某平面度检测机的设计

在一些工业领域,需要对产品零件的平面度进行检测;但是传统的检测方法都是在实验室完成的,且操作步骤繁琐,无法满足工业生产的需要。本文简单介绍了平面度的概念,同时探讨了使用SO-NY磁尺作为量具进行平面度检测的控制实现方法,解决了对只能在实验室平面度进行检测的问题,提高了现场生产效率。     

磨料密度测定结果的重复性和复现性分析

《JJF1001-1998通用计量学术语及定义》对测量结果的重复性和复现性作了定义,该定义与ISO等7个国际组织于1993年公布的《国际通用计量学基本名词（第二版）》是一致的。而《ISO5725-1994测量方法与测量结果的准确度》定义了另外两个术语：重复性限和复现性限。许多标准中常采用（ISO5725）中的重复性限和复现性限作为重复性和复现性定义,实际检测工作中所遇到的测量结果的重复性或复现性问题,也基本上都是重复性限或复现性限的定义所指的含义。因此,常把《ISO5725》中的重复性限或复现性限的定义作为重复性和复现性的第二个定义。本文通过分析磨料密度测定结果的重复性和复现性,说明如何分析影响检测结果的主要因素,以及如何评定两次测量结果的重复性和复现性。     

Evaluating the measurement capability of a wheel profile measurement system by using GR&R

Reliable data with less variation play a key role for acceptance of the usefulness of the measurement output of a wheel profile measurement system (WPMS) in a railway network. However, in practice, most studies are carried out without checking the reliability of data from such a system, which may lead to inappropriate maintenance strategies. To ensure the measurement capability of WPMS and to support robust maintenance in railway systems, this study has evaluated measurement data for the flange height, flange thickness, flange slope, and tread hollowing of rolling stock wheels by using gauge repeatability and reproducibility (GR&R). In this study, acceptance and rejection criteria for the precision-to-tolerance ratio (PTR), signal-to-noise ratio (SNR), and discrimination ratio (DR) have been employed to evaluate the measurement capabilities. For the purpose of illustration, we have implemented a new proposed approach. This approach involves both an analysis using graphs with four regions with a confidence interval (CI) of 95% and an analysis using a graph with three regions with only the predicted values; the latter type of graph represents an innovation made in this study. This graph has the advantages that it can visualize three different levels of data quality in same figure, namely “unacceptable”, “acceptable” and “good”, and also include a number of measures without becoming unclear, which are features that have been missing in previous presentations. The results show that the measurements of the flange slope are on an acceptable level, while those for the flange height, flange thickness and tread hollowing have to be rejected as unacceptable. The action proposed for increasing the quality of data on the flange height, flange thickness and tread hollowing is to enhance the calibration of the WPMS. In conclusion, GR&R is a useful tool to evaluate the measurement capability of WPMS and to provide helpful support for maintenance decision making. This investigation also shows that there is good reason to be careful when selecting measures and when interpreting the results, since, for a certain wheel profile parameter, when one measure is used, the results may be acceptable, but when another measure is used, the results may be unacceptable.     

检具随机误差的验收评定方法

介绍了四种常用的检具随机误差验收评定方法,并分析了各种评定方法的特点及适用性。     

Impacts of spectral variations in multiwavelength excitation method on measurements of fluorescently whitened papers

The multiwavelength excitation (MWE) method for measuring the colorimetric properties of fluorescent whitening agent (FWA)‐treated specimens illuminated by a standard daylight illuminant computationally approximates not the spectral power distribution (SPD) of the illuminant but the luminescent SPD excited thereby by a weighted sum of the luminescent SPDs excited by a few different narrow‐band illuminations. The weights are optimized for the actual SPDs of those illuminations and the bispectral luminescent radiance factors of typical FWA‐treated paper specimens. Since the latter is invariant among instruments once provided as the common numerical data, the variations of the narrow‐band SPDs give major impacts to the reproducibility of this method. The weights optimized for the varied SPDs, however, mitigate the impacts. For investigating how they impact, one basic illumination system and its 16 simple variation systems were built virtually. The basic system consists of three narrow‐band LEDs and one blue‐excited white LED, whereas the individual simple variation system has either the peak wavelength or spectral width of one of the four LEDs (including the blue LED in the white LED) varied. With those systems, seven FWA‐treated papers with the known bispectral radiance factors were measured computationally by simulating the procedure of the MWE method. The differences in the colorimetric values measured with the simple variation systems from those with the basic system are far below the just noticeable difference, which indicates that the MWE method can be a practical solution for better reproducibility in measuring FWA‐treated papers.     

Technical note: Development and evaluation of a standardized technique to assess blood perfusion in teats of dairy cows using power Doppler ultrasonography

Ample research has described the assessment of dimensional changes for different teat traits, whereas diagnostic techniques to reliably assess blood circulation in teats of dairy cows are limited. Here, we describe the development and evaluation of a scanning technique to quantify blood flow in teats of dairy cows using power Doppler ultrasonography. In 2 consecutive trials, 384 teat scans [trial 1, n = 256 (sagittal plane, n = 128; transverse plane, n = 128); trial 2, n = 128 (transverse plane)] from 16 cows were obtained by the same 2 operators. Perfusion intensity from single images (trial 1) and video images (trial 2) were assessed using a commercially available software program. Intraclass correlation coefficients (ICC) and concordance correlation coefficients (CCC) were used to assess interoperator reproducibility (agreement between measurements performed by different operators) and intraoperator repeatability (agreement between measurements performed by the same operator). In trial 1, interoperator ICC and CCC indicated poor agreement (ICC ≤0.26, CCC ≤0.26). Intraoperator ICC and CCC demonstrated poor agreement between duplicate measurements within operators (ICC ≤0.19, CCC ≤0.19). Modifications after trial 1 included (1) a different ultrasound device, (2) analysis of video clips rather than single images, (3) restriction to 1 sectional plane (i.e., transverse), and (4) a scanning sequence such that repeated scans within operators were measured one after another. Through these modifications, intraoperator repeatability in trial 2 yielded fair to good agreement, with intraoperator ICC and CCC over both operators ranging from 0.44 to 0.70 and from 0.57 to 0.69, respectively, whereas interoperator ICC and CCC showed poor agreement (ICC = 0.35, CCC = 0.34). We conclude that repeatable measurements of blood perfusion intensity of teats in dairy cows can be attained with power Doppler ultrasonography. Power Doppler ultrasonography is a suitable tool to quantify slow flow in small vessels and may be an acceptable diagnostic technique to assess changes in blood circulation that result from machine milking in teats of dairy cows, although further research is necessary to validate this hypothesis.     

Evaluation of Two Different Questionnaires used for Diagnosing Ocular Manifestations in the Sick Building Syndrome on the Basis of an Objective Index

The paper evaluates ocular manifestations as reported in two different questionnaires completed within one to Two weeks by 164 office workers in four town halls in Copenhagen. Among 14 previously investigated, these town halls constitute the two with the highest and the two with the lowest prevalence of the Sick Building Syndrome (defined as mucous membrane complaints such as eye, nose or throat irritation, and general symptoms such as headaches or fatigue several times a week). There was a highly significant rank correlation in each of the four town halls between the frequency of self-reported ocular manifestations in the two questionnaires. Furthermore, the eye complaints reported in both questionnaires were significantly correlated with an objective measure for eye dryness, investigated using a biomicroscope. By combining the two questionnaires it was possible to define subgroups using both frequency of eye complaints and consistency of reporting in the two questionnaires. The subgroup of 107 subjects with consistency in the frequency of their eye complaints in the two questionnaires showed a significantly higher correlation with the objective index than did the subjects with inconsistent reporting. Furthermore, with increased frequency of complaints and consistency of reporting, not only the prevalence of microscopically determined eye dryness, but also the number of up to 7 different eye symptoms per subject increased, and an increased percentage of these symptoms was found to be related to sensory reactions in the common chemical sense, which earlier has been postulated to be involved in the Sick Building Syndrome. In conclusion, the study shows that data from two different questionnaires on self-reported ocular manifestations associated with the Sick Building Syndrome are reproducible and associated with objective dryness in the eyes.     

Accuracy and precision in amino acid analysis

Five laboratories collaborated in a two-part study to improve and measure the accuracy and precision of amino acid analysis. The results of the unpublished first part allowed each laboratory the opportunity to optimise their own procedure. In the second part of the study reported here, three purified and six conventional proteins were analysed, each after three different preparation procedures (normal and extended acid hydrolysis, and following preliminary oxidation). Preparative effects reported in the literature were confirmed though not uniformly, and there were other, often unique, preparative effects. Well documented preparative effects are essential in matching analytical work to differing requirements. Results from one laboratory were excluded from further statistical analysis because of high replicate variation. The repeatability (within laboratory) coefficient of variation was 4.1% and for reproducibility (between laboratory) it was 13.1%. Discrepancies between best amino acid estimates for purified proteins and estimates calculated from published sequences (P < 0.01) provided evidence of bias in five amino acids from one laboratory and in one from another. When P < 0.01 was used as the discard threshold for conventional protein results, a total of 9.9% of best estimates were discarded: 8.1% were biased, 3.2% were outliers and 1.3% were both biased and outliers. When these values were discarded, 19 of 96 mean values changed by up to 4%, nine changed by 4-8%, eight changed by larger amounts and the pooled coefficient of variation fell from 8.2% to 5.4%. At this threshold between zero and 31% of each laboratory's data on conventional proteins was discarded. A lower threshold (P < 0.05) doubled the discard rate but had marginal effects on mean values and residual variation. At P < 0.01 less than 20% of biased estimates were also outliers and less than half the outliers were also biased. This means that only studies which examine both accuracy and precision will achieve maximum improvement in either.     

Microtasking as a complement to macrotasking

The ECMWF weather model runs daily as a time critical application. Acceptable elapsed times are achieved by multitasking the code on a CRAY X-MP/48. This is done at a high level giving rise to large tasks. Investigations have been carried out to tackle inefficiencies by microtasking at a low level so that the code can take advantage of any idle processors which may become available.     

Stereological estimation of mean nuclear volume in prostatic cancer,the reproducibility and the possible value of estimations on repeated biopsies in the course of disease

The reproducibility of stereological estimates of mean nuclear volume by using the principle of volume estimation of particles of arbitrary shape is investigated together with the possible prognostic value of the estimates in the course of advanced prostatic cancer. Repeated transurethral resection of the prostate was performed 14–93 months after the first resection in 14 of 85 consecutive patients in whom prostatic cancer was newly diagnosed in the period 1979–1983. Twelve of these fourteen patients needed endocrine treatment because of progression of the metastatic disease. The reproducibility of the estimations was excellent as the variation of the method was less than 1 % when the estimation of the mean nuclear volume was repeated at random on the same specimens after a time-interval of 2 months. The progression of the disease was evidenced by a significant histological upgrading and by a highly significant increase of the mean nuclear volume from the first to the second transurethral resection of the prostate.