一种滚球法测橡胶粘度的视觉矫正算法研究

针对橡胶粘度测量精度不高、测试时间长、效率低的问题,对视觉测橡胶粘度的方法进行了研究,提出了一种利用滚球测橡胶粘度的视觉矫正算法。首先对滚球法测橡胶粘度的原理进行了说明,建立了视觉矫正模型,并对矫正算法进行了分析与实现;该算法根据滚球运动不同位置状态进行了分析处理,解决了不同状态下滚球中心位置的确定问题;最后通过粘度测量平台测量橡胶的粘度验证了矫正算法的可行性。实验结果表明:该算法得到的多次实验数据波动较小,满足工业生产的要求;该矫正算法因不存在近似求解,同时模型不受滚球到投影面距离的影响,算法的适用性与测试结果的准确性得到进一步提高。     

基于蒙特卡罗法与GUM法的直线度测量不确定度评定

由于形位误差测量的复杂性和测量结果评定的多样性,导致在实际测量结果中形位误差的不确定度评定成了难题。通过GUM法和蒙特卡罗法对直线度的测量不确定度进行评定。首先,根据最小二乘法得到直线度的误差模型;然后采用GUM方法对测量结果进行不确定度评定,采用蒙特卡罗仿真方法对测量值进行模拟仿真,从而得到直线度误差的不确定度;设置实验对比,通过数据分析验证了蒙特卡罗方法评定的可行性,为形位误差测量结果不确定度评定提供了更加简便的方法。     

皮托管测量风速时GUM评定不确定度的偏差修正

针对不确定度表示指南法(GUM)进行皮托管测量风速值的不确定度评定时,测量结果存在偏差的现状,为确认该方法的适用性,并获取其偏差的修正值,首先采用GUM和蒙特卡洛法(MCM)对皮托管测量风速值的不确定度进行评定;然后,通过JCGM 101:2008 GUM supplement 1给出的方法,对GUM的适用性进行验证;最后,将GUM与MCM获取的风速测量结果进行对比。结果表明,GUM方法依然适用于皮托管进行风速测量时的不确定度的评定; GUM评定的结果标准不确定度产生了负偏差,其相对于实测风速值的偏差率为-0. 611 8×10-5,对应的修正值为"0. 611 8×10-5×实测风速值",由于该值相对于实测风速值较小,因此,在应用时可根据实际情况,决定是否对其进行修正。     

毛细管顶空气相色谱法测定饮用水中三氯甲烷浓度的测量不确定度评定

本文讨论毛细管顶空气相色谱法测定饮用水中三氯甲烷浓度测量不确定度的主要来源,并对各不确定度分量和测量结果的不确定度进行评定。     

一种平板检定装置测量结果不确定度评定方法

检定装置的测量不确定度是确保量值传递准确性的重要指标参数,所以测量不确定度评定方法及过程尤为重要。本文介绍一种以电子水平仪为主标准器的平板检定装置的测量不确定度评定方法。依据JJG 117-2013《平板检定规程》规定的检定方法,从工作原理进行分析,构建数学模型,分析不确定度来源,进行了标准不确定度分量分析,阐述了计量标准测量不确定度的评定方法。     

基于拟蒙特卡罗方法的测量不确定度评定

测量不确定度是表征测量结果可靠性的一个重要参数.针对蒙特卡罗方法在测量不确定度评定时存在的收敛速度较慢以及仿真结果不稳定的不足,利用拟蒙特卡罗方法进行测苗不确定度的评定.拟蒙特卡罗方法使用拟随机数进行仿真计算.在测量不确定度的评定中,先基于Halton序列产生分布较为均匀的随机数,再利用数学变换转换成服从相应概率分布的随机数进行仿真评定计算.对圆柱体积测量不确定度的模拟评定结果表明,拟蒙特卡罗方法收敛速度快,计算结果较为稳定,可以简单高效地用于测量不确定度的评定.     

蒙特卡洛方法在GPS不确定度评定中的应用

不确定度的概算是新一代GPS测量不确定度管理体系的核心内容。《测量不确定度表示指南》提供的评定方法是基于不确定度传播率。可是当不确定度分量间的相关系数以及有效自由度难以有效确定时,依据GUM提供的方法就会遇到很大的困难。采用蒙特卡洛方法对新一代GPS不确定度进行了分析和概算,给出了评定复杂模型测量不确定度的原理和评定步骤,并对GUM法和蒙特卡洛法两种评定方法进行了对比,用实例验证了蒙特卡洛方法的实用性和准确性。     

圆弧检测结果的不确定度评定

介绍圆弧间接测量法检测中半径值及圆心位置的测量不确定度评定方法,比较测量不确定度评定指南方法(GUM)与蒙特卡洛方法(MCM)的结果差异及评定测量不确定度的流程,分析了小圆心角圆弧测量不确定度大的原因,在实际工作中应尽量避免检测小圆心角的圆弧。     

基于蒙特卡罗仿真方法的大尺寸测量不确定度分析

为评价大尺寸测量不确定度,特别是多站融合测量不确定度,引入蒙特卡罗仿真方法.该方法根据各传感器单元的概率特性重复采样,生成测量结果的样本,统计样本得到坐标测量不确定度,并利用计算机可视化样本的三维散点图.通过不同样本数对运算时问和准确性影响的实验,确定样本数为500.以激光跟踪仪为例进行实验,比较蒙特卡罗法、统计法和解析法三种方法得到的不确定度结果,吻合情况较好,其中与解析法比较最大偏差仅为2.7 um实验结果表明,蒙特卡罗仿真方法可以准确评价大尺寸测量仪器及多站融合测量不确定度,融合精度优于各局部精度.     

蒙特卡罗方法在复杂模型测量不确定度评定中的应用

<测量不确定度表示指南>(简称GUM)提供的评定方法基于不确定度传播律,主要适用于线性模型,在评定复杂模型时,由于灵敏系数、输入量间的相关系数以及有效自由度难以确定,这种方法存在很大的局限性.针对复杂模型的评定问题,<测量不确定度表示指南>补充文件1给出了用蒙特卡罗数值模拟方法通过分布传播评定测量不确定度的指南.本文参照补充文件1的要求,给出了用蒙特卡罗数值模拟方法评定复杂模型测量不确定度的原理和评定步骤,并用实例对上述两种评定方法进行对比.     

A magnetoelastic viscometer for on-line monitoring of viscosity of lubricating oils

The paper discusses the prospects for developing means for on-line measurement of the viscosity of lubricating oils, including diagnostic instrumentation based on magnetoelastic interaction. The theoretical basis for the development of magnetoelastic sensors and the main concept of measuring the fluid viscosity are presented. Two methods of measuring the viscosity are described. The first method is based on estimating variations in the natural frequency of oscillations of a sensitive element and the second involves analysis of the decay rate of the amplitude of oscillations. The design of the developed magnetoelastic sensor and the experimental results of comparing the two measurement methods are reported. The paper also presents the comparative results of measurement of the oil viscosity by a magnetoelastic sensor, a capillary viscometer, and a solid-state piezoacoustic sensor. It is shown that the reliability of the magnetoelastic sensor is high from the viewpoint of on-line monitoring; owing to its relatively low cost and ease of maintenance, it has wide potential for application in monitoring of lubricating oils in tribosystems.     

微量供油条件下润滑油液滴的生长与脱附

润滑油液滴的生长与脱附性能对于微量供油过程和微量润滑效果有重要影响。采用试验和数值仿真相结合的方法,研究微量供油条件下、在重力环境中的润滑油液滴在毛细管出口端的生长与脱附行为,考察毛细管管径和表面润湿特性变化对润滑油液滴脱附性能的影响。结果表明,润滑油液滴的生长与脱附是毛细力、黏性力、表面张力和重力等共同作用的结果;减小毛细管管径或增大润滑油液滴在毛细管表面的接触角,均可有效减弱毛细效应,降低润滑油液的爬移高度和脱附粒径,改善液滴脱附性能;毛细管管径由1.2 mm减小至0.7 mm过程中,液滴脱附粒径减小了4.5%;接触角由5°逐渐增加至90°的过程中,液滴脱附粒径减小了9.3%;通过选用低表面能材料制作微量供油的毛细管可以显著增大接触角。     

基于旋转法的发动机润滑油黏度检测技术研究

在传统旋转法基础上,提出一种新型的旋转式黏度在线测量方法。该方法利用流体力学相关理论对转子旋转时的黏滞力矩进行分析,通过建立传感器直流电机电流和油液黏滞力矩的关系来仿真计算油液黏度。研发一种发动机润滑油黏度在线检测传感器,通过高低温试验测试传感器对润滑油黏度的响应,并对传感器进行标定。结果表明,该传感器对油液黏度变化具有较快的响应与较高的灵敏度,结构简单,稳定可靠,克服了传统黏度计测量时间长、对环境要求苛刻、尺寸较大且价格昂贵的缺点。     

基于振动法的在线监测润滑油黏度传感器测试

开发一种基于振动法的在线监测润滑油黏度传感器,在恒温和变温状态下,通过实验室和柴油机台架实验测试传感器对润滑油黏度的响应,温度对传感器的影响及传感器的稳定性。结果表明,该传感器对润滑油黏度变化具有较高的响应和灵敏度,能准确测量润滑油黏度,且稳定可靠。     

Prediction of pressure–viscosity coefficient of lubricating oils based on sound velocity

The pressure–viscosity coefficient is an important parameter in tribology. Experimentally, it is calculated using the high‐pressure viscosity measurement. Also, the adiabatic bulk modulus is calculated using the sound velocity in the lubricating oil. Several lubricating oils are considered on the group basis such as traction oil, mineral oil, polyalphaolefin oil, perfluoropolyether oil and glycerol, depending on their molecular structure. Experimental pressure–viscosity coefficient is compared with the adiabatic bulk modulus. It is found that the pressure–viscosity coefficient increases exponentially with the adiabatic bulk modulus, and the relationship depends on the molecular structure of the lubricating oils. This study proposes two equations to predict the pressure–viscosity coefficient from the adiabatic bulk modulus based on sound velocity, one for the traction oil, and another for the paraffinic mineral oil and the polyalphaolefin oil. Copyright © 2009 John Wiley & Sons, Ltd.     

Measurements of blood viscosity using a pressure-scanning slit viscometer

A newly designed pressure-scanning slit viscometer is developed to combine an optical device without refraction while measuring blood viscosity over a range of shear rates. The capillary tube in a previously designed capillary viscometer was replaced with a transparent slit, which is affordable to mount optical measurement of flowing blood cells. Using a pressure transducer, we measured the change of pressure in a collecting chamber with respect to the time, p(t), from which the viscosity and shear rate were mathematically calculated. For water, standard oil and whole blood, excellent agreement was found between the results from the pressure-scanning slit viscometer and those from a commercially available rotating viscometer. This new viscometer overcomes the drawbacks of the previously designed capillary viscometer in the measuring whole blood viscosity. First, the pressure-scanning slit viscometer can combine an optical instrument such as a microscope. Second, this design is low cost and simple (i.e., ease of operation, no moving parts, and disposable).     

润滑油水侵对动压可倾瓦推力轴承润滑性能的影响*

针对核主泵、船用轴系等特定工况下推力轴承润滑油的进水问题,以46润滑油和68润滑油为例研究润滑油水侵对推力轴承润滑性能的影响。通过黏度测试获得润滑油中水分质量分数为0、0.5%、1.0%时的运动黏度,采用黏温曲线对润滑油含水前后的动力黏度进行表征。将润滑油的黏温关系代入推力轴承的润滑计算当中,获得不同含水量下轴承的最小油膜厚度、温升、流量及功耗等静态特性参数,并分析含水量对推力轴承起飞转速的影响。研究结果表明：润滑油含水后对最小油膜厚度和功耗影响较大,对温升和流量影响较小;随着润滑油含水量的增加最小油膜厚度和功耗均降低,而温升增大,流量减小;使用2种润滑油在不含水和水分质量分数为0.5%时的起飞转速都在50 r/min以下,水分质量分数为1.0%时起飞转速都在50 r/min以上,表明随着含水量的增加起飞转速增大。     

扩大粘度基准量程的研究

对扩大粘度基准量程作了研究 ,包括高粘度标准物质 (聚异丁烯 )性能及定值方法 ,特别是高粘度物质在毛细管法中残留量影响的研究。通过研究使粘度基准量程提高了一个数量级 ,从 1× 10 5mm2 /s提高到 1×10 6mm2 /s。该量程基准的测量不确定度为 0 7%～ 1% ,达到国际先进水平     

Continuous viscosity measurement of non-Newtonian fluids over a range of shear rates using a mass-detecting capillary viscometer

A newly designed mass-detecting capillary viscometer uses a novel concept to continuously measure non-Newtonian fluids viscosity over a range of shear rates. A single measurement of liquid-mass variation with time replaces the flow rate and pressure drop measurements that are usually required by capillary tube viscometers. Using a load cell and a capillary, we measured change in the mass flow rate through a capillary tube with respect to the time,m(t), from which viscosity and shear rate were mathematically calculated. For aqueous polymer solutions, excellent agreement was found between the results from the mass-detecting capillary viscometer and those from a commercially available rotating viscometer. This new method overcomes the drawbacks of conventional capillary viscometers meassuring non-Newtonian fluid viscosity. First, the mass-detecting capillary viscometer can accurately and consistently measure non-Newtonian viscosity over a wide range of shear rate extending as low as 1 s⁻¹. Second, this design provides simplicity (i. e., ease of operation, no moving parts), and low cost.     

Intelligent method for monitoring the state of lubricating oil

Mathematical decision-making methods for estimating the state of lubricating oil have been analyzed. It has been demonstrated that the most promising direction for solving problems of determining the performance of oil taking into account the existing uncertainty, ambiguity, incompleteness, and fuzziness of information on the object is the application of an expert system based on fuzzy logic, which provides objective and more substantiated decisions. The intelligent decision-making method on the state of lubricating oil and the structural diagram of the fuzzy logic method based on the Mamdani algorithm have been developed. An example of the implementation of the developed method for monitoring the lubricating oil state has been given based on the analysis of the following diagnostic parameters: total oil contamination measured in three spectral ranges, chemical destruction factor, and oil viscosity. A conclusion has been drawn on oil serviceability based on the analysis of the integrated numerical oil state factor. It has been demonstrated that the developed method provides a real-time objective estimation of oil serviceability and makes it possible to perform the timely maintenance of the tribosystem.