|
|
Options for increasing the efficiency of small motors.
Kusý, Karel ; Janda, Marcel (referee) ; Hájek, Vítězslav (advisor)
This bachelor thesis concerns itself with the possibilities of achieving higher efficiency of small asynchronous motors and their manufacturing costs. The following chapters describe the design, function and principles of speed regulation of the asynchronous motor. Next, losses that occur during motor operation and ways of reducing them, are described. The last chapter of the thesis addreses factors that influence the manufacturing costs of the asynchornous motor and evaluates the material costs of one modified motor.
|
|
| |
|
|
Metals Transport in the System Soil/Plant. Comparison of the Active and Passive Sampling Method (The Diffusive Gradients in Thin Films Technique)
Trávníčková, Jana ; Janoš, Pavel (referee) ; Chýlková, Jaromíra (referee) ; Čelechovská, Olga (referee) ; Dočekalová, Hana (advisor)
The doctoral thesis deals with comparison between copper uptake by radish (Raphanus sativus L.) and concentration of copper measured by a DGT-device and concentration of copper obtained by extraction with generally used extraction agents (HNO3, NaNO3 and water). Plants were cultivated in pot experiments on a tested non-treated and gradually spiked soil. The amount of copper was determined in various part of radish (whole plant, above- and below-ground part) after mineralization in the APION mineralizer by ET – AAS. The highest concentration was in belowground part, especially in root tissues and sheel of root bulb. It confirms copper is associated with cell walls. The amount of copper taken by radish up does not pass beyond sanitary standards not even in spiked soils and consummation of radish is not unhealthy. Good correlations were found between copper concentration in radish and the amount of copper extracted with HNO3, NaNO3 and water and the amount found in soil solution. Results of extraction with HNO3 confirmed the amount of copper was stable in spiked soils during the pot experiments. The DGT experiments have shown that the rate of resupply from the solid phase to soil solution is constant during the deployment time. Whereas the release of copper decreases after 24 hours in natural soil. Copper added to soil in form of cupric ions is present in the different form after one month-equilibration than copper present in unspiked soils. The results obtained by DGT measurements were approximately up to two orders of magnitude lower than copper concentration obtained by leaching with sodium nitrate. The extraction with sodium nitrate does not provide true reflection of metal availability to plant root system and soil microorganism. High values of correlation coefficients (R2 > 0,9) were found between concentration of copper in radish plant and the concentration of copper in soil solution measured by DGT technique. Concentration of copper in soil solution was three times higher than concentration measured by DGT technique. Soil solution contains species of copper that are not measured by DGT technique and available to plants. Concentration of metals obtained by DGT measurements is more closely to real concentration of bioavailable forms of metal in soil. Therefore it is possible to recommend the DGT technique as a technique for determination of bioavailable forms of copper in soils.
|
|
|
Additional Treatment of Drinking Water at the Point of Consumption
Hrubý, Ladislav ; Biela, Renata (referee) ; Kučera, Tomáš (advisor)
This bachelor’s thesis deals with problem of pollution in drinking water during its transport towards consumers. It particularly deals issues with heavy metals such as lead, copper and sums up methods which can be used when trying to remove such metals at water connections or taps. Next, particular filter materials are described together with processes that happen during filtration. Finally, a short experiment has been performed for finding out the most appropriate filter material.
|
|
|
Determination of hydroxymethylfurfural in honey
Dohnalová, Barbora ; Slavíková, Zuzana (referee) ; Diviš, Pavel (advisor)
Honey is a valuable food of a natural nature that can be subject to adulteration for higher profits. One method of detecting this adulteration may be to determine hydroxymethylfurfural, the formation of which is promoted by heating. The theoretical part of the thesis deals with the types of honey, their origin, and the possibilities of their falsification. HMF, its occurrence and use and methods for its determination are also described. The practical part is devoted to the description of the experiment such as sample preparation, measurement and evaluation. The HPLC (high performance liquid chromatography) method was used to determine HMF in honey, which can be used to determine even very low concentrations. There were five samples for the experiment, four of them directly from the beekeeper and one from the retail chain. All samples were compared for HMF content. The highest concentration of HMF was determined in a sample of commercially available honey. In domestic honeys, the HMF content increased with the age of the honey. The content of HMF in all honeys complied with Decree No. 76/2003 Coll.
|
|
|
Use of pollution indices for evaluation of soil contamination
Čmelíková, Dorota ; Pavlovský, Jiří (referee) ; Doležalová Weissmannová, Helena (advisor)
This thesis focuses on heavy metal contamination of soil and the use of pollution indices for its evaluation. Two regions were selected for assessment and comparison. The chosen heavy metals were mercury, zinc, copper, lead and cadmium. These heavy metals were analysed in 15 samples from Kyjov nad 15 samples from Ostrava. Methods of analysis were AMA-254 and FAAS. The established concentrations were used to calculate pollution indices and for health risk assessment. Pollution in Kyjov was assessed as low to medium without any health risks. Ostrava region was assessed as moderately to highly polluted with a low health risk, especially for children.
|
|
|
Calorimetric study of interactions of humic substances with metal ions
Solná, Irena ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The main object of the diploma thesis is study of interaction beetween humic acids and selected metal ions using calorimetric titration. The research about reactivity of humic substances is done comparing the different models used to describe the variety of properties of humic substances. In experimental part the methods of FT-IR spektrometry, potenciometric and conductometric titration are used to recieve the total acidity and carboxylic acidity of lignite humic acid. The optimalization of isothermic titration calorimetry is done to be used within study of reactivity of humic acids, revealing the best correlation with sols of studied humic acid. The basic organic compounds were used including benzoic acid, ftalic acid, salycilic acid, pyrocatechol and phenol as models of bonding groups in humic acids. The reaction enthalpy was calculated from the titration of models and results were compared with semiempiric quantum chemistry calculations following INDO method.
|
|
|
Study of the effect of myocardial fibrosis on elemental distribution in rat soft tissues using Laser Ablation ICP-MS
Machalová, Martina ; Zlámalová Gargošová, Helena (referee) ; Vašinová Galiová, Michaela (advisor)
The most common cause of death in the Czech Republic continue to be cardiovascular diseases. The field of heart failure therapy still keeps moving forward. Yet myocardial fibrosis is one of the consequences and causes of heart failure for which there exists no effective medical care. The solution would be predicting the advancement of fibrosis and a preventive therapy. Many medical methods are being developed now in this regard, and the element distribution in affected tissue could help them. That is the reason why this work centers on the research of the element distribution in rat hearts with an induced myocardial fibrosis. An influence of sample couloration on the analysis was observed during its course. Special attention was paid to the distribution of iron in the fibrotic tissue as well as to the comparisson of the images of myocardial fibrosis. It seems that the iron distribution specificly could be helpful in recognising a damaged myocardium.
|
|
|
Design of a heating system for an office building
Vítek, Lukáš ; Horká, Lucie (referee) ; Vyhlídalová, Karolína (advisor)
The aim of this bachelor thesis is to design a proposal of space heating and water heating system for an administrative building in Ostrava. The building has four above-ground floors and an underground floor. In the underground floor are located technical building background, stocks and a parking. In the above-ground floors are administrative offices. The heating is solved as a water heating, with a distribution of the heat into the space using panel radiators and convectors. Water heating is solved by an accumulation heater. As a heating energy source serves a cascade gas boilers. We can find in the whole building a forced ventilation. The theoretical part of this thesis deals with the BIM technology.
|
|
|
Leachability of Cu, Ni and Co from alkali-activated matrices
Janíčková, Vlasta ; Kalina, Lukáš (referee) ; Koplík, Jan (advisor)
The work deals with the determination and comparison of leaching of heavy metals from two types of alkali activated systems based on blast furnace slag and high-temperature fly ash. These systems are capable in their structure encapsulate heavy metals, toxic substances or radioactive substances, which can be harmful for the environment. The aim of this work is to prepare a mixture with acceptable mechanical properties. Leachibility from matrix was tested according to ČSN EN 12457–4, followed by analyses Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Structure of matrix was analysed using Scanning electron microscope (SEM).
|
guest ::
