NURBS曲线和曲面造型的工程应用研究

本文论述了NURBS曲线和曲面的理论和技术基础,并在CAD领域的工程实际应用中进行了探索。     

基于序列二次规划的赛车行驶线曲率优化分析

运用非均匀有理B样条方法描述赛道内外边界以及赛车行驶线,并运用序列二次规划算法对赛车行驶线曲率进行优化.该方法能帮助赛道工程师在比赛前分析赛道特性.     

基于突变级数法的福建省九大地市零售电子商务发展评价--以淘宝网注册店铺零售数据为例

电子商务是网络化的新型经济活动,是对传统商务的重大变革,是增强区域经济实力的战略选择。零售电子商务是信息技术在零售业中应用范围不断扩大的的历程,是一个地区精神文化和物质文化建设的重要指标,但是我国零售电子商务的整体水平还不高。本文选取了福建省九大地市淘宝网注册店铺的零售数据为样本,采用三阶样条插值模型对样本中的缺失数据进行估计,并使用突变级数模型综合评价各地市现阶段零售电子商务的发展状况,最后提出针对福建省零售电子商务企业的发展建议。     

利用三次B样条函数作等值线分析

为了解决传统地图等高线、天气图等值线手工分析的缺点,而以计算机自动分析作替代。通过考察插值、拟合几种数学方法,提出如何应用三次B样条函数,处理格点数据,寻找等值控制点,进行曲线拟合,这一方法具有客观化程度高、分析速度快且线条光滑等特点。     

Smooth interpolation on homogeneous matrix groups for computer animation

INTRODUCTION Homogeneous matrices are matrices used to represent geometric transformations for homogene- ous coordinates. Because they provide uniform rep- resentation for various transformations, they are widely used in the computer graphics community. As a homogeneous matrix corresponds to a geometric transformation, a curve on the set of homogeneous matrices can be taken as a piece of motion. Thus interpolation between those matrices is of high in- terest in many applications such as c…     

Effect of endpoint conditions on position and velocity near impact in tennis

Smoothing to obtain accurate position and velocity data near impacts in sport biomechanics studies is complicated by the accelerations of impact, endpoint effects and the smoothing technique used. Wrist goniometric data with two levels of random noise added were used to examine three endpoint modelling conditions for obtaining accurate position and velocity data at impact in the tennis forehand. The common approach of smoothing through impact created distortions of the position signal up to 100 ms before impact and resulted in consistent underestimations (-3.2%) of wrist angle and angular velocity (-67.9%) at impact. New linear and polynomial extrapolation conditions smoothed with all techniques provided lower root mean squared errors than the smoothing-through-impact condition, with discrete wrist positions at impact within 1.1% of the criterion data. Both the new linear and polynomial conditions can be used to make more accurate angular position and velocity estimates for tennis impacts, whereas the smoothing-through-impact condition creates spurious decreases in speed before impact that in the past have been assumed to be aspects of skilful movement.     

A fast direct point-by-point generating algorithm for B Spline curves and surfaces

INTRODUCTION Curve generating algorithms are important incomputer graphics and CAD/CAM. For some simplecurves such as line, circle, ellipse, etc., we have somerendering algorithms such as DDA algorithm for line,Bresenham algorithm and midpoint algorithm forcircle, Pitteway’s algorithm for ellipse, etc. (Bresen-ham, 1977; Pitteway, 1985; Ammeraal, 1987; Foleyet al., 1990; 1993). For rendering parametric curves and surfaces, apopular method is to compute a set of points along thecurv…     

基于多项式样条回归的基尼系数的算法

基尼系数的测算目前有分布函数法、几何计算法与曲线拟合法。本文推导出洛伦兹曲线的三次分段多项式样条函数拟合的简单表达式,再通过样条回归确定系数,从而可以比较精确地求出基尼系数,并在此基础上进行了实证分析,且计算结果比文献[6]的结果要精确。     

The Physics—Based Manifold Modeling Method for Free—form Surface Design

A new framework for free-surface design is proposed.Using Manifolds can generalize the spline scheme to surfaces of arbitrary topology,Physics-based modeling incorporate physical laws into shape representation to provide direct shape interaction.The combination presents a new method inherits the attractive properties of the manifold surface as well as that of the physcis-based models.     

在CNC编程中用圆弧样条函数拟合列表曲线的数学处理方法

在CNC编程中用圆弧样条函数拟合列表曲线的数学方法,将双圆弧相切法应用于实际,使加工零件轮廓光滑连续,通过对大跨度型值点的加密,使逼近误差最小,减少尖角过渡,避免了爬行．