本文的目的在于说明提高旧船螺旋桨转速所用的一些实用方法。

This paper describes some practical methods used to increase propeller revolutions in aged ships.

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用短时傅立叶分析的方法研究了辐射噪声在高频段时频变化的周期性，估计了目标的螺旋桨转速。

Period characteristics of radiated noise at high frequency is investigated by a method based on short time Fast Fourier Transformation, and propeller speed is estimated.

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通过DEMON分析可以获得诸如舰船螺旋桨转速、螺旋桨叶片甚至舰船的车数等不变的舰船物理特征。

Many invariable physical features can be obtained with DEMON analysis such as revolution rate of propeller, the propeller vane, and the number of propellers.

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