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Experimental evaluation of aluminothermic welds
Zeman, L. ; Valach, J. ; Zlámal, P. ; Krčmářová, N. ; Koudelková, Veronika ; Zeman, J.
The article presents a study of the mechanical processes occurring during the aluminother-mic reaction using experimental methods (strain gauges, digital image correlation, thermography,scanning electron microscopy, profilometry). The aluminothermic reaction is a highly efficient weldingmethod due to its exothermic behaviour, however, it places considerable demands not only on thewelding technique, but also on the capabilities of the experimental methods used - these limitationsare also discussed in the article. The aluminothermic reaction is associated with the formation of alocalised heat source with a time evolution dictated by the technological procedure, which manifestsitself in heat propagation to the surrounding weld material. The unequal evolution of the temperaturefield is the fundamental cause of the appearance of the heat affected zone or local deformations orsurface curvature, which was the focus of the experimental methods deployed above and the results ofwhich are shown in the article.
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Determination of reference parameters for evaluating the strengthening of degraded sandstone masonry of the Cathedral of St. Vit at Prague Castle
Válek, Jan ; Kozlovcev, Petr ; Fialová, Anna ; Slížková, Zuzana ; Kotková, Kristýna ; Svoboda, Milan ; Koudelková, Veronika
Sandstone materials exposed to weather conditions degrade naturally, consequently consolidation of these materials is often required. The aim of this research was to evaluate the impact of four commercials organosilicate consolidants on degraded sandstones, which were used during the neogothic rebuilding of st. Vithus Cathedral at the turn of the 19th to 20th century. The depth of penetration of consolidants into the sandstone porous system and the impact of consolidants on the physical properties of sandstones, namely on the hydrofobicity, water absorption and evaporation, were evaluated primarily. According to the test results, all four consolidants should be suitable for consolidation of sandstones mentioned above even though the results varied slightly between consolidants. For final chose of appropriate consolidant, it is necessary to consider the properties of the treated sandstoned and the technological conditions of the application given by the manufacturer.
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The GAP in Brno
Koudelková, Veronika ; Bernátek, Tomáš (referee) ; Palaščák, Michal (advisor)
The subject of my work was to fill a selected gap in the heart of Brno with a residential building, to compact the city center and effectively use unmaintained spaces. The solved area is located on Cejl street in the Zábrdovice district, nicknamed the Brno Bronx. With my design, I try to contribute to the attractiveness of the location and the creation of pleasant living in the city center as part of a friendly and creative community. The concept is based on the ideal use of the land and also takes into account the surrounding buildings and normative requirements for their placement, spacing and sun exposure. The resulting design therefore consists of three buildings - two apartment buildings in the courtyard and a street building, which in addition to the vertical communication serves also as a noise and dust filter and with its facade brings into the street a hitherto non-existent green element. In this building there is also a space on the ground floor for the sale of local plants, flowers or vegetables, which residents can grow directly on the plot, in greenhouses in the street building or directly on spacious galleries connecting all 3 designed buildings. The design also takes into account the need for parking spaces for residents, which are located on the ground floor directly below the apartment buildings together with the cellars.
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Micro-mechanical performance of concrete used as recycled raw material in cementitious composite
Hrbek, Vladimír ; Koudelková, Veronika ; Prošek, Z. ; Tesárek, P.
The reduction of industrial pollution is recently one of main goals over all fields. In civil engineering, re-cycling of structural waste provides wide opportunity contributing this effort. This paper focus on re-use of concrete waste, which after further processing can be used in new constructions as partial supplement to the mixture. To investigate the impact of re-cycled concrete addition, it is necessary to determine mechanical and structural parameters of individual phases in the “raw” material. For this purpose, grid indentation and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM, EDX) are combined to determine properties of concrete sample.
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Utilization of image and signal processing techniques for assessment of built heritage condition
Koudelka_ml., Petr ; Koudelková, Veronika ; Doktor, Tomáš ; Kumpová, Ivana ; Kytýř, Daniel ; Valach, Jaroslav
Historical buildings represent invaluable heritage from the past and therefore their protection is a very important task. Assessment of their condition must not cause damage accumulation thus the least possible volume removed from the structure is essential. As many historical buildings in the Czech Republic are built using sandstone that can be considered as a typical heterogeneous system, statistical signal processing is a promising approach for determination of the representative volume element (RVE) dimensions. Such calculations can be carried out on the domain of logical arrays representing binary images of the materials microstructure. This paper deals with processing of image data obtained using SEM-BSE and high resolution flatbed scanner for determination of RVE dimensions. Advanced image processing techniques are employed and results from calculation using grayscale data are presented and compared with results calculated on the basis of color input images.
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