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Thermodynamic Conditions in Quenching Chamber of Low Voltage Circuit Breaker
Urban, Ferdinand ; Hüttner,, Ľudovít (referee) ; Kapička, Vratislav (referee) ; Aubrecht, Vladimír (advisor)
Práce se zabývá studiem procesů probíhajících při zhášení silnoproudého oblouku ve zhášecí komoře jističe. Je zaměřena na výpočet dynamiky tekutin a teplotního pole v okolí elektrického oblouku. V práci je dále popsán vliv vzdálenosti plechů v komoře a vliv tvarů plechů z hlediska aerodynamických podmínek uvnitř komory. Dalším cílem dosaženým touto prací je poskytnutí informací o vlivu polohy elektrického oblouku na termodynamické vlastnosti uvnitř komory. Toto je důležité, zejména pokud je oblouk do komory vtahován jinými silami, např. elektromagnetickými a během tohoto vtahovacího procesu mění svůj tvar i polohu. Za účelem co nejjednoduššího, ale zároveň co nejefektivnějšího řešení úkolu, byl vyvinut software určen speciálně pro výpočet dynamiky tekutin numerickou metodou konečných objemů (FVM). Tato metoda je, v porovnání s rozšířenější metodou konečných prvků (FEM), vhodnější pro výpočet dynamiky tekutin (CFD) zejména proto, že režie na výpočet jedné iterace jsou menší v porovnání s ostatními numerickými metodami. Další výhodou tohoto softwarového řešení je jeho modularita a rozšiřitelnost. Cely koncept softwaru je postaven na tzv. zásuvných modulech. Díky tomuto řešení můžeme využít výpočtové jádro pro další numerické analýzy, např. strukturální, elektromagnetickou apod. Jediná potřeba pro úspěšné používání těchto analýz je napsáni solveru pro konečné prvky (FEM). Jelikož je software koncipován jako multi–thread aplikace, využívá výkon současných vícejádrových procesorů naplno. Tato vlastnost se ještě více projeví, pokud se výpočet přesune z CPU na GPU. Jelikož současné grafické karty vyšších tříd mají několik desítek až stovek výpočetních jader a pracují s mnohem rychlejšími pamětmi, než CPU, je výpočetní výkon několikanásobně vyšší.
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Optimization of the indoor climate of an eatery by air conditioning
Mrázková, Hana ; Kašpar, Antonín (referee) ; Šikula, Ondřej (advisor)
This thesis is focused on the optimization of the catering service internal environment by air conditioning in Brno. This concept uses a forced ventilation system and air conditioning. The theoretical part addresses the proper air distribution in the catering operation. The experimental part involves the measurement of carbon dioxide, air velocity, relative humidity and air temperature and the temperature of the thermometer ball. Depending on the observed values a technical solution was created in variations and applied in the calculation program.
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Selected heat transfer phenomena in air conditioning
Vojkůvková, Petra ; Gebauer, Günter (referee) ; Šikula, Ondřej (advisor)
Numerical simulation is a scientific method used to describe characteristics of examined system by means of experiments on its mathematical model. This thesis uses this method to elucidate the processes taking place in two different systems. Firstly it deals with the design of air conditioning systems for buildings, focusing on the mixing chambers. It focuses on the formation of condensation of water vapor in mixing chambers under conditions where the final temperature of the mixture does not drop below the saturation curve. Second prepared topic falls within the field of thermodynamics applied in food production. In order to assess the sufficiency of air-cooling method examines the thermal field in the product and evaluates the application of air-cooling assembly line in practice.
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The impact of new water area on microclimate
Bartůňková, Kristýna ; Sokol, Zbyněk
In this contribution the impact of new water area on local climate is studied. The area of interest is newly originated lake Most in northern Bohemia. The impacts on microclimate that are evoked by physic-geographical changes in the area are studied by the help of the NWP model COSMO. The part of this model is Lake Model FLake. Input data are measured at the meteorological observatory Kopisty and at the lake station that measures also the water temperature in 16 vertical levels to the depth of 20 m. First results show significant influence of lake existence on air temperature, especially in summer months (June, July and August). The maximum influence is 1.2°C cooling in the surface level of the atmosphere. With the rising distance from the surface the impact on air temperature is decreasing.
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Influence of geometric parameters on the stiffness of traditional dovetail timber joint
Kunecký, Jiří ; Cacciotti, Riccardo ; Kloiber, Michal
The paper presents the development of numerical modeling for a traditional dovetail timber joint. The objective is to find the influence of its geometrical properties on the mechanical stiffness of the joint as well as to assess the main problems and limitations faced during the numerical modeling of the structure. An experiment with a replicated timber joint was used to validate the model. Material properties were ascertained and contact adjustment was made. Parametric study was performed: two angles of the joint beams were varied. Suitable ranges of the angles for each type of loading were found. Main limitations and problems present in the modeling are depicted in the discussion.
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Impact of Pedogenetic Processes on Pore System Development and Consequently on Soil Hydraulic Properties
Kodešová, R. ; Kodeš, V. ; Žigová, Anna
Soil micromorphological properties were studied on soil thin sections to define configuration of soil porous system that is reflected in a shape of soil hydraulic properties. The micromorphological study of soil porous systems discovered multimodality of pore-size distributions and hierarchical pore configuration. Some pore systems were affected by clay coatings. The soil water retention curves also frequently display multimodality. The single-porosity and dual-permeability models in HYDRUS-1D (Šimůnek et al., 2003, 2005) were applied for description of soil hydraulic properties and soil water flow. Results showed a very important impact of multimodality of soil porous systems and effect of clay coatings on water flow process in soil.
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