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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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Diffusion of cupric ions in humic hydrogels
Grunt, Jakub ; Pabst, Willi (referee) ; Klučáková, Martina (advisor)
Presented diploma thesis focuses on the study of diffusion of cupric ions in humic acid hydrogels. A total of eight different hydrogels were prepared by dissolving the humic acids with sodium hydroxide and sodium triphosphate. For the purpose of precipitation and cross linking, hydrochloric acid and chlorides of magnesium, calcium and iron were used during a modified preparation of gels. Different gel-forming interactions were achieved by modifying the preparation of hydrogel systems. The aim of the thesis was to assess the effect of gel preparation procedure on the transport properties of the gels. Therefore, diffusion coeficients were determined for all samples. Two different methods - constant-source diffusion and instantaneous planar source diffusion - were used to assign the diffusion coefficients. Methods differ in source concentrations of cupric ions and are suitable for assessing the impact of the concentration on the diffusion coefficient. Both these methods were based on monitoring temporal evolution of diffusion profiles of cupric ions and on assigning the overall diffusion flow. Copper ions were elected as diffusing medium because of their high affinity and strong binding to humic acids. Measurements show that gels prepared using polyphosphate allow slightly faster diffusion of cupric ions and that the constant-source method provides higher diffusion coefficients in comparison to instantaneous planar source method.
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Chemical heat treatment of steel
Pišek, David ; Molliková, Eva (referee) ; Němec, Karel (advisor)
This bachelor thesis deals with methods of chemical and heat treatment of steel. This thesis incorporates basic findings and ways of the performance of the chemical and heat treatment with detailed specialization in cementation and nitration of steels. This study is also focused on property of surface layers and their use. The primary aim of this thesis is to evolve an overview of the most frequent methods of chemical and heat treatment of steel and to evaluate advantages and disadvantages of individual methods for a practical use in industry.
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Influence of polyelectrolyte biopolymers on transport of ions
Kolesa, Pavel ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
This bachelor thesis was focused on the study of interaction of cationic biopolymer with model diffusion probe (basic organic dye) in the gel media by diffusion processes. The main aim was optimization of simply laboratory diffusion technique (unsteady diffusion in a cuvette) because of study on interactions of chosen biopolymer with model compound depending on temperature. Cationic chitosan was chosen as model biopolymer. The model diffusion compound was chosen organic anionic dye Acidal Black 10B (C.I. 20470). Diffusion processes in plastic cuvettes were realized by transport of dye in a hydrogel media based on thermoreversible polysaccharide – agarose. The important content of this method is a monitoring of the time progression of diffusion profile by UV-VIS spectrophotometry. Important part of this work was characterization of hydrogel medium and biopolymers by basic physical-chemical methods. This bachelor thesis is focused on reactivity of chitosan and its behavior in different systems. Unsteady diffusion in cuvettes appears to be a universal method for the study on reactivity of biopolymers.
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Simulations of synthetic diffusion MRI data based on Brownian motion
Valla, Radek ; Mikl, Michal (referee) ; Labounek, René (advisor)
This master thesis focuses on dMRI (diffusion magnetic resonance imaging) and its dependance on diffusion in human brain tissue. It is described how to retrieve an image from gained data and its properties, advantages and disadvantages. It mentions problem in detecting kissing fibres due to its similarity with crossing fibres. Design of mathematical models of axons is decribed and suggested measurement to detect difference in signals for kissing and crossing fibres. It describes new simulator of diffusion-weighted MRI (dMRI) data which is able to generate it based on random walk algorithm with geometrical constraints not only for crossing fiber geometry, but also as o novelty for bending and kissing fiber geometries. This study contains results of simulations and disscusion about their usefulness with suggestions for simulator improvement. Simulated dMRI data shows significant difference in certain gradients. Data reconstruction shows, that these reults cannot be reconstructed into the same geometry as it was simulated for.
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Optoelectronic sensor of polarization state of transmitted light
Bajgar, Aleš ; Rampl, Ivan (referee) ; Tománek, Pavel (advisor)
The living body tissues consist of cells which dimensions are bigger than a wavelength of visible light. Therefore a Mie scattering of transmitted light occurs and different polarization states arise. The changes of polarization state due to the multiple scattering of light in the biological cellular tissues allow measure the aging of biological tissue. The transmitted polarized laser light exhibits multiple scattering on the thin slice of sample.
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Diffusion in humic gels with incorporated metal ions
Krpatová, Lenka ; Gregorová,, Eva (referee) ; Klučáková, Martina (advisor)
The main topic of this diploma thesis is the study of diffusion of humic gels with incorporation of copper ions. Humic gel was prepared by precipitation of humate sodium with 5 M copper dichloride. First, it was necessary to find a useful extraction of surfactant that would have extracted copper from humic gel. Magnesium chloride was chosen as optimal surfactant from obtain relation of concentration copper(II) ions on time. Magnesium chloride was used to elution of copper from the slices of the gel. In next part it was important to verify the diffusion method that reaction in gel was not proceed in. Elution from slices of the gel before and after diffusion were scaled on the UV/VIS spectrophotometer. Experiment was prepared for times 3, 12, 24, 48 and 72 hours. Coefficient of the diffusion was calculated from obtained results, but 72 hours was not counted to the result.¨ From the coeficient of diffusion theoretic concentration profiles were calculated and then they were compared with experimentally results. Profile for 72 hours shows that it was unusable because it was oblate and fringe and concentration was lower than in other profiles. Other theoretic profiles agree.
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Errors of diffusion measurements for MRI
Kavan, Pavel ; Rampl, Ivan (referee) ; Bartušek, Karel (advisor)
The Bachelor’s thesis is, at it’s begining, focused on the imaging and diagnostic techniques based on principles of magnetic resonance imaging. Nowadays, nuclear magnetic resonance belongs to reputable examing methods of variable molecule matters. Especially, due to multiinterval spin-echo PFGSE methods. Further in this thesis is spin-echo pulse sequence simulated in the data processing computer program Matlab. Simulations influencing error measurement of b-factor and diffusion are performed. These simulations could help to prevent appearance of measurement errors at some other experiments.
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Optimalization of experimental method for study on penetration of humic acids into leaves.
Smilková, Marcela ; Pekař, Miloslav (referee) ; Sedláček, Petr (advisor)
This bachelor’s thesis is focused on the study of penetration of humic substances trough the plant cuticle. The main objective of the thesis aimed at a literature search on foliar fertilization and transport of substances in the plant leaves. According to the literature search, experimental technique was suggested and tested in order to study penetration of humic substances through the leaf cuticle. The method consists of observation of diffusion transport of humic acids between two inert agarose gels separated by the plant cuticle. Cuticles were prepared by the means of three different isolation procedures.
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