n.活塞下降行程
A helical buckling of pumping rods has taken place in the course of downstroke of pumping. 认为抽油杆在下行冲程中可能因失稳而在有限空间内发生螺旋状弯曲。
Both the upstroke and downstroke of this pump push air into your balloons, making for smooth, nearly effortless inflation. 这个泵浦向上的一击和向下的一击推挤空气入您的气球, 做为光滑, 几乎不出力的通货膨胀。
So, when a bird banks right, its left wing moves faster on the downstroke while the right is faster on the upstroke, which slows the animal’s rotation. 因此，当鸟儿向右侧倾斜飞行时候，它的左翼向下拍打的速度要比右翼向上拍打的速度快一些，这样就可以使旋转减速。
The flow fields are different for the three phase motion patterns and there are two types of leading-edge vortex motion at an earlier stage of upstroke or downstroke. 三种相位下的涡流场形态各有不同，上挥（下拍）初期前缘涡的运动主要存在两种形态。
According to the calculating equations of the friction load on the rod string on the upstroke and downstroke, the friction load increases remarkably with the increa... 孤东油田八区部分见聚油井摩擦载荷的计算值与实测值的实例对比表明,二者的数值差距很小,表明计算方法可行。
