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Modelování přírodních katastrof
Zuzák, Jaroslav ; Zimmermann, Pavel (advisor) ; Masec, Frant (referee)
This thesis introduces various approaches to natural catastrophe risk assessment in (re)insurance environment. Most emphasis and further elaboration is put on probabilistic models in comparison to the standard model as proposed by Solvency II. The outcomes of natural catastrophe modeling play an important role in the design of proper actuarial models related to catastrophe risk. More specifically it is shown that they can be entirely understood in a wider actuarial context, namely risk theory. Within the Solvency II framework, probabilistic model outcomes are translated by means of the proposed decomposition methodology putting them into a similar language of the standard formula in order to create the ability to compare different results implied by either probabilistic model or standard formula. This enables both comparison of the implied dependence structure of probabilistic model to standardized correlations assumed in Solvency II, and scenario year loss factors of Solvency II to implied damage factors of probabilistic models in defined cresta zones. The introduced decomposition methodology is illustrated by flood and windstorm model outcomes calculated on exposure data of Czech insurance companies and compared to the respective standard formula parameters and outcomes. Finally, other applications of the proposed decomposition methodology are introduced, such as measurement of diversification effect or blending of different results calculated by different models or even approaches to natural catastrophe risk assessment.
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Cellulose decomposition in selected wetlands
FILIPOVÁ, Marie
This work deals with the decomposition of cellulose in wetland. The speed decomposition has been studied in several areas. Mokré Louky u Třeboně, Záblatské louky, Červené blato mined and not mined. The intensity of degradation processes were determined using the litter-bags. The experiment was done for two years and each year was used another method. Bags with cellulose were placed in the soil and the soil surface. In this work the values were determined in different places and at different times.
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Decomposition of aboveground biomass of a herbaceous wetland stand
KLIMOVIČOVÁ, Lucie
The master?s thesis is part of the project GA ČR č. P504/11/1151- Role of plants in the greenhouse gas budget of a sedge fen. This thesis deals with the decomposition of aboveground vegetation in a herbaceous wetland. The decomposition rate was established on the flooded part of the Wet Meadows near Třeboň. The rate of the decomposition processes was evaluated using the litter-bag method. Mesh bags filled with dry plant matter were located in the vicinity of the automatic meteorological station at four randomly selected sites. Values of the decomposition rate were assessed in two experiments. In the first experiment the litter bags were fixed in April 2009. The litter bags were fixed in the vertical position and they had one size. Values of the decomposition rate were assessed for 6 sampling dates and the total exposure time was 2,5 years. The decrease of the total dry mass was 18,37 % in the first year and 13,05 % in the second year. The value of LDR was 0,7227 in the first year and 0,4740 in the second year. In the 2nd experiment the litter bags were fixed in November 2010. The litter bags were fixed in the vertical and horizontal position, respectively, and they were of two sizes (small, big). Values of the decomposition rate were assessed for 2 sampling dates and the total exposure time was one year. The total annual value of LDR was 0,5212 for the vertical bags and 1,0676 for horizontal bags.
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Decomposition Methods in Turbulence Research
Uruba, Václav
Nowadays we have the dynamical velocity vector field of turbulent flow at our disposal coming thanks advances of either mathematical simulation (DNS) or of experiment (time-resolved PIV). Unfortunately there is no standard method for analysis of such data describing complicated extended dynamical systems, which is characterized by excessive number of degrees of freedom. An overview of candidate methods convenient to spatiotemporal analysis for such systems is to be presented. Special attention will be paid to energetic methods including Proper Orthogonal Decomposition (POD) in regular and snapshot variants as well as the Bi-Orthogonal Decomposition (BOD) for joint space-time analysis. Then, stability analysis using Principal Oscillation Patterns (POPs) will be introduced. Finally, the Independent Component Analysis (ICA) method will be proposed for detection of coherent structures in turbulent flow-field defined by time-dependent velocity vector field. Principle and some practical aspects of the methods are to be shown. Special attention is to be paid to physical interpretation of outputs of the methods listed above.
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Decomposition of aboveground biomass of a herbaceous wetland stand
KLIMOVIČOVÁ, Lucie
This work deals with the decomposition of aboveground vegetation in wetlands. The decomposition process leads to the release of greenhouse gases, which are currently being studied primarily in relation to current climate change. The decomposition rate was established on the flooded part of the Wet Meadows near Třeboň. The intensity of degradation processes was evaluated using the litter-bag method. Bags of dry matter were located in the vicinity of the automatic meteorological station at four randomly selected sites in April 2009. The litter bags were fixed so that their positio followed the natural positionof the standing dead matter. Values of the decomposition rate were assessed for two sampling, summer and autumn 2009. The obtained values of decomposition rates are discussed with the results of Kovářová who used the litter-bags method on Wet Meadows near Třeboň in the past.
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Acitivity of phenoloxidases and peroxidases in the litter of spruce forest in Plešné and Čertovo lake watersheds
APPLOVÁ, Markéta
The aim of the study was to determine the activity of phenoloxidases and peroxidases in three dominating litter samples (Vaccinium myrtillus, Calamagrostis villosa and Picea abies) from Plešné and Čertovo lake watersheds. High activity of lignin-degrading enzymes was detected in litter incubated at 0°C. Activity of enzymes was in general higher at 10°C but the difference was not significant compared to 0°C. In Plešné Lake watershed high amount of phenolic compounds negatively influenced the activity of enzymes compared to Čertovo Lake watershed, where the effect of phenolic compounds was opposite. The highest activities of the enzymes were found in the Calamagrostis villosa litter from Plešné Lake watershed and in the litter of spruce needles from Čertovo lake watershed.
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System of evaluation of soil organic matter based on fractionation by level of hydrophilic characteristics and by characterisation of fractions with differential thermic analysis
STROSSER, Eduard
The contemporary methods of evaluation of the soil organic matter do not sufficiently characterize its stability. The aim of this study is to develop a method for soil organic matter stability evaluation. The four different methods were tested, two based on chemical principle a two on microbiology principle. The first method is based on sequential soil organic matter fractionation by a system of solvents with increasing polarity, the second method uses oxidizers with different oxidizing efficiency. In the third method micro-organisms decompose soil organic matter in anaerobic environment as well as in the four method, but this one makes use of up gas production measuring sensors. The method of sequential extraction is not suitable for practical use, the oxidation method is preferred. The oxidation method also both microbiology methods imply that the most important part of soil organic matter is decomposed rapidly or while using weak oxidizer. This fraction is the most important for evaluation decomposability and it is characteristic for particular soils. After decomposition of this part of SOM its remnant is decomposed steady and linear or micro-organisms are not able to decompose it.
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DECOMPOSITION METHODS FOR A PIV DATA ANALYSIS WITH APPLICATION TO A BOUNDARY LAYER SEPARATION DYNAMICS
Uruba, Václav
Separation of the turbulent boundary layer (BL) on a flat plate under adverse pressure gradient was studied experimentally using Time-Resolved PIV technique. The results of spatio-temporal analysis of flow-field in the separation zone are presented. For this purpose, the POD (Proper Orthogonal Decomposition) and its extension BOD (Bi-Orthogonal Decomposition) techniques are applied as well as dynamical approach based on POPs (Principal Oscillation Patterns) method. The study contributes to understanding mechanisms of a boundary layer separation process. The acquired information could be used to improve strategies of a boundary layer separation control.
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