|
|
What hinders the recovery of zooplankton communities in acidified lakes?
Jůzek, Václav ; Sacherová, Veronika (advisor) ; Kaňa, Jiří (referee)
Acidification of soil and water environments, which emerged with the beginning of the Industrial Revolution, became a major ecological problem of the 20th century. The increase in emissions and subsequent deposition of acidifying substances into the environment has caused a significant decline in abundance and biodiversity of aquatic organisms in European and North American lakes. Emissions causing acidification have been reduced since the 1990s, yet aquatic ecosystems are not returning to their pre-acidification state. This thesis concludes the factors affecting the course of chemical and biological recovery of aquatic ecosystems affected by atmospheric acidification. The reviewed literature shows that communities newly established in acidified waters seek a new ecological equilibrium, and thus recolonization of native species is not limited by merely unsuitable water chemistry itself. Bohemian forest lakes have also been affected by acidification and are now in the process of recovering. The main factors affecting the recovery of natural zooplankton communities in lakes are high aluminium concentrations, periodic pH fluctuations, catchment characteristics and, more recently, climate change and associated bark beetle-induced tree dieback. Keywords: acidification, recovery, zooplankton, Bohemian...
|
|
|
The Impact of Load Folowing in Providing System Services of the Selected Dukovany Power Plant Unit on the Parameters of the Core
Kaňa, Jiří ; Ing. Jakub Lüley, PhD., ÚJFI FEI STU v Bratislave (referee) ; Katovský, Karel (advisor)
To operate safely and reliably, the power grid needs power sources that are capable of providing flexibility. In the scenario that emission-free sources dominate the energy mix, the provision of these services will largely be the responsibility of nuclear power plants. Changing the output of a nuclear power plant is burdened with a number of specificities that need to be respected compared to the output changes of thermal power plants. This thesis explores the possibilities of using the reactor at the Dukovany power plant to provide load-following. From a theoretical point of view, it presents information on the needs of the power system, the general possibilities and limitations of using nuclear power plants for load-following and presents the historical context of this practice. After applying different scenarios of load-following, the simulation results are assessed from safety, operational and economic points of view.
|
|
|
Electricity balance in a typologically local system of an energy community with electricity production
Kaňa, Jiří ; Radil, Lukáš (referee) ; Drápela, Jiří (advisor)
The European trend of increasing the share of renewables and decentralizing energetics is leading to an enthusiastic debate over local energy communities. Mass support for this arrangement may seem to solve many of today's energetics problems, but at the same time we need to keep in mind the problematic aspects of the energy communities themselves. In particular, there is a need to resolve the economic and legal relations of the members of the community and to ensure the technical feasibility of such a transformation. This work summarizes the existing knowledge about the idea of energy communities, presents a summary of the most important information from a technical, economic and legal point of view in the context of the European and Czech environment and draws attention to the most pressing issues. Furthermore, the creation of a model of electricity consumption, photovoltaic production and metrics for measuring electricity with respect to the actual properties of the modeled systems is presented. In the final phase, a simulation of energy flows is performed on a model of an energy community with a specific topology with evaluation of the results.
|
|
|
Long-term trends in sulphur and nitrogen wet deposition - a comparison of Northern Hemisphere regions
Vlnasová, Eliška ; Hůnová, Iva (advisor) ; Kaňa, Jiří (referee)
This scientific literature review examines the time trends of wet atmospheric deposition of sulphur and nitrogen over a four decade period in three regions of the Northern Hemisphere, namely Europe, North America and Southeast Asia. The wet atmospheric deposition processes transport sulphur and nitrogen compounds from the atmosphere to the Earth's surface via vertical or horizontal pathways. Excessive levels of these deposited compounds can cause a number of environmental problems, such as change in biodiversity, degradation of forest stands or change in water and soil chemistry. It is therefore necessary to monitor and evaluate these trends. Sulphur and nitrogen can enter the atmosphere through anthropogenic emissions, among other sources. The change in sulphur and nitrogen emissions over the last four decades has undoubtedly influenced the time trends of wet deposition. The aim of this work is to evaluate these patterns in addition to the sulphur and nitrogen trends. This work also addresses the change in wet deposition ion ratios, in particular the change in the ratio of NH4 + to NO3 - in the wet deposition of nitrogen. Wet deposition of sulphur, in line with a significant reduction in sulphur compounds emissions, records a noticeable decrease in both Europe and North America, but wet...
|
|
|
Alternativní paliva pro spalovací motory
Káňa, Jiří
This Bachelor Thesis on Alternative Fuels for Combustion Engines briefly discusses current and alternative fuels used in internal combustion engines. Initially, the development of the internal combustion engine is the present. It also discusses the advantages and disadvantages of fuels, their production and use, market introduction. In conclusion, it will evaluate the future use and direction of new biofuel production.
|
|
|
Electricity balance in a typologically local system of an energy community with electricity production
Kaňa, Jiří ; Radil, Lukáš (referee) ; Drápela, Jiří (advisor)
The European trend of increasing the share of renewables and decentralizing energetics is leading to an enthusiastic debate over local energy communities. Mass support for this arrangement may seem to solve many of today's energetics problems, but at the same time we need to keep in mind the problematic aspects of the energy communities themselves. In particular, there is a need to resolve the economic and legal relations of the members of the community and to ensure the technical feasibility of such a transformation. This work summarizes the existing knowledge about the idea of energy communities, presents a summary of the most important information from a technical, economic and legal point of view in the context of the European and Czech environment and draws attention to the most pressing issues. Furthermore, the creation of a model of electricity consumption, photovoltaic production and metrics for measuring electricity with respect to the actual properties of the modeled systems is presented. In the final phase, a simulation of energy flows is performed on a model of an energy community with a specific topology with evaluation of the results.
|
|
|
Acid/base character of dissolved organic carbon in soil and surface waters
Vanerová, Zuzana ; Hruška, Jakub (advisor) ; Kaňa, Jiří (referee)
This thesis deals with acid-base properties of dissolved organic carbon (DOC), which markedly affect chemistry of surface and soil water in mountain catchments. It describes long-term trends of acid-base character of organic acids (humic and fulvic acids) in two acid-impacted peaty catchments Tajga and Černý potok in Slavkov Forest, western Czech Republic between 1993 - 2010. Area was significantly acidified by sulfur emission from coal-burning power plants in the region which burned coal with a high content of sulfur (1 - 15 %). These power plants were desulphurized between 1994 - 1999 and observed changes are significantly affected by decrease of strong mineral acids atmospheric deposition. Changes during the period 2006 - 2010 were also studied in soil waters from Načetín in Ore Mountains. There are three forest stands - spruce, beech and limed spruce stand. Limed spruce stand was limed in August 2007. For an evaluation of similarity of acid/base character of DOC samples from Sweden, Portorico and Congo were also taken. Many studies examined DOC acid/base character using different analytical methods. These methods produced different and hardly comparable results. In this work rightness, reproducibility and errors of one of these methods - titration after transfering acids to H+ cycle - was tested. Method...
|
|
|
Analýza technických parametrů vznětových spalovacích motorů
Káňa, Jiří
The diploma thesis "Analysis of technical parameters of compression ignition engines" deals with the current concept of diesel engine construction. The introduction introduces the development of a diesel engine to the present. Furthermore, it discusses the current state of the engine design and its problems, there are presented the technical parameters of the selected set of diesel engines. The technical parameters are tabular, there is a graphical and computational analysis. The final stage of the work is to discuss and conclude on the topic of diesel combustion engines.
|
|
|
The usage of Global Navigation Satellite Systems in the transnational transport of dangerous goods
Darmovzal, Pavel ; Zelený, Lubomír (advisor) ; Káňa, Jiří (referee)
The master thesis The usage of Global Navigation Satellite Systems in the transnational transport of dangerous goods examines the possibilities of space-based radio-navigation systems in the transport sector, specifically in the carriage of hazardous materials. The author puts an emphasis on identifying the economic and other benefits, as well as the downsides from the key users perspective, which is accomplished by means of interaction with said stakeholders. The dissertations final part aims to point to the factors decisive in the future development with regard to societal needs on both national and European Union levels.
|
|
|
Acid/base character of dissolved organic carbon in soil and surface waters
Vanerová, Zuzana ; Hruška, Jakub (advisor) ; Kaňa, Jiří (referee)
This thesis deals with acid-base properties of dissolved organic carbon (DOC), which markedly affect chemistry of surface and soil water in mountain catchments. It describes long-term trends of acid-base character of organic acids (humic and fulvic acids) in two acid-impacted peaty catchments Tajga and Černý potok in Slavkov Forest, western Czech Republic between 1993 - 2010. Area was significantly acidified by sulfur emission from coal-burning power plants in the region which burned coal with a high content of sulfur (1 - 15 %). These power plants were desulphurized between 1994 - 1999 and observed changes are significantly affected by decrease of strong mineral acids atmospheric deposition. Changes during the period 2006 - 2010 were also studied in soil waters from Načetín in Ore Mountains. There are three forest stands - spruce, beech and limed spruce stand. Limed spruce stand was limed in August 2007. For an evaluation of similarity of acid/base character of DOC samples from Sweden, Portorico and Congo were also taken. Many studies examined DOC acid/base character using different analytical methods. These methods produced different and hardly comparable results. In this work rightness, reproducibility and errors of one of these methods - titration after transfering acids to H+ cycle - was tested. Method...
|
guest ::
RSS feed.