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Banach Algebras
Machovičová, Tatiana ; Nechvátal, Luděk (referee) ; Franců, Jan (advisor)
By Banach algebra we mean Banach space enriched with a multiplication operation. It is a mathematical structure that is used in the non-periodic homogenization of composite materials. The theory of classical homogenization studies materials assuming the periodicity of the structure. For real materials, the assumption of a periodicity is not enough and is replaced by the so-called an abstract hypothesis based on a concept composed mainly of the spectrum of Banach algebra and Sigma convergence. This theory was introduced in 2004.
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Homogenization in Perforated Domains
Rozehnalová, Petra ; Bock, Igor (referee) ; Rohan, Eduard (referee) ; Franců, Jan (advisor)
Numerické řešení matematických modelů popisujících chování materiálů s jemnou strukturou (kompozitní materiály, jemně perforované materiály, atp.) obvykle vyžaduje velký výpočetní výkon. Proto se při numerickém modelování původní materiál nahrazuje ekvivalentním materiálem homogenním. V této práci je k nalezení homogenizovaného materiálu použita dvojškálová konvergence založena na tzv. rozvinovacím operátoru (anglicky unfolding operator). Tento operátor poprvé použil J. Casado-Díaz. V disertační práci je operátor definován jiným způsobem, než jak uvádí původní autor. To dovoluje pro něj dokázat některé nové vlastnosti. Analogicky je definován operátor pro funkce definované na perforovaných oblastech a jsou dokázány jeho vlastnosti. Na závěr je rozvinovací operátor použit k nalezení homogenizovaného řešení speciální skupiny diferenciálních problémů s integrální okrajovou podmínkou. Odvozené homogenizované řešení je ilustrováno na numerických experimentech.
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Homogenization of closed foam structures using Kelvin cell
Škoviera, Jozef ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The bachelor‘s thesis deals with creating calculation model of the foam structure based on Kelvin cell with closed porosity. First aim of this work is homogenization of the foam structure by identical deformation response in foam structure and continuum. Second aim is follow-up parametrical study of influence of characteristic measures of Kelvin cell on material characteristics. Task was solved in ANSYS software by method of final elements. Resultant dependences rendering was done in MATLAB software.
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Sample preparation for DNA analysis from foods of plant origin
Silná, Renata ; Rittich, Bohuslav (referee) ; Kovařík, Aleš (advisor)
The isolation of high quality DNA is nessecary for many molecular biology applications. However, plant DNA contains high amonts of polysaccharides, polyphenols and various secondary metabolites, which decrease yield and quality of isolated DNA. The aim of this study was preparation of samples and different food matrices for DNA isolation DNA by magnetic particles. It was about 5 species of vegetable and 10 species of processed plant food. Homogenization of samples was performed in CTAB buffer. Isolation of plant DNA was performed by magnetic particles covered with carboxyl groups. All DNAs were isolated in conventional PCR qualities using primers for 700 bp amplicons, in the case of heat processed products for 220 bp ampilicons and for real time PCR. The efficiancy of separation of magnetic particles with DNA by magnetic separator and magnetic needle was compared. It was find out that DNA of higher purity was isolated using magnetic needle. The micromethod of isolation of plant DNA from homogenates with CTAB with magnetic particles is suitable for different processed food.
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Design of the composite rotor sleeve of a high speed rotary machine
Pavlík, Ondřej ; Ševeček, Oldřich (referee) ; Návrat, Tomáš (advisor)
The diploma thesis focuses on manufacturing carbon fiber and epoxy composite material using filament winding method. Material properties of manufactured composite are ap-proximated using analytical and numerical homogenization models. Calculated material properties are applied to design and evaluate reserve factor of retaining sleeve for high speed brushless permanent magnet synchronous motor. Margin of safety of designed rotor is evaluated using composite failure criteria. Test stand for both static and dynamic testing is designed, static test stand is manufactured and assembled. Static strength test is carried out.
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News in the field of the road construction
Zelenka, Lukáš ; Zajíček, Jan (referee) ; Varaus, Michal (advisor)
The bachelor’s thesis focuses on new technological equipment for transport and paving of asphalt mixtures. Specifically, it is a thermo superstructure with an extrusion face and a homogenization tank of an asphalt mixture. The advantages of these machines and their positive influence on the quality of the work are described. Subsequently, the researches which confirm it are described. The last chapter describes recommendations for the contracting authority to require the use of these technologies in tenders.
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Lattice Topology Optimization in ANSYS software
Černák, Martin ; Vaverka, Ondřej (referee) ; Vrána, Radek (advisor)
ANSYS is one of the first commercially available software which allows to make topology optimization of lattice structures. In this bachelor’s thesis optimization workflow, calibration of numerical model, validation of numerical results and revelation of influence of basic parameters involved in computation – cell type, minimum and maximum relative density, cell size and used discretization, are showed. Optimised part was compared by means of FEM and homogenization with available experimental data. Subsequently, influence of basic parameters was evaluated. It was shown that optimized structure is stiffer than benchmark and influence of basic parameters for mechanical response and computational complexity was introduced. Simultaneously, it was shown that homogenization overestimated mechanical response. The findings of bachelor’s thesis validate computational model in program ANSYS and can be used for more effective making of optimization models.
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CFD modelling of pipe flow mixing of liquids
Pavlíček, David ; Hájek, Jiří (referee) ; Juřena, Tomáš (advisor)
This work is focused on computational modelling of mixing fluids in pipeline with static mixers. Main objective is to analyze several selected static mixers in a particular industrial application, namely dosing of the aluminium sulphate solution in the clarification process for potable water treatment. The analysis focuses on the degree of mixedness and pressure loss of individual mixers. Further, the aim of this work is to process the search of available types of static mixers. The benefit of this work is at least an effort to motivate the reader to deeper understanding of the mixing fluids, especially by static mixers.
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Computational analysis of the electro-mechanical characteristics of ferroelectric/dielectric composite material
Vítek, Tomáš ; Marcián, Petr (referee) ; Ševeček, Oldřich (advisor)
This diploma thesis deals with the computational modeling of ceramic ferroelectric/dielectric particle composites. The literature review section explains the principle of the piezoelectric phenomenon, describes the quantities defining the piezoelectric behaviour of materials, and provides characteristics of commonly used piezoelectric materials, including the mentioned ferroelectric/dielectric composites. The computational part of the thesis begins with the homogenization of particle composites consisting of a ferroelectric matrix and dielectric particles. Available analytical models for determining the effective electromechanical properties of the composite are tested, and parametric finite element models of the particle composite are assembled using Ansys Mechanical APDL software. The algorithm for creating these models is described, and the procedure for computing the relevant effective properties of the composite based on the obtained results is explained. Subsequently, the results obtained from the analytical and finite element models are compared, and the usability of the chosen analytical models is assessed based on the composite parameters. Sensitivity analyses are then performed using the assembled finite element models to evaluate how specific geometric and material parameters affect the effective electromechanical properties of the composite. These properties predicted by the finite element method are compared to the provided experimental results in the next part of the thesis. A computational analysis of residual stresses induced in the composite during sintering follows, and the output of this analysis provides recommendations for the manufacturing of these composites, aiming to reduce residual stresses and, thus, the risk of crack formation. Finally, various designs of ferroelectric/dielectric composites that can be manufactured using 3D printing are proposed and analysed, with the presented results serving as a basis for future research.
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The impact of urban sprawl on the environment.
Havel, Petr ; Chuman, Tomáš (advisor) ; Romportl, Dušan (referee)
The suburbanization process - a shift of population and activities from city centre to its fringe - is not only a socioeconomical phenomenon; city spatial expansion is a serious concern for an environment as well. The volume of suburban and sprawling areas is constantly increasing, moreover the character of this development is inefficient both spatially and energetically. A crucial changes take place in a landscape, which is being fragmented and homogenized. Those changes affect organisms, which live in the landscape; their natural environment is intensively modified and not all of them are able to get used to a newly created conditions and resist to a pressure of invasive species. A lot of compacted and impervious surfaces negatively influence not only the biota, but also a water quality, infiltration and water regime. Last but not least, new development seals a lot of quality agricultural land. Sealed soils are irreversibly deteriorated and become useless for further agricultural use. Despite the fact, that legislative in the Czech Republic should protect the high-quality agricultural soils, the study, made in the surroundings of D1 highway shows that's not the case. Two thirds of the commercial suburban development take place on the most productive and valuable soils. This number suggests poor...
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