ON DESIGN METHOD OF THE PRECISION CAM PROFILE WITH RANDOM PROCESSING ERRORS

Based on probability and statistic, a design method of precision cam profileconcerning the influence of random processing errors is advanced. Combining the design with theprocess, which can be used to predict that cam profiles will be successfully processed or not in thedesign stage, design of the cam can be done by balancing the economization and reliability. Inaddition, an fuzzy deduction method based on Bayers formula is advanced to estimate processingreasonable of the designed precision cam profile, and it take few samples.

Real time remaining useful life prediction based on nonlinear Wiener based degradation processes with measurement errors

Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.

ON THE CONVERGENCE PROBLEMS OF ISHIKAWA AND MANN ITERATIVE PROCESSES WITH ERROR FOR Φ-PSEUDO CONTRACTIVE TYPE MAPPINGS

The purpose of this paper is to introduce the concept of Φ_pseudo contractive type mapping and to study the convergence problem of Ishikawa and Mann iterative processes with error for this kind of mappings. The results presented in this paper improve and extend many authors'recent results.

Iterative Processes with Errors for Generalized Set-Valued φ-Hemi-contractive Mapping in Banach Spaces

A new conception of generalized set-valued Ф-hemi-contractive mapping in Banach spaces is presented. Some strong convergence theorems of Ishikawa and Mann iterative approximation with errors is proved. The results in this paper improve and extend the earlier results.

Data processing and error analysis for the CE-1 Lunar microwave radiometer

The microwave radiometer （MRM） onboard the Chang＇ E-1 （CE-I） lu- nar orbiter is a 4-frequency microwave radiometer, and it is mainly used to obtain the brightness temperature （TB） of the lunar surface, from which the thickness, temperature, dielectric constant and other related properties of the lunar regolith can be derived. The working mode of the CE-1 MRM, the ground calibration （including the official calibration coefficients）, as well as the acquisition and processing of the raw data are introduced. Our data analysis shows that TB increases with increasing frequency, decreases towards the lunar poles and is significantly affected by solar illumination. Our analysis also reveals that the main uncertainty in TB comes from ground calibration.

Auxiliary error and probability density function based neuro-fuzzy model and its application in batch processes

This paper focuses on resolving the identification problem of a neuro-fuzzy model(NFM) applied in batch processes. A hybrid learning algorithm is introduced to identify the proposed NFM with the idea of auxiliary error model and the identification principle based on the probability density function(PDF). The main contribution is that the NFM parameter updating approach is transformed into the shape control for the PDF of modeling error. More specifically, a virtual adaptive control system is constructed with the aid of the auxiliary error model and then the PDF shape control idea is used to tune NFM parameters so that the PDF of modeling error is controlled to follow a targeted PDF, which is in Gaussian or uniform distribution. Examples are used to validate the applicability of the proposed method and comparisons are made with the minimum mean square error based approaches.

ERROR PROCESSING METHOD OF CYCLOIDAL GEAR MEASUREMENT USING 3D COORDINATES MEASURING MACHINE

An error processing method is presented based on optimization theory and microcomputer technique which can be successfully used in the cycloidal gear measurement on three dimensional coordinates measuring machine (CMM). In the procedure, the minimum quadratic sum of the normal deviation is used as the object function and the equidistant curve is dealed with instead of the teeth profile. CMM is a high accurate measuring machine which can provide a way to evaluate the accuracy of the cycloidal gear completely.

The Application of the GM(1,1) Metabolism Model to Error Data Processing of NC Machine Tools

This paper applied the gray system theory to error data processing of NCmachine tools according to the characteristic. It presented the gray metabolism model of error dataprocessing. The test method for the model needs less capacity. Practice proved that the method issimple, calculation is easy, and results are exact.

CHANNEL ERROR CORRECTION FOR WIDEBAND SAR-A JOINT MULTIPLE SUBPULSES PROCESSING METHOD

A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simultaneously,which frequently occur in wideband Synthetic Aperture Radar(SAR) systems.Based on the time-frequency relation of the chirp signal and the analyses of the channel errors in wideband SAR,joint multiple subpulses processing method is adopted to separate the image frequency component due to the I/Q channel error.Then,the complete description of the channel error is acquired for building the correction function,which is used to correct the radar raw echo in frequency domain.The validity and capability of this method are demonstrated by the experiments of the channel error correction on the high resolution SAR system with the effective bandwidth of 500 MHz.

Estimation for nearly unit root processes with GARCH errors

In this paper the limiting distribution of the least square estimate for the autoregressive coefficient of a nearly unit root model with GARCH errors is derived. Since the limiting distribution depends on the unknown variance of the errors, an empirical likelihood ratio statistic is proposed from which confidence intervals can be constructed for the nearly unit root model without knowing the variance. To gain an intuitive sense for the empirical likelihood ratio, a small simulation for the asymptotic distribution is given.

机器视觉技术在大坝表面变形监测中的适用性研究

针对大坝表面变形自动化监测中GNSS系统垂直位移监测精度低、费用昂贵和静力水准仪布设难度大、维修成本高等问题,利用机器视觉技术对大坝表面变形进行监测。室内试验结果表明,相机与标靶距离在100 m范围内,机器视觉的测量精度可达到亚毫米级,且水平和垂直变形位移精度相近。由误差分析可知,标靶与相机的距离与测量精度有明显的相关性,而环境因素是影响远距离监测精度的重要因素,并利用大坝视准线原理优化了机器视觉监测系统。最后以浙江省大力塘水库为试点,对大坝表面变形进行实时监测,结果表明,机器视觉技术完全可满足实际工程需求,且优化后的机器视觉测量技术可明显提高监测数据的精度和稳定性。

Influence of a multi-step process on the thickness reduction error of sheet metal in a flexible rolling process

Flexible rolling is a forming process based on thickness reduction, and the precision of thickness reduction is the key factor affecting bending deformation. The major purpose of the present work is to solve the problem of bending deformation error caused by insufficient thickness reduction. Under the condition of different rolling reductions with the same sheet thickness and the same thickness reduction with different sheet thicknesses, the thickness reduction error of sheet metal is analyzed. In addition, the bending deformation of sheet metal under the same conditions is discussed and the influence of the multi-step forming process on the thickness reduction error is studied. The results show that, under the condition of the same sheet thickness, the thickness reduction error increases with increasing rolling reduction because of an increase in work hardening. As rolling reduction increases, the longitudinal bending deformation decreases because of the decrease of the maximum thickness difference. Under the condition with the same thickness reduction, the thickness reduction error increases because of the decrease of the rolling force with increasing sheet thickness. As the sheet thickness increases, the longitudinal bending deformation increases because of the increase in the maximum thickness difference. A larger bending deformation is divided into a number of small bending deformations in a multi-step forming process, avoiding a sharp increase in the degree of work hardening; the thickness reduction error is effectively reduced in the multi-step forming process. Numerical simulation results agree with the results of the forming experiments.

面向机器人加工复杂轮廓误差控制的策略研究

针对机器人加工复杂曲面零件,提出一种面向加工轮廓误差的控制策略。通过向量的形式定义了机器人加工任务的轮廓误差,结合双向搜索、斐波那契搜索和球面线性插补算法,对机器人轮廓误差进行了估计;在此基础上通过将加权轮廓误差分量补偿到机器人任务空间的速度指令中,设计了机器人加工任务的轮廓控制策略。实验结果表明:对于位置和姿态轮廓误差,估计值与真实值的差异非常小,且与单纯的跟踪控制相比,位置和方向轮廓平均误差大约降低了30%,验证了所提加工轮廓误差控制策略的有效性。

非圆齿轮电火花线切割加工工艺参数对齿廓误差的影响

线切割加工非圆齿轮时电参数是影响齿廓误差的关键因素之一.设计正交试验,分别采用非圆齿轮齿根、齿廓中部和齿顶的最大齿廓误差对线切割加工非圆齿轮进行分析.通过方差分析方法和主效应分析法,研究线切割加工电参数峰值电流、脉冲宽度、脉冲间隔和跟踪对非圆齿轮齿根、齿廓中部和齿顶的齿廓误差影响规律.同时,对齿廓误差、加工时长和工艺参数进行回归分析,并建立回归模型,基于灰狼优化算法对回归模型进行多目标优化求解.通过研究结果可以得出线切割加工非圆齿轮齿廓不同部位的最优参数组合,可为实际加工提供参考.

基于线结构光扫描的工件高精度三维测量方法

为了提高工业中对复杂轮廓工件的测量精度和效率,设计了一套高精度非接触三维测量系统,并提出了一种基于线结构光扫描的工件轮廓三维测量方法。首先,利用高精度相机和三轴移动平台采集线结构光图像。然后,通过基于差分区间的灰度质心算法,精确而高效地提取出线结构光中心线,并生成原始点云模型。接着,对采集到的点云数据进行必要的点云滤波和精简预处理。最后,将预处理后的点云数据与CAD模型精确配准,进行工件表面轮廓的测量与误差评定。实验结果表明:测量工件轮廓高度的绝对误差小于0.07 mm,相对误差小于0.5%。所提出的三维测量系统及方法测量误差较低,能够实现工件的高精度三维测量,具有一定的工业应用价值。

考虑测量误差的CUSUM控制图对维纳过程的监控设计

目的 针对医疗设备存在的退化加速现象,提出对退化过程进行监控的方法,旨在有效监测到真实情况中退化加速的现象并进行预警,降低设备运维成本。方法 无论是退化率恒定还是退化率加速的维纳过程,其增量概率分布都是独立于其他时间区间增量的,本文运用上侧累积和(Cumulative Sum,CUSUM)控制图监控策略,并分析两类测量误差(乘性测量误差和加性测量误差)对控制图监控效率的影响。结果 运用蒙特卡洛仿真得到不同加速系数和测量误差下的平均运行链长(Average Run Length,ARL)和运行链长标准差,结果表明对于退化率恒定的固定效应模型,CUSUM对退化加速的监控具有稳健性,ARL的降低率均维持在43%左右;而在退化加速的随机效应模型中,监控性能会随着乘性测量误差(当乘性误差>0.1后)的增加而下降。结论 CUSUM控制图对医疗设备退化加速现象具有良好的监控能力,随着退化率的加速系数的增加,控制图能够越早发现异常退化加速状态。

基于改进SVM的电力工程造价预测

针对支持向量机求解速度较慢且用于预测电力工程造价的性能不理想等问题,提出了一种基于改进SVM的电力工程造价预测模型。该模型全面考虑了电力工程成本的组成要素并进行参数归一化处理,利用最小二乘估计改进SVM模型,同时采用遗传算法求解LSSVM的参数最优值,并通过优化后的GA-LSSVM模型实现对电力工程成本的预测。基于MATLAB仿真平台的仿真实验结果表明,模型预测的工程成本与实际值较为接近,归一化均方误差与平均绝对百分比误差分别为18.34万元和3.58%,且预测时间仅为256 ms,证明了其整体性能优于其他对比模型。

法兰盘的工艺分析与专用夹具设计

法兰盘是工业产品中常见的连接元件,其典型的加工工艺包括:零件图的分析、毛坯图的设计,机械加工工艺过程的编制、数控加工工序的编制、数控加工刀具的选用和数控加工进给路线图的绘制等。针对工序8中难加工的φ6mm斜孔,设计了一套钻床专用夹具,其中,钻模板设计成可翻转式样,钻套设计成快换式特种钻套。夹具采用一面两销的定位方案,限制了工件的六个自由度,达到了完全定位。最后,对夹具的定位误差进行了计算,验算后,确定该夹具的定位误差控制在图纸的加工精度要求之内,满足加工要求。

具Robin条件的高维扩散方程反问题正则化算法

初始热场和热源同时识别问题是一类热传导方程反问题.通过两个固定时刻的温度测量数据同时反演初始温度和热源项,提出了改进的正则化方法,获得了稳定化算法,给出了正则化参数的选取策略及正则化解的误差估计,对带噪声干扰的测量数据进行预处理以提高数据精度.数值算例验证了算法的有效性.

凹非球面的非零位干涉检测技术

为了实现凹非球面的快速、高精度与通用化检测,文中提出了一种将非球面当做球面,直接采用干涉仪检测的非零位干涉检测方法,并结合相应的数据处理方法,获得非球面的面形误差检测结果。首先,介绍了该方法的检测原理,建立了回程误差、调整误差的计算与去除模型,研究了面形误差的数据处理方法。然后,以两个不同非球面度的凹非球面为例,对其回程误差和调整误差进行了仿真计算,验证了该方法的有效性。最后,搭建了凹非球面的非零位检测实验装置,成功测量得到其面形误差。通过与自准直零位检测法或LUPHOScan轮廓测量法检测结果对比发现,两种方法测量得到的面形分布和评价指标具有高度一致性,验证了该检测方法的正确性。该检测方法在保证高精度测量的同时兼备一定的通用性与便捷性,为凹非球面的通用化检测提供了一种有效手段。