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Spectroscopic analysis of an electric arc
Hartman, Tadeáš ; Kloc, Petr (referee) ; Šimek, David (advisor)
The bachelor thesis deals with spectroscopic diagnostics of electric arcs. The first part explains the creation and properties of electric discharges, especially electric arcs. Methods for composition and temperature analysis of electric arcs are also given there. The next part deals with practical use of these methods for identification of elements contained in electrodes between which an arc discharge was happening, measurement of the arc temperature and also measurement of the temperature of the electrodes. In the last part, these methods are also used for the analysis of time progression of composition and temperature of an electric arc created on a contactor's contacts with the resistive load.
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Generation of nanoparticles by electrical discharge in liquids
Čechová, Ludmila ; Horák, Jakub (referee) ; Kozáková, Zdenka (advisor)
This thesis focuses on the process of nanoparticle generation by electric discharge in liquids. The theoretical part is focused on generation of electric discharge in liquids, various methods of preparation of nanoparticles, including plasmachemical methods and methods of nanoparticle characterization. The experimental part deals with the preparation of silver nanoparticles. As a precursor for generation of nanoparticles by electric discharge, an aqueous solution of silver nitrate was used. The influence of experimental conditions, such as the influence of voltage polarity, influence of delivered power, effect of concentration, effect of added electrolyte and time course of nanoparticle formation were studied. All samples were analyzed by UV-VIS spectrometry. To confirm the presence of nanoparticles in the solution, one of the samples was analyzed by a scanning electron microscope with an energy dispersion spectrometer for elemental analysis. Plasma diagnostics was performed using optical emission spectroscopy.
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Possibilities of clinical use single and tandem shock waves.
Zeman, Jan ; Beneš, Jiří (advisor) ; Kneppo, Peter (referee) ; Bolek, Lukáš (referee)
Shock waves have been used in medicine for more than 30 year. At the beginning was mainly use for lithotripsy, but today is also applied in other fields of medicine, such as orthopedics, rheumatology and others. Single shock wave is one shock that usually is repeated every 1-1.5 seconds. By contrast tandem shock waves are two shocks consecutively (ideal interval between shocks is from 8 to 15 microseconds), that are repeated. In this work we investigated the clinical use of single and tandem shock waves that are generated entirely new source. It is based on the principle of multichannel discharge. It was found that a single shock wave can destroy the union between bone and bone cement, this effect could be used in orthopedics. Single and tandem shock wave can damage the tumor in vivo, but the principle damage is different. Tandem shockwave is able to cause damage in a depth of acoustically homogeneous medium and enhances the effect of chemotherapy. It would therefore be possible to used single and tandem shock waves in oncology either alone, or their combination with other chemicals. Functional sample of clinically usable applicator of shock waves with a new source was made for these applications. Powered by TCPDF (www.tcpdf.org)
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Plasma speaker - audio modulated electric arc
Klein, Ondřej ; Červinka, Dalibor (referee) ; Martiš, Jan (advisor)
The bachelor thesis deals with design and realization of electric arc modulated by audio signal. It is also known as plasma speaker. Absence of any mechanical components gives membranless speaker no frequency limitation. The design consist of single circuits as power sources for power and control section, control electronics, which modulates the signal, and power section, which reproduce signal in form of sound.
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Arc optical diagnostics
Čermák, Jiří ; Valenta, Jiří (referee) ; Dohnal, Petr (advisor)
The aim of this bachelor thesis is to sort out the individual types of electric discharges, explain the ionization inside the plazma of the electric arc and the elucidation of the energetic balance inside the plazma. The electric arc is an undesirable and hardly predictable phenomenon occurring in switching devices during switching on and switching off the electric circuit. Some older methods of image processing obtained by a high-speed camera are also mentioned. Based on the images obtained from the camera, it is possible to make an equidensity or an equidensitogram that is used to monitor the arc in a quenching chamber. The second part includes the description of an experiment performed in a laboratory and the description of the high-speed camera used during this experiment. A modern method of the image processing using software Matlab is also described. An equidensitogram showing different levels of radioation was made in Matlab from the obtained images.
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Electrical characteristics of gliding discharge for VOC decomposition
Jeřábek, Martin ; Sysel, Petr (referee) ; Bartlová, Milada (advisor)
The subject of this bachelor's thesis was to get familiar with the characteristics of plasma, its divisinon and diagnostics. In physics and chemismy plasma is considered to be, an ionized gas composed of ions, electrons (and possibly neutral atoms and molecules), which is produced by detachement of electrons from the atomic shell, or by dissociation and ionization of molecules. The plasma is often referred as the fourth state of matter. Attention was given to the description of various types of electric discharge, its characteristics and occurrence. One of the most idey known electrical discharges occurring in nature is lightning, a spark discharge, which occurs in the storm. Lightning is an electric discharge between centres of positive and negative charge of one or more clouds, between cloud and earth, or rarely between the cloud and the stratosphere. The greatest attention is paid mainly to gliding electric arc discharge, called Glide-Arc; it is a representative of on-thermal plasma formed by weakly ionized gas. It has many industrial applications, especially for its high energy efficiency, specific productivity and high selectivity of chemical reactions. Under low and atmospheric pressure, Glide-Arc represents a simple and non-expensive way of non-thermal plasma generation. The discharge is excited between two electrodes of different materials in the pressure range from very low pressures up to the pressures of the order of units of MPa. The gliding arc system consist of horn-gaps electrodes diverging in the direction of the working gas flow. After the application of DC or AC voltage, a breakdown occurs at the smallest distance between the electrodes, and a spark plasma channel drifts (“glides“) in the direction of the flowing gas. The final experimental part deals with the measurement of VA characteristics and oscillation characteristics of the current, and with the determinativ of gliding arc ignitron for selected of nitrogen and methane gases at various flow rates. The values of ignition voltage for variol mixtures of gases have been compared. Furthermore, the properties various combinations of gases at different gas flow rates have been evaluated. Measurements were carried out in the plasma laboratory of the Faculty of Chemistry BUT in the plasma reactor at the atmospheric pressure.
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Study of electrical stress of slot insulations
Jabůrek, Ladislav ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This bachelor works deals with electrical effort problems of dielectric materials. The general aim is study of impact alternating electric field of great effort on slot insulation Nomex-Kapton-Nomex. Measurement of loss is realised by dielectric relaxation spectroscopy in frequency domain method. The another aim is apprise of electrical aeging, its causes and incidence on materials. Works deals below dielectric relaxation spectroscopy in time domain and frequency domain, fundamental effect in dielectric and measurement values coherent with electrical aeging.
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Influence of Change in Frequency of the Supply Current to the Operational Parameters of the Discharge Light Sources
Kuptsov, Alexander ; Škoda, Jan (referee) ; Krbal, Michal (advisor)
The master’s thesis is devoted to exploiting of gas-discharge lamps and their dependence on frequency of the supply current. The first part describes the theory of discharge, its types and properties, terms of its origin, and ways of its exploitation. The second part concerns electrical ballast systems of gas discharge light sources, inductive (reactive) and electronic ballasts, principles of their functioning, advantages and disadvantages, and the comparison of their properties. The following chapters deal with low-pressure and high-pressure gas-discharged lamps, compare their properties and describe exploitation of fluorescent lamps. Before conducting laboratory experiments the influence of frequency of the supply current on different properties of gas-discharge lamps was described. Besides, simulation of basic electric parameters of high-pressure gas-discharged lamps was implemented in the program SIMULINK/MATLAB. As a result, the received graphs show the dependence of current, voltage and electric power on time. Another simulation included building of dynamic current-voltage characteristics at various frequencies of the supply current. Preparations for the laboratory experiment and the experiment itself were implemented. Compact and tube low-pressure fluorescent lamps were measured. The received graphs show the influence of change in frequency of the current on the operational parameters of the discharge light sources.
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Influence of Change in Frequency of the Supply Current to the Operational Parameters of the Discharge Light Sources
Kuptsov, Alexander ; Škoda, Jan (referee) ; Krbal, Michal (advisor)
The master’s thesis is devoted to exploiting of gas-discharge lamps and their dependence on frequency of the supply current. The first part describes the theory of discharge, its types and properties, terms of its origin, and ways of its exploitation. The second part concerns electrical ballast systems of gas discharge light sources, inductive (reactive) and electronic ballasts, principles of their functioning, advantages and disadvantages, and the comparison of their properties. The following chapters deal with low-pressure and high-pressure gas-discharged lamps, compare their properties and describe exploitation of fluorescent lamps. Before conducting the experiment we have described the influence of frequency of the supply current on fluorescent tube lamps. Preparations for laboratory measuring have been also implemented. During the experiment the two types of lamps have been analyzed, the results of the research are summed up in the conclusion.
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Utilization of electrodischarge machining technology
Dlabaja, Zdeněk ; Mouralová, Kateřina (referee) ; Osička, Karel (advisor)
Electrical discharge machining (EDM) is quite simple but very effective method for machining of materials. This method has an irreplaceable place in modern engineering. The technology of the EDM is theoretically described in this work. The aim of this work was to judge the advantages and disadvantages of this technology, and its application in a tool company Brenas, Ltd. A component typical for production using EDM was chosen for this judgement. The shape complicatedness and necessary dimensional and surface quality can be clearly seen in this component.
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