Comparability of Raman Spectroscopic Configurations: A Large Scale Cross-Laboratory Study

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordThe variable configuration of Raman spectroscopic platforms is one of the major obstacles in establishing Raman spectroscopy as a valuable physicochemical method within real-world scenarios such as clinical diagnostics. For such real world applications like diagnostic classification, the models should ideally be usable to predict data from different setups. Whether it is done by training a rugged model with data from many setups or by a primary-replica strategy where models are developed on a 'primary' setup and the test data are generated on 'replicate' setups, this is only possible if the Raman spectra from different setups are consistent, reproducible, and comparable. However, Raman spectra can be highly sensitive to the measurement conditions, and they change from setup to setup even if the same samples are measured. Although increasingly recognized as an issue, the dependence of the Raman spectra on the instrumental configuration is far from being fully understood and great effort is needed to address the resulting spectral variations and to correct for them. To make the severity of the situation clear, we present a round robin experiment investigating the comparability of 35 Raman spectroscopic devices with different configurations in 15 institutes within seven European countries from the COST (European Cooperation in Science and Technology) action Raman4clinics. The experiment was developed in a fashion that allows various instrumental configurations ranging from highly confocal setups to fibre-optic based systems with different excitation wavelengths. We illustrate the spectral variations caused by the instrumental configurations from the perspectives of peak shifts, intensity variations, peak widths, and noise levels. We conclude this contribution with recommendations that may help to improve the inter-laboratory studies.COST (European Cooperation in Science and Technology)Portuguese Foundation for Science and TechnologyNational Research Fund of Luxembourg (FNR)China Scholarship Council (CSC)BOKU Core Facilities Multiscale ImagingDeutsche Forschungsgemeinschaft (DFG, German Research Foundation

Water Tree Influence on Space Charge Distribution and on the Residual Electric Field in Polyethylene Insulation

A computation method of the electricfield and ionic space charge density in planeinsulations with water trees (using a ComsolMultiphysics software and the thermal step currents(Im(t)) measured with Thermal Step Method) ispresented. A parabolic spatial variation of volumecharge density, an exponential spatial variation ofthe electric permittivity ε and a linear dependency ofε and the temperature coefficient of permittivity αεwith the average water concentration in trees, areconsidered. For a water tree with a known length,different values of charge density are consideredand the electric field and the thermal step currentsIc(t) are calculated. The currents Ic(t) and Im(t) arecompared and the volume of charge density andelectric field for which Ic(t) is identical with Im(t) arekept

Computation of the electric field in aged underground medium voltage cable insulation

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Influence of Dimensions and Density of Water Trees on Residual Electric Field in Polymeric Power Cable Insulations

International audienceIn this paper, the residual electric field computation in a cable insulation in the presence of water trees and space charge is presented. Considering that, in treed areas, the variations of the permittivity and the space charge density are known, the thermal step current Ic(t) is computed and the curves Im (t) and Ic(t) are compared. The results show an important increase of residual electric field for some dimensions and concentrations of the water trees (up to 10 MV/m). Finally, the influence of the residual electric field on electrically aged cable insulations is analyzed

Calcul du champ électrique dans des échantillons de polyéthylène avec des arborescences d’eau en présence de charges d’espace

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On a Method for Assessing the Electrical State of Gate Oxides in Trench-Gated IGBTs

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Evolution de l'oxyde de grille de composants semi-conducteurs de puissance soumis à des contraintes électro-thermiques cycliques

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