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Ab initio simulation of a tensile test in iron
Friák, Martin ; Šob, Mojmír ; Vitek, V.
A tensile test in ferromagnetic and nonmagnetic iron is simulated by ab initio electronic structure calculations using all-electron full potential linearized augmented plane wave method (FLAPW) within generalized gradient approximation (GGA). The theoretical tensile strength of ferromagnetic iron for [001] loading is determined and compared with that of other materials. The magnetic behavior of iron under tensile loading is studied in detail and compared with results for triaxial loading.
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System for Dust Grain Levitation
Beránek, Martin ; Němeček, Zdeněk (advisor) ; Čermák, Ivo (referee)
Laboratory simulations of dust grain charging can provide an unique data about inuence of the separate charging processes, which are inseparable otherwise. Knowledge of the inuence of individual processes is important for understanding charging dust grains in real conditions. For laboratory experiments the electrodynamic trap, in which is captured single dust grain, is used. We have analysed several particular trap geometries and their inuence on the accuracy of measurements in this work. We deale mainly with nding of the electrode layout, which forms an open trap and therefore minimises unwanted electron emission from electrodes. We have found such modication of a linear quadrupole, which allows to trap the charged grain in the axial direction too. The calculation shows that the modication should not have a negative inuence on the electric eld with respect to the measuring of the grain specic charge.
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Mobile robot control system
Kalina, Michal ; Veselý, Libor (referee) ; Hynčica, Ondřej (advisor)
This thesis deals with building of two-wheeled mobile robot and consecutive creation of drivers and control for sensors, engines and controller design. The control is based on Arduino platform using ATmega328 processor. Firstly there is in this thesis recherche. Part of this thesis is modelling one where simulation model of our system is created, its linearization and then controller design. Further it contains description of the building robots body, description and functionallity of used engines, description of all sensors and detailed description of available printed circuit board. In the end there is software part where the engines control is described, operation of the sensors and functionallity of the controller. Result of this thesis is function application of controlling and operating of two-wheeled unstable mobile robot.
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Interaction of fluid flow with an dirfoil
Feistauer, M. ; Horáček, Jaromír ; Sváček, P.
Numerical simulation of 2D oncompressible viscons fluid flow in interaktion with an vibrating dirfoil is described. The airfoil has two degrees of freedom, for rotation and translation. The Navier-Stokes and continuity equations are solved by finite element method associated with solution of ordinary differential equations describing the dirfoil motion. The computational domain is time dependent and the problem is solved by Arbitrary-Lagrangian-Eulerian (ALE) method.
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Quality of Service Provision in Wireless Networks
Hnilička, Miroslav ; Janeček, Jan (advisor) ; Peterka, Jiří (referee)
This thesis aims at quality of service provisioning mechanisms in wireless packet networks. The main target of the work is multiple hops wireless networks area in which the problem is more general than in access networks. Theoretical part of the thesis analyses the problem and shows detailed insight of possible solutions. Practical part of the thesis focuses on more specific problem. Impacts of using different particular mechanisms on link and network layers are studied here, considering wireless mesh networks based on IEEE 802.11b technology (WiFi). Simulation model MeshQoS is designed on the basis of discrete simulation system OMNeT++. Inside this model, there are implemented two routing protocols - AODV defined by IETF and newly proposed hybrid opportunistic protocol OMR (OpportunisticMesh Routing). Results of experiments with this model helps to get the notion of the level of quality of services achievable in particular mesh networks configurations. They also show the positive effects of using opportunistic routing principle. In most scenarios OMR provide much lower latency, higher delivery probability and higher throughput.
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Cell shape simulation using cytoskeleton model
Horáček, Jaroslav ; Bílý, Tomáš (referee) ; Bálek, Martin (advisor)
This work is focused on computer modelling of cells' behavior. Emphasis is layed on simulating of cell shaping. The goal is to design theoretical structure, which suitably represents cytoskeleton of cell. Our model is based on Zygotic graph. It defines cell reactions to incoming stimulation from environment. Unlike previous models we newly add Fill graph and Granary graph to the Zygotic graph. In order to modelling of cell shaping we define membrane flexibility. We also define mechanism of Cytoplasmatic pulse. It is necessary for amoeboid movement modelling. We added new structure called Granary, which represents storage ability of cell. We use our model to simulate movement of amoeba cell. Another example shows white blood cell moving through blood vessel wall. We also attempt to simulate growth of cells inside closed environment.
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Numerical solution of compressible flow through a turbine cascade using various transition models
Nádvorník, M. ; Straka, P. ; Příhoda, Jaromír
The contribution deals with the numerical simulation of 2D compressible flow through a linear turbine blade cascade. Simulations were carried out by the in-house numerical code based on the two-equation k-omega turbulence model with the algebraic transition model and by the commercial software Fluent using the three-equation turbulence model including the transition model proposed by Walters and Cokljat. Predictions carried out for different Reynolds and Mach numbers cover the transition in the attached and separated flow as well. Predicted values of the loss coefficient and the flow outlet angle were compared with experimental data for the turbine cascade VS33.
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Evaluation of climate continentality
Mikolášková, Kateřina
The paper considers climate continentality from points of view of both temperature and precipitation. Main indices developed for climate continentality are present and compared and a suggestion of new index is made. The newly suggested index is based on daily means of temperature and considers influence of latitude on temperature distribution on the Earth. Linear regression was chosen as a function which describes the best the dependence of annual mean temperature on latitude. All indices are applied to the area of Europe and they are illustrated in maps created in ArcGIS and then evaluated. Evaluation is focused on newly suggested index. Trend of climate continentality from 1961 up to 2004 at station Prague - Clementinum is considered from points of view of all indices used in this paper. No significant trend is obvious but changes in a sub periods are noticeable.
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Mixing audio console with microphone preamplifier
Mecerod, Václav ; Šotner, Roman (referee) ; Kratochvíl, Tomáš (advisor)
Bachelor’s thesis on the theme "Mixing audio console with microphone preamplifier" deals with the design of an audio device for mixing signals from different sources. After a short theoretical introduction to issues mixing audio consoles, block diagram and circuit diagrams of each part are designed. These are redrawn into OrCAD Capture and using software PSpice simulations are performed. Configuration of the proposed mixing audio console is as follows: Two microphone preamplifiers with true differential inputs with switchable sensitivity, with the quad-band equalizer with tunable mid bands and adjustable delay. One line level input and one instrument input with three bands corrector. The output section consists of headphone and line level out.
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