中心线

In present paper a three-dimensional discrete vortex filament method is put forward to simulate the motion and bubble entrainment of an inviscid,incompressible vortex ring .

本文发展了三维离散涡模型用于模拟无粘不可压缩涡环的发展及其与气泡的相互作用，涡环被离散为平均分布在其中心线上的球形涡元，由Biot-Sarvart定律叠加每个涡元的诱导速度得到涡环的运动速度。

Tail set high, tightly curled, and carried over the centerline of the back.

尾巴：位置高，紧紧的卷在后背，超过背部中心线。

All the bases of the groove should be in the identical strip horizontal middle line

所有托滚槽形底部应在同一条水平中心线上

Stop valve is a valve with the flap moving along with the centre-axis of valve seat when it works.

截止阀是指关闭件沿阀座中心线移动的阀门。

By mechanical analysis of star wheel loading mechanism,the relationship between rotating speed of star wheel and its structural parameters is determined.

通过对星轮装载机构的力学分析，确定星轮转速与星轮结构参数之间的关系，在此基础上，得出了在一定的星轮转速条件下星轮轮齿的中心线。

The Examination of the Sine Bar for the Petroleum Thread Gage;2. The sine bar is a practical precision measuring implement which can measure indirectly or a machining tool for the precision angle by the sine principle.

正弦规是利用正弦函数原理对精密角度进行间接测量或加工的一种常用的精密量具或工具，常用于测量内、外锥体的锥角及外锥体的大小端直径，也用于测量角度块的角度、孔中心线与平面之间的夹角。

VALVE TO BE ACCESSIBLE AND INSTALLED HORIZONTALLY ON A VERTICAL SECTION OF LINE.

阀门要便于安装并且水平安装，阀门的法兰和管线中心线垂直。

Yellow colour indicates that the central line of that eclipse passes through Hong Kong lands.

资料依照香港境内可见最大食地点；黄格表示该次日食的中心线经过香港陆地。

The central line of the eclipse passes through the airport, so that sites within the city proper may be quite suitable, and Wuhan has a good assortment of public parks and waterside enclaves.

日食的中心线通过机场，所以呢这些地点可能适合作为观测点，武汉有不错的各式的公园和小洲岛。

For observers near the central line of a total eclipse, the limb corrections can be more closely approximated by using a smaller value of k, which accounts for the valleys along the profile.

对于全食中心线附近的观测者而言，使用较小的K值进行边缘修正更合适。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。