IMEKO Event Proceedings

Page 10 of 748 Results 91 - 100 of 7479

S. Davidson
A comparison of primary platinum-iridium kilogram mass standards among eighteen European NMIs

The kilogram is unique among the base SI units in being the only one defined by an artefact rather than with relation to naturally occurring physical constants. A major problem with maintaining the traceability of the mass scale is the inherent instability of the kilogram artefacts. National standard kilograms accrete surface contamination over time which leads to an increase in their mass values. Without reference to the international prototype kilogram it is difficult to assess the magnitude of this mass gain and the traceability of measurements is compromised to some extent. This comparison examined the values of the national standard kilogram of 18 European NMIs, each of which uses an algorithm to predict the mass gain of their national standard. The results have been used to evaluate the accuracy of these algorithms and also to recommend a best-fit algorithm for the modelling of mass gain of national standard kilograms.

S. Nattapon, S. Tassanai
A COMPARISON OF PURELY STATIC AND CONTINUOUS TORQUE CALIBRATION PROCEDURE

This paper presents the results of calibration procedure comparison in pure torque measurement with a synchronous system between the purely static (step-by-step) and continuous (quasi-static) facilities in order to prove the influence of the procedural conditions on the uncertainty of calibration. The filter setting (Low pass Bessel: 0.2 Hz, 1.25 Hz, 5 Hz and 10 Hz) and speed of applying torque (≈ 0.7 % of full scale/sec to ≈ 2.8% of full scale/sec) were varied to examine the effects of both parameters on the measurement results and to optimize the continuous procedure. The measurement was made by a torque calibration machine (TCM) with a reference torque transducer and the HBM MGCplus amplifier system using a comparison method.
The results of this experiment show the deviation between the purely static and continuous procedure within ± 0.01% of reading that was enough for class 0.2 torque measuring devices (DIN 51309) and torque transfer wrench (DAkkS-DKD-R 3-7) calibration. For the step-by-step measurement, the duration time in each torque step (form applying torque to data record) must be adequate for steady state of filter setting. For the continuous measurement, the speed of applying torque and filter setting should be optimized for best measurement capability.

Daniela Ichim, Franco Pavese
A COMPARISON OF THE INITIAL UNCERTAINTY BUDGET AND AN ESTIMATE OF THE POSTERIOR UNCERTAINTIES, IN THE CASE OF LARGE BATCHES OF CALIBRATION DATA: THE LHC THERMOMETERS AT CERN

The paper will describe the techniques that have been used to perform the comparison on large batches of cryogenic semiconductor-type thermometers, calibrated for the CERN LHC and the main results obtained: they concern either the uncertainty of the CernoxTM thermometers under calibration and the behaviour of the standards used during the calibrations.

J. Jokela, F. Pollinger, N. R. Doloca, K. Meiners-Hagen
A COMPARISON OF TWO WEATHER DATA ACQUISITION METHODS FOR THE CALIBRATION OF THE PTB GEODETIC BASELINE

The Physikalisch-Technische Bundesanstalt has recently refurbished its geodetic baseline in Braunschweig, Germany, and the baseline is now supplied with an inclusive set of environmental sensors for weather observations. The Finnish Geodetic Institute calibrated the baseline in June 2011. In the calibration, the observers also used conventional instruments, common in surveying work, to obtain weather data. By comparing the two weather data sets and the results computed when using them, it is possible to demonstrate the good capability of conventional instruments, when properly used. The results of the comparison, which are applicable in electronic distance measurements for conventional surveying, are presented in this paper.

Ercihan Kiraci, Glen A Turley, Alex Attridge, Alan Olifent, Mark A Williams
A COMPARISON STUDY OF ON-CMM LASER SCANER AND TOUCH TRIGGER PROBE FOR AUTOMOTIVE MEASUREMENT APLICATIONS

Coordinate Measuring Machines (CMMs) are considered as the most accurate metrology equipment and are used widely in the manufacturing sector. Traditionally, touch trigger probes have been employed but more recently non-contact laser scanning sensors have been developed, offering potential advantages in terms of speed and number of points captured. Laser scanning is attracting significant interest from industry due to its ability to characterise complex, free-form surface geometries which are becoming common in the styling of automotive body panels. However, laser scanning sensors do not currently offer the accuracy and repeatability that can be achieved with touch trigger probes. Furthermore, there are no recognised standards for qualifying non-contact probes, making reliable verification of measurements difficult to achieve. Past research has attempted to qualify the capability of different non-contact probing technologies using small artefacts designed for technology validation; however, little work has been done on the verification of on-CMM laser scanning technologies for large volume, industry-relevant measurement applications. This study used a full-scale machined physical representation of a sheet metal vehicle body to evaluate the measurement agreement and repeatability of a laser scanning sensor, relative to touch trigger probe measurements, mounted on a horizontal arm CMM using individual surface points, edge points and circular holes, located across the entire structure. Through the use of a static repeatability analysis it was found that there was good correlation between touch trigger probe and laser scanner measurements. Repeatability of the laser scanner was found to be better than 28 µm for surface, edge and circular holes measurement. Accuracy of the laser scanner relative to the touch trigger probe measurements fell within a range of 50 µm which is a factor of 10 lower than typical automotive body-shell manufacturing tolerances. The results collected demonstrate that laser scanning sensor and CMM used in this study would provide a level of accuracy and repeatability better than which is typically required by automotive manufacturers for body-in-white quality inspection applications.

Ireneusz Jablonski, Adam G. Polak, Janusz Mroczka
A COMPLEX MATHEMATICAL MODEL OF THE RESPIRATORY SYSTEM AS A TOOL FOR THE METROLOGICAL ANALYSIS OF THE INTERRUPTER TECHNIQUE

The paper presents the issue connected with the construction and simulations of the complex mathematical model of the respiratory system for the interrupter technique. Combining morphometric data for the consecutive segments of the object (assumption on symmetrical structure of the bronchial tree) with information on existence and proportions between the processes, proper for the interrupter experiment, resulted in an exact imitation of the occlusion conditions, both in the time and frequency domain. It is expected that the model will be a base for design of the simple and reliable diagnostic test dedicated to the respiratory mechanics measurement. From this point of view, the proposed complex mathematical analog of the respiratory system during airflow interruption is a forward model in the forward-inverse scheme of cognition.

M.C.Brinzila, C.Fosalau, E.Lunca, M.Cretu
A COMPLEX SYSTEM FOR ENVIRONMENTAL MONITORING WITH A PROTOTYPE DATA ACQUISITION BOARD

In the present paper is presented a method for on-line measurement using a complex system for environmental monitoring whit a prototype data acquisition board. A study for Taguchi-type gas sensor using the data acquisition board will be performs.

Fazil Syed, Faheem Mohammad, Luai M. Al-Hadhrami
A COMPREHENSIVE OVERVIEW OF THE LASER BASED CALIBRATION FACILITY AT MEASUREMENT STANDARDS LABORATORY

Non-destructive testing (NDT) describes a wide range of methods for measuring and comparing physical quantities against a nominal condition. The most familiar laser based optical non destructive methods are based on the interference of wave fronts of monochromatic light reflected from a test surface. This paper will focus primarily on the profound review of operating principles of laser based non destructive methods involved with the measurement principles at Measurement Standards Laboratory (MSL). Michelson Inteferometric Principles with emphasis on minimizing alignment errors for better results will be assessed. The paper also enlists the discussion about airy points and its impact on measurement results. Uncertainties associated with the measurement results have been estimated using the GUM: Evaluation of measurement data — Guide to the expression of uncertainty in measurement procedures. The Agilent 5530 Laser Calibration Facility does provide the much needed Flexibility and better control. The necessary compensation factors including wavelength, air and material compensation factors with their due influence on the repeatability of the measurement results are studied. The range of optics involved in the measurement process both in linear and angular measurement procedures will be evaluated. A summary overview of different errors like Cosine, Abbe, and Dead path Errors resulting from the measurement of laser based dimensional parameters will be discussed with profound insight. By virtue of the high quality of its calibration services, MSL has gained national and international recognition to the kingdom of Saudi Arabia. It provides expertise and state-of-the art measurement infrastructure to ensure that the accurate calibration results are achieved with high degree of reliability. Precision engineering measurements at MSL are traceable to national and international calibration laboratories such as National Institute of Standards and Technology (NIST), USA, Physikalisch Technische Bundesanstalt (PTB), Germany, National Physical Laboratory (NPL), UK, Commonwealth Scientific Industrial Research Organization (CSIRO), Australia and more.MSL operates under the Total Quality Management Scheme and in conformity with ISO/IEC-17025: General requirements for the competence of testing and calibration laboratories guidelines. The information presented in this paper is most useful to the metrological organizations, who want to get enriched with comprehensive and exhaustive study involving the laser based measurement systems. This research grade laser based non destructive system will improve the metrological capabilities and will be of greater importance to the industrial community at large in Saudi Arabia.

David Samper, Jorge Santolaria, Jorge Juan Pastor, Juan José Aguilar
A COMPREHENSIVE SIMULATION SOFTWARE FOR TEACHING CAMERA CALIBRATION

This paper describes the Metrovisionlab computer application implemented as a toolbox for the Matlab program. It is designed for learning the key aspects of camera calibration techniques in dimensional metrology applications such as laser triangulation sensors and photogrammetry or stereovision systems. The software is used in several industrial vision courses for senior undergraduate mechanical engineering students. The application:
1) simulates a virtual camera, providing a simple and visual understanding of how the various characteristics of a camera influence the image that it captures;
2) generates the coordinates of synthetic calibration points, both in the world reference system and the image reference system, commonly used in camera calibration; and
3) can calibrate with the most important and widely-used methods in the area of vision cameras, using coplanar (2D) or non-coplanar (3D) calibration points. Thus, the main goal is to have a simulation tool that allows characterizing the accuracy, repeatability, error mechanisms and influences for different measurement conditions and camera calibration algorithms.

Francesco Bonavolontà, Massimo D'Apuzzo, Annalisa Liccardo, Gianfranco Miele
A Compressed Sampling-Based Method Compliant with IEC 61000-4-30 for Harmonic and Interharmonic Measurements

The paper deals with the problem of measuring harmonic and interharmonic pollution in electrical power delivery systems. The attention is specifically focused on the possibility of exploiting the compressed sampling in order to implement cost-effective nodes for distributed acquisition of the voltage signals. Differently from the traditional distributed measurement systems, the proposed approach should allow a dramatic cost reduction of the monitoring network. According to the compressed sampling protocol, the operations of distributed nodes will, in fact, be limited to random digitization and transmission of few samples for each voltage line; no high performance architectures should, thus, be necessary, with a consequent money saving. Assessing the compliance of the achieved measurements with the current standards turns out to be mandatory, thus verifying the absence of artifacts introduced by the adopted compressed sampling approach. Results obtained in numerical and experimental tests have highlight the promising performance of the proposed approach, thus suggesting its implementation in an actual measurement instrument.

Page 10 of 748 Results 91 - 100 of 7479