IMEKO Event Proceedings

Page 814 of 851 Results 8131 - 8140 of 8504

D. T. Nguyen, W. Kang, Y. M. Choi, S. H. Lee, Y. M. Choi
Uncertainty Evaluation of Stack Flowrate Measurement with S-Type Pitot Tube by Monte Carlo Method

In order to attempt to mitigate the climate change, efforts to reduce the quantity of carbon emissions by actively seeking CO2 trading and carefully control the liability of the emission test monitoring system from the industrial factories are a current issue. Therefore, the quality of greenhouse gas (GHG) emissions measurement with a proper uncertainty needs to be firstly considered. Currently, GHG emissions are estimated by a continuous emission measurement (CEM). The U.S Environmental Protection Agency (EPA), has classified the measurement of GHG emissions by the CEM as the highest quality Tier IV with lowest uncertainty level. Relating to accuracy of the CEM, both knowledge of the uncertainty contributions on GHG concentrations and volumetric flow rates are necessary for achieving a credible result. In order to accurately evaluate the uncertainty of the CEM method, flow rate measurements in the stack as well as GHGs concentration measurements by gas analyzer are crucial due to various uncertainty factors. In this study, we concentrate on finding measurand inputs and their uncertainty estimates that affect volumetric flow rates in a heat and power generation plant. Both the law of propagation method and Monte Carlo method (MCM) are used to evaluate the uncertainty of the flow rate measurement in order to minimize the numerical approximation of the partial derivatives of the complex model with respect to the every input. Consequently, the result of MCM is consistent with the result that by the law of propagation of uncertainty. The relative expanded uncertainties at 95% confidence level with coverage factor k = 2 are 528.1 m³ and 527.2 m³, respectively.

Koji Ohgushi, Takashi Ota, Kazunaga Ueda

A deadweight-type torque standard machine of 20 kN·m rated capacity (20 kN·m-DWTSM) has been designed and developed by the National Metrology Institute of Japan (NMIJ) at the National Institute of Advanced Industrial Science and Technology (AIST). Each uncertainty contribution comes mainly from the performance of each mechanical part of the 20 kN·m-DWTSM. Authors evaluated the uncertainty of the mass of the linkage weights, local acceleration of gravity, influence of air buoyancy on deadweight loading, initial moment-arm length (including CMM measurement and temperature compensation), and sensitivity of the fulcrum. This report deals especially with evaluation of the remaining contributions, namely the influence of arm flexure and reference line variation at the end of the moment-arm on best measurement capability (BMC). Estimation of BMC in the 20 kN·m-DWTSM gave a relative expanded uncertainty of less than 7.0 × 10-5 (k = 2) for the calibration range from 200 N·m to 20 kN·m.

Jiong-Shiun Hsu, Chi-Shen Chang, Yu-Yi Su, Jeah-Sheng Wu, Sheau-Shi Pan

In this paper, the uncertainty of nanoindentation system was evaluated. The laser interferometer and electronic balance were respectively adopted to calibrate the quantities of displacement and load of nanoindeantion system. The results reveal that the relative expanded uncertainty of indeantion hardness, UH, is 8.1%. The relative expanded uncertainity of reduced modulus, UEr, is 5.4%.

Anton Štibler, Konrad Herrmann

A commercial hardness testing machine has been provided to represent a reference hardness standard in Slovenia. Various hardness scales which are important for calibration purposes are realized on this machine. The evaluation of measurement uncertainty is one of the most important tasks for establishing this reference standard. Therefore the influence quantities contributing to the uncertainty are determined and the calibration of the machine by direct and indirect method is carried out. Calculations of measurement uncertainties for Brinell, Vickers and Rockwell hardness scales are presented. The hardness scales for Brinell HBW 2,5/187,5; HBW 2,5/62,5; HBW 2,5/31,25, Vickers HV 30 and Rockwell are subject of uncertainty determination in this paper.

Fu-Lung Pan, Yu-Yi Su

Center for Measurement Standards (CMS) had established a thin-film indentation testing system based on Akashi MZT-522. The electronic balance was made use of calibrating the testing force and the internal depth sensor was calibrated by laser hologauge. Five other uncertainty was also evaluated in the paper. Finally, the uncertainty of the thin-film indentation testing system reached a total of 5.02 %.

A. S. Ribeiro, D. Loureiro, M. C. Almeida, M. G. Cox, J. A. Sousa, M. A. Silva, L. Martins, R. Brito, A. C. Soares
Uncertainty evaluation of totalization of flow and volume measurements in drinking water supply networks

Clean water and sanitation are one of the 17 sustainable development goals (SDG) of the United Nations’ 2030 agenda for action, being directly related to several other objectives, namely, economic growth, sustainable cities’ communities, responsible consumption and production, and climate action. Since demand for this resource is constantly growing, problems of scarcity of water and transboundary issues are becoming critical to increase water supply efficiency and to improve water management in modern society. Water providers make use of large infrastructures – water supply networks – defined as engineering systems based on hydrological and hydraulic elements able to supply water to consumers, industries, facilities, services and other users. These infrastructures rely on the quality of measurement as a condition to management, having a relevant role in the process of decision-making and to deal with the common problem of water losses. Good measurement practices and uncertainty evaluation are needed to support robust analysis in urban water supply systems. For many water utilities the evaluation of uncertainty is still considered a difficult task, often in situations of missing data for the analysis, having to deal with large amounts of raw and processed data, and requiring support to apply the provisions of the Guide to the expression of uncertainty in measurement (GUM). However, the application of the GUM to the simple mathematical models used in this context makes it possible to obtain simplified equations that can be used in specific conditions of measurement, providing support to non-expert users with more straightforward approaches. Those include measurement of constant flow, totalization of volume at a single measurement point, and sums and differences obtained by combining branches of a network.

Michal Lisowski, Ryszard Kacprzyk
Uncertainty Evaluation Problems in Measurements of Volume and Surface Resistivities

The problems associated with evaluation of uncertainty of volume and surface resistivities were presented in the paper. Special attention was paid to the measurements carried out on extremely high resistivity materials. Different factors affecting the uncertainty were classified and estimated. A simplified method of uncertainty evaluation was proposed.

Andrea Zanobini, Gaetano Iuculano, Gabriella Pellegrini
Uncertainty Evaluation: Analysis of Simultaneous Measurement of Multiple Measurands

The Guide to the expression of uncertainty in measurement (GUM) (ISO,1995), contains internationally agreed recommendations for the evaluation and expression of uncertainties in a measurement process, providing valuable advise for constituting the model that relates input to output quantities.
If a probability density function is associated with each of input quantities, a probability “region” for the outputs quantities (the measurands) can be derived and its level of confidence may be evaluated by analytical or numerical methods.
This paper analyzes the uncertainty evaluation of a process concerning simultaneous measurement of multiple measurands on the base of the fundamental properties of the probability confidence region.

J. Sola, F. J. Brosed, J. J. Aguilar

The Guide to the Expression of Uncertainty in Measurement has some limitations, especially for systems with complex mathematical models. In this article, two alternative methods to obtain the measurement uncertainty (Monte-Carlo simulation and calibration based on experimental measurement) are compared. These methods are widely used to calculate the measurement uncertainty of measurement systems. The advantages and disadvantages of these two methods are going to be studied estimating the uncertainty of the flatness measurement using a system based on laser triangulation. The measurement system captures images of the laser plane projected in the surface to be digitalized. The laser pointsin each image are identified and extracted and transformed into 3D coordinates to calculate the flatness of the surface. The influence of different factors will be characterized and the results of the estimation of the uncertainty with both Monte Carlo simulation and the calibration based on experimental measurement will be compared as well as the characteristics and requirements of each procedure.

Joan Gomez-Clapers, Albert Serra-Rocamora, Ramon Casanella, Ramon Pallas-Areny
Uncertainty factors in time-interval measurements in ballistocardiography

There is a growing interest on measuring time intervals between the J peak of the ballistocardiogram (BCG) and several features of other cardiovascular signals such as the ECG in order to obtain cardiovascular function markers. Nevertheless, possible uncertainty factors involved in these measurements have not been identified and analyzed, which is a necessary step to advance towards standardization in this reemerging biomedical engineering field. In this paper we analyze the effect of the low-pass cutoff frequency and phase characteristic of filters, noise and power line interference on J-peak time measurement. We conclude that BCG acquisition systems require a minimum low-pass cutoff frequency of 25 Hz but the phase angle of filters at this frequency introduce more than 6 ms delay that increases with increasing filter order. Further, SNR and power line interference levels respectively below about 25 dB and 30 dB, commonly found in data acquisition systems in this area, may lead to uncertainties in the time position of the J peak of tens of milliseconds, which are comparable to measured time interval changes that may have diagnostic interest.

Page 814 of 851 Results 8131 - 8140 of 8504