实验室动态

“铁路局计量管理信息系统”通过技术审查，晋中市水表计量检测站正式成立，德阳市水表检定站顺利通过计量标准考核，泰安市计量测试所通过国家实验室认可评审，临海市食品检验检测中心挂牌成立。[编者按]     

水表计量误差的原因分析与对策

本文从工作实际出发,对造成水表计量误差的原因作了系统分析,并根据国家有关规定,结合油田用水计量工作实际,在完善计量检测体系的基础上,从监督管理、检测方法等方面入手提出行之有效的措施,以提高油田水表计量和水费结算的准确性和公正性,从而避免因计量误差而带来的经济损失。     

水表计量误差的原因分析与对策

水表是企业节约和控制用水、降低生产成本的必须手段,水表的计量准确性直接影响供水单位的经济、社会效益,与千家万户的切身利益密切相关,属于强制检定的计量器具。文章从工作实际出发,对水表计量误差的原因作了分析,并根据国家有关规定,结合油田水计量工作实际,从监督管理、检测方法等几方面提出行之有效的应对措施,供大家参考。     

使用中水表计量性能变化趋势与风险监测技术研究

广州市开展使用中水表计量性能风险监测是全国首创的计量风险监测工作,通过对本地区各类水表进行分析,研究抽样方案,实施抽样检测,获得各种使用年份各种类型和使用环境的水表计量性能的统计数据用于分析,从而为计量行政主管部门制定逐步推进水表到期轮换或周期检定时间表提供依据。     

广东省龙川县城燃气表、水表首次强制检定现状分析

燃气表、水表首次强制检定是国家保障民生计量工作顺利开展的重要政策。作为具有代表性的后发县域经济体,本文分析的县级计量检测机构在落实国家政策过程中,结合燃气表、水表的首次强制检定现状,通过限期使用、到期轮换的方式,不断提高县域计量检测与监督的工作水平站,积极探索与经济发展相适应的质量监督与计量检测道路。     

在用水表产生计量超差的原因分析及防范措施

水表是自来水公司与用户进行贸易结算的惟一计量器具。水表在使用一段时间后出现的计量超差现象对维护自来水公司和用户之间的利益关系,提高自来水公司的水费回收率、降低产销差率等都将产生负面的影响。为此,我们进行了积极的探索和分析,现结合工作实践谈一谈在用水表产生计量超差的原因及防范措施。一、产生计量超差的原因1郾由于水表本身质量较差,导致安装使用后不久即出现计量超差现象(1)水表在出厂检定时就不合格或合格率较低。一方面是由于水表检定装置不合格或水表检定时水压波动太大;另一方面我们在企业监督检查中也发现:由于检定人…     

水表运行过程中计量性能变化及准确度分析研究

水表在实际运行过程中．由于各种不确定度因素的变化会造成其计量失准．所以．研究运行过程中水表的计量性能变化及其规律．提高计量准确度和供水商品率．是当前供水部门计量工作的重点和亟须解决的问题．提出该项目研究是针对大庆地区的特定条件（如水质特点、在用水表特性、用户用水特点等）,研究各种规格型号水表运行过程中计量性能的变化规律．确定水表的计量误差和运行时间以及运行水量之间的关系．从而绘制出各种型号水表运行过程中的运行时间、运行水量的计量特性曲线．掌握用水变化规律,以此加强计量管理,提高在用水表计量准确度。     

郊区水表首次强检工作的实践和探索

古诚嘉定地处上海市区西北角 ,经济发展速度落后于市区。由于历史、地理和行政的原因 ,在供水格局上形成了嘉定自来水公司一家独大 ,十几家乡镇水厂各自为政的局面。无论从供水量还是水表用户数量 ,嘉定自来水公司都占较大比重 ,紧紧抓住嘉定自来水公司的水表强检工作不松懈历来是我们贯彻法制计量要求的工作重心。而如何开展乡镇水厂供水范围内用户水表的强检工作也一直是我们努力实践与探索的内容。嘉定区水表强检站的建立 ,得到了市质技监局、嘉定区质技监局、上海市水表强检站在技术、人员培训、规章制度建设等的大力支持。嘉定自来水公…     

浅谈公路工程试验检测机构CMA计量认证

本文结合公路工程试验检测机构实际工作,阐述了计量认证在质检机构中的作用,结合作者单位的公路工程试验检测站在计量认证工作中的体会,总结出几点经验,供相关公路工程检测机构交流和参考。     

提高水表检定快捷准确的又一先进方法

本文将计算机技术引入供水计量工作,结合本厂的实际情况,采用先进的检定工艺方法-标准流量计法检定水表,从而使得检定水表过程与水表实际工况相仿,提高了水表的准确性,同时还可节约用水量,缩短检定时间,提高了劳动生产率。     

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.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

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.