National Repository of Grey Literature 9 records found  Search took 0.00 seconds. 
Design and Realization of Acoustic Treatment of Small Recording Studio
Tkadlec, Vojtěch ; Husník, Libor (referee) ; Schimmel, Jiří (advisor)
This bachelor thesis deals with the topic of acoustic properties of an enclosed space, their detection and modification. The thesis examines the acoustic properties of a small enclosed space, which were determined by simulation using a virtual 3D model and subsequently verified by measurement. After finding out the properties, a substantial part was also devoted to their modification, where the task was to design the acoustic elements so that the resulting length of the reverberation time corresponds to the optimal values for a small recording studio. The design of the elements is followed by their construction, followed by a re-measurement of the space. Furthermore, the work summarizes the principles of modeling and simulation of 3D models.
Piezoelectric MEMS resonators for sensing applications
Klempa, Jaroslav ; Svatoš, Vojtěch (referee) ; Gablech, Imrich (advisor)
Basic principles and processes used during fabrication of microelectromechanical systems are presented in this work. This thesis is focused on material properties, deposition, lithographic and micromachining processes. Fundamental principles and applications of piezoelectric resonant structures are described as well. Final part of this work is devoted to simulation of resonant beams using FEM method in ANSYS® Workbench, practical fabrication and characterization of piezoelectric MEMS resonators.
Model of breathing stabilization in infant using stochastic mechanosensoric stimulation
Laníková, Petra ; Čmiel, Vratislav (referee) ; Provazník, Ivo (advisor)
The goal of this thesis is to create a stochastic model of the breathing automaticity oscillator, including its management with the possibility of stopping and restarting oscillation by an accidental process. The oscillator is implemented by computer program MATLAB R2014a and the results are compared with real records of breathing patterns in newborns. These results are represented with pictures. To evaluate these records is used knowledge of respiratory automatism and sleep apnea syndrome, especially apnea in preterm neonates
Realization of the positioning device for mapping electromagnetic fields
Jozífek, Eduard ; Drexler, Petr (referee) ; Nešpor, Dušan (advisor)
This paper deals with the measurement of electromagnetic fields in reactive zone and proposing an automated workstation for its measurement. The sample is a periodic structure of the circular split resonators, which is due to the magnetic field generated from the supplied loop antenna is brought to resonance and itself becomes imaginary antenna. The measuring probe is placed on the cross-positioning table movement is controlled by two stepper motors.
Adaptive Digital Filtering of Biological Signals
Ištok, Martin ; Kozumplík, Jiří (referee) ; Provazník, Ivo (advisor)
The main objective of this bachelor’s thesis was to describe adaptive digital filtering theory including different types of the adaptive algorithm and adaptive filter. An adaptive systém is used for power line interference canceller for ECG signal. The thesis includes design of 4 adaptive filters: simple adaptive filter, simple adaptive notch filter, adaptive notch filter using resonator and adaptive notch filter using adaptive resonator. It also contains basic testing of the filters based on different settings. Different settings are also evaluated.
Estimation of equivalent circuit parameters of a piezoelectric resonator
Ryšavý, Lukáš ; Majzner, Jiří (referee) ; Sedlák, Petr (advisor)
In this thesis, a simple measurement setup including control software is designed to estimate the parameters of Mason electrical equivalent circuit for piezoelectric resonators. Direct measurements can evaluate variables, such as mechanical quality factor, parallel resonance, serial resonance and serial resistance. These variables are used to estimate remaining parameters. The software is implemented in C++ Builder. Experimental study and verification were carried out on several quartz crystal and piezoceramic samples. The measurements are in good agreement with simulations as it is illustrated by a low value of relative error. The measurement setup will be used for scientific purposes of Dept. of physics FEEC BUT.
Numerical Modeling of Periodical Structures
Nešpor, Dušan ; Bartušek, Karel (referee) ; Brančík, Lubomír (referee) ; Fiala, Pavel (advisor)
The thesis discusses the dynamic electromagnetic field on periodic structures. The author focuses on three principal types of resonant structures, considering their application possibilities. In general, these types can be individually defined as follows: materials exhibiting a negative refractive index of the incident electromagnetic wave; structures with gradual changes in impedance, characterised by their usability as reflectionless surfaces; and periodic structures able to conveniently shape the magnetic field distribution. Materials of the third group within the above-shown short list facilitate the fabrication of magnetoinductive lenses for nuclear magnetic resonance. The presented analysis of the properties of periodic resonant structures is mainly based on numerical models utilising the finite element method, and this approach is combined with both the derivation of the corresponding analytical relations and an experimental measurement of the non-radiating component of the electromagnetic field. The thesis includes a physical description of the basic elements of periodic resonant structures. Physical properties of the elements were examined in detail via numerical analysis. In the course of the research, the data acquired through this analysis and the related experimental measurement enabled the author to propose a method for optimising the most widely used resonant structures. Moreover, several new versions of resonant elements, structures, and fabrication techniques were also designed. The results obtained from the numerical analyses carried out to examine the central physical properties of the fabricated structure samples were all verified via the designed method for measuring the non-radiating component of the magnetic field.
Complex permittivity measurement of materials at microwave frequencies
Polák, Radek ; Hertl, Ivo (referee) ; Láčík, Jaroslav (advisor)
This article describes some methods of measuring complex permitivity in milimeter – wave band, their characteristics, anvatages and disadvantages. Discused are here the reasons for their use in the construction of work place. On the basis these reasons is chosen the best method for practical measurement. That is cavity resonant method. Article contain description of designed measurement system. Whitch is verified by computer simulating of developed model in HFSS Ansoft. Text contain also result of simulations and execute computing of comlex permittivity and tangent loss. In Conclusion is desribed results of practical permittivity measure with realized measurement system.
Modeling metamaterial microwave resonators
Zvolenský, Tomáš ; Kovács, Peter (referee) ; Raida, Zbyněk (advisor)
Práce je věnována modelování mikrovlnných rezonátorů z metamateriálů (materiálů se záporným indexem lomu). V úvodu je rozebráno, co metamateriály jsou, jak se vytvářejí a které jejich vlastnosti jsou podstatné při návrhu rezonátorů. Následuje návrh planárního rezonátoru z metamateriálů. Pro tento účel byly naprogramovány funkce počítající rozměry jednotlivých součástí struktury. Simulace navržené struktury probíhala v programu Zeland IE3D. Simulované struktury byly optimalizovány s ohledem na požadované kmitočty rezonance. První rezonátor sestával z jedné elementární buňky, druhý ze dvou buněk, naladěných na rozdílné kmitočty. Rezonátory byly vyrobeny a experimentálně byly ověřeny jejich vlastnosti.

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