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Form finding of shell structures
Musil, Jiří ; Bažant, Zdeněk (referee) ; Vítek,, Jan (referee) ; Stráský, Jiří (advisor)
The theme of this doctoral thesis is the design of concrete shell structures with the focus on finding their optimal shape. The optimal shape of a concrete shell is the shape in which for a given load (usually the dead weight of the structure) no significant bending moments are generated in the shell and the structure is in the so-called membrane state. The inspiration for this thesis is the work of Swiss engineer Heinz Isler, who developed the shapes of shell structures using model tests of appropriately loaded flexible membranes. He developed the shell structure for large spans by inverting the resultant shape, which carried its weight almost entirely via membrane forces. The numerical solution of the above experiments using Midas Civil is presented herein. The basic principles of the method are demonstrated on the example of sagged cable. The numerically found shapes are compared with the analytical solution. A shell is designed based on the numerically found shapes and its stress response to dead load is described, particularly in relation to the membrane action. In the next part, the acquired knowledge and methods were used to design three relatively complicated shell structures. Each structure was statically analysed and its static behaviour was described. Structures with perfectly rigid or flexible supports, which simulate real behaviour of the supports, were studied. In the final phase, the results of static analysis of the selected shell were experimentally verified on a physical model in a scale of 1: 55.56. The model has been built using 3D printing. The thesis describes the use of a modelling similarity, the model design, the production process, and the experiment. The load test confirmed the optimal design of the shell structure and the validity of the numerical method for finding their shapes.
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Analysis of Mechanical Stress during Short Circuit in an Air-Insulated MV Switchgear
Bártů, Jan ; Bajánek, Tomáš (referee) ; Orságová, Jaroslava (advisor)
This Master thesis is based on problems of force effects of the magnetic field of short-circuit current. Firstly, I analysed the force action of the three phase busbars during the three-pole short circuit. The analysis was performed in the Ansys Maxwell program and I verified the correctness of the analysis by numerical calculation. The second practical part was executed for ABB company. The main task was to analyse the force effects of the short-circuit current in the HV switchgear with focusing on the arms and contact system of the circuit breaker. The simulations of the following configurations were performed in more details: three configurations of the simplified VD4 circuit breaker, two types of VD4 circuit-breaker contact systems and a linear circuit breaker configuration model. The objective was to calculate the forces acting on the current path of the arms and contact system of the VD4 circuit breaker during the three-phase short-circuit and to simulate the effects of forces on these current parts. For modelling of individual assemblies, calculations and simulations I used: SolidWorks 2014, Ansys Maxwell 16.0 and Ansys Workbench 14.5 programs. With SolidWorks 2014 3D CAD software were modelled simplified assemblies of circuit breakers and contact systems. These systems were imported into the Ansys Maxwell software, where the force effects of the magnetic field of the short-circuit current were calculated. In Ansys Workbench programme was simulated the effect of forces on the current circuit breakers. Moreover, the final deformations of the materials (with respect to the mechanical properties of the structure) were plotted. The analysis of force effects of the magnetic field was performed for the specified static short - circuit current value.
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Dynamic analysis of railway bridge
Mojrová, Martina ; Vlk, Zbyněk (referee) ; Nevařil, Aleš (advisor)
The content of work is to determine modal characteristics of bridge construction over the Dyje river near Břeclav. That is done in ANSYS software and AxisVM software. These characteristics are compared with results from dynamic loading test and they are compared between themselves. In thesis is also an assessment of response to static traffic loads because of decision about dynamic analysis necessity. Then there is a simulation of dynamic traffic loads and results of this simulation are compared with results of dynamic analysis which was done by the project. The aim is to do a few static and dynamic tasks and compare results with the real dynamic test and with calculated results and to determinate the effect on certain variables.
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Equivalence-Based Slicing of Programs
Malecová, Tatiana ; Vojnar, Tomáš (referee) ; Malík, Viktor (advisor)
Cieľom tejto práce je navrhnúť metódu, ktorá zjednoduší dva porovnávané programy na základe výsledkov ich sémantickej analýzy. Cieľom je odstránenie čo najväčšieho množstva sémanticky ekvivalentných častí porovnávaných programov. Pre nájdenie týchto ekvivalentných častí aplikujeme vlastné riešenie problému nájdenia najväčšieho spoločného indukovaného podgrafu. Následne sme schopní zjednodušiť programy využitím spätného statického prerezávania. Aplikáciou tohto zjednodušenia získame prerezané programy, ktoré obsahujú rozdielne časti a časti programov, ktoré môžu tieto rozdiely ovplyvniť. Táto metóda je naimplementovaná ako rozšírenie nástroja DiffKemp, čo je statický analyzátor sémantických rozdielov medzi rôznymi verziami rozsiahlych programov. Experimenty vykonané na jadrách Linux-u ukazujú, že metóda je schopná veľmi efektívne vyprodukovať korektné prerezané programy (analýza sa predĺžila len o 3.2%). Navyše, vzniknuté prerezané programy sú omnoho menšie, ako originálne, čo ich činí vhodnými pre ďalšiu analýzu.
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Analysis of C Programs with Dynamic Linked Data Structures
Šoková, Veronika ; Rogalewicz, Adam (referee) ; Vojnar, Tomáš (advisor)
This master's thesis deals with the analysis of dynamic linked data structures using shape analysis used in the Predator tool. It describes the chosen abstract domain for heap representation - symbolic memory graphs. It deals with the design of framework for the development of static analyzers based on Clang/LLVM. The main contribution is implementing and testing LLVM's transformation passes that simplify the LLVM IR. Second contribution is the optimization of parameters for parallel run of several variants of the Predator tool. Parameters are tuned for benchmark from SV-COMP'16, where our tool won gold medal in Heap Data Structures category. Last contribution is the design of verification core with the focus on the SMG domain.
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Detection of Expressions with Undefined Behavior in C Language
Hellebrandt, Lukáš ; Vojnar, Tomáš (referee) ; Müller, Petr (advisor)
Práce se zabývá detekcí nedefinovaného chování v programech v jazyce C. Zaměřujemese na nedefinované chování vznikající nesprávnou prací se sekvenčními body a vedlejšími efekty. Provedeme teoretický rozbor a pojmy jako nedefinované chování nebo vedlejší efekt zasadíme do kontextu práce. Dále vysvětlíme nebezpečnost konstrukcí vedoucích k nedefinovanému chování. Navrhneme metodu pro automatickou detekci zmíněného druhu nedefinovaného chování. Nakonec navrhneme a implementujeme nástroj pro jeho automatizovanou statickou detekci a popíšeme principy funkce tohoto nástroje. Při jeho návrhu klademe, narozdíl od současných řešení, důraz na funkčnost i v případě přístupu k paměti přes ukazatel nebo z volané funkce. Práce obsahuje příklady nebezpečných konstrukcí, na některých z nich jsou demonstrovány funkce vytvořeného nástroje.
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Static Analysis of Java Programs
Vyvial, Pavel ; Hýsek, Jiří (referee) ; Křena, Bohuslav (advisor)
The project SHADOWS has started research which is developing software for automatic bug healing. We work with self-healing software, which looks for concurrent bugs. If the~detection software finds a bug, the healing action will be performed. After every healing action, one would like to know whether this action has fixed the detected problem and, perhaps even more importantly, that it has not caused any other, possibly even more serious, problem. Therefore this paper describes a technique which gives the answer for this question after automatical healing. One can fix some concurent bugs by adding healing locks. One does healing assurance by searching monitorenter instruction and uses Control Flow Graph analysis over Java byte-code. The prototype uses static analysis (tool FindBugs) for this purpose.
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Analysis of structural and proportional criteria of Romanesque and Pre-Romanesque rotundas.
Kříž, Pavel ; Kalousek, Lubor (referee) ; Unger,, Josef (referee) ; Vlček, Milan (advisor)
Topic of this dissertation thesis follows previous dissertations dealing with reconstructions of historical buildings that were successfully defended at Institute of Building Structures, Faculty of Civil Engineering, Brno University of Technology. The thesis deals with Romanesque and Pre-Romanesque round churches, called rotundas, that were built between 9th and 13th century in the historical territory of Great Moravia. Churches of similar shape can be also found in surrounding countries, but only scarcely. By the time of origin these rotundas were among the oldest masonry buildings built within borders of contemporary Czech Republic. Later some rotundas were destroyed and are known only thanks to the archaeological findings or written records. Some are still waiting to be discovered. Surviving rotundas are the oldest masonry buildings in Czech Republic, therefore it can be said that they belong to the most valuable historical buildings in the country. Preserved rotundas were often modified or rebuild in some way. Thanks to their age, origins of many of these buildings are shrouded in a mystery, which is one of the reasons why they attract attention of many researchers – archaeologists, historians and art historians. Many questions arise from their research. These questions have interdisciplinary character and finding the answers requires cooperation of specialists in different fields. One of these fields is building engineering. This dissertation thesis deals with proportional and structural analysis of Pre-Romanesque and Romanesque rotundas. For the proportional analysis author focused on verifying of some of the hypotheses of other researchers connected to the Romanesque rotundas. These include hypothesis dealing with use of historical units for the design of rotundas, hypothetical use of proportional canon, or some universal sets of proportional ratios of vertical and horizontal dimensions. The proportional analysis also helped with verification of some hypothe
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Multiplatform Linux Sandbox for Analyzing IoT Malware
Uhříček, Daniel ; Burget, Radek (referee) ; Kolář, Dušan (advisor)
Analýza IoT malwaru je problematická zejména pro množství a rozlišnost architektur procesorů používaných IoT zařízeními. Práce shrnuje možnosti statické, dynamické a síťové analýzy Linuxového malwaru a hodnotí existující open source řešení oddělených běhových prostředí pro automatizovanou analýzu. Práce navrhuje modulární, rozšířitelný systém s~jednoduchými možnostmi nasazení, dostupnou API a webovým rozhraním. Výsledná implementace podporuje pět architektur a byla testována na vzorcích IoT malwaru.
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Static Analysis Using Facebook Infer to Find Atomicity Violations
Harmim, Dominik ; Smrčka, Aleš (referee) ; Vojnar, Tomáš (advisor)
The goal of this thesis is to propose a static analyser that detects atomicity violations. The proposed analyser Atomer is implemented as a module of Facebook Infer, which is an open-source and extendable static analysis framework that promotes efficient modular and incremental analysis. The analyser works on the level of sequences of function calls. The proposed solution is based on the assumption that sequences executed atomically once should probably be executed always atomically. The implemented analyser has been successfully verified and evaluated on both smaller programs created for testing purposes as well as publicly available benchmarks derived from real-life low-level programs.
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