切线锥面

The paper deals with curvature line and curvature characteristic of developable surface based on differential invariant of developable surface and it details curvature line and curvature characteristic of cone and tangent surface .

本文通过可展曲面的微分不变量，导出可展面的曲率线与曲率特征，并以锥面和切线曲面为例阐明这些特性的几何意义。

The methods of development for cones and tangent surface on C-Bézier curve and the complex surfaces are obtained.

首先，构造了C-B？zier曲线上的锥面和切线曲面，分别建立了它们到平面的等距映射，给出了C-B？

As the application of the methods given, involute helicoid, which is widely applied in engineering, is developed into plane. And the problem in plate metalwork, which is t he development of square-circle tie-in, is also solved by the method.

其一是钣金工中方-圆类接头的展开问题，该问题的解决是锥面展开方法的成功应用；其二是螺旋输送器的核心部件——铰龙的展开问题，它是切线曲面展开方法应用的典型实例。

First, a map between the cones and tangent surface on C-Bézier curve und two-dimensional plane is found respectively and then a ruled surface between two Bezier curves is constructed and a sufficient condition on its developablity is given.

zier曲线上锥面、切线曲面的展开方法。然后，构造两条空间B？zier曲线上的直纹面，给出了它成为可展曲面的一个充分条件，并通过保角保长原则，将其贴合到平面上。

The latter is a tangent surface with C-Bézier curve as spine curve.

四、给出了C-B？zier曲线上锥面、切线曲面以及复杂曲面的展开方法。

Based on the principle of surface development in differential geometry, the method of development for cone and tangent surface is given. Cone is developed in the unit ball way.

锥面的展开是利用单位球方法，确定直母线与平面上过定点射线之间的映射关系，进而展开曲面；切线曲面的展开则利用准线曲率在展开中的不变性，确定准线在平面上的展开曲线，再作与之相切的直母线，从而实现曲面的展开。

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％。