“…Extensive work has been done on inverse problems for linear materials [4,5,7,9,12]. However, the literature on inverse problems for nonlinear rods is sparse [8,13,18,22,24], especially in the time domain (although there has been recent activity in nonlinear electromagnetic scattering problems using wave splitting [1,6,16,25]). But the time domain is the natural place to study the propagation of short duration pulses, nonperiodic waves and transients, which are important in many applications.…”