The criterion for judging flow reversals can be obtained through FDF theory.
而FDF理论分析可得出一个壁面（冷壁）或两个壁面均出现倒流的判断准则。
2
The simulation results illustrate that the FDF detected the faults occurred in different sensors effectively.
实验结果表明，故障诊断滤波器对发生在不同传感器上的故障进行了有效的检测。
3
When designing FDF system of compact spinning, the negative pressure drops resulting from spindles at the front and back of the machine should be kept within allowance.