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Study of transverse velocity field in the vicinity of rotating wheel with assumption of forced convection of disc brake
Regner, Dominik ; Polanský, Jiří (referee) ; Štefan, David (advisor)
The master thesis deals with the influence of a local change of temperature due to advection from disc brake to axial velocity field close to the rotating wheel of a car. The second goal is to set parameters applicable to various wheel discs and study of the influence of these parameters to aerodynamical properties of car and thermodynamical properties of the disc brake. The thesis is numerically executed in StarCCM+. The first part focuses on theoretical background about the numerical solution and current status of research. There are described disc parameters, geometry input and solver settings in the second part. The final part deals with a comparison of velocity fields for isothermal and thermodynamical model and evaluates the influence of parameters to velocity field, aerodynamical drag and thermodynamical performance of the brake.
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Study of transverse velocity field in the vicinity of rotating wheel with assumption of forced convection of disc brake
Regner, Dominik ; Polanský, Jiří (referee) ; Štefan, David (advisor)
The master thesis deals with the influence of a local change of temperature due to advection from disc brake to axial velocity field close to the rotating wheel of a car. The second goal is to set parameters applicable to various wheel discs and study of the influence of these parameters to aerodynamical properties of car and thermodynamical properties of the disc brake. The thesis is numerically executed in StarCCM+. The first part focuses on theoretical background about the numerical solution and current status of research. There are described disc parameters, geometry input and solver settings in the second part. The final part deals with a comparison of velocity fields for isothermal and thermodynamical model and evaluates the influence of parameters to velocity field, aerodynamical drag and thermodynamical performance of the brake.
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A DSGE Model with Financial Dollarization: the Case of Serbia
Djukić, Mirko ; Hlédik, Tibor ; Polanský, Jiří ; Trajčev, Ljubica ; Vlček, Jan
We amend a DSGE model of a small open economy by adding financial euroization in order to capture the main channels of the monetary transmission mechanism in match the Serbian data. In contrast to the standard DSGE workhorse, the model encompasses commercial banks and foreign-exchange-denominated deposits and loans. Given these features, the model is well suited to evaluating effects of the nominal exchange rate on the financial wealth and consumption of households. The model structure, including optimization problems and first-order conditions, is provided in the paper. The model properties are tested to match the stylized facts of dollarized economies. Specifically, the model is calibrated to the Serbian data, and a model-consistent multivariate filter is used to identify unobserved trends and gaps.
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High Efficiency Gas Turbine Recuperator
Hejčík, Jiří ; Lábaj,, Ján (referee) ; Polanský, Jiří (referee) ; Jegla, Zdeněk (referee) ; Jícha, Miroslav (advisor)
This thesis deals with the high efficiency gas turbine recuperator design and its production methods. First part of the work presents an analysis of basic constructions and materials used for present recuperators. The requirements on the recuperator for a low emission gas turbine power source are then specified and the recuperator is designed according to the available literature sources. The quality of the heat transfer surface is examined by CFD modeling using the commercial CFD code Star-CD. The second part deals with the recuperator manufacturing and experimental validation of the designed recuperator performance. This section describes ways to build the recuperator matrix, technologies available to assemble the recuperator and methodology of measurements. Experimental results are presented including a discussion of the uncertainties of determining individual variables. Finally the engineering equations are found based on the experimental data obtained, that can be employed to design the recuperator.
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Empirical Analysis of Labor Markets over Business Cycles: An International Comparison
Brůha, Jan ; Polanský, Jiří
The goal of this paper is to document and summarize the main cyclical features of labor market macroeconomic data in advanced countries. We report the second moments (correlations, coherences and volatility) of labor market variables for various data transformations (growth rates and cycles). Then we use dynamic factor models to inquire about the number of orthogonal shocks that drives labor market data dynamics. We also investigate the time-varying nature of these features: we ask whether they are stable over time, especially at times of severe crises such as the Great Recession. Finally, we compare these features across countries to see whether there are groups of countries characterized by similar features, such as labor market institutions. We find that certain features are stable over time and across countries (such as Okun’s Law), while others are not. We also confirm that labor market institutions influence selected characteristics, but to a limited degree only. We find that one or at most two orthogonal shocks seem to drive the cyclical dynamics of labor market variables in most countries. The paper concludes with our interpretation of these findings for structural macroeconomic models.
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The Housing Sector over Business Cycles: Empirical Analysis and DSGE Modelling
Brůha, Jan ; Polanský, Jiří
In this paper, we analyse the dynamics of the housing sector over business cycles. First, we provide an empirical analysis of the relationships between housing sector data and the main macroeconomic variables both on Czech data and on a sample of advanced economies. We document that in most countries the housing sector co-moves with the rest of the economy. In the past, the Czech housing market showed temporary episodes during which the housing sector was seemingly disconnected, but since 2005 the housing sector has become more cyclical. Second, we develop a cascade of increasingly complex DSGE models to assess the relative merits of each additional mechanism. Contrary to the popular framework with collateral constraints, we concentrate on the housing sector as an additional production sector via the standard supply and demand mechanisms. Our results confirm that these standard mechanisms are sufficient to replicate the observed comovements of housing market variables.
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Incorporating Judgments and Dealing with Data Uncertainty in Forecasting at the Czech National Bank
Brůha, Jan ; Hlédik, Tibor ; Holub, Tomáš ; Polanský, Jiří ; Tonner, Jaromír
This paper focuses on the forecasting process at the Czech National Bank with an empha- sis on incorporating expert judgments into forecasts and addressing data uncertainty. At the beginning, the core model and the forecasting process are described and it is presented how data and the underlying uncertainty are handled. The core of the paper contains five case studies, which reflect policy issues addressed during forecasting rounds since 2008. Each case study first describes a particular forecasting problem, then the way how the issue was addressed, and finally the effect of incorporating off-model information into the forecast is briefly summarized. The case studies demonstrate that a careful incor- poration of expert information into a structural framework may be useful for generating economically intuitive forecasts even during very turbulent times, and we show that such judgements may have important monetary policy implications.
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