|
|
Modal Analysis of the Swirl Turbine Rotor Blades
Pekar, Marek ; Chromek, Lukáš (referee) ; Lošák, Petr (advisor)
The aim of this diploma thesis is to determine and compare modal properties of four swirl turbine wheels, each with a different geometry. Natural frequencies and mode shapes were obtained based on computer modelling using Ansys software and they were compared with experimental modal analysis' results. The computer modelling and the experimental modal analysis were carried out for different boundary conditions and in different environments. The beginning of the thesis is dedicated to a brief overview of literature with similar issues. Then a brief introduction of a dynamics theory is mentioned in which equations of motion for a damped and an undamped single degree of freedom system are derived. The creation of a geometry model which is obtained by a reverse engineering is shown in the second part of the thesis. The geometry model was subsequently used for the computer based modelling of the modal parameters. In the third part an experimental equipment, setting, measurement and processing of data are described. The conclusion of the thesis is dedicated to the comparison of the results obtained by the experimental modal analysis and the computing modelling is presented. Moreover, influence of boundary conditions and influence of the environment on the natural frequencies are evaluated.
|
|
|
Laboratory astrochemistry and applications of computer simulations
Roučka, Štěpán ; Hrach, Rudolf (advisor) ; Bonaventura, Zdeněk (referee) ; Novák, Stanislav (referee)
This work is focused on laboratory studies of ion chemistry at conditions relevant for astrophysics. The three main outcomes of the thesis are: (1) The experimental study of the reaction rate coefficient of the associative detachment reaction H- + H -> H2 + e-; measurement of the thermal rate coefficient at the temperatures in the range 10-135 K is described. (2) The design of a novel apparatus for detecting the electrons produced in the RF trap and measuring their energy; numerical simulations and preliminary experimental results are presented. (3) The development of a model of the electron cooling in the afterglow plasma and the application of the model in the analysis of the H3+ recombination measurements.
|
|
|
Theoretical study of enzymes related to carcinogenesis: DNA polymerase β and cytochromes P450
Jeřábek, Petr ; Martínek, Václav (advisor) ; Entlicher, Gustav (referee) ; Ettrich, Rüdiger (referee)
Present doctoral thesis contributed to understanding of mechanistic principles of two enzymes participating in the process of carcinogenesis; DNA polymerase (pol ) and cytochromes P450 (CYP). Pol is part of the DNA base-excision repair mechanism (BER). The primary role of pol in, the BER mechanism, is inserting a new nucleotide into a DNA strand according to Watson-Crick base pairing rules. Pol plays an important role in the process of carcinogenesis, approximately 30 % of human tumors express pol mutants. The ability of pol to discriminate between "right" and "wrong" nucleotide during the insertion process is called fidelity. We employed computational methods to elucidate molecular basis of the fidelity of pol . First, the relative free energy calculation method LRA was employed to compare differences in free energies between the "right" and "wrong" nucleotide during its insertion into DNA. The results indicated a better stabilization of transition-state of the nucleophilic substitution catalyzed by pol in the case of the "right" versus "wrong" nucleotide. This difference resulted in an 80-fold contribution to its fidelity. Further, computational methods FEP and LIE were used to examine how mutations effect fidelity of pol . Results were than correlated with experimental data...
|
|
|
Laboratory astrochemistry and applications of computer simulations
Roučka, Štěpán ; Hrach, Rudolf (advisor) ; Bonaventura, Zdeněk (referee) ; Novák, Stanislav (referee)
This work is focused on laboratory studies of ion chemistry at conditions relevant for astrophysics. The three main outcomes of the thesis are: (1) The experimental study of the reaction rate coefficient of the associative detachment reaction H- + H -> H2 + e-; measurement of the thermal rate coefficient at the temperatures in the range 10-135 K is described. (2) The design of a novel apparatus for detecting the electrons produced in the RF trap and measuring their energy; numerical simulations and preliminary experimental results are presented. (3) The development of a model of the electron cooling in the afterglow plasma and the application of the model in the analysis of the H3+ recombination measurements.
|
|
|
Modal Analysis of the Swirl Turbine Rotor Blades
Pekar, Marek ; Chromek, Lukáš (referee) ; Lošák, Petr (advisor)
The aim of this diploma thesis is to determine and compare modal properties of four swirl turbine wheels, each with a different geometry. Natural frequencies and mode shapes were obtained based on computer modelling using Ansys software and they were compared with experimental modal analysis' results. The computer modelling and the experimental modal analysis were carried out for different boundary conditions and in different environments. The beginning of the thesis is dedicated to a brief overview of literature with similar issues. Then a brief introduction of a dynamics theory is mentioned in which equations of motion for a damped and an undamped single degree of freedom system are derived. The creation of a geometry model which is obtained by a reverse engineering is shown in the second part of the thesis. The geometry model was subsequently used for the computer based modelling of the modal parameters. In the third part an experimental equipment, setting, measurement and processing of data are described. The conclusion of the thesis is dedicated to the comparison of the results obtained by the experimental modal analysis and the computing modelling is presented. Moreover, influence of boundary conditions and influence of the environment on the natural frequencies are evaluated.
|
|
|
Computer modelling in programming language COMSOL Multiphysics
MÁCHA, Václav
The thesis deals with a computer modelling by means of the commercial software COMSOL Multiphysics. The thesis is structured into three topical sections. The first part is dedicated to the programme characteristics and its development. In the second part the brief characteristics of working with the programme COMSOL Multiphysics is presented which should make the user´s first steps in working with software easier. The last part of thesis shows the specific demonstration of the created multiple physics task taken from the field of plasma physics. This task is solved by means of continuous simulation of a computer modelling based on the drift-diffusion approximation of low temperature plasma. The proposal of the paper for the proceedings of the conference ,,Technical Computing Prague 2012" is also a part of this thesis.
|
|
|
Preparation of web presentation on fundamental conceptions in computer physics
KŘÍŽOVÁ, Jaroslava
This Bachelor's Thesis has undertaken to acquaint high school students with basic information in the field of computer physics. The work is conceived as a textual overview which does not aspire to provide a specialization base for scientific work, but is primarily aimed at understanding the basic terms. In the introduction, I deal with the definitions of computer physics. The chapter entitled Hardware and Software Devices of Computer Physics begins with a brief description of the architecture of the computer and its historical development. This is followed by the basics of programming with a short overview of programming languages. In the chapter entitled Computer Modelling, I present a brief characteristic of this field and acquaint the reader with the basic terms and techniques of modelling. In the following chapter, the reader is acquainted with the principles associated with hybrid modelling as well as the Monte Carlo method. The fourth chapter is intended to be an interesting demonstration of modern trends in computer modelling. In the last chapters, I deal with the brief characteristic of programs that are most commonly used in the field of computer modelling (MATLAB, Fluent and COMSOL Multiphysics).
|
|
|
Literature search about the computer modelling in dusty plasma
NAROVEC, Jiří
Bachelor's thesis presents selected pieces of knowledge from the field of complex plasma. The topic was treated with reference to about 100 technical publications as listed in the bibliography. Special attention of measuring techniques and complex plasma models is given to description of dust particles in plasma. That provides better comprehension of processes occurring in this specific type of plasma and better prediction of its behavior in real systems.
|
|
|
Porovnání 2D a 3D modelu dávkovače zinku
Mach, M. ; Musil, Ladislav
The paper deals with the mathematical and computer modelling of electromagnetic zinc feeder, which is a device for exact dosing of molten zinc. 2D and 3D models of the feeder were developed, solved and the results were compared and discussed. Computations were carried out by the professional FEM-based codes FEMLAB, OPERA, QuickField and a number of single-purpose user procedures written by the authors
|
guest ::
