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Minnaar, Ulrich. "The characterisation and automatic classification of transmission line faults." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9287.
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Includes bibliographical references.A country's ability to sustain and grow its industrial and commercial activities is highly dependent on a reliable electricity supply. Electrical faults on transmission lines are a cause of both interruptions to supply and voltage dips. These are the most common events impacting electricity users and also have the largest financial impact on them. This research focuses on understanding the causes of transmission line faults and developing methods to automatically identify these causes. Records of faults occurring on the South African power transmission system over a 16-year period have been collected and analysed to find statistical relationships between local climate, key design parameters of the overhead lines and the main causes of power system faults. The results characterize the performance of the South African transmission system on a probabilistic basis and illustrate differences in fault cause statistics for the summer and winter rainfall areas of South Africa and for different times of the year and day. This analysis lays a foundation for reliability analysis and fault pattern recognition taking environmental features such as local geography, climate and power system parameters into account. A key aspect of using pattern recognition techniques is selecting appropriate classifying features. Transmission line fault waveforms are characterised by instantaneous symmetrical component analysis to describe the transient and steady state fault conditions. The waveform and environmental features are used to develop single nearest neighbour classifiers to identify the underlying cause of transmission line faults. A classification accuracy of 86% is achieved using a single nearest neighbour classifier. This classification performance is found to be superior to that of decision tree, artificial neural network and naïve Bayes classifiers. The results achieved demonstrate that transmission line faults can be automatically classified according to cause.
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Johansson, Christian, and Marcus Karlsson. "Characterisation of a data transmission link." Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2359.
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This report is the result of a Master Thesis work that has been performed between October 2003 and March 2004. The purpose of the work was to evaluate a part of the signal chain in a product of Micronic Laser Systems AB. The evaluation was performed to obtain the characterisation for the signal chain, such as impedances and crosstalk.
The work started with a literature study in order to refresh and increase the knowledge that was needed before the practical work. Then measurements, computer aided simulations and comparisons between these were performed.
Measurements were performed using TDR (Time Domain Reflectometry). The results showed the impedance levels along the signal chain. This was interesting since it showed how well the different parts in the system are matched. Unmatched parts result in reflections that disturb the transmitted signal and contribute to crosstalk, which also was measured.
Simulations were done using ADS (Advance Design System), a tool from Agilent Technologies Inc. A substantial part of the simulation work was to build models of the real system. These models have been used for simulation. The simulation results were then compared to the measurement results.
The results show that the system can be better matched concerning the channel impedance. There are large variations in impedance levels along the signal chain, resulting in signal reflections. Another effect studied is crosstalk between channels. Measurements and simulations showed the presence of crosstalk but it seems to be a minor problem in the current machine.
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Rossi, Jose Osvaldo. "Transmission line transformers." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284500.
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KLAUSNER, JEREMIAS CORAL. "TRANSMISSION LINE MODEL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1992. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8740@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste trabalho apresenta uma metodologia para simulação de linhas de transmissão, geradores, interconexões e cargas por modelos baseados em filtragem digital. Estes modelos usam de maneira intensiva o conceito de redes digitais equivalentes, para resolver problemas aliados à responsabilidade dos filtros digitais em redes onde haja interconexão de elementos, desde simples cargas a subredes. O resultado deste trabalho é um sistema que representa de maneira quase que integral o espectro do sinal discretizado, em contraposição aos métodos tradicionalmente encontrados na simulação de sistemas deste tipo por computador digital. Por outro lado o processo é facilmente implementado por processadores digitais de sinal (DSPs), resultado em simulações em tempo rela comparáveis a simulações off-line por aplicativos
This thesis introduces a metodology for the simulation of transmission lines, power generators, interconnnections and loads, base don digital filtering models. These models make intensive use of digital equivalent network concepts in order to solve the computability problem of the digital filter. The result of this work is a system that represents the discrete-time signal on a bandwsiths covering up to the Nyquist frequency, in contraposition with traditional methods of computer simulation. The structure is easily implemented with Digital signal Processors (DSPs), resulting in real time simulations that compare to off-line circuit simulators in precision.
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Lapohos, Tibor. "Multiconductor transmission line networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0012/NQ31123.pdf.
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Becker, Matthew E. (Matthew Erin). "Resonant transmission line drivers." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/81519.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaves 71-72).
by Matthew E. Becker.
Ph.D.
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Cooke, Bradly James. "S-parameter VLSI transmission line analysis." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184876.
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This dissertation investigates the implementation of S-parameter based network techniques for the analysis of multiconductor, high speed VLSI integrated circuit and packaging interconnects. The S-parameters can be derived from three categories of input parameters: (1) lossy quasi-static R,L,C and G, (2) lossy frequency dependent (dispersive) R,L,C,G and (3) the propagation constants, Γ, the characteristic impedance, Z(c) and the conductor eigencurrents, I, derived from full wave analysis. The S-parameter network techniques developed allow for: the analysis of periodic waveform excitation, the incorporation of externally measured or calculated scattering parameter data and large system analysis through macro decomposition. The inclusion of non-linear terminations has also been developed.
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Ahmeda, Mohammad. "Earthing performance of transmission line towers." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/42730/.
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This work is primarily concerned with the performance of tower base earthing systems under AC variable frequency and transient conditions. The work has involved the investigation into the performance of practical earthing systems including tests on a full-size 275kV transmission tower base and corresponding calculation and numerical simulations.
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Kang, Ning. "ADVANCEMENTS IN TRANSMISSION LINE FAULT LOCATION." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/69.
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In modern power transmission systems, the double-circuit line structure is increasingly adopted. However, due to the mutual coupling between the parallel lines it is quite challenging to design accurate fault location algorithms. Moreover, the widely used series compensator and its protective device introduce harmonics and non-linearities to the transmission lines, which make fault location more difficult. To tackle these problems, this dissertation is committed to developing advanced fault location methods for double-circuit and series-compensated transmission lines.
Algorithms utilizing sparse measurements for pinpointing the location of short-circuit faults on double-circuit lines are proposed. By decomposing the original network into three sequence networks, the bus impedance matrix for each network with the addition of the fictitious fault bus can be formulated. It is a function of the unknown fault location. With the augmented bus impedance matrices the sequence voltage change during the fault at any bus can be expressed in terms of the corresponding sequence fault current and the transfer impedance between the fault bus and the measured bus. Resorting to VCR the superimposed sequence current at any branch can be expressed with respect to the pertaining sequence fault current and transfer impedance terms. Obeying boundary conditions of different fault types, four different classes of fault location algorithms utilizing either voltage phasors, or phase voltage magnitudes, or current phasors, or phase current magnitudes are derived. The distinguishing charactristic of the proposed method is that the data measurements need not stem from the faulted section itself. Quite satisfactory results have been obtained using EMTP simulation studies.
A fault location algorithm for series-compensated transmission lines that employs two-terminal unsynchronized voltage and current measurements has been implemented. For the distinct cases that the fault occurs either on the left or on the right side of the series compensator, two subroutines are developed. In additon, the procedure to identify the correct fault location estimate is described in this work. Simulation studies carried out with Matlab SimPowerSystems show that the fault location results are very accurate.
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Lowery, A. J. "Transmission line modelling of semiconductor lasers." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384697.
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Batty, Eric Richard. "A novel transmission line monitoring method." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326654.
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Dulmage, Andrew. "Low cost automatic transmission line sectionalizing." Connect to resource, 2009. http://hdl.handle.net/1811/44545.
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Martini, Pietro. "Live-line working and evaluation of risk on 400kV transmission line." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/liveline-working-and-evaluation-of-risk-on-400kv-transmission-line(b19247d6-22cc-4815-b865-d80a957dfd7b).html.
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Power industries in transmission and distribution level are obligated to maintain and replace their electrical equipment. Maintaining the quality and continuity of supply is their priority to avoid customers' complaints and financial penalisation. Live-line working as one of the most important methods of maintenance has been used since the 1900s where the new methods in 1960s made the live-line workers enabled to work on the higher voltage levels up to 800kV. Various industries adopt different techniques to calculate the minimum approach distance (MAD) during the live-line work. A suitable method reduces the risk to live-line workers and provides adequate safety distances between the live parts and linesmen. Therefore, setting an appropriate safety distance between the linesmen and live parts ensures the safety of the workers and minimise the risk of flashover. In this thesis, different methods of calculation of the minimum approach distance are described, and results from overvoltage simulations are used as an input to the methodology outlined in IEC 61472. Also, this thesis highlights and investigates the impact of a range of factors within 400kV transmission line on the minimum approach distance (MAD). Factors examined include the time to crest of the overvoltage (wave shape), the fault type, the probability of occurrence of each type of fault, fault level and the type of overhead line and towers. Furthermore, the minimum approach distances and also associated risk due to each factor and scenario have been calculated. The calculated risk in this thesis presents the risk of failure of a gap against the switching overvoltages due to the simulation of sources of overvoltage. A new set of estimated equations is developed to consider the influence of wave shape in the calculation of the minimum approach distance (MAD). This thesis does not propose a method to replace the international standards, but it could be used in many situations including where utility companies wish to develop a complete understanding of the risk associated with live-line working. Calculation of the minimum approach distance (MAD) within the National Grid UK is based on the methodology described in the IEC 61472, whereas EDF Energy uses the IEEE method to calculate the minimum approach distance. The choice of a smaller / larger minimum approach distance (MAD) using different methods will have an impact on the risk associated with live-line working. Previous works intend to investigate the magnitude of switching overvoltages on one part of a network and calculate the appropriate minimum approach distance for the work in that section. This work is based on the examination of the switching overvoltages under the worst case scenarios. As a result, the simulated overvoltages in this work are higher than expected overvoltages in National Grid network. Also as in practice, the magnitude of switching overvoltages in National Grid network is controlled by different protections equipment therefore, the simulated results and the calculated minimum approach distances in this work are very conservative.
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Zhang, Yucheng. "Characterisation of GaN using transmission electron microscopy." Thesis, University of Cambridge, 2008. https://www.repository.cam.ac.uk/handle/1810/252119.
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Robinson, Robert Allen. "An Electroacoustic Analysis of Transmission Line Loudspeakers." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14579.
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The concept of mounting a loudspeaker on one end of a sound-absorbing tube has existed since at least 1936. Surprisingly, a detailed mathematical analysis of the configuration has not been performed, nor has a design method been established. This configuration, known as a transmission line loudspeaker, has received little consideration in the reviewed literature. Instead, it has become frequently featured in magazines for audio hobbyists, where it is experimentally designed with rules seemingly derived from hearsay and described with terms of high praise. In this dissertation, an electro-acoustical model of a fiberglass-filled transmission line is presented. This model represents the transmission line as two separate lines -- a mechanical line that models the mechanical motion of the fiberglass and an acoustical line that models the motion of the air. The lines are linked by the flow resistance of the fiberglass. From the model, solutions for the acoustic pressure, acoustical volume velocity of the air, mechanical velocity of the fiberglass fibers, and mechanical force on the fiberglass in the line are obtained. The fiberglass is characterized and empirical formulas that describe its characteristics are found. It is shown that the modeled input impedance to the transmission line is a good fit to measured data. The performance of the system is assessed by comparing it with the performances of typical loudspeaker mountings, i.e., the infinite baffle, the closed box, and the vented box. Finally, an example is shown of how the equations derived from the model can be used to evaluate the design of a transmission line loudspeaker system.
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Adebisi, Bamidele. "Broadband Transmission over indoor Power-line channels." Thesis, Lancaster University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536027.
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Chakrabarti, Abhimanyu. "Transmission line matrix modelling for semiconductor transport." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338228.
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Chen, Dian. "Transmission line modelling (TLM) of physical systems." Thesis, University of Sheffield, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361632.
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DOMINGUES, LUIS ADRIANO DE MELO CABRAL. "MODEL FOR TRANSMISSION LINE CONDUCTORS TEMPERATURE FORECASTING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2748@1.
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CENTRO DE PESQUISA DE ENERGIA ELÉTRICAAs linhas de transmissão têm um papel fundamental no funcionamento do sistema elétrico, efetuando a ligação entre as usinas geradoras e os centros de carga. Quando o sistema de transmissão atinge sua capacidade limite de transferência de potência torna-se necessário expandir o sistema, quer construindo novas linhas quer aumentando a capacidade das existentes. Entre os fatores que limitam a capacidade de transporte de uma linha destaca-se a sua temperatura limite de operação, estabelecida por questões econômicas e de segurança. Pela sua extensão geográfica, a construção de uma linha de transmissão envolve tanto um custo quanto um impacto ambiental elevados. Por estes motivos a recapacitação de linhas existentes, no sentido de aumentar sua capacidade de transporte, tornou-se um assunto prioritário e uma opção estratégica para expansão do sistema elétrico. Neste trabalho analisa-se o problema da temperatura de operação dos condutores de linhas aéreas de transmissão. Descreve-se a metodologia atualmente utilizada para definir o limite operativo das linhas, destacando-se a possibilidade de aumentar sua capacidade limite pelo conhecimento mais preciso da temperatura de operação dos seus condutores.Descreve-se o desenvolvimento de uma série de dois modelos para previsão da temperatura de operação de condutores, um modelo completo, baseado em previsões das diversas variáveis meteorológicas e um modelo direto de previsão que utiliza as séries de valores de temperatura. No desenvolvimento dos modelos de previsão foram utilizados modelos estocásticos, lineares, de amortecimento exponencial e Box-Jenkins e técnicas de Redes Neurais Artificiais. Apresenta-se uma série de testes de validação, que mostram um desempenho muito bom dos métodos de previsão, e ilustra-se as possibilidades de aplicação dos modelos desenvolvidos.
Transmission lines have a fundamental role in the electric system performance,connecting power sources to load centers. When the transmission system attains it`s transmission capability limit, the system must be expanded, either constructing new lines, or upgrading existing ones. Among the factors that can limit a transmission line transfer capability is the operating temperature limit, established for both economic and safety reasons. Due to its geographic extension the construction of a transmission line involves a big economic as well as environmental cost. For this reasons the upgrade of existing lines, in the sense of increasing it`s transmission capability, has become a priority to electric utilities and a main option for system expansion. In this work the problem of transmission line conductors` operational temperature is analised and the methodology presently used to establish it`s operational limit is described. Two models to forecast transmission line conductors` temperature are developped:a complete model which uses forecasts of the relevant metheorological variables,and a direct model using univariate methods on temperature series. In the development of forecasting models, linear stochastic methods such as exponential smoothing and Box-Jenkins, as well as Artificial Neural Networks techniques were used.Finally model validation is presented, showing very good performance of the proposed forecasting models, and some potential applications are suggested.
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DEMENICIS, LUCIENE DA SILVA. "TRANSMISSION LINE TRANSFORMER FOR HIGHSPEED OPTOELECTRONIC DEVICES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5576@1.
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ERICSSON DO BRASILA utilização de transformadores de impedância banda larga possibilita o acoplamento de forma eficiente das linhas convencionais de 50 (ômegas) dos sistemas de alta freqüência aos componentes optoeletrônicos de alta velocidade de baixa impedância, tais como lasers semicondutores (tipicamente com 3 a 5 (ômegas) de resistência de entrada). Uma das principais restrições para a realização de um transformador de impedância planar para uso em sistemas de comunicações ópticas é a sua dimensão física. A fim de se obter um transformador de impedância compacto, de dimensões compatíveis com às dos dispositivos optoeletrônicos, foram analisadas diferentes configurações. Inicialmente foi analisada a configuração coplanar (CPW) utilizando substrato de altíssima constante dielétrica. Devido às limitações encontradas nesta configuração, são propostas, aqui, duas outras soluções. As duas novas configurações propostas associam ao substrato bulk convencional de alumina, filmes de elevada constante dielétrica. Foi desenvolvida uma técnica para caracterizar a constante dielétrica e as perdas dos filmes especialmente fabricados para este trabalho. As análises teóricas mostraram que as configurações propostas apresentam desempenho muito superior ao desempenho das configurações convencionais CPW. Foi implementado o transformador de impedância utilizando uma das soluções propostas e seu desempenho foi avaliado experimentalmente.
Wide-band transmission line impedance transformer enables efficient coupling of 50 (ômegas) transmission line circuits to low impedance high-speed optoelectronic components such as semiconductor lasers (typically with input resistance of 3 to 5 [ômegas]). The physical dimensions of the planar transmission line transformer have to be properly chosen to allow its use in optical communication systems. In order to design a high performance impedance transformer with physical dimensions compatible with optoelectronic components, several possibilities were investigated. A CPW configuration with very high dielectric constant bulk substrate has been analyzed. Simulations have shown some limitations in the performance of this configuration. Then, two new configurations were introduced. Both configurations are obtained using high dielectric constant films and alumina bulk substrate. A new technique has been developed in order to characterize the dielectric constant and the losses of the films specially made for this thesis. Simulations have shown that the performance of both new configurations is much better than the conventional CPW configuration performance. The planar transmission line impedance transformer has been constructed using a new configuration and its performance has been experimentally evaluated.
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Alavi, Hessam. "Acoustics of high performance transmission-line loudspeakers." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/388041/.
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Acoustically treated, lined ducts are used in a wide range of applications, one of which is a transmission-line loudspeaker (TLL), which consists of a long, acoustically-lined, folded duct attached to the rear of the loudspeaker driver. Consequently, knowledge and understanding of sound propagation within acoustically treated ducts is essential in order to be able to create and analyse designs for the intended applications. The lowfrequency driver of a loudspeaker creates pressure fluctuations on both sides of the diaphragm. Therefore, a loudspeaker cabinet of some sort is required to control the sound radiation from the rear of the driver and to prevent the unwanted interference of those sounds with that radiated from the front of the loudspeaker. The transmission-line loudspeakers are however, designed and optimized to control this rear driver radiations by redirecting the pressure at the back of the driver and use them to extend the overall low-frequency response of the loudspeaker system. Transmission-line loudspeakers rely on the use of sound absorbing materials and, although attempts at modelling the performance of these have been reported in the literature, most transmission-line loudspeakers are designed empirically, using a combination of experience and trial-and-error. This project is concerned with creating and evaluating an engineering method of accurately modelling the sound propagating inside the transmission-line loudspeaker waveguides. Loudspeaker systems inherently suffer from an insufficient low-frequency response, due to their inefficiency at low-frequencies. Therefore, TLL rely on the use of sound absorbing materials added on their internal boundaries to extend their overall response of the loudspeaker at the lowfrequency region. The acoustic load on the driver and the sound radiated from the open end of the TLL duct both depend upon the propagation of sound through the duct; and the physical length of the duct determines the frequencies that can propagate within it. The addition of sound absorbing materials along the interior boundaries of the TLL reduces the speed of propagating sound within it, causing the TLL to respond such as having a much longer internal waveguide, consequently accommodating far lower frequencies within the TLL duct, extending the overall response of the loudspeaker system. The characteristics of sound propagation through a variety of two-dimensional and three-dimensional acoustically lined ducts at low-frequencies have been analyzed. Analytical models of straight ducts have been compared with the developed numerical models. In this research dissipative mufflers, that consist of ducts lined on the inside with an acoustically absorptive material, have been considered. Starting with the propagation of sound within hard-walled boundary condition ducts, this investigation moves to the modelling of waveguides treated with locally-reacting acoustic liners and next into the analysis of ducts treated with bulk-reacting acoustic absorbent materials; two kinds of excitations have been considered, namely pistonic and non-uniform excitation. The impedance mismatch and acoustic dissipation between the sound absorbing layer and the free propagation within the duct has been modelled numerically, and the results have been compared with the in-situ measurements conducted on a range of acoustically treated and purpose built transmission-line loudspeakers. A wide range of sound absorbing materials, namely fibrous and porous absorbers, have been characterized using their low-resistivity and acoustic impedance. Based on their individual characteristics, acoustical optimization was applied on a simple geometry U-shaped TLL duct.
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McLaren, Mathew Jonathon. "Transmission electron microscope characterisation of iron-rhodium epilayers." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/8281/.
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Iron-rhodium (FeRh) alloys exhibit an unusual magnetostructural transition, making them a fascinating topic of research. When the alloy is approximately equiatomic (Fe48Rh52 to Fe56Rh44) it is in a caesium chloride (CsCl) structure. At room temperature it is antiferromagnetic (AFM), making a first-order phase transition to a ferromagnetic (FM) state when heated above ~350K. There is also a 1% increase in unit lattice volume upon heating to the FM phase, as well as an increase in entropy and decrease in resistivity. The transition can be modified by doping, applied strain and applied magnetic field among other methods. Thin film FeRh has potential uses as part of a spin valve system for magnetic data storage and as a suitable choice for a memristor. The work presented here demonstrates the methods approached to preparing a variety of sputter-deposited thin film FeRh samples for characterisation in a transmission electron microscope (TEM) as well as by techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). These include samples capped with epitaxial chromium (Cr) and tungsten (W) to raise and lower the transition temperature respectively. After cross-section or plan-view preparation using either a conventional ion polishing method or a focused ion beam, the samples were characterised using a variety of methods in the TEM. Initial characterisation has examined the crystal structure, layer thickness and interfacial roughness of these films, confirming results from bulk X-ray measurements. It has been found that FIB-prepared samples do not exhibit the phase transition whereas ion polished samples are unaffected. Compositional analysis of the interface FeRh makes with a magnesium oxide (MgO) substrate finds a change in iron-to-rhodium ratio while characterising the FeRh/cap interface finds significant Fe diffusion into Cr-capped samples with no interdiffusion seen in identical W-capped FeRh films. Analysis of the transition dynamics observing changes in strain and ferromagnetic domains via heating experiments have confirmed the nucleation and growth of the phase change at the interfaces. Finally, there is some evidence to suggest that a martensitic change is occurring in FeRh through the transition. The presence of twins in the FeRh as well as extra ordering spots in a FIB-prepared cross-section allude to a more complex transition than previously thought.
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Boonkhao, Bundit. "On-line characterisation techniques for manufacture of nanomaterials." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540791.
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Boda, Pranav. "Effects of global warming on transmission line sag." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5377.
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Global warming has forced the power industry to adapt its infrastructure and develop technology in order to mitigate the effects and reduce the extent to which it will affect the operation of the electrical grid. With this goal in mind, the project attempts to quantify the effect of global warming on transmission line sag. First, a climate model that could predict temperature data for the time period (2001-2100) was needed. Next, a relationship between temperature and electricity demand needed to be quantified. Using this relationship and the temperature values generated by the climate model, the predicted electricity demand values were calculated for the examined time period. Since the voltage at which power is transported remains constant, the rate at which power is delivered will be given by the current flowing through the conductor. Using the estimated current values, the temperature of the conductor was calculated. This value is then used to calculate incremental sag due to the additional electrical demand.
The calculated incremental sag is then plotted across time to show the increase in sag as temperatures increase. The plots also show various spikes in transmission line sag values ranging from less than an inch to just over two inches over the examined time period which does not significantly affect the operation of the grid. However, the project was performed using ideal values and is only a best case scenario. Overall, the project was successful in establishing that a relationship between global warming and transmission sag does exist, and that it needs to be addressed during future infrastructure planning.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Cokkinides, George J. "Frequency dependent transmission line modeling with grounding representation." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/15494.
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Zahra, Fathima. "Artificial neural network approach to transmission line relaying." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ42465.pdf.
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Boston, Ian Edward. "Transient stress analysis by the transmission line method." Thesis, University of Hull, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259799.
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Ahmadian, Mansour. "Transmission Line Matrix (TLM) modelling of medical ultrasound." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/427.
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This thesis introduces TLM as a new method for modelling medical ultrasound wave propagation. Basic TLM theory is presented and how TLM is related to Huygens principle is discussed. Two dimensional TLM modelling is explained in detail and one dimensional and three dimensional TLM modelling are explained. Implementing TLM in single CPU computers and parallel computers is discussed and several algorithms are presented together with their advantages and disadvantages. Inverse TLM and modelling non linear wave propagation and different types of mesh are discussed. A new idea for modelling TLM as a digital filter is presented and removing the boundary effect based on digital filter modelling of TLM is discussed. Some modelling experiments such as : 1) Focusing mirror, 2) Circular mirror, 3) Array transducers, 4) Doppler effect, are presented and how to use TLM to model these experiments is explained. A new low sampling rate theory for TLM modelling is proposed and verified. This new theory makes the modelling of a much larger spaces practical on a given hardware platform.
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Scaramuzza, Richard Alan. "Simulation of conductive environments using transmission line modelling." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239486.
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Samad, Salina Abdul. "Link-transmission-line modelling of wave digital filters." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260520.
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Flockhart, Craig. "Simulation of microwave heating using transmission line modelling." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319922.
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Willison, Peter A. "Transmission line matrix modelling of underwater acoustic propagation." Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334426.
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Kim, Sangwoo. "Multiconductor transmission line analysis using surface ribbon method /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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O'Toole, Danielle. "Risk assessment of transmission line lattice tower foundations /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16339.pdf.
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VELOZO, LILIANE TOJEIRA. "METHODIZATION OF TRANSMISSION LINE FOUNDATION - STUDY AND DESIGN." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16178@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
As fundações dos elementos de apoio de uma linha aérea de transmissão de energia elétrica situam-se ao longo de extensos traçados, onde diferentes condições de apoio para as estruturas são encontradas em razão da variação natural dos horizontes. Tal configuração pode levar alternativamente a se programarem estudos e sondagens especiais em cada local de suporte, fazendo crescer os custos e prazos de projeto, ou ao contrário, reduzindo drasticamente a investigação, com prejuízos evidentes ao planejamento, execução e economia da obra de implantação da linha de transmissão. Dessa maneira, são organizados e propostos procedimentos para avaliação do terreno segundo as suas orografia, hidrografia, geologia e pedologia e do ambiente atmosférico local, cujas manifestações são capazes de impor severas solicitações às torres e, indiretamente, às fundações. É eleita a região da bacia do rio da Prata para constituir o grande cenário do estudo, quer pela abundância de dados e informações disponíveis sobre linhas de transmissão já em carga, ou ainda em construção, nessa região. Assim sendo, desenvolve-se uma metodização para orientar o estudo dessas fundações, considerando o conjunto torre x terreno x fundação e buscando soluções técnicas convenientes e economicamente aceitáveis, atendendo assim ao binário desempenho-custo. Para as torres são considerados os modelos auto-suportados e estaiados, o terreno é variado entre algumas categorias identificadas na região e as fundações são representadas pelas superficiais, em sapatas, e pelas profundas do tipo tubulão. Buscando, ainda, auxiliar no aprimoramento dos projetos de fundações para suportes de linhas de transmissão, é desenvolvido um estudo de confiabilidade estrutural tendo como modelo algumas das fundações pré-selecionadas para a metodização primariamente desenvolvida. São determinadas as probabilidades de falha dessas fundações através do programa FERUM e, a partir do levantamento dos prejuízos financeiros causados pela falha desses elementos, determina-se o risco de falha. Por último, é desenvolvido um estudo paramétrico para avaliar a influência do projeto de fundação, do tipo de solo e da velocidade de vento sobre a probabilidade de falha.
The transmission line tower foundations are executed following extensive paths, where different structural foundation conditions are found, in reason of natural horizontal ground layer variations. Then, one may alternatively to schedule and to execute special and specific studies or, conversely, to substantially reduce the geothecnical investigation, with sensible economical loses in the transmission line design and behavior. In such way, a methodology is proposed to evaluate conveniently the site according to its geology, orography , hydrography and pedology as well to related atmospheric local manifestations, able to submit severe mechanical solicitations to the towers and their foundations. In this way, one proposes a methodology to govern the study of these foundations, considering the tower x site x foundation relations and searching for convenient technical and acceptable economical solutions. Guyed and self-supported models are considered for towers, and the foundations are represented by footings, as the superficial type, and piers, as the deep type. The rio do Prata basin is chosen to constitute the large scenery of the study, because its abundant available data concerned to already operational transmission lines, or still under design and construction ones. Moreover, seeking the improvement of the tower foundation design a study based on structural reliability is developed considering some foundation models selected as mentioned above. Foundation failure probabilities are determined by the FERUM computational program and the risk of failure is obtained from economical damages caused by foundation failures. In the last, a parametric study is developed to evaluate how does the failure probability behave according to variations in the foundation soil, wind velocity and footing dimensions and depth.
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DUQUE, CARLOS AUGUSTO. "SIMULATION TECHNIQUE OF ELECTRICAL NETWORK AND TRANSMISSION LINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1997. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8212@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREste trabalho discute técnicas para simulação de redes elétricas com ênfase em operação em tempo real. As redes possuem linhas de transmissão como elementos a parâmetros distribuídos, enquanto redes RLC correspondem aos elementos concentrados, se bem que muitos dos resultados não se restringem só a estes tipos de elementos. A modelagem de linhas de transmissão é considerada primeiro, sob o ponto de vista da comparação entre dois modelos da literatura, caracterizando sua adequação para simulação em tempo real. Desta comparação resulta uma combinação de procedimentos como adequada à simulação. Na seqüência, é apresentado um novo algoritmo de integração numérica, baseado na descrição de estado de rede e em filtragem digital multitaxa. O novo algoritmo mostrou que pode reduzir o esforço computacional da simulação da rede, ao mesmo tempo que melhorou a qualidade das mesmas. O próximo objetivo relaciona-se com as oscilações numéricas, causadas pelo uso da Integração Trapezoidal em algumas configurações de rede. Um método de análise, baseado em teoria de rede e processamento digital de sinais é desenvolvido. A Partir dele são identificadas as configurações de redes, passíveis de gerações numéricas na sua contraparte digital. Métodos convencionais de eliminação das oscilações numéricas são analisados, incluindo no método o sistema multitaxa. Em todos os casos o sistema novo apresentou melhores resultados, sendo que seu uso apropriado, pode, por se, eliminar as oscilações numéricas. Alguns casos ilustrativos de redes de sistemas de potência estão incluídos, sendo desenvolvidos em linguagem MATLAB. Eles indicam que a combinação do modelo sugerido para linha de transmissão com o novo método de integração numérica multitaxa, permite a simulação da rede com reduzido esforço computacional e portanto aumentar a possibilidade de simulação de redes complexas em tempo real.
This work discusses techniques for electrical network digital simulation, emphasizing real time operation. The networks contain transmission lines as distributed elements and RLC elements as lumped parameters, although many of the results are not restricted to these elements. Transmission line modeling is considered first, comparing two of the methods found in literature from the real time simulation point of view. The convenience of their use is subject of analysis, leading, later on, to suggest a blend of approaches for real time simulation. In the sequence of the work, it is introduced a new numerical integration algorithm, based on network state space description and multirate digital filtering. The new integration method reduces the simulation computational complexity while simultaneously improving its accuracy. Next, the focus is on numerical oscillations caused by the Trapezoidal Integration approach in some network configurations. It is presented a method to identify electrical network configurations that might generate numerical oscillations in their digital counterparts. The method is a result of both, network and digital signal theory. Conventional and new techniques are applied in order to eliminate the numerical oscillations. The new multirate approach improves convetional techniques results, while properly used eliminates by itself the numerical oscillations. Some power systems network illustrative cases are included, using the new integration method and the proposed digital transmission line model. It is shown that this combination produces improved performance, final accuracy and reduced computational effort, resulting appropriate for real time simulations.
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Cavazos, Charles J. (Charles Jason). "Application of a resonant transmission line clock driver." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80051.
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Elkalsh, Ahmed. "Coupled electro-thermal transmission line modelling (TLM) method." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/40661/.
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The theme of this thesis is concerned with the modelling of the multi-physics interactions that occur in lightning and arc discharge. The main contributions of this research are presented as combining different physical studies namely, electromagnetic (EM) propagation, thermal diffusion and non-linear materials using a numerical algorithm. The algorithm was developed based on the two dimensional (2D) numerical transmission line method (TLM). The algorithm was applied to several practical examples namely, to model the electro-thermal analysis and the temperature development in a plasmonic nano-heat sources for terahertz applications; to predict the shape and the location of an arc discharge channel caused by a lightning strike using electro-thermal analysis, and to model diverter strips for lightning protection on aeroplanes. Different electro-thermal coupling approaches, such as fully and partially coupled methods were used to investigate the efficiency and accuracy of the model. In the fully coupled method the thermal model was allowed to change the electrical properties of materials in the electromagnetic model. On the other hand partial coupling did not consider the temperature dependency of the electrical properties in the electromagnetics model. Both of the models used the dissipated power from the electromagnetic model as a source signal to evaluate the temperature profile in the thermal model. Also different coupling interval timesteps were investigated to minimize the computational power needed without affecting the model accuracy.
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Liang, Yan. "Integrated Frequency-Selective Conduction Transmission-Line EMI Filter." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26360.
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The multi-conductor lossy transmission-line model and finite element simulation tool are used to analyze the high-frequency attenuator and the DM transmission-line EMI filter. The insertion gain, transfer gain, current distribution, and input impedance of the filter under a nominal design are discussed. In order to apply the transmission-line EMI filter to power electronics systems, the performance of the filter under different dimensions, material properties, and source and load impedances must be known. The influences of twelve parameters of the DM transmission-line EMI filter on the cut-off frequency, the roll-off slope, and other characteristics of the insertion gain and transfer gain curves are investigated. The most influential parameters are identified. The current sharing between the copper and nickel conductors under different parameters are investigated. The performance of the transmission-line EMI filter under different source and load impedances is also explored.
The measurement setups of the DM transmission-line EMI filter using a network analyzer have been discussed. The network analyzer has a common-ground problem that influences the measured results of the high-frequency attenuator. However, the common-ground problem has a negligible influence on the measured results of the DM transmission-line EMI filter. The connectors and copper strips between the connectors and the filter introduce parasitic inductance to the measurement setup. Both simulated and measured results show that transfer gain curve is very sensitive to the parasitic inductance. However, the insertion gain curve is not sensitive to the parasitic inductance. There are two major methods to reduce the parasitic inductance of the measurement setup: using small connectors and applying a four-terminal measurement setup. The transfer gain curves of three measurement setups are compared: the two-terminal measurement setup with BNC connectors, the two-terminal measurement setup with Sub Miniature version B (SMB) connectors, and the four-terminal measurement setup with SMB connectors. The four-terminal measurement setup with SMB connectors is the most accurate one and is applied for all the transfer gain measurements in this dissertation.
This dissertation also focuses on exploring ways to improve the performance of the DM transmission-line EMI filter. Several improved structures of the DM transmission-line EMI filter are investigated. The filter structure without insulation layer can greatly reduce the thickness of the filter without changing its performance. The meander structure can increase the total length of the filter without taking up too much space and results in the cut-off frequency being shifted lower and achieving more attenuation. A prototype of the two-dielectric-layer filter structure is built and measured. The measurement result confirms that a multi-dielectric-layer structure is an effective way to achieve a lower cut-off frequency and more attenuation.
This dissertation proposes a broadband DM EMI filter combining the advantages of the discrete reflective LC EMI filter and the transmission-line EMI filter. Two DM absorptive transmission-line EMI filters take the place of the two DM capacitors in the discrete reflective LC EMI filter. The measured insertion gain of the prototype has a large roll-off slope at low frequencies and large attenuation at high frequencies. The dependence of the broadband DM EMI filter on source and load impedances is also investigated. Larger load (source) impedance gives more attenuation no matter it is resistive, inductive or capacitive. The broadband DM EMI filter always has more high-frequency attenuation than the discrete reflective LC EMI filter under different load (source) impedances.Ph. D.
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Najafi, Syed Ahmed Ali. "Energy Harvesting From Overhead Transmission Line Magnetic Fields." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1548448189459464.
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Pink, Clive Desmond. "Liquid level measurement using a coplanar transmission line." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/8326.
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Bibliography: leaves 93-94.The coplanar line has been used very successfully as an element in microwave circuits. Small size, high Q-factor, and accurate reproduction, are some of its many advantages. The coplanar transmission lines discussed in this report, are targeted at liquid level measurement, and are typically 30 cm. long. Their operating frequencies are consequently much lower than those of microwave coplanar waveguides, but they have common advantages. The factor which separates the coplanar line from similar liquid level sensors, is that it makes use of the electrical component of the electromagnetic fringe field, setup between its inner conductor, and the surrounding ground plane. The line is effectively a sharply tuned resonator, incorporated as the frequency controlling element of an electronic oscillator. The output frequency falls as a dielectric material penetrates the fringe field. An impressive sensitivity is accomplished by using very thin conductors, thereby ensuring that the fringe field energy is maximised. The most important feature of this sensor is its ability to operate non-intrusively when used with non-conducting vessels, or if employed in a metal tank, the unit can be encased in a dielectric material where the line is non-contacting (the liquid does not penetrate the unit). This combined with its excellent mechanical and electrical stability, and an accuracy better than 1 percent, makes the coplanar line a strong competitor in the field of liquid level measurement. The research began with a theoretical approach, and used lines machined from an Aluminium plate for characteristic impedance measurement. An empirical relation between the gap width, the line thickness, and the characteristic impedance of the line is presented. To assist with the design of the sensor, a lumped capacitance model of the line was developed. Various geometries were tested, and modified until a near linear response to water level was achieved. An advanced engineering model of the level sensor has been developed, which incorporates a stable digital output display, user calibration from the line's end points, and temperature compensation. A T-shaped line, which concentrates the field around its open end, was used for other applications such as, evaporation monitoring, measurement of slurry settlement, and to observe the effect of acids, bases, and salts in water. Various applications of the different coplanar line designs are proposed.
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Melton, Mark David. "Precise surface placement in transmission line matrix modelling." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/14898.
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The Transmission Line Matrix modelling technique is a spatially discrete, time domain numerical modelling method. It has uses in many fields; however its main applications are for acoustic and electromagnetic modelling. This work focuses upon the study the positioning of surfaces which reflect and scatter waves within TLM models. In particular, the way in which the precise position of objects and surfaces are represented within the limitations of the model. Previously reported methods for improving surface positioning are investigated and evaluated. The previous methods are used as the basis for a new and improved method. The key features and performance of the method are appraised and areas for improvement defined. From this starting point, an enhanced method modifying the basic features and implementation is described. This enhanced method gives significantly improved results. Extensive testing of the original method and the enhanced method . are given in an unobstructed abstract case, clearly showing the performance differences of both methods and suitability for representing preCisely placed surfaces. Examples of the application of the method for both electromagnetic and acoustic modelling are given. Applications to ideal, abstract, and real world models are included. Results are compared with standard analytical benchmarks, results from other methods and measured data. The results show that there is a very clear and significant improvement in the performance of the TLM technique if the precise placement scheme given here is used.
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Keen, Alan G. "Planar transmission line analyses using the Method of Lines." Thesis, University of Kent, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293993.
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Taylor, Gareth Andrew. "A high voltage transmission line for space power systems." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315620.
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Perras, Stefan. "Electricity transmission line planning: Success factors for transmission system operators to reduce public opposition." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-161770.
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Europe requires significant transmission grid expansions to foster the integration of electricity markets, enhance security of supply and integrate renewable energies. However, next to lengthy authorization processes, transmission system operators (TSOs) in Europe are currently facing extreme public opposition in their transmission line projects leading to significant project delays. These delays imply significant additional costs for TSOs as well as society as a whole and put the transformation of the European energy system at risk. Existing scientific literature currently lacks comprehensive studies that have tried to identify generalizable success factors to overcome public opposition in transmission line projects. The goal of work at hand was to close this research gap. Potential success factors were collected through extensive literature review and interviews throughout Europe with respective stakeholders such as citizen action groups, NGOs or energy experts. Experiences from analogue large infrastructure projects like wind parks, carbon capture and storage facilities, hydro dams, nuclear waste repositories, etc. were also used to form hypotheses. The findings were transformed into a structural equation model and tested through a questionnaire answered by almost all European TSOs.
Results revealed that people’s trust in the TSO is of utmost importance for less public opposition. It can be regarded as the critical success factor per se. TSOs can create trust through stakeholder participation, sufficient communication, proper organizational readiness and liaison with stakeholders. Furthermore, appropriate technical planning can help to reduce public opposition in transmission line projects. In total 18 concrete and actionable success factors were identified for TSO management to facilitate the establishment of these aforementioned aspects. They will help European TSOs to reduce public opposition and thus accelerate the implementation of new transmission lines. Interestingly, economic benefits for people did not turn out to be a Significant success factor in reducing their opposition against new transmission lines.
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Lahmar, Mustafa. "ESTIMATION OF TRANSMISSION LINE PARAMETERS USING LINEAR METHOD WITH SYNCHRONIZED AND UNSYNCHRONIZED DATA." UKnowledge, 2019. https://uknowledge.uky.edu/ece_etds/135.
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Accurate value of transmission line parameters is important for power system protection applications, especially for distance relays whose zone settings are based on positive sequence line impedance. The research is devoted to estimating transmission line positive-sequence parameters from synchronized or unsynchronized measurements of voltage and current phasors that are obtained at both terminals of the line. The positive sequence parameters including series impedance and shunt admittance can be linearly estimated. The linear least square algorithm has been derived in this dissertation for different transmission line configurations. The algorithm is able to handle both synchronized and unsynchronized measurements and deal with potential synchronization errors by explicitly modeling the synchronization angle. Sample results are reported to demonstrate the effectiveness of the proposed method.
Three types of transmission line models depending on line length (long, medium and short) are studied in this dissertation. Chapter 3 uses unsynchronized data for the long transmission line. The derived method can detect the unsynchronized angle and estimate the positive sequence of long line parameters. The proposed method is examined with negative impacts such as errors on currents and voltages data. These errors are added randomly to one set each time to test the robustness of the developed algorithm.
The medium transmission line algorithm derivation is presented in chapter 4. This chapter uses a linear least square to estimate the lumped parameters of a medium transmission line. The two different transmission line circuits are used to model the medium line. The first circuit is a single transmission line with two nodes and is used to evaluate the developed algorithm. The second circuit is a double transmission line. These two lines can have the same or different line parameters or line length. The developed algorithm shows that the proposed method achieves highly accurate results for the estimation of positive sequence line parameters.
The short transmission line is studied in chapter 5. The short transmission line uses less data than the long or medium lines because in this model the shunt capacitance is omitted. Thus, the linear estimation yields highly accurate results. Case studies are considered to test the robustness of this developed method.
The line temperature mainly affects the series resistance, and the developed algorithms in previous three chapters can accurately estimate the transmission line parameters. To simplify the real-time estimation of line resistance and temperature, the series inductance, and shunt capacitance can be treated as constant and known values. Chapter 6 provides such studies of estimating resistance by treating inductance and capacitance as known values.
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Liu, Chuan-Pu. "Characterisation of ultrathin semiconductor layers using transmission electron microscopy." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624121.
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Shmeliov, Aleksey. "Transmission electron imaging and diffraction characterisation of 2D nanomaterials." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:4bc4d60f-4db0-43d2-9119-cb0a0366090e.
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Following the discovery of graphene, 2D nanostructures have been noted for their potential in a range of high-impact applications, such as sensing, catalysis, and composite reinforcement. Liquid-phase exfoliation and chemical vapour deposition have been demonstrated and indicate the feasibility of mass-scale production. With the advent of mass-produced 2D nanostructures a key focus of research is to characterise these materials. This thesis is concerned with imaging and structural properties of the 2D nanomaterials, hexagonal boron nitride (h-BN), molybdenum disulfide (MoS2), tungsten disulfide (WS2), titanium disulfide (TiS2) and hexabenzocoronene (HBC), produced via liquid phase exfoliation. HBC strictly speaking is not 2D nanomaterial, however, it can be viewed as transition molecule from benzene to graphene. The data used for characterisation is based primarily on electron diffraction and, in particular, aberration corrected annular dark field (ADF) scanning transmission electron microscopy (STEM). The incoherent nature of ADF STEM provides direct atomic imaging without the contrast reversals upon focus changes seen in conventional high-resolution transmission electron microscopy (HRTEM). The main structural feature investigated in this thesis was the stacking sequences in few-layers h-BN, MoS2, WS2 and TiS2. Simple stacking (AAA) can be distinguished from Bernal (ABA) and rhombohedral (ABC) on the basis of intensity ratio, I{10̅10}/I{11̅20} , in diffraction patterns and indirectly in HRTEM images. Nonetheless acquisition of the diffraction patterns suitable for analysis can be challenging due to the sample issues. Non-bulk stacking sequences were reliably confirmed for all above 2D nanomaterials on the basis of atomically resolved ADF STEM. 20 h-BN, 28 MoS2, 5 WS2 and 6 TiS2 nanoflakes were imaged and analysed. Amongst them 2 h-BN, 9 MoS2, 4 WS2 and 1 TiS2 nanoflakes displayed non-bulk stacking. Hence, it appears that 2D WS2 has the greatest affinity for non-bulk stacking. Finally, an interesting structural transformation was observed in HBC molecules. Under the influence of electron beam HBC agglomerates were transformed into crystalline phase with 90o symmetry.
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Mandviwala, Tasneem. "TRANSMISSION LINES FOR IR SIGNAL ROUTING." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3911.
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In this dissertation, the design, fabrication, and characterization of coplanar striplines, vias, and microstrip lines is investigated, from the point of view of developing interconnections for antenna-coupled infrared detectors operating in the 8- to 12-micron wavelength range. To our knowledge, no previous efforts have been made to study the performance of metallic-wire transmission lines at infrared frequencies. Both the design and fabrication of these structures present unique challenges. Because of attenuation and dispersion issues, the analytical formulas for transmission-line parameters that are valid below a few hundred GHz are not applicable in the infrared. Therefore, numerical modeling was performed to characterize the coplanar striplines and microstrip structures in terms of transmission-line parameters: characteristic impedance, attenuation constant and effective index of refraction. These parameters were extracted by fitting the computed impedance as a function of transmission-line length to the usual impedance transformation equation. The material properties used in the model are realistic, having been measured at the frequencies of interest by infrared ellipsometric techniques. The transmission-line parameters cannot be measured directly in the infrared, so experimental validation was carried out by measuring the response of a bolometer, which was connected to a dipole antenna by different lengths of both the coplanar and microstrip transmission lines. The modeled and measured responses for both types of transmission lines was in good agreement. A third type of signal-routing structure was also investigated, that of the vertical via, essentially a low-frequency connection that facilitates location of the bondpads away from the plane of the antenna. In the configuration studied, the vias pass vertically down through the SiO2 isolation layer and a groundplane, which provides electromagnetic isolation between the antenna and the structures that allow for signal-extraction from the bolometer. This type of interconnection will be useful for future detailed studies relating the angular antenna pattern to the spatial response of the antenna-coupled sensor.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Yogesh, S. "Power Line For Data Communication : Characterisation And Simulation." Thesis, 1995. http://etd.iisc.ernet.in/handle/2005/2188.
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