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An Efficient Way to Allocate and Read Directory Entries in the Ext4 File System
Pazdera, Radek ; Michal, Bohumil (referee) ; Kašpárek, Tomáš (advisor)
Cílem této práce je zvýšit výkon sekvenčního procházení adresářů v souborovém systému ext4. Datová struktura HTree, jenž je v současné době použita k implementaci adresářu v ext4 zvládá velmi dobře náhodné přístupy do adresáře, avšak není optimalizována pro sekvenční procházení. Tato práce přináší analýzu tohoto problému. Nejprve studuje implementaci souborového systému ext4 a dalších subsystému Linuxového jádra, které s ním souvisí. Pro vyhodnocení výkonu současné implementace adresářového indexu byla vytvořena sada testů. Na základě výsledků těchto testů bylo navrženo řešení, které bylo následně implementováno do Linuxového jádra. V závěru této práce naleznete vyhodnocení přínosu a porovnání výkonu nové implementace s dalšími souborovými systémy v Linuxu.
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Modelling of Load Impacts Acting on Transport and Handling Equipments with the Aim of their Optimization
Šťastný, Antonín ; Hrabovský, Leopold (referee) ; Kuľka,, Jozef (referee) ; Škopán, Miroslav (advisor)
This PhD thesis deals with employment of the state of the art methods of mathematical optimization and structural analysis in the field of load carrying steel structures of handling devices. The goal of the thesis is to compile a methodology which enables generating of optimal dimensions of conceptually designed load carrying parts of handling devices. The proposed methodology is composed of sub-methods which are successively applied to find an optimal configuration of structure according to a chosen criterion. The methodology incorporates sub-methods such as Design of Experiments, parametric finite-element modelling, the state of the art computational methods for stability assessment, mathematical approximation methods and state of the art optimization schemes based of both, heuristic and gradient principle. Recommendations from Eurocode 3 are used to introduce imperfections to the finite element model in order to perform the nonlinear buckling analysis. The practical part of this thesis is focused on optimization of welded beams. The principle of the methodology is in detail explained and demonstrated on an example of lifting spreader beam of load carrying capacity of 20 tons. The proposed methodology is practically realized by an algorithm created in Matlab software. Matlab is also utilized to implement some sub-methods including mathematical optimization schemes. Both, gradient and heuristic optimization algorithms are used for comparison and mutual verification. Structural analysis is performed by means of parametrical finite-element models which are built in the Ansys Parametric Design Language (APDL). The methodology takes into account buckling, which is inherent to thin walled structures under compressive load. The buckling analysis is performed by means of both, linear and non-linear procedures in Ansys. The output of the algorithm is an optimized configuration of the structure, which minimizes the objective function and complies with all requirements implemented in the form of design constraints.
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Design of sewer network rehabilitation of choice parts of urbanized areas
Horák, Ondřej ; Malaník, Stanislav (referee) ; Raclavský, Jaroslav (advisor)
The thesis approaches the problem of design of sewer network rehabilitation of urbanized area named Kamenná čtvrť. The thesis is divided into several parts. In the first part of the thesis there is the accompaying report, which describs characteristics of the area as a whole. The second part of the thesis is about describing each part of the network, clasification of defects according to the ČSN EN 13508 -2 and fothcoming TNV 75 6905 and photographs from network camera survey. In the third part of this thesis there is a chart with all defects located on the network. Also there is an evaluation of each part of network according to prepared TNV 75 6905. The fourth part of the thesis talks about evaluation of each part of the network as a whole. In the fifth part of the thesis we design possible choises of reahabilitation on the network. The sixth part of the thesis contains the economic aspects of possible alternatives and their comparsion. Last part of the thesis contains a hydrotechnical calculation, which means calculation of the current situation and the possible alternatives. There is an individual evaluation of the calculation and if its necessary optimizations of the network.
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