Pulse stimulus

Figure 19.3 Pulse stimulus (a)-response (b) experiment with tracer A...

The best outcome may be achieved using a constant-current device with a brief-pulse stimulus sufficient to at least moderately surpass the seizure threshold, especially when using the UND placement. As noted earlier, we consider high-energy stimulation (250% to 500% of ST) and would also avoid the use of... 

A pulse stimulus in which a relatively small amount of tracer is injected at the reactor entrance in the shortest possible time. 

For linear systems the relative response to a pulse stimulus is equal to the derivative of the relative response to a step stimulus. Illustration 11.1 indicates how the response of a reactor network to a pulse stimulus can be used to generate an F(t) curve. 

ILLUSTRATION 11.1 Determination of an F(t) Curve from the Response of a Reactor to a Pulse Stimulus... 

Alternative methods of estimating T) are based on the response of the reactor to an ideal pulse stimulus. For example, equation (11.1.39) may be used to calculate the mean residence time and its variance. Levenspiel and Bischoff (9) indicate that for the boundary conditions cited. 

In Illustration 11.1 we considered the response of an arbitrary reactor to a pulse stimulus and used these data to determine the average residence time and the F(0 curve. If the pulse is assumed to be perfect, what value of T)JuL gives a reasonable fit of the experimental data Use the slope and variance methods to evaluate this parameter. 

Now consider determination of this parameter using the variance of the response to a pulse stimulus. The variance measures the spread of the distribution about the mean. For a continuous distribution it is defined as... 

A preferable alternative to the slope approach to determining the appropriate value of n for use in model calculations is based on a determination of the variance of the response of the actual reactor to a pulse stimulus. For linear systems this is equivalent to determining the variance of the derivative of the F(t) curve. The response of the... 

Hence by determining the variance of the response of a system to a pulse stimulus, one may obtain an estimate of n for use in subsequent reactor design calculations. 

Use the data of Illustration 11.1 for the response of a reactor network to a pulse stimulus to determine the number of identical stirred tank reactors in series that gives a reasonable fit of the experimental data. Use both the slope and variance methods described above. 

Table P11.29 Pulse Stimulus-Response Data for Inert and Adsorbed Gases...

All signals are ignored during the absolute refractory period, and noise sampling occurs within the relative refractory period. The purpose of the ARP is to prevent oversensing of the output pulse stimulus afterpotential, the atrial electrogram produced by the atrial stimulus, or ventricular depolarization. 

Concentration of X increases from X, to Xf for a time At and then decreases to X again to give a pulsed stimulus (shaded region of graph). Bfis the final steady-state concentration of B, i.e., the concentration that would be reached if the stimulus remained fixed at Xf. For other details see text. 

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