Theses (Faculty of Science and Technology)
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Theses collection of the XX department/institute. The collection was started in 2017.
At the University of Debrecen, in accordance with the 2022 amendment to the 2011 Higher Education Act, student theses are only accessible from devices connected to the University's Eduroam WiFi network or from a university IP address.
“The thesis or diploma work of a student who has successfully passed the final examination shall be stored in full in the academic system of the higher education institution, and a record shall be maintained thereof. The stored theses and diploma works – with the exception of parts classified as confidential in accordance with the relevant legislation – must be made accessible and searchable without restriction through the academic system.” Further info on the National Higher Education Act in Hungarian: Felsőokt. tv. (új) - 2011. évi CCIV. törvény a nemzeti felsőoktatásról - Hatályos Jogszabályok Gyűjteménye.
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Tétel Korlátozottan hozzáférhető A 10 Year Statistical Analysis of Heavy Metal in River and Sediment in River Tisza, HungaryBabar, Nayna; Czédli, Herta; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetIn course of our research, we did 10-year statistical analysis of heavy metals in Tisza river, Szolnok from 2010-2020. In doing so, we measured As, Zn, Hg, Cd, Cr, Mn, Ni, Pb, Cu, Fe from Tisza river. The sampling point was conducted at the Szolnok road bridge (335.5 TKM) from the small circle of the Tisza to the Hármas-Körös. The samples were collected from the period of 01/01/2010-03/12/2020. We did a time-series analysis on heavy metals.Tétel Korlátozottan hozzáférhető 15-membered rigid macrocyclic ligand for Mn2+ complexation: synthesis and coordination chemical characterizationBaghirova, Aghanana; Tircsó, Gyula; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThe investigation of Mn²⁺ chelates as alternatives to Gd³⁺-based MRI contrast agents has gained significant attention due to their promising safety and performance profiles. My research focused on the synthesis and coordination chemistry of a novel 15-membered bipyridine-based macrocyclic ligand, 15-BPyN5. The ligand demonstrated excellent thermodynamic stability (log K_MnL = 13.44), high kinetic inertness, and favorable relaxivity properties (r1p/r2p = 3.60/6.60 mM⁻¹s⁻¹). Dissociation studies revealed slow exchange kinetics with Zn²⁺ ions, with half-lives of 79.0 and 28.7 hours at 25°C and 37°C, respectively, attributed to the rigid coordination environment provided by the bipyridine moiety. These properties highlight the potential of [Mn(15-BPyN5)] as a safe and effective MRI contrast agent. This work paves the way for developing non-toxic alternatives to gadolinium-based agents, offering improved safety and imaging performance.Tétel Korlátozottan hozzáférhető 2024 Update of Retro-Transposons in the Aspergillus and Penicillium Genera and Other Filamentous FungiAdil, Dastan; Michel , Flipphi; Michel , Flipphi; DE--Természettudományi és Technológiai Kar--Biotechnológiai IntézetRetrotransposons are mobile genetic elements that can generate genomic diversity, impacting gene expression and genomic stability. This thesis investigates the role of Copia-type retrotransposons, specifically Ty1 elements, in filamentous fungi like Aspergillus niger and Penicillium chrysogenum, focusing on their evolutionary and biotechnological significance. The study examines the structural characteristics, integration patterns, and functional impacts of AniTA2, a Copia retrotransposon identified in A. niger, with attention to its influence on genes linked to industrially relevant traits. Further, it discusses the application of Ty1 retrotransposons in industrial strain development, highlighting both their potential to enhance fungal strains and the challenges posed by genomic instability. The research concludes with future possibilities for using genome-editing tools like CRISPR/Cas9 to harness Ty1 elements safely for fungal biotechnology.Tétel Korlátozottan hozzáférhető 33 MVA DISTRIBUTION GRID FOR A NIGERIAN TOWNSHIP USING MEDIUM VOLTAGEMaduagwu, Osinaka; Kosa, Janos; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThe power sector is the backbone of any thriving economy, providing the necessary energy for industrial, commercial, and domestic activities. In Nigeria, as in many developing nations, the power sector has been marred by persistent challenges, hindering the nation's economic growth and development. This dissertation seeks to delve into the intricate workings of the 33 MVA distribution grid in Nigeria, examining its role in the broader context of the nation's power sector, and proposing strategic interventions to address the prevailing issues. Nigeria, with its rapidly growing population and expanding economy, faces a continuous struggle to meet the escalating demand for electricity. The 33 MVA distribution grid plays a pivotal role in the final stage of the power supply chain, distributing electricity to end-users across various regions. However, despite the significance of this grid, there are systemic challenges that have hampered its effectiveness. In this report we are going to have an overview of how I conducted my thesis research report with the help of my supervisor Dr János Kosa. In my research report, we divided it into five main segments of which I wrote a detailed description of each segment to give an idea of what we are working with and how it all builds up together eventually. The following are the five main segments are listed below: 1. Show the Nigerian power grids. 2. Direction of development in Nigeria. 3. Design a medium voltage grid. 4. Calculation of the grid. 5. Applied switch gears in planned system.Tétel Korlátozottan hozzáférhető 3D analysis of the reaction products in Co2Si/Zn solid state diffusionTamel, Doga; Cserháti , Csaba; DE--Természettudományi és Technológiai Kar--Fizikai IntézetIn this thesis, a comprehensive investigation is conducted into the solid-state reaction between cobalt-disilicide (Co2Si) and solid zinc (Zn), with particular focus on the formation of periodic layered microstructures. The interaction between Co2Si and Zn is examined at 390°C, and samples are annealed for various durations to study the development of alternating layers. The reaction zone is characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). Additionally, 3D imaging and analytical mapping are presented to provide a detailed visualisation of the reaction dynamics.Tétel Korlátozottan hozzáférhető A Comparative Study on Credit Risk Between Industrial and Commercial Bank of China and Hunan Bank — Based on Empirical AnalysisChen, Zihao; Fruzsina , Mészáros; DE--Természettudományi és Technológiai Kar--Matematikai IntézetAgainst the backdrop of China’s ongoing economic transformation and upgrading, credit risk management in commercial banks has become a core issue, and the performance of credit risk varies significantly across different types of banks. This paper conducts a comparative study on the credit risk of large state-owned commercial banks and regional urban commercial banks, taking Industrial and Commercial Bank of China (ICBC) and Hunan Bank as research subjects. Using annual time series data from 2015 to 2024, this study adopts empirical analysis methods including descriptive statistics, independent samples t-test, and multiple linear regression to examine differences in credit risk levels and the heterogeneity of influencing factors. The research verifies three hypotheses: First, the credit risk level of ICBC is significantly lower than that of Hunan Bank, specifically reflected in a lower NPL ratio and higher PCR. Second, the intensity of the impact of Hunan’s GDP growth rate on Hunan Bank is significantly greater than that of national GDP growth rate on ICBC. Third, the intensity of the impact of capital adequacy ratio and micro, small, and medium-sized enterprise (SMEs) loan ratio on Hunan Bank is significantly greater than that of capital adequacy ratio and cross-regional coverage on ICBC. This study enriches the empirical support for the theory of credit risk heterogeneity in commercial banks, improves the empirical paradigm for comparing credit risk among different types of banks, provides quantitative evidence for both types of banks to optimize risk control strategies and for regulatory authorities to formulate differentiated regulatory policies, and facilitates the precise matching of financial resources with the needs of the real economy.Tétel Korlátozottan hozzáférhető A FIRST STEP IN ASSESSING THE DIATOM-BASED ECOLOGICAL STATUS OF INTERMITTENT STREAMS IN THE CARPATHIAN BASINESTHER, SHAMIM; Edina Kundrát-Simon, Viktória B-Béres; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetExtreme weather events such as prolonged droughts or flash floods are currently the most obvious signs of climate change. These disturbances are causing significant environmental stress to the wetland and aquatic communities. In the last century, the average temperature in the Carpathian Basin has increased by approximately 1°C. All of these alterations had a significant impact on the small streams, resulting in a typological shift in many of them: streams that had a permanent water supply became intermittent waters. In recent years, our research group has been studying the effects of stream drying on benthic algal assemblages in small watercourses in the Carpathian Basin. Here, we focus on the differences in diatom indices between (i) intermittent and permanent lowland streams and (ii) different phases of drying such as flowing, standing and dry phasesTétel Korlátozottan hozzáférhető A genetical and oenological analysis of some interspecific hybrids with recombinant and nonrecombinant mitochondrial genomesKumagai, Yukino; Antunovics, Zsuzsa; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThe interspecies hybrids of Saccharomyces cerevisiae and Saccharomyces uvarum have the possibility to overcome some issues, which wineries face, like the condition changes due to climate change or changes in client demand. In this research, the results indicated that the hybrids are polyploid, which means they have chromosome sets from their parental strains by karyotyping. Also, it was confirmed that some of them have recombinant mitochondrial DNA due to the result of RFLP. With some physiological tests, heterosis is confirmed based on the results, which demonstrate better traits of the hybrids compared to the parents. For example, the hybrids could undergo fermentation with more various sugars, or grow more efficiently under cold temperatures. Additionally, there are some differences between non-recombinant and recombinant mitochondrial DNA contained strains, such as different fermentation rates with disaccharide sugars, or the growth test with glycerol under warmer and colder temperatures. However, overall, the significant differences were not able to be observed in the physiological tests between non-recombinant and recombinant mitochondrial DNA-containing strains. Therefore, further research is required to understand the importance of mitochondrial DNA recombination in wine industry applications.Tétel Korlátozottan hozzáférhető A Novel Approach Utilizing Polylactic Acid and Chitosan for Enhanced Shelf Life and Sustainability.Uurtsaikh, Tselmegzaya; Norbert , Ág; DE--Természettudományi és Technológiai Kar--Biotechnológiai IntézetBiopolymers, such as chitosan and polylactic acid (PLA), are being thought of more and more as alternatives to synthetic polymers because they are better at being renewable and biodegradable. Reinforcement techniques like grafting and mixing are being used to further enhance their properties. One of the best things about PLA is that it is easy to get, biodegradable, flexible, and can be strengthened with different natural fibers and fillers. Bioplastics are being explored as viable alternatives to traditional synthetic plastics, in light of international agreements concerning plastics.Tétel Korlátozottan hozzáférhető A Quick Study on The Basics of Dynmaical Fields and Their PotentialsABDELRAZEQ, ALHASAN; Trócsányi , Zoltán; DE--Természettudományi és Technológiai Kar--Fizikai IntézetAmong the most compelling topics within this discipline are the dynamics of cosmological fields and the enigmatic forces driving the universe’s accelerated (or decelerated) expansion, commonly attributed to dark energy. This thesis embarks on a systematic study of dynamical fields, delving into their mathematical formulations, physical interpretations, and cosmological implications.Tétel Korlátozottan hozzáférhető A Spatial and Technical Assessment of Decentralized Solar Energy Adoption and Its Impact on Grid Imports Potential in Kimberley, Northern CapeCole, Katelyn; Lázár, István; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThis study evaluated the solar energy potential of three Kimberley neighbourhoods, the CBD, Royldene, and Galeshewe, using GIS-based spatial analysis across three technologies: rooftop PV, solar water heaters, and community-scale PV. Of 2,617 buildings analysed, 67.9% were deemed suitable for solar installation, with Royldene leading at 86.8% suitability and Galeshewe lowest at 57.1% due to smaller rooftop sizes. The combined annual energy output across all technologies totals 215 GWh/year, with rooftop PV contributing 95.1 GWh, community PV 113 GWh, and SWH 6.5 GWh in thermal savings, representing a potential 39% reduction in Kimberley's grid imports. The three technologies proved strongly complementary: community PV bridges equity gaps in underserved townships, rooftop PV enables household-level generation, and SWH delivers the highest efficiency for water heating specifically. Crucially, the study finds that the barriers to deployment are not technical but institutional, as the solar resource is abundant, the technologies are mature, and spatial data already exists. What remains needed is city-wide suitability mapping, disaggregated energy monitoring, dedicated funding for township community PV, and a municipal solar strategy that places energy equity at the heart of urban planning.Tétel Korlátozottan hozzáférhető A study and simulations of short interest rates and some effects on the market instruments using Vasicek ModelSukkar, Izzat; GÁLL, József; DE--Természettudományi és Technológiai Kar--Matematikai IntézetStudying the movements of short interest rates is a very important research field. Almost all banks and investment institutes borrow or lend money with floating interest rates. Thus, this study is essential to measure the risk and hedge it or to speculate a possible gain in the future. In this work we will focus on researching the short interest rates movements using Vasicek model and review some other models. Simulations for the interest rates and market instruments are presented using the Vasicek model in R.Tétel Korlátozottan hozzáférhető A Study on the Financial Feasibility of Overseas Chinese Catering Entrepreneurship Based on Discounted Cash Flow (DCF)WANG, YONGJIN; Nagy, Ábris; DE--Természettudományi és Technológiai Kar--Matematikai IntézetWith the in-depth extension of the "Belt and Road" Initiative to the Central and Eastern European region, Chinese-funded enterprises have accelerated their landing in the EU market, which has also brought deterministic segmented demand for overseas Chinese catering entrepreneurship. However, for individual entrepreneurs with limited overseas operation experience and start-up capital, existing valuation tools are difficult to adapt to the characteristics of short cycle and high uncertainty of overseas micro catering projects, and there is a lack of implementable quantitative decision-making reference system. This study takes the Chinese-funded public works supporting group meal market in Debrecen, Hungary as the research object. Aiming at the static limitations of the traditional Discounted Cash Flow (DCF) method, it introduces the real option theory to build a three-stage dynamic decision analysis framework, takes Net Present Value (NPV) and Internal Rate of Return (IRR) as the core indicators, and designs a Minimum Viable Product (MVP) model of "pure B2B virtual kitchen + second-hand equipment reuse + mechanized auxiliary cooking". The financial calculation results show that the initial investment of this model is only 35,000 euros, which is 45% of the traditional Chinese food entrepreneurship model; under the baseline scenario, the dynamic investment payback period is 3.4 months, the internal rate of return is 128%, and the marginal contribution rate exceeds 60%; the results of 5000 Monte Carlo simulations show that the probability of the project obtaining positive NPV is 97.6%, which has strong economic feasibility and anti-risk ability. This study not only corrects the adaptability of the traditional DCF model in the valuation of micro entrepreneurship projects, but also provides a replicable operation framework and risk prevention and control scheme for low-cost catering entrepreneurship of overseas Chinese.Tétel Korlátozottan hozzáférhető Accumulation and translocation of metals in Sudan grass during a 3-month-long field experimentMunuhe, Esther; Tőzsér, Dávid; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetHeavy metal accumulation in plants is a critical aspect of phytoremediation strategies aimed at mitigating environmental pollution. A study was conducted in which we investigated the heavy metal accumulation in Sudan grass ((Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) cultivated in a contaminated area located in Lovász-zug. We monitored metal accumulation in the roots, stems and leaves to assess their remediation potential. Through analysis, we identified notable variations in the accumulation capacity of different metals within the plant organs with time. Based on the results obtained, our study concluded Sudan Grass as a tolerant plant species in soils with low to moderate levels of contamination. The main depository organ of Sudan grass is the root. It can be effectively utilized to phytoremediate heavy metal contaminated soils through extraction, stabilization and transfer processes in the plant organs. The findings prospects Sudan grass as a promising candidate for phytoremediation.Tétel Korlátozottan hozzáférhető Accumulation and translocation of metals in Sudan grass during a 3-month-long field experimentMunuhe, Esther; Tőzsér, Dávid; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetHeavy metal accumulation in plants is a critical aspect of phytoremediation strategies aimed at mitigating environmental pollution. A study was conducted in which we investigated the heavy metal accumulation in Sudan grass ((Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) cultivated in a contaminated area located in Lovász-zug. We monitored metal accumulation in the roots, stems and leaves to assess their remediation potential. Through analysis, we identified notable variations in the accumulation capacity of different metals within the plant organs with time. Based on the results obtained, our study concluded Sudan Grass as a tolerant plant species in soils with low to moderate levels of contamination. The main depository organ of Sudan grass is the root. It can be effectively utilized to phytoremediate heavy metal contaminated soils through extraction, stabilization and transfer processes in the plant organs. The findings prospects Sudan grass as a promising candidate for phytoremediation.Tétel Korlátozottan hozzáférhető Accumulation patterns of metals in selected plant species - meta-analysisYelamanova, Ayash; Edina Kundrát-Simon, Edina; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThe study investigates the concentration and accumulation of heavy metals in amaranth plant tissues. The results indicate that the accumulation pattern of metals is different. The study also demonstrates that heavy metals were translocated from soil to plant organs. The Bioaccumulation Factor (BAF) was calculated for evaluation of the plants accumulation potential. Therefore, it can be dangerous to consume amaranth plants grown in polluted soil, because they greatly absorb much of these toxic metals.Tétel Korlátozottan hozzáférhető Accuracy Assessment of Airborne-Based Photogrammetry using UAVOyewole, Eriifeoluwa; Szabó, Gergely; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetAccuracy assessment using unmanned aerial vehicles (UAVs) involves evaluating the accuracy and precision of the data collected through photogrammetric methods. This can be done by comparing the UAV data to a ground truth dataset, such as GPS or survey data. The accuracy assessment process involves establishing ground control points (GCPs) to ensure accurate positioning, and then comparing the UAV data to the ground truth data through statistical analysis. This statistical analysis includes calculating square values, absolute vertical difference, mean, standard deviation, and root mean square error (RMSE) values. The results of the accuracy assessment is used to draw conclusions about the validity of the photogrammetric method used in the study and to provide recommendations for future research or applications.Tétel Korlátozottan hozzáférhető Accuracy constraints of different UAV sensor data of a landslide survey in HungaryNkunzi Rugamba , Fabrice; Bertalan, Laszlo; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThis study is about using modern technology to study and measure landslides, which are very dangerous events where rocks, soil, or mud slides down hills or mountains. Landslides can cause serious problems. Because they destroy homes, roads, farms and sometimes even take people’s lives. In many places around the world. These particular events they often happen mostly during heavy rain or because of different human activities like farming, deforestation and poor building methods. This topic was chosen in order to solve real-life problem in my country Rwanda and to gain skills in using smart technology to keep people safe. The study has several goals like how to detect landslide using LIDAR technology and different methods for analyzing results, get real results, and reduce landslide impact using remote sensing and 3D point cloud technology. This study uses remote sensing technology like LIDAR. INSAR and UAVs. These tools allowed the scanning from the sky without needing to go to dangerous place. Lidar uses laser beams to measure the land’s shape. Drones take many pictures, and special software is like Agisoft Metashape turns these images into 3D models. The study was done into steps where, the first step was fly the drone over the study area to take many high-quality pictures. These pictures were cleaned and processed to remove vegetation so that the land could be seen clearly. Then LIDAR and structure from motion (SFM) method were used to create 3D point cloud. Millions of small points and these points shows the land’s surface very Cleary. These point clouds were turned into digital elevation models (DEMs). DEMs are 3D maps that show the height and shape of the land. Finally, software’s like SAGA GIS, Arc GIS, Cloud compare, QGIS and past were used to analyze and get Statistical results and basic terrain analysis.Tétel Korlátozottan hozzáférhető Acoustic Emission During Structural Transformation in TWIP SteelsGuliyeva, Mehin; Dároczi, Lajos; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis investigates the acoustic emission (AE) behavior during deformation of FeMn(Cr) steel. The primary objective of this study was to correlate AE signals with the stress-strain curve of the deformation prcess. A combination of uniaxial tensile testing and in-situ acoustic emission measurements was employed to capture real-time AE and simultaneous stress-strain data. Optical microscopy and scanning electron microscopy (SEM) were used to get additional microstructural informations and determine the chemical composition. This research offers a thorough exploration of the acoustic emission phenomena in TWIP steels, highlighting how AE can serve as an effective tool for real-time monitoring of material behavior during mechanical testing.Tétel Korlátozottan hozzáférhető Acute Exercise-Induced Modulation of NOD-like Receptors (NLRs) Expression in Skeletal MuscleElsayed, Eman Abdallah Elsayed; Benkő, Szilvia; Eduárd, Bíró; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetNod-like receptors (NLRs) are part of the innate immune system, but they are also found in many other cell types, and their role in skeletal muscle remains largely underexplored. To address this, we developed a reproducible treadmill-based acute exercise model in mice, conducted at Zeitgeber Time 16 (ZT16) to align with their active nocturnal phase. Muscle samples were collected from the gastrocnemius at 4-, 8-, and 24-hours post-exercise to capture immediate and delayed gene expression responses. The aim of this thesis was to investigate the role of NLRs in muscle function by assessing how acute exercise affects the expression of NOD1 and NOD2 in skeletal muscle and comparing their expression between males and females. Gene expression analysis using qPCR confirmed that the early response gene NR4A3 was significantly upregulated at 4 hours in both male and female mice, indicating successful activation of exercise-responsive pathways. NOD2 expression was significantly elevated at 8 hours post-exercise in males only, suggesting a sex-specific activation possibly linked to cellular stress and the release of DAMPs following muscle damage. The downstream signalling molecule RIPK2, which is activated by NOD2, was also upregulated in males at 24 hours, further supporting this pathway's involvement. In contrast, NOD1 expression remained unchanged in both sexes. These results suggest that acute exercise triggers sex-specific molecular responses in skeletal muscle, particularly involving NOD2 signalling pathways. The study highlights the importance of considering biological sex in experiments investigating immune and exercise-related gene expression in skeletal muscle tissue.