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804. A contribution to the vascular and bryophyte flora of the upper Neretva and Zalomka river valleys (Bosnia and Herzegovina)Đorđije Milanović, Simona Strgulc Krajšek, Jugoslav Brujić, Valentin Heimer, Dragan Koljanin, Marija Kravanja, Ivana Rešetnik, Vladimir Stupar, Peter Schönswetter, Božo Frajman, 2025, izvirni znanstveni članek Povzetek: etween 1st and 6th June 2023, we conducted floristic research on sev-eral sites in the upper Neretva River valley and along Zalomka River at Nevesinjsko Polje. We recorded 933 taxa in total; 897 plant taxa including 125 bryophytes were found at 51 localities in the upper Neretva River val-ley, and 200 plant taxa, including 32 bryophytes, were found at 11 sites in the Zalomka River valley. Among the registered taxa, 39 taxa are endemic to the Balkan Peninsula, 56 are listed in the List of endangered and rare taxa of Bosnia and Herzegovina, 27 are on the Red List of the Federation of Bosnia and Herzegovina, and 95 taxa are protected in the Republic of Srpska. We also registered several species new to the flora of Bosnia and Herzegovina. Among Angiosperms these were Barbarea intermedia, Lamium hybridum, Myosotis sicula and Poa ursina, and among bryophytes Fissidens gracilifolius, Grimmia dissimulata, Plagiomnium ellipticum, Schistidium robustum, Sphenolobus minutus, Tortella fasciculata and T. pseudofragilis. Our study reveals the high nature conservation value of the upper Neretva and Zalomka River valleys that should be protected for future generations. In addition, further systematic research of the flora of Bosnia and Herzegovina is needed
Ključne besede: angiosperms, mosses, nature conservation, Neretva River, vegetation, are species
Objavljeno v DiRROS: 16.10.2025; Ogledov: 233; Prenosov: 104
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805. Optimal version of the fundamental theorem of chronogeometryMichiya Mori, Peter Šemrl, 2025, izvirni znanstveni članek Povzetek: We study lightlikeness preserving mappings from the $4$-dimensional Minkowski spacetime $\mathcal{M}_4$ to itself under no additional regularity assumptions like continuity, surjectivity, or injectivity. We prove that such a mapping $\phi$ satisfies one of the following three conditions. (1) The mapping $\phi$ can be written as a composition of a Lorentz transformation, a multiplication by a positive scalar, and a translation. (2) There is an event $r\in \mathcal{M}_4$ such that $\phi(\mathcal{M}_4\setminus\{r\})$ is contained in one light cone. (3) There is a lightlike line $\ell$ such that $\phi(\mathcal{M}_4\setminus \ell)$ is contained in another lightlike line. Here, a line that is contained in some light cone in $\mathcal{M}_4$ is called a lightlike line. We also give several similar results on mappings defined on a certain subset of $\mathcal{M}_4$ or the compactification of $\mathcal{M}_4$.
Ključne besede: fundamental theorem of chronogeometry, special relativity, coherency preserving mapping
Objavljeno v DiRROS: 16.10.2025; Ogledov: 205; Prenosov: 91
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806. Randomized methods for computing joint eigenvalues, with applications to multiparameter eigenvalue problems and root findingHaoze He, Daniel Kressner, Bor Plestenjak, 2025, izvirni znanstveni članek Povzetek: It is well known that a family of $n \times n$ commuting matrices can be simultaneously triangularized by a unitary similarity transformation. The diagonal entries of the triangular matrices define the $n$ joint eigenvalues of the family. In this work, we consider the task of numerically computing approximations to such joint eigenvalues for a family of (nearly) commuting matrices. This task arises, for example, in solvers for multiparameter eigenvalue problems and systems of multivariate polynomials, which are our main motivations. We propose and analyze a simple approach that computes eigenvalues as one-sided or two-sided Rayleigh quotients from eigenvectors of a random linear combination of the matrices in the family. We provide some analysis and numerous numerical examples, showing that such randomized approaches can compute semisimple joint eigenvalues accurately and lead to improved performance of existing solvers.
Ključne besede: commuting matrices, joint eigenvalues, Rayleigh quotient, randomized numerical linear algebra, multiparameter eigenvalue problems, polynomial systems
Objavljeno v DiRROS: 16.10.2025; Ogledov: 217; Prenosov: 117
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808. Effect of hardening on the magnetic behavior of AISI 1045 steelMario Vukotić, Damijan Miljavec, Jaka Burja, 2025, izvirni znanstveni članek Povzetek: Hardening is an effective method to improve the hardness of the steel construction elements of an electric machine, such as rotor shaft. Surface hardening is typically employed for shafts as it provides a material with hard wear-resistant surface (martensite) and tough and ductile core (ferrite and pearlite), with the transitional zone between them (martensite, ferrite, and pearlite). The investigations were performed on the specimens of AISI 1045 steel, which is commonly used in electric machines. There were three categories of specimens, each of them representing a region in a surface hardened shaft – normalized specimens found in as-delivered steel (core), partially hardened specimens obtained by partial hardening of normalized specimens (transitional zone), and fully hardened specimens (hardened surface), also obtained from the normalized steel. Comparison of the magnetization curves showed that partially and fully hardened specimens exhibited a decrease of saturation magnetic flux density for about 11% and 7%, respectively, compared to the normalized specimens. The magnetizing curves from this study can be directly used in the magnetic simulations of a surface-hardened shaft. This allows more accurate electromagnetic design of electric machines, in which the shaft represents an important part of the magnetic circuit, e.g. two-pole wound-rotor synchronous machine.
Ključne besede: electric machine, hardening, hysteresis loop, magnetic properties, magnetizing curve, microstructure, shaft
Objavljeno v DiRROS: 16.10.2025; Ogledov: 225; Prenosov: 129
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809. Workflow and practical guidance for identical location scanning electron microscopy: reliable tracking of localized transformationsBlaž Tomc, Marjan Bele, Ana Rebeka Kamšek, Milena Martins, Aleš Marsel, Miha Hotko, Stefan Popović, Gregor Kapun, Črtomir Donik, Mitja Kostelec, Matjaž Godec, Nejc Hodnik, Luka Suhadolnik, 2025, izvirni znanstveni članek Povzetek: Understanding material transformations at the nano- and microscale is essential for advancing electrocatalysis, energy storage, and other applications. Conventional SEM imaging, which captures random locations before and after treatment, struggles to distinguish real transformations from inherent sample heterogeneity. Identical Location SEM (IL-SEM) overcomes this by enabling re-imaging of the exact same region, offering clear evidence of localized changes in morphology, structure, and composition. Despite its simplicity and wide applicability, IL-SEM remains underutilized. This article presents a detailed, practical guide to implementing IL-SEM reliably, including sample alignment, multiscale imaging, and consistent re-localization. Key methodological tips and solutions to common challenges are provided, making the approach accessible even for non-expert users. To showcase its versatility, we present case studies involving electrocatalysts, alloys, and nanostructured materials. Moreover, by integrating IL-SEM with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD), we demonstrate how compositional and crystallographic evolution can be tracked alongside morphological changes. This optimized workflow offers a powerful, non-destructive method for visualizing dynamic material behavior and provides a foundation for IL-SEM to become a standard technique for studying structural evolution across diverse materials research fields.
Ključne besede: electrocatalysis, identical location electron microscopy, IL-SEM, materials characterization, scanning electron microscopy, surface analysis
Objavljeno v DiRROS: 15.10.2025; Ogledov: 299; Prenosov: 155
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810. Potential for improving the environmental sustainability of natural aggregates production (Slovenian case study)Janez Turk, Anja Kodrič, Rok Cajzek, Tjaša Zupančič Hartner, 2025, izvirni znanstveni članek Povzetek: The environmental performance of natural aggregates for concrete and road construction, extracted from a dolomite quarry, was investigated. Environmental hotspots were identified, and potential optimization measures to further reduce the environmental footprint were proposed. The natural aggregates extracted from the dolomite quarry have relatively low GWP and a low environmental footprint in general. The GWP of 1 tonne of natural aggregates used in concrete production is 1.13 kg CO2 equiv., while for 1 tonne of aggregates used in road construction, it is 0.97 kg CO2 equiv. The dolomite rock in the quarry in question is tectonically fractured, such that very intensive extraction is not required, taking into account the blasting of the rock and further processing. The use of non-road mobile machinery is already optimized. Additional reductions in environmental impact could be achieved by powering the screening process exclusively with electricity from renewable sources, such as a photovoltaic system. In this context, integrating on-site battery storage systems might present a promising solution for addressing the seasonal mismatch between solar energy generation and processing demands.
Ključne besede: rock extraction, global warming potential, environmental impact, optimization, sensitivity
Objavljeno v DiRROS: 15.10.2025; Ogledov: 225; Prenosov: 107
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