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Stochastic discrete modeling of progressive damage of concrete structures
Kučera, Michal ; Sadílek, Václav (referee) ; Vořechovský, Miroslav (advisor)
The work focuses on the use of deterministic discrete modeling with representation of spatial randomness in material parameters to simulate a series of experimental tests of concrete specimens in the shape of a dog bone, loaded in excentric uniaxial tension. The main focus is on the influence of the size of the structure on its mechanical properties, especially nominal strength (Size effect). The specimens are modeled as a plane stress problem using available discrete computational methods.
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Reliability analysis of embankment dams endangered by filtration deformations
Čejda, Marek ; Baroková,, Dana (referee) ; Fošumpaur, Pavel (referee) ; Říha, Jaromír (advisor)
Subject of the dissertation is a probability analysis on creation of embankment subsoil filtration deformations. Out of the broad topic of filtration deformations, the dissertation is focused at initiation of the process. At this phase, the overlying layers downstream of levee get uplifted, and eventually get breached. The process of downstream subsoil failure probability estimation is formulated using mathematical and statistical modelling. Within the scope of parametrical study the suggested method is applied onto a test environment. Results of the probability estimation are compared with results obtained using Limit state design method. The results of stochastic modelling can be used for improvement of Limit state design method precision.
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Stochastic discrete modeling of progressive damage in concrete structures
Kučera, Michal ; Sadílek, Václav (referee) ; Vořechovský, Miroslav (advisor)
The work focuses on the statistical strength of structures made of quasi-brittle ma- terials, specifically concrete. Special attention is paid to the influence of the size of the structure on strength and on the entire process of material failure during loading. The mechanics of these processes are modeled using discrete models, and these models are also considered in a probabilistic variant with spatially variable material parameters. Spatial variability is then modeled using random fields. The work clarifies the effect of diffuse damage in the volume of the structure before reaching the maximum load on the further course of dissipative processes, especially on the shape of the fracture process zone and subsequently on its interaction with the random variability of material parame- ters in eccentrically drawn dogbone-shaped bodies. In addition to the tools of stochastic computer fracture mechanics, an analytical model based on averaging and subsequent analysis of the minimum of the random field is presented
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Stochastické modelování reakčně-difuzních procesů v biologii
Lipková, Jana ; Maslowski, Bohdan (advisor) ; Vejchodský, Tomáš (referee)
Many biological processes can be described in terms of chemical reactions and diffusion. In this thesis, reaction-diusion mechanisms related to the formation of Turing patterns are studied. Necessary and sufficient conditions under which Turing instability occur is presented. Behaviour of Turing patterns is investigated with a use of deterministic approach, compartment-based stochastic simulation algorithm and molecular-based stochastic simulation algorithm.
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Stochastic discrete modeling of progressive damage of concrete structures
Kučera, Michal ; Sadílek, Václav (referee) ; Vořechovský, Miroslav (advisor)
The work focuses on the use of deterministic discrete modeling with representation of spatial randomness in material parameters to simulate a series of experimental tests of concrete specimens in the shape of a dog bone, loaded in excentric uniaxial tension. The main focus is on the influence of the size of the structure on its mechanical properties, especially nominal strength (Size effect). The specimens are modeled as a plane stress problem using available discrete computational methods.
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The influence of stochastic behaviour of ion channels on the signal and information transfer at excitable neuronal membranes
Šejnová, Gabriela ; Kuriščák, Eduard (advisor) ; Maršálek, Petr (referee)
The stochastic behavior of voltage-gated ion channels causes fluctuations of conductances and voltages across neuronal membranes, contributing to the neuronal noise which is ubiquitous in the nervous system. While this phenomenon can be observed also on other parts of the neuron, here we concentrated on the axon and the way the channel noise influences axonal input-output characteristics. This was analysed by working with our newly created computational compartmental model, programmed in Matlab environment, built up using the Hodgkin-Huxley mathematical formalism and channel noise implemented via extended Markov Chain Monte Carlo method. The model was thoroughly verified to simulate plausibly a mammalian axon of CA3 neuron. Based on our simulations, we confirmed quantitatively the findings that the channel noise is the most prominent on membranes with smaller number of Na+ and K+ channels and that it majorly increases the variability of travel times of action potentials (APs) along axons, decreasing thereby the temporal precision of APs. The simulations analysing the effect of axonal demyelination and axonal diameter correlated well with other finding referred in Literature. We further focused on spike pattern and how is its propagation influenced by inter-spike intervals (ISI). We found, that APs fired...
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Reliability analysis of embankment dams endangered by filtration deformations
Čejda, Marek ; Baroková,, Dana (referee) ; Fošumpaur, Pavel (referee) ; Říha, Jaromír (advisor)
Subject of the dissertation is a probability analysis on creation of embankment subsoil filtration deformations. Out of the broad topic of filtration deformations, the dissertation is focused at initiation of the process. At this phase, the overlying layers downstream of levee get uplifted, and eventually get breached. The process of downstream subsoil failure probability estimation is formulated using mathematical and statistical modelling. Within the scope of parametrical study the suggested method is applied onto a test environment. Results of the probability estimation are compared with results obtained using Limit state design method. The results of stochastic modelling can be used for improvement of Limit state design method precision.
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Stochastické modelování reakčně-difuzních procesů v biologii
Lipková, Jana ; Maslowski, Bohdan (advisor) ; Vejchodský, Tomáš (referee)
Many biological processes can be described in terms of chemical reactions and diffusion. In this thesis, reaction-diusion mechanisms related to the formation of Turing patterns are studied. Necessary and sufficient conditions under which Turing instability occur is presented. Behaviour of Turing patterns is investigated with a use of deterministic approach, compartment-based stochastic simulation algorithm and molecular-based stochastic simulation algorithm.
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Modelling population structure and their changes: Neolithic demographic transition in Central Europe.
Galeta, Patrik ; Brůžek, Jaroslav (advisor) ; Černý, Viktor (referee) ; Fialová, Ludmila (referee)
Neolithic dispersal in Europe has been alternatively explained through spread of farmers (migrationist position) or by adoption of farming by Mesolithic foragers (indigenist position). Mixed explanations have considered a combination of both processes. Neolithic dispersal in Central Europe was traditionally viewed as migrationist process. It was believed that farmers colonized the area and replaced indigenous foragers. During the last decade, authors have adhered to integrationist view as they have observed the continuity between Mesolithic and Neolithic technologies. Interestingly, the most recent genetic analyses again invoked the idea of colonization. Surprisingly, little attention has been paid to demographic modeling. The farming quickly spread in Central Europe between 5 600 and 5 400 calBC. Assuming colonization, Neolithic dispersal in Central Europe would have to be associated with high fertility rate of farmers. Our goal was to test whether the fertility rate of farmers was high enough to allow them to colonize Central Europe without admixture with local foragers. We produced four stochastic models of population dynamics of farmers during their colonization in Central Europe. The principle of Model 1-3 is based on methods of population projections. Model 4 stems from the wave of advance...
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Analysis of relation between macroeconomic indicators and economic results of a company
Scigel, Pavel ; Dlouhá, Zuzana (advisor) ; Formánek, Tomáš (referee)
The Czech Republic's economic performance is measurable by some macroeconomic indicators which have made variable progress in recent years. Based on general economic conditions, economic development has impacted upon economic results of companies. Over time their progress is recorded by economic time series, which describe it. Through the agency of economic time series, economic development and mutual dependences among indicators can be researched. This problem can be solved by applying the methodology which helps describe and quantify relations among quantities. For the purpose of expression of a single time series, stochastic linear modelling is used, and for quantifying the strength of relation among time series, regression analyses and Granger causality testing are used.
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