Furthermore, the time history and spectrum of the average flow velocity through an orifice are computed, from which the nonlinear distortion of flow velocity is analyzed.

进而计算了圆孔中的声质点速度，并分析了孔中速度的畸变情况、最后给出了圆孔的非线性声阻和声抗的理论值。

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The currents of history may ebb and flow, but over time they move -- decidedly, decisively -- in a single direction.

WHITEHOUSE: President Obama Speaks to the Australian Parliament