关于砝码量值比对的评述

广州计量检测技术研究院开展了广州市地区的砝码质量量值比对工作。由广州计量检测技术研究院作为主导实验室,负责拟写比对计划任务书、制定比对实施细则,确定砝码质量量值比对的参考值和比对结果评价方法,并进行最终的数据处理和评估。分析比对结果不满意的可能原因及影响比对结果的五个因素。通过对比对结果的分析与评述,能了解和评估各参加比对实验室的环境条件、仪器设备运行情况、人员技术水平以及质量保证体系的有效性,进一步促进地区质量计量工作的发展。     

基于GUM的比对数据处理方法和MCM方法比较

在举行区域性质量参数国际比对时,由于比对砝码的多样性以及参比实验室水平的不一致,传统的比对数据处理方法很难获得各实验室均认可的比对参考值。本文以APMP.M.M-K1比对数据为例,给出了基于蒙特卡洛的测量结果分析,并与其报告进行比较和分析。     

广东省砝码验证比对试验结果及分析

广东省质量技术监督局计量处、广东省计量科学研究所于１９９９年组织省内地级以上市计量所进行了砝码质量的验证比对试验（以下简称比对） ,本次比对旨在科学、公正、客观反映我省砝码质量量值传递工作的可靠性 ,了解和评估各参加比对实验室的环境条件、仪器设备运行状况、检定人员技术水平以及质量保证体系的有效性。另外 ,通过比对 ,有助于各实验室找差距 ,互相促进 ,共同提高砝码检定的工作质量 ,确保我省砝码质量量值传递准确可靠。广东省计量科学研究所作为参考实验室（以下均称为参考实验室）提供比对用砝码及其质量参考值。参加比对…     

M1等级大砝码计量比对分析

实验室间计量比对是质量控制管理中比较常用方法，是控制和衡量各实验室间能力的一个重要手段。通过实验室间的计量比对，能够考察实验室测量量值和出具测量结果的准确一致的程度，同时对实验室环境条件、检校技术人员水平和数据分析处理能力进行考察，能够保证实验室检校能力的可靠性和稳定性。M₁等级大砝码检校结果受衡量仪器、人员、环境等因素影响较大，其比对结果可以很好的反映出实验室的检校能力。文章以M₁等级大砝码为例，对实验室间计量比实施过程及结果进行分析。     

一次砝码国际比对

介绍了中国航空长城计量测试研究所质量校准实验室参加亚太地区国际实验室之间砝码比对的情况,给出了测量结果的不确定度分析。     

陕西省法定计量检定机构F_2等级砝码计量比对实例

介绍了陕西省法定计量检定机构F2等级砝码比对的目的、方法和内容,介绍了比对路线和比对要求。汇总了各参比实验室的实验数据,采用了主导实验室的量值作为参考值,最后进行了En值的计算,并对比对结果进行了分析。     

实验室检测结果内部比对满意度评价方法初探

0引言根据《检测和校准实验室认可准则》和《资质认定评审准则》的要求,为控制实验室的检测结果的准确性,维持实验室的检测能力,实验室必须对检测结果进行质量控制,实验室经常采用实验室内部比对来进行,但对于比对结果满意程度各实验室评价方法不同,有的实验室从真正意义上进行评价了,但有的实验室的评价尚不到位,从而失去了开展实验室比对的意义,更无法指导实验室来控制检测结果的准确性。本实验室对比对结果满意程度的评价进行的初步的探索,介绍如下:1利用标准物质进行检测结果比对满意度的评价利用有证标准物质进行实验室内部检测结果监控是一种有效的手段,有证标准物质在实验室方便易得,且有精确的数据和完善的不确定度。利用该方法进行的检测结果监控,可以用下面的方法评价实验室检测结果的满意程度。En=Xlab-XrefU2LAB-U2ref(1)式中,Xlab为实验室的测量结果;Xref为被测物品的参考值;Ulab为实验室获得认可的能力的扩展不确定度;Uref为参考值的扩展不确定度。Ulab和Uref的置信水平为95%。若En≤1,则判定实验室的结果为满意,否则判定为不满意。利用En值评价实验室内部检测结果满意程度,前提是必须正确评定该实验室...     

从验证比对试验结果的评定与分析谈对测量结果不确定度的评定

《中国计量》２０００年第６期刊登了《广东省砝码验证比对试验结果及分析》一文 ,文中用Ｅｎ 值法评定比对结果。Ｅｎ＝式中 :ｘｌａｂ———参加比对实验室的测量结果 ;ｘＲｅｆ———参考实验室的测量结果（参考值） ;Ｕｌａｂ———参加比对实验室的测量结果的扩展不确定度 ,置信概率Ｐ＝９９ % ;ＵＲｅｆ———参考实验室的测量结果的扩展不确定度 ,置信概率Ｐ＝９９ %。Ｅｎ值在０和 +１之间时表示参加比对的实验室测量结果与参考值之间是一致的 ;超过这个范围则说明参加比对的实验室的测量结果与参考值之间是不一致的 ,应对该测量进…     

水系沉积物中重金属检测的实验室间比对结果及分析

本文介绍了两家实验室参加的水系沉积物中重金属检测实验室间比对结果分析。实验检测使用水系沉积物标准物质作为比对样品,比对项目为标准品中Cu、Pb、Zn、Cd、Cr、As的含量测定结果,检测结果依据CNAS2014年新颁布的《能力验证结果的统计处理和评价指南》(CNAS-GL02:2014)中规定的En值法判定。比对结果表明,对于比对项目Cu、Pb、Zn、Cr、As,参加比对的两家实验室结果判定均为满意;对于比对项目Cd,A实验室结果判定为满意,B实验室结果判定为不满意。对于不满意的结果,通过对实验室内部检测过程的分析找出原因,从而促进该实验室在内部管理水平和检测能力的提升。     

转速可控型房间空气调节器能效标识备案实验室间比对试验结果分析与评价

为了保证转速可控型房间空气调节器能效标识备案实验室间比对试验时的准确性,制备符合均匀性和稳定性要求的标准样机,采用稳健统计技术对参与比对的实验室的全年能源消耗效率(APF)检测结果进行统计与分析。结果表明:在比对的43家实验室中,40家实验室结果为满意、3家为不满意,说明目前转速可控型房间空气调节器能效标识备案实验室的数据一致性较好。     

Erratum to: Interlaboratory Comparison of Five Standard Weights of Class F2 in Several Romanian Laboratories

This paper reports the results of measurements performed on five standard weights of class F₂, by several metrology laboratories throughout Romania. The comparison began in 2009 and concluded in 2010. Mass Laboratory of National Institute of Metrology (INM) acted as pilot laboratory (PL) and reference laboratory (RL) for the programme. Five standard weights of class F₂ (nominal values: 5?kg, 1?kg, 200?g, 100?g and 10?g) were sent to the participants. The laboratory??s results are presented for each weight, along with the associated uncertainty and the normalized errors of each laboratory, with respect to the INM. The results obtained by the participating laboratories in this comparison can be used to validate the measurement capabilities (in the calibration of weights) claimed/approved under the quality management systems.     

Interlaboratory Comparison of Five Standard Weights of Class F2 in Several Romanian Laboratories

This paper reports the results of measurements performed on five standard weights of class F₂, by several metrology laboratories throughout Romania. The comparison began in 2009 and concluded in 2010, Mass Laboratory of National Institute of Metrology (INM) acted as pilot laboratory (PL) and reference laboratory (RL) for the programme. Five standard weights of class F₂ (nominal values: 5?kg, 1?kg, 200?g, 100?g and 10?g) were sent to the participants. The laboratory??s results are presented for each weight, along with the associated uncertainty declared and the normalized errors of each laboratory, with respect to the INM. The results obtained by the participating laboratories in this theme can be used to validate the measurement capabilities (in the calibration of weights) declared under the quality management systems.     

Realization of the scale of high fiber optic power at three national standards laboratories

Nowadays the transmission powers in optical telecommunication networks are often hundreds of milliwatts. Such high power levels are known to cause several nonlinear effects, thus affecting data transfer. Therefore, accurate measurements of such high power levels are required. The general issues that are to be considered when one is realizing a scale for high fiber optic power are discussed. The scales of the national standards laboratories in Finland, Sweden, and Denmark are described, and the results of a trilateral comparison of these scales are presented. The power range of the comparison was 1-200 mW. The results show that the stated measurement uncertainties of the three laboratories (1.3%-2.9%, k = 2) are applicable over this power range.     

MOLECULAR WEIGHT EFFECTS OF OLIGOMERIC DISPERSANTS ON AQUEOUS ALUMINA SUSPENSIONS

The objectives of this study are to synthesize an oligomer (75% acrylic acid, 15% acrylamide, and 10% methyl acrylate) with different molecular weights and determine the effects of molecular weight on the dispersing ability of the oligomers. Molecular weights were calculated using Proton NMR spectroscopy for end-group analysis. Rheology and adsorption measurements of aqueous alumina slurries at various polymer dosages were acquired at pH 9.5. Based on the results of these studies, it was concluded that the molecular weight of an oligomer does have a significant effect on alumina suspensions. Moreover, there is an optimum molecular weight at which suspension viscosity is the lowest due to the amount of oligomer adsorbed onto alumina particles. In this study, oligomer C (1970 g/mol) with 2 mg/g of alumina dosage in 0.50 volume fraction alumina suspensions yielded the lowest viscosity and highest adsorption. Viscosity and adsorption values increased above and below 1970 g/mol molecular weight. In summary, efficiency of a dispersant is essentially related to the conditions under which it is used. Therefore, it is important to optimize all conditions, molecular weight and charge interactions being most fundamental.     

Improvement in Preform Weights from a 48-Cavity PET Injection Molder

John Jones (pseudonym), injection engineer for Corporation X, gave our student project group from Iowa State University the challenge of determining the most influential variables affecting weights of preform plastic beverage bottle produced by injection-molding machines. In addition to determining which variables are most important, we were charged with identifying settings for the variables that will produce optimal preform weights. We benchmarked the current injection-molding process to get an idea to typical performance. This allowed us to compare later experimental results to typical process output.

From company experience with the process, the team and Mr. Jones identified injection time, injection pressure, hold time, and hold pressure as candidates for the variables most influential on preform weight. The team devised a matrix of experimental conditions to study that consisted of combinations of high, low, and medium values of these process variables. After experimentation with the injection-molding process, regression analysis was used to help determine which factors are most influential in determining preform weight. The group determined that hold time and hold pressure are the two most influential factors in determining mean preform weight. The group also determined that hold pressure has the primary influence on the consistency of preform weight across the cavities in the mold. Using regression equations for mean weight and a within-die standard deviation, new machine settings for hold time and hold pressure were recommended. Additional runs were then performed to validate our recommendations. Ten runs were made with hold pressure set to 1140 psi and hold time set to 3.95 s. The average weight of 50 preforms from the verification experiment was 23.41 g with a standard deviation of 07 g. These results compare well to the engineering specifications of 23.9-22.9 g set on preform weights. A subsequent comparison of routine process monitoring data collected after implementing our recommendations with historical process data also confirms the substantial improvement provided by our analysis.     

Batch adsorption and kinetics of chromium (VI) removal from aqueous solutions by Ocimum americanum L. seed pods

In this paper batch removal of hexavalent chromium from aqueous solutions by Ocimum americanum L. seed pods was investigated. The optimum pH and shaker speed were found to be 1.5 and 121 rpm. The equilibrium adsorption data fit well with Langmuir isotherm. The maximum chromium adsorption capacity determined from Langmuir isotherm was 83.33 mg/g dry weight of seed pods at pH 1.5 and shaker speed 121 rpm. The batch experiments were conducted to study the adsorption kinetics of chromium removal for the concentrations of 100 mg/L, 150 mg/L and 200mg/L chromium solutions. The adsorbent dosage was 8 g dry seed pods/L. The removal efficiency observed for all the three chromium concentrations was 100%. The equilibrium was achieved less than 120 min for all the three concentrations. The adsorption kinetic data was fitted with first and second order kinetic models. Finally it was concluded that the chromium adsorption kinetics of O. americanum L. seed pods was well explained by second order kinetic model rather than first order model.     

Complete on-line determination of biopolymer molecular weight via high-performance liquid chromatography coupled to low-angle laser light scattering, ultraviolet, and differential refractive index detection

An optically modified high-performance liquid chromatography refractive index detector was developed to allow complete on-line determinations for biopolymer molecular weights. On-line concentration, refractive index, specific refractive index increment (dn/dc2)mu, and Rayleigh factor were determined under flow injection analysis (FIA) and size exclusion chromatography (SEC) conditions using low-angle laser light scattering, ultraviolet, and modified refractive index detection. This instrumental system is capable of determining absolute on-line molecular weights. The error and time requirements involved in conventional methodologies for proteins have been reduced. Sample quantities have been reduced from 150 to 200 mg, in conventional off-line methods, to less than 2 mg for on-line FIA and 0.5 mg for on-line SEC, if mass absorptivities (a) are known. Otherwise, the determination of a will be the most sample-demanding step, requiring about 3 mg of the pure protein. On-line measurements of (dn/dc2)mu are in good agreement with traditional off-line values established at Donnan equilibrium (usually within 5%). In addition, this technique provides true injected mass as determined by the UV detector, after chromatographic exposure where losses may occur, which is then used in the calculation of biopolymer molecular weight.     

Molecular plating of actinides on thin backings

Actinide targets on thick and thin backings are needed for experiments at heavy-ion accelerators. One of the efficient ways to prepare such targets is by molecular plating. Although many laboratories have successfully prepared targets on thick backings by this technique, it is quite difficult to make targets on thin backings (100 μg/cm² up to 1 mg/cm²). In recent years, we have plated targets on thin Ni and carbon backings, for example ²³⁴U targets on a 200 μg/cm² Ni backing. The Ni foils, evaporated on a copper substrate, are available commercially. We used these foils to plate ²³⁴U and afterwards we removed the copper by dissolving it in a mixture of ammoniacal trichloroacetic acid. In this way 400 μg/cm^{2 234}U targets were prepared on a 200 μg/cm² Ni backing. A 100 μg/cm^{2 243}Am target was prepared by plating onto a 75 μg/cm² carbon film left on its glass substrate for later floating. We found that a plating cell made from Teflon was difficult to use because it scratched the C film producing a liquid leak at the joint of the column and the C film. This sealing surface needs to be extremely smooth to avoid leakage. A column made of Delrin™ was then tried and did not produce any scratch on the carbon film surface. This column was used to prepare 100 μg/cm^{2 243}Am targets. Details of the technique will be presented.     

Ultrasound‒Mediated Synthesis of High‒Molecular Weight Polystyrene‒Grafted Silver Nanoparticles by Facile Ligand Exchange Reactions in Suspension

Ultrasound mediated facile ligand exchange method in suspension for the formation of polystyrene?grafted silver nanoparticles is reported. Amazingly, this method allows even grafting of very high molecular weight polystyrenes (up to 217 200 g mol^?1) having a single terminal thiol group at the chain end. Detailed studies are carried out to gain insights in the role of molecular weight of the ligands and the mechanism of the ligand exchange reactions. Key factors are determined to be the droplet formation by ultrasonification and low silver content, which enhances the availability of the terminal thiol end group significantly. The extraordinary compatibility of the ligand exchange method in particular regarding high molecular weights is attributed to hydrophilic orientation of the terminal thiol groups at the liquid?liquid interphase. This is proved conclusively by using an in situ method as a reference approach in which agglomeration occurs at considerably lower molecular weights due to the absence of preferred end group orientation within the polymer coil. In homogeneous phase only the chain length is found to be the crucial factor in stabilization of silver nanoparticles.     

Long-Term Accuracy of Time Comparisons via TV Signal along Radio Relay Links

A time comparison method, which is based on TV synchronization pulses sent along radio links, was proposed and successfully tested in Czechoslovakia in 1967. Experiments performed afterwards in Europe and the U. S. confirmed the significance of this method. The instability of the overall propagation time delay along the radio links (including the equipment) is the major source of errors for long-term timekeeping between remote laboratories. In 1969, a research project on this subject was initiated in Italy, using the comparison of simultaneous time measurements by the TV method and integrated phase measurements via a coaxial cable between two remote laboratories that were located in Rome and Turin, Italy. The results show that the discrepancy between the TV results and the direct comparison by cable, over periods of 100 days, is usually less than 3 ?s.