It is fine.It is a closed surface.
这是一个封闭曲面。
So, s is actually this whole closed surface here.
那么，S实际上是这个完整的封闭曲面。
So, that's by the divergence theorem using the fact that s is a closed surface.
所以那是通过散度定理得到的，其中使用了S是封闭曲面这一事实。
Let's say that we want to find the flux of the electric field out of a closed surface.
我们想要找出，电场对于一个封闭曲面向外的通量。
So, the divergence theorem gives us a way to compute the flux of a vector field for a closed surface.
散度定理为我们提供了一种，计算向量场通过闭曲面的通量的方法。
If you select two points on closed surface (a cylinder for example), the result may be unstable.
如果你选的两点在一个封闭的面上(例如圆柱)，那结果是不稳定的。
Integral absolute mean curvature is introduced to describe average curving of an orientable closed surface.
引入积分绝对平均曲率来描述可定向闭曲面的平均弯曲程度。
Integral absolute mean curvature is introduced to describe average curving of an orientable closed surface.
引入积分绝对平均曲率来描述可定向闭曲面的平均弯曲程度。
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