图7. 不同主动弯矩波长$\lambda_{act}/L$ 下波速比与(a)驱动波频率和(b)组合无量纲量$\varPi$的关系图
Fig. 7. The speed ratio in relation to (a) the dimensionless frequency $\omega/\omega_0$ and (b) the dimensionless variable $\varPi$ under different wavelengths of active bending moment