Mineral oil content in sediments and soils: comparability, traceability and a certified reference material for quality assurance

The performance of twelve laboratories with previously established proficiency in the determination of the mineral oil content in a fresh water sediment is described. The summation parameter total petrol hydrocarbon (TPH) is defined according to ISO 16703:2004 with regard to the sample preparation to be applied, the flame ionisation detection (FID) and the boiling range of C₁₀–C₄₀ to be integrated. Comprehensive tests of homogeneity and stability have been carried out on the candidate material using appropriate models. The outcome of the study served as the basis for the certification of the candidate reference material as ERM-CC015a. The certified mass fraction is 1,820±130mgkg⁻¹and traceability was established by using an appropriate calibration standard certified for the mass fraction of C₁₀–C₄₀. The interlaboratory scatter of measurement results in this exercise can largely be explained by the variability of the individual calibrations based on this common calibration standard.     

On the Deformation of the Circumflex Coronary Artery During Inflation Tests at Constant Length

Here we investigate whether the deformation observed in an experiment in which the porcine circumflex coronary artery is subjected to inflation at constant length included in the class, , , . We find that this is not the case and discuss its implications in the study of the mechanics of this artery. Moreover, we identify and quantify the uncertainty in the value of the invariants of the left Cauchy–Green tensor inferred from the 2D motion of markers affixed to the surface of the test specimen, and suggest that 3D tracking of markers is needed due to inherent bending and twisting induced by pressurization in vitro.     

An angular resolved pulsed UV LED photoelectron source for KATRIN

The KArlsruher TRItium Neutrino experiment KATRIN aims to determine the mass of the electron antineutrino with a sensitivity of 0.2 eV/c² on m(ν_e) at 90% confidence level by measuring the kinematics of the tritium beta decay with a spectrometer of MAC-E filter-type. To investigate the properties of the spectrometer, electron sources with special properties are needed. A pulsed UV LED photoelectron source with angular selectivity has been developed for this purpose. The principle has been successfully tested during measurements at the spectrometer of the Mainz neutrino mass experiment.     

Ensemble Multivariate Calibration Based on Mutual Information for Food Analysis Using Near-Infrared Spectroscopy

An ensemble multivariate calibration algorithm, termed as MISEPLS, is proposed. In MISEPLS, when constructing a member model, the variables that have mutual information (MI) with the response less than a threshold are eliminated; thus, the modeling can be performed in a subset of original variables and some problems arising from multi-collinearity can be avoided. Through experiments on three near-infrared (NIR) spectroscopic datasets from the food industry, MISEPLS proves to be superior to the single-model full-spectrum PLS and MIPLS (PLS combined with MI-induced variable selection). MISEPLS can improve the accuracy and robustness of a calibration model, without increasing its complexity.     

Transformation of phase to (x,y,z)-coordinates for the calibration of a fringe projection profilometer

In this work we present a phase to (x,y,z)-coordinates transformation method for the calibration of a fringe projection profilometer. Our technique is divided in two parts: (1) phase to z transformation (for axial calibration) based on the typical polynomial fitting which uses a flat plane placed at several z positions to measure the phase of the projected fringes. (2) Phase to x and y transformation (for transverse calibration) based on the use of a crossed gratings pattern and a Fourier phase measurement method to determine x and y coordinates at several z positions. As will be shown the use of the crossed gratings pattern and the Fourier phase measurement method for transverse calibration is advantageous in several aspects: an unique image can give us x and y information at once. It provides x and y coordinates at each pixel in the image avoiding the use of interpolation methods. We present some experimental results and explain the viability of the proposed technique.     

Regime switching volatility calibration by the Baum-Welch method

Regime switching volatility models provide a tractable method of modelling stochastic volatility. Currently the most popular method of regime switching calibration is the Hamilton filter. We propose using the Baum-Welch algorithm, an established technique from Engineering, to calibrate regime switching models instead. We demonstrate the Baum-Welch algorithm and discuss the significant advantages that it provides compared to the Hamilton filter. We provide computational results of calibrating and comparing the performance of the Baum-Welch and the Hamilton filter to S&P 500 and Nikkei 225 data, examining their performance in and out of sample.     

输入层自构造神经网络用于红外光谱多元校正

为了解决多组分红光谱定量分析中的特征的取和校正建模问题，本文提出了一种输入层自构造神经网络。在应用这种网络之前的预处理过程首先对训练数据进行分析，获得关于问题的某些先验知识。在训练阶段，神经网络根据先验知识自动选择输入层神经元的个数，同时确定网络参数。这种网络模型将特征提取和参数学习过程融为一体，有利于提高建模效率。利用仿真红外光谱的定量分析实验表明，这种网络模型不仅能够对光谱数据实现高效率的波长选择，并具有抑制随机噪声和非线性干扰的能力。     

水听器校准器的开发研究

本文所介绍的水听器校准是由一动圈活塞式换能器和由它激励的一端开口的水柱组成。水柱中的声压由驱动电流的大小来控制。在校准器的水柱中用比较法来校准水听器的低频接收电压灵敏度。     

Linear calibration graph applicable to the indirect determination of sulphate

Equations based on the equilibrium relationship between a sulphate-containing solution and solid lead sulphate were derived and applied to calibration graphs for the determination of sulphate. The special character of the linear graphs extends not only the applicability of linear calibration and standard addition procedures to the indirect determination of sulphate, but also the reliability of the analytical results. Experiments with the flow-injection technique confirmed the applicability of the proposed linear graphs.