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Abstract: To date, no piezoelectric material system has been developed that would match the piezoelectric performance of the group of lead-based relaxor ferroelectrics, such as Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT). In the quest to f ind alternatives, continuous efforts have been made to understand the complex microscopic origins leading to the large macroscopic piezoelectric response of PMN–PT and similar lead-based perovskites with relaxor characteristics. Despite significant advances, it is still unclear whether those concepts can be efficiently used to develop lead-free relaxor ferroelectric alternatives. Here, a large piezoelectric response of BiFeO3–BaTiO3 (BFO–BTO) ceramics is reported, characterized by a d33 coefficient of 1200 pmV−1 measured at 325 °C, 1 kV cm−1 of driving field and 90 Hz of field frequency. While composed of multiple contributions, the large response is found to be dominated by a strongly nonlinear and hysteretic process, likely associated with the dynamics of hierarchically arranged nanodomain walls, thus resembling the mechanisms operating in lead-based relaxor materials. Although the response is triggered upon elevated thermal energy, the results provide valuable information about the microscopic behavior that can be potentially used to tailor the response of lead-free relaxor ferroelectrics and bring them closer to the highly performant lead-based perovskites
Published in DiRROS: 13.06.2025; Views: 441; Downloads: 149
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Abstract: One way to demonstrate the research focus and progress in a scientific field is through scientific publishing. Scientific articles are a starting point for analyzing the main topics, concerns, and author networks within a specific domain. This way, we can track the development of the discipline. Through publications, researchers create narratives that reveal the direction and development of specific disciplines. These narratives help form scientific paradigms. The main goal of this article is to detect and discuss the development of predominant scientific topics in particular period of Slovenian sociological science. The analysis starts with the emergence of the transition process from non-democratic Yugoslavia towards the independent Republic of Slovenia and onwards to contemporary times. We analyzed 774 scientific articles published between 1984 and 2022 in the journal Social Science Forum, which had an impact factor of 0.175 in 2022. The findings indicate that Slovenian sociologists’ research interests reflect historical transformations – from the transition to independence to EU accession. We use ontology-based analysis with OntoGen to track these thematic shifts systematically. This positions our work as a localized application of established text-mining approaches. The method applied allows us to uncover patterns of knowledge production tied to key sociopolitical moments in Slovenian history.
Keywords: Slovenian sociology, bibliographical data, OntoGen, concept, ontology creation
Published in DiRROS: 13.06.2025; Views: 477; Downloads: 274
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Abstract: Overcooling and/or pressurization events have the potential to result in pressurized thermal shock (PTS) in reactor pressure vessels of pressurized water reactors (PWRs). PTS can occur during various overcooling scenarios, including loss-of-coolant accidents (LOCAs). Thermal-hydraulic calculations of overcooling scenarios provide an input to structural analysis. The purpose of this study is to perform advanced thermal-hydraulic calculations of a hot-leg LOCA with uncertainty and sensitivity analyses. A novel approach, utilizing a fast Fourier transform–based method (FFTBM) with signal mirroring (SM), is proposed for a sensitivity study to evaluate the influence of input uncertain parameters with low computational cost before performing an uncertainty analysis. For the analysis, a break size of 45.6 cm2 (equivalent to a 76.2-mm- or 3-in.-equivalent diameter) was selected in a two-loop PWR. A verified and validated RELAP5 input deck was used. In sensitivity study 30, one-at-a-time sensitivity calculations plus reference calculation were performed. These were followed by uncertainty and sensitivity analyses using the GRS (Gesellschaft für Anlagen- und Reaktorsicherheit) Software for Uncertainty and Sensitivity Analyses (SUSA) version 4.2.6 tool, varying 15 uncertain input parameters across 208 samples. The input uncertain parameters were derived from the European Union–funded Advanced PTS Analysis for LTO (APAL) project. Three figures of merit (FOMs), reactor pressure, liquid temperature, and reactor vessel wall temperature below the cold leg connection, were analyzed. The results demonstrated that FFTBM-SM effectively identified the four most influential parameters, aligning closely with the results from the global sensitivity analysis from SUSA, which utilized 208 samples from the uncertainty analysis. Although slight differences in parameter ranking were observed, the findings validate FFTBM-SM as a valuable prescreening tool for sensitivity studies. The limitation of the sensitivity study is that it adopts a local approach. Finally, the results of the uncertainty analysis provide tolerance regions for the selected FOMs that are comparable to those obtained in the original APAL study for a four-loop PWR.
Keywords: uncertainty analysis, sensitivity analysis, FFTBM-SM, advancedthermal-hydraulic calculations of a hot-leg LOCA
Published in DiRROS: 11.06.2025; Views: 500; Downloads: 285
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Keywords: Saccharomyces yeasts, Non-Saccharomyces yeasts, Wine, Yeast counting, Plate count method
Published in DiRROS: 11.06.2025; Views: 472; Downloads: 127
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Abstract: MAVOMcoat MC1300 (Zr-Cr-based coating) and MC1700 (Zr-based coating) on chemically pre-treated aluminium alloy 3003. Conversion times varied from 80 s to 45 min. After deposition, the samples were subjected to three post-treatments: air drying for 15 min, air drying for 24 h, and immersion in 3.5 wt% NaCl solution for 24 h. Corrosion resistance was evaluated using electrochemical measurements, whereas scanning electron microscopy with energy dispersive spectroscopy and X-ray photoelec tron spectroscopy were employed for surface analysis. Based on the evaluation of corrosion parameters, the optimal conversion times for MC1700 and MC1300 were determined to be 10 min and 7 min, respectively. The conversion coatings MC1700 and MC1300 were characterised by distinct elemental compositions, with the former predominantly comprising Zr, O, Al and F, and the latter Zr, O, Al, Cr and F. Notably, the thickness of coatings was between 10 and 170 nm, depending on the type of coating and location (matrix or intermetallic particles). The 24-hour immersion of MC1700 ZrCC in 3.5 wt% NaCl led to progressive build-up of Zr oxide and release of fluoride from the coating.
Published in DiRROS: 10.06.2025; Views: 555; Downloads: 186
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