Thesis (Ph. D.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 102-110). Also available on the World Wide Web.

The inner continental shelf off the western half of the barrier island Fire Island, NY, is characterized by a series of obliquely oriented shoreface-connected ridges. The long-term historic shoreline record shows persistent undulations in shoreline shape at an alongshore scale similar to the alongshore scale of the ridges. This suggests that the ridges affect the wave transformation, alongshore sediment transport and corresponding shoreline change. These processes are investigated by utilizing the SWAN (Simulating WAves Nearshore) model, forced with realistic wave parameters, on a simplified, synthetic bathymetry replicating the scales of the shoreface-connected ridges. Results indicate that the relative magnitude of alongshore variations of modeled waves, alongshore transport, and the corresponding shoreline change are highly correlated with the relative orientation of the incoming waves to the ridges. Alongshore variations in both wave height and direction along the breaker line are much stronger when the predominant wave direction is along the main axis of the ridges rather than perpendicular to the ridge crests. This pattern of wave height variation is further explained by evaluating the directional energy spectrum and using a reverse ray-tracing technique. The gradients of the alongshore sediment transport, which lead to shoreline change, also appear to be stronger for waves with an angle of incidence similar to the ridge orientation. These results help explain the relationship between the oblique shoreface-connected ridges and the corresponding shoreline changes and shed light on the connection between the inner-shelf ridges and persistent shoreline undulations for the Western portion of Fire Island.

Utfört examensarbete undersöker vinkelfelet i mätkretsen för riktade jordfelsskydd och hur det påverkar dess felbortkoppling. Uppkomna vinkelfel i mätkretsen kan påverka det riktade jordfelsskyddet så att verklig felström och uppmätt felström inte stämmer överens, vilket kan leda till uteblivna eller obefogade felbortkopplingar. Vattenfall ställer krav på att vinkelfelet får uppgå till max ±2 grader för mätkretsen. Eftersom vinkelfelet i många fall har en hög påverkan på jordfelsskyddets noggrannhet undersöks vad Vattenfalls vinkelkrav egentligen innebär. Största orsaken till vinkelfelet uppstår oftast i strömtransformatorn och därför undersöks hur mycket två strömtransformatorer med olika klassificeringar som är vanliga i elnätet påverkar vinkelfelet i mätkretsen. Jordfel är det vanligast uppkomna felet i mellanspänningsnät och dess storlek beror till stor del på hur mycket kapacitivt bidrag som finns på linjerna samt värdet på nollpunktsresistorn. Det kapacitiva bidraget från linjen kompenseras centralt i fördelningsstationen och ibland lokalt ute på ledningen. Den högst tillåtna centralt kompenserade delen av en linje får vara 30 A, vid reservdrift av en linje kan denna del uppgå till 60 A. Vinkelfelet har en högre påverkan vid stora kapacitiva bidrag och vid låga värden på nollpunktsresistorn. I många fall sitter det flera riktade jordfelsskydd på samma linje där selektivitet alltid eftersträvas. Vinkelfelet kan ha en negativ påverkan på denna selektivitet. Genom beräkningar, simuleringar och provningar har ett antal slutsatser dragits. Vattenfalls vinkelkrav ger en otydlig bild angående tillåten påverkan på jordfelsskyddet. Med rätt val av strömtransformator påvisas att det troligtvis är möjligt att skärpa vinkelkravet. För att minska vinkelfelets påverkan kan den högst tillåtna centralt kompenserade delen minskas och/eller öka värdet på nollpunktsresistorn. En beloppsselektivitet på 1000 Ω kan inte alltid tillämpas då vissa fall kräver en beloppsselektivitet på 2000 Ω. Genom att sätta nollpunktsspänningen som utlösningsvillkor och nollpunktsströmmen som frigivningsvillkor kan enligt studien troligen ett noggrannare jordfelsskydd uppnås. / This bachelor's thesis examines the angular error in the measurement circuit for directional earth-fault protection and how this error affects the fault disconnection. Angular errors in the measurement circuit can affect the directional earth-fault protection in such a way that the real fault current and the measured fault current do not match. This can lead to missed or unwarranted fault disconnections. Vattenfall has a requirement which states that the angular error must not exceed ±2 degrees for the measurement circuit. Since the angular error in many cases has a high impact on the earth-fault accuracy, an investigation concerning what Vattenfalls angle requirement really means. The main cause of the angular error usually occurs in the current transformers and therefore two commonly used current transformers in the grid with different classifications and their impact on the angular error in the measurement circuit are examined. Ground fault is the most common fault which occurs in a distribution network, its size depends largely on the amount of capacitive current which the grid contributes with as well as the size of the neutral grounding resistor. The capacitive contribution of the grid compensates centrally in the distribution station and sometimes locally on the line. The maximum permitted centrally compensated part of a line is limited to 30 A, this central part can go up to 60 A in case the line needs to be fed from a second distribution station. The angular error has a higher impact if the capacitive contribution is high and for low values of the neutral grounding resistor. In many cases more than one earth-fault protection are found on the same line, in these cases selectivity is always pursued. The angular error may have a negative effect on the selectivity. By calculations, simulations and tests a number of conclusions can be drawn. Vattenfalls angle requirement gives an unclear picture concerning the permitted impact on the earthfault protection. Moreover selecting the correct current transformer demonstrates that the angular requirement can probably be sharpened. To reduce the influence of the angular error the maximum permitted centrally compensated part be reduced and/or the value of the neutral grounding resistor can be increased. A selectivity of 1000 Ω can not always be applied since certain cases require a selectivity of 2000 Ω. By setting the zero sequence voltage as the trigger condition and the zero sequence current as the realese condition, according to this study it may be possible to achieve a more accurate earth-fault protection.

Surface gravity waves exist in the oceans as multi-directional nonlinear phenomena. Understanding how these two properties interact is intrinsically important in itself. Furthermore, an understanding of this relationship may be used to gain insight into other oceanic phenomena. This thesis first describes an experimental investigation into the relationship between directionality and non-linearity (Part I). This relationship was then used as a tool to estimate the directional spreading of field data (Part II). Experiments have been conducted in which directionally spread focused wave groups were created in a wave tank. The relationship between the degree of directional spreading and the second-order bound harmonics of the wave groups was examined, in particular the formation of a `set-up'. These measurements were then compared to predictions from second-order theories, finding good agreement. The two-dimensional structure of the bound waves was explored giving new insight into the underlying physics. Experiments were then carried out for directionally spread crossing wave groups. It is believed that the crossing of two sufficiently separated wave groups may be the cause of an anomalous set-up in the second-order bound waves observed for some extreme and potentially freak waves. This set-up is reproduced experimentally. Again, the results of these test agreed very well when compared to second-order theory. The insight gained from the foregoing experiments was then utilised in the analysis of field data. A method, which requires only a single measurement to estimate the observed degree of directional spreading, was applied to a large dataset of field measurements from the North Alwyn platform in the North Sea. This method was then compared to conventional approaches, which require multiple concurrent measurements. The method that requires only a single measurement was shown to be effective, and presents a promising approach to gaining additional insight about the directional spreading of point observations.

abstract: As a developing nation, China is currently faced with the challenge of providing safe, reliable and adequate energy resources to the county's growing urban areas as well as to its expanding rural populations. To meet this demand, the country has initiated massive construction projects to expand its national energy infrastructure, particularly in the form of natural gas pipeline. The most notable of these projects is the ongoing West-East Gas Pipeline Project. This project is currently in its third phase, which will supply clean and efficient natural gas to nearly sixty million users located in the densely populated Yangtze River Delta. Trenchless Technologies, in particular the construction method of Horizontal Directional Drilling (HDD), have played a critical role in executing this project by providing economical, practical and environmentally responsible ways to install buried pipeline systems. HDD has proven to be the most popular method selected to overcome challenges along the path of the pipeline, which include mountainous terrain, extensive farmland and numerous bodies of water. The Yangtze River, among other large-scale water bodies, have proven to be the most difficult obstacle for the pipeline installation as it widens and changes course numerous times along its path to the East China Sea. The purpose of this study is to examine those practices being used in China in order to compare those to those long used practices in the North American in order to understand the advantages of Chinese advancements. Developing countries would benefit from the Chinese advancements for large-scale HDD installation. In developed areas, such as North America, studying Chinese execution may allow for new ideas to help to improve long established methods. These factors combined further solidify China's role as the global leader in trenchless technology methods and provide the opportunity for Chinese HDD contractors to contribute to the world's knowledge for best practices of the Horizontal Directional Drilling method. / Dissertation/Thesis / Doctoral Dissertation Civil Engineering 2014

Este trabalho envolve dois diferentes aspectos da estimação de espectros direcionais de onda a partir de movimentos de 1a ordem da embarcação. Sendo a estimação do espectro de ondas feita por meio de um método Bayesiano, existe a necessidade da calibração dos hiperparâmetros derivados da modelagem Bayesiana. O primeiro assunto abordado é a determinação de uma metodologia de calibração dos hiperparâmetros necessários à estimação do espectro direcional de ondas. Desenvolve-se ao longo deste uma primeira análise de um método aplicável a qualquer embarcação do tipo FPSO para a determinação a priori de valores de dois hiperparâmetros de controle da suavização da estimativa. Obtém-se resultados indicativos de que é possível definir valores destes hiperparâmetros dependentes de quantidades observáveis como calado da embarcação e período das ondas, de modo que os erros de estimação ainda se mantém muito próximos aos encontrados por valores ótimos dos hiperparâmetros. Isto leva à conclusão de que na abordagem atual, com valores fixos a cada calado, erros excessivos e desnecessários podem ocorrer no processo de estimação. O segundo tema trata da estimação paramétrica de espectros, utilizando modelos paramétricos de descrição de espectros como forma de obtenção de estatísticas de mar. Abordam-se também os assuntos de mares cruzados, donde se faz necessária a identificação da bimodalidade dos espectros para a estimação correta das estatísticas de mar. / In this work, two differents aspects of directional wave spectra estimation from 1st order ship motions are presented. As the estimation of wave spectrum is made by means of a Bayesian method, it is necessary to calibrate the hyperparameters derived from Bayesian modeling. The first addressed subject is the determination of a calibration methodology of the hyperparameters needed for the directional wave spectrum estimation. It is developed through this work a first analysis of an applicable method to any vessel of FPSO type for the prior determination of values for this two hyperparameters depending on observable quantities, such as draft of the vessel and wave period, in such a way that the estimation errors are still very close to those found by optimum values of the hyperparameters. This leads to the conclusion that in the current approach excessive and unnecessary errors can occur on the estimation process. The second subject addresses the parametric estimation of spectra, using parametric models of spectrum description to acquire the sea statistics. For this purpose, it became necessary the study of crossed-sea states, which was employed in the bimodal spectrum identification for the correct estimation of sea statistics.

Vários estudos sobre ontogenia e assimetria foram e vêm sendo realizados com cetáceos odontocetos através da utilização da morfometria convencional. Frequentemente compara-se o tamanho de estruturas do sistema respiratório de ambos os lados do crânio para avaliar a assimetria de tamanho e analisa-se o aumento de tamanho do corpo com a idade para avaliar ontogenia. Porém, através da morfometria convencional nem sempre é possível descrever ou representar a variabilidade de forma dos organismos, sendo que informações sobre a forma craniana dos odontocetos são bastante escassas. A morfometria geométrica é uma técnica que vem sendo amplamente utilizada em estudos de comparação da forma dos organismos, a qual leva em consideração o caráter geométrico das formas biológicas e analisa estatisticamente sua variação. Além disso, possibilita a realização de descrições independentes de forma e tamanho, o que permite que os mesmos sejam analisados separadamente. Sendo assim, este estudo se propôs a investigar as alterações ontogenéticas na forma e tamanho do crânio do boto-cinza, Sotalia guianensis, buscando alterações cranianas entre indivíduos de diferentes classes etárias, além de verificar a existência e analisar a assimetria direcional na forma e tamanho craniano para esta espécie. Para isso, os crânios foram digitalizados através de um braço digitalizador e depois de um tratamento geométrico as configurações geradas foram analisadas estatisticamente, a partir dos seus componentes de forma e tamanho. Foi observada assimetria de tamanho e forma para muitas das estruturas cranianas estudadas, notando-se diferenças com relação à assimetria entre as subunidades de desenvolvimento do crânio. Com relação à ontogenia, verificou-se um padrão semelhante para a alteração da forma e do tamanho com a idade, evidenciando que, tanto a forma como o tamanho craniano, se estabilizam por volta dos oito anos de idade. / Several studies exploring the ontogeny and asymmetry involving the skull and skeleton of the species of the Suborder Odontoceti have been performed using traditional morphometric techniques. Ontogenetic studies are usually based on the relationship between body size and age, while those focusing on the existence and degree of asymmetry compare the size of skull elements related to the respiratory tract. However, traditional morphometrics can not describe or represent adequately the variability of shape between organisms and therefore information about shape of dolphin skulls are very scarce. Geometric Morphometrics is a toolbox of techniques that is been widely applied in studies comparing the shape of organisms taking into consideration the biological shapes and analyzing their variation statistically. In addition, this technique allows to independently describe both shape and size separately, as well as exploring their relationship. The main objective of this study is to investigate the changes in skull shape and size during the ontogeny for the estuarine dolphin, Sotalia guianensis, characterizing the shape of the skull among different age groups. The second goal is to verify and analyze directional asymmetry in skull size and shape for this species. Dolphin skulls were scanned using a Microscribe-3D digitizer, statistically analyzing size and shape of the configurations created after translating, rotating and rescaling the original variables. Asymmetry in size and shape was detected for some cranial structures. There were also differences in asymmetry degree between the development subunits of the skull. For the ontogenetic trajectory it was detected a similar pattern of changes in shape and in size with age, in which both are stabilizing around eight years old for this species.

Orientador: Rubens Caram Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-22T02:53:41Z (GMT). No. of bitstreams: 1 Chaves_RicardoRisso_M.pdf: 6259336 bytes, checksum: 8f28236a72aaf02db8ce4c16083702ab (MD5) Previous issue date: 1997 / Resumo: O processo de fusão zonal consiste na passagem de uma ou mais zonas líquidas através de uma barra do material a ser purificado. Como variáveis do processo, tem-se: velocidade de solidificação, gradiente térmico junto à interface sólido-líquido, convecção imposta ao líquido e tamanho da zona líquida. O presente trabalho tem como objetivo apresentar uma solução à baixa produtividade dos métodos de purificação baseados na teoria de solidificação. Inicialmente, o método aqui proposto foi analisado através de sua simulação numérica e de experimentos utilizando ligas de SnPb. As amostras processadas foram caracterizadas pela técnica de espectrometria de absorção atômica. Finalmente, o método concebido foi aplicado à purificação de índio e por meio da técnica de espectrometria de emissão atômica, comprovou-se a viabilidade da técnica concebida. Os resultados obtidos indicam que o método aqui descrito tem maior produtividade que os métodos de fusão zonal tradicionais / Abstract: The zone refining process consists of the movement of one or more melted zones along the bar of the material which purification is desired. This purification process presents as variables: solidification rate, thermal gradient in front of the solid/liquid interface, convection imposed to the liquid and relative size of melted zone. The present work aims to introduce a solution to the problem of low production rate of the purification methods based on the solidification theory. Firstly, the proposed method was investigated by using numerical simulation. In addition, in order to evaluate the performance of this new version of the zone melt technique. an experimental apparatus was examined by the processing of a SnPb alloy. Atomic absorption spectroscopy was used to determine the chemical composition of the samples. Finally, this purification method was used to purify indium, which was characterized by using atomic emission spectrometry analysis. The results obtained show that the method described in this work has better performance than regular zone refining methods / Mestrado / Materiais / Mestre em Engenharia Mecânica

Novas rotas para obtenção de silício grau solar a partir de silício grau metalúrgico estão em desenvolvimento e a solidificação direcional é uma etapa presente em todos os processos propostos. O refino de silício por solidificação direcional baseia-se no fenômeno de macrossegregação das impurezas. Experimentos de solidificação direcional transiente foram realizados em condições estáticas utilizando um equipamento projetado no âmbito desse trabalho. A partir de um experimento de referência, foram avaliadas as influências da alteração do material da base do cadinho, altura do lingote e condição de resfriamento do forno. Para estudo das condições de solidificação e dos mecanismos envolvidos no fenômeno de macrossegregação de solutos foi proposto e implementado um modelo matemático. Esse modelo considera as equações gerais de transporte no caso unidirecional e o transporte de espécies químicas por difusão macroscópica e convecção. A convecção foi tratada a luz da teoria da camada estagnada a frente da interface sólido-líquido. Variáveis como velocidade da interface sólido-líquido, gradiente de temperatura, perfis de concentração de soluto e de fração de sólido foram obtidos com o modelo matemático utilizando as temperaturas medidas no silício durante os experimentos de solidificação como condições de contorno do modelo. Os resultados experimentais mostraram que sob algumas condições foram obtidos lingotes com macroestrutura típica de solidificação unidirecional e, além disso, as microestruturas mostraram evidências de macrossegregação de solutos. Os resultados do modelo matemático mostraram que a solidificação ocorreu em diferentes condições de velocidade da interface sólido-líquido e gradiente de temperatura nos experimentos. Os resultados obtidos com a utilização do modelo matemático mostraram que a convecção teve papel fundamental no fenômeno de macrossegregação de solutos. / New process routes are under development to obtain solar grade silicon from metallurgical grade one, and the directional solidification is an essential step in all proposed process routes. The silicon refining by directional solidification is based on the impurities macrosegregation phenomena. Transient solidification experiments were conducted under a static condition in a furnace projected for this work. From a reference experiment it was analyzed the effects of the changing the material of the crucible base, the ingot height and the cooling condition of the furnace. A mathematical model was proposed and implemented in order to study the solidification conditions and the main mechanisms regarding the macrosegregation phenomena. The mathematical model considers the conservation equations in one direction and the transport of chemical species occurs by diffusion and convection. The convection was treated using the diffusion layer theory. The velocity of solid-liquid interface, temperature gradient and profiles of solute concentration and solid fraction were obtained using the temperatures on silicon during the solidification experiments as boundaries conditions of the model. The experimental results showed that under some conditions it was obtained ingots with typical unidirectional macrostructure and, besides, showed in the microstructure evidences of macrosegregation. The mathematical model results showed that the solidification took place under different conditions of solid-liquid interface velocities and temperature gradient in the experiments. The results from the mathematical model showed that convection plays an essential role in the macrosegregation phenomena.

Dust particles in the atmosphere are a key cause of nuisance, health and other environmental problems. The mining sector is a major source of airborne particulate matter caused by operations like terrain clearing, drilling, blasting, tipping and loading and the passage of vehicles on unpaved roads. The nuisance effect of airborne dust can be measured by using dust buckets and/or directional dust deposition gauges. Dust buckets are used to determine vertical dust deposition rates and directional dust deposition gauges are used to determine the direction of the sources. Traditionally the measurement of the vertical flux of dust, or dust deposition has been used as to indicate the nuisance caused by coarse suspended particulate matter. Several countries have produced standards for permissible dust deposition rates. Although alternative deposition measurement methods have been proposed, ASTM D1739 has remained the method most often used in the South African mining and industrial sectors to measure dust deposition. In addition, a number of non-standard directional dust deposition gauges have been used. SANS 1929:2005 (South African National Standards, 2005) prescribes the use of ASTM D1739:98 for measuring dust deposition. However, for historical reasons the previous version, ASTM D1739:70 (re-approved as ASTM D1739:82) is still widely used and in the recently promulgated South African Dust Management regulations the use of this version is prescribed. In order to determine the difference in the results obtained by the two versions, ASTM D1739:82 and ASTM D1739:98 were used to measure dust deposition levels arising from a coal mining operation in the Mpumalanga Province and a gold mining operation in North-West Province. In order to determine whether a correlation exists between vertical dust flux (dust deposition) and horizontal dust flux, standard directional horizontal dust flux gauges according to BS 1747 part 5 were also set up at both sites. The measurement of dust deposition using three dust deposition gauges (i.e. ASTM D1739:82, ASTM D1739:98 and BS 1747 part 5, directional dust deposition gauges) was undertaken monthly over a period of fourteen (14) months at the two sites. The findings of the study indicate that the dust deposition rates for an opencast coal mine are generally higher than the dust deposition rates for an underground gold mine. ASTM D1739:98 was shown to be a more efficient dust deposition collection method than ASTM D1739:82, with the ratio between the mean values slightly more than 2. The addition of water to the dust bucket does not make a statistically significant difference to retention of dust in the bucket. There is a weak correlation between results for the vertical dust gauges and horizontal dust flux. It is recommended that the South African mining sector continue dust deposition monitoring and reporting using the more recent version of ASTM D1739, as high deposition levels may indicate a potential health impact from PM10 thoracic dust. / Dissertation (MEng)--University of Pretoria, 2014. / gm2014 / Chemical Engineering / unrestricted