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Actual trends in manufacturing of permanent patterns
Procházka, Michal ; Bouška, Ondřej (referee) ; Horáček, Milan (advisor)
This bachelor thesis deals with the more detailed description of various methods employed for the manufacturing of permanent patterns which are used for making of nonpermanent moulds. According to the type of materials the models are divided into the wooden, the metallic, the plastic and the models made from the resin. The work covers the description of handmade manufacturing which is performed either manually (generally in case of wooden models) or by conventional methods of machining. It also includes the CNC machining mostly used for the manufacture of larger models. Further, certain methods Rapid prototyping are described here but these methods are restricted in sizes of future model, as they are used for the models of smaller measurements. Finally, the newer methods including the methods of Additive manufacturing are also described in the work.
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NQR spectroscopy - design of measurement methods
Procházka, Michal ; Bartušek, Karel (referee) ; Steinbauer, Miloslav (advisor)
Nuclear quadropole spectroscopy is a modern analytical method for detecting specific solid state materials, e.g. explosives, drugs etc. It uses phenomenon of atomic nucleus called nuclear quadrupole moment. NQR method is very similar to common nuclear magnetic resonance (NMR) that is why major principles are explained using NMR. The thesis deals with basic principle of NQR, its usage for explosives detection and also detection of other chemical compounds and many other useful applications. The thesis deals with specific circuit design, techniques for sufficient sensitivity, impedance matching and circuit isolation. Practical part consists of simulations as well as designs of a few impedance transformers, pi-networks, and coils. Also experimental probe was created. In the last part, NQR workplace was assembled and a few chemical compounds were detected. These were KClO3, NaClO3 and NaNO2 . Finally minimum detectable amount of potassium chlorate as the strongest signal of these was determined.
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Diagnostics of thin layer deposition using dimethylphenylsilane monomer
Procházka, Michal ; Kudrle, Vít (referee) ; Krčma, František (advisor)
The aim of this thesis is a study of processes during organosilicone thin film deposition via plasma polymerization. Recently, thin films are the most expanding way of surface modification of materials. They are used as protective coatings, functional layers, they can increase or decrease adhesion to different compounds (e.g. water), or just improve mechanical properties of bulk materials. Plasma polymers, which are not known so long, are a modern trend in evolution of thin film deposition. They have perfect adhesion to the substrate and they are highly resistant against most of chemical compounds. Their structure is quite different from the structure of classical polymers. Recently, organosilicon compounds are used as precursors for plasma polymers because silicon built in the structure of plasma polymer allows thin film deposition on glass substrate and the organic part of monomer gives us infinite possibilities of modification. In our case dimethylphenylsilane (DMPS) was used as a monomer. Various RF low pressure discharges were used during this study. Plasma diagnostic was performed by optical emission spectroscopy of inductive coupled plasma. This method allows us to determine plasma composition during the deposition process. Thus we can predict the composition of deposited thin film according to input parameters. From relative populations of fragments we are able to find out optimal conditions for deposition process. We can also calculate temperature of particles in plasma which gives us some information about particle energies. The first part of the study deals with the identification of particles (fragments) created by fragmentation of monomer in plasma environment. We successfully identified hydrogen atomic lines of Balmer’s series in the spectra. Many rotational lines of hydrogen molecule were also detected. Atomic carbon occurred only in small amount. Much more carbon was detected in the form of CH radical. We also found some weak lines connected to atomic silicon. When we used a mixture of DMPS and oxygen, OH radical and O2+ were present in spectra. Next, optimal settings of deposition were determined for particular fragments from relative intensities of these fragments in optical emission spectra. Using this information we are able to set up the process to deposit thin films of desired composition and properties. We calculated electron temperature from intensities of hydrogen lines in Balmer’s series. Rotational temperature was obtained from CH radical intensity. Unfortunately, there was no convenient radical from which intensity we would be able to calculate vibrational temperature. All results and information obtained during the research can be used in industrial plasma polymerization processes and development of new coatings and functional thin films. Other studies on DMPS or similar monomer may also be realized to get more knowledge about processes in plasma and this thesis could serve as a basis for further research. Moreover, this study is a part of an international project. The aim of this project is to study processes during plasma polymerization both theoretically and practically. Once finished, the project and its results will be presented in scientific literature and at international conferences.
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Mobile germicidal source
Procházka, Michal ; Murina, Milan (referee) ; Steinbauer, Miloslav (advisor)
Germicidal light is a type of UV light which is able to kill bacteries and microorganisms. These germicidal lamps usually operate on the same principle like common fluorescent lamps but they emit the different spectra. For higher efficiency and longer lamp life it is desirable to use electronic ballast as a source for germicidal lamp which in version of integrated circuit offers further advantages. First part of the thesis describes the theory of UV desinfection and electronic ballasts. The second part is about the construction of the mobile germicidal source. In the last part of the thesis there is the germicidal mobile source tested against a few various mildews.
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Detection methods of energetic materials
Procházka, Michal ; Diviš, Pavel (referee) ; Friedl, Zdeněk (advisor)
A research on current methods of detection of explosives and related materials was made. At first the thesis studies methods of detection and analysis of explosives including chromatographic methods (TLC, GC, HPLC, IC), mass spectrometry and its variations, ion mobility spectrometry and infra-red spectroscopy. Next the attention is placed on detection of explosives in solid phase by X-ray detection, nuclear magnetic and quadrupole resonance and thermal neutron activation. Practical applications of these methods are of great importance in this thesis as well as their usage in the counterterrorist fight.
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Valuation of Baťa, a.s
Procházka, Michal ; Bernát, Michal (referee) ; Beranová, Michaela (advisor)
The aim of the master’s thesis is to valuate comapny BATA, a.s. using income – based valuation mmethods. Thesis is dividend into two parts, theoretical and practical. Theoretical part describes basic charakteristics of the terms, defines company and its value, overview of invidual methods and procedures used for valuation of the company. Practical part is focused on application of theoretical knowledge in practise. The master’s thesis contains economical analysis, especially strategic analysis, financial analysis and preliminary valuation of comapany based on value generators. Company value was based on two yield methods, especially method of discounted cash flow entity and method of economic addend value.
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Barriere layers for culture herritage objects preservation
Procházka, Michal ; Lehocký, Marián (referee) ; Zahoranová, Anna (referee) ; Krčma, František (advisor)
Every year, many archeological findings are discovered. It is necessary to document and conserve these items dug up from the ground. However, archeologists and conservators cannot handle such a big amount of newly found items. This work offers an alternative approach to standard conservation techniques, increasing the processing capacity and lowering the cost on items’ conservation. Studied alternative, mainly for protection of metallic artefacts, includes thin films based on parylene and organosilicons. Thin films were prepared on two experimental apparatuses. Parylene films were deposited by chemical vapour deposition (CVD). Final product was a thin film of parylene C. Organosilicon thin films were deposited via plasma enhanced chemical vapour deposition (PECVD). PECVD apparatus operates with capacitively coupled radiofrequently initiated plasma. Using hexamethyldisiloxane, thin films very similar to silicon dioxide were produced, thus called SiOx. Thin films were characterized by several methods and compared to standard treatment used by conservators – tannate layer, acrylic furnish Paraloid B72 and microcrystalline wax Revax 30. Parylene films showed excellent conformity and resistance to corrosion on iron substrate. First signs of corrosion were observed on layer of 5 µm thickness after 24 hours in salt fog. On samples coated by SiOx films, corrosion was spreading wide even during 1st hour of the corrosion test. Most probable cause was that SiOx film has thermal expansion coefficient different from iron substrate and due to this fact cracking occurs during cooling down of the treated substrate. On samples coated by standard treatment, corrosion occurred after 1-3 hours of the test. Oxygen transmission rate (OTR) measurements (performed on polypropylene substrate) confirmed good barrier properties of parylene C. Best parylene thin films had OTR approximately 170 cm3•m-2•atm-1•day-1. SiOx films reached good results with OTR 300 cm3•m-2•atm-1•day-1, compared to clean polypropylene substrate with OTR 1700 cm3•m-2•atm-1•day-1. Standard conservation layers could not be applied on polypropylene substrate, thus their OTR was not measured. We did not succeed in finding a substrate which is compatible for all types of treatments. Next, the study focused on combinations of thin films forming sandwich structures. All types let the corrosion attack the substrate during the 1st hour of the test. The cause was insufficient film thickness as well as crack ing of SiOx films due to different thermal expansion properties from the iron substrate. Although SiOx thin films were not deposited on substrate directly, they have excellent adhesion to parylenu and thus they could tear parylenu films due to thermal expansion. However, OTR measurements showed improvement in barrier properties. Multilayer parylene C–SiOx–parylene C–SiOx had OTR 5 cm3•m-2•atm-1•day-1. Final result is that parylene C thin films have better barrier properties than standard coatings and are suitable for conservation of metallic archaeological artefacts. SiOx films and multilayers showed poor anticorrosion protection of metallic substrates but they have good barrier and chemical properties in combination with other types of substrates. Mainly deposited on polymers, there is great potential for their application in many fields. Further research would be focused on new substrates for SiOx thin films and on the improvement of UV stability of parylene films.
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Comparison of accuracy of exercise heart rate mesurement in electronic watch without a chest belt - and by ECG
Dillingerová, Eliška ; Pokorný, Jan (advisor) ; Procházka, Michal (referee)
This bachelor work is focused on "Comparison of accuracy of exercise heart rate measurement in electronic watch without a chest belt - and by ECG". The objective of this work is to compare accuracy of the heart rate measurement with the sporttester Garmin Fenix 5 and ECG. The theoretical part describes the heart rate, its measurement, ECG, sporttester and studies concentrated on a similar topic. The practical part describes methodology, test group, measuring devices and measurement report. The measuring of heart rate is provided with both devices and with two exercise equipment: a bicycle and a treadmill.
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