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A Stefan problem of heat conduction with phase change and its exact solution
Kesler, René ; Mauder, Tomáš (referee) ; Klimeš, Lubomír (advisor)
This bachelor's thesis deals with analytical solutions of heat conduction problems with phase change which are known as classical Stefan problems. At the beginning a differential equation of heat conduction is derived and a mathematical model of Stefan problem is formed. The greatest attention is paid to the derivation of analytical solutions for cases in which these solutions are obtainable. The MATLAB environment was chosen for implementation of the obtained solutions. The thesis also includes a description of the program and its graphical interface in MATLAB. The applicability of the program is demonstrated in several phase change problems.
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Magnetic force microscopy and transport properties of metamagnetic nanostructures
Jaskowiec, Jiří ; Vaňatka, Marek (referee) ; Uhlíř, Vojtěch (advisor)
Iron-rhodium (FeRh) is a material featuring a first-order phase transition between antiferomagnetic (AF) and feromagnetic (FM) phases. The phase transition is symmetric with respect to the direction of transition in bulk FeRh and FeRh thin films. The bachelor thesis focuses on the properties of mesostructures of sub-micron size, where asymmetry between the AF-FM and FM-AF transitions has been recently discovered using electrical transport measurements dependent on temperature. The phase domain structure of FeRh mesostructures during the phase transition is visualized by magnetic force microscopy (MFM) in an out-of-plane magnetic field. Quantitative analysis of the measured magnetic signal reveals the effect of structure size on supercooling of the FM phase and abrupt increase of the AF phase during the FM-AF transition.
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Regelation of patterned ground in the High Tatras.
Pechačová, Blanka ; Křížek, Marek (advisor) ; Voják, Karel (referee)
Regelation (freeze-thaw cycles) is the collective term used for a process of alternate freezing and thawing of water and solutions into the soil or bedrock. The series of geomorphological and pedological processes such as migration of soil water, formation of segregated ice or frost heaving, is connected with regelation. Condition of freezing-thawing process is a phase transition of water that leads to an important phenomenon - a release or consumption of latent heat. This phenomenon can be observed from the data obtained by measuring the temperature in the soil profile. In the present bachelor thesis, here are investigated sites of sorted patterned ground (Hincovo pleso, Lučné sedlo) and earth hummocks (Kopské sedlo) in the High Tatras for the purposes of the study regelation process. In addition to detailed description of the physical-geomorphological processes associated with phase changes of water in patterned groud, the main aim of the thesis is to set regelation cycles and their characteristics using different methods for determination of regelation on the basis of temperature measurements in patterned groug of the foregoing locations. The results indicate differences in regelation in the individual shapes within the locations, among the sites, but also between different types of patterned groud -...
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