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Contact erosion of switchgear under real conditions
Holoubek, Josef ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This bachelor thesis is focused on the material loss - contacts erosion during switching process of the switchgears. First part is focused on the switchgears generally, their dividing and functions. Then there is closer look on the contacts of switchgears and what is necessary to be considered during their designing a operating. In this part there is also section devoted to the theory of the contacts erosion including the formulas for material loss calculation, which I found in existing literature. Practical part is focused on the contact system model and the measuring performed on this model. Measuring was also performed on the real switchgears for common use. There is also part devoted to this measuring. In the last part of thesis the analyze of the measured values is performed.
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Decomposition and stability of organic matter in soil
Tabaková, Eva ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
In the soil, the plant material is decomposed by several factors. In the process, one part of the carbon returns to the atmosphere as carbon dioxide, whereas another part is stabilised in the soil. The aim of this study is decomposition and stability of organic matter in soil using a simple and innovative TBI method. Through this method, we examined the weight change after the incubation period of 90 days, where biomass of green tea was degraded in cambodia soil. Tea bags have provided us with valuable information on the decomposition and amount of carbon in the soil, because the biomass itself is of organic origin. This information is based on the fact that the soil and the decomposition processes have a direct impact on the change in climatic conditions. Thanks to further analytical methods, elemental analysis, thermogravimetric analysis and infrared spectroscopy with Furier transformation, was found indispensable information about tea composition.
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Measurement of corrosion resistance of anodized aluminum protective surface layers
Redr, Martin ; Jandová, Kristýna (referee) ; Chladil, Ladislav (advisor)
This master’s thesis is focused on anodic oxidation of an aluminium surface with subsequent sealing of the surface using mid-temperature sealing methods. The research in the theoretical part of the thesis is carried out in surface treatments of aluminium and its alloys, where attention is mainly paid to anodic oxidation, as it is the most widely used surface treatment. The second discussed and at the same time key topic is the sealing process of the anodic coating, which has a fundamental effect on the quality of the corrosion resistance of the resulting surface. In the practical part of the thesis, a number of anodic oxidation experiments with subsequent sealing of the coating on prepared aluminium samples and their subsequent evaluation according to ČSN EN ISO 3210 standard were carried out. Mid-temperature sealing experiments were mainly focused on the use of triethanolamine (TEA), which seems very promising in terms of the resulting sealing quality.
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Embedded Modules of Modern Mobile Devices
Pelikán, Ondřej ; Čermák, Martin (referee) ; Křivka, Zbyněk (advisor)
This bachelor thesis concerns mobile application development for Windows Phone 7 platform focused on lifestyle changes and dealing with problems concerning weight, physical condition and appearance. The application uses built-in modules of modern mobile phones like GPS navigation, high resolution camera and Internet connection. The application development description starts from general introduction of the issue, through description of main features of the platform Windows Phone 7, concrete architecture of the application and solution of implementation problems, to description of methods and tools used for the design and planning, library and third-party framework description.
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Contact erosion of switching devices
Píška, Jakub ; Šimek, David (referee) ; Valenta, Jiří (advisor)
This bachelor thesis deals with the erosion of contacts, as one of the negative phenomena affecting contacts of switchgears. In its first part, it briefly summarizes the other negative influences that must be considered when designing switching devices. In the following part, the physical mechanism of erosion and the primary criterion of assessment - weight loss are approached. The last and main part of the work deals with design of the contact system for comparing this loss for for frequently used materials and testing on a real switchgear. After the tests, the results were analyzed primarily from the perspective of ignition angles, the polarities of the current pulse and the current flowing through the arc. Taking into account the influence of the material composition, the size of the contacts and the presence of the arc-runner.
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Bones implants based on Fe and Mg
Košíček, Adam ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This paper work deals with properties of metallic biomaterials in terms of their suitability for use as a temporary metal implants. The work focuses on biodegradable materials based on iron and suitable alloying elements, which would create a perfect implant. A part of this work describes procedure of creating biodegradable metallic samples with alloying element Magnesium and measuring the corrosion rates. There are a few theoretical chapters concerning permanent implants, function and composition of human bones, iron and magnesium in human body and biodegradable materials.
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Posouzení trvanlivosti vybraných druhů dřev pro obchodovatelný výrobek
Sion, Matěj
In this thesis, the problem of the resistance of terrace boards to biological degradation. The following woods were chosen for the experiment: 1) Garapa (Apuleia leiocarpa Vog.) → is a representative of tropical woods and at the same time a species required by customers. 2) Mulberry (Morus) → a possible alternative in future years. 3) Acetylated European alder wood (Alnus glutinosa) → a possible alternative, when this method of modification appears to be very effective. The selected woods were tested according to the ČSN EN 350 standard for resistance to the wood decay fungi of white rot (Trametes versicolor) and brown rot (Gloeophyllum trabeu) and Coniophora puteana). The second part of this thesis was the determination of the total content of extractive substances (ES), phenolic substances (FS), carbohydrates (C), and pH values of aqueous leachate selected wood species. All samples were tested and compared with each other. The wood of the mulberry tree was evaluated and as to how these properties change along the radius of the trunk. The selected woods have been found to be suitable for decking. Weight losses (white and brown rot) were in negative values, so the fungi were not able to attack the wood and it was classified in durability class 1 "very durable". From the point of view of chemical composition, it was found that the most chemical substances are contained in the wood of the mulberry tree, garapa, and the least acetylated alder. In the case of the mulberry tree, it was also found that the amount of chemical substances varies depending on the position along the stem radius. The high resistance of garapa and mulberry to wood-rotting fungi is mainly caused by the content of chemical substances. The resistance of acetylated alder was due to the acetylation process.
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Evaluation of resting energy expenditure and body composition in obese patients
Jílková, Anna ; Matoulek, Martin (advisor) ; Zelinka, Tomáš (referee)
Introduction: The basis of obesity treatment is a conservative regimen based on a reduced diet and physical activity, individually set for each person. As the obese often show extreme deviations in body composition compared to individuals of normal weight, it is often difficult to determine their energy needs or determine their energy expenditure. The gold standard for determining resting energy expenditure (REE) is examination using indirect calorimetry (IC). This method can also detect deviations from the calculations of predictive equations, determine the degree of adaptation of the individual to low energy intake, and thus set the appropriate therapy. Objectives: The main objective of the work is the analysis and description of data on body composition and resting energy expenditure values of selected groups of obese individuals whose REE measurement results using indirect calorimetry reached a level below 95 % of the predicted REE calculated using the Harris Benedict (H-B) equation. The sub-goals are to describe the dependence of the size of some components of body composition on the size of the REE and to find out if the deviations between the number of the total measured REE and the REE calculated using H-B in the adapted group are significant. Methodology: For the research 71 patients of...
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The effect of a weight loss on bone and energy metabolism in premenopausal women with obesity
Malinová, Pavlína ; Zikán, Vít (advisor) ; Michalská, Dana (referee)
Introduction: Current findings show that obesity may not only have a protective effect in terms of the osteoporosis development. Although higher mechanical load on bones in obese people increases bone mass density, inflammatory cytokines produced by adipose tissue, on the contrary, increase bone resorption. The reduction of body weight itself can contribute to the deterioration of the quality of bone mass. Aim: The main aim of the study was to evaluate changes in BMD and selected parameters of body composition during a 2-month strict very low-calorie diet (VLCD) and a subsequent 4-month low-calorie diet (LCD) in premenopausal women with obesity. Methods: The study was carried out at the workplaces of the III. Internal Clinic of the General University Hospital in Prague and the Institute of Endocrinology in Prague. Data were collected in the period from April 2021 to May 2023. 11 patients participated in the study with dietary intervention, data was processed from 10 of them. The average age was 44.1 ± 9.3 years, the average weight was 94 ± 10.4 kg. The control group consisted of 14 patients, 10 of them were included in the study. The average age in the control group was 40.7 ± 6.4 years, the average weight was 64.4 ± 7.5 kg. Patients of the intervention group were given a very low-calorie diet with...
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The effect of nutritional intervention in patients with obesity and atrial fibrillation
Buzická, Julie ; Souza Lopes, Kristýna (advisor) ; Havránek, Štěpán (referee)
Introduction: Due to its high and increasing prevalence, obesity is among the most prevalent and one of the most serious risk factors for cardiovascular diseases. It is well established that there is an epidemiological link between obesity and atrial fibrillation and the risk of atrial fibrillation increases with increasing BMI. Studies show that weight reduction combined with antiarrhythmic drug therapy has a good effect in the treatment of atrial fibrillation in some patients. Nutritional intervention is an important part of the treatment of obesity and for this reason this paper focuses on its effect. Objectives: The aim of this theses is to evaluate the effect of individual nutritional intervention using telemedicine in obese patients with atrial fibrillation on the intake of total energy, individual major nutrients and fibre. In addition, the development of body weight and adipose tissue mass over a 6 month period should be evaluated. A secondary objective is to evaluate the exercise intervention based on the number of steps per day. Methods: Data were collected on III. Department of Internal Medicine, Department of Endocrinology and Metabolism, 1st Faculty of Medicine, Charles University and General University Hospital in Prague, in the outpatient clinic of dietitians. The study included...
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