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Diffusion processes in modified humic gels
Grunt, Jakub ; Sedláček, Petr (referee) ; Klučáková, Martina (advisor)
This bachelor thesis presents a study on diffusion of cupric ions in humic acid gels. A total of four types of samples were made during a modified preparation of gels. Humic acids were dissolved either in sodium hydroxide or in the solution of sodium triphosphate. Subsequently, hydrochloric acid and magnesium chlorid were used for "precipitation" of the gels. Gained samples differed particularly in the nature of interactions forming their gel structures. All the samples were subjected to diffusion experiments. Two different methods – constant-source diffusion and immediate planar source diffusion – were used to assign the diffusion coefficients. Both these methods were based on monitoring how the diffusion profiles of cupric ions in gels develop in time and on assigning the overall diffusion flow. The aim of the thesis was to assess the impact of gel preparation procedure and resultant structure on diffusion coefficients of cupric ions and their transport attributes in gels in general. Two different methods of diffusion inquiry were chosen particularly to assess the impact of cupric ion concentration on the diffusion coefficient.
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Semiconductor nanowire growth modelling
Kovács, Roland ; Bartošík, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
This bachelor’s thesis deals with modelling of semiconductor nanowires growth. The work describes the mechanism of growth using the VLS method. The main objective is to simulate the distribution of eutectic material in a droplet in the initial stage of growth. Mathematical models describing different situations of material diffusion in the droplet were depeloped. The simulation model is programmed in MATLAB.
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Diffusion of cupric ions in humic gel
Kalina, Michal ; Gregorová,, Eva (referee) ; Klučáková, Martina (advisor)
The bachelor´s thesis deals with the study of non–stationary diffusion of copper (II) ions in humic gel. The objective of the study was to validate that the diffusion is influenced by the volume of cupric ions solution and by the length of tubes filled with humic gel. Diffusion was characterized by the value of diffusion flux and by the copper (II) ionic concentration profiles in humic gel. The data necessary for calculation were obtained by spectrophotometric measuring of the extracts of each slice after diffusion.
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Numerické simulace teplotního a vlhkostního pole ve střešních konstrukcích
Šmiták, Jan
In this bachelor thesis are compared different types of roof structures, whose compositions are different in type and thickness of the used materials. Explained is here of thermal transfer and water vapor diffusion of the structures. By using numerical simulation of calculation software which is based on the finite element method, described temperature and moisture field in stable (stationary) conditions in different geometric and boundary conditions.
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