|
|
Plasma diagnostics of electric discharges generated in selected configurations in liquids
Vašíček, Michal ; Bartlová, Milada (referee) ; Kozáková, Zdenka (advisor)
My diploma thesis is focused on a comparison of direct-current and high frequency (15-80 kHz) electric discharge, which generates non-thermal plasma in water solution of sodium chloride. Mainly current-voltage and Lissajous charts are discussed in the first part of this thesis. These charts describe different discharge phases: electrolysis, bubble formation, discharge breakdown and discharge regular operation in a pin-hole of a dielectric barrier. Influence of frequency, electrolyte conductivity, thickness of the diaphragm (or length of the capillary) and pin-hole diameter on discharge breakdown and bubble generation was studied, too. Measurements were realized in a polycarbonate reactor with total volume of 110 ml, which was divided by a changeable polyacetal insulating wall. This wall divided the reactor into two approximately equal spaces with one stainless steel planar electrode in each part. The Shapal-MTM ceramic discs (thickness of 0.3–1.5 mm and diameter of the central pin-hole of 0.3-0.9 mm) were mounted in the centre of the insulating wall. Initial conductivity of sodium chloride solution was chosen within the interval of 100900 S/cm. The second part of my thesis compares an influence of the direct-current (DC) and high frequency (HF) power sources on physical solution properties (conductivity, pH and temperature) and generation of hydrogen peroxide. A plasma reactor with total volume of 4 l and with mixing set up was divided into two equal spaces with one planar platinum electrode in each part. Diaphragm with thickness of 0.6 mm and pin-hole diameter of 0.6 mm was installed in the middle of the separating wall. Experiment was held at discharge operation of 45 W for 40 minutes with both power sources. Detection of hydrogen peroxide was realised by using a titanium reagent forming a yellow complex, which was analysed by absorption spectroscopy. If HF discharge power is plotted as a function of applied frequency, exponential decrease of frequency with increasing power can be observed. Higher breakdown voltage is necessary for thicker dielectric barriers, on the other hand for bigger diameter of the pin-hole lower breakdown voltage and higher power is needed in DC as well as in HF regime. Breakdown voltage is decreased by the increasing conductivity in both regimes; due to more charge carriers in the higher conductivity lower breakdown voltage is needed. However frequency in HF regime and DC discharge power increases. HF discharge power is decreased by the increasing conductivity. Solution conductivity and temperature are increased by initial conductivity value in both discharge regimes. Solution pH drops to acidic conditions when HF or DC positive regime is applied due to the generation of reactive species and electrolysis (in DC regime). However solution becomes alkaline when DC negative regime is applied. Concentration of hydrogen peroxide is produced linearly when HF or DC negative regime is applied and it depends on initial solution conductivity.
|
|
| |
|
|
Electrical features of surface discharge for organic material decomposition
Budík, Martin ; Zdražil, Vladimír (referee) ; Bartlová, Milada (advisor)
The aim of this semestral work is to describe importance of electric surface discharges for decomposition of organic substances. This will serve to practical measurement of VA characteristic of surface discharge ignition, flow effect and type of portative gas for VA characteristic and moment of ignition of surface discharge. Then measurement of dynamic characteristic of surface discharge in assorted portative gases with diverse kind of flowage and setting of energetic ratios in discharge by means of dynamic characteristics. The main part of this work is dedicated to conditions of discharge ignition, its characteristics in different conditions and another types of discharges.
|
|
|
Influence of Solvent on Deformation Behavior of Hydrogels
Kulovaná, Eva ; Bartlová, Milada (referee) ; Mráček, Aleš (referee) ; Žídek, Jan (advisor)
The thesis deals with molecular dynamic simulation of the influence of water on the deformation of hydrogels. Hydrogels are model materials formed from macromolecular networks solvated with water. It was found that water can form bridges between macromolecules that take the form of temporary ionic crosslinks. These bridges affect the behavior of the network during deformation. Water bridges are water molecules that have a limited radius of motion in the space between two macromolecules. The concentration of the water bridges was regulated by a partial charge on the macromolecular chain in the organic network. Bridges are a type of interaction that is relatively strong but significantly delocalized. It is not possible to dissociate the water bridge, after dissociation it will be re-created in another place in a short time. The influence of water bridges was compared with other types of network crosslinks, especially covalent and physical bonds. Covalent crosslinks are modeled as a simple binding interaction between two macromolecules. They are undissociable and are local throughout the simulation. Physical bonds are modeled as micelles, where hydrophobic groups form the core and hydrophilic groups form the micelle shell. Physical bonds have the nature of dissociable bonds that are local. Different types of crosslinks have different effects on deformation properties. The deformation of a network containing a combination of two types of crosslinks was simulated: (i) physically-covalent, (ii) ionically-covalent, and (iii) physically-ionic networks and (iv) ternary physically-covalent-ion networks. For individual and combined networks, the behavior depending on simple networks was verified. The number of water bridges was fundamentally affected by the primary structure of the chains. When the PEG chain was replaced with hydrophobic polyoxymethylene (POM) or polyoxytrimethylene (POTM), their solvation and mechanical behavior deteriorated.
|
|
|
Visual Art in the Housing Estates of Brno (1945–1989)
Kořínková, Jana ; Bartlová, Milena (referee) ; Hrůša, Petr (referee) ; Chamonikolasová, Kaliopi (advisor)
With special attention being paid to the development in the city of Brno, the dissertation focuses on the issue of applying artworks in Czechoslovak architecture after World War II. The main research questions – Why were in Czechoslovakia after 1945 artworks again integrated in architecture and what strategies were applied in the case of the newly built housing estates in the city of Brno? – are answered in two successive sections. First, the institutional background for application of art in architecture in the light of the events in Brno (1945–1993) is examined; the closing part is devoted to three case studies that illustrate local development in the period of socialist realism, creative release of the1960s and political normalization. The aim is to highlight the complexity of the examined subject and refute a popularly handed down conviction that integration of artworks into architecture in the period of socialism was motivated exclusively by the communist propaganda, and to show that the attempts to create a synthesis of art and architecture were also based both on earlier theoretical considerations about the educational function of art and its effect on humans and the need to improve poor economic situation of artists after World War II.
|
|
|
attributes of corporeality
Lukešová, Eva ; Bartlová, Milena (referee) ; Gabriel, Michal (advisor)
My thesis titled Attributes of corporeality is a continuation of my thinking on the topic of identity. Now I approach identity as a category, not as an identity that belongs to a particular person. I consider the question of how is identity shaped in a postmodern, globalized world and how is it related to corporeality. My answer is based on the reality I know, on the current state of society. However, the intention of my work is above all to express my idea, which is rather a utopian scenario than anything else.
|
|
|
Preparation and testing of lightweight composite materials
Peroutka, Jakub ; Bartlová, Milada (referee) ; Žídek, Jan (advisor)
This thesis deals with simulation of composite origami-like auxetic materials, which exhibit self – assembly effect (SE). The freeware named INKSCAPE was used for preparing structures. Simulations were made by MATLAB with GIBBON plugin using finite element method. For structure evaluation, freeware programme FEBIO Studio were used. The theoretical part was divided into four sections – auxetic materials, shape memory polymer materials, self-assembly auxetic materials and thermal expansion of auxetic materials. Each section contains of basic information and knowledge from its category. For each area of the theoretical part, literature searches were conducted based on the latest findings on the given topic. The experimental part consisted of simulations of prepared structures and their subsequent evalution using MATLAB programme. Simulations were performed for two types of auxetic structures that differed in the size of external angle (121,99 °and 131,78 °) in total. In the next step, simulation of cubic structure with dimensions 20 × 20 mm was performed. The prepared auxetic structures were composed of two neo- Hookean materials and were further divided into homogeneous, two-layered and multi-layers structures. For two-layer and multi-layer structures, a thermal expansion simulation was performed, and with the help of the values obtained from the simulation of the cube structure, the temperature change was calculated for individual simulation states, which were randomly determined. Furthermore, stress histograms were made for prepared structures and the most frequent stress value for the given simulation state was determined. The last part consisted of determining the thermal expansion of the simulated materials. Coefficient of thermal expansion of prepared materials was calculated using data obtained during each simulation of the cubic structure of dimensions mentioned above.
|
|
|
Egon Bondy and his atheism. The comparation of his academical and belletristic works.
Dundáčková, Petra ; Bartlová, Milena (advisor) ; Nešpor, Zdeněk (referee)
This study is based on comparative analysis of (un)faith in the literary and academic works of the writer and philosopher Egon Bondy. The aim of this research is to find out how much he was actually an avowed atheist and what differences are in the concept of transcendence in the philosophical and literary works. The study is divided into three sections. The first section is devoted to the theoretical framework, the second section pays attention to Bondy's biography and the third section concerns the analysis and comparison of his philosophical and literary works. The theoretical first section primarily deals with Ricœur's comparison of narrative in history and philosophy presented in a monograph Time and Narrative, which is analogously used for the comparison of literature and philosophy. An important fact is that Bondy's literary work is characterized by significant autobiographical features and stands on the border between literature and philosophy. The second section deals with the life of Egon Bondy and his work in the underground environment. The third section pays attention to the main lines of the selected works (Philosophical work I.-II., Nepovídka) and there is a comparison of texts based on a content analysis. The result is the finding of a high similarity of expressed ideas. Bondy...
|
|
|
The Chronicles of the Triforium of the Cathedral of St. Vitus at Prague Castle
Lenochová, Šárka ; Bartlová, Milena (advisor) ; Čornej, Petr (referee)
Cílem práce je proto ověřit věrohodnost výpovědí jednotlivých nápisů srovnáním jejich obsahu s jinými, nezávislými zprávami. Součástí dané analýzy je také ověření pravosti dnešního stavu nápisů za pomoci zjištění, která přinesly dosavadní odborné restaurátorské průzkumy. Vzhledem ktomu, že tématem věrohodnosti a pravosti nápisů se zabývala již nejedna generace historiků, si práce klade za cíl také utřídění a zpřehlednění poznatků o nápisech získaných více jak dvousetletým bádáním. Powered by TCPDF (www.tcpdf.org)
|
|
|
Influence of Solvent on Deformation Behavior of Hydrogels
Kulovaná, Eva ; Bartlová, Milada (referee) ; Mráček, Aleš (referee) ; Žídek, Jan (advisor)
The thesis deals with molecular dynamic simulation of the influence of water on the deformation of hydrogels. Hydrogels are model materials formed from macromolecular networks solvated with water. It was found that water can form bridges between macromolecules that take the form of temporary ionic crosslinks. These bridges affect the behavior of the network during deformation. Water bridges are water molecules that have a limited radius of motion in the space between two macromolecules. The concentration of the water bridges was regulated by a partial charge on the macromolecular chain in the organic network. Bridges are a type of interaction that is relatively strong but significantly delocalized. It is not possible to dissociate the water bridge, after dissociation it will be re-created in another place in a short time. The influence of water bridges was compared with other types of network crosslinks, especially covalent and physical bonds. Covalent crosslinks are modeled as a simple binding interaction between two macromolecules. They are undissociable and are local throughout the simulation. Physical bonds are modeled as micelles, where hydrophobic groups form the core and hydrophilic groups form the micelle shell. Physical bonds have the nature of dissociable bonds that are local. Different types of crosslinks have different effects on deformation properties. The deformation of a network containing a combination of two types of crosslinks was simulated: (i) physically-covalent, (ii) ionically-covalent, and (iii) physically-ionic networks and (iv) ternary physically-covalent-ion networks. For individual and combined networks, the behavior depending on simple networks was verified. The number of water bridges was fundamentally affected by the primary structure of the chains. When the PEG chain was replaced with hydrophobic polyoxymethylene (POM) or polyoxytrimethylene (POTM), their solvation and mechanical behavior deteriorated.
|
guest ::
RSS feed.