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Figure 3: Normalized cell voltage for two values of the BEMF
Smoothing/fitting the normalized cell voltage
Amperage fluctuations are not the only phenomena adding higher frequency
variation or noise on the raw cell voltage. Metal pad roll generated by magneto-hydro-
dynamic (MHD) and CO
2
bubble gas release are two extra phenomena that add noise to
the cell electrical resistance either expressed as cell pseudo-resistance or normalized cell
voltage.

Dyna/Marc can be used to generate noisy cell resistance data which is
accomplished by adding higher frequency ACD fluctuations in addition to the very
slowly evolving ACD. Since Dyna/Marc knows the value of the slowly evolving ACD
before the addition of the extra higher frequency fluctuation, it can calculate the noise
free cell pseudo-resistance in addition to the noisy cell pseudo-resistance (see Figure 4).

To generate those results, Dyna/Marc was run using a 0.1 seconds time steps.
The ACD noise generation subroutine available in Dyna/Marc generated a higher
frequency ACD fluctuation to mimic metal roll and CO
2
gas release. That noise can be
set to be proportional to ACD, mass of sludge and ledge toe position by user defined
parameters. The aim of any cell controller smoothing/fitting algorithm is to generate the
blue curve using data from the noisy green curve in Figure 4.