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3D Scene Reconstruction from Images
Ambrož, Ondřej ; Řezníček, Ivo (referee) ; Španěl, Michal (advisor)
Existing systems of scene reconstruction and theorethical basics necessary for scene reconstruction from images data are described in this work. System of scene reconstruction from video was designed and implemented. Its results were analyzed and possible future work was proposed. OpenCV, ArtToolKit and SIFT libraries which were used in this project are also described.
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Comparison of technological, environmental and economical properties of various binder systems of mould sand mixtures
Ambrož, Ondřej ; Rusín, Karel (referee) ; Cupák, Petr (advisor)
This bachelor thesis is focused on a comparison of technological, environmental and economical properties of various binder systems of mould sand mixtures. The thesis comprises basic overview of the systems used in foundry practice and the individual systems are described properties, advantages, disadvantages and applications. There are mentioned harmful substances which are generated during the preparation of the sand mixture and during casting. Requirements for ecological production castings are a prerequisite for the development of new methods which are environmentally friendly and are also characterized by favorable technological and economic characteristics.
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Influence of solidification conditions on structure and properties of austenitic chrome-nickel steels
Ambrož, Ondřej ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
The thesis deals with the influence of solidification conditions on structure and mechanical properties of austenitic stainless steels. The first part involves the distribution of stainless steels and a basic understanding of the issue of achieving the desired structure and mechanical properties. The second part is focused on austenitic steels and their basic characteristics. This section also describes the experiment and the results achieved. Finally, these results were evaluated and further research steps were recommended.
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Microstructure modifications of Al-Si-coated press-hardened steel 22MnB5 by laser welding
Šebestová, Hana ; Horník, Petr ; Mika, Filip ; Mikmeková, Šárka ; Ambrož, Ondřej ; Mrňa, Libor
Weld microstructure depends on the characteristics of welded materials and parameters of welding technology, especially on the heat input that determines the peak temperature and the cooling rate. When the coated sheets are welded, the effect of the chemical composition of the coating must be also considered even though its thickness is only a few tens of microns. During 22MnB5+AlSi laser welding experiments, the ferrite-stabilizing elements of coating modified the weld metal microstructure. Ferrite appeared in a quenched weld metal. The rapid cooling rate accompanying welding with a focused beam limited the homogenization of the weld metal which resulted in the formation of ferritic bands in the regions rich in Si and especially in Al. On the other hand, a high level of homogenization was reached when welding with the defocused beam. The ferritic islands uniformly distributed in the weld metal were formed at 0.4 wt% and 1.6 wt% of Si and Al, respectively. The doubled heat input reduced the Al content to 0.7 wt% insufficient for the ferrite formation at still relatively high cooling rates. Predicting the distribution of ferrite in the weld metal is challenging due to its dependence on various factors, such as cooling rate and the volume of dissolved coating, which may vary with any modifications made to the welding parameters.
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Automation of metallographic sample cleaning process
Čermák, Jan ; Ambrož, Ondřej ; Jozefovič, Patrik ; Mikmeková, Šárka
Specimen cleaning and drying are critical processes following any metallographic preparation steps. The paper focuses on automation by reason of absence of the process repeatability during manual sample handling. An etchant or electrolyte results in inhomogeneous surface quality because the solution runs off the specimen surface during its removal from the beaker. High-quality specimen cleaning is absolutely crucial for the acquisition of the specimen suitable for characterization by a scanning electron microscope operated at very low landing energies of the primary electrons (SLEEM). The SLEEM technique is a powerful tool for the characterization of advanced steels, as described by many scientific papers. The SLEEM requires the specimen absolutely free of water and any organic residues on the surface. This work presents a novel unique apparatus enabling automatic specimen cleaning and drying after the etching or electropolishing processes. Automation reduces the influence of dependent variables that would be introduced into the process by the metallographer. These variables include cleaning time, kinematics, and motion dynamics, but the process can also be affected by variables that are not obvious. Performed experiments clearly demonstrate our in-house designed apparatus as a useful tool improving efficiency and consistency of the sample cleaning process. The high quality of the specimen surface is verified using a light optical microscope, an electron scanning microscope, and above mentioned SLEEM technique.
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New methods of sample preparation for modern scanning electron microscopy
Ambrož, Ondřej ; Čermák, Jan ; Mikmeková, Šárka
Modern scanning electron microscopes (SEM) are equipped with a very sophisticated detection system that allows the detection of signal electrons by several differently located detectors simultaneously. Signal electrons are filtered according to energy and angle. Effective signal filtering in SEM together with the possibility of using very low impact energies of the primary beam leads to the extreme sensitivity of this method to the quality of the sample surface. Current metallographic methods of sample preparation are becoming insufficient for advanced imaging in modern SEM instruments. Classical sample preparation proves to be completely unsuitable especially for low-voltage scanning electron microscopy. The work will present the first results of the influence of preparation methods on the surface condition and the possibility of differentiating the individual phases of TRIP steel using advanced electron microscopy techniques. The possibilities of new procedures using robotics will be shown.
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Artifacts and errors in EBSD mapping of retained austenite in TRIP steel
Mikmeková, Šárka ; Jozefovič, Patrik ; Ambrož, Ondřej
The present work aims to demonstrate artifacts and errors in visualization of retained austenite phase in TRIP steel by an electron back-scattered diffraction (EBSD) technique. Retained austenite phases size and shape obtained by the EBSD are directly compared with a real image of these phases acquired by means of an atomic force microscopy (AFM). The effect of the step size parameter used for the EBSD analysis on the retained austenite phase fraction and morphology is discussed in detail and quantified. Surface roughness as a barrier for the imaging of fine features situated on a specimen surface is demonstrated.
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Apparatus for automatic chemical etching of metallographic samples
Ambrož, Ondřej ; Čermák, Jan ; Mikmeková, Šárka
The microstructure of steels after mechanical polishing is revealed only by the application of a suitable etchant. To achieve adequate optical or electron microscope images, the specimen surface must be free of any artifacts. Chemical etching can be defined as a controlled corrosion process. The metal of the investigated material passes as cations into the etchant solution during the chemical etching reaction. Chemical etching is usually performed manually either by immersing the sample in the etchant with simultaneous stirring or by swabbing with a lint-free cloth soaked in the etchant. It is also extremely important to debug the process of removing the sample from the bath and subsequent cleaning. It is recommended to wash the sample after removal from the etchant with water (distilled or demineralized) or alcohol (ethanol, methanol, or isopropyl alcohol) and dry it properly (depending on the etchant and the etched material). The main problem with these processes is the human factor, which significantly contributes to the already limited repeatability. All operation steps must be performed by properly trained personnel in the field of occupational safety because hazardous substances are handled. A high manual dexterity is also needed. Training a new employee is a long-term process. Moreover, keeping the exact etching time can be a challenge and one second can decide success. These problems become more serious in the case of using surface sensitive analytical method, such as a low energy scanning electron microscopy, due to the high spatial resolution and extreme surface sensitivity. We have developed an apparatus for automatic etching of metallographic samples of purpose to overcome all above-mentioned difficulties. The apparatus and results of the first experiments will be presented.
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Case report of physiotherapeutic care about patient with diagnosis of radicular syndrome with left L5 irritation
Ambrož, Ondřej ; Vrbová, Martina (advisor) ; Vančurová, Markéta (referee)
Title of bachelors thesis: Case report of physiotherapeutic care about patient with diagnosis of radicular syndrome with left L5 irritation. Objective: Acquisition of theoretical and practical introduction to the herniated lumbar intervertebral disc and possible physiotherapy approaches used in this problem. Special part includes detailed case study of patient with the diagnosis of radicular syndrome with left L5 irritation. Summary: The general part focuses on theoretical knowledge of anatomy, kinesiology and biomechanics of the lumbar spine. Also the degenerative changes of the spine and the possibilities of diagnostic and therapeutic methods. The practical presents case study of patient with a diagnosis of root irritation syndrome L5 left. Keywords: Radicular syndrome, irritable syndrome, intervertebral disc, spine, physiotherapy
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