Simulation of PFE signal expansion. The initial velocity, deceleration rate, and signal duration are fixed at v
= 10, a = -1, and D = 2, respectively. Signals are propagated according to the t-x plot shown on the right side of this figure. Signal durations are depicted by horizontal bars under the t axis. The front and rear of a signal for a single PFE are indicated by arrows of the same colour. As time progresses, the position and size of the PFEs change. Treatments that produced similar PFEs in Figure 4 are indicated above each simulated PFE.