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Dielectric properties of liquid insulators
Jahn, Michal ; Starý, Jiří (referee) ; Špinka, Jiří (advisor)
This master‘s thesis deals with measurement of liquid dielectric materials (insulators). Above all, it is the different kinds of clean and drinking water, but also transformer oils. There was done theoretical information retrieval about the given topic in this project and on the basis of theory there were realized the relevant measurements of selected properties of liquid dielectric, such as permittivity, capacitance, loss number, conductivity, but also temperature dependence of these parameters. The measurements were realized with the help of product manufactured at the faculty FEKT VUT and with the help of measuring system AGILENT 16452A. The measured results were evaluated, graphically processed and compared.
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Preparation and characterization of plasma activated water for bio applications
Lemonová, Hana ; Matěj,, Klas (referee) ; Krčma, František (advisor)
The aim of this master thesis is the preparation and characterization of plasma activated water (PAW) prepared by dielectric barrier discharge at atmospheric pressure in air for the future applications in agriculture and medicine. The theoretical part is focused on plasma activated water and its effects on seeds and plants. The work also deals with the preparation and application of PAW in the world. Various types of plasma discharge configurations suitable for its preparation are described here. In the experimental part of the master thesis, distilled and tap water were chosen for activation. The concentrations of active particles in PAW generated by DBD such as nitrites, nitrates and hydrogen peroxide were determined. The value of the concentration of active particles changes probably due to mutual interactions when nitrites are oxidized by hydrogen peroxide to nitrates. Physical properties of PAW such as conductivity and pH were also characterized. After the preparation of PAW, the conductivity increases due to the increase in the concentration of active particles formed by dissociation and ionization of water molecules by plasma. The particles presented in the air, which are dissociated and ionized by plasma, also diffuse into the liquid, and contribute to this increase. The decrease in pH also corresponds to an increase in the concentration of hydrogen ions and the formation of nitric acids. Another aspect of this work was to study plasma activated water during the first eight hours after its preparation and to determine its properties. We have found that PAW prepared from tap water retains its characteristic properties for at least 8 hours and distilled water for 6 hours. In the master thesis, the analysis of plasma discharge was performed using optical emission spectroscopy. OES measurements were performed in the wavelength range 300 to 800 nm. The second positive nitrogen system (N2 (C 3u) N2 (B 3g)) and the first positive nitrogen system (N2 (B 3g) N2 (A 3+u)) were identified in the overview spectrum. Molecular nitrogen ions, OH· radicals, atomic oxygen and atomic hydrogen can be observed in the spectrum, too. The dielectric barrier discharge was also captured using a high-speed camera, and the recording shows the occurrence of multiple discharges that are spatially as well as temporary unstable.
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Study of organic based structures for solar cells
Kostovčík, Tomas ; Hégr, Ondřej (referee) ; Boušek, Jaroslav (advisor)
Práce se zabývá problematikou využití organických materiálů v solárních článcích. V úvodu práce jsou rozebrány a vysvětleny jednotlivé fyzikální a chemické jevy, které ovlivňují vlastnosti organických materiálů. Práce pokračuje rozborem působení rozličných struktur organických solárních článků na jejich vlastnosti. Dále je popsána technologie výroby vzorku a jsou v ní uvedeny výsledky měření fotovodivosti.
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Testing of polymeric piezoresistive materials for use in pressure sensors
Janík, Jan ; Chladil, Ladislav (referee) ; Čech, Ondřej (advisor)
The aim of the bachelor’s thesis is to choose convenient piezoresistive and conductive materials for pressure sensors in the field of e-textiles. Thesis is divided into practical and theoretical part. Theoretical part deals with piezoeresistive effect itself and describes composite and piezoresistive materials. Practical part is focused on laboratory measuring resistance and capacitance of pressure materials and sensors in dependence on stress level. This part also includes practical reliability testings of conductive materials using accelerated aging testing methods.
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Study of properties of electrolytically modified NaCl solutions.
Brázda, Lukáš ; Mika, Otakar Jiří (referee) ; Mašek, Ivan (advisor)
This work concentrates on the study of properties of NaCl solutions, prepared by electrolysis and their using for disinfection of water. Then it is focused on reporting on possibality for corrosin of metals, whice are used in water distribution. For study was used 0,25 mol/l, 0,1 mol/l, 0,05 mol/l NaCl solutions and input direct-current voltage for electrolysis was 6V a 12 V. During the electrolysis pH and conducitivity were measured. After the end of electrolysis free active chlorine and chlorides were determined on the time. For electrolysis was used diaphragm.
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Diagnostics of semiconductors properties
Šeliga, Ladislav ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This thesis describes the basic properties of semiconductor materials and methods of their measuring. In the first part of this work are discussed elemental semiconductors, semiconductor compounds and the band structure. The next section describes current conduction in semiconductors, methods for measuring resistivity. This work is focused on the measuring drift mobility of minority charge carriers using the Haynes-Shockley method for a sample of silicon semiconductor, the creation of automated workplace in the development environment VEE Pro and resistivity measurements of silicon samples.
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High-voltage method for measuring the specific conductivity of tissue
Uher, Jakub ; Novotná, Veronika (referee) ; Červinka, Dalibor (advisor)
This master´s thesis is dedicated to the ever-improving medical method - electroporation. This work is divided into six chapters. The first two chapters describe what electroporation entails and how it affects the tissue, how we can evaluate it and how much influence the change in tissue temperature has on measurements. The third chapter deals with the design of coaxial arrangement of electrodes - from the initial simulation to the physical product. In the fourth chapter, the measuring workplace is shown. The penultimate chapter is described and processed by individual experiments carried out on animal tissue. The last, sixth chapter summarizes the possible inaccuracies that arise in the measurement and therefore affect the results.
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The influence of ionic liquids on functional elements in lithium-ion batteries
Meščánková, Veronika ; Sedlaříková, Marie (referee) ; Máca, Josef (advisor)
This thesis deals with ionic liquids, their conductivity and the action of the electrode materials, separators and current collectors. The theoretical part is focused on the properties of ionic liquids, Li-ion batteries, corrosion, conductivity and analysis elements. The practical part is focused on the production of graphite electrodes, measuring the conductivity of ionic liquids with different parts of lithium – ion battery and measuring the potential window. Also, there is the effect of ionic liquids described in these parts.
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