Virtual voltage sources

In order to facilitate the way of notation, it is useful to represent the virtual voltage sources by SF = [SF] cos (2coLf) and Sc = [Sc] cos (2col ). Again, the Laplace transform method is most useful for solving... 

The shape of the crossover diameter dco> which is the virtual electron source, is controlled by the geometry of the electrodes that compose the electron gun and the associated voltages (Fig. 

As an example, the circuit with one switch in Fig. 4.1, is considered. To keep the illustration of the procedure short and simple it is assumed that only one parameter is uncertain. Accordingly, the incremental bond graph is obtained by replacing the element by its incremental model and by replacing the constant voltage source Se Vi by an effort source of value zero and by replacing detectors by dual virtual detectors for the variations of ARR residuals. 

The recognition that a resistor could be simulated with the combination of a capacitor and MOS switches was the basic theory underlying the operation of SC filters. To illustrate this principle let us consider the SC configuration shown in Fig. 7.149 where the switch is moving back and forth between positions 1 and 2 with frequency Hz. In the analysis to follow, switch position 1 or 2 will be referred to as switch-1 or switch-2, respectively. Assume that vi and V2 are voltage sources (or virtual ground or op amp s output) that is, the values of vi and V2 are not affected by the switch actions. When the switch is in position 1... 

In addition to these general impedance simulations, the sensitivity of an electrode arrangement to impedance variations in the bladder region has been assessed. For this, the principle of the reciprocal lead field described by [12] and adapted to COMSOL by [11] has been used. To quantify to which extent a small volume contributes to the measured overall impedance, a second, virtual current source is introduced by making the voltage measurement electrodes current carrying. The current density vector field by this virtual current source is called the reciprocal lead field and specifies the sensitivity of the voltage measurement electrodes. The measured impedance can be expressed as... 

Except for the most exact measurements, zener diodes in a constant-temperature oven are generally used now as reference voltage sources in electrical equipment. They are stable and virtually immune to mechanical trauma. 

A Hanovla chromatollte lamp was used as the source of ultraviolet radiation. This Is a low-pressure mercury arc, the main emission comprising the resonance lines at 1849 and 253 R. The former Is completely absorbed by 1 cm of air, while the latter Is almost completely transmitted by air and 95% by silica. Thus virtually pure 253 X radiation Impinges on the polymer. The lamp was connected to an L.T.H. transistorized 1 kVA voltage regulator to ensure that fluctuations In mains output did not affect emission. 

In principle, the low-side mosfet does not have any significant crossover loss because there is virtually no overlap between its V and I waveforms — it switches (changes state) only when the voltage across it is almost zero. Therefore, typically, the high-side mosfet is selected primarily on the basis of its high switching speed (low crossover loss), whereas the low-side mosfet is chosen primarily on the basis of its low drain-to-source on-resistance, Rds (low conduction loss). 

There is very little loading effect of the current follower circuit. Because the input current source is connected between point S and arinmon and point 5 is kept at virtual common, the input-signal. source senses virtually zero resistance at its output terminals. The effective input resistance R, is the error voltage divided by the input current, i, that is, / , -- v ii.. Because - c,.M atid from Equation 3-4/, - -i jR,. we can write... 

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