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QUANTUM MECHANICAL STUDY OF PHASE STABILITY IN METALLIC SYSTEMS
Káňa, Tomáš ; Vřešťál, Jan (referee) ; Paidar,, Václav (referee) ; Černý, Miroslav (referee) ; Šob, Mojmír (advisor)
This work presents a theoretical study of stability of phases in selected metallic systems. We propose a model of structural transformations in transition metal disilicides MoSi2, CrSi2, VSi2 and TiSi2 and in Pd thin films grown on cubic substrates W(001) and Nb(001). The obtained results yield the total energy proles for the structural transformations studied, the activation energies needed for each individual transformation and an estimate of the temperature at which the structure can transform. The total energies are calculated by full-potential linearized augmented plane waves (FLAPW) method incorporated in the WIEN2k code. Both generalized gradient approximation (GGA) and local density approximation (LDA) are employed for the exchange-correlation term. It turns out that temperatures corresponding to the activation energies of structural transformations in transition metal disilicides exceed their melting temperatures. Comparing the resulting total energy proles to those obtained by the semiempirical Bond Order interatomic potentials (BOP) substantially helps to adjust the fitting parameters of the BOPs. The estimated temperature of 168 K needed to transform the hcp structure of an innite Pd crystal into the dhcp structure explains the behavior of the Pd thin lm on W(001) and Nb(001) substrates. Pd lms deposited on W(001) substrate and thicker than about 100 monolayers undergo this transformation already at room temperature. Thinner lms need to be annealed at 400 K rst, due to their stronger interaction with the substrate. The difference between the computed result and a real temperature at which the hcp Pd lm transforms its structure to the dhcp can be explained by both the interaction between the lm and the substrate and by the inuence of the domain topology of the lm. Analyzing different models of transformation of the initial hcp Pd structure to the ground state fcc structure, we identied the optimum model that respects the domain topology of the Pd lm.
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GIS ANALYSIS IN BUILDING INFORMATION MODELS
Černý, Martin ; Kubíček,, Petr (referee) ; Vyhnálek,, Rudolf (referee) ; Bartoněk, Dalibor (referee) ; Pospíšil, Lubomil (advisor)
This dissertation thesis are concerned about the Geographic Information Systems (GIS) and spatial analyses inside of the Building Information Models (BIM). BIM and GIS are compared from different points of view like data organization, geometry types and modelling paradigms. Results of this comparisons are applied in the first case study where BIM data in IFC format are converted to the SHP format usable for spatial analyses in GIS. The results of the case study are evaluated and new approach for spatial analyses in BIM models is proposed based on the results. The new proposed approach is based on the semantic relations existing in the BIM models. Thesis are concluded with the future development which is in line with authors actual focus.
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Price Comparison of an Apartment Building in the Bučovice Cadastral Area According to the Valid Valuation Regulations
Černý, Michal ; Hlavinková, Vítězslava (referee) ; Karabec, Jiří (advisor)
Diploma thesis introduces two different options for property valuation. With an emphasis on the different ownership of the apartment building. In the first case, the building seen as a whole and used the combination of yield and cost method of valuation. In the second case, a building is divided into individual residential units and valued method of comparison. Both methods are conducted in accordance with Decree No. 3 / 2008 digest Implement certain provisions of Act No. 151/1997 digest., Valuation of property and amending certain laws, as amended (Decree valuation), as follows of the changes made by Decree No. 456/2008 digest. and No. 460/2009 digest. In conclusion, the following derived values were compared and evaluated.
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Optimization of Methods for Manufacturing Wormshafts
Černý, Michal ; Prokop, Jaroslav (referee) ; Kalivoda, Milan (advisor)
The subject of this diploma thesis is the optimization of the production wormshaft under specific conditions in a particular company. The optimization was requested by firm as a solution in the areas which are defined by content of this thesis. In first part, the technology of the product manufacture is evaluated. Next analysis of the original production technology is performed the regarding rationalization explained later, proposing a new form of manufacturing process. In the following parts layout variants of workplaces are assembled. These variants are based on the newly designed technology. The final part presents a control jig, which will be used in quality assurance and manufacturing workplaces and allows to measure various type of wormshaft parts. In the discussion section there is a proposal of another possible solution for manufacturing optimization these key components that make up assembly control gearbox of valves and ball valves.
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Design of the steam generator for modular reactor
Černý, Marian ; Baláš, Marek (referee) ; Šen, Hugo (advisor)
Subject of this thesis is design of the steam generator for modular reactor. The dissertation consist of the theoretical part, where are described heat-exchangers and steam generators used in nuclear power plants. Second part contains theoretical calculations in the first approach (thermal, hydraulic and strenght calculation). In the next part are particular variants of steam generator selected. For the final variant are necessary calculations (introduced above) and drawings of selected parts are done. In the final statement is technical solution evaluated, and the parameters of the steam generator are compared with actually used steam generators.
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Stand-up power wheelchair
Juříček, Václav ; Maňas, Pavel (referee) ; Černý, Michal (advisor)
This thesis deals with the structural design and manufacture of special power wheelchair prototype in collaboration with company Brano. Remarkable feature of this wheelchair is the ability to pull its user to an upright position, offering the greater independence, self-sufficiency and medically positive impact on physical functions. The content of this thesis is devoted to a search of the current state of knowledge in the matter, structural analysis of complete wheelchair assembly with a detailed description of each component including the important calculations and analyzes, as well as a description of the wheelchair testing. The conclusion presents summarization of all the results in structural, technological and economic terms.
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Mobile equipment for the surface hardening
Bašek, Ondřej ; Veselý, Oldřich (referee) ; Černý, Michal (advisor)
Diploma thesis is specialized in an engineering design of mobile equipment for the surface hardening. At first, overview of methods and instruments for surface hardening is introduced. Solution to the thesis is a proposial for any eventual options of contruction, appreciation and choice of a suitable option. Subsequently, particular parts of the equipment with design and check calculations are explicated. Constructional tasks were done in the SolidWorks program. Finally, an economical analysis is described.
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Heat and mechanical resistance of zinc coating
Horák, Karel ; Dzimko, Marián (referee) ; Černý, Michal (advisor)
The work is aimed at studying the thermal degradation of the protective zinc coating. Its large part deals with the structure of the various stages of transition and their arrangement, the main emphasis is on analysis of brittle intermetallic phases, which arise due to increased temperature. Conclusion of the work is trying to clear itself causes degradation of this protective layer.
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Stability of crystalline solids from first principles
Řehák, Petr ; Šob, Mojmír (referee) ; Černý, Miroslav (advisor)
This work deals with study of stability of solid crystals under isotropic loading. Ab initio methods were used for this purpose. Crystals of four fcc metals (Al, Cu, Ir, Au) and diamond were subjected to simulated isotropic tensile deformation and maximum value of isotropic stress was evaluated for them. Consequently, phonon spectra were calculated for several strain values in order to assess crystal stability. Phonon instabilities in dispersion curves of diamond, Al, Ir and Au appeared at strains lower than those corresponding to their decohesion. This appearance of instability determinates the value of ideal strength. However, significant reduction (by about 20%) was found only in the cases of Au and Ir.
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Solar cell non-destructive analysis
Černý, Michal ; Škarvada, Pavel (referee) ; Macků, Robert (advisor)
This thesis briefly analyse contemporary situation of photovoltaic systems and their actual developemenet. It shows a typical properties of most produced up-to-date types. Decision point of this thesis consist in nondestructive analyse of monocristalic unijunction solar cells. It describes two main diagnostic aproaches. First – through the use of measuring of VA characteristics, second – through the use of measuring noise characteristics. With selected samples are performed experimental measurements and estabilished basic parameters. In case of drone analysis considerably attention is devoted to experimental equipment for automatized measuring of spectral power density. This experimental equipment is consequently used for measuring some samples where we can observe microplazmatic noise.
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