|
Numerical synthesis of filtering antennas
Kufa, Martin ; Mazánek, Miloš (referee) ; Masopust, Jiří (referee) ; Raida, Zbyněk (advisor)
Dizertační práce je zaměřena na kompletní metodiku návrhu tří a čtyř prvkových flíčkových anténních řad, které neobsahují žádné filtrující části a přesto se chovají jako filtrující antény (filtény). Návrhová metodika kombinuje přístup pro návrh filtrů s přístupem pro anténní řady a zahrnuje tvarování frekvenčních odezev činitele odrazu a normovaného realizovaného zisku. Směr hlavního laloku přes pracovní pásmo je kontrolován také. S cílem kontrolovat tvary uvedených charakteristik, nové gi koeficienty jsou představeny pro návrh filtrujících anténních řad. Návrhová metodika byla ověřena na tří a čtyř prvkové filtrující anténní řadě přes frekvenční pásmo od 4,8 GHz do 6,8 GHz, pro šířku pásma celé struktury od 7 % do 14 % a pro požadovanou úroveň činitele odrazu od –10 dB do –20 dB. Celá metodika byla podpořena výrobou a měřením šesti testovacích vzorků filtrujících anténních řad s rozdílnými konfiguracemi. Ve všech případech se simulované a naměřené výsledky dobře shodují.
|
|
Insulation and dielectric properties of water
Grill, Jiří ; Frk, Martin (referee) ; Špinka, Jiří (advisor)
This master´s thesis deals about insulation and dielectric properties of water. It describes the structure of water, covalent and hydrogen bonds. It outlines primary chemical and physical properties of water and then it describes parameters of water - dynamic viscosity, conductivity, surface tension, pH and also describes dielectric properties - dielectric loss, loss factor, permittivity, polarization. Part of the work is practical section, which includes measurements of deionized water, destilled water, tap water and shows primary dependence such as dependence loss factor on frequency or relative permittivity on frequency.
|
|
Measurement uncertainty in diagnostics of insulating materials
Kamenická, Zuzana ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with measurement capacity and dissipation factor of capacitor with real dielectric in frequency range 20 Hz to 30 MHz. Liquid and solid dielectrics are measured by LCR instruments and by test fixtures, both from company Agilent. Relative permittivity and loss number are calculated for different instruments settings. The general aim is to specify the influence of parameters as frequency, voltage, integration time and thickness of material on the uncertainties of primary and secondary quantities for measurement.
|
|
Influence of Loading Frequency on Fatigue Properties of Structural Materials
Kašpar, Jan ; Němec, Karel (referee) ; Věchet, Stanislav (advisor)
This thesis analyse the influence of loading frequency on the fatigue of the structural materials. Low frequency loading (to the 200 Hz) has nearly no influence on the fatigue properties in almost all cases. Hight frequency loading (1 and more kHz) has major influence on the fatigue limit of the structural materials. This interference will disply like increasing of the fatigue limit. For example fatigue limit of steel is more affected by hight frequency loading than the cast-iron. Important aspect at hight frequency loading is rising temperature in the loading process. Rising temperature has negative influence on the fatigue limit of materials. Important aspect of the loading high frequency is possibility to achieved gigacycle regime of the fatigue (109 and more cycles), where should appear crack from below surface. This crack is call „ fish eye".
|
|
Analysis of varnish composites properties in the course of moisture
Novák, Petr ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
The presented bachelor´s work deals with preparation of micronized mica filled varnish sauples. At the same time the temperature and relative humidity influence on the electrical properties of composite material by dielectric relaxation spectroscopy method are monitoring. The composite material consists of epoxide varnish TSA 220S, which is modified with different mass percentage of micronized mica. The results of this project are frequency dependencies of real and imaginary parts of complex permitivity with the environmental temperatures and humidities parameters of varnish components.
|
|
Spanish proverbs (keyword human body) and their Czech equivalents
VRABCOVÁ, Kateřina
This Graduation Thesis aims to capture the characteristics of selected proverbs and to analyze the collected material (351 proverbs). At first in the theoretical part the proverbs come to be classified by the form and the meaning and then their specific forms are characterized. In the practical part the proverbs are analyzed and an examination is performed as to their syntax and semantics compared with their Czech equivalents. The frequency of use of individual proverbs in the contemporary Spanish is described according to the corpus CREA.
|
|
Teplotní účinek na rheologické vlastnosti pryžového prvku
Půst, Ladislav ; Pešek, Luděk ; Vaněk, František ; Bula, Vítězslav
Deformation and temperature data of a vibro-damping element measured in laboratory condition at harmonic loading with constant prload F st =6kN were elaborated with the aim to build termo-mechanical characteristic of rubber-like material. It is shown that the increase of temperature during harmonic loading at various amplitudes F0=(0,75,3) kN and frequencies fe(10,30) Hz is exponential in time and proportional to the square of loading amplitude. The proposed mathematical model of dynamic characteristic of specimen gained by the regression procedure consists of linear, quadratic and fourth root function of displacement amplitude Xo and of the linear correction function of temperature.
|
|
Power Laser Technology at ISI 2013
Mrňa, Libor
The article described the activities of the ISI laser center. It was advanced diagnostics of laser welding process using frequency analysis, the development of a new type of adaptive mirrors for high power laser applications, an apparatus construction for laser hybrid laser-TIG welding, the development of new types of solar absorbers. Contract research for companies was offered.
|
|
Anticipatory "it" objects
Filipová, Anežka ; Malá, Markéta (advisor) ; Šaldová, Pavlína (referee)
The present study focuses on object extraposition in English based on an analysis of corpus findings. The construction in question comprises a monotransitive verb complemented by it which anticipates an object nominal content clause introduced by the conjunctions that, when or if/whether, immediately juxtaposed to the anticipatory it. The aim of the study is to determine the types and frequency of verbs which occur with object it extraposition and to describe what factors influence the use of anticipatory it. The study first provides a review of the relevant topics and outlines a summary of possible factors influencing the occurrence of the construction under study. It focuses on the properties of the verb and complements, the nature of object extraposition in English and the realisations of the object function, and lastly, it outlines the possible factors leading to the use of anticipatory it object. The research part of the study consists of two parts. The first one deals with the selection of material and methodology, while the second presents the description and analysis of the findings. The primary main part of the research was conducted on the data containing 836 sentences that were drawn from the British National Corpus. The research shows that the most frequent verbs occurring with...
|
|
Application of metamaterial structures in terahertz spectral range
Šibík, Juraj ; Kužel, Petr (advisor) ; Čtyroký, Jiří (referee)
The thesis is devoted to a research on metamaterials for terahertz spectral range based on deeply etched silicon. The aim of the work is a theoretical conception and experimental realization of wave plates for selected terahertz frequencies. These wave plates are made of silicon substrates with an etched two-dimensional periodic microstructure where the dimensions of an elementary cell are below the considered wavelength. Theoretical proposal is optimized using the transfer matrix formalism. We designed and experimentally characterized quarter-wave plates for frequencies 0.5 THz and 1 THz and a half-wave plate for frequency 1 THz.
|
guest ::
