•We propose two improved calorimetric configurations for the determination of g-value in test cells.•They significantly reduce the amount of internal energy temporarily stored in the envelope of the ...calorimeter compared to the traditional solution.•They allow for accurate measurement of the residual amount of temporarily stored energy.•They significantly improve precision and accuracy of g-value measurement compared to the traditional configuration.
Calorimetric methods for the performance assessment of building components have been largely applied in indoor laboratories and under steady-state conditions. Although effects of one or more outdoor weather parameters are sometimes mimicked by means of dynamic schedules, they never fully reproduce the complex interactions of the stochastic processes typical of real climate.
The present work introduces improved measurement procedures to determine the solar factor under dynamic conditions, applicable to outdoor test cell experiments and which take into account the variation of internal energy in the control volume. An in-depth uncertainty analysis has been conducted in order to highlight the most relevant uncertainty sources and to suggest improvements to the measurement techniques.
Based on an iterative application of the uncertainty analysis, we developed and optimised two new strategies to extract and measure the solar load entering through a test sample and a new design concept of test cell facility, which allows the configuration to be adapted according to various test objectives. In order to accurately analyse the storage and delay effects of the thermal capacities within the control volume of the calorimeter, lumped-parameter models of three alternative designs (the two proposed strategies and a reference, traditional one) have been developed and coded in Matlab.
The simulation results suggest that, compared to a traditional solution, the two proposed solutions offer a higher measurement accuracy and measurement precision in the determination of the solar factor. In addition, the results indicate that rapidly variable solar irradiance levels are detrimental to the accuracy level of the solar factor measurement; therefore tests should be carried out under stable clear sky conditions.
A comparative analysis of the results of estimation of measurement uncertainty is conducted. The results are obtained by a method described in the Handbook on the Expression of Uncertainty in ...Measurement and also by Monte-Carlo methods and empirical and Bayesian methods recommended in a tentative version of the Handbook. Examples of calculations of measurement uncertainty for several measurement techniques in the field of analytic chemistry are presented. Features of the application and the advantages and drawbacks of the methods are described.
In modern life, to make measurements comparable, stating the quality of a measurement in terms of the measurement uncertainty is an absolute necessity. The ISO/BIPM “Guide to the Expression of ...Uncertainty in Measurement”—usually referred to as the GUM or the Guide—, which was published in 1993, introduces a method to unify the evaluation and the statement of measurement uncertainties. This method has been accepted by almost all calibration services all over the world and has become a quasi-standard in the field of metrology. This paper deals with the background of the GUM, the knowledge of the respective measurement and other fundamental aspects which have been included in the EA-4/02 requirements document published by the European co-operation for Accreditation. It shows how the basic concepts may be converted in a straight forward procedure to evaluate the uncertainty in a measurement. It is an expanded version of a lecture with the same title, held by the author at the workshop “GUM uncertainty budget in calorimetry—questions and ways to realistic determinations of measurement uncertainty” at the 14th Ulm-Freiberg Kalorimetrietage in Freiberg (Saxony) March 21/23, 2001.
Postupak ispitivanja preciznosti geodetskih i mjernih instrumenta dan je skupom normi osnovne oznake ISO 17123. Preciznost rotirajućega laserskog sustava – rotirajućeg lasera ispitana je prema ...potpunom postupku norme ISO 17123-6:2012. Potpuni postupak ispitivanja preciznosti rotirajućeg lasera definira dvije neovisne sesije mjerenja, od kojih svaka sadrži četiri serije mjerenja s trima različito definiranim stajalištima instrumenta. Nakon ispitivanja preciznosti rotirajućeg lasera obavljena su četiri statistička testiranja, koja su preporučena navedenom normom. Ispitivanje točnosti određivanja visinske razlike provedeno je usporedbom s referentnom visinskom razlikom, koja je određena metodom preciznoga geometrijskog nivelmana. Procijenjeni su izvori pogrešaka koji utječu na rezultate mjerenja rotirajućeg lasera. Kao parametri kvalitete mjerenja iskazane su standardna mjerna nesigurnost A-vrste, standardna mjerna nesigurnost B-vrste, sastavljena standardna mjerna nesigurnost i proširena mjerna nesigurnost. Podaci mjerenja automatski su matematički izjednačeni i statistički obrađeni u programu ISO_ROLAS. Analizom dobivenih rezultata utvrđeno je da su empirijske vrijednosti standardnih odstupanja manje od vrijednosti koja je deklarirana u tehničkim specifikacijama proizvođača te da empirijska standardna odstupanja dviju neovisnih sesija mjerenja potječu iz istog uzorka.
