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1752. Značilnosti in gospodarjenje z gozdovi plemenitih listavcev - habitatni tip Javorovi gozdovi (Natura 2000) : spletni seminar ZGS, Ljubljana, 15. februar 2024Valerija Babij, Lado Kutnar, Janez Kermavnar, Anže Martin Pintar, 2024, druge monografije in druga zaključena dela Ključne besede: vegetacija, rastišče, ekologija gozda, gozdovi plemenitih listavcev, gospodarjenje z gozdovi, Natura 2000 Objavljeno v DiRROS: 05.03.2024; Ogledov: 419; Prenosov: 115
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1753. Lower bounds on the homology of Vietoris–Rips complexes of hypercube graphsHenry Adams, Žiga Virk, 2024, izvirni znanstveni članek Povzetek: We provide novel lower bounds on the Betti numbers of Vietoris-Rips complexes of hypercube graphs of all dimensions, and at all scales. In more detail, let $Q_n$ be the vertex set of $2^n$ vertices in the $n$-dimensional hypercube graph, equipped with the shortest path metric. Let ${\rm VR}(Q_n;r)$ be its Vietoris-Rips complex at scale parameter $r \ge 0$, which has $Q_n$ as its vertex set, and all subsets of diameter at most $r$ as its simplices. For integers $r < r'$ the inclusion ${\rm VR}(Q_n;r) \hookrightarrow {\rm VR}(Q_n;r')$ is nullhomotopic, meaning no persistent homology bars have length longer than one, and we therefore focus attention on the individual spaces ${\rm VR}(Q_n;r)$. We provide lower bounds on the ranks of homology groups of ${\rm VR}(Q_n;r)$. For example, using cross-polytopal generators, we prove that the rank of $H_{2^r-1}({\rm VR}(Q_n;r))$ is at least $2^{n-(r+1)}\binom{n}{r+1}$. We also prove a version of homology propagation: if $q\ge 1$ and if $p$ is the smallest integer for which ${\rm rank} H_q({\rm VR}(Q_p;r)) \neq 0$, then ${\rm rank} H_q({\rm VR}(Q_n;r)) \ge \sum_{i=p}^n 2^{i-p} \binom{i-1}{p-1} \cdot {\rm rank} H_q({\rm VR}(Q_p;r))$ for all $n \ge p$. When $r \le 3$, this result and variants thereof provide tight lower bounds on the rank of $H_q({\rm VR}(Q_n;r))$ for all $n$, and for each $r \ge 4$ we produce novel lower bounds on the ranks of homology groups. Furthermore, we show that for each $r\ge 2$, the homology groups of ${\rm VR}(Q_n;r)$ for $n \ge 2r+1$ contain propagated homology not induced by the initial cross-polytopal generators. Ključne besede: Vietoris–Rips complexes, clique complexes, hypercubes, Betti numbers Objavljeno v DiRROS: 05.03.2024; Ogledov: 429; Prenosov: 158
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1754. Treatment of condensation in sandwich panels without known vapour resistance of sealantGregor Vidmar, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: In order to calculate amount of interstitial condensation in a building envelope, water vapour resistance of each layer is of importance. Once having it, 1D calculation according to ISO 13788 with monthly average vapour pressures can be applied. In EN 14509 sandwich panels are considered to be impermeable for water vapour, thus (according to the standard) water vapour cannot enter from outside and condensate in the panels. But it is not always true for real sandwich panels, because joints between neighbouring panels can cause non-neglecting water vapour bridges. Although in measurements of linear water vapour transmittance of the joints (Ψv) stationary boundary vapour pressures can be applied, the measurements can be long lasting. We shortened time needed to get Ψv performing simulations in Delphin6.0. We simulated panels and steel sheets with joints using constant boundary vapour pressures and compared the results with the results of measurements on the equivalent systems.
In systems under consideration a sealant in built-in-state, located at a joint of a sandwich panel, is a compressed EPDM tube. It is impossible to directly measure its effective μ according to ISO 12572. In the paper we study to which precision it is possible to determine it using measurements and simulations. Once having effective μ of the sealant (if all other necessary material parameters available) one can simulate condensation in envelopes including sandwich panels in 2D according to EN 15026 using hourly climatic data. Another goal of the study was determination of differences in resulting Ψv values when varying narrowest part of the gap dGAP at the joint in the panels without any sealant. Results confirm significant sensibility of Ψv to variations of dGAP. Ključne besede: water vapour condensation, water vapour diffusion, numerical simulations, water vapour resistance, linear water vapour transmittance, sendwich panels Objavljeno v DiRROS: 05.03.2024; Ogledov: 371; Prenosov: 234
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1755. Evaluation of fly ash-based alkali activated foams at room and elevated temperaturesKatja Traven, Mark Češnovar, Srečo D. Škapin, Vilma Ducman, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: Alkali activated materials (AAM) are, in their broadest classification, any binder systems derived by the reaction of an alkali metal source (silicates, alkali hydroxides, carbonates , sulphates) with a solid, amorphous alumosilicate powder (found in precursors such as slag, fly ash and bottom ash). A wide variety of products can be obtained by the alkali activation process and could replace traditional construction products. Among the se, alkali activated foams (AAF) represent one of the most promising materials, owing to their economically accessible alumosilicate rich source materials, including industrial waste materials, clean processing, higher added value and most importantly, pro ducts with competitive properties. In the present study, the properties of alkali activated fly ash - based foam materials were studied at room temperature as well as at elevated temperatures (up to 1200 °C ) in order to develop a durable material in terms o f mechanical properties and suitability for high temperature applications. Ključne besede: lightweight porous insulating material, alkali activated materials, microstructural analysis Objavljeno v DiRROS: 05.03.2024; Ogledov: 443; Prenosov: 366
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1756. BIM and LCA integration : a systematic literature reviewTajda Potrč Obrecht, Martin Röck, Endrit Hoxha, Alexander Passer, 2020, pregledni znanstveni članek Povzetek: To foster sustainable development, the environmental impacts of the construction sector need to be reduced substantially. Life cycle assessment (LCA) is the established methodology for the quantification of environmental impacts, and therefore has been increasingly applied to assess the environmental performance of buildings. By coupling LCAs with digital design tools, e.g., building information modeling (BIM), the identification of environmental hotspots and their mitigation is possible during the design process. The objective of the study is to identify the current integration approaches, and determine the pros and cons of the integration process from different viewpoints, namely, technical, informational, organizational and functional issues. Therefore, a comprehensive systematic literature review (SLR) was performed. We identified 60 relevant BIM-LCA case studies and analyzed the applied BIM-LCA workflows in detail. A total of 16 of the reviewed studies applied LCA during the early design stage. These studies used a manual or semiautomatic data exchange between the BIM models and LCA tools. In most cases, contemporary BIM-LCA workflows utilized conventional spreadsheets (e.g., Excel sheets in 16 cases). However, the analysis shows that an automated link between LCA and BIM can be achieved when overcoming the technical, organizational and informational issues discussed in the paper. This could enable the streamlining of LCA applications in design practice, and thus support the necessary improvements in the environmental performance of buildings. Ključne besede: building information modeling (BIM), life cycle assessment (LCA), systematic literaturereview (SLR), environmental product declarations (EPD), workflow, bill of quantities (BoQ) Objavljeno v DiRROS: 05.03.2024; Ogledov: 490; Prenosov: 153
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1757. The use of paper industry side product in constructionBarbara Likar, Laura Vovčko, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: The amount of waste material and side products of various industrial plants is increasing, which leads into waste accumulation and lack of space in disposal landfills. Paper industry, with its side products paper sludge and ash, faces these same issues. To reduce the accumulation of these materials, we explored the possibility of their use in construction. At first a series of geomechanical tests was conducted on a product consisting of fly ash and bottom ash. Based on the laboratory results test fields were constructed, where the preparation and installation technologies were tested. The fields were exposed to the atmospheric conditions, so durability of the product in the natural environment was proven. Since the composition of both fly ash and bottom ash depends on the paper industry process, a continuous monitoring of their characteristics was established. Ključne besede: paper industry, fly ash, bottom ash, construction material, geomechanical properties Objavljeno v DiRROS: 05.03.2024; Ogledov: 357; Prenosov: 147
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1758. Reviewing the modeling aspects and practices of shallow geothermal energy systemsPaul Christodoulides, Ana Vieira, Stanislav Lenart, João Maranha, Gregor Vidmar, Rumen Popov, Aleksandar Georgiev, Lazaros Aresti, Georgios Florides, 2020, pregledni znanstveni članek Povzetek: Shallow geothermal energy systems (SGES) may take different forms and have recently taken considerable attention due to energy geo-structures (EGS) resulting from the integration of heat exchange elements in geotechnical structures. Still, there is a lack of systematic design guidelines of SGES. Hence, in order to contribute towards that direction, the current study aims at reviewing the available SGES modeling options along with their various aspects and practices. This is done by first presenting the main analytical and numerical models and methods related to the thermal behavior of SGES. Then, the most important supplementary factors affecting such modeling are discussed. These include: (i) the boundary conditions, in the form of temperature variation or heat flow, that majorly affect the predicted thermal behavior of SGES; (ii) the spatial dimensions that may be crucial when relaxing the infinite length assumption for short heat exchangers such as energy piles (EP); (iii) the determination of SGES parameters that may need employing specific techniques to overcome practical difficulties; (iv) a short-term vs. long-term analysis depending on the thermal storage characteristics of GHE of different sizes; (v) the influence of groundwater that can have a moderating effect on fluid temperatures in both heating and cooling modes. Subsequently, thermo-mechanical interactions modeling issues are addressed that may be crucial in EGS that exhibit a dual functioning of heat exchangers and structural elements. Finally, a quite lengthy overview of the main software tools related to thermal and thermo-hydro-mechanical analysis of SGES that may be useful for practical applications is given. A unified software package incorporating all related features of all SGES may be a future aim. Ključne besede: shalow geothermal energy systems, energy geo-structures, thermal analysis, thermo-hydro-mechanical, modelling, software tools Objavljeno v DiRROS: 05.03.2024; Ogledov: 399; Prenosov: 170
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1759. Metal–support interaction between titanium oxynitride and Pt nanoparticles enables efficient low-Pt-loaded high-performance electrodes at relevant oxygen reduction reaction current densitiesArmin Hrnjić, Ana Rebeka Kamšek, Lazar Bijelić, Anja Logar, Nik Maselj, Milutin Smiljanić, Jan Trputec, Natan Vovk, Luka Pavko, Francisco Ruiz-Zepeda, Marjan Bele, Primož Jovanovič, Nejc Hodnik, 2024, izvirni znanstveni članek Objavljeno v DiRROS: 04.03.2024; Ogledov: 321; Prenosov: 156
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1760. On a continuation of quaternionic and octonionic logarithm along curves and the winding numberGraziano Gentili, Jasna Prezelj, Fabio Vlacci, 2024, izvirni znanstveni članek Povzetek: This paper deals with the problem of finding a continuous extension of the hypercomplex (quaternionic or octonionic) logarithm along (quaternionic or octonionic) paths which avoid the origin. The main difficulty depends upon this fact: while a branch of the complex logarithm can be defined in a small open neighbourhood of a strictly negative real point, no continuous branch of the hypercomplex logarithm can be defined in any open set which contains a strictly negative real point. To overcome this difficulty, we use the logarithmic manifold: in general, the existence of a lift of a path to this manifold is not guaranteed and, indeed, the problem of lifting a path to the logarithmic manifold is completely equivalent to the problem of finding a continuation of the hypercomplex logarithm along this path. The second part of the paper scrutinizes the existence of a notion of winding number (with respect to the origin) for hypercomplex loops that avoid the origin, even though it is known that the definition of winding number for such loops is not natural in ${\mathbb R}^n$ when $n$ is greater than $2$. The surprise is that, in the hypercomplex setting, the new definition of winding number introduced in this paper can be given and has full meaning for a large class of hypercomplex loops (untwisted loops with companion that avoid the origin). Finally an original but rather natural notion of homotopy for these hypercomplex loops (the $c$-homotopy) is presented and it is proved to be suitable to comply with the intrinsic geometrical meaning of the winding number for this class of loops, namely, two such hypercomplex loops are $c$-homotopic if, and only if, they have the same winding number. Ključne besede: hypercomplex logarithm, continuation of the hypercomplex logarithm along paths, winding number Objavljeno v DiRROS: 04.03.2024; Ogledov: 376; Prenosov: 166
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