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Fatigue characteristics of Metal Matrix Composites (MMC)
Judas, Jakub ; Věchet, Stanislav (referee) ; Zapletal, Josef (advisor)
This bachelor thesis is focused on analysis of fatigue characteristics of hybrid composite based on magnesium matrix QE22 reinforced with Al2O3 fibres and SiC particles. Test specimens of the composite material prepared by infiltration method were subjected to quasi-static tensile and compression test and discovered data were afterwards compared with the magnesium matrix. Cyclic response and low-cycle fatigue life were studied on the material under stress-control mode. All of the experiments were conducted at room temperature. Cyclic curves were fit with regression analysis in order to measure fatigue parameters of the hybrid composite. Cyclic and fatigue parameters were discussed and compared to similar magnesium alloy AZ91 reinforced with SiC particles.
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Low Cycle and High Cycle Fatigue Properties of Austempered Ductile Iron
Zapletal, Josef ; Bokůvka, Otakar (referee) ; Kunz, Ludvík (referee) ; Věchet, Stanislav (advisor)
The thesis is focused on assessment of fatigue behaviour of austempered ductile iron with nodular graphite. Optimal period of transformation was determined based on the best combination of stress and strain characteristics established by tensile test. Cyclic response and low-cycle fatigue life were studied under both stress-control and longitudinal strain-control mode at room temperature. For both modes, shapes of cyclic hardening curves are dependent on stress amplitude. Cyclic deformation curves (CDC) were fitted by power regression function. Results were compared with CDC established by multiple step test in both modes with verification of the influence of cyclic creep (high stress levels, stress-control mode). Experimental data of S-N curves are in agreement with the Manson-Coffin and the Basquin law. Fatigue and cyclic parameters were compared. Fatigue life time in high-cycle fatigue region was determined. Experimental data were fitted by suitable regression functions. Regression parameters and fatigue limit were established by means of each regression function. Experimental data in low- and high-cycle fatigue regions were used to construct S-N curve and to determine relevant parameters. Discontinuity of experimental data was not observed. Low-cycle fatigue behaviour was predicted. Approximation of tolerance bands was realized in high-cycle and both high and low cycle fatigue regions.
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Analysis of Some Indicators of the Company VÚEZ, a.s. Using Time Series
Vicenová, Ivana ; Kubica, Ing, Juraj (referee) ; Kropáč, Jiří (advisor)
The content of this bachelor’s thesis is the analysis of some selected indicators of company VÚEZ Inc. using time series. In the first theoretical part, there is prepared theoretical base for the calculation and the use of regressive analysis and time series. The second, practical part, is focused on the introducing the company, analysis of the specific indicators using time series and the assessment of them. There is also prognosticated another trend of indicators and suggestions to follow or change the trend of selected indicators.
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Assessing Economic Situation of a Company and Proposals for Its Improvement
Machová, Hana ; MSc,, Miroslav Hladký, (referee) ; Doubravský, Karel (advisor)
The diploma thesis is focused on the evaluation of the economic situation of the selected company. The theoretical part describes the issues of financial and statistical analysis. Financial analysis indicators, time series analysis, regression and correlation analysis are described. In the analytical part, a financial and thereafter statistical analysis is performed using selected methods to determine the current situation and expected progression of indicators in the following years. Based on the identified problematical areas, possible suggestions for improving the current situation are describes in the proposal part.
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Assessing Selected Indicators Using Time Series Analysis
Turisová, Alena ; Novotná, Veronika (referee) ; Doubravský, Karel (advisor)
Master's thesis deals with the assessment of selected financial indicators of the production company X in order to evaluate its performance and financial situation. Based on the results of the analyzes for the period 2008 to 2015 and the application of statistical methods of time series analysis and regression analysis, prognosis of future development of monitored indicators are obtained. Subsequently, the prognosis are used for the final formulating of proposals to improve future business efficiency of the company.
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Assessment of Selected Indicators of an International Company Using Statistical Methods
Zouharová, Daniela ; Špačková,, Romana (referee) ; Doubravský, Karel (advisor)
The thesis deals with the assessment of the economic situation of a selected company using statistical methods. The theoretical part describes the financial indicators, time series and regression analysis. The analytical part contains the calculation of selected indicators, which are subjected to statistical analysis. Based on the statistical analysis, the future development of indicators in the next two years is predicted. The last part contains suggestions that can lead to the improvement of the current situation of the company.
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Assessment Of Economic Indicators of the Company Vinařství U Kapličky s.r.o. Using Time Series
Šešulka, Michael ; Novotná, Veronika (referee) ; Doubravský, Karel (advisor)
The bachelor´s thesis is focused on the assessment of selected economic indicators of the company Vinařství U Kapličky s.r.o. using time series. The theoretical part includes the issue of time-series, regression function and description of selected economic indicators. In the practical part of the thesis is directed to the real use of the information obtained from the theoretical part, using time series are the results of the regression function indicators aligned and subsequently predicted their development in the future. The final part is devoted to the evaluation of the results and based on them are provided with appropriate proposals improve the current economic and financial situation of the company.
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Extremely low cycle fatigue life of magnesium alloy
Novák, Marek ; Věchet, Stanislav (referee) ; Zapletal, Josef (advisor)
The goal of this bachelor´s thesis is to predict the fatigue life of magnesium alloy AZ61 in the very low cycle count range (less than 100), which also called extremely low fatigue (ELCF) range. Life prediction predicted by Manson-Coffin´s law is higher than the experimental values show. The main problem is that the slope of the real life curve in the ELCF range is different than the slope of the predicted one. A new regression function with additional material parameters has to be found to match the experimentally measured values. The thesis deals with the literature search of the ELCF range and models of fatigue life prediction in the said range. Furthermore, in the experimental part of the thesis, magnesium alloy AZ61 without any heat treatment has been measured for mechanical and fatigue properties. Also, the microstructure of the alloy was observed. Measured values of fatigue life in the ELCF and LCF range were fitted by a regression function proposed by L. Xue.
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Assessment of Selected Indicators of a Company Using Statistical Methods
Shalaginova, Daria ; Novotná, Veronika (referee) ; Doubravský, Karel (advisor)
Master’s thesis is aimed at assessing the selected financial indicators of the company using statistical methods. Based on the results, the current situation of the company is evaluated. The thesis consists of three parts. The first part contains the necessary theoretical bases for processing the analytical part. The second part is devoted to the analysis of selected indicators, which are then applied statistical methods to the prediction of the future development of these indicators and findings, here between these indicators there is a dependence. At the end of this part, there is an evaluation of the analyzed indicators. The third part presents appropriate proposals for solutions to existing problems caused by indicators that deviate from the recommended values.
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