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Nanoscale AFM and TEM observations of elementary dislocation mechanisms
Veselý, Jozef ; Cieslar, Miroslav (advisor) ; Dlouhý, Antonín (referee) ; Novák, Pavel (referee)
Single crystals of iron with 20, 28 and 40 at. % aluminium were deformed in compression at room temperature. The later two alloys were deformed also at temperatures in the range of yield stress anomaly. Room temperature deformation was carried under the atomic force microscope (AFM) and the evolution of surface was recorded in-situ. Samples deformed at elevated temperatures were investigated by AFM after the deformation. Dislocation structures in deformed samples were then investigated in transmission electron microscope (TEM). Observations of surface (AFM) and bulk (TEM) are compared. Results of both techniques mutually agree and support the interpretation of observed phenomena. Several original analysis methods were developed. Most notably the stereographic reconstruction, which was applied to dislocation structures and carbide particles present in investigated alloys. Model explaining the distribution of carbide particle axes is presented. Powered by TCPDF (www.tcpdf.org)
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Influence of Explosive Hardening on the Structure and Characteristic of Hadfield Steel in Terms of use in the Railway Transport
Havlíček, Petr ; Podrábský, Tomáš (referee) ; Nesvadba,, Petr (referee) ; Schmidtová,, Eva (referee) ; Stránský, Karel (advisor)
The high alloyed austenitic manganese steel, the Hadfield steel, thanks to its good wear resistance of the work surface and maintaining the high toughness of the internal material in the same time, is successfully applied for casted crossings. The crossings are the most dynamic stressed components in the railway turnouts. Thanks to low surface and sub-surface hardness the occurrence of plastic deformation and the progressive wear of the crossing running surfaces can be found since the initial stages of the crossing operational life. One possibility how to increase the surface and the sub-surface hardness and this way improve the dimensional stability and the crossing lifetime as well is to apply the explosive hardening of the crossing running surfaces. The technology mentioned above means the application of the explosives in the imminent nearness to the running surface of the crossing, when the high pressure wave acting within the extremely short period actuates the plastic deformation of the material structure. The work deals with analysis of influence of explosive hardening on the structure and characteristic of Hadfield steel. The explosive hardened samples have the surface and the sub-surface hardness checked and the microscopic analysis and X – ray diffraction is applied, including the TEM analysis as well carried out by the transmission electronic microscope. The characteristics experimental testing including outcomes from assessment of the contact – fatigue load of the explosive hardened Hadfield steel samples are the part of the work as well. As an experiment final part the outcomes of the long –term validation, the surface hardness and wear of the crossing running surfaces of the explosive hardened crossing already installed into the Czech Republic railway track are introduced as well.
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Problems of the complex potentials of the isotropic elasticity
Padělek, Petr ; Druckmüller, Miloslav (referee) ; Profant, Tomáš (advisor)
The presented Bachelor Thesis investigates the problem of the complex potentials in the isotropic elasticity. The objective of the work is acquiring the components of the stress tensor and the displacement vector which describe the elasticity of continum. This problem is primarily solved on the mathematical level by means of the Airy stress function and the Muschelishvili´s complex potentials. The thesis is supplemented with the necessary theory of the elasticity and finally the concrete solution of the edge dislocation in the infinite domain is demonstrated and compared with the results acquired by FEM method.
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The marked word-order in Italian and its Czech translations.
BUZKOVÁ, Aneta
This diploma thesis deals with the marked word order in Italian and its translation into Czech. The work is divided into two parts. In the opening of the first, theoretical one the author applies her mind to the development of the linguistic attitude to the word order. The author focuses on the description of the basic parameters of the Czech and Italian word order with respect to the marked structures. The second, analytical part works with the selected examples of the Italian marked word order and its translation into Czech. The comparative examples of word order in the analytical part are chosen from the spoken corpus, fictional text and the parallel corpus InterCorp. The aim of this thesis is firstly comparing the Italian marked word order to the Czech one and secondly mapping general principles of translations into Czech. Conclusions and recommendations are drawn for translation into Czech.
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Air services in the Czech Republic, their possibilities and efficiency rate when used in emergency situations
SEDLÁK, Milan
The thesis deals with the current state of how air services are used within the Integrated Rescue System (IRS); it analyzes the level of equipment, possibilities of use and deployment of such technologies in emergency situations; and evaluates technical, qualitative and quantitative levels of all means that air services use in emergency situations. The thesis also puts emphasis on the analysis of dislocation of these means, its advantages and suitability when scrutinized in terms of quality, speed and efficiency of their deployment in emergency security situations, rescue operations, or their deployment during natural disasters. The outcome of the thesis comprises of proposals how to comprehensively amend applicable laws; and of conclusions that may help instigate discussion on the observed shortfalls, and how to increase efficiency, economy, and logical scheme leading to a timely response in emergency situations. The empirical part of thesis includes quantitative and qualitative researches which scrutinized two research corpuses. Tackling the first research corpus, the author used questionnaires to collect data technically. The questionnaires were aimed at members of the basic units of the IRS components. The outcomes of the questionnaires are shown in graphs. Tackling the second research corpus, the author held semi-structured interviews with expert representatives of subjects that provide air services within the IRS. Assessment of the outcomes was based on the transcriptions of the interviews which involved inserting the data into tables summarizing the most important outcomes of the research. Subsequently, these outcomes were used to identify the most important theses which were based on the answers provided by the respondents to research questions. The research also included an analysis of the available legal standards and documents related to the use of air services to provide efficient intervention, their assessment and identification of some criteria for de lege ferenda proposals to comprehensively amend selected laws. In conclusion, it was found out that there is poor awareness of possibilities how to use air services among the members of the basic units in individual IRS components, which results in insufficient deployment of Air Services while carrying out interventions.
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