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Strain, stress and strength analysis of the high pressure compound vessel by finite element method
Koutský, Jiří ; Suchánek, Miroslav (referee) ; Vrbka, Jan (advisor)
Strength and strain analysis of high pressure compound vessel, which is used to produce superhard materials (for example synthetic diamond). This work was elaborated to compare the stresses and strains calculated by Prof. Jan Vrbka making use of the FEM program ‘Prokop’17 years ago with those gained with the contemporary FEM Ansys program. The vessel is loaded by internal pressure of size 6 GPa. The elastic-plastic material be-haviour is taken into account. Real value of friction between rings and non-uniform temperature field is included into the calculation. The process of assembling the compound vessel is simulated step by step.
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Superhard cutting materials and theirs effective use
Grausgruber, Jiří ; Prokop, Jaroslav (referee) ; Humár, Anton (advisor)
n the first part of this diploma thesis there are described basic findings about superhard cutting materials (sorts, notation, structure, physical-mechanical properties, usage, production) and evaluates this tool of material from the aspect of cutting ability. The second part focused on complex data processing about assortment of superhard cutting materials of significant tools materials producers and comparison of work conditions (kind of machined ma-terials, cutting conditions), which are recommend for effective turning applica-tions by producers.
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Carbon Based Materials
Hrazdíra, Matěj ; Čelko, Ladislav (referee) ; Klakurková, Lenka (advisor)
The proposed bachelor thesis deals with carbon based materials. First of all, an overview of its allotropic modifications including newly discovered forms, conditions of their existence and also their basic properties is shown. Further the extraction of carbon materials is briefly introduced. In the next chapters, forms of carbon are classified and particularly described individually with respect to manufacturing technologies and further applications. Individual chapters are dedicated to synthetic carbon and graphite, carbon fibers and carbon fiber reinforced composites. Manufacturing processes of synthetic carbon and graphite, involving possible precursors, are described in detail together with their use in various engineering applications. The following part is dedicated to carbon fibers, in particular to the manufacturing process based on the precursor used including surface treatment and sizing. Additionally the use of virgin carbon fibers is also described. The last part is focused on carbon fiber reinforced composites. Firstly possible distributions of carbon fibers in a matrix are described. Then the technology of manufacturing, properties and use of single composites according to the matrix material are expounded.
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Superhard cutting materials
Mlčoch, Petr ; Dvořáček, Jan (referee) ; Humár, Anton (advisor)
This bachelor thesis deals with superhard cutting tool materials, which include diamond and cubic boron nitride. It is divided into three parts. In the first one there is a short summary of cutting tool materials currently used for machining. The second part pursues sorts, production and properties of superhard cutting materials. The last part represents superhard cutting materials in the offer of two important producers of cutting tool materials and two producers of cutting tools.
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Diamond wheels and their use in the stone industry
Skryja, Jan ; Kolář, Ladislav (referee) ; Jaroš, Aleš (advisor)
This bachelor thesis deals with stone sawing during stone processing. It is divided into theoretical and practical parts. In the theoretical part diamond blades, the sawing process and stone extraction are described. The practical part is focused on the wear of circular saws in granite circular sawing. The wear is determined for two diamond cutting blades made by different manufacturers and is determined by the blade weight loss and segments height loss as a function of time. Both measured values show linear dependence. The results are the basis for a future comparison of the two diamond blades on the economic side, which is not the subject of this work.
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Coating methods for cutting tools
Doležal, Jan ; Madaj, Martin (referee) ; Humár, Anton (advisor)
Bachelor work describes methods of coating of cutting tools and their technical characteristics. The work is given below the current product range of manufacturers of coated cemented carbides. At the end of this work is treated the development of coating cutting tools and types of applied coatings.
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Spectroscopy of semiconductors with ultra-high time resolution
Hanák, Martin ; Trojánek, František (advisor) ; Kozák, Martin (referee)
This thesis is aimed at building and optimization of a new experiment setup for measuring time-resolved transmittance using a pump-probe method. Test measurements were then conducted on a sample of SiV centers in diamond. The theoretical part contains a general description of luminescence of color centers. It then specifically focuses on SiV centers in diamond and describes their structure, electronic and spectral properties in detail. The description of our setup and its optimization is given at the beginning of the experimental part. The dependencies of differential transmittance of SiV centers in diamond on excitation intensity and wavelength were measured and the lifetime of SiV centers was then determined from our measurement results. 1
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Electronic effects at the interface between biomolecules, cells and diamond
Krátká, Marie ; Rezek, Bohuslav (advisor) ; Cifra, Michal (referee) ; Skládal, Petr (referee)
Understanding and control of interactions between biological environment (cells, proteins, tissues, membranes, electrolytes, etc.) and solid-state surfaces is fundamental for biomedical applications such as bio-sensors, bio-electronics, tissue engineering and implant materials as well as for environmental monitoring, security and other fields. Diamond can provide unique combination of semiconducting, chemical, optical, biocompatible and other properties for this purpose. In this thesis we characterize electronic properties of protein-diamond interface by employing a solution-gated field-effect transistor (SGFET) based on hydrogen-terminated diamond, surface of which is exposed to biological media. We elucidate the role of adsorbed protein layer on the electronic response of the diamond transistor. We investigate effects of cells (using mainly osteoblast cells as model) on diamond SGFETs transfer characteristics and gate currents. We employ nanocrystalline diamond (NCD) thin films of different grain sizes (80 - 250 nm) to characterize and discuss influence of grain boundaries and sp2 phase on bio- electronic function of SGFETs. We investigate effects of gamma irradiation on function and stability of hydrogen-terminated diamond SGFETs interfaced with proteins and cells, showing feasibility of...
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Superconductivity in disordered systems
Šopík, Břetislav ; Lipavský, Pavel (advisor) ; Novotný, Tomáš (referee) ; Munzar, Dominik (referee)
Author: Mgr. Břetislav Šopík Thesis advisor: doc. Pavel Lipavský, CSc. Ph.D. thesis Superconductivity in disordered systems Abstract We study some aspects of the superconductivity in disordered systems - namely the superconductivity in a boron-doped diamond. We also apply theoretical methods originally developed in the field of the disordered systems to the theory of superconductivity. In the case of the boron-doped diamond we focus on the question of the dependence of the critical temperature Tc on boron doping. We discuss the impact of the boron distribution correlations on the Tc as well. First, we evaluate the density of states at the Fermi energy N0 within the dynamical cluster approximation. We discuss the Tc as a function of N0 within the BCS, the McMillan and the Belitz theory. In the case of 100 samples, the simplified Belitz theory gives the best agreement with experimental data. For 111 samples the McMillan theory is sufficient. We also show that the difference of 100 and 111 samples in the N0 dependence of Tc can be explained as given by attractive correlations in the boron distribution. Applying the concept of the coherent potential approximation, we re- move a self-interaction from the Galitskii-Feynman T-matrix approxima- tion. This correction has no effect in the normal state but makes the...
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