曲面

Using combinatorial thoughts and topological methods,a closed curve system that contains the most number of non-contractible,pair-wise disjoint and pair-wise non-homotopic closed curves on the orientable surface is investigated.

利用组合数学的思想、拓扑的方法研究在可定向曲面上，一类含有个数最多的不可收缩的、两两不相交、互不同伦的圈系统及其性质，得出了关于这些圈的一些拓扑定性性质，并给出这些圈在曲面上的位置分布。

Motivated by this problem, in this paper, we give an upper-embeddable property of one kind of digraphs in orientable surfaces.

受此问题的启发，本文给出了一类有向图在可定向曲面上是上可嵌入的性质。

Chapter 7,discusses some unresolved problems about minimum genus and genus distribution of orientable embeddings for a graph,such as based on the joint tree model,calculation of minimum genus of complete graphs,determination of minimum genera for further types of graphs or even arbitrary graphs,etc.

第七章介绍了图的最小亏格及亏格分布领域中一些需要更进一步研究的问题，如如何利用联树模型计算完全图的最小亏格，以及如何通过刻画最小亏格关联曲面的特性来确定更广泛图类，乃至任意图类的最小亏格问题等等。

We establish several unique embedding results for 3-connected graphs on orientable surfaces which admit relatively large facial walks and representativity and hence generalize Thomassen's uniqueness theorem on LEW-embeddings.

本文给出了几个关于一般可定向曲面上嵌入图的唯一性定理。结果表明：一些具有大的面迹的可定向嵌入仍然具有唯一性。这在本质上推广了C.Thomassen在LEW-嵌入方面的工作。

Oriented boundary of surface.

曲面的定向边界。

In order to support sculptured surface design oriented to manufacturing, an embedded-computer-based platform was presented. Two function modules, constraint information modeling module and manufacturability analysis module, were developed and embedded in a CAD/CAM software system.

为了支持面向制造的曲面设计，提出了一个基于计算机辅助设计／计算机辅助制造系统的嵌入式计算平台，该计算平台主要包括约束信息建模和可制造性分析2个功能模块。

This paper simulated the unsteady free water sheet flow on bucket surface using 3-D non orthogonal Body-Fitted coordinate system.

在水斗三维贴体坐标系中，还推导了流体粒子在水斗曲面上的运动控制方程。

The necessary and sufficient condition of separation for homogeneous Scalar Helmholtz equation is both the existence of Stackel determinant and h 1h 2h 3S=f 1(μ 1)f 2(μ 2)f 3(μ 3)in orthogonal curvilinear coordinates system.

讨论了在正交曲面坐标系中齐次标量Helmholtz 方程变量分离的充要条件是Stackel行列式存在且h1h2h3S＝ f1（μ1）f2（μ2）f3（μ3）成立。

With differential geometry knowledge, the local characters of the blade surface are analyzed. Based on researching the cylindrical cutters osculating location, the methods to calculate the osculating location of the conic cutter and the torus cutter are discussed. A method of tool path planning based on the second order osculating method is preferred.

利用微分几何学知识，分析了螺旋桨桨叶曲面的局部特征，在研究圆柱刀二阶密切法规划刀位的基础上，探讨了圆锥刀和圆环刀的二阶密切刀位计算方法，采用二阶密切法规划刀位可以显著地提高加工精度。

Before machining,the NC programs must be checked to examine whether thetrajectory is right or not , whether the tool will overcut or without cut.

在数控加工中随着工件复杂程度的增加，尤其是鞋楦这样的复杂曲面，其数控加工程序的正确性无法靠人工检查。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。