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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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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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Design of experiments for quality optimization
Havlásek, Radim ; Kosina, Petr (referee) ; Novotný, Radovan (advisor)
This thesis is aimed to Design of Experiments methodology. Main purpose of this thesis is to create detailed materials for lessons of Design of Experiments in Quality Control courses. Thesis contains case studies which are applicable for education purposes. Design of Experiments has been applied for solder joints quality evaluation. Solder joints have been modeled in software ANSYS and finite element method has been applied for thermomechanical stress evaluation.
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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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Extremely low cycle fatigue life of non-ferrous alloys
Judas, Jakub ; Kohout, Jan (referee) ; Zapletal, Josef (advisor)
This thesis is focused on fatigue behaviour of aluminium alloy 2024-T351 in low cycle and extremely low cycle fatigue regime. Test specimens were firstly subjected to quasi-static tensile and compression tests to establish basic mechanical properties of the experimental material. Fatigue tests were conducted in strain-control mode, when cyclic plastic response and S-N curves were determined. All of the experiments were conducted at room temperature. Shapes of mechanical hysteresis loops are dependent on the strain amplitude and clearly exhibit cyclic plasticity of the alloy. Cyclic deformation curve was fitted by power regression function and subsequently compared with the tensile test. Experimental data of the S-N curves were fitted by Manson-Coffin and Wöhler-Basquin law. The discrepancy of the fatigue data was observed in the extremely low cycle fatigue regime. Based on this phenomenon, new regression function was used to overcome shortening of fatigue life in the extremely low cycle regime.
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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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Current distribution on linear antennas
Novák, Tomáš ; Bártík, Hynek (referee) ; Nováček, Zdeněk (advisor)
This work will describe current distribution measurement problems along antenna conductor using a probe (coupling loop), which is attached to selective micro-voltmeter, which will indicate signal level (voltage). The signal level will be used for representing the current distribution. Subsequently, measuring workplace issues from generator to antenna conductor, probe and selective micro-voltmeter, will be discussed. Analysis of voltages of this link-up and additional study will be conducted. Other parameters, which complement this situation, will be calculated from the current distribution. A computer program, which calculates these parameters and speeds up the collected data processing, will be used for this process.
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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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