Metrology, Volume 2, Issue 3 (September 2022) – 4 articles

Understanding the length and subdivisions of ancient length units is necessary for Archaeology, Architecture, and engineering, among other fields. These metrological units derive from anthropocentric concepts (fathom, cubit, foot, finger, etc.) and hence their metrological characteristics are variable and unknown for various ancient civilizations. The Roman length units are well determined, but the ancient Greek units are not. A rule sculpted in a metrological relief recently permitted the recognition of the Doric foot as having a length of 327 mm, but the broader use and divisions of this length unit remain unknown. In this article we present evidence of use of the Doric foot from the modeling of an ancient, atypical small theatre of the 4th–3rd century B.C., at Makyneia, on the western Greece mainland. It was found that this structure was designed using the Doric foot and its division in 24 (or even 12) digits. This result from a small provincial town indicates that the Doric foot was in broad use in architectural and engineering works of the ancient Greek World, and this result may be used to solve various problems of that era. Full article

Arterial simulators are a useful tool to simulate the cardiovascular system in many different fields of application and to carry out in vitro tests that would constitute a danger when performed in in vivo conditions. In the literature, a thriving series of in vitro experimental set-up examples can be found. Nevertheless, in the current scientific panorama on this topic, it seems that organic research from a metrological and functional perspective is still lacking. In this regard, the present review study aims to make a contribution by analyzing and classifying the main concerns for the cardiovascular simulators proposed in the literature from a metrological and functional point of view, according to their field of application, as well as for the transducers in the arterial experimental set-ups, measuring the main hemodynamic quantities in order to study their trends in specific testing conditions and to estimate some parameters or indicators of interest for the scientific community. Full article

Ultrasonic clamp-on meters have become an established technology for non-invasive flow measurements. Under disturbed flow conditions, their measurement values must be adjusted with corresponding fluid mechanical calibration factors. Due to the variety of flow disturbances and installation positions, the experimental determination of these factors often needs to be complemented by computational fluid dynamics (CFD) simulations. From a metrological perspective, substituting experiments with simulation results raises the question of how confidence in a so-called virtual measurement can be ensured. While there are well-established methods to estimate errors in CFD predictions in general, strategies to meet metrological requirements for CFD-based virtual meters have yet to be developed. In this paper, a framework for assessing the overall uncertainty of a virtual flow meter is proposed. In analogy to the evaluation of measurement uncertainty, the approach is based on the utilization of an expanded simulation uncertainty representing the entirety of the computational domain. The study was conducted using the example of an ultrasonic clamp-on meter downstream of a double bend out-of-plane. Nevertheless, the proposed method applies to other flow disturbances and different types of virtual meters. The comparison between laboratory experiments and simulation results with different turbulence modeling approaches demonstrates a clear superiority of hybrid RANS-LES models over the industry standard RANS. With an expanded simulation uncertainty of 1.44 × 10⁻², the virtual measurement obtained with a hybrid model allows for a continuous determination of calibration factors applicable to the relevant mounting positions of a real meter at a satisfactory level of confidence. Full article

The increased relevance of large-volume metrology (LVM) in industrial applications entails certain challenges: measurements must be cost-efficient and the technologies must be easy to use while ensuring accuracy and reliability. Portable photogrammetry shows great potential to overcome such challenges, but industrial users do not yet rely on its accuracy for large scenarios (3 to 64 m), especially when mass-market cameras are not conceived of as industrial metrology instruments. Furthermore, the measurement results might also depend on the operator’s skills and knowledge of the key process variables. In this work, a methodology was designed so that the measurement uncertainty of portable photogrammetry can be evaluated under controlled conditions for LVM. To do so, PTB’s reference wall, which was designed to assess laser-based methods applied to large volumes, was used as a reference artefact to study the measurement performance under different conditions, enabling an analysis of the relative influence of two process variables: the spatial arrangement of the optical instruments on the scene, and the relative camera poses for an accurate triangulation. According to these variables, different measuring conditions were designed (Monte Carlo analysis), and experimentally evaluated and reported (LME, length measuring errors), analysing the performance figures expected from both unskilled and expert users. Full article