IMEKO Event Proceedings

Page 813 of 851 Results 8121 - 8130 of 8504

Saher R. Gawda, A. Abu-Sinna, M. I. Mohamed, Moanes M. Mohamed, Ali E. Abuelezz

To determine the confidence of the test results, it is necessary to evaluate the main factors contributing to the uncertainty in Charpy impact measurements (pendulum impact). These factors are: the uncertainty of reference force and length measuring devices and its long term instability (drift), machine resolution, rated energy error, indicated energy error, losses due to the drag of the pointer, friction losses in the bearing and air resistance, and other geometric parameters. In this study the calibration process based on the relevant international standard is explained. Most of the uncertainty elements are identified and directly verified. Other elements that could not be directly verified are analyzed or assessed using the available information.

M. Abbe, M. Nara, K. Takamasu
Uncertainty evaluation of CMM by modeling with spatial constraint in error

A noble simulation method for evaluating task specific uncertainty in coordinate metrology is proposed. Provided that specification or test result conforming to ISO 10360-2 is available, both variance of point coordinates and covariance expressing the mutual influence is handled to perform Monte Carlo simulation reflecting spatial constraint in error of CMM. Development and implementation of the over all procedures are pursued to apply them on real CMM. Comparison result between uncertainties obtained by the proposed method and that by experimental measurements shows good agreement. However the worst shows 1 μm over-estimated, and the functionality and the characteristic of ease to use are validated.

G. Raiteri, A. Bordone, T. Ciuffardi, F. Pennecchi
Uncertainty evaluation of CTD measurements: a metrological approach to water-column coastal parameters in the Gulf of La Spezia area

The ENEA Marine Environment Research Centre S. Teresa has been involved since the ‘70s in monitoring, analysis and comprehension of physical, chemical and biological processes in marine environment. The purpose of this work is to describe the recently-implemented metrological approach aimed to evaluate the uncertainty associated with measurement results obtained by a Conductivity-Temperature-Depth profiler (CTD), deployed during routine coastal campaigns in the Eastern Ligurian Sea, close to the Gulf of La Spezia area. Main effort of this work is focused on applying the standard framework necessary to correctly assess the measurement uncertainty for each involved parameter. To this aim, an appropriate uncertainty evaluation is performed by combining type A and B contributions, evaluated from experimental data measured in reproducibility conditions and from calibration certificates periodically supplied by manufacturer, respectively.

E. Balestrieri, M. Catelani, L. Ciani, S. Rapuano, A. Zanobini

The paper proposes a novel approach to evaluate the measurement uncertainty of time domain dynamic parameters in Digital to Analog Converters (DACs). In particular, DAC rise time and fall time are taken into account and analyzed experimentally by means of dedicated measurement stations. The uncertainty of such measures is evaluated using the bootstrap method in order to define confidence intervals from short acquisition records without needing hypotheses about the measurand distribution.
The final aim of this work is to give a contribution, in terms of uncertainty assessment, for the draft of IEEE Std.1658 concerning terminology and test methods for DACs.

Clemens Elster, Sascha Eichstädt, Alfred Link

We consider the task of uncertainty evaluation in the context of dynamic measurements. We assume that the relation between the time-dependent value of the measurand and the available output signal of an employed sensor is governed by a linear time-invariant system. Estimation of the measurand is done by applying a digital filter to the sensor's output signal. We propose a method for uncertainty evaluation which is in line with the Guide to the Expression of Uncertainty in Measurement (GUM). The method accounts for dynamic errors due to non-perfect compensation of the dynamic behavior of the sensor, and it allows for real-time calculation when a causal digital filter is employed. The proposed uncertainty calculation method can be used to design an uncertainty-optimum filter. We illustrate the procedures in terms of a simple example.

Jin-Seok Chang, Sang-Gu Lee

KTL has forced piston gauge which generate very low pressure (1 Pa ~ 1400 Pa) stable. Prior to forced piston gauge, we calibrate with digital manometer or capacitance diaphragm gauge below 1400 Pa (uncertainty: 0.011 %). This paper will introduce uncertainty evaluation of new standard by means of cross-float.

Jiong-Shiun Hsu, Sheng-Jui Chen, Hui-Ching Lu, Shear-Shi Pan, Gwo-Jen Wu, Chung-Lin Wu, Chin-fen Tuan

The uncertainties of nanoindentation measurement system were evaluated in this paper. A precise electonic balance and an optical interferometric system were respectively utilized to calibrate the force and displacement of nanoindentation measurement system. The uncertainties of reduced modulus and indentation hardness providing from the naoindentaion measurement were respectively obtained.

Álvaro Silva Ribeiro, Maria do Céu Almeida, João Palma

Technical requirements and economical impacts of flow measurements in sewer systems are a issue concern in today's system's management. Thus, the quality of the measurements is considered to be a critical issue. Considering the complex nature of the measurand and the metrological requirements of local installations, the best available level of accuracy in measurement results should be sought. Therefore, both the knowledge of the measurand estimates and measurement of uncertainties are required for achieving robust results.
Within this context, the quality of measurement results depends on the knowledge of the uncertainty contributions and on the selection of an appropriate method to evaluate the measurement uncertainty. The study of these aspects can be of major importance in providing information to management of the system, namely in the selection of appropriate technology, upgrading and maintenance activities.
The Monte Carlo method is used in this paper to carry out the evaluation of the measurement uncertainty, considering its inherent capacity to deal with non-linear and multi-stage mathematical models. Influence of geometric conditions and other relevant parameters in the quality of measurements is discussed. The study was developed within the context of a specific sewer system, using a particular measurement system, from which measurement data was gathered.

Miliadis, G., Tsiantas, P., Paraskevaidi, K., Siragakis, G.
Uncertainty evaluation of parameters used in LC-MS/MS system suitability for the determination of pesticide residues

Parameters used to assess LC-MS/MS system suitability for the determination of the concentration of pesticide residues in food are the retention time, the ion ratio, the signal to noise ratio and the slope of the calibration line.
The EU tolerance values of the first two of these parameters have changed more than one time during the last years in the SANTE Document (last edition 11945/2015), they are differentiated from the respective tolerances mentioned in the Commission Decision 657/2002, and have been subject of debate.
In the present study system suitability parameters of LC-MS/MS were evaluated under the same LC- MS/MS conditions at concentration 0.01µg/mL, over 28 months’ period. Six representative compounds were used for this purpose and the respective control charts were constructed. The uncertainty values of these parameters were evaluated and compared to respective values of the literature.

Christian Schlegel, Gabriela Kiekenap, Rolf Kumme

Periodical force measurement is used for the primary calibration of force transducers. This abstract describes models for an uncertainty determination of the sensitivity, which is the main measurand. Influences like the mechanical coupling of test masses as well as their rocking during a measurement are the dominating contributions to the uncertainty of measurement. The achievable uncertainties will be demonstrated on the basis of intercomparison periodical force measurements between CEM and PTB as well as the comparison between standard GUM and Monte Carlo based uncertainty evaluation.

Page 813 of 851 Results 8121 - 8130 of 8504