• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 55
  • 28
  • 9
  • 5
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 159
  • 159
  • 39
  • 37
  • 30
  • 26
  • 24
  • 22
  • 19
  • 18
  • 14
  • 14
  • 13
  • 12
  • 12
  • 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.
81

Demand response of domestic consumers to dynamic electricity pricing in low-carbon power systems

McKenna, Eoghan January 2013 (has links)
The ability for domestic consumers to provide demand response to dynamic electricity pricing will become increasingly valuable for integrating the high penetrations of renewables that are expected to be connected to electricity networks in the future. The aim of this thesis is to investigate whether domestic consumers will be willing and able to provide demand response in such low-carbon futures. A broad approach is presented in this thesis, with research contributions on subjects including data privacy, behavioural economics, and battery modelling. The principle argument of the thesis is that studying the behaviour of consumers with grid-connected photovoltaic ('PV') systems can provide insight into how consumers might respond to dynamic pricing in future low-carbon power systems, as both experience irregular electricity prices that are correlated with intermittent renewable generation. Through a combination of statistical and qualitative methods, this thesis investigates the demand response behaviour of consumers with PV systems in the UK. The results demonstrate that these consumers exhibit demand response behaviour by increasing demand during the day and decreasing demand during the evening. Furthermore, this effect is more pronounced on days with higher irradiance. The results are novel in three ways. First, they provide quantified evidence that suggests that domestic consumers with PV systems engage in demand response behaviour. Second, they provide evidence of domestic consumers responding to irregular electricity prices that are correlated with intermittent renewable generation, thereby addressing the aim of this thesis, and supporting the assumption that consumers can be expected to respond to dynamic pricing in future markets with high penetrations of renewables. Third, they provide evidence of domestic consumers responding to dynamic pricing that is similar to real-time pricing, while prior evidence of this is rare and confined to the USA.
82

Quantifying the Transition to Low-carbon Cities

Mohareb, Eugene 30 August 2012 (has links)
Global cities have recognized the need to reduce greenhouse gas (GHG) emissions and have begun to take action to balance of the carbon cycle. This thesis examines the nuances of quantification methods used and the implications of current policy for long-term emissions. Emissions from waste management, though relatively small when compared with building and transportation sectors, are the largest source of emissions directly controlled by municipal government. It is important that municipalities understand the implications of methodological selection when quantifying GHG emissions from waste management practices. The “Waste-in-Place” methodology is presented as the most relevant for inventorying purposes, while the “Methane Commitment” approach is best used for planning. Carbon sinks, divided into “Direct” and “Embodied”, are quantified using the Greater Toronto Area (GTA) as a case study. “Direct” sinks, those whose sequestration processes occur within urban boundaries, contribute the largest share of carbon sinks with regional forests providing a significant proportion. “Embodied” sinks, those whose sequestration processes (or in the case of concrete, the processes that enable sequestration) are independent of the urban boundary, can contribute to the urban carbon pool, but greater uncertainty exists in upstream emissions as the management/processing prior to its use as a sink are generally beyond the consumer’s purview. The Pathways to Urban Reductions in Greenhouse gas Emissions (or PURGE) model is developed as a means to explore emissions scenarios resulting from urban policy to mitigate climate change by quantifying future carbon sources/sinks (from changes in building stock, vehicle stock, waste treatment and urban/regional forests). The model suggests that current policy decisions in the GTA provide short-term reductions but are not sufficient in the long term to balance the pressures of economic and population growth. Aggressive reductions in energy demand from personal transportation and existing building stock will be necessary to achieve long-term emissions targets.
83

Quantifying the Transition to Low-carbon Cities

Mohareb, Eugene 30 August 2012 (has links)
Global cities have recognized the need to reduce greenhouse gas (GHG) emissions and have begun to take action to balance of the carbon cycle. This thesis examines the nuances of quantification methods used and the implications of current policy for long-term emissions. Emissions from waste management, though relatively small when compared with building and transportation sectors, are the largest source of emissions directly controlled by municipal government. It is important that municipalities understand the implications of methodological selection when quantifying GHG emissions from waste management practices. The “Waste-in-Place” methodology is presented as the most relevant for inventorying purposes, while the “Methane Commitment” approach is best used for planning. Carbon sinks, divided into “Direct” and “Embodied”, are quantified using the Greater Toronto Area (GTA) as a case study. “Direct” sinks, those whose sequestration processes occur within urban boundaries, contribute the largest share of carbon sinks with regional forests providing a significant proportion. “Embodied” sinks, those whose sequestration processes (or in the case of concrete, the processes that enable sequestration) are independent of the urban boundary, can contribute to the urban carbon pool, but greater uncertainty exists in upstream emissions as the management/processing prior to its use as a sink are generally beyond the consumer’s purview. The Pathways to Urban Reductions in Greenhouse gas Emissions (or PURGE) model is developed as a means to explore emissions scenarios resulting from urban policy to mitigate climate change by quantifying future carbon sources/sinks (from changes in building stock, vehicle stock, waste treatment and urban/regional forests). The model suggests that current policy decisions in the GTA provide short-term reductions but are not sufficient in the long term to balance the pressures of economic and population growth. Aggressive reductions in energy demand from personal transportation and existing building stock will be necessary to achieve long-term emissions targets.
84

Analysis Of Warm Forging Process

Aktakka, Gulgun 01 January 2006 (has links) (PDF)
Forging is a metal forming process commonly used in industry. Forging process is strongly affected by the process temperature. In hot forging process, a wide range of materials can be used and even complex geometries can be formed. However in cold forging, only low carbon steels as ferrous material with simple geometries can be forged and high capacity forging machinery is required. Warm forging compromise the advantages and disadvantages of hot and cold forging processes. In warm forging process, a product having better tolerances can be produced compared to hot forging process and a large range of materials can be forged compared to cold forging process. In this study, forging of a particular part which is being produced by hot forging at 1200&deg / C for automotive industry and have been made of 1020 carbon steel, is analyzed by the finite volume analysis software for a temperature range of 850-1200&deg / C. Experimental study has been conducted for the same temperature range in a forging company. A good agreement for the results has been observed.
85

The emergence of low carbon development in China and India : energy efficiency as a lens

Ma, Yuge January 2015 (has links)
Low-carbon development (LCD) in China and India is crucial to global sustainability. As representatives of the emerging world, China and India have to tackle the LCD challenge at the same time as they address rapid urbanization, industrialization and globalization, making this process an unprecedented problem in policy and practice. My dissertation uses a comparative perspective to examine the unique institutional change processes of China and India's LCD during the period of late 1970s to the present day - through the lens of energy efficiency (EE). I argue that despite the manifold differences in political, economic and social contexts in contemporary China and India, the process of institutional development and change in EE reveals some similar mechanisms. I investigate the common mechanisms through a five-phase framework, and find: First, in both countries, EE was initially triggered by complicated interactions between international and domestic crises. Second, through processes of political negotiation led by various policy groups, EE was conceived and planned by each state to embody not one single objective but multiple political, economic and social development goals. Third, in order to realize EE, an organizational complex formed within an existing governance structure. Fourth, detailed policy processes (which both shape and are shaped by their institutional settings) emerged from the previous stages. Finally, EE institutions are stabilized jointly through legalization and the establishment of specialist technical subfields. I argue that the key mechanism of the five-phase process of institutional change is the bundling structure between EE organizations and the host governance structure. While in China the latter is the structure of economic governance, in India it is that of energy governance. These bundling structures imprinted multiple path-dependencies from the host governance structure to the newly developed EE regime, which in turn determine the long-term impact of EE on LCD in China and India. My original contributions are threefold. First, this project is one of the first scholarly attempts to systematically make sense of LCD in large and complex countries with fast economic growth by using the perspective of institutional change. Second, drawing on broad theoretical resources and through an interdisciplinary exploration, the thesis tries to construct a cause-effect, systemic, and political-economic theory of LCD in contemporary China and India. Finally, my comparative framework adds a systemic and nuanced methodological viewpoint to the emerging field of multidisciplinary China-India comparative scholarship.
86

Considerações sobre o atrito para processos de forjamento a frio através do ensaio de compressão do anel

Geier, Martin January 2007 (has links)
São realizadas análises teóricas e experimentais do atrito nos processos de forjamento a frio, através do ensaio de compressão do anel. Os modelos de atrito de Amonton-Coulomb (μ), atrito interfacial (m) e de Levanov (f) são investigados com auxílio de softwares comerciais de simulação de processos de forjamento. Diferentes condições de lubrificação foram aplicadas para o aço baixa liga 16MnCr5 e a liga de alumínio AA6351 nas condições recozido e encruado. O atrito foi analisado, utilizando os softwares MSC.Superforge e Qform, em função dos resultados obtidos e as condições de lubrificação e estado do material. Valores paramétricos do atrito adquiridos através de correlação teórico-experimental são condizentes com a literatura, indicando a relação do atrito com o material de trabalho, inclusive com seu grau de encruamento. Os modelos de atrito m e f apresentaram maior sensibilidade com relação ao estado do material. / Experimental and theoretical analyses of friction in cold forging process are evaluated by means of the ring compression test. Friction models from Amonton- Coulomb (μ), interfacial friction (m) and Levanov’s model (f) are investigated by aid of numerical simulation software. Different lubricants are applied for low carbon steel alloy 16MnCr5 under annealed and work-hardened conditions. Friction is analyzed by means of lubricant and material conditions using MSC.Superforge and Qform numerical simulation softwares. Acquired frictional parameter values obtained by theoretical-experimental correlation agree with literature, showing friction’s relationship with workpiece material and its hardening level. Friction models m and f presented better sensitivity when concerning the material’s hardening level.
87

Klimatsmart livsstil : Hur människor kan påverkas till att leva mer klimatsmart

Sandberg, Linnéa January 2018 (has links)
One of the greatest challenges of our time is the ongoing climate change. Research suggests that it is us humans that through our greenhouse gas emissions are the greatest cause of globalwarming and the problems that comes with it. To reduce the emissions of greenhouse gas and meet the international goals, it is necessary for individuals to make changes in their behavior. Some people care a lot about the climate and tries to do everything in their power to lower theirown impact, others want to do something but do not know what and some people does not care at all. The purpose of this study is to provide a deeper understanding of how to influence people to live in a more environmentally friendly way by identifying factors that determines environmentally friendly actions both positively and negatively. The study was conducted through a qualitative case study where the data collection was made through personal interviews with citizens in Luleå. The results of the study show that knowledge has a strong connection to individual behaviors. It is important to know that the environmental actions you take is of importance. Many people have the desire to do more than they do but are hindered by contextual factors like saving time. Except for the factors that was identified in the frame of reference the study also shows that there are other reasons for individuals to act in an environmentally friendly way: health, economy, ethics, frugality and care about future generations. By identifying these factors and get an explanation of how they impact individuals, the study can aid decision makers of a county with information that helps them adapt their conversion work to the citizens. The recommendations for counties are to provide citizens with clear information both regarding what goals they aim to reach as well as concrete actions to take in order to fulfil these, make it easier to choose environmentally friendly options, market the environmental benefits but also other reasons for certain behaviors since many people are more motivated byother things than environmental reasons, share their results in their environmental work to include citizens as well as spread motivation for further behavior changes. / En av vår tids största utmaningar är de pågående klimatförändringarna. Forskning visar att det till allra största del är vi människor som genom våra utsläpp av växthusgaser är ansvariga för den globala uppvärmningen och de problem som den för med sig. För att reducera utsläppen av växthusgaser och uppnå de internationella utsläppsmålen krävs delvis insatser på individnivå. Vissa människor bryr sig mycket om klimatet och försöker göra allt i sin makt för att minska sin egen klimatpåverkan, andra vill göra något men vet inte vad och vissa bryr sig inte alls. Denna studie syftar till att ge en djupare förståelse för hur man kan påverka människor att leva mer klimatsmart genom att identifiera faktorer som påverkar miljövänliga beteenden i både positiv och negativ riktning. Studien genomfördes genom en kvalitativ fallstudie där datainsamlingen gjordes genom personliga intervjuer med invånare i Luleå kommun. Studiens resultat visar att kunskap har en stark koppling till en individs beteenden. Det är viktigt att de insatser man gör till förmån för klimatet känns betydelsefulla. Många har en vilja att göra mer för klimatet men hindras av kontextuella faktorer, till största del handlar det om tidsaspekten. Förutom de faktorer som identifierades i det teoretiska ramverket framkom även ytterligare orsaker till varför individer beter sig miljövänligt: hälsa, ekonomi, etik, sparsamhet samt att värna om framtida generationer. Genom att identifiera dessa faktorer samt få förklarat hur de påverkar individen kan studien bidra med information till beslutsfattare exempelvis inom kommuner för att de ska kunna anpassa sitt omställningsarbete till medborgarna i kommunen. Studiens rekommendationer för kommuner är att de bör bistå med tydlig information till invånarna, både när det gäller vilka mål de siktar till att uppnå samt vad som konkret krävs för att uppfylla dessa. Kommunen bör också göra det lättare att välja miljövänliga alternativ, marknadsföra såväl klimatnyttan men även andra skäl till ett visst beteende eftersom att många motiveras mer av andra fördelar än klimatnytta. Samt dela med sig av resultat i klimatarbetet för att göra medborgarna delaktiga samt sprida motivation att arbeta vidare.
88

Optimal diversification and the transition to net zero : a methodological framework for measuring climate goal alignment of investor portfolios / Diversification optimale et la transition au zéro net : un cadre méthodologique pour mesurer l'alignement des portefeuilles des investisseurs avec les objectifs climatiques

Thomä, Jakob 02 July 2018 (has links)
La thèse vise à développer un cadre pour mesurer l'alignement des portefeuilles financiers avec les objectifs climatiques, prenant comme point de départ à la fois la théorie traditionnelle du portefeuille moderne et les cadres d'analyse des risques financiers, ainsi que la science du climat. Il s'agit de la première tentative d'élaboration de points de repère scientifiques pour le portefeuille financier. Le cadre utilise comme point de départ le concept de «diversification optimale» basé sur la théorie moderne du portefeuille et l'hypothèse de marché efficace. Selon cette théorie, les stratégies optimales impliquent l'achat du «portefeuille de marché». Il postule que cette stratégie ne peut toutefois pas être alignée sur une stratégie de portefeuille alignée avec un scenario 2 ° C. Une telle stratégie de portefeuille basée sur la science peut toutefois avoir un sens pour les institutions financières qui considèrent des objectifs multiples (financiers et non financiers) ou des institutions financières qui pensent que les marchés évaluent mal les risques financiers associés à la transition vers une économie 2°C. Les stratégies associées à 2°C peuvent surperformer le marché. Sous l'hypothèse que la transition vers une économie bas-carbone présente un facteur de risque, pour lequel la thèse fournit une série de preuves théoriques, les stratégies de portefeuille peuvent chercher à acheter le «marché à 2 ° C» en cherchant et gérant une «diversification optimale». Le modèle étend ainsi la logique de la diversification pour réduire le risque, inhérent à la théorie moderne du portefeuille, de la classe d'actifs au niveau sectoriel et technologique. Après le développement du modèle, le modèle a été testé par une série de compagnies d'assurance, de gestionnaires d'actifs et de gestionnaires de portefeuille. Au total, plus de 250 investisseurs institutionnels ont appliqué le modèle au moment de la publication. En outre, le modèle a été testé sur environ 10000 fonds. De plus, deux banques centrales européennes ont appliqué le modèle en interne dans le cadre d'une analyse de scénario à 2 ° C de leurs entités réglementées (fonds de pension et compagnies d'assurance). Dans le cadre d'un sondage auprès de 25 investisseurs, 88% ont déclaré que le cadre était tout aussi pertinent ou plus pertinent que les évaluations climatiques existantes, et 88% ont indiqué qu'ils étaient susceptibles ou très susceptibles d'utiliser la méthodologie pour aller de l'avant. / The thesis seeks to develop a framework to measure the alignment of financial portfolios with climate goals, taking as point of departure both traditional modern portfolio theory and financial risk analysis frameworks, as well as climate science. It represents the first attempt to develop science-based benchmarks for financial portfolios. The framework uses as the starting point the concept of ‘optimal diversification’ based on the modern portfolio theory and efficient market hypothesis. Under this theory, optimal strategies involve buying the ‘market portfolio’. It posits that a 2°C aligned, science-based portfolio strategy is not aligned with such a strategy. Such a science-based portfolio strategy, in turn, may make sense for financial institutions that consider multiple objectives (e.g. financial and non-financial) or financial institutions that think markets are mispricing financial risks associated with the transition to a low-carbon economy and that associated low-carbon, or 2°C aligned strategies can outperform the market. Under the assumption that the transition to a low-carbon economy presents a risk factor, for which the thesis provides a range of theoretical evidence, portfolio strategies can seek to buy the ‘2°C market’ by managing ‘optimal diversification’ to the 2°C aligned technology set, in addition to managing sector exposures. The model thus extends the logic of diversification to reduce risk, intrinsic to the modern portfolio theory, from asset class to sector and technology level.Following the development of the model, a range of insurance companies, asset managers, and portfolio managers tested the model. In total, over 250 institutional investors have applied the model to date. In addition, the model has been tested on around 10,000 funds. Moreover, two European central banks have applied the model internally as part of 2°C scenario analysis of their regulated entities (pension funds and insurance companies). As part of a feedback survey with 25 investors, 88% said the framework was equally or more relevant than existing climate assessments, and 88% said they were likely or very likely to use the methodology moving forward.
89

Considerações sobre o atrito para processos de forjamento a frio através do ensaio de compressão do anel

Geier, Martin January 2007 (has links)
São realizadas análises teóricas e experimentais do atrito nos processos de forjamento a frio, através do ensaio de compressão do anel. Os modelos de atrito de Amonton-Coulomb (μ), atrito interfacial (m) e de Levanov (f) são investigados com auxílio de softwares comerciais de simulação de processos de forjamento. Diferentes condições de lubrificação foram aplicadas para o aço baixa liga 16MnCr5 e a liga de alumínio AA6351 nas condições recozido e encruado. O atrito foi analisado, utilizando os softwares MSC.Superforge e Qform, em função dos resultados obtidos e as condições de lubrificação e estado do material. Valores paramétricos do atrito adquiridos através de correlação teórico-experimental são condizentes com a literatura, indicando a relação do atrito com o material de trabalho, inclusive com seu grau de encruamento. Os modelos de atrito m e f apresentaram maior sensibilidade com relação ao estado do material. / Experimental and theoretical analyses of friction in cold forging process are evaluated by means of the ring compression test. Friction models from Amonton- Coulomb (μ), interfacial friction (m) and Levanov’s model (f) are investigated by aid of numerical simulation software. Different lubricants are applied for low carbon steel alloy 16MnCr5 under annealed and work-hardened conditions. Friction is analyzed by means of lubricant and material conditions using MSC.Superforge and Qform numerical simulation softwares. Acquired frictional parameter values obtained by theoretical-experimental correlation agree with literature, showing friction’s relationship with workpiece material and its hardening level. Friction models m and f presented better sensitivity when concerning the material’s hardening level.
90

Penser nos futurs modes de vie dans les démarches de prospective énergétique : proposition d’une approche par la modélisation / Investigating long-term lifestyle changes into energy foresight studies : a modelling approach

Le Gallic, Thomas 21 December 2017 (has links)
Le mode de vie des pays industrialisés, basé sur le consumérisme, est considéré comme l’un des principaux moteurs de l’usage de ressources et de la dégradation de l’environnement global. Sa substitution par d’autres modes de vie constitue l’une des clés pour bâtir un futur soutenable, d’autant qu’il tend à être imité dans les pays émergents et en développement. Pourtant, la question de la transition des modes de vie a été jusqu’à présent relativement peu investie par les politiques publiques, y compris par celles qui visent à répondre aux enjeux de la transition énergétique et de l’atténuation du changement climatique. C’est dans le but d’encourager les parties prenantes de ces enjeux à se saisir de cette question que nos recherches ont été initiées. Pour cela, nous avons choisi de nous concentrer sur la démarche prospective, qui est l’un des outils d’aide à la décision privilégiés pour éclairer les politiques de l’énergie et du changement climatique dont les enjeux portent sur les moyen et long termes. Nous avons constaté que la question était jusqu’à présent très partiellement abordée dans la plupart des exercices de prospective énergie-climat. Ce constat tient en partie au fait que, alors que la pratique actuelle accorde une place importante à la modélisation, le formalisme des modèles utilisés n’a bien souvent pas été pensé pour traiter de cette notion multidimensionnelle. Dans ce contexte, notre contribution porte sur les plans conceptuel et méthodologique. Nous avons dans un premier temps défini un cadre conceptuel pour aborder la notion de mode de vie et clarifier son rôle dans le système énergétique. Dans un second temps, nous avons proposé une approche par la modélisation destinée à simuler des scénarios d’évolution des modes de vie à l’échelle de la France. Cette approche formelle, dont le développement a constitué le cœur de nos recherches, permet de quantifier la demande en logements, la demande en mobilité et la demande en biens et services qui résultent de ces scénarios et définissent la structure des usages de l’énergie. La mise en œuvre de cette approche est illustrée dans ce manuscrit par la simulation de trois scénarios d’évolution des modes de vie. / Consumerist lifestyles in industrialized countries are considered one of the main drivers of global resource use and environment degradation. Changes in these lifestyles are therefore one of the keys to achieving a sustainable future, especially as these lifestyles also tend to be pursued by some economic classes in developing countries. Yet the lifestyles issue has only marginally been considered in public policies until now, including the ones that aimed to address the challenges of energy transition and climate change mitigation. Our research was initiated in order to encourage all parties engaging with these challenges to take into account our future lifestyles in this context. To this aim, we focused on the prospective approach. It is indeed one of the tools and processes that is most commonly used to support decision-makers on the long-term challenges raised by energy transition and tackling climate change. We found that most foresight studies did not go in depth while addressing the issue of lifestyles, especially the model-based studies. Indeed, the models generally used in these studies are not thought out to allow for proper consideration of this multidimensional issue. To answer for this, we propose a conceptual framework that allows proper understanding of the lifestyle concept and clarifies its role in the energy system. As a core contribution, we developed a modelling approach to simulate lifestyle-change scenarios for France. This formal approach allows us to quantify the demands for housing, mobility, goods and services that arises in these scenarios and defines the structure of energy uses. Three scenarios for lifestyle changes are considered in this manuscript to demonstrate implementations of the proposed approach.

Page generated in 0.0545 seconds