Landau damping in the multiscale Vlasov theory

Vlasov kinetic theory is extended by adopting an extra one particle distribution function as an additional state variable characterizing the micro-turbulence internal structure. The extended Vlasov equation keeps the reversibility, the Hamiltonian structure, and the entropy conservation of the original Vlasov equation. In the setting of the extended Vlasov theory we then argue that the Fokker-Planck type damping in the velocity dependence of the extra distribution function induces the Landau damping. The same type of extension is made also in the setting of fluid mechanics

Ehrenfest regularization of Hamiltonian systems

Imagine a freely rotating rigid body. The body has three principal axes of rotation. It follows from mathematical analysis of the evolution equations that pure rotations around the major and minor axes are stable while rotation around the middle axis is unstable. However, only rotation around the major axis (with highest moment of inertia) is stable in physical reality (as demonstrated by the unexpected change of rotation of the Explorer 1 probe). We propose a general method of Ehrenfest regularization of Hamiltonian equations by which the reversible Hamiltonian equations are equipped with irreversible terms constructed from the Hamiltonian dynamics itself. The method is demonstrated on harmonic oscillator, rigid body motion (solving the problem of stable minor axis rotation), ideal fluid mechanics and kinetic theory. In particular, the regularization can be seen as a birth of irreversibility and dissipation. In addition, we discuss and propose discretizations of the Ehrenfest regularized evolution equations such that key model characteristics (behavior of energy and entropy) are valid in the numerical scheme as well

Extra mass flux in fluid mechanics

The conditions of existence of extra mass flux in single component dissipative non-relativistic fluids are clarified. By considering Galilean invariance we show that if total mass flux is equal to total momentum density, then mass, momentum, angular momentum and booster (center-of-mass) are conserved. However, these conservation laws may be fulfilled also by other means. We show an example of weakly non-local hydrodynamics where the conservation laws are satisfied as well although the total mass flux is different from momentum density

Hamiltonian Coupling of Electromagnetic Field and Matter

Reversible part of evolution equations of physical systems is often generated by a Poisson bracket. We discuss geometric means of construction of Poisson brackets and their mutual coupling (direct, semidirect and matched-pair products) as well as projections of Poisson brackets to less detailed Poisson brackets. This way the Hamiltonian coupling between transport of mixtures and electrodynamics is elucidated

Continuum Mechanics and Thermodynamics in the Hamilton and the Godunov-type Formulations

Continuum mechanics with dislocations, with the Cattaneo type heat conduction, with mass transfer, and with electromagnetic fields is put into the Hamiltonian form and into the form of the Godunov type system of the first order, symmetric hyperbolic partial differential equations (SHTC equations). The compatibility with thermodynamics of the time reversible part of the governing equations is mathematically expressed in the former formulation as degeneracy of the Hamiltonian structure and in the latter formulation as the existence of a companion conservation law. In both formulations the time irreversible part represents gradient dynamics. The Godunov type formulation brings the mathematical rigor (the well-posedness of the Cauchy initial value problem) and the possibility to discretize while keeping the physical content of the governing equations (the Godunov finite volume discretization)

Control systems of Kaplan Turbine

V této bakalářské práci je uvedeno stručné rozdělení nejužívanějších druhů vodních turbín, následně je obsažen důkladný rozbor konstrukce a především regulace Kaplanovy turbíny. Dále jsou v ní popsány jednotlivé mechanismy a pochody ve stroji při regulaci rozvaděčem a lopatami oběžného kola. Je zde poukázáno také na to, jaký vliv má regulace na průběh účinnosti turbíny. V závěru práce je čtenáři nastíněno stručné vysvětlení a srovnání moderního řízení regulace stroje s dříve používaným řízením regulace pomocí hydraulických roztěžníků.The main objective of this bachelor´s thesis is to list briefly the most common types of water turbines and explain the construction and especially regulation of Kaplan water turbine. Second task is to describe individually both regulatory mechanisms and movements in the machine during the regulation by distributor and by blades of runner wheel. The next intention is to describe the influence of regulation on the efficiency curve and further briefly explain and compare the modern control systems of turbine regulation with the old way using the centrifugal regulator.

Scientific Web Portal Generator

Generátor vědeckých webových portálů je rozsáhlý projekt, jehož cílem je vytvoření systému, který umožní budování webových portálů za účelem poskytování přehledu vědeckých prací z konkrétních oblastí. Jednou z částí tohoto projektu je i modul pro vyhledávání domovských stránek autorů publikací. Cílem této bakalářské práce je implementace právě tohoto modulu formou skriptu nebo programu. Náplní mé práce je nalezení vhodné metody extrakce sémantické informace ze značkovaného textu, návrh a vývoj systému, který tuto metodu realizuje a sestavení množiny, na které bude systém otestován. Výstupem bakalářské práce je prototyp programu nebo skriptu, který na základě vstupního souboru ve formátu XML se jmény vědeckých pracovníků vygeneruje výstupní XML soubor s URL adresami na jejich domovské stránky a stránky se seznamem publikací. Převážná část mé práce je věnována důkladné analýze daného problému z různých hledisek, rozčlenění na podproblémy a výběru nejvhodnějších variant řešení.Scientific web portal generator is a large project. It's purpose is to create a system for building web portals for providing the view of science publications of authors. One of the parts of this project is module for searching of homepages. The goal of this bachelor's thesis is the implementation of of this module using the program or script. Content of this thesis is to find the best way of method of extraction the semantic information from the marked text, design and development o the system and creating the test set for the purpose of testing. The output of this thesis should be prototype of program or script, which will generate XML file with the URL adresses of homepages of authors. System should have XML input. Almost entire thesis is about analyzing of this problem and choosing the best solution.

Remediation of Sign Texts as the Theme of Cultural Studies

Sign texts hide different versions of cultural reality, in whose creation and interpretation are involved their producers and consumers. The problem is what role in the processes of text interpretation constructing cultural realities plays remediation as a transport of texts from one communication medium into another. The study aims to find out what role in the processes of cultural practices plays remediation of visual sign texts and what changes in the mediated contents causes remediation of visual sign texts? The study aims to reflect the fact that the socio-cultural reality is presented, constructed and stored in the processes of cultural practices, which is an essential component of remediation and interpretation of sensate sign texts and to analyze selected visual texts with the intention to identify changes that causes remediation carried out by different communication media. In context of textual approaches of cultural studies the study uses qualitative methods – semiotic, narrative and discourse analysis of visual sing text. The study analyzes selected visual sign texts that carry different communication media, among other artistic collage, poster, exhibition catalog, illustration in a popular science book, and e-mail. The study showed that the remediation of visual texts is an instrument of semiotic and cultural transfer, is initiated by socio-cultural practices and brings changes in contents of sign texts. It further showed that the remediation is simultaneously the bearer of cultural traditions and initiator of cultural changes since ancient times. Interpretation of selected visual texts concluded that remediation is a basic condition for reproduction of cultural values, norms and myths as elementary forms of cultural integration and that remediation in the context of contemporary cultural studies is not only an important research topic, but also the research problem that has not been sufficiently thoroughly theoretically nor practically processed.Sign texts hide different versions of cultural reality, in whose creation and interpretation are involved their producers and consumers. The problem is what role in the processes of text interpretation constructing cultural realities plays remediation as a transport of texts from one communication medium into another. The study aims to find out what role in the processes of cultural practices plays remediation of visual sign texts and what changes in the mediated contents causes remediation of visual sign texts? The study aims to reflect the fact that the socio-cultural reality is presented, constructed and stored in the processes of cultural practices, which is an essential component of remediation and interpretation of sensate sign texts and to analyze selected visual texts with the intention to identify changes that causes remediation carried out by different communication media. In context of textual approaches of cultural studies the study uses qualitative methods – semiotic, narrative and discourse analysis of visual sing text. The study analyzes selected visual sign texts that carry different communication media, among other artistic collage, poster, exhibition catalog, illustration in a popular science book, and e-mail. The study showed that the remediation of visual texts is an instrument of semiotic and cultural transfer, is initiated by socio-cultural practices and brings changes in contents of sign texts. It further showed that the remediation is simultaneously the bearer of cultural traditions and initiator of cultural changes since ancient times. Interpretation of selected visual texts concluded that remediation is a basic condition for reproduction of cultural values, norms and myths as elementary forms of cultural integration and that remediation in the context of contemporary cultural studies is not only an important research topic, but also the research problem that has not been sufficiently thoroughly theoretically nor practically processed