The topic of the thesis is safe and economical design of a bearing bridge structure according to valid regulations and standards. The structure is reviewed by limit states of ultimate and serviceability. The solution includes time dependent analysis of the structure.

This thesis deals with options of laboratory heating of high voltage cables. First part of the work is reserved for description of heat as physical phenomenon and quantities connected with the heat. Second part deals with options of temperature measurements of objects in practical use and third part of the work deals with options of cables heating regarding the measurements according the ČSN rules. Practical part of diploma thesis is focused on physical phenomenon description, being under way during measurement using selected methods in individual components and optimization of results for practical measurements.

This master's thesis deals with the basic principles of slot antennas. Models of antennas were simulated in a selected electromagnetic simulator CST MICROWAVE STUDIO (CST MWS). There are several models of slot antennas which are optimized for communication in the car at a frequency 8 GHz.

I deal with the road bridge near Velké Meziříčí in the thesis. The highway bridge overcomes valley 360 m long and 36 m high. For each course there is a separate super-structure. Each of the support structures converts three stripes of road transport. I do calculation of internal forces both manually and in Scia Engineer. In the thesis is drawings, showing the gradual construction, diagram of prestressing and reinforcement.

The calculation of frequency-dependent cable parameters is essential for simulations of transient phenomena in electrical power systems. The simulation of transients is more complicated than the calculation of currents and voltages in the nominal frequency range. The model has to represent the frequency dependency and the wave propagation behavior of cable lines. The introduced model combines an improved subconductor method for the determination of the frequency-dependent parameters and a PI section wave propagation model. The subconductor method considers the skin and proximity effect in all conductors for frequency ranges up to few megahertz. The subconductor method method yields accurate results. The wave propagation part of the cable model is based on a cascaded PI section model. A modal transformation technique has been used for the calculation in the time domain. The frequency-dependent elements of the related modal transformation matrices have been fitted with rational functions. The frequency dependence of cable parameters has been reproduced using a vector fitting algorithm and has been implemented into an resistor-inductor-capacitor network (RLC network) for each PI section. The proposed full model has been validated with measured data.

The knowledge about the behavior of cables is substantial in cases of transients or in cases of faults. However, there are only a few models that are tailored to the current requirements for calculations of transient phenomena in three-phase cable systems. These models are based on complex structures. PI-section cable models with simple structures were previously qualified only for calculations in the frequency domain. A new full frequency-dependent cable model to simulate transient phenomena is introduced and validated. The model is based on lumped parameters with cascaded frequency-dependent PI-sections. For the implementation and the integration in simulation tools, it is important to investigate the impact of the PI-section parameters to the accuracy, the stability and the mathematical robustness. In this work, the impact of the frequency dependence of cable parameters, the length distribution and the number of PI-sections on the results of the developed three-phase cable model have been discussed. For simulations in the time domain, two algorithms have been presented to optimize the number of PI-sections based on a specified accuracy.

Density functional theory (DFT) calculations of polyethylene (PE) HVDC cable insulation have been performed for systems containing four different chemical impurities: acetophenone, cumene, $\alpha$-methyl styrene and $\alpha$-cumyl alcohol. Systems were generated by molecular dynamics (MD) equilibration at four different temperatures relevant for cable insulation applications: 277 K, 293 K, 343 K and 363 K. With the goal of gaining better measure of variations in hole and electron traps energies, four initial configurations were also stochastically generated at each temperature, which yielded four different final configurations after equilibration. The counterpoise correction scheme was implemented for DFT calculations, by distributing ghost atoms thought any empty pockets of space in between the PE chains. The PBE functional was selected for DFT simulations. The resulting band gaps were in agreement with those of earlier GGA-based studies, and thus lower by 3 eV than empirical band gaps. For all impurities, the first HOMO state and the first two LUMO states were generally located on the impurity molecule, forming one hole trap and two electron traps, but certain configurations generated increased electron trap numbers, or eliminated hole traps. No dependence could be derived between temperature and trap depth for either electron or hole traps. Mean electron trap energies were largely in agreement with results from earlier studies, they were deepest for acetophenone, and they varied by as much as 0.6 eV between different configurations. Hole traps are universally shallow and vary by up to 0.7 eV between configurations, and are similar in depth for all impurities. Results suggest that electron trap depths correlate with the presence of molecular features such as oxygen atoms and conjugated double bonds. The dependence of trap depth on the spatial configuration of the impurity molecule suggests that results could be improved by more precise quantum mechanical treatment of the dynamics of the impurity. / Täthetsfunktionalteori (DFT) har använts för beräkningar av isolering till HVDC kablar som består av polyeten innehållande fyra olika kemiska orenheter: acetofenon, kumen, alfa-metylstyren och alfa-kumylalkohol. System att studera genererades genom molekylärdynamisk ekvilibrering vid fyra olika temperaturer relevanta för tillämning till kabelisolering: 277 K, 293 K, 343 K och 363 K. För att få ett mått på de variationer som existerar i energierna på hål- och elektronfällor genererades stokastiskt fyra initialkonfigurationer vid varje temperatur, vilket fyra olika konfigurationer efter relaxering. Motviktskorrigering implementerades för DFT-beräkningar, genom att fördela "spökatomer" i de tomrum som bildas mellan PE-kedjorna i den amorfa fasen. PBE-funktionalen användes för DFT-simuleringar. De resulterande bandgapen stämde överens med tidigare GGA-baserade studier, och var därmed runt 3 eV smalare än empiriskt uppmätta bandgap. För alla orenheter var det första HOMO-tillståndet och de två första LUMO-tillstånden i allmänhet placerade på orenheten, vilket resulterade i en hålfälla och två elektronfällor, men vissa konfigurationer gav upphov till fler elektronfällor, eller eliminerade hålfällorna. Inget samband kunde härledas mellan temperaturen och djupet på fällorna för vare sig elektron- eller hålfällor. Medelvärdet på elektronfällornas energier överensstämde till stor del med resultat från tidigare studier, energierna var högst för acetofenon, och de varierade med så mycket som 0,6 eV mellan olika konfigurationer. Hålfällorna var genomgående grunda, varierade med upp till 0,7 eV mellan olika konfigurationer, och hade likartat djup för alla orenheter. Resultaten indikerar att variationerna elektronfällornas medeldjup uppstår på grund av orenheternas olika molekylära uppbyggnad: förekomst av syreatomer och konjugerade dubbelbindningar i orenheterna leder till djupare elektronfällor. Det faktum att djupet på elektron- och hålfällor varierar mellan olika rumsliga konfigurationer av av orenheten och polyetenstrukturen ger en antydan om att resultaten kan komma att förbättras om dynamiken hos orenheten simuleras med mer exakta kvantmekanisk metoder.

Thesis (MPhil)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The present thesis deals with the impact of the ancient Greek farce on modem literature with specific reference to the play Kinkels innie Kabel (1971) by the contemporary Afrikaans author André P. Brink. This play is loosely based on Shakespeare's The Comedy of Errors, which in tum derives from Plautus' Menaechmi. Brink's play thus resonates with an entire European tradition. The relationship between the modem and the ancient farce is studied with reference to the concept of comedy. Comic effects, the difference between comedy and tragedy in respect of the handling of vital issues and the comic vision of the playwright are all taken into account. The analysis of the development of Athenian Old Comedy to the Roman Comedy refers to the contribution of Plautus and Terence to the continuation and revitalisation of Greek New Comedy. A comparison of these two playwrights reveals the characteristics of the farce and the difference between farce and comedy. The modem relevance of the farce is studied on the basis of Brink's text. For this purpose Plautus' original plot, the Shakespearian version and Brink's rendition are discussed and compared. On the basis of the similarities and differences in plot, caricaturisation, misidentifications, politics, fantasy, coincidence, irony, farcical violence, mechanical structure, temporal structure and linguistic register, the influence of the ancient farce on its modem counterpart is demonstrated. In addition to farce, Brink employs the classical devices of satire and parody to drive home his (political) message. Finally it is shown that the farcical in Plautus, Shakespeare and Brink serves a significant and serious thematic purpose. / AFRIKAANSE OPSOMMING: Hierdie verhandeling handel oor die impak van 'n antieke Griekse komedievorm, die klug, op moderne werke en denke. A.P. Brink se verhoogstuk Kinkels innie Kabel (1971) is 'n vrye verwerking van William Shakespeare se The Comedy of Errors. Laasgenoemde werk is weer op sy beurt gebaseer op Plautus se Menaechmi. In sy verwerking van Plautus en Shakespeare laat A.P. Brink die hele Europese tradisie deurklink. Die verhouding tussen die moderne klug en die antieke klug word bestudeer deur te fokus op die term komedie: die verhouding daarvan met lag en hoe die komedie van die tragedie verskil ten opsigte van die hantering van lewensproblematiek en komiese visie van die komedieskrywer, maak deel uit van hierdie bespreking. Die komedie se herkoms en ontwikkeling vanaf die Ou Komedie tot die Romeinse Komedie, val ook onder die soeklig. In aansluiting hiermee word Plautus en Terentius bespreek as twee komedieskrywers wat 'n rol gespeel het in die oorlewering en verlewendiging van die Griekse Nuwe Komedie. Hierdie twee skrywers word ook met mekaar vergelyk sodat die eienskappe van die klug geïllustreer word, en hoe dit in wese verskil van komedie. Die relevansie van die klug in moderne denke word bestudeer aan die hand van Brink se teks. In hierdie verband word daar 'n uiteensetting gegee van die oorspronklike Plautiniese verhaal, die Shakespeariaanse weergawe en die Brinkiaanse teks. Aan die hand van die ooreenkomste en verskille in intrige, karikaturisering, identiteitsvergissings, politiek, die fantasie-element, toeval, ironie, klugtige geweld, die meganiese struktuur, die tydstruktuur en taalregister word die invloed van die antieke klug op die moderne klug geïllustreer. Benewens die klug word Brink se werk ook verder beïnvloed deur twee klassieke middele, met name satire en parodie. Hiermee bring Brink sy (politieke) boodskap tuis. Ten slotte word die dieperliggende temas in Plautus, Shakespeare en Brink se werk bespreek deur aan te toon dat die werk nie net om die klugtige gaan nie, maar ook die meer ernstige.

Nanocomposites of polyethylene and metal oxide nanoparticles have shown to be a feasible approachto the next generation of insulation in high voltage direct current cables. In order to reach an operationvoltage of 1 MV new insulation materials with reduced conductivity and increased breakdown strengthas compared to modern low-density polyethylene (LDPE) is needed.In this work polyethylene MgO nanocomposites for electrical insulation has been produced andcharacterized both from an electrical and material perspective. The MgO nanoparticles weresynthesized into polycrystalline nanoparticles with a large specific surface area (167 m2 g–1). Meltprocessing by extrusion resulted in evenly dispersed MgO nanoparticles in LDPE for the silane surfacemodified MgO as compared to the unmodified MgO. All systems showed a reduction in conductivityby up to two orders of magnitude at low loading levels (1–3 wt.%), but where the surface modifiedsystems were able to retain reduced conductivity even at loading levels of 9 wt.%. A maximuminteraction radius to influence the conductivity of the MgO nanoparticles was theoretically determinedto ca. 800 nm. The interaction radius was in turn experimentally observed around Al2O3 nanoparticlesembedded in LDPE using Intermodulation electrostatic force microscopy. By applying a voltage on theAFM-tip charge injection and extraction around the Al2O3 nanoparticles was observed, visualizing theexistence of additional localized energy states on, and around, the nanoparticles. Ptychography wasused to reveal nanometre features in 3D of electrical trees formed under DC-conditions. Thevisualization showed that the electrical tree grows by pre-step voids in front of the propagatingchannels, facilitating further growth, much in analogy to mechanical crack propagation (Griffithconcept). An electromechanical effect was attributed as possible mechanism for the formation of the voids. / Nanokompositer av polyeten och metalloxidpartiklar anses vara möjliga material att använda i morgondagens isolationshölje till högspänningskablar för likström. För att nå en transmissionsspänning på 1 MV behövs isolationsmaterial som i jämförelse med dagens polyeten har lägre elektrisk ledningsförmåga, högre styrka mot elektriskt genomslag och som kan kontrollera ansamling av rymdladdningar. De senaste årens forskning har visat att kompositer av polyeten med nanopartiklar av metalloxider har potential att nå dessa egenskaper. I det här arbetet har kompositer av polyeten och nanopartiklar av MgO för elektrisk isolation producerats och karaktäriserats. Nanopartiklar av MgO har framställts från en vattenbaserad utfällning med efterföljande calcinering, vilket resulterade i polykristallina partiklar med en mycket stor specifik ytarea (167m2 g-1). MgO-nanopartiklarna ytmodifierades i n-heptan genom att kovalent binda oktyl(trietoxi)silan och oktadekyl(trimetoxi)silan till partiklarna för att skapa en hydrofob och skyddande yta. Extrudering av de ytmodifierade MgO nanopartiklarna tillsammans med polyeten resulterade i en utmärkt dispergering med jämnt fördelad partiklar i hela kompositen, vilket ska jämföras med de omodifierade partiklarna som till stor utsträckning bildade agglomerat i polymeren. Alla kompositer med låg fyllnadsgrad (1–3 vikt% MgO) visade upp till 100 gånger lägre elektrisk konduktivitet jämfört med värdet för ofylld polyeten. Vid högre koncentrationer av omodifierade MgO förbättrades inte de isolerande egenskaperna på grund av för stor andel agglomerat, medan kompositerna med de ytmodifierade fyllmedlen som var väl dispergerade behöll en kraftig reducerad elektrisk konduktivitet upp till 9 vikt% fyllnadshalt. Den minsta interaktionsradien för MgO-nanopartiklarna för att minska den elektriska konduktiviten i kompositerna fastställdes med bildanalys och simuleringar till ca 800 nm. Den teoretiskt beräknade interaktionsradien kompletterades med observation av en experimentell interaktionsradie genom att mäta laddningsfördelningen över en Al2O3-nanopartikle i en polyetenfilm med intermodulation (frekvens-mixning) elektrostatisk kraftmikroskop (ImEFM), vilket är en ny AFM-metod för att mäta ytpotentialer. Genom att lägga på en spänning på AFM-kantilevern kunde det visualiseras hur laddningar, både injicerades och extraherades, från nanopartiklarna men inte från polyeten. Det tolkades som att extra energinivåer skapades på och runt nanopartiklarna som fungerar för att fånga in laddningar, ekvivalent med den gängse tolkningen att nanopartiklar introducera extra elektronfällor i den polymera matrisen i nanokompositer. Nanotomografi användes för att avbilda elektriska träd i tre dimensioner. Avbildningen av det elektriska trädet visade att tillväxten av trädet hade skett genom bildning av håligheter framför den framväxande trädstrukturen. Håligheterna leder till försvagning av materialet framför det propagerande trädet och förenklar på det sättet fortsatt tillväxt. Bildningen av håligheter framför trädstrukturen uppvisar en analogi till propagering av sprickor vid mekanisk belastning, i enlighet med Griffiths koncept. / <p>QC 20161006</p>

The main topic of this work is the analysis of the measurement of partial discharge measurements on high voltage cables. The thesis also deals with other measurements, including the measurement of the loss factor and the voltage retention and breakdown test. Part of the text describes the issue of partial discharge, its measurement by galvanic method and methods of elimination of disturbing influences that affect this method in terms of sensitivity and accuracy of the measured values. Thesis also describes the construction of the cables, their marking and the tests carried out on them. There is also a description of the cable terminals used for measuring, especially water terminals, which are designed for high voltages and which are carried out in the practical part of the thesis. The next part deals with problems prior to the commissioning of water terminals and their preparation for certain tests, including description and evaluation of the results of the measurements.