Quintic abelian fields are characterized in terms of their conductor and a certain Galois group. From these, a generating polynomial and its roots and an integral basis are computed. A method for finding the fundamental units, regulators and class numbers is then developed. Tables listing the coefficients of a generating polynomial, the regulator, the class number, and a coefficients of a fundamental unit are given for 1527 quintic abelian fields. Of the seven cases where the class group structure is not immediate from the class number, six have their structure computed. / Ph. D.

Master's thesis deals with principles of design of earthing of a substation 110/22 kV. Specific requirements for safety have to be fulfilled when designing power installations exceeding 1kV. The aim of this paper is to design a new earthing system for reconstructed substation 110/22kV considering valid standards. Reconstruction of a property is always more or less complicated by new orders and regulations for construction. Earthing is a part of all electric equipment, therefore it is essential for the design engineer to consider a broad spectrum of requirements, even those seemingly not related to this subject, from legislative requirements to the study of reactions of a human body to electric current. The theoretical part of this work examines different approaches to earthing system's design, and analyzes the origins and earthing standards throughout history. The correctness in consideration of effects of the environment is an often neglected factor. Defining of all types of effects of the environment is a broad field, therefore this paper only summarizes the main principles. The practical part of this paper deals with the basic design of substation's earthing system and it's verification in respect of touch voltage and step voltage according to the Czech national standard ČSN 33 3201 (Power installations exceeding 1kV a.c.) and of company's energetics' standard PNE 33 0000-1 ed.4 (Protection against electric shock in distribution network and transmission system) required by the substation's distributor. This paper later quotes and takes into consideration the requirements of other standards, more or less related to listed documents, creating an interconnected body for design and testing the earthing system.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This paper presents the implementation of an artificial magnetic ground-plane with a low profile Log-periodic Dipole Array (LPDA) antennas. After the properties of three typical Electromagnetic Bandgap (EBG) structures are investigated and their bandwidth properties are studied, a mechanism is presented to improve the band-width over which the EBG surface acts as a perfect magnetic conductor (PMC). A low profile LPDA is modeled above this surface and the results indicate an improved band-width region. Compared with a LPDA in free space the frequency band is shifted higher by the EBG surface and the gain pattern is shifted from a horizontal orientation to a vertical orientation. / AFRIKAANSE OPSOMMING: Hierdie dokument stel voor die implementering van kunsmatige magnetiese grondvlakke met Logaritmiese Periodiese Dipool Samestelling (LPDS) antennas. Die eienskappe van drie tipiese Elektromagnetiese Bandgaping (EBG) strukture word ondersoek en hul bandwydte eienskappe word bestudeer. ’n Meganisme word voorgestel om die bandwydte te verbeter waar die EBG oppervlakte soos n perfekte magnetiese geleier optree. ’n Lae profiel LPDS word bo hierdie oppervlakte geplaas. Die resultate dui aan ’n verbetering in the bandwydte. In vergelyking met ’n LPDS in vrye ruimte skuif die frekwensie band ho¨er as gevolg van die EBG oppervlakte en die aanwins patroon skuif van ’n horisontale orientasie na ’n vertikale orientasie.

The landscape of consumer electronics has drastically changed over the last decade. Technological advances have led to the development of portable media devices, such as the iPod, smart phones and laptops. This has been achieved primarily through miniaturisation and using materials such as Lithium and Indium Tin Oxide (ITO) to increase energy density in batteries and as transparent electrodes for light emitting displays respectively. However, ten years on there are now new consumer demands, which are dictating the direction of research and new products are under constant development. Graphene is a promising next-generation material that was discovered in 2004. It is composed of a two-dimensional lattice made only from carbon. The atoms are arranged in a two atom basis hexagonal crystal structure which forms a fundamental building block of all sp2 hybrid forms of carbon. The production of large area graphene has a high cost, due to the long growth times and the high temperatures required. This is relevant as graphene is not viable compared to other transparent conductors which are produced on industrial scales for a fraction of the cost of graphene growth. Furthermore, graphene has a high intrinsic resistivity (2KW/_) which is three orders of magnitude greater than the current industry standard ITO. This limits the size of the electrodes as there is dissipation of energy across the electrode leading to inefficiency. Furthermore a potential drop occurs across the electrode leading to a non-uniform light emission when the electrode is used in a light emitting display. I investigate alternative methods of large area graphene growth with the aim of reducing the manufacturing costs, while maintaining the quality required for graphene human interface devices. Building on this I develop new fabrication methods for the production of large-area graphene devices which are flexible and transparent and show the first all graphene touch sensor. Focusing on the reducing the high resistivity of graphene using FeCl3 intercalation, while maintaining high optical transmission, I show low resistivity achieved using this process for microscopic graphene flakes, large-area graphene grown on silicon carbide and large-area graphene grown by CVD. Furthermore, I explore the stability of FeCl3 intercalated graphene and a process to transfer a material to arbitrary flexible substrates.

Dans cette thèse, on étude le complexe des cycles proches d'un faisceau l-adique sur un schéma au-dessus d'un trait en utilisant la théorie de ramification d'Abbes et Saito. La première partie est consacrée à une nouvelle preuve d'une formule de Deligne et Kato qui calcule la dimension du complexe des cycles proches d'un faisceau l-adique sur une courbe relative lisse au-dessus d'un trait strictement local. Deligne a considéré le cas où le faisceau n'a pas de ramification verticale, et Kato a traité le cas général. Notre approche est basée sur une notion locale de cycle caractéristiquedéfinie grâce au conducteur de Swan raffiné d'Abbes et Saito. Dans la deuxième partie, on démontre une formule qui calcule le conducteur de Swan de la cohomologie du complexe des cycles proches d'un faisceau l-adique sur une variété lisse au-dessus d'un trait d'égale caractéristique, vérifiant une certaine condition de ramification. Tsushima a introduit la classe caractéristique raffinée du faisceau et il a démontré qu'elle calcule le conducteur de Swan de la cohomologie du complexe de ses cycles proches par une formule du type Lefschetz-Verdier. On calcule la classe caractéristique raffinée comme un produit d'intersection sur le fibré cotangent logarithmique de la variété faisant apparaître le cycle caractéristique du faisceau défini par Abbes et Saito et la section nulle. / In this thesis, we study the nearby cycle complex of an l-adic sheaf on a scheme over a trait, using ramification theory of Abbes and Saito. The first part is devoted to a new proof of a formula of Deligne and Kato that computes the dimension of the stalks of the nearby cycle complex of an l-adic sheaf on a smooth relative curve over a strictly local trait. Deligne considered the case where the sheaf has no vertical ramification and Kato extended the formula to the general case. Our approach is based on a local notion of characteristic cycle defined using the refined Swan conductor of Abbes and Saito. In the second part, we prove a formula that computes the Swan conductor of the cohomology of the nearby cycle complex of an l-adic sheaf on a smooth variety over a trait of equal characteristic, satisfying a certain ramification condition. Tsushima introduced the refined characteristic class of the sheaf and he proved that it computes the Swan conductor of the cohomology of its nearby cycle complex by a Lefschetz-Verdier type formula.We compute the refined characteristic class as an intersection product on the logarithmic cotangent bundle of the variety, involving the characteristic cycle of the sheaf defined by Abbes and Saito and the zero section.

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My recent engagement as music director and conductor of Robert Nelson’s A Room with a View (1992, rev. 2004) has offered me the valuable opportunity to work on an opera side by side with its composer. The purpose of this dissertation is to reconstruct the various stages of the process of creation, interpretation, and performance of a contemporary opera, addressing aspects of the collaboration between the composer and the conductor. The methodology used in my research is based primarily on direct observation and interview. The investigation is conducted from the perspective of a “participant-observer,” due to my personal involvement in the project, as music director and conductor first, and then as interviewer and researcher. The document will be organized in three sections: - the first chapter will establish the context and specific features of my research, providing a scholarly background in relation to the study of the relationship between composer and conductor; - the second chapter will focus on the process of composition in all its stages. I have defined this as the “extended creative process” of A Room with a View; - the third chapter will discuss the Michigan State University production of the opera, considering several aspects of the artistic collaboration between Robert Nelson and me, as well as my involvement in the process as conductor. Through my research, I wish to provide useful insight into the crucial aspects of the composition and the production of new music. In addition, the project aims to offer a fresh contribution to the investigation of the relationship between composers and interpreters, and perhaps could provide some background reference for an interrogation about the current state and the future of American opera.

Power system fault detection is conventionally achieved using current and potential measurements. An alternate and unconventional form of protective relaying is feasible using rigid bus conductor motion as the means of detection. The research presented focuses on the detection of power system faults using visual displacement of conductor spans. Substation rigid bus conductor motion is modeled using dual spring-mass systems for accurate representation of conductor response to electromagnetic forces generated during system faults. Bundled rigid conductors have advantages including detection independent of system load currents and improved ability to detect polyphase and single phase faults. The dynamic motion of the conductors during the fault is optically monitored with a laser detection system. Timeovercurrent characteristics are derived for the application of fault detection. The response time of the conductor detector system is slower than conventional relays due to the natural frequencies of the conductor span limiting the speed of its displacement. This response time makes the fault detection system using conductor displacement an ideal candidate for a backup relay in power system protection schemes.

RSAT (Reticulation Sag And Tension) software is a tool available for use as part of the medium voltage Eskom Distribution standard. This software is scrutinised for its usability and for errors such that it can be revised to improve the usability of the tool. The type of software being studied is used to ensure optimum design performance and reduce the probability of a conductor failure on distribution lines. The algorithms for calculating tension, sag and clearance values take into account research into optimum design tensions. This ensures low bending forces due to conductor vibration. An algorithm for creep is designed based on common life expectancy of line conductors. The design methodology and algorithms were then put into software form as RSAT. Review and alterations include the changing of compiler, user interface, data storage mechanisms and the inclusion of options allowing the addition of new data.