查询词典 plane curve

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。

Here, we will give an independent proof of the existence for inequality (2.1.3), and by the way, give an estimate on the width of the bi-enclosing annulus of closed convex curves in the plane. Secondly, in this part, we will introduce the notation of average geodesic curvature for curves in the hyperbolic plane, and investigate the relationship between the embeddedness of the curve and its average geodesic curvature.

其次，对双曲平面上的曲线引入平均测地曲率的概念，并讨论双曲平面上凸曲线的嵌入性与它的平均测地曲率之间的关系，其目的是为了将双曲平(来源：ABC论84文网www.abclunwen.com)面上曲线的性质与欧氏平面中曲线的性质作一些对比；最后，我们利用Minkowski支撑函数构造了一类新的非圆的光滑常宽曲线，其目的是想回答有关常宽曲线的一些未解决问题如是否存在非圆的多项式常宽曲线？

In this paper it is given a more effective formula about the direction angle of the main plane in the plane stress state.2. To introduce the principle and method for drawing 3-D graph with the compuer and for checking up with the computer cursor,to give outline of expressions of 3-D curve,outline of cursor meterage of well depth,well deflection angle and direction angle at any section.

介绍了在实践中总结出的计算机绘制与光标检测3维图形的原理和方法，给出了3维动态图形到屏幕坐标的变换式、各测点的平滑连接方法以及描绘与检测井眼轨迹曲线的典型应用，实现了空间井眼轨迹曲线的任意旋转、投影和给出了任一井段的井深、井斜角和方位角的光标检测软件。

From commonly used equation of calculating plane figure quadrature, formulas of calculating plane figure quadrature by applying curve parametric equation can be deduced.

从由曲线普通方程求平面图形面积的公式出发推出在各种情形下由曲线参数方程求平面图形面积的公式。

The shapes of the melting solid surface may be concave, convex or plane, while the perimeter of plane contact regions may be rectangular, circular, elliptical, parabolic and arc curve. The types of relative motion reviewed here are the movement of a solid PCM melting inside a heated capsule, the movement of a hot body through a melting solid medium, slide contact and rolling contact. The contact melting may be caused by temperature difference, pressure difference, friction and viscous heating. Finally, the research regions in the future are summarized.

内容包括各种形式的接触熔化，可归纳为：在接触形状上可以有凹、凸与平的面，而接触的周长可以是矩形、圆形、椭圆形、抛物线形与弧形曲线；相对运动的类型有固体相变材料在加热容器内熔化，加热体通过熔化固体介质的运动，滑动接触与滚、转动接触；引起接触熔化的原因有温差、压力差、摩擦与粘性热。

In this chapter, three kinds of target recognition methods are performed, which are:①Target recognition method based on the description of polarization parameter plane. The echo polarization states of target are projected onto the polarization state plane described by the ellipticity ε and the tilt angle τ of the polarization ellipse, the change of parameter following ferquency becomes the chart. According to the changing trait of the chart, the multidimensional polarization feature space of target has been contructed. Furthermore, a series of polarization feature parameters used in designing the structure of target recognition device are extracted, and they are insensible to the posture of target.②Target recognition method based on the description of Poincare polarization sphere. The echo polarization states of target expressed by Stokes vector are projected onto the Poincare polarization sphere. The conception of polarization ferquency stability, which is used in describing the dynamic distribution characteristics of the target echo polarization states on Poincare polarization sphere, has been defined. A group of polarization feature parameters used in designing the structure of target recognition device are extracted, and they are insensible to the posture of target.③Target recognition method based on the description of frequency sensitivity. In accordance with the conception of the polarization state distance defined on Poincare polarization sphere, the frequency sensibility of the physical structure property of target has been investigated, the frequency distribution feature curves in PSD domain are obtained, and targets'features are extracted by means of the curve-fitting method with Least Square Criterion.

这章具体研究了基于三种极化散射特性描述的相应的目标识别方法：①基于极化参数平面描述的目标识别方法，将目标回波极化状态投影到以极化椭圆参数，即椭圆率角ε和倾角τ表征的极化状态平面上，参数随观测频率的变化就形成了图，根据图的变化特点构造了目标的多维极化特征空间，并提取了不敏感目标姿态变化的极化特征参数组来设计目标的识别器结构；②基于Poincare极化球面描述的目标识别方法，采用Stokes矢量表征目标回波的极化状态，并将其投影到描述极化状态的Poincare极化球面上，定义了极化频率稳定度的概念用以刻画目标回波极化状态在Poincare极化球面上的动态分布信息，提取了准方位不变性的目标极化特征，最后设计了目标的识别器结构；③基于频率敏感性描述的目标识别方法，通过在Poincare极化球面上所定义的极化状态距离的概念，研究的是复杂目标物理结构特性对探测信号频率的敏感程度问题，获得了在极化状态距离下的频率分布特性曲线，采用最小二乘估计曲线拟合方法，它既用于极化特征的降维，同时又直接将拟合参数作为目标的分类特征。

For NC machining of plane section method, the machining path of tool cutting plane and implicit surface can be found, and the curve of the tool path is drawn by the positive-negative method.

把隐函数的优势应用到数控加工编程中，即对于截面法的数控加工，求出刀具切削平面与隐函数曲面的加工轨迹，再用正负法绘制刀具轨迹曲线。

This paper analyses the tangent equation of space curve and the derivation process of the curved tangent plane equation in the higher-mathematics teaching-materials, and shows another method to extract the tangent equation of space curve.

分析高等数学教材中空间曲线的切线方程和曲面的切平面方程的推导过程，给出求空间曲线的切线方程的另一种方法。

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。

For the application of Mathematica in the differential geometry,this paper introduces how to processe the curve curvature and the torsion questions,the graphic expression of the curvature and the torsions,and draw curves by the curvature and the torsions. Curvature ; torsion ; solution curve ; osculating plane ; natural parameter ; natural equation

利用Mathematica，只要输入有关系统命令就可以得到期望的结果。1曲率和挠率及其图形意义假设R3上的曲线一般参数表示为r=r它的曲率和挠率计算公式是：κ=‖r′×r&‖‖r′‖3τ=‖r′×r‖我们知道，空间曲线r=r在一点(s=s0)邻近的近似方程为ξ=sη=120κs2ζ=160κ0τs3通过近似方程可以确定曲线在其基本三棱形的三个平面(即密切平面，法平面，从切平面)上的投

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。