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Hybrid Blends of Recycled Plastics
Černý, Miroslav ; Lehocký, Marián (referee) ; Balgová,, Vendula (referee) ; Jančář, Josef (advisor)
Work describes the relationship between structure and mechanical properties in case of hybrid mixtures. They are composed from polyurethane matrices (eventually polyurethane-urea or polyurethane-inorganic filler mixtures), different rubber fractions as filler and eventually reinforcement made from PET monofilaments. Mechanical behaviour was studied by tensile testing. Studied mechanical properties include tensile modulus, ultimate strength and strain and also specific energy need neccessary for ultimate strength achievement. Prepared materials are naturally porous. Therefore their mechanical behaviour has to be described generally for porous composites. The porosity occurence means, that it is difficult to describe them by models valid for mechanical behaviour (mainly elastic modulus) of nonporous composites. Models are also based on idealized structures on microscopic level. In case of porous composites, it is very difficult to create any idealized structure. The structure is changed with modifications of composition (change of components or their rates). These conditions have lead to utilizing of different approach how to describe the relationship between structure and mentioned mechanical properties. The chosen approach comes from knewledge about structural parametres coming from porosity. Structural parameters describe the structure on macroscopic level. They include interspace volume (volume lying between filler particles), interspace filling (how the matrix fills the interspace volume) and matrix volume fraction. Proposed parameters are used in relations, where they are fitted by exponents to interlay values of chosen mechanical properties for composites containing discrete matrix and filler. Found exponents are then described by properties of matrices to obtain relations describing properties of filled porous materials. Very similar approach was chosen for description in the case of reinforced composites. Proposed relation are potentially valid for materials containing binding matrix, infinity count of fillers and one kind of reinforcement.
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Design of a technology and checking the production of small steel ingots
Jakubčíková, Lucie ; Čamek, Libor (referee) ; Záděra, Antonín (advisor)
The thesis deals with the design of ingots from duplex (austenitic-ferritic) stainless steels in terms of minimal occurrence of axial porosity. The optimal shape and dimension of the ingot and the casting conditions are determined based on numerical simulations. The resulting internal quality of the realized ingot is evaluated. The presence of shrinkage porosity is determined by penetrant testing. The degree of chemical heterogeneity, the extent of macrosegregation, of selected elements in given ingot locations is measured by an optical emission spectrometer. Segregation values are compared with simulation results. The micro-purity of the ingot is assessed on the basis of metallographic samples.
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Preparation processes and properties of porous zinc material
Moleková, Kristína ; Březina, Matěj (referee) ; Hasoňová, Michaela (advisor)
Bachelor thesis occupy with preparation of porous material from zinc powder by cold pressing, cold pressing followed by sintering and hot pressing. This thesis contain both preparation of bulk material, and charakterization of materials based on the compaction process conditions. Impact of pressing process on subsequent progress of sintering and final attributes of materials is evaluated. Bulk material is characterized considering to structure, porosity, and physical-mechanical properties. Properties of final metarial will serve to optimize conditions for process of pressing and sintering.
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Effect of basic agrotechnics for physical and hydrophysical properties of soil
Komárková, Markéta ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
In the master’s thesis, we evaluate the impact of different types of soil treatment on the physical and hydro-physical properties of the subsurface layers of soil. The experimental research took place near the town of Šakvice in two chosen areas treated conventionally, i.e. by tillage. The PRP SOL substance was applied to one of the observed areas. Unimpaired soil samples were taken during the vegetation period of the grown crops in the topsoil (10,20 cm) and in the undersoil (30 cm) on 13th May 2009 and on 10th September 2009. The chosen physical parameters of the soil, i.e. the reduced volume mass, the porosity, the distribution of pores, the actual content of water and air, were determined by standard analytical methods. The double-ring infiltration method was used during the field measuring of infiltration. The Philip’s equation and the Philip’s type three-parameter equation were used for the data analysis, serving as a base for estimation of saturated water content Ks. A protractor with a constant gradient was used during laboratory measuring. The results of a year-long research have not shown any major influence of the PRP SOL substance on the physical quality of the subsurface layers of soil in the observed area. On the contrary, the permeability od the soil obtained on the basis of Ks estimation is higher in the area treated by the PRP SOL substance.
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The impact of agro-technology on the physical and hydraulic properties of the soil
Vláčilíková, Michaela ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
The bachelor thesis deals with the impact of agrotechnics on the physical and hydraulic properties of the soil. At the beginning of the work a literary research was elaborated on the above mentioned problems in the final part an evaluation of the physical and hydraulic characteristics of soil, which are used as indicators of soil quality. Experimental research was carried out in 2017 near the village Bohaté Málkovice, the soil on one area was processed by minimization technology and on the other parcel (with mild erosion) direct sowing was applied to the soil. The crop was sunflower.
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Sintering ability of feldspars and their alternatives
Votava, Petr ; Štubňa,, Igor (referee) ; Sokolář, Radomír (advisor)
The main goal of this Bachelor’s thesis is to compare sintering ability of feldspars which are the most used flux in ceramics with their alternatives such as quarry dust and bone ash. Theoretic part describes process of sintering, sintering activities of used fluxes and their use in the manufacture of ceramics. Practical part is dedicated to description and evaluation of experiment in witch sintering activities of various fluxes ceramic product are compared in dependence on their percent proportion in raw material mix.
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On the analysis of welding seams
Němečková, Monika ; Sliwková, Petra (referee) ; Píška, Miroslav (advisor)
The thesis deals with the analysis of the quality of welded joints on the pressure tank, which is produced by Bosch Diesel s.r.o. The main point is to improve the porosity in the weld joint. The theoretical part deals with the analysis of the pressure container and its production process. The practical part deals with the cleaning process before welding and the analysis of residual grease on the welding surfaces after the cleaning process in which two different cleaning media were used. Furthermore, the CT evaluation of welded joints was used to support which washing medium is better, thus providing better degreasing and thus less porosity in the weld joint, for pretreatment of weld surfaces.
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Measurement of infiltration in the field using MiniDisk infiltrometer
Vláčilíková, Michaela ; Doležal, Ing Petr (referee) ; Kameníčková, Ivana (advisor)
The diploma thesis deals with measuring of infiltration by MiniDisk method and its evaluation, but also with analysis of intact and grab soil sample, by means of which it is possible to assess the soil quality. The measurements took place on 30.4.2019, 4.5.2019, 12.5.2019, 2.6.2019, 30.6.2019, 2.7.2019, 31.8.2019 and 21.9.2019 on grassland near the town of Luhačovice. Grab and intact soil samples were taken from the upper soil layer and processed in a pedological laboratory. The Zhang method was used to evaluate the infiltration results. The results of soil analyzes and infiltration were processed numerically, plotted and subsequently described and compared.
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Architectural concrete
Novosad, Petr ; Ďurica,, Tibor (referee) ; Dulenčín, Juraj (referee) ; Klečka,, Tomáš (referee) ; Hela, Rudolf (advisor)
In the development of concrete structures and its finishes we are constantly looking for new ways to highlight the aesthetic value of the concrete. With all the possibilities of shapes, textures and colours, an architectural concrete in the hands of an architect and designer becomes a material, which can be used to express different individual and specific ideas. It is necessary to recognize and cope with these possibilities, but also the limits, which determine the properties of concrete as the proper design and implementation creates excellent finishes that are otherwise inaccessible to other materials and technologies. The theoretical part includes an extensive summary carries out a research on issues of architectural concrete and its production. From this research comes a new definition of architectural concrete and the newly redesigned and determined classes of architectural concrete with respect to the continuous development of technologies and production possibilities, rendering and surfacing. The aim of the thesis is to verify the possibilities of producing quality architectural concrete and additional treatment of the surface with respect to the desired aesthetic quality.
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Development of ultra lightweight concretes
Popelková, Adéla ; Hubertová,, Michala (referee) ; Hela, Rudolf (advisor)
This bachelor thesis deals with the technology of production of ultralight concretes using direct lighten cementing compound and at the same time indirect lighten using lightweight aggregate. Further work deals with the choice of suitable raw materials for these concretes. The practical part consists of a proposal of several different recipes, experimental verification and by comparing their properties in a fresh or hardened state.
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