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Vibrational analysis in time domain
Friedel, Petr ; Řehák, Kamil (referee) ; Dlugoš, Jozef (advisor)
The final thesis deals with the possibility of solving the problem of nonlinear vibration phenomena in the time domain using the finite element method. In the introductory part are presented possible simulation approaches for solving nonlinear vibration behaviour, areas of current use and the knowledge, which is needed for a real application using the explicit dynamics approach. In the next part is developed a methodology for investigating the frequency spectrum in time domain and its subsequent implementation on a simple nonlinear model. The third part of the thesis is focused on impact of the presence of nonlinear contacts applied on three-dimensional models and its effect at the frequency spectrum. The final part of the thesis includes the experimental measurement of the nonlinear spring vibration characteristics, in the resonance region and the subsequent replication of the investigated model for numerical FEM simulation. A final discussion of the results answers if experimental vibration measurement can be replaced by numerical simulation.
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Electronic thermostat
Flek, Tomáš ; Číž, Radim (referee) ; Lattenberg, Ivo (advisor)
In essence, this thesis focuses on a search for an optimal measuring method suitable for converting a temperature measurement into an electrical signal that can be processed easily in the other parts of the electrical circuit. The selection of the measurement method was guided by the need to find one suitable for the temperature range in question. For each method there are different temperatures sensors, each with different parameters. This thesis covers in detail the various kinds of temperature sensors and notes their advantage and disadvantage, accuracy, repeatability, non-linearity, longevity, and purchasing price. The thesis also investigates how to cope with non-linearity of the selected temperature sensor while also listing various methods for non-linearity compensation and their effect on the overall measuring. A part of the thesis presents a design of a suitable thermostat that was selected on the basis of this work to provide suitable measuring properties and be most cost effective.
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Static Analysis of Parts of Thermoplastic Pipe Systems
Plášek, Jan ; Kuklík,, Pavel (referee) ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Kytýr, Jiří (advisor)
Thermoplastic materials have significant nonlinear behaviour. The nonlinear behaviour is described by creep curves. The curves of creep modules are dependent on stress, temperature and time. The dissertation thesis deals with the approximation of the creep modules by Prony series. Subsequently three procedures are proposed to take account of creep modules. The proposed procedures are used in two applications. The first application deals with the ring stiffness value of a corrugated sewage pipe. The ring stiffness value is influenced by the creep modulus. The other one deals with a thermoplastic flange connection. The clamping force is dependent on the creep modulus of thermoplastics. The problems were solved by ANSYS program system.
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Behaviour of Objects in Structured Light Fields and Low Pressures
Flajšmanová, Jana ; Čižmár, Tomáš (referee) ; Marago, Onofrio (referee) ; Zemánek, Pavel (advisor)
Studium chování opticky zachycených částic nám umožňuje porozumět základním fyzikálním jevům plynoucím z interakce světla a hmoty. Předkládaná práce podává vysvětlení zesílení tažné síly působící na opticky svázané částice ve strukturovaném světelném poli, tzv. tažném svazku. Ukazujeme, že pohyb dvou opticky svázaných objektů v tažném svazku je silně závislý na jejich vzájemné vzdálenosti a prostorové orientaci, což rozšiřuje možnosti manipulace hmoty pomocí světla. Následně se práce zaměřuje na levitaci opticky zachycených částic ve vakuu. Představujeme novou metodologii na charakterizaci vlastností slabě nelinearního Duffingova oscilátoru reprezentovaného opticky levitující částicí. Metoda je založena na průměrování trajektorií s určitou počáteční pozicí ve fázovém prostoru sestávajícím z polohy a rychlosti částice a poskytuje informaci o parametrech oscilátoru přímo ze zaznamenaného pohybu. Náš inovativní postup je srovnán s běžně užívanou metodou založenou na analýze spektrální hustoty polohy částice a za využití numerických simulací ukazujeme její použitelnost i v nízkých tlacích, kde nelinearita hraje významnou roli.
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Analog distortion musical signals
Růžička, Matěj ; Kubánek, David (referee) ; Vrba, Kamil (advisor)
In this bachelor thesis I studied the differences in sound of valve amplifiers and solidstate amplifiers, causes of those differences, mathematical modelling the transfer characteristic of valve amplifier and then modeling it with simple diode limiter, which used several types of semiconductor diodes, Properties of those diodes were measured as well. Then I constructed limiters for both polarities of input signal, which had non-linear transfer characteristics similar to the valve amplifier and I evaluated their qualities. Then I measured simple amplifier with bipolar transistor, JFET N-channel transistor and optocoupler, Furthermore, I modified triangle-to-sine converters with bipolar transistor, JFET N-channel transistor, measured and evaluated their transfer characteristics. At the end of this bachelor thesis I described designing a diode-based functional converter and converter made from several bipolar transistors, both of these had similar shape of transfer characteristics and I evaluated their qualities by comparing weighted harmonic distortion of the output signal with output signal of tube amplifier.
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Tilt sensors
Hájek, Tomáš ; Caha, Luděk (referee) ; Beneš, Petr (advisor)
The topic of the Bachelor's thesis are MEMS sensors of inclination, which find their use inside integrated circuits, equipment of aerospace and automobile industry, but also in ordinary electrical appliance. The work serves the reader to build a grasp over production, usage, basic principles. Finally, it offers an overview of sensors to ease the orientation on the market. The design of the physical model, which can be used to prevent the sensor from apperance of mathematical errors, is tested in the practical part.
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Behaviour of Objects in Structured Light Fields and Low Pressures
Flajšmanová, Jana ; Čižmár, Tomáš (referee) ; Marago, Onofrio (referee) ; Zemánek, Pavel (advisor)
Studium chování opticky zachycených částic nám umožňuje porozumět základním fyzikálním jevům plynoucím z interakce světla a hmoty. Předkládaná práce podává vysvětlení zesílení tažné síly působící na opticky svázané částice ve strukturovaném světelném poli, tzv. tažném svazku. Ukazujeme, že pohyb dvou opticky svázaných objektů v tažném svazku je silně závislý na jejich vzájemné vzdálenosti a prostorové orientaci, což rozšiřuje možnosti manipulace hmoty pomocí světla. Následně se práce zaměřuje na levitaci opticky zachycených částic ve vakuu. Představujeme novou metodologii na charakterizaci vlastností slabě nelinearního Duffingova oscilátoru reprezentovaného opticky levitující částicí. Metoda je založena na průměrování trajektorií s určitou počáteční pozicí ve fázovém prostoru sestávajícím z polohy a rychlosti částice a poskytuje informaci o parametrech oscilátoru přímo ze zaznamenaného pohybu. Náš inovativní postup je srovnán s běžně užívanou metodou založenou na analýze spektrální hustoty polohy částice a za využití numerických simulací ukazujeme její použitelnost i v nízkých tlacích, kde nelinearita hraje významnou roli.
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Analog distortion musical signals
Růžička, Matěj ; Kubánek, David (referee) ; Vrba, Kamil (advisor)
In this bachelor thesis I studied the differences in sound of valve amplifiers and solidstate amplifiers, causes of those differences, mathematical modelling the transfer characteristic of valve amplifier and then modeling it with simple diode limiter, which used several types of semiconductor diodes, Properties of those diodes were measured as well. Then I constructed limiters for both polarities of input signal, which had non-linear transfer characteristics similar to the valve amplifier and I evaluated their qualities. Then I measured simple amplifier with bipolar transistor, JFET N-channel transistor and optocoupler, Furthermore, I modified triangle-to-sine converters with bipolar transistor, JFET N-channel transistor, measured and evaluated their transfer characteristics. At the end of this bachelor thesis I described designing a diode-based functional converter and converter made from several bipolar transistors, both of these had similar shape of transfer characteristics and I evaluated their qualities by comparing weighted harmonic distortion of the output signal with output signal of tube amplifier.
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Static Analysis of Parts of Thermoplastic Pipe Systems
Plášek, Jan ; Kuklík,, Pavel (referee) ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Kytýr, Jiří (advisor)
Thermoplastic materials have significant nonlinear behaviour. The nonlinear behaviour is described by creep curves. The curves of creep modules are dependent on stress, temperature and time. The dissertation thesis deals with the approximation of the creep modules by Prony series. Subsequently three procedures are proposed to take account of creep modules. The proposed procedures are used in two applications. The first application deals with the ring stiffness value of a corrugated sewage pipe. The ring stiffness value is influenced by the creep modulus. The other one deals with a thermoplastic flange connection. The clamping force is dependent on the creep modulus of thermoplastics. The problems were solved by ANSYS program system.
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Inherent instability of financial markets
Hladík, Jan ; Buben, Radek (advisor) ; Znoj, Milan (referee)
The main aim of this presented diploma thesis is to help build a systematic understanding of the political and social foundations of global financial markets, their operations and impacts on the global power affairs. The thesis highlights the dynamic complexity of the post financial crisis state of the World with its itra- and inter-social features. It instrumentaly uses critique of a free market agenda and neo-classical economy which contrasts the Efficient Markets Hypothesis with Hyman Minsky's Financial Instability Hypothesis (FIH), taking into account the dynamic complexity of financial markets. This approach offers analytical tools that can account for crisis through processes endogenous to contemporary financial capitalism. I shall argue that a financially complex system is, according to the FIH, inherently flawed and unstable. After a theoretical and historical review, the thesis discusses various aspects of the process of austerity regime and its social consequences. This provides an opportunity for analyses of the ongoing existence of interstate competition, of militarised foreign policy, and of other international, at times violent conflicts. In an effort to make sense of some of these phenomena, I instrumentaly use the study of geoeconomics that builds on some fundamental assumptions...
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