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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.
331

Despacho de um arranjo hidro-eólico incluso em um sistema coordenado centralmente : modelo híbrido de otimização com meta-heurísticas / Dispatch of a hydro-wind arrangement included in a centrally coordinated system : hybrid optimization model with metaheuristics

Barros, Regiane Silva de, 1986- 28 August 2018 (has links)
Orientadores: Paulo de Barros Correia, Ieda Geriberto Hidalgo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-28T12:05:23Z (GMT). No. of bitstreams: 1 Barros_RegianeSilvade_D.pdf: 4190585 bytes, checksum: c320645bbd13fd28d572f5b9751d4ff7 (MD5) Previous issue date: 2015 / Resumo: Este trabalho propõe um modelo de despacho ótimo no horizonte diário de operação, que permite coordenar a operação entre uma usina eólica e uma usina hidrelétrica. Nessa abordagem, a usina eólica é despachada em primeira instância. Para suprir eventuais saídas forçadas que possam ocorrer na geração eólica, aloca-se um valor de reserva girante incremental na usina hidrelétrica usando o conceito de Value at Risk como métrica de risco da geração eólica. O modelo é formulado como um problema multiobjetivo que busca maximizar a geração de energia e minimizar o número de partidas e paradas da usina hidrelétrica. O acoplamento hidráulico é considerado através da meta diária de defluência da usina. O problema é solucionado em duas etapas. A primeira resolve 24 problemas estáticos, que representam o despacho horário da usina hidrelétrica, separadamente. Essa etapa emprega o Algoritmo Genético para otimizar a operação da usina em termos da geração de energia elétrica. A segunda etapa soluciona o problema dinâmico, ou seja, o despacho diário da usina. A natureza do problema dinâmico, correspondendo à obtenção de caminhos mínimos eficientes em termos de partidas e paradas, sugeriu o uso da técnica de Otimização por Colônia de Formigas. As restrições de reserva girante, meta de defluência, atendimento do contrato de demanda e limites operacionais das usinas são plenamente satisfeitas. A diferença entre os montantes de energia produzidos e contratados é liquidada no mercado de curto prazo e valorada ao preço de liquidação das diferenças. O modelo se mostrou adequado em termos de tempo computacional e em relação à qualidade das soluções obtidas / Abstract: This work proposes an optimal dispatch model in the daily horizon, which coordinates the operation of a wind farm and a hydroelectric plant. In this approach the wind farm is dispatched first. In order to provide eventual faults that may occur in the wind farm generation, an incremental spinning reserve is allocated in the hydroelectric plant using the concept of Value at Risk. The model is formulated as a multiobjective problem which seeks to maximize the energy generation and to minimize the number of start-ups and shut-downs of the hydroelectric plant. The plant¿s hydraulic coupling is considered through the daily released flow goal. The model is solved in two stages, the first one solves, separately, 24 static problems that represents the hourly dispatch of the hydroelectric plant. This stage employs Genetic Algorithm to optimize the operation of the hydroelectric plant in terms of electric energy generation. The second stage considers the dynamic problem, which is the plant¿s daily dispatch. The nature of the dynamic problem, which implies in obtaining efficient shortest paths in terms of start-ups and shut-downs, suggests the use of the Ant Colony Optimization. The spinning reserve, the released flow goal, the demand contract and the generating unit¿s operational limits are fully satisfied. The difference between the energy amounts produced and contracted are liquidated in the spot market and it is valuated with the settlement differences price. Regarding computational costs and solutions quality, the model suitability is shown / Doutorado / Planejamento de Sistemas Energeticos / Doutora em Planejamento de Sistemas Energéticos
332

Cycles du carbone et de l’azote et émissions de gaz à effet de serre (CH4, CO2 et N2O) du lac de barrage de Petit Saut et du fleuve Sinnamary en aval du barrage (Guyane Française) / Carbon and nitrogen cycles and greenhouse gases emissions (CH4, CO2, N2O) of the Petit Saut reservoir and the Sinnary river downstream of the dam (French Guiana)

Cailleaud, Emilie 01 December 2015 (has links)
Les eaux continentales sont des sources de méthane (CH4), de dioxyde de carbone (CO2)et de protoxyde d’azote (N2O). Dans le but de préciser leur importance dans le bilan global des émissions de gaz à effet de serre (GES), de nombreuses études ont été réalisées afin de quantifier les différents flux de carbone et d’azote les parcourant. Ces flux sont perturbés par la mise en place de barrages sur le lit des fleuves. Peu d’études présentent des bilans de carbone et d’azote complets (apports, exports, flux vers l’atmosphère et enfouissement) pour les lacs de barrages, et elles concernent uniquement des écosystèmes boréaux et tempérés. Suite à la création d’un barrage, de la matière organique (MO) est mise en eau (sols et forêts), elle se dégrade rapidement les premières années suivant la mise en eau puis plus lentement par la suite. L’état de dégradation de la MO et la principale source de GES dans un lac de barrage près de 20 ans après la mise en eau sont souvent méconnus. L’étude réalisée 18 ans après la mise en eau du lac de Petit Saut (Guyane Française) est la première étude où les principaux éléments des cycles du carbone et de l’azote d’un lac de barrage hydroélectrique, et de son fleuve en aval, situé en climat équatorial et dont la création a entraîné la mise en eau de forêt primaire, sont étudiés près de 20 ans après la mise en eau. Cette étude se base sur (i) la mesure mensuelle de la qualité des eaux et des concentrations en carbone et azote en amont, dans, et en aval du lac de barrage, (ii) la mesure et/ou le calcul des différents flux de GES vers l’atmosphère, (iii) des données de la signature isotopique et de l’état de dégradation de la MO en amont, dans, et en aval du lac, (iv) des prélèvements de sédiments et de troncs d’arbres ennoyés en 1994 et (v) des incubations d’eau du fleuve, de sédiments et de troncs d’arbres du lac. L’ensemble des données collectées au cours des 12 mois de campagnes réalisées en 2012 - 2013 nous a permis de déterminer que (i) les sols inondés sont toujours des sources significatives de GES contrairement aux troncs d’arbres ennoyés, (ii) dans le lac 84 % des émissions de CH4 et 51 % des émissions de CO2 ont lieu dans la zone littorale (< 10 m de profondeur), (iii) 54 % du CO2 produit dans le fleuve en aval provient de la dégradation de la MO apportée par le lac. Cette étude nous a aussi permis de réaliser des bilans de carbone et d’azote à Petit Saut et un bilan des émissions de chacun des GES émis (CH4, CO2, N2O) près de 20 ans après la mise en eau. / Inland waters are sources of methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). In order to define their importance in the global balance of greenhouse gases (GHG) emissions, numerous studies have been conducted to quantify the different fluxes of the carbon and nitrogen browsing them. These fluxes are modified by the creation of dams on river beds. Few studies present full carbon and nitrogen balances (inputs, outputs, fluxes to the atmosphere and sequestration) for reservoirs, and they concern only boreal and temperate ecosystems. The creation of a dam floods organic matter (OM) (soils and forests), which is rapidly degraded the first years following the impoundment and thereafter more slowly. The state of degradation of the OM and the main source of GHG in a reservoir nearly 20 years after impoundment are often unknown. The study conducted 18 years after the impoundment of the Petit Saut Reservoir (French Guiana) is the first study where the main elements of carbon and nitrogen cycles of an hydroelectric reservoir, and its river downstream, located in equatorial climate and which creation resulted in the flooding of primary forest, are studied nearly 20 years after impoundment. This study is based on (i) a monthly measurement of water quality and carbon and nitrogen concentrations upstream, in, and downstream of the reservoir, (ii) measurements and/or calculations of the different fluxes of GHG through the atmosphere, (iii) data of the isotopic signature and of the state of degradation of OM upstream, in, and downstream of the reservoir, (iv) sediments and 1994’s flooded tree trunks sampling and (v) incubations of downstream river water, sediments and tree trunks from the reservoir. All the data collected during the 12 months of campaigns carried out in 2012 - 2013 allowed us to determine that (i) flooded soils are still significant sources of GHG unlike flooded tree trunks, (ii) in the reservoir 84 % of CH4 emissions and 51 % of CO2 emissions occur in the littoral zone (< 10 m depth), (iii) 54 % of the CO2 produced in the river downstream of the dam come from the degradation of the OM provided by the reservoir. This study also allowed us to achieve carbon and nitrogen balances in Petit Saut and emission balance of each GHG emitted (CH4, CO2, N2O) nearly 20 years after impoundment.
333

Biodiversité anguillicole en milieu tropical insulaire (Tahiti) face aux aménagements hydroélectriques / Anguillicol biodiversity in island tropical environment (Tahiti) in front of hydroelectric developments

Helme, Herehia 08 December 2017 (has links)
Cette thèse en recherches fondamentale et appliquée a pour modèle biologique l’anguille d’eau douce qui a toujours fasciné le monde de la recherche par son cycle de vie unique et tous ses mystères non encore résolus pour certains. Dans le monde, 19 espèces d’anguilles existent dont certaines en déclins dans les zones tempérées ce qui peut justifier l’amplification des recherches sous les tropiques. En Polynésie française, cet animal mystérieux est sacré ; les légendes polynésiennes associent les anguilles à la création de la vie. Trois espèces y sont présentes : l’anguille marbrée « Anguilla marmorata », l’anguille de montagne « Anguilla megastoma » et l’anguille de vase « Anguilla obscura ». Elles n’ont pas la même distribution spatiale où la première s’adapte à n’importe quel milieu, la deuxième remonte les rivières jusqu’en haute vallée à plusieurs centaines de mètres d’altitude, tandis que la dernière reste en basse vallée préférant les eaux stagnantes. Grâce aux nombreuses rivières présentes sur Tahiti, cette île principale de Polynésie est en pleine transition énergétique et privilégie maintenant les énergies renouvelables ; particulièrement l’hydroélectricité. Cependant, les aménagements hydroélectriques connus pour provoquer des problèmes de continuité écologique de la biodiversité dulçaquicole, notamment pour les anguilles, vont nous intéresser dans ce travail de thèse en bourse Cifre. C’est dans ce contexte que s’inscrit cette thèse, dans la plus grande vallée de Tahiti, la Papenoo. Deux problématiques y sont étudiées : le recrutement des civelles et l’étude de la population adulte. Nos résultats sur les trois années de suivi de l’arrivée des juvéniles d’anguilles dans l’embouchure de la Papenoo révèlent un recrutement saisonnier des civelles de Novembre à Mars avec deux pics en Décembre et Janvier. Plus de 80% des civelles sont des Anguilla marmorata. Concernant les populations adultes, nous observons : 1/ plus de 90% de la population sont également de l’espèce Anguilla marmorata, 2/ les anguilles adultes présentent un gradient de densité de l’aval vers l’amont et 3/ le problème de continuité biologique ne vient pas des barrages ou captages en eux-mêmes, mais proviendrait des canaux de fuite en sortie de centrale où nous observons une sur-attractivité pour les anguiles. Cette étude s’est révélée très importante dans l’avancement théorique de nos connaissances biologiques et écologique sur l’anguille, dans l’appropriation par l’industriel de bonnes pratiques et par une solide communication sur la coexistence possible entre gestion et développement. / This thesis in fundamental and applied research has for biological model the freshwater eel which has always fascinated the world of the research by its unique cycle of life and all its mysteries not solved for some. Worldwide, 19 species of eels exist, some of which are declining in temperate zones, which may justify the increase in research in the tropics. In French Polynesia, this mysterious animal is sacred; the Polynesian legends associate the eels with the creation of life. Three species are present: the marbled eel "Anguilla marmorata", the mountain eel "Anguilla megastoma" and the eel "Anguilla obscura". They do not have the same spatial distribution where the former adapts to any medium, the second goes up the rivers to the upper valley at several hundred meters of altitude, while the latter remains in the lower valley preferring the stagnant waters. Thanks to the numerous rivers on Tahiti, this main island of Polynesia is in the midst of an energy transition and now favors renewable energies; particularly hydroelectricity. However, hydroelectric developments known to cause problems of ecological continuity of freshwater biodiversity, especially for eels, will interest us in this thesis work on the Cifre grant. It is in this context that this thesis, in the largest valley of Tahiti, is the Papenoo. Two problems are studied: the recruitment of glass eel and the study of the adult population. Our results over the three years following the arrival of juvenile eels in the mouth of the Papenoo reveal a seasonal recruitment of elvers from November to March with two peaks in December and January. More than 80% of elvers are Anguilla marmorata. For adult populations, we observe: 1/ more than 90% of the population is also Anguilla marmorata, 2/ adult eels have a density gradient from downstream to upstream, and 3/ biological continuity does not come from dams or water removal in themselves, but comes from the tailrace leaving the hydropower plant where we observe an over-attractiveness for the eels. This study proved to be very important in the theoretical advancement of our biological and ecological knowledge about the eel, in the appropriation by industry of good practices and in a solid communication on the possible coexistence between management and development.
334

Zvýšení úrovně spolehlivosti dodávky elektrické energie z hydrocentrály Jasenie do Železiarní Podbrezová / Increasing of reliability of power supply from the Jasenie hydropower plant to Železiarně Podbrezová

Budovec, Michal January 2019 (has links)
This thesis deals with operation of the Jasenie hydroelectric power plant, which supplies electricity to Železiarne Podbrezová Inc. This thesis describes actual operation, devices and equipment in all substations. The second chapter briefly describes company’s history and activities of the company. The next chapter mentions an overview of the sources of own electricity production. The fourth chapter in detail deals with actual situation of the hydroelectric power plant operation, describes devices and equipment in all substations. It also outlines what measures should be taken to increase the reliability of electricity supply. Next part deals with replacing insulators on the 22 kV line. Sixth chapter is focused on protection this line by multifunctional protection relay and data transfer from HC Jasenie to the building of power engineering. In the next step is designed a backup transformer with bus control for thermal and dynamic effects of the short-circuit current. The last chapter is focused on surge protection in HC Jasenie as well as in the area of Stary závod substation. The results and benefits of this work are summarized in the conclusion. The attachment contains schemes of substations and overall overview scheme, which are used for better understanding of this problem.
335

Návrh postupu při obnově napájení vlastní spotřeby zdrojů Tepláren Brno po rozsáhlé systémové poruše v ES / Proposal for the Procedure of Supply Restoring for Power Plant Teplárny Brno Auxiliary System after Extensive System Fault in PS

Jára, Jaroslav January 2015 (has links)
This work deals with the issue of supply restoring for heating plant Teplárny Brno, a. s. Špitálka division, after a system-wide failure of the “blackout”. The thesis solves the “black start” of the Špitálka Teplárny Brno operation by delivering a voltage from the hydroelectric power Vír I, proposes a methodology for commissioning of individual devices, up to phasing the generators with subsequent possibility of creating an “island mode” in the area of Brno city, which the work already does not deal with. The work also deals with the preparation of the operational test, while starts of the selected devices are tested. The schedule of commissioning of each device is supported by calculations of the parameters for the entire system with regard to voltage drops while connecting the high load. The result of this work is the proposal of methodological process of supply restoring for power plant Teplárny Brno – Špitálka division, by submission a voltage from the hydroelectric power Vír I, which can be used both in any system-wide failure of the “blackout”, or during the operational test.
336

Projekt modelu malé vodní elektrárny / The project of model hydroelectric power plant

Urbánek, Jaroslav January 2015 (has links)
Master thesis consists of the construction of a small hydroelectric power play model for laboratory use. The first step is to calculate parameters required for the creation of the 2D model Banki turbine. Next part is a proposal and selection of individual components of the model, such as generator, turbine housing, water circuit, pump and alternator mounting. The last step is to launch the model and verify, if the model of a small hydroelectric power plant achieves the required parameters.
337

Identifying Synergies and Trade-offs between the Grand Ethiopian Renaissance Dam and the Sustainable Development Goals / Identifiering av Synergier och Målkonflikter mellan Grand Ethiopian Renaissance Dam och de Globala Målen

Thengius, Sandra, Preston, Olivia January 2018 (has links)
The Grand Ethiopian Renaissance Dam (GERD) is a large hydropower project currently under construction in Ethiopia. Supposedly it will benefit the people of Ethiopia through an increased access to electricity, but it is also associated with complex political relations between Ethiopia and the neighbouring countries Egypt and Sudan. The aim of this thesis is to analyse the GERD project with regard to the United Nations’ 17 Sustainable Development Goals and their 169 related targets, and to show what actions should be taken to improve the contribution of the GERD to sustainable development. A method developed for mapping synergies and trade-offs between targets in the SDGs was used. To identify how the GERD contributes to and/or hinders the fulfillment of the goals, published evidence was systematically searched. 83 synergies, 45 trade-offs and 16 instances when cooperation in the Nile River basin is needed were identified. By radically increasing the electricity access in Ethiopia and because of the dam itself, the GERD both potentially contributes to and hinders sustainable development in relation to environment, society and economy. Identified key actions to reinforce the synergies and minimise the trade-offs are to establish a secure and including cooperation between Ethiopia, Egypt and Sudan; to ensure increased transparency, public access to information and participatory processes; to investigate and carry out measures that benefit the ecology in the area; and to strengthen the positive outcomes of electrification through supplementary measures. / Grand Ethiopian Renaissance Dam (GERD) är ett stort vattenkraftprojekt som är under uppbyggnad i Etiopien. Genom att radikalt öka tillgången till elektricitet förväntas GERD bidra positivt till det etiopiska samhället, men dammen är också associerad med komplicerade politiska relationer mellan Etiopien och grannländerna Egypten och Sudan. Målet med rapporten är att analysera GERD-projektet i förhållande till FN:s 17 Globala mål och dess 169 tillhörande delmål, samt att visa vilka åtgärder som bör vidtas för att GERD i större utsträckning ska bidra till en hållbar utveckling. En metod som utvecklats för att kartlägga synergier och målkonflikter mellan olika delmål av de Globala målen användes. För att undersöka hur GERD bidrar till och/eller förhindrar uppfyllandet av delmålen gjordes en systematisk sökning av publicerad litteratur. 83 synergier, 45 målkonflikter och 16 fall där dessa hänger ihop med att samarbete krävs i regionen identifierades. Genom att öka tillgången till elektricitet, och på grund av dammen i sig, potentiellt både bidrar till och förhindrar GERD hållbar utveckling i förhållande till miljö, samhälle och ekonomi. Identifierade nyckelåtgärder för att förstärka synergierna och minimera målkonflikterna är att etablera ett bestående samarbete mellan Etiopien, Egypten och Sudan; att säkerställa ökad transparens, deltagandeprocesser och allmän tillgång till information; att utreda och utföra åtgärder som är till nytta för områdets ekologi; och att förstärka de positiva resultaten av elektrifiering genom kompletterande åtgärder.
338

Empire’s Stores: The Architecture of Conveyance and Corporate Imperialism in America, 1890–1930

Sturtevant, Elliott January 2024 (has links)
This dissertation examines how American businesses’ focus on transportation and trade came to be key agents of US imperialism at the turn of the twentieth century. Extending our understanding of the architecture and urbanism of US industry and commerce, “Empire’s Stores” turns to the design, construction, and maintenance of transnational and transimperial supply chains and the physical infrastructure that made them possible—what I call the architecture of conveyance. Divided into four chapters, the project examines the built environment created by a set of firms and related industries selected geographically: to the West, the “Big Five” sugar factors and their predecessors operating in the Hawaiian Islands; to the North, the Niagara Falls Power Company and related hydroelectric concerns located along the Niagara Frontier; to the South, the United Fruit Company’s operations, including both tourism and trade, anchored in the Port of New Orleans; and, to the East, the storage, handling, and shipment of freight at the Bush Terminal Company in Brooklyn, New York. Through these case studies I show how American corporations produced and profited from imperial formations and, in doing so, reshaped territorial, geographic, and economic borders.
339

Habitat use by fishes of the New River, West Virginia

Lobb, M. Delbert January 1986 (has links)
Density estimates of the species and life stages in different habitat types were made from electrofishing collections and underwater fish counts. During midday, fish densities in edge pool and riffle habitats were comparable, but densities in edge pool habitat were significantly higher than densities in middle pool and run habitats. Snag and edge riffie habitats supported the highest densities of fish. Habitat use and activity shifts between daytime and nighttime were found for many species. Fish species and lifestage composition and densities differed among the habitat types, and five habitat-use guilds (edge-pool, middle-pool, edge-channel, riffie, and generalists) were described. Larger centrarchids preferred deep habitats with slow velocities (deep edge and middle pool, and snags), while young centrarchids preferred shallower habitat. However, all sizes of smallmouth bass were nearly ubiquitous in the habitats of the study area. The cyprinids and percis preferred shallow areas, but preferences for velocity differed among the species and lifestages. Spawning and habitat preferences of the endemic bigmouth chub, Nocomis platyrhynchus, were described. Bigmouth chubs used areas with plenty of small to large gravel (3-64 mm diameter), shallow depths, and moderate velocities for constructing spawning mounds. Bigmouth chubs were seen only using riffie and adjacent run habitat during late summer. Within these areas, depth, velocity, substrate, and cover were used in accordance with their availability, except for an avoidance of the shallowest available depths. Bigmouth chubs occupied positions near the substrate, where velocities were slower than the mean water column velocity. / M.S.
340

En fossilfri elframtid : En kvantitativ analys av samvariationen mellan sol-, vind- och vattenkraft för en fossilfri elproduktion i Sverige / A fossil free future

Berg, Moa, Blomqvist, Victor January 2024 (has links)
Syftet med studien var att undersöka samvariationen och korrelationen mellan de variabla förnybara energikällorna sol-, vind- och vattenkraft i fyra olika begränsade områden i Sverige. Studien ämnade att identifiera mönster mellan energislagen för att undersöka huruvida ett elkraftsystem enbart baserat på förnybara energikällor i Sverige är möjligt. Initialt genomfördes en litteraturstudie i syfte att ge kvalitativt underlag för det komplexa ämnet som undersöktes. Analysen och den kvantitativa delen av studien grundades på historiska klimatologiska data. Arbetet genomfördes i sin tur med hjälp av mjukvaran Matlab, där data hanterades och bearbetades. Parametrar och variabler som diskuterades och identifierades var framförallt effektspektrum, korskovarians och korrelation. Tidigare forskning tyder på att både positiv och negativ korrelation mellan olika variabla energislag förekommer beroende på vilka geografiska förutsättningar och vilket tidsspann som undersökts. Denna studie fann att negativ korrelation mellan sol- och vindkraft återkom för samtliga platser som studerades, medan sol- och vattenkraft istället korrelerade positivt. För vatten- och vindkraft var resultaten inte lika entydiga utan olika resultat erhölls beroende på tidsintervallet. / The purpose of the study was to examine the co-variation and correlation among the variable renewable energy sources solar, wind and hydropower in four different confined regions in Sweden. The study aimed to identify patterns among the energy sources to investigate whether a power system based on renewable energy sources in Sweden is achievable. Initially, a literature review was conducted to provide qualitative background for the complex subject investigated. The analysis and quantitative aspect of the report were based on historical climatological data. The work was carried out using Matlab software, where data was handled and processed. Parameters and variables discussed and identified primarily included power spectrum, cross-covariance, and correlation. Previous research suggests both positive and negative correlations among different variable energy sources occur depending on the geographic conditions and time span studied. This study found that negative correlation between solar and wind power recurred for all sites examined, while solar and hydropower instead showed a positive correlation. For hydropower and wind power, the results were not as consistent, with different outcomes depending on the time interval analyzed.

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