Knot placement for piecewise polynomial approximation of curves

For piecewise polynomial representation of curves, an algorithm to create knots is presented. The aim is to minimize the interpolation error for a given number of knots or, conversely, the number of knots needed to interpolate within a tolerance. The method used is a modification of de Boor's knot placement scheme. The algorithm described in this paper has been realized in the CADCAM system SYRKO, a Daimler-Benz development for car body design and manufacturing.     

应用AFM观察小白鼠心肌核DNA片段的基因体外转录

用AFM直接观察到心肌核DMA片段中各种活性基因两头的调控序列可能与某些特定蛋白质等活性因子特异结合,形成大小不同的“基因节”,“基因节”之间有“间隔”起分隔作用。用AFM意外观察到在转录中心肌核DNA片段由3－4－5个基因节及其相对应的“间隔”,它们可能按某种“排列组合”,同时形成多种大小不同的“基因系”。各种“基因系”转录时分别形成相对应3倍基因节数量的多种RNA链状复合体,每一多种RNA链状复合体与相对应的“基因系”两边的接口相连。DNA片段上同一“基因节”可能按不同的排列组合,可能参与形成不同的基因系,故形成与基因系相对应的RNA链状复合体相交叉,可能参与形成不同的基因系,故形成与不同的基因系相对应的RNA链状复合体相交叉,起始转录点与基因系个数相同,DNA分子中全部基因系从相对应的起始转录点可能同时高效转录。本工作展示了未来运用AFM来研究在转录过程DNA分子中的基因节组成基因系的多样性和基因节转录的高效性等生物学反应的前景。     

ACCC导线芯棒高温“竹节”现象浅析

ACCC 导线整体上无疑是一种性价比优良的新型架空输电导线,能有效提高载流量,提高线路输送能力。但也有其自身的弱点,通过对ACCC 导线进行不同状态的耐高温性能试验,发现该导线耐张跳线段的碳纤维复合芯棒表面高温运行时会出现“竹节”现象,在设计中应予特别关注。建议直线段采用ACCC 导线时,耐张跳线段最好用常规的ACSR 钢芯铝绞线或采用耐热铝合金导线按双分裂布置。     

山东烟草根结线虫病病原种、小种鉴定初报

采集了山东１２个主要产烟县（市）的３９份线虫样本进行了病原鉴定。通过对线虫样本的雌虫会阴花纹观察和鉴别寄主试验进行了综合比较鉴定,结果表明,其中２３份为南方根结线虫１号小种,占５８．９７％;９份为爪哇根结线虫,占２３．０８％;７份为花生根结线虫２号小种,占１７．９５％。表明山东烟草根结线虫病病原种类以南方根结线虫１号小种占优势。但其他种类根结线虫危害比例正在上升。     

不停航施工中沥青混合料量的准确计算

准确测算机场不停航施工接坡时的沥青混合料量,在实际施工中至为重要。既要保证施工质量,又要保证施工人员、设备的安全撤离,使机场恢复正常使用起决定性作用,回返计算法确定混合料量可为不停航机场改造提供可靠保障。     

决策树在风险管理中的应用分析

该文对决策树的原理、定义、特点、构成要素、应用步骤和应用场合进行了深入浅出的论述,并举例作了详细说明,对于应用决策树这一风险型决策方法具有一定启迪。     

Approximation of multivariate functions and evaluation of particular solutions using Chebyshev polynomial and trigonometric basis functions

A two‐stage numerical procedure using Chebyshev polynomials and trigonometric functions is proposed to approximate the source term of a given partial differential equation. The purpose of such numerical schemes is crucial for the evaluation of particular solutions of a large class of partial differential equations. Our proposed scheme provides a highly efficient and accurate approximation of multivariate functions and particular solution of certain partial differential equations simultaneously. Numerical results on the approximation of eight two‐dimensional test functions and their derivatives are given. To demonstrate that the scheme for the approximation of functions can be easily extended to evaluate the particular solution of certain partial differential equations, we solve a modified Helmholtz equation. Near machine precision can be achieved for all these test problems. Copyright © 2006 John Wiley & Sons, Ltd.     

无结图及其若干性质

给出了结、无结图、有结图等概念，然后提出了图Ｇ０为无结图的充要条件，并论述了无结图的若干性质。     

Real-time accurate hand path tracking and joint trajectory planning for industrial robots(II)

Previously, researchers raised the accuracy for a robot’s hand to track a specified path in Cartesian space mainly through increasing the number of knots on the path and the segments of the path. But, this method resulted in the heavier on-line computational burden for the robot controller. In this paper, aiming at this drawback, the authors propose a new kind of real-time accurate hand path tracking and joint trajectory planning method for robots. Through selecting some extra knots on the specified hand path by a certain rule, which enables the number of knots on each segment to increase from two to four, and through introducing a sinusoidal function and a cosinoidal function to the joint displacement equation of each segment, this method can raise the path tracking accuracy of robot’s hand greatly but does not increase the computational burden of robot controller markedly. Foundation item: Foundation of the Robotics Laboratory, Chinese Academy of Sciences (No: RL200002) Biography of the first author: TAN Guan-zheng, Ph D, professor, born in Oct. 1962, majoring in artificial intelligence, robotics, and automation.