Normalized parameter values vs. the nondimensionalized grain strength: (a) d₁/d_1s vs. and (b) k/k_s vs. ,. The normalized d₁ values distribute around d₁/d_1s ≃ 0.5. In the regime of , k/k_s can be scaled as , with C = 2.4 ± 0.3 and α = 0.32 ± 0.03. In the regime of , k/k_s is close to unity. The inset of (b) shows the log-log plot of the identical data. The error bars indicate the standard deviation of five experimental runs.