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Artificial Evolution by Viability Rather than Competition

Figure 2

Example of viability boundaries definition for a filter design problem.

A candidate filter design being optimized with Viability Evolution must satisfy certain requirements defined by the user as viability boundaries. Here, the filter gain-bandwidth product (GBW, computed at the cutoff frequency ) must satisfy the viability boundary . The stop-band attenuation (SBA) of the filter is also constrained by the viability boundary . Finally, a filter must also satisfy a requirement on the pass-band flatness (PBF), i.e. the deviation of amplitude gain from the gain at cut-off frequency, such that . The response for two different filters is depicted in figure. The first filter (solid line) is viable as it satisfies all viability boundaries, while the second filter (dashed line response) is non-viable, as it violates the viability boundaries expressed on pass-band flatness.

doi: https://doi.org/10.1371/journal.pone.0086831.g002