Polar plot unit circle

When co = ir/0. ZG(jco) = -k. On the polar plot, the dead time function is a unit circle. 

The Nyquist plot does not encircle the (—1, 0) point if the polar plot of Mreal axis inside the unit circle. The system would then be dosedloop stable. 

Figure 3. 2-D lattice tetramer toy model. Black circles represent solvophobic repeat units (H) and open circles polar repeat units (P). The sigmoidal plot shows the fraction of folded molecules as a function of temperature.

Thus, the Co contour maps into a semicircle in the GmGc plane with a radius that goes to infinity and a phase angle that goes from +7t/2 through 0 to —ttI2. See Fig. 11.4c. The Nyquist plot does not encircle the (- 1,0) point if the polar plot of GM(m)Gc iw) crosses the negative real axis inside the unit circle. The system would then be closedloop stable. 

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