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The thermoelectric inhomogeneity as a function of position along wires is one the significant uncertainty of measurement using thermocouples. Here we report development of an electrical annealing system for thermoelectric inhomogeneity treatment. Two inhomogeneous type-S thermocouples, which had the inhomogeneity greater than 0.04%emf, are successfully recovered using the system. An improvement on thermocouple performance as large as 0.28 °C (at temperature of 1000 °C) can be obtained using the system. This article provides detailed information and may help the reader to obtain a quick grasp about the system.

The International System of Units (SI) is to be redefined with implementation set to be on World Metrology Day (20^th May 2019). Under the auspices of the Consultative Committee of Thermometry (CCT) the world thermometry community has been working together to ensure a smooth and effective redefinition of the kelvin. A large part of that activity has been coordinated through the European Metrology Programme for Innovation and Research: "Implementing the new kelvin" projects. This paper describes the InK2 project contribution.

This thesis focuses on the research of multi-spectrum thermometry image distortion and non-uniformity correction based on the characteristic of single CCD transient imaging multi-spectrum thermometry. A distortion correction based on Zhang calibration is used to rectify the lens distortion. A non-uniformity correction combined two-point calibration with neural network is carried out to rectify the non-uniform images. Compare the images before and after correction, the distortion calibration method used in this thesis can decrease the error between the field image and the target location. The comparison of the images before and after non-uniformity correction illustrates that the non-uniformity correction used in this thesis can reduce the temperature measurement error caused by CCD pixel conformance differences observably.

After measuring thermodynamic temperatures in the range from 900 °C to 2500 °C, The Centro Español de Metrologia (CEM) in collaboration with the Instituto de Óptica of the Consejo Superior de Investigaciones Científicas (IO-CSIC) are currently involved in the measurement of thermodynamic temperatures down to 400 °C using radiometers based on InGaAs detectors with central wavelengths in the near-infrared spectral range (NIR). This communication summarizes the progress towards the extension of absolute radiation thermometry measurement range to lower temperatures.

This paper introduces the methods of heat flux sensor calibration and gives detailed descriptions of absolute and transfer techniques. The transmission of standard heat flux is realized by comparing the calibrated heat flux sensor with standard heat flux sensor based on a flat plate furnace. Furthermore, we design a heat flux sensor calibration equipment using absolute method which contains a sodium heat pipe blackbody with 50-mm-diam cavities. Thus heat flux sensor calibration can be traceable to the temperature standard using the absolute equipment.

The melting and freezing behaviours of pure Si contained in alumina crucible were investigated using a monitoring Pt/Pd thermocouple. To induce melting and freezing, furnace temperatures were controlled from ± 3 °C to ± 10 °C. The melting and freezing temperatures coincided within 10 mK at the offset temperature of ± 3 °C, showing a good consistency. The melting and freezing plateau temperature varied with offset temperature, and melting had much smaller offset temperature dependence. The freezing temperature showed a good reproducibility of about 20 mK (1 σ) regardless of the offset temperature. After repeated 9 phase transitions at high temperature, it turned out that it was not mechanically broken. One drawback of pure Si cell is the formation of white and finite powders inside. This is probably due to evaporation of molten Si and deposition on the surface of alumina components. Finally it is recommended to calibrate high temperature noble metal thermocouples of about 1412 ° C using the freezing point of a pure Si cell made of alumina crucibles.

This study developed emissivity-compensated radiation thermometry. The principle of this method is based on the combined utilization of effective radiance and a specular reflection parameter. The former value is derived from multiple reflections of radiant flux between a specimen surface with an unknown spectral emissivity and a reflector. The latter value is derived from the reflection pattern of a specimen surface for incident light flux. The measurement system was composed of a radiation thermometer, a cylindrical cavity for multiple reflections, and a laser to obtain the specular reflection parameter. This system enabled the simultaneous measurement of temperature and emissivity of a specimen with any surface irregularities.

A set-up to calibrate thermocouple up to 1500 °C by comparison against radiation thermometer is recently established in Research Center for Metrology – LIPI (RCM – LIPI). A blackbody cavity, made of silicon carbide, is put in a single-zone-controller furnace as a comparator block. A radiation thermometer standard (worked at λ = 650 nm) is employed to determine the reference temperature of the calibration. In this work, a type B thermocouple is calibrated in the range of 1000 – 1500 °C. The expanded uncertainty (k = 2) is evaluated to be 2.4 °C at 1500 °C. The uncertainty due to inhomogeneity of the thermocouple contributes more than 50% (1.4 °C) of the total uncertainty.

A high temperature fixed-point cell based on a melting or freezing transition can only be as good as the purity of the metal used to make it, and that purity can be hard to quantify. Least squares fitting of the Scheil solidification model has been applied to four cobalt-carbon and four platinum-carbon fixed point cells, as measured variously at eight different laboratories, to determine the pure material liquidus temperature for each cell. If this value does not agree with the liquidus temperatures of the same melting transitions, within the assigned uncertainties, as determined directly from the melting curve then the implication is that the allowed uncertainty component for impurities may not be large enough. We find the method can be accurate enough to be useful in validating a high-temperature fixed-point cell.

The current and the forthcoming definition of the base unit kelvin are critically analysed. Using basic concepts of statistical thermodynamics, an attempt is made to elucidate the physical meaning of the revised definition of the kelvin. The consistency between the revised and the current thermodynamic scales is evaluated and the impact of the redefinition on the measurement infrastructures is speculated on.

The archaeological artefacts storage is possible in passive microclimate chambers, where relative humidity can be maintained using the moisture stabilizer. The aim of the paper is to check the homogeneity of the relative humidity in dependence on the distance from the moisture stabilizer in the horizontal and vertical situation of the chamber and to check the impact of the outside temperature to the conditions inside the microclimate chamber. We placed a plexiglass tube into the large climatic chamber. In the tube we evenly distributed four measuring probes that measured temperature and relative humidity. The measurements were carried out at 10 ° C, 23 ° C and 40 ° C temperature and in three different tube positions: vertically (silica gel at the bottom of the tube), vertically (silica gel at the top of the tube) and horizontally.

An absolute primary acoustic gas thermometer has been developed and successfully tested in VNIIFTRI. The acoustic gas thermometer is planned to be included in the Russian state primary standard of the temperature unit – kelvin in the range 0.3-273.16 K. The uncertainty of the thermodynamic temperature measurements with the acoustic gas thermometer near the triple point of water was experimentally researched.

All-in-one type apparatus for measuring thermoelectric properties of the thermoelectric devices has been developed. This apparatus gives Seebeck coefficient, electrical conductivity, and thermal conductivity simultaneously, which give the thermoelectric figure-of-merit of the thermoelectric modules and materials. In this study, we present the apparatus for evaluating the thermoelectric figure-of-merit of the thermoelectric devices in the range of 150 °C and 700 °C using guarded hot plate method.

In this work we present a comparative study of an impact of several optical windows (the SCHOTT glass filters (KG1 to KG5) with a broadband transmittance in the visible spectral range) and an interference filter (with a peak transmittance at 650 nm) on the size-of-source effect (SSE) of a radiation thermometer. The investigations were performed in the scope of the development of a Double Wavelength Radiation (DWT) thermometer at UME. There are two radiometric channels in the DWT, where one of the channels will comprise of a broadband transmittance filter, while the other - an interference filter. In order to exclude the optical path effects on the SSE measurements the investigations were performed on a single channel radiation thermometer. The SSE measurements were performed by means of the indirect method. The SSE measurement results are illustrated and discussed.

The calibration interval of standard platinum resistance thermometers (SPRTs) was studied using the fixed-point calibration data accumulated for eleven years. A model was proposed to predict the long-term drift of the change rate of resistance R_TPW at the triple point water and the resistance ratio at the freezing point of Sn (W_Sn) and Zn (W_Zn). A Monte Carlo simulation was carried out to present the calibration interval in terms of the measurement reliability of SPRT over elapsed times after a calibration based on the model with various target tolerance limit of the drifts.

In the scope of the project HUMEA – Expansion of European research capabilities in humidity measurement within the EURAMET EMPIR program, the modular chamber for calibration of relative humidity instruments was designed, manufactured and characterized. The modular chamber consists of arbitrary numbers of aluminum blocks each of which provides accommodation for the one relative humidity probe and also has the fittings for pressure and temperature probes as well as ports for gas sampling and/or supplying. The gas can be supplied from the dew/frost point generator or the larger climatic chamber. In the latter case, the airflow through the chamber can be enhanced by using an additional fan. The preliminary study was carried out to investigate the improvement in temperature uniformity using a new chamber in combination with two climatic chambers. The investigation results show significant improvement in temperature uniformity thus lowering the uncertainties of the calibration of relative humidity instruments.

This paper presents an analysis of the correlation effect in the uncertainty estimation of a system for humidity generation based on the two pressures principle. In order to compare the validity of the calculations, two methods for evaluating uncertainty, including the correlation between the input variables, were used. The first one was the classical approximation based on the applicability of the central limit theorem, while the second consisted of the propagation of the input distributions using Monte Carlo simulations. The obtained results show that the usual assumption of negligible correlations between the input variables is valid for uncertainty levels in calibrations of hygrometers.

The control and measurement of humidity is important for many industrial applications and to ensure the appropriate storage of materials and products. Humidity measurement techniques are diverse and each presents different challenges for use and calibration for a range of pressures and gases. Over the past few years, the development of humidity sensors and apparatus has matured to a level where traceable calibration is beneficial to all industries in which humidity and moisture measurement and control are important. This paper deals with a European project in which the overall objective is to develop or extend the measurement and research capabilities of the participating emerging NMI/DIs' countries in the field of humidity measurements, where access to these types of facilities is currently limited.

In the frame of the EMPIR-funded joint research project 15SIB02 "Implementing the new kelvin – 2" (InK2) the determination of T-T₉₀ over the temperature range between 430 K and 1358 K with a target uncertainty around the 10 mK level is under preparation in several NMIs, among which LNE-Cnam and CEM. The two laboratories have joined their efforts for the thermal characterisation of a set of three aluminium fixed-point pyrometric cells. The cells were constructed using the hybrid design based crucibles and the piston filling method both developed by LNE-Cnam over the past decade. To study the effect of the temperature gradients on the freezing temperatures of the cells, two three-zone furnaces were used for the implementations of the cells with different temperature distributions. Finally, a first determination of the thermodynamic temperature of the freezing plateau was determined by extrapolation from the thermodynamic temperature of the copper point of LNE-Cnam. The results of the characterisations and the temperature determination are presented.

For proper use of thermocouples in every day laboratory calibration is important to know the deviation function from the thermocouple standard EN 60584-1. In practise, the polynomial of first, second and third order are used for an interpolation calculation. Evaluation of uncertainty is often based on least squared method where no correlation is involved. In reality, each calibration point is correlated by using of same equipment and traceability. This paper will show the influence of different levels of correlation to the uncertainty propagation of interpolation. The evaluation is based on real thermocouple and Monte Carlo simulation method.

The performance of athletes doing outdoor sport activities, such as cycling, is highly affected by the thermo-hygrometric comfort which depends on environmental and individual factors, such as geographical characteristics, season of the year, actual weather condition, physical and physiological state, and very important, the characteristics of personal garment that should protect the individual athlete. In this study, we use a multi-sensor approach to estimate thermo-hygrometric comfort of new textiles and designs in cycling clothes. The method relies on a simplified transfer of heat-moisture transport model over multiple layers.

Thermodynamic temperature measurements of Al and Zn points using a near-infrared radiation thermometer 3 (NIRT3) are described. The NIRT3 was constructed for long-term stable operation, low size-of-source and characterized for linearity. The spectral responsivity was measured using tuneable near-infrared lasers and window-less InGaAs diodes. The spectral responsivity of the NIRT3 was scaled using a Au freezing-temperature blackbody and an absolute visible radiation thermometer. We then measured both the Al and Zn freezing temperatures and these measurements are compared against T-T₉₀ values estimated by the Consultative Committee for Thermometry.

With increasingly urgent requirements for pollution control and energy saving, the study of low-emission and high-efficiency burners has been proposed worldwide. Among all these new technologies, swirl-induced environmental (EV) burners are outstanding with notable features, such as low emissions, particularly NOx, while maintaining a good combustion stability. In this study, an EV burner is investigated by both an ECT system and an OH-PLIF system. The aim is to detect the structure of a flame and obtain more information, for instance, OH radicals distributions about the combustion process in an EV burner. The experimental images of a flame by ECT are in good agreement with the OH radical distribution pictures captured by OH-PLIF. Visualizing flame distributions in combustion chambers would be the first and necessary step to more difficult tasks such as detecting the locations of poor combustion zones in a combustion chamber that tend to reduce the combustion efficiency, and the locations with excessively high temperature that would generate high concentration of nitric oxides (NOx) gases

We estimated uncertainty components associated with the extrapolation of temperature scales down to the boiling point of nitrogen (77.352 K) from a temperature scale of the standard resistance thermometers calibrated at the triple points of argon, mercury and water based on the international temperature scale of 1990. The extrapolation below the triple point of argon is done by using the deviation function of the ITS-90 obtained by the calibration down to the triple point of argon. The standard uncertainty at the boiling point of nitrogen due to the extrapolation is estimated to be 0.17 mK on the assumption that the differences between the two temperature scales calibrated down to the triple points of argon and oxygen are described by a symmetric, rectangular a priori probability distribution.

Modern testing of thermophysiological comfort of functional textile fabrics involves not only their water vapour permeability and thermal resistance in dry state, but also testing of these properties in wet state. Besides stationary properties, also transient properties like warm-cool feeling or thermal absorptivity are important. In the paper, the concept of special version of this parameter, called moisture absorptivity, is explained and used for evaluation of transient moisture transfer (moisture management) between simulated wet human skin and selected dry functional underwear fabrics.

The measurement of air temperature is important in many types of metrology. Despite being generally an auxiliary measurement, in some fields poor knowledge of air temperature represents a limiting uncertainty. Applications where this is the case include interferometric dimensional measurements, in which the air refractive index correction is required, and the determination of relative humidity. Yet despite its ubiquity, relatively little attention has been paid to determining air temperature with low uncertainty. In this paper we discuss an under-appreciated systematic error in air temperature measurements: the diameter-dependence of the radiation correction for cylindrical and spherical sensors. After a discussion of the typical magnitude of the effect we consider ways to mitigate the effect by the careful design of air temperature sensors, and through use of non-contact air temperature measurement techniques.

This paper is about unique the interlaboratory large comparison organized under EA-2/14 - Procedure for Regional Calibration ILCs in Support of EA MLA and describe final results of the comparison and several pitfalls when measuring temperature with base metal thermocouple. Interlaboratory comparison (ILC) serves as a tool for comparison of measurement results carried out by accredited or non-accredited calibration laboratories in the relevant field of measurement. ILC represents very effective means to demonstrate technical competence of the participant and also serves as a technical base for accreditation. The subject of this comparison was calibration of several pieces the N-type thermocouples. The pilot laboratory of this ILC was the Department of primary metrology of thermo-technical quantities of the Czech Metrology Institute. The reference values of the test items were provided by the above mentioned organizational unit this company. The evaluation of the measurement results of participating laboratories was performed on the basis of E_n score (EN ISO/IEC 17043). In this ILC program 47 accredited calibration laboratories from different European countries and also from Bosnia and Hercegovina, Switzerland and Turkey have participated. The results of this comparison demonstrate satisfactory agreement of the majority of the participants measured values with the reference ones within their stated expanded uncertainties. The article also highlights the basic and often neglected components of uncertainty.