工程实践及计算证明，堆石坝只有漏水问题，但坝体堆石不会被渗流冲失导致失事。
It is proved through the engineering practice and the calculation that the only problem with the rock fill dam is lea...
由于携砂液向地层的滤失以及通过筛管缝隙的流体质量交换，水平井砾石充填过程中冲筛、井筒环空两个流动系统均为复杂的变质量流。
During the process of gravel-packing in horizontal Wells, there are the filtration flow of the carrier fluid to the formation and the exchange flow through the screen slots.
当启动频率较高时，启动时会造成失步，而停止时由于惯性作用又会发生过冲，所以在步进电机控制中必须要采取升降速控制措施。
When the startup speed is higher, stepping motor will lose steps. While stopping, it will also lose steps because of inertia. So, it needs to take speed control measures on control of stepping motor.
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