mean effective diameter

例句：

1. 1. The meaneffective diameter of the pipe is 20 cm.
   这个管道的平均有效直径是20厘米。
2. 2. The engineer calculated the mean effective diameter of the beam.
   工程师计算了梁的平均有效直径。
3. 3. The manufacturer claims that their product has a mean effective diameter of 5 mm.
   制造商声称他们的产品有5毫米的平均有效直径。