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The use of optimization in production planning
Pokorný, Pavel ; Rais, Karel (referee) ; Dostál, Petr (advisor)
The Master’s thesis deals with production scheduling in an industrial company. It uses the means of artificial intelligence to develop an appropriate production schedule in a generalized Flow-shop Programming problem. This problem can be solved by application which is a result of this thesis and was prepaired with use of the software Matlab 7.1 and its Genetic Algorithm and Direct Search toolbox. There is a part devoted to the use of advanced production systems (APS) and the concept of the operative production planning in praxis as well. The thesis pays attention to various optimization models in production scheduling and supply chain management too.
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Construction of the Optimal Control Strategy for an Electric-Powered Train
Pokorný, Pavel ; Šeda, Miloš (referee) ; Kuben, Jaromír (referee) ; Čermák, Jan (advisor)
Předložená disertační práce se zabývá popisem charakteru optimální strategie řízení pro elektrický vlak a výpočtem přepínacích okamžiků mezi jednotlivými optimálními jízdními režimy pro standardní typy odporové funkce. S využitím Pontrjaginova principu a souvisejících nástrojů teorie optimálního řízení odvodíme optimální strategii řízení a rovnice pro výpočet přepínacích okamžiků včetně odpovídajících rychlostních profilů. Kromě základního tvaru úlohy o energeticky optimální jízdě vlaku budeme uvažovat i její modifikace zahrnující globální rychlostní omezení, sklon trati i časově-energeticky optimální řízení vlaku. Navíc uvedeme i analýzu řešení s využitím teorie nelineární parametrické optimalizace. Důraz je kladen na exaktní tvar řešení s minimálním využitím numerických metod.
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Software for an estimation of residual fatigue lifetime of mechanical parts with crack
Motyka, Jakub ; Náhlík, Luboš (referee) ; Pokorný, Pavel (advisor)
This bachelor thesis deals with the creation of software for determining the residual fatigue time of mechanical parts with a crack. In the calculation of the lifetime of fatigue-stressed parts, the existence of an initial crack is assumed. During the operating load of the part, the crack may grow up to a critical size, when a sudden fracture of the part occurs. Knowledge of the number of residual loading cycles is important for machine design and safe part-operation. The first part of this thesis deals with linear-elastic fracture mechanics which forms the theoretical basis of the calculation software. The second part is devoted to the software itself, its principles and work in user interface. The last part compares the software-acquired results with the results reached analytically.
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Comparison of freeware software for estimation of residual fatigue life of bodies
Hanáček, Jan ; Ševčík, Martin (referee) ; Pokorný, Pavel (advisor)
In the first part of this bachelor's thesis the fundamental laws of linear elastic fracture mechanics are described, especially state of stress in bodies with crack and stress intensity factor. Further, the propagation laws of fatigue crack are described and interaction effects of fatigue crack, especially retardation effects are explained. In the second part of this thesis the software NASGRO and AFGROW are described and compared. In the last part of this work the several examples are carried out to compare residual fatigue life obtained by no retardation approach and approach with consideration of retardation effects.
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Determination of elastic modulus of thin layer - numerical study of microcompressive test and the bulge test
Petráčková, Klára ; Pokorný, Pavel (referee) ; Náhlík, Luboš (advisor)
Determination of mechanical properties of very thin films is rather difficult task as all of currently using testing techniques have some weakness. This master’s thesis deals with microcompressive test and bulge test. Finite element simulations of the two methods were carried out in order to better understanding of experimental record. Microcompression combines the sample preparation with the use of focused ion beam (FIB) with a compression test carried out using nanoindenter. Cylindrical specimens (pillars) were prepared from Al film deposited on Si substrate using FIB. Experimentally measured data on pillars needs correction to obtain undistorted material properties of Al thin film. A necessary correction using FE modeling is suggested in the thesis. Second part of the work is focused on modeling of bulge test. Pressure is applied on freestanding SiNx film while deflection of the film is measured. Stress state in the film is biaxial making determination of mechanical properties of the film more complicated. The goal is to present how to model the whole problem. In addition, preparation of the specimens was simulated to estimate residual stress in the film. The paper contributes to a better characterization of very thin surface layers and determination of their mechanical properties.
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Frequency references and dissemination
Hrabina, Jan ; Pravdová, Lenka ; Šarbort, Martin ; Čížek, Martin ; Holá, Miroslava ; Oulehla, Jindřich ; Pokorný, Pavel ; Lazar, Josef ; Číp, Ondřej
The work deals with an overview of research topics of the “Frequency references and dissemination” group, Department of Coherence Optics, Institute of Scientific Instruments, Czech Academy of Sciences. These topics include frequency locking of lasers by laser spectroscopy and high-finnese optical cavities, digital holography and optical frequency tranfers through fiber and free-space optical links.
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Similarities in chaotic behavior of Lorenz 05 model and ECMWF models
Bednář, Hynek ; Raidl, Aleš (advisor) ; Jaňour, Zbyněk (referee) ; Pokorný, Pavel (referee)
This thesis tests the ability of the Lorenz's (2005) chaotic model to simulate predictability curve of the ECMWF model calculated from data over the 1986 to 2011 period and demonstrates similarity of the predictability curves for the Lorenz's model with N = 90 variables. This thesis also tests approximations of predictability curves and their differentials, aiming to correct the ECMWF model estimated parameters and thus allow for estimation of the largest Lyapunov exponent, model error and limit value of the predictability curve. The correction is based on comparing the parameters estimated for the Lorenz's and ECMWF and on comparison with the largest Lyapunov exponent (λ=0,35 day-1 ) and limit value of the predictability curve (E∞=8,2) of the Lorenz's model. Parameters are calculated from approximations made by the Quadratic hypothesis with and without model error, as well as by Logarithmic and General hypotheses and by hyperbolic tangent employing corrections with and without model error. Average value of the largest Lyapunov exponent is estimated to be λ=0,37 day-1 for the ECMWF model, limit values of the predictability curves are estimated with lower theoretically derived values and new approach of calculation of model error based on comparison of models is presented.
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