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Thermodynamic 1-D model of the turbocharger of an internal combustion engine
Mrázková, Kristýna ; Böhm, Michael (referee) ; Štětina, Josef (advisor)
The thesis deals with 1D heat transfer simulation of turbine housing laying emphasis on temperature of exhaust gas leaving the turbine. The thesis covers construction and thermodynamics of turbochargers, SCR catalysts and 1D simulation software. Then the thesis focuses on exploring turbine housing 3D model discretization, building physical turbocharger model for 1D simulation of heat transfer through turbine housing with time dependent input values and predicting temperature of exhaust gas flowing through turbine outlet in compliance with NEDC cycle. Result analysis and a suggestion of subsequent actions follow.
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Thermodynamic modelling of hydrogen fuel cells
Nováček, Marek ; Pavelka, Michal (advisor) ; Němec, Tomáš (referee)
In this thesis, proton exchange membrane fuel cells are studied. At the beginning, the ideas underlying their function are exposed and some possibilities of usage are pre- sented. Thereafter, we aim to describe the processes inside the fuel cells with the aid of thermodynamics and in agreement with constitutive relations that have been obtained experimentally. Namely, we are interested in the fluxes of water and protons inside the membrane, where they are acted upon by thermodynamic forces, and the electrochemical reactions at the electrodes, which can be described by the Butler-Volmer equations. Also do we study the efficiency of the fuel cell by evaluating the production of entropy due to the diverse processes that take place in the fuel cell. It is the goal of the computational part of this thesis to propose a zero-dimensional model and compare it with the results provided in the supervisor's doctoral thesis. 1
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Mineral assemblages, alteration reactions and transport model of the greisen formation in the Horní Blatná granite pluton, Krušné hory Mts.
Heřmanská, Matylda ; Dolejš, David (advisor) ; Štemprok, Miroslav (referee)
English abstract Hydrothermal systems related to highly evolved granitic magmas host diverse mineralization styles and provide an important source of economic metals. This master thesis concentrates on description and interpretation of geological structure, petrographic and textural variability, alteration zoning and calculation of time-integrated fluid fluxes recorded in highly evolved granites and tin-mineralized greisens of the Horní Blatná massif in the Western Krušné hory pluton. The massif is a composite intrusion, which consists of a large number of intrusive units emplaced during two stages. The first stage is represented by sparsely porphyritic fine-grained low-lithian annite granites that can be correlated with marginal granites (G2) of the Fichtelgebirge (Smrčiny) batholith or with intermediate granites (Walfischkopf type) of the Western Krušné hory (Erzgebirge) pluton. Intrusive batches of the second stage progressively evolve from medium- to coarse-grained serial high-lithian annite and zinnwaldite granites with topaz and rare tourmaline towards aphyric fine-grained zinnwaldite (or trilithionite) granites. This suite corresponds to the EIB2 and EIB3 facies of the younger intrusive complex in the Western Krušné hory (Erzgebirge) pluton and it can be compared to the G3 Waldstein and G4 units in...
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The Nature of Entrepreneurship: Society, the Individual and the Firm
Kapustin, Victor ; Benáček, Vladimír (advisor) ; Balcar, Petr (referee)
Entrepreneurship is often perceived as a crucial component of economic growth and social development. Studies into entrepreneurship inform policy design, thus the diverse understanding of entrepreneurship among scholars can create confusion in policy design. The current state of the field of entrepreneurial research is examined in order to identify the need for a universal definition of entrepreneurship. After a synthesis and analysis of prior research is conducted to identify the various links in perspectives, a new definition and framework is suggested. The resulting framework sees entrepreneurship as an autocatalytic process of creation of meaning and the consequent retention of said meaning in the structure of a new venture. The elements of this framework (autocatalytic process, creation of meaning, and retention in structure) can be assigned varying degrees of importance corresponding to differing perspectives, while simultaneously ensuring the presence of each element. The developed framework can be used to better inform the decisions of scholars and policy makers, due to the uncovering of the complex relationships between society, individuals and firms.
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Termodynamická analýza procesů v polymerní elektrolytické membráně palivového článku
Pavelka, Michal ; Maršík, František (advisor) ; Málek, Josef (referee)
Thermodynamic analysis of processes in electrolytic fuel cell membrane Michal Pavelka April 12, 2012 Abstract Hydrogen fuel cells1 may become a key technology of 21st century, and it is important to be able to describe their behavior, therefore. In this work we focus on hydrogen fuel cells with a polymer-electrolyte membrane. For the membrane we adopt an existing model2 . We for- mulate the model in the framework of the mixture theory which we develop similarly as has been done in the classical textbook of Mazur and de Groot3 . However, refining the concept of potential energy of a material point, we introduce new terms called internal potential ener- gies which enable us to describe macroscopic consequences of internal forces between water and polymer in the membrane and to describe the influence of gradient of surface tension of water in the membrane. We solve the model in 1D approximation. Consequently, we calculate the influence processes in the membrane have on efficiency of the fuel cell. 1 see for example Larminie, J. and A. Dicks. Fuel Cell Systems Explained. 2nd edition. John Wiley & Sons Ltd., 2003. ISBN 0-470-84857-X. 2 Weber, A. Z. and J. Newman. Transport in Polymer-Electrolyte Membranes I, II, III. J. Electrochem. Soc., 150 (7), A1008-A1015, 2003; 151 (2), A1311-A1325, 2004.; 151 (2), A1326-A1339,...
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Study of structural features of single stranded DNA by biophysical techniques and crystallography
Svoboda, Jakub ; Schneider, Bohdan (advisor) ; Pavlíček, Jiří (referee)
DNA is the fundamental molecule in all domains of life, its role in heredity is well established. Although the famous double helical complementary form is indispensable for replication mechanism DNA can occupy wide range of conformations. In the past studies performed in the laboratory, DNA oligomers related to single stranded bacterial Repetitive Extragenic Palindromic (REP) showed spectral behavior suggesting complex equilibria including double helical, hairpin, and tetraplex conformations. The studies presented in this thesis extended the scope of analyzed sequences and employed circular dichroism spectroscopy and X-ray crystallography. We report spectral data and X-ray structures of three successfully crystalized oligonucleotides. All three structures acquire double helical architecture with two consecutive T- T mismatches in the center. To improve the convergence of the refinement process of the crystal structures we used novel dinucleotide conformational classes, NtC classes. The NtC class classification was also used to analyze geometries of selected non-canonical base pairs in all DNA crystal structures in the Protein Data Bank. We measured the fit between geometries of the dinucleotides involved in the non-canonical base pairing and the NtC classes and correlated this fit to the electron...
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Interactions of Proteins with Nucleic Acids: from Structure to Specificity
Jakubec, Dávid ; Vondrášek, Jiří (advisor) ; Šponer, Jiří (referee) ; Zagrovic, Bojan (referee)
Sequence-specific interactions between proteins and nucleic acids play an essential role in the cell biology. While several molecular mechanisms contributing to the binding speci- ficity have been identified empirically, no general protein-DNA recognition code has been described to date. In this thesis, I explore selected characteristics of protein-DNA inter- actions using computational methods. First, the pairwise interactions between the basic biomolecular building blocks-amino acids and nucleotides-are investigated. It is shown that several statistically enriched, biologically relevant interaction motifs correspond to the most energetically favorable configurations of the respective binding partners. In ad- dition, a relationship between the physico-chemical properties of the amino acid residues found at the protein-DNA interface and the local geometric features of the DNA helix is presented. Next, the applicability of molecular dynamics-based setups to the description of binding equilibria in protein-DNA systems is investigated. Discrepancies are observed between the description offered by the computer simulations and experimental results, as well as between the results obtained using two molecular mechanical force fields. Finally, the more general evolutionary aspects of protein organization...
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Thermodynamic modelling of hydrogen fuel cells
Nováček, Marek ; Pavelka, Michal (advisor) ; Němec, Tomáš (referee)
In this thesis, proton exchange membrane fuel cells are studied. At the beginning, the ideas underlying their function are exposed and some possibilities of usage are pre- sented. Thereafter, we aim to describe the processes inside the fuel cells with the aid of thermodynamics and in agreement with constitutive relations that have been obtained experimentally. Namely, we are interested in the fluxes of water and protons inside the membrane, where they are acted upon by thermodynamic forces, and the electrochemical reactions at the electrodes, which can be described by the Butler-Volmer equations. Also do we study the efficiency of the fuel cell by evaluating the production of entropy due to the diverse processes that take place in the fuel cell. It is the goal of the computational part of this thesis to propose a zero-dimensional model and compare it with the results provided in the supervisor's doctoral thesis. 1
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