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Conceptual Modeling for XML
Nečaský, Martin ; Pokorný, Jaroslav (advisor) ; Krátký, Michal (referee) ; Thalheim, Bernhardt (referee)
XML is a popular format for data representation. As the amount of data represented in XML grows, it is necessary to concentrate on the process of modeling XML schemes of the XML representations. However, modeling the XML schemes on the level f XML schema languages, such as XML Schema, has some drawbacks. A natural idea to improve this situation is to model the XML schemes rst on the conceptual level. It is motivated by the world of relational databases where we also start modeling the data fi rst on the conceptual level. In this thesis we focus on conceptual modeling for XML. We start with a motivating example to point out to several problems that can arise when using only XML schema languages for modeling XML schemes. We discuss how modeling the data rst on the conceptual level can help. We also show that conceptual modeling for XML has some speci cs that should be taken into account by a conceptual model for XML. Mainly, we show that it is necessary to separate the conceptual modeling process to two parts. First, we need to model the data independently of its representation in XML. Second, we need to model how the data is represented in di erent types of XML documents. In the next step, we analyze in detail existing approaches to conceptual modeling for XML and show their limitations. In the main part of...
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XML Data in (Object-) Relational Databases
Mlýnková, Irena ; Pokorný, Jaroslav (advisor) ; Krátký, Michal (referee) ; Osswald, R. (referee)
As XML has become a standard for data representation, it is inevitable to propose and implement techniques for e±cient managing of XML documents. A natural alternative is to exploit features and functions of (object-)relational database management systems, i.e. to rely on their long theoretical and practical history. The main concern of such techniques is the choice of an appropriate XML-to-relational mapping strategy. In this thesis we focus on further enhancing of current most e±cient XML-to-relational storage strategies { so-called adaptive methods. Firstly, we perform a detailed analysis of existing works and especially remaining open issues. Secondly, we propose their enhancing which can be characterized as a hybrid user-driven adaptive mapping strategy, i.e. a combination of so-called user-driven and adaptive methods. In the enhancing we focus especially on deeper exploitation of user-given information, i.e. schema annotations, and we propose an approach which enables to identify new annotation candidates and thus to help users to nd a more appropriate mapping strategy. For this purpose we propose a similarity measure which focuses mainly on structural similarity of the given data and an algorithm which enables reasonable tuning of its parameters on the basis of results of statistical analysis of...
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Bulk Evaluation of User-Defined Functions in XQuery
Bednárek, David ; Král, Jaroslav (advisor) ; Kuznetsov, Sergey (referee) ; Krátký, Michal (referee)
XPath queries are usually translated into an algebra that combines traditional relational operators and XML-speciffic ones. In particular, FLWOR loops are represented using nest, unnest, join, and similar operators and their original nested-loop nature disappears, creating an opportunity for bulk evaluation and join reordering. In XQuery, two additional issues shall be handled - tree construction and the presence of user-deffined functions. The recursive nature of functions pushes the problem outside of the range of relational algebra. This thesis presents a novel evaluation framework based on an expanding network of relational operators, called R-program. In this environment, functions are evaluated in bulk instead of evaluating each call separately. Besides obvious advantages of bulk evaluation, R-programs also allow rearrangement of data flow across function boundaries. A set of program transformations employing these capabilities is described; together with rule-based static interprocedural analysis algorithms used to determine the applicability of the transformations.
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Electrical machines fault simulator
Krátký, Michal ; Krbal, Michal (referee) ; Šlezingr, Jan (advisor)
The goal of this bachelor’s thesis is the laboratory task focused on vibrodiagnostics of rotating electrical machines. The thesis is divided into theoretical and practical part. The theoretical part is made of information related to rotating electrical machine mainly its faults and technical diagnostics. Besides that the vibrodiagnostics is involved into the theoretical part as well. The practical part deals with the design of laboratory task focused on vibrodiagnostics of rotating electrical machines. There is shown how vibrations influence the machine during the operation. There is used asynchronous machine 1LA7080 and vibrometer MV-5L and noncontact tachometer UNI-T UT372 for this experiment. The second task is the starting current diagnostics. The starting current ofthe engine with the rotor asymmetry 1LA7080 and rotor symmetry 1LA7090 is going to be analyzed here. On these engines will be shown, how current flicks affectthe magnetic field of the engine in the air gap.
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Load flow analyses of reactive power in distribution system
Krátký, Michal ; Kašpírek,, Martn (referee) ; Topolánek, David (advisor)
This thesis is focused on issues with transmission of reactive power though the distribution line of E.ON area. The goal is to find out where and in what rate are overflows of reactive power and to project the correctional steps to minimize this overflow. In this solution, there were used data of dispatcher measurement, which were processed by created source code in Matlab. The processing was analyzed for final conclusion. There were discovered shortages in overflow of reactive power in transfer between distribution and transmission line and in unsuitably regulated capacity power factor in Planá power plant and wrong automatic regulation of turns in 440/110kV substation Dasný. The action to minimize overflows of reactive power was projected by decompensation reactor placed in T101 and T102 transformers in substation Tábor.
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