Dissertations / Theses: 'Energy streams'

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Gunapati, Venkat Yashwanth. "CLOUD BASED DISTRIBUTED COMPUTING PLATFORM FOR MULTIMODAL ENERGY DATA STREAMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1399373847.

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Altawell, Najib. "A systematic approach to biomass and energy crop streams for co-firing." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522986.

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Fernandez, Rodriguez Emmanuel. "Analysis of floating support structures for marine and wind energy." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/analysis-of-floating-support-structures-for-marine-and-wind-energy(f4870ce2-b8b5-4c7e-ba7e-f91a1d3c4bc9).html.

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Bed connected support structures such as monopiles are expected to be impractical for water depths greater than 30 m and so there is increasing interest in alternative structure concepts to enable cost-effective deployment of wind and tidal stream turbines. Floating, moored platforms supporting multiple rotors are being considered for this purpose. This thesis investigates the dynamic response of such floating structures, taking into account the coupling between loading due to both turbulent flow and waves and the dynamic response of the system. The performance and loading of a single rotor in steady and quasi-steady flows are quantified with a Blade Element Momentum Theory (BEMT) code. This model is validated for steady flow against published data for two 0.8 m diameter rotors (Bahaj, Batten, et al., 2007; Galloway et al., 2011) and a 0.27 m diameter rotor (Whelan and Stallard, 2011). Time-averaged coefficients of thrust and power measured by experiment in steady turbulent flow were in agreement with BEMT predictions over a range of angular speeds. The standard deviation of force on the rotor is comparable to that on a porous grid for comparable turbulence characteristics. Drag and added mass coefficients are determined for a porous disc forced to oscillate normal to the rotor plane in quiescent flow and in the streamwise axis in turbulent flow. Added mass is negligible for the Keulegan Carpenter number range considered ( less than 1). The drag coefficient in turbulent flow was found to decay exponentially with number, to 2±10% for values greater than 0.5. These coefficients were found to be in good agreement with those for a rotor in the same turbulent flow with disc drag coefficient within 12.5% for less than 0.65. An extreme-value analysis is applied to the measured time-varying thrust due to turbulent flow and turbulent flow with waves to obtain forces with 1%, 0.1% and 0.01% probability of exceedance during operating conditions. The 1% exceedance force in turbulent flow with turbulence intensity of 12% is around 40% greater than the mean thrust. The peak force in turbulent flow with opposing waves was predicted to within 6% by superposition of the extreme force due to turbulence only with a drag force based on the relative wave-induced velocity at hub-height estimated by linear wave theory and with drag coefficient of 2.0. Response of a floating structure in surge and pitch is studied due to both wave- forcing on the platform defined by the linear diffraction code WAMIT and due to loading of the operating turbine defined by a thrust coefficient and drag coefficient. Platform response can either increase or decrease the loading on the rotor and this was dependant on the hydrodynamic characteristics of the support platform. A reduction of the force on the rotor is attained when the phase difference between the wave force on the support and the surface elevation is close to ± and when the damping of the support is increased. For a typical support and for a wave condition with phase difference close to , the 1% rotor forces were reduced by 8% when compared to the force obtained with a rotor supported on a stiff tower.

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Colon-Gaud, Jose Checo. "ENERGY FLOW AND MACROINVERTEBRATE PRODUCTION IN PANAMANIAN HIGHLAND STREAMS: ASSESSING THE IMPACTS OF AMPHIBIAN DECLINES." OpenSIUC, 2008. https://opensiuc.lib.siu.edu/dissertations/280.

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Amphibian populations around the world have been declining rapidly over the past two decades, particularly in upland regions of the neotropics, where a fungal pathogen that causes chytridiomycosis has decimated many regions. Despite increasing concern over these and other dramatic losses of biodiversity, little information is available on the overall ecological effects of amphibian declines. As part of the Tropical Amphibian Declines in Streams (TADS) project, I quantified major energy fluxes, secondary production, and macroinvertebrate community structure for two consecutive years in four stream reaches in the Panamanian uplands, two with healthy amphibian populations and two that had experienced amphibian declines in 1996-1997. Despite relatively high year-round inputs of allochthonous organic materials, storage of detritus in the stream channels was low compared to streams in temperate regions. Organic matter inputs and standing stocks were similar between pre- and post-decline streams, and did not differ appreciably with season. Seston export was a major energetic flux in these systems, and differences in the nutritional quality (C:N) of seston in pre- and post-decline streams suggested that the loss of tadpoles may decrease the quality of materials exported from these headwaters. At coarse scales (e.g., total abundance) macroinvertebrate assemblages were similar between pre- and post-decline sites, but there were noticeable differences in production and functional and taxonomic structure. Pre-decline reaches had higher shredder production and post-decline streams had higher scraper production. In addition, taxonomic differences between pre- and post-decline streams were also evident, with a shift from dominance of smaller scraper taxa in pre-decline sites (i.e. Psephenus) to larger-bodied scrapers such as Petrophila in post-decline reaches. Filterer production was dominated by hydropsychid caddisflies in pre-decline reaches, whereas black flies dominated filterer production in post-decline reaches. Overall, detritus and detritivores dominated energy flow in all study reaches. However, scrapers were well represented in these systems and appeared to be food-limited, particularly in pre-decline reaches where grazing tadpoles were still abundant. During the second year of my study, predicted amphibian declines began at the pre-decline site. The loss of amphibians through this year resulted in subtle shifts in macroinvertebrate functional and taxonomic structure, which correlated with changes in available food resources. Some grazing mayflies responded positively to declining tadpole populations and subsequent increased periphyton resources, suggesting a potential for some degree of functional redundancy in these systems. However, other grazers, such as the water penny beetle Psephenus, showed no response during the period of study. My results indicate that responses of remaining consumers to tadpole declines in streams may not be evident at some coarse scales (e.g., total abundance, biomass). However, differences in secondary production at the community and the functional level, along with assemblage structure changes were evident, with some individual taxa responding relatively quickly. Long-term studies in these same stream reaches will further illuminate the ultimate ecological consequences of these dramatic and sudden losses of consumer diversity.

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Colón-Gaud, José Checo. "Energy flow and macroinvertebrate production in Panamanian highland streams : assessing the impacts of amphibian declines /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674100701&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2008.
"Department of Zoology." Keywords: Amphibians, Biodiversity, Declines, Macroinvertebrates, Production, Streams. Includes bibliographical references (p. 100-114). Also available online.

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Hogsden, Kristy Lynn. "Structure and function of food webs in acid mine drainage streams." Thesis, University of Canterbury. School of Biological Sciences, 2013. http://hdl.handle.net/10092/10357.

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Acid mine drainage (AMD) is a significant environmental issue worldwide, which often causes severe contamination and marked species losses in receiving streams. However, little is known about how this stress alters food webs and ecosystem function. I conducted a literature review, which revealed that AMD-impacted streams generally had depauperate benthic communities dominated by a few tolerant species and impaired ecosystem processes. Next, using survey and experimental-based approaches, I investigated food web structure and energy flow in these highly stressed streams, which typically have low pH (< 3), high concentrations of dissolved metals (Al, Fe), and substrata coated with metal hydroxide precipitates, on the South Island, New Zealand. Inputs of AMD caused substantial loss of consumers and reduced the overall number of links between species generating small and simplified food webs, with few invertebrates and no fish. Comparative analysis of food webs from a survey of 20 streams with either anthropogenic or natural sources of acidity and metals, indicated that anthropogenic sources had a stronger negative effect on food web properties (size, food chain length, number of links); an effect driven primarily by differences in consumer diversity and diet. However, the presence of fewer trophic levels and reduced trophic diversity (detected using isotopic metrics), were common structural attributes in AMD-impacted webs along a pH gradient, regardless of impact level. Furthermore, complementary dietary analyses of consumer gut contents and stable isotope signatures (δ13C and 15N) confirmed that primary consumers fed generally on basal resources and that there were few predatory interactions, which reflected low densities of small-bodied chironomids. This suggests that food quantity was unlikely to limit primary consumers but that reduced prey availability may be an additional stressor for predators. In these radically re-structured food webs, trophic bottlenecks were generated at the primary consumer level and energy flow to higher consumers was disrupted. However, streams still retained some limited function, including slow leaf litter breakdown, which provided detrital resources and supported the small food webs. Overall, my findings have furthered our understanding of these highly stressed stream ecosystems by providing new insights into interactions among species and trophic levels that structure food webs and enable function.

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Merck, Madeline F. "Variability of Water Storage and Instream Temperature in Beaded Arctic Streams." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/912.

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The purpose of this study is to investigate variation in water export and instream temperatures throughout the open water season in a beaded Arctic stream, consisting of small pools connected by shallow chutes. The goals are to better understand heat and mass movement through these systems, how this may impact chemical and biological processes, and the resulting shifts with changes in climate. This is accomplished by first examining the extent and variability of water storage and export through qualitative analysis of observational data. Further, heat fate and transport is examined through development of an instream temperature model. The model formulation, a simple approach to model calibration and validation, and information regarding residence and characteristic times of different pool layers are presented. Using temperatures measured at high spatial resolution within the pools and surrounding bed sediments as well as other supporting data (e.g., instream flow, specific conductivity, weather data, and bathymetry), various types of storage within the pools, banks, and marshy areas within the riparian zone, including subsurface flow paths that connect the pools, were found. Additionally, data illustrated that some pools will stay stratified during higher flow periods under certain weather conditions. Through modeling efforts, the dominant heat sources were found to vary between stratified layers. It was also found that potential increases in thaw depths surrounding these pools can shift stratification and mixing patterns. These shifts can further influence mass export dynamics and instream water quality. Given the amount and different types of storage within these systems and the influence of stratification patterns on the residence times in the pools, Imnavait Basin and similar beaded Arctic watersheds will likely experience delayed export of nutrients that are limiting in most Arctic systems.

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Deront, Eva. "L’Atome de la Discorde : évolutions de la politique nucléaire de l’Union européenne de 2000 à 2016." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAH002.

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Cette thèse étudie les conditions et l’ampleur des évolutions de la politique nucléaire de l’Union européenne, de 2000 à 2016. Depuis le milieu des années 1990, plusieurs événements – ou « fenêtres d’opportunité » selon la terminologie du Multiple Streams Framework – ont remis les politiques nucléaires au centre de l’attention des décideurs européens : l’adhésion de nouveaux Etats membres en 2004 ; différentes Présidences du Conseil et nominations de Commissaires ayant pris clairement position sur les questions nucléaires ; l’accident de Fukushima de mars 2011 ; et enfin, les deux sorties du nucléaire allemandes, en 2000 et 2011.La première partie de ce travail est consacrée à l’analyse de l’ampleur du changement introduit par les directives adoptées durant la période étudiée: les directives sûreté réacteur de 2009 et 2014, ainsi que la directive déchets radioactifs de 2011. La deuxième partie étudie les facteurs de stabilité qui ont empêché la mise à l’agenda ou l’adoption de certaines propositions, comme les politiques d’harmonisation des régimes de responsabilité civile ou comme les tentatives d’abolition du traité Euratom.Parmi les différentes variables testées, des coûts de mise en œuvre limités, ainsi que l’existence d’indicateurs pour un problème donné, sont apparus comme des conditions nécessaires (mais non suffisantes) pour un changement de politique.La variable la plus pertinente pour expliquer les changements contenus dans les directives adoptées est l’évolution de la place d’un problème dans les priorités des acteurs. L’accident de Fukushima n’a modifié ni les conditions objectives d’existence d’un problème, ni, sur le long terme, les priorités des Etats Membres ou du secteur nucléaire. Ainsi, les propositions post Fukushima tendant à augmenter le rôle de la Commission européenne ou une calibration plus stricte des mesures de sûreté ont donc été partiellement rejetées, pour finalement aboutir à une révision de la directive sûreté, en 2014, avec peu de changements. De même, la priorité accordée à la résolution des problèmes nationaux liés à gestion des déchets radioactifs a abouti à l’adoption d’une directive incluant des mesures plus précises.Les principaux changements ayant eu lieu dans les directives étudiées concernent leur logique instrumentale et leur calibration ; aucun changement n’a été observé dans les buts ou les orientations générales de la politique nucléaire de l’UE. La politique nucléaire de l’UE semble ainsi particulièrement stable.Cette thèse met en évidence plusieurs facteurs d’inertie des politiques et institutions d’Euratom, malgré l’action d’entrepreneurs politiques : le haut niveau de méfiance entre acteurs, la délégation de la sûreté à des agences indépendantes, la dépendance au sentier liée à la technologie nucléaire, et la flexibilité « incorporée » dans Euratom. Ces facteurs réduisent le nombre d’entrepreneurs politiques potentiellement efficaces ainsi que l’éventail de leurs stratégies pour promouvoir un changement. En plus des facteurs institutionnels, la stabilité des politiques et institutions est également promue par des veto players.Néanmoins, les problèmes récents auxquels est confronté le secteur nucléaire européen (intégration croissante de sources d’énergie renouvelable, difficultés économiques) érodent les conditions de reproduction et de stabilité des institutions d’Euratom. Cet aspect se traduit notamment dans le progressif retrait du nucléaire des communications officielles mentionnant les sources d’énergie à développer pour remplir les objectifs de l’Union.En se basant sur le MSF et sur l’institutionnalisme historique, cette thèse démontre ainsi que les évolutions de la politique nucléaire de l’UE requièrent trois conditions : l’action d’un entrepreneur politique, l’émergence d’un problème dans les priorités des principaux acteurs et, pour des changements d’orientation ou d’institution, l’érosion des mécanismes de reproduction
The goal of this dissertation is to understand the conditions under which the nuclear policy of the European Union has evolved – between 2000 and 2016 — as well as the scope of these evolutions. From the mid-1990s onwards, various events – “windows of opportunity” in the terminology of the Multiple Streams Framework – brought nuclear energy back to the attention of European policy-makers: the accession of new member states in 2004; different Council presidencies and nomination of Commissioners with a strong position on nuclear energy; the Fukushima accident in March 2011; Germany’s first and second nuclear phase-outs (in 2000 and 2011).This PhD proceeds in two parts: First, it analyses the scope of change in policies that have been set on the agenda and finally adopted (the reactor safety and the radioactive waste management directives); second, it analyses the stability factors that have hindered the agenda-setting or the decision-making on proposals for policy change or institutional reforms (harmonisations of civil liability regimes, licensing processes, or decommissioning funds; abolition of the Euratom treaty).Among the several variables tested, low implementation costs, as well as the existence of problem indicators, may be a necessary, but not a sufficient condition for policy change.The most relevant variable accounting for the policy changes included in the adopted directives, was the evolution of the problem in place of actors’ priorities. The Fukushima accident neither modified the objective conditions of existence of a problem, nor the long-term priority of Member States or the nuclear sector. Hence the post-Fukushima proposals suggesting an increase in the role of the European Commission or a stricter calibration of safety measures have been partially rejected. Hence there was no substantial policy change in the safety directive adopted in 2014. In a similar way, the priority granted to overcoming national problems of radioactive waste management led to the 2011 radioactive waste directive, which contained more settings than the 2009 reactor safety directive .The main changes observed in the directives impacted their settings, instrumental logic and calibration; no change has been observed in the goals or orientations of the EU nuclear policy since 2000. Therefore, the EU nuclear policy seems especially stable: in many cases, policy proposals did not even make in onto the agenda of the Council.In order to account for the stability of the policy in spite of the action of policy entrepreneurs, this PhD underlines the particular “stickiness” of the Euratom institutions and policies: The high distrust among actors; the delegation of safety to independent agencies; the technological path-dependence linked to the use of nuclear energy; and the “built-in” institutional flexibility of Euratom. These factors reduce the number of potential successful policy entrepreneurs and the range of strategies of change. Not only the institutional context but also the defiance among actors has accounted for the particular stability of the European nuclear policy and for the absence of change in goals or objectives: Stability was promoted by veto players, whose actions can be taken into account by the Multiple Streams Framework.Still, the recent problems facing the nuclear sector (growing renewable energy share, economic difficulties) are eroding the conditions of stability and mechanisms of reproduction of the European nuclear institutions. This is reflected in the progressive modification of the Commission’s official positions on nuclear energy, which is no longer included in the energy sources to be developed to meet the EU’s energy objectives.Relying both on the MSF and the historical institutionalism, this PhD shows that change in the European nuclear policy requires the action of a policy entrepreneur, the erosion of reproduction mechanisms and the occurrence of a problem among the priorities of main actors

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Taylor, Stephen H. "Analytical Modeling and Optimization of a Thermoelectric Heat Conversion System Operating Betweeen Fluid Streams." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2813.

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Analytical, closed-form solutions governing thermoelectric behavior are derived. An analytical model utilizing a thermal circuit is presented involving heat transfer into, through, out of, and around a thermoelectric device. A nondimensionalization of the model is presented. Linear heat transfer theory is applied to the model to obtain a series of closed form equations predicting net power output for the thermoelectric device. Fluid streams flowing through shrouded heat sinks with square pin fins are considered for the thermal pathways to and from the device. Heat transfer and pressure drop are characterized in a manner conducive to an analytical model using previously published experimental results. Experimental data is presented which validates and demonstrates the usefulness of the model in predicting power output for commercially available thermoelectric generators. A specific design for a thermoelectric power harvester is suggested consisting of a pattern of thermoelectric generators. An economic model for calculating payback time is developed. An optimization process is demonstrated that allows for the payback time of such a system to be minimized through optimization of the physical design of the system. It is shown that optimization of the thermal pathways dramatically reduces payback time. Optimized design of a system is discussed in light of theoretical cases with feasible payback times.

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Meyer, Lars Alan. "In Light of Energy: Influences of Light Pollution on Linked Stream-Riparian Invertebrate Communities." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345479410.

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Parreira, de Castro Diego Marcel. "Functional diversity and trophic relationships in benthic communities : a multi-scale spatial approach in neotropical savanna streams." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1092/document.

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Les changements d'intensité dans l'utilisation des sols et la dégradation de l'environnement en raison de activités humaines ont entraîné une forte altération des écosystèmes tropicaux, en particulier dans les cours d'eau de tête de bassin de la savane néotropicale. Les pressions humaines liées à l'expansion agricole et à l'urbanisation ont conduit à une réduction drastique de la couverture végétale indigène, affectant les zones riveraines et altérant le fonctionnement des écosystèmes aquatiques. Il est urgent de quantifier et de prévoir comment les communautés aquatiques répondent aux changements de l'utilisation des sols pour guider les efforts de conservation et de gestion des ressources naturelles. Dans ce contexte, cette thèse visait à évaluer à quelles échelles spatiales la relation entre habitat et communautés de macroinvertébrés benthiques s'exprimait le plus fortement et comment l'intensité d'utilisation des sols affectait les relations trophiques et la composition en traits biologiques des communautés de macroinvertébrés benthiques. Dans le chapitre 1, j'évalue comment l'intensité d'utilisation des sols (représentée par un gradient depuis la végétation autochtone, au pâturage, et à la plantation de canne à sucre et la végétation indigène) influe sur les flux d'énergie et les niches trophiques des macroinvertébrés benthiques. Ensuite, j'ai évalué à quelle échelle spatiale (bassin versant, localité) et pour quelles variables, le lien entre la composition taxonomique et fonctionnelle des assemblages de macroinvertébrés benthiques était le mieux exprimé (chapitre 2). Enfin, j'ai montré que les perturbations anthropiques avait unj impact sur la diversité fonctionnelle des assemblages de macroinvertébrés benthiques (chapitre 3). Les résultats présentés ici montrent que les changements d'intensité de l'utilisation des sols conduisent les assemblages de macroinvertébrés benthiques vers des comportements d'alimentation plus généralistes avec un chevauchement des niches trophiques (chapitre 1). De plus, les variables environnementales à l'échelle locale et du bassin versant expliquent de façon significative les variations de la composition taxonomique et fonctionnelle des assemblages d'Ephéméroptères, Plécoptères et Trichoptères, mais les variables décrivant l'intensité d'utilisation des sols expliquent le mieux les différences de composition fonctionnelle entre les différents sites (chapitre 2). Enfin, J'ai montré que les sites quasi-naturels (dans des conditions de référence) ont des assemblages de macroinvertébrés plus spécialisés comparés aux sites perturbés (chapitre 3). Les résultats corroborent le fait que la biodiversité doit être évaluée en tenant compte de variables agissant à de multiples échelles spatiales et que les éléments fonctionnels des communautés biologiques doivent être considérés, en vue de la conservation et du développement d'outils prédictifs. Cette étude contribue à une meilleure compréhension de la structure et du fonctionnement des cours d'eau dans la savane néotropicale dans le contexte du développement d'outils d'évaluation environnementale. Ces approches contribueront à l'élaboration de mesures de gestion et de conservation plus appropriées et permettront d'examiner les conséquences futures d'une poursuite de la dégradation des conditions écologiques dans les cours d'eau tropicaux
Changes in land cover and use and the associated environmental degradation due to human activities have resulted in extreme alterations of tropical ecosystems, especially in headwater streams and their watersheds in the neotropical savanna. Human pressures related to agricultural expansion and urbanization have led to drastic reductions in native vegetation cover, affecting riparian zones and degrading aquatic ecosystem functioning. There is an urgent need to quantify and predict how aquatic communities respond to different intensities of land use to guide conservation and natural resource management efforts. This thesis aims to evaluate how spatial scales influence the relationship between habitat and benthic macroinvertebrate communities and how land use intensity affects the trophic relationships and biological traits of macroinvertebrates. In Chapter 1, we evaluated how the intensity of land use (represented by a gradient moving from native vegetation toward pasture and sugar cane plantations) influences the energy flow and trophic niches of macroinvertebrates. In Chapter 2, we investigated the spatial scales (e.g., catchment, local) that most influence the taxonomic and functional composition of macroinvertebrate assemblages. Finally, in Chapter 3, we examined the impacts of human pressures on the functional diversity of macroinvertebrate assemblages. we showed that the intensity of land use affects benthic macroinvertebrate assemblages, yielding more generalist feeding behaviors with greater overlap of trophic niches (Chapter 1). In addition, environmental variables at the local and catchment scales significantly explained the variations in the taxonomic and functional composition of Ephemeroptera, Plecoptera and Trichoptera assemblages, but land use variables best explained the differences in functional composition among sites (Chapter 2). Finally, we showed that less impacted sites (under reference conditions) had more specialized and more functional diverse macroinvertebrate assemblages compared to disturbed sites (Chapter 3). These results corroborate the idea that biodiversity should be evaluated at multiple spatial scales and that the functional elements of biological communities should be considered when aiming for conservation and the development of predictive tools. This study contributes to a better understanding of the structure and functioning of streams in the neotropical savanna by subsidizing the development of environmental assessment tools. Such approaches will contribute to the development of more appropriate management and conservation measures that will allow for evaluation of the impacts on biota of further degradation of the ecological conditions in tropical streams

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Evans, E. M. "Tidal stream energy." Thesis, University of Plymouth, 1987. http://hdl.handle.net/10026.1/515.

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Lalander, Emilia. "Modelling the hydrokinetic energy resource for in-stream energy converters." Licentiate thesis, Uppsala University, Electricity, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-113597.

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Hydrokinetic energy, referring to the energy contained in moving water, is a renewable energy source that has gained much attention the past years. The energy is found in all moving water masses, but is only economical to convert for water masses moving with high velocity, i.e. likely around 1 m/s and above. This energy can for example be found in tidal, ocean and river currents which flow through narrow straits and channels. Along the west coast of Norway, there are many sites where kinetic energy conversion would be possible due to the strong current present. The driving force behind the currents is the tidal wave that progresses northward along the coast and increases in strength. The models that so far have been used for estimating the resource in Norway have been shown to be uncertain since they do not account for the fact that the velocities and the water levels are altered when energy is extracted. These effects can be simulated with numerical models. A channel in the Dal river, the Söderfors channel, is situated downstream a hydropower plant and was simulated with the numerical model MIKE. The water level alteration due to turbines was simulated. It was shown to be a lot less than the water level alteration caused by the level change in the downstream lake. Velocity profiles measured at several different locations were used to estimate how the power coefficient was changed. Four turbine configurations were studied and it was shown that changes in the power coefficient were prominent only for a vertical shear profile with a strong gradient. At the Division of Electricity, studies have been conducted on how to convert hydrokinetic energy to electricity since 2003. The main idea has been to use a system that limits the need for maintenance. The concept studied is a vertical axis turbine directly coupled to a permanent magnet generator. The Söderfors channel has, due to aspects such as the flow properties and velocity, been chosen as a site for an experimental station.

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Vogel, Christopher Reiner. "Theoretical limits to tidal stream energy extraction." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:68486b23-d773-44ad-a353-7efc855dc8ff.

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Tidal stream energy has gained attention as a source of predictable and renewable energy. Devices resembling underwater wind turbines, placed in fast tidal streams, have been proposed to extract this energy. Arrays of many such devices will need to be deployed to deliver a significant amount of energy to the electricity grid. One consequence of energy extraction is that the array provides a resistance to the tidal stream, which may change the local and far field hydrodynamics, which in turn affects the power available to the array. Array-scale hydrodynamic changes affect the flow presented to the devices, which in turn affects the total resistance the array provides to the flow. This thesis is concerned with the interactions between device, array, and the tidal stream resource, to better understand the power potential of turbine arrays. Linear momentum actuator disc theory is employed to describe the operation of an idealised turbine array partially spanning a wide channel. The model is comprised of two quasi-independent sub-models, an array-scale model, describing flow phenomena around the array, which provides the upstream boundary condition to the device-scale model, describing the flow around a device. The thrust applied by the array is the sum of the thrust applied by the devices, completing the sub-model coupling. The numerical simulation of arrays in depth-averaged simulations is then investigated using the two-scale concept developed in the analytic partial-array model. It is shown that the device-scale flow must be modelled with a sub-grid scale model in order to correctly describe the unresolved device-scale flow and hence estimate the power available to an idealised array. Turbulence modelling in depth-averaged simulations of turbine arrays is also discussed. Temporal variations in tidal amplitude and strength mean that generator capacity will need to be economically matched to the available resource. As device performance may consequently depart from the relationship derived in idealised models when power capping is employed, blade element momentum theory is modified to parameterise tidal turbine performance during power capping. The array-scale effect of power capping is studied in depth-averaged simulations, in which it is shown that a significant reduction in device thrust may occur during power capping, reducing the impact of energy extraction from the tidal stream.

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Dagà, Kunze Jordi Sebastián. "Aprovechamiento Hidroeléctrico de las Mareas y su Posible Desarrollo en Chile." Tesis, Universidad de Chile, 2008. http://repositorio.uchile.cl/handle/2250/103061.

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Utilizar fuentes de energía renovable es el desafío para el mundo civilizado del siglo XXI. Una fuente que ha sido poco explorada en Chile es la energía mareomotriz. Esta fuente depende de factores como el efecto gravitacional de la luna y el sol, fuentes que están aseguradas por muchos millones de años más. Además, las energías no renovables se están encareciendo cada día más, por lo que se espera que algún día estas nuevas fuentes de energías sean rentables. Por esto es importante estudiar el recurso de las mareas en nuestro país, y prepararse para cuando eso suceda. En este estudio se investiga acerca del fenómeno de las mareas y se estudia este recurso en Chile, haciendo así un diagnóstico del potencial mareomotriz que existe en este país. Además se analizan los lugares más propicios para el desarrollo de las diversas formas de explotar este recurso en Chile. Se exponen distintas tecnologías para aprovechar el potencial energético de las mareas, tanto las que aprovechan su energía potencial como las que utilizan la energía cinética generada por las corrientes de mareas. Se pone especial énfasis en esta última debido a que es una forma ambientalmente muy favorable de obtener electricidad. Para analizar la factibilidad económica de la explotación energética de este recurso se estudia la eficiencia energética de las distintas tecnologías analizando su factor de planta y el costo de la energía producida, se analiza la central mareomotriz más emblemática que es la central de La Rance, Francia. Además, se diseña un posible proyecto en Chile, utilizando la tecnología que aprovecha la energía cinética de las mareas y haciendo la evaluación económica de él.

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Loeva, Jessica. "Skolrelaterad stress hos kvinnliga gymnasieelever : En jämförelse mellan yrkesförberedande och teoretiskt program." Thesis, Högskolan i Gävle, Akademin för hälsa och arbetsliv, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-14513.

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Abstract Loeva, J (2013). Schoolrelated stress in female students – a comparison between vocational and theoretical program. The Academy for health and working life, University of Gavle. Purpose: To investigate and compare perceived stress and recovery among Swedish female students (high school, third degree) in a vocational program versus a theoretical program. Method: A cross-sectional study was conducted on forty female students (vocational program, n=20; theoretical, n=20) to give a cross section of the population in question. Data was collected by questionnaries, which included questions on perceived stress and energy levels, demand, control and social support at school. In addition, physical symptoms were measured. Results: This study showed that there were no differences between vocational and theoretical programs regarding perceived stress. There was a significant difference in energy between the groups after school, where students in vocational programs had more energy after school than students in theoretical programs. The results showed that both groups had similar requirements but that students in vocational programs experienced less control on their study situation. Social support and physical symptoms was similar in both groups. Conclusion: This study shows no differences in perceived stress and energy levels during the school day. In contrast, the perceived energy level after school where lower among students in theoretical programs. Within a stress and energy perspective it doesn´t matter which program the student choose.
Sammanfattning Syfte: Att undersöka och jämföra upplevd stress och återhämtning bland svenska kvinnliga studenter (tredje årets gymnasieelever) i ett yrkesförberedande program jämfört mot ett teoretiskt program. Metod: En tvärsnittsstudie genomfördes på fyrtio kvinnliga studenter (yrkesförberedande program, n = 20, teoretiskt program, n = 20) för att ge ett tvärsnitt av befolkningen i fråga. Data samlades in genom enkäter, vilket inkluderade frågor om upplevda stressnivåer, återhämtning, krav, kontroll och socialt stöd i skolan. Dessutom mättes fysiska symtom. Resultat: Denna studie visade att det inte fanns några skillnader mellan yrkesförberedande och teoretiskt program gällande upplevd stress. Det fanns en signifikant skillnad i energi efter skolan mellan grupperna, där elever på yrkesförberedande program hade mer energi efter skolan än elever på teoretiskt program. Resultatet påvisade att båda grupperna hade lika krav men att elever i yrkesförberedande program upplevde mindre kontroll kring sin studiesituation. Sociala stödet och fysiska symtom var lika i båda grupperna. Slutsats: Denna studie visar inga skillnader i upplevd stress. Däremot var upplevd energi efter skolan lägre bland elever i teoretiskt program. Slutsatsen är att det inte spelar någon roll vilket gymnasieprogram eleverna studerar utifrån ett stress-energi perspektiv, eftersom elever från både teoretiska och yrkesinriktade program upplever samma nivå av stress och energi under skoldagen. Samtidigt finns andra faktorer som kan skapa stress som inte undersökts i denna studie, så som elevernas egna ställda krav, prestationsångest och jämförelse mot andra elevers skolprestation.

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Lande-Sudall, David. "Co-located offshore wind and tidal stream turbines." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/colocated-offshore-wind-and-tidal-stream-turbines(72acb21d-1b88-45ad-b944-3f9664330420).html.

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Co-location of offshore wind turbines at sites being developed for tidal stream arrays has been proposed as a method to increase capacity and potentially reduce the cost of electricity compared to operating either technology independently. This research evaluates the cost of energy based on capital expenditure and energy yield. It is found that, within the space required around a single 3 MW wind turbine, co-location provides a 10-16% cost saving compared to operating the same size tidal-only array without a wind turbine. Furthermore, for the same cost of electricity, a co-located farm could generate 20% more yield than a tidal-only array. These results are based on analysis of a case-study site in the Pentland Firth. Wind energy is assessed using an eddy viscosity wake model in OpenWind, with a 3 MW rated power curve and thrust coefficient from a Vestas V90 turbine. Three years of wind resource data is from the UK Met Office UK Variable (UKV) 1.5 km numerical model and corrected against a 400 m Weather Research and Forecasting (WRF) model run over the site. Tidal stream energy is modelled using a semi-empirical superposition of self-similar plane wakes, with a generic 1 MW rated power curve and thrust based on a full-scale, fixed-pitch turbine. Coincident tidal resource data is from the Forecasting Ocean Assimilation Model (FOAM) at 7.5 km resolution and correlated with a 150 m ADvanced CIRCulation model (ADCIRC). Wave parameters are corrected from ERA-Interim data with six months of wave buoy data. Multiple tidal turbine array layouts are considered, with maximum tidal energy generated for a staggered array with spacing of 20 tidal turbine diameters, Dt , streamwise and 1.5Dt cross-stream. However, cheapest cost of electricity from the tidal-only array, was found for a single row of turbines, due to minimal wake effects. Laboratory experiments were undertaken to validate the superposition wake model for use with large, shared support structures. Two rotors mounted either side of a central tower generate a peak wake velocity deficit 70% greater than predicted by superposition. This was due to high local blockage and a complex near-wake structure, with a corresponding increase in tower drag of 9%. Further experiments evaluated the impact of oblique inflow on turbines yawed at +/-15 degrees. These results validated a theoretical cosine correction for thrust coefficient and characterised the centreline wake drift with downstream distance. Extreme environmental loads for a shared support structure, compared to structures for wind-only and tidal-only, have also been modelled. A non-linear wave model was used to represent a single wave form with 1% occurrence for each hour of time-series data. Overturning moment about the base of a shared support, with one wind and two tidal turbines, was found to be 4.5% larger than for a wind-only turbine in strong current and with turbines in different operational states. Peak loads across the tidal array were found to vary by 2.5% and so little load reduction benefit could be gained by locating a shared support in a more sheltered area of the array.

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Liang, Cao. "SmartCell: An Energy Efficient Reconfigurable Architecture for Stream Processing." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-dissertations/263.

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Data streaming applications, such as signal processing, multimedia applications, often require high computing capacity, yet also have stringent power constraints, especially in portable devices. General purpose processors can no longer meet these requirements due to their sequential software execution. Although fixed logic ASICs are usually able to achieve the best performance and energy efficiency, ASIC solutions are expensive to design and their lack of flexibility makes them unable to accommodate functional changes or new system requirements. Reconfigurable systems have long been proposed to bridge the gap between the flexibility of software processors and performance of hardware circuits. Unfortunately, mainstream reconfigurable FPGA designs suffer from high cost of area, power consumption and speed due to the routing area overhead and timing penalty of their bit-level fine granularity. In this dissertation, we present an architecture design, application mapping and performance evaluation of a novel coarse-grained reconfigurable architecture, named SmartCell, for data streaming applications. The system tiles a large number of computing cell units in a 2D mesh structure, with four coarse-grained processing elements developed inside each cell to form a quad structure. Based on this structure, a hierarchical reconfigurable network is developed to provide flexible on-chip communication among computing resources: including fully connected crossbar, nearest neighbor connection and clustered mesh network. SmartCell can be configured to operate in various computing modes, including SIMD, MIMD and systolic array styles to fit for different application requirements. The coarse-grained SmartCell has the potential to improve the power and energy efficiency compared with fine-grained FPGAs. It is also able to provide high performance comparable to the fixed function ASICs through deep pipelining and large amount of computing parallelism. Dynamic reconfiguration is also addressed in this dissertation. To evaluate its performance, a set of benchmark applications has been successfully mapped onto the SmartCell system, ranging from signal processing, multimedia applications to scientific computing and data encryption. A 4 by 4 SmartCell prototype system was initially designed in CMOS standard cell ASIC with 130 nm process. The chip occupies 8.2 mm square and dissipates 1.6 mW/MHz under fully operation. The results show that the SmartCell can bridge the performance and flexibility gap between logic specific ASICs and reconfigurable FPGAs. SmartCell is also about 8% and 69% more energy efficient and achieves 4x and 2x throughput gains compared with Montium and RaPiD CGRAs. Based on our first SmartCell prototype experiences, an improved SmartCell-II architecture was developed, which includes distributed data memory, segmented instruction format and improved dynamic configuration schemes. A novel parallel FFT algorithm with balanced workloads and optimized data flow was also proposed and successfully mapped onto SmartCell-II for performance evaluations. A 4 by 4 SmartCell-II prototype was then synthesized into standard cell ASICs with 90 nm process. The results show that SmartCell-II consists of 2.0 million gates and is fully functional at up to 295 MHz with 3.1 mW/MHz power consumption. SmartCell-II is about 3.6 and 28.9 times more energy efficient than Xilinx FPGA and TI's high performance DSPs, respectively. It is concluded that the SmartCell is able to provide a promising solution to achieve high performance and energy efficiency for future data streaming applications.

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Atwater, Joel. "Limitations on tidal-in-stream power generation in a strait." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/635.

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In the quest to reduce the release of carbon dioxide to limit the effects of global climate change, tidal-in-stream energy is being investigated as one of many possible sustainable means of generating electricity. In this scheme, turbines are placed in a tidal flow and kinetic energy is extracted. With the goal of producing maximum power, there is an ideal amount of resistance these turbines should provide; too little resistance will not a develop a sufficient pressure differential, while too much resistance will choke the flow. Tidal flow in a strait is driven by the difference in sea-level along the channel and is impeded by friction; the interplay between the driving and resistive forces determines the flow rate and thus the extractible power. The use of kinetic energy flux, previously employed as a metric for extractible power, is found to be unreliable as it does not account for the increased resistance the turbines provide in retarding the flow. The limits on extraction from a channel are dependant on the relationship between head loss and velocity. If head loss increases with the square of the velocity, a maximum of 38% of the total fluid power may be extracted; this maximum decreases to 25\% if head loss increases linearly with velocity. Using these values, the estimated power potential of BC's Inside Passage is 477MW, 13% of previous assessments. If a flow has the ability to divert through a parallel channel around the installed turbines, there are further limits on production. The magnitude of this diversion is a function of the relative resistance of impeded and diversion channels. As power extraction increases, the flow will slow from its natural rate. This reduction in velocity precipitously decreases the power density the flow, requiring additional turbine area per unit of power. As such, the infrastructure costs per watt may rise five to eight times as additional turbines are installed. This places significant economic limitations on utility-scale tidal energy production.

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Bergström, Maria. "Effekter av körsång." Thesis, Karlstads universitet, Institutionen för sociala och psykologiska studier, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-62929.

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Syftet med studien var att undersöka effekter av körsång, hos körsångare. Trots körsjungandets populäritet och omvittnade fördelar, har relativt få forskare undersökt omfattningen av de förmodade positiva effekterna av körsång på välbefinnande. Vid en systematisk genomgång av forskning som rörde körsång och välbefinnande konstaterades att många studier har skett i liten skala och varit kvalitativa, med endast ett fåtal stora kvantitativa undersökningar eller väl utformade experiment. Föreliggande studie ville bidra med kunskap på området genom att kvasi-experimentellt undersöka körsjungandets effekter avseende stress och energi samt positiv och negativ affekt. Deltagarna i studien var 20 körsångare från två olika körer, varav åtta män och tolv kvinnor i blandad ålder. Data erhölls genom psykometriskta test bestående av självskattningsformulär, före och efter körsång. Med körsång avsågs en körövning då kören repeterade. För statistisk bearbetning av datamaterialet användes statistiskprogrammet SPSS. Där gjordes beräkningar av deskriptiv statistik och beroende t-tester. För att undvika massignifikans presenterades resultaten utifrån p<0,0125 (0.05/4) en så kallad Bonferroni-korrektion. Resultatet visade att körsång minskade stressnivån och ökade energinivån samt att positiv affekt ökade och negativ affekt minskade. Resultatet var signifikant. Slutsatsen var att körsjungande ökade välbefinnandet. Det är troligtvis ingen nyhet för Sveriges 600 000 körsångare men slutsatsen kan få betydelse i andra sammanhang, som i skolan och på arbetsplatser.
The purpose of the study was to investigate the effects of choir singing. Despite the popularity of choir singing and its proven advantages, relatively few researchers have studied the extent of the supposed positive effects of choir singing on well-being. In a systematic review of research related to choir singing and well-being, it was found that many studies have taken place on a small scale and have been qualitative, with only a few large quantitative studies or well-designed experiments. The present study would contribute knowledge in the field by making a quasi-experimental study of the effects of choir singing regarding stress levels and energy, plus positive and negative emotions. The participants in the study were 20 choir singers from two different choirs, eight men and twelve women of mixed ages. Data was obtained through a psychometric test consisting of a self-assessment form, before and after choir practice. For statistical processing of the data, the statistical program SPSS was used. Calculations were made of descriptive statistics and dependent t-tests. In order to avoid mass significance, the results were presented based on p <0.0125 (0.05 / 4) a so-called Bonferroni correction. The results showed that choir singing decreased stress levels and increased energy levels and that positive emotions increased and negative emotions decreased. The result was significant. The conclusion was that choir singing increased well-being. It is probably no news for Sweden's 600,000 choir singers, but the conclusion could be important in other contexts, such as at school and at workplaces.

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Potgieter, Suretha. "Metabolic energy management and cancer / Suretha Potgieter." Thesis, North-West University, 2007. http://hdl.handle.net/10394/9086.

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This study examined the energy dependence of cancer cells. Glucose was found to be their main energy source. It seems possible to use this dependence to advantage in the fight against cancer. A novel experiment to reduce the blood glucose supply and utilisation was proposed. It entailed caloric restriction, suppression of glucose secretion by the liver as well as suppression of stress hormones (which elevates glucose levels). This minimises the blood glucose value. As a last step, anti-insulin is provided to inhibit cancer cells to utilise the glucose. The cancer cells are thus deprived of their main energy source. This should lead to a reduction or elimination of tumours and will aid in preventing their development. Although feasible, this method turned out to be too expensive to perform the necessary clinical trials to prove the hypothesis. Next, the focus shifted to cancer prevention. The human energy system was analysed with the goal to reduce the circulating glucose level. The main focus here was metabolised CHO energy consumption. A previously proposed unit – the Equivalent Teaspoon Sugar, or ets , was used to quantify energy with. It was shown that cancer risk increases significantly when the recommended ets consumption per day is exceeded. Furthermore, it was shown that including fibre in a meal reduces the ets value of the meal. One gram of fibre leads to a reduction of around 0.6 ets . The link between exercise, stress, fibre, their resulting blood glucose levels and cancer were quantified in terms of ets . Exercise expends ets , while stress causes the liver to secrete more ets . Experimental data was analysed to confirm the relationships. In conclusion an equation was formulated to describe the combined effect of all these elements on the energy system. One’s total daily ets consumption can be obtained from the equation, and it was linked to one’s cancer risk. Adapting a lifestyle that ensures the correct daily ets intake will lead to a significant reduction in cancer risk. This study proved that cancer cells are very dependent on sugar and a restriction of this energy source forces them into regression. Using this knowledge to advantage may help in the combat one of the biggest killers of our time – cancer.
Thesis (Ph.D. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2012

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Olczak, Alexander. "The influence of waves on tidal stream turbine arrays." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/the-influence-of-waves-on-tidal-stream-turbine-arrays(3ed6653f-1cc3-4e3b-ba03-5e5094a15ecc).html.

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The aim of this research was to quantify the influence of waves on arrays of tidal turbines. Experiments measured the wake of a turbine operating in combined wave-current flows, these were found to reduce velocity deficit as opposed to current only flow. The vertical region of the wake affected was dependant on the wave depth parameter, kd.RANS-BEM and Actuator Line methods were implemented within a commercial CFD code to provide computationally efficient methodologies for the simulation of both large turbine arrays and a turbine subjected to unsteady flow. For scaled experiments thrust coefficient was within 7% and 1% of the flume experiments for the RANS-BEM and Actuator Line methods respectively. The methods were found to give good prediction of a single turbine wake at distances greater than four diameters downstream, provided values of inlet turbulence intensity and length scale were equal to those measured experimentally.An unsteady Actuator Line method was used to quantify rotor loads and wake generation for a turbine operating within combined wave-current flow. The use of a streamwise pulsatile flow was found to give similar rotor and blade loads to simulations using a wave in a two phase volume of fluid simulation. The control strategy adopted by the turbine was found to greatly influence the computed rotor loads and blade bending moments. The wake generated by an Actuator Line method showed a reduction in velocity, however this was smaller than that measured experimentally for equivalent wave conditions.The accuracy with which the RANS-BEM method computed turbine loads and wakes was quantified for a number of one, two and three row arrays. The square of the disk averaged velocity encountered by turbines downstream of a single row of five turbines was found to be predicted to within 5% and 28% for an aligned and staggered arrangement respectively. For the two row arrays, the thrust of individual turbines was within 31% of the experimental measurements. The merged wake downstream of the multiple turbines was well predicted.Measurements of the wake of five porous disks showed combined wave-current flow did not alter the wake in the same manner as a single isolated disk. Measurement of wave energy over the wake showed the downstream current field altered wave propagation, causing a reduction in wave energy over the wake but an increase over the bypass flow. The accuracy of the wave model SWAN was assessed for the calculation of this change in wave characteristics. The model gave good prediction of the lateral variation of wave height over the far wake, however discrepancies in the near wake and upstream of the disk occurred.

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MacGillivray, Andrew John. "Economically sustainable development of wave and tidal stream energy technologies." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25405.

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The wave and tidal energy sectors have received much interest in recent years, from policy-makers attentive to the prospect that ocean energy technologies could be capable of contributing towards meeting environmental targets; from utility companies that expressed interest in developing, constructing and operating array projects to export large quantities of clean energy from ocean based resources; and from Small to Medium Enterprises (SMEs) and large multi-national Original Equipment Manufacturers (OEMs) that were interested in undertaking technological development to commercialise wave and tidal energy converters that could successfully harness the energy contained within the ocean waves and tides. Within the existing research, development and innovation environment that has largely dominated the development of wave and tidal energy to date – rapid development of large MW-scale devices capable of utility scale power generation – technology developers have failed to reach the level of deployed capacity that was initially anticipated, despite the significant level of investment that has taken place. Indeed, the expected contribution of ocean energy in the wider energy mix, which has been written into policy documentation at both national and European level, has so far failed to materialise in the form of prolific multiple device array deployments. The research, development and innovation environment has not delivered on its intended objective of demonstrating commercial technology readiness, and the historic development trajectories for ocean energy technologies may not represent the most cost-effective route to product commercialisation. This research explores the wave and tidal energy research, development, and innovation environment through extensive stakeholder engagement within the ocean energy sector, and through application of suitable techniques from innovation theory. The purpose of this research was three-fold. Firstly, an objective analysis of the development of the wave and tidal energy sectors – building a comprehensive understanding of their development to date through extensive stakeholder engagement, and comparing wave and tidal energy technology development with that of historic energy technologies that have successfully entered into commercial operation – was necessary in order to identify whether the attempt by ocean energy technologies for rapid up-scaling of technology is consistent with the development pathway that was followed by energy technologies which have successfully transitioned from novel invention to full commercial operation. This work identified several dichotomies that are present in the nascent stages of technology development in the wave and tidal energy sectors. Secondly, the uncertainties surrounding existing capital and revenue costs, and the uncertainties within the potential future cost reductions associated with current technology trajectories, could lead to unsustainable investment requirements. Commercialisation of wave and tidal energy technology is predicated upon significant cost reduction – the current technology costs are not feasible for large scale roll out of technology. A research focus on the economic uncertainty through application of learning theory and a learning investment sensitivity analysis was anticipated to demonstrate the economic impact of minor perturbations from idealised reference assumptions. The results from this work suggest that even minor perturbations in input parameters have substantial negative impact on overall investment requirements to bring technology to a level of cost competitiveness. Thirdly, the policy landscape surrounding wave and tidal energy development has not been specifically compared and contrasted, using a number of performance metrics, to a technology which was subject to similar expectations in the form of income streams – wind energy technology. The causes and motivations for the rapid transition to large-scale technologies and ‘accelerated innovation’ within ocean energy technology were considered within this research, which suggested that a mismatch between policy support and technological readiness could misguide and misdirect the innovation pathway, harming the commercialisation prospects of ocean energy technology. In order for the successful emergence of economically sustainable wave and tidal energy technologies, a paradigm shift may be necessary, a change from the current approach that has to date dominated technological development within both the wave and tidal energy sectors. This research draws together industry consultation with academic insight to identify an optimised innovation pathway, culminating in a policy appraisal to guide and inform economically sustainable development of wave and tidal energy technologies.

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Leach, Jason A. "Stream temperature dynamics following riparian wildfire : effects of stream-subsurface interactions and standing dead trees." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1411.

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The primary objectives of this study were to address how stream temperature is influenced by (1) spatial variability in energy exchanges, (2) reach-scale stream-subsurface water interactions and (3) the net radiation dynamics associated with standing dead riparian vegetation. Stream temperature, riparian microclimate, and hydrology were characterized for a 1.5 km reach of Fishtrap Creek, located north of Kamloops, British Columbia. Within-reach air temperature and humidity variability was small, while wind speed, net radiation and surface-subsurface interactions exhibited considerable spatially variability. The field data were used to drive a deterministic energy budget model to predict stream temperature. The model was evaluated against measured stream temperature and performed well. The model indicated that the spatially complex hydrology was a significant control on the observed stream temperature patterns. A modelling exercise using three canopy cover scenarios revealed that post-disturbance standing dead trees reduce daytime net radiation reaching the stream surface by one third compared to complete vegetation removal. However, standing dead trees doubled daytime net radiation reaching the stream compared to pre-wildfire conditions. The results of this study have highlighted the need to account for the spatial variability of energy exchange processes, specifically net radiation and surface-subsurface water interactions, when understanding and predicting stream thermal regimes.

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Behzadnia, Peyman. "Dynamic Energy-Aware Database Storage and Operations." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7125.

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Energy consumption has become a first-class optimization goal in design and implementation of data-intensive computing systems. This is particularly true in the design of database management systems (DBMS), which is one of the most important servers in software stack of modern data centers. Data storage system is one of the essential components of database and has been under many research efforts aiming at reducing its energy consumption. In previous work, dynamic power management (DPM) techniques that make real-time decisions to transition the disks to low-power modes are normally used to save energy in storage systems. In this research, we tackle the limitations of DPM proposals in previous contributions and design a dynamic energy-aware disk storage system in database servers. We introduce a DPM optimization model integrated with model predictive control (MPC) strategy to minimize power consumption of the disk-based storage system while satisfying given performance requirements. It dynamically determines the state of disks and plans for inter-disk data fragment migration to achieve desirable balance between power consumption and query response time. Furthermore, via analyzing our optimization model to identify structural properties of optimal solutions, a fast-solution heuristic DPM algorithm is proposed that can be integrated in large-scale disk storage systems, where finding the most optimal solution might be long, to achieve near-optimal power saving solution within short periods of computational time. The proposed ideas are evaluated through running simulations using extensive set of synthetic workloads. The results show that our solution achieves up to 1.65 times more energy saving while providing up to 1.67 times shorter response time compared to the best existing algorithm in literature. Stream join is a dynamic and expensive database operation that performs join operation in real-time fashion on continuous data streams. Stream joins, also known as window joins, impose high computational time and potentially higher energy consumption compared to other database operations, and thus we also tackle energy-efficiency of stream join processing in this research. Given that there is a strong linear correlation between energy-efficiency and performance of in-memory parallel join algorithms in database servers, we study parallelization of stream join algorithms on multicore processors to achieve energy efficiency and high performance. Equi-join is the most frequent type of join in query workloads and symmetric hash join (SHJ) algorithm is the most effective algorithm to evaluate equi-joins in data streams. To best of our knowledge, we are the first to propose a shared-memory parallel symmetric hash join algorithm on multi-core CPUs. Furthermore, we introduce a novel parallel hash-based stream join algorithm called chunk-based pairing hash join that aims at elevating data throughput and scalability. We also tackle parallel processing of multi-way stream joins where there are more than two input data streams involved in the join operation. To best of our knowledge, we are also the first to propose an in-memory parallel multi-way hash-based stream join on multicore processors. Experimental evaluation on our proposed parallel algorithms demonstrates high throughput, significant scalability, and low latency while reducing the energy consumption. Our parallel symmetric hash join and chunk-based pairing hash join achieve up to 11 times and 12.5 times more throughput, respectively, compared to that of state-of-the-art parallel stream join algorithm. Also, these two algorithms provide up to around 22 times and 24.5 times more throughput, respectively, compared to that of non-parallel (sequential) stream join computation where there is one processing thread.

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Martinez, Fabien. "Drag study of the nacelles of a tidal stream device using CFD." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/7440.

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Nowadays, renewable energy is in full growth. In particular, offshore wind farms will be at the centre of UK energetic strategy in the coming years. However, other types of marine renewable are still at an early development stage. That is the case for tidal energy. Many projects have been undertaken but there is no candidate for competitive commercial applications yet. Deltastream is one of these numerous pioneering projects. It consists of a set of three marine current turbines mounted on a triangular base put down onto the seabed. The device is not moored and no harm is done to the environment. However, that makes the structure more sensitive to water flows. And it is important to ensure that it will remain at its location and not being carried along with the tidal streams. Using CFD, the present study aims to evaluate the drag on the nacelles of the structure and come up with solutions to reduce it as much as possible.

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Johnson, P. "Hydrodynamics of tidal stream energy devices with two rows of blades." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1348136/.

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Tidal stream energy is an emerging low-carbon technology which could meet 5% of UK electricity demand. Current developments use ‘axial-flow’ rotors, which are efficient but limited in size, to generate electricity from ocean currents. This thesis investigates the hydrodynamics of a previously undeveloped rotor concept which has two rows of blades and also has no inherent size limit, hence it might achieve greater economies of scale. The rotor concept, called the ‘Moonraker’, is a cross-flow device with an oval blade path in the horizontal plane. This thesis presents research into the hydrodynamic performance of the Moonraker, focussing on the forces exerted on the blades by water currents and thereby deriving the thrust on and power generated by a Moonraker. The point vortex method was used to model the Moonraker and predicted high power coefficients when compared to a conventional cross-flow turbine with a circular blade path. A lab-scale Moonraker device was built and tested in the towing tanks at UCL and QinetiQ. The device was 2 m wide, 0.5 m high, with up to six blades and was towed at up to 0.7 m/s (blade Reynolds numbers were in the range 65,000--112,000). One of the blades was instrumented with strain gauges so that two components of blade loading could be recorded. Comparisons of predictions and measurements of blade loading showed some encouraging agreement, but also some disagreement, leading to suggested improvements in the modeling of the blade forces. The vortex model was subjected to further verification and validation tests in order to explore the issue of double actuator surfaces in close proximity. The extension of this work could help optimise the spacing between the two rows of blades on a Moonraker.

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Li, Xiaorong. "Three-dimensional modelling of tidal stream energy extraction for impact assessment." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3006766/.

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This research is themed around development of a tidal turbine simulation platform based on a three-dimensional oceanographic numerical modellling environment; more specifically, parameterization of effects of tidal turbine on flow current, turbulence, waves and sediment transport. In this context, the author adopts concepts in the current module, the turbulent module, the wave module and the sediment transport module of Finite-Volume, primitive equation Commmunity Ocean Model (FVCOM) to simulate the effects of tidal turbines. The retarding force concept is employed in the current module, working as an additional body force exerted on the water to simulate the turbine induced water deceleration. Three terms are added into the MY-2.5 turbulence closure to model turbine related turbulence generation, dissipation and turbulence length-scale interference. The built-in feature 'OBSTACLE' of the wave module is used to simulate the reduction of wave height caused by the turbine. The enhanced sediment suspension due to the turbine in motion is represented by an additional bottom shear stress term, entraining an extra portion of sediment particles from the bed into the water. Due to the fact that the bedload sediment transport module of FVCOM is not fully developed, it is not considered in this research; development of such a module is beyond the scope of this project. Coefficients of the turbine simulation terms are calibrated based on experimental data collected in the 'Total Environment Simulator laboratory flume' at the University of Hull, in which a prototype experiment was conducted. Small scale simulations carried out using ANSYS FLUENT also provided complementary calibration data. An idealized water channel model with mesh resolution fined down to the size of the simulated turbine is built to carry out the coefficient calibration. In general, the developed turbine simulation platform is capable of predicting reliable flow velocity, turbulent level, wave height and suspended sediment transport in the far wake region of the turbine, given proper values assigned to the relating coefficients. In addition, preliminary sensitivity tests are carried out to investigate the impact of these coefficients to the model's overall prediction to reveal the model's application range. Upon the satisfactory choices of the coefficients, the platform is applied to a 15m scale idealized single turbine case as well as a regional scale case based on the realistic hydrodynamics off the Anglesey coast, north-west of Wales. A series of single turbine tests are carried out with and without the turbine implementations, i.e. the coefficients represent turbine effects being switched on and off, in order to reveal the differences between the baseline case (no turbine) and case with turbine effects. Under realistic natural tidal and wave conditions, the Anglesey coast case showcases impact from a large scale turbine farm to both local and regional processes.

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29

Jagtap, Rohan Surendra, and Smruti Smarak Mohanty. "Sustainable Manufacturing: Green Factory : A case study of a tool manufacturing company." Thesis, Linköpings universitet, Energisystem, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168688.

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Efficient use of resources and utility is the key to reduce the price of the commodities produced in any industry. This in turn would lead to reduced price of the commodity which is the key to success. Sustainability involves integration of all the three dimensions: environmental, economic and social. Sustainable manufacturing involves the use of sustainable processes and systems to produce better sustainable products. These products will be more attractive, and the industry will know more about the climate impact from their production. Manufacturing companies use a considerable amount of energy in their production processes. One important area to understand the sustainability level at these types of industries is to study this energy use. The present work studies energy use in a large-scale tool manufacturing company in Sweden. Value Stream Mapping method is implemented for the purpose of mapping the energy use in the different operations. To complement this, an energy audit has been conducted, which is a method that include a study and analysis of a facility, indicating possible areas of improvements by reducing energy use and saving energy costs. This presents an opportunity for the company to implement energy efficiency measures, thus generating positive impacts through budget savings. Less energy use is also good for the environment resulting in less greenhouse gas emissions level. This also helps in long-term strategic planning and initiatives to assess the required needs and stabilize energy use for the long run. Social sustainability completes the triad along with environmental and economic sustainability. In this study, the social sustainability is reflected with the company’s relationship with its working professionals by conducting a survey. The sustainable manufacturing potential found in the case study indicates that significant progress can be made in the three sustainability dimensions. Although, the scope of the thesis is limited to a tool manufacturing company, several of the findings could be implemented in other tool companies as well as industries belonging to other sectors.

The thesis is a joint report between Linköping and Uppsala University. My thesis teammate has published it before at UU Diva Portal. The URL is: https://uu.diva-portal.org/smash/record.jsf?dswid=8179&pid=diva2%3A1449223&c=1&searchType=SIMPLE&language=en&query=sustainable+manufacturing&af=%5B%22dateIssued%3A2020%22%5D&aq=%5B%5B%5D%5D&aq2=%5B%5B%5D%5D&aqe=%5B%5D&noOfRows=50&sortOrder=author_sort_asc&sortOrder2=title_sort_asc&onlyFullText=false&sf=undergraduate

Green Factory project, AB Sandvik Coromant

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30

Balzer, Ulf. "European energy security and Nord Stream a case study of the Nord Stream pipeline, its opportunities and risks for Europe, and its impact on European energy security." Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5644.

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Approved for public release; distribution is unlimited.
tageous position over Europe concerning energy policies, thus raising the fears of Nord Stream's critics that Russia might use this leverage to promote its own position in political areas other than energy. It is, therefore, essential to analyze the opportunities and risks associated with Nord Stream for Europe, and to give thought for future mechanisms of European energy security that will assist in maximizing opportunities and minimizing risks.

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31

Yang, Xiufeng. "Ocean current energy resource assessment for the United States." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50352.

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Ocean currents are an attractive source of clean energy due to their inherent reliability, persistence and sustainability. The Gulf Stream system is of particular interest as a potential energy resource to the United States with significant currents and proximity to the large population on the U.S. east coast. To assess the energy potential from ocean currents for the United States, the characterization of ocean currents along the U.S. coastline is performed in this dissertation. A GIS database that maps the ocean current energy resource distribution for the entire U.S. coastline and also provides joint velocity magnitude and direction probability histograms is developed. Having a geographical constraint by Florida and the Bahamas, the Florida Current has the largest ocean current resource which is fairly stable with prevalent seasonal variability in the upper layer of the water column (~200m). The core of the Florida Current features higher stability than the edges as a result of the meandering and seasonal broadening of the current flow. The variability of the Gulf Stream significantly increases as it flows past the Cape Hatteras. The theoretical energy balance in the Gulf Stream system is examined using the two-dimensional ocean circulation equations based on the assumptions of the Stommel model for quasi-geostrophic subtropical gyres. Additional turbine drag is formulated and incorporated in the model to represent power extraction by turbines. Parameters in the model are calibrated against ocean observational data such that the model can reproduce the volume and kinetic energy fluxes in the Gulf Stream. The results show that considering extraction over a region comprised of the entire Florida Current portion of the Gulf Stream system, the theoretical upper bound of averaged power dissipation is around 5.1 GW, or 45 TWh/yr. If the extraction area comprises the entire portion of the Gulf Stream within 200 miles of the U.S. coastline, the theoretical upper bound of averaged power dissipation becomes approximately 18.6 GW or 163 TWh/yr. The impact of the power extraction is primarily constrained in the vicinity of the turbine region, and includes a significant reduction of flow strength and water level drop in the power extraction site. The turbines also significantly reduce residual energy fluxes in the flow, and cause redirection of the Gulf Stream. A full numerical simulation of the ocean circulation in the Atlantic Ocean is performed using Hybrid Coordinate Ocean Model (HYCOM) and power extraction from the Florida Current is modeled as additional momentum sink. Effects of power extraction are shown to include flow rerouting from the Florida Strait channel to the east side of the Bahamas. Flow redirection is stronger during peak summer flow resulting in less seasonal variability in both power extraction and residual fluxes in the Florida Current. A significant water level drop is shown at the power extraction site, and so is a slight water level rise along the coasts of Florida and the Gulf. The sum of extracted power and the residual energy flux in the Florida Current is lower than the original energy flux in the baseline case, indicating a net loss of energy reserve in the Florida Current channel due to flow redirection. The impact from power extraction on the mean flow field is concentrated in the near field of the power extraction site, while shifts in the far flow field in time and space have little impact on the overall flow statistics.

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32

Santos, Sílvia Camila Vasconcelos dos. "Cellular energy allocation of Chironomus riparius under toxic stress." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/9869.

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Mestrado em Biologia Aplicada
A alocação de energia celular (CEA) é um biomarcador energético que integra a análise das reservas energéticas disponíveis (conteúdo total de proteínas, lípidos e carbohidratos) e da energia consumida pelo organismo (sistema de transporte de eletrões), fornecendo uma análise global do estado metabólico dos organismos. Neste trabalho, este biomarcador foi usado como uma potencial ferramenta para a avaliação de efeitos do Cádmio e do inseticida Movento em larvas da espécie Chironomus riparius. Alterações no CEA foram comparadas com efeitos no crescimento e emergência dos organismos, de modo a avaliar a sensibilidade e relevância do CEA como uma ferramenta na avaliação de risco ecológico. Cádmio e Movento tiveram efeitos negativos no crescimento e na emergência dos organismos e o biomarcador energético revelou uma menor sensibilidade que os outros parâmetros para ambos os contaminantes. Contrariamente à exposição ao inseticida, onde não foram observadas diferenças na alocação de energia, o cádmio causou um aumento na energia consumida – provavelmente devido a um maior gasto de energia para a destoxificação. Uma menor quantidade de energia disponível irá, provavelmente, provocar uma redução nas taxas de desenvolvimento com consequências na emergência, afetando assim a reprodução e a dinâmica da população. Alterações na alocação de energia, dependendo da sua magnitude, podem estar intimamente relacionadas com alterações nos parâmetros individuais do ciclo de vida dos organismos (crescimento e reprodução), podendo ter consequências negativas em níveis de organização biológica superiores. Isto pode reforçar a importância de utilizar estes biomarcadores energéticos como uma potencial ferramenta na avaliação de risco ambiental. Contudo, e apesar do CEA ser utilizado como um biomarcador sensível em diferentes espécies de invertebrados, os resultados deste trabalho mostram que a sua utilização e interpretação em organismos modelo com ciclos de vida rápidos e complexos, como C. riparius, deve ser feita de forma cuidadosa.
The Cellular Energy Allocation (CEA) is an energetic biomarker that integrates the assessment of the available energy reserves (total content of protein, lipids and carbohydrates) and the energy consumed by the organism (electron transport system), providing an overall assessment of the metabolic status of the organisms. In this work, this biomarker was used as a prospective tool to assess the effects of Cadmium and the insecticide Movento to exposed midge larvae, Chironomus riparius. Alterations in CEA were compared to effects on growth and emergence in order to evaluate CEA’s relevance and sensitiveness as a tool in environmental risk assessment. Cadmium and Movento impaired the growth and emergence of the organisms and the energetic biomarker revealed less sensitivity than the other endpoints for both contaminants. Contrary to the insecticide exposure, where no differences in the energy allocation were observed, cadmium caused an energy allocation shift – towards the increase of the consumed energy - probably due to a higher energy demand for toxic defense purposes. Less energy available will most probably reduce development rates with consequences on the emergence thus affecting reproduction and population dynamics. Changes in the energy allocation, depending on their magnitude, are closely related to changes in the individual life cycle traits (growth and reproduction) and may therefore have major impacts in higher levels of biological organization. This may strengthen these energy based biomarkers as prospective tools in environmental risk assessment. Nevertheless and despite CEA’s potential use as a sensitive biomarker in different invertebrates species the results of this work call for a careful use and interpretation of CEA assessment in model test species, such as C. riparius, which have a rapid and complex life-cycle.

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33

Brown, Alice Goward. "Simulating feedbacks between tidal stream array operation and the marine energy resource." Thesis, Bangor University, 2017. https://research.bangor.ac.uk/portal/en/theses/simulating-feedbacks-between-tidal-stream-array-operation-and-the-marine-energy-resource(418a4dee-601e-44e5-b656-1a3c4870a9e7).html.

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Tidal streams have long since been acknowledged as a reliable and predictable source of energy. For tidal energy developments to be economically viable, the arrangement of tidal devices needs to consider regional complex flow conditions. First generation tidal energy development sites are selected on their proximity to port and grid infrastructure, water depth and mean spring current velocity. The layout of tidal energy devices within an array is planned to reduce blade fatigue. The continental shelf seas around the United Kingdom have world leading levels of tidal dissipation; Tidal streaming around the coastline is further accentuated by topographic complexities. The Crown Estate has leased numerous locations around the United Kingdom's shelf seas and a spatially representative selection of these sites has been characterised using the Regional Ocean Modeling System (ROMS). Using the HPC Wales system, high resolution regional 3-D models are developed. Model results enable maps of metrics which illuminate flow features important to tidal energy extraction, which include: tidal phasing, tidal asymmetry and the misalignment of flood and ebb tidal currents. From this assessment four leased tidal development sites within the Pentland Firth are highlighted as the most dynamic of the UK's leased tidal stream sites. Three-dimensional tidal energy extraction techniques are employed within each of the sites in the Pentland Firth which enables a technical resource assessment to be carried out. Furthermore, changing the hydrodynamics has a cumulative impact on natural physical processes of the coastal system. The non-linear nature of the interaction between tidal arrays and physical processes calls for more complex numerical modelling techniques to enable a full quantification of tidal energy development on marine systems.

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34

Akin, Manolya. "Turkey’s Foreign Energy Policy andRealist Theory : The Cases of Nabuccoand South Stream Gas Pipeline Projects." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-150752.

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This paper focuses on Turkey’s foreign energy policy with a special focus on cases ofNabucco and South Stream Gas Pipeline Projects and examines the issue from the perspectiveof “realist theory”.The research question aims to discover the realist tendency in Turkishforeign energy policy and to find out which gas pipeline project is more beneficial in terms ofnational interest for Turkey and also relevant for meeting the goals of Turkish Foreign EnergyPolicy.Energy is the key concept of the discussions about future of our world and sustainabledevelopment. If energy functions as a subject that increases the tensions between countriesthis means a threat to sustainable development since it becomes a factor jeopardizing peaceand makes cooperation between states imporssible. Also; energy constitutes a fundamentalplace national strategies of states along with sustainable development.In order to make the theory operational, three main dimensions, being security, economicsand strategic are used as tools or in other words as filters to look through, in the analysis offoreign and energy policy, as well as cases of Nabucco and South Stream Gas Pipeline Projects.

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35

Gay, Thomas Joseph. "Assessment of tidal stream energy potential for Marine Corps Recruit Depot Parris Island." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37293.

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The energy of the tides represents one globally existent source of renewable energy, and has the potential to play a major role in a sustainable future. An assessment of the potential for tidal energy extraction using marine current turbines at a particular location in the Beaufort River near Parris Island, South Carolina is presented. The Marine Corps Recruit Depot located on Parris Island is situated between the confluence of the Broad and Beaufort Rivers. These rivers are tidally dominated, and experience some of the largest tidal ranges in the southeastern United States, between 2.5 and 3 meters during spring tide periods. Because Parris Island already has much of the necessary land-based infrastructure in place, there is logical potential for the extraction of kinetic energy from the nearby tidal streams using underwater turbines for power production. In order to evaluate the potential of a particular location to produce significant amounts of energy using these types of devices, extensive investigations must be conducted to determine important site characteristics such as water depth, current velocity, and water level fluctuations over time. This potential was investigated using in-situ measurements in the vicinity of the pump station on Parris Island, and by developing a numerical model of the region using the Regional Ocean Modeling System (ROMS). This model was calibrated using the results from the in-situ measurements, and was then used to determine the impacts of tidal energy extraction on the local flow field. Results from in-situ measurements indicate that tidal currents along the portion of the Beaufort River analyzed in this study are driven primarily by the semi-diurnal M2 tidal constituent. The tidal range at the study site is approximately 2 meters on average, with a mean depth-averaged current velocity magnitude of 0.57 m/s predicted for a period of one year. A mean depth-averaged current velocity magnitude of 0.59 m/s was observed over the course of the longer-term ADCP deployment from November 12 to December 17, 2009. The maximum current speed at the site is approximately 1.2 m/s at the water surface. The ROMS model applied to the coastal areas surrounding Parris Island, SC produces results that closely resemble in-situ measurements collected previously during both the boat-based survey and the longer-term ADCP deployment. In the analysis of the effects of energy extraction from the system, four separate cases were considered in which 10, 20, 30, and 60% of the total kinetic energy contained in the flow was dissipated near the location of the longer-term ADCP deployment. Minimal impacts on the local hydrodynamics were observed across the four cases considered.

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36

Whiting, Daniel P. "Macroinvertebrate production, trophic structure, and energy flow along a tallgrass prairie stream continuum /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967802681&sid=3&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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37

Blunden, L. S. "New approach to tidal stream energy analysis at sites in the English Channel." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/73610/.

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Tidal stream power generation offers the prospect of predictable, low-CO2 power at a number of locations around the UK and the world. Previous assessments of tidal energy resources have taken the form of desk studies based on simplified navigational data. Where numerical model data has been used it has been at too low a resolution to capture high velocity tidal flows constrained by coastal topography. Analytical solutions for maximum energy extraction in simple tidal channels have been produced, but they have not been extended to more complex open-boundary cases such as flow around headlands and islands. There is therefore a role for site-specific numerical modelling, which when validated, offers the twin advantages of a high-resolution picture of the resource and allowing simulation of momentum extraction within the model to take place. In order to parameterize the sub-grid-scale momentum extraction in such models, a new analytical model of the velocity reduction in a large array of tidal turbines has been derived. The model extends previous models of large wind turbine arrays and uses analogies with flow through submerged vegetation. It provides an equivalent added drag coefficient suitable for use in a 2-D coastal numerical model. A numerical model of the flows in the region of the Portland Bill headland has been produced, forced by tidal elevations at the free boundary. A site selection exercise was carried out for the Portland Bill location and an area of around 12 km2 was identified as having a high potential for development using mean cubed speed found through tidal analysis of model results without energy extraction. A large tidal stream generator array has also been simulated within the Portland Bill model—linked to the new model for momentum extraction—and was found to have a significant effect on the tidal parameters in the locality. This was the first time that a large tidal array has been simulated in a realistic coastal domain of large extent, with a parameterization that takes into account the interaction of the turbines with the rough-wall flow in the natural state. Results predict that there is a region downstream of the array extending approximately 5–10 km around the simulated tidal stream turbine array in which the tidal stream ellipse major axis is reduced by at least 5%. In the area of momentum extraction the principal semi-diurnal tidal stream ellipse major axis length was reduced by 10–15%.

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38

Whiting, Daniel Philip. "MACROINVERTEBRATE PRODUCTION, TROPHIC STRUCTURE, AND ENERGY FLOW ALONG A TALLGRASS PRAIRIE STREAM CONTINUUM." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/120.

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Conceptual models of stream continua predict that energy flow and consumer functional structure change predictably with the physical attributes of a stream. To quantify these relationships in a prairie landscape, I estimated macroinvertebrate production, benthic organic matter standing stocks, and resource consumption and egestion by consumer groups along a longitudinal continuum of Kings Creek, a tallgrass prairie stream draining the Konza Prairie Biological Station in Eastern Kansas. I sampled benthic macroinvertebrates for 1 year from three stream reaches, each bordered by distinct riparian vegetation. Riparian vegetation along the continuum ranged from grassy headwaters to shrubby mid-reaches to lower reaches bordered by gallery forest. Total habitat-weighted production ranged from 31.9 g ash-free dry mass (AFDM) m-2 y-1 in the grassy headwater reach to 9.1 g AFDM m-2 y-1 in the shrubby reach to 17.0 g AFDM m-2 y-1 in the gallery forest. Functional group contributions to production generally were similar along the continuum, with collector-gatherers (40%-56% of total) and Predators (23%-38%) dominating all reaches. Quantitative food webs indicated detrital pathways dominated energy flow in all reaches, with collector-gatherers accounting for most energy flow through primary consumers. Predators were well represented and consumed 75% - 135% of total macroinvertebrate production whereas shredders (2-4%), scrapers (11-15%), and filterers (<1%) consumed a small percentage of their particular resources. High production and consumption estimates for macroinvertebrate predators suggest top-down controls are important in this system. Although functional structure was fairly similar among reaches, changes in energy flow through some groups reflected longitudinal changes in resource availability. Results indicate that this tallgrass prairie stream ecosystem is intermediate in the context of predictions of conceptual stream continua models, and biotic interactions may override some predicted responses to changes in the physical template.

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39

Melot, Nicolas. "Algorithms and Framework for Energy Efficient Parallel Stream Computing on Many-Core Architectures." Doctoral thesis, Linköpings universitet, Programvara och system, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132308.

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The rise of many-core processor architectures in the market answers to a constantly growing need of processing power to solve more and more challenging problems such as the ones in computing for big data. Fast computation is more and more limited by the very high power required and the management of the considerable heat produced. Many programming models compete to take profit of many-core architectures to improve both execution speed and energy consumption, each with their advantages and drawbacks. The work described in this thesis is based on the dataflow computing approach and investigates the benefits of a carefully pipelined execution of streaming applications, focusing in particular on off- and on-chip memory accesses. As case study, we implement classic and on-chip pipelined versions of mergesort for Intel SCC and Xeon. We see how the benefits of the on-chip pipelining technique are bounded by the underlying architecture, and we explore the problem of fine tuning streaming applications for many-core architectures to optimize for energy given a throughput budget. We propose a novel methodology to compute schedules optimized for energy efficiency given a fixed throughput target. We introduce \emph{Drake}, derived from Schedeval, a tool that generates pipelined applications for Many-Core architectures and allows the performance testing in time or energy of their static schedule. We show that streaming applications based on Drake compete with specialized implementations and we use Schedeval to demonstrate performance differences between schedules that are otherwise considered as equivalent by a simple model.

This thesis has also been funded by CUGS, Graduate School in Computer Science and FP7 EXCESS.

The electronic version has been corrected. See the published errata list.

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40

Senterzi, Zahide Tugba. "Visegrad Group Facing The Nord Stream And South Stream Gas Pipeline Projects." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614610/index.pdf.

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This thesis analyzes the Visegrad Group&rsquo
s stance toward the Russian-German Nord Stream and Russian-Italian South Stream gas pipeline projects, which aimed to circumvent the traditional energy routes situated in Central Europe and Eastern Europe. The level of the Visegrad Group&rsquo
s dependency on inherited Soviet gas pipeline routes is examined alongside the Visegrad Group&rsquo
s policy setting ability within the group itself and in the European Union. The thesis also traces the evolution of energy relations between Europe and Russia and Visegrad Group&rsquo
s adaptation to the new state of affairs after the collapse of the Soviet Union, particularly with respect to energy issues. It is argued that despite all differences, Visegrad Group members are able to set a cooperation platform at times of crisis and develop common energy strategies. However, the thesis shows that the Visegrad Group&rsquo
s endeavor has encountered some setbacks at the national level and serious challenges at the European level, largely owing to the lack of a common European energy policy. The thesis concludes that the Visegrad Group&rsquo
s energy policy is both dependent on the stances of Russia and larger EU actors.

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41

Lynch, Cathy. "Creating an alternative energy source for the streets of the world." University of Pittsburgh, 2008. http://etd.library.pitt.edu/ETD/available/etd-01102008-163141/.

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42

Ikeme, Patience Obianuju. "Human ecological stress and menstrual function." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360734.

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43

Tian, Yongzhe. "Applications of Slattery - Lagoudas' theory for the stress deformation behavior." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4252.

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The thermodynamics of three-dimensional, single-component elastic crystalline solids was developed by Slattery and Lagoudas (2005). Considering the inÃÂ¯nitesimal deformations, the stress can be expressed as a function of the lattice vectors and density in the reference configuration and ÃÂ¹(I;mn), which is defined as the derivative of specific Helmoholtz free energy with respect to the I(mn). Using the Cauchy - Born rule to connect the interatomic potential energy and the specific Helmholtz free energy, it is possible to calculate the elastic properties of both nano-scale materials such as carbon nanotubes and macro-scale materials such as diamond and silicon. In this study, we used TersoÃÂ® (1988a) - Brenner (1990b) Potential, TersoÃÂ® (1988b) potential and Finnis and Sinclair (1984) potential for carbon, silicon, and vanadium systems respectively. Using the interatomic potentials to describe the specific Helmholtz free energy, the elastic properties of graphite, diamond, silicon and vanadium were calculated. This method was also extended to the calculation of Young's modulus of single-walled carbon nanotubes (SWCNTs), which are composed of a two dimensional array of carbon atoms. For SWCNT, we get good agreement with the available experimental data. For diamond and silicon, C11 and C12 were consistent with both the superelastic model and the experimental data. The difference of C44 between the calculation and experimental data was due to accuracy of the potential functions.

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44

Lundberg, Gunilla, and Ulrika Svahn. "Hur stress kan påverkas av individens energi och av det privata stödet : En tvärsnittsstudie om stress, energi, privatstöd och copingstrategier." Thesis, Högskolan Väst, Avd för företagsekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-9691.

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Stress kan vara positivt och negativt. Lite stress kan skärpa sinnet och förmågan att arbeta, men en för lång period med stress är negativt och skadligt. Stress ökar i samhället, inte minst inom yrken som vård och omsorg. Denna studie syftar till att undersöka hur stress, privat stöd och energi i arbetslivet ser ut på tre äldreboenden. I studien undersöks även hur olika strategier kan påverka och förbättra enskilda individers stresspåverkan. En kvantitativ tvärsnittsstudie baserad på enkäter gör det empiriska underlaget. Tre äldreboenden har studerats för att undersöka sambandet mellan energi, privatstöd och stress. Studien visar att medarbetarna på äldreboendena känner sig slutkörda med höga krav och låg kontroll enligt stress- och energi modellen. Studien påvisar ett negativt samband mellan privat stöd och stress. När en deltagares privata stöd är högt är stressen låg men för de individer där privata stödet är lågt är istället stressen hög. Inga andra samband kan påvisas.
Stress can be positive and negative. A little stress can sharpen the mind and the ability to work, but a too long period of stress is negative and harmful. The stress is increasing in society, especially in professions as nursing and care. This study aims to examine how stress, private support and energy at work looks at three homes for the elderly. The study also explores how different strategies can influence and improve individuals' stress effects. A quantitative cross-sectional study based on surveys makes the empirical basis. Three elderly have been studied to examine the relationship between energy, private support and stress. The study shows that employees of nursing homes feel exhausted with high demands and low control by the stress and energy model. The study demonstrates a negative relationship between private support and stress. When a participant private support is high is the stress low but for those individuals where private support is low the stress is high. No other connection can be demonstrated.

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45

Hall, Melinda M. "Horizontal and vertical structure of velocity, potential vorticity and energy in the gulf stream." Thesis, Online version, 1985. http://hdl.handle.net/1912/3150.

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46

Hamilton, Nicholas Michael. "Anisotropy of the Reynolds Stress Tensor in the Wakes of Counter-Rotating Wind Turbine Arrays." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1848.

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A wind turbine array was constructed in the wind tunnel at Portland State University in a standard Cartesian arrangement. Configurations of the turbine array were tested with rotor blades set to rotate in either a clockwise or counter-clockwise sense. Measurements of velocity were made with stereo particle-image velocimetry. Mean statistics of velocities and Reynolds stresses clearly show the effect of direction of rotation of rotor blades for both entrance and exit row turbines. Rotational sense of the turbine blades is visible in the mean spanwise velocity W and the Reynolds shear stress -[macron over vw]. The normalized anisotropy tensor was decomposed yielding invariants [lowercase eta] and [lowercase xi], which are plotted onto the Lumley triangle. Invariants of the normalized Reynolds stress anisotropy tensor indicate that distinct characters of turbulence exist in regions of the wake following the nacelle and the rotor blade tips. Eigendecomposition of the tensor yields principle components and corresponding coordinate system transformations. Characteristic spheroids are composed with the eigenvalues from the decomposition yielding shapes predicted by the Lumley triangle. Rotation of the coordinate system defined by the eigenvectors demonstrates streamwise trends, especially trailing the top rotor tip and below the hub of the rotors. Direction of rotation of rotor blades is evidenced in the orientation of characteristic spheroids according to principle axes. The characteristic spheroids of the anisotropy tensor and their relate alignments varies between cases clearly seen in the inflows to exit row turbines. There the normalized Reynolds stress anisotropy tensor shows cumulative effects of the rotational sense of upstream turbines. Comparison between the invariants of the Reynolds stress anisotropy tensor and terms from the mean mechanical energy equation indicate a correlation between the degree of anisotropy and the regions of the wind turbine wakes where turbulence kinetic energy is produced. The flux of kinetic energy into the momentum-deficit area of the wake from above the canopy is associated with prolate characteristic spheroids. Flux upward into the wake from below the rotor area is associate with oblate characteristic spheroids. Turbulence in the region of the flow directly following the nacelle of the wind turbines demonstrates more isotropy compared to the regions following the rotor blades. The power and power coefficients for wind turbines indicate that flow structures on the order of magnitude of the spanwise turbine spacing that increase turbine efficiency depending on particular array configuration.

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47

García-Martín, Eva. "Extraction and Energy Efficient Processing of Streaming Data." Licentiate thesis, Blekinge Tekniska Högskola, Institutionen för datalogi och datorsystemteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15532.

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The interest in machine learning algorithms is increasing, in parallel with the advancements in hardware and software required to mine large-scale datasets. Machine learning algorithms account for a significant amount of energy consumed in data centers, which impacts the global energy consumption. However, machine learning algorithms are optimized towards predictive performance and scalability. Algorithms with low energy consumption are necessary for embedded systems and other resource constrained devices; and desirable for platforms that require many computations, such as data centers. Data stream mining investigates how to process potentially infinite streams of data without the need to store all the data. This ability is particularly useful for companies that are generating data at a high rate, such as social networks. This thesis investigates algorithms in the data stream mining domain from an energy efficiency perspective. The thesis comprises of two parts. The first part explores how to extract and analyze data from Twitter, with a pilot study that investigates a correlation between hashtags and followers. The second and main part investigates how energy is consumed and optimized in an online learning algorithm, suitable for data stream mining tasks. The second part of the thesis focuses on analyzing, understanding, and reformulating the Very Fast Decision Tree (VFDT) algorithm, the original Hoeffding tree algorithm, into an energy efficient version. It presents three key contributions. First, it shows how energy varies in the VFDT from a high-level view by tuning different parameters. Second, it presents a methodology to identify energy bottlenecks in machine learning algorithms, by portraying the functions of the VFDT that consume the largest amount of energy. Third, it introduces dynamic parameter adaptation for Hoeffding trees, a method to dynamically adapt the parameters of Hoeffding trees to reduce their energy consumption. The results show an average energy reduction of 23% on the VFDT algorithm.
Scalable resource-efficient systems for big data analytics

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Yuen, Katarina. "System Perspectives on Hydro-Kinetic Energy Conversion." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-181555.

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Free-flowing water currents such as tides and unregulated water courses could contribute to world electricity production given the emergence of robust technical solutions for extracting the energy. At Uppsala University, a concept for converting the energy in water currents to electricity using a vertical axis turbine with fixed blade-pitch and a direct-drive permanent magnet generator is studied. Technological equipment for extracting energy from water currents can be studied at desktop to some extent, but physical realizations, first in a laboratory setting, and later in a natural aquatic setting, are necessary. For this reason, a laboratory generator has been constructed and evaluated, and an experimental setup comprising turbine, generator and control system has been constructed. The turbine and generator are to be deployed in the Dalälven River in Söderfors, and operated from an on-land control station. The author has worked with constructing and evaluating the low-speed laboratory generator, participated in the design and construction of the Söderfors generator, and designed and constructed the control system for Söderfors. The generator design incorporates a low rotational speed, permanent magnets, and many poles, in order to adapt the generator to the nature of water currents. Simulations and experimental data for the laboratory prototype have been compared and show that the simulation tool used is adequate for design studies of this type of generator. The generator has also been shown to be able to operate with the intended turbine design and range of water velocities. The control system to be used in Söderfors has been tested in a laboratory environment. Simulations of the control system show that it should be able to operate the turbine and generator at the desired rotational speeds in water velocities up to about 1.8 m/s. Simulations of the system have also shown that maximizing system power output may not correspond with maximizing turbine power.

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Lai, Farley. "Stream processing optimizations for mobile sensing applications." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5797.

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Mobile sensing applications (MSAs) are an emerging class of applications that process continuous sensor data streams to make time-sensitive inferences. Representative application domains range from environmental monitoring, context-aware services to recognition of physical activities and social interactions. Example applications involve city air quality assessment, indoor localization, pedometer and speaker identification. The common application workflow is to read data streams from the sensors (e.g, accelerometers, microphone, GPS), extract statistical features, and then present the inferred high-level events to the user. MSAs in the healthcare domain especially draw a significant amount of attention in recent years because sensor-based data collection and assessment offer finer-granularity, timeliness, and higher accuracy in greater quantity than traditional, labor-intensive, data gathering mechanisms in use today, e.g., surveys methods. The higher fidelity and accuracy of the collected data expose new research opportunities, improve the reliability and accuracy of medical decisions, and empower users to manage personal health more effectively. Nonetheless, a critical challenge to practical deployment of MSAs in real-world is to effectively manage limited resources of mobile platforms to meet stringent quality of service (QoS) requirements in terms of processing throughput and delay while ensuring long term robustness. To address the challenge, we model MSAs in dataflows as a graph of processing elements that are connected by communication channels. The processing elements may execute in parallel as long as they have sufficient data to process. A key feature of the dataflow model is that it explicitly capture parallelism and data dependencies between processing elements. Based on the graph composition, we first proposed CSense, a stream-processing toolkit for robust and high-rate MSAs. In this work, CSense provide a simple language for developers to describe their sensing flow without the need to deal with system intricacy, such as memory allocation, concurrency control and power management. The results show up to 19X performance difference may be achieved automatically compared with a baseline using the default runtime concurrency and memory management. Following this direction, we saw the opportunities that MSAs can be significantly improved from the perspective of memory performance and energy efficiency in view of the iterative execution. Therefore, we next focus on optimizing the runtime memory management through compile time analysis. The contribution is a stream compiler that captures the whole program memory behavior to generate an efficient memory layout for runtime access. Experiments show that our memory optimizations reduce memory footprint by as much as 96% while matching or improving the performance of the StreamIt compiler with cache optimizations enabled. On the other hand, while there is a significant body of work that has focused on optimizing the throughput or latency of processing sensor streams, little to no attention has been given to energy efficiency. We proposed an accurate offline energy prediction model for MSAs that leverages the pipeline structure and iterative execution nature to search for the most energy saving batching configuration w.r.t. a deadline constraint. The developers are expected to visualize the energy delay trade-off in the parameter space without runtime profiling. The evaluation shows the worst-case prediction errors are about 7% and 15% for energy and latency respectively despite variable application workloads.

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Tattersfield, Lisa Joanne. "Effects of copper on the energy budget of a stream detrivore : validation and ecological relevance." Thesis, University of Sheffield, 1993. http://etheses.whiterose.ac.uk/10259/.

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It is undisputed that single species toxicity tests are essential for obtaining information on concentrations and durations of exposures to chemicals that result in changes in survival, reproduction, physiology, biochemistry and the behaviour of individuals within a particular species (Caims, 1983). However, the extent to which single species toxicity tests can be used to predict effects in the natural environment and changes at higher levels of biological organization are largely unknown (Kooijman, 1985). The ultimate aim of laboratory tests is to predict the potential effects of toxicants in natural systems in order to protect the structure and functioning of the ecosystem. Hence, the aim of this study was to investigate the validity (i. e. the extent to which effects observed in the laboratory are mirrored in a more natural environment) and ecological relevance (i. e. the extent to which the tests are indicative of effects at higher levels of organisation which are important for the structure and / or functioning of the ecosystem) of a particular single species laboratory test. In order to increase its potential ecological relevance, both test species and response criteria for the laboratory test were carefully selected. The effects of copper, a reference toxicant, on energy budget parameters of Gammarus pulex, an important stream detritivore, were investigated. The validity and ecological relevance of these energy budget tests, under more natural conditions, were investigated with the use of outdoor artificial streams. In the laboratory tests, consumption rates were identified as the most sensitive energy budget parameter to copper-induced stress in G. pule-x. This decrease in consumption rates was due to an increase in the body copper concentration of G. pulex via copper uptake from the media, rather than to a rejection of copper contaminated food. As well as being the most sensitive parameter to copper stress in laboratory tests, consumption rates were identified as the most sensitive energy budget parameter measured in animals deployed in the artificial streams. Further, there was no statistically significant difference between the effects of copper on consumption rates of animals in laboratory tests and in the artificial streams. Therefore tests based on consumption rates as a response criterion were valid in more natural systems. Potential additional effects on the consumption rates of G. pulex due to copper-induced reductions in food quality were also indicated. The ecological relevance of these tests was investigated by trying to predict higher level effects in terms of growth and reproduction of whole organisms in the laboratory and in terms of the structure and functioning of populations and communities in artificial streams. Predictions regarding effects of copper on growth and reproduction of whole organisms were fairly accurate in indicating trends but were unsuccessful in predicting actual growth rates and reproductive output. Population density and leaf processing were selected as response criteria indicative of effects of copper on the structure and function of the freshwater ecosystem respectively. Effects on these two parameters were observed at the same concentration as adverse effects on consumption rates, and no adverse effects were detected at concentrations below those causing a decrease in consumption rates. Potential consequences, of the observed effects of copper on G. pulax, for the structure and functioning of the freshwater community are discussed. iii It is concluded that by careful selection of ecologically meaningful response criteria and test species, laboratory tests based on individuals can be representative of potential impact of a toxicant at higher levels of organisation in the natural environment. Consumption rates in G. pulex represent a sensitive, valid and ecologically relevant response criterion for the determination of the effects of a pollutant in natural ecosystems.

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Dissertations / Theses on the topic 'Energy streams'

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