IMEKO Event Proceedings

Page 808 of 851 Results 8071 - 8080 of 8504

Jean Marc Linares, Jean Mailhé, Jean Michel Sprauel
UNCERTAINTIES OF MULTI SENSORS CMM MEASUREMENTS APPLIED TO HIGH QUALITY SURFACES

A statistical approach, based on a maximum likelihood criterion, is used to define the uncertainties of the derived element associated to a set of measured coordinates. The method is applied to high quality surfaces of low extent.

K. Nahrstedt, J. Bajcsy
UNCERTAINTIES OF SCHEDULING SYSTEM FOR MULTIMEDIA

Processing of multimedia applications in digital computing environments requires support of qualities, such as low jitter between video frames, known from current television or radio. This is especially difficult in these environments due to various noises coming from the hardware and software.
In this paper we present (1) a novel scheduling software system for multimedia applications, (2) the measurement of quality parameters (e.g., skews, jitters) that are important for multimedia applications; and (3) evaluation of these measurements using uncertainties.
Our Dynamic Soft Real Time scheduling software system(DSRT) allows us to minimize the noises and to guarantee desired quality of service (QoS) for multimedia applications. We measure the quality of multimedia applications running under the classical time sharing scheduling system and the DSRT system. Evaluation of these measurements is performed using metrological evaluation methods. These methods allow us to quantify the improvements of the DSRT system using uncertainties and to optimize its performance.

Robert A. Ellis
UNCERTAINTIES OF VICKERS HARDNESS TEST BLOCKS

Uncertainties of Vickers hardness can be calculated for every individual Vickers hardness test block using the standardizing testing machine uncertainty components and the non- uniformity of the reference material. Unlike the Rockwell test for example, the test components can be directly related to the outcome of the uncertainty of the Vickers test. It can be shown in some cases that the reference uncertainty is larger than the accepted tolerances at the lower end of the hardness ranges.

Will Almeida, Bruno Costa, Raimundo Freire, Francisco Santos, Sebastian Catunda
UNCERTAINTIES PROPAGATION STUDY OF THE TRANSIT TIME METHODS IN ULTRASONIC ANEMOMETERS

The fluids speed measurement, particularly the air speed measurement is very important for industrial and laboratory applications. The ultrasonic method is among the most common methods used for determining the air speed. The basic principle to measure a fluid speed, using an ultrasonic transducer, is based on the modification of the apparent propagation speed of an ultrasonic signal caused by the fluid movement. Particularly, the method based on the Transit Time, which can use the techniques of Phase Difference and Time Difference, is one of the most used. In this work we carry on a comparative study of the uncertainty propagation employing these techniques in ultrasonic anemometers for determining the air speed.

R. M. H. Borges, I. M. G. Lemos, A. M. S. Antunes, L. A. d’Avila
UNCERTAINTIES SOURCES EVALUATION ASSOCIATED TO SULFUR AND FLASH POINT IN DIESEL FUEL

The international trade, the environmental protection and the science, today, cannot be able to exist without reliable measurements. Nowadays, any results of measurement of a physical or chemical quantity should be accompanied for any quantitative indication of the quality of this data, in order to be able to evaluate its reliability. Thus, an easy concept known and with wide acceptance that could characterize the quality of the result of a measurement is expressed by its uncertainty. In this work, we will present the application of the ISO GUM 95 for estimating uncertainty in the following tests: sulfur and flash point in diesel fuel. This research includes the development of a software based on Delphi version 6.0 to calculate the possible sources of uncertainty associated to the measurement used in both process and an estimation of their value, either by statistical methods (Type A) or by other means (Type B). Later on the individual components are combined to calculate the standard and expanded uncertainty for the whole process. The program developed aimed reducing the time spent in figuring out the main sources of uncertainty, moreover, facilitating the obtainment of the uncertainty result. To visualize the most relevant factor in the uncertainty measurement, the program provides a graphic showing the uncertainty contributions and enables the calculation of final uncertainty combined by the relative method, based on Eurachem/CITAC Guide, allowing the graphic comparison among the different methods in calculating uncertainty in measurement.

Wolfram Bremser, Werner Hässelbarth, Uwe Hirlehei, Hans-Jürgen Hotze, Bodo Mickan, Rainer Kramer, Dietrich Dopheide
UNCERTAINTY ANALYSIS AND LONG-TERM STABILITY INVESTIGATION OF THE GERMAN PRIMARY HIGH-PRESSURE NATURAL GAS TEST FACILITY pigsar

The high-pressure gas flow meter test facility pigsar operated by Ruhrgas AG serves for testing and calibration of turbine-wheel and ultrasonic meters for natural gas in the pressure range between 14 and 50 bar and flow rates ranging from 8 to 6500 m³ / h. Pigsar is the national standard of high-pressure natural gas flow under supervision of the German national metrological institute PTB. It represents and disseminates the unified German-Dutch reference value for the unit of volume for high-pressure natural gas. The uncertainty analysis of the test facility presented here was one of the main pre-requisites for the creation of the harmonised reference value.

Pasquale Arpaia, Marco Buzio, Luca De Vito, Mario Kazazi, Stephan Russenschuck
UNCERTAINTY ANALYSIS FOR A MOVING FLUXMETER

This paper presents an uncertainty analysis for field measurements by means of a moving fluxmeter. The measurement method has been analysed and the most relevant uncertainty sources have been characterised. Among all the sources, it has been found that those concerning the transport system lead the most relevant contribution to the uncertainty budget. Experimental results, aiming at characterising such sources and determining their contribution to the uncertainty of the measurement, are presented.

Felipe Jaloretto, Marcelo Souza de Castro
Uncertainty Analysis for Multiphase Flow: A Case Study for Horizontal Air-Water Flow Experiments

This work describes the procedure used to define the measurements uncertainties of experiments in horizontal air-water two-phase flow performed in order to identify influences due to pipe diameter. These experiments were performed with 4 different pipe diameters, always using the same test section length, therefore varying the length-by-diameter (L/D) ratio. Several parameters were measured, such as fluid flow, pressure, temperature and pressure drop; other parameters were calculated, such as the superficial velocities of each fluid, as well as their respective properties. The main parameters studied were the flow patterns for different velocity configurations and the two-phase pressure drop to be used for model improvement, thus the importance of uncertainties analysis. The sources of uncertainty were defined, detailed, systematically studied and quantified. The flow maps with its uncertainties could show the regions a pattern can be defined, and the plots of two-phase pressure drop variation with diameter validated the homogeneous model as a good approach to calculate pressure drop

V. Pop, P.P.L. Regtien, H.J. Bergveld, P.H.L. Notten, J.H.G. Op het Veld
UNCERTAINTY ANALYSIS IN A REAL-TIME STATE-OF-CHARGE EVALUATION SYSTEM FOR LITHIUM-ION BATTERIES

Lithium-ion (Li-ion) is the most commonly used battery chemistry in portable applications nowadays. Accurate State-of-Charge (SoC) and remaining run-time (tr) calculation for portable devices is important for the user convenience and to prolong the lifetime of batteries. A new SoC algorithm for Li-ion batteries that combines adaptivity with direct measurement and book-keeping systems has been developed and implemented in a real-time evaluation system.
In this paper the error sources in the real-time SoC evaluation system with possible calibration solutions are described. The goal of the SoC system is to predict the remaining run-time of a Li-ion battery with an uncertainty of 1 minute or better under all realistic user conditions, including a wide variety of load currents and a wide temperature range.

M. Catelani, L. Ciani, S. Giovannetti, A. Zanobini
UNCERTAINTY ANALYSIS IN HIGH-SPEED MULTIFUNCTION DATA ACQUISITION DEVICE

In instrumentation based on an analog-to-digital converter (ADC), the performance of data acquisition (DAQ) device has a direct impact on the performance index of the whole measurement system, so it has an important significance that research the uncertainty analysis of data acquisition board. This paper proposes an automatic measurement system based on DAQ board with automatic uncertainty evaluation of the measurement results according to the “guide to the expression of uncertainty in measurement” and its supplement. Theoretical aspects of the uncertainty analysis in high-speed multifunction data acquisition device and the LabVIEW interface carried out are analyzed and discussed.

Page 808 of 851 Results 8071 - 8080 of 8504