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Proposition of new type of injection material with electrically conductive function
Uher, Vojtěch ; Černý, Vít (referee) ; Drochytka, Rostislav (advisor)
The bachelor thesis deals with the design of a new type of grouting material with electrically conductive function suitable for connecting cracks and gaps in building protection systems against lightning strikes and surges. The theoretical part summarizes the important knowledge about the grouting and grouting materials, introduces the current state of knowledge in the field of lightning and surge protection of buildings and also the preconditions of electrical conductivity of cement-based composite materials. In the practical part are summarized selected properties, which the electrically conductive grouting material should have and the relevant standards tests for experimental verification of selected properties are described. A wide range of primary and secondary fillers are studied and the most suitable ones are chosen to achieve a low electrical resistivity value. At the end of the thesis, there are recipes based on amassed knowledge and using secondary fillers to reduce the environmental impact of the developed materials during mass production. Reduced resistivity has been demonstrated in recipes using waste carbon and chopped carbon fibers, but has failed to fully meet standard requirements. The result of the work are new recipes and knowledge that can serve as a basis for further research.
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Study of the influence of structure on the resistivity of silicate composites
Uher, Vojtěch ; Šteffan,, Pavel (referee) ; Drochytka, Rostislav (advisor)
Electroconductive silicate-based composites are advanced materials that allow building structures to perform several different functions simultaneously. Addressing the issues of their development and use is a suitable topic for research work. The aim of this work is to study the effect of structure on the resistivity of silicate composite. The structure of electrically conductive composites is studied on dry cement paste and mortar mixtures as well as on test bodies made of hardened cement paste and mortar after 28 days of curing. Based on the analysis of the raw materials, six suitable electroconductive fillers are selected based on particle size, resistivity, and water absorption. The parameters of dry cement paste and hardened cement paste with replacement of 4-19 wt. % cement by the selected fillers are determined. Two of the fillers are selected for use in dry and hardened mortar. Resistivity is determined for all dry mixes and hardened composites variants, and percolation thresholds are approximately determined. By studying the structure of the selected variants, it is shown that the most important parameters that have the greatest influence on the resistivity of the silicate composites are mainly the particle size and the intrinsic resistivity of the electrically conductive filler. For silicate composites in the hardened state, the volume of hydration products, especially portlandite and C-S-H gels, also has a significant influence. For both dry blends and hardened composites, it was found that the smaller the particle size of the electroconductive filler, the smaller the representation needed to reach the percolation threshold. Portlandite and C-S-H gels in the volume of the hardened composite cause its high resistivity. The resistivity of the hardened composite is always higher than that of the dry blends. Thus, the proportion of electroconductive filler needed to reach the percolation threshold is higher in hardened composites than in dry mixes. The resist
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Study of possibilities of activation of power plant fly ash as an active ingredient in concrete
Máša, Jiří ; Uher, Vojtěch (referee) ; Hela, Rudolf (advisor)
Global concrete production is increasing, which brings some environmental burden. A certain solution is the use of secondary raw materials, which has been a long-standing practice in the construction industry. One of the most widespread secondary raw materials is power fly ash. However, in recent years trends have been directed towards maximizing their utility properties. The aim of this work was to study the possibilities of activation of power plant fly ash as an active admixture in concrete. The thesis is divided into two parts, the theoretical and the practical part. The theoretical part describes in detail the possibilities of power plant fly ash activation for use as an active admixture in concrete. The practical part of the thesis is focused on mechanical activation, where the knowledge of the theoretical part is verified on various fly ash.
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Using smart watches and their functions to measure health parameters
Uher, Vojtěch ; Křivánková, Markéta (advisor) ; Mahrová, Andrea (referee)
Title: Utilization and preferences of smartwatches and their features for measuring health parameters in the adult population Objectives: The aim of this master's thesis is to analyze the utilization and preferences of smartwatches in the adult population and to examine their potential for measuring health parameters through a questionnaire survey. Methods: The research was conducted through a questionnaire survey. A questionnaire of our own design was utilized. The research section also included an analysis of parameters and functions of smartwatches. Results: The average age of the respondents who filled out the questionnaire for this diploma thesis was 31.2 years. 63 out of 103 probands use smartwatches to monitor their health status, with the most frequently measured parameter being heart rate. All 63 respondents follow here. The most used function associated with physical activity is tracking the number of steps. 91 respondents are interested in this data. Factors such as quality, accuracy, and design play a key role when choosing a smartwatch. According to the respondents, the most used smartwatches are from Apple and Garmin. Apple Watch is used by 42% of probands and the Garmin brand by 26% of probands. Respondents often prefer the Apple brand for its compatibility with other devices, and...
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Development of concrete recipes with recycled brick aggregates as partial or complete substitutes for natural aggregatesDevelopment of concrete recipe
Pijáčková, Erika ; Uher, Vojtěch (referee) ; Hela, Rudolf (advisor)
The master thesis is focused on the issue of using recycled brick aggregate in structural concrete. The theoretical part summarizes knowledge of the properties of recycled bricks, their preparation and production, and legislative restrictions for their use in structural concrete. The properties and utilization of concrete with recycled brick aggregate are also described. In the experimental part, the properties of recycled bricks are investigated considering to their use in concrete, and based on the results of these properties, recipes for concrete with brick recycles and reference concretes are proposed. The aim of the experimental part was to verify the resulting properties of concrete and their use for construction purposes. Furthermore, as part of the experimental part of the work, an economic balance sheet was made to compare the prices of reference concrete and concrete with recycled brick aggregates.
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Study of the influence of structure on the resistivity of silicate composites
Uher, Vojtěch ; Šteffan,, Pavel (referee) ; Drochytka, Rostislav (advisor)
Electroconductive silicate-based composites are advanced materials that allow building structures to perform several different functions simultaneously. Addressing the issues of their development and use is a suitable topic for research work. The aim of this work is to study the effect of structure on the resistivity of silicate composite. The structure of electrically conductive composites is studied on dry cement paste and mortar mixtures as well as on test bodies made of hardened cement paste and mortar after 28 days of curing. Based on the analysis of the raw materials, six suitable electroconductive fillers are selected based on particle size, resistivity, and water absorption. The parameters of dry cement paste and hardened cement paste with replacement of 4-19 wt. % cement by the selected fillers are determined. Two of the fillers are selected for use in dry and hardened mortar. Resistivity is determined for all dry mixes and hardened composites variants, and percolation thresholds are approximately determined. By studying the structure of the selected variants, it is shown that the most important parameters that have the greatest influence on the resistivity of the silicate composites are mainly the particle size and the intrinsic resistivity of the electrically conductive filler. For silicate composites in the hardened state, the volume of hydration products, especially portlandite and C-S-H gels, also has a significant influence. For both dry blends and hardened composites, it was found that the smaller the particle size of the electroconductive filler, the smaller the representation needed to reach the percolation threshold. Portlandite and C-S-H gels in the volume of the hardened composite cause its high resistivity. The resistivity of the hardened composite is always higher than that of the dry blends. Thus, the proportion of electroconductive filler needed to reach the percolation threshold is higher in hardened composites than in dry mixes. The resist
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Overview of knowledge of children in primary and secondary school about the integrated rescue system
Uher, Vojtěch ; Fiala, Miloš (advisor) ; Vilášek, Josef (referee)
Title: Overview of knowledge of children in primary and secondary school about the integrated rescue system. Objectives: The aim of this bachelor thesis is to find out what knowledge students in primary and secondary school have about the integrated rescue system. Furthermore, to compare individual answers of students between the two schools. Methods: For this research, an electronic questionnaire was created on the survio.com website. Results: Pupils from both schools have a great overview of the integrated rescue system. The high school students answered flawlessly, with some exceptions. All results are recorded in the work in the form of graphs. Keywords: integrated rescue system, Police of the Czech Republic, Medical Rescue Service, Fire Rescue Corps
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Study of possibilities of activation of power plant fly ash as an active ingredient in concrete
Máša, Jiří ; Uher, Vojtěch (referee) ; Hela, Rudolf (advisor)
Global concrete production is increasing, which brings some environmental burden. A certain solution is the use of secondary raw materials, which has been a long-standing practice in the construction industry. One of the most widespread secondary raw materials is power fly ash. However, in recent years trends have been directed towards maximizing their utility properties. The aim of this work was to study the possibilities of activation of power plant fly ash as an active admixture in concrete. The thesis is divided into two parts, the theoretical and the practical part. The theoretical part describes in detail the possibilities of power plant fly ash activation for use as an active admixture in concrete. The practical part of the thesis is focused on mechanical activation, where the knowledge of the theoretical part is verified on various fly ash.
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Proposition of new type of injection material with electrically conductive function
Uher, Vojtěch ; Černý, Vít (referee) ; Drochytka, Rostislav (advisor)
The bachelor thesis deals with the design of a new type of grouting material with electrically conductive function suitable for connecting cracks and gaps in building protection systems against lightning strikes and surges. The theoretical part summarizes the important knowledge about the grouting and grouting materials, introduces the current state of knowledge in the field of lightning and surge protection of buildings and also the preconditions of electrical conductivity of cement-based composite materials. In the practical part are summarized selected properties, which the electrically conductive grouting material should have and the relevant standards tests for experimental verification of selected properties are described. A wide range of primary and secondary fillers are studied and the most suitable ones are chosen to achieve a low electrical resistivity value. At the end of the thesis, there are recipes based on amassed knowledge and using secondary fillers to reduce the environmental impact of the developed materials during mass production. Reduced resistivity has been demonstrated in recipes using waste carbon and chopped carbon fibers, but has failed to fully meet standard requirements. The result of the work are new recipes and knowledge that can serve as a basis for further research.
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