Benefits arising from proficiency testing schemes: The comparison of analytical methods

 The primary objective of proficiency testing (PT) is in the provision of information and support to participating laboratories, to enable them to monitor and improve the quality of their measurements. However, other benefits can be obtained from PT. These include the comparison of data for a given measurement by different methods, the validation of new methods, and the provision of information for laboratories' customers and accreditation bodies. This paper considers the subject of method comparison, and highlights some of the approaches which can be followed, as well as the practical use to which this can be put, to benefit the analytical community more widely. This is illustrated by a case study concerning the measurement of haze in beer. In this study the United Kingdom Institute of Brewing (IoB) conducted a survey of participants in the Brewing Analytes Proficiency Scheme (BAPS). From the survey data taken together with data from the BAPS scheme, the IoB is now in a position to give guidance on the use of particular instruments and procedures, as well as consider changes to the scope of the BAPS scheme to provide greater benefits for participants concerned with measuring haze. Received: 3 March 1998 · Accepted: 9 June 1998     

Detection and description of non-linear phenomena in experimental modal analysis via linearity plots

Ground vibration tests (GVTs) on aircraft prototypes are mainly performed to experimentally identify the structural dynamic behaviour in terms of a modal model. This assumes a linear dynamic behaviour of the structure. However, in the practice of ground vibration testing it is often observed that structures do not behave in a perfectly linear manner. Non-linearities can be determined, for example, by free play in junctions, hydraulic systems in control surfaces, or friction. This paper compiles measured, typical, non-linear phenomena from various GVTs on large aircraft. The standard procedure in GVTs nowadays is the application of the Harmonic Balance method which linearizes the dynamic behaviour on the level of excitation. The procedure requires a harmonic excitation of the structure which is usually performed during phase resonance testing. The non-linear behaviour is investigated in terms of linearity plots in which the resonance frequency of a mode is plotted as a function of the excitation level. The experimental data is then compatible with all post-processing procedures for the measured results, e.g. updating of the finite element model or flutter calculations. This paper shows measured linearity plots for some typical non-linear phenomena. In the second part of the paper analytical linearity plots for different non-linear stiffness and damping models are considered in order to investigate whether the type of non-linearity can be identified from measured linearity plots. The analytical linearity plots are discussed with respect to their application limits. The analytical linearity plots are used to interpret the experimental linearity plots stemming from various GVTs on different aircraft prototypes. Finally, the observability of non-linear stiffness and non-linear damping characteristics via linearity plots is assessed.     

Encapsulation of filaments of a self-assembling bicopper complex in polymer nanowires

We report on the preparation conditions and the characterization by calorimetry and small-angle neutron scattering of a molecular composite material obtained via the heterogeneous nucleation of the fibrils of a thermoreversible gel. This physical process allows encapsulation of monomolecular filaments of a self-assembling bicopper complex into nanosized polymer fibrils. Due to the existence of 1-D arrangements of copper atoms, this material may possess unusual magnetic properties (spin ladders). Received 20 January 1999 and Received in final form 14 May 1999     

Minimum value assured by a method to determine gold in alloys by using laser-induced breakdown spectroscopy and partial least-squares calibration model

A procedure for estimating the minimum value assured by an analytical method has been developed. It is applied to the determination of gold in jewellery alloys by means of a recently proposed spectroscopy technique. The laser-induced breakdown spectroscopic data of 17 gold alloys, with gold concentration ranging between 50 and 100% were used as calibration set for carrying out the partial least-squares regression (PLS). Ninety alloys, with known gold concentration, were used to evaluate the method’s accuracy. Finally, the minimum guaranteed value of the gold content was analysed, taking into account the values for gold hallmark in Spanish regulations.     

BEPC实验电子枪系统的研究

E5-4实验电子枪系统是BEPC电子枪系统的改进版本，文中首先对其进行了理论分析，并介绍了利用Y796阴栅组件和新的电源及Pulser系统进行测试的结果，分析了各个参数对束流的影响，给出了电子枪流强与直流高压、pulser 电压、栅偏压、阴极参数等的关系曲线，对BEPCII电子枪系统的研制和调试起到了重要的指导作用.     

层次分析法中整体一致性判别及校正

针对层次分析法(AHP)中下层存在不满足满意一致性条件判断矩阵的整体一致性判别问题，提出了具有满意一致性的充要条件．对判断矩阵，提出一种不需求最大特征值即可计算出一致性指标的新方法，用此方法可非常方便地求出判断矩阵的最大特征值．给出了判断矩阵一致性的统计检验方法的使用条件，提出了不满足满意一致性的判断矩阵的校正新方法，所给出的方法用计算机实现非常方便，对于低阶矩阵，手工计算也非常简便．     

激光驱动器能源系统实验平台测控系统的研究

为了提高激光驱动器能源系统运行的稳定性、可靠性、安全性 ,研制了一套能源系统实验平台的测控系统。该测控系统采用 RS-2 32串行通讯、多线程程序设计来完成并行处理 ,具有较强的抗干扰能力 ,可远距离的进行自动控制、数据采集 ,并能及时的进行数据处理和分析 ,显示报表并打印。该项研究的结果为大型激光装置的相关系统设计提供了依据。     

Automated ion-selective measurement of lithium in serum. A practical approach to result-level verification in a two-way method validation

 The Quality Assurance Department of Medix Diacor Labservice evaluated a two-way method validation procedure for serum lithium quantification in therapeutic drug monitoring In the process of a company fusion and rationalization of two considerably large production lines, three independent ion-selective electrode (ISE) methods were surveyed, among many others. While tailoring the new medical laboratory production, subcontracting from a collaborating company was discontinued. Likewise, modernization of the ISE instrumentation was unavoidable to increase throughput and effectiveness. It was important that the new result levels should be comparable both with the former subcontractor's levels and with the levels reported from the previously existing instrumentation. The aim of this study was to evaluate the most crucial performance characteristics of a novel lithium method in comparison to the two ISE test methods being withdrawn. The standardized lithium test method was inspected in terms of linear measurement range, analytical variation, bias, past and on-going proficiency testing, in addition to method comparison, to achieve the desired analytical goals. Fulfilling the accreditation requirements in terms of the introduced method validation parameters is discussed. Received: 19 April 2000 / Accepted: 26 July 2000     

弱吸收多层薄膜消光系数的反演

从窄带干涉滤光片的峰值透射率测量可以直接反演出弱吸收薄膜的消光系数，从而得到一种能简易而又精确地评价多层薄膜微弱吸收的新方法. 推导了弱吸收窄带干涉滤光片的吸收表达式， 阐述了确定弱吸收薄膜消光系数的基本原理.以离子束溅射的Ta₂O5/SiO₂波分复用滤光片为例，分析了这种评价方法的基本精度. 关键词： 光学测试 离子束溅射 光学薄膜干涉滤光片 消光系数     

Terahertz波计算机辅助三维层析成像技术

介绍和讨论了Terahertz波计算机辅助层析成像技术(Terahertz-CT).与x射线计算机辅助层析成像技术(XCT)相比较，Terahertz-CT可获得更丰富的信息来处理图像.理论上，该技术可获得被测物在Terahertz波段的折射率和吸收率的三维分布.这意味着有可能利用Terahertz-CT进行暗箱识别探测，该技术的原理在安全检查和无损探测等方面的应用有着广阔的前景.