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On The Analyse of High Productive Reaming Technology
Gashkova, Irina ; Slaný, Martin (referee) ; Píška, Miroslav (advisor)
Diplomová práce se zabývá analýzou technologie vysoceproduktivního vystružování. V rámci práce byly provedeny testy vystružování za různých technologických podmínek (vc=40, 60, 80, 100 m/min; f=0.2, 0.4, 0.6, 0.8 mm) na materiálu austenitické oceli DIN 1.4404 při použití vystružovací hlavicí MT3. Jednotlivé operace vystružování byly porovnány z hlediska parametrů jako tlačná síla, krouticí moment, výsledná drsnost obrobeného povrchu a dále z hlediska tvaru třísky. Následně byly vypočítány průměrné hodnoty a směrodatná odchylka naměřených parametrů. Dále bylo provedeno porovnání pomocí diagramů. Výsledky ukazují lepší kvalitu, nižší drsnost povrchu (Ra 0,37 µm) a méně zdeformovanou třísku při pomalejších řezných rychlostech (40 m/min) a menším posuvu na otáčku (0,2 mm). Výsledky také ukazují nárůst tlačné síly a krouticího momentu za uvedených technologických podmínek. Při zvyšující se řezné rychlosti vystružování tyto silové účinky klesají.
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Design of small CNC milling machine
Rajdl, Filip ; Pavlík, Jan (referee) ; Blecha, Petr (advisor)
The bachelor thesis deals with the design of headstock, spindle and Z axis of a small CNC milling machine. Firstly, the current state and production of small CNC milling machines is described. The other contains a system analysis of the given issue. Then input parameters are selected to be used for the necessary calculations. The last part of the thesis contains the structural design of the headstock and spindle with Z-axis feed, which is created in Autodesk Inventor. It includes a 3D model, assembly drawing, and production drawings.
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Optimization of production steering shaft
Hlavinka, Martin ; Kalivoda, Milan (referee) ; Jaroš, Aleš (advisor)
Bachelor thesis deals with the creation of the optimal divided chip in the turning technology. The material for production of the steering shaft is steel C35RC suitable for forming and turning from which semi-finished products are produced at horizontally forming presses. They are machined at the production robotized line where the problem with the undivided chip arises. For the specified set of cutting conditions the uses the cutting tools which aren’t very suitable for the given types of technological operations. The recommended values of cutting conditions are different from the specified set of cutting conditions. The result will be choice of new-cutting tools for turning technological operations to shape short divided chip.
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Application of Mass Spectrometry for the Determination of Oxidative Stress Markers and Mycotoxins
Čumová, Martina ; Večeřa, Zbyněk (referee) ; Hajšlová, Jana (referee) ; Vávrová, Milada (referee) ; Čáslavský, Josef (advisor)
The first topic presented in the dissertation thesis is determination of isoprostanes as markers of oxidative stress and other compounds affected by presence of oxidative stress. Isoprostanes iPF2-III, iPF2-VI, iPF2-VI, astaxanthin and polyunsaturated fatty acids (PUFA), especially arachidonic acid (AA) were monitored in Atlantic salmon eggs (Salmo salar). Methods for the determination of these compounds have been developed and optimized using chromatographic separation coupled to conventional or mass spectrometric detection. Freshly laid eggs, eyed embryos and non-viable eggs were used to test a general hypothesis that egg viability can be affected by susceptibility to oxidative stress, either through the specific fatty acid concentration and/or the antioxidant capacity of the eggs. Levels of isoprostanes and arachidonic acid (AA) were significantly higher in non-viable eggs than in control (eyed embryos) as well as relative abundance of PUFA. While no difference of isoprostanes was found between freshly laid and control those from the Atlantic stock except iPF2-VI which was observed under the LOQ in the control. Higher levels of PUFA and AA in comparison with the control were observed in the freshly laid eggs. However, the only statistically significant difference was observed in the amount of astaxanthin. Different levels of PUFA and astaxanthin may be related to their biochemical consumption during the development of eggs. This work evaluated potential effect on the viability of eggs Salmo salar due to the presence of oxidative stress. The monitoring of mycotoxins in food and feed was the subject of the second topic. Mycotoxins are secondary metabolites produced by fungi. They are ubiquitous undesirable natural contaminants that are toxic for humans and animals. Today are known more than 500 mycotoxins. However, only few of them are regulated by the European Union. The European Food Safety Authority (EFSA) was asked by the European Commission to provide a scientific opinion on other mycotoxins for which statutory limits could be developed. In this study is proposed simultaneous screening allowing fast, reliable and sensitive approach, identification and quantification of 17 mycotoxins in food and feed sample. The method includes both mycotoxins regulated by the EU and selected mycotoxins required by the EFSA (aflatoxins, deoxynivalenol, nivalenol, zearalenone, fumonisin, ochratoxin A, T-2 toxin, HT-2 toxin, enniatins and beauvericin). Analytes are isolated by the modified QuEChERS method. For separation and target mycotoxins detection, ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC –MS/MS) was employed. The method also allows determination of ergot alkaloids (ergocornine, ergosine, ergocryptine, ergocristine and their respective epimers). The developed method was used either for monitoring mycotoxins and ergot alkaloids in feed and raw materials and barley and malt prepared from it.
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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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Milling Machine for Machining of Plastics
Frejlich, Tomáš ; Brada, Michal (referee) ; Brandejs, Jan (advisor)
Bachelor thesis deals with the structural design of the longitudinal and transverse feed for the milling of embedded hollow fibers of fixed size used in heat exchangers and the design of these components during milling. The work contains a brief description of the routing, basic milling division and a brief overview of the kinds of lines that are use for machine tools. It als presents an overview of fastenings for easy and quick clamping of milling, individual design variations and optimal solution. The works also includes the drawing of the components and complete set. The results of the Bachelor thesis are used for the Laboratory heat transfer and flow at University of Technology, Faculty of Mechanical Engineering.
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Determination of selected perfluoroalkyl compounds in complex matrices
Ondreášová, Klára ; Vávrová, Milada (referee) ; Mgr. Petra Kosubová, Ph.D (advisor)
Diploma work focuses on the determination of selected representatives of perfluoroalkyl substances in complex matrices, particularly, in sewage sludge and feed. In case of sewage sludge, samples were extracted into methanol and three extractions techniques were compared: accelerated Soxhlet, pressurized liquid extraction and Powley method. Powley method showed sufficient efficiency, the lowest matrix effect and minimal background. Perfluorooctane sulfonate was present in all tested samples of sewage sludge (0.74–38.02 ng.g-1). Other detected compounds were perfluorodecanoic acid and perfluorooctanoic acid. Three extraction techniques were tested on feed samples (QuEChERS, fast methanol extraction and Powley method into acetonitrile). Powley method provided the cleanest extracts and showed simultaneously the highest recovery of native perfluoroalkyl substances and the lowest matrix effects. Perfluorooctane sulfonate and perfluorooctanoic acid were rarely present in samples of complete and supplemental feeds, while other perfluoroalkyl substances were found at levels below limit of quantification or they were not detected at all. Perfluorooctane sulfonate (0.100–2.768 ng.g-1), perfluoroundecanoic acid and perfluorotridecanoic acid were determined in all fish meal samples.
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Turning of steels at low depths of cut
Tichá, Dana ; Dvořáková, Jana (referee) ; Dvořák, Jaromír (advisor)
Thesis is devoted to the analysis of the competition of indexable cutting inserts, which are used for turning at lower cutting widths of the blade than the tip radius. Thesis is an analysis of five indexable cutting inserts from diferent companies. Furthermore the chip breakers of selected inserts are compared and finally the testing of the insert and its results based on metal chip shapes are described.
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Calculation of column destillation unit.
Bytešník, Jan ; Jecha, David (referee) ; Jícha, Jaroslav (advisor)
The bachelor's thesis is divided into three main parts. The first part discusses principles and theoretical base of the distillation process. The majority part of this thesis includes solution of elementar steps towards the resultant parameters of the distillation column. This results may be served like input parameters during other calculations, which can make an effective optimalization of the distillation column for the practical use. The last part of bachelor's thesis compares results of the second part with results, which was generated by ChemCAD aplication with the same input numerical values.
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