三次曲线

This algorithm firstly translates arbitrary parameter curves into the piecewise cubic-degree Bezier curves, then using the properties of Bezier curve we can get the tangent vector and the normal vector of every point on the approximation curve, and calculate the approximating offset curve.

此算法先将任意形式的参数曲线转化成分段三次Bézier曲线，利用Bézier曲线的性质容易得到逼近曲线的切向量和法向量，从而计算出其等距逼近曲线。

The pencil of plane quadratic lines is the foundation for studying plane cubic curve and hig-her plane curves.

平面二次线束是研究平面三次代数曲线和高次曲线的基础。

In chapter 1,we find out a kind of two-parameter invariant cubic curve family of a certainquadratic system which is important one for studying the distribution of limit cycles.

第二章讨论一般的二次系统具有三次代数曲线同宿环的充要条件，针对问题，我们采用了具有双曲鞍点的二次系统的标准形，利用仿射坐标变换，我们把系统和曲线同时简化，使问题得到了完满解决。

The history and representative work of methods of the developable surface modeling and surface development in the field of CAGD are briefly reviewed.

二、推导出了三次C-B？zier曲线导矢计算的简洁公式，证明了B？zier曲线的速端曲线性质对C-B？zier曲线不成立。

It's the first time that from the angle of computational mathematics combined with the structure model of parallel machine, the parallel degree of the relevant algorithms in orthopaedics clinic engineering modeling system, such as piecewise cubic Lagrange interpolation formula, piecewise cubic Hermite's interpolation formula, cubic spline, Chebyshev multinomial fitting algorithms, least square method and contour curve multinomial algorithms, were discussed.

论文首次从计算数学的角度并结合并行机的结构模式出发，讨论了在骨科临床工程造型系统中可能涉及的如分段三次拉格郎日插值公式、分段三次埃尔米特插值公式、三次样条函数、切比雪夫多项式拟合算法，最小二乘法以及轮廓曲线多项式求值算法的并行度。

The given method takes the Hermite interpolation curvcs and the cubic non-uniform B-spline curves as the special cases and unifies the representation of the curves interpolating the control polygon and the cubic non-uniform B-spline curves approximating the control polygon.

所给方法以Hermite型插值曲线和非均匀三次B样条曲线为特殊情形，将插值于控制点的曲线和逼近于控制多边形的非均匀B样条曲线统一起来。

For equidistant knots, the trigonometric polynomial curves of first and second degrees are C^1 continuous, and those of third degree are C^3 continuous.

对于等距节点，一次和二次三角多项式曲线是C^1连续的，三次三角多项式曲线是C^3连续的。

Cubic non-uniform trigonometric polynomial curves with multiple shape parameters are presented in this paper. They are C^2-continuous for a non-multiple knot vector and C^3-continuous for a uniform knot vector respectively. The ellipses can also be represented by them.

对于非均匀节点向量给出了一类带多个形状参数的三次三角多项式曲线，这类曲线具有三次多项式B样条的许多重要性质：对非重节点为C^2-连续，对均匀节点则为C^3-连续，能直接表示椭圆。

In general, the main contents and achievements of this paper consist of the following aspects:(1) Based on the characteristics of the transportation and the classic flow-occupancy inverse "V" model, implement polynomial fitting using least-squares algorithm and statistics method on flow curves to detect outliers which are proved to be not accord with practice through the actual implement, then use the moving average model to recorrect the outliers and absent.

本文根据交通领域的流量—时间占有率的倒&V&字型曲线模型，提出了一种基于曲线拟合的交通流异常检测方法，利用三次多项式的最小二乘法拟合流量/时间占有率曲线，并且利用分箱的思想对拟合好曲线上下部分分别采用基于统计的方法划分上下界，有效的识别异常交通流数据。

This paper establishes cubic spline function, analyzes subsection curve function and curve slope and curvature, at last decides to place the curve especial points which can be obtain easement curve length and other line parameters, such as the ZH point (end of line and beginning of transition curve), the HY point (end of transition curve and beginning of circular curve), the QZ point, the YH point (end of circular curve and beginning of transition curve), the HZ point (end of transition curve and beginning of line).

针对公路平面线形的8种组合类型，其线形元素特征则由最基本的直线、圆曲线、缓和曲线组成的特点，解析三次样条函数模型，得分段曲线函数、曲线斜率、曲率，从而确定曲线特征点（直缓ZH点、缓圆HY点、曲中QZ点、圆缓YH点、缓直HZ点）位置，进而得到曲线缓和曲线长度及其他线形参数。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。