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Study of laser wobbling welding process through the radiation of plasma plume
Mrňa, Libor ; Horník, Petr ; Jedlička, Petr ; Pavelka, Jan
During laser welding with wobbling to the vector of the welding speed adds trivial movement of the beam in the shape of a circle or other shapes. Therefore, the laser beam moves with much higher current speeds than during normal welding. The melting of material on the leading edge of the keyhole occurs periodically. This fact is reflected in the character of the radiation of plasma plume over the keyhole. Experiments were conducted in which it was obtained spectrum of plasma plume radiation by using autocorrelation function for different parameters of circular wobbling (circle diameter, frequency) and for different materials. In the spectra are found the higher harmonic frequency of wobbling. The results were also compared with the radiation of the plasma plume during pulsed laser welding where the laser beam also periodically melts the leading edge.
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n-3 polyunsaturated fatty acids in prevention of cardiovascular diseases
Pavelka, Jan ; Kraml, Pavel (advisor) ; Černá, Milena (referee)
Clinical trials have documented beneficial effect of n-3 polyunsaturated fatty acids on health. Regular dietary intake of n-3 PUFAs decreases the risk of cardiovascular dieseas. n-3 PUFAs may be a safe and effective supplement to drug treatment for reducing the risk of myocardial infarction, arrhythmia and sudden cardiac death. n-3 PUFAs show antiatherogenic properties; e.g. they decrease inflammation, stabilize atherosclerotic plaques and prevent other chronic deseases. For primary prevention it is recommended to eat fish at least twice a week, people with documented coronary heart disease should consume 1 gram of n-3 PUFAs daily. Fish oil and oily fish (losos, tuna, trout, mackerel) are rich in EPA and DHA. ALA is found e.g. in flax seed oil.
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Radio frequency resonator for feeding ion trap
Jedlička, Petr ; Pham, Minh Tuan ; Čížek, Martin ; Pavelka, Jan ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Číp, Ondřej
Two versions of resonators were designed and manufactured - asymmetric and symmetric.\nThe resonator consists of a coil and capacity of ion trap which makes parallel resonant circuit.\nEnergy is supplied to the resonator through the coupling inductance. Resonator assembly was equipped with outputs for monitoring high-frequency voltage. Both versions have been tuned and tested.\n\n
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Tool for Easy Coding and Debugging of PHP Application
Pavelka, Jan ; Křivka, Zbyněk (referee) ; Marušinec, Jaromír (advisor)
The goal of this master's thesis is an introducing with tools for easy coding and debugging of PHP applications and to implement such tool on the basis of analysis of common requirements and specific requirements of IS VUT designers. The project includes an introduction with important ideas and terms referring to tool, analysis and specifications of requirements and design and implementation of final tool.
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Transport and Noise Characteristics of MOSFET Transistors
Chvátal, Miloš ; Hudec, Lubomír (referee) ; Koktavý, Bohumil (referee) ; Pavelka, Jan (advisor)
This doctoral thesis is focused on the analysis of transport characteristics of submicron and micron transistors MOSFET. The assumption is a constant gradient of concentration, which leads to the fact that the diffusion current density is independent of the distance from the source. Active energy was determined from temperature dependence. The proposed physical model made it possible to determine the value of access resistance between drain and source their temperature dependence. Based on the assumption that the divergence of the gradient of the current density in the channel is zero. IV characteristics of the transistor MOSFET are derived and conducted experimental monitoring current channel depending on the collector voltage for the series of samples with different channel lengths in a wide temperature range from 10 to 350 K. Information on the concentration of charge transport in the channel and the position of the Fermi level at the point of active trap, which is the source of RTS noise, is obtained from the analysis of the transport characteristics. Determining the concentration of charge transport and the position of the Fermi level is important because these variables determine the intensity of quantum transitions and their values are not the same throughout the length of the channel. It was experimentally proved from the analysis of the characteristics of RTS noise that concentration at the local channel decreases with increasing current at a constant voltage on the gate and a variable voltage at the collector. Further, the position of active traps of RTS noise was intended and it was found that this is located near the collector. Active trap is located at the point where the Fermi level coincides with energy level of the traps.
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Eclipse platform plugin creation
Pavelka, Jan ; Buchalcevová, Alena (advisor) ; Ženíšek, Jan (referee)
Purpose of this thesis is to create a methodology for Eclipse plugin development based on Methodology for small software projects (MMSP). Methodology designed in this thesis can be used by developers who develop plugins for Eclipse. First part describes Eclipse platform, its architecture and its fundamental principles, Eclipse Rich Client Platform and Eclipse Integrated Development Environment. Another topic presented in this part is framework for automated testing of web applications Selenium, which relates to practical part of the thesis. Methodology for small software projects is pre-sented next with Eclipse plugin development extensions. Practical part of this thesis deals with development of Eclipse Selenium plugin for Integra-ted Testing Node project. This part provides examples of principles of methodology presen-ted in first part of the thesis and provides basic description of functions of the plugin. The result of this part is working Eclipse plugin.
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Use schlieren method for displaying flow in laser technologies
Mrňa, Libor ; Pavelka, Jan
It is important to know the flow of gas protective atmosphere for the laser welding degree of protection of the weld pool from the atmosphere and for the interaction between the gas and the plasma plume rising from the keyhole. The gas flow from the nozzle during laser cutting of material has a significant impact on the quality of the final cut. In both cases the schlieren method a very useful tool for understanding the dynamics of gas flow. There were performed multiple experiments to clarify the flow of various kinds of gas (argon, helium, nitrogen) and their dynamics.
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Succession Planning in the Organization
Babíčková, Kateřina ; Stříteský, Marek (advisor) ; Pavelka, Jan (referee)
The master's thesis is about succession planning in the organization. The theoretical part is focused on defining basic principles of succession planning and describes related areas of personal work. Then it discusses the influence and importance of succession planning and its implementation in the organization. The next part of the thesis provides information about approach to succession planning of companies in the Czech Republic based on questionnaire research. The practical part of the thesis introduces Kooperativa pojišťovna a.s. and analyses its system of succession planning. The thesis suggests opportunities for improvement of this system based on theoretical findings and approaches of other companies.
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The project of selecting the human resources information system presented on the particular example
Náhlovská, Klára ; Střížová, Vlasta (advisor) ; Pavelka, Jan (referee)
The Master thesis The project of selecting the human resources information system presented on the particular example is focused on the selection of a suitable personnel information system (PIS) for Jan Becher Karlovarská Becherovka a.s. company (Jan Becher). The main objective of this thesis is decide upon the best supplier of the PIS whose offer will be the most suitable for the requirements specified by Jan Becher company. In order to achieve this main objective of the thesis, there are the following targets. The first one, and most important, is to analyze and comprehend the way the human resources activities are currently being done. Based on the analysis the system's functional requirements will be specified. In addition to this, the selection criteria and desired target conditions will be set up. The second one is to carry out an IT focused research. This is done in order to address potential suppliers and obtain and assess the given quotations. Thereafter, the decision on the most suitable supplier of PIS for Jan Becher will be taken. The thesis is divided into the theoretical and practical part. The theoretical part is to define terms such as human resources evidence, human resources information system and a model of selecting and deploying PIS. In the practical part the company Jan Becher is introduced. Subsequently, the reasons laeding the company to a change in the current PIS are listed. Especially this part is focused on the analysis of the current situation in the company, market analysis of the information and communication technologies, assessment of the quotations and selection of the suppliers of PIS for the Jan Becher company.
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