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Dissolved and gaseous nitrogen losses in forests controlled by soil nutrient stoichiometry
Oulehle, Filip ; Chuman, T. ; Hruška, Jakub ; Krám, Pavel ; Navrátil, Tomáš ; Tesař, Miroslav ; Ač, Alexander ; Urban, Otmar
This study investigates the consequences of chronic nitrogen deposition in forests, including its effects on soil and surface water quality, and greenhouse gas emissions. To predict these effects, the authors explore the controls over dissolved and gaseous nitrogen fluxes in temperate forests. Their findings indicate that stream leaching losses of dissolved nitrogen correspond with the nutrient stoichiometry\nof the forest floor, with stream N losses increasing as ecosystems progress towards phosphorus limitation. Soil nitrogen storage increases with oxalate extractable iron and aluminium content. The authors estimate soil gaseous losses based on 15 N stocks, which averaged 2.5±2.2 kg N ha-1 year-1 , comprising 20±14% of total nitrogen deposition. They also extrapolate the current gaseous nitrogen loss flux from forests globally to be 8.9 Tg N year-1 , which represents 39% of current nitrogen deposition to forests worldwide.
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Carbon materials for power sources
Tichý, Jiří ; Bača, Petr (referee) ; Novák, Vítězslav (advisor)
This work deals with carbon materials and using them in electrochemical energy sources. Object of this work was to prepare carbon materials and investigate their electrical properties. The theoretical part objects of the carbon materials, their properties, application in electrochemical energy sources and measurement methods used in experimental part. Experimental part describes the preparation of the electrodes with various carbon materials and summarizes the results of measurements.
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Desing of the carbon cap for the bike's fork
Gallo, Dominik ; Čípek, Pavel (referee) ; Košťál, David (advisor)
This bachelor's thesis discusses problems and solutions of design of the carbon crown for the bike's fork. It shows an overview of the possible implementation of the initial design up to final part. The output will be the crown made of carbon composite by mould pressing. For manufacturing the prototype form will be used 3D printing – Fused Deposition Modeling.
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Development of negative electrodes for lithium-ions batteries
Drahokoupil, Petr ; Libich, Jiří (referee) ; Sedlaříková, Marie (advisor)
This thesis deals with lithiation of negative electrode li-ion batteries. In this thesis is used several electrode materials: carbon, FeCl3, lithiated carbon electrodes and silicon carbide. Reduction of irreversible capacity lithium-ion batteries leads to increased capacity and also we can use new materials as a positive electrode. Thesis deals with the differences in the properties of materials using lithiation and their use in practice
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Pyrolytic graphite
Chýlková, Adéla ; Adam, Ondřej (referee) ; Němec, Karel (advisor)
The purpose of this bachelor thesis was to write a literature search summarizing knowledge about carbon-based materials and experimental determination of thermal expansion and thermal balance of samples of various types of graphite and evaluation of measured data. The research part of the work describes most of the currently known types of carbonaceous materials, with a more thorough study of pyrolytic graphite. The whole next chapter was devoted to a more thorough study of pyrolytic graphite. The second part of the thesis is focused on the experimental determination of thermal expansion and thermal balance on selected graphite samples (natural, expanded, pressed expanded and pyrolytic graphite). We used dilatometric analysis and thermogravimetry to solve this task. Finally, the measurement data were processed into graphs and relevant tables and conclusions were deduced.
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Natural Graphite as Negative Electrode Material for Lithium-Ion Batteries
Paulovics, Petr ; Jahn, Michal (referee) ; Libich, Jiří (advisor)
This bachelor thesis deals with an issue of lithium-ion batteries. It is focused on the negative (anode) electrode materials, dealing with the study of their electrochemical properties. The aim was to study the capacity characteristics of active electrode materials based on natural graphite. Mainly it was assessed the relationship morphology electrode material and the pressing pressure due to the electrochemical properties of the capacitive electrode. The first part of the thesis contains a theoretical introduction to the negative electrode materials with focuses on the composition and overall analysis of the lithium-ion cell. The second part is focuses on the manufacture, assembly and measurement of lithium-ion cells.
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The Material Selection for Bicycle Frames
Šály, Peter ; Petrenec, Martin (referee) ; Němec, Karel (advisor)
Bachelor's thesis summarises basic information about materials that are used for production of bicykle's frames. It concerns not only with common materials that are the most used nowadays, thus aluminium alloys and composite materials – carbon in the concrete, but it also pointed on the other, alternative materials. It also explains specific terms that relate to concrete materials or to their technological treating. Each material has listed characteristic which is objective thus measurable and it results from physical-chemical's properties and treating possibilities of concrete materials. It conveys assumption of frame behaviour made from this material. Subjective characteristic is also listed and it results from practice – from the feelings by real ride. Comparison of these two approaches resulted in conclusion which may help in choosing material for bicykle's frame which we have specific requirements on. Next thesis concerns with usage of concrete materials by various producers whether world producers or national ones, with orientation on brands which are interesting because of their treating of unusual materials or they are interesting because of their specific treating of common materials. There is a brief review of most used materials for concrete types of bicycle's frames at the end of the thesis.
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Phase Transformations during Heat Treatment of Fe - C Materials
Škvarka, Jakub ; Pacal, Bohumil (referee) ; Molliková, Eva (advisor)
The goal of this thesis is a study of heat treatment of iron-carbon alloys from a physical angle. Characteristics of main components from this system and their modifications are described there. There is also described what is going on during heat treatment especially from an angle of thermodynamics and kinetics, thanks to available information from literature. The knowledge is applied on specific types of heat treatment of material and processes which can follow it.
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