An Accurate Equation for the Electrolytic Conductivity of Potassium Chloride Solutions

An empirical equation has been developed to model the electrolytic conductivity of potassium chloride (KCl) solutions over the temperature range 0 to 55 °C (ITS-90) and molality concentrations from 0 to 5 mol⋅kg⁻¹ (H₂O). The National Institute of Standards and Technology (NIST) Demal values are treated as the defining data and selected historical data provided further data. Changes in the definition of the ohm, liter and temperature scales have been identified and the historical data were converted to modern units. The accuracy of the equation is estimated to be equal to 0.03% as suggested by NIST as the accuracy of these data.     

Calibration in chemical measurement processes. II. A methodological approach

This article discusses the common terms related to chemical measurement processes, the different methodologies of calibration (which are not always well established) and the role of chemical standards. General classifications of reference materials and their use in the calibration process are clarified. Related features, such as recovery studies or screening and corrections of matrix systematic errors, are also considered, and guidelines concerning experimental design and verification of the calibration are given.     

EAST 磁探针 NS 值标定

为了获得精准的磁场测量数据,基于磁探针测量磁场的基本原理,构建了由长螺线管、交流电源、标准探针和数据采集系统组成的长螺线管标定系统,对EAST 磁探针垂直于磁感应强度方向的总有效面积(NS 值) 进行了精确的标定,并对标定数据进行了分析处理。获得的结果符合预期的误差要求,为磁探针精确测量托卡马克中的磁场提供了前提条件。     

基于稳定竞争自适应重加权采样的光谱分析无标模型传递方法

提出了一种基于稳定竞争自适应重加权采样(stability competitive adaptive reweighted sampling,SCARS)的无标模型传递方法。利用有用信息标准即稳定度指数(定义为回归系数除以其标准偏差的绝对值)和传递后的预测均方根误差(root mean squared error of prediction,RMSEP),选择重要的、受测样参数影响不敏感的波长变量,能够消除或减少不同仪器或测量条件对样本信息反应差异,提高模型传递效果。此外,在该方法中,光谱变量被压缩、降维,从而使模型传递更稳定。采用该方法对谷物的近红外光谱分析模型在不同仪器之间进行传递研究。结果表明,该方法能消除仪器间的大部分差异,较好地实现模型传递效果。与正交信号校正法(orthogonal signal correction,OSC)、蒙特卡罗结合无用信息变量消除法(Monte Carlo uninformative variable elimination,MCUVE)、竞争自适应重加权采样法(competitive adaptive reweighted sampling,CARS)的比较表明,SCARS不仅在传递精度上能取得比OSC、MCUVE及CARS更好的效果,而且能有效地对光谱数据进行压缩,简化并优化传递过程。     

外标法NMR实验中化学位移的校正

推导了 NMR实验中任意条件下柱状介质所感受到的有效磁场和固有化学位移的公式 ,概括了通过单谱仪、双谱仪和魔角实验校正化学位移的方法 ,阐述了平行场和垂直场中的介质磁化率效应。     

光电光谱分析电炉钢中微量Ca

电炉炼钢工艺中对 Ca的成分有一定的要求 ,特别是微量 Ca元素的快速炉前分析。采用仪器所带原始曲线 ,现有的标样 ,以及与 ICP对照比较试样 ,成功地解决了这一 Ca的分析问题。     

近红外透射技术分析大豆籽粒

本文建立了近红外透射技术 (NIT)分析大豆样本的新方法 ,批量地分析了大豆子粒的水分、蛋白、脂肪 ,定标误差分别为 0 .36 9、0 .5 78、0 .4 6 0 ,相关系数分别为 0 .95 8、0 .913、0 .912。通过 30个样本的独立样品集的定标验证 ,预测误差分别为 0 .4 0 4、0 .6 2 2、0 .5 0 8,相关系数分别为 0 .95 2、0 .90 1、0 .90 8。结果表明 ,近红外光谱技术用于测试大豆品质是可行的 ,可用于育种的早代选择     

硫酸钡漫反射板在250～400 nm光谱辐射亮度标定中的应用研究

表面喷涂硫酸钡的漫反射板正入射时是最接近朗伯特性的用于标定光谱辐射亮度的实用漫反射板。通过实验测量硫酸钡漫反射板 2 5 0～ 4 0 0nm的半球反射率和双向反射分布函数表明 ,实测的双向反射分布函数与假定漫反射板为朗伯表面根据测量的半球反射率计算的双向反射分布函数的相对差值为 6 7% ,实测的双向反射分布函数随散射角的变化可达 2 8%。为提高光谱辐射亮度标定的准确性 ,考虑双向反射分布函数的微小变化和漫反射板上的光谱辐射照度的不均匀性 ,通过对光谱仪视场内每一小面元积分 ,最后可精确求得所测光谱辐射亮度 ,并标定光谱仪的光谱辐射亮度     

分立波长型近红外光谱分析仪定标模型的优化

对于滤光片型或者二极管阵列型等采用非连续扫描方式工作的近红外光谱仪来说 ,如何快速、准确地进行定标波长的优选一直是很关键的问题 ,传统近红外定标波长的优选采用向前或者向后逐步多元线性回归方法 ,依据回归结果所给出的各个波长的t检验值进行定标波长的筛选 ,但是在实际应用中 ,被筛选掉的波长也可能是非常有用的定标波长 ,而增加波长的定标所给出的定标标准差往往会减小 ,但预测精度则不一定会提高。文章将组合数学中的组合生成算法和面向矩阵运算的计算机语言相结合运用于近红外最优回归定标波长的计算机选取 ,可以在较短的时间内完成最优波长组合的选取 ,由于最优波长组合的选取是在优选定标波长数一定的前提下进行比较而且以经回归定标分析确定定标标准差最小原则 ,所以由此得到的定标方程是稳健的。     

Vehicle-wet snow interaction: Testing,modeling and validation

For a vehicle interacting with snow, whether dry or wet, uncertainties exist in the mechanical properties of snow, and in the interfacial properties between the tires of the vehicle and snow. For dry snow, these uncertainties have been studied recently using methods within a statistical framework employing a simple stochastic tire-snow interaction model and several validation metrics. Wet snow is more complicated and much less studied than dry snow, especially for tire-snow interaction. In this paper, the authors used a physical tire-snow interaction model and a similar statistical framework as was used to analyze dry snow, and presented results of calibration and validation of the interaction model for wet snow in conjunction with new test data based on a single test run with the assumption that it would provide needed sampling points for statistical analysis. Four local and global statistical validation metrics were used to assess the physical and statistical models with good results. Comparison between wet and dry snow, based on a single test run, shows that the former has a lower interfacial coefficient of friction, and a higher drawbar pull than the latter.