Acta IMEKO

Detection of induction motor faults by envelopes of higher current harmonics

Alexander Shestakov — 2026-08-25

Detection of broken rotor bars in induction motors based on sideband components near the fundamental stator current frequency often yields unreliable results under variable operating conditions due to masking effects and the dominant amplitude of the fundamental component. This study proposes a robust fault detection method which uses higher-order current harmonics, which demonstrate significantly reduced susceptibility to load variations and other masking phenomena. As principal contribution this study demonstrates that a convolutional neural network trained exclusively on data derived from a single operating condition achieves strong generalisation across a wide spectrum of unsteady operating regimes, spanning substantially different supply frequencies and load levels, with consistently high classification accuracy. Signal processing involves bandpass filtering around the fifth and seventh harmonic frequencies, envelope extraction via the Hilbert transform, continuous wavelet transform to generate time-frequency scalograms, and data augmentation through vertical shifts to simulate variations in defect-related frequency components under changing slip conditions. Scalograms corresponding to the fifth and seventh harmonics are treated as independent training samples, effectively expanding the dataset while leveraging physically redundant fault information. This single-point training paradigm directly addresses a critical industrial limitation, thereby enabling deployment of data-driven condition monitoring systems even under severe training data constraints.

Enhancing accelerometer calibration results by reporting interpolated calibration data

Ian Veldman — 2026-08-18

This paper describes the implementation of interpolation methods (fitting curves) for reporting complex (magnitude and phase) accelerometer calibration measurements. The authors’ evaluation focused on two interpolation methods: polynomial fit and mathematical model description of a charge accelerometer. Charge accelerometers, such as the Brüel & Kjær model 8305 and the ENDEVCO model 2270, are the de facto laboratory standard accelerometers. NMIs have been maintaining sensitivity calibration data, with the associated uncertainty of measurement (UoM), on such devices for decades and reported publicly available comparison data using these accelerometers, which provide ample vetted data for curve-fitting technique investigations.

Assessment of innovation management systems in established innovative companies: A conceptual model based on ISO 56002:2019 standard

Felippe Vicencio Gomes — 2026-08-18

This study presents a comprehensive assessment model designed to facilitate organizational excellence in innovation management through a systematic evaluation of maturity levels vis-à-vis the ISO 56002:2019 standard clauses and items. The practical applicability of the model was validated through an empirical investigation conducted at Light SESA, a prominent organization in the Brazilian electricity sector. The methodological framework encompasses six interconnected phases: (i) an extensive literature review and documentary analysis of pertinent research domains; (ii) development of an analytical framework based on ISO 56002:2019 parameters; (iii) implementation of the Analytic Network Process (ANP) for weight attribution to dimensional and factorial components within the assessment structure; (iv) design and validation of a survey instrument targeting senior leadership and RD&I project managers to evaluate organizational maturity relative to ISO 56002:2019 requirements; (v) application of fuzzy logic principles for processing collective judgments, thereby mitigating assessment bias; and (vi) utilization of Importance-Performance Analysis (IPA) methodology to identify priority areas for innovation management system enhancement. The primary contribution of this research is a robust, empirically validated model for assessing innovation management system maturity in organizations seeking to enhance their innovative capabilities and performance metrics.

Self-assessment model for pharmaceutical companies based on Good Manufacturing Practices for pharmaceuticals in Brazil: a multicriteria approach

Alexandre Souza Nunes — 2026-08-18

This study presents a novel self-assessment model for evaluating organizational compliance capabilities within Brazilian pharmaceutical companies regarding the Resolution RDC 658/2022 requirements established by the National Health Surveillance Agency (Anvisa) aligned with the World Health Organization's Good Manufacturing Practices (GMP) for pharmaceutical products. The research methodology comprised a systematic literature review and documentary analysis spanning 2010-2023, followed by the development of an analytical framework integrating the Analytic Hierarchy Process (AHP) for weighting the regulatory requirements of the aforementioned Resolution. The model's empirical validation was conducted through implementation at a Brazilian pharmaceutical company, evaluating its organizational compliance capabilities vis-à-vis the RDC 658/2022 requirements. Importance-Performance Analysis (IPA) was subsequently employed to prioritize areas that require enhanced regulatory compliance. The primary contribution of this study is a comprehensive self-assessment framework that provides pharmaceutical companies with robust decision-making support for visa certification processes. Empirical validation demonstrated the model's effectiveness in identifying critical compliance gaps and prioritizing improvement initiatives. This methodological advancement strengthens the interface between health regulatory authorities and pharmaceutical companies, potentially enhancing the effectiveness of Brazil’s regulatory system

Multicriteria conceptual framework for maturity assessment of testing and calibration laboratories based on the ISO/IEC 17025: 2017 standard

David Batista Correa — 2026-08-18

This study presents a novel multicriteria framework for assessing the maturity of testing and calibration laboratories in accordance with ISO/IEC 17025:2017 requirements. The research methodology comprised a systematic literature review spanning 2010–2023, followed by the development of an analytical framework integrating the Analytical Hierarchy Process (AHP) for weighting standard requirements and the Importance–Performance Analysis (IPA) for maturity assessment. The framework's empirical validation was conducted at the Brazilian Army Evaluation Center (CAEx) to evaluate laboratory compliance capabilities vis-à-vis the ISO/IEC 17025:2017 requirements regarding competence, impartiality, and operational consistency. The validation process involved senior laboratory managers and resulted in quantitative maturity assessments across standard requirements, enabling the identification of critical improvement areas and the development of targeted action plans for accreditation preparation. The primary contribution of this study is a comprehensive assessment framework that provides testing and calibration laboratories with robust decision-making support for accreditation processes. The empirical validation demonstrated the effectiveness of the framework in identifying critical compliance gaps and prioritizing improvement initiatives. This methodological advancement is a significant contribution to the field of laboratory quality management.

Development of an IoT-based network for urban environmental monitoring in a vulnerable area of Los Ríos, Santo Domingo, Dominican Republic

Jesús D´Alessandro — 2026-08-28

The aim of this research phase was to develop an environmental data collection tool specific for the context of Los Ríos–Santo Domingo, where vulnerable settlements coexist with other clusters of higher socioeconomic status. The design of such tool needed to address the social, legal, and climatic frameworks of its context, while also aiming at a reliable, energy efficient, and replicable architecture. The project hopes to encourage future information-based participatory planning aimed at improving safety and elevating the quality of life in the area. The workflow carried out during this phase included: area visits, document consultation, work on an urban footprint map, review of comparable projects, device development, and the strategic selection of the installation site. The project achieved the design and production of ten compact devices that contain seven sensors each, to register concentrations of important air contaminants, vibration, sound intensity, and specific atmospheric conditions. Devices were installed within the inner perimeter of a property in the proximity of vulnerable and non-vulnerable polygons to enable the observation of potential reading differences. Preliminary total averages obtained from a sample showed high concentrations of CO, NO₂ (according to guidelines from WHO), and PM₁ (following the 2024 paper “On the safe levels of micro-sized particles PM1.0 in ambient air” by Zaitseva, Kleyn, Chetverkina, Andrishunas, and Tsinker), alongside noise levels between 6.9 and 74.09 dB in most units and RH values below 40 %.

X-ray computed tomography for non-destructive evaluation of steel wire ropes: Comparison of laboratory XCT configurations for image quality and damage visualization

Daniel Kytyr — 2026-09-04

Steel wire ropes are critical structural components whose internal damage often cannot be reliably assessed using conventional non-destructive testing methods. This study evaluates the applicability of laboratory X-ray computed microtomography (XCT) for detailed inspection of steel wire ropes by comparing three complementary XCT configurations: one employing a liquid-metal anode microfocus source with a large-area flat-panel detector, a conventional sealed-type microfocus tube with CMOS detector, and a high-power X-ray source coupled with scintillating screen and a laboratory camera. Intact and damaged rope specimens together with an individual fractured steel wire were investigated under various acquisition conditions. Image quality was quantitatively assessed using the contrast-to-noise ratio (CNR) and the full width at half maximum (FWHM) of the line spread function, complemented by qualitative evaluation of reconstructed three-dimensional models. The results demonstrate the influence of X-ray source characteristics and the acquisition parameters on image quality and defect detectability. Although the high-power system provided superior penetration capability and the highest CNR, its large focal point substantially limited the achievable spatial resolution. In contrast, both microfocus configurations enabled reliable visualization of individual wires and internal damage features, with image quality strongly dependent on the number of acquired projections. The presented comparison provides practical guidance for selecting appropriate laboratory XCT configurations for non-destructive evaluation of steel wire ropes and similar highly attenuating engineering components.

Spiral X-ray computed tomography of long wooden samples: Influence of pitch and geometric calibration on reconstruction quality

Vaclav Rada — 2026-09-04

X-ray computed tomography (XCT) is widely used for three-dimensional characterization of material microstructure. In wood science, XCT increasingly serves as a tool for quantitative analysis of annual rings, porosity, and other structural features requiring high reconstruction fidelity, and geometrical consistency. Spiral XCT enables scanning of samples exceeding the detector field of view in height by combining continuous sample rotation with synchronized axial translation during acquisition. This work investigates the influence of mechanical alignment, motion synchronization, geometric calibration, and spiral pitch on the reconstruction quality of long wooden specimens.
Reconstruction fidelity depends on the agreement between the assumed spiral trajectory and the actual coupled rotational and axial motion during acquisition. Misalignment of the rotation axis with respect to the source–detector geometry, together with inaccuracies in axial translation or magnification calibration, may introduce geometric distortions, blurring, and loss of structural fidelity. The effect of spiral pitch, defined as the axial displacement per full rotation, was experimentally investigated by performing scans with different predefined pitch values. Increasing the spiral pitch reduced axial sampling density and projection overlap, resulting in progressively stronger interpolation artefacts and degradation of reconstruction quality.
The study further demonstrates the sensitivity of cone-beam spiral XCT reconstruction to accurate magnification calibration, as even small scaling errors lead to cumulative misregistration along the reconstructed volume. Reliable spiral XCT of long wooden samples therefore requires accurate geometric calibration, stable synchronization of the rotational and axial motions, and an appropriately selected spiral pitch.