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Multimedia Services in Mobile Networks
Kovář, Petr ; Molnár, Karol (advisor)
Long time ago, there were developed methods which can allow fast exchange of information at the longest distance possible. Until recent time, the possibilities of long way communications were very limited. There were technological and financial limitations mainly. With telegraph, telephone and the newest – computer networks invention, the telecommunication services became cheaper and much more comprehensive. With accession and high scale spread of internet, the role of communications is much more important. The most actual trend is mobile internet and connected multimedia networks and their instant accessibility from anywhere. On the first side there are classical telecommunication networks as GSM, UMTS, on the other side there is very strong alternative in shape of WiMAX and WiFi networks combination. For the usage of multimedia services in that networks is very important to handle their prefferization over other traffic, which is very difficult task even on wireless media. For the finding of new processes and methods, which can allow it, there is, at fist, the need for highly accurate and authentic mathematical models. In this doctoral thesis is mapped actual state of the art and proposed the new mathematical model of Distribution Coordination Function, which is much-frequent used as access method in 802.11 networks, Wi-Fi.
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Mobile Robot Localization Using Camera
Vaverka, Filip ; Orság, Filip (referee) ; Rozman, Jaroslav (advisor)
This thesis describes design and implementation of an approach to the mobile robot localization. The proposed method is based purely on images taken by a monocular camera. The described solution handles localization as an association problem and, therefore, falls in the category of topological localization methods. The method is based on a generative probabilistic model of the environment appearance. The proposed solution is capable to eliminate some of the difficulties which are common in traditional localization approaches.
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Information Retrieval in Czech Wikipedia
Balgar, Marek ; Bartík, Vladimír (referee) ; Chmelař, Petr (advisor)
The main task of this Masters Thesis is to understand questions of information retrieval and text classifi cation. The main research is focused on the text data, the semantic dictionaries and especially the knowledges inferred from the Wikipedia. In this thesis is also described implementation of the querying system, which is based on achieved knowledges. Finally properties and possible improvements of the system are talked over.
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Probabilistic model for textile concrete reinforcement and comparison with experiments
Lomič, Jiří ; Rypl, Rostislav (referee) ; Vořechovský, Miroslav (advisor)
The scope of the presented bachelor’s thesis was the establishment of a probabilistic model for material strength of textile reinforcement used for textile reinforced concrete. This reinforcement is composed of AR-glass multi-filament yarns. The goal of this thesis was to determine the potential weak spot of the textile yarn and evaluate its strength in overall. The weak spot could have been a lateral cross-connection, which narrowed the textile yarn at several locations. Another thing of interest was the observation of statistical size effect with the increasing length of textile yarn. In order to properly fit the numerical model to real behavior of multi-filament yarns, five series of experimental tensile testing has been executed in laboratory. Each series consisted of 8-10 specimens and had a different yarn length. Maximum tensile force and maximum deformation have been measured to obtain L-D diagrams for each specimen. Measured data were statistically analyzed and gave the information necessary for the identification of probabilistic model parameters. This parameter estimation has been carried out with the help of numerical and optimization methods included in Python programming algorithms. The problem statement resulted in a combination of model parameters describing the textile yarn behavior. The statistical size effect was observed corresponding to the Weibull theory. The performed study showed that the failure of the textile yarn depends on material strength of its filaments. There are no load concentrators at the location of lateral cross-connections affecting the yarn failure.
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Conversion of Piano Recording from WAV to MIDI
Bednařík, Jan ; Černocký, Jan (referee) ; Szőke, Igor (advisor)
The aim of the thesis is to propose a system capable of automatic conversion of polyphonic piano recordings from the audio format WAV to MIDI. The thesis describes problems related to single tone recognition in music recordings and proposes a solution based on a probabilistic model that uses the Probabilistic Latent Component Analysis method. Recordings of isolated digital piano tones were used to train the system. The proposed system was tested on classical recordings of the Classical Piano MIDI database and on recordings of a Korg SP-250 piano and evaluated using a variety of metrics. The conclusion part contains the results of recognition success rate and their comparison with other existing systems.
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The role of credit default swaps during the subprime mortgage crisis in 2007-2009
Lazukićová, Andrea ; Teplý, Petr (advisor) ; Vozková, Karolína (referee)
This thesis focuses on the role of credit default swaps during the subprime mortgage crisis 2007-2009 with special focus on mortgage-backed securities. In the empirical part of the thesis, three models are constructed. All of them have the same dependent variable, a mortgage delinquency rate in the 2005-2010 period, and independent variables representing various types of credit default swaps issued. Streamlined in each model, credit default swaps (CDS) were divided based on certain criteria (underlying sectors, maturity and ranking) and subsequently compared and analysed. By using the probit model, the main research question "How the probability of mortgage delinquency depends on the volume of credit default swaps issued?" was inspected. The contribution of this thesis is three-fold. First, we show that a delinquency rate of mortgages was correlated with the maturity of CDS issued (the delinquency rate was higher for short-term loans). Second, we state that the volume of subprime loans increased along with the volume of issued CDS, what contradicts to the insurance nature of a CDS. Finally, a mortgage delinquency rate was lower in the 2006-2008 period than in 2009-2011, what implies the domino effect of failing mortgages had an immense impact even after the global crisis.
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Communication complexity
Wagner, Vojtěch ; Krajíček, Jan (advisor) ; Koucký, Michal (referee)
Title: Communication Complexity Author: Vojtěch Wagner Department: Department of Algebra Supervisor: prof. RNDr. Jan Krajíček, DrSc. Abstract: This work deals with communication complexity, which considers mo- del of two (or more) parties, each holding its own binary input (let's say x and y). Each of players has information only about his own input. Their common goal is to compute value of some function f(x, y) of these inputs. Communicati- on complexity measures amount of information communicated between players in order to compute f(x, y). This work especially concerns two main models - deterministic, in which all decision made by players is deterministic and they compute the right value in all cases and probabilistic model which allows ran- domized fashion and the goal of the players is to compute the right value with high enough probability. We present some basic concepts and methods to lower bound communication complexity of functions, all ilustrated on some examples of basic functions. In the end we present some complex and practically relevant examples, on which presented methods are demonstrated. Keywords: communication complexity, deterministic communication model, ran- domized model, lower bounds on communication complexity. 1
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Information Retrieval in Czech Wikipedia
Balgar, Marek ; Bartík, Vladimír (referee) ; Chmelař, Petr (advisor)
The main task of this Masters Thesis is to understand questions of information retrieval and text classifi cation. The main research is focused on the text data, the semantic dictionaries and especially the knowledges inferred from the Wikipedia. In this thesis is also described implementation of the querying system, which is based on achieved knowledges. Finally properties and possible improvements of the system are talked over.
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The role of credit default swaps during the subprime mortgage crisis in 2007-2009
Lazukićová, Andrea ; Teplý, Petr (advisor) ; Vozková, Karolína (referee)
This thesis focuses on the role of credit default swaps during the subprime mortgage crisis 2007-2009 with special focus on mortgage-backed securities. In the empirical part of the thesis, three models are constructed. All of them have the same dependent variable, a mortgage delinquency rate in the 2005-2010 period, and independent variables representing various types of credit default swaps issued. Streamlined in each model, credit default swaps (CDS) were divided based on certain criteria (underlying sectors, maturity and ranking) and subsequently compared and analysed. By using the probit model, the main research question "How the probability of mortgage delinquency depends on the volume of credit default swaps issued?" was inspected. The contribution of this thesis is three-fold. First, we show that a delinquency rate of mortgages was correlated with the maturity of CDS issued (the delinquency rate was higher for short-term loans). Second, we state that the volume of subprime loans increased along with the volume of issued CDS, what contradicts to the insurance nature of a CDS. Finally, a mortgage delinquency rate was lower in the 2006-2008 period than in 2009-2011, what implies the domino effect of failing mortgages had an immense impact even after the global crisis.
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Communication complexity
Wagner, Vojtěch ; Krajíček, Jan (advisor) ; Koucký, Michal (referee)
Title: Communication Complexity Author: Vojtěch Wagner Department: Department of Algebra Supervisor: prof. RNDr. Jan Krajíček, DrSc. Abstract: This work deals with communication complexity, which considers mo- del of two (or more) parties, each holding its own binary input (let's say x and y). Each of players has information only about his own input. Their common goal is to compute value of some function f(x, y) of these inputs. Communicati- on complexity measures amount of information communicated between players in order to compute f(x, y). This work especially concerns two main models - deterministic, in which all decision made by players is deterministic and they compute the right value in all cases and probabilistic model which allows ran- domized fashion and the goal of the players is to compute the right value with high enough probability. We present some basic concepts and methods to lower bound communication complexity of functions, all ilustrated on some examples of basic functions. In the end we present some complex and practically relevant examples, on which presented methods are demonstrated. Keywords: communication complexity, deterministic communication model, ran- domized model, lower bounds on communication complexity. 1
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