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The entry of JAF HOLZ Co. the Czech market
Němec, Tomáš ; Halík, Jaroslav (advisor) ; Havelka, Josef (referee)
The first chapter introduces the most important forestry business organization in our country. The second chapter talks about the company itself entering the Czech market. The third chapter provides a disassembly of customer service company. In the fourth chapter I compare two major while competing products of the company.
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Public-private partnerships and their praxis in EU member states
Sisková, Monika ; Němcová, Ingeborg (advisor) ; Němec, Tomáš (referee)
The aim of this final thesis is to analyse and compare the PPP practices of EU member states and to evaluate the current situation of their PPP markets as well as the issues faced at present. The study consists of four chapters. The first chapter deals with the theoretical and legal concept of public-private partnerships: the definition of PPPs, their characteristics, advantages and disadvantages of PPPs and the factors influencing the success of PPP projects. The section thereafter analyses the position and role of the EU, EIB and EBRD in promoting and supporting the implementation of PPP projects. The section is followed by an assessment of the PPP market development trend, high lightening the basic quantitative differences between the EU member states. Chapter four forms the core of this thesis in which, based on specified criteria (legal and institutional PPP conditions, average value of a project, corruption, transparency and the nature of the public sector) the PPP praxis of Great Britain, Italy, Greece, Sweden, Poland and Slovakia are analysed and compared. The states are characterized by national PPP markets of diverse quality as well as significant differences in the national conditions for implementing PPP projects.
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Nucleation rate in binary cavitating systems - A comparison of experimental data and classical nucleation theory predictions
Němec, Tomáš
A brief review of recent literature on proton exchange membrane fuel cell (PEMFC) modelling is presented and the governing equations of the transport processes in the proton exchange membrane are presented. Consequently, the model of water transport in the membrane electrode assembly of a fuel cell in commercial software FLUENT is investigated. The aim of this work is to test the possibilities of the PEMFC modelling using FLUENT. Special attention is given to the water management and the properties of the fuel cell membrane.of four binary mixtures, i.e. diethylether - nitrogen, propane - carbon dioxide, isobutane - carbon dioxide, and chlorodifluoromethane - carbon dioxide. The predictions of the classical nucleation theory show very good agreement with the measured nucleation rates.
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Modelling of water transport in the polymer electrolyte membrane of a fuel cell
Šimek, M. ; Němec, Tomáš ; Maršík, František
A brief review of recent literature on proton exchange membrane fuel cell (PEMFC) modelling is presented and the governing equations of the transport processes in the proton exchange membrane are presented. Consequently, the model of water transport in the membrane electrode assembly of a fuel cell in commercial software FLUENT is investigated. The aim of this work is to test the possibilities of the PEMFC modelling using FLUENT. Special attention is given to the water management and the properties of the fuel cell membrane.of four binary mixtures, i.e. diethylether - nitrogen, propane - carbon dioxide, isobutane - carbon dioxide, and chlorodifluoromethane - carbon dioxide. The predictions of the classical nucleation theory show very good agreement with the measured nucleation rates.
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Klasická nukleační teorie a modelování kavitačních jevů
Němec, Tomáš
The description of the nucleation of bubbles and their growth in cavitation processes suitable for computational fluid dynamics (CFD) simulations is investigated. The number of newly created bubbles and their sizes are treated empirically in most of the numerical codes. We show that the Classical Nucleation Theory (CNT) can be used to calculate the nucleation probabilities in water. Also a simple model of the growth of the nucleated bubbles is described. The CNT predictions of the nucleation rate show promising results and together with the bubble growth model can be used to enhance the precision of CFD modeling of cavitating flows.
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Microscopic Surface Tension in the Classical Nucleation Theory
Němec, Tomáš ; Maršík, František
The surface tension of liquid clusters in the Classical Nucleation Theory (CNT) is investigated using the Gibbs adsorption isotherm. A theoretical derivation is given that shows the relation between macroscopic (plain-surface) surface tension and the surface tension of microscopic spherical clusters of the CNT. An exemplary water – ethanol binary condensing system is studied. It is shown that by using the microscopic surface tension in nucleation calculations an exceptional agreement between theoretical and experimental nucleation rates is achieved.
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Nucleation theory for the description of cavitation in water
Němec, Tomáš ; Maršík, František
The Classical Nucleation Theory (CNT) is a powerful tool for the description of nucleation processes whose development started more than a century ago. It proved its strength above all in dealing with the condensation phenomena, and it is quite accurate when describing not only the nucleation in pure water vapor but also evaluating the influence of admixtures, e.g. sulfuric acid, alcohols, mineral salts. Such a multicomponent approach was not yet applied in the case of cavitation processes; the CNT predictions are restricted to pure water, and the role of other components of the cavitating medium are implemented ad-hoc. This paper describes the influence of a gas dissolved in water (e.g. oxygen, nitrogen, carbon dioxide) on the nucleation process in cavitation.
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