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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Impact of tropical instability waves on nutrient and chlorophyll distributions in the equatorial Pacific /

Evans, William Wiley. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 88-93). Also available on the World Wide Web.
342

Bottom currents and abyssal sedimentation processes south of Iceland /

Shor, Alexander Noble. January 1979 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Supervised by Charles D. Hollister. Includes bibliographical references (leaves 206-211).
343

Remote measurements of waves and currents over complex bathymetry /

Chickadel, Carmine C. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.
344

Tidal influence on downstream fining in gravel-bed rivers /

Coles, Derron Rafiq. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 238-244). Also available on the World Wide Web.
345

Inner-shelf circulation off the central Oregon Coast /

Kirincich, Anthony R. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 169-179). Also available on the World Wide Web.
346

Impulse impedance of grounding systems and its effect on tower crossarm voltage : a dissertation presented to the faculty of the Graduate School, Tennessee Technological University /

Manna, Tapan K., January 2006 (has links)
Thesis (Ph.D.)--Tennessee Technological University, 2006. / Bibliography: leaves 164-169.
347

Benthic habitats in a tide-swept channel of the Pentland Firth and their potential responses to a tidal energy development

Harendza, Astrid January 2014 (has links)
This thesis investigates sublittoral epibenthic assemblages, the ecological processes associated with distributions of benthic assemblages and potential ecological impacts arising from the de-ployment of tidal energy devices (TEDs) at a key tidal energy development site. An extensive field campaign was undertaken to collect fine-scale, in-situ data for local hydrodynamics, seabed structure and epibenthic assemblages. Data from a two-dimensional hydrodynamic model com- plemented in-situ flow data and provided an insight into possible changes to local tidal patterns after the deployment of a tidal array. The study revealed a highly complex tidal stream structure with maximal velocities reaching 4.2 ms1 during spring tide. The seabed was predominantly formed by scoured bedrock. Deployment of a tidal array was predicted to decrease tidal flow within and downstream of the array by up to 24 % for peak flows, whereas effects on the seabed were thought to be minor. Epibenthic assemblages were typical for tide-swept channels with a fringe of dense kelp forest along the shallow, sheltered waters of the channel, followed by a 'tran- sition zone' dominated by foliose red algae in the mid-depth ranges and animal turf assemblages in the deeper, very tide-swept waters. Multivariate analyses identified depth and bed-shear stress as being strongly associated with the distribution and composition of assemblages. In conjunction with presence-only data for epibenthic species, depth and bed-shear stress were used as predic- tor variables to develop site-specific habitat suitability models (HSMs) for a baseline and TED deployment case. Comparison of probability of occurrence values between the respective HSMs indicated a potential increase of suitable habitat for species inhabiting the deep, very tide-swept circalittoral following the deployment of TEDs, whilst assemblages along the fringes of the channel were mostly unaffected. This is the first attempt of using HSM as a tool for identification of potential changes in distributions of benthic species arising from the deployment of TEDs. The good overall performance of the models shows this tool may be valuable for for impact analysis of tidal energy development projects.
348

Estudo de caso: diagnóstico do consumo e da qualidade de energia numa indústria metalúrgica

Carvalho, Antonio Carlos de [UNESP] 27 August 2004 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-08-27Bitstream added on 2014-06-13T20:27:08Z : No. of bitstreams: 1 carvalho_ac_me_ilha.pdf: 884948 bytes, checksum: 678386f50d74fa0271afe8eabfc08a7f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho tem por objetivo a proposição de um estudo de caso realizado em uma planta industrial, cuja linha de produção se concentra na área da metalurgia. O principal enfoque foi direcionado na avaliação e nos efeitos causados pelas correntes distorcidas, geradas por cargas não lineares, nos barramentos e alimentadores da industria. Com o objetivo de avaliar o impacto das cargas elétricas, com características não lineares, as instalada e a serem instaladas no sistema elétrico da industria. Foi realizada também uma avaliação geral da planta da indústria através da análise das faturas de energia elétrica buscando identificar nos principais indicadores, os desvios no sistema elétrico da planta. Entre estes, podemos destacar a demanda, o consumo, os reativos excedentes e outros. Todos os procedimentos desenvolvidos neste trabalho foram direcionados no sentido de se usar racionalmente a energia elétrica e controlar o seu desperdício. / This work aims to study a case carried out in an industrial plant, whose production line is concentrated on the metallurgy field. The main objective was addressed in the evaluation and in the effects caused by the distortion of the currents, due to nonlinear loads connected at the industry busbar and feeders. With the objective of evaluating the impact of the electric loads, with non- linear characteristics, or installed in the industry electric system. It was also accomplished a general evaluation of the industry plant by analyzing the electric power invoices looking for identifying, in the main quality power indicators, the deviations in the electric plant system. Among these, we can mention the demand, the consumption, the exceeding reactives and others. All the procedures developed in this work were addressed aiming to use the electric power rationally and to control its waste.
349

Correntes subinerciais na Plataforma Continental interna entre Peruíbe e São Sebastião: observações / Subdital Inner-Shelf currents between Peruíbe and São Sebastião: Observations

Piero Luigi Fernandes Mazzini 06 August 2009 (has links)
A região costeira do Estado de São Paulo, entre Peruíbe (24o24\'30\'\'S, 46o54\'00\'\'W) e São Sebastião (23o50\'30\'\'S, 45o40\'00\'\'W) faz parte da Plataforma Continental Sudeste do Brasil (PCSE). A região possui grande importância econômica e social devido ao turismo, indústria de óleo e gás, e ao porto de Santos, o maior do país. Correntes sobre a plataforma continental interna (PCI) dessa região foram pouco estudadas antes do projeto ECOSAN. Durante o ECOSAN, dados de correntes foram obtidos por aproximadamente 10 meses (2005-2006), através de 4 fundeios: 3 localizados na PCI, próximo à isóbata de 20 m: em frente à Peruíbe (P20) (24o24\'30\'\'S, 46o54\'00\'\'W), em frente à Santos (S20) (24o03\'30\'\'S, 46o17\'30\'\'W), e próximo à ilha Montão de Trigo (M20) (23o50\'\'30\'S, 45o40\'\'00\'W); e 1 localizado na plataforma continental média (PCM), próximo à isóbata de 100 m, em frente à Santos (S100) (25o05\'00\'\'S, 45o42\'00\'\'W). Medições de ventos foram feitas durante o mesmo período através de 2 bóias meteorológicas, localizadas junto à P20 e M20, e na Lage de Santos (L30) (24o19\'48\'\'S, 46o11\'20,4\'\'W). Os dados foram analisados no domínio do tempo e da freqüência para estudar as características das correntes bem como a importância relativa das forçantes da circulação, principalmente: tensão de cisalhamento do vento, gradientes de pressão baroclínicos e troca de momentum entre a Corrente do Brasil (CB) e as águas mais internas da plataforma continental. Resultados mostraram que as componentes de corrente paralelas à topografia foram as mais energéticas, sendo aparentemente geostróficas. Correntes forçadas pelo vento na PCI foram observadas em P20 durante o verão e em M20. Já em S20, o vento não foi capaz de suplantar os efeitos baroclínicos causados pela descarga fluvial do sistema estuarino de Santos. Em períodos de ventos fracos M20 é forçada por efeitos baroclínicos, aparentemente sofrendo também influência do sistema estuarino de Santos. Em P20 durante o inverno foi constatada a presença de forçantes baroclínicas, sendo estas atribuídas às águas provenientes do sul, com influência do Rio da Prata, as quais possivelmente influenciam também a dinâmica da PCM. Durante o período amostrado não foi verificado nenhuma inuência direta da Corrente do Brasil sobre a PCM, e tampouco sobre a PCI, demonstrando que essas regiões possuem dinâmica distinta da plataforma continental externa. A circulação na plataforma continental estudada não é homogênea, apresentando um sistema complexo de uxos e contra-uxos, havendo uma tendência das correntes sobre a PCM e a PCI apresentarem sentidos opostos. Há também tendência das correntes na PCI apresentarem sentido predominante para NE sobretudo entre Santos e São Sebastião, enquanto que na PCM a direção predominante é para SW. / The São Paulo State coastal region located between the cities of Peruíbe (242430S, 465400W) and São Sebastião (235030S, 454000W) is part of the SouthBrazil Bight. This region has great economic and social importance due to the tourism, oil and gas industries and the presence of the largest Brazilian port (Santos). Currents at the regions inner-shelf were poorly sampled before the eld work of the ECOSAN project. During ECOSAN, current meter data was obtained for nearly 10 months (2005-2006), from 4 moorings: 3 deployed in the inner-shelf, near the 20 m isobath: in front of Peruíbe (P20) (242430S, 465400W), in front of Santos (S20) (240330S, 461730W) and near Montão de Trigo Island (M20) (235030S, 454000W); and 1 deployed at the mid-shelf, near the 100 m isobath, in front of Santos (S100) (25 0500S, 45 4200W). Wind time series were measured at the same period, at the two inner shelf moorings, P20 and M20, by a surface met-buoy, and at the Lage de Santos (L30) (241948S, 46 1120,4W). Current and wind data were analyzed in time and frequency domains for describing currents characteristics and comparing the relative importance of the forcing mechanisms for the inner-shelf circulation, mainly: wind-stress, baroclinic pressure gradients and Brazil Current momentum exchanges. Results showed that alongshelf current components were the most energetic and nearly geostrophic. Wind driven currents on the inner-shelf were observed on P20 during summer time and on M20, however on S20 the wind wasnt capable of overcoming baroclinic eects caused by river discharge from the Santos estuarine system. Over weak wind periods M20 was forced by baroclinic eects, apparently also inuenced by Santos estuarine system. Baroclinic forcing was observed on P20 during winter time, being atributed to waters from the south, under the inuence of the Plata River, possibly inuencing the mid-shelf as well. During the whole period there was no presence of Brazil Current eddies or meanders, showing that neither inner-shelf nor mid-shelf are inuenced by the outer-shelf dynamics. The continental shelf circulation is not homogeneous, with a complex pattern of uxes and counter-uxes, where currents have tendency to ow on opposite directions between mid and inner-shelf. There is also a tendency for currents on the inner-shelf to ow towards NE, speccialy between Santos and São Sebastião, and towards SW on the mid-shelf.
350

Combined numeric and analytic methods for foil winding design

Odendaal, Willem Gerhardus 13 March 2014 (has links)
M.Ing (Electrical and Electronic Science) / High frequency magnetic components have significant advantages related to cost and physical size compared to their low frequency counterparts. The advent of high frequency power switch technology made the transformer frequency a variable and recent advances in this field have been ever pushing the switching frequency of higher power converters. Although high frequency inductors and transformers have been used and applied extensively to an increasingly broad range of applications over recent decades, analysis and design of these devices involves certain difficulties, related to extra losses due to eddy currents as well as smaller cooling surfaces, to the developer and designer. Numerical simulations of eddy currents in windings are slow, if not impossible in many cases, due to the large mesh impositions required in order to converge. Eddy currents and thermal constraints impose limitations on flux- and current densities, complicating the design. As yet, a convenient means of design, analysis and optimization of the physical magnetic topology does not exist. In this study, a method for analysing eddy currents in windings, usmg a combined analytical and numerical approach, is presented and implemented in a CAD tool. The one dimensional solutions for eddy currents in strip conductors are written in a more flexible form. A new approach to magnetic component design, called scant modelling, is presented and applied to two practical examples. The scant model comprises a minimum number of functional and form parameters in analysing and optimizing a design, but considers eddy current effects, thermal constraints and the effects of physical size and shape of core and windings at high frequencies.

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