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Study of intercalation properties of electrode materials based on naturla graphite
Bílek, Lukáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This diploma thesis deals with the issue of lithium-ion accumulators. The thesis focuses on the negative electrode of lithium-ion accumulators made of natural graphite. The first part of this thesis points to the issue of electrochemical cells. In the theoretical part the thesis deals with the SEI layer, advantages, disadvantages, characteristics, operating principle and the use of lithium-ion accumulators. The practical part focuses on the electrochemical properties of negative electrode, especially the determination of the diffusion coefficient. Thesis also deals with electrochemical impedance spectroscopy (EIS) and its use in determining the equivalent replacement circuit and calculating the diffusion coefficient.
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Lithium-ion cell: Treatment of Natural Graphite by Lithiation Method
Bílek, Lukáš ; Kazda, Tomáš (referee) ; Libich, Jiří (advisor)
This bachelor thesis deals with the issue of lithium-ion accumulators. The thesis focuses on the negative electrode of lithium-ion accumulator made of natural graphite. In the theoretical part the thesis focuses on the characteristics, the operating principle and the use of lithium-ion accumulators. Negative electrode materials are also analyzed. The main topic of the thesis is the use of lithiation method which suppresses irreversible capacity losses with the improvement of the capacitance and current characteristics of the battery.
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Study of intercalation properties of electrode materials based on naturla graphite
Bílek, Lukáš ; Máca, Josef (referee) ; Libich, Jiří (advisor)
This diploma thesis deals with the issue of lithium-ion accumulators. The thesis focuses on the negative electrode of lithium-ion accumulators made of natural graphite. The first part of this thesis points to the issue of electrochemical cells. In the theoretical part the thesis deals with the SEI layer, advantages, disadvantages, characteristics, operating principle and the use of lithium-ion accumulators. The practical part focuses on the electrochemical properties of negative electrode, especially the determination of the diffusion coefficient. Thesis also deals with electrochemical impedance spectroscopy (EIS) and its use in determining the equivalent replacement circuit and calculating the diffusion coefficient.
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Lithium-ion cell: Treatment of Natural Graphite by Lithiation Method
Bílek, Lukáš ; Kazda, Tomáš (referee) ; Libich, Jiří (advisor)
This bachelor thesis deals with the issue of lithium-ion accumulators. The thesis focuses on the negative electrode of lithium-ion accumulator made of natural graphite. In the theoretical part the thesis focuses on the characteristics, the operating principle and the use of lithium-ion accumulators. Negative electrode materials are also analyzed. The main topic of the thesis is the use of lithiation method which suppresses irreversible capacity losses with the improvement of the capacitance and current characteristics of the battery.
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Potential use of Douglas fir for the enrcihment of tree species composition in forest stands of forest district Klokočná, Forests of the Czech Republic, State Enterprise
Ludík, Josef ; Bílek, Lukáš (advisor) ; Otakar, Otakar (referee)
This bachelor thesis evaluates the potential use of Douglas fir (Pseudotsuga menziesii /Mirb./ Franco) to enrich the woody species composition at Klokocna forest area, Konopiste forests, state-owned Forests Czech Republic, s. p. The introductory part of the review of literature deals with the morphology, the main distribution area, introductions, ecology, production and also cultivation of Douglas fir. The aim of this study was to obtain data for assessing the potential interspersed Douglas fir individuals for natural regeneration, to determine the degree of damage to wildlife and its effect on cultivation quality. Data were measured for evaluation and recorded on square plots. These areas were selected on the basis of the position of mother trees whose dendrometric characteristics were measured. In total, nine plots have been identified with an area of 3600 m2. Based on the measured data the amount of Douglas fir young growth was determined. It was also done measurement of dendrometric and growing characteristics at this regeneration of Douglas fir. On the basis of these findings silvicultural measures have been recommended.
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Impact of Silvicultural Measures on Some Mechanical Wood Properties of Scots Pine
Schönfelder, Ondřej ; Zeidler, Aleš (advisor) ; Bílek, Lukáš (referee)
The purpose of this study is to assess the impact of silvicultural measures on selected mechanical properties of Scots pine of the area Doksy and Plasy. Each area is characterized by growths that are typical for the locality. From areas Doksy were selected 3 stands and 2 from Plasy region. For each crop were chosen representative of the trees that were cut down, and testing material was produced. On test samples was determined density at 12 % level moisture, modulus of rupture, modulus of elasticity, toughness and compression strength in the fiber direction. All tests were carried out by standardized procedures. Using statistical methods, it was found that a statistically significant value of compared areas were only in the density. The others properties which were examined in the areas are statistically insignificant. However, when assessing individual stands with ANOVA was generally for the most of properties found statistically significant difference. This suggests that the pine wood properties are dependent on location. In horizontal plane strain was found a statistical significance for all of the tested characteristics. That shows that the position of the wood in the stem has impact on the mechanical properties. Furthermore, the individual results were evaluated in terms of dependence on the density. Which resulted in the majority of cases middle to high dependency.
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Ecological forestry – principles, experiences and possible applications in Czech rep.
Vysloužilová, Barbora ; Čada, Vojtěch (advisor) ; Bílek, Lukáš (referee)
Current methods of forest management are often unsatisfactory in terms of ecology. In the context of biodiversity conservation it is necessary to develop and apply alternative methods of forestry. Ecological forestry has been established as a response to criticism of the logging process, within which there is no emphasis on environmental functions. It is a collective term for methods and practices that replicate the natural ecosystem processes. Three basic principles of ecological forestry has been described and justified - conservation of biological heritage of natural disturbances; diverse interventions that maintain or create heterogeneity; enough time for the regeneration of vegetation. Further models were characterized by specific practical application and their application in the world. Finally, the possibilities of ecological forestry were summarized into a number of possible practical applications. It is rather general recommendations, in which inappropriate methods of practices are replaced with more ekological options, and the impact of these methods on the forest ecosystem has been explained.
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Canopy effect on the Scotch pine regeneration in understory
Kostohryzová, Aneta ; Ulbrichová, Iva (advisor) ; Bílek, Lukáš (referee)
The Pinus sylvestris natural regeneration growth and site characteristics effect were evaluated in the area of VLS ČR, s. p. divize Mimoň-Doksy in september of 2015. The dendrometric parameters of seedlings as listed: the total height, the diameter, the last 5 years height increment, the crown diameter, the quality and vitality of plants and the branch angle) were measured at nine plots. Also microsite characteristics, such as: herbal layer composition, light conditions, litter horizons and distance to the nearest adult tree) were noted at these sites. The 416 seedlings were measured in total. The main site characteristic with significant effect on the mean increment was direct photosynthetical radiation (r = 0,47). Other significat factors were the total and the diffuse photosynthetical radiation, the canopy and the amount of small bushes in herbal layer. There can be also concluded that good light conditions have statistically significant effect on the quality of seedlings. Influence of other site characteristics was not statistically significant.
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Root system morphology of bare root and containerized beech and oak plants
Becher, Vladimír ; Kupka, Ivo (advisor) ; Bílek, Lukáš (referee)
The thesis follows the bachelor thesis on comparison of morphological and economic parameters of various types of seedlings, which resulted in the planting of containerized and bare root seedlings of the European beech (Fagus sylvativa Linne) and the English oak (Quercus robur Linnaeus) in a forest regeneration in September 2011 and April 2012.
The measurement of the height and thickness of the root neck of the seedlings was carried out on designated plots in March 2015. I also investigated possible mortality from the afforestation inspection in July 2012. Furthermore, 154 seedlings, 84 containerized seedlings a 70 bare root seedlings, in order to evalutate the development of the root system, its possible deformation and subsequently detection of the volume by using xylometric method. The data collected in the field were processed into tables and compared with the results observed in the bachelor thesis.
The average figures for the height, the thickness of the root neck and the volume of the root system showed almost identical development of bare root and containerized seedlings in the forest cover, even though the figures of individual seedlings were highly variable. When reviewing the development of the root system, I found unacceptable deformation of the main taproot at 25% containerized seedlings and 20% bare root seedlings. The remaining seedlings were without deformation or with acceptable deformation of the taproot (wavy taproot, unbalanced taproot with the axis in the above-ground part, an outgrowth).
It was discovered that containerized seedlings were more easily removable from the ground, the seedlings were not sufficiently fixed in the ground and its root system was in some cases less developed than it was with bare root seedlings. This may be influenced by several factors, e.g. the influence of richness of the root system on fine roots, the obstruction of development of the root system by cementing the surrounding soil when using the slit method.
The bare root seedlings, the English oak in particular, showed root development to a greater depth, which is very important not only for sealing but also as an important factor in the drought season and extreme summer temperatures when there is rapid exhaustion of the moisture in the upper horizon of the soil due to the vapor.
Unfortunately, it was not possible to verify these findings in a larger sample size, as there had been major damage of the forest.
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Analysis of production potential of forest stands on former agricultural land in Doupovske hory Mts. (VLS ČR, s.e., Division Karlovy Vary)
Sedláček, Jiří ; Bílek, Lukáš (advisor) ; Otakar, Otakar (referee)
This diploma thesis evaluates the structure and development of forest stands on former agricultural land in the conditions of Doupovské hory, VLS ČR, s.p. The main objective of this research was to compare production and growth characteristics of following tree species: Picea abies (L.) KARST., Larix decidua MILL., Acer pseudoplatanus L., Alnus glutinosa (L.) Gaertn. and Populus nigra L. Stand structural characteristics were measured on 5 circular plots (500 m2) for each tree species. Beside basis dendrometric characteristics, health status of individual trees was evaluated and increment cores were taken for the description of growth dynamics (n > 10 for each tree species). Software Statistica 12 was used for the comparison of production parameters. Comparing all types of damage, the difference between alder (0.084) and maple (0.091) was not statistically significant, while larch (0.356) and poplar (0.513) both were significantly different from the first two mentioned tree species. The highest damage was confirmed in the case of spruce (0,736), which differed from all other species. On the other hand, spruce had the highest standing volume (416.8 m3.ha-1, 29.7 SD), followed by poplar (350.0 m3.ha-1, 91.7 SD). The lowest standing volume was stated in the case of maple (182.9 m3.ha-1, 73.3 SD), followed by larch (238.3 m3.ha-1, 57.7 SD). For all tree species we saw during the observation period decrease of diameter increment. The steepest decline is obvious for larch and alder, on the contrary relatively stable growth pattern was stated for maple and to a certain extent also poplar. Based on the research results, management guidelines for the selection of appropriate trees species and regeneration of studied stands are proposed.
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