Flux looks quite different in the plane and in space because, in the plane, it is just another kind of line integral, while in space it is a surface integral.

平面中的通量和空间中的通量有很大区别，在平面中，通量仅仅是线积分的另一种形式，而在空间中，它表现为曲面积分。

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The paper evaluates the limitations that semielliptical surface crack in a shaft is simplified to a unilateral crack in a finite boundary plane and a cross straight line crack in a semi infinite body.

评价了将轴表面半椭圆裂纹简化为有限边界平板的单边裂纹问题和半无限体表面穿透直线裂纹问题来处理的局限性。

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It is presented that the locus of a line crossed with each of two guide line and a guide conic not being on a common plane is a ruled surface of fourth order.

本文提出了由一条二次曲线和与该二次曲线不共面的两条异面直线为导线，与该三导线均相交的直线轨迹是一个直纹四次曲面，并讨论了二次曲线分别为椭圆、双曲线和抛物线时，形成的曲面的形状特征。

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