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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.
211

Korelativní tomografie / Correlative tomography

Vařeka, Karel January 2021 (has links)
Předložená diplomová práce se zabývá korelativním přístupem multimodální analýzy struktur prokovování s různým rozlišením. Výzkum je součástí mezinárodního projektu týkajícího se charakterizace poruch zmíněných struktur, které jsou implementovány v polovodičových zařízeních. Kombinace korelativní mikroskopie a tomografie technikami NanoXCT, FIB-SEM (EDS), FIB-SIMS a AFM byla navržena k zavedení opakovatelného pracovního postupu. Tomografie fokusovaným iontovým svazkem je metoda přesného odprašování v řezech, která mimo jiné v každém průřezu získává cenné snímky s vysokým rozlišením (FIB-SEM) nebo mapy chemického složení (FIB-SIMS). Následující transformace obrazu umožňuje identifikaci defektů jako funkci hloubky ve struktuře. Práce dále věnuje pozornost metodám sjednocení obrazů za účelem optimální prezentace získaných dat.
212

Fosfátová pojiva / Phosphate binders

Kalina, Lukáš January 2008 (has links)
The work deals with the preparation and study of polyphosphate composites. Aluminum phosphates provide some unusual properties like high-heat resistance in terms of inorganic binders. The addition of chromium in the form of Cr2O3 or directly the bond with the aluminum-chromium-phosphate can improve the properties of this binder. Highly viscous Al2Cr(H2PO4)9 and Al3Cr(H2PO4)12 binders were prepared by dissolving Al(OH)3 and CrO3 in 85% phosphoric acid, and mixed with Al2O3 and Cr2O3 fillers. The composites were cured in the furnace at 150 °C for 24 h under pressure of 10 MPa. During the annealing at temperatures up to 1 500 °C changes in chemical structure of the cured composites were observed, leading to the understanding of the creation of crystalline phases and their eventual changes. The characterization of binders was mainly based on FT-IR, EDAX, TG-DTA and optical microscopy analyses.
213

Redukce korozních vrstev na mosazi pomocí vodíkového plazmatu / Reduction of brass corrosion layers using hydrogen plasma

Řádková, Lucie January 2011 (has links)
The main topic of this Diploma thesis is the application of low-pressure low-temperature hydrogen plasma for the treatment model samples of rusted brass. Plasmachemical treatment of metallic artifacts is a relatively new way how to remove corrosion of artifacts. The temperature of an object should not exceed 150 °C during the treatment. Corrosion layers were prepared in an ammoniac corrosion atmosphere. The corrosion formation took two weeks. Energy Dispersive X-ray Microanalysis has shown that the corrosion layer was formed by carbon, oxygen, copper, zinc, and lead. The corrosion layers were blue-colored with white crystals on the surface. Except those two colors, brown color was observed on corrosion layers, too. The plasma reactor was a quartz tube with outer copper electrodes and supplied by the RF source of 13.54 MHz. The reactive atomic hydrogen was formed in plasma discharge. This atomic hydrogen reacted with the corrosive layer containing oxygen. This reaction created an unstable OH radical, which emitted light in the region of 305–320 nm. This radiation was detected by the optical emission spectroscopy and it was applied as process monitoring quantity. Rotational temperature and intensity of OH radicals were determined from obtained data. The sample temperature was measured by thermocouple installed inside the sample volume. Rusted samples were treated by low-pressure low-temperature hydrogen plasma. 16 samples were treated at different conditions – plasma power was 100 W, 200 W, 300 W, and 400 W at continuous mode and pulse mode with duty cycle of 25 %, 50 %, and 75 %. The pressure was between 140–160 Pa at hydrogen flow rate of 50 sccm. Samples after plasmachemical treatment were grey colored with white crystals on their surface. Corrosion layers were removed by spatula. The corrosion layers of some samples were easy removable, some others were difficult. Energy Dispersive X-ray Microanalysis, which was carried out after the treatment of 2 selected samples (400 W, 50% pulse mode and 400 W, 75% pulse mode), showed different amounts of carbon, oxygen, copper, zinc, and lead compared to the rusted sample. Other elements in the treated layer were silicon, sulfur, chlorine, and fluorine.
214

Redukce korozních vrstev na bronzu pomocí vodíkového plazmatu / Reduction of bronze corrosion layers using hydrogen plasma

Miková, Petra January 2011 (has links)
This diploma thesis is focused to the plasma chemical reduction of model corrosion layers prepared on bronze samples. Bronze was the main material for production of the subjects in Bronze Age. First, it was very rare, and therefore was used only for making jewellery and other decorative subjects. Later, the objects of daily use and weapons were produced of bronze. These objects are found and it is necessary to restore him and preserve the cultural heritage for future generations. The research and the optimalization of plasmochemical reduction of model corrosion layers on bronze samples contributes to this. A metallographic grinder was used to create a defined surface, first with the sandpaper P 280 and then after sample 90 degree rotation with the sandpaper P 600. This ensured uniform surface at all bronze samples that is necessary to provide the same corrosion conditions. The grinded samples were washed by ethanol and dried by hot air stream. To prevent contact with the surrounding atmosphere and successive initiation of corrosion, the samples were stored in lockable polyethylene bags. This step was followed by the preparation of model corrosion layers. Hydrochloric and sulfuric acids were chosen as corrosive environments. Petri dish containing 20 ml of the selected acid was placed at the bottom of the desiccator. Samples were placed to the ceramic grate, over the dish, and they were corroded (in vapours of hydrochloric acid for 34 days and in vapours of sulfuric acid for 27 days). The corroded samples were treated using low-pressure hydrogen plasma excited by RF generator. Treatment of samples was carried out in quartz cylindrical reactor (length of 90 cm, inner diameter 9.5 cm) with copper electrodes placed outside. The pressure in the reactor was ranged around 160 Pa at hydrogen flow rate of 50 sccm during the experiments. The continuous and pulse modes (duty cycle of 25%, 50% or 75%) at peak power of 50–300 watts were used for the treatment of 90 minutes duration. The plasma treatment was monitored by optical emission spectroscopy of OH radical using compact Ocean Optics HR4000 spectrometer. Its integral intensity is proportional to the corrosion layer removal. The rotational temperatures of plasma were calculated using selected OH rotational lines, too. The sample temperature during the treatment was measured by thermocouple installed inside the additional non-corroded samples. The reduction of corrosion layer is successful when the maximum of relative intensity of OH radicals is produced and follow gradual decline. The samples which corroded in vapours of sulphuric acid and were treated in pulse modes with duty cycle of 25 % or with delivered power of 50 W has produced no maximum. To the remain samples the maximum although were observed, but reduced corrosion products on the surface were very cohesive. The maximum of relative intensity of OH radicals was observed at all samples corroded in vapours of hydrochloric acid. But there is problem with temperature of sample during experiment. The samples which layer of corrosion product was after experiment incoherent produced the layer of deposit tin. This effect formation at a higher temperature of sample during experiment and therefore with greater deliver energy.
215

Experimentální stanovení hloubky ostrosti optických systémů / Experimental depth of field determination of optical imaging systems

Kubáček, Svatopluk January 2013 (has links)
The aim of this work is to introduce the principle of scanning in optical microscopy. This thesis deals with problem of parameters of display process and their influence on the results and measurements of these parameters. In detail there is analyzed the depth of field of the optical system and there are established some possibilities of theoretical and experimental determination. Part of this thesis is the realization of the measurement work place and program providing experimental depth of field based on different measurement methods. The conclusion is devoted to the practical part, which has the task to monitor settings and optical systems and their impact on depth of field.
216

Zpracování signálů z moderních mikroskopů pro lokální charakterizaci materiálů / Processing of modern microscope signals for local material characterization

Kaspar, Pavel January 2013 (has links)
Signal processing from modern microscopes for local characteristics of materials Image processing is more and more important for the advancement of image evaluation taken from microscopes. This thesis engages the problem of artefact detection and removal from images taken by electron microscope, more accurately by low energy electron microscopy (LEEM). It then offers a possible course of processing such images by edge detection and its theoretical use. These operations are all made in MatLAB language.
217

Softwarové řešení systému FLIM s využitím pulsního laditelného laseru v konfokální mikroskopii / Software FLIM system with pulse white light laser in confocal microscopy

Grund, Pavel January 2015 (has links)
The theoretical part of this master's thesis is focused on research of confocal microscopy and FLIM method. There are a principles and types of confocal microscopy and the use of broad-spectrum laser as a basic light source of these microscopes. It gives what the FLIM method and its use not only in cell biology. The practical part thesis includes the acquisition of three sets of fluorescence intensity images with use of applications tunable pulsed laser, function TimeGate and detection of hybrid detectors. For practical elaboration of this thesis is in the software Fiji created a plugin, which is the source code in the Java programming language. The types of plugins and their uses are described in the third chapter of the thesis. This plugin including the graphical user interface in the form of the dialog box, proceses the fluorescence intensity images and creates a graphical representation of data showing the fluorescence lifetime, so called pseudocolor map.
218

Numerické metody zpracování obrazů z mikroskopu s rotujícím kondenzorem. / Numerical image processing methods for rotating condenser microscope images processing

Týč, Matěj January 2008 (has links)
Tato práce popisuje vznik obrazu v transmisním světelném mikroskopu s proměnnou aperturou kondenzoru. Tento způsob pořizování obrazu je výhodný při pozorování tlustých vzorků, což jsou objekty, u kterých je v mikroskopickém měřítku významná výška. Klasické transmisní mikroskopy pro tento výzkum vhodné nejsou, protože výsledný obraz, který produkují, obsahuje patrné informace z velkého objemu vzorku mimo oblast, která je vyšetřovaná. Tento problém byl vyřešen po vynálezu konfokálního mikroskopu, který je ovšem daleko dražší a má i některé nevýhody navíc. Cílem je zpracovat obrazy pořízené pomocí kondenzoru s rotující aperturou tak, aby došlo k redukci podílu nežádoucí informace a obraz se tak stal "čistším". Tato metoda zpracování obrazu nemohla být použita v minulosti, protože tehdejší počítače neměly dostatečnou paměť a výkon. Na tuto metodu se dá nahlížet jako na převod množiny výstupů z mikroskopu s vylepšenou osvětlovací soustavou na odpovídající množinu výstupů konfokálního mikroskopu.
219

Automatizace metody měření povrchových struktur reflexním digitálním holografickým mikroskopem. / Automatization of method of surface structure measurement by means of reflection mode digital holographic microscope.

Vacula, Daniel January 2010 (has links)
Reflected-light digital holographic microscope developed at IPE FME BUT uses off-axis holography principle and low spatial and temporal coherence illumination. Microscope allows reconstruction of the image amplitude and the image phase, which can be handled in real time. The only limiting factors are imaging speed of the detector and computer performance when processing holograms. Reconstruction of image phase and amplitude allows high-resolution profilometric measurements in the vertical axis direction. This thesis deals with the automatization of profilometric measurement method proposed in [2]. Proposed method uses the combination of the image phase and the image amplitude for the measurement of specimens with surface structure the vertical size of which cause the uncertainty of the image phase by a factor of 2pí. Futher the thesis deals with the construction design of the illumination system of the microscope and its realization together with experimental verification of functionality of proposed method automatization.
220

Design elektronového mikroskopu / Design of electron microscope

Havlíček, Petr January 2011 (has links)
The aim of my Master's thesis is the design of a scanning electron microscope. The designed concept presents an innovative approach to the problems and respects all technical, ergonomic and aesthetical demands made on it. The main creative part of design process starting from the concept development and ending up with the final solution is preceded by a background research study including a historical, technical and design analysis of the electron microscope. The conclusion of my Master's thesis analyses the final design, its character and its contribution in broader context.

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