The tests for the effects of jet position on dragbit cutting process were described.
就射流相对于刀具的四处不同位置对切割效能的影响进行了测试。
2
The bit is usually a dragbit fitted with either PDC or natural diamond cutting structures, but the core bit is unusual in that it has a hole in its center.
钻头通常属于刮刀型，装备有PDC或者天然金刚石切削齿，但取芯钻头的特别之处在于钻头中心有一孔。
3
And just as their long, heavy trains pose a burden to peacocks, the extravagant feathers of Anchiornis may have been a bit of a drag, literally.