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Humbat Nasibov, Sevilay Ugur
CHARACTERIZATION OF THE PYROMETERS TO THE SUBJECT OF PREAMPLIFIER GAIN NONLINEARITY

Dc-operated radiation thermometers, due to their high-speed response, simple and rigid optical and electrical systems are widely used in industry and science. Practically, in all metrology laboratories the realization and dissemination of the temperature scale (by means of radiation temperature) is carried out using the dc-operated transfer standard radiation thermometers. Therefore, the actuality of the accurate characterization of all aspects of the pyrometer system is evidently clear.
This paper describes the systematic error contribution of the gain non-linearity of well-designed preamplifiers in the signal processing of the dc-operated radiation thermometers.

Juraj Božicevic, Alojz Caharija, Nenad Bolf, Denis S. Vedrina
DETERMINATION OF THERMAL CONDUCTIVITY IN LIQUIDS BY MONITORING TRANSIENT PHENOMENON

Thermal properties of liquids, especially thermal conductivity, are important issues in the designing, developing and application of products. In this paper, the method of thermal conductivity determination is based on heat transfer process analysis during transient phenomena caused by an energy pulse, with application of parameter value estimation of process model. Essentially, influence of energy pulse on the liquid condition in the measuring cell is negligible.

Achim Seifter
ABOUT THE MEANING OF THE HAGEN – RUBENS RELATION TO RADIATION THERMOMETRY

Pyrometry is the only way to obtain temperature measurements when performing fast (µs duration) experiments on metals up to and above their melting points. Converting the pyrometer signals to true temperatures requires some knowledge about the normal spectral emissivity of the target at the operating wavelength of the pyrometer. Because dynamic emissivity measurements are rather difficult, one often has to resort to assumptions about the temperature and wavelength dependence of emissivity instead of a direct measurement. The HAGEN–RUBENS relation between the normal spectral emissivity of a metal and its electrical resistivity can be helpful in making such assumptions. In this work, a method for obtaining good estimates of the normal spectral emissivity of metals and alloys above their melting points as a function of temperature, based on the HAGEN-RUBENS relation, is presented. Its usefulness is examined by comparing results derived from it to actual emissivity data on several liquid metals and alloys that were measured using a pulse-heating technique.

Domen Hudoklin, Jovan Bojkovski, Janko Drnovšek
THE INFLUENCE OF ASPIRATED PSYCHROMETER ON CALIBRATION PROCESS

In the proposed paper the influence of motor aspirated psychrometer on calibration process is investigated. Proper humidity measurement with psychrometer requires sample gas stream of sufficient velocity in order to achieve accurate measurements. For this reason modern psychrometer typically have integrated aspiration motor to assure such gas stream over the thermometer, which is enclosed by a wet wick (wet thermometer). The wick has to be maintained in a wet condition, which causes evaporation and consequently the unwanted humidification of the air being measured, especially in a closed humidity chamber or humidity generator. Different psychrometers were tested in a humidity test chamber in order to estimate the level of such humidification. The results are summarised in the paper. In addition, special considerations are addressed regarding the calibration of motor aspirated psychrometer in closed calibration environment.

Jovan Bojkovski, Valentin Batagelj, Igor Pušnik
THE COMPARISON OF THE REALISATION OF THE FREEZING POINT OF INDIUM INSIDE THE THREE ZONE FURNACE AND THE FLUDISED POWDER FURNACE

In the paper the comparison of the realisation of the freezing point of indium inside the three-zone furnace and the fluidised powder furnace is presented. The emphasis of the paper is given to the comparison of the metrological characteristics of the realisations such as time duration of the plateau and the width of the plateau. The same fixed-point cell (closed fixed-point cell, serial number In 86, made by Isotech) was realised in both furnaces. Also the analysis of the immersion curve is performed in order to see how it agrees with the expected curve.

Valentin Batagelj, Jovan Bojkovski, Igor Pušnik
OPTIMIZING THE UNCERTAINTY DUE TO THE SELF-HEAT OF PLATINUM RESISTANCE THERMOMETERS IN PRACTICAL USE

Self-heat of platinum resistance thermometers (PRTs) is a well-known phenomenon that occurs when measurement current additionally heats up a PRT sensor. This temperature increase depends on measurement current, PRT design, operating temperature and surrounding medium. Self-heat temperature increase can be corrected with some residual uncertainty, but this applies mainly to calibration of PRTs, while in practical temperature measurements self-heat measurement or estimation is difficult due to poor temperature stability and/or short measurement time that does not allow temperature transient effects to fade away. If not handled properly, self-heat uncertainty can be one of the largest, but often neglected uncertainty contributions in temperature measurement. A study of uncertainty optimization is presented for a measurement system composed of up to twenty PRTs that are connected to the ohmmeter via a scanner and sequentially measured. The optimal measurement procedure is discussed and the uncertainty analysis is given.

Toru Yamamoto, Minoru Tanaka, Masaru Tsudagawa, Shigeru Takayama
MEASUREMENT OF HEAT DISCHARGE OF AN OFFICE BUILDING BY ENERGY CONSUMPTION

To estimate a thermal environment of city, it is necessary to know and evaluate a state of heat discharge of buildings, cars and a solar radiation. This paper shows an estimation method of the heat discharge of an actual office building by using measurement results of the amount data of energy consumption and energy demand for one year per hour, and the efficiency of energy supply equipm ents. And also, from the estimation, the dynamic characteristics of the heat discharge of an actual office building in a year are evaluated.

Yasser A. Abdelaziz
GUIDELINES FOR ASSESSMENT OF TEMPERATURE UNIFORMITY AND INVESTIGATION OF THE MEASUREMENTS UNCERTAINTY WITHIN LABORATORY OVEN

Laboratory ovens as drying and heattreatment ovens require to be calibrated in order to meet the measurement traceablitiy according to the ISO Guide 17025 requirements, special in accredited laboratories. Industrial and medical laboratories also need to evaluate and assessment of the temperature uniformity within their ovens, to get the optimum working conditions.
This paper describes the methodology for assessment the temperature uniformity within the working space of the oven and the measurements uncertainty budget. The method covers the temperature range from ambient up to 1000°C.
The paper is presented also the method for assessment of some oven parameters as temperature gradient, stability, temperature fluctuation and temperature drift within the oven.

Slavolhub G. Petkovic , Fernando A. L. Goulart, Fabio. D. Campos, Hamilton D. Vieira, Klaus N. Quelhas, Marcelo S. Monteiro, Paulo R. F. Santos
FIXED POINT CALIBRATION FOR TYPE N THERMOCOUPLES IN THE 0°C TO 1000°C RANGE

Noble metal thermocouples are suitable for fixed point calibration method. Basic metal thermocouples, on the other hand, are usually calibrated by comparison. This happens because of th eir electromotive force (emf) instability in short time. In the range from 0 to 1084°C, according to the Monograph CCT/WG1 – BIPM the typical uncertainty of type N thermocouple is about 0.2°C (k=2) at the fixed points and 1.0°C (k=2) in the interpolated values. This paper tries to enlighten this discussion presenting results which confirm that type N thermocouples have the best emf stability among base metal thermocouples up to 1000°C, when it is used by customers for calibrations by comparison, after have being calibrated at fixed points cells in primary laboratories. In this condition, it is possible to show that type N thermocouple permits to achieve results near to mentioned uncertainties. The calibration method, laboratory facilities, results and uncertainty budget are reported in this paper. A sheathed thermocouple having compacted mineral oxide insulation was calibrated by fixed points method at Inmetro and by comparison in Brazilian secondary laboratories along two years. This thermocouple has accumulated more than 200h at 1000°C .

Tomáš Sysala, Vladimír Vašek
DETERMINATION OF DYNAMIC POLYMER PROPERTIES

The paper deals with equipment for plastic materials analysis. This equipment is called thermoanalyser. The general principle of analysis is based on the temperature measurement and the temperature control on the desired temperature and simultaneously on penetrating measurement of the deforming tip into microsample. From these data and from force on the deforming tip we can determinate many plastic materials properties. The first problem was measurement, the second problem was the temperature control in two furnaces. There is the pole placement algorithm (2nd and 3rd order) used. The last part of the paper deals with the storing of the materials parameters to the database.

Page 901 of 939 Results 9001 - 9010 of 9382