几何基础

The hand - drawing is not good for the second production and map - users. In this paper, the classification of folds is firstly dis-cussed. Based on Ramsay classification standard, drawing alded by computer of anticline and syncline have been tested to find a new arithmetic applica-tion.

以兰姆赛分类方案为基础，通过褶皱形态的几何特征分析，提出一种针对简单背，向斜构造的计算机辅助设计算法，并编写出相应的褶皱剖面形态的模拟程序，利用各种不同形态的褶皱实例进行试验。

The parameter equation, tangent, normal plane, the length of the arc, curvature, the basic equation of the spatial curve, torsion and the equation of the curve in flat surface etc.

为解决实际中各种空间共轭曲面问题，分析和评价各种传动装置的几何特性和传动性能，为探索新型的传动装置奠定基础。

Based on the geometric expression of the NURBS curve, a simple and effective method of curve and surface extension is put forward, and the blade surface is then successfully extended with the tangent vector by repeatedly applying the above method.

根据叶片的形状特征，以曲线的几何形式为基础，提出了一种简单实用的曲线曲面延伸方法，实现了切矢量连续的叶片型面的延伸。

The main contributions of the dissertation are concluded as follows: 1 A mathematical basis of the exchange of product data----the Set-based model mapping is established. The shape model mapping, such as the 1: 1, 1: n and n: n topological and geometrical mapping, is especially analyzed.

总结下来，论文做出了以下几个方面贡献：(1)建立了产品数据交换的数学理论基础——基于集合的模型映射，重点研究了在产品数据模型映射中具有代表性的形状模型映射，给出了一到一、一到多和多到多的拓扑几何映射分类。

On the basis of triangular Bezier surface modeling technology for 3-D scattered data points, some research work has been done in building the geometric model of ore deposit.

以离散数据的Bezier三角曲面造型技术为基础，本文探讨了Bezier三角曲面在建立矿床几何模型中的应用。

In this paper, according to the data format of surface in mechanics analysis software and based on computer aided geometric modeling, we present a novel intersection and trimming algorithm based on triangular discrete surface to realize the complex modeling of pneumatic membrane structure.

本文按照力学分析软件中曲面表示的数据格式，辅以计算机辅助几何造型的基础，提出了一种基于三角离散的曲面求交和裁减算法，实现了充气膜结构复杂外形的造型工作。

With the development of Ad Hoc networks, some researchers proposed geometric routing protocols to guarantee the delivery of the packet between any pair of nodes in the network, and the underlying network topology is also constructed by the ways of Delaunay triangulation.

随着无线Ad Hoc网络的发展，一些研究者提出了可以保证网络任意节点对之间分组顺利传输的几何路由协议，而这些协议的网络基础拓扑同样可以用Delaunay三角剖分的思想来实现。

A simplified kinematic model on locomotion of the undulatory long dorsal fin propulsion is based on the the observation and experimental data.

在"尼罗河魔鬼"巡航游动试验的基础上，通过对鱼体几何形态和柔性长背鳍波动的运动学分析，建立了"尼罗河魔鬼"长背鳍波动推进的简化运动学模型，并利用大摆幅伸长体理论分析了长背鳍波动推进的水动力学特性。

According to the practical engineering application, the reasonable effective lengths of compressed chords and braces are presented. In the end, the static behavior of multiplanar XX-joints are discussed, which used widely in practical engineering. An amount of joints with the variable joint parameters under lode-case are analyzed. Base on research achievement of uniplanar X-joints, a set of formula is proposed to predict the ultimate bearing capacity of multiplanar XX-joints, which are easy to understand in physical concept and simple in practice.

最后对实际工程中常用的空间XX 型节点进行了探讨，分析空间轴心受力XX 节点和空间平面内受弯XX 型节点的空间几何效应和空间荷载效应，进行大量系统的参数研究后，得到各自的效应系数，并且在矩形钢管混凝土桁架平面X型节点研究成果的基础上，给出了两种受力情况下节点的承载力计算公式，公式物理概念清晰、简单实用。

Methods Based on thin layer CT mandible image data and the USIS software by ourselves, the individual geometry of the complete range of mandible was well established, also the distinction between the contour boundary of cortical and cancellous bones was done automatically. A series of new effective CAD methods such as "no-seed region segmentation", non-parallel "best cross-section planes" and the algorithm employed a pair of B-spline curves fitting were used to accurately construct of 3D geometry surface model of the complete range of mandible in a man-machine conversation and automatic style.

利用CT薄层扫描下颌骨获取的断层图像数据，在自主开发的USIS软件的基础上，自动分辨骨皮质和骨松质轮廓边界，并对下颌骨采用"非种子区域分割"、非平行"最佳切割曲面"及"B样条曲线拟合法"一系列新型CAD方法进行人机对话自动重建精确的几何表面模型。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。