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A multi-level approach to circular economy progress
Get PDFAn integrated top-down methodology for assessing and promoting progress towards a circular economy at macro (national) and micro (company) levels is presented. It is based on the MICRON (MIcroCirculaR ecOnomy iNdex) framework developed by Baratsas et al. (2022) for companies. In this paper, it has been extended to enable a consistent assessment for companies and countries. The methodology facilitates the analysis of key categories: energy, emissions, water, materials, and waste. A quantitative analysis of circularity, including a sensitivity analysis, is conducted at the macro level, identifying critical areas and the most influential factors for the circular economy. Based on this analysis, existing national strategies are evaluated, and implementation plans with specific measures are developed. This is followed by micro-level implementation, which involves techno-economic assessment of circular projects. Using this methodology, coordinated improvements in circularity are achieved at all levels. The methodology was tested in Slovenia, where the national circularity index revealed stable performance over five years, averaging slightly above 50 points out of 100. Analysis identified significant improvement potential in areas such as energy and emissions, aligning with the country\u27s focus on decarbonization and energy efficiency in its climate strategies. At the company level, circularity assessments highlighted critical challenges in renewable energy use and overall energy efficiency. The proposed measures showed potential for significantly improving circularity and reducing emissions, while the results provided valuable insights into the economic feasibility of these transitions
Radiotherapy department supported by an optimization algorithm for scheduling patient appointments
Get PDFPrompt administration of radiotherapy (RT) is one of the most effective treatments against cancer. Eachday, the radiotherapy departments of large hospitals must plan numerous irradiation sessions, con-sidering the availability of human and material resources, such as healthcare professionals and linearaccelerators. With the increasing number of patients suffering from different types of cancers, manuallyestablishing schedules following each patient’s treatment protocols has become an extremely difficultand time-consuming task. We propose an optimization algorithm that automatically schedules andgenerates patient appointments. The model can rearrange fixed appointments to accommodate urgentcases, enabling hospitals to schedule appointments more efficiently. It respects the different treatment Prompt administration of radiotherapy (RT) is one of the most effective treatments against cancer. Eachday, the radiotherapy departments of large hospitals must plan numerous irradiation sessions, con-sidering the availability of human and material resources, such as healthcare professionals and linearaccelerators. With the increasing number of patients suffering from different types of cancers, manuallyestablishing schedules following each patient’s treatment protocols has become an extremely difficultand time-consuming task. We propose an optimization algorithm that automatically schedules andgenerates patient appointments. The model can rearrange fixed appointments to accommodate urgentcases, enabling hospitals to schedule appointments more efficiently. It respects the different treatment
The approach of using a horizontally layered soil model for inhomogeneous soil, by taking into account the deeper layers of the soil, and determining the model’s parameters using evolutionary methods
Get PDFA new approach using a horizontally layered analytical soil model for inhomogeneous soil is presented. The presented approach also considers deeper soil layers, which is not the case when simply dividing the area of interest into smaller subareas. The finite element method model was used to prepare test data because, in such a case, the soil parameters are known. Six lines simulating Wenner’s method were used, and their results were combined appropriately to determine the soil parameters of nine subareas. To determine the soil parameters in the scope of each subarea, different optimization methods were used and compared to each other. The results were analyzed, and Artificial Bee Colony was selected as the most appropriate method among those tested. Additionally, the convergence of the methods was analyzed, and Memory Assistance is presented, with the aim of shortening the calculation time. In this study, three-, four-, five-, and six-layered soil models were tested, and it is concluded that the three-layered model is most appropriate. A finite element method model based on the soil determination results was constructed to verify the results. The results of the Wenner’s method simulation in the cases of the test data and final model were compared to confirm the accuracy of the presented metho
Parametric modeling of a dryer heat exchanger
Get PDFNamen zaključnega dela je razvoj generičnega 3D modela toplotnega izmenjevalca v Siemens NX, ki se uporablja v podjetju Gorenje za razvoj sušilnikov. V uvodu so opisane vrste sušilnikov: ventilacijski, kondenzacijski in s toplotno črpalko. Osrednji del naloge prikazuje postopek modeliranja ključnih komponent, kot so cevni sistemi, lamele in sestavne plošče. Zaključek obravnava parametrično modeliranje z uporabo izrazov in relacij za prilagajanje dimenzij. Prikazane so različne konfiguracije, uporabljene med testiranjem. Rezultat je prilagodljiv model za hitro izdelavo variant glede na zahteve.This thesis focuses on developing a generic 3D model of a heat exchanger in Siemens NX, used by Gorenje for designing clothes dryers. It begins with an overview of vented, condenser, and heat pump dryers and their operating principles. The core section details the modeling of key heat exchanger components, such as pipes, fins, and end plates. Emphasis is placed on parametric modeling, enabling easy adjustment of dimensions and element counts. The final part presents various tested configurations. The outcome is a flexible, adaptable model that supports efficient creation of multiple heat exchanger variants for product development
The impact of climate change on emerging security challenges
Get PDFDiplomsko delo obravnava vpliv podnebnih sprememb na nove varnostne izzive s poudarkom na podnebnih konfliktih in migracijah. Podnebne spremembe povzročajo pomanjkanje naravnih virov (voda, hrana, energija), kar povečuje družbene napetosti in tveganje za konflikte. Mednarodni odzivi, kot sta Kjotski protokol in Pariški sporazum, določajo cilje za zmanjšanje emisij toplogrednih plinov, krepitev odpornosti držav in vključevanje podnebnih ukrepov v varnostne strategije. Študija primera Sirije prikazuje, kako dolgotrajne suše, zmanjšanje vodnih zalog in degradacija zemlje, skupaj z omejitvami pretoka Evfrata iz Turčije, slabšajo kmetijsko proizvodnjo, povzročajo migracije s podeželja v mesta in poglabljajo humanitarno krizo. To prispeva k nestabilnosti in otežuje obnovo države. Drugi primer, Bangladeš, ponazarja vpliv dviga morske gladine in pogostih poplav, ki uničujejo obdelovalne površine, povzročajo notranje in čezmejne migracije ter obremenjujejo infrastrukturo in socialne sisteme sosednjih držav. Podnebne migracije tako predstavljajo izziv za varnost, gospodarstvo in politično stabilnost regij. Delo poudarja, da so podnebni varnostni izzivi večplastni. Od povečanja konfliktov zaradi tekmovanja za vire, pritiska na urbane centre, socialnih nemirov do ogrožanja prehranske in energetske varnosti. Reševanje zahteva povezovanje humanitarnih, razvojnih in podnebnih ukrepov, krepitev mednarodnega sodelovanja, vlaganje v obnovljive vire energije in trajnostno upravljanje z naravnimi viri. Povezovanje podnebnih in varnostnih strategij je ključno za zmanjšanje tveganj in zaščito ranljivih skupnosti po svetu.The thesis examines the impact of climate change on emerging security challenges, focusing on climate-related conflicts and migrations. Climate change causes shortages of essential natural resources (water, food, energy), which heightens social tensions and increases the risk of conflicts. International responses, such as the Kyoto Protocol and the Paris Agreement, set targets for reducing greenhouse gas emissions, strengthening state resilience, and integrating climate measures into security strategies. The case study of Syria shows how prolonged droughts, reduced water supplies, and land degradation, combined with restricted flows of the Euphrates from Turkey, undermine agricultural production, drive rural populations into cities, and deepen the humanitarian crisis. These dynamics contribute to instability and hinder national recovery. The case of Bangladesh illustrates the effects of sea level rise and frequent flooding, which destroy farmland, cause internal and cross-border migration, and strain the infrastructure and social systems of neighboring countries. Climate migration thus poses significant challenges to regional security, economies, and political stability. The study highlights that climate security challenges are multifaceted. They include increased conflicts over scarce resources, pressure on urban centers, social unrest, and threats to food and energy security. Addressing these issues requires linking humanitarian, development, and climate actions, strengthening international cooperation, investing in renewable energy sources, and managing natural resources sustainably. Integrating climate and security strategies is essential for reducing risks and protecting vulnerable communities worldwide
Test time augmentation for classification of ECG signals
Get PDFAtrijska fibrilacija je ena najpogostejših in najnevarnejših srčnih aritmij, njena pravočasna identifikacija pa je ključna za preprečevanje resnih zapletov. Kljub razvoju metod strojnega učenja ostaja pomanjkanje kakovostnih in strokovno označenih EKG podatkov, ki jih je težko pridobiti brez kardioloških ekspertov, velik izziv. V zaključnem delu smo zato preučili tehnike umetnega povečanja testnih podatkov, pri katerih model med napovedovanjem obravnava več spremenjenih verzij istega signala. Z eksperimentom, ki je vključeval različne kompleksnosti modelov, pristope učenja in načine odločanja, smo pokazali, da tehnike umetnega povečanja testnih podatkov delno prispevajo k boljši napovedi.Atrial fibrillation is one of the most common and dangerous cardiac arrhythmias, and its timely identification is key to protecting against serious complications. Despite the development of machine learning methods, the lack of high-quality and professionally labeled ECG data, which is difficult to obtain without cardiology experts, remains a major challenge. As part of our final work, we examined artificial augmentation techniques for test data, in which the model considers multiple modified versions of the same signal during prediction. With an experiment that included different model complexities, learning approaches, and decision-making methods, we showed that artificial augmentation techniques for test data partially contribute to better predictions
Exploring the divergent manifestation of corruption within the slovenian healthcare system with regards to centralisation versus decentralisation
Get PDFTo diplomsko delo prispeva k dosedanji znanstveni literaturi o vplivu centralizacije in decentralizacije na koruptivna tveganja, z primerjavo zdravstvenega sistema Slovenije na strukturni ravni, z zdravstvom Avstrije in Švice.
Različnim dimenzijam decentralizacije v praksi (Freille, Haque in Kneller, 2007), predstavimo pravokotni pojav (de)koncentracije (Haček, 2001), za preglednejše orodje pri lociranju koruptivnih tveganj. Decentralizacija se ponovno izkaže za bolj kompleksno kot avtomatski spust koruptivnih aktivnosti.
Aplikacija zgornjega orodja, na dosedanjo literaturo o korupciji v slovenskem zdravstvu (Slak, Loknar, Behram in Dobovšek, 2023), nam prikaže mračno sliko, s katero potrdimo, da nepopolna decentralizacija, ki izpusti ključno fiskalno dimenzijo, le oslabi elemente unitarne ureditve, ki so po naravi le te, bolj odporni korupciji (Freille, Haque in Kneller, 2007). Centralizacija namreč ni vedno le objektivno zlo, zato naj rušenje hierarhij nikoli ni odločeno z lahkim srcem.
Naša glavna kontribucija boju proti korupciji, pa je pregledna komparativna analiza, ki obsega vse tri države, razločene na organe njihovega zdravstvenega sistema, z ogledom na stopnjo centralizacije vseh (prirejeno po Bachner, Bobek, Habimana, Ladurner, Lepuschütz, Ostermann in Winkelmann, 2018).
Transparenca namreč preostaja primarno orodje pri izkoreninjanju koruptivnih akterjev, kar je kritičnega pomena, ko obravnavamo kritično infrastrukturo.This thesis adds to the expanding knowledge base regarding the dynamic link between (de)centralization and corruption, via comparative analysis between healthcare structures of Slovenia, Austria and Switzerland.
We recognize the practical dimensions of decentralization set forth by Freille, Haque in Kneller (2007), however we expand on the framework by acknowledging a perpendicular force of concentration and deconcentration (Haček, 2001), hoping to create a broader view of an institution, to accommodate easier pinpointing of corruption risks. From this expanded field-of-view we can corroborate the inadequacy of the once held bilateral view of (de)centralisation as an easy means to reduce corruption.
Henceforth, this combined framework functioned as a lens to (re)interpret the extensive documentation, compilation and presentation of corruption within Slovenian healthcare by Slak, Loknar, Behram in Dobovšek (2023), resulting in a grim image, that corroborates former research, linking inadequate decentralization, to increased corruption. As Freille, Haque & Kneller (2007) elaborated, their empirical analysis suggests unitarism occasionally proves more resilient to certain forms of corruption, but decentralization, if lacking the crucial fiscal dimension, instead weakened those benefits. The main contribution we hope to provide, is a comparative analysis of structural elements comprising the Slovenian, Austrian and Swiss healthcare, with regards to their level of centralization (adapted from Bachner et al., 2018). Transparency, after all, remains the primary tool in unearthing, and uprooting corrupt elements, which remains of critical importance, especially when dealing with critical infrastructure
Match-Fixing as a form of organized crime
Get PDFV diplomskem delu smo se osredotočili na pojav nameščanja tekem kot obliko organizirane kriminalitete, ki predstavlja eno najresnejših groženj integriteti športa, saj spodkopava načela poštene igre in zmanjšuje vrednost športnega tekmovanja, hkrati pa gledalcem odvzema občutek nepredvidljivosti. Problem se kaže v povezavi med športom in nezakonitimi stavnimi trgi, kjer kriminalne združbe z manipulacijo izidov ustvarjajo velike finančne dobičke. Zaradi globalnega razvoja spletnega stavništva, hitrih denarnih prenosov in pomanjkljivega nadzora se je nameščanje tekem razvilo v čezmejni pojav, ki presega okvire posameznih držav. Namen raziskave je bil analizirati razloge, oblike in posledice tega pojava ter preučiti odzive pravosodnih organov in športnih organizacij. Posebna pozornost je bila namenjena pravnemu okviru v Sloveniji ter preventivnim mehanizmom, ki jih razvijajo nacionalne in mednarodne športne institucije. V teoretičnem delu smo najprej predstavili razumevanje pojma nameščanja tekem in ga opredelili kot zavestno manipulacijo športnih izidov zaradi pridobitve protipravne koristi. Poudarili smo, da so kriminalne mreže pri tem zelo prilagodljive, delujejo večnivojsko in izkoriščajo ranljivosti akterjev, kot so športniki, sodniki in klubsko osebje. Ti se pogosto znajdejo v finančnih težavah, so izpostavljeni neizplačanim plačam ali pa postanejo žrtve odvisnostnih razmerij, izsiljevanja in groženj. V empiričnem delu smo s pomočjo študij primerov analizirali konkretne afere, med drugim Asiagate v Zimbabveju, kriket škandal s Hansiejem Cronjejem ter afero namiznoteniških tekem v Ukrajini. Na podlagi teh primerov je bilo prikazano, kako se kriminalne mreže povezujejo s športnimi akterji, katere metode uporabljajo pri manipulaciji izidov in kakšne so bile sankcije za vpletene od disciplinskih ukrepov športnih organizacij do denarnih kazni in zapornih kazni v kazenskih postopkih. Mednarodne institucije so vzpostavile različne mehanizme za odkrivanje in preprečevanje manipulacij, a pregon ostaja otežen zaradi prikritosti dejanj, pomanjkanja dokazov in globalne narave stavniških trgov. Glavni namen diplomskega dela je bil opozoriti na nevarnosti, ki jih nameščanje tekem predstavlja za šport in širšo družbo, ter prispevati k ozaveščanju o potrebi po učinkovitejšem sodelovanju med športnimi organizacijami, državnimi organi in mednarodnimi institucijami pri preprečevanju tega pojava.In this thesis, we focused on the phenomenon of match-fixing as a form of organized crime, which represents one of the most serious threats to the integrity of sport, as it undermines the principles of fair play, diminishes the value of sporting competition, and deprives spectators of the element of unpredictability. The problem manifests itself in the connection between sport and illegal betting markets, where criminal groups manipulate outcomes in order to generate substantial financial gains. With the global expansion of online betting, rapid money transfers, and insufficient regulatory oversight, match-fixing has developed into a cross-border phenomenon that transcends the boundaries of individual states. The aim of the research was to analyze the causes, forms, and consequences of this phenomenon and to examine the responses of judicial authorities and sports organizations. Special attention was devoted to the legal framework in Slovenia and the preventive mechanisms developed by national and international sports institutions. In the theoretical part, we first presented the understanding of the concept of match-fixing and defined it as the deliberate manipulation of sporting outcomes for the purpose of obtaining unlawful benefits. We emphasized that criminal networks are highly adaptable, operate on multiple levels, and exploit the vulnerabilities of actors such as athletes, referees, and club officials. These individuals often face financial difficulties, are exposed to unpaid wages, or become victims of dependency relationships, extortion, and threats. In the empirical part, we analyzed concrete cases through case studies, including the Asiagate scandal in Zimbabwe, the cricket scandal involving Hansie Cronje, and the table tennis match-fixing affair in Ukraine. These cases demonstrated how criminal networks establish connections with sporting actors, which methods they use to manipulate results, and what sanctions were imposed on those involved ranging from disciplinary measures imposed by sports organizations to monetary fines and prison sentences under criminal law. International institutions have introduced various mechanisms for detecting and preventing manipulations, yet prosecution remains difficult due to the covert nature of the acts, the lack of sufficient evidence, and the global scope of betting markets. The main purpose of this thesis was to highlight the dangers that match-fixing poses to sport and to society at large, and to contribute to raising awareness of the need for more effective cooperation between sports organizations, state authorities, and international institutions in preventing this phenomenon
Methods for deploying a Kubernetes cluster in a resource-constrained environment
Get PDFV magistrskem delu obravnavamo metode razmestitve gruče Kubernetes v okolju z omejenimi viri. Cilj dela je predstaviti dva različna pristopa vzpostavitve gruče lahke distribucije Kubernetes, imenovane K3s, z osredotočenjem na implementacijo načel metodologije DevOps , ter prikazati ključne razlike teh pristopov.
V praktičnem delu sta bili razmeščeni dve gruči Kubernetes: ena z ročnimi posegi in druga na standardiziran način s pomočjo orodja za avtomatizacijo Ansible. V okviru poskusa smo prav tako integrirali mehanizem neprekinjene dostave aplikacij ter vzpostavili sistem za spremljanje in nadzor gruč Kubernetes. Na podlagi primerjave obeh pristopov razmestitve so v magistrskem delu predstavljeni ključni vidiki, kot so varnost, vzdrževalnost, stabilnost, učinkovitost in uporabnost.
Ugotovitve so pokazale, da avtomatizacija opravil in neprekinjena dostava skupaj omogočata zanesljivejšo, učinkovitejšo ter lažje vzdrževalno razmestitev gruče Kubernetes. Orodje Ansible je koristno predvsem pri upravljanju večjega števila vozlišč, saj zmanjšuje možnosti za človeške napake in omogoča enostavnejšo izvedbo nalog, čeprav je za pripravo konfiguracijskih skript treba vložiti kar nekaj časa in truda. Integracija orodja za neprekinjeno dostavo pa se najbolj obrestuje pri vzdrževanju večjega števila uvedenih aplikacij in sodelovanju več ekip, saj zagotavlja sledljivost sprememb, upravljanje različic in samodejno sinhronizacijo stanja v gruči z želenim.In the master\u27s thesis, we examine the methods of deploying a Kubernetes cluster in a resource-constrained environment. The objective of the thesis is to present two different approaches to setting up a lightweight Kubernetes distribution, named K3s, with a focus on implementing DevOps methodology principles, and to highlight the key differences between these approaches.
In the practical part, two Kubernetes clusters were deployed. One through manual interventions and the other in a standardized manner using the Ansible automation tool. As part of the experiment, we also integrated a continuous delivery mechanism for application deployment and established a monitoring system for Kubernetes clusters. Based on the comparison of both deployment approaches, the thesis presents key aspects such as security, maintainability, stability, efficiency and usability.
The findings indicate that task automation and continuous delivery together enable a more reliable, efficient and reproducible setup of a Kubernetes cluster. Ansible proves particularly useful when managing a larger number of nodes, as it reduces the risk of human error and simplifies task execution, although preparing configuration scripts requires a considerable amount of time and effort. The integration of continuous delivery tool is most beneficial for maintaining a larger number of deployed applications and for collaboration across multiple teams, as it ensures change of traceability, version management, and automatic synchronization of the cluster state with the desired configuration
Development of magnetically heated catalysts for chemical hydrogen storage
Get PDFDoktorska disertacija obravnava razvoj inovativnih magnetno odzivnih nanokompozitov, namenjenih uporabi kot nosilcev katalizatorjev za elektrificirane kemijske procese. Uporaba izmeničnega magnetnega polja omogoča lokalizirano, hitro in selektivno segrevanje katalitskega sloja, kar predstavlja alternativo klasičnim načinom gretja ter prispeva k večji energetski učinkovitosti in združljivosti procesov z obnovljivimi viri energije.
Glavni cilj doktorske disertacije je bil razvoj in karakterizacija novih magnetnih materialov za tehnologijo magnetno segrevane katalize ter preizkus njihove aktivnosti v procesih, ki omogočajo pretvorbo električne energije v kemijsko, kot je shranjevanje energije v molekulah, bogatih z vodikom. Preučili smo dva ključna primera: shranjevanje energije v obliki amonijaka (NH₃) ter v tekočih organskih nosilcih vodika (LOHC).
Za ta namen smo razvili postopek priprave CoxNi1-x-Al₂O₃ nanokompozitov, prenosljiv na večjo skalo, v katerih so zlitinski nanodelci CoNi (~ 15 nm) homogeno porazdeljeni po porozni matrici iz aluminijevega oksida. Ti materiali imajo visoko specifično površino (~150 m² g⁻¹), so stabilni in se učinkovito segrevajo (≥ 500 °C, 25 mT), ko so izpostavljeni izmeničnemu magnetnemu polju. Nanos rutenijevih nanodelcev (1 ut.%, 2-7 nm) in njihova promocija z barijem (4,5 ut.%) sta omogočila pripravo katalizatorjev z visoko disperzijo (54 %) ter dobro pokritostjo (52 %) aktivnih mest.
Eksperimenti sinteze in razgradnje amonijaka so potekali v namensko izdelanem kvarčnem reaktorju, ki omogoča obratovanje pri povišanih tlakih. Rezultati kažejo, da z barijem promoviran rutenijev katalizator pri sintezi NH₃ doseže reakcijsko hitrost 1600 mmol NH₃ gRu⁻¹ h⁻¹ pri 400 °C in 5,5 MPa, medtem ko nepromoviran katalizator doseže pri enakih pogojih zgolj 158 mmol NH₃ gRu⁻¹ h⁻¹. Podoben trend je prav tako pri razgradnji, kjer je popolna pretvorba s promoviranim katalizatorjem pri 50 °C nižja kot pri nepromoviranem. Poskusi, kjer smo dinamično vklapljali in izklapljali izmenično magnetno polje, so pokazali doseganje stacionarnih stanj v približno 10-15 min. Kvantnomehanski izračuni in modeliranje mikrokinetike so pokazali, da stična površina med barijevim oksidom in rutenijem bistveno olajša hitrost določujočo stopnjo, ki je razklop N2, kar pojasni opaženo povečano aktivnost z barijem promoviranih katalizatorjev.
Aktivnost pripravljenih magnetnih katalizatorjev smo testirali tudi v šaržnem sistemu v procesih hidrogenacije tekočih organskih nosilcev vodika, in sicer na toluenu in dibenziltoluenu. Pri nizkem tlaku (1 MPa) in zmernih temperaturah (120–150 °C) smo dosegli visoke stopnje pretvorbe. Pri toluenu je bila 100-odstotna pretvorba dosežena že po dveh urah pri 120 °C, medtem ko je bil pri 150 °C za popolnoma hidrogeniranem dibenziltoluen dosežen izkoristek 37,6 % po 7,4 urah reakcije.
Disertacija uvaja nov koncept katalitskih procesov, ki temeljijo na magnetnem segrevanju katalitskega sloja. Ta inovativni pristop predstavlja izviren znanstveni prispevek, saj omogoča učinkovitejšo izrabo energije, hitrejši odziv sistema in odpira možnosti za razvoj prilagodljivih, nizkoogljičnih tehnologij, združljivih z obnovljivimi viri energije. Doseženi rezultati potrjujejo uporabnost razvitih materialov za dolgoročno shranjevanje energije v kemijski obliki in s tem pomembno prispevajo k trajnostnemu razvoju alternativnih tehnologij.This dissertation focuses on the development of innovative magnetically responsive nanocomposites to serve as catalyst carriers for electrified chemical processes. The use of an alternating magnetic field enables localised, rapid and selective heating of the active sites of the catalyst, which represents an alternative to conventional heating methods and contributes to improved energy efficiency and compatibility with renewable energy sources.
The main objective of this work was to develop and characterise new magnetic materials for magnetically heated catalysis. Furthermore, we evaluated their performance in processes that enable the conversion of electrical energy into chemical energy, such as energy storage in hydrogen-rich molecules. Two important case studies were investigated: energy storage in the form of ammonia (NH₃) and hydrogen storage in liquid organic hydrogen carriers (LOHC).
To this end, a scalable synthesis route for CoxNi₁₋ₓ-Al₂O₃ nanocomposites was developed in which the CoNi-alloy nanoparticles (~15 nm) are homogeneously dispersed in a porous aluminium oxide matrix. These materials exhibit a high specific surface area (~150 m² g⁻¹), good stability and efficient heating (≥500 °C, 25 mT) when exposed to an alternating magnetic field. The deposition of ruthenium nanoparticles (1 wt%, 2–7 nm) and their promotion with barium (4.5 wt%) resulted in catalysts with high dispersion of ruthenium (54 %) and good coverage of the ruthenium active sites with barium species (52 %).
The ammonia synthesis and decomposition experiments were carried out in a custom-designed high-pressure reactor. The results show that the barium-promoted ruthenium catalyst achieves an ammonia synthesis rate of 1600 mmol NH₃ gRu⁻¹ h⁻¹ at 400 °C and 5.5 MPa. In contrast, the non-promoted catalyst only achieved 158 mmol NH₃gRu⁻¹ h⁻¹ under the same conditions. A similar trend was observed for ammonia decomposition, where complete conversion was achieved 50 °C lower with the promoted catalyst compared to the non-promoted catalyst. Dynamic experiments, in which the alternating magnetic field was switched on and off at regular intervals, showed that the steady state is reached within 10–15 minutes. Quantum chemical calculations and microkinetic modelling revealed that the interface between barium oxide and ruthenium significantly lowers the energy barrier for nitrogen dissociative adsorption. The latter explains the observed increased activity of the barium-promoted catalysts.
The activity of the prepared magnetic catalysts was also tested in batch hydrogenation processes of liquid organic hydrogen carriers, in particular toluene and dibenzyltoluene. High conversion rates were achieved at low pressure (1 MPa) and moderate temperatures (120–150 °C). For toluene, complete conversion was achieved within two hours at 120 °C, while a yield of 37.6 % was achieved for H18-dibenzyltoluene after 7.4 hours at 150 °C.
The dissertation presents a novel concept for catalytic processes based on magnetic heating. This innovative approach represents a significant scientific contribution as it enables more efficient energy utilisation, faster system response and opens up new possibilities for the development of flexible, low-carbon technologies compatible with renewable energy sources. The results confirm the applicability of the developed materials for long-term renewable energy storage in chemical form and thus make an important contribution to the development of sustainable technologies