Bilous and Amundson [S], inspired by the work of Van Heerden put the analysis of local stability of the reactor steady states on a rigorous basis by the use of the First method of Liapunov. Thus since this paper in 1955, it has been a straightforward matter to determine the stability properties of the steady states. Although Bilous and Amundson did show phase plots of oncentration and temperature trajectories in their paper [5], really extensive numerical
calculations were only first reported in 1958 by Aris and Amundson[6]. Through the use of an
example with a variable proportional feedback controller gain, Aris and Amundson[6] demonstrate
how the phase plots change as the controller gain is increased. Through this example they show that in addition to the presence of multiple steady states, undamped oscillations in the form of limit cycles can occur for some combinations of the system parameters. They also recognized that these limit cycles should bifurcate (originate) at the critical value of the feedback control parameter where the stable steady state becomes unstable. In fact, they developed a criterion for the direction of bifurcation and gave plausible arguments for the stability of the limit cycle.