1. Lightweight aggregates made from fly ash using the cold-bond process and their use in lightweight concreteAna Frankovič, Violeta Bokan-Bosiljkov, Vilma Ducman, 2017, izvirni znanstveni članek Povzetek: Aggregates made from fly ash have been developed by means of the cold-bonding process, with the addition of Portland cement as a binder at (10, 20, and 30) % of mass fractions, and by pouring the mixtures into moulds. After curing for 28 d the samples were processed into aggregate by crushing and sieving. An aggregate containing a weight percentage of 10 % of cement was additionally produced by pelletization on a granulating plate. The density, water-adsorption capacity, porosity, compressive strengths, and frost resistance of the samples were determined. The aggregates prepared by both routes were then used to make concrete samples, whose properties were then compared to those of conventional concrete made using limestone aggregate. The compressive strength of the concrete made with the granulated aggregate reached 16.0 MPa after 28 d, whereas that of the concrete made with crushed aggregate amounted to 24.1 MPa, and that of the conventional concrete was 34.6 MPa.
Ključne besede: fly ash, lightweight aggregates, density, compressive strength, frost resistance
Objavljeno v DiRROS: 14.08.2024; Ogledov: 286; Prenosov: 204
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2. The Ural Owl, Strix uralensis macroura, in Slovenia : an overview of current knowledge on species ecologyAl Vrezec, Tomaž Mihelič, 2012, izvirni znanstveni članek Povzetek: In Slovenia the Ural Owl, Strix uralensis macroura, is on the north-western limit of its distribution with an estimated population size of 400-700 breeding pairs. The densities of territories range between 0.9 to 13.4 territories per 10 km2, and the highest densities are reached in montane forests of the southern Dinaric region. In the forests with dominant deciduous trees, e.g. Fagus sylvatica and Quercus robur, the breeding densities are significantly higher than in the forests with a higher proportion of coniferous trees, e.g. Picea abies. The species does not select specific altitude and throughout Slovenia it occurs between 150 and 1600 m a.s.l. Most natural nests were found in tree holes or semi-holes (56%) and on the tree stumps (20%). Breeding begins between 15 March to 21 June with median clutch sizes of 3.0 eggs per nest. In the brood there are 2 young and 1.5 young are fledged in median. At present 75% of nests produce at least one young. Voles and Mice are the most frequent prey in the diet, but the Fat Dormouse, Glis glis, seems to have very important role in the post-breeding period. As a top predator, the Ural Owl influences also the distribution of other owl species in the guild through direct predation or competitive exclusion. However, it could have also a positive indirect effect on smaller species, e.g. Tengmalm’s Owl, Aegolius funereus, which are tolerated within Ural Owl territories, and are able to extend their distribution due to exclusion from certain areas of the Tawny Owl, Strix aluco, by the Ural Owl.
Ključne besede: distribution, breeding density, habitat, breeding biology, interactions, Slovenia
Objavljeno v DiRROS: 05.08.2024; Ogledov: 227; Prenosov: 159
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3. Exceptional dense water formation on the Adriatic shelf in the winter of 2012Hrvoje Mihanović, Ivica Vilibić, Sandro Carniel, M. Tudor, A. Russo, A. Bergamasco, N. Bubić, Z. Ljubešić, Damir Viličić, A. Boldrin, Vlado Malačič, Massimo Celio, Cinzia Comici, F. Raicich, 2013, izvirni znanstveni članek Povzetek: In this paper we document dense water formation throughout the Adriatic shelf and coastal area in January/February 2012, resulting in record-breaking densities observed during and after the event. The unprecedented dense water generation was preconditioned by a dry and warm year which resulted in a significant reduction of coastal freshwaters, superimposed on a long-term basin-wide salinity increase. The final event that triggered the dense water formation was an extended period of cold weather with strong and severe winds. Record-breaking potential density anomalies (above 30 kg m−3) were measured at several formation sites. Accumulated surface net heat and water losses in some coastal regions exceeded 1.5 GJ m−2 and 250 kg m−2 over 21 days, respectively. Excessiveness, importance of shelf-type dense water formation and effects on the thermohaline circulation and deep aquatic systems are discussed.
Ključne besede: sea, marine water, density, physical oceanography, dense water, water density, Adriatic sea, Mediterranean sea, Adriatic shelf
Objavljeno v DiRROS: 02.08.2024; Ogledov: 266; Prenosov: 235
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4. Model uncertainty in a parametric fire curve approach : a stochastic correction factor for the compartment fire load densityFlorian Put, Andrea Lucherini, Bart Merci, Ruben Van Coile, 2024, izvirni znanstveni članek Povzetek: A commonly used approach to represent the thermal load in a compartment fire is the Eurocode Parametric Fire Curve (EPFC), which specifies gas temperatures (or rather adiabatic surface temperatures). Recognizing the significant deviations between real fires and the EPFC framework, the concept of model uncertainty is explored. This study does not aim to assess or improve the EPFC, but introduces a model uncertainty, allowing for reliability-based structural fire engineering (SFE). It presents a stochastic correction factor for the fire load density, based on the maximum temperature in steel sections. The focus is on the fire load density, but in general other parameters can be jointly taken into account as well. This correction factor considers protected and un- protected sections, incorporating variations in section factor and protection thickness. The findings reveal that the fire load density within the EPFC framework can be modified to better represent the severity of fire ex- periments. This approach ensures physical consistency of the obtained compartment gas temperatures, as opposed to alternative approaches for addressing the EPFC model uncertainty. While promising results are evident in this proof of concept, exploration for other types of structural elements and evaluation for structural systems is necessary before integration into design practices.
Ključne besede: structural fire engineering, compartment fires, fire load density, steel structures, reliability, probability of failure
Objavljeno v DiRROS: 17.04.2024; Ogledov: 404; Prenosov: 79
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5. Recent developments on Oka manifoldsFranc Forstnerič, 2023, pregledni znanstveni članek Povzetek: In this paper we present the main developments in Oka theory since the publication of my book "Stein Manifolds and Holomorphic Mappings (The Homotopy Principle in Complex Analysis)", 2nd ed., Springer, 2017. We also give several new results, examples and constructions of Oka domains in Euclidean and projective spaces. Furthermore, we show that for $n > 1$ the fibre $\mathbb C^n$ in a Stein family can degenerate to a non-Oka fibre, thereby answering a question of Takeo Ohsawa. Several open problems are discussed.
Ključne besede: Oka manifold, Oka map, Stein manifold, elliptic manifold, algebraically subelliptic manifold, Calabi–Yau manifold, density property
Objavljeno v DiRROS: 14.03.2024; Ogledov: 795; Prenosov: 629
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6. Oka domains in Euclidean spacesFranc Forstnerič, Erlend Fornæss Wold, 2024, izvirni znanstveni članek Povzetek: In this paper, we find surprisingly small Oka domains in Euclidean spaces $\mathbb C^n$ of dimension $n>1$ at the very limit of what is possible. Under a mild geometric assumption on a closed unbounded convex set $E$ in $\mathbb C^n$, we show that $\mathbb C^n\setminus E$ is an Oka domain. In particular, there are Oka domains only slightly bigger than a halfspace, the latter being neither Oka nor hyperbolic. This gives smooth families of real hypersurfaces $\Sigma_t \subset \mathbb C^n$ for $t \in \mathbb R$ dividing $\mathbb C^n$ in an unbounded hyperbolic domain and an Oka domain such that at $t=0$, $\Sigma_0$ is a hyperplane and the character of the two sides gets reversed. More generally, we show that if $E$ is a closed set in $\mathbb C^n$ for $n>1$ whose projective closure $\overline E \subset \mathbb{CP}^n$ avoids a hyperplane $\Lambda \subset \mathbb{CP}^n$ and is polynomially convex in $\mathbb{CP}^n\setminus \Lambda\cong\mathbb C^n$, then $\mathbb C^n\setminus E$ is an Oka domain.
Ključne besede: Oka manifold, hyperbolic manifolds, density property, projectively convex sets
Objavljeno v DiRROS: 19.02.2024; Ogledov: 690; Prenosov: 222
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7. Complete nonsingular holomorphic foliations on Stein manifoldsAntonio Alarcón, Franc Forstnerič, 2024, izvirni znanstveni članek Povzetek: Let $X$ be a Stein manifold of complex dimension $n \ge 1$ endowed with a Riemannian metric ${\mathfrak g}$. We show that for every integer $k$ with $\left[\frac{n}{2}\right] \le k \le n-1$ there is a nonsingular holomorphic foliation of dimension $k$ on $X$ all of whose leaves are topologically closed and ${\mathfrak g}$-complete. The same is true if $1\le k \left[\frac{n}{2}\right]$ provided that there is a complex vector bundle epimorphism $TX\to X \times \mathbb{C}^{n-k}$. We also show that if $\mathcal{F}$ is a proper holomorphic foliation on $\mathbb{C}^n$ $(n > 1)$ then for any Riemannian metric ${\mathfrak g}$ on $\mathbb{C}^n$ there is a holomorphic automorphism $\Phi$ of $\mathbb{C}^n$ such that the image foliation $\Phi_*\mathcal{F}$ is ${\mathfrak g}$-complete. The analogous result is obtained on every Stein manifold with Varolin's density property.
Ključne besede: Stein manifolds, complete holomorphic foliations, density property
Objavljeno v DiRROS: 19.02.2024; Ogledov: 516; Prenosov: 215
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8. Mechanical properties of high carbon low-density steelsJiri Hajek, Zbyšek Nový, Ludmila Kucerova, Hana Jirková, Črtomir Donik, Zdeňek Jansa, 2023, izvirni znanstveni članek Ključne besede: low density steels, heat treatment, tensile test
Objavljeno v DiRROS: 02.02.2024; Ogledov: 519; Prenosov: 258
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9. Selective glucose oxidation to glucaric acid using bimetallic catalysts : lattice expansion or electronic structure effect?Žan Lavrič, Janvit Teržan, Ana Kroflič, Janez Zavašnik, Joanna E. Olszówka, Štefan Vajda, Matej Huš, Miha Grilc, Blaž Likozar, 2024, izvirni znanstveni članek Povzetek: Our study presents a comprehensive approach for the selective oxidation of glucose to glucaric acid (GA) by heterogeneous catalysis. We have synthesized and characterized Au/ZrO2, AuCu/ZrO2 and AuPt/ZrO2 catalysts using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and oxygen pulse chemisorption (OPS) techniques. Combining experimental observations with in-depth density functional theory (DFT) studies, we found that bimetallic catalysts form alloys, which exhibit different characteristics than monometallic counterparts for the given reaction. We performed batch reactions, varying temperature and oxygen pressure, and used the data to construct a predictive microkinetic model. As it turned out, AuPt/ZrO2 showed the highest selectivity, yielding 32 % of GA at 100 °C and 30 barg O2. Our results provide valuable insights for the developing of efficient catalysts and point out the bottlenecks for the oxidation of glucose to GA.
Ključne besede: glucaric acid, glucose oxidation, catalyst characterization, density functional theory, microkinetic modelling
Objavljeno v DiRROS: 06.12.2023; Ogledov: 610; Prenosov: 262
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10. Quality-assurance of heat-flow data: the new structure and evaluation scheme of the IHFC Global Heat Flow DatabaseSven Fuchs, Ben Norden, Florian Neumann, Norbert Kaul, Akiko Tanaka, Ilmo T. Kukkonen, Christophe Pascal, Rodolfo Christiansen, Gianluca Gola, Dušan Rajver, 2023, izvirni znanstveni članek Povzetek: Since 1963, the International Heat Flow Commission has been fostering the compilation of the Global Heat Flow Database to provide reliable heat-flow data. Over time, techniques and methodologies evolved, calling for a reorganization of the database structure and for a reassessment of stored heat-flow data. Here, we provide the results of a collaborative, community-driven approach to set-up a new, quality-approved global heat-flow database. We present background information on how heat-flow is determined and how this important thermal parameter could be systematically evaluated. The latter requires appropriate documentation of metadata to allow the application of a consistent evaluation scheme. The knowledge of basic data (name and coordinates of the site, depth range of temperature measurements, etc.), details on temperature and thermal-conductivity data and possible perturbing effects need to be given. The proposed heat-flow quality evaluation scheme can discriminate between different quality aspects affecting heat flow: numerical uncertainties, methodological uncertainties, and environmental effects. The resulting quality codes allow the evaluation of every stored heat-flow data entry. If mandatory basic data are missing, the entry is marked accordingly. In cases where more than one heat-flow determination is presented for one specific site, and all of them are considered for the site, the poorest evaluation score is inherited to the site level. The required data and the proposed scheme are presented in this paper. Due to the requirements of the newly developed evaluation scheme, the database structure as presented in 2021 has been updated and is available in the appendix of this paper. The new quality scheme will allow a comprehensible evaluation of the stored heat-flow data for the first time.
Ključne besede: heat-flow density, quality scheme, thermal geophysics, global heat flow database (GHFD), thermal parameter, data information system, International Heat Flow Commission (IHFC)
Objavljeno v DiRROS: 09.08.2023; Ogledov: 596; Prenosov: 237
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