A metrological approach for multispectral photogrammetry

<p>This paper presents the design and development of a three-dimensional reference object for the metrological quality assessment of photogrammetry-based techniques, for application in the cultural heritage field. The reference object was 3D printed, with nominal manufacturing uncertainty of the order of 0.01 mm. The object was realized as a dodecahedron, and in each face, a different pictorial preparation was inserted. The preparations include several pigments, binders, and varnishes, to be representative of the materials and techniques used historically by artists.</p><p>Since the reference object’s shape, size and uncertainty are known, it is possible to use this object as a reference to evaluate the quality of a 3D model from the metric point of view. In particular, verification of dimensional precision and accuracy are performed using the standard deviation on measurements acquired on the reference object and the final 3D model. In addition, the object can be used as a reference for UV-induced Visible Luminescence (UVL) acquisition, being the materials employed UV-fluorescent. Results obtained with visible-reflected and UVL images are presented and discussed.</p>

Evaluation of domestic water measurement error: a case study

This study presents a method to determine the operation of the measuring equipment by analyzing the metrological quality and degradation of accuracy, depending on the accumulated volume and the installation time. Different types of meters at three flow rates were tested to assess the evolution of the relative error and to determine the average error curves and rate of deterioration. The volume of apparent losses caused by the inaccuracies of the meters was also calculated. The results of the investigation establish the sub-accounting errors and the annual degradation rate were −15 and −1.88%, respectively for consumption flows below 30 L/h represented by 23% of the subscribers. For flow rates of 120 L/h, the system accounts for a 68% consumption of subscribers and an error of −1.8% and a degradation of −0.14% were recorded. Finally, for consumption flows of 1,500 L/h, the system has accounted for 9% consumption of the subscribers; over-accounting values were obtained generating an average error of 16% and a degradation of 1.68%. It is concluded that the hydrometric district has a sub-accounting error equal to −3.24%, which results in a volume of apparent losses of 1.21 m3/connection/month.

Validation study: evaluation of the metrological quality of French hospital data for perinatal algorithms

ObjectiveThe aim of our validation study was to assess the metrological quality of hospital data for perinatal algorithms on a national level.DesignValidation study.SettingThis was a multicentre study of the French medicoadministrative database on perinatal indicators.ParticipantsIn each hospital, we selected 150 discharge abstracts for delivery (after 22 weeks of gestation), in 2014, and their corresponding medical records. Overall, 22 hospitals were included.InterventionsA single investigator performed blind data collection from medical records in order to compare data from discharge abstracts with data from medical records. Finally, 3246 discharge abstracts were studied.Primary and secondary outcome measuresSeventy items, including maternal and delivery characteristics and maternal morbidity, were collected for each delivery stay.ResultsThe concordance rate of maternal age at delivery was 94.8% (95% CI 93.8 to 95.4). Combining the two forms of pre-existing diabetes, the algorithm presented a PPV of 65.9% and a sensitivity of 75.7%. The concordance rate of gestational age at delivery was 91.8% (90.9 to 92.7). Regarding gestational diabetes, the PPV was 80.8% (79.4 to 82.2) and the sensitivity was 79.5% (78.1 to 80.9). Regardless of the algorithm explored, the PPV for vaginal delivery was over 99%. For the diagnosis codes corresponding to immediate postpartum haemorrhage, the PPV was 77.7% (76.3 to 79.1) and the sensitivity was 75.5% (74.0 to 77.0). The algorithm for stillbirth presented a PPV of 89.4% (88.3 to 90.5) and a sensitivity of 95.4% (94.7 to 96.1).ConclusionsThis first national validation study of many perinatal algorithms suggests that the French national hospital database is an appropriate data source for epidemiological studies, except for some indicators which presented low PPV and/or sensitivity.

Optical metrology applied in CCTV inspection in drain and sewer systems

<p class="Abstract">This paper addresses the metrological quality of dimensional measurements based on images obtained from CCTV inspections in drain and sewer systems. In this type of indirect visual inspection, a significant number of absolute and relative dimensional quantities can be quantified, contributing to the characterization of the observations and, consequently, to the analysis of performance of drain and sewer systems outside buildings. Unfavorable environmental factors and conditions within the drain or sewer components affect estimation of the quantities of interest and the quality of the recorded images (lighting, lack of reference points, geometric irregularities and subjective assessments, among others). Quantification improvement of the dimensional quantities is a key objective to achieve a better assessment of components condition from these inspections. This study contributes to improve the quality of the dimensional measurements by defining experimental procedures, applicable to the optical systems used in CCTV inspection. The paper describes the European normative framework for these inspection activities and proposes approaches aiming at increasing confidence in the dimensional measurements based on the metrological characterization of the optical systems used, as well as, to establish a traceability chain. Results presented and discussed include the evaluation of measurement uncertainty.</p>

Optical characterisation of three reference Dobsons in the ATMOZ Project – verification of G. M. B. Dobson's original specifications

Three reference Dobsons (regional standard Dobsons No. 064, Germany and No. 074, Czech Republic as well as the world standard No. 083, USA) were optically characterized at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig in 2015 and at the Czech Metrology Institute (CMI) in Prague in 2016 within the EMRP ENV 059 project “Traceability for atmospheric total column ozone”. Slit functions and the related parameters of the instruments were measured and compared with G. M. B. Dobson's specifications in his handbook. All Dobsons show a predominantly good match of the slit functions and the peak (centroid) wavelengths with deviations between −0.11 and +0.12 nm and differences of the full width half maximum (FWHM) between 0.13 and 0.37 nm compared to the nominal values at the shorter wavelengths. Slightly larger deviations of the FWHMs from the nominal Dobson data, up to 1.22 nm, can be seen at the longer wavelengths, especially for the slit function of the long D-wavelength. However, differences between the effective absorption coefficients (EACs) for ozone derived using Dobson's nominal values of the optical parameters on one hand and these measured values on the other hand are not too large in the case of both “old” Bass–Paur (BP) and “new” IUP-ozone (Institut für Umweltphysik, University of Bremen) absorption cross sections. Their inclusion in the calculation of the total ozone column (TOC) leads to improvements of significantly less than ±1 % at the AD-wavelengths between −1 and −2 % at the CD-wavelengths pairs in the BP-scale. The effect on the TOC in the IUP-scale is somewhat larger at the AD-wavelengths, up to +1 % (D074), and smaller at the CD-wavelengths pair, from −0.44 to −1.5 %. Beside this positive effect gained from the data with higher metrological quality that is needed for trend analyses and satellite validation, it will be also possible to explain uncommon behaviours of field Dobsons during calibration services, especially when a newly developed transportable device TuPS (tuneable portable radiation source) from CMI proves its capability to provide similar results as the stationary setups in the laboratories of National Metrology Institutes. Then, the field Dobsons can be optically characterized as well during regular calibration campaigns. A corresponding publication will be prepared using the results of TuPS-based measurements of more than 10 Dobsons in field campaigns in 2017.

Lessons Efficiency Paradox: The Unexpected Empirical Findings about the Amount of Homework and the Teacher’s Strictness

In the article a newly created questionnaire intended for older schoolchildren – “evaluate the teacher and his lessons” is introduced. The theoretical and practical context of the instrument based on 87 primary questions is named, the dimensional structure and metrological quality of the formed integrated scales and sub-scales is presented. The scales and sub-scales were formed following the classical test theory, combining logical and factorial validation. The secondary sub-scale factorization has indicated that it is expedient to distinguish between two integrated lesson dimensions (scales). The first integrated scale reflects the quality of social relations and teacher-centered orientation. The second scale reflects the management and didactics of the educational process. High correlation between the evaluations of integrated scales (r = 0.86) indicates that a generalized integrated index of evaluation of the teacher and his lesson can be derived by aggregating even 81 primary variables defining the most various aspects of the lesson. In the article the basis of statistic norming of the questionnaire possessed at present is described: Nschool children = 4024 and Nteachers = 200 which encompasses schools of different types from various regions of the country. The wide coverage of the content of created questionnaire, quite good quality of the scales opens good opportunities for its application in both the practice of schools evaluation and research. First of all, the methodical purpose of the article has been to introduce a new standardized instrument of survey. Secondly, the question why such indicators as “abundance of homework” and “level of the requirements set by the teacher” practically do not correlate with all the remaining scales, although the latter intercorrelate very significantly, is set. In the paper the question (and hypotheses) whether the mentioned variables can truly affect the didactic quality of the lesson counterproductively is elaborated.

On the Validation of Models of Large Complex Electrical Systems

The broad topic of verification and validation (V&V) of simulation model is considered, narrowing the scope to electric network models, using briefly electric traction systems as the working example. Definitions, properties and requirements of the validation process, of the model characteristics and of simulation test methods are considered: the focus is on the background and the methods to address the general problem of model validation with emphasis on the use of experimental measured data and how to characterize them to assess the required metrological quality. Depending on the method approached for model validation, the metrological quality may take the form of uncertainty, consistency and credibility. Bibliography is selected as the most representative for the respective topics of the vast V&V subject and is believed to represent a comprehensive, yet synthetic, reference. This work is intended as a general basis for a more detailed and specific analysis of V&V techniques applied to electric simulation and models.