IMEKO Event Proceedings

Page 809 of 851 Results 8081 - 8090 of 8504

Valmir Ruis, Noemi Christina Hernandez
UNCERTAINTY ANALYSIS IN PISTON PROVER CALIBRATION

This paper presents main uncertainties sources, differential equations analysis and the estimation of combined uncertainty in the calibration of a compact piston prover of the IPT Flow Laboratory.
The piston prover is used mainly for calibration of liquid flow meters as turbine meters, positive displacement meters and rotameters. Calibration of other types of liquid flow meters can also be performed provided its particularities are taken into account.
The procedure used was the gravimetric method with static weighing using water (Water Draw) as described in ISO 4185/80 Measurement of liquid flow in closed conduits - weighing method. The uncertainty analysis was made according to the ISO GUM - International Standard Organization - Guide to the Expression of Uncertainty in Measurement.

Simone Turrin, Subanatarajan Subbiah
Uncertainty Analysis in Prognostics for Optimal Maintenance

Reliable prognostics have become indispensable to provide predictive service solutions. In fact, by assessing the residual useful life of a product, a condition-based maintenance strategy can be adopted. Consequently, the appropriate service activity can be assigned and scheduled only if and when required. Hence cost and time related to unnecessary preventive service tasks is saved. Prognostics algorithms are usually affected by different types of uncertainties stemming, for example, by randomness and lack of knowledge in the degradation behaviour, the inherent failure mechanism and the usage of the product by the customer. Such uncertainties can have potentially large effects on the determination of the residual useful life and, consequently, on the planning and scheduling of the subsequent service activity. This paper is focused on the customer usage as a main source of uncertainty. A statistical and a fuzzy approach are presented. The application case is given by the determination of the electrical overhaul for a generator circuit breaker (GCB). Nevertheless, the suggested approaches can be generally used for any type of products.

Fernando M. Janeiro, Frank Wagner, Pedro M. Ramos, A. M. Silva
UNCERTAINTY ANALYSIS OF A CLOUD BASE HEIGHT MEASUREMENT SYSTEM BASED ON DIGITAL PHOTOGRAPHY

Cloud height is an important parameter in both air safety and weather monitoring. The authors have previously developed a low-cost cloud height measurement system based on stereovision and digital photography. In this paper, the cloud height uncertainty is derived for the previously developed system. The main sources of uncertainty are identified and improvements to the measurement system are proposed.

C.Divieto, G.Sassi, M.P.Sassi
UNCERTAINTY ANALYSIS OF CELL COUNTING BY METABOLIC ASSAYS

Cell counting is an important procedure in cell biology and its uncertainty evaluation is fundamental to improve cell-based measurement comparability which is currently variable. In this study, for the first time, the uncertainty of a metabolic assay for cell counting based on fluorescence intensity measurement has been evaluated. Results, in 2D cell culture, revealed that three are the main components: repeatability and reproducibility of the measurement system and a contribution due to the sample loading step procedure. This study represents the basis of a 3D cell culture in which metabolic methodologies are the most suitable method to monitor cell growth.

Jerzy Augustyn
Uncertainty Analysis of Impedance Measurements in the Sampling Sensor Instrument

The algorithms based on digital signal processing for impedance components’ evaluation in circuits with sampling transducer have been analysed. It is supposed that the voltage and current are sampled synchronously to the fundamental frequency of the generated sinusoidal signal. Two fitting sine wave algorithms, which are based on the least mean square (LMS) technique, have been described. The first one reconstructs indirect measurement method. The second algorithm estimates the unknown impedance components by direct method. The uncertainty’s propagation by described algorithms can be analysed by means of covariance matrix. The elements of covariance matrix are dependent on the phase angles of the measurement signals. It is shown that those algorithms provide minimization of uncertainty for selected number of samples and phase angles. The influence’s simulations of quantization error of the AD converter and jitters of sampling time for described algorithms on uncertainty processing results have been carried out.

Aaron N. Johnson, Chris J. Crowley, TT Yeh
Uncertainty Analysis of NIST’s 20 Liter Hydrocarbon Liquid Flow Standard

The National Institute of Standards and Technology (NIST) uses a bi-directional 20 L-displacement piston prover as its primary standard for measuring hydrocarbon liquid flows ranging from 1.86 × 10-5 m3/s (0.3 gpm) to 2.6 × 10-3 m3/s (40 gpm). Our analysis that shows that the prover’s uncertainty over this flow range is 0.074 % (k = 2, corresponding to a 95 % confidence interval). Using a dual rotor turbine meter as the transfer standard, we compare the new 20 L piston prover standard with NIST’s other hydrocarbon liquid standards and NIST’s water flow standard. The results are consistent with the presented uncertainty analysis.

Erasmo F. Vergara, Jovani A. Steffani, Samir N. Y. Gerges, Marcos A. Pedroso
UNCERTAINTY ANALYSIS OF NOISE EXPOSURE MEASUREMENTS FOR HEADPHONE USERS

Noise emissions from sources located close to the ear, such as the headphones of telemarketing operators are determined using the international standard ISO 11904. The MIRE and manikin techniques are applied simultaneously to estimate the levels of noise exposure. The uncertainties from different sources are estimated for the determination of the diffuse-field related equivalent continuous A-weighted SPL from an earphone.

Takashi Shimada, Ryouji Doihara, Yoshiya Terao and Masaki Takamoto
Uncertainty Analysis of Primary Standard for Hydrocarbon Flow at NMIJ

The uncertainty of the primary standard for hydrocarbon flow measurements at NMIJ has been evaluated experimentally and analytically in detail. The primary standard is based on the static and gravimetric method with a flying start and finish at flow rates in the range between 3 and 300 m3/h. It consists of two separated test rigs with kerosene and light oil as working liquids. The expanded uncertainty is estimated to be better than 0.03 % for volumetric flow rates and 0.02 % for mass flow rates (coverage factor k = 2). The dominant sources of combined uncertainty of the flow rate are the mass of the oil accumulated in the weighing tank and the density of the oil flowing through the flowmeter being tested. A Coriolis flowmeter, a turbine meter and an ultrasonic flowmeter have been calibrated in both test rigs in order to verify the performance of the facility. The results indicate that the expanded uncertainty estimated analytically is adequate.

F. Corrêa Alegria, A. Cruz Serra
UNCERTAINTY ANALYSIS OF THE ADC HISTOGRAM TEST USING TRIANGULAR STIMULUS SIGNALS

This paper addresses the uncertainty of the estimates of ADC testing obtained with the Histogram Method when a triangular stimulus is used. Expressions are presented for the computation of the standard deviation of the transition voltages and code bin widths. These can be used for the Ramp Vernier Test which is a novel test method which will be included in the new version of the IEEE 1057 standard currently in balloting.

A. Lazzari, G. Iuculano, A. Ponterio
UNCERTAINTY ANALYSIS ON AN OPTICAL MACHINE WITH VISION SYSTEM FOR THREE-DIMENSIONAL MEASURING WITHOUT CONTACT

In order to rise to the traceability of the optical machine equipped with a television camera CCD (Charge Coupled Device), the purpose of this paper is to evaluate the ability of the optical machine to provide measurements, the dispersions of which are compatible with the specified tolerances and the dispersions of the process that is measured. Referring to the principles of the Statistics Inference, the purpose is to verify that the performance of the optical machine is in conformity with what the builder have stated, both in reference to the capability of the optical machine measurement to be in a sufficiently little interval around the expected value and in reference to the measurement variability. The analysis of experimental data seems that the results are very appreciable. The paper presents the basic ideas for evaluating the uncertainty expression in a measurement process of an optical machine equipped with a television camera CCD: this will allow to qualify the optical machine in each part as well as on the whole, since till today no metrological traceability of this equipment in primary metrology is provided, neither in national (SIT) nor in international level (EA).

Page 809 of 851 Results 8081 - 8090 of 8504