IMEKO Event Proceedings

Page 788 of 822 Results 7871 - 7880 of 8218

John D. Wright, Aaron N. Johnson
UNCERTAINTY IN PRIMARY GAS FLOW STANDARDS DUE TO FLOW WORK PHENOMENA

Static gravimetric and static volumetric gas flow standards are both affected by uncertainty components related to the measurement of the change of mass of gas within the inventory volume. In the process of diverting gas into the collection vessel, rapid pressure and temperature changes occur in the inventory volume. A low uncertainty gas flow standard requires thorough understanding of these transients so that appropriate instrumentation, system design, and operating procedures may be developed. A thermodynamic model for the flow work phenomena is presented and compared to experimental measurements and strategies for minimizing their effects on flow uncertainty are discussed.

F. Corrêa Alegria, A. Cruz Serra
UNCERTAINTY IN THE ADC TRANSITION VOLTAGES DETERMINED WITH THE HISTOGRAM METHOD

This paper, presents an innovative study of the uncertainty in the ADC transition voltages, determined by the Histogram Method for ADC testing. The new approach used, allows for a global and uniform overview of this subject, improving the existing knowledge about the workings of the Histogram Method.

Tohru Iuchi, Atsushi Gogami
UNCERTAINTY IN THE TEMPERATURE OF SILICON WAFERS MEASURED BY RADIATION THERMOMETRY BASED UPON A POLARIZATION TECHNIQUE

The emissivity behaviour of a silicon wafer under various conditions was theoretically and experimentally investigated. As a result, the quantitative relationship between the ratio of p-polarized radiance to s-polarized one, and polarized emissivities was obtained irrespective of the emissivity change of wafers due to the oxide film thickness under the wide variations of resistivity. Based on the result, we propose a new radiation thermometry method that can measure both the temperature and the spectral polarized emissivity of the silicon wafer, and estimate the uncertainty of the measurements. Currently, the uncertainty of the temperature measurement is estimated to be 3.52 K (k = 2) and 3.80 (k = 2) for p-polarization and s-polarization, respectively, in the temperature range over 900 K.

Dieter Kenzler, Jörg Oblasser, Andreas Subaric-Leitis, Christian Ullner
UNCERTAINTY IN TORQUE CALIBRATION USING VERTICAL TORQUE AXIS ARRANGEMENT AND SYMMETRICAL TWO FORCE MEASUREMENT

Calibration machines up to a torque range of 20 kN·m need extensive design if the force is performed by dead weights. A machine based on two force reference standards and a vertical torque axis may serve to avoid these specific problems. The precision force transducers work at a lever arm of precision length. The test piece is mounted in vertical arrangement between a hydraulically operating rotary-actuator and the torque measuring system. Such a calibration machine allows additionally performing easily continuous calibration. Regarding an overall relative uncertainty not greater than 2·10-4 there are some significant problems. The estimation of the uncertainty has been proved by comparative tests with the national torque standard by the PTB according to the guidelines EA-10/14 and EA-2/03.

K. Torokhtii, A. Alimenti, N. Pompeo, E. Silva
Uncertainty in uncalibrated microwave resonant measurements

We present an extended study on the uncertainty in resonant measurements. The uncertainty of the resonant frequency and quality factor was estimated. The effect of the use of uncalibrated resonant curve on uncertainty was extensively studied. For the uncalibrated data the systematic contribution to uncertainty was determined.

Ranny Michalski, Marco Nabuco, Gustavo Ripper
UNCERTAINTY INVESTIGATION OF FIELD MEASUREMENTS OF AIRBORNE SOUND INSULATION

Sound insulation is very important for the acoustic quality of buildings. The Brazilian Association of Technical Standards, ABNT, published a set of standards concerning the evaluation of the performance of buildings up to five floors, ABNT NBR 15755, and sound insulation is one the considered topics. Minimum, intermediate and superior values are presented for some acoustic parameters. In order to make measurements carried out by different professionals comparable with the values established in the standards, the uncertainty of the results shall be expressed. The Guide to the Expression of Uncertainty in Measurement, ISO/IEC Guide 98 (GUM), is the international document that standardizes how to assess the uncertainty of a measurement result.
In general, two types of methods are used to measure sound insulation parameters: the classical method and the new method or impulsive response method. However, there is not an established and simple procedure to obtain the measurement uncertainty. Uncertainties estimates are available only for the classical method.
Measurements of airborne sound insulation between rooms were carried out in field conditions with the impulse response method and the work presents a study of the estimate of the uncertainties of the results, in accordance with the GUM.

Salvatore Caldara, Rosario Miceli, Pietro Romano, Ciro Spataro, Fabio Viola
Uncertainty management in the measurements of low frequency magnetic fields

The paper deals with low-frequency magnetic field measurements carried out by using a broadband and isotropic instrument. These measurements are characterized by very high uncertainty values, which imply a high risk of wrong decisions when there is the need to establish if a site complies or does not comply with specified emission limits. To reduce this risk, we decided to perform the so called “uncertainty management” that is the discipline of optimizing the cost of a measurement versus the uncertainty target. The task is achieved by using the PUMA method that is an iterative technique originally conceived for geometrical and mechanical measurements. The approach is completely based on the “Guide to the Expression of Uncertainty in Measurement” rules, but provides a more engineering methodology. By using this approach, it is possible to avoid the usage of too expensive instrumentations or, on the contrary, too expensive resources for the uncertainty estimation.

Yuri Machekhin
UNCERTAINTY MEASUREMENT AND DYNAMIC SYSTEM CHAOTICAL BEHAVIOUR

Chaotic behaviour of nonlinear dynamic system as a mechanism of influence on uncertainty measurement are discussed. Based on the logistic equation as a mathematical model, measeurement uncertainty investigated. In the case when dynamic chaos take place in the system, uncertainty measurement has anormal distribution.

Jan Blaška, Miloš Sedláček
UNCERTAINTY OF AMPLITUDE DFT SPECTRUM ANALYSIS IN POWERLINE SYSTEMS

Characterization of measurement by uncertainty becomes a commonly accepted practice. Since in case of several sources of uncertainties which may even be correlated finding the resulting uncertainty according to the Guide to the Expression of Uncertainty in Measurements [1] is not an easy task, computer simulations are a suitable tool respecting the possible correlations of quantities influencing uncertainty. Analysis of DFT spectrum uncertainty was published elsewhere for coherent sampling. We compare correction factors and remaining uncertainties of two methods of the DFT spectrum analysis applicable for noncoherent sampling. Simulations are performed on power-line frequency with predefined harmonic components and noise and ideal quantizer with selectable resolution.

Edi Kulderknup, Viktor Krutob, Jürgen Riim
UNCERTAINTY OF BRAKING PARAMETERS MEASUREMENTS BY VEHICLES TECHNICAL INSPECTION

Nowadays more widely is taken to use the road vehicles periodical inspection with aim to have knowledge of the technical level of item and to assure the safety. To have the assured right inspection results there shall be used various testing and measurement procedures. Among of the important are measurements of the parameters showing the road vehicles brakes correct operation. To give proper conformity estimation to the vehicles brakes operation shall be used uncertainty of measurement result. To give more confidence to the estimated uncertainty components suitable way is to carry out measurement comparisons of brakes parameters.

Page 788 of 822 Results 7871 - 7880 of 8218