closed region meaning in English

闭域
封闭区域

Bounded closed regions
有界闭区域
If the line crosses an odd number of path segments , the starting point is inside the closed region and is therefore part of the fill or clipping area
如果该直线跨过奇数个路径段，则起始点位于闭合区域内并且因此是填充或剪辑区域的一部分。
When optical fiber bends , the refraction of towline rush pith changes with stress ' s function . then conduction and close region of the fiber change too
光纤弯曲时，光纤的纤芯折射率分布由于应力作用而发生变化，因此，光纤的通导和截止空域也发生了变化。