(Color online) Patterns of wave trains interacting on defects with different shapes. The pacing frequencies are ω/ω_min=0.82 in (a), ω/ω_min=0.83 in (b), ω/ω_min=0.93 in (c), and ω/ω_min=0.96 in (d), respectively. The size is H = L = R = 30 △ x .