虽然肯定要比喷气式飞机速度慢一些，但是混合型的飞艇基本上没有噪声，同时起飞和降落都不需要下面的基础设施。

Although certainly slower that hopping on a jet, the hybrid blimps are nearly silent and require very little infrastructure to take off and land.

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声学相似性是水下结构噪声模型试验的基础。

Acoustic similarity is the base of scaled model tests of underwater structure noise.

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再次，在对轮胎花纹噪声研究的基础上，探讨了道路噪声的发声机理、 发声模型及其仿真模型，并进行了仿真实验分析。

Thirdly, the paper has discussed the generation mechanism, acoustic model and the simulation model of the road noise on the basis of the tire pattern noise, and carried out the simulation analysis.

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