AutoCAD曲线的坐标变换和最值求取

给出了AutoCAD环境下的木工成型铣刀CAD系统中 ,用户输入的工件截形曲线通过坐标变换生成木工成型铣刀前刀面截形曲线的方法 ,并进一步讨论了样条曲线最值点的求法     

Binary Sequences Derived from Dickson Permutation Polynomials over Binary Extension Field

In this paper, based on a result of Lidl and Mullen (Mathematical Journal of Okayama University, 1991), the maximum length and the second maximum length that can be attained by cycles of Dickson permutation polynomial (of the first kind) with parameter 1 are studied. Necessary and sufficient conditions for these two lengths to be attained are given, which are connected with Fermat primes and Mersenne primes, respectively. Furthermore, a class of coordinate sequences that maintains a large period is obtained, which is shown to be the coordinate sequences derived from cycles of the second maximum length. Explicit formulas for their periodicity and shift-equivalences are also presented.     

Use of coordinate measuring machines and digital optical machines for the geometric characterization of circumference arcs using the minimum zone method

This paper presents an optimised method for the characterization of circular features of any amplitude, which includes the capture of geometric data, by means of the use of three-coordinate measuring machine or digital optical machines with a CCD camera, and its subsequent mathematical processing. The proposed model determines the radius and the circularity error, based on the minimum zone method, and to this end it uses linear programming techniques, the Simplex programming principles and the limaçon approximation. An experimental study on ring gauges and reference disks is provided, including a comparative analysis using the Chauvenet and Grubbs filtering procedures. Last of all, an uncertainty estimation method is proposed by means of the Monte Carlo simulation. The experimental analysis carried out on ring gauges and reference disks accredit that the algorithm developed, implemented in a Matlab® environment, gives reliable results for any circumference arc considered, regardless of its amplitude.     

适用于不对称系统的有源滤波器的两相控制法

本文提出了一种新型的有源滤骂的两相控制法。     

地理空间信息数据在PGIS中的应用

研究了基础地理空间信息数据在警用地理信息系统中的应用。通过对空间数据的精细组织,包括矢量数据与栅格数据的预处理与坐标转换,使其符合PGIS标准规范要求,然后利用专业配图切片工具,实现电子地图的网络发布。同时通过对公安部门的专业地址数据赋予空间信息的方法研究,总结了一套完整的公众信息数字化流程,大大提高工作的效率与准确性。     

旋转浇注流场数值模拟技术研究

旋转浇注过程流场数值模拟能否成功的关键技术之一是如何描述铸型在旋转过程中的位置变化及铸型内流体的速度变化,提出了坐标旋转法的基本思想并建立了相应的数学模型,通过编制程序对实际铸件的旋转浇注过程进行模拟计算,实践证明,模拟结果同实际浇6铸过程比较吻合。     

数控机床结构有限元分析方法

用有限元分析软件对数控机床进行分析时,能否获得较高精度的分析结果是关键问题。传统的结构分析注重研究某个单独的机械部件,缺乏考虑在实际工况下,切削力、重力等外部载荷作用在机床各部件之间的作用力和约束的相互关系对结果精度和可靠性的影响。在分析一立式数控镗铣床各部件之间装配关系的基础上,在结构相应位置上设置接触及节点坐标耦合,将实际工况下机床各部件间的关系转化到有限元模型上,使有限元分析结果更加贴近实际工况,通过对比有限元法和现场实验所得结果,验证基于分析各部件间的装配关系的机床结构分析过程是可行和可靠的。