys itself after 15 sec fli t (Ref 2)... 

The rectifier (1) may be of the 6 or 12-pnlse type. The choice mainly depends npon the tolerance that is available for the harmonics, which will be injected into the upstream power system. The rectifier will be designed to provide a sonrce of variable voltage to the DC link. The 12-pulse type will usually be necessary for the highly rated motors within their voltage level. Inside the rectifier compartment will be a set of voltage transformers (9) which will be nsed to derive a set of firing pulses (10) for the rectifier elements. These pnlses will be in synchronism with the power supply. 

Dubey, R.K., Black, D.L., McQuay, M.Q., and Carvalho, J.A. Jr., The effect of acoustics on an ethanol spray flame in a propane-fired pulse combustor. Combustion and Flame, 110, 1997, 25-38. 

The control of a thyristor unit, on the other hand, is applied to the rectifying elements themselves by varying the timing of the firing pulse. Action is much more rapid (one or two cycles, vs a number of seconds), and control is smooth over the entire range... 

PRF. Defines the pulse repetition frequency (PRF), in Hz, of the probe firing. 

Figure B2.3.9. Schematic diagram of an apparatus for laser fluorescence detection of reaction products. The dye laser is syncln-onized to fire a short delay after the excimer laser pulse, which is used to generate one of the reagents photolytically.

There are two types of impulse printers (Eig. 19). A piezoelectric ink jet propels a drop by flexing one or more walls of the firing chamber to decrease rapidly the volume of the firing chamber. This causes a pressure pulse and forces out a drop of ink. The flexing wall is either a piezoelectric crystal or a diaphragm driven by a piezoelectric incorporated into the firing chamber (Eig. 19a). Thermal impulse ink jets also propel one drop at a time, but these use rapid bubble formation to force part of the ink in a firing chamber out the orifice (Eig. 19b). 

Flywheels are found in internal-combustion engines, where they damp out torque pulses caused by the periodic firing of cylinders. In this application, energy is stored veiy briefly before it is used— for less than one revolution of the wheel itself... 

NOTE Action potentials are represented as a pulse output from a spike-height discriminator Each vertical line represents one action potential. The firing rate of this neuron during similar pre-and postdrug behaviors is increased by injection of 1.0 mg/kg, SC, amphetamine. This increase occurs for both locomotion (from a mean of 28.3 to 39.0 spikes/sec) and face washing (fiom a mean of 43.7 to 46.5 spikes/sec). 

The analytical area of interest is positioned in the focal spot of the He Ne laser beam, the transient recorder is armed to record, and the Nd YAG laser is fired. This laser pulse of between 5 and 15 ns duration produces a packet of ions that is accelerated from the sample surface and injected into the TOF-MS. All the... 

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