增量式轴角编码器的电子细分及零位处理

使用单片机对增量式光电轴角编码器产生的叠栅条纹信号进行计数和电子细分,便可将轴的机械转动模拟量转换成数字量;加上固定参考零位后,可使编码器具有"记忆"功能,因此对如何解决零位技术问题做了详细分析说明,并给出了实际解决方案.     

The impact of metrological traceability on the validity of creatinine measurement as an index of renal function

When the calibration of a routine measurement procedure is traced back to metrological higher order, a significant discrepancy can occur between the analytical conditions of the routine measurement and the analytical conditions that were used in the clinical studies upon which the decision-making criteria are based. This can lead to serious interpretation errors with possible dramatic consequences for patients. The calibration of the creatinine Jaffé method is an excellent example of the importance of medical traceability. The compensated Jaffé method correlated accurately with the reference method and the compensated Jaffé creatinine clearance (CrCl), Cockroft and Gault and MDRD with the ⁵¹Cr EDTA clearance. The Schwartz estimate based upon the compensated Jaffé and enzymatic method overestimated, while uncompensated Jaffé slightly underestimated glomerular filtration rate (GFR). The situation in children is complex since serum creatinine concentrations are much lower in infants, rendering tubular secretion relatively more important. Low-molecular weight proteins have been suggested to replace serum creatinine as a marker for GFR. -trace protein, cystatin C, and ₂-microglobulin showed good correlation with GFR. However, care should be taken in patients presenting with some malignant tumors, since significant increases of cystatin C in patients with metastatic melanoma or colorectal cancer has been reported.Presented at the 9th Conference on Quality in the Spotlight, 18-19 March 2004, Antwerp, Belgium     

Improved DOSY NMR data processing by data enhancement and combination of multivariate curve resolution with non-linear least square fitting

The quality of DOSY NMR data can be improved by careful pre-processing techniques. Baseline drift, peak shift, and phase shift commonly exist in real-world DOSY NMR data. These phenomena seriously hinder the data analysis and should be removed as much as possible. In this paper, a series of preprocessing operations are proposed so that the subsequent multivariate curve resolution can yield optimal results. First, the baseline is corrected according to a method by Golotvin and Williams. Next, frequency and phase shift are removed by a new combination of reference deconvolution (FIDDLE), and a method presented by Witjes et al. that can correct several spectra simultaneously. The corrected data are analysed by the combination of multivariate curve resolution with non-linear least square regression (MCR-NLR). The MCR-NLR method turns out to be more robust and leads to better resolution of the pure components than classic MCR.     

Traceability without uncertainty: current situation in the pharmaceutical industry

The current situation in the pharmaceutical industry is discussed, when the traceability of measurement (analytical) results to certified values of pharmacopoeial reference standards is required, without evaluating their uncertainties. It is shown that the evaluation of measurement uncertainty is necessary for understanding the level of confidence of the analytical results and their comparability, particularly during preparation and characterisation of the reference standards.Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher. Apart from exceptional circumstances, they are not submitted to the usual referee procedure and go essentially unaltered.     

Assessment of element-specific homogeneity in reference materials using microanalytical techniques

The IAEA established in 1994 a co-ordinated research programme (CRP) on "Reference Materials for Microanalytical Nuclear Techniques" as part of its efforts to promote and strengthen the use of nuclear analytical technologies in member states with the specific aim of improving the quality of analysis of nuclear, environmental, and biological materials. The objectives of this initiative were: to identify suitable biological reference materials which could serve the needs for quality control in microanalytical techniques; to evaluate existing CRMs for use in microanalytical investigations; to evaluate appropriate sample pretreatment procedures for materials being used for analysis with microanalytical techniques; to identify analytical techniques which can be used for characterisation of homogeneity determination, and to apply such techniques to the characterization of candidate reference materials for use with microanalytical techniques. The CRP lasted for 4 years and seven laboratories and the Agency's Laboratories in Seibersdorf participated. A number of materials including the candidate reference materials IAEA 338 (lichen) and IAEA 413 (single cell algae, elevated level) were evaluated for the distribution of elements such as Cl, K, Ca, Cr, Mn, Fe, Zn, As, Br, Rb, Cd, Hg, and Pb. The results obtained during this CRP suggest that: each element exhibits its characteristic distribution in a matrix described by the "Ingamels' sampling constant" or the "relative homogeneity factor" of Kurfuerst; both concepts are valid over a large range of sample mass used for analysis (from 0.1 g to around 100 mg); and materials being characterised quantitatively for element homogeneity could be used for the experimental determination of total uncertainty of other analytical techniques. As far as we are aware this is the first time the concept of quantitative characterisation of homogeneity has been applied to potential reference materials and the first demonstration of the feasibility and usefulness of the concept with particular emphasis on enhancing quality control opportunities for microanalytical techniques.     

Calibration and evaluation of optical systems for full-field strain measurement

The design and testing of a reference material for the calibration of optical systems for strain measurement is described, together with the design and testing of a standardized test material that allows the evaluation and assessment of fitness for purpose of the most sophisticated optical system for strain measurement. A classification system for the steps in the measurement process is also proposed and allows the development of a unified approach to diagnostic testing of components or sub-systems in an optical system for strain measurement based on any optical technique. The results described arise from a European study known as SPOTS whose objectives were to begin to fill the gap caused by a lack of standards.     

惯导辅助相对导航系统在漂移坐标系中的相对定位算法

对惯导辅助相对导航系统（JTIDS／INS）组网，根据相对坐标漂移概念和理论，本文详细介绍了辅助相对位置基准的相对位置滤波、相对坐标漂移滤波和在漂移坐标系中进行相对定位的特点和算法，并进行了组网仿真，仿真结果满足系统技术性能要求。     

Reference intervals of serum folate and vitamin B12 developed from data of healthy subjects

 In this study the reference intervals for folate and vitamin B₁₂ were estimated according to the National Committee for Clinical Laboratory Standards Approved Guideline C28-A and International Federation of Clinical Chemistry recommendations. The study included 155 women and 124 men between ages 18–40. The health status was confirmed by history, physical examination and a questionnaire. The central 95% reference intervals of serum folate and vitamin B12 for women, determined non-parametrically, were found to be 3.9–18.1 ng/ml and 101–666.7 pg/ml, respectively. The reference values of serum folate and vitamin B12 for men were also found to be 2,5–17.6 ng/ml and 100–699.57 pg/ml, respectively. We did not observe subclass differences between females and males. Received: 15 April 2000 · Accepted: 15 April 2000     

Uncertainty calculations in the certification of reference materials

To serve as a measurement standard, a (certified) reference material must be stable. For this purpose, the material should undergo stability testing after it has been prepared. This paper looks at the statistical aspects of stability testing. Essentially, these studies can be described with analysis of variance statistics, including variant regression analysis. The latter is used in practice for both trend analysis and for the development of expressions for extrapolations. Extrapolation of stability data is briefly touched upon, as far as the combined standard uncertainty of the reference material is concerned. There are different options to validate the extrapolations made from initial stability studies, and some of them might influence the uncertainty of the reference material and/or the shelf-life. The latter is the more commonly observed consequence of what is called ’stability monitoring’. Received: 6 October 2000 Accepted: 4 December 2000