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Keywords: virtual reality, mixed reality, technology, basic life support, cardiovascular pulmonary resuscitation, near-peer mentoring, education, high school students
Published in DKUM: 07.10.2025; Views: 0; Downloads: 3
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Abstract: Due to the widespread importance of clonality in plants, investigating the mechanisms by which clonality-related traits are associated with community organization is crucial for a functional understanding of vegetation. In this study, the patterns in clonality and other life-history traits in a series of species-rich semi-dry grasslands (alliance Bromion erecti, order Brometalia erecti, class Festuco-Brometea) in the central-European region of Slovenia, all assigned to the same EUNIS (Middle European Bromus erectus semi-dry grasslands, code R1A32) and Natura 2000 habitat type [Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia), code 6210 (important orchid sites)] were studied. The aims of this research were (i) to assess the diversity of clonal growth organs (CGOs) and other clonal traits in semi-dry grasslands and (ii) determine differences in distribution of clonal growth organs and other clonal traits in three plant communities (associations). Data from 224 vegetation plots (phytosociological relevés) with 247 species and nine plant traits of grassland species were used. This revealed that more than half of the plant species were clonal. Most common clonal growth organs (CGOs) were perennial splitting main root (produced by non-clonal plants), epigeogenous rhizomes and hypogeogenous rhizomes. For each plot, the community weighted mean (CWM) of all plant traits was calculated to determine differences between the three grassland types. Soil moisture and productivity seem to be the key factors associated with differences in clonal growth in the associations studied. Clonal tussock plants with rhizomes, and species with a rich bud bank and a high number of clonal offspring were abundant in grasslands with deep soils and mesic conditions (Onobrychido-Brometum association). Grasslands on stony soils over fissured limestone or dolomite and with more xeric conditions were characterized by rosette clonal plants with hypogeogenous rhizomes (Bromo-Danthonietum calycinae) and/or non-clonal plants with splitting main root (Scabioso hladnikianae-Caricetum humilis). The diversity and characteristics of clonality-related traits indicate that clonal growth is an essential feature of these species-rich grasslands. Importantly, the results of this study indicate that in order to support the characteristic species and functional composition of all types of grassland, management plans for semi-dry grassland habitats in the area studied need to be carried out at a finer scale (e.g. at the level of associations) than the level of EUNIS and Natura 2000 habitat types.
Keywords: community assembly, community weighted mean, Festuco Brometea, functional traits, high nature value habitats, species coexistence
Published in DKUM: 22.09.2025; Views: 0; Downloads: 2
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Abstract: Two models have recently been proposed to describe dielectric spectroscopy measurements of ferroelectric nematics (NF) in thin planar capacitors. The polarisation-external capacitance Goldstone reorientation mode (PCG model) considers the NF layer between the electrodes as an effective low resistivity material; the resistivity is inversely proportional to the square of polarisation magnitude. The ‘high-ε’ model considers the NF material as having a huge permittivity due to the ease of polarisation rotation. We study implications of both models and show, why both models describe the majority of the observed dielectric spectroscopy results equally well. We point out differences among the models’ predictions and explain why some observations can be explained only by the high-� model. The high-� model predicts that the frequency range within which capacitors filled with NF material effectively store energy can be increased by using thicker cells, while within the PCG model this frequency range reduces with increasing capacitor thickness. Within both models, a crucial parameter that determines the behaviour of the capacitors filled with an NF material is parasitic resistance, primarily due to the electrode resistance. We present measurements of electrode resistance and find that in ITO cells it is of the order of few hundred ohms.
Keywords: ferroelectric nematics, dielectric measurements, high-permittivity model, electrode resistance
Published in DKUM: 14.08.2025; Views: 0; Downloads: 2
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Abstract: This study demonstrates the potential of supercritical CO₂ curing to enhance the performance and sustainability of lignite-based fly ash geopolymer mortar offering a promising approach to reducing CO₂ emissions in the construction industry while improving material properties. The research comprehensively compared conventional curing (GEO-REF) with supercritical CO₂ curing (GEO-CO₂), revealing that GEO-CO₂ samples exhibited higher compressive and flexural strengths, achieving peak performance almost immediately after curing. Supercritical CO₂ exposure resulted in enhanced carbonation, with a depth of up to 7.6 mm and a carbonation rate of up to 67 %. XRD confirmed phase changes due to CO₂ curing, with GEO-CO₂ showing additional calcium carbonate-calcite, calcium carbonate-aragonite, and calcium silicate hydroxide compared to GEO-REF. Nitrogen adsorption/desorption studies indicated larger pore diameters but a reduced BET surface area in GEO-CO₂ samples, suggesting structural changes due to CO₂ exposure. TGA analysis revealed that supercritical CO₂ curing reduced water retention and enhanced carbonation, resulting in increased CaCO₃ content and changes in Ca(OH)₂ levels.
Keywords: geopolymer, fly ash, carbonation, CO2 fixation, supercritical CO2, high pressure reactor
Published in DKUM: 25.07.2025; Views: 0; Downloads: 3
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Abstract: Ground fault relays (GFRs) in resonant-grounded medium voltage distribution networks shall not operate during phase-to-ground (Ph-G) fault inception, allowing the Petersen coil to suppress self-extinguishing faults, but the designated GFR must operate during permanent faults. In order to enhance the performance of GFRs, particularly during high-impedance faults, the scope of this paper is to propose a straightforward, machine-learning-based protection framework. The enhanced GFR is modeled as a classification task. Depending on the GFR’s position and the Ph-G fault location in the network, fault samples are labeled as “no operation,” “primary,” “backup,” or “backup of backup,” forming two-class, three-class, and four-class GFR setups, respectively. This assures selective operation across three protection zones and improves the reliability of all GFRs. The proposed protection scheme employs backward optimal feature selection to identify the most relevant discrete features obtained from measured zero-sequence current and voltage waveforms. An ensemble of k-nearest neighbor classifiers is utilized for accurate classification, simulating the GFR operating conditions, with measurement errors and sensitivity incorporated in the preprocessing. A 20 kV case study network validates the proposed framework, achieving F1-scores exceeding 96 %. The maximum operation delay of the protection scheme for an enhanced GFR is 225 ms, accommodating the required time window (200 ms), prediction time (5 ms), and change detection time (20 ms), thus assuring safe operation. Compared to other machine-learning-based methods used for Ph-G fault protection in resonant-grounded radial networks, this framework is high-performing, fast, and easy to implement, utilizing a simpler structure than neural networks.
Keywords: resonant grounded networks, ground-fault relay, high-impedance faults, ensemble-based learning, optimal feature selection
Published in DKUM: 25.07.2025; Views: 0; Downloads: 4
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