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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Experimentální a teoretické studium využití sondových metod pro diagnostiku plazmatu / Experimental and theoretical study of utilization of probe methods for plasma diagnostics

Peterka, Matěj January 2014 (has links)
The ball-pen probe is a unique probe recently developed at the Institite of Plasma Physics in Prague. It has been designed for direct measurement of plasma potential at the CASTOR tokamak. Nowadays, it is used routinely at several tokamaks in Europe, and the first tests in low-temperature plasma have also already been performed. The aims of the thesis are primarily experimental. A ball-pen probe has been constructed from available materials, which is suitable for systematic measurements of radial profiles in the low-temperature plasma of a cylindrical magnetron. By means of comparison to other diagnostics, it was proved that ball- pen probe is able to directly measure plasma potential in a certain range of plasma parameters even though its current-voltage characteristic is not symmetric, which is in contradiction with the simplified theory for ball-pen probe. Powered by TCPDF (www.tcpdf.org)
82

Experimentální studium využití sondových metod pro diagnostiku nízkoteplotního zamagnetovaného plazmatu / Experimental study of the use of probe methods for diagnostic of low-temperature magnetized plasma

Zanáška, Michal January 2015 (has links)
The ball-pen probe is a relatively new diagnostic method, that has been designed for direct measurement of plasma potential in magnetized plasmas. Nowadays, it is routinely used at several high-temperature plasma devices in Europe and it has been tested also in conditions of low-temperature plasma, which are substantially different from that of high-temperature plasma. The measurements performed so far showed, that ball-pen probe could be used also in low-temperature plasma. However, more measurements were needed to prove the applicability of ball-pen probe. Therefore, the main aim of this work is to compare the method of ball-pen probe with simultaneous measurements using Langmuir and emissive probe. Measurements were performed in DC discharge of cylindrical magnetron at various discharge conditions and radial positions of probes. Powered by TCPDF (www.tcpdf.org)
83

Studium sondových diagnostik okrajového plazmatu v tokamaku pomocí počítačových simulací / Study of probe diagnostics of tokamak edge plasma via computer simulation

Podolník, Aleš January 2019 (has links)
The aim of the thesis is to examine plasma-wall interaction using computer modeling. Tokamak- relevant plasma conditions are simulated using the particle-in-cell model family SPICE working in three or two dimensions. SPICE model was upgraded with a parallel Poisson equation solver and a heat equation solver module. Plasma simulation aimed at synthetic Langmuir probe measurements were performed. First set considered a flush-mounted probe and the effect of variable magnetic field angle was studied with aim to compare existing probe data evaluation techniques and assess their operational space, in which the plasma parameters estimation via fit to the current-voltage characteristic is accurate. Second simulation set studied a protruding probe pin. Effective collecting area of such probe was investigated with intentions of density measurement collection. This area was found to be influenced by a combination of two factors. First, the density dampening inside the magnetic pre-sheath of the probe head, and the second, the extension of the area caused by Larmor rotation. A comparison with experimental results obtained at COMPASS tokamak was was performed, confirming these results. Keywords Langmuir probe, simulation, particle-in-cell, tokamak, Poisson equation, COMPASS 1
84

Diagnostika technologického plazmatu / Diagnostics of plasmas for technological applications

Turek, Zdeněk January 2020 (has links)
The subject of the master thesis is the extension of the measurement of plasma para- meters by the Langmuir probe in a system with a planar magnetron and a hollow cathode operating in pulse mode. The main tasks are to modify the measuring circuit to increase the maximum probe current and to put the USB oscilloscope into operation for data collection with higher resolution and higher sampling rate. Furthermore, the function of the entire device will be verified using test circuits and also by measuring the probe characteristics in discharges in a system with a magnetron and a hollow cathode in both continuous and pulse mode. 1
85

Termodynamická metoda stanovení účinnosti vodního stroje. / Thermodynamic method for assessing hydraulic machine efficiency

Mizera, Ladislav January 2011 (has links)
The master´s thesis contained basic information about the method of thermodynamic efficiency of hydraulic machines. The first part briefly mentioned our opinion on the most widely used method for determining the efficiency of hydraulic machines. Another section of thesis is characterization and measurement procedure using the thermodynamic method. Another section describes measurements of water plants and laboratory measurements, which took place in the past. The final part describes the results of laboratory measurements, which took place in the lab of VUT FSI Brno, and evaluating and comparing the results.
86

Agreagační chování polysacharidů ve vodných roztocích / Aggregation Behaviour of Polysaccharides in Aqueous Solutions

Mravec, Filip January 2008 (has links)
Tato práce je zaměřena na agregační chování nativního a hydrofobně modifikovaného hyaluronanu, v různých molekulových hmotnostech a stupních substituce, ve vodném prostředí. Pro studium bylo vybráno šest fluorescenčních sond s různými vlastnostmi (Pyren; Nilská červeň; Perylen; Akridinová oranž; 6-(p-Toluidino)-2-nafthalenesulfonová kyselina; PRODAN). a výsledky získané pomocí těchto sond byly porovnány s jednoduchým anionaktivním tenzidem (Dodecylsíran sodný). U všech použité sond byly testovány jejich spektrální vlastnosti v závislosti na polaritě okolí a/nebo na koncentraci. Pro stanovení vlastností nepolárního jádra hyaluronového agregátu byly vybrány dvě sondy (Pyren, Nilská červeň). U domén byly sledovány polarita a viskozita vnitřního prostředí a jejich závislost na iontové síle a teplotě. Pro modifikované hyaluronany bylo stanoveno, že jejich kritická agregační koncentrace klesá s rostoucí molekulovou hmotností a stupněm substituce. Pro vlastní doménu platí, že její kompaktnost roste s rostoucí iontovou silou, ale klesá s rostoucí teplotou.
87

Aspectos cinéticos, estructurales y de reactividad de los dianiones de bifenilo y tetrafenileno

Blasco, Inmaculada 22 July 2016 (has links)
En la presente memoria se aborda el estudio de la reactividad de dianiones de hidrocarburos aromáticos policíclicos (HAPs). En el capítulo I se llevó a cabo una síntesis eficaz del fluorometilciclopropano y posterior estudio como sonda de radicales. Se estudió el mecanismo de reacción a través del cual tiene lugar la alquilación de dianiones de HAP (bifenilo y naftaleno) con fluoruros de alquilo primarios, con el fin de elucidar si este mecanismo transcurre vía TE, o si existe competencia con la sustitución nucleófila bimolecular SN2. En el capítulo II se ha conseguido establecer una ruta eficaz para la síntesis asimétrica del 2,7,10,15-tetra-terc-butiltetrafenileno, obteniendo ambos enantiómeros con excelentes excesos enantioméricos. Se ha llevado a cabo un estudio cinético para el cálculo de la energía de racemización del 2,7,10,15-tetra-terc-butiltetrafenileno.
88

Charakterizace nově vyvinutých fluorescenčních sond v buněčných systémech / Characterization of newly developed fluorescence probes in cellular systems

Kadlecová, Julie January 2021 (has links)
Nanoparticles (NP) are currently a progressive area of scientific research. The possibility of synthesizing them according to the required parameters opens up possibilities for their wide use also in biomedicine. One example is a nanoparticle that can detect cellular processes, such as pH. We already know that the pH of healthy and cancer cells differs by the opposite gradient on the intracellular and extracellular side of the membrane. In this context, this work deals with the study of fluorescent silicon nanoparticles (SiNP) tested on a human keratinocyte cell line from a healthy donor (HaCaT) and from skin cancer donor (A431). Once found that even the highest concentrations of SiNP used are not cytotoxic, they can be further studied by fluorescence, confocal and super-resolution microscopy. In order to assess the pH detection properties of these SiNPs, a method for measuring intracellular pH with a fluorescent raciometric probe SNARF-1 using fluorescence spectroscopy and flow cytometry was introduced. Since the pH values of the intracellular environment are closely related to cellular metabolism, the metabolism of A431 and HaCaT cells was characterized and compared. To do this, methods for measuring analog glucose consumption (2-NBDG) and another new method for measuring real-time metabolism...
89

Techniky zavádění nasojejunálních sond / Nasojejunal tube placement techniques

Součková, Veronika January 2013 (has links)
Author's title and name: Bc. Veronika Součková Institute: Charles University, Prague 1. Faculty of medicine Kateřinská 32, 121 08, Prague 2 Study branch: follow-up Master's - intensive care Study programme: specialization in intensive care Title: Nasojejunal tube placement techniques Consultant: MUDr. František Novák, Ph.D. Number of pages: 81 Number of attachments: 3 Number of tables, grafs and pictures: 24 Year of presentation: 2013 Keywords: Nasojejunal tube, placement techniques, enteral nutrition, endoscopy, fluoroscopy, blind bedside technique This dissertation is dedicated to the issue and options in the field of nasojejunal tubes placement technique. Theoretical part aims at the description of methods and procedures of placing the nasojejunal tube and briefly mentions possible complications and principles of enteral nutrition, which is administrated by this method. Empirical part of the dissertation aims at the comparison of placement the nasojejunal tube using the blind bedside technique developed at intensive care unit in General University Hospital in Prague to, endoscopic and fluoroscopic methods. The research brings description and comparison of the most frequently used methods of placement the feeding tube into the small intestine.
90

Snímače proudu / Current sensors

Vaculík, Vlastimil January 2012 (has links)
This diploma theisis deals with the theoretical analysis of the known types of current sensors, including for example, current transformers, shunts, and advanced sensors using Hall sensor or Rogowski coil. Subsequently, the rest of the work deals with the issue of current transducers with Hall sensors, without using a ferromagnetic circuit. For optimal currnet measure and overall precision, several possible options are designed and calculated. This includes number of sensing elements and distribution of sensors around the wires. Based on calaculation of magnetic intensity, related 3D charts ale plotted unsing Excel software. These charts illustrate the theoretical calculations of field distribution around conductors for various number of sensor. In the last part, components ale designed for practical implementation and scheme of electrical wiring. According to this scheme there is PCB designed as well. Whole current meter ir practically build and its results are compared with theoretical assumtions that are discussed in conclusion part of this theisis.

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