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Finding Weaknesses of Hyperscan
Hrabovský, Jiří ; Vojnar, Tomáš (referee) ; Síč, Juraj (advisor)
Cilem této bakalářské práce je vysvětlit, jak funguje open source vyhledávač regulárních výrazů Hyperscan, a poskytnutí přehledu algoritmů, které interně používá. Druhým cílem je pomocí experimentů zjistit, jak moc lze ovlivnit výkon Hyperscanu skenovaným textem. Na základě zdrojového kódu a článků od autorů Hyperscanu je v kapitole 3 vysvětleno, jak Hyperscan vyhledává regulární výrazy v textu a v kapitole 4 jsou vysvětleny implementace konečných automatů používaných Hyperscanem. Různé způsoby zpomalení vyhledávačů regulárních výrazů jsou zhodnoceny a je zvolena metoda, která je založena na fungování jedné z implementací konečných automatů používaných v Hyperscanu. Na základě zvolené metody je implementován generátor, který pro vybraný výraz vygeneruje text, jehož skenování by mělo Hyperscanu zabrat výrazně déle než u normálního textu. Provedené benchmarky ukázaly, že pro některé regulární výrazy způsobil generovaný text v porovnání vůči náhodnému textu výrazné prodloužení vyhledávání Hyperscanem. U nejvíce ovlivněného regulárního výrazu trvalo skenování generovaného textu více než 8000krát déle než skenování náhodného textu.
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Quantification of Hydraulic Descaling Mechanisms
Hrabovský, Jozef ; Toman,, Zdeněk (referee) ; Dobeš, Ferdinand (referee) ; Horský, Jaroslav (advisor)
The issue of descaling is an important part of the forging and heat treatment of steel and semi products of steel production. Rising of new information and study of this process can increase efficiency and improve the surface quality after descaling. This thesis is focused on the mechanisms of the high pressure hydraulic descaling qualification and study of the chemical compounds of which the scales grown. To achieve all goals of this work and to get a comprehensive view of descaling process, few experimental measurements and numerical analyses were performed. All experimental measurements were focused on obtaining data about fundamental parameters and effects of the hydraulic descaling. The data obtained from measurements were applied to numerical analyses, which aimed to discover a deeper relation and to confirm the experimental results. This thesis can be divided into two main parts. The first part is devoted to parameters of the water jet study. The main studied characteristics of the high pressure hydraulic water jet were heat transfer coefficient and impact pressure at different modes such as standard or pulsating water jet. Experimentally measured data of these parameters were applied in numerical analyses. The numerical analyses were focused on studying the impact of the water jet parameters on the stresses in the oxide scale layers. A further water jet analysis was focused on the influence of the individual parts of the hydraulic system (such as water chamber or stabilizer) on its characteristics. In this part different types of the water chambers in combination with different types of stabilizers on the impact pressure values were investigated. These measurements were supported by fluid flow analysis through the hydraulic system. The second part of this work was focused on getting mechanical properties of the oxide scales from specimens prepared from standard structural steel and specimens from silicon steel. In this thesis, the influence of various parameters and characteristics was studied on these two types of steel. Mechanical properties of oxide scale structures were carried out by the Small Punch Test method. To obtain the fundamental mechanical properties such as Young´s modulus, yield strength and ultimate strength, material parameters based on the measured data were optimized. The whole work was carried out in order to get valuable and comprehensive results about high pressure hydraulic descaling process and influencing factors as well as about oxide scales themselves.
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Materials for biodegradable bones based on Fe
Hrabovský, Jan ; Vondrák, Jiří (referee) ; Sedlaříková, Marie (advisor)
The thesis deals with biodegradable bone implants which must have good mechanical properties and also good compatibility with the human body. The thesis contains literary research in the area of bone physiology, biogenic materials and implants for the human body. The thesis focues on the selection of suitable materials for biogenic implants. It is also described the preparation of iron powder mixtures and application onto selected materials. The selected samples were subjected to thermal analysis.
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High Voltage Switchgear Thermal Distribution Analysis
Bílek, Tomáš ; Rudolf, Pavel (referee) ; Hrabovský, Jozef (advisor)
Cílem této práce je analýza teplotního pole vysokonapěťového rozvaděče. Tato analýza je založena na kombinaci experimentálního měření a CFD simulace proudění vzduchu v prostoru rozvaděče. Na základě výsledků pro referenční geometrii jsou předloženy návrhy na úpravu topologie rozvaděče, které mají za cíl snížení teploty kritických komponent rozvaděče během jeho provozu. Druhá část práce je spojena s problematikou oteplení plošných spojů, jakožto hlavních zdrojů tepla v prostoru rozvaděče. Pro popis závislosti oteplení plošného spoje na jeho charakteru byla použita statistická metoda design experimentu. Výsledky z experimentálního měření jsou podpořeny konečně prvkovým modelem kontaktu spoje.
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Water cooling intensity prediction for given thickness of oxide layer
Haluza, Vít ; Hrabovský, Jozef (referee) ; Pohanka, Michal (advisor)
This diploma thesis is dealing with the impact of oxide scales on heat conduction. One of the main tools that were used are numerical simulations. Heat conduction is modelled by solving partial differential equations. Regression models and artificial neural networks are used for the prediction of the influence of oxides on cooling intensity. Determination of the conditions when the cooling was intensified and comparison of individual methods of prediction are the main results of the thesis.
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Biodegradable bones implants based on iron
Hrabovský, Jan ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This work deals with a current topic, which are biodegradable bone implants. These implants seem to be a suitable candidate for temporary fixations, with their gradual decomposition. An important parameter is not only the mechanical properties so that the material can withstand the load, but above all the corrosion properties and the degradation process. This work introduces the physiology of bone, trace elements and also describes current trends in the field of implants. The last part is a theoretical introduction to cross-stage processes. The practical part is focused on the preparation of iron-based samples with various dopants, subsequent annealing and analysis.
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Experimental and Numerical Assessment of the Heat Transfer Coeficients for Industrial Steam Turbine for Siemens Industrial Turbomachinery
Hladík, Petr ; Pospíšil, Jiří (referee) ; Hrabovský, Jozef (advisor)
The subject of this diploma thesis is experimental and numerical assessment of the heat transfer coefficients during condensation of water steam in simplified parts of an industrial steam turbine. This simplified part is a pipe with circular cross section, which is often used in simulations of processes inside the steam turbine. The first part of thesis describes theoretical basics of heat transfer during conduction, convection and condensation. The content of other chapters is description of methods used to determine heat transfer coefficient. These are: ex-perimental analysis performed on a measuring device and evaluated using finite element ana-lysis (FEA), computational fluid dynamics analysis (CFD) in ANSYS CFX and analytical calculations of heat transfer coefficients using mathematical models for condensation. Thesis is concluded by validation and comparison of obtained results.
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Virtualisation Design in Corporate
Mareček, Ján ; Hrabovský, Jiří (referee) ; Ondrák, Viktor (advisor)
The purpose of my master's thesis is to make a proposal for optimalization of desktop infrastructure using virtualization. The master's thesis is divided into three main parts. First one is engaged in theoretical ground about virtualization. Second part is dedicated to analysis of current state of desktop infrastructure in company and the third contains proposal to modernization of existing infrastructure including project management
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Optimization analysis of brake wheel
Hrabovský, Jozef ; Vlach, Radek (referee) ; Houfek, Lubomír (advisor)
Subject of this diploma thesis is break wheel optimalization analysis. Break wheels are used in mountain bike downhill races in extreme conditions. It is the first product of this type of an emergent company that was made by the use of intuitive approach. The reason for optimalization is improper behavior of existing solution that occurred during testing. This optimalization consists of finding and analyzing existing characteristics, deciding which factors influence this improper behavior, suggesting new solution and verification of this solution. Break wheel characteristics were detected in an experiment. For realization and evaluation of this experiment, a method named Design of experiments, was selected. This method is used for elaboration of results coming from the Regression analysis. It is possible to effectively achieve the result data by using this procedure. The experiment was oriented to gain data of temperature behavior of break wheel during real load. Mathematical model was adapted on the basis of this data and finally, the calculation was made by the use of Final element method by ANSYS WORKBENCH. Calculations were also coordinated through Design of calculation, and were oriented on temperature deformation and stress. Solution achieved by the Final element method, was evaluated by the Regression analysis and served as a proposition for a new break wheel construction.
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