查询词典 parametric curve

In this paper, a region approximation idea that means using a "fat curve" with a width to approximate the offset curve is proposed, and a complete set of algorithms to approximate offset curve using disk Bézier curve are given and implemented. In the algorithms, the optimal and uniform approximate curve of the offset curve as the central curve of the Disk Bézier curve is found by using Remez method, and then the upper optimal and uniform approximation principle is proposed to compute the error radius function of the Disk Bézier curve. Thus, the whole Disk Bézier curve can be obtained. In the end of this paper, the approximate effect of the Disk Bézier curve is not only analyzed and assessed, but also some specific examples are provided.

提出用一条带宽度的"胖曲线"来逼近上述等距曲线的区域逼近思想，并建立与实现了圆域Bézier曲线等距逼近的整套算法，包括应用Remez方法求出等距曲线的最佳一致逼近曲线作为圆域Bézier曲线的中心曲线，提出上控最佳一致逼近的原理求出圆域Bézier曲线的误差半径函数，以及确定整条圆域Bézier曲线，最后还对该圆域Bézier逼近的效果做了分析和考核，并给出了一些具体实例。

The interpolation algorithm of introduced error compensation for complex parametric curve in space is proposed for the high precision interpolation of parametric curve on the basis of studying the first, second order taylor expression parametric curve interpolation algorithm and the plane parametric curves interpolation algorithm.

以一、二阶泰勒展开式参数曲线插补算法和平面参数曲线插补算法研究为基础，提出引入误差补偿值的复杂空间参数曲线高精度插补算法以实现空间曲线的高精度插补。

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。

For a general parametric curve/surface, we usually cannot compute its exact implicit form. Even though its exact implicit form can be computed, the curve/surface implicitization involves relatively complicated computation and the degree is higher. Moreover, it may have unexpected components and self-intersections. All these unsatisfied properties limit the applications of the exact implicitization. So finding curve/surface approximate implicitization has become a practical problem. In this paper, we present an algorithm to solve the approximate implicitization of a given parametric curve by using a quadratic algebraic spline curve.

由于精确隐式化过程不一定可以实现，即使可以实现隐式曲线曲面的阶数高计算复杂，并且具有不希望的自交点和奇异分支，从而限制了隐式化的运用，所以寻求参数曲线曲面的近似隐式化问题成为很实际又重要的问题，提出利用二次代数样条曲线来实现一般平面参数曲线近似隐式化的一种算法。

Space curve is one of the basic elements in geometric modeling, and its effective representation is the basis of modeling. Parametric representation based on features is a kind of high-level representation including semantic information. In Chapter 4, para- metric representations based on features for free form space curve are investigated, and a parametric model for the loop of plain knitted fabric is established, in which 5 parameters with practical meanings are used to represent the shape of a loop and the relationship between loops. A new shrinkage prediction method for knitted fabric are proposed based on the parametric representation and energy minimizing. Experimental results on some plain knitted fabrics illustrate the feasibility of the proposed method.

空间曲线是造型中最基本的几何元素之一，对其有效的表示是造型的基础，而特征参数化表示是其中一种包含语义信息的高层次表示，本文对空间自由曲线的特征参数化表示进行研究，建立了一种针织物线圈的特征参数化几何模型，采用5个具有实际意义的参数表示织物线圈的几何形状及线圈之间的位置关系，并将该模型与能量极小化的方法相结合，得到了一种能较好地预测针织物缩水率的新模型，对随机选取的一些针织布缩水预测实验表明了算法的可行性。

In the last chapter, on the basis of theories in paper [4, 5], the notions of strong mixing, weak mixing, generator and expansion of the variable-parametric dynamical system are introduced, it turns out that in variable-parametric dynamical system strong mixing implies weak mixing and then implies transitivity; it is proved that if and both are variable-parametric dynamical system, F conjugates with G , the members of F are communicate with each other and the members of G are also communicate with each other, what's more, they are both homeomorphism, then F is strong mixing implies G has the same properties; futhermore, we prove that F is strong mixing implies F Devaney chaos in the sense of modification in variable-parametric dynamical system and that F Devaney chaos in the sense of modification if and only if G Devaney chaos in the sense of modification when semi-conjugate with and they both are communicate and homeomorphism; at last, we illustrate that F has generator if and only if it has weak generator, and we also prove that if F is expansion, then F has generator.

在第三章中，我们在文[4，5]的基础上，提出了变参数动力系统拓扑强混合、拓扑弱混合以及变参数动力系统的生成子、扩张的概念；证明了变参数动力系统拓扑强混合蕴含拓扑弱混合，进而蕴含拓扑传递；证明了：如果，为两个变参数动力系统，F与G拓扑半共轭，且F两两可交换，G两两可交换，它们均为同胚映射，那么F拓扑强混合，则G也有同样的性质；本章还证明了变参数动力系统拓扑强混合蕴含F在修改的意义下Devaney混沌；在此基础上得出了：如果变参数动力系统与变参数动力系统拓扑半共轭，它们都两两可交换，并且它们均为同胚映射，那么F在修改的意义下Devaney混沌当且仅当G在修改的意义下Devaney混沌；得出了F有生成子当且仅当F有弱生成子；如果F是扩张的，则F有生成子。

The relations of parametric equations with the route coordinates and the part coordinates are found out according to the curve model,the parametric equations of middle and side stakes in circular curve and easement curve are derived,thence the value of parameters is obtained,the solution procedure is got.

根据曲线模型，找出线路控制坐标系与局部坐标系坐标之间的参数方程关系，推出了缓和曲线及圆曲线中边桩坐标的参数方程，代入已知量求得参数的值，给出了求解步骤。

Finally it analyzes the feasibility that using hydromechanics to analyze traffic flow by contrasting various characters between traffic flow and fluid flow. It analyzes influence of road alignment to basic expressway segment capacity by hydromechanics, and obtains viscous resistance and viscous movement differential equation when the vehicle drives on circular curve segment of expressway. And it infers that viscous resistance is correlated with sideway force coefficient, slope of crown and radius of circular curve. Radius of circular curve, sideway force coefficient and slope of crown are bigger, viscous resistance is smaller, the influence to capacity is smaller when the vehicle is running on nearside lane of circular curve; but radius of circular curve and sideway force coefficient are bigger, slope of crown is smaller, viscous resistance is smaller, the influence to capacity is smaller when the vehicle is running on fast lane of circular curve.

最后通过对比交通流与流体流的相似性，运用流体力学分析了道路线形对快速路基本路段通行能力的影响，求出了车辆在曲线路段的粘性阻力，建立了车辆在曲线路段的粘性运动微分方程，并由此推知，粘性阻力与横向力系数、路拱横坡度和圆曲线半径都有关系，当车辆在圆曲线外侧车道上行驶时，圆曲线半径、横向力系数和路拱横坡度越大，粘性阻力就越小，对道路的通行能力影响就越小；而当车辆在圆曲线内侧车道上行驶时，圆曲线半径和横向力系数越大，路拱横坡度越小，粘性阻力就越小，对道路的通行能力影响就越小。

Result: Scoliosis was identified in 58 cases with Marfan syndrome (38 males and 20 females), the prevalence rate was 42.03%, male-female sex ratio was 1.18:1, 6 cases were in younger than 10-year-old group. 12 cases were in 11~20-year-old group, 19 cases were in 21~30-year-old group, 11 cases were in 31~40-year-old group, 7 cases were in 41~50-year-old group, 3 cases were in 51~60-year-old group. Mean magnitude of Cobb angle in coronal plane was 26.8°±27.8°, the types of scoliosis curve included thoracic curve (36 cases), thoracolumbar curve (11 cases), lumbar curve (2 cases), double curve (6 cases) and triple curve (3 cases), apex vertebraes were convex to the right side among single curves in 38 cases while 11 cases were convex to the left side. Mean magnitude of kyphosis in sagittal plane was 14.3°±13.2°, 5 patients had thoracic lordosis and 40 patients had hypokyphosis and 12 patients had normal kyphosis.

结果：58例(42.03%)患者合并脊柱侧凸，男38例，女20例，男女患病率比例为1.18：1，其中≤10岁6例，11~20岁12例，21~30岁19例，31~40岁11例，41~50岁7例，51~60岁3例；平均冠状面Cobb角为26.8°±27.8°；胸弯36例，胸腰弯11例，腰弯2例，双弯6例，三弯3例；单弯中顶椎凸向右侧38例，凸向左侧11例；矢状面胸椎后凸平均为14.3°±13.2°，其中胸椎前凸5例，胸椎后凸不足40例，胸椎正常后凸12例，仅1例胸椎后凸45°；11例患者冠状面Cobb角＞40°，平均年龄15.9岁。

From a neutral gray balance curve, the curve Y, m, and the basic coincideut from neutral gray balance curve, the curve Y, m, and C coincideut basic curve the Y, m into a bow-shaped curve.

而从洋性灰不均弧线来看，Y、M弧线根基重分，而从洋性灰不均弧线来看，Y、M弧线根基重分，而C弧线则矮不入Y、M成为一条弓形弧线。

Now she was hungry and angry.She began to smoulder.

现在她又饿又气，她开始流露难以抑制的怒火。

You have placed our iniquities before You, Our secret sins in the light of Your presence.

诗90：8 你将我们的罪孽摆在你面前、将我们的隐恶摆在你面光之中。