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Four-cylinder in-line gasoline aircraft engine
Kučera, Ondřej ; Kučera, Pavel (referee) ; Píštěk, Václav (advisor)
The thesis deals with the structural design of a steel connecting rod for the aircraft engine Walter Mikron III, which is currently still manufactured and developed by company PARMA-TECHNIK, s.r.o. The proposed connecting rod would replace the current duralumin connecting rod. The work also contains a strength analysis of the designed component, in which it was aimed to verify the stress on the connecting rod, based on which the fatigue safety factor was performed. This is crucial for dynamically stressed parts of internal combustion engines. Furthermore, was investigated the effect of the change of the connecting rod on the torsional vibration of the crank mechanism. For this purpose, was built a discrete torsion model. The output of the whole work is the drawing documentation of the new connecting rod, meeting the requirements for application in an aircraft engine.
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Experimental study of lubricant films in contact of machine parts
Kučera, Ondřej ; Křupka, Ivan (referee) ; Vaverka, Michal (advisor)
This bachelor thesis is focused on the description of methods for experimantal study of lubrication films in contact of machine parts, particularly for non-conformal surfaces, for which elastohydrodynamic and mixed of lubrication is typical. The methods are devided according to measured quantity into the methods for film thickness measurement, contact pressure measurement and temperature measurement. It was described the principle of these methods, the equipment, application and characteristics. Finally, evaluation of current status and further development are included.
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Library for Evaluation of Noises Used in Procedural Texturing
Kučera, Ondřej ; Chudý, Peter (referee) ; Herout, Adam (advisor)
The aim of the work is to describe procedural texturing and usage of a noise for creating textures of real materials. The reader will learn the fundamentals of the noise, its properties and a way of using it. Random numbers and interpolation methods are important parts of the noise evaluations, therefore there are chapters about random numbers generating and interpolation methods. Obviously, there is not missing the chapter, which is depicting properties and principles of several methods of creating noise. The main part of this work is effective implementation of library with a chosen noise methods, so next chapters are about choosing methods and design of the interface, implementation and many kinds of tests and optimalizations. Achieved results and final conclusions are at the end of this work.
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Input audio preamplifier used for laboratory measurements
Kučera, Ondřej ; Kaller, Ondřej (referee) ; Kratochvíl, Tomáš (advisor)
This article looks at pre-input low-frequency amplifiers for laboratory work. The task was to study, design and build a fully functional pre-input amplifier for use in low frequency audio technology. In each section, we will discuss the various preamps, which are classified according to signal processing parameters. The construction of each amplifier uses discrete components and operational amplifiers. The second part of the article looks at different measuring devices, such as input sensitivity, transfer characteristics and input impedance etc., which would form part of the amplifier.
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Characteristic of ESP written communication
Kučera, Ondřej ; Walek, Agata (referee) ; Baumgartnerová, Alena (advisor)
Cílem této bakalářské práce je definovat, co je to angličtina pro specifické účely, vymezit její styly a žánry. Tato práce je rozdělena do tří hlavních částí. V první části je stručně představen anglický jazyk pro specifické účely a jeho historie. Jsou zde přiblíženy styly tohoto jazyka a je vysvětleno jejich použití. Ve druhé části jsem definoval žánry tohoto jazyka, vysvětlil účel každého z nich a ukázal, jak se dále dělí. Ve třetí části jsou prezentovány části textů, jež jsou analyzovány a porovnány: dva texty z elektrotechniky a dva texty z medicíny. V obou oblastech je porovnáván úryvek z populárně vědeckého článku a učebnice. Analýza je provedena ve čtyřech kategoriích: koheze, deixe, signposting a hedge. Tyto výsledky jsou porovnány nejdříve ve stejném oboru mezi rozlišnými styly a následně mezi odlišnými obory – elektrotechnika a medicína. Všechny výsledky jsou komentovány.
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Processing and properties of piezo-dielectric ceramic composites
Kučera, Ondřej ; Drdlík, Daniel (referee) ; Maca, Karel (advisor)
The diploma thesis deals with piezoelectric materials combining dielectric and piezoelectric ceramics. The first part of this diploma thesis summarizes the preparation of ceramic materials and thermodynamic of sintering. The electric properties of ceramic materials and current knowledge in BCZT ceramics are summarized. The second part of this diploma thesis describes BCZT ceramics preparation process from raw materials in powder form through the reaction of the precursors to sintering the experimental material into the compact body. The properties of prepared BCZT samples such as density, grain size, hardness, relative permittivity, piezoelectric constant and dielectric loss are summarized in the thesis.
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Chord structure detection in music recordings
Kučera, Ondřej ; Miklánek, Štěpán (referee) ; Ištvánek, Matěj (advisor)
This thesis deals with music information retrieval, namely automatic chord recognition in audio recordings. The thesis defines the concepts of chord and chroma features and describes the methods of converting the signal from the time domain to the frequency domain. The thesis explores methods for automatic chord detection; the state-of-the-art methods are based on deep learning. The thesis includes a system implemented in Python that allows chord detection from audio recordings. Individual recordings and associated chord labels can be visualized. The system offers a choice of methods for chord recognition – a method based on chord templates, a method using deep chroma vectors, and a method based on a convolutional neural network. The results of the methods are evaluated on a multi-genre dataset compiled from freely available annotations and recordings.
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Impact of joint implant surface structure on friction behaviour
Kučera, Ondřej ; Nečas, David (referee) ; Ranuša, Matúš (advisor)
In osteoarthritis of small joints, the use of total endoprosthesis is currently being developed to ensure physiological movement, but it provides only a limited-service life. The use of microstructures on the implant surface may improve tribological properties, but this issue is not described enough. Thus, this work addresses the impact of microstructures on friction coefficient, lubricant thickness in the contact area, wear, as well as surface topography and geometry of the structures. Furthermore, the influence of DLyte electrochemical machining on the change of microstructures geometry and tribological properties is investigated. Measurements were performed using a reciprocal tribometer, interferometry and optical profilometry. The textured samples achieved an increase in both friction coefficient and lubricant thickness in the contact area. Furthermore, a correlation between the height of the texture edges and the measured lubricant thickness was demonstrated. DLyte significantly reduces these edges, also reducing wear, however, it degrades the surface of the CoCrMo samples. Implant texturing can lead to reduced wear, prolonged life, and thus improved quality of life for many patients. Texturing of Ti6Al4V alloy in combination with DLyte shows great potential.
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