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THIN LUBRICANT FILMS STUDY USING SPECTROSCOPIC REFLECTOMETRY
Čudek, Vladimír ; Dzimko, Marián (referee) ; Navrátil, Karel (referee) ; Dobeš, Petr (referee) ; Křupka, Ivan (advisor)
ectroscopic reflectometry is measurement technique that enables the study of the thickness and refractive index of thin layers. This thesis deals with its use for the study of lubrication films within EHD contact and verifies a new approach suggested in recent publications. It is focused on the development of an optical arrangement and mathematical model for the lubrication film thickness measurement within the entire EHD contact. This technique brings the possibility to study the pressure distribution within the contact area through the evaluation of changes in lubricant refractive index.
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Nanorobots
Haluza, Lukáš ; Vrbka, Martin (referee) ; Křupka, Ivan (advisor)
The point of Bachelor´s work is to illustrate Nanotechnology and Nanorbots to all. The first part concerns Nanotechnology as a science, description of nanoworld and its explanation a technical terms. The second part concerns nanorobots, their construction, succeses which was reached, areas of use, plans and problems that inhibit their full usage in ordinary life
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Study of lubrication films formation under starved lubrication conditions
Košťál, David ; Hartl, Martin (referee) ; Křupka, Ivan (advisor)
The purpose of this thesis is to reveal production mechanisms of lubrication films between non-conformal surfaces in situations, when is not possible to designate lubrication regime as fully flooded elastohydrodynamic contact. Under certain conditions of lubrication volume, rolling speeds, temperatures, lubrication properties or loads could lubrication film decrease under values determined by fully flooded formulas. This regime is designated as starvation at it includes risk of increased wear. In this thesis the methodology and the new simulator of starving contact are described. Obtained film thickness results are compared with existing numerical models.
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Design of a translation stage for focusing objective inside the LIBS interaction chamber
Olejník, Ivan ; Křupka, Ivan (referee) ; Kaiser, Jozef (advisor)
This diploma thesis describes the design of a translation stage for focusing objective inside the LIBS interaction chamber. It contains a description of the fundamentals and basic functions of LIBS spectroscopy. Moreover, in the thesis an overview of different translation stages as possible LIBS components is given. Their advantages and disadvantages for use in a vacuum translation stage construction are evaluated. The thesis describes the final solution of a linear translation stage for focusing objective, and his advantages for LIBS method
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Study of Correlation between Grease Film Formations and Mechanical Losses on Various Surfaces
Sakai, Kazumi ; Glovnea, Romeo (referee) ; Gonçalves, David (referee) ; Křupka, Ivan (advisor)
Tato disertační práce se zaměřuje na studium závislosti mezi reakčním momentem ložiska mazaného plastickým mazivem s lithným mýdlem a vlastnostmi maziva, jako například tloušťka vytvářeného mazacího filmu, jeho reologie, struktura zpevňovadla, trakční vlastnosti či vliv topografie povrchu. Typ maziva poskytujícího nižší odpor závisí na podmínkách provozu ložiska, zejména rychlosti. Chování mazacího filmu za nízkých rychlostí má vliv na reakční moment ložiska v nízkých rychlostech. Mez toku a trakční chování koreluje s momentem ložiska za vysokých rychlostí. Schopnost zpevňovadla vstupovat do kontaktu má vliv na tloušťku filmu, vzhled kavitační oblasti na výstupu kontaktu a chování hladovění. Důvod vstupu zpevňovadla do kontaktu je jeho chemická struktura. Vysoká polárnost hydroxylových sloučenin zpevňovadla podporuje jeho vtažení kontaktními povrchy. Mazivo s nejvyšší polaritou prokázalo na površích obsahujících denty nejčastější vstup do prostoru dentů. Na základě předchozích pozorování je navržen popis principu mechanismu mazání.
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Wear of hard coatings
Černý, Libor ; Křupka, Ivan (referee) ; Omasta, Milan (advisor)
This bachelor's thesis was made as a description of the main technological methods, which are used in order to manufacture hard coatings. Applications of hard coatings are realized to improve tribological properties of components in various industries. The aim is to minimize the amount of wear and friction losses. Thesis also discusses methods of measuring the hard coatings wear. These methods are important to determine the properties of coating layers and their subsequent use. A lot of testing methods offer sufficient possibilities to test various mechanisms of wear in variety of laboratory conditions. Additionally in the end of the thesis there is an experimental wear measurement of specimen on tribometer using the "Pin on disc" method. Both size and type of the wear are evaluated by profilometer.
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Effect of additives on wear reduction of rubbing surfaces
Súkeník, Juraj ; Dzimko, Marián (referee) ; Křupka, Ivan (advisor)
Lubricants additives are inseparable component of modern high-tech lubricants. Viscosity index improvers additives play uncoverable role in a branch of boundary lubrication. They are designed to ensure sufficient oil film thickness in low speeds of frictional surfaces motion. This thesis deal with effect of specific viscosity index improvers additives on boundary lubrication film formation in elliptical contact. The purpose of this work is also checking the effect of concentration changing these additives on lubricantion film thickness formation.
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