RESONANT AND QUASI-RESONANT SWITCHMODE POWER SUPLIES

Tato práce se zaměřuje na problematiku a řešení spínaných zdrojů. V první části je rozebráno porovnání analogových stabilizovaných a spínaných zdrojů a jejich základní zapojení. Dále je řešena obvodová koncepce rezonančního spínaného zdroje. Pro tento zdroj jsou postupně navrţeny vstupní obvod, hlavní část spínaného zdroje, výstupní obvod a zpětnovazební porovnávací obvod. Podle návrhu byl navrţen tištěný spoj, byly změřeny jeho vlastnosti.This project focuses on issues and solutions to switch mode power suplies. The first part discusses comparison of analog and switching power supply stabilized, and their essential involvement. Further addressed the concept of peripheral participation resonant switch mode power suplies. This chapter is progressively designed input circuit, the main part of the switching resources, output circuit and feedback circuit comparison. At the end of the project is the komplete wiring diagram with a list of used parts. Under the proposal was designed printed circuit, is characteristics were measured.

Double ridge horn antenna for antenna measurement

Tato diplomová práce se zabývá problematikou širokopásmové antény pro měřící účely. Pro tuto koncepci je zvolena hřebenová trychtýřová anténa navrhována na kmitočtové pásmo 0,9 GHz - 9 GHz. Tato práce obsahuje teoretické poznatky o anténách obecně a dále je soustředěna na konkrétní návrh hřebenové trychtýřové antény počínaje výpočtem rozměrů, modelováním a její optimalizací na požadované vlastnosti. V neposlední řadě byla anténa sestrojena a naměřena. Bylo dosaženo činitele odrazu s11The thesis deals with broadband antennas for measurement purposes. A ridged horn antenna has been selected for this concept, designed for the frequency range 0.9 GHz to 9 GHz. This work contains general theoretical description of antennas and further it focuses on a specific design of the ridged horn antenna, beginning with the calculation of its dimensions, modeling and optimization to obtain desired antenna properties. Finally, the antenna was constructed and measured. The reflection factor s11

Measurement of concentration of N atoms in afterglow

We carried out the measurements of concentration of N atoms in afterglo

Non-monotonous evolution of hybrid PVD – PECVD process characteristics on hydrocarbon supply

Hybrid PVD – PECVD process of titanium sputtering in argon and acetylene atmosphere combines aspects of both conventional techniques: sputtering of titanium target (PVD) and acetylene as a source of carbon (PECVD). This process can be used for preparation of metal carbon nanocomposites (MeC/C(:H)) or DLC layers doped with metal (DLC:Me). The aim of this paper is to describe and understand elementary processes in fl uencing the hybrid PVD – PECVD process. A non-monotonous dependence of cathode voltage and current, total pressure and spectral line intensities on acetylene supply fl ow is reported. Explanation of non- monotonous evolutions through the analysis of the target state correlating the process characteristics with properties of coatings prepared by this process is proposed

Study of carbon black types in SBR rubber: Mechanical and vibration damping properties

Styrene-butadiene rubber mixtures with four types of carbon black were studied in this paper. The mechanical properties, including the ability to damp mechanical vibration, were investigated, along with dynamical mechanical analysis (DMA). It has been found that carbon black types N 110 and N 330, having the largest specific surface area and the smallest particle diameter, provide a good stiffening effect. These particles have significant interactions between the rubber, resulting in good reinforcement. On the other hand, the carbon black N 990 type has a lower reinforcing effect and improved vibration damping properties at higher excitation frequencies due to higher dissipation of mechanical energy into heat under dynamic loading. The effect of the number of loading cycles on vibration damping properties of the rubber composites was also investigated in this study. It can be concluded that the abovementioned properties of the investigated rubber composites correspond to physical-mechanical properties of the applied carbon black types. © 2020 by the authors.Research Center of Advanced Mechatronic Systems project within the Operational Program of Research, Development, and Education [CZ.02.1.01/0.0/0.0/16_019/0000867]; NPU I [LO1504]; [IGA/FT/2018/008

Influence of rubber composition on mechanical properties

The purpose of this contribution is to investigate different mechanical properties of various types of rubber composite materials that were filled with carbon black nanofiller. The rubber composites were produced from three different basic rubbers. Moreover, the composites were produced with different volume concentrations of the basic rubbers including their various ratios. Mechanical properties of the tested rubber composites were investigated by means of tensile testing, Shore hardness, rebound resilience, mechanical friction, abrasion, viscoelastic behaviour and vibration damping measurements. It was found in this study that the rubber composition has a significant influence on the stiffness of the investigated rubber composites, and thus, on their mechanical properties. © 2021 Manufacturing Technology. All rights reservedRP/CPS/2020/004; CZ.02.1.01/0.0/0.0/16_019/0000867; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠM

Simultaneous measurement of N and O densities in plasma afterglow by means of NO titration

The paper presents an advanced method based on well established NO titration to determine the absolute densities of atoms and radicals in the afterglow plasma.Soucasne urceni konecntraci N a O v dohasinajicim plazmatu pomoci titrace NOSimultaneous measurement of N and O densities in plasma afterglow by means of NO titratio

Electron density measurements in afterglow of high power pulsed microwave discharge

In the paper we study, be means of microwave interferometry, the evolution of electron density in afterglow of pulsed driven nitrogen discharge. Recombination coeffients are derived, too.Urceni elektronove hustoty v dohasinani pulsniho mikrovlnneho vyboje o velkem vykonuElectron density measurements in afterglow of high power pulsed microwave discharg

DYNAMIC IMPACT WEAR AND IMPACT RESISTANCE OF W-B-C COATINGS

Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings’ impact lifetime

Composition, Structure and Mechanical Properties of Industrially Sputtered Ta–B–C Coatings

Ta–B–C coatings were non-reactively sputter-deposited in an industrial batch coater from a single segmented rotating cylindrical cathode employing a combinatorial approach. The chemical composition, morphology, microstructure, mechanical properties, and fracture resistance of the coatings were investigated. Their mechanical properties were linked to their microstructure and phase composition. Coatings placed stationary in front of the racetrack of the target and those performing a 1-axis rotation around the substrate carousel are compared. Utilization of the substrate rotation has no significant effect on the chemical composition of the coatings deposited at the same position compared to the cathode. Whereas the morphology of coatings with corresponding chemical composition is similar for stationary as well as rotating samples, the rotating coatings exhibit a distinct multilayered structure with a repetition period in the range of nanometers despite utilizing a non-reactive process and a single sputter source. All the coatings are either amorphous, nanocomposite or nanocrystalline depending on their chemical composition. The presence of TaC, TaB, and/or TaB2 phases is identified. The crystallite size is typically less than 5 nm. The highest hardness of the coatings is associated with the presence of larger grains in a nanocomposite structure or formation of polycrystalline coatings. The number, density, and length of cracks observed after high-load indentation is on par with current optimized commercially available protective coatings