Material unaccounted for ( called muf ) is often stuck in piping 物料去向不明损失量（ muf ）通常都是附在管道系统中。
2.
Muf maximum usable frequency 最高可用频率
3.
The muf and the possible maximum skywave field strength are calculated and are compared with the corresponding groundwave . and the conclusion is that the main propagation mode 200 kilometers on the sea is groundwave and the disturbance of skywave could be omitted 得出天波传播的最高可用频率、可能的最强天波场强，并与相应的地波场强进行了比较，阐明了海上200公里距离上的短波通信中电波主要是以地波的形式传播的，天波对地波通信的多径干扰问题可以忽略的结论。
