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Engineering optimization models
Tydlačka, Martin ; Plšek, Jan (referee) ; Popela, Pavel (advisor)
A cross-section of a girder made out of profile I is designed with respect to random loads, to which a girder will face during life time. Because the random loads are there, we need another aaproach to solving this exercise. Acceptable aproach is usage of optimisation and four choosen models, solving random loads. The cross-section has been to optimize with respect to minimal weight subject the safety constraint. Goal of this thesis is to present method of transfer structural exercise to exercise of mathematical optimisation, present four choosen models and apply this to exercise with random loads.
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Synchrotron Radiation PhotoElectron Studyof CeOx-Pd,Sn,Au Model Catalysts
Škoda, Michal ; Matolín, Vladimír (advisor) ; Čech, Vladimír (referee) ; Plšek, Jan (referee)
The doctoral thesis deals with study of model catalytic systems Ce(Ox)-Pd(111), Sn-CeO2(111) and Au-CeO2(111). The metal-metal and metal-oxide interactions are investigated by means of photoelectron spectroscopy method (PES), first of all resonant photoelectron spectroscopy (RPES). The RPES method showed, that the chemical state modifications of the system induce significant modifications in the band structure of its atoms implicating dramatic valence band changes. The RPES method has appeared to be a powerful instrument for valence band electron structure study.
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Low temperature CO oxidation on bimetallic structures
Hanyš, Petr ; Nehasil, Václav (advisor) ; Janovská, Michaela (referee) ; Plšek, Jan (referee)
Title: Low temperature CO oxidation on bimetallic structures Author: Petr Hanyš Department: Department of Surface and Plasma Science Supervisor: Doc. RNDr. Václav Nehasil, Dr., Department of Surface and Plasma Science Abstract: Bimetallic system Sn-Rh in the form of the model Sn/Rh(111) system, supported Rh+Sn/Al2O3 and Rh/SnO2 clusters and Rh/SnO2 and Rh+Sn/Al2O3 powder samples was studied using synchrotron radiation photoelectron spectroscopy (SRPES), X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS), molecular beams (MB), transmission and scanning electron microscopy (TEM, SEM), powder X-ray diffraction (XRD) and high pressure reactor within the framework of the study. It was found that formation of Sn-Rh alloy influences catalytic properties of Rh by lowering CO adsorption energy and capacity. It was also found that presence of Rh in this bimetallic system mediates reversible oxidation/reduction of Sn/SnO2, whereas Sn oxide acts as an oxygen reservoir for low temperature CO oxidation. Keywords: bimetallic systems, rhodium, tin, low temperature CO oxidation
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Preparation and characterization of nanostructures for catalysis and gas detection
Haviar, Stanislav ; Matolínová, Iva (advisor) ; Zahoran, Miroslav (referee) ; Plšek, Jan (referee)
First part of this thesis is focused on magnetron sputtering deposited layers of cerium oxide using carbonaceous substrates. Micrographs from scanning and transmission electron microscopes reveal that cerium oxide layers exhibit remarkable roughness and nano-porosity. In this work there are presented optimized key preparation parameters for growth of highly nano-porous layers of cerium oxide on amorphous graphite as well as on graphite foil. The effect of residual atmosphere during the magnetron sputtering deposition is discussed. Results of deposition using oxygen/argon mixture as working gas are presented. A simple growth model is formulated and discussed. Second part deals with utilization of cerium and tungsten oxides as conductometric gas sensors. A testing station was constructed for gathering sensorial properties of such devices. The construction and abilities of the measuring system designed by the author are noted. Preliminary results of measurements of response to hydrogen are presented. Cerium oxide layers suprisingly exhibit measurable response to hydrogen gas. Tungsten oxide nanowires grown on mica substrate were formed into gas sensor via electron beam lithography and show high sensitivity. Powered by TCPDF (www.tcpdf.org)
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Controllable synthesis, treatment and characterization of anodes for Direct Formic Acid Fuell Cell
Bieloshapka, Igor ; Jiříček, Petr (advisor) ; Khalakhan, Ivan (referee) ; Plšek, Jan (referee)
Title: Controllable synthesis, treatment, and characterization of anodes for Direct Formic Acid Fuel Cell Author: Igor Bieloshapka Department: Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Ing. Petr Jiříček, CSc., Institute of Physics of the Czech Academy of Sciences, Division of Solid State Physics, Department of Optical Materials Abstract: This doctoral thesis concerns the preparation of anodes with Pd-based catalysts. Anodes were deposited on a support surface with magnetron sputtering. The prepared samples were tested in a direct formic acid fuel cell (DFAFC) station. Polyaniline, graphene oxide (GO) and reduced graphene oxide (RGO) have been additionally investigated as promising support material for polymer membrane fuel cells (FCs). A scanning electron microscope (SEM) and a transmission electron microscope (TEM) were used to observe the morphological differences between the prepared samples. Elemental composition and chemical states on the anode part were studied through X-ray photoelectron spectroscopy (XPS). The results show that the power density of the prepared anodes with 3 nm of palladium thickness is lower only by 30% in comparison with chemically prepared catalysts. The highest power density results were achieved for the...
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Analýza rizik v softwarových projektech
Plšek, Jan
Plšek, J. Risk Analysis in Software Projects. Diploma thesis. Brno, 2020. This diploma thesis deals with the design and implementation of a web application whose aim is to try to make small start-ups available for risk analysis for their IT projects. Users must first register and then check their current status after identifying potential risks.
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Interaction of organic molecules with metal passivated semiconductor surfaces studied via STM
Zimmermann, Petr ; Sobotík, Pavel (advisor) ; Plšek, Jan (referee) ; Šikola, Tomáš (referee)
Title Interaction of Organic Molecules with Metal Passivated Silicon Surfaces Studied via STM Author Petr Zimmermann Department Department of Plasma and Surface Science Supervisor Doc. RNDr. Pavel Sobotík, CSc. Department of Plasma and Surface Science Abstract Organic molecules offer a wide range of optical, electronic or chemical properties. Coupling them to silicon could pave way to novel applications and devices, however, a controlled molecular functionalization of silicon remains challenging due to the presence of highly reactive dangling bonds on its surfaces. We attempt to decrease the reactivity of low index silicon surfaces with an ultra-thin layer of a metal adsorbates and study their interaction with organic molecules via scanning tunnelling microscopy. In the first part we investigate the interaction of ethylene, a small unsaturated molecule, with tin and indium 1D chains grown on Si(001) - 2 × 1. The chains consist of dimers structurally analogous to the dimers of the underlying Si(001) - 2 × 1 surface. Aided by photoelectron spectroscopy we find that the Sn chains are less reactive than the Si(001) surface and that the absence of a π dimer bond renders indium chains inert. In the second part we study the interaction of copper phthalocyanine, a small macrocyclic heteroaromatic compound, with the...
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Analysis of logistic processes in CSI – DISTRI s.r.o.
Štěpánský, Jan ; Vinš, Marek (advisor) ; Plšek, Jan (referee)
The bachelor´s thesis focuses on analysis of logistic processes in CSI DISTRI s.r.o., which is provider of logistic services for the Swiss brand of sports clothing called Compressport Int. SA. The aim of this thesis is to analyse process chain in the company by the method SIPOC together with the evaluation of potential faults during set processes by the analytic method FMEA. The output of this thesis is rate of failure for the defects which are founded together with suggested arrangements which would eliminate defects during logistic processes chain inside the company. The results of this thesis are evaluation of set logistic process with the suggestion for their improvement. This thesis would be suitable as suggestion for more efficient internal logistic processes which should lead to more satisfied customers.
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Studium fyzikálně-chemických vlastností povrchově modifikovaného oxidu wolframu
Polášek, Jan ; Mašek, Karel (advisor) ; Novák, Stanislav (referee) ; Plšek, Jan (referee)
This work can be divided into two parts. In the first part, we examine possibilities of preparation of monocrystalline tungsten and tungsten oxide nanoclusters by means of magnetron sputtering with gas aggregation. Clusters are prepared in the non-reactive (Ar) and reactive (Ar + O2) atmosphere and heated after the deposition or during the flight by IR radiation. Influence of oxygen in the aggre- gation process was described and possibilities of generating crystalline tungsten and tungsten oxide clusters were found. In the second part, we study reactivity of tungsten oxide layers, pure and doped with rare metals (Pt, Au), deposited on the silicon wafer and etched carbon, towards partial methanol oxidation. Influence of carbon substrate and metal doppants on reactivity was found and described, along with mofrological and chemical changes that occurs in the sample during the proces. 1
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Study of dependence of the metal-oxide electron structure on the reactivity of these systems
Ševčíková, Klára ; Nehasil, Václav (advisor) ; Jiříček, Petr (referee) ; Plšek, Jan (referee)
The presented thesis focuses on studying the interaction between rhodium and cerium oxide and its impact on the reactivity. We investigated two different systems, Rh/CeOx and Rh-CeOx, by means of the photoelectron spectroscopy and the temperature programmed reactions. Rh/CeOx stands for rhodium nanoparticles supported by cerium oxide thin film. We show that there is an electronic metal-substrate interaction between rhodium and cerium oxide. The type of the interaction depends on a degree of cerium oxide reduction and it has a tremendous impact on the reactivity of the system. On the other hand, Rh-CeOx represents cerium oxide thin films doped by rhodium. We characterized the properties of the films with various concentration of rhodium. We show that the morphology, chemical composition and reactivity of the samples strongly depend on the concentration of the rhodium dopant. Powered by TCPDF (www.tcpdf.org)
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