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Optimization of concrete structures using stochastic optimization methods
Slowik, Ondřej ; Pukl,, Radomír (referee) ; Novák, Drahomír (advisor)
The thesis focuses the reader on the sense of optimization and its importance for civil engineering. It outlines the principles used by some optimization methods and discusses the possibility of combination of any type of methods LHS with other optimization method. The result is a new type of optimization method named Nested LHS described in the text of the third chapter. The fifth chapter applies some of the lessons learned to solve practical optimization problem - reinforced concrete bridge solved by nonlinear finite element analysis using pseudostochastic optimization method LHS mean.
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An efficiency comparison of simulation methods for artificial neural network training and inverse analysis
Nezval, Michal ; Novák, Drahomír (referee) ; Lehký, David (advisor)
The thesis deals with inverse analysis which is based on combination of artificial neural network and stochastic methods. The goal is to compare an efficiency of new simulation method Hierarchical Subset Latin Hypercube Sampling to classical Monte Carlo method and standard Latin Hypercube Sampling method used for neural network training. The efficiency is compared for a different neural network structures. The inverse analysis is then applied for engineering tasks – identification of limit state fiction parameters related to pitched-roof frame and material parameters of concrete specimen subjected to three-point bending. Finally an efficiency of Hierarchical Subset Latin Hypercube method comparing to Monte Carlo and Latin Hypercube Sampling methods is discussed.
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Reliability-based structural optimization
Slowik, Ondřej ; Pukl, Radomír (referee) ; Novák, Drahomír (advisor)
This thesis presents the reader the importance of optimization and probabilistic assessment of structures for civil engineering problems. Chapter 2 further investigates the combination between previously proposed optimization techniques and probabilistic assessment in the form of optimization constraints. Academic software has been developed for the purposes of demonstrating the effectiveness of the suggested methods and their statistical testing. 3th chapter summarizes the results of testing previously described optimization method (called Aimed Multilevel Sampling), including a comparison with other optimization techniques. In the final part of the thesis, described procedures have been demonstrated on the selected optimization and reliability problems. The methods described in text represents engineering approach to optimization problems and aims to introduce a simple and transparent optimization algorithm, which could serve to the practical engineering purposes.
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The probabilistic solution of dike breaching due to overtopping
Alhasan, Zakaraya ; Fošumpaur, Pavel (referee) ; Šoltész,, Andrej (referee) ; Říha, Jaromír (advisor)
Doctoral thesis deals with reliability analysis of flood protection dikes by estimating the probability of dike failure. This study based on theoretical knowledge, experimental and statistical researches, mathematical models and field survey extends present knowledge concerning with reliability analysis of dikes vulnerable to the problem of breaching due to overtopping. This study contains the results of probabilistic solution of breaching of a left bank dike of the River Dyje at a location adjacent to the village of Ladná near the town of Břeclav in the Czech Republic. Within thin work, a mathematical model describing the overtopping and erosion processes was proposed. The dike overtopping is simulated using simple surface hydraulics equations. For modelling the dike erosion which commences with the exceedance of erosion resistance of the dike surface, simple transport equations were used with erosion parameters calibrated depending on data from past real embankment failures. In the context of analysis of the model, uncertainty in input parameters was determined and subsequently the sensitivity analysis was carried out using the screening method. In order to achieve the probabilistic solution, selected input parameters were considered random variables with different probability distributions. For generating the sets of random values for the selected input variables, the Latin Hypercube Sampling (LHS) method was used. Concerning with the process of dike breaching due to overtopping, four typical phases were distinguished. The final results of this study take the form of probabilities for those typical dike breach phases.
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Reliability-based structural optimization
Slowik, Ondřej ; Červenka,, Jan (referee) ; Lepš, Matěj (referee) ; Novák, Drahomír (advisor)
Presented PhD thesis deals with reliability-based optimization of structures and problems related to automatization of various algorithms of solution for various reliability-based optimization task definitions. The text presents a general definition of the reliability-based optimization problem, followed by a description of state of the art within the broad field of reliability-based optimization as well as the current state of the art of selected methodology utilized or developed by the author during his work in order to meet objectives of his dissertation. The theoretical part of the thesis is supplemented by a description of developed software tools and by examples of described methodology applications during a solution of practical problems of nonlinear numerical models reliability-based optimization and problems of inverse analysis.
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The probabilistic solution of dike breaching due to overtopping
Alhasan, Zakaraya ; Fošumpaur, Pavel (referee) ; Šoltész,, Andrej (referee) ; Říha, Jaromír (advisor)
Doctoral thesis deals with reliability analysis of flood protection dikes by estimating the probability of dike failure. This study based on theoretical knowledge, experimental and statistical researches, mathematical models and field survey extends present knowledge concerning with reliability analysis of dikes vulnerable to the problem of breaching due to overtopping. This study contains the results of probabilistic solution of breaching of a left bank dike of the River Dyje at a location adjacent to the village of Ladná near the town of Břeclav in the Czech Republic. Within thin work, a mathematical model describing the overtopping and erosion processes was proposed. The dike overtopping is simulated using simple surface hydraulics equations. For modelling the dike erosion which commences with the exceedance of erosion resistance of the dike surface, simple transport equations were used with erosion parameters calibrated depending on data from past real embankment failures. In the context of analysis of the model, uncertainty in input parameters was determined and subsequently the sensitivity analysis was carried out using the screening method. In order to achieve the probabilistic solution, selected input parameters were considered random variables with different probability distributions. For generating the sets of random values for the selected input variables, the Latin Hypercube Sampling (LHS) method was used. Concerning with the process of dike breaching due to overtopping, four typical phases were distinguished. The final results of this study take the form of probabilities for those typical dike breach phases.
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Optimization of concrete structures using stochastic optimization methods
Slowik, Ondřej ; Pukl,, Radomír (referee) ; Novák, Drahomír (advisor)
The thesis focuses the reader on the sense of optimization and its importance for civil engineering. It outlines the principles used by some optimization methods and discusses the possibility of combination of any type of methods LHS with other optimization method. The result is a new type of optimization method named Nested LHS described in the text of the third chapter. The fifth chapter applies some of the lessons learned to solve practical optimization problem - reinforced concrete bridge solved by nonlinear finite element analysis using pseudostochastic optimization method LHS mean.
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|
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Reliability-based structural optimization
Slowik, Ondřej ; Pukl, Radomír (referee) ; Novák, Drahomír (advisor)
This thesis presents the reader the importance of optimization and probabilistic assessment of structures for civil engineering problems. Chapter 2 further investigates the combination between previously proposed optimization techniques and probabilistic assessment in the form of optimization constraints. Academic software has been developed for the purposes of demonstrating the effectiveness of the suggested methods and their statistical testing. 3th chapter summarizes the results of testing previously described optimization method (called Aimed Multilevel Sampling), including a comparison with other optimization techniques. In the final part of the thesis, described procedures have been demonstrated on the selected optimization and reliability problems. The methods described in text represents engineering approach to optimization problems and aims to introduce a simple and transparent optimization algorithm, which could serve to the practical engineering purposes.
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