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The Segregation in Ferrous Alloys when Casting Heavy Castings
Pernica, Vítězslav ; Čech, Jan (referee) ; Vodárek, Vlastimil (referee) ; Havlíček,, František (referee) ; Šenberger, Jaroslav (advisor)
This thesis is dedicated to the field of manufacture of heavy steel castings with resulting properties which are influenced by long solidification time. During the long solidification time a segregation process of additives in the steel occurs which results in numerous metallurgical defects. The work was intended to observe the macrosegregation effects in the wall of a heavy experimental steel casting respectively a part of a real superheavy casting intended for cement furnaces (weight 210 t). The steel casting for the research was manufactured in the joint-stock company of VHM where such heavy castings are commonly produced for the market. The supplied piece of the steel casting was cut into the smaller pieces for the better examination. The examination resulted in information about the casting macrostructure and chemical heterogeneity of chosen elements in the casting wall. The heterogeneity of the chosen elements (C, Mn, Si, Cr, S, P) is clearly shown in the worked out visual concentration maps. Based on the experimental data the measured results of segregations were confronted with the results of segregation modelling with the use of the commercial simulation software ProCAST. It resulted in the conclusion that the prediction of segregations is not in accordance with the reality. Furthermore, the results from the experimental casting are shortly compared with previously manufactured castings of the same type and the results summarizing the found range of macrosegregations of the tested sample are interpreted in the work conclusion.
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Acquisition, Modeling and Signal Processing in Ultrasound Perfusion Imaging
Mézl, Martin ; Kozubek, Michal (referee) ; Flusser,, Jan (referee) ; Jiřík, Radovan (advisor)
This work deals with possibilities of ultrasound perfusion analysis for the absolute quantification of perfusion parameters. In the theoretical part of this work are discussed possibilities of using of the ultrasound contrast agents and approaches for the perfusion analysis. New methods for the perfusion analysis are suggested and tested in the practical part of this work. The methods are based on convolutional model in which the concentration of the contrast agent is modeled as aconvolution of the arterial input function and the tissue residual function. The feasibility of these methods for the absolute quantification of perfusion parameters is shown on data from phantom studies, simulations and also preclinical and clinical studies. The software for the whole process of the perfusion analysis was developed for using in hospitals.
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Modelling 3D Forest Structure for Improved Retrieval of Forest Biophysical Properties
Janoutová, Růžena ; Albrechtová,, Jana (referee) ; Štarha, Pavel (referee) ; Martišek, Dalibor (advisor)
Hlavním cílem práce bylo zlepšení kvantitativních odhadů vegetačních parametrů smrkových porostů pomocí spektrálních simulací trojrozměrného modelu přenosu záření. Prvně bylo potřeba vytvořit přesný 3D model smrku. Implementace přesného 3D modelu smrku pro parametrizaci celých lesních porostů je v současné době výpočetně nemožné, bylo tedy nutné tento 3D model smrku zjednodušit. Přesný 3D model smrku společně s dostupnými leteckými daty sloužil pro nalezení optimálního zjednodušení. Optimální model vedl ke kompromisu mezi výpočetní náročností a přesností výsledné odrazivosti z modelu přenosu záření. Následně byl optimální model smrku využit pro odhady vegetačních parametrů ze satelitních snímků. Přesnost odhadů byla ověřena oproti pozemním měřením odhadovaných parametrů. Na závěr byly porovnány výsledky z odhadů vegetačních parametrů pomocí optimálního 3D modelu smrku s výsledky z tradičního přístupu pomocí modelů stromu s geometricky jednodušími tvary korun.
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Analysis of runoff in selected urban watershed
Kučera, Vít ; Máca, Petr (advisor) ; Petr, Petr (referee)
The work deals with schematization area with sewage networks in the Rainfalls-runoff model urbanized watershed modeling and changes in the Manning roughness coefficient of the pipe to the main sewer, which drains most of the wastewater. The comparison was made on two schematization basin Bohnice collector the main sewer F in the city. Prague. For the simulation program was used Mike URBAN DHI Inc.
The main variable was observed outflow hydrograph on the selected sealing profile watershed and its development depending on schematization and change the Manning roughness coefficient.
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Combinatorial Games Theory
Valla, Tomáš ; Nešetřil, Jaroslav (advisor) ; Sgall, Jiří (referee) ; Spirakis, Paul (referee)
Title: Combinatorial Games Theory Author: Tomáš Valla Department / Institute: IUUK MFF UK Supervisor: Prof. RNDr. Jaroslav Nešetřil, DrSc., IUUK MFF UK Abstract: In this thesis we study the complexity that appears when we consider the competitive version of a certain environment or process, using mainly the tools of al- gorithmic game theory, complexity theory, and others. For example, in the Internet environment, one cannot apply any classical graph algorithm on the graph of connected computers, because it usually requires existence of a central authority, that manipu- lates with the graph. We describe a local and distributed game, that in a competitive environment without a central authority simulates the computation of the weighted vertex cover, together with generalisation to hitting set and submodular weight func- tion. We prove that this game always has a Nash equilibrium and each equilibrium yields the same approximation of optimal cover, that is achieved by the best known ap- proximation algorithms. More precisely, the Price of Anarchy of our game is the same as the best known approximation ratio for this problem. All previous results in this field do not have the Price of Anarchy bounded by a constant. Moreover, we include the results in two more fields, related to the complexity of competitive...
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User influence on miniature antennas in mobile applications
Vehovský, Radek ; Polívka,, Milan (referee) ; Pokorný, Michal (advisor)
This master’s thesis deals with user influence on miniature antennas in mobile application. Electrically small antennas including fundamental performance properties and limitations are introduced in the theoretical section of this thesis. This section also deals with microstrip antennas and their common types. The accent is on PIFA antennas, their typical constructions and methods of miniaturization. In the practical section, dual-band PIFA antenna for operation at frequencies of systems GSM900 and GSM1800 is designed with the assistance of electromagnetic field simulator CST Microwave Studio. On this type of antenna, the user influence on impedance matching and radiation pattern in data mode (the user is typing message or browsing with the phone) is investigated. For this purpose the hand phantom, corresponding to author’s right hand, was made from agar based material. For typical position of human hand is designed matching network, which eliminate the user influence and ensure correct function of antenna.
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Valuation of PEBAL s.r.o.
Turza, Vladimír ; Brabenec, Tomáš (advisor) ; Keselý, Ladislav (referee)
The thesis aims to determine the equity value of the company PEBAL s. r. o. as of January 1st 2016. It is not separated into theoretical and practical part, because it is considered as fake appraisal of an expert. That is the reason why the whole thesis is practical with occasional theoretical background explanations. In the first part there is basic information provided about the appraised company along with its characteristics. Then financial analysis is carried out which will provide an overall picture of financial health of the company along with determination of competitors. Followed by strategical analysis which deals with the market as whole and predicts its future development as well as development of sales of the valued company. The next part consists of analysing and predicting value drivers and the overall financial plan. Result of the last part is the valuation itself applying discounted cash flow (DCF) method using discounts rate calculated earlier in the chapter. The final chapter also contains market valuation using method of comparable companies along with Monte Carlo simulation, that provides probability distribution of the value of the company.
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Risk analysis of the company Prestar's business plan
Bartoň, Daniel ; Špička, Jindřich (advisor) ; Vacík, Emil (referee)
The goal of this thesis is to compile a strategic business plan of the company Prestar and to identify and evaluate corresponding risks. A substantial part of the turnover is generated by business activities in Russia which recently exhibits unstable development. Strategic analysis is conducted based on the findings, key risk factors are identified and an estimate of the enterprise value based on discounted cash flow is calculated. Finally the influence of the identified risk factors on the enterprise value is simulated using the Monte Carlo method. The key risk factors include wage growth rate, development of sales generated in Russia and the exchange rate.
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