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Shopping centre entrance area
Čech, Ondřej ; Sýkora, Karel (referee) ; Brosch, Petr (advisor)
Diploma thesis describes the design and assessment of roof structure that covers entrance of the shopping center. Structure has an irregular floor plan and roof height is 16.5 m. The material of the structure is steel S355. The construction is located in Hradec Kralove. Two options were processed that were designed and evaluated according to applicable standards. The work also includes the design of anchoring and selected joints.
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The Performance Evaluation of the Company using the EFQM Excellence Model
Cook, Jakub ; Čech, Ondřej (referee) ; Bartoš, Vojtěch (advisor)
The master’s thesis focuses on the performance evaluation of company EXprojekt s.r.o. using the EFQM Excellence Model. The theoretical part of the thesis explains the concept of performance and characterizes individual methods of measuring the company performance. In the practical part of the thesis the company is described, and its current situation is analyzed. Subsequently, the company’s performance is evaluated using the START Model, which is based on the principles of the EFQM Excellence Model. In the final part of the thesis are, based on the results of the evaluation, suggested measures that would increase the company’s performance.
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Calandering of li-ion electrodes and its impact on the final capacity of lithium-ion cell
Svoboda, Lukáš ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
There is an effort to produce lithium-ion batteries with maximal density of energy, or higher capacity of cell with the same size. Calendaring of electrodes is important part of manufacturing of batteries. Its parameters, mainly the pressure of calendaring and with it related the final compression ratio of electrode layers, affect parameters of battery significantly. It is the process of pressing electrode material coated on current collector with certain pressure and it reduces its porosity and thickness. The aim of this bachelor thesis is determination of suitable level of calendaring that increases specific capacity, but does not reduce its cyclability.
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Electrode materials and electrolytes for aluminium-ion accumulators
Benešová, Petra ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
This bachelor thesis presents a topic of aluminum-ion batteries, which have recently attracted great attention owing to their good electrochemical performance and possible use in commercially produced electronics. The paper introduces the basic principles of the function of aluminum-ion accumulators and their advantages, which are a main motivation for further research. The main feature of the theoretical part is an overview of the current state of research on suitable electrode materials and electrolytes for this type of accumulators. The experimental part is focused on the preparation of several carbon-based cathode materials, preparation of the IL-type electrolyte and subsequent cell assembly. The obtained results are evaluated and briefly discussed, taking into account the effects of the cell components and other factors.
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Design and testing of XRD holder for post-mortem analysis of li-ion battery electrodes performed in an inert atmosphere
Klvač, Ondřej ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
The work describes the design and manufacturing of a test device for post-mortem measurements of electrodes of electrochemical cells using X-ray diffraction spectroscopy. The theoretical part describes the diffractometer Rigaku Miniflex 600, for which the product is intended. At the same time, an overview of solutions in various applications is processed here in the form of a recherche. The practical part documents the current development of a new cell, on which tests were performed. Here is an overview of the influence of gases and insulating materials on the resulting data, especially distortion and attenuation. Subsequently, a new design with improved hermetic insulation and sample displacement error correction is described. The principle of operation of the manufactured cell, including the control unit and software, is elaborated in the form of technical documentation. Finally, the functionality is verified by comparing the diffractograms of the powder standards and the graphite electrodes.
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Influence of working conditions on the results of EDS in ESEM
Pospíchal, David ; Čech, Ondřej (referee) ; Čudek, Pavel (advisor)
The bachelor thesis deals with energy dispersion spectroscopy and detection of characteristic X-rays in the field of environmental scanning electron microscope. The aim of the semester work is to compare the results of elemental microanalysis of samples under optimal conditions and to monitor changes of results, when changing working conditions, resp. nitrogen and water vapor pressure in the sample chamber of the scanning electron microscope Vega3 XMU with LaB6 cathode. TESCAN, a.s equipped with Xflash 6 | 10 spectrophotometer. Bruker
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Synthesis and characterization of sulfurized polymers for electrochemical power sources
Svoboda, Lukáš ; Kazda, Tomáš (referee) ; Čech, Ondřej (advisor)
Batteries based on lithium-sulfur technology have the potential to increase the amount of stored energy in comparison with current lithium-ion systems while maintaining the same weight. Achieving this goal is possible due to the high theoretical energy density of sulfur, which exceeds the values of other materials used in batteries. However, these batteries suffer from several failing, which still hinder the practical use. The use of amorphous sulfur instead of its crystalline form might lead to increasing of durability and charge efficiency. Inverse vulcanization of sulfur seems to be the perspective method for the preparation of polymer sulfur because it prevents its recrystallization and stabilizes amorphous sulfur. The aim of this thesis is the preparation and study of properties of materials made of inverse vulcanized sulfur.
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The LiOh influence in alkaline accumulators
Prchal, Jiří ; Čech, Ondřej (referee) ; Pléha, David (advisor)
The deal of this thesis is study of the influence of LiOH added to electrolyte on Ni-Cd batteries. In theoretical part are analyzed properties of Ni-Cd accumulators in strong alkaline surroundings, especially with emphasis on structure changing of NiOH2 and NiOOH. In the second part of theoretical are also described methods for depositing Ni layers. In practical part electro-chemical spectrum and mass changing on Quartz crystal microbalance are measured by cyclic voltammetry method during charge/discharge process. The process of cation integration to the positive electrode structure in KOH, NaOH and CsOH electrolyte including related structural changes are observed.
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The influence of iron on nickel accumulator charging
Mičák, Tomáš ; Čech, Ondřej (referee) ; Pléha, David (advisor)
This bachelor's thesis is dealing with a problematics of iron influence on charging of accumulator, more precisely on its cathode. The theory describes comparision of an accumulators at our market, important properties of Ni-Cd accumulators, their function principle, events happening during charge-discharge cycles of Ni-Cd cells and measuring method that will be used to verify of the iron influence. The practical part deals with the influence of iron on the development of oxygen during process of battery charging, on how iron affects the potential shift of oxygen gassing and how temperature affects this event.
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Measurement of dielectric properties of liquid fuels for automotive power units
Redr, Martin ; Čech, Ondřej (referee) ; Chladil, Ladislav (advisor)
This bachelor thesis dealt with measuring of dielectric properties of propellants. The aim of the thesis was to find out differences between dielectric quantities of propellants from various manufacturers and in different proportions of refined to so-called bio-components. The theoretical physical principles of dielectric substances – permittivity and dissipation factor were described. In the thesis the most famous electrical insulation fluids whose dielectric characteristics are similar as propellants were mentioned. Furthermore, the study about dielectric properties of propellants and chosen fuels on the Czech market were mentioned. In the experimental part of the thesis, selected fuel samples at varying frequency and temperature were measured. These results were then evaluated and compared.
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