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Synthesis of ceramic powder materials in the presence of the ultrasound field
Kočicová, Pavla ; Bartoníčková, Eva (referee) ; Částková, Klára (advisor)
The thesis concerns the synthesis Ceric Oxide, Samarium Oxide and Samarium doped Cerium Oxide. The theoretical part is focused on the characteristics, applications and possibilities of the Cerium Oxide synthesis. The experimental part describes the precipitation of the Cerium Oxide powder. The synthesis of the powders were proceeded in the normal conditions or in the presence of ultrasonic field. For the purposes of description of the ready powders the x-ray diffraction (XRD) and the raster electron microscopy (SEM) were used. The ceramics were made of the selected powders where the structure was described by SEM, the density by Archimedes´Method and the grain size by grid-line intersect method. Using the precipitation synthesis, the pure powders of Ceric Oxide, Samarium Oxide and Samarium doped Cerium Oxide were prepared. The powder morphology was strongly involved by the pH level and by ageing time. The ultrasound was accelerating the ageing. At the values of pH > 11 the rodlike particles were created. The ageing time and the ultrasound supported the creation of the rodlike particles. The ceramics made of the powder with the presence of the rodlike morphology showed the density up to 97,14% of the theoretical density.
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The Changes in Structure of Steel P91 after Short Annealings
Král, Lubomír ; Čermák, Jiří ; Král, Petr
Phase composition of the steel P91 during annealing was studied with the aim to reveal the evolution of new phases. In this paper, the precipitation was characterized using energy-dispersive X-ray spectroscopy (EDS) and electron diffraction in transmission microscopy (TEM). Only Nb-rich particles were found in the studied samples austenitized at 1423 °C for 20h and water cooled. After tempering at 673 °C for 2 h, the formation mainly M3C type carbides and after tempering at 873 °C for 2 h, the formation of M7C3 and M23C6 was observed. These structure changes play an important role for stability and also carbon diffusion.
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Analysis of monthly precipitation totals from selected monitoring stations in Europe
Krause, Patrik ; Helman, Karel (advisor) ; Kladívko, Kamil (referee)
This thesis is focused on analysis of time series of monthly precipitation totals for four European stations for the years 1913 to 2012. The data were obtained from European database of ECA&D. The aim of this thesis is to find out development of time series and predict precipitation for the year 2013. Prediction of future development of time series is made by using regression modeling of seasonality and Box-Jenkins methodology and the results obtained by the two methods are then compared. The thesis is divided into theoretical and practical parts.
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Atmospheric deposition of substances in the Czech Republic and abroad
BARTŮŠEK, Ondřej
This thesis is focused on atmospheric deposition of substances in the Czech Republic and abroad. There are also briefly explained concepts such as source pollution emissions and air pollutants, which are depended on each other and which are closely linked with atmospheric deposition. There is also explained the process of formation of atmospheric deposition. There are also described in detail the types of atmospheric deposition, their structure, removing a procedure for estimating the size of atmospheric deposition. To get an idea of the work the values of atmospheric deposition in Europe, China, North America and in the last row in the Czech Republic, where is briefly described the trend of atmospheric deposition. Furthermore, there are station network in the Czech Republic. The last part of the thesis deals with the development of the atmospheric deposition of sulfur, nitrogen and hydrogen ions in the Czech Republic and at certain stations.
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The change of annual and seasonal precipitation totals in the Czech Republic during 1961-2012
Střeštík, Jaroslav ; Rožnovský, J. ; Štěpánek, P. ; Zahradníček, P.
Using the monthly values of precipitation totals at 267 stations in the Czech Republic a longterm change has been estimated at each station for the last 50 years. Annual totals for the whole country display a slight increase, however, supplemented by a much stronger fluctuations from year to year. Long-term changes in annual totals at different stations and in different regions are different. In southern and western Bohemia precipitation totals increased more, in Elbe lowlands and in a large part of the Moravia, rather a small decrease in rainfall has been observed. Long-term changes depend only slightly on the total rainfall at the respective station or in the region. Summer precipitation totals increased more than annual averages, while spring precipitation totals decreased, at other times seasons the change is negligible. At the same time, the annual variation changes slightly: maximum precipitation has shifted from June to July and August.
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The comparison of water and matter flows in small catchments in the Šumava Mountains depending on landscape management.
VÁCHA, Aleš
The present thesis deals with the comparison of water flow and quality of water flowing from small watersheds under different farming methods on the right bank of Lipno in the Bohemian Forest. Watersheds are comparable to its size, exposure, altitude, climatic conditions and differ in land use and management. Solution in bachelor thesis contributed to more accurate flow measurement and analysis of data from 2008 to 2013. The evaluated results show that the drained basin used as pasture (Mlýnský) has drained in average of 70 %, the runoff in the watershed covered with forest, wetlands and meadows (Horský) is 39 % and the runoff from watershed covered with forest (Bukový) is 33 % of water, that the basin falls in precipitation. During the period the average annual water flow rates were 43.1 l.s-1 with a maximum of 662.9 l.s-1 on Mlýnský creek (2 June 2013), 28.6 l.s-1 with a maximum of 451.2 l.s-1 on Horský creek (2 June 2013) and 24.5 l.s-1 with a maximum of 220.0 l.s-1on Bukový creek (2 June 2013). The greatest variation values were recorded in the catchment area of the Mlýnský creek. The results show a direct correlation between the values of runoff and the amount of dissolved solids expressed through the electrical conductivity of the water. The average value of conductivity is 84 ?S.cm-1 in Mlýnský creek, 43 ?S.cm-1 in Horský creek and 39 ?S.cm-1 in Bukový creek. The solution in bachelor thesis confirmed that land use is an important factor in the watershed water balance and also in the quality of the effluent.
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Precipitation variability in the czech land since ad 1500. How strong is the signal contained within documentary sources?
Dobrovolný, Petr ; Brázdil, Rudolf ; Trnka, Miroslav ; Kotyza, O. ; Valášek, H.
Past climate may be reconstructed from a number of proxies. Some of them are “natural archives”, such as tree rings, ice cores and boreholes, most of which are sensitive to air temperature. Other valuable information can be also found in “man-made archives”. Various sources of documentary data very oft en refer not only to temperature but also to other aspects of past weather and climate, such as dry and wet periods. We use the long and homogeneous precipitation series from the recent instrumental period to calibrate precipitation indices derived from older documentary sources. Th e primary objective of this contribution is to provide a quantitative reconstruction of precipitation in the Czech Lands for the last 500 years. Calibration and verifi cation statistics are used to evaluate the strength of the signal. Reconstructed precipitation series are compared with similar Central European documentary-based reconstructions, as well as with reconstructions based on a range of natural proxies.
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Factors affecting the runoff response of watersheds to precipitation
DROZDOVÁ, Martina
This bachelor thesis is focused on the factors that affect the drainage basin of the response. It contains a literature review, which deals with the hydrological cycle characteristics of precipitation, surface runoff and flood and erosion protection. The aim of the work is to evaluate the factors that adversely affect the runoff from the catchment.
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Comparison of selected methods of calculating baseflow in a small basin and evaluate influnence of baseflow to concentrations of phosphorus in total runoff.
ŠVARCOVÁ, Eliška
This thesis is focused on the methods of separation of baseflow and comparing of these metods. It is analyzing concentrations of total phosphorus in the total runoff and influence of baseflow to concentrations of phosphorus in total runoff. The studied area is subcatchment P52 in the catchment Kopaninský flow. Subcatchments P52 is small (64,93 hectares), drained agro-forestry catchment in Českomoravská vrchovina (Czech-Moravian highlands), with a large proportion of forest area (64% forest and 31% of arable land). Studied the period is hydrological period 2009 - 2011. To obtain the necessary results are used daily flow, daily concentrations, daily precipitation of rain gauge station Velký Rybník and monthly precipitation from rain gauge stations of the ČHMŮ (Czech Hydrometeorological Institute) in Humpolec. For the separation of the baseflow and comparison of methods were selected five methods: - method of digital filter according to Chapman (1999), - method UKIH designed by Institute of hydrology (1980), - method RDF proposed by LINE AND Hollick (1979), - method FUKIH proposed by AKOSY AT. AL. (2009) and - method of Kille (1970). All methods are simple to perform and not challenging to input data. When comparing methods, the main problem is that, the results obtained by different methods are very different. Another point of this work is to evaluate the concentrations of total phosphorus in the tatal runoff. Here is analyzed series of daily concentrations of total phosphorus and monthly and annual average concentrations. Low and high concentrations are compared with the values ??of precipitation and clinks are searched between these values. The main problem is that, the concentration of phosphorus are not dependent only on precipitation. The last point is solution of influnence of baseflow to the amount of total phosphorus in the runoff. Here is used the procedure which described BYSTŘICKÝ in its work (2012). There are determined values concentrations typical of baseflow, for direct runoff and total runoff. Groups of values ??are mutually tested and compared. The results show that, the baseflow is negligible contributor of phosphorus to the total runoff, but to achieve more accurate results would be needed to analyse a longer time period (eg 10 years) and compare the results with several different river basins.
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Local climate and its impact on the application of organic agriculture in the selected area
KOUKOL, Marek
The aim of this study is to evaluate the local climate in the selected area and assess its impact. Monitoring will be situated in South Bohemia in Nové Hrady on an organic farm called Farm Besednice Ltd. This company is mainly focused on agricultural activities. The main interest is cattle breeding and cultivation of permanent grassland, i.e. production of hay and silage for farm´s own breeding and hay for export. Beside that a cultivation of fruit trees is other interest of this farm. There are many aspects that affect the economy. Therefore we are finding what agricultural activity favors and what does not, both in terms of weather, as well as in the practical side of farm´s own experiences
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