For conductive fillers / piezoelectric ceramic / polymer composites , based on the piezoelectric and conductive theories , mechanical energy or sound energy can change into electric energy induced by piezoelectric ceramic ' s piezoelectric effect , and then these energy can be dissipated in form of heat energy through conductive network formed by conductive fillers in the system 在导电填料/压电陶瓷/聚合物复合材料体系中，根据压电、导电原理，机械振动能(或声能)可通过压电陶瓷的压电效应转换为电能，并通过体系中导电填料形成的导电网络，将电能以热的形式耗散，从而达到减振降噪的效果。
The reason that the noise is lower with inclining tongue is : 1 ) both the radius of the tongue and the gap between the tongue and the blade are changed across the wideth ; 2 ) the phase angle between blade and the tongue is changed across the wideth , therefore the peak value of the noise do not appear at the same time , so the peak value of the noise with inclining tongue is much lower than the straight one . the influence of the expanded angle of the shell of the fan on the noise was invested experimentally , and the optimal angle was got 倾斜蜗舌降噪的主要原因是：一是改变了从气流入口侧到风机轮盘的蜗舌间隙和蜗舌半径；二是改变了叶轮与蜗舌非定常相互作用的相位差，使其产生噪声也有相位差，迭加的结果进一步降低了噪声。另外，试验研究了不同蜗壳扩张角对风机噪声及效率的影响规律，蜗壳扩张角选择当否，对效率和噪声影响较大。
