平面曲线

Plane analytic geometry is a important content in the mathematics curriculum of high school, which embodies powerful function of analytic method and algebraic method in the depicting curve. It reflects important idea of the combination of number and figure. Learning the course is very important for students to improve mathematics thought ability. Teachers and students are engaged in teaching and learning by the textbook, so it is necessary to analyse plane analytic geometry textbook.

平面解析几何是高中数学课程中的重要内容之一，它体现了解析方法和代数方法在刻画平面曲线方面的强大作用，反映了数形结合的重要思想，学习这部分内容对提高学生的数学思维能力具有十分重要的价值，师生正是通过教材这一载体从事教学和学习活动的，因此，很有必要对平面解析几何教材进行分析。

Curve resulting from the intersection of a circular cone and a ''.

由完全相交的一个圆锥体和一个平面的交集所形成的闭合的平面曲线。

A closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it.

由完全相交的一个圆锥体和一个平面的交集所形成的闭合的平面曲线。

Chapter 1 briefs the relation between invariance and computer vision and summarizes the research and application of invariance in computer vision. Chapter 2 first derives the transformations of three camera models, then makes the correpondences between the models and three typical geometrical transformation groups by analysing the transformations respectively. The correspondences supply the theoretical basis for applying geometrical invariants to resolve the problems of computer vision. In Chapter 3, we describe the geometrical invariant theory and prove some geometrical invariants of coplanar points, lines or conics by algebraic method. In order to use the invariants of conic pairs to describe general 2D shapes, we discuss the perspectively invariant representation of planar curves using conies in detail. A system consisted of two TMS320C25 and based on moment invariants is introduced in Chapter 5. The system can recognize more than 30 different shapes of object model or more than 10 plane models with similar shape in real time.

第一章简述了不变性与计算机视觉的关系，以及计算机视觉中的不变性研究和应用概况；第二章推导了计算机视觉中常用三种投影模型的变换关系，通过对这三种变换关系的分析，分别建立了这三种投影模型和几何学中的三种变换群之间的一一对应关系，为几何不变性在计算机视觉中的应用提供了理论基础；在第三章中，我们介绍了几何不变性的理论，并且用代数方法证明了共面点、直线、二次曲线的几何不变量和射影不变量；为了把二次曲线的不变量用于一般二维形状描述，在第四章中我们详细地讨论了用二次曲线实现一般平面曲线的透视不变性表示的方法；第五章介绍了用两片TMS320C25构成的、基于不变矩形特征的运动目标实时识别系统。

A new curvature-based algorithm in free-form curve fitting was proposed to fit a 2D NURBS profile with an arc spline ,where a new form of curvature formula with matrix representation was also proposed,and then the arc spline tool path with G~(1) continuity was generated.

给出了一种平面曲线轮廓的圆弧样条拟合及刀具路径生成算法，该算法面向零件轮廓的光顺性刀具路径生成，通过应用曲线的曲率关系，对以NURBS表示的被拟合自由曲线按参数递增的方向用G1连续的圆弧或直线段逐段拟合，并生成相应的圆弧样条刀具路径，从而实现零件曲线轮廓表面的光顺加工。

Basing on the 3D image data compression and in accordance with the structure characteristics of 3DLCS scanning data that the scanning data set of 3D surface can be considered as a curve set in 3D space, the thesis extends 2D curve Splitting compressing method to the 3D space and presents a 3D curve compressing method based on the curve compression and the color information compression. The 3D compressing effect is better.

在三维图像数据压缩方面，根据3DLCS的扫描数据结构特点（即可以将三维表面扫描数据集看作一个空间曲线的集合），将平面曲线压缩中的Splitting方法推广到三维情形，提出了一种基于曲线压缩和彩色信息压缩的三维数据压缩方法，取得了较好的压缩效果。

The concept of exponential transformations of rectangular Cartesiancoordinates is introduced, showing that a plane curve is more frequently expressed by a unionof four or fewer quadrantal equations defined uniquely in the respective quadrants whichthe curve covers and are therefore quadrant invariant, then the Fermat curve s with someof their geometric properties are formulated.

引入直角笛卡儿坐标幂变换的概念，说明一平面曲线是较经常地用4个或更少的象限方程的并集来表示的；这些象限方程是在曲线所在的各个象限中惟一定义的，因而是象限不变的。然后列出费马曲线的方程，并简述了费马曲线的一些几何性质

Mathematics A perpendicular, especially a perpendicular to a line tangent to a plane curve or to a plane tangent to a space curve.

正交：一条垂直线，尤指一条相对一条平面曲线的切线垂直线或一条相对一条空间曲线的平面切线垂直线

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。

If we implicitly represent the plane curves as the level lines of the surface, the evolution of the plane curves will lead to the evolution of the corresponding surface.

如果把平面曲线隐式地表示成曲面的水平线，由这些平面曲线的演化可得到相应的曲面的演化。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了