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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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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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Advanced Layered Composites for Dental Applications
Šedivý, Zbyněk ; Kučera, Jaroslav (referee) ; Štěpánek, Petr (referee) ; Jančář, Josef (advisor)
Disertační práce se zabývá mechanickou odezvou vrstevnatých kompozitů pro stomatologické aplikace. Různé skladby vrstev a různé částicové a vláknové kompozity jsou studovány v tříbodovém ohybu za pokojové teploty. Tyto výsledky jsou korelovány s výstupy dynamické termomechanické analýzy (DMTA) a optické analýzy (vysokorychlostní video záznam, SEM). Exeprimentální data byla použita pro srovnání s výsledky analytických a numerických modelů s cílem určit nejvhodnější model pro predikci základních mechanických vlastností vrstevnatých kompozitů. Na základě těchto analýz jsou navržena základní pravidla pro klinické použití vrstevnatých kompozitů ve stomatologických aplikacích jako jsou minimálně invazivní můstky nebo stabilizační dlahy.
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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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Forest vegetation in Eastern Elbe Basin in the mid-20th century and today
Pospíšková, Marie ; Hédl, Radim (advisor) ; Novák, Jan (referee)
This thesis describes the shift in vegetation of broadleaf forests in eastern part of the Elbe River Basin between 1958-1968 and 2011-2013. It emphasizes the understorey vegetation. From lowland woodlands in other temperate regions in Europe and North America changes towards eutrophic and mesophytic vegetation are documented, specifically driven by changes in forest management and by atmospheric depositions; in some localities the game impact can be also important. The data were obtained by sampling 190 typological semi-permanent plots, which were precisely located - in 43% the original soil pit was found. The vegetation on study sites shifted towards nutrient-demanding, shade- adapted species, it was partly ruderalized. These changes can be seen on the level of species and communities as well as on phytosociological level. Increase of soil pH and moisture was discovered using Ellenberg indicator values. The number of seedlings and cover of shrubs also increased significantly. Homogenization of sites was significant as well although total number of species and alpha- diversity remained unchanged. These changes are probably caused by changes in forest management and by atmospheric depositions of nitrogen. On subset of plots in game-preserves the vegetation also demonstrated eutrophication but no increase in...
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Homogenization of flows of non-Newtonian fluids and strongly nonlinear elliptic systems
Kalousek, Martin ; Kaplický, Petr (advisor)
The theory of homogenization allows to find for a given system of partial differential equations governing a model with a very complicated internal struc- ture a system governing a model without this structure, whose solution is in a certain sense an approximation of the solution of the original problem. In this thesis, methods of the theory of homogenization are applied to three sys- tems of partial differential equations. The first one governs a flow of a class of non-Newtonian fluid through a porous medium. The second system is utilized for modeling of a flow of a fluid through an electric field wherein the viscosity depends significantly on the intensity of the electric field. For the third system is considered an elliptic operator having growth and coercivity indicated by a general anisotropic inhomogeneous N-function. 1
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