Meaning: The self-correlation function and power spectrum density Function of a power-typed signal compose a FT pair.

上式表明：功率型信号的自相关函数与其功率谱密度函数构成傅立叶变换对。

An analysis of a type of angular contact ball bearing under given input power spectrum density is performed. The result demonstrate that the bearing is safe in any load direction.

以某种角接触球轴承为例，验证了其在给定输入功率谱密度下任意方向加载都安全。