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Verification of setting speed and building adhesion of PU adhesives depending on external conditions
Slatinská, Jana ; Žák, Ladislav (referee) ; Kubíček, Jaroslav (advisor)
The company IFE a. S. (Knorr - Bremse) in Modřice needed to verify the curing process of glued joints with the used adhesive Sikaflex®-265. The aim was to find out whether a controlled environment is needed for curing and mainly find out influence of factors on the curing process and the velocity of building adhesion. The main factors that were investigated were temperature, humidity, the ratio of the Sikabooster® P-50 to the tested adhesive and the curing time. The result then shows which factors have an influence and which only minimal. The aim was also to verify the strength of the joint, which is stated by the manufacturer after a specific time. The impact on open technology time has not been measured.
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Production of the material chamber to a blast furnace
Netopil, Lubomír ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The theses deals with the production of furnace-top hopper. Mainly it is focused on the welding of abrasion-resistant materials and steel for pressure vessels using the FCAW method. These materials are described in detail in the research section, including the additional materials used, the welding methods used and NDT tests used to check the quality of the welds. The practical part then describes the technological process of production. Subsequently, the procedure of welding of the abrasion-resistant steels and steel for pressure vessels, including the developed WPS, is elaborated. The procedure of testing by non-destructive tests of selected combinations of materials with documented test reports and a plan of inspections and tests is also described. Finally, a technical and economic evaluation of production was performed.
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Optimalization of the welding process for low - pressure tubular sets
Urbánek, Štěpán ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis examines the implementation of the production process of low-pressure pipe sets for hydraulic aggregates in the company Bosch Rexroth. The first part presents a literature analysis of used technologies and basic welded materials. The second part focuses on selected subprocesses ensuring the production and proposals for their streamlining. It includes a summary of responsibilities across departments and a template for processing the necessary technical documentation for the smooth running of production. Another proposal includes a technological procedure for practical verification of the production, which simultaneously serves as a basis for measuring the welding time. The reason for the implementation of this production was the extended delivery time of pipe sets from suppliers and possible financial savings. The practical part is concluded with a technical and economical evaluation, which expresses the possible financial savings in the production of low-pressure pipelines instead of the current state involving the cooperation with suppliers.
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Nickel alloy overlay welding parameters optimalization
Lauš, Lukáš ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The aim of these master's thesis is to choose and optimize parameters of the Venturi tube throat weld cladding. The Venturi tube is made from carbon steel ASME SA-106 Grade C. The weld cladding is performed by plasma transferred arc welding. The throat is weld overlaid with nickel base powder Inconel 625. The overlays are made without oscilation. The main requirement was to find a maximum possible powder feed rate and others welding parameters to develop maximum welding speed and productivity on automat. Visual and penetrant testing on the overlays were performed. Metalographic samples were prepared. On the samples was meassured dilution, overlay thickness and width of the heat affected zone. Results are compared with parameters succesfully used in the cooperating company.
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Materials change of parts for harvester chain production
Houdek, Radim ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The work is focused on the track element, namely the replacement of the crossbar material from steel 27MnCrB5-2 to steel 30MnB5 from which the other parts of the cell, the cubes, and the bar are made and welded by the GMAW method. Changing the material and omitting the preheating phase would reduce the production time of the cell by approximately half the time. The theoretical preheating temperature calculated according to the relevant standard for both steels exceeded 200 ° C. Test specimens imitating the weld between the crossbar and the cube were welded on which a qualitative evaluation was performed. These were weldments of 30MnB5 steel with preheating (sample 10), 30MnB5 steel without preheating (sample 11) and 27MnCrB5-2 steel with preheating (sample 9). In terms of macrostructure, non-penetrations were found on all samples. Martensitic structure was found in all areas by microstructural observation. When measuring the hardness according to the Vickers method, approximately the same hardness profile was obtained in all weld areas of samples 10 and 11. The highest value reached 450 HV1 and exceeds the maximum hardness recommended by the standard. Due to very similar test results for 30MnB5 steel weldments with and without preheating, it is possible not to perform preheating. However, the results may be skewed by the relatively small size of the test specimens. For a reliable evaluation and final decision, it is necessary to perform tests on a real crossbar after complete production.
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Surface treatment of a composite part
Bahenský, Štěpán ; Žák, Ladislav (referee) ; Kubíček, Jaroslav (advisor)
This diploma thesis focuses on composite materials and the possibility of their surface treatment with a focus on painting. The aim was to create a layer on the surface of the material that would serve as protection against UV radiation and subsequent degradation. The first theoretical part is devoted to the material composition. In the subsections, the different types of functional components of the composites are presented. Their possible applications as well as their advantages and disadvantages are described. In addition, the theoretical part is supplemented by the types of methods used for the production of composite materials and the subsequent surface preparation in order to improve the adhesion properties of the material to the paint. The second part, which was developed in cooperation with GDP Koral, s. r. o., deals with the chosen type of surface treatment for composite materials produced by the pultrusion method. The UV coating method was chosen, where the wet layer of the varnish is cured by UV radiation. Two sets of samples were created, which differ in both the method of varnish application and the parameters of the curing process. Mechanical tests were then performed on each sample to verify the resulting adhesion capability of the paint system. The practical part also includes the design of possible technologies for the implementation of the surface treatment in the production line. In the third part, a techno-economic evaluation is presented, which focuses on the cost comparison of standard painting and painting with UV varnishes. The final section contains a summary of the findings and an evaluation of the chosen type of coating with respect to the results of mechanical tests and the possibilities of application in a pultrusion production process.
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Retrospektivní bibliografie: Využívání zdrojů otevřených dat
Horčáková, Václava ; Kubíček, Jaromír
Východiskem pro zpracování této metodiky se stal kritický rozbor bibliografické produkce z oborů společenských věd za posledních deset let, v němž jsou posouzeny samostatně vydané soupisy nebo práce publikované v časopisech a ve sbornících a také monografie, v nichž bibliografie tvoří samostatnou část k biografické studii. Metodika retrospektivní bibliografie je předkládána ve třetím roce plnění projektu NAKI II Česká literatura ve světě a světová literatura v Čechách v letech 1989–2020, v rámci něhož již byla využita ve zpracování bibliografické části. Rozborem současného bibliografického zpracování domácích a zahraničních databází i tištěných výstupů byla zjištěna jejich zřejmá neúplnost. Až využíváním národních a mezinárodních zdrojů otevřených dat je možné dosáhnout potřebné úplnosti i relevance dat. K tomu napomáhají jak přehledy světových a národních databází, tak i pokyny ke zpracování záznamů jednotlivých typů dokumentů, jak jsou uvedeny v této metodice.
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Gravitation in higher dimensions
Kubíček, Jan ; Pravdová, Alena (advisor) ; Žofka, Martin (referee)
The thesis starts with a brief introduction to the algebraic classificati- on of tensors and spacetimes in higher dimensions. Attempts to generalize the Goldberg-Sachs theorem are also discussed. There is a summary of main results for optical matrices of algebraically special spacetimes in higher dimensions. The optical matrix for a type III spacetime in six dimensions is found using Bianchi identities. A few properties of type III optical matrices in a general dimension are also found. Various properties of equations obtained from Bianchi identities for type III spacetimes are studied in appendices. 1
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Thin discs and rings as sources of Weyl space-times
Kubíček, Jan ; Semerák, Oldřich (advisor) ; Žofka, Martin (referee)
Static and axially symmetric vacuum solutions of Einstein's equations can be descri- bed by the Weyl metric which only depends on two unknown functions, given by the Laplace equation and a line integral. In this thesis we study some properties of two Weyl space-times whose sources are one-dimensional rings - the Appell ring and the Bach-Weyl ring. On the behaviour of proper distances and geodesics in the central region we demonstrate that in Weyl coordinates these sources represent directional singularities. 1
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Contextualising or relativising evil? A probe into US antebellum slavery
Kubíček, Jan ; Ženíšek, Jakub (advisor) ; Topolovská, Tereza (referee)
The purpose of this thesis is to examine the abolition of antebellum slavery in the US through a leftist prism introduced by Michael Parenti. The first part provides a brief explanation of Parenti's theory on an example of the late Roman republic and its politico-economic background, which is depicted in The Assassination of Julius Caesar. In this part is also covered the historical precedent of slavery along with specific scientifically based arguments in favour of slavery developed by Samuel Cartwright. The last chapter gives a description of the process of abolition and eventually an analogy between Roman senatorial democracy and the antebellum slavery is established on a premise that in both the cases the privileged social class influenced historical narration of those events for its own benefit to cover its economic interests. Keywords: Michael Parenti, slavery, historical narrative, exploitation, Samuel Cartwright, the process of abolition
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