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Design of nuclear ceramic materials with enhanced thermal conductivity
Roleček, Jakub ; Katovský, Karel (referee) ; Salamon, David (advisor)
Oxid uraničitý (UO2) je v současnosti nejčastěji používaným materiálem jakožto palivo v komerčních jaderných reaktorech. Největší nevýhodou UO2 je jeho velmi nízká tepelná vodivost, a protože se při štěpení UO2 v jaderném reaktoru vytváří velké množství tepla, vzniká v UO2 peletě velký teplotní gradient. Tento teplotní gradient způsobuje vznik velkého tepelného napětí uvnitř pelety, což následně vede k tvorbě trhlin. Tyto trhliny napomáhají k šíření štěpných plynů při vysoké míře vyhoření paliva. Tvorba trhlin a zvýšený vývin štěpného plynu posléze vede ke značnému snížení odolnosti jaderného paliva. Tato práce se zabývá problematikou zvyšování tepelné vodivosti jaderného paliva na modelu materiálu (CeO2). V této práci jsou studovány podobnosti chování CeO2 a UO2 při konvenčním slinováním a při „spark plasma sintering.“ Způsob jak zvýšit tepelnou vodivost použitý v této práci je včlenění vysoce tepelně vodivého materiálu, karbidu křemíku (SiC), do struktury CeO2 pelet. Od karbidu křemíku je očekáváno, že zvýší tok tepla z jádra pelety, a tím zvýší tepelnou vodivost CeO2. V této práci je také porovnávána podobnost chování SiC v CeO2 matrici s chováním SiC v UO2, které bylo popsáno v literatuře.
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Design inverter using semiconductor on based SiC
Kharchenko, Vadym ; Procházka, Petr (referee) ; Kuzdas, Jan (advisor)
This work builds on a semester project 2. from the winter semester of this academic year. The aim of this thesis is the design of converter using semiconductor components based on SiC technology. This converter is used in the construction of quick charger for electric vehicles. The design of this converter must be based on the requirements for compliance voltage safety. It describes the design of power components used in the construction of this facility, the determination of their losses and determines the overall efficiency of the converter. There is also proposed mathematical model of high-frequency transformer and made his simulation in Matlab-Simulink.
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Design of an effusion cell for the deposition of Sn and Zn ultrathin layers
Horák, Stanislav ; Kolíbal, Miroslav (referee) ; Mach, Jindřich (advisor)
This bachelor thesis deals with the design and the construction of effusion cells for the deposition of zinc and tin ultrathin layers. In the introductory part there is an explanation of principles of eusion cells' functions, like a molecular beam epitaxy (MBE) or a construction of the efussion ow. Furthermore, the work describes a general principles of a ccreation of the atom sources. Theoretical part ends with review about the growth of ultrathin layers and nanostructures of zinc, tin and their compounds. Experimental part provides a design of the effusion cells with radiation heating from silicon carbide and heating by electrons impact. The complete drawing documentation of the designed effusion cells is included in the attachment.
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CONVERTER DESIGN USING SEMICONDUCTORS BASED ON SiC
Kharchenko, Vadym ; Procházka, Petr (referee) ; Kuzdas, Jan (advisor)
This work builds on a semester project 2 from the winter semester of this academic year. The aim of this thesis is the design of converter using semiconductor components based on SiC technology. This converter is used in the construction of quick charger for electric vehicles. The design of this converter must be based on the requirements for compliance voltage safety. It describes the design of power components used in the construction of this facility, the determination of their losses and determines the overall efficiency of the converter. There is also proposed mathematical model of high-frequency transformer and made his simulation in Matlab-Simulink.
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Electroerosion wire cutting of technical ceramics
Habovštiaková, Mária ; Mouralová, Kateřina (referee) ; Osička, Karel (advisor)
The presented diploma thesis deals with the issue of wire electrical discharge machining of SiSiC ceramics. The first part explains the principles of electrical discharge machining, describes the WEDM technology and presents the properties of the advanced ceramics. The second part consists of a detailed analysis of the cutting process of eighteen samples obtained with systematically changing process parameters. Based on the obtained results from EDX analysis, SEM electron microscopy and topography there was performed an analysis of the influence of process parameters on the cutting speed, surface roughness, kerf width and number of wire breaks with usage of the selected brass cutting wire. From the evaluated results it was possible to select a combination of parameters that ensured a stable machining process.
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Switching supply source 5,5kV/4,3kW with silicon-carbide semiconductors
Gabriel, Petr ; Patočka, Miroslav (referee) ; Vorel, Pavel (advisor)
This thesis is about to introduce the development of switched power supply with output voltage of 5,5 kV and power of 4,3 kW. This thesis directly follows the outputs of two previous semester projects. Main task is about to finish the development of remaining printed circuit boards and perform launching of all parts of developed power supply. Next necessary task is about to assemble a functional prototype of the supply using the developed parts, performing a series of measurement supply’s parameters and creating of technical documentation of mechanical part. There are all stages of supply’s development included in this thesis. From the first part, that describes various types of converters, through the design of all the supply’s parts, to final implementation of functional prototype. There are the results of measurement supply’s parameters at the end of this thesis.
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Proposal PCB power of the charger for electromobil
Kharchenko, Vadym ; Otýpka, Jan (referee) ; Kuzdas, Jan (advisor)
The aim of this Bachelor Thesis is the PCB design of the Quick Charger performance based on new semiconductors SiC for electric vehicles. This work builds on a semester project from a winter semester of this academic year. In addition to the PCB design here described dimensioning of power devices used in the construction of Quick Charger, setting their losses and carry out the measurements, which aims to compare the performance of DC / DC converters with manned SiC diodes converter, whose structure is based on conventional silicon diodes.
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Testing of Surge Arresters
Jeřábek, Lukáš ; Paar, Martin (referee) ; Krbal, Michal (advisor)
This bachelor's thesis is devoted to metal oxide surge arresters. After historical and theoretical introduction, which explains their principles and describes their characteristical properties, analysis of the standard IEC 60099-4 and testing according to the standard with focus on the type tests follows. This chapter is also amended with review of the standard's imperfections and with its most probable future development. The work concludes with a market survey, a review of the largest manufacturers and a comparison of their products.
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Market survey of high power semiconductor devices
Jankovský, Martin ; Rujbrová, Šárka (referee) ; Zmrzlá, Petra (advisor)
Hlavním tématem práce jsou moderní výkonové polovodičové součástky. Jsou diskutovány i rozvíjející se materiály s velkou šířkou zakázaného pasu a jejich elektrické vlastnosti. Práce je pak zaměřena na tyto moderní součástky, včetně jejich teorie, aplikace a dostupnosti na trhu. Dále práce předkládá tabulky jednotlivých zařízení, které jsou nabízeny evropskými předními výrobci polovodičů.
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