复杂圆板形零件厚度的快速精密测量

复杂圆板形零件的快速和精密测量在工业生产中具有重要的意义,使用两个非接触式的激光位移传感器可实现圆板形零件厚度的精密和快速测量,影响测量精度的因素包括传感器的精度、传感器激光的同轴度、板的偏斜度、圆板上孔洞和沟槽的分布、测量环境温度的变化,通过合理设计测量装置的结构,减少两个传感器的激光的同轴度偏差和板的偏斜度,增加恒温装置消除环境温度对测量结果的影响,为了去除由圆板上的孔洞和沟槽所带来的含有粗大误差的数据点,综合采用了阈值法和差分法相结合的数据处理方法,并用去除了粗大误差的测量值序列的平均值作为测量结果,实验证明这种测量方法具有精度高和速度快的特点.     

基于电容传感器的大型工件圆度误差测量系统

轴类回转工件的圆度误差是衡量机床加工水平的重要指标.针对大直径轴类工件无法采用传统圆度仪进行圆度误差测量,介绍了三点法测量轴类回转工件圆度误差的理论基础、数学模型.采用非接触式电容传感器进行微位移测量,介绍了传感器结构与测量电路基本原理,搭建了适用于圆度误差测量基于电容传感器的硬件系统,应用虚拟仪器技术开发了可用于数据采集、线性校正、误差分离与评定的专用测试系统.最后进行了测试实验,通过对多次测量数据的分析评定测量系统的可靠性与精度.     

基于三坐标测量圆度误差测量的精度分析

本文主要介绍了三坐标测量的原理及应用前景,针对三坐标测量圆度误差所产生的精度问题进行分析,研究三坐标测量圆度误差时产生的测量误差并提出解决措施。     

基于VC的轴类零件形状误差评定系统设计

针对轴类零件形状误差评定指标圆度和圆柱度,提出采用高精度非接触的激光测距法测量距离方案,利用最小二乘法评定圆度误差及采用径向全跳动的测量方法初步评定圆柱度误差,通过VC软件设计轴类零件形状误差软件系统;结果表明:采用VC软件平台与测量系统的软硬件结合,能够在系统软件的可视化界面中同时实现对轴类零件圆度和圆柱度误差的测量与评定,圆度误差值为0.693276,圆柱度误差为0.720,不仅实现了形状误差的自动评定,而且提高了评定效率和降低了成本。     

基于改进随机Hough变换算法的开缝衬套圆度检测

圆度误差作为开缝衬套的形状误差之一,对开缝衬套冷挤压强化工艺的性能有重要影响,是开缝衬套几何精度的重要指标.探讨了一种基于图像测量技术的圆度误差测量方法.该方法通过对开缝衬套进行图像采集及图像预处理,提取出噪声较少的图像轮廓,然后利用改进的随机Hough变换,结合最小二乘圆法对开缝衬套进行圆度误差评定.实测表明,用该方法进行圆度误差的测量是可行的,并具有测量精度高、实用性强等特点.     

蒙特卡罗法评定圆度测量不确定度

形位误差测量的复杂性和测量结果评定的多样性,使形位误差的不确定度评定较为困难。因此,探索一种准确、高效的形位误差测量不确定度评定方法具有实际的意义。目前,主要根据《测量不确定度评定指南》进行形位误差不确定度评定,评定过程需要计算出误差模型中的传递系数。当误差模型复杂或者参数之间存在非线性时,评定结果准确性差。为解决该问题,在分析形位误差测量不确定度评定方法和评定原理之后,提出了采用蒙特卡罗法评定形位误差测量不确定度。该方法利用计算机产生伪随机数来模拟圆度误差的实际测量值,将其代入误差模型中,构成圆度误差的概率分布,并求出其期望值和方差,从而得出圆度误差和测量不确定度。试验数据显示,蒙特卡罗法评定圆度不确定度结果可靠、高效快捷,为几何量测量领域、误差分析与数据处理领域提供了新的方法,值得推广和应用。     

RV减速器行星架主要参数在线检测研究

针对行星架轴承安装孔的孔组位置度、平行度、孔径尺寸和圆度公差在线检测,提出一种快速检测的方法来实现多传感器对行星架关键尺寸进行测量。以行星架外圆为定位基准,采用接触式电感传感器对孔组位置度和平行度误差进行检测;根据被测孔径特点,采用非接触气动测量方式实现对行星架轴承安装孔内径和圆度的快速评定的方案,详细分析了各参数的评价方法。通过对研制出的样机与三坐标测量机的测量结果进行实验比对,实现孔组的位置度误差<3μm、孔径及圆度误差<2μm、平行度误差<1μm和整机测量节拍<1 min,结果表明本系统的测量方法和评定算法准确可靠,满足企业在线生产需要。     

数控磨床加工中自动检验装置的设计与应用

在零部件加工的过程中进行自动检测检验,已成为生产过程自动化的重要标志.针对数控磨床加工内圆与外圆,设计了外圆磨削单触点的自动测量装置与内圆磨削双触点测量装置;并为提高加工的精度和效率,采用尺寸控制原则设计了自动补偿装置.检验装置在自动与半自动磨床的实际运行中,表现出结构简单、稳定性好、加工精度高、检验效率高的特点.     

圆度和圆柱度测量虚拟仪器的开发

对基于虚拟仪器技术的圆度和圆柱度误差测量方法进行了研究,分析了测量系统误差对测量结果的影响,并提出了相应的解决办法.该测量系统采用误差分离技术,利用LabVIEW作为软件开发平台,以ADLINK PCI-8134运动控制卡、先导C000056微型工作台等作为运动控制部分,以NI的PCI-6010数据采集卡、联能CWY-DO-502电涡流位移传感器等作为数据采集部分,可一次性完成圆度和圆柱度的测量.研究表明,系统人机界面友好,有助于零件加工过程中的在线测量,减少废品率.     

基于极坐标测量的圆度误差评定算法

提出一种利用极坐标测量数据求解圆度误差的网格搜索算法,其原理是在最小二乘圆心周围按一定规则布置一系列的极坐标网格点,依次以各网格点为理想圆心计算所有测点的半径值,通过比较这些半径值,实现最小区域法、最小外接圆法和最大内接圆法的圆度误差精确评定。详细叙述了算法求解圆度误差的过程和步骤,给出了数学计算公式及程序流程图。试验结果表明,该算法可有效、正确地评定圆度误差。     

基于L297/L298芯片步进电机的单片机控制

在分析了步进电机驱动芯片L297/L298的性能、结构的基础上,结合AT89C52单片机,介绍实现驱动步进电机的一种简单方法.文中给出了控制原理图。实测表明,利用该方法设计的步进电机驱动系统具有硬件结构简单、软件编程容易和价格低廉的特点。     

Analysis of an upwind finite-difference scheme for a system of coupled singularly perturbed convection-diffusion equations

We study a system of coupled convection-diffusion equations. The equations have diffusion parameters of different magnitudes associated with them which give rise to boundary layers at either boundary. An upwind finite difference scheme on arbitrary meshes is used to solve the system numerically. A general error estimate is derived that allows to immediately conclude robust convergence – w.r.t. the perturbation parameters – for certain layer-adapted meshes, thus improving and generalising previous results [4]. We present the results of numerical experiments to illustrate our theoretical findings.     

Errors of linear multistep methods for singularly perturbed Volterra delay-integro-differential equations

This paper is concerned with the error behaviour of linear multistep methods applied to singularly perturbed Volterra delay-integro-differential equations. We derive global error estimates of A(α)$A(\alpha )$-stable linear multistep methods with convergent quadrature rule. Numerical experiments confirm our theoretical analysis.     

A parareal algorithm based on waveform relaxation

We report a new parallel iterative algorithm for time-dependent differential equations by combining the known waveform relaxation (WR) technique with the classical parareal algorithm. The parallelism can be simultaneously exploited in both sub-systems by WR and time by parareal. We also provide a sharp estimation on errors for the new algorithm. The iterations of parareal and WR are balanced to optimize the performance of the algorithm. Furthermore, the parallel speedup and efficiency of the new approach are analyzed by comparing with the classical parareal algorithm and the WR technique, respectively. Numerical experiments are carried out to verify the effectiveness of the theoretic work.     

Solving and analyzing PD0L inverse process

The importance of L inverse process is emphasized and an algorithm is given to realize PO0L inverse process. On the basis of algorithm analysis, this note discusses the possibility of apply-ing L inverse process to data compression and the difficulties in doing that.     

多模态信号同步策略研究与仿真设计

考虑新扩频方式、新调制方式以及频率共享等特性要求,单用途的同步接收已不能满足需要.以GPS系统及Galileo系统中的L1,L5频段信号为例,在对其信号机理、特性进行研究的基础上,重点通过相应的控制策略及数据处理方法,对通道、积累时间、处理方式等进行合理选取,从而达到对多模信号同步接收的目的.进一步的仿真实验表明了此方法的可行性、合理性及有效性.     

Order conditions for ARKN methods solving oscillatory systems

For the perturbed oscillators in one-dimensional case, J.M. Franco designed the so-called Adapted Runge-Kutta-Nyström (ARKN) methods and derived the sufficient order conditions as well as the necessary and sufficient order conditions for ARKN methods based on the B-series theory [J.M. Franco, Runge-Kutta-Nyström methods adapted to the numerical integration of perturbed oscillators, Comput. Phys. Comm. 147 (2002) 770-787]. These methods integrate exactly the unperturbed oscillators and are highly efficient when the perturbing function is small. Unfortunately, some critical mistakes have been made in the derivation of order conditions in that paper. On the basis of the results from that paper, Franco extended directly the ARKN methods and the corresponding order conditions to multidimensional case where the perturbed function f does not depend on the first derivative y^′ [J.M. Franco, New methods for oscillatory systems based on ARKN methods, Appl. Numer. Math. 56 (2006) 1040-1053]. In this paper, we present the order conditions for the ARKN methods for the general multidimensional perturbed oscillators where the perturbed function f may depend on only y or on both y and y^′.     

General linear methods for ordinary differential equations

General linear methods were introduced as the natural generalizations of the classical Runge–Kutta and linear multistep methods. They have potential applications, especially for stiff problems. This paper discusses stiffness and emphasises the need for efficient implicit methods for the solution of stiff problems. In this context, a survey of general linear methods is presented, including recent results on methods with the inherent RK stability property.     

Extended RKN-type methods with minimal dispersion error for perturbed oscillators

In this paper, extended Runge-Kutta-Nyström-type methods with minimal dispersion error for the numerical integration of perturbed oscillators are presented, which are based on the order conditions derived by Yang et al. (H.L. Yang, X.Y. Wu, X. You, Y.L. Fang, Extended RKN-type methods for numerical integration of perturbed oscillators, Comput. Phys. Comm. 180 (2009) 1777-1794). The numerical stability and phase properties of the new methods are analyzed. Numerical experiments are reported in comparison with some well-known high quality codes proposed in the scientific literature.     

基于拨号虚拟专用网协议的分析与比较

基于拨号的虚拟专用网（VPDN）可以在拨号基本结构上不花费任何费用，就可实现对Intranet安全的远程访问，实现VPDN的协议主要有PPTP、L2F和L2TP。本文阐述PPTP、L2F和L2TP实现VPDN的分析与比较。