Incremental impedance

Output power is 3.3 x 50 = 165 W. Rl is 3.3/50 = 0.066 O. Duty cycle is 0.092 at 36 V input. So the magnitude of Rin is 0.066 / (0.092)2 = 7.8 Q. In terms of decibels this is 201og(7.8) = 18 dBO. A similar calculation at 75 V input gives 31 dBO. So the (magnitude of the negative incremental) impedance of the buck converter falls as the input voltage falls. We will see that this means that this form of instability is more likely to occur at low input voltages. 

Incremental Impedance for Nonlinear, Time-Variant Objects... 

Digitizing the waveforms at 5 ns increments over nearly 6 decades yields in excess of 260,000 data points. This has two drawbacks. One is that it is simply inconvenient the excessive number of data points is cumbersome and impedes data analysis and display. The second drawback has a more important consequence. Digitizing a long time span in small intervals leads to unnecessary point density at longer times. For example, at t — 25 ns, the... 

At the macroscopic scale, shear localization flow in the alloy develops during initial increments of deformation. Softening and globularization of structure in the macro shear band lead to realization of deformation at mesoscopic scale. In this case the mesoscopic scale deformation is determined by cooperative grain boundary sliding leading to superplastic flow. Superplastic flow results in deformation accumulation in the central area of the sample and impedes in structure transformation in periphery regions. 

Whole blood exhibits P-, y-, and 6-dispersion, but curiously enough it exhibits no a-dispersion (Foster and Schwan, 1989). The 3-dispersion has a dielectric increment of approximately 2000 centered at approximately 3 MHz (hematocrit 40%). Erythrocytes in suspension have a frequency-independent membrane capacitance with very low losses (Schwan, 1957). The impedance of lysed erjrthrocytes in suspension shows two clearly separated single relaxation frequencies (Debye dispersions). The a-dispersion is in the lower kilohertz range, and the p-dispersion is in the lower MHz range (Schwan, 1957 Pauly and Schwan, 1966). 

Fig. 4.2 Incremental bond graph of a 1-port R element in (a) impedance and (b) admittance causality...

When the specimen is utilized as an electrical component such as a filter or a vibrator, the electrical impedance [(applied voltage/induced current) ratio] plays an important role. The current flow into the specimen is described by the surface charge increment, dD /dt, and the total current is given by ... 

Table 2.4 tabulates some variations of overall thicknesses that can be configured with the previously stated four increments of tape thicknesses. This gradation of overall thickness coupled with line width variation results in the ability to meet a wide variety of impedance values. 

Good gas barrier properties of the organoclay in the nanocomposites and formation of char on the surface of the samples are the factors responsible for the increment in flame retardancy. These factors will impede oxygen diffusion into the nanocomposites and so reduce the fuel supply for burning. 

It is reasonable to assume that the microstructure of the polymer is on a much finer scale than the thickness of the film, so unit increments of N have little effect on the total impedance. Hence for large N, we set N + 1 = N, and Eqn. 421 reduces to... 

In larger lesions, the array is withdrawn and redeployed anteriorly at 1.5- to 2.0-cm intervals into the tumor. After the hooks are fully deployed, the electrode is connected to the RF generator. The heating protocol for all the available needles is provided by the manufacturer. In general, the generator is started at a lower power setting and is subsequently increased in 10-W increments at 1-min intervals. The endpoint of RF application is the appearance of a rapid increase in tissue impedance (Roll-off) around the electrode. When this occurs, the RF application is automatically terminated. This process is repeated starting at 70% of the roll-off power until a second increase of the impedance occurs. Since the time point of the rapid increase in tissue impedance cannot be predicted, the ablation time needed varies dramatically between different tumor sizes and nodules. At the end of the procedure the needle track is ablated to prevent any tumor dissemination. Therefore, the tip has to be unisolated prior to the insertion of the needle. 

Electrical impedance is defined as the ratio of incremental voltage to the resulting current. The excitation voltage applied is a modulated AC signal ie, a small direct current (DC) bias is superimposed with an AC signal. Let us assume the following ... 

Figure 12.22. Transmission line example. Source voltage with source impedanee and load impedance are shown. Incremental internal model is shown.

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