万能材料试验机的检定与维修

本论文提出万能材料试验机主要用于鉴定材料的力学性能指标，从而对材料的质量进行检定。根据试验机的检定数据，再根据不同试验机的结构原理。对试验机进行正确的分析后，找出故障并加以排除。了解万能材料试验机一些原理与常见故障，有助于计量检定人员顺利开展检定工作。     

恒定加力速度建筑材料试验机检定的自动化

正开发一个可在较短时间内自动完成材料试验机仪的检定工作,并能自动读取检定数据、处理误差数据、判断材料试验机是否合格,提高工作效率,降低检定人员劳动强度,减少人为误差的恒定加力速度材料试验机自动化检测系统具有良好的应用前景。恒定加力速度材料试验机自动化检测系统的系统框图如图1所示。一、标准测力仪的选择就国内外现状来看,检定材料试验机所使用的标准测力仪都是以模拟式传感器作为受力元件,难以实     

三等测力计(标准)的使用规则

1．在用测力计检定材料试验机时，必须遵照试验机检定规程来进行。     

一种材料试验机手动加荷微调装置的研制

材料试验机是测定金属材料、非金属材料、机械零件等机械性能、工艺性能的一种精密仪器。材料试验机的检定是力学计量的重要内容之一。为解决部分材料试验机检定时加荷速率不易掌控的问题,研制了一种通过手动控制加荷速率的微调装置,让材料试验机的检定更加方便、安全、高效、准确。     

甘肃省计量测试检定东部分中心进行现场检定服务重点项目

本刊讯近日,甘肃省计量测试检定东部分中心技术人员对庆阳境内雷西高速公路各标段实验室仪器设备进行了现场检定服务。为确保施工质量及检测数据准确无误,此次检定重点是压力试验机、万能材料试验机、抗折试验机拌和机、地中衡及     

WE系列液压摆锤式万能材料试验机的检定、力值误差的分析及消除方法

本文详细地介绍了WE系列液压摆锤式万能材料试验机的检定、力值误差的分析和力值误差的消除方法。阐明了作为一名称职的力值计量检定人员，不但要会检定试验机，而且还要会对试验机所产生的误差进行综合细致地分析，将超差的试验机词修到合格的范围之内。     

试验机的常见故障及解决方法

试验机是检测各种材料本身机械性能及工艺材料性能的重要设备,在日常工作中,从事检定和校准的工作人员经常会遇到试验机出现的各种各样的故障。本文主要介绍试验机在检定工作中遇到的各种故障及解决问题的方法。     

材料试验机的故障分析与排除方法

材料试验机主要用于鉴定材料的力学性能指标,从而对材料的质量进行检定.对材料试验机的故障进行分析并能排除,对试验机的操作和材料的鉴定具有重要意义.     

1级材料试验机示值误差的测量结果不确定度

本文介绍了依据JJG139-1999《拉力、压力和万能材料试验机检定规程》或JJG157-1995《非金属拉力、压力和万能试验机检定规程》,采用直接测量法,按JJF1059-1999《测量不确定度评定与表示》对1级材料试验机示值误差的测量结果不确定度的分析方法.     

材料试验机期间核查方法比较

正一、试验机期间核查概述一般来说,材料试验机检定/校准的有效周期为一年。在检定/校准计划之外还需要根据试验机状态编制期间核查计划。针对使用频率较大的试验机,在检定周期内,建议进行两次及以上期间核查。如果使用较少,也可以把核查时间间隔延长。除此之外,具备如下特征的试验机需要     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Numerical study of methods of linearization of the output characteristics of radio-frequency sensors of the level of dielectric media

Different constructions of the sensing elements of radio-frequency level sensors based on sections of long lines are numerically investigated by means of the Matlab program for the purpose of minimizing the measurement error caused by the nonlinearity of the output characteristic. It is shown that the nonlinearity is lowest for U-shaped designs. The nonlinearity factor KN may be regulated by varying the capacitance of a correcting capacitor connected to the input of the sensing element and (or) the length of one of the sections of the long line. In selecting an optimal capacitance of the correcting capacitor KN ≤ 0.15% for control media with dielectric permittivity in the range 2.2–30.     

Possibilities of Decreasing the Errors of Determination of the Height of the Pole of a Sessile Drop of Melt

We analyze the possibilities of decreasing the errors of measuring the height of the pole of a sessile drop of melt above its equator by determining the position of the equator according to the midpoints of vertical chords of the image of the drop. The optimal distance between these chords and the edge of the image of the drop is chosen within 10–20% of the radius of the equator. The proposed method guarantees the same level of errors of evaluation of the height of the pole and the radius of the equator, which enables one to substantially increase the accuracy of evaluation of the capillary constant and the surface energy of the melt according to the geometric parameters of the sessile drop.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.