纳米尺度下的气体流动具有不同于常规尺度的规律，其中重要的特征是纳米间隙中气体分子自由输运行程将减小，进而影响气体的输运规律。

Gas flow in nanoscale space has distinct characteristics compared with that in conventional macro-scale, due to the influence of space dimension on gas mean free path.

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作功行程：活塞处于汽缸中的上止点，火花塞点燃充分压缩后的混合气体。

Power stroke: As the fuel is compressed and the piston nears the top of the cylinder the spark plug fires and ignites the fuel and air.

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作功行程：活塞处于汽缸中的上止点，火花塞点燃充分压缩后的混合气体。

Power stroke: As the fuel is compressed and the piston nears the top of the cylinder the spark plug fires and ignites the fuel and air.

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