主曲率方向

Seawater intrusion mechanism and its 3D numerical simulation are further explored and researched in this paper. On the basis of the classical theory of fluid mechanics, it built the ideal model of seawater intrusion, and attained the speed in flow field which gradually decreased along with the increasing distance of curvature center along the principal normal in the course of seawater intrusion.

以流体力学经典理论为基础，建立了海水入侵内陆的理想模型，得到在海水入侵内陆的过程中沿弯曲流线的主法线方向，流场中速度随着距曲率中心距离的增大而逐渐减小，根据流线上的速度分布，并可表示出流场中的流线方程，可确定一定条件下海水入侵内陆的速度和方向。

Chapter 2 introduces some propaedeutics of classic differential geometry, which include the first basic form, the second basic form, normal curvature, main curvature, mean curvature, Gauss curvature, unit normal vector, main vector, etc.

第二章介绍一系列的预备知识，主要是关于古典微分几何中第一，第二基本形式的定义，法曲率，主曲率，平均曲率，Gauss曲率，单位法向量，主方向等的定义。

Principal curvatures and principal directions are obtained by computing in closed form the eigenvalues and eigenvectors of certain 3×3 symmetric matrices defined by integral formulas, and closely related to the matrix representation of the tensor of curvature.

通过计算3×3对称矩阵的特征值和特征向量可以得出主曲率和主方向，而该对称矩阵是由积分公式定义并且与曲率张量的矩阵表达密切相关。

We propose a unified method to approximate important geometric attributes, including normal vector, gauss curvature, mean curvature, principal curvatures and principal directions on point sampled surface. Based on MLS projection our method is robust to noise and stable to the sampling density.

曲面的微分性质包括法向量和切平面、高斯曲率、平均曲率、主曲率和主方向，在计算机图形学、机器视觉和计算机辅助设计等领域发挥了重要的作用，比如曲面绘制、内外测试、曲面重建、曲面简化、去除曲面噪声和模型分割等。

After analyzing the curvature of the forming surface and the relativ emotion between the forming surface and the curved tooth surface during envelope tooth cutting,the authors work out the equations for calculating the induced normal curvature and geodesic deflection,the principal curvature and direction of the tooth surface of this kind of circular-arc gear .

通过对产形面曲率和包络切齿时产形面与齿曲面相对运动关系的分析，推导出双向圆弧齿轮齿面的诱导法曲率、诱导短程挠率和齿面的主曲率、主方向等计算公式。

In this paper, we will study the definination of lines of curvature and the correlative conception, for example, normal curvature, principal direction and principal curvature and so on, the connection of lines of curvature and correlative conception, especially probe into the solution with the equation of lines of curvature and the equivalence with its determinant theorem.

本课题主要研究曲率线的定义及其相关概念如法曲率、主方向、主曲率等，曲率线与相关概念的关系，重点探讨了曲率线方程的求解及曲率线判定的等价定理。

According to the characteristic that the definition point of the Q matrix of wave front is always located on the extremum point on the axis of the beam, a three-dimensional formula for the rectificative factor of phase in complex ray paraxial approximation is proposed, which calculates the rectificative factor of phase directly without considering the calculation of the main directions and curvatures and the rotation of the coordinates, thus simplifying the paraxial approximation calculation by the complex ray expansion method.

根据波前Q矩阵的定义点总位于波束轴上极值点的特点，提出了三维复射线近轴近似相位校正因子计算公式。该公式不用考虑主方向和主曲率的计算和坐标旋转，直接计算相位校正因子，从而简化了复射线展开法的近轴近似计算。

Thus, to study tooth surface curvature is significant. However, from the published information, the curvature of face gear drives hasn′t been well studied until now. Based on the knowledge of differential geometry, a method for calculating principal curvature and principal directions for face gears is established, and thus the principal v...

文中利用微分几何原理推导了面齿轮传动的齿面主曲率与主方向，由此得出面齿轮传动中诱导法曲率的两个主值；开发了相应的程序；进行了实例计算；分析了传动中的主要参数对曲率的影响，所获得的结论对面齿轮传动的强度计算与分析具有参考价值

A method of CNC turbine blade profile abrasive belt grinding is introduced based on optimum grinding effect, where the direction of the axis of trolley wheel is consistent with that of minimum principal curvature on the contact point of turbine blade. And the cutter location path is determined, and then the NC code is derived from post-processing.

根据接触轮轴线与叶片型面接触点处最小主曲率方向重合可以达到最好的切削效果，设计了叶片磨削加工过程的运动方式，以此计算出刀位轨迹并进行后置处理得到 NC 代码。

Theory; the spatial meshing theory includes comparative motion, comparative differential and conjugative curved surface; and the application of meshing theory includes gear drive and worm drive. The spatial meshing theory is the main part of the course.

课程的重点讲解内容有曲线的参数方程、切线、法面、弧长、曲率、空间曲线的基本公式、挠率及平面曲线的基本公式等；曲面第一和第二基本公式，法曲率、主方向和主曲率、欧拉公式、短程挠率、欧拉公式和贝特朗公式推广、相对法曲率和相对短程挠率等；刚体的绝对和相对运动速度、相对微分和绝对微分、相对速度和相对微分、轨迹曲面的法曲率和短程挠率等；空间共轭曲面的啮合条件、诱导法曲率、两类界限点、等距共轭曲面、空间啮合的二次接触原理等；蜗杆传动的数学模型建立及啮合特性分析方法等。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。