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Optimization of data communication over high-voltage lines
Minárik, Peter ; Krajsa, Ondřej (referee) ; Mlýnek, Petr (advisor)
The thesis deals with analysis of the PLC (Power Line Communication) system for data communications through powerlines. In the introduction describes the technology of data transmission through the energy network and is divided into categories corresponding with the explanation of the various specifications and features. Different types of coding, affecting the transmitted signal interference and modulation techniques used in a PLC are also described. The practical part is made up of telecommunications network model with transmission channel realized as additive white noise. The model can setup different types of modulation and coding in relate with the signal to noise ratio and bit error rates. The individual blocks settings are described in detail. The model was simulated. The results of simulation are displayed and evaluated at the end of work.
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Laboratory task of the card access system.
Minárik, Peter ; Kyselák, Martin (referee) ; Burda, Karel (advisor)
The Bachelor´s thesis is based on creating laboratory task of the card access system. Principles, technical solutions and primary parts of card access system are described in the first part of the project. The laboratory task is designed in the second part. It’s focused on getting familiar with card access systems, their setup and function.
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Phase transformations in aluminium AlEr(Sc)-based alloys
Leibner, Michal ; Vlach, Martin (advisor) ; Minárik, Peter (referee)
The effects of Sc addition, different Er concentrations and deformation on phase transitions in Al(-Sc)-Er-Zr alloys were studied. Three distinct processes were identified during isochronal annealing in all of the alloys investigated. The first process with maximum at ~ 240 řC is probably related to clustering of Er or to clustering of Er and Sc atoms, respectively. This effect was more pronounced in the deformed alloy due to easier diffusion of solutes along dislocations and (sub)grain boundaries. The second process with a maximum around 360 řC stems from the formation of Al3Er or Al3(Er,Sc) particles, respectively. This effect was more pronounced and led to a more significant hardening in the Sc-containing alloy. The third process is most likely related to the formation of Zr-rich shell around the previously formed precipitates. After aging at 600 řC, precipitates with a core made of Al3Er phase and a shell made of Al3(Er,Zr) phase were observed in the Al-Er-Zr alloy.
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Investigation of deformation mechanisms in textured magnesium alloy by advanced in-situ methods
Dittrich, Jan ; Minárik, Peter (advisor)
Title: Investigation of deformation mechanisms in textured magnesium alloy by advanced in-situ methods Author: Bc. Jan Dittrich Department: Department of Physics of Materials Supervisor: RNDr. Peter Minárik, PhD., Department of Physics of Materials Abstract: This thesis aims to investigate the correlation between texture and the activation of particular deformation mechanisms during the deformation of a rolled magnesium alloy AZ31. A combination of advanced in-situ techniques, providing complementary information about the processes within the material during its deformation, was employed to achieve this goal. The combination of neutron diraction and acoustic emission measurements allowed to investigate both rapid and continuous processes related to changes of the material microstructure resulting from its deformation. The in-situ loading of the sample inside the chamber of a scanning electron microscope, coupled with the electron backscatter diraction analysis, provided more direct observations of the microstructural evolution. Furthermore, the high-speed camera imaging of the deformed sample surface enabled a direct, real-time view of the occurring rapid processes. The results of the experiments conrmed the anisotropy of the mechanical behaviour of samples oriented diversely with respect to the...
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High-temperature oxidation of selected complex concentrated alloys
Jača, Eliška ; Minárik, Peter (advisor) ; Kubásek, Jiří (referee)
The increasing industry demands give rise to a continuous call for materials with an improved combination of mechanical and oxidation properties. Recently developed Complex concentrated alloys - alloys consisting of multiple elements in near-equiatomic ratios - may fulfill these criteria. One of the promising group of these alloys comprises base FeAlCr and other alloying elements such as vanadium, nickel or cobalt. In this study, we focused on the detailed characterization of the microstructure and high-temperature oxidation of FeAlCr-Ni-V alloys with vari- ous content of nickel and vanadium. We have found out that investigated alloys FeAlCrNiV and FeAlCrNi exhibit promising BCC/B2 microstructure, possibly providing a preferable combination of ductility and strength. However, our fin- dings have shown that vanadium, even in a reduced amount, deteriorates oxi- dation resistance of the materials and leads to the formation of complex mul- tilayered oxide scale. Presumably, the formation of V2O5 impairs alumina and chromia scale and limits the formation of more protective scales. Generally, this study also reveals limitations in the characterization of complex oxide scales and presents the complexity of the oxidation process of Complex concentrated alloys.
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Effect of microstructure on mechanisms of plastic deformation in fine-grained magnesium alloys
Minárik, Peter ; Král, Robert (advisor) ; Hadzima, Branislav (referee)
In this work were studied effects of the grain refinement on the mechanical properties and the corrosion resistance of magnesium alloys potential for medical applications - AE21 and AE42. Mechanical properties changed after ECAP pressing in consistency with literature data. Enhanced corrosion resistance in AE42 alloy was achieved by the grain refinement. Corrosion layer created on the surface was observed by light and electron microscopy. Effect of the grain size on the character of the corrosion layer was investigated. AE42 alloy is suitable for further investigation as potential biodegradable material. AE21 alloy was excluded from further investigation due to low corrosion resistance even after ECAP treatment.
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Effect of composition and microstructure on mechanical and corrosion properties in magnesium alloys with a potential for medical applications.
Minárik, Peter ; Král, Robert (advisor) ; Chráska, Pavel (referee) ; Landa, Michal (referee)
Title: Effect of composition and microstructure on mechanical and corrosion properties in magnesium alloys with a potential for medical applications. Author: RNDr. Peter MINÁRIK Department / Institute: Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. Dr. rer. nat. Robert Král, PhD., Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague Abstract: Doctoral thesis is focused on the effect of thermomechanical processing through ECAP on the microstructure, mechanical properties and corrosion properties. The investigation was performed on the extruded magnesium alloys AE21, AE42 and LAE442, because their potential for medical applications. Microstructure development was characterized in detail by scanning electron microscopy together with detection of back scattered electros, transmission electron microscopy and positron annihilation spectroscopy. Development of mechanical properties was investigated by tensile and compression deformation tests and microhardness measurement. Corrosion resistance was investigated by linear polarization method. Fine-grain structure with grain boundaries with high angle misorientation was achieved by the thermomechanical processing. The resulting...
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Effect of substantial grain refinement on microstructure and mechanical properties of precipitation hardenable magnesium alloys.
Hofman, Daniel ; Minárik, Peter (advisor) ; Janeček, Miloš (referee)
Properties of magnesium alloy WE43 and the effect of substantial grain refinement by ECAP were studied. The compressive strength test revealed a significant increase of yield strength after ECAP, resulting in yield strength of over 400 MPa after 8 ECAP passes. The material remained surprisingly ductile in both compression and tension. Thermal stability of the material was investigated via Vickers hardness test. The ultrafine-grained structure shows good thermal stability up to 300 řC, where the precipitates start to dissolve and grain size starts to increase, resulting in sharp fall of hardness. Annealing of the initial state showed best results for 210 řC where the precipitation hardening led to an increase in hardness up to ∼101 HV.
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Investigation of deformation mechanisms in textured magnesium alloy by advanced in-situ methods
Dittrich, Jan ; Minárik, Peter (advisor) ; Janeček, Miloš (referee)
Title: Investigation of deformation mechanisms in textured magnesium alloy by advanced in-situ methods Author: Bc. Jan Dittrich Department: Department of Physics of Materials Supervisor: RNDr. Peter Minárik, PhD., Department of Physics of Materials Abstract: This thesis aims to investigate the correlation between texture and the activation of particular deformation mechanisms during the deformation of a rolled magnesium alloy AZ31. A combination of advanced in-situ techniques, providing complementary information about the processes within the material during its deformation, was employed to achieve this goal. The combination of neutron diraction and acoustic emission measurements allowed to investigate both rapid and continuous processes related to changes of the material microstructure resulting from its deformation. The in-situ loading of the sample inside the chamber of a scanning electron microscope, coupled with the electron backscatter diraction analysis, provided more direct observations of the microstructural evolution. Furthermore, the high-speed camera imaging of the deformed sample surface enabled a direct, real-time view of the occurring rapid processes. The results of the experiments conrmed the anisotropy of the mechanical behaviour of samples oriented diversely with respect to the...
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Effect of microstructure on mechanisms of plastic deformation in fine-grained magnesium alloys
Minárik, Peter
In this work were studied effects of the grain refinement on the mechanical properties and the corrosion resistance of magnesium alloys potential for medical applications - AE21 and AE42. Mechanical properties changed after ECAP pressing in consistency with literature data. Enhanced corrosion resistance in AE42 alloy was achieved by the grain refinement. Corrosion layer created on the surface was observed by light and electron microscopy. Effect of the grain size on the character of the corrosion layer was investigated. AE42 alloy is suitable for further investigation as potential biodegradable material. AE21 alloy was excluded from further investigation due to low corrosion resistance even after ECAP treatment.
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