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1.
Comparative analysis of synchronous motors
Vasilija Sarac, Goce Stefanov, Dragan Minovski, 2021, izvirni znanstveni članek

Opis: This paper compares the parameters, steady-state and transient characteristics of two different types of synchronous motors (SM) – a motor with surface mounted magnets on the rotor, and a motor with embedded magnets and squirrel cage winding, widely known as a line-start synchronous motor. The comparison is based on results obtained from analytical, numerical and transient models of both motors for the same output power of the motors. The models for obtaining transient characteristics allow comparison of acceleration of both motors taking into consideration that the line-start SM is a self-starting motor while the SM with surface magnets is always started with the aid of a PWM inverter. The results obtained from the analytical, numerical and transient models of the motors should assist in choosing the most cost-effective solution in terms of the type of the motor for the appropriate application.
Ključne besede: FEM models, synchronous motors, steady-state characteristics, transient characteristics
Objavljeno v DKUM: 13.11.2023; Ogledov: 79; Prenosov: 2
.pdf Celotno besedilo (727,90 KB)
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2.
String Universality and Non-Simply-Connected Gauge Groups in 8D
Mirjam Cvetič, Markus Dierigl, Ling Lin, Hao Y. Zhang, 2020, izvirni znanstveni članek

Opis: We present a consistency condition for 8D N 1 supergravity theories with nontrivial global structure G=Z for the non-Abelian gauge group, based on an anomaly involving the Z 1-form center symmetry. The interplay with other swampland criteria identifies the majority of 8D theories with gauge group G=Z, which have no string theory realization, as inconsistent quantum theories when coupled to gravity. While this condition is equivalent to geometric properties of elliptic K3 surfaces in F-theory compactifications, it constrains the unexplored landscape of gauge groups in other 8D string models.
Ključne besede: supergravity theories, string theory, 8D string models
Objavljeno v DKUM: 16.10.2023; Ogledov: 110; Prenosov: 3
.pdf Celotno besedilo (207,17 KB)
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3.
Conformal symmetries for extremal black holes with general asymptotic scalars in STU supergravity
Mirjam Cvetič, Christopher N. Pope, Aritra Saha, 2021, izvirni znanstveni članek

Opis: We present a construction of the most general BPS black holes of STU supergravity (N = 2 supersymmetric D = 4 supergravity coupled to three vector supermultiplets) with arbitrary asymptotic values of the scalar fields. These solutions are obtained by acting with a subset of the global symmetry generators on STU BPS black holes with zero values of the asymptotic scalars, both in the U-duality and the heterotic frame. The solutions are parameterized by fourteen parameters: four electric and four magnetic charges, and the asymptotic values of the six scalar fields. We also present BPS black hole solutions of a consistently truncated STU supergravity, which are parameterized by two electric and two magnetic charges and two scalar fields. These latter solutions are significantly simplified, and are very suitable for further explicit studies. We also explore a conformal inversion symmetry of the Couch-Torrence type, which maps any member of the fourteen-parameter family of BPS black holes to another member of the family. Furthermore, these solutions are expected to be valuable in the studies of various swampland conjectures in the moduli space of string compactifications.
Ključne besede: black holes, extended supersymmetry, supergravity models, string theory
Objavljeno v DKUM: 16.10.2023; Ogledov: 51; Prenosov: 8
.pdf Celotno besedilo (636,89 KB)
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4.
Statistics of limit root bundles relevant for exact matter spectra of F-theory MSSMs
Martin Bies, Mirjam Cvetič, Mingqiang Liu, 2021, izvirni znanstveni članek

Opis: In the largest, currently known, class of one quadrillion globally consistent F-theory Standard Models with gauge coupling unification and no chiral exotics, the vectorlike spectra are counted by cohomologies of root bundles. In this work, we apply a previously proposed method to identify toric base threefolds, which are promising to establish F-theory Standard Models with exactly three quark doublets and no vectorlike exotics in this representation. The base spaces in question are obtained from triangulations of 708 polytopes. By studying root bundles on the quark-doublet curve Cð3;2Þ1=6 and employing well-known results about desingularizations of toric K3 surfaces, we derive a triangulation independent lower bound Nˇ ð3Þ P for the number Nð3Þ P of root bundles on Cð3;2Þ1=6 with exactly three sections. The ratio Nˇ ð3Þ P =NP, where NP is the total number of roots on Cð3;2Þ1=6 , is largest for base spaces associated with triangulations of the eighth three-dimensional polytope Δ∘ 8 in the Kreuzer-Skarke list. For each of these Oð1015Þ threefolds, we expect that many root bundles on Cð3;2Þ1=6 are induced from F-theory gauge potentials and that at least every 3000th root on Cð3;2Þ1=6 has exactly three global sections and thus no exotic vectorlike quark-doublet modes.
Ključne besede: astrophysics, compactification, string theory models, geometry, higher-dimensional field theories, mathematical physics, quantum fields in curved spacetime, string phenomenology, supersymmetric models, topology
Objavljeno v DKUM: 16.10.2023; Ogledov: 60; Prenosov: 3
.pdf Celotno besedilo (444,13 KB)
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5.
Artificial intelligence based prediction models for individuals at risk of multiple diabetic complications : a systematic review of the literature
Lucija Gosak, Kristina Martinović, Mateja Lorber, Gregor Štiglic, 2022, pregledni znanstveni članek

Opis: Aim The aim of this review is to examine the effectiveness of artificial intelligence in predicting multimorbid diabetes-related complications. Background In diabetic patients, several complications are often present, which have a significant impact on the quality of life; therefore, it is crucial to predict the level of risk for diabetes and its complications. Evaluation International databases PubMed, CINAHL, MEDLINE and Scopus were searched using the terms artificial intelligence, diabetes mellitus and prediction of complications to identify studies on the effectiveness of artificial intelligence for predicting multimorbid diabetes-related complications. The results were organized by outcomes to allow more efficient comparison. Key issues Based on the inclusion/exclusion criteria, 11 articles were included in the final analysis. The most frequently predicted complications were diabetic neuropathy (n = 7). Authors included from two to a maximum of 14 complications. The most commonly used prediction models were penalized regression, random forest and Naïve Bayes model neural network. Conclusion The use of artificial intelligence can predict the risks of diabetes complications with greater precision based on available multidimensional datasets and provides an important tool for nurses working in preventive health care. Implications for Nursing Management Using artificial intelligence contributes to a better quality of care, better autonomy of patients in diabetes management and reduction of complications, costs of medical care and mortality.
Ključne besede: artificial intelligence, prediction models, diabetes, prediction of diabetes complications
Objavljeno v DKUM: 03.10.2023; Ogledov: 101; Prenosov: 18
.pdf Celotno besedilo (509,07 KB)
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6.
Recent advances in the development of automotive catalytic converters: a systematic review
Laura Robles-Lorite, Ruben Dorado Vicente, Eloisa Torres Jiménez, Gorazd Bombek, Luka Lešnik, 2023, pregledni znanstveni članek

Opis: Despite the current boost in the use of electric vehicles to reduce the automotive sector’s footprint, combustion vehicles are and will be present in our cities in both the immediate and long term. In this sense, catalytic converters, which are exhaust gas post-treatment systems for vehicle emission control, are critical for complying with increasingly stringent environmental regulations. This work proposes a systematic review to identify the most relevant knowledge regarding the parameters (materials, geometries, and engine conditions), conditions (cold start, oxygen storage, and deactivation), and mathematical models to consider in the design of catalytic converters. The Scopus database contains 283 records related to this review’s objective. After applying the inclusion and exclusion criteria, 65 reports were retrieved for evaluation. A table was created to present the results and prepare this manuscript. The evaluation revealed that the following topics were active: the study of non-noble catalyst materials, as well as new substrate materials and geometries, for designing more compact and cost-effective catalytic converters; the development of strategies to improve conversion during cold starts; and the development of accurate and fast estimation models.
Ključne besede: automotive converters, catalytic converters, emissions reduction, exhaust gas post-treatment, catalyst deactivation, oxygen storage, numerical models
Objavljeno v DKUM: 06.09.2023; Ogledov: 139; Prenosov: 11
.pdf Celotno besedilo (532,89 KB)
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7.
6th International Conference on Technologies & Business Models for Circular Economy : book of abstracts
2023

Opis: The 6th International Conference on Technologies & Business Models for Circular Economy (TBMCE) was organized by the Faculty of Chemistry and Chemical Engineering, University of Maribor in collaboration with the Strategic Research and Innovation Partnership - Networks for the Transition into Circular Economy (SRIP- Circular Economy), managed by the Chamber of Commerce and Industry of Štajerska. The conference was held in Portorož, Slovenia, at the Grand Hotel Bernardin from September 6th to September 8th, 2023. The Netherlands joined us as a partner country of the conference. TBMCE 2023 was devoted to presentations of circular economy concepts, technologies and methodologies that contribute to the shift of business entities and society as a whole to a more responsible, circular management of resources. The conference program included panel discussions, plenary and keynote sessions, oral and poster presentations on the following topics: Sustainable energy, Biomass and alternative raw materials, Circular business models, Secondary raw materials and functional materials, ICT in Circular Economy, Processes and technologies. Panel discussions addressed following topics: Capture, storage or conversion of CO2 or H2?, The potential of small scale biorefining, Circular economy in construction – myth or real opportunity?, Importance of circular communities in international arena, Sector Coupling: pathways to integrated energy systems, Combating water pollution by plastic waste. The event was
Ključne besede: circular economy, sustainable development, processes and technologies, circular business models, research and development
Objavljeno v DKUM: 01.09.2023; Ogledov: 153; Prenosov: 28
.pdf Celotno besedilo (3,06 MB)
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8.
Towards an adaptive strategic IT governance model for SMEs
Aleš Levstek, Andreja Pucihar, Tomaž Hovelja, 2022, izvirni znanstveni članek

Opis: Information technology (IT) can have a direct and indirect impact on business performance. New technologies change the risks at the strategic and governing levels of an enterprise. In the age of digitalization, we need to develop new understandings and approaches to governance and management. The most established IT governance (ITG) models, such as COBIT, ITIL and CMMI, are universal, one-size-fits-all models that are not in line with contingency theory and are predominantly designed for large multinational enterprises. They are too cumbersome and cost-intensive for small and medium enterprises (SMEs) to use effectively. Therefore, there is a need to develop more efficient models that are contingency-based and easier to implement than existing models and thus adaptable to the actual needs of the business. This paper presents an empirical evaluation of key ITG mechanisms from the literature that clearly shows that several are not universally but situationally necessary, thus demonstrating the need for new contingency-based ITG models.
Ključne besede: upravljanje informatike, mehanizmi upravljanja informatike, modeli upravljanja informatike, prilagodljiv model upravljanja informatike, IT governance, IT governance mechanisms, IT governance models, contingency IT governance model
Objavljeno v DKUM: 12.07.2023; Ogledov: 183; Prenosov: 27
.pdf Celotno besedilo (2,34 MB)
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9.
Using different surface energy models to assess the interactions between antiviral coating films and phi6 model virus
Zdenka Peršin Fratnik, Olivija Plohl, Vanja Kokol, Lidija Fras Zemljič, 2023, izvirni znanstveni članek

Opis: High molecular weight chitosan (HMWCh), quaternised cellulose nanofibrils (qCNF), and their mixture showed antiviral potential in liquid phase, while this effect decreased when applied to facial masks, as studied in our recent work. To gain more insight into material antiviral activity, spin-coated thin films were prepared from each suspension (HMWCh, qCNF) and their mixture with a 1:1 ratio. To understand their mechanism of action, the interactions between these model films with various polar and nonpolar liquids and bacteriophage phi6 (in liquid phase) as a viral surrogate were studied. Surface free energy (SFE) estimates were used as a tool to evaluate the potential adhesion of different polar liquid phases to these films by contact angle measurements (CA) using the sessile drop method. The Fowkes, Owens–Wendt–Rabel–Kealble (OWRK), Wu, and van Oss–Chaudhury–Good (vOGC) mathematical models were used to estimate surface free energy and its polar and dispersive contributions, as well as the Lewis acid and Lewis base contributions. In addition, the surface tension SFT of liquids was also determined. The adhesion and cohesion forces in wetting processes were also observed. The estimated SFE of spin-coated films varied between mathematical models (26–31 mJ/m2) depending on the polarity of the solvents tested, but the correlation between models clearly indicated a significant dominance of the dispersion components that hinder wettability. The poor wettability was also supported by the fact that the cohesive forces in the liquid phase were stronger than the adhesion to the contact surface. In addition, the dispersive (hydrophobic) component dominated in the phi6 dispersion, and since this was also the case in the spin-coated films, it can be assumed that weak physical van der Waals forces (dispersion forces) and hydrophobic interactions occurred between phi6 and the polysaccharide films, resulting in the virus not being in sufficient contact with the tested material during antiviral testing of the material to be inactivated by the active coatings of the polysaccharides used. Regarding the contact killing mechanism, this is a disadvantage that can be overcome by changing the previous material surface (activation). In this way, HMWCh, qCNF, and their mixture can attach to the material surface with better adhesion, thickness, and different shape and orientation, resulting in a more dominant polar fraction of SFE and thus enabling the interactions within the polar part of phi6 dispersion.
Ključne besede: films, surface free energy, SFE mathematical models, phi6, wettability, spreading, interactions
Objavljeno v DKUM: 21.04.2023; Ogledov: 274; Prenosov: 16
.pdf Celotno besedilo (3,21 MB)

10.
5th International Conference on Technologies & Business Models for Circular Economy : Conference Proceedings
2023

Opis: The 5th International Conference on Technologies & Business Models for Circular Economy (TBMCE) was organized by the Faculty of Chemistry and Chemical Engineering, University of Maribor in cooperation with the Chamber of Commerce and Industry of Štajerska and SRIP- Circular Economy. The conference was held in Portorož, Slovenia, at the Grand Hotel Portorož from September 12th to September 14th, 2022. TBMCE 2022 was devoted to presentations of circular economy concepts, technologies and methodologies that contribute to the shift of business entities and society as a whole to a more responsible, circular management of resources. The conference program included a round table: Asia – factory of the world, what about the EU?, 4 panel discussions, 1 plenary and 4 keynote lectures, oral and poster presentations on the following topics: Sustainable energy, Biomass and alternative raw materials, Circular business models, Secondary raw materials and functional materials, ICT in Circular Economy, Processes and technologies. The event was under the honorary patronage of Mr. Matjaž Han, Minister of Economic Development and Technology.
Ključne besede: circular economy, sustainable development, processes and technologies, circular business models, research and development
Objavljeno v DKUM: 30.01.2023; Ogledov: 307; Prenosov: 20
.pdf Celotno besedilo (4,86 MB)
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