1. Računalniška simulacija proizvodnje vodika s parnim reformiranjem etanola za uporabo v trdno oksidnih gorivnih celicah : magistrsko deloNežka Brunec, 2025, magistrsko delo Opis: V magistrskem delu je prikazana uporaba energije vodika kot goriva za tehnologijo sistemov trdno oksidnih gorivnih celic (SOFC). Obravnavan je proces pridobivanja vodika po reakcijah parnega reformiranja etanola v napravi reformer. Izvedena je implementacija kemijskih reakcij z uporabo programskega vmesnika AVL User Coding Interface (AUCI). Izdelan kinetični model je uporabljen v komponenti katalitični pretvornik za 1D model reformerja v programskem paketu AVL CRUISE™ M. Izvedena je simulacija modela reformerja, kjer so opazovani vplivi temperature in razmerja pare proti etanolu (razmerje S/E) na proces parnega reformiranja etanola. Iz rezultatov je razvidno, da ima največji vpliv na nastanek najvišje koncentracije vodika povišana temperatura ter nižje razmerje S/E, kar velja za najboljše termodinamične pogoje procesa parnega reformiranja etanola. Model reformerja je validiran, pri čemer se rezultati simulacije dobro ujemajo z referenčnimi podatki. Izdelan model reformerja je uporabljen v študiji delovanja 1D modela sistema SOFC, pri čemer je reformer integriran v prenosniku toplote na vstopu v anodno stran sklada SOFC. Izdelan model sistema SOFC na gorivo etanol deluje stabilno ter prikazuje realno stanje obnašanja sistema. Uporabnost računalniških simulacij v procesu razvoja tehnologije kot je SOFC, je dodatno prikazana s primerjavo delovanja sistema SOFC na gorivo metan, etanol, metanol in amonijak, pri čemer je možno izbirati ukrepe optimizacije in možne korake izboljšanja delovanja sistemov.
Ključne besede: vodikovo gospodarstvo, parno reformiranje etanola, sistem trdno oksidnih gorivnih celic, modeliranje, računalniška simulacija
Objavljeno v DKUM: 27.05.2025; Ogledov: 0; Prenosov: 15
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2. Razvoj modela za napovedovanje odjema toplote v sistemu daljinskega ogrevanja z uporabo umetne inteligence : magistrsko deloPatrik Jakopiček, 2025, magistrsko delo Opis: Magistrsko delo obravnava razvoj različnih modelov globokih nevronskih mrež za napovedovanje odjema toplote v sistemu daljinskega ogrevanja. Razviti so bili trije napovedni modeli, pri čemer ima vsak svoje prednosti in slabosti. Predstavljen je celoten postopek razvoja – od zbiranja in urejanja podatkov, izbire ustreznih slojev in arhitekture nevronskih mrež, do določitve hiperparametrov učenja. Za vsako kombinacijo modelov so prikazane tudi metrične napake. Poleg tega so ocenjeni prihranki oziroma dodatni stroški ob uporabi posameznih napovedi. Rezultati so pokazali, da razviti modeli v nekaterih primerih podajo boljšo napoved od trenutno uporabljenega sistema napovedovanja in z njimi lahko prispevamo k optimizaciji stroškov. V primerih, kjer zaostajajo, pa nam razviti modeli ponujajo dobro izhodišče za nadaljnji razvoj in izboljšave.
Ključne besede: daljinski sistem ogrevanja, globoko učenje, LSTM, programsko napovedovanje
Objavljeno v DKUM: 27.05.2025; Ogledov: 0; Prenosov: 21
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3. The numerical analysis of flame stability in case of premixed hydrogen-air combustionMarc Jaeger, Matjaž Hriberšek, Niko Samec, Yang Guo, Xuebin Wang, Filip Kokalj, 2025, izvirni znanstveni članek Opis: This study addresses the urgent need for decarbonization of heating sector, focusing on the potential of hydrogen-air combustion in gas condensing boilers. In the field of gas condensing boilers, groups of holes or slits can be used in perforated burner surfaces, providing a possible solution to the challenge of hydrogen air combustion. Real burners are always adjacent to an area with non-existent combustion, which can lead to a disturbed flame pattern. For this reason, a comparison between single-slit and multi-slit perforated flame holders with a significantly reduced structure temperature with a hydrogen-air premix is carried out as part of this study. Using Ansys Fluent, a 2D simulation approach is employed to analyze laminar flame stability behind a perforated flame holder. Inlet conditions consider fully premixed and homogenous distributed mixtures as well as nonhomogeneous premixed mixtures, with variations in pressure, velocity, and mixing degree. The model examines various slit-burner configurations and flashback behaviors based on an actual geometric shape used in a gas heating device. It has been found that with finite multi-slit burners, the bulk flow rates at the critical flashback point are 30–50% higher compared to infinitely symmetrical burners. A further deterioration of 32% is to be expected due to real mixture quality fluctuations and inhomogeneous inflow conditions. Finally, the findings demonstrate the model’s potential for designing efficient surface-stabilized burners and lay the groundwork for future 3D simulations in the pursuit of sustainable heating solutions.
Ključne besede: hydrogen combustion, flashback, flame stability, perforated flame holder, gas condensing boiler
Objavljeno v DKUM: 19.05.2025; Ogledov: 0; Prenosov: 3
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4. Towards circularity in Serbian mining: unlocking the potential of flotation tailings and fly ashNela Vujović, Vesna Alivojvodić, Dragana Radovanović, Marija Štulović, Miroslav Sokić, Filip Kokalj, 2025, izvirni znanstveni članek Opis: This paper examines sustainable industrial practices in Serbia, particularly in the mining and energy sector, focusing on the potential of flotation tailings and fly ash, as materials with the largest share in disposed waste in Serbia in 2023 (95%). It highlights the environmental challenges of mining waste and explores innovative approaches to waste management within the circular economy framework. The study analyzes the current state of mining waste in Serbia, particularly in copper mining regions in the east of the country. It discusses the potential for metal recovery from waste and its reuse in various industries. The research also investigates the use of fly ash from thermal power plants as a valuable resource in the construction industry and other sectors. The paper reviews existing initiatives and legislation in Serbia in order to promote sustainable mining practices and waste utilization. By presenting case studies and potential applications, the study demonstrates how implementing circular economy principles in the mining sector can contribute to environmental protection, resource conservation, and economic growth in Serbia. The comprehensive overview of the current state in Serbia provides a solid foundation for establishing a higher degree of circularity in the mining and energy sectors.
Ključne besede: mining, flotation tailings, fly ash, Serbia, circular economy
Objavljeno v DKUM: 17.03.2025; Ogledov: 0; Prenosov: 6
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5. Simple method for measuring and mapping of site-specific draft force during plowing : Elektronski virVojislav Simonović, Emil Veg, Miloš Milošević, Dragan Milković, Filip Jerenec, Nenad Gubeljak, 2024, izvirni znanstveni članek Opis: This paper presents and analyzes the procedure for indirect measurement of soil mechanical properties using strain transducers installed on the lower links of the tractor and corresponding acquisition equipment, along with simultaneous use of the tractor unit positioning equipment in the field during tillage operation with a two-furrow plough. Sensors are installed and calibrated according to measurement requirements and after the Finite Element Method (FEM) analysis of the tractor lower links. The results obtained for the draft force longitudinal measurements are well consistent with expected results predicted by using the Goryachkin approach and ASAE Standard D497.4. The presented method can be successfully applied to measure the draft force when performing any other operation in the field. Maps produced by measuring the draft force are very useful in precision seeding in terms of varying seeding depth or soil amelioration. Such maps can be a useful layer in any other decision-making considerations in precision agriculture.
Ključne besede: draft force, lower links, plowing, strain transducer
Objavljeno v DKUM: 17.03.2025; Ogledov: 0; Prenosov: 8
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6. Increased planting speed did not affect silage and grain yield of maize, while saving seed and energyFilip Vučajnk, Igor Šantavec, Darja Kocjan Ačko, Jurij Rakun, Jože Verbič, Rajko Bernik, Stanislav Trdan, Matej Vidrih, 2020, izvirni znanstveni članek Opis: Optimal planting speed of vacuum maize planters is usually suggested by planter’s manufacturers, while increased planting speed may influence plant spacing and finally yield. Our hypothesis was that by increasing planting speed over the suggested level plant spacing variability will also increase which will result in decrease of silage and grain yield and saving of seed and energy. The field trial consisted of three planting speeds of 7, 9 and 11 km/h in the form of random blocks. The following measurements were taken as follows: plant spacing, silage and grain yield, fuel and energy use at planting. Results in this study show that planting speed did not have significant influence on silage and grain yield of maize, while up to 10% less seed was needed per hectare and fuel and energy use was lower for 15%. By the increase of planting speed the distance between the plants in a row, and in most cases also the plant spacing variability increased. It was noticed that by increasing planting speed plant density decreased. This research established that at higher planting speeds significant increase of the silage yield per individual plant and of the grain yield per individual plant was achieved. The ear parameters also show that the kernel mass per individual ear, the ear mass, and the cob mass, as well as the individual kernel mass, are larger at the planting speed of 11 km/h than at the planting speed of 7 km/h. At the latter planting speed, significantly higher fuel consumption per hectare and higher energy use was achieved than at the other two planting speeds. Overall the main benefits of planting speed of 11 km/h is saving seed and energy at planting while maintaning the same level of silage and grain yield compared to lower planting speeds used in the trial.
Ključne besede: energy use, grain yield, maize, planting speed, plant spacing, seed savings, silage yield, vacuum planter
Objavljeno v DKUM: 11.03.2025; Ogledov: 0; Prenosov: 4
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7. Enhancing utilization of municipal solid waste bottom ash by the stabilization of heavy metalsFilip Kokalj, Vesna Alivojvodić, Luka Lešnik, Nela Petronijević, Dragana Radovanović, Niko Samec, 2025, izvirni znanstveni članek Opis: Waste-to-energy (WtE) is a key part of modern waste management. In the European Union, approximately 500 WtE plants process more than 100 million tons of waste yearly, while globally, more than 2700 plants handle over 500 million tons. Roughly 20% of the waste processed is bottom ash (BA). However, this ash can contain heavy metals in concentrations that may render it hazardous. This paper presents a study focusing on stabilizing municipal solid waste incineration BA using simple and industrially viable treatments. The Slovenian WtE plant operator wishes to install the stabilization process; thus, the samples obtained from the plant were treated (1) with a CO2 gas flow, (2) with water spraying, and (3) with a combination of water spraying and a CO2 gas flow under laboratory conditions. Thermodynamic calculations were applied to define potential reactions during the treatment processes in the temperature range from 0 to 100 ◦C and to define the equilibrium composition of the treated ash with additions of CO2 and water. The standard leaching test EN 12457-4 of treated ash shows a reduction of over 40% in barium concentration and over 30% in lead concentration in leachates.
Ključne besede: heavy metals, waste-to-energy, bottom ash, leachate, reuse
Objavljeno v DKUM: 10.03.2025; Ogledov: 0; Prenosov: 8
Celotno besedilo (2,72 MB)
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8. Razvoj 3D resne igre za prepoznavanje kroničnih bolezni z algoritmom iskanja najkrajše potiFilip Senekovič, 2025, diplomsko delo Opis: Diplomsko delo opisuje razvoj 3D resne igre za prepoznavanje kroničnih bolezni. V igri ima igralec vlogo pacienta in raziskuje stanovanje ter prepoznava vzroke in simptome kroničnih bolezni. V diplomskem delu se osredotočamo na oblikovanje igralca in scene, interakcijo igralca s sceno ter navigacijo z uporabo algoritma iskanja najkrajše poti. Cilj je ponuditi interaktivno učenje o kroničnih boleznih in poudariti pomen pravočasnega prepoznavanja simptomov ter sprememb življenjskih navad. Rezultati testiranja kažejo, da je izdelana igra dostopna širšemu občinstvu, saj dobro deluje tudi na manj zmogljivih računalnikih. Poleg tega je algoritem iskanja najkrajše poti zmožen igralca v realnem času učinkovito voditi skozi sceno.
Ključne besede: kronične bolezni, resna igra, Unity, algoritem iskanja najkrajše poti
Objavljeno v DKUM: 04.03.2025; Ogledov: 0; Prenosov: 52
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10. Survey of inter-prediction methods for time-varying mesh compressionJan Dvořák, Filip Hácha, Gerasimos Arvanitis, David Podgorelec, Konstantinos Moustakas, Libor Váša, 2025, izvirni znanstveni članek Opis: Time-varying meshes (TVMs), that is mesh sequences with varying connectivity, are a greatly versatile representation of shapesevolving in time, as they allow a surface topology to change or details to appear or disappear at any time during the sequence.This, however, comes at the cost of large storage size. Since 2003, there have been attempts to compress such data efficiently. Whilethe problem may seem trivial at first sight, considering the strong temporal coherence of shapes represented by the individualframes, it turns out that the varying connectivity and the absence of implicit correspondence information that stems from itmakes it rather difficult to exploit the redundancies present in the data. Therefore, efficient and general TVM compression is stillconsidered an open problem. We describe and categorize existing approaches while pointing out the current challenges in thefield and hint at some related techniques that might be helpful in addressing them. We also provide an overview of the reportedperformance of the discussed methods and a list of datasets that are publicly available for experiments. Finally, we also discusspotential future trends in the field.
Ključne besede: compression algorithms, data compression, modelling, polygonal mesh reduction
Objavljeno v DKUM: 07.02.2025; Ogledov: 0; Prenosov: 2
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