A velocity wave and a stress wave resulting from the stress variation are transmitted downward along the drill string.
悬点的应力变化产生速度波和应力波沿钻杆向下传递。
When the variation rate of field intensity is more than zero, plants absorb negative ions and form a downward plant nourishment transport electric current;
场强变化率大于零时，植物吸收阴离子，形成方向向下的植物养料输送电流（以下简称植物电流）；
When the variation rate of field intensity is more than zero, plants absorb negative ions and form a downward plant nourishment transport electric current;
场强变化率大于零时，植物吸收阴离子，形成方向向下的植物养料输送电流（以下简称植物电流）；
应用推荐