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Optimization of properties of Ti based alloys for biomedical and structural applications
Stráský, Josef ; Janeček, Miloš (advisor) ; Hadzima, Branislav (referee) ; Karlík, Miroslav (referee)
Title: Optimization of properties of Ti based alloys for biomedical and structural applications Author: Josef Stráský Department / Institute: Department of Physics of Materials Supervisor of the doctoral thesis: Assoc. Prof. Miloš Janeček, Ph.D. Abstract: Titanium alloys belong to the mostly used biomaterials for orthopaedic implants. Advanced surface treatments of Ti alloys for orthopaedic use and newly developed biomedical beta-Ti alloys are investigated in this thesis. Wide spectrum of experimental techniques was employed in order to correlate material processing, microstructure and mechanical properties. Electric discharge machining was used as a biocompatibility enhancing surface treatment of Ti-6Al-4V alloy, but the treated material suffered from the poor fatigue performance. Two subsequent surface treatments - chemical etching and shot- peening - were proposed and it was shown that their combination significantly improves the fatigue performance of the material making it applicable in orthopaedics. This process was patented in the Czech Republic. The thesis further reviews complex problematic of biocompatible beta-Ti alloys. Several new biocompatible beta-Ti alloys were designed on the basis of Ti-Nb-Zr-Ta quaternary alloy. The effect of Fe, Si and O additions on microstructure, elastic modulus and...
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Experimentální studium ultrajemnozrnných slitin Ti pro využití v biomedicíně
Václavová, Kristína ; Stráský, Josef (advisor) ; Šíma, Vladimír (referee)
In the present work the microstructure evolution of Ti-6Al-7Nb alloy prepared by high pressure torsion (HPT) and equal channel angular pressing (ECAP) was studied by scanning electron microscopy, microhardness measurements and electrical resistance measurements. Electron microscopy showed a bimodal structure of the alloy and deformed structure after HPT. Microhardness increased with the increasing number of turns of high pressure torsion. Electron back-scattered diffraction figured out that the grain misorientations are not random. Changes in the electrical resistance of the alloy prepared by ECAP showed irreversible process after heating above 450řC.
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Zeeman effect in semiconductor quantum structures
Stráský, Josef
This theoretical thesis presents detailed study of negatively charged excitons - trions - confined in single quantum well in presence of perpendicular magnetic field. Complex valence band of GaAs/GaAlAs compound is described within Luttinger Hamiltonian framework. Singlet and triplet states of negative trion are introduced. Advanced theoretical analysis of Zeeman effect for different states of trion is performed. Landau gauge of magnetic field and unusual wavefunctions basis is chosen and its accuracy is tested. Evolution of ground state energy and photoluminescence spectra with magnetic field is evaluated for different values of Landé g-factors. Probability of occurrence of electrons with respect to the hole position and their spatial correlation function are investigated.
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Modeling of government spending and endogenous tax rates in New Keynesian models : the case of Czech Republic
Zelený, Tomáš ; Stráský, Josef (advisor) ; Mertlík, Pavel (referee)
The topic of fiscal policy has been long neglected in terms of fiscal policy's interdependence with other main macroeconomic variables. Presented thesis therefore analyses the validity of different fiscal policy models for the case of Czech Republic. Dynamic stochastic general equilibrium (DSGE) framework is used throughout the thesis. Different fiscal policy rules are put into otherwise identical - benchmark - model and the models are compared to each other and to the benchmark model. The analysed fiscal policy models are an acyclical, counter- cyclical, two pro-cyclical and dichotomous spending models. We find that the most plausible fiscal policy rule is of pro-cyclical type and closely follows the model of Alesina et al. (2008). The model assumes that interest groups can steal part of government income through corruption and voters cannot observe it, so they demand maximum fiscal spending in the good times. The logic of this model is in accordance with the current state of fiscal and economic behaviour in Czech Republic.
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Housing financing support
Marková, Diana ; Hlaváček, Michal (advisor) ; Stráský, Josef (referee)
This thesis presents the system of housing financing support generally in the context of European countries and concretly in the Czech Republic. First, the housing market and the specificity of housing as a good are presented. Next, the thesis describes taxation in relation to housing and the influence of taxation on affordability of housing. The main part of the thesis is devoted to general concept of housing policy and overview of the instruments of housing financing support, which is followed by concrete example of the Czech Republic. The overview of the instruments in the Czech Republic is followed by an attempt to estimate their impact to the state and public budgets. The situation in the Czech Republic was wery interesting because of the started application of the new concept from 2011, which changed the direction of the housing policy and the portfolio of instruments. Almost at the end of the thesis, there is briefly presented the model of real estate market by DiPasquale and Wheaton. According to this model it is possible to make a statistic comparative analysis of the impacts of some instuments of housing financing support on the real estate market. The knowledge, acquired during the work on the thesis, is used in the last chapter to prepare the SWOT analysis and evaluation of the current portfolio...
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Can Bayesian econometric methods outperform traditional econometrics in inflation forecasting?
Stráský, Josef ; Baxa, Jaromír (advisor) ; Netuka, Martin (referee)
Forecasting of inflation has become crucial for both policy makers and private agents who try to understand and react to Central Bank decisions because many Central Banks implemented inflation targeting rules instead of control of monetary aggregates. Inflation forecasting is considered to be very complicated issue because univariate regression models and structural macroeconomic models are usually outperformed by naive random walk model. This work is intended for forecasting inflation in the Czech Republic by employing Bayesian econometric method (namely Bayesian vector autoregression - BVAR). Bayesian methods proved to be useful in inflation forecasting in developed countries (Fabio Canova: G-7 Inflation Forecasts: Random Walk, Phillips Curve or What Else?, 2007). Bayesian econometrics is one of the fast developing fields of econometrics for past two decades. In the centre of the approach is Bayesian probabilistic theory based on conditional probabilities. This probabilistic approach is, however, computationally demanding. Fast computer evolution enables wide applications of Bayesian models. Model estimations are based on combining information from some prior beliefs and from the data. Many different sorts of models have their Bayesian variants (e.g. OLS) but the emphasis in this work is on Bayesian...
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Zeemanův jev v polovodičových kvantových strukturách
Stráský, Josef ; Grill, Roman (advisor) ; Výborný, Karel (referee)
This theoretical thesis presents detailed study of negatively charged excitons - trions - confined in single quantum well in presence of perpendicular magnetic field. Complex valence band of GaAs/GaAlAs compound is described within Luttinger Hamiltonian framework. Singlet and triplet states of negative trion are introduced. Advanced theoretical analysis of Zeeman effect for different states of trion is performed. Landau gauge of magnetic field and unusual wavefunctions basis is chosen and its accuracy is tested. Evolution of ground state energy and photoluminescence spectra with magnetic field is evaluated for different values of Landé g-factors. Probability of occurrence of electrons with respect to the hole position and their spatial correlation function are investigated.
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Can Bayesian econometric methods outperform traditional econometrics in inflation forecasting?
Stráský, Josef ; Netuka, Martin (referee) ; Baxa, Jaromír (advisor)
Forecasting of inflation rates has become crucial for both policy makers and private agents who try to understand and react to Central Bank decisions since many Central Banks implemented inflation targeting rules instead of control of monetary aggregates. Inflation forecasting is considered to be very complicated issue because univariate regression models and structural macroeconomic models are usually outperformed by naive random walk model. This work is intended for forecasting inflation in the Czech Republic by employing Bayesian econometric method (namely Bayesian Vector autoregression - BVAR). Bayesian methods proved to be useful in inflation forecasting in developed countries (Fabio Canova: G-7 Inflation Forecasts: Random Walk, Phillips Curve or What Else?, 2007). Bayesian econometrics is one of the most developing fields of econometrics for past two decades. In the centre of the approach is Bayesian probabilistic theory based on conditional probabilities. This probabilistic approach is, however, computationally demanding. Fast computer evolution enables wide applications of Bayesian models. Model estimations are based on combining information from some prior beliefs and from the data. Many different sorts of models have their Bayesian variants (e.g. OLS) but the emphasis in this work is on Bayesian...
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Forecasting the Exchange Rate in the Czech Republic Using Non-linear Threshold Models
Žák, Petr ; Stráský, Josef (advisor) ; Kočenda, Evžen (referee)
The aim of this thesis is to analyze the performance of nonlinear threshold models in forecasting the exchange rate of Czech koruna against EUR. Data for this study were obtained from Statistical Data Warehouse of European Central Bank (ECB) website, from Czech National Bank (CNB) Board decisions minutes and from the press releases of Governing Council of ECB. The data set was split into two periods - from 1999 until November, 2013 when CNB started to use interventions and from November, 2013 until April, 2016. Models used in the thesis are Self-Exciting Threshold Auto Regressive (SETAR) models with one and two thresholds and two Threshold Auto Regres- sive (TAR) models with different threshold variables - meetings of CNB Board as dummy variable and average volatility over recent periods. The forecasting results indicate that SETAR models did not outperform Random Walk in any period. TAR models offered promising results in the period before interventions and surprisingly failed in the period during interventions. This study supports the general belief of exchange rates being difficult to forecast and that it holds in case of Czech koruna as well. JEL Classification F12, F21, F23 H25, H71, H87 Keywords forecasting, exchange rate, time series, nonlin- earity, SETAR, TAR Author's e-mail zaka.one@gmail.com...
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