1991. 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: 810; Prenosov: 643 Celotno besedilo (1014,41 KB) Gradivo ima več datotek! Več... |
1992. Optimal approximation of spherical squares by tensor product quadratic Bézier patchesAleš Vavpetič, Emil Žagar, 2023, izvirni znanstveni članek Povzetek: In cited article E. F. Eisele considered the problem of the optimal approximation of symmetric surfaces by biquadratic Bézier patches. Unfortunately, the results therein are incorrect, which is shown in this paper by considering the optimal approximation of spherical squares. A detailed analysis and a numerical algorithm are given, providing the best approximant according to the (simplified) radial error, which differs from the one obtained mentioned article. The sphere is then approximated by the continuous spline of two and six tensor product quadratic Bézier patches. It is further shown that the $G^1$ smooth spline of six patches approximating the sphere exists, but it is not a good approximation. The problem of an approximation of spherical rectangles is also addressed and numerical examples indicate that several optimal approximants might exist in some cases, making the problem extremely difficult to handle. Finally, numerical examples are provided that confirm the theoretical results. Ključne besede: Bézier patches, spherical squares, optimal approximation, sphere approximation Objavljeno v DiRROS: 14.03.2024; Ogledov: 494; Prenosov: 207 Celotno besedilo (1,59 MB) Gradivo ima več datotek! Več... |
1993. Resolving a structural issue in cerium-nickel-based oxide : single compound or a two-phase system?Jelena Kojčinović, Dalibor Tatar, Stjepan Šarić, Cora Pravda Bartus, Andraž Mavrič, Iztok Arčon, Zvonko Jagličić, Maximilian Mellin, Marcus Einert, Angela Altomare, Rocco Caliandro, 2024, izvirni znanstveni članek Ključne besede: cerium oxide, nickel oxide, crystallography Objavljeno v DiRROS: 13.03.2024; Ogledov: 768; Prenosov: 616 Celotno besedilo (4,01 MB) Gradivo ima več datotek! Več... |
1994. Coherence and avoidance of sure loss for standardized functions and semicopulasErich Peter Klement, Damjana Kokol-Bukovšek, Blaž Mojškerc, Matjaž Omladič, Susanne Saminger, Nik Stopar, 2024, izvirni znanstveni članek Povzetek: We discuss avoidance of sure loss and coherence results for semicopulas and standardized functions, i.e., for grounded, $1$-increasing functions with value $1$ at $(1, 1, \ldots , 1)$. We characterize the existence of a $k$-increasing $n$-variate function $C$ fulfilling $A \le C \le B$ for standardized $n$-variate functions $A$, $B$ and discuss methods for constructing such functions. Our proofs also include procedures for extending functions on some countably infinite mesh to functions on the unit box. We provide a characterization when $A$ respectively $B$ coincides with the pointwise infimum respectively supremum of the set of all $k$-increasing $n$-variate functions $C$ fulfilling $A \le C \le B$. Ključne besede: copulas, quasi-copulas, semicopulas, standardized function, coherence, avoidance of sure loss, k-increasing function Objavljeno v DiRROS: 13.03.2024; Ogledov: 420; Prenosov: 217 Celotno besedilo (992,65 KB) Gradivo ima več datotek! Več... |
1995. Outerplane bipartite graphs with isomorphic resonance graphsSimon Brezovnik, Zhongyuan Che, Niko Tratnik, Petra Žigert Pleteršek, 2024, izvirni znanstveni članek Povzetek: We present novel results related to isomorphic resonance graphs of 2-connected outerplane bipartite graphs. As the main result, we provide a structure characterization for 2-connected outerplane bipartite graphs with isomorphic resonance graphs. Three additional characterizations are expressed in terms of resonance digraphs, via local structures of inner duals, as well as using distributive lattices on the set of order ideals of posets defined on inner faces of 2-connected outerplane bipartite graphs. Ključne besede: distributive lattice, inner dual, isomorphic resonance graphs, order ideal, 2-connected outerplane bipartite graph Objavljeno v DiRROS: 13.03.2024; Ogledov: 472; Prenosov: 239 Celotno besedilo (452,02 KB) Gradivo ima več datotek! Več... |
1996. On the structure of consistent cycles in cubic symmetric graphsKlavdija Kutnar, Dragan Marušič, Štefko Miklavič, Primož Šparl, 2024, izvirni znanstveni članek Ključne besede: 1/2-consistent cycles, automorphisms, consistent cycles, cubic symmetric graphs, shunt, s-regular graphs Objavljeno v DiRROS: 13.03.2024; Ogledov: 429; Prenosov: 216 Celotno besedilo (1,02 MB) Gradivo ima več datotek! Več... |
1997. On the exact region determined by Spearman's rho and Spearman's footruleDamjana Kokol-Bukovšek, Nik Stopar, 2024, izvirni znanstveni članek Povzetek: We determine the lower bound for possible values of Spearman’s rho of a bivariate copula given that the value of its Spearman's footrule is known and show that this bound is always attained. We also give an estimate for the exact upper bound and prove that the estimate is exact for some but not all values of Spearman's footrule. Nevertheless, we show that the estimate is quite tight. Ključne besede: copula, dependence concepts, supremum and infimum of a set of copulas, measures of concordance, quasi-copula, local bounds Objavljeno v DiRROS: 13.03.2024; Ogledov: 459; Prenosov: 208 Celotno besedilo (1,55 MB) Gradivo ima več datotek! Več... |
1998. Minimal surfaces with symmetriesFranc Forstnerič, 2024, izvirni znanstveni članek Povzetek: Let $G$ be a finite group acting on a connected open Riemann surface $X$ by holomorphic automorphisms and acting on a Euclidean space ${\mathbb R}^n$ $(n\ge 3)$ by orthogonal transformations. We identify a necessary and sufficient condition for the existence of a $G$-equivariant conformal minimal immersion $F:X\to{\mathbb R}^n$. We show in particular that such a map $F$ always exists if $G$ acts without fixed points on $X$. Furthermore, every finite group $G$ arises in this way for some open Riemann surface $X$ and $n=2|G|$. We obtain an analogous result for minimal surfaces having complete ends with finite total Gaussian curvature, and for discrete infinite groups acting on $X$ properly discontinuously and acting on ${\mathbb R}^n$ by rigid transformations. Ključne besede: Riemann surfaces, minimal surfaces, G-equivariant conformal minimal immersion Objavljeno v DiRROS: 13.03.2024; Ogledov: 436; Prenosov: 174 Celotno besedilo (483,34 KB) Gradivo ima več datotek! Več... |
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2000. Weathering effects on cellulose acetate microplastics from discarded cigarette buttsBranka Mušič, Andrijana Sever Škapin, 2024, objavljeni znanstveni prispevek na konferenci (vabljeno predavanje) Povzetek: Cellulose acetate, commonly used in cigarette filters, poses environmental concerns due to its questionable (bio)degradability and prevalent presence in nature. This study compares the weathering effects on two types of cigarette filters: traditional and newer filters used in heated tobacco devices (HTP). Microplastics were derived from used cigarette parts and then subjected to artificial aging. Analytical techniques (Thermogravimetry-Differential Scanning Calorimetry TG/DSC, Fourier-Transform Infrared Spectroscopic Analysis (FTIR)) and loose bulk density measurements were employed pre- and post-aging cellulose acetate of both types of samples. Despite increasing evidence influencing European Union (EU) directives on tobacco product disposal, there's a lack of systematic analysis on the weathering impact, especially concerning the touted environmental benefits of newer filters. Results indicate decreased particle size in cellulose acetate filters post-aging. Variances were observed in thermal behavior, yet FTIR spectra remained unchanged. Ključne besede: cellulose acetate, cigarette filters, microplastics, artificial weathering, polymer degradation Objavljeno v DiRROS: 12.03.2024; Ogledov: 644; Prenosov: 499 Celotno besedilo (84,58 MB) Gradivo ima več datotek! Več... |