Hyperbolic Error Analysis and Parametric Optimization of Round Body Form Tool

with the merits of the easy manufacture and the long service life and the processing the inside or outside form surface, round body form tool is extensive use in large scales production. Its main demerit is the big hyperbolic error which is caused in the process of processing cone, but about the discussion of hyperbolic error, there are two drawbacks in the current books and documents: (1) The error measuring plane is established on the rake face of tool, which doesn’t coincide with the actual measuring plane (axial plane) of work piece; (2) When the influential elements of error are analyzed, single parameter is only discussed. In order to overcome these demerits, the mathematical model of hyperbolic error on the axial plane of work piece is built in this paper when round body form tool processes cone. The fundamental reason which causes hyperbolic error when round body form tool processes cone is that the line profile replaces the curve profile of theory in the radial cut plane of tool in the design and manufacture of tool. In order to evaluate the mathematical formula of its error, firstly, the equation of cone of work piece must be established, secondly, the equation of cutting lip in the rake face is established, then, the profile equation of the radial plane of tool is evaluated on the condition that coordinate is changed, at last, the hyperbolic error is derived according to the equation and the substitutional line equation, and the error is converted to the axial plane of work piece which is coincided with the measuring plane. The actual calculation and the theory analysis indicated that if the cone length and the coning of the cone of work piece are fixed, the main elements which affect the hyperbolic error in the axial plane of work piece are the outside diameter R of round body form tool, the rake angle and the rear angle in "base point". If these three parameters are combined rationally, the hyperbolic error is minimum when round body form tool process cone, and the machining precision of work piece can be improved, on the condition that neither the work capacity of the tool design nor the manufacture cost of tool increases.

Performance Analysis and Evaluation of Geometric Parameters in Stereo Deflectometry

This paper presents a novel geometric parameters analysis to improve the measurement accuracy of stereo deflectometry.Stereo deflectometry can be used to obtain form information for freeform specular surfaces.A measurement system based on stereo deflectometry typically consists of a fringe-displaying screen,a main camera,and a reference camera.The arrangement of the components of a stereo deflectometry system is important for achieving high-accuracy measurements.In this paper,four geometric parameters of a stereo deflectometry system are analyzed and evaluated:the distance between the main camera and the measured object surface,the angle between the main camera ray and the surface normal,the distance between the fringe-displaying screen and the object,and the angle between the main camera and the reference camera.The influence of the geometric parameters on the measurement accuracy is evaluated.Experiments are performed using simulated and experimental data.The experimental results confirm the impact of these parameters on the measurement accuracy.A measurement system based on the proposed analysis has been set up to measure a stock concave mirror.Through a comparison of the given surface parameters of the concave mirror,a global measurement accuracy of 154.2 nm was achieved.

Modeling and Sensitivity Analysis of Navigation Parameter Errors for Airborne Synthetic Aperture Radar Stereo Geolocation

For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geoloeation errors for ground target points. In addition, utilizing true flight track parameters＇ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.

UNCONDITIONALLY OPTIMAL ERROR ANALYSIS OF THE SECOND-ORDER BDF FINITE ELEMENT METHOD FOR THE KURAMOTO-TSUZUKI EQUATION

This paper aims to study a second-order semi-implicit BDF finite element scheme for the Kuramoto-Tsuzuki equations in two dimensional and three dimensional spaces.The proposed scheme is stable and the nonlinear term is linearized by the extrapolation technique.Moreover,we prove that the error estimate in L^(2)-norm is unconditionally optimal which means that there has not any restriction on the time step and the mesh size.Finally,numerical results are displayed to illustrate our theoretical analysis.

基于改进遗传算法的飞行器光轴自动校准优化

飞行器光轴质量监控过程中,主要通过标准遗传算法完成光轴参数优化求解,易出现过早收敛和停滞现象的问题,导致校准优化后光轴偏移量依旧较大。为了降低飞行器光轴偏移量,提出基于改进遗传算法的飞行器光轴自动校准优化方法。以牛顿环干涉条纹为依据,采用正交实验方法实现光轴平行性自动校准处理,获取合理的光轴校准参数取值区间。针对飞行器光轴系统定义一个坐标系,在其中分析照准轴误差、经轴误差、纬轴误差和光轴指向误差,以最小光轴平行度综合误差为目标构建光轴自动校准优化目标函数。采用自适应交叉、变异概率改进遗传算法,对优化目标函数进行迭代求解,获取最佳光轴校准参数,实现飞行器光轴自动校准优化。实验结果表明,该方法优化处理后,飞行器高温光轴和低温光轴的偏移量仅为0.34 mrad、0.296 mrad,证明该方法降低了飞行器光轴偏移量,满足了飞行器光轴性能提升要求。

基于三相动态谐波分析的电能表误差检测方法

在检测电能表误差时,原始信号中谐波的干扰会导致检测结果与实际情况存在较大偏差。为此,提出基于三相动态谐波分析的电能表误差检测方法。在谐波分析阶段,考虑到谐波的动态属性会导致三相信号的采样执行效果难以达到同步,构建了余弦组合窗——旁瓣最低与最速下降窗,利用其对电能表离散信号进行截取,以此避免信号能量向临近谱线泄漏,再利用离散傅里叶变换对信号进行处理,实现对谐波的提取。在误差检测阶段,以离散随机信号的概率密度函数为导向,采用最优直方图曲线拟合法对其加以分析,并结合标准情况下电能表信号的分布状态,实现对误差的计算。在测试结果中,电能表误差检测结果的偏差始终稳定在3.0%以内。

某调水泵站流量优化分配方案的敏感性分析

针对调水泵站在提水过程中流量监测误差导致的流量优化分配方案可靠性和实用性不足的问题,基于粒子群算法构建泵站流量优化分配模型,揭示泵站开机台数和整体效率对流量监测误差的响应规律,并识别最优开机台数敏感区域,以指导泵站现地实时控制。以珠三角水资源配置工程鲤鱼洲泵站为例进行分析,结果表明:泵站最优开机台数敏感区域主要集中在开机台数调整过渡区间;流量监测误差一定时,最优开机台数敏感区域随流量增大而扩大,且开机台数敏感区域占比与流量监测误差绝对值呈正相关;流量监测误差导致泵站效率变幅集中在2%以内。因此,在制定泵站开机方案时,鉴于开机台数调整过渡区间处工况对流量监测误差较为敏感,故需特别关注相应工况处的流量监测误差,以减少非必要机组调控。

PSO优化算法在尾矿库空间预测中的应用

由于尾矿库的空间变异特殊性,传统的插值法预测精度不高,误差很大。为解决这一问题,考虑到粒子群算法在求解非线性问题时具有更强的全局搜索能力、并行性和多样性、适应性和自适应性,提出了一种基于粒子群算法优化Kriging模型来拟合尾矿库内部参数数据的克里格空间预测算法,旨在提高尾矿库内部参数信息的拟合精度,减少误差。为验证改进算法的有效性,采用多种预测评价指标进行分析,并与传统Kriging进行交叉验证分析,确定优化算法的可靠性。结果表明:相比于传统的加权最小二乘法拟合法,采用PSO算法拟合Kriging模型参数时,内摩擦角平均误差率降低了23.36%,黏聚力平均误差率降低了8.45%,证明算法可行和有效。

基于正交试验的单级双吸离心泵多目标优化设计

单级双吸离心泵由于运行平稳、噪声小、故障率低、易于维护等优点,已成为水利工程中最普遍、最通用的设备。本文以型号为950SY240-HY的单级双吸离心泵为研究对象,通过模型试验与数值模拟,以扬程和效率为目标函数进行多目标优化,在原型泵的基础上对叶片进、出口安放角、叶片包角、叶轮出口直径、出口宽度及叶片数这六个叶轮关键参数设计了L^(18)(3^(5)×2^(1))正交试验。通过极差分析,明确了各因素对单级双吸离心泵水力性能的影响程度,发现叶轮出口宽度、叶片出口安放角和叶片数对单级双吸泵扬程与效率的影响最大。相比于原始方案,正交试验最终确定的单级双吸离心泵设计方案,各工况点下扬程与效率有显著提高,叶轮内流态得到改善,流动损失减小,水力性能提高,额定工况下效率提高了4.1%,符合优化的目标。

转台运动误差分离与角度优化技术研究

为了解决测量转台运动误差时存在的多种误差耦合问题,提出了一种基于多点法的运动误差分离方法。首先,通过分析转台在回转过程中多自由度误差的运动特性,提出了一种端面四点误差分离方法,在分离出测量盘下表面的平面度误差的同时,可完成倾斜误差和轴向误差的解耦。然后,建立了该方法的误差传递函数,采用麻雀算法(SSA)进行优化,寻找不同阶次下受谐波抑制影响最小的最优布置角,提高了误差解耦精度。最后,通过仿真与实验的方式对该方法进行验证。仿真结果表明,端面四点误差分离方法对轴向、倾斜误差的分离精度(相对误差)分别为1.934%和9.177%。实验结果表明,分离的运动误差与转台标定误差相符合,验证了该方法能够精确获得转台运动误差。

基于GA-BP优化模型的红外CO分析仪温度补偿研究

光谱分析法是煤矿气体定量分析的重要技术手段。然而,当前广泛采用的便携式红外气体分析仪在现场测试过程中受环境温度影响较大,为提高气体分析仪的分析精度和适用性,围绕红外气体分析仪恒温加热的必要性、合理加热温度范围、测试数据误差优化模型等问题,开展了理论分析和实验研究。首先,搭建了涵盖温度补偿前、恒温加热测试、温度补偿后以及不同测试环境温度条件的红外气体分析仪实验平台,提出了实验步骤以及相应的分析方法;其次,在环境温度为25~45℃时,测试的CO气体体积分数为800×10^(-6),通过多次测试发现加热温度为45℃时,CO气体分析仪精度最佳,测试值最接近气体体积分数真实值;同时,选用CO(体积分数为10×10^(-6)~500×10^(-6))标准气体进行了精度测试,计算CO气体绝对误差仅为0~9×10^(-6),优于标准规定的误差范围;最后,设置-15~45℃的变温环境,对加热后的CO气体分析仪进行了温度补偿验证,测试得出环境温度越低,待测气体体积分数越高,则分析仪检测误差越大,最大误差可达110×10^(-6)。基于此,建立了BP、GA-BP神经网络误差分析模型,将环境温度、测试体积分数和标准气体体积分数与优化模型进行融合。对比发现:采用GA-BP神经网络模型得到的MAE值相较于BP神经网络降低了12.9823×10^(-6),且MSE、RMSE计算结果也验证了GA-BP模型在气体分析中的稳定性和可行性。

On the Linear Convergence of the Approximate Proximal Splitting Method for Non-smooth Convex Optimization

Consider the problem of minimizing the sum of two convex functions,one being smooth and the other non-smooth.In this paper,we introduce a general class of approximate proximal splitting(APS)methods for solving such minimization problems.Methods in the APS class include many well-known algorithms such as the proximal splitting method,the block coordinate descent method(BCD),and the approximate gradient projection methods for smooth convex optimization.We establish the linear convergence of APS methods under a local error bound assumption.Since the latter is known to hold for compressive sensing and sparse group LASSO problems,our analysis implies the linear convergence of the BCD method for these problems without strong convexity assumption.

煤质化验中误差原因及有效控制方法的分析研究

煤质化验作为煤炭质量控制的重要环节,其准确性直接关系到煤炭的使用效果与产业链的可持续发展。然而,在实际的化验过程中,由于多种因素的影响,化验结果往往存在一定的误差。本文旨在对煤质化验中误差原因进行分析,并提出有效的控制方法,以提高煤炭质量评价的精度和可重复性。

林用高空作业车调平机构的优化

为了提高林业高空作业车调平机构的调平稳定性,对调平机构进行了研究,对上调平机构的调平液压缸推力进行了分析,建立了上下调平机构六变量优化的数学模型,以调平过程中上调平油缸受力最小、调平摆动极值趋于0、调平摆动误差区间最小作为优化目标,以几何空间位置约束、三角形约束为约束条件,采用Box-Behnken Design(BBD)设计响应面实验进行参数优化。优化实验结果表明,优化后的调平机构误差区间最大值为0.422°,较优化前的误差区间降低了31.3%,上调平液压缸最大推力为308458 N,较优化前降低了1.8%。该研究可为高空作业平台液压调平机构的工作原理分析及优化设计提供参考依据。

直线电机驱动的数控机床误差分析与性能优化研究

直线电机技术作为现代数控机床驱动的核心,其精度和效率直接影响机床的加工质量和效率。文章旨在探讨直线电机驱动的数控机床在误差分析与性能优化方面的研究进展,先概述直线电机驱动数控机床的基本原理和特点,然后重点分析该类机床存在的主要误差来源,并在此基础上提出一系列性能优化方法。

An effective method for improving the accuracy of Argo objective analysis

Based on the optimal interpolation objective analysis of the Argo data, improvements are made to the em- pirical formula of a background error covariance matrix widely used in data assimilation and objective anal- ysis systems. Specifically, an estimation of correlation scales that can improve effectively the accuracy of Ar- go objective analysis has been developed. This method can automatically adapt to the gradient change of a variable and is referred to as ＂gradient-dependent correlation scale method＂. Its effect on the Argo objective analysis is verified theoretically with Gaussian pulse and spectrum analysis. The results of one-dimensional simulation experiment show that the gradient-dependent correlation scales can improve the adaptability of the objective analysis system, making it possible for the analysis scheme to fully absorb the shortwave information of observation in areas with larger oceanographic gradients. The new scheme is applied to the Argo data obiective analysis system in the Pacific Ocean. The results are obviously improved.

2TPR&2TPS并联机器人结构参数辨识

并联机器人末端位姿精度对其工作性能影响较大,建立有效的标定算法是提高机器人位姿精度的重要保证。本文以一种2TPR&2TPS并联机构为研究对象,首先对机器人进行运动学分析,采用全微分法得出机器人的误差模型,根据该模型得出机器人结构参数误差与末端位姿误差的量化关系,以及各误差项误差变动对末端位姿误差的影响规律;接着,建立参数辨识模型和标定效果评价函数,验证了参数辨识模型的有效性,再用该模型辨识机器人的结构参数误差;最后,修正运动学模型完成了机器人的误差标定。实验结果显示,标定后机器人的平均位置精度提升68.62%,距离误差均值由7.710 mm降至2.350 mm,精度提升69.52%,实验结果证明本文的标定算法有效。

几何误差测量方法应用分析——以机床导轨和机用虎钳直线度测量为例

设备的几何误差的测量是设备中零件制造、安装过程中重要的质量检测工作之一,测量结果是否准确直接关系到设备安装质量的好坏及后期使用精度。几何误差的测量方法虽然很多,但既能满足精度要求、又能便捷地用于工作设备在作业现场测量的测量方式方法就比较少。文章分别以机床导轨和机用虎钳导轨的直线度误差的测量为例,提炼出了设备实际测量过程中,两种不同工况下的四种常用的测量方案,加以分析、比较,最终推广出可操作性强、精确度高的最合理、最适应的测量方案,进而进行推广和应用。

基于几何图形参数优化的特型齿轮工业造型设计

考虑到工业造型设计方法对于特型齿轮几何参数设定较为不合理,导致特型齿轮传动稳定性较差的问题,提出基于几何图形参数优化的特型齿轮工业造型设计方法。首先,使用SolidWorks三维软件以及球面渐开线方程,构建特型齿轮三维参数模型;其次,使用双面法,设定特型齿轮轮坯的基础参数;再次,根据几何图形参数优化原理,对特型齿轮模型进行优化处理,设定模型约束条件对模型的相关参数进行调整,完成特型齿轮工业造型设计;最后,进行工件制造测试,并对此方法进行分析。测试结果表明:此方法使用后可使传动系统结构更加紧凑,在节约制造成本的同时,提升了齿轮的传动稳定性。

精密剪叉升降机构的设计与精度分析

针对自动装配机器人的升降平台安装空间大、承载性能差和位移精度低的问题,从运动的稳定性及精度出发,设计了一种精密剪叉升降机构。进行结构设计,建立了剪叉机构升降运动学及误差分析模型,使用MATLAB分析了升降平台位移与电机转角关系。利用微分原理求解了剪叉升降机构的位移误差模型并进行了误差合成与分配,得到了对升降平台输出位移误差因素影响大小排序为δ_(S)、δ_(K)、δ_(L)、δ_(φ)。经样机试验及精度检测,证明所设计的剪叉升降机构位移精度等性能均能满足设计要求。