如何表示曲面上的曲线,在处理诸如数控加工中的路径设计以及CAD/CAM等领域频繁出现的曲面裁剪问题时显得日益重要.给出了数据点的切方向(切方向及曲率向量或测地曲率值)指定而G1连续(G2连续)插值曲面上任意点列的方法.作为曲面上曲线插值问题的特例,还讨论了曲面上曲线的混合问题.基本思想是借助于微分几何的有关结论,曲面上曲线的插值问题被转化为其参数平面上类似的曲线插值问题.该方法能够用二维隐式方程来
Wetland is the conjunction of lake and terrene where human activities are concentrated. From the viewpoints of material transport and cycling in the terrene-lake system, wetland is the buffer where sa
讨论了山东省鸟类资源的种类组成、生态类型及地理分布,评价了鸟类资源的特点,指出了资源利用中存在的问题并提出了相应的保护建议。
With both sides of the Taklimakan Desert highway line as the study area, three typical aeolian sand landforms, i.e. complex dune ridge, barchan dune and flat sand land, were selected as sand beds for
NURBS curve is one of the most commonly used tools in CAD systems and geometric modeling for its various specialties, which means that its shape is locally adjustable as well as its continuity order,
本文讨论了在流行的CAD环境下进行零件和装配件公差分析。介绍了公差分析中的两个重要的分析方法。并用公差分析工具CE/TOL对某一行星减速箱中的一个间隙值进行了公差分析。极限状态分析法给出的结果是最保守的,而统计分析法从概率的角度出发,给出了更现实的结果。
A 1.5 Ma sporopollen record was obtained from a continuous loess-paleosol sequence at Chaona in the central Chinese Loess Plateau. It shows that (1) arid herbs of largely Artemisia and Chenopodiaceae
This paper takes Zhexi hydraulic region in Taihu Basin as a study area. On the basis of hydraulic analysis function of Arcgis8.3, the drainages were delineated by selecting the monitoring points and d