|
|
Oscillatory Power Generator Base on Mechanical Resonant Element
Mihalík, Vlastimil ; Houška, Pavel (referee) ; Hadaš, Zdeněk (advisor)
This work deals with the power supply of wireless sensors. When using a wireless sensor is desirable application of alternative energy sources, because the primary cells or batteries may reduce the extent or length of service of the sensor itself. Ambient energy can be used as a suitable alternative source. This energy must be in an appropriate form, which allows its conversion to electric energy. These appropriate, already used types include: solar en., temperature gradient en., en. of flowing liquids, vibration, etc. The advantage of vibrations is its presence in almost all mechanical systems. One of the possibilities for using the vibration of machine systems for power supply wireless sensors is using the vibration power generator with oscillating component. The generator must be designed so that its resonance frequency coincides with the frequency of vibration in the machine system. This method can be used only if the machinery system vibrations at least partially constant. Another option is to use the vibrations caused by, for example, transit transport, or different step acting factor. In this case, it is desirable that the generator is designed with variable resonant frequency, which can partly be achieved, for example, integrating several oscillating component in the body of generator. After the general analysis of the problem, graduation theses will be concerned with the possibility of use of energy from the short damped oscillation and step impulse. Focusing on a proposal of multi-element structures.
|
|
|
Analysis of tuned mass damper
Jurečka, Martin ; Rubeš, Ondřej (referee) ; Kšica, Filip (advisor)
Complex mechanical structures are often exposed to external influences that can cause excessive vibrations, which can limit their ability to perform their function or affect operational safety. Tuned mass dampers, which are focus of this thesis are very often used to avoid such vibrations. The firts part of the thesis is focused on the research of the principle of tuned mass damper and its use in engineering practice. In the secound part obtained knowlage is used to create a mathematical model of the selected mechanical system and then to implement a suitably designed tuned mass damper to damp unwanted vibrations. Part of the work i also to build a real model of the tuned mass damper, which will demonstrate its function.
|
|
|
Study of the oscillation of a pendulum in a magnetic field
Zapoměl, Jaroslav ; Kozánek, Jan ; Košina, Jan ; Cibulka, Jan
Realization of some technological processes requires application of rotating machines with a vertical rotor mounted in rolling element bearings. One of the requirements put on their operation is minimization of energy losses in the support elements. The proposed design variant consists in supporting the vertical rotor by one rolling element bearing placed at its upper part and by one axial magnetic bearing mounted in its lower end. The magnetic bearing is composed of an electric coil coupled with the stationary part and of a permanent magnet attached to the rotating part. The magnetic force attracts the permanent magnet, which reduces radial displacement of the lower end of the rotor. The magnetic field between the magnets represents a force coupling between the rotor and the stationary part, which shows some stiffness and affects the system natural frequencies. The controlled change of the stiffness makes it possible to reduce the rotor lateral oscillations in the resonance area. The investigated pendulum is coupled with the frame by a revolute joint at its upper end. The permanent magnet is attached to its lower end. The electric coil is coupled with the stationary part and placed under the pendulum. The system is excited by a moment of harmonic time history, which sets the pendulum into a seesaw motion.\n\n
|
|
|
The role of fermions and bosons in magnetic resonance imaging
ADAMEC, Filip
Abstract Currently, there are only partial theories describing the role and application of fermions and bosons in magnetic resonance imaging, but there are no interdisciplinary theories. I believe, that by combining diverse disciplines (physics, mathematics and the medical nature of MR), an interdisciplinary theory may emerge, that can also be used as a material to deepen the knowledge of future or already active radiologists in radiological physics and magnetic resonance imaging. The following objectives have been set for this Bachelor thesis: Global target: Creation of an expert description of the role of fermions and bosons in magnetic resonance imaging using interdisciplinary communication. Sub-objectives: C1: Data processing - physics of elementary particles C2: Data processing - classical form of electromagnetic field theory C3: Data processing - structure of magnetic resonance imaging C4: Data processing - quantum mechanics of protons Due to the goals of this bachelor thesis, the following hypotheses were made: H1: The classical dimension of the physical nature of MR can be created by comparison of the structure of magnetic resonance and the classical form of electromagnetic field H2: The quantum dimension of the physical nature of MR can be created by comparison of the structure of magnetic resonance and the quantum mechanics of protons H3: The role of fermions and bosons in the description of the physical nature of magnetic resonance can be described by the comparative structure of magnetic resonance and the quantum dimension of the physical substance of magnetic with the standard model of elementary particles and their interactions In the introduction to the theoretical part of the work, I dealt with elementary particles, their physics and mutual interactions. Furthermore, these particles were divided into fermions and bosons, which were described in more detail. I devoted another part of the theory to the classical form of the electromagnetic field, where I discussed mainly Maxwell's equations. The next part was devoted to quantum mechanics of particles and at the end of the theoretical part I focused on the medical part of magnetic resonance. The practical part compares the knowledge gained in the theoretical part of this work. The results were divided into two sections, according to established hypotheses. The results of this bachelor thesis point to the relatively crucial role of fermions and bosons in magnetic resonance imaging, thus confirming all three established hypotheses. The results of this bachelor thesis point out the relatively crucial role of fermions (electrons, protons) and bosons (photons, Cooper pairs) based on verified and accepted hypotheses.
|
|
| |
|
|
Solid State Tesla Coil
Pařenica, Jakub ; Mikláš, Ján (referee) ; Martiš, Jan (advisor)
The bachelor's thesis focuses on a theoretical description of the operation of Tesla's transformer, its design, including electronics, and its subsequent construction. The basic theory of the transformer replacement scheme is described. The Tesla transformer is generally described, as well as the methods of excitation of the primary side of the transformer, the generation of the discharge, the skin effect and the meaning of resonance. Furthermore, the work describes the construction of the primary coil holder, secondary coil. The work contains a pattern of the power board from the Eagle program, and everything is accompanied by photos. The work describes the recovery procedure and describes all the waveforms that were measured before and after the connection of the secondary coil.
|
|
|
A model of resonant collisions of electrons with molecules and molecular ions
Váňa, Martin ; Houfek, Karel (advisor) ; Cejnar, Pavel (referee) ; Mašín, Zdeněk (referee)
A two-dimensional model of the resonant electron-molecule collision processes with one nuclear and one electronic degree of freedom introduced by Houfek, Rescigno and McCurdy [Phys. Rev. A 73, 032721 (2006)] and a similar two- dimensional model of the dissociative recombination with potential proposed by Hamilton [Ph.D. thesis, University of Colorado, (2003)] are formulated within the time-dependent framework and solved numerically using the finite-element method with the discrete variable representation basis, the exterior complex scaling method and the generalized Crank-Nicolson method. On the model of electron-molecule collisions we illustrate how the time-dependent calculations can provide a deep insight into the origin of oscillatory structures in the vibrational excitation cross sections if one evaluates the cross sections not only at sufficiently large time to obtain the final cross sections, but rather at several characteristic times which are given by the evolution of the system. With use of the time- dependent calculations we demonstrate the complex nature of the dissociative recombination model dynamics and we propose the interpretation of the recom- bination process mechanism. We also propose few techniques for the explanation of the sharp structures in the dissociative recombination cross sections...
|
|
|
Studies of Lanthanide Complexes by a Combination of Spectroscopic Methods
Krupová, Monika ; Bouř, Petr (advisor) ; Kapitán, Josef (referee)
Studies of Lanthanide Complexes by a Combination of Spectroscopic Methods Monika Krupová (Department of Physical and Macromoecular Chemistry, Faculty of Science, Charles University in Prague) Since conventional structural analysis offers rather limited means for the chirality detection, a series of lanthanide tris-(β-diketonates) are investigated as effective receptors for a better chirality sensing in biomolecular substrates. These lanthanide complexes containing β-diketonate ligands are electrically neutral; they can further coordinate with various small organic molecules such as chiral alcohols, amino alcohols or amino acids in organic solvents and produce a strong chiral signal. Previously, a resonance in Raman scattering was observed in the studied systems due to the correspondence of europium electronic transition energy to the laser excitation wavelength, about a 100-fold signal enhancement if compared to non-resonant vibrational ROA was observed. This enabled shorter detection times as well as lower sample concentrations. In the current work, interaction of the Eu(FOD) complex with (R)- and (S)- enantiomer of 1-phenylethanol in n-hexane was studied using IR spectroscopy, Raman spectroscopy and Raman optical activity (ROA), UV-Vis spectroscopy and ultraviolet circular dichroism (UVCD). Only...
|
|
|
Description of narrow resonances using two-potential formula
Bednařík, Lukáš ; Čížek, Martin (advisor) ; Houfek, Karel (referee)
In the presented thesis we study tunneling problems with projection formalism and two potential approach. We apply this approximative method proposed by S.A. Gurvitz in [4] to two new potentials with a quasistationary state. In the next chapter we generalize this method to one-dimensional nonsymmetric potential. A new formula is found and used for calculation of energy width. We compare our results with a numerical method of complex scaling. Finally, we discuss three-dimensional potential. One axis of symmetry is assumed and we derive relatively simple formula for energy width.
|
|
|
Solution of integral equations for separable interactions
Hvizdoš, Dávid ; Horáček, Jiří (advisor) ; Kolorenč, Přemysl (referee)
Title: Solution of integral equations for separable interactions Author: Dávid Hvizdoš Department: Institute of Theoretical Physics Supervisor: prof. RNDr. Jiří Horáček, DrSc., Institute of Theoretical Physics Abstract: This work deals with the most fundamental types of integral equations (Fredholm and Volterra). Their occurrence in quantum mechanics is illustrated and the process that leads to the so-called regular and Jost solution is presented. Further their solutions in the case of separable interactions are studied. Analytical solutions on model separable potentials are sought. Analytical extensions of these solutions to the complex energy plane are provided and the properties of these functions are examined. The method of analytical continuation in the coupling constant based on the extension of the coupling constant as a function of is introduced. For some examples of separable potentials the Taylor expansion of the function and from it the inverse series √ are calculated. These series are then used to determine the resonance parameters of the potential and the accuracy of these calculations is discussed. Key words: integral equations, scattering theory, resonances, separable potential
|
guest ::
