| 1. |
- Betta, Giovanni, et al.
(författare)
-
Metrological characterization of 3D biometric face recognition systems in actual operating conditions
- 2017
-
Ingår i: Acta IMEKO. - : IMEKO International Measurement Confederation. - 2221-870X .- 2221-870X. ; 6:1, s. 33-42
-
Tidskriftsartikel (refereegranskat)abstract
- Nowadays, face recognition systems are going to widespread in many fields of application, from automatic user login for financial activities and access to restricted areas, to surveillance for improving security in airports and railway stations, to cite a few.In such scenarios, the architectures based on stereo vision and 3D reconstruction of the face are going to assume a predominant role because they can generally assure a better reliability than solutions based on a single camera (which make use of a single image instead of a couple of images). To realize such systems, different architectures can be considered by varying the positioning of the pair of cameras with respect to the face of the subject to be identified, as well as both kind and resolution of camera considered. These parameters can affect the correct decision rate of the system in classifying the input face, especially in presence of image uncertainty.In this paper, several 3D architectures differing in camera specifications and geometrical positioning of the camera pair (with respect to the input face) are realized and compared. The detection of facial features in the images is made by adopting a popular method based on the Active Appearance Model (AAM) algorithm. 3D position of facial features is then obtained by means of stereo triangulation. The performance of the realized systems has been compared in terms of sensitivity to the quantities of influence and related uncertainty, and of typical indexes for the analysis of classification systems. Main results of such comparison show that the best performance can be reached by reducing the distance between cameras and subject to be identified and by minimizing the horizontal angle between the plane containing the camera pair axis and the face to be identified.
|
|
| 2. |
- Carratù, M., et al.
(författare)
-
Smart wearable devices for human exposure vibration measurements on two-wheel vehicles
- 2020
-
Ingår i: Acta IMEKO. - : International Measurement Confederation (IMEKO). - 0237-028X .- 2221-870X. ; 9:4, s. 121-127
-
Tidskriftsartikel (refereegranskat)abstract
- The comfort experienced while driving a motorcycle is becoming a subject of great importance; indeed, the driver is exposed to vibrations that are typically caused by irregular profiles or wear of the road surface as well as by the aerodynamic influence and high-frequency rotation of the motorcycle engine. This paper discloses an original solution that allows the driver to monitor their exposure to vibration during a ride using a low-cost wearable device (smartwatch). A suitable measurement system has been designed and tested using a real motorcycle. The system captures acceleration signals in real time through Bluetooth communication and interfaces with a wearable device with a microcontroller unit that calculates vibrations transmitted through the driver's hands. Different indexes proposed in the literature are adopted for the comfort analysis in both time and frequency domains. The hand transmitted vibrations are also experimentally compared with those measured through a fixed accelerometer according to the prescription included in the standard ISO 5349 to show the feasibility of the proposed approach in typical application conditions. © 2020 International Measurement Confederation (IMEKO). All rights reserved.
|
|
| 3. |
|
|
| 4. |
- Forssén, Clayton, et al.
(författare)
-
A transportable refractometer for assessment of pressure in the kPa range with ppm level precision
- 2020
-
Ingår i: Acta IMEKO. - : International Measurement Confederation (IMEKO). - 0237-028X .- 2221-870X. ; 9:5, s. 287-292
-
Tidskriftsartikel (refereegranskat)abstract
- A transportable refractometer for assessment of kPa pressures with ppm level precision is presented. It is based on the GAs MOdulation Refractometry (GAMOR) methodology, making it resistant to fluctuations and drifts. At the National Metrology Institute at RISE, Sweden, the system assessed pressures in the 4.3 - 8.7 kPa range with sub-ppm precision (0.5 - 0.9 ppm). The system was thereafter disassembled, packed, and transported 1040 km to Umeå University, where it, after unpacking and reassembling, demonstrated a similar precision (0.8 - 2.1 ppm). This shows that the system can be disassembled, packed, transported, unpacked, and reassembled with virtually unchanged performance.
|
|
| 5. |
- Melin, Jeanette, et al.
(författare)
-
Entropy-based explanations of serial position and learning effects in ordinal responses to word list tests
- 2023
-
Ingår i: Acta IMEKO. - 2221-870X. ; 12:3
-
Tidskriftsartikel (refereegranskat)abstract
- Measuring a person’s cognitive abilities, such as memory and learning, is central in many medical conditions to reliably diagnose, treat and monitor disease progression. Common tests typically include tasks of recalling sequences of blocks, digits or words. Recalling a word list is affected by so-called serial position effects (SPE), meaning that words at the beginning or end of the list are more likely to be recalled. In our earlier work, as part of including ordinal and nominal properties in metrology, compensation for ordinality in the raw test scores has been performed with psychometric Rasch measurement theory. Thereafter, SPE have been successfully explained with construct specification equations (CSE) dominated by information theoretical entropy as candidate reference measurement procedures. Here, we present how previous German results for explaining memory difficulty in the immediate recalling (IR, trial 1) task of the Rey’s Auditory Verbal Learning Test (RAVLT) can be replicated with a Swedish cohort (the Gothenburg Mild Cognitive Impairment study, n = 251). This CSE replicability for RAVLT demonstrates comparability across the two cohorts in a kind of inter-laboratory study. Moreover, RAVLT includes repeated trials and learning through practice is expected. How memory task difficulty changes over the eight trials in RAVLT is studied: SPE are not so prominent for the delayed recalling sequences and there is an overall reduction in the task difficulty CSE intercept with trial number, interpreted as an effect of learning. To conclude, the methodology and evidence provided here can be clinically used not only to measure a person’s memory ability but also his or her learning ability, as well as understanding the relationship between learning ability and other cognitive domains.
|
|
| 6. |
- Seneviratne, D., et al.
(författare)
-
Smart maintenance and inspection of linear assets : An Industry 4.0 approach
- 2018
-
Ingår i: Acta IMEKO. - : International Measurement Confederation (IMEKO). - 0237-028X .- 2221-870X. ; 7:1, s. 50-56
-
Tidskriftsartikel (refereegranskat)abstract
- Linear assets have linear properties, for instance, similar underlying geometry and characteristics, over a distance. They show specific patterns of continuous inherent deteriorations and failures. Therefore, remedial inspection and maintenance actions will be similar along the length of a linear asset, but because as the asset is distributed over a large area, the execution costs are greater. Autonomous robots, for instance, unmanned aerial vehicles, pipe inspection gauges, and remotely operated vehicles, are used in different industrial settings in an ad-hoc manner for inspection and maintenance. Autonomous robots can be programmed for repetitive and specific tasks; this is useful for the inspection and maintenance of linear assets. This paper reviews the challenges of maintaining the linear assets, focusing on inspections. It also provides a conceptual framework for the use of autonomous inspection and maintenance practices for linear assets to reduce maintenance costs, human involvement, etc., whilst improving the availability of linear assets by effective use of autonomous robots and data from different sources.
|
|
| 7. |
- Silander, Isak, 1980-, et al.
(författare)
-
An invar-based fabry-perot cavity refractometer with a gallium fixed-point cell for assessment of pressure
- 2020
-
Ingår i: Acta IMEKO. - : International Measurement Confederation (IMEKO). - 0237-028X .- 2221-870X. ; 9:5, s. 293-298
-
Tidskriftsartikel (refereegranskat)abstract
- An Invar-based Fabry-Perot cavity refractometer equipped with an automated, miniaturized gallium fixed-point cell for assessment of pressure is presented. The use of an Invar cavity spacer has previously demonstrated pressure assessments with sub-0.1 ppm precision. The fixed-point cell, whose design and implementation are presented here, provides a reference for temperature assessment of the gas inside the cavity with an uncertainty of 4 ppm. This opens up for a self-contained system for realization of the Pascal with an accuracy in the low ppm range. This is an important step towards disseminating the Pascal through fundamental principles.
|
|
| 8. |
- Silander, Isak, et al.
(författare)
-
AN INVAR-BASED FABRY-PEROT CAVITY REFRACTOMETER WITH AGALLIUM FIXED-POINT CELL FOR ASSESSMENT OF PRESSURE
- 2020
-
Ingår i: Acta IMEKO. - : IMEKO International Measurement Confederation. - 2221-870X. ; :5, s. 293-298
-
Tidskriftsartikel (refereegranskat)abstract
- An Invar-based Fabry-Perot cavity refractometer equipped with an automated, miniaturized galliumfixed-point cell for assessment of pressure is presented. The use of an Invar cavity spacer has previously demonstrated pressure assessments with sub-0.1 ppm precision. The fixed-point cell, whose design and implementation are presented here, provides a reference for temperature assessment of the gas inside the cavity with an uncertainty of 4 ppm. This opens up for a self-contained system for realization of the Pascal with an accuracy in the low ppm range. This is an important step towards disseminating the Pascal through fundamental principles.
|
|
| 9. |
- Zakrisson, Johan, et al.
(författare)
-
Simulation of pressure-induced cavity deformation : the 18SIB04 Quantumpascal EMPIR project
- 2020
-
Ingår i: Acta IMEKO. - 0237-028X .- 2221-870X. ; 9:5, s. 281-286
-
Tidskriftsartikel (refereegranskat)abstract
- The 18SIB04 QuantumPascal EMPIR project aims for development of photon-based standards that can replace primary standards of the SI unit of pressure, the Pascal. In this project, four partners simulated the pressure-induced deformation of a given Fabry-Pérot cavity, using various versions of two types of software, COMSOL Multiphysics® and ANSYS Workbench. It was demonstrated that, for a given geometry and set of material parameters, simulations of the deformation could be performed by the various partners with such small discrepancies that methodological mistakes of the simulation procedures will solely contribute to a sub-ppm uncertainty in the assessments of refractivity of N2.
|
|
| 10. |
- Zelan, Martin, et al.
(författare)
-
Recent advances in Fabry-Péro-based refractometry utilizing gas modulation for assessment of pressure
- 2020
-
Ingår i: Acta IMEKO. - : International Measurement Confederation (IMEKO). - 0237-028X .- 2221-870X. ; 9:5, s. 299-304
-
Tidskriftsartikel (refereegranskat)abstract
- Gas modulation refractometry (GAMOR) is a methodology that can mitigate the influence of fluctuations and drifts in Fabry-Pérot cavity–based refractometry. This paper presents a thorough description of its principles, what it enables, and its applicability. An overview of the latest results is presented, including the realization of a system based upon a cavity spacer made of Invar that allows for detection of N2 with sub-ppm precision, and a characterization procedure that allows for assessment of N2 with an accuracy at low-ppm levels.
|
|
| 11. |
- Zelan, Martin, et al.
(författare)
-
RECENT ADVANCES IN FABRY-PEROT-BASED REFRACTOMETRYUTILIZING GAS MODULATION FOR ASSESSMENT OF PRESSURE
- 2020
-
Ingår i: Acta IMEKO. - : IMEKO International Measurement Confederation. - 2221-870X. ; 9:5, s. 299-304
-
Tidskriftsartikel (refereegranskat)abstract
- Gas modulation refractometry (GAMOR) is a methodology that can mitigate the influence off luctuations and drifts in Fabry-Pérot cavity–based refractometry. This paper presents a thorough description of its principles, what it enables, and its applicability. An overview of the latest results is presented, including the realization of a system based upon a cavity spacer made of Invar that allows for detection of N2 with sub-ppm precision, and a characterization procedure that allows for assessment of N2 with an accuracy at low-ppm levels.
|
|
