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Analysis of the gas flow in the passage of the primary electron beam differentially pumped chamber depending on the shape of the nozzle inlet
Hladký, David ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
It is necessary to separate sample chamber with pressure up to 2000 Pa and the surroundings of tube with pressure 0.01 Pa with help of a differential pumped chamber at the environmental scanning electron microscope This differential pumped chamber is to be designed so that it has to manage to separate sections with very different pressures sufficiently and in the trajectory of transitting (overflying) prime electrons the average value of pressure and density has to be as low as possible, so that it would occure the lowest diffusion of these electrons, which is caused by collisions of electrons and air molecules too. It were created axisymmetric 2D models variant of Differentially pumped chamber with different opening angles of the clone, which were analyzed to choose the best variant. The Ansys Fluent systeme using finite volume method for analysis of fluid flow was used for analysis.
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Analysis of the gas flow when pumping vacuum for newly designed scintillation detector
Poruban, Milan ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
The aim of this thesis is to study the issue of eniveromental scanning electron microscopy and pumping gas to create vacuum in the newly designed scintillation detector. Further, creating a model of recently proposed scintillation detector and simulating and analyzing pumping gas in differentially pumped chamber of detector. The theoretical part deals with electron microscopy, electron sources, electron optics and secondary electrons detectors. It is also presented which signals are generated by the electron beam on the surface of a solid. Further fluid flow issues and equations describing the flow in the solved chamber are dismantled. Furthermore, the impact of gaseous environment on the trajectory of primary electrons, because there are collisions of primary beam with atoms and molecules of gas. The following section discusses creating, quality and importance of the network in mathematical modelling. A method of a final volume used to calculate the differential equations describing the flow of gas at the premises of the detector is described . The practical part consists in creating a model of scintillation detector and analyzing the gas flow in drawing a vacuum in the newly designed scintillation detector. At the end the simulation results of gas flow are compared for different variants of apertures and various pressures on the neck of a scintillation detector designed for optimum performance of the detector. The outcome of this thesis is model of newly designed scintillation detector with optimized shapes of apertures according to functional requirements.
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Optimalization and methods of internal resistance measurement of the lead acid battery cell
Fojtlín, Branislav ; Vaculík, Sebastian (referee) ; Křivík, Petr (advisor)
The aim of this master´s thesis is optimalization and methods of measuring the internal resistance of lead acid accumulator. First focus is on the analysis of properties of lead acid accumulators, their construction and negative effects. After that a method of measuring the internal resistance of experimental accumulator is processed. In this thesis practical design of measuring workplace is completed. The frequency analysis of impedance of charging and discharging accumulator is performed. After that the graph of internal resistance for various amplitude intensities, for various signal forms and also for various size of frequencies of alternating current are processed. The result of this thesis is a comparison of graphic works addictions charging and discharging characteristics of lead acid accumulator and determination of optimal amplitude, form and intensity of frequency of alternating current in point when internal resistance is evaluated correctly.
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The effect of pressure on the electrode system in lead acid batteries with experimental glass fibers aditives electrodes
Fryda, Daniel ; Vaculík, Sebastian (referee) ; Bača, Petr (advisor)
This Master’s thesis deals with the lead-acid batteries, which are alternativ power supply. The lead-acid batteries are the oldest type of battery cells. This lead-acid batteries have a great use in hybrid electric vehicles (HEVs), which operate in different modes of vehicle operation. These modes correspond to the reactions taking place during discharging and charging the battery. The lead-acid batteries in hybrid electric vehicles work in mode PSoC. The practical part of the Master`s thesis examines how the characteristics of lead-acid batteries are modified due to admixture of glass fibers into negative active material and application of pressure to the electrode system.
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Impedance measurements of lead-acid accumulators
Vaculík, Sebastian ; Bača, Petr (referee) ; Abraham, Pavel (advisor)
The main aim of this paper is to contribute to the elucidation of electrochemical processes. These processes occur in the investigated experimental lead-acid cell. For this purpose, electrochemical impedance spectroscopy was used. There are two methods of measurement presented. First one is used to measure impedance between electrodes. Second one is used to measure impedance of collector ribs inside positive or negative electrode. The results are represented by electrical equivalent circuits, whose elements are described in detail in the theoretical part.
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CNC router for PCB
Gerják, Rastislav ; Vaculík, Sebastian (referee) ; Vyroubal, Petr (advisor)
In mechanical industry, both additive and subtractive manufacturing methods are controlled by instructions in G-code, making it possible to utilize both technologies in one modular device. Main objective is to design, construct, and calibrate multipurpose machine based on RepRap 3D printer, which will be able to use attached spindle to precisely mill light materials. Particular emphasis is given to ability to carve a pattern and drill holes in plated substrate in order to create functional PCB by incision.
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Influence of the pulse charge on properties of the lead acid batteries
Zbožínek, Štěpán ; Vaculík, Sebastian (referee) ; Křivík, Petr (advisor)
The presented master´s thesis deals with lead-acid batteries and methods of their charging. First part shortly describes the problems of lead-acid batteries. There are introduced common principles, type of construction and requirements, that should be complied with lead-acid batteries. Following part discusses the basic characteristics of charging. There is given a detailed description of current pulse charging method, on which is also mainly focused this master´s thesis. For this charging method, several basic experiments were done in order to verify functionality of the measuring device, software, the tested cells and primarily to verify charging modes. The goal of this thesis is to find out suitable mode of pulse charging, which would be fast as well as tested cells-friendly. The conclusion of this master´s thesis contains a resume of acquired theoretical knowledge and an evaluation of measured results, on which was the appropriate charging mode proposed.
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The cycle modes of lead-acid batteries
Mičák, Tomáš ; Tošer, Pavel (referee) ; Vaculík, Sebastian (advisor)
Main goal of the diploma thesis is to examine lead-acid accumulator and to study cycling modes in different setups. Theoretical part describes history, types of maintenance-free batteries, degradation mechanisms and possibilities to remove them. Practical part involves the production of electrodes and experimental cell, composition of active mass and measurement of internal resistance. Different configurations for deep cycling are researched as well. The results of the work are summarized and commented at the conclusion of the thesis.
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