Related Experiment Video
Updated: Nov 1, 2025

Automatic Laser-based Geometry Capture for Finite Element Analysis of Weld Beads
Published on: July 25, 2025
Contributions of precision engineering to the revision of the SI
Harald Bosse1, Horst Kunzmann1, Jon R Pratt2
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany.
Abstract:
All measurements performed in science and industry are based on the International System of Units, the SI. It has been proposed to revise the SI following an approach which was implemented for the redefinition of the unit of length, the metre, namely to define the SI units by fixing the numerical values of so-called defining constants, including c, h, e, k and N A. We will discuss the reasoning behind the revision, which will likely be put into force in 2018. Precision engineering was crucial to achieve the required small measurement uncertainties and agreement of measurement results for the defining constants.
Related Concept Videos
SI Units: 2019 Redefinition
A standard set of units has been defined...
Units of Measurement
There are various well-known historical measurement systems, such as the Babylonian system, the Roman system, the Egyptian system, the Olympian system, the British system, and the Indus...
Distance Corrections
Accuracy and Precision
Rules for Significant Figures
It should be emphasized that when we represent measured values, the...
Accuracy, limits, and approximation
Accuracy is defined as the closeness of the measured value to the true or actual value. In engineering mechanics, repeated measurements are taken during theoretical or experimental analyses to ensure that the result is precise and accurate.
The accuracy of any solution is based on the...

