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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Hidroenergetikos darnaus vystimosi kriterijų analizė / Criteria of Hydropower Sustainable Development Analysis

Kasiulis, Egidijus 15 June 2010 (has links)
2003 m rugsėjo 11 d. Lietuvos Respublikos vyriausybė patvirtino „Nacionalinę darnaus vystymosi strategiją“, kurioje įsipareigojo teikti paramą atsinaujinantiems energijos šaltiniams, tarp jų ir hidroenergetikai. Žymaus elektros gamybos padidinimo iš atsinaujinančių energijos šaltinių siekia ir ES, priėmusi Elektros, pagamintos iš atsinaujinančių energijos šaltinių, skatinimo direktyvą (Directive on the promotion of the Use of Energy from Renewable Sourses; RES, 2009/28/EB). Tačiau Bendrosios vandens politikos direktyvos (Water Framework Directive; WFD, 2000/60/EC) vykdymas reikalauja pasiekti gerą būklę visuose vandens telkiniuose 2015 metais, o tai tampa kliūtis naujų hidroelektrinių statymui bei visos hidroenergetikos vystimuisi. Geriausia galima išeitis – hidroelektrinių sertifikavimas. Hidrojėgainės, kurios atitiktų aplinkosauginius reikalavimus, gautų žaliosios elektros energijos žymą. Šis darbas skirtas įvertinti užsienyje esamų žaliųjų sertifikavimo sistemų pritaikomumą Lietuvos sąlygomis. / In September 2003 Lithuanian Government approved the “National Sustainable Development Strategy“ in which committed to provide support for alternative energy sources, including hydropower. Approving Directive on the promotion of the Use of Energy from Renewable Sources, EU is seeking significant increase in electricity produced from renewable sources. However Water Framework Directive requires achieving good status in all water bodies in 2015. This is an obstacle to constructions of new hydroelectric power plants ant to whole hydropower development. Hydropower certification is the best possible solution. Hydropower plants, that will meet environmental requirements, will receive green label. This work is intending to evaluate adaptability of existing foreign green certification systems in Lithuanian conditions.
112

An investigation of river kinetic turbines: performance enhancements, turbine modelling techniques, and an assessment of turbulence models

Gaden, David L. F. 27 September 2007 (has links)
The research focus of this thesis is on modelling techniques for river kinetic turbines, to develop predictive numerical tools to further the design of this emerging hydro technology. The performance benefits of enclosing the turbine in a shroud are quantified numerically and an optimized shroud design is developed. The optimum performing model is then used to study river kinetic turbines, including different anchoring systems to enhance performance. Two different turbine numerical models are studied to simulate the rotor. Four different computational fluid dynamics (CFD) turbulence models are compared against a series of particle image velocimetry (PIV) experiments involving highly-separated diffuser-flow and nozzle-flow conditions. The risk of cavitation is briefly discussed as well as riverbed boundary layer losses. This study is part of an effort to develop this emerging technology for distributed power generation in provinces like Manitoba that have a river system well adapted for this technology.
113

Fotogrammetrisk analys av kornstorleksfördelningeni erosionsskydd vid kraftverksdammar / Photogrammetric analysis of the grain size distributionof erosion protection at hydropower dams

Bäcklund, Annika January 2014 (has links)
This master thesis was made to investigate the possibilities of using the Matlab-basedsoftware Basegrain to determine grain size distributions of erosion protections onhydropower dams. Basegrain is a photogrammetric tool developed to generate grainsize distributions and other information about coarse flood sediments by analyzing adigital photo of the stone bed. The investigation was made by validating the ability forBasegrain to assess grain size distributions of various materials smaller than the blocksused in an erosion protection by comparing sieving results or manual measurementswith the results obtained by the program. A statistical comparison was then made bycomparing the results from sieving and the program. The possibilities of using thesame method on existing hydropower dams were then investigated by determiningwhether the method was practically viable or not.The results showed that Basegrain generated grain size distributions for coarse gravelthat were very close to the sieving results. It also provided grain size distributions forlarger fractions of stones quite close to the results made by measuring the diameterof the stones by hand. The results also showed it was possible to use the samemethod on existing erosion protections on hydropower dams and obtain grain sizedistributions.
114

Mobilization of metals from mining wastes and the resuspension of contaminated sediments

Thuy Nguyen, Lan January 2008 (has links)
In some environmental situations, environmental effects caused by elevated metals resulting from past mining and smelting activities can be observed in nearby receiving water bodies several decades after mine and smelter closure. There is a growing need for managing the hazardous solid wastes such as mining wastes as well as for assessing water quality and for sustainable management of sediment quality. The work presented in this thesis examined the mobilization of metals from two metal sources: mining wastes from a mine site in Vietnam and sediments from a contaminated lake in Sweden in order to test the hypothesis that mobilization of metals will be increased, when the environmental conditions change by e.g. exposure of mining wastes to oxidative weathering, change of redox conditions at the water-sediment interface and resuspension of sediments. The results from this work under field and laboratory conditions have verified the hypothesis. The exposure of sulphidic mining wastes in oxidative weathering conditions may cause long-term production of ARD and the resultant long-term mobility of metals. The oxidation/resuspension of sediments is an important factor for the release of trace metals Zn, Cu and Cd into the solution and substantial amounts of particles and, hence, associated metals into overlying water. The concomitant changes in pH during oxidation/resuspension of sediment play a significant role in the metal release both to redox sensitive elements Fe and Mn and trace elements Zn, Cu and Cd. The concomitant change in DOC during oxidation/resuspension can also contribute to the increased mobility of study metals. The field study was coupled to intermittent operation of a hydropower plant. The mobility of the metals was higher under operation compared to non-operation and, thus, the potential impacts on dispersal of metal pollution to downstream aquatic environments. The sudden increase in water flow upon the hydropower plant upon shifts from inactive to active state could cause immediate release of particles and thus particulate metals in the overlying water. However, the magnitude and its integrated effects in fluxes of metals over the season call for further research. There is a need to further investigate the impacts of hydropower generation in a longer period of time and at a higher frequency of observations at the very start of the hydropower operation. The results from this multidisciplinary approach would give a basis for an optimal operation of the hydropower plant to minimize the metal pollution associated with the water flow. / <p>The series number is changed from 410 to 430 and the ISBN is changed from 978-91-85895-56-4 to 978-91-7393-926-3.</p>
115

Expanding operation ranges using active flow control in Francis turbines / Lastområdesutvidgning med aktiv flödeskontroll i Francisturbiner

Adolfsson, Sebastian January 2014 (has links)
This report contains an investigation of fluid injection techniques used in the purpose of reducing deleterious flow effects occurring in the draft tube of Francis turbines when operating outside nominal load. There is a focus on implement ability at Jämtkrafts hydroelectric power plants and two power plants were investigated, located in series with each other named Lövhöjden and Ålviken. The only profitable scenario found with some degree of certainty was an increase in the operating range upwards to allow overload operation. Findings show that both air and water can be introduced in various locations to improve hydraulic efficiency around the turbine parts as well as reduce pressure pulsations in harmful operating regions. Investments in such systems have proven useful and profitable at several facilities with poorly adapted operating conditions. But due to losses in efficiency when operating injection systems, it turns out unprofitable in situations where it does not improve the operating range in a way that is resulting in increased annual or peak production.
116

An investigation of river kinetic turbines: performance enhancements, turbine modelling techniques, and an assessment of turbulence models

Gaden, David L. F. 27 September 2007 (has links)
The research focus of this thesis is on modelling techniques for river kinetic turbines, to develop predictive numerical tools to further the design of this emerging hydro technology. The performance benefits of enclosing the turbine in a shroud are quantified numerically and an optimized shroud design is developed. The optimum performing model is then used to study river kinetic turbines, including different anchoring systems to enhance performance. Two different turbine numerical models are studied to simulate the rotor. Four different computational fluid dynamics (CFD) turbulence models are compared against a series of particle image velocimetry (PIV) experiments involving highly-separated diffuser-flow and nozzle-flow conditions. The risk of cavitation is briefly discussed as well as riverbed boundary layer losses. This study is part of an effort to develop this emerging technology for distributed power generation in provinces like Manitoba that have a river system well adapted for this technology.
117

Detection of Frazil Ice at Water Intakes at Träbena Power Station

Carrera Artola, Iosu, Lucena Garcerán, Alejandro January 2014 (has links)
Frazil ice is a phenomenon that takes place in cold regions when the water of rivers, lakes or oceans is cooled under 0ºC. Several times during winter, frazil ice can appear at river Ätran, where Träbena hydropower plant is held by the company Wetterstad Consulting AB. Frazil ice particles contained in the flowing water are extremely sticky and adhere to any object placed in the water. Trash racks are used by the power plant at the water intakes to prevent any strange object to go into the turbines. However, frazil ice particles stick to the trash racks creating an ice blockage that interrupts the water inflow. In this situation, the power plant has to stop the production even for several months, due to the lack of water that reaches the turbines. In order to solve this problem, the company has installed a heating system on the trash racks that prevent the adhesion of frazil ice particles. This system is manually operated, and it is turned on or off based on the experience and predictions of the company. This heating system is very power consuming and every time it is turned on unnecessarily the company loses money. An automatic frazil ice detection system that turns on the heating system when needed is to be created. For that, several options have been analysed, and finally a capacitor-based sensor has been developed as a solution. The sensor consist of two steel plates coated with semi-transparent polycarbonate submerged underwater parallel placed in the space between the trash racks’ bars, forming this way a parallel plate capacitor. The capacitance of a capacitor depends exclusively on its geometry and the dielectric material between the plates. Hence when the water temperature is low enough, frazil ice particles stick to the plates of the capacitor and its capacitance will vary indicating that the accretion of frazil ice may block the water inflow. This variation is registered and a signal is send to the heating system to start operating. This way, the heating system is completely automated; no human intervention is needed at all. / <p>Developed for Wettestad Consulting AB.</p>
118

Fuelling insecurity?: Sino-Myanmar energy cooperation and human security in Myanmar.

Botel, Gabriel 11 July 2012 (has links)
This thesis examines the relationship between energy, development and human security in Sino-Myanmar relations. Rapid economic growth and increased urbanisation have intensified China’s industrial and domestic energy consumption, drastically increasing demand and overwhelming national supply capacities. Chinese foreign policy has responded by becoming more active in securing and protecting foreign energy resources and allowing Chinese companies more freedom and opportunities for investment abroad. Consequently, Chinese foreign investment and policies have become increasing sources of scrutiny and debate, typically focusing on their (presumed) intentions and the social, economic, environmental and political impacts they have on the rest of the world. Within this debate, a key issue has been China’s engagement with so-called pariah states. China has frequently received substantial international criticism for its unconditional engagement with such countries, often seen as a geopolitical pursuit of strategic national (energy) interests, unconcerned with international opprobrium. In the case of Myanmar, traditional security analyses interpret this as, at best, undermining (Western) international norms and, at worst, posing a direct challenge to international security. However, traditional security analyses rely on state-centric concepts of security, and tend to over-simply Sino-Myanmar relations and the dynamics which inform it. Conversely, implications for human security are overlooked; this is in part because human security remains poorly defined and also because there are questions regarding its utility. However, human security is a critical tool in delineating between state, corporate and ‘civilian’ interests, and how these cleavages shape the security environment and potential for instability in the region. iv This thesis takes a closer look at some of the entrenched and changing security dynamics shaping this Sino-Myanmar energy cooperation, drawing on an extensive literature in human security rarely applied in this context. This includes a brief review of human security and Sino-Myanmar relations, and is grounded in an empirical analysis of Chinese investment in Myanmar’s hydropower and oil and gas sectors. Ultimately, this thesis argues that, while insightful, many traditional interpretations of Sino-Myanmar energy cooperation overlook the security interests of those worst affected. Furthermore, that the worst excesses of Chinese companies in Myanmar are not unique to China, but common across all investors in the regime, Western or otherwise. / Graduate
119

Ilisu Dam And Hepp, Investigation Of Alternative Solutions

Yalcin, Emrah 01 October 2010 (has links) (PDF)
This study is an assessment of a hydraulic solution not only rescues Hasankeyf with countless ancient monuments from inundation but also supplies the foreseen energy production of the Ilisu Dam and HEPP Project. An alternative composed of five dams on the Tigris River and its branches was developed as a result of the conducted hydro-meteorological, water potential, flood analysis and optimization studies considering the topographical and geological characteristics of the proposed dam locations. While there is a 27 percent decrease in the overall reservoir area compared to the existing project, 4426.1 hm3 of water can be stored in these dams with a fill volume of 14.8 hm3. Over this storage, determined according to the maximum water levels designated by considering the upstream schemes developed by General Directorate of State Hydraulic Works (DSI), General Directorate of Electrical Power Resources Survey and Development Administration (EIE) and incorporated companies according to Law No.4628, a volume of 3634.4 hm3 can be used as active storage. In the fully developed upstream stage, according to the conducted consecutive operation studies, while the existing project has an energy production capacity of 3094.3 GWh/year, the proposed project is capable of providing 3139.1 GWh/year with a smaller installed power although there is a slight decrease in the produced firm energy.
120

Evaluating ecologically-inspired displays for complex systems: Hydropower system case study

Ms Xi Li Unknown Date (has links)
The purpose of this thesis is to explore the theoretical and practical issues associated with the design, execution and analysis of an empirical evaluation of novel process control displays in a collaborative control room environment. An important feature of the thesis is how practical constraints associated with limited access to industry controllers were handled and how convergent lines of evidence were used to achieve the evaluation. As a novel research domain, hydropower systems (HPS) present many design challenges, because controllers must coordinate multiple domains across different time frames. If controllers are to maintain effective situation awareness and if they are to exercise effective control, the displays must integrate controllers’ problem solving across water, generation, market, and transmission concerns and across time frames. However, these needs are ignored in the current displays in a hydropower control room. The two new ecologically-inspired displays, called “Functional Displays”, evaluated in this thesis, are intended to overcome the above shortcomings. The evaluation was done with industry hydropower controllers and coordinators on a medium fidelity simulator which represented the working environment of a large hydropower control room. The core issue of this thesis is how the evaluation was conceptualized, operationalized and analysed given practical constraints arising from limited access to industry controllers, limited capacity of the simulator, and the complexity of the hydropower domain. Of key concern was the design of test scenarios, selection of measures of performance, and data analysis in the face of these constraints. The rationale of the scenario design was to combine representative contingencies within and outside the hydropower scheme, emergent storage problems and different market contexts so that controllers or coordinators would be required to act in different domains. Only by placing controllers in such challenging and time pressured situations could we maximize our chances of seeing the expected benefits of the new display, given the limited length of the experiment. Multiple measures were proposed to capture the quality of in-the-loop coupling between human controllers and the system under various disturbances. The measures of performance include: (1) control quality, which investigates how the new displays tame “temporal complexity” by helping the control team construct a more effective pattern of activities to handle contingencies; and (2) control strategy, which exposes how the new display support the coordination between storage, generation and market to meet the strategic or tangible objectives. The measures of cognition and affect include: (1) situation awareness (SA), which represents controllers’ or coordinators’ degree of cognitive coupling with different time frames and different levels of the hydropower scheme and (2) controllers’ or coordinators’ trust in the supporting displays, and their self-confidence in their own ability to control the hydropower scheme. Through the effort of triangulating the different measures, balancing the elements in designing scenarios, and extracting and integrating raw data from the study, convergent lines of evidence were achieved for evaluation. It was found that the new Functional Displays led the participant teams to a better pattern of work which was reflected in their situation awareness, their discretionary control activity, and the outcome of their control with respect to system productivity and stability. However, limitations of these findings because of the constraints of the experiment are discussed. This research contributes to many theoretical and practical issues in Human-System Interface (HSI). For example, it outlines how some of the principles of ecological interface design (EID) can be used and it highlights the value of using time as a basis for distinguishing interfaces. Moreover, this research provides fruitful insights into the selection and development of measures to assess human control in real world complex work environments. Because a key issue of this thesis is how practical constraints were handled; pragmatic approaches for measuring SA and control were developed. Because industry often performs evaluations under similar intensive constraints, the approaches and solutions developed in this thesis for evaluating novel interfaces could be easily adapted to various industrial settings.

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