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Differential interferometry with suppression of the influence of refractive index of air for nanometrology
Holá, Miroslava ; Číp, Ondřej ; Hrabina, Jan ; Buchta, Zdeněk ; Lazar, Josef
We present an interferometric technique based on differential interferometry setup for measurement in the subnanometer scale in atmospheric conditions. The motivation for development of this ultraprecise technique is coming from the field of nanometrology. The key limiting factor in any optical measurement are fluctuations of the refractive index of air representing a source of uncertainty on the 1*E-6 level when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of overdetermined interferometric setup where a reference length is derived from a mechanical frame made from a material with very low thermal coefficient on the 1*E-8 level. The technique allows to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range acting as a tracking refractometer. The principle is demonstrated on an experimental setup and a set of measurements describing the performance is presented.
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FEM for flow and pollution transport in urban canopy
Bauer, Petr ; Klement, V. ; Žabka, V.
We develop a mathematical model of air flow and pollution transport in a simplified urban canopy based on incompressible Navier-Stokes equations for air flow and the advection-diffusion equation for concentration. The model is discretized by means of finite element method (FEM) and the resulting systems are solved using multigrid techniques. A numerical study of pollutant dispersion in a domain with two street canyons is presented.
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Effect of surface of semiconductor nanocrystals on their properties: investigation by laser spectroscopy
Preclíková, Jana ; Malý, Petr (advisor) ; Franc, Jan (referee)
The topic of the diploma thesis is chemical treatment of the surfaces of semiconductor nanocrystals CdS and CdSe in the form of thin nanocrystalline films prepared by chemical bath deposition. The evolution of photoluminescence and absorption spectra was investigated under treatment by water, toluene, butylamine, pyridine and hydrogen peroxide. The strongest changes were observed by samples soaked in water, pyridine and aqueous solution of pyridine. The observed effects were explained by partly dissolving of nanocrystals by water and affecting behaviour of photoexcited holes in the presence of the strong hole acceptor pyridine. The second part of this diploma thesis deals with photochromic properties of silver nanoparticles in a titanium oxide matrix. The photochromic behaviour of the samples was examined in detail. A phenomenological model of photochromic changes was suggested in analogy with the hole burning spectroscopy. In order to better understand the microscopic processes in this composite material other experiments were realized - e.g. samples were UV irradiated, or laser illuminated under lowered air pressure, pump & probe experiment. Under laser irradiation optical extinction of some nanoparticles was decreased. Simultaneously, changes of plasmon resonances of the rest of nanoparticels were...
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Studying the possibility of improving the frost resistance of concrete
Šafrata, Pavel ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The purpose of this study is to summarize theoretical and practical knowledge of frost resistance of concrete. It suggests, that there are numerous factors affecting the freeze-thaw resistence of concrete. These are especially raw materials, production technology, time and method of curing. The influence of addition, air entrainment and air void structure is complied and evaluated experimentally. The testing method is crucial for the evaluation of durability of concrete. Hence, this thesis includes a research of methods used around the world and practical comparison of some of them. This thesis is valuable because of implementation of the requirement in the standard ČSN EN 206 (2014) for the frost resistence of concrete in exposure classes XF1 and XF3.
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Effect of admixtures on the properties of metakaolin geopolymer
Halasová, Kristýna ; Vyšvařil, Martin (referee) ; Rovnaník, Pavel (advisor)
Geopolymers are amorphous to semi-crystalline aluminosilicate polymers which are formed from inorganic polycondensation reaction of a solid aluminosilicate precursor with an alkaline sodium hydroxide or silicate. The resulting materials exhibit high durability, resistance to aggressive environments, high temperature resistance and many other properties that make them have received much attention in recent years, not only in construction. This thesis describes the influence of additives commonly used in concrete and mortar (water reducing, superplasticizer, air-entraining, foamer and defoamer, anti-shrinkage, stabilization) on the behavior of metakaolin in geopolymer fresh and hardened state. It describes metakaolin geopolymer effect on rheological properties of fresh mixtures, compressive strength and flexural strength after 28 days and a density in the fresh and hardened state.
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Hygrothermal processes in walls of wooden houses
Vencel, Lukáš ; Vlach, František (referee) ; Bečkovský, David (advisor)
This diploma thesis solves the problems of hydrothermal processes in walls of wooden houses and associated issues. A chosen were two apartment buildings, where they underwent exmerimental measurement of indor air, in order to determine the boundary conditions commonly boundary building evelope. Was followed by hygrothermal analysis of four commonly used constructions of wooden buildings in the Czech Republic, using various numerical methods. The quantity of information obtained from various numerical methods were analyzed individually. The final part of the thesis is devoted to experimental measurements of diffusion properties of materials. Namely foil vapor barrier, in terms of its influence on the perforation vapor diffusion resistance factor. Information obtained from the experiments were applied to re numerical analysis for walls with a foil vapor barrier. Followed by comparing both cases, in terms of changes hygrothermal behavior of structures with influence of perforation of the vapor barrier.
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Microclimate study rooms with natural ventilation
Hajn, Daniel ; Uher, Pavel (referee) ; Rubinová, Olga (advisor)
Master thesis solves the level of CO2 concentration in the premises of universities in Brno. The main objectives of the processed data measured from two monitored rooms, compare it with the permissible limits of concentration, evaluate the effectiveness of natural ventilation and develop a more efficient way to exchange air with forced venti-lation. Space solutions are part of the Philosophical Faculty of Masaryk University, the fourth above-ground floors of buildings A and B1. The theoretical part deals with CO2 concentrations, measurement methods, the influence of CO2 on the organism and the assessment of daylight.
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Hotel
Wawreczka, Stefan ; Blažková, Vendula (referee) ; Daněk, Lukáš (advisor)
Diploma thesis deals with the design documentation hotel building in the village of Vendryně. The building is designed in accordance with the existing this area and the slope of the terrain. This is a two-tier four-storey building. Above the 1st floor is designed flat vegetation roof and above the 4th floor is gabled roof. The building contains part of the accommodation, dining area and facilities for staff. Work includes architectural and layout design, preparation of construction drawings, design of fire safety design of buildings, basic thermal technical assessment and calculation of a selected wooden truss and a draft air exchange for restaurants and kitchens. The entire work will be complemented by a text part.
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Ventilation of near zero energy buildings
Fojtík, Pavel ; Horká, Lucie (referee) ; Hirš, Jiří (advisor)
Diploma thesis is focus on ventilation systems in Zero energy building and indoor air quality. Whole thesis has three part. First is about theory, where you can find law regulations and standards connected wit nZEB, factors influence IAQ and introduced ventilations systems. Second part is focus on particles transport in buildings like a nZEB and in heat recovery units. Last part of the thesis shows own design of the nZEB for Nový Lískovec.
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Application and evaluation of energy enthalpy heat exchanger
Jetelina, Michal ; Horák, Petr (referee) ; Uher, Pavel (advisor)
This master thesis is solving measuring the efficiency heat recovery and application unit, which includes heat recovery into selected building. In the first part of the thesis are analy-zed the different types of heat recovery system, their behavior and suitability of use in HVAC systems. The second part includes the actual experiment, when were measured parameters of air, which passed through the unit and then were analyzed the results. In the last part, third, was measured unit applied to the selected house and was compared to operation of the unit in case of use by the producer given unit parameters and measured parameters.
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