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Low temperature tests and fracture toughness of selected ceramic materials
Beck, Branislav ; Drdlík, Daniel (referee) ; Chlup, Zdeněk (advisor)
Diploma thesis deals with the determination of fracture toughness values of sintered silicon carbide and casted basalt using both the Single Edge V-Notch Beam (SEVNB) and the Chevron Notched Beam (CNB) methods at room and cryogenic temperatures. The first part of this thesis offers general overview and categorization of ceramic materials. Fracture mechanics of the ceramic materials and available fracture toughness testing methods are discussed in following chapters. The last section in the theoretical part is aimed to the microstructure and properties of the silicon carbide. Experimental part of the work summarizes methods used for characterization of selected materials from the microstructural and fracture point of view. Preparation of samples for microstructural observation and samples for fracture toughness determination are described in details. The results of the fracture toughness data for sintered silicon carbide and cast-basalt obtained at room temperature and at -100 °C are displayed. Consideration of possible measurements errors and application of various fracture toughness testing methods are discussed in the next chapter of this work. The difference in the fracture toughness values with the decrease of testing temperature was found. The difference depends on both, the used method of fracture toughness determination and the material used for the tests. The most important results gained during the experimental work are summarized in the chapter “Conclusions”.
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Comparison of different types of commercial lithium-ion batteries and their properties under low temperature
Bičák, Tomáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
The diploma thesis deals with the issue of lithium-ion batteries. Describes development, technologies and materials used. The diploma thesis describes the operating principle, characteristics, advantages and disadvantages. The work is focused on the characteristic properties of commercial lithium-ion batteries under standard conditions and at reduced temperatures. At reduced temperatures, changes in properties due to low temperatures are observed. Furthermore, in this work they compare the measured values with the values given by the manufacturers.
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Very low temperature measurement
Mráz, Dominik ; Harabiš, Vratislav (referee) ; Chmelař, Milan (advisor)
This bachelor thesis is focused on low temperature measurement, respectively on temperature sensors classsification, their accuracy, temperature range and linearity. It deals especially in use of these sensors in cryogenic applications. It contains temperature sensor block diagram, including the description of each block. It also contains schematic designs with description of each design’s function, components and the reason why it’s used. Additionally the realization of the temperature sensor is described and it’s testing.
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Design of a Non-Resonant General Purpose Sample Holder for Terahertz Electron Paramagnetic Resonance Spectroscopy
Martínek, Tomáš ; Sojka, Zbigniew (referee) ; Neugebauer, Petr (advisor)
Cílem diplomové práce je navrhnout konstrukční řešení držáků vzorků pro vysokofrekvenční elektron paramagnetickou resonanci. Předmětem návrhu je vytvořit jednoduchý zamykací systém pro spojování mikrovlnného vlnovodu a držáku vzorku. Dále navrhnout systém s řešením držáku pro více vzorků. Toto unikátní provedení držáku povede k několikanásobné úspoře celkového času měření vzorků. Poslední návrh spočívá v optimalizaci držáku vzorku s možností naklápění osy, kterou lze díky přímému napojení na piezoelektrický rotátor pootáčet s přesností na miliradiány. Oba typy držáku vzorku jsou navrženy s ohledem na automatizaci měření.
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Conceptual design of a gear tester for space applications
Florián, Vojtěch ; Černohlávek, Mikuláš (referee) ; Košťál, David (advisor)
This bachelor thesis deals with the creation of a conceptual design of gears tester for space applications. The tester must simulate space conditions and test whether the gear can operate in those conditions. It is more important to test the wheel material than its geometry. The work is divided into theoretical and practical part. In the theoretical part, a search of current knowledge of the issue is created. The second part describes several conceptual designs of testers and their models. Subsequently, a concept that can most faithfully simulate real conditions in low orbit is selected and described in detail. The final design of this concept will facilitate the testing of gears and minimize their failure rate during operation.
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Analysis of critical parameters of the batteries for space applications
Šimek, Michal ; Šedina, Martin (referee) ; Kazda, Tomáš (advisor)
This thesis deals with the use of lithium-ion batteries for space applications. Primary and secondary electrochemical sources and their comparison are described in the paper. The main part of this work deals with lithium-ion batteries, their history, properties and used materials, deals with the use of li-ion batteries for space applications in terms of temperature and describes the effects of temperatures on li-ion batteries. At the last chapter deals with a lithium plating and his detection. In the practical part, a methodology for the detection of cast plating is proposed, which I then test on a number of cells, which I measure at various practical workloads.
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Very low temperature measurement (to -160 of degrees Celsius)
Vlček, Josef ; Rampl, Ivan (referee) ; Chmelař, Milan (advisor)
his semestral thesis deals with measurement of low temperatures (down to -160 degrees Celsius). This thesis describes basics of cryotherapy and its practical implementation. It also deals with different types of temperature sensors which means theoretical description of their work, thein advantages and disadvantages. The main goal is to put a recommendation of which of this sensors is the most suitable for practical implementation of the thermometer.
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Jak rostliny vnímají chlad: omická analýza
Karšulinová, Daniela
Plants of temperate zones have developed a sophisticated mechanism that helps them cope with freezing conditions. This process is called cold acclimation. From an agronomical point of view, comprehending this process is necessary to ensure crop yield and quality. This thesis entitled: "Jak rostliny vnímají chlad: omická analýza" describes the molecular mechanism behind the cold acclimation process, specifically the role of light and selected photoreceptors in this process. In the experimental part of the thesis, a mutant line (UVR8 line12-monomer) of model organism Arabidopsis thaliana, which has a partially activated signaling of the UV-B, and the control line (Ws-4) were used. These lines were exposed to cold and UV-B radiation to further study the interaction of the cold signaling pathway and UV-B radiation signaling. LC-MS profiling identified more than 6000 proteins, of which 3472 significantly changed their abundance. Moreover, lipidome analysis was performed using TLC Proteomic analysis revealed an increased abundance of proteins involved in biosynthesis of jasmonic acid. Based on this, a validation experiment with exogenous application of methyl jasmonic acid was performed.
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Workplace for measuring capacity and rate-capability characteristics of lithium-ion batteries
Cápal, David ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This master's thesis deals with the issues of lithium-ion batteries, describing common types of commercial lithium-ion batteries, their advantages, disadvantages, and characteristic properties. The thesis focuses in more detail on the influence of temperature on the characteristics of lithium-ion battery. The thesis describes the design and construction of a workplace for measuring capacity and rate-capability characteristics of lithium-ion batteries at low and high temperatures. The thesis also describes the implementation of a cooling and heating module using a system based on Peltier devices.
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