Use the method of lines with a five-point, biased, upwind finite-difference approximation and a stiff integrator to

Question:

Use the method of lines with a five-point, biased, upwind finite-difference approximation and a stiff integrator to perform PSA cycle calculations that approach the cyclic steady state for the data and design basis in Example 15.14, starting from:
(a) A clean bed, and
(b) A bed saturated with the feed. Are the two cyclic steady states essentially the same?