|
|
Filtering structures for fotovoltaic power stations
Hruška, Petr ; Dostál, Tomáš (referee) ; Petržela, Jiří (advisor)
This thesis is dedicated to an issue of vibration of photovoltaic panels, which manifests itself primarily in the acoustic field. From the photoelectric effect is gradually getting through photovoltaic cell, panel, string, power plant to define the causes of the vibration. The aim of the work is to design electrical low pass filter that suppress disruptive elements, which prevents audible vibrations of panels and the whole system of photovoltaic power plants.
|
|
|
Democratic State Governed by law: Ideal and Reality
Hruška, Petr ; Žák Krzyžanková, Katarzyna (referee)
The diploma thesis deals mainly with four topics - the rule of law, democracy, the democratic state governed by the rule of law and its real form in the Czech Republic during the global pandemic of COVID-19. The development of the rule of law, democracy and the democratic state governed by the rule of law continues and is influenced by the challenges that arise over time. The original formal conception of the rule of law was focused primarily on the observance of the rule of law, while the material conception already takes into account certain value aspects and fundamental human rights. Today's form of democracy differs significantly from its original ancient Greek definition. It was originally intended to be applied to small homogeneous units in which individuals would participate in voting on all important matters. Over time, however, it began to apply to large nation states, which required the adoption of the institute of council. A democratic state governed by the rule of law is a concept based on the dynamic balancing of the components between which a certain tension may arise. Its ideal is fulfilled by a situation where its individual aspects are continually improved in the most balanced way possible. All these the above-mentioned institutes have been affected by the global pandemic of...
|
|
|
Regular and chaotic collective motions of atomic nuclei
Hruška, Petr ; Cejnar, Pavel (advisor) ; Knapp, František (referee)
This thesis deals with quantum chaos in the geometric collective model of atomic nuclei (GCM). The rst and second chapters introduce the derivation and analysis of basic aspects of the GCM. Two ways of quantization are introduced for zero rotations of the nucleus. The rst one takes into account only the vibrational degrees of freedom and does not correspond to real nuclei. The second way reects both vibrational and rotational degrees of freedom and leads to the standard GCM. The third chapter includes analytical calculations of matrix elements of the GCM in the harmonic oscillator basis. Some measures of chaos are described in the fourth chapter, including the method based on Peres lattices. Numerical results for both quantization methods are presented in the form of Peres lattices, which are compared with some adopted results of other measures of chaos.
|
|
| |
|
|
Studium defektů v tenkých kovových vrstvách
Hruška, Petr ; Čížek, Jakub (advisor) ; Bulíř, Jiří (referee)
In the present work Mg films prepared by RF magnetron sputtering were studied. Variable energy positron annihilation spectroscopy (VEPAS) was employed for investigation of defects in the Mg films. VEPAS characterization was combined with scanning electron microscopy and X-ray diffraction in order to determine grain size, phase composition and texture. The effect of different deposition rate and deposition temperature, annealing, various substrates and film thickness on the structure and amount of defects present in the Mg films was examined. Defect studies by VEPAS showed that positrons in studied Mg films are trapped at misfit dislocations and at vacancy-like defects in grain boundaries and their density can be reduced by the deposition at elevated temperature. 1
|
|
|
Parish Pastoral Councils in the Czech Ecclesial Province as Realization of Synodality in Pastoral Practice
Hruška, Petr ; Opatrný, Aleš (advisor) ; Ambros, Pavel (referee) ; Křišťan, Alois (referee)
Pastorační rady farností v České církevní provincii jako realizace synodality v pastorační praxi Předkládaná dizertace se ve světle dnešní praxe pastoračních rad farností v české církevní provincii snaží prozkoumat různé modely a přístupy k práci pastoračních rad farností, teologicky je reflektovat z hlediska realizace synodality v církvi, naznačit některé možnosti synodálního chápání služby pastoračních rad a nabídnout některé praktické podněty pro podporu jejich služby v diecézích, aby pastorační rady farností mohly být účinnými nástroji pastorační služby farností jakožto učednických a sloužících komunit, které jsou na "společné cestě" (syn-ódos) do Božího království v kontextu dnešní společnosti. Srdcem celé dizertace je "prakticko-teologická reflexe" v páté kapitole založená na tvůrčím dialogu pramenů prezentovaných v kapitolách předchozích: (1) "kontextových východisek", (2) "situační reflexe", (3) "teologických základů" a (4) "organizačních inspirací". Navazující "strategicko-praktická perspektiva" zachycená v kapitole šesté pak vše zaostřuje zpět do pastorační praxe tím, že navrhuje formulaci "vize synodálně chápané pastorační rady farnosti" a načrtává model "strategie podporovaného růstu" takovýchto pastoračních rad, který je "šitý na míru" pastoračnímu kontextu diecézí české církevní...
|
|
|
Study of hydrogen interaction with defects in thin metallic films
Hruška, Petr ; Čížek, Jakub (advisor) ; Krsjak, Vladimír (referee) ; Mathis, Kristián (referee)
Thin metallic films are particularly interesting as potential hydrogen storage materials as well as hydrogen sensitive optical sensors. Thin films with various microstructure from nanocrystalline to epitaxial can be relatively easily prepared by varying the deposition parameters. Deposition of multi-layers enables preparation of thin films with arbitrary composition. Defects structure plays a key role in hydrogen absorption. Hydrogen atoms segregated at open volume defects reduce their formation energy leading to enhan- ced concentration of hydrogen-induced defects in the material. Moreover hydrogen diffusion along dislocations and grain boundaries facilitates hydrogen absorption in the metal lattice. Thin films clamped to the stiff substrate undergo anisotropic volume expansion during the hydrogen loading. As a consequence high stresses are induced in the film and can result in detachment of the film from the substrate. In this work hydrogen absorption in Gd and Pd films and Pd-Mg multi-layers was studied. Development of the defect structure of hydrogen-loaded films was investigated by means of variable energy positron annihilation spectroscopy com- bined with X-ray diffraction, atomic force microscopy and optical transmittance measurement. Complementary studies of interaction of hydrogen with defects in...
|
|
|
Impact of lattice distortions on physical properties of high entropy alloys
Starý, Dominik ; Čížek, Jakub (advisor) ; Hruška, Petr (referee)
This bachelor thesis is focused on a group of mostly high entropy alloys, composed of metals Cr, Cu, Hf, Fe, Mo, Nb, Ni, Ta, Ti, V, Zr, Co and Al, and their properties studied by scanning electron microscopy, Vickers hardness test and positron lifetime spectroscopy. One of the high entropy alloys' characteristic properties is a presence of local lattice distortion, the magnitude of which is commonly estimated by δr parameter. Based on Vickers hardness test, positive and statistically significant correlation between alloys' microhardness and δr parameter was evaluated. Estimated value of Pearson correlation coefficient is 0,5(1) and obtained p-value is of order 10−4 . That is below significance level 0,05. Based on positron lifetime spectroscopy, it was found out, that positron lifetime and δr parameter are not significantly correlated. 1
|
|
|
Study of the structure and properties of black aluminium thin films prepared by magnetron sputtering
Prokop, Dejan ; Hruška, Petr (advisor) ; Čížek, Jakub (referee)
Black metallic thin films are characterized by their excessively rough fractal-like surface structure. Furthermore, black metal films have a much bigger surface- to-volume ratio compared to classic reflective metals. Therefore, they can be used e.g. as a basis for optical or chemical sensors. In the present bachelor thesis, we study and pro- vide a comparison between the properties of reflective and black thin films with thickness in the range of 50-700 nm prepared by pulsed DC magnetron sputtering. A small amount of nitrogen that is introduced during deposition to a chamber is responsible for a change in the structure and the growth of the black films. Different surface morphology is studied using a contact profilometer, atomic force microscope and scanning electron microscope. The measurements obtained by these instruments provide valuable information regarding the overall surface structure and means of growth. The surface roughness, as well as the mean crystallite size was observed to increase with the thickness of the films. The X-ray diffraction analysis shows that both types of film crystallize in the face-centered cubic crystal structure. Spectrophotometrical measurements of specular reflectance pro- vide quantitative information about the optical properties. The ultraviolet, visible and near-infrared...
|
|
|
Study of the structural changes of thin films by in-situ spectrophotometry
Jakubik, Matej ; Hruška, Petr (advisor) ; Čížek, Jakub (referee)
The focus of this bachelor thesis was on modifying vacuum chamber to study two different physical topics. First was the absorption of hydrogen in metals. Hydrogen ab- sorption was studied on palladium thin films. Palladium was chosen thanks to its high kinetics of hydrogen absorption at room temperature, which leads palladium to be the model system to study hydrogen absorption. Using optical measurement one can study hydrogen absorption for thin films. From the results of optical transmittance measure- ment, it is possible to study the change of atomic ratio between hydrogen and palladium, i.e. phase transformation. The second topic will be the study of the dependence of vari- ous conditions (initial temperature of sample, pressure) on the energy of laser pulse on laser-induced dewetting, i.e. structural changes in thin films caused by laser annealing. Minimal energy needed to initiate dewetting was calculated from one-dimensional heat equation. Minimal energy needed to initiate dewetting was tested implementing various initial temperatures and energy densities. 1
|
guest ::
RSS feed.