Digital repository of Slovenian research organisations

Search the repository
A+ | A- | Help | SLO | ENG

There are two search modes available: simple and advanced. Simple search can include one or more words from the title, summary, keywords or full text, but does not allow the use of search operators. Advanced search allows to limit the number of search results by entering the search terms of different categories in the search window, as well as the use of Boolean search operators (AND, OR and AND NOT). In search results short formats of records are displayed and some data are displayed as links, which open a detailed description of the material (title link) or perform a new search (author or keyword link).

Help
Search in:
Options:
 


471 - 480 / 2000
First pagePrevious page44454647484950515253Next pageLast page
471.
472.
Domains without parabolic minimal submanifolds and weakly hyperbolic domains
Franc Forstnerič, 2023, original scientific article

Abstract: We show that if $\Omega$ is an $m$-convex domain in $\mathbb{R}^n$ for some $2 \le m < n$ whose boundary $b\Omega$ has a tubular neighbourhood of positive radius and is not $m$-flat near infinity, then $\Omega$ does not contain any immersed parabolic minimal submanifolds of dimension $\ge m$. In particular, if $M$ is a properly embedded non-flat minimal hypersurface in $\mathbb{R}^n$ with a tubular neighbourhood of positive radius, then every immersed parabolic hypersurface in $\mathbb{R}^n$ intersects $M$. In dimension $n=3$, this holds if $M$ has bounded Gaussian curvature function. We also introduce the class of weakly hyperbolic domains $\Omega$ in $\mathbb{R}^n$, characterised by the property that every conformal harmonic map $\mathbb{C} \to \Omega$ is constant, and we elucidate their relationship with hyperbolic domains, and domains without parabolic minimal surfaces.
Keywords: minimal surfaces, m-plurisubharmonic functions, hyperbolic domain
Published in DiRROS: 10.04.2024; Views: 459; Downloads: 419
.pdf Full text (242,50 KB)
This document has many files! More...

473.
The Waring problem for matrix algebras, II
Matej Brešar, Peter Šemrl, 2023, original scientific article

Abstract: Let $f$ be a noncommutative polynomial of degree $m\ge 1$ over an algebraically closed field $F$ of characteristic $0$. If $n\ge m-1$ and $\alpha_1,\alpha_2,\alpha_3$ are nonzero elements from $F$ such that $\alpha_1+\alpha_2+\alpha_3=0$, then every trace zero $n\times n$ matrix over $F$ can be written as $\alpha_1 A_1+\alpha_2A_2+\alpha_3A_3$ for some $A_i$ in the image of $f$ in $M_n(F)$.
Keywords: Waring problem, noncommutatative polynomials, matrix algebras
Published in DiRROS: 10.04.2024; Views: 161; Downloads: 87
.pdf Full text (133,03 KB)
This document has many files! More...

474.
Variety of mutual-visibility problems in graphs
Serafino Cicerone, Gabriele Di Stefano, Lara Drožđek, Jaka Hedžet, Sandi Klavžar, Ismael G. Yero, 2023, original scientific article

Abstract: If $X$ is a subset of vertices of a graph $G$, then vertices $u$ and $v$ are $X$-visible if there exists a shortest $u,v$-path $P$ such that $V(P)\cap X \subseteq \{u,v\}$. If each two vertices from $X$ are $X$-visible, then $X$ is a mutual-visibility set. The mutual-visibility number of $G$ is the cardinality of a largest mutual-visibility set of $G$ and has been already investigated. In this paper a variety of mutual-visibility problems is introduced based on which natural pairs of vertices are required to be $X$-visible. This yields the total, the dual, and the outer mutual-visibility numbers. We first show that these graph invariants are related to each other and to the classical mutual-visibility number, and then we prove that the three newly introduced mutual-visibility problems are computationally difficult. According to this result, we compute or bound their values for several graphs classes that include for instance grid graphs and tori. We conclude the study by presenting some inter-comparison between the values of such parameters, which is based on the computations we made for some specific families.
Keywords: mutual-visibility, total mutual-visibility, dual mutual-visibility number, outer mutual-visibility, grid graphs, torus graphs, computational complexity
Published in DiRROS: 10.04.2024; Views: 214; Downloads: 95
.pdf Full text (456,36 KB)
This document has many files! More...

475.
On a definition of logarithm of quaternionic functions
Graziano Gentili, Jasna Prezelj, Fabio Vlacci, 2023, original scientific article

Abstract: For a slice-regular quaternionic function $f$, the classical exponential function ${\mathrm exp} f$ is not slice-regular in general. An alternative definition of an exponential function, the $\ast$-exponential ${\mathrm exp}_\ast$, was given in the work by Altavilla and de Fabritiis (2019): if $f$ is a slice-regular function, then ${\mathrm exp}_\ast f$ is a slice-regular function as well. The study of a $\ast$-logarithm ${\mathrm log}_\ast f$ of a slice-regular function $f$ becomes of great interest for basic reasons, and is performed in this paper. The main result shows that the existence of such a ${\mathrm log}_\ast f$ depends only on the structure of the zero set of the vectorial part $f_v$ of the slice-regular function $f = f_0 + f_v$, besides the topology of its domain of definition. We also show that, locally, every slice-regular nonvanishing function has a $\ast$-logarithm and, at the end, we present an example of a nonvanishing slice-regular function on a ball which does not admit a $\ast$-logarithm on that ball.
Keywords: regular functions over quaternions, quaternionic logarithm of slice-regular functions
Published in DiRROS: 10.04.2024; Views: 204; Downloads: 81
.pdf Full text (425,44 KB)
This document has many files! More...

476.
Critical edges in Rips complexes and persistence
Peter Goričan, Žiga Virk, 2023, original scientific article

Abstract: We consider persistent homology obtained by applying homology to the open Rips filtration of a compact metric space $(X, d)$. We show that each decrease in zero-dimensional persistence and each increase in one-dimensional persistence is induced by local minima of the distance function $d$ When $d$ attains local minimum at only finitely many pairs of points, we prove that each above mentioned change in persistence is induced by a specific critical edge in Rips complexes, which represents a local minimum of $d$. We use this fact to develop a theory (including interpretation) of critical edges of persistence. The obtained results include upper bounds for the rank of one-dimensional persistence and a corresponding reconstruction result. Of potential computational interest is a simple geometric criterion recognizing local minima of $d$ that induce a change in persistence. We conclude with a proof that each locally isolated minimum of $d$ can be detected through persistent homology with selective Rips complexes. The results of this paper offer the first interpretation of critical scales of persistent homology (obtained via Rips complexes) for general compact metric spaces.
Keywords: persistent homology, Rips complex, critical simplex, reconstruction result
Published in DiRROS: 10.04.2024; Views: 312; Downloads: 226
.pdf Full text (579,74 KB)
This document has many files! More...

477.
Does age matter? : The well-being of migrant children in comparative perspective
Zorana Medarić, Barbara Gornik, 2024, original scientific article

Abstract: This article explores the subjective perceptions of well-being of migrant children attending primary school (9-14 years) and secondary school (15-18 years) in Slovenia. It focuses on how they conceptualise their fears, worries and concerns, what is important for them to feel accepted and safe, and how they think about their past and the future. Using a comparative perspective, similarities and differences in the experience of well-being of these two age groups of migrants are explored. The analysis is based on open-ended narrative interviews with migrant children and revolves around the question of whether and how age influences their subjective perception of well-being. The article sheds light on age-specific meanings and understandings of migration processes based on the views and experiences of migrant children and youth regarding their well-being, bringing to the fore the perspectives of children that are often missing or underrepresented in integration policy.
Keywords: acceptance, agency, well-being, age differences, migrant children
Published in DiRROS: 09.04.2024; Views: 253; Downloads: 78
.pdf Full text (262,01 KB)
This document has many files! More...

478.
Corrosion behaviour of additively manufactured metallic materials
Aleksandra Kocijan, 2024, review article

Keywords: additive manufacturing, corrosion, steel, Inconel 625, FeMn alloy
Published in DiRROS: 09.04.2024; Views: 342; Downloads: 115
.pdf Full text (579,23 KB)
This document has many files! More...

479.
Researching the change in the weight of split oak firewood due to different drying methods
Amina Gačo, 2021, published scientific conference contribution

Abstract: In this paper, the influences of stacking methods and drying places of split oak firewood in winter conditions (Quercus cerris) have been experimentally and theoretically investigated, due to the great importance of use in heating with such wood. The research was conducted on a sample of 48 pieces of logs with bark made of freshly cut oak. The logs were obtained by mechanized technology with the help of grafting by a hydraulic splitter and a chainsaw. Each log was measured for a research length of 0.30 m, marked with numbers 1-24. On each log, the weight was measured on a scale of 5 kg with an accuracy of 0.5 grams. Drying of logs was performed in two places. The first drying place was in outdoor conditions, sheltered from the snow and ventilated. The second place was indoors, at approximately constant room temperature. The logs were stacked in a crossed way for better air circulation. They were dried between 15/12/2020 and 15/02/2021, a total of 62 days. The average initial weight of logs dried in the facility was 1130.3 g, in the dried state the average weight was 952.87 g, which represented 84.3% of the original weight. The average initial weight of logs dried in outdoor conditions was 1192.125 g, in the dried state 1076.37 g, which represented 90.29% of the original weight. The average initial water content in the logs dried in the facility was 37.9%, in the dried state it was 27.5%. For logs dried in outdoor conditions, the average initial amount of water was 36.6%, in the dried state the average amount of water was 31.2%.
Keywords: weight, drying methods, splitting firewood, oak, stacking methods
Published in DiRROS: 09.04.2024; Views: 563; Downloads: 403
.pdf Full text (871,77 KB)
This document has many files! More...

480.
Search done in 0.66 sec.
Back to top