Special Methods for Microwave Vector Measurements

V práci je popsán princip měření metodou šestibranu, jeho teoretický návrh, vliv jeho parametrů na přesnost měření a vlastnosti dalších obvodů pro zpracování jeho signálů. Jednoduchý šestibran byl plně realizován a jeho parametry prezentovány. Jako vlastní přínos je navržen nový přístup k použití metody s více detektory. Jeho základními vlastnostmi jsou více funkčních šestibranů na jednom pracovním kmitočtu a rozšíření pracovního pásma na rozsah 1 : 100 i více. Takový šestibran byl navržen pro rozsah 50 až 2680 MHz, realizován a jeho parametry prezentovány.Theoretical principles of the sixport measurement method are presented. Description of theoretical design and influence of its parameters on measurement precision follows. Simple sixport measurement system was made and its parameters are described. As the main thesis contribution there is described a new approach to method with more detectors in the system. Mean features are more valid sixports at one specific frequency and frequency bandwidth aviable up to 1 : 100 and more. Such a wideband measurement system was designed for the frequencies between 50 and 2680 MHz and its parameters are presented in the work.

Digitally-Compensated Wideband 60 GHz Test-Bed for Power Amplifier Predistortion Experiments

Millimeter waves will play an important role in communication systems in the near future. On the one hand, the bandwidths available at millimeter-wave frequencies allow for elevated data rates, but on the other hand, the wide bandwidth accentuates the effects of wireless front-end impairments on transmitted waveforms and makes their compensation more difficult. Research into front-end impairment compensation in millimeter-wave frequency bands is currently being carried out, mainly using expensive laboratory setups consisting of universal signal generators, spectral analyzers and high-speed oscilloscopes. This paper presents a detailed description of an in-house built MATLAB-controlled 60 GHz measurement test-bed developed using relatively inexpensive hardware components that are available on the market and equipped with digital compensation for the most critical front-end impairments, including the digital predistortion of the power amplifier. It also demonstrates the potential of digital predistortion linearization on two distinct 60 GHz power amplifiers: one integrated in a direct-conversion transceiver and an external one with 24 dBm output power

Constraining models of twin peak quasi-periodic oscillations with realistic neutron star equations of state

Twin-peak quasi-periodic oscillations (QPOs) are observed in the X-ray power-density spectra of several accreting low-mass neutron star (NS) binaries. In our previous work we have considered several QPO models. We have identified and explored mass-angular-momentum relations implied by individual QPO models for the atoll source 4U 1636-53. In this paper we extend our study and confront QPO models with various NS equations of state (EoS). We start with simplified calculations assuming Kerr background geometry and then present results of detailed calculations considering the influence of NS quadrupole moment (related to rotationally induced NS oblateness) assuming Hartle-Thorne spacetimes. We show that the application of concrete EoS together with a particular QPO model yields a specific mass-angular-momentum relation. However, we demonstrate that the degeneracy in mass and angular momentum can be removed when the NS spin frequency inferred from the X-ray burst observations is considered. We inspect a large set of EoS and discuss their compatibility with the considered QPO models. We conclude that when the NS spin frequency in 4U 1636-53 is close to 580Hz we can exclude 51 from 90 of the considered combinations of EoS and QPO models. We also discuss additional restrictions that may exclude even more combinations. Namely, there are 13 EOS compatible with the observed twin peak QPOs and the relativistic precession model. However, when considering the low frequency QPOs and Lense-Thirring precession, only 5 EOS are compatible with the model.Comment: 12 pages, 9 figures, 3 tables, accepted for publication in The Astrophysical Journa

Multimedijski udžbenik o teoriji i primjeni elektromagnetizma

Teaching university courses, which deal with the phenomena of electromagnetic nature and their application, is rather difficult due to their abstract nature. Therefore, the teaching has to be accompanied by clear explanation, and by simulation illustrating the examined topics. That is why a multimedia textbook was developed, which presents the theoretical description of electromagnetic phenomena, and at the same time, enables to simulate them. The textbook is of a two-dimensional structure, which enables the book to be used by bachelor\u27s students and master\u27s ones for studying, by users of incorporated programs for guiding, and by programmers for developing their own applications. The textbook is completed by an explanatory indexing mechanism, which makes the book readable even for an inexperienced reader.Podučavanje sveučilišnih kolegija koji se bave fenomenima elektromagnetizma prilično je zahtjevno zbog apstraktnosti gradiva koje se iznosi. Podučavanje stoga valja popratiti jasnim objašnjenjima i simulacijama koje ilustriraju teme koje se obrađuju. Upravo je zato priređen multimedijski udžbenik koji donosi teorijski opis elektromagnetskih fenomena i istodobno omogućava njihovo simuliranje. Struktura udžbenika je dvodimenzionalna što omogućava njegovu primjenu na dodiplomskom i poslijediplomskom studiju korištenjem gotovih programa koji su dio udžbenika ili izradbom vlastitih programa od strane korisnika. Udžbenik je opremljen sustavom kazala s objašnjenjima, što olakšava korištenje i čitateljima koji ne poznaju područje

GRBAlpha: the smallest astrophysical space observatory -- Part 1: Detector design, system description and satellite operations

Aims. Since launched on 2021 March 22, the 1U-sized CubeSat GRBAlpha operates and collects scientific data on high-energy transients, making it the smallest astrophysical space observatory to date. GRBAlpha is an in-obit demonstration of a gamma-ray burst (GRB) detector concept suitably small to fit into a standard 1U volume. As it was demonstrated in a companion paper, GRBAlpha adds significant value to the scientific community with accurate characterization of bright GRBs, including the recent outstanding event of GRB 221009A. Methods. The GRB detector is a 75x75x5 mm CsI(Tl) scintillator wrapped in a reflective foil (ESR) read out by an array of SiPM detectors, multi-pixel photon counters by Hamamatsu, driven by two separate, redundant units. To further protect the scintillator block from sunlight and protect the SiPM detectors from particle radiation, we apply a multi-layer structure of Tedlar wrapping, anodized aluminium casing and a lead-alloy shielding on one edge of the assembly. The setup allows observations of gamma radiation within the energy range of 70-890 keV with an energy resolution of ~30%. Results. Here, we summarize the system design of the GRBAlpha mission, including the electronics and software components of the detector, some aspects of the platform as well as the current way of semi-autonomous operations. In addition, details are given about the raw data products and telemetry in order to encourage the community for expansion of the receiver network for our initiatives with GRBAlpha and related experiments.Comment: Accepted for publication in Astronomy & Astrophysics, 9 pages, 10 figure

Technological and operational aspects of rail operation after addition of the second track Hradec Králové - Týniště nad Orlicí

Tato práce se zabývá úsekem tratě Hradec Králové - Týniště nad Orlicí po zdvoukolejnění. Zkoumá dopad na ukazatele propustnosti, jízdních dob a spolehlivosti jednotlivých variant jízdního řádu, včetně vlivu zřízení zastávky Nepasice. Posouzen je i potřebný počet dopravních kolejí ve vybraných dopravnách.This thesis deals with the section of the track Hradec Králové - Týniště nad Orlicí after rebuilding the single track to double track. It examines the impact on the capacity, driving time and reliability of the timetable options, including the impact of setting up the Nepasice stop. The necessary number of transport tracks in selected transport facilities is also assessed.Dopravní fakulta Jana PerneraStudent úspěšně obhájil diplomovou práci a odpověď na otázky státní zkušební komise

Czech Sherlock Holmes: Domestic Creative Reflections of British Literary and Cultural Traditions

Ač postava a příběhy Sherlocka Holmese tkví hluboce v britské kulturní tradici, jsou již delší dobu různými způsoby adaptovány v rámci jiných kultur. Rovněž čeští autoři občas po svém uchopují tento popkulturní materiál. Cílem práce bude zamyslet se nad dosavadními původními českými literárními díly využívajícími postavu Sherlocka Holmese a pokusit se zjistit, jak a čím se odlišují od britského kanonického podání a co typicky českého autoři do holmesovské tradice vkládají.The character and stories of Sherlock Holmes are deeply situated in a british cultural tradition but they are also adapted in a diferent ways into the other cultures. Czech authors sometimes also use this popcultural material. The goal of this work is to analyze czech adaptations of Sherlock Holmes and try to compare them with a canonic work of Arthur Conan Doyle and also to discover if there is something typical for all czech adaptations.Fakulta filozofická1. Představení a objasnění tématu práce. 2. Posudky vedoucího práce a oponenta. 3. Diskuse o problematických otázkách

Tvorba metodiky auditu jakosti u dodavatelů

Import 20/04/2006Prezenční výpůjčkaVŠB - Technická univerzita Ostrava. Fakulta metalurgie a materiálového inženýství. Katedra (639) kontroly a řízení jakost

Modification rail connection on the track 018 Chocen - Litomysl

Práce se v první části zabývá analýzou železničního spojení na trati 018 Choceň Litomyšl, konkrétně technickými parametry, jednotlivými dopravnami, výkony v osobní dopravě a krátkým shrnutím autobusové dopravy. Dále jsou navržena opatření pro zvýšení traťové rychlosti a bezpečnosti. Mezi hlavní opatření patří změna organizování drážní dopravy a jízdního řádu. Poslední část práce se zabývá zhodnocením navrhovaných opatření.This bachelor thesis in the first part deals with analyzis of the railway connection on the track 018 Choceň - Litomyšl specially with technical parameters, individual operating posts, perfomance in public tranport and short summary of the bus service. Further are proposal provision for improve the critical running speed and safety. Amongst the main provisions belongs change of organisation in the rail transport and the schedule. Last part of thesis deals with evaluation of proposal provision.Dopravní fakulta Jana PerneraStudent obhájil předloženou bakalářskou práci, zodpověděl na otázky vedoucího práce a oponenta práce a kladně reagoval na dotazy kladené v rozpravě