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Biology of three-toed woodpecker
Navrátil, Martin ; Fuchs, Roman (advisor) ; Reif, Jiří (referee)
In my thesis I have tried to find out how does forest management influence presence of the Three-toed woodpecker Picoides tridactylus.This species is considered a "flagship species" of an untouched primeval type of forest and therefore it requires our attention and protection. The thesis contains results of North-American studies focused on the species very similar to Picoides tridactylus. The main chapters are those aimed to provide information about how is the Picoides tridactylus affected by forest fragmentation, stand health condition and finally the impact of food supply on the occurence and behaviour of the species.
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Vertically polarized Yagi antenna with magnetic dipole
Weigel, Filip ; Pokorný, Michal (referee) ; Raida, Zbyněk (advisor)
This bachelor’s thesis deals with the principles of operation and simulation of planar Yagi antennas with a magnetic dipole. Simulation of electromagnetic field was performed in the simulator CST MICROWAVE STUDIO (CST MWS). The project compares results of simulations of several types of Yagi antennas. These antennas can be used for the communication along the living tissue (on-body communication).
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Design of dualband antenna for WiFi USB Dongle
Prchal, Lukáš ; Tkadlec, Roman (referee) ; Wolanský, David (advisor)
This project deals with the design of dual band antenna for the receiving of Wi-Fi signal integrated to the USB key receiver, which can be connected to notebook or PC with the help of interface and receive available Wi-fi signal . The center frequencies were chosen for 2,4 GHz and 5 GHz where the Wi-Fi signal operates and for these frequencies the antenna has been tuned. The antenna has been designed and simulated in CST Microwave Studio 2010. The first part of this work deals with the design of dual band antenna. Next, the resonant frequencies of the antenna are optimized in order to compensate the influence of the plastic housing and the electronic part of the USB key.
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Insulating Properties of Flip Chip Structures
Dóczy, Robert ; Šandera, Josef (referee) ; Pulec, Jiří (advisor)
This work deals with the insulation properties of microelectronic structures. Specifically, insulation resistance of the gap that separates the conductive parts of the system. There are also described the influences, which have the effect on insulation resistance and the methods by which the insulation resistance is measured. There are also slightly described the issues of designing microelectronic packages and ways in which the microelectronic chip can be connected to the circuit. In the experimental part, the thesis deals with specific design of microelectronic structure such as flip-chip. Conductive pattern of this structure was made to allow the measurement of insulation resistance which depends on the application materials which were used in structure assembly. For this purpose, the structures also undergo a series of cleaning, whose influence is also discussed.
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Tool for Designing Procedural Textures
Číž, Miloslav ; Polok, Lukáš (referee) ; Milet, Tomáš (advisor)
This thesis deals with implementation of a program library for designing and generating two-dimensional procedural textures and its GUI supportive tool. Attention was paid to common methods as well as to other computer graphics areas with effort for modifying the algorithms in order to achieve unique results. An effective way of texture representation and its concrete implementation is also presented.
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Planar Antennas on Electromagnetic Bandgap Substrates
Horák, Jiří ; Dědková, Jarmila (referee) ; Škvor,, Zbyněk (referee) ; Raida, Zbyněk (advisor)
Planar antennas are used in several technical applications. The family of planar antennas contains microstrip antennas, which are very popular due to the low weight, low profile, simple manufacturing and easy mass production. Lower gain and excitation of surface waves are disadvantages of microstrip antennas. The propagation of surface waves can be efficiently suppressed if the conventional substrate is replaced by an electromagnetic bandgap (EBG) substrate. Microstrip antennas on EBG substrates have been presented in an open literature for several years. Nevertheless, no published work is devoted to the design of EBG substrates, which can suppress surface waves at several frequencies those cannot be covered by a single bandgap. In order to reach optimum parameters of designed antennas, selected global optimization methods are applied (genetic algorithms, particle swarm optimization, ant colony optimization).
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Optimization of production of thin films of metallic materials
Čejka, Marek ; Kadlec, Michal (referee) ; Šubarda, Jiří (advisor)
The present thesis deals with optimization of the formation of thin layers of metallic materials. In the theoretical part was elaborated overview of the implementation of the formation of thin- film structures, particularly using vacuum techniques. Chemical and physical vapor deposition. They were described methods of pretreatment of thin layers. The findings were discussed methods of controlling the pre-treated surface, quality control and mutual adhesion of coating layers. In the experimental part of the pre-treatment methods were selected and applied to selected substrates. Pretreatments were evaluated using a control surface by wetting angles and by atomic force microscopy. Then, the metal structure formed of copper on the pretreated substrates. Implementation by means of magnetron sputtering. Adhesion layers was checked by testing the surface lattice method. The quality was observed by scanning electron microscopy. The results were used to design the technological process of making metal layers.
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Antennas with metamaterial radomes
Martínek, Luděk ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This thesis deals with microstrip antennas covered by the metamaterials. First, are described planar antennas, their problems and the emergence of surface waves. Surface waves can cause unwanted coupling among particular parts of the structure and can degrade its parameters. The problem can be solved using an electromagnetic band gap structure (EBG). These periodic structures are able to suppress surface waves in different frequency bands. It is shown how the EBG structure in the function superstate improve directivity and antenna gain. Radiation conventional microstrip antenna with metallo-dielectric EBG superstrate and with the purely dielectric double-layer superstrate is described. The both structures are designed and simulated in CST Microwave Studio program. Further is described the antenna radiation with so-called mushroom structure and metallo-dielectric EBG superstate. The structure is again designed and simulated in CST MWS program. Finally, there are two structures with metallo-dielectric superstate implemented and measured.
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Using konduktometric method for conductivity measurement of the corrosive layer of lead alloys
Neoral, Jiří ; Vaněk, Jiří (referee) ; Bača, Petr (advisor)
Lead-acid batteries are the oldest and most common type of secondary cells. Their biggest use is as a power source for a car starter. Bipolar lead-acid batteries could also be used for new applications such as power sources for hybrid electrical vehicles (HEV) for their high power. But there are still many technical problems limiting its use in these applications, which have to be overcome. This could cover parasite reactions as is gas creation, heat removal from the battery and another big problem is substrate corrosion. This diploma thesis concerns the actual state of bipolar lead batteries in the world with detail orientation to substrate corrosion. This thesis describes the conductometric method of lotion conductivity measurement and its modification for measurement of lead grid conductivity. From that we can find out, that when material loses more conductivity, the greater the corrosion. This thesis describes needed preparative experiments for assurance, that the conductometric method can be used for corrosion speed measurement and there are other experiments testing different lead alloys for corrosion speed.
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Tools Made from Cemented Carbide
Opršál, Ladislav ; Osička, Karel (referee) ; Kalivoda, Milan (advisor)
The thesis focuses on cutting tools made of both coated and uncoated cemented carbides. The first part of the thesis deals with the division of materials used for the production of the tools. The second part of the thesis introduces uncoated cemented carbides, special attention being paid to the labelling, production and properties of such compounds. The third part of the thesis presents coating deposition techniques and examines the properties of coating layers. Coating layers are produced using two different methods – CVD and PVD. The last part of the thesis compares the properties of the cutting tools (e.g. their cutting values) produced by the companies Pramet Tools, Sandvik – Coromant and Seco Tools.
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