The aviation industry plays a significant role in global connectivity and economic growthbut has substantial negative environmental impacts, particularly in terms of carbondioxide emissions. According to a study by the European parliament, the aviationindustry accounts for 0,4 % of greenhouse gas emissions within the EU and 3,4% forinternational flights. In response to these environmental issues, liquid hydrogen is seenas a promising choice, offering efficiency as a clean energy source, especially whenproduced through electrolysis, as well as higher energy density per volume, making itattractive for the aviation industry where energy and weight optimization are crucial. However, the challenge of using hydrogen as fuel lies in designing a tank that canwithstand extreme conditions, such as low temperature and high pressure , while alsominimizing the risk of flammability and explosion. Additionally the right materials mustbe chosen to resist hydrogen embrittlement. This project aims to design a hydrogentank for aircraft that meets the requirements specified in this study. This will be achievedthrough a literature review, numerical simulations with SolidWorks FEM to test differenttank shapes and materials, and the use of Python code to calculate different spatialparameters.The results indicate that a cylindrical shape is the most optimal choice for the tank, andfour materials have been identified as suitable, with aluminum alloys showing moreadvantages compared to stainless steel due to reduced weight with similar strength.

Šiame baigiamajame darbe optimizuojama plokščiojo kūno forma esant žinomai apkrovai ir kraštinėms sąlygoms. Aptariami pagrindiniai optimizavimo tipai, globaliojo optimizavimo ir kontinuumo diskretizavimo metodai. Forma optimizuojama trimis skirtingais neadaptyviais genetiniais algoritmais ir trimis adaptyviais, taikant migracijos strategijas. Poslinkiai ir von Mises įtempimai skaičiuojami baigtinių elementų metodu. Darbo užduotis realizuota C++ kalba. Darbą sudaro 9 dalys: įvadas, kūno formos modeliavimo metodų apžvalga, baigtinių elementų metodas, genetiniai algoritmai, kūno formos optimizavimo uždavinys, rezultatų palyginimas, išvados, literatūros sąrašas, priedai. Darbo apimtis - 62 p. teksto be priedų, 39 iliustr., 5 lent., 24 bibliografinių šaltinių. / The task of Master thesis is to optimize shape of plane body with given loading and boundary conditions. The classes of structural optimization problems, the methods of global optimization and discretization of continual structures are discussed. For shape optimization three different not adaptive and three adaptive genetic algorithms with migration strategy are used, displacements and von Mises stresses are calculated using finite element method. The program was created using C++ language. The work consists of 9 parts: introduction, overview of methods used for shape optimization, finite element method, genetic algorithms, shape optimization of plane body, results, conclusions, references, appendixes. Work consist of 62 p. text without appendixes, 39 pictures, 5 tables, 24 bibliographical entries. Appendixes are included.

L’électronique de puissance a un rôle de plus en plus grandissant dans les systèmes de transports : voitures électriques et hybrides, trains et avions. Pour ces applications, la sécurité est un point critique et par conséquent la fiabilité du système de puissance doit être optimisée. La connaissance du temps de fonctionnement avant défaillance est une donnée recherchée par les concepteurs de ces systèmes. Dans cette optique, un indicateur de défaillance précoce permettrait de prédire la défaillance des systèmes avant que celle-ci soit effective. Dans cette thèse, nous nous sommes intéressés à la caractérisation électromécanique des puces de puissance IGBT et MOSFET. L’exploitation de cette caractérisation devrait permettre, à plus long terme, de mettre en évidence un indicateur de l’état mécanique des assemblages de puissance à des fins de fiabilité prédictive. / Power electronics has a role increasingly growing up in transport:electric and hybrid vehicles, trains and aircraft. For these applications, security is a critical point, thus the reliability of the power assembly must be optimized. The knowledge of time to failure is very important information for the designers of these systems. Inthis context, an early failure indicator would predict system failuresbefore it becomes effective. In this thesis, we focused on the electromechanical characterization of power transistors: MOSFET and IGBT. Based on these results this electromechanical characterization should help us in the longer term, to highlight an early failure indicator of the power assembly.

Performance of static analysis of the London Eye structure is the subject of this diploma thesis. First chapters of the thesis analyses overview of realized structures of the Ferris wheel. The main part of the thesis analyses the London Eye structure itself. Specifically are described response analyses, sensitivity analyses, analyses of ultimate limit state and serviceability, stress analyses, analyses of fatigue stress and lifetime analyses. The thesis describes among static analysis also a design of dynamic vibration absorbers. The results of each analysis are evaluated in the final chapters.