二次曲面

A linear feasible direction algorithm is proposed to calculate reliability index of structure.

为克服当极限状态曲面方程非线性程度较高时应用一次二阶矩法求解可靠指标可能不收敛的问题，提出一种求解结构可靠指标的线性可行方向算法。

Because of the condition of 〓 for two neighbour parametricspline surfaces is too strong,here,instead of it,some simple and practicableconditions of 〓 resulted from the general theorem obtained by Prof.LiuDing Yuan in Chapter 1 were proved,and three 〓 triangular splinesurfaces schemes wre presented:one is piecewise cubic spline surface patcheshaving local 〓 and whole 〓 continuity based on the refined HCTtriangulation,another is the same degree spline surface patches but based onthe refined Powell-Sabin triangulation,the third is piecewise quartic splinesurface patches having local 〓 and whole 〓 continuity based on therefined P-S triangulation.

由于对参数曲面，一阶导数连续的要求较强，我们采用第一章从刘鼎元定理导出的简单实用的几何连续条件，讨论了基于HCT加细三角剖分和P-S加细三角剖分上的两种局部达一阶导数连续而整体有一阶几何连续的分片三次样条曲面构造算法，一种局部达二阶导数连续整体有一阶几何连续的分片四次样条曲面构造方法。

Aiming at the disadvantages of the present machining method of the propeller,such as lower machining precision and efficiency,needing more time of clamping and limited machining scope,a new machining method — the second order osculating machining method has been presented and used in the manufacture of the propeller ...

针对目前螺旋桨加工中存在的加工精度和效率较低、需多次装夹、适用范围有限等缺点，在分析螺旋桨桨叶曲面特征的基础上，提出了基于圆柱形刀具二阶密切加工螺旋桨的方法。

Aiming at the disadvantages of the present machining method of the propeller, such as lower machining precision and efficiency, needing more time of clamping and limited machining scope, a new machining method the second-order osculating machining method has been presented and used in the manufacture of the propeller by analyzing the curve surface characteristics of the marine propeller blade.

针对目前螺旋桨加工中存在的加工精度和效率较低、需多次装夹、适用范围有限等缺点，在分析螺旋桨桨叶曲面特征的基础上，提出了基于圆柱形刀具二阶密切加工螺旋桨的方法。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。