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Basic Mechanism of Fatigue and Combined Fatigue/Creep Damage of Ni-based Superalloys MAR-M 247 and IN 713LC
Horník, Vít ; Kohout, Jan (referee) ; Pantělejev, Libor (referee) ; Kunz, Ludvík (advisor)
The thesis is focused on clarifying fatigue damage mechanisms and fatigue-creep damage mechanisms of MAR-M 247 and IN 713LC polycrystalline Ni-based superalloys. This thesis begins with basic information about nickel-based superalloys and their microstructure, followed by a description of fatigue and creep mechanisms and their mutual interaction. The next part contains experimentally obtained results describing the behavior of MAR-M 247 and IN 713LC superalloys under various sets of conditions. Three testing temperatures - 800, 900 and 950 °C were used for the measurement of fatigue properties under symmetrical loading cycle, because in the temperature range 800 – 950 °C, the mechanism of fatigue crack propagation of both superalloys should change from the originally crystallographic at "lower" temperatures (800 °C) to non-crystallographic at "higher" temperatures (950 °C). In addition the effect of processing technology on fatigue properties was studied on the superalloy IN 713LC. High-frequency cyclic loading (about 120 Hz) with high mean stress at elevated temperatures was applied to induce fatigue-creep interaction. The combined fatigue-creep loading was performed on the IN 713LC superalloy at 800 °C and on the MAR-M 247 superalloy at 900 °C.
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Health expectancy in Europe: analysis of explanatory factors
Horník, Vojtěch ; Hulíková Tesárková, Klára (advisor) ; Kulhánová, Ivana (referee)
Health expectancy in Europe: analysis of explanatory factors Abstract Health expectancies are aggregate measures of morbidity and mortality. This thesis analyzes health expectancies in European countries, especially in relation to factors that explain variation in values of health expectancy. Healthy life years and healthy life expectancy based on self-perceived health are chosen as specific indicators used throughout the analysis. First, trends in these measures are analyzed in the period 2005-2017. Second, healthy life expectancy based on self-perceived health is regressed on gross domestic product (GDP), measures of education, long-term unemployment rate, share of government expenditure on health and a measure of income inequality. Income inequality and education are found to have significant associations with health expectancy. For GDP and health expenditures, results were not conclusive. Unemployment was found to be associated with health expectancy positively, contradictory to expectations. Keywords: health expectancy, healthy life years, self-perceived health, regression, morbidity
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Interaction of Creep and High Cycle Fatigue of IN 713LC Superalloy
Horník, V. ; Šmíd, Miroslav ; Hutař, Pavel ; Kunz, Ludvík ; Hrbáček, K.
The study deals with the interaction of creep and high cycle fatigue of cast polycrystalline nickel-based superalloy IN 713LC at high temperatures. Previous works indicated that creep lifetime of superalloy structures was un-affected or even slightly increased in the cases with superimposed vibrations. The reason for this behaviour was not well described up to now. Therefore, set of fatigue tests was conducted at high mean stresses level to observe this phenomenon. The mean stress was kept constant while the stress amplitudes were selected in order to measure wide range of conditions from pure creep to pure fatigue. Fractographic analysis by scanning electron microscopy (SEM) was done with the aim to identify governing damage mechanisms for particular test conditions as a preliminary evaluation of conducted tests.
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Comparison of mortality trends in Central Europe and Baltic countries from 1970 to the present
Horník, Vojtěch ; Hulíková Tesárková, Klára (advisor) ; Burcin, Boris (referee)
Comparison of mortality trends in Central Europe and Baltic countries from 1970 to the present Abstract The aim of this thesis is to assess the most important mortality trends development in countries of Central Europe and Baltic region between 1970 and 2009. The measures used involve life expectancy at birth and life expectancy at the age of 65; besides of this, the age-specific contributions to life expectancy changes are computed according to the method of R. Pressat. The convergence and divergence tendencies among the analyzed countries and between the two regions are evaluated in this thesis as well. Main findings are, on one hand, that mortality trends are relatively similar within each of the regions. When comparing regions between each other, however, significant differences, mostly in the period between mid-1980s and mid-1990s, arise, they are attributed mostly to the influence of mortality crisis in Baltic region after the Soviet Union dissolution. Even though after 1994 mortality development was favourable in Baltic countries, they did not reach mortality level of Central Europe until 2009. Keywords: mortality, Central Europe, Baltic countries, life expectancy, decomposition, convergence, divergence
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Analysis of the influence of temperature cycles on the elimination of recast layer on materials used in aerospace
Slavíková, Barbora ; Martin,, Grepl (referee) ; Horník, Vít (advisor)
This bachelor thesis is dealing with the analysis of the influence of temperature cycles on the elimination of recast layer on materials used in aerospace. This thesis was created in cooperation with Honeywell Aerospace Company in Olomouc. The aim of this work was to prepare the study about influence of the brazing heat cycle on recast layer removing which was caused by laser cutting process. In first part of this bachelor thesis the unconventional machining methods, materials and related brazing processes used in Honeywell Aerospace Olomouc were described. Second part of the thesis consists of experimental measurement of the recast layer provided on a test specimens including their evaluation and interpretation of the results. The conclusions of this bachelor thesis will be used as future reference for next technological research in Honeywell Aerospace Company in Olomouc.
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Thermomechanical fatigue of austenitic stainless steels
Dobeš, Ondřej ; Petráš, Roman (referee) ; Horník, Vít (advisor)
The aim of this bachelor thesis was to study the influence of termomechanical fatigue with dwells in loading cycles on material response as well as damage mechanism. Austenitic stainless steel Sanicro 25 was subjected to in-phase and out-of-phase thermomechanical fatigue (TMF) loading conditions with different amplitudes of mechanical strain in the temperature range 250 to 700 °C. The mechanism of the damage was investigated by means of scanning electron microscope equipped with focused ion beam (FIB) and electron backscatter diffraction (EBSD). Different mechanisms of the fatigue crack initiation were observed in in-phase and out-of-phase TMF cyclic loading. The effect of the type of loading on the damage mechanism and fatigue life is discussed.
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Problems in the use of information technology in teaching at primary school. Analysis of current situation in Prague 1
Galata, Peter ; Horník, Vlastimil (advisor) ; Sedláčková, Daniela (referee)
The bachelor thesis deals with the topic of the implementation of information and communication technologies (ICT) in primary schools in the Czech Republic. It briefly outlines the historical development of educational aids from the 19th century until the beginning of the 21st century, when the level of ICT development significantly affects the educational process. Specifics of an information society and the impact of ICT on today's world are described as well. Several European and Czech strategic documents connected to the implementation and teaching of ICT in schools are mentioned. A description of the three main aspects of the ICT implementation (required hardware, software and teachers' training) is provided, including a description of problems and risks of the implementation process. The process of the successful implementation of ICT in the school environment and educational process is described on the example of ZS Lupacova, Prague. The analysis of the current situation in primary schools in Prague 1 is provided.
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Computer at home and at school with regard to the risks to the childs personal development
Knapová, Jana ; Krykorková, Hana (advisor) ; Horník, Vlastimil (referee)
This thesis on "Computer at home and at school, having regard to the risks to the child's personality development", discusses how to use computers in school, especially in the education, home and leisure of the child. Work emphasizes the risks resulting from improper use of information and communication technology (especially computers and the Internet) and offers solutions to minimize these risks. The aim is to acquaint the reader with the emerging phenomena due to using computers, such as the already extensive social networking, cyberbullying and "addiction" emerging on the Internet and computer games.
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The use of information technology as a competency of a pupil
Daněk, Petr ; Koťa, Jaroslav (advisor) ; Horník, Vlastimil (referee)
The aim of this Diploma Thesis is a description of pupils' competency to use information technologies. The theoretical part focuses on information and computer literacy and it explores information and communication technologies in the curriculum of the Czech educational system. The research part evaluates data gathered in a questionnaire survey of pupils from the Elementary school in Úvaly. The questionnaire survey searched for the level of pupils' computer literacy. A small extent of the survey doesn't enable a wider generalization to the Czech population of elementary school pupils.
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Alternatives of modern information technologies used in education
Horník, Vlastimil ; Vališová, Alena (referee) ; Koťa, Jaroslav (advisor)
The intent of this thesis is to chart educational technology issues. In the theoretic part I'm engaged in universal questions related to school modemizing, teachertechnique relations and a teacher's role in a leaming process supported by an educational technology. In addition to a traditional educational technology and a literature about it, I'm interested in a modem educational technology used along with computers. Except a summary ofthis technology I'm thinking about its use. In the practical part I worked out a case study that charts the process of selected secondary school modemizing. For this purpose I have chosen a school I'm teaching at. It has provided me to get down more in a process of the school modemizing. Even if this part is intended on one concrete school I suppose that problems which have appeared there are similar as in other schools. An outcome of this thesis is a summary of key issues related to a process of modemizing and an indication of next development in this sector.
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