Comparison of analytical error and sampling error for contaminated soil

Investigation of soil from contaminated sites requires several sample handling steps that, most likely, will induce uncertainties in the sample. The theory of sampling describes seven sampling errors that can be calculated, estimated or discussed in order to get an idea of the size of the sampling uncertainties. With the aim of comparing the size of the analytical error to the total sampling error, these seven errors were applied, estimated and discussed, to a case study of a contaminated site. The manageable errors were summarized, showing a range of three orders of magnitudes between the examples. The comparisons show that the quotient between the total sampling error and the analytical error is larger than 20 in most calculation examples. Exceptions were samples taken in hot spots, where some components of the total sampling error get small and the analytical error gets large in comparison. Low concentration of contaminant, small extracted sample size and large particles in the sample contribute to the extent of uncertainty.     

Analysis of error sources in time-domain dielectric spectroscopy

Translated from Izmeritel'naya Tekhnika, No. 8, pp. 61–63, August, 1992.     

The needle method for induction tests: sources of error

The regional flux density in laminations of soft magnetic materials is usually determined by means of a single-winding coil inserted through drilled holes. An alternative method is to use needle contacts arranged at lamination surface points through the surface coating. This method is simple and nondestructive. However, concern exists whether the results of measurements are fully equivalent with results from the coil method. We show here that full equivalence can be expected in most cases. The test results prove to be fully equivalent if the investigated region exhibits quasi-homogeneous induction or linear induction variations. If the region encloses a local induction extremum, a systematic error arises, but it can be neglected in practice. On the other hand, strong errors may arise if the in-plane flux is combined with asymmetric off-plane flux. This is because the method takes advantage of the surface eddy-current configuration, which reflects both components of flux.     

不同分析标准测试土壤铅镉结果比较

土壤的金属测试重点在于前处理,不同的消解方式对于测试结果有着较大的影响,我国目前现行的土壤铅、镉分析标准,主要选用《GB/T 17141-1997土壤质量铅、镉的测定石墨炉原子吸收分光光度法》(以下简称石墨炉法),该方法通过加入四酸加热使土壤完全消解,与《HJ 803-2016土壤和沉积物12种金属元素的测定王水提取-电感耦合等离子体质谱法》(以下简称ICP-MS法)王水提取或国外常用的王水提取法(如美国EPA 6020)在前处理上有较大区别。本文通过对不同质地的实际土壤样品分别使用四酸完全消解法和王水提取法分析铅、镉含量,比较发现上述两种前处理方法的分析结果相近,相对偏差较小。     

Improved modal truncation error in the directly analytical method for damage identification of frame structures

A directly analytical method of structural identification is derived by sensitivity theory and iteration theory. The application.of the directly analytical method of damage identification for frame structures is discussed in this paper. To increase the calculation accuracy and the construction convenience, the author improved the modal truncation error on the basis of the generally direct analytical method, and thus the required modal number could be reduced. The least modal number for damage identification drops from 23 to 16 by improving the method. The damage identification is made by the numerical simulation analysis of a five-storey-and-two-span RC frame structure, using improved and unimproved direct analytical method respectively; and the fundamental equations was solved by the minimal least square method (viz. general inverse method). It demonstrates that the feasibility and the accuracy of the present approach was impoved significantly, compared with the result of unimproved damage identification.     

Selection of the initial error model in developing analytical chemical measurement procedures

Mathematical models are presented for the error of quantitative chemical analysis procedures. The connection is traced out between the error characteristics and the repeatability, intralaboratory reproducibility, and interlaboratory reproducibility indices of the measurements. Criteria for selecting the error model in developing the procedures are considered. Translated from Izmeritel'naya Tekhnika, No. 3, pp. 57–61, March, 1998.     

Analysis of strain error sources in micro-beam Laue diffraction

Micro-beam Laue diffraction is an experimental method that allows the measurement of local lattice orientation and elastic strain within individual grains of engineering alloys, ceramics, and other polycrystalline materials. Unlike other analytical techniques, e.g. based on electron microscopy, it is not limited to surface characterisation or thin sections, but rather allows non-destructive measurements in the material bulk. This is of particular importance for in situ loading experiments where the mechanical response of a material volume (rather than just surface) is studied and it is vital that no perturbation/disturbance is introduced by the measurement technique. Whilst the technique allows lattice orientation to be determined to a high level of precision, accurate measurement of elastic strains and estimating the errors involved is a significant challenge. We propose a simulation-based approach to assess the elastic strain errors that arise from geometrical perturbations of the experimental setup. Using an empirical combination rule, the contributions of different geometrical uncertainties to the overall experimental strain error are estimated. This approach was applied to the micro-beam Laue diffraction setup at beamline BM32 at the European Synchrotron Radiation Facility (ESRF). Using a highly perfect germanium single crystal, the mechanical stability of the instrument was determined and hence the expected strain errors predicted. Comparison with the actual strain errors found in a silicon four-point beam bending test showed good agreement. The simulation-based error analysis approach makes it possible to understand the origins of the experimental strain errors and thus allows a directed improvement of the experimental geometry to maximise the benefit in terms of strain accuracy.     

Part dimension deviation control in batch manufacturing process for monitoring error sources

In a batch manufacturing process a cross-correlation exists among dimension deviations of different parts. The modelling and control of these deviations are essential to improve product dimension quality. Traditional dimension deviation statistical control methods have been focused on retrospectively analysing part dimension feature, while based on the spatial relationship between part dimensional features and error sources showed in part dimension error propagation model, this paper presents a method to control part dimension deviation in batch manufacturing that focuses on error sources. At each operation, total part deviation is separated into three components corresponding to three error sources. Therefore, a multivariate exponentially weighted moving average (MEWMA) chart for error sources is proposed to control part dimension deviations with identified error sources attribute to part dimension deviation. Efficiency and reliability of this model were verified by simulation analysis in common error source abnormal patterns, and the model is proved to be effective for detecting small deviations in a batch manufacturing process.     

Generalization of robustness test procedure for error estimators. Part II: test results for error estimators using SPR and REP

In this part of the paper we shall use the formulation given in the first part to assess the quality of recovery‐based error estimators using two recovery methods, i.e. superconvergent patch recovery (SPR) and recovery by equilibrium in patches (REP). The recovery methods have been shown to be asymptotically robust and superconvergent when applied to two‐dimensional problems. In this study we shall examine the behaviour of the recovery methods on several three‐dimensional mesh patterns for patches located either inside or at boundaries. This is performed by first finding an asymptotic finite element solution, irrespective of boundary conditions at far ends of the domain, and then applying the recovery methods. The test procedure near kinked boundaries is explained in a step‐by‐step manner. The results are given in a series of tables and figures for various cases of three‐dimensional mesh patterns. It has been experienced that the full superconvergent property is generally lost due to presence of boundary layer solution and the definition of the recoveries near boundaries though the results of the robustness test is still within an acceptable range. Copyright © 2005 John Wiley & Sons, Ltd.     

汽车前轮转向角测试误差修正算法研究

提出一种利用汽车转向桥机械结构特性解决汽车转向轮转向角测试误差修正的算法,通过该算法可计算出汽车轮胎准确的零转角起点位置,进而对转角测试数据进行修正,以此计算出准确的左右轮最大转向角及相关角,解决了目前汽车转向轮转向角测试数据准确度低、重复性差的问题。     

电流互感器自动化检定系统误差试验单元验收方法

介绍了母线式电流互感器和复匝式电流互感器进行全自动的检定试验方法。通过对误差试验单元的分析,并结合JJF 1033-2014《计量标准考核规范》的相关要求,深入探讨和研究了误差试验单元的验收方法和技术路线。     

Potential of modern technologies for improving internal exposure monitoring

Internal dosimetry is the science of assessing the amount and distribution of radionuclides in the body, and calculating resulting radiation doses to internal organs or tissues over specific time periods. Because the ionizing radiation energy deposited in a particular organ from radionuclides incorporated in the body cannot be measured directly, internal doses are estimated or inferred principally from in vivo or in vitro bioassay. As a matter of fact, in an effort to implement effective programmes in internal dosimetry, since internal dosimetry programmes exist, the internal dosimetry laboratories have always tried to develop new capabilities for these techniques or achieve the harmonisation in individual monitoring for occupational exposures. The primary goal of this paper is to categorise the principal trends made in recent developments in these fields regarding their potential and eligibility for the routine monitoring community and discuss the main aspects, which aims at a comprehensive assessment of these techniques. Secondly, starting from these data, their potential improvements are compared to the currently employed monitoring techniques used in routines.     

电光源频闪测试技术研究

采用经V(λ)修正后的硅光电接收器模拟人眼接收光信号,高速A/D采样,使用傅里叶变换理论及其改进算法处理采样数据,实现电光源频闪频谱和波动深度的准确、快速测试。运用方法学考证,设计了验证实验并取得理想的验证结果。在对常用电光源进行了大量测试研究的基础上,提出了电光源频闪特性的参数及限量指标的建议,给出典型电光源的频闪数据。     

Under potential deposition of lead onto carbon fibres for use in lead/acid battery applications

An effective method of reducing the mass of a lead acid battery is to replace the lead with a less dense electrical conductor such as carbon. The application of a thin layer of lead onto the surface of carbon fibres can improve the electrical and mechanical properties of the bond between the fibre and battery active material. Under-potential deposition was used to apply a thin layer of lead onto carbon fibre tows. The efficiency of this process using a number of different electrolytes and voltage ranges was assessed. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy were used to evaluate the deposition process. Lead was successfully deposited onto the surface of the fibres at a potential of approximately 262 mV using the electrolyte consisting of 0.1 M HCIO₄ and 0.01 M Pb(OAC)₂.