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Photochromic effect in nanoporous titanium dioxide film with Ag nanocrystals
Galář, Pavel ; Malý, Petr (advisor) ; Dohnalová, Kateřina (referee)
The diploma thesis is devoted to multicolour photochromic effect in nanocomposite material Ag-TiO2, which is caused by a spectrally selective photoinduced decrease in extinction. The Thesis introduces briefly the theory of particle plasmons which are of fundamental significance for the investigated phenomenon. A short summary of the models and results published on photochromic effect in Ag-TiO2 is than given. The core of thesis deals with the optimization of this nanocomposite material towards a high photochromatic response. The influence of concentration of the TiO2 solution and of the speed of its spin coating deposition on a substrate was measured. Also the effect of AgNO3 quality used for sample preparation was monitored. A change in the extinction was found to depend on parameters of the excitation laser beam too. As a part of the optimization process, also the alternative TiO2 matrixes produced on basis of lamellar micelles were tested. The photochromic effect was monitored by measurements of the light extinction and scattering in dependence on the sample photoexposition. The properties of a set of the high-quality samples were studied using photoluminescence spectroscopy. Measurements of the photoluminescence decay with subpicosecond time resolution by up-conversion technique as well as of the...
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Generation of short-wavelength (<160 nm) radiation by conventional lasers
Chalupský, Jaromír ; Malý, Petr (advisor) ; Krása, Josef (referee)
The theoretical part of this diploma thesis seeks to explain the methods used for generation of coherent short-wavelength radiation. It describes the principles and the operation conditions of direct laser sources and indirect coherent radiation sources based on non-linear effects. Special attention is then paid to the short-wavelength free-electron lasers. This work summarizes properties of numerous sources of this kind. The introductory part of the thesis deals with the physical background of the generation and the manipulation of shortwavelength (VUV/XUV) radiation. The experimental part gives a summary of the results obtained at the FLASH facility (Free Electron LASer in Hamburg; earlier known as VUV FEL) operated at DESY. Methods and instrumentation used for investigating the materials damage due to laser ablation are described in this part of the thesis. UV-vis emission spectra of ablation plume were measured. Main goal is here to determine the ablation thresholds and the effective atenuation lengths in poly (methyl methacrylate) (PMMA), quartz (a-SiO2) and monocrystalline silicon irradiated with pulsed (~30fs) short-wavelength (32nm) intense laser radiation.
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Effect of surface of semiconductor nanocrystals on their properties: investigation by laser spectroscopy
Preclíková, Jana ; Malý, Petr (advisor) ; Franc, Jan (referee)
The topic of the diploma thesis is chemical treatment of the surfaces of semiconductor nanocrystals CdS and CdSe in the form of thin nanocrystalline films prepared by chemical bath deposition. The evolution of photoluminescence and absorption spectra was investigated under treatment by water, toluene, butylamine, pyridine and hydrogen peroxide. The strongest changes were observed by samples soaked in water, pyridine and aqueous solution of pyridine. The observed effects were explained by partly dissolving of nanocrystals by water and affecting behaviour of photoexcited holes in the presence of the strong hole acceptor pyridine. The second part of this diploma thesis deals with photochromic properties of silver nanoparticles in a titanium oxide matrix. The photochromic behaviour of the samples was examined in detail. A phenomenological model of photochromic changes was suggested in analogy with the hole burning spectroscopy. In order to better understand the microscopic processes in this composite material other experiments were realized - e.g. samples were UV irradiated, or laser illuminated under lowered air pressure, pump & probe experiment. Under laser irradiation optical extinction of some nanoparticles was decreased. Simultaneously, changes of plasmon resonances of the rest of nanoparticels were...
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Mobile Cash Desk
Malý, Petr ; Hruška, Tomáš (referee) ; Kurečka, Radomír (advisor)
The bachelor thesis deals with the proposition and the implementation of system for mobile orders in restaurants, that would enable sta ff to create and to bill orders. Spending can be paid from customer's account after customer authentication. The system is implemented for mobile platform Windows Phone version 7.5.
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Design of Automatic Trading Systém Based on Fractal Geometry
Malý, Petr ; Dostál, Petr (referee) ; Budík, Jan (advisor)
This thesis deals with an analysis and prediction of foreign exchange markets. The thesis is based on the fractal market hypothesis and it uses tools based on fractal geometry for prediction of markets. The thesis also describes ways of using advanced methods of artificial intelligence for analyzing markets. The outcome is designed and implemented automatic trading system. The thesis also deals with testing of designed system on historical data and on the latest data as well.
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Winter swimming training and its importance in speed canoeists in the junior year.
MALÝ, Petr
MALÝ, Petr. Winter swimming training and its importance in speed canoeists in his junior season. České Budějovice 2014. Thesis. University of South Bohemia in the České Budějovice. Faculty of Education. Department of Health Education. Supervisor Mgr. M. Pospíšilová. This thesis deals with the winter training in speed canoeists. The theoretical part describes the influences and effects of swimming technique and various styles. The practical part contains detailed descriptions of training cycles and recommendations, dedicated athletes who are engaged in similar activities. Shows the way to achieve optimal results for junior canoeists, use of swimming training in the winter. Indicates errors incurred due to improper execution of techniques and try to eliminate them through simple training exercise.
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