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Optimisation of a die casting part production.
Vencálek, Jaroslav ; Janský, Milan (referee) ; Píška, Miroslav (advisor)
The project aim is an optimalization of production of pressure die casting, which serves as a one part of handle in office furniture area. The main emphasis was for mass finishing operation, which serves for rounding of very sharp part edges after die casting operation. A few tests of single mass finishing parameter was carried out and as result was a few partial recommendations for an increasing of production efficiency and improving of manufacturing process, namely an adjustment of separation cycle, proposal of optimum amount of pieces in each single batch and an innovation of chips type and dimensions. The project includes a proposal of a new and more efficiency layout of pieces on the transport pallet.
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Cryogenic Technique
Zrůst, Michael ; Milčák, Pavel (referee) ; Kracík, Petr (advisor)
Bachelor thesis deals with technology of cryogenic temperatures, liquefying gases in this temperature interval, effects of these temperatures on materials and insulations. In the introduction, brief history of development of this field. Next part is about gases which get liquefied in cryogenic temperatures and their applications. The largest chapter is chapter about liquefying in which principle of coolers, heat exchangers and liquefiers is described. Next, means of cooling by expansion, cooling cycles used to reach desired temperatures and ways of separating gas mixtures, are specified. In the last chapter insulation used to maintain cryogenic temperatures inside space is discussed.
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Determining the possibilities of increasing binding potencial of fly ash for the usage in cement composites
Jančaříková, Denisa ; Ďurica,, Tibor (referee) ; Klečka,, Tomáš (referee) ; Kulísek, Karel (referee) ; Hela, Rudolf (advisor)
The deliberate use of fly ash in the production of concrete has been used for decades, but recent trends tend to maximise its utility properties. These are different types of activations from chemical through thermal to mechanical. An alkaline agent is added to chemical activation which, by etching the glass structure of the ash grain, promotes its reactivity. Mechanical activation is mainly focused on granulometry and particle size distribution curve. In this thesis three mechanical activation methods are compared: separation the ash into fractions by grain size, mixing these fractions to achieve the ideal particle size distribution curve and grinding. Four types of ash were collected from the Tušimice power plant – ash from individual electrostatic separators (I, II and III) and SESYP ash which represents the total volume of production. Ash from individual separators differ not only in the particle size but also in the chemical composition and reactivity. Better properties generally have smaller ash particles. This is used by mechanical activation by sorting. When mixing the individual ash fractions, the aim is to achieve an optimal grading curve of either the ash itself or the fine particle set in the concrete. In this work, ash is only used to calculate the mixing ratio and the grading curve according to Funk was selected as optimal. The last compared option of activation was grinding ash. Grinding was carried out in an industrial mill for 15, 30, 45, 60 and 75 minutes. The efficiency of the modified ash was monitored for cement paste in terms of rheology and for concrete in terms of consistency, strength and durability. Based on the results we can say that mechanical activation by sorting is suitable for special purposes, but it’s necessary to realise that coarser ash fractions remain unused. When mixing the fractions to ensure matrix density, the efficiency was shown mainly on the durability characteristics. Grinding cause positive effect.
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Efficiency of selected chemical reactions on the membrane reactor
Liman, Martin ; Mirko,, Dohnal (referee) ; Svěrák, Tomáš (advisor)
This bachelor’s thesis focuses on the efficiency of reactions happening on the membrane reactor or also known as a contactor. The theoretical part contains basic insight into the theories needed to understand chemically physical phenomena on membrane contactors. Furthermore, the theoretical part serves as a recherche for modern membrane contactor technologies, including the examples of their usage. The practical part consists of a description of the membrane contactor that is used, the methodology of the measuring and the measured data output. Afterwards, the results are being talked over and developed further to the possible use in the current technologies.
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Friction and air feeders for paper sheets
Svoboda, Ondřej ; Košťál, David (referee) ; Brandejs, Jan (advisor)
The thesis is focused on summarizing the evidence on the issue of paper sheets feeding at the final processing of documents. The thesis includes dividing of paper feeders, their characterization, and description of friction and air feeders, which are most widespread. As a model for the description methods of sheets feeding were used machinery CFM 700 and GPM 540A of Cyklos company. The thesis also compares friction and air feeding from the constructional point of view. The conclusion focuses on the new methods in the paper feeding in future.
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Preliminary aerodynamic analysis of remotely controlled model with jet propulsion
Novák, Ondřej ; Zikmund, Pavel (referee) ; Popela, Robert (advisor)
This bachelor´s thesis deals with aerodynamic analysis of unmanned aircraft and subsequent changes to design of wing, its position and wing-fuselage junction. In this work emphasis is laid on flow separation, its interaction with other flow structures and its influence on aerodynamic properties. The goal of these changes to the aircraft is ensuring sufficient stability and controllability in low as well as high angle of attack flight. AVL, XFLR5 and CFD methods were used in the thesis. In case of inaccuracy of CFD calculation, two backup wing related modifications were prepared.
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Musk compounds in water biota
Zouhar, Libor ; Stoupalová, Michaela (referee) ; Vávrová, Milada (advisor)
Synthetic musk compounds (MUSK) or synthetic fragrances are organic substances commonly used as fragrant constituents of perfumes, detergents, cosmetics and personal care products. These compounds are discharged after use via domestic wastewater and sewage treatment plants to the aquatic environment. The result is accumulation in the environment and occurrence in a food chain especially of aquatic and marine ecosystems. Synthetic musk compounds are also found in surface water, fish tissues and also in body fluid (blood, urine, milk) and tissues of human body. Quantitative detection and studying properties of these compounds is an important activity because we have low knowledge about their fate in the environment (persistence, bioaccumulation) and toxicity. This diploma thesis is focused on three commonly used synthetic fragrances – tonalide, musk ketone and musk xylene. The base of this study was to perform a method optimisation for the determination of selected compounds in water and water biota (fish). The aim was determination of selected musk compounds in real samples (water, fish) and evaluation of the results. Pressurized solvent extraction (PSE) for fish samples and solid phase microextraction (SPME) for water samples were used for isolation of analytes from samples. The identification and quantification of analytes was carried out by high resolution gas chromatography – mass spectrometry.
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Suspension flow modeling
Hideghéty, Attila ; Koutný, Luděk (referee) ; Rudolf, Pavel (advisor)
Diplomová práce se zabývá prouděním v hydrocyklónu. Hydrocyklón je separační stroj, kterým slouží k oddělování pevných částice z kapaliny (nejčastěji z vody). Díky tangenciálnímu vstupu do zařízení nastává silné vířivé proudění, které způsobuje přisávání vzduchu přes horní a dolní výtok. Toto vzduchové jádro hraje důležitou roli v separaci částic. Výpočty jsou provedeny pomoci CFD.
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Portable and Miniaturized Separation Techniques Applicable for Food and Biotechnology Analysis
Dvořák, Miloš ; Pospíchal, Jan (referee) ; Bednář,, Petr (referee) ; Rittich, Bohuslav (advisor)
Capillary electrophoresis was used for determination of 6 fractions of caseins. Those fractions were measured in 144 samples of cow’s milk originated from the feeding experiment focused on explanation the influence of the feeding onto casein productions. In this work were separated 6 fraction of caseins first time with total resolution of the peaks. Capillary electrophoresis was applied for determination of short-chain organic acids during fermentation of wine must. It was compared the fermentation of must fermented by different yeast. The difference of profile short-chain organic acids during fermentation were not statistically significant. The once difference was in the utilisation of the malic acid and production of the lactic acid. A portable miniaturized system for medium pressure liquid chromatography was developed. The components were tested and system was used for the isocratic and gradient elution of various analytes (food dyes, parabens). New line of electroluminescent diodes (LEDs) for deep-UV areas of wavelength based on a different materials substrate was characterised. The new line was compared with old line LEDs. The new line LEDs was incorporated in deep-UV absorbance detectors. Detectors were characterised and tested for a detection various analytes in modes flow injection analysis and chromatography separation. First time was characterised this new line of the LEDs and the origin of the parasitic emission band produced by deep-UV LEDs light sources was explained. This origin is given by disturbances of a materials substrates. This work is a contribution for an advance of low-cost and portable systems and detection devices in the field of analytical chemistry.
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