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Statistical analysis of samples from the generalized exponential distribution
Votavová, Helena ; Popela, Pavel (referee) ; Michálek, Jaroslav (advisor)
Diplomová práce se zabývá zobecněným exponenciálním rozdělením jako alternativou k Weibullovu a log-normálnímu rozdělení. Jsou popsány základní charakteristiky tohoto rozdělení a metody odhadu parametrů. Samostatná kapitola je věnována testům dobré shody. Druhá část práce se zabývá cenzorovanými výběry. Jsou uvedeny ukázkové příklady pro exponenciální rozdělení. Dále je studován případ cenzorování typu I zleva, který dosud nebyl publikován. Pro tento speciální případ jsou provedeny simulace s podrobným popisem vlastností a chování. Dále je pro toto rozdělení odvozen EM algoritmus a jeho efektivita je porovnána s metodou maximální věrohodnosti. Vypracovaná teorie je aplikována pro analýzu environmentálních dat.
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Determination of thermophysical properties of scale layer on steel at high temperatures
Ondruch, Tomáš ; Votavová, Helena (referee) ; Pohanka, Michal (advisor)
The thesis deals with thermophysical properties of scale layer on steel and their determination at high temperatures. The first part summarizes fundamental characteristics of scales, it is also devoted to principles of heat transfer with emphasis on heat conduction. The following text presents current state of research on scales’ thermophysical properties. Subsequently, the thesis aims to experimental measurement of thermophysical properties by use of laser flash method and conducted measurement is described, as well. The following chapters present a finite-element numerical model of the measurement aparatus and computation technique for determination of scales’ thermophysical properties is explained. The obtained results are compared with available data and sensitivity analysis of selected model parameters is carried out.
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Development of New Approaches in Descaling in the Continuous Production of Steel using High-Pressure Water Jet
Votavová, Helena ; Hloch,, Sergej (referee) ; Čecho, Ladislav (referee) ; Pohanka, Michal (advisor)
The thesis summarizes general and up-to-date knowledge of descaling during the continuous production of the hot-rolled steel and proposes further streamlining of this process in industrial production. The first chapter of the thesis deals with the origin, structure and physical properties of the scales. The second chapter describes the principles of descaling by using a high pressure flat water jet. The third chapter introduces the principles of the experimental methods and describes the used laboratory equipment. The fourth chapter summarizes the description of the particular experiments and their evaluation, and thus represents the focus of the dissertation. It is divided into six sections which independently solve predefined objectives of the dissertation. The first section focuses on the height and structure development of the scales on 54SiCr6 and HDT580X steels. It has been proven that the height of the formed scales increases with the time and temperature of the oxidation. The layered nature of the scales was verified at the same time. The second section examines the effect of the nozzle stabilizer on the focussing and distribution of the impact pressure of the nozzle. Experiments have shown that increase of 11 % of an average maximum nozzle pressure can be achieved, depending on the type of nozzle and the length of the stabilizer. The third section deals with the analysis of shadowgraphy images of water jet structures of the nozzles. A script was developed for analysis of these shadowgraphy photos by an adaptive thresholding. The findings are correlated using a regression analysis with an average heat transfer coefficient. It has been reported that most of the standard nozzle configurations produced disintegrated stream of little droplets at the height of the rolled surface. The fourth section focuses on the area of water jet overlap, especially the area of the so-called washout, where the impact pressure of one nozzle is reduced by the nozzle stream of the other. The influence of the pressure change and the mutual displacement of the nozzles is investigated. The analysis showed that the change of pressure did not have any effect on the percentage of reduction of the impact pressure in the area of the washout. It has been shown that if the area of the washout is wide the descaling efficiency in this area may be reduced. The fifth section builds on the previous section and focuses directly on the areas of waterjet overlaps. The influence of the change of rotation and pitch of the nozzles is studied. Experiments have shown that small changes in nozzle pitch do not have a significant impact on impact pressure and heat transfer coefficient. The effect of nozzle rotation, on the other hand, was a significant factor for the efficiency and homogeneity of the descaling of the surface. The last section deals with the effect of the rolling speed on the heat transfer coefficient in the descaling process. The regression model has shown that with a higher rolling speed there is a reduction in the average heat transfer coefficient. Conclusion summarizes the results of the dissertation and proposes which findings can be used in the industry to make the descaling process more effective.
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Mathematical models for transportation problems
Votavová, Helena ; Novotný, Jan (referee) ; Popela, Pavel (advisor)
The thesis deals with modelling and solution techniques for the selected transportation problems. Firstly, historical remarks and application-related comments are introduced. Then the selected transportation problems are defined and mathematical programming and graph theory concepts are utilised to model them. The travelling salesman problem and suitable algorithms are under focus. The original implementation in GAMS and Python is discussed. Algorithms have been tested for the instance based on the set of 73 towns in the Czech Republic. Finally, the test results are evaluated and compared.
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Statistical Models of Success of Various Techniques of Rugby Kicking
Vrbacká, Kateřina ; Votavová, Helena (referee) ; Bednář, Josef (advisor)
This bachelor thesis is dealing with the testing of statistical hypothesis and their practical use. We model the success of rugby kicking and analyze the dominant factors (ball position, kicking technique, player) and their interactions. We will use some mathematical terms such as chi-square test of independence and logistic regression. The final model will be processed by software MINITAB. The outcome from this thesis will be the exact description of this situation.
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Gene expression analysis in patients with myelodysplastic syndrome
Vašíková, Alžběta ; Votavová, Hana (advisor) ; Neuwirtová, Radana (referee) ; Jarošová, Marie (referee)
Myelodysplastic syndrome (MDS) is a clonal disorder affecting maturation and differentiation of hematopoietic stem cells. MDS is characterized by ineffective hematopoiesis resulting in peripheral blood cytopenia in at least one lineage, and increased risk of development of acute myeloid leukemia (AML). This disorder mostly affects the elderly, with the incidence of 10-50/100000 people per year. Heterogeneity of MDS is further underlined by the presence of both idiopathic primary and secondary therapy-related forms, which arise from accumulation of mutational events induced by cytotoxic therapy (exposure to alkylating agents or after therapy with topoisomerase II inhibitors). In this thesis, we focused on determination of differential gene expression between MDS patients and control subjects using different microarray platforms. Using nylon membranes, we detected 4 genes (ERCC1, FLT1, NME4, PCNA) with increasing expression pattern in advanced MDS stages, which correlated with disease progression. Their strong up- regulation was also observed in patients with de novo AML, suggesting their involvement in the leukemic transformation of MDS. Comparison of gene expression profiles of early and advanced MDS obtained by Agilent microarrays resulted in the set of differentially expressed genes, which might...
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Distinguishing of primary mediastinal B-cell lymphoma and diffuse large B-cell lymphoma with real-time quantitative polymerase chain reaction
Votavová, Hana ; Trněný, Marek (advisor) ; Papajik, Tomáš (referee) ; Kozák, Tomáš (referee)
Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. It is a molecular and prognostic heterogeneous disease. Three main genetic subtypes are called germinal center-like DLBCL (GC-like DLBCL), non-germinal center-like DLBCL (nonGC-like DLBCL) and primary mediastinal B-cell lymphoma (PMBL). These subtypes can be reliably distinguished only with usage of gene expression profiling (GEP). The GEP method can be applied only when fresh frozen tissue is available. The method is technically difficult and expensive. Thus, it is not used routinely. Since the DLBCL subtypes differ in prognosis, it is extremely important to be able to distinguish them. The presented thesis is focused on distinguishing of PMBL diagnosis in the group of DLBCL. Easily stored formalin-fixed, paraffin-embedded tissue (FFPE) and gene expression analysis using real-time quantitative polymerase chain reaction (RTqPCR) are used. In the first step, PMBL and DLBCL cases were distinguished with an internationally accepted clinical-pathological method. The agreement between clinical-pathological diagnosis and GEP is only 76%. In the presented text a genetic algorithm for PMBL/DLBCL distinguishing is suggested. It uses three carefully chosen genes and their expression is measured with RTqPCR. Both, the...
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Development of New Approaches in Descaling in the Continuous Production of Steel using High-Pressure Water Jet
Votavová, Helena ; Hloch,, Sergej (referee) ; Čecho, Ladislav (referee) ; Pohanka, Michal (advisor)
The thesis summarizes general and up-to-date knowledge of descaling during the continuous production of the hot-rolled steel and proposes further streamlining of this process in industrial production. The first chapter of the thesis deals with the origin, structure and physical properties of the scales. The second chapter describes the principles of descaling by using a high pressure flat water jet. The third chapter introduces the principles of the experimental methods and describes the used laboratory equipment. The fourth chapter summarizes the description of the particular experiments and their evaluation, and thus represents the focus of the dissertation. It is divided into six sections which independently solve predefined objectives of the dissertation. The first section focuses on the height and structure development of the scales on 54SiCr6 and HDT580X steels. It has been proven that the height of the formed scales increases with the time and temperature of the oxidation. The layered nature of the scales was verified at the same time. The second section examines the effect of the nozzle stabilizer on the focussing and distribution of the impact pressure of the nozzle. Experiments have shown that increase of 11 % of an average maximum nozzle pressure can be achieved, depending on the type of nozzle and the length of the stabilizer. The third section deals with the analysis of shadowgraphy images of water jet structures of the nozzles. A script was developed for analysis of these shadowgraphy photos by an adaptive thresholding. The findings are correlated using a regression analysis with an average heat transfer coefficient. It has been reported that most of the standard nozzle configurations produced disintegrated stream of little droplets at the height of the rolled surface. The fourth section focuses on the area of water jet overlap, especially the area of the so-called washout, where the impact pressure of one nozzle is reduced by the nozzle stream of the other. The influence of the pressure change and the mutual displacement of the nozzles is investigated. The analysis showed that the change of pressure did not have any effect on the percentage of reduction of the impact pressure in the area of the washout. It has been shown that if the area of the washout is wide the descaling efficiency in this area may be reduced. The fifth section builds on the previous section and focuses directly on the areas of waterjet overlaps. The influence of the change of rotation and pitch of the nozzles is studied. Experiments have shown that small changes in nozzle pitch do not have a significant impact on impact pressure and heat transfer coefficient. The effect of nozzle rotation, on the other hand, was a significant factor for the efficiency and homogeneity of the descaling of the surface. The last section deals with the effect of the rolling speed on the heat transfer coefficient in the descaling process. The regression model has shown that with a higher rolling speed there is a reduction in the average heat transfer coefficient. Conclusion summarizes the results of the dissertation and proposes which findings can be used in the industry to make the descaling process more effective.
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Determination of thermophysical properties of scale layer on steel at high temperatures
Ondruch, Tomáš ; Votavová, Helena (referee) ; Pohanka, Michal (advisor)
The thesis deals with thermophysical properties of scale layer on steel and their determination at high temperatures. The first part summarizes fundamental characteristics of scales, it is also devoted to principles of heat transfer with emphasis on heat conduction. The following text presents current state of research on scales’ thermophysical properties. Subsequently, the thesis aims to experimental measurement of thermophysical properties by use of laser flash method and conducted measurement is described, as well. The following chapters present a finite-element numerical model of the measurement aparatus and computation technique for determination of scales’ thermophysical properties is explained. The obtained results are compared with available data and sensitivity analysis of selected model parameters is carried out.
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