IMEKO Event Proceedings

Page 11 of 855 Results 101 - 110 of 8545

Roman Z. Morawski, Andrzej Miekina
A COMPARATIVE STUDY OF FORTY ALGORITHMS FOR SPECTROPHOTOMETRIC ANALYSIS OF EDIBLE OIL MIXTURES

This paper is devoted to the comparison of forty least-squares-type algorithms for spectrophotometric analysis of edible oil mixtures, viz. olive oil corrupted with corn oil and nut oil. The paper is providing a specification of the compared algorithms, a description of the methodology of their comparison, selected results of comparison, and conclusions drawn from them.

Carlo Ferrero, Adelina Leka
A COMPARATIVE VERIFICATION OF FORCE CALIBRATION MACHINES USED BY AN ACCREDITED LABORATORY

One of the most important activities of the National Accreditation Body (NAB) is the organisation of a series of comparisons (ILC), at the National level, to verify the measurements capability of the accredited laboratories.
For evaluation of the best measurement capability of AEP Transducers -an calibration accredited laboratory for Force quantity - over several years (1999-2005) are carried out measurements during accreditation and re-accreditation process of this SIT Centre, whose main results are reported in the following.
The results were evaluated using the En - normalised error - according to the SIT Doc-511.
The metrological procedures applied and the results of the accreditation of the SIT Centre, show that the best measurement capabilities and the total uncertainty, including transfer standards contribution and long term stability, can be considered as well:
± 50 ppm for the 50 kN dead weight machine (DWM);
± 250 ppm for the 200 kN Comparison machine;
± 350 ppm for the 1 MN Comparison machine (compression)
± 250 ppm for the 1 MN Comparison machine (tension).

Seung-Hee An, Jae-Young Her
A COMPARISION OF ACCURACY ON ORIFICE METER WITH AND WITHOUT STRAIGHTENER IN THE FIELD

The objective of this study is to improve the metering facilities at metering stations of Korea Gas Corporation (KOGAS), which are being operated in unsatisfying meter run conditions. For experiments, a test facility was constructed to simulate one of the metering stations and it was set up in Jung-dong metering station. Presently, KOGAS has 60 nationwide metering stations and among them, 34 metering stations are located in metropolitan area.
Tests were performed with both diameter ratio (<i>β = <i>d / <i>D) and flow rate variations and the test range of diameter ratio of orifice flow meter was from 0.3 to 0.7. The results showed that the error was - 7.2 % (maximum flow rate=3,661 Nm³/h) and - 3.1% (maximum flow rate=11,716 Nm³/h) for <i>β = 0.3 and 0.7, respectively without straightener. Thus, the diameter ratio was inversely proportional to the error, but on the contrary, the flow rate was proportional to the error. For the case of straghtener installation, the error showed 0.4 % (maximum flow rate = 3,030 Nm³/h) and 0.8% (maximum flow rate = 9,204 Nm³/h) for <i>β = 0.3 and 0.7, respectively. The error was not sensitive to the diameter ratio, but it was decreased when the flow rate was increased.

Federica Vurchio, Giorgia Fiori, Andrea Scorza, Salvatore Andrea Sciuto
A comparison among three different image analysis methods for the displacement measurement in a novel MEMS device

The functional characterization of MEMS devices is of great importance today, since it has the purpose both of verifying the behavior of these devices and of improving their future design. In this regard, the main topic of this study is the functional characterization of a microgripper prototype, a MEMS suitable in biomedical applications: to this aim, the measurement of the angular displacement of its comb-drive (capacitive electrostatic actuator that allows its movement) is provided by means of two novel automatic procedures, based on an image analysis software, the SURF-based (Speeded Up Robust Features) and the FFT-based (Fast Fourier Transform) method respectively. A preliminary comparison has been made, also with a previous semiautomatic method, to evaluate which of them is the best suitable for the functional characterization of the microgripper, highlighting their main advantages and limitations. The results obtained from the SURF-based method are promising; the curve obtained from the data showed a quadratic trend in agreement with both the analytical model and with the results obtained through the semiautomatic method. Moreover, the measurement obtained by the SURF-based method are affected by less than 0.2 ° uncertainty, that is less than one half of the measurement uncertainty due to the FFT-based algorithm.

Francesco Orsini, Andrea Rossi, Andrea Scorza, Fabio Botta, Salvatore Andrea Sciuto
A comparison between a commercial WBV platform and an experimental prototype

There are many commercial WBV platforms for clinical applications but in literature very few have been tested to verify their actual amplitude, frequency spectra and waveform shape of vibration, although some clinical studies showed that these parameters can influence significantly the muscles performance. In this study the performances of a prototype WBV1 designed by the authors are compared with a commercial platform WBV2 typically used in clinical and rehabilitation investigations. Tests performed with four accelerometers in 3 different directions show the presence of transversal accelerations that in some cases exceeded the vertical one in WBV2 while they were always lower than the 25% in WBV1. Also the waveform shape of the vibration provided by WBV1 , evaluated by means of the SINAD parameter, show a better value compared to the commercial device: indeed secondary harmonics reaches the 30% of the fundamental in WBV2 but they are always below the 25% in the prototype.

Xumo Li
A COMPARISON BETWEEN A RESISTANCE BRIDGE AND AN INTEGRATED-CIRCUIT RESISTANCE THERMOMETER READOUT USED FOR SPRT CALIBRATION

Specially designed bridges are used for standard platinum resistance thermometer (SPRT) calibration to achieve lowest uncertainty. Such bridges are expensive and their measuring speeds are slow. A new type of instrument reported a few years ago was compared against the bridge to see if it is possible to use the new instrument instead of the bridge for SPRT calibration in some cases. Four SPRTs were calibrated at the triple point of water and the freezing points of tin and zinc using a Model 6010T Bridge and the new instrument (Model 1590) simultaneously. At these calibration points the maximum differences between the two instruments were within 0.4 mK at the tin point, and within 0.7 mK at the zinc point. The maximum difference in resistance ratio W(t) at these points was within 0.9 ppm of the readings. The differences over the entire range from 0°C to 419.527°C were calculated for the four SPRTs. The maximum differences were within 0.1 mK close to 0°C, within 0.5 mK at 300°C and within 0.7 mK at 420°C. The comparison results show the new instrument can be used for SPRT calibration to achieve an expanded uncertainty (k = 2) as low as 1.5 mK.

Barry Pratt, Andy Robinson
A COMPARISON BETWEEN SUPPORTED AND UNSUPPORTED BEAMS FOR USE IN STATIC TORQUE CALIBRATIONS

In industry, calibration beams are frequently coupled directly to the measurement transducer. This paper aims to quantify the effect of using such a method in contrast to the bearing supported case for a range of commercially available transducers.

Michal Ulvr, Petr Kašpar
A COMPARISON OF DC AND AC METHODS FOR CALIBRATION OF SEARCH COILS WITH A HIGH AREA TURNS VALUE

Search coils are widely used for measuring AC magnetic fields, and in special cases for measuring DC magnetic fields with the webermeter and for comparing magnetic flux density standards and magnetic flux standards. This paper compares the measuring equipment that is used and the accuracy that can be achieved by known DC and AC methods for calibrating search coils with a high area turns value.

S. Davidson
A comparison of primary platinum-iridium kilogram mass standards among eighteen European NMIs

The kilogram is unique among the base SI units in being the only one defined by an artefact rather than with relation to naturally occurring physical constants. A major problem with maintaining the traceability of the mass scale is the inherent instability of the kilogram artefacts. National standard kilograms accrete surface contamination over time which leads to an increase in their mass values. Without reference to the international prototype kilogram it is difficult to assess the magnitude of this mass gain and the traceability of measurements is compromised to some extent. This comparison examined the values of the national standard kilogram of 18 European NMIs, each of which uses an algorithm to predict the mass gain of their national standard. The results have been used to evaluate the accuracy of these algorithms and also to recommend a best-fit algorithm for the modelling of mass gain of national standard kilograms.

S. Nattapon, S. Tassanai
A COMPARISON OF PURELY STATIC AND CONTINUOUS TORQUE CALIBRATION PROCEDURE

This paper presents the results of calibration procedure comparison in pure torque measurement with a synchronous system between the purely static (step-by-step) and continuous (quasi-static) facilities in order to prove the influence of the procedural conditions on the uncertainty of calibration. The filter setting (Low pass Bessel: 0.2 Hz, 1.25 Hz, 5 Hz and 10 Hz) and speed of applying torque (≈ 0.7 % of full scale/sec to ≈ 2.8% of full scale/sec) were varied to examine the effects of both parameters on the measurement results and to optimize the continuous procedure. The measurement was made by a torque calibration machine (TCM) with a reference torque transducer and the HBM MGCplus amplifier system using a comparison method.
The results of this experiment show the deviation between the purely static and continuous procedure within ± 0.01% of reading that was enough for class 0.2 torque measuring devices (DIN 51309) and torque transfer wrench (DAkkS-DKD-R 3-7) calibration. For the step-by-step measurement, the duration time in each torque step (form applying torque to data record) must be adequate for steady state of filter setting. For the continuous measurement, the speed of applying torque and filter setting should be optimized for best measurement capability.

Page 11 of 855 Results 101 - 110 of 8545