The shortcoming of traditional filter media, such as high and fluctuating resistance, low efficiency for very small size dust, highfrequency of regeneration etc.
The blood flow frequency imaging of peritrophoblastic artery flowing was searching by pulse Doppler, it was high extending flow and low resistance.
用彩色能量图显示低速血流，用脉冲多普勒寻找高舒张期低阻力滋养动脉血流频谱。
3
Because of high-frequency effects (namely skin effect and proximity effect), the current flowing through those windings may be not equally divided among them, resulting in high ac resistance.