Дисертації з теми "Global peak"
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1
Sorrell, Steve. "Analysing controversies in energy policy : assessing the evidence for rebound effects and global oil depletion." Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/11544.
Повний текст джерелаАнотація:
This thesis is submitted as a PhD by Publication. Part A provides an overview of the thesis and summarises its context, research questions, methodological approach and key findings. Part B is a collection of nine, first-named academic papers. The thesis addresses two highly complex and controversial questions within energy policy, namely the nature and magnitude of ‘rebound effects’ from energy efficiency improvements and the extent and rate of depletion of global oil resources. Both of these questions are critically important to the development of a sustainable energy system and both are the subject of long-standing and highly polarised disputes. The thesis adapts, develops and applies a common methodology for reviewing the evidence on these questions, supplements this with original primary research and syntheses the results in a way that improves understanding and provides new insights. The thesis includes four papers examining different aspects of rebound effects and four examining different aspects of global oil depletion. Given the complexity of the chosen topics, the papers cover a wide range of questions, issues and approaches. Collectively the papers: clarify relevant definitional and conceptual issues; evaluate competing methodological and analytical techniques; appraise the methodological quality of empirical studies; identify levels of uncertainty and potential sources of bias; develop simple mathematical models; conduct statistical analyses of primary data; compare and evaluate the results of modelling studies; and synthesise results from multiple research areas to provide novel insights into poorly understood phenomena. A ninth paper evaluates the strengths and limitations of systematic review techniques when applied to complex, policy-relevant questions such as these. The thesis draws two main conclusions. First, rebound effects are frequently large and can substantially reduce the energy and carbon savings achieved from improved energy efficiency. Second, there is a significant risk that the global production of conventional oil will enter sustained decline before 2020. These conclusions run counter to conventional wisdom and have significant implications for public policy. The thesis also shows how the methodology of systematic reviews can be adapted and modified to make a valuable contribution to energy and climate policy research.
2
Oyeyemi, Elijah Oyedola. "A global ionospheric F2 region peak electron density model using neural networks and extended geophysically relevant inputs." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1005255.
Повний текст джерелаАнотація:
This thesis presents my research on the development of a neural network (NN) based global empirical model of the ionospheric F2 region peak electron density using extended geophysically relevant inputs. The main principle behind this approach has been to utilize parameters other than simple geographic co-ordinates, on which the F2 peak electron density is known to depend, and to exploit the technique of NNs, thereby establishing and modeling the non-linear dynamic processes (both in space and time)associated with the F2 region electron density on a global scale. Four different models have been developed in this work. These are the foF2 NN model, M(3000)F2 NN model, short-term forecasting foF2 NN, and a near-real time foF2 NN model. Data used in the training of the NNs were obtained from the worldwide ionosonde stations spanning the period 1964 to 1986 based on availability, which included all periods of calm and disturbed magnetic activity. Common input parameters used in the training of all 4 models are day number (day of the year, DN), Universal Time (UT), a 2 month running mean of the sunspot number (R2), a 2 day running mean of the 3-hour planetary magnetic index ap (A16), solar zenith angle (CHI), geographic latitude (q), magnetic dip angle (I), angle of magnetic declination (D), angle of meridian relative to subsolar point (M). For the short-term and near-real time foF2 models, additional input parameters related to recent past observations of foF2 itself were included in the training of the NNs. The results of the foF2 NN model and M(3000)F2 NN model presented in this work, which compare favourably with the IRI (International Reference Ionosphere) model successfully demonstrate the potential of NNs for spatial and temporal modeling of the ionospheric parameters foF2 and M(3000)F2 globally. The results obtained from the short-term foF2 NN model and nearreal time foF2 NN model reveal that, in addition to the temporal and spatial input variables, short-term forecasting of foF2 is much improved by including past observations of foF2 itself. Results obtained from the near-real time foF2 NN model also reveal that there exists a correlation between measured foF2 values at different locations across the globe. Again, comparisons of the foF2 NN model and M(3000)F2 NN model predictions with that of the IRI model predictions and observed values at some selected high latitude stations, suggest that the NN technique can successfully be employed to model the complex irregularities associated with the high latitude regions. Based on the results obtained in this research and the comparison made with the IRI model (URSI and CCIR coefficients), these results justify consideration of the NN technique for the prediction of global ionospheric parameters. I believe that, after consideration by the IRI community, these models will prove to be valuable to both the high frequency (HF) communication and worldwide ionospheric communities.
3
Thorbjörnsson, Anders. "Carbon Capture and Storage : Energy penalties and their impact on global coal consumption." Thesis, Uppsala universitet, Naturresurser och hållbar utveckling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235442.
Повний текст джерелаАнотація:
Coal has been used as a fuel for electricity generation for centuries. Inexpensive electricity from coal has been a key component in building large industrial economies such as USA and China. But in recent decades the negative aspects of coal, mainly carbon dioxide emissions, has changed the view on the fuel. Carbon capture and storage (CCS) is a solution to be able to continue using coal as an energy source, while limiting carbon emissions. One of the drawbacks of CCS is the energy need associated with the capture process, the energy penalty. This study aims to gather and analyze the energy penalties for the most developed types of carbon capture technologies. It also aims to model how the implementation of CCS would affect the future coal consumption. The results show that the range of energy penalties for a given type of technology is wide. Despite obtaining the energy penalty with the same simulation software, the energy penalty for post- combustion with MEA can range between 10.7% and 39.1%. Comparing mean energy penalties show that pre-combustion capture is the most efficient capture method (18.4% ± 4.4%) followed by oxy- fuel (21.6% ± 5.5%) and post-combustion (24.7% ± 7.9%). Further on, CCS implementation scenarios were compared and used as a starting point for coal consumption calculations. Three pathways were constructed in order to investigate how different distributions of technologies would affect the amount of needed coal. The pathways describe a implementation with only the most efficient technology, the least efficient and a middle option. The results suggest that a large scale implementation of CCS on coal power plant will have a significant impact on the global coal consumption. Under certain assumptions it takes up to 35 % more coal to deliver the same amount electricity with CCS in comparison without CCS. It is also found that certain implementation scenarios will struggle to produce the amount of coal that is needed to power the plants. A sensitivity analysis was performed to examine the impact of assumptions made on for instance plant efficiencies. The analysis shows that optimistic assumptions on development in plant efficiency and deploying only the best technology, uses less coal than a development without CCS and with current plant efficiencies.
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Atzberger, Craig Philip. "A Complex Systems Approach to Sustainability: Can Peak Oil Fuel the Sub-Saharan AIDS Epidemic?" online version, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1156898969.
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Cordell, Dana. "The Story of Phosphorus : Sustainability implications of global phosphorus scarcity for food security." Doctoral thesis, Linköping : Department of Water and Environmental Studies, [The Tema Institute], Linköping University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-53430.
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Liu, Lollo. "Life Cycle Assessment of a Lithium-Ion Battery pack for Energy storage Systems : - the environmental impact of a grid-connected battery energy storage system." Thesis, Uppsala University, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-428627.
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This thesis assessed the life-cycle environmental impact of a lithium-ion battery pack intended for energy storage applications. A model of the battery pack was made in the life-cycle assessment-tool, openLCA. The environmental impact assessment was conducted with the life-cycle impact assessment methods recommended in the Batteries Product Environmental Footprint Category Rules adopted by the European Commission (2016). The findings in this study showed that the most important parameter in the cradle-to-grave assessment was the use-stage losses, which can be reduced by using electricity grids with high sharesof renewable energy or by increase the round-trip efficiency of the battery system. However, for the cradle-to-gate assessment, five impact categories were found to be relevant. These categories were: climate change, acidification, fossil resource use, resource use (minerals and metals) and particulate matter. Furthermore, within these impact categories, four materials contributed to more than 65 % of all impact. These key materials were; nickel, aluminium, cobalt and graphite. Therefore, a recommendation to battery manufacturers is to prioritise sourcing these four key materials from sustainable suppliers to reduce the overall cradle-to-gate environmental impact. Lastly, by integrating recycling of the battery pack in the end-of-life-stage, it was possibleto achieve a net reduction of 9-20 % of the cradle-to-grave climate change, acidification and fossil resource use compared to not including recycling. Therefore, the development of efficient and large-scale recycling will likely play a major role in reducing the environmental impact from lithium-ion batteries in the future.
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Tupin, Simon. "Caractérisation de l'effet de la microstructure collagénique sur le comportement mécanique global des peaux reconstruites." Ecole nationale d'ingénieurs (Saint-Etienne), 2015. http://www.theses.fr/2015ENISE032.
Повний текст джерелаАнотація:
L'objectif de cette thèse est l'étude multi-échelle des propriétés mécaniques et structurelles de la peau reconstruite par ingéniérie tissulaire. Un premier dispositif expérimental à faible chargement a permis l'étude des propriétés visco-élastiques macroscopiques des tissus (tests d'indentation et de relaxation). L'étude bi-axiale de la raideur des différentes couches en profondeur a été menée par un dispositif original basé sur la méthode mesure continue de la raideur. La combinaison de la microscopie confocale bi-photonique avec un essai de traction a permis une évaluation originale du coefficient de Poisson de ces tissus reconstruits ainsi que les contraintes et les forces de tension du réseau de fibres de collagène. Les résultats des études menées ont montré la pertinence des outils expérimentaux développés, pour étudier le mécanisme du vieillissement et l'effet de la micro-structure sur la réponse mécanique globale des tissus reconstruitsThe aim of this thesis is the multi-scale study of the mechanical and structural properties of artificial skin. Firstly, an experimental device was designed to evaluate the mechanical properties at macroscopic scale (indentation and relaxation tests). Bi-axial study of the stiffness of different layers through depth was performed with an original device based on continuous stiffness measurements. Combination of bi-photonic confocal microscopy with a tensile test permitted the assessment of the Poisson coefficient of the reconstructed tissues, stresses and tensile forces of the collagen fibers network. Results of the studies revealed the suitability of the developped experimental tools to study aging mechanism and microstructure effects on the global mechanical behavior of artificial skin
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Müller, Jürgen [Verfasser]. "Modellierung der globalen Goldproduktion durch Anwendung der Hubbert'schen Peak-Oil Methodik / Jürgen Müller." Norderstedt : Books on Demand, 2012. http://d-nb.info/1019465735/34.
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Nordangård, Jacob. "Med brödfödan som drivkraft : En studie om att byta olja mot biodrivmedel i ett globalt perspektiv." Thesis, Linköping University, Department of Water and Environmental Studies, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8116.
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Av två anledningar anses det som mycket viktigt att bryta beroendet av olja, naturgas och kol. Den första anledningen är de uppmärksammade klimatförändringarna. Förbränning av fossila bränslen anges idag som huvudorsak till växthuseffekten. Den andra mindre uppmärksammade orsaken är att oljan och naturgasen snart inte räcker till för att föda en allt energihungrigare värld. Utvinningen ser dessutom ut att ha nåt sin kulmen. Efter denna kommer en oundviklig produktionsnedgång. Med det stora beroendet som finns av oljan inom i stort sett alla sektorer är det ytterst viktigt att hitta andra alternativ. Speciellt gäller detta inom transportområdet. Förhoppningen står idag till ”gröna” drivmedel som etanol och biodiesel. IEA (International Energy Agency) har uppmanat de västerländska nationerna att satsa stort på biobränslen. I denna studie görs en analys av de förutsättningar som finns att bygga ut produktionen av denna i USA, Brasilien och Malaysia/Indonesien. Syftet har varit att ta reda på om det är möjligt att göra detta utan att inkräkta på andra näringar, inte skada miljön samt vara oberoende av fossil energi? Den bakomliggande teorin är att detta inte låter sig göras i den omfattning som krävs för att bibehålla de nuvarande samhällsstrukturerna. Detta visar sig också stämma med de uppgifter som står till buds. Endast en fraktion av det nuvarande drivmedelsbehovet går att försörja med biodrivmedel om det inte ska uppstå en allvarlig konkurrens om odlingsmarken eller orsaka stora ekologiska skador.
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Walsh, Tim. "Local Implications of Globally Restricted Mobility: A study of Queenstown’s vulnerability to peak oil and climate change." Thesis, University of Canterbury. Geography, 2011. http://hdl.handle.net/10092/5654.
Повний текст джерелаАнотація:
This thesis employs a case study approach to investigate local implications of globally restricted mobility by examining Queenstown’s vulnerability to peak oil and climate change. Qualitative research methods are the principal means of inquiry. The research findings suggest that Queenstown is particularly vulnerable to peak oil and climate change at a broad scale because of its dependence on tourism and heavy reliance on air transport. However, Queenstown has fortuitously built up resilience to peak oil and climate change through tourism industry diversity, comparative advantage and an increasing proportion of short-haul visitors. A selection of key Queenstown tourism stakeholders interviewed as part of the research demonstrated some grasp of peak oil and climate change issues but lacked in-depth understanding. They generally considered the issues as being beyond their control although several suggested ways that Queenstown could strengthen resilience to peak oil and climate change. In terms of solutions, this research identifies three potential strategies. The first involves investing in a low carbon local transport system to increase destination level resilience to peak oil and climate change and enhance the uniqueness of the Queenstown brand. The second involves Queenstown promoters targeting the high-end niche tourism market in order to create a more resilient visitor profile. And the third involves the creation of new and expansion of existing industries not tied to tourism – preferably industries that are not excessively oil dependent and carbon intensive. But in order to successfully tackle the problem, it is imperative to first raise awareness. The research recommends implementing a framework that ensures an inclusive community-wide open dialogue process as the most effective way to achieve this.
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Kylander, Malin E. "Global perspectives on natural and anthropogenic controls on atmospheric lead and dust cycling using peat bog archives." Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/7481.
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Lehtinen, Emma. "Ekologisk hållbarhet." Thesis, Malmö universitet, Fakulteten för kultur och samhälle (KS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-23061.
Повний текст джерелаАнотація:
Detta examensarbetet är baserat på fallstudier av byggföretag som verkar i Sverige, Europa och USA. Fokuset i fallstudierna var att undersöka hur tre byggföretag applicerar och översätter de globala målen i sin verksamhet och hur det fungerar i det praktiska arbetet. Studien var koncetrerad på begrepp som hållbarhet och ekologisk hållbarhet tillsammans med Agenda 2030 - de globala målen. Begreppen behandlades genom att titta noggrannare på hur de som mål kan tolkas, översättas och verka i praktiken beroende på personens expertis och yrke. Begreppet hållbarhet, ekologiskt hållbarhet förklarades och tolkades på många varierande sätt i uppsatsen och begreppet var öppet för tolkning genom hela uppsatsen. Varje företags hemsida blev granskad och analysen baserades på hur företagen skrev om hållbarhet, de globala målen och hur begreppet ekologisk hållbarhet fungerade i företagens praktiska verksamhet. Företagen i fallstudierna var NCC AB, Peab AB och Skanska AB. Syftet med studien var att få en inblick över hur företagen applicerar, använder och arbetar med begreppen hållbarhet, ekologisk hållbarhet och de globala målen. Intervjuerna var baserad på frågor som rörde varje enskilt företag och hur deras hållbarhetsarbete ter sig i praktiken. Varje förtags representant hade en specifik hållbarhetsposition på vardera företag. Intervjuerna skedde via nätet på grund av den rådande Covid-19 situationen. En ökad kunskap om hur vi ska hantera och arbeta med ekologisk hållbarhet är en viktig aspekt som behöver utvecklas och förbättras inom byggd miljö och arkitekturen för att kunna förbättra våra bostäder och verksamheter ute i samhället. I syfte att skapa en bättre inne och utemiljö för människan och naturen. Jag använde mig av visualiseringar och tabeller för att få läsaren att lättare förstå de nya begrepp som finns med i uppsatsen som hjälper läsaren att förstå vad jag tycker och vad det är företaget berättar.This bachelor thesis is based on case studies of construction companies that operate in Sweden, Europe and the US. The focus of the studies was how these three Swedish construction companies apply and translate global environmental goals in their work. Hence, the study concentrated on the global concepts of sustainability, ecological sustainability and Agenda 2030. These concepts underwent a close analysis concerning how they can be interpreted, translated and become operational in practice depending on different expertise and profession. Based on this analysis, the concepts of sustainability and ecological sustainability were interpreted to some potential understandings to be used in this study.To analyse how the three Swedish construction companies understand and promote environmental goals, each company’s website were analysed regarding the concept of sustainability, ecological sustainability and comprehensive global goals in the field of construction. The companies included were NCC AB, Peab AB and Skanska AB. The purpose of the study was to gain knowledge about how these companies work with sustainability and act on new environmental goals. In addition, three representatives for each company were interviewed based on questions that related to the company’s work with sustainability. The interviews aimed at acquiring further knowledge on each company’s work with sustainability. Due to the spread of the COVID-19, the representatives were interviewed online.An increased knowledge of how to manage and work with ecological sustainability is an important aspect that needs to be developed and improved in the field of built environment and architecture in order to improve our homes and activities in the community. In order to create a better indoor and outdoor environment for man and nature, it’s necessary to improve the work behind ecological sustainability. In this study, visualisations and tables help the reader to understand the concepts used in this study.
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Weber, Valentine. "Simulation numérique du procédé de refusion sous laitier électroconducteur." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL010N/document.
Повний текст джерелаАнотація:
Le procédé de refusion sous laitier électroconducteur (Electro Slag Remelting ou ESR) est aujourd’hui largement utilisé pour la production d’alliages métalliques à haute valeur ajoutée, comme les aciers spéciaux ou les superalliages base nickel. La modélisation mathématique et la simulation numérique du procédé ESR présentent un grand intérêt puisque les études expérimentales sur installations industrielles sont coûteuses et souvent difficiles à mettre en oeuvre. Ainsi, afin d’améliorer la compréhension et la maîtrise de la conduite d’une refusion, un modèle prédictif a été développé dans le cadre de cette étude. Il décrit les transferts couplés de chaleur et de quantité de mouvement lors de la croissance et de la solidification d’un lingot, en géométrie axisymétrique. La résolution des équations est basée sur une approche de type volumes finis. Le modèle tient compte de l’effet Joule dans le laitier résistif, des forces électromagnétiques et de la turbulence éventuelle de l’écoulement des phases liquides. La zone pâteuse est traitée comme un milieu poreux. Le modèle permet notamment de prédire la formation de la peau de laitier solide qui entoure le laitier et le lingot. Par ailleurs, il offre l’avantage de simuler le comportement du lingot et du laitier après la coupure finale du courant.Le développement s’est accompagné d’une importante étape de validation. Quatre refusions à l’échelle industrielle ont ainsi été réalisées à l’aciérie des Ancizes (Aubert&Duval). Les observations expérimentales ont ensuite été confrontées aux résultats du calcul. La comparaison a montré que le modèle peut être utilisé afin de prédire le comportement du procédé, à condition d’accorder une attention particulière à l’estimation des propriétés thermophysiques du métal, et surtout du laitier. Enfin, afin d’illustrer l’utilisation du modèle comme support à la compréhension du procédé, nous avons étudié l’influence de la variation de paramètres opératoires tels que la profondeur d’immersion de l’électrode, le taux de remplissage ou la pression de l’eau de refroidissementElectro Slag Remelting (ESR) is widely used for the production of high-value-added alloys such as special steels or nickel-based superalloys. Because of high trial costs and complexity of the process, trial-and-error based approaches are not well suitable for fundamental studies and optimization of the process.Consequently, a transient-state numerical model which accounts for electromagnetic phenomena and coupled heat and momentum transfers in an axisymmetrical geometry has been developed. The model simulates the continuous growth of the electroslag remelted ingot through a mesh-splitting method. In addition, solidification of the metal and slag is modelled by an enthalpy-based technique. A turbulence model is implemented to compute the motion of liquid phases (slag and metal), while the mushy zone is described as a porous medium whose permeability varies with the liquid fraction, thus enabling an accurate calculation of solid/liquid interaction. The coupled partial differential equations are solved using a finite-volume technique.Computed results are compared to experimental observation of 4 industrial remelted ingots fully dedicated to the model validation step. Pool depth and shape are particularly investigated in order to validate the model. Comparison shows that the model can be used as a predictive tool to analyse the process behavior. Nevertheless, it is necessary to pay a particular attention to the estimation of the thermophysical properties of metal and especially slag.These results provide valuable information about the process performance and influence of operating parameters. In this way, we present some examples of model use as a support to analyse the influence of operating parameters. We have studied the variation of electrode immersion depth, fill ratio and water pressure in the cooling circuit
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FURTADO, Artur Muniz Szpak. "Técnicas de seguimento do ponto de máxima potência para sistemas fotovoltaicos com sombreamento parcial." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17824.
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FACEPE
A curva da potência em função da tensão nos terminais de uma conexão em série de módulos fotovoltaicos, com diodos de passagem protetores, exposta a um sombreamento parcial, exibe um comportamento com múltiplos picos. Os múltiplos picos tornam as estratégias clássicas de seguimento do ponto de máxima potência, ou MPPT, ineficazes. Em primeiro momento, este trabalho realiza uma análise estatística que determina uma região trapezoidal no plano tensão potência onde o ponto de máxima potência global está inserido para qualquer situação de irradiâncias múltiplas e temperatura, para configurações com inversor central e módulos conectados em séries puras ou conectadas em paralelo. Em segundo momento, este trabalho pesquisa as técnicas de MPPT Global que rastreiam o ponto de máxima potência global de uma curva tensão potência com múltiplos picos. Duas destas técnicas são estudadas a fim de avaliar a rapidez em encontrar o ponto de máxima potência global e a energia perdida na busca. Por fim, é proposta uma nova técnica de MPPT Global baseada no estudo estatístico preliminar. Esta nova técnica é proposta tirando proveito do trapézio delimitado na análise estatística.
The power-voltage characteristic of series arrays of photovoltaic modules with bypass diodes under partial shading conditions, displays a multiple peaks behavior. The multiple peaks make the classical algorithms of maximum power point tracking, or MPPT, ineffective. At first, this work performs a statistical analysis that determines a trapezoidal region in the power voltage plan where the global maximum power point is situated for any situation from multiple irradiances and any temperature, for central inverter configuration with a series array of modules or parallel connected series arrays. Soon after, this paper researches the Global MPPT techniques that track the global maximum power point of power-voltage curves with multiple peaks. Some of these techniques are studied to assess how fast they can find the global maximum power point and the energy lost at this search. Finally, it is proposed a new Global MPPT technique based on the preliminary statistical study. This new technique is proposed taking advantage of the trapezoidal region defined in the statistical analysis.
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Oliveira, Lucas Kerr de. "Petróleo e segurança internacional : aspectos globais e regionais das disputas por petróleo na África Subsaariana." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/11150.
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A importância do petróleo tem sido revisada nos últimos anos, principalmente pelo reconhecimento de sua função estratégico-militar, tanto no século XX, onde o controle sobre este recurso permitiu a ascensão de grandes potências, como em alguns dos conflitos atuais. Estes passaram a incluir a África nas disputas globais por petróleo. O contexto mundial se torna complexo com o aprofundamento da crise petrolífera mundial, em meio a crise de acumulação de capitais e hegemonia, ambas iniciadas nos anos 1970. O aumento dos conflitos regionais e a intensa competição entre as grandes potências por recursos energéticos cada vez mais escassos, passam a ser variáveis essenciais para a análise dos problemas de Segurança Internacional. Neste contexto o continente africano, responsável por 12% da produção petrolífera mundial, ganha ainda maior relevância global por ter dobrado o volume de suas reservas, que na porção subsaariana aumentou quase três vezes desde os anos 1980. As disputas por petróleo se misturam em meio a conflitos históricos ampliando-os e gerando novos ciclos de violência. Nos maiores produtores subsaarianos como Angola, Nigéria e Sudão, ampliam e criam novas disputas entre governo e províncias produtoras. No nível global, corporações estadunidenses e chinesas passam a disputar diretamente o acesso ao petróleo africano, apoiados pelos respectivos governos que intensificam sua presença regional na forma de investimentos, acordos comerciais, diplomáticos e militares, de treinamento e defesa, transferência de armas e instalação de bases militares. Assim, o petróleo se torna central, tanto para entender a atual dinâmica destes conflitos subsaarianos, no nível regional, como nas disputas por influência no subcontinente envolvendo China e Estados Unidos.The importance of oil has been revised in the latest years, mainly due to its strategic-military function, not only in the twentieth century, when control over this resource allowed the rise of great powers, but also in current conflicts. The latest included Africa in the global disputes over oil. Global context becomes complex as the world-wide oil crisis gets deeper, during the crisis of capital accumulation and hegemony, both having started in the 1970s. The intensification of regional conflicts and intense competition among great powers over increasingly scarce energetic resources are essential variables to the analysis of International Security problems. In this context, the African continent, responsible for 12% of world oil production, becomes globally more relevant for having doubled its reserves volume. In the subsaharan portion it has almost tripled since the 1980s. Disputes over oil make historical conflicts greater and create new cycles of violence. In the greatest sub-shaharan oil producers, such as Angola, Nigeria and Sudan these conflicts create new disputes between government and producing provinces. In a global level, North-American and Chinese corporations compete directly for access to African oil, supported by the respective governments that intensify their regional presence in the form of investments, commercial, diplomatic and military agreements, training and defense agreements, transference of weapons and installation of military bases. Thus, oil becomes central to understand the current dynamics of these sub-saharian conflicts in the regional level as well as the disputes for influence on the subcontinent involving China and United States of America.
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Oyeyemi, Elijah Oyedola. "A global ionospheric F2 region peak electron density model using neural networks and extended geophysically relevant inputs /." 2005. http://eprints.ru.ac.za/256/.
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Bradford, John Hamilton. "Systems, Social Order, and the Global Debt Crisis." 2010. http://trace.tennessee.edu/utk_graddiss/778.
Повний текст джерелаАнотація:
Part I examines the global rise of both public and private debt and its recent manifestations in the US housing bubble and the financial panic of 2007-8. A review of the most popular theories of the debt crisis is provided, including an explication of securitized banking and economic theory. The underlying condition of increasing ecological and energetic scarcity is accorded central significance in the broad trajectory of world growth and debt, Part II explicates systems theories of social order and the social significance of markets. The theories of Niklas Luhmann, Talcott Parsons, Mario Bunge, Anthony Giddens, and Jürgen Habermas are evaluated with respect to their theories of social order and crisis. A central finding is that, although declining rates of exergy production inhibit the global economic recovery as measured by conventional economic tools, this fact is not likely to be widely recognized. A central theme of Part II is how social systems handle uncertainty, risk, and to what extent complex social systems can be regulated normatively by the public sphere. As global society becomes increasingly interconnected and dependent upon the depletion of material and energy resources, the communication channels that facilitate the self-understanding of modern society at the same time proliferate, becoming increasingly disconnected and self-referential. Luhmann’s systems theory is used to explain why collective recognition and action is at once rendered more necessary and increasingly unlikely given the complexity of global society that Earth’s terrestrial stock of nonrenewable energy resources has engendered.
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Howe, Samuel. "Quantifying & Characterising Peak Intensities of Professional Rugby using GPS & Accelerometers." Thesis, 2020. https://vuir.vu.edu.au/42069/.
Повний текст джерелаАнотація:
The use of wearable technology in team sports to quantify physical activity during training and competition is now ubiquitous. Coaches typically use information derived from player tracking technologies such as Global Positioning Systems (GPS) to prescribe and monitor training. If coaches prepare players relative to the average intensity of competition, they will be underprepared for the rigors of competiton. Despite the majority of team sport competition being spent at submaximal intensity, high-intensity activities are often aligned with key events that determine match outcome. Therefore, coaches should periodically expose players to the physical worst-case scenarios of competition, whilst concurrently training tactical and technical qualities so that players may thrive and not simply survive during these intense periods of match-play. Understanding the utility of player tracking technologies, measures and analysis techniques for identifying and quantifying peak periods of competition enables coaches to more accurately interpret and use the data to inform match-specific training practices. This series of studies sought to identify, quantify and characterise the most intense periods of professional rugby competitions and periods thereafter with the aim of helping coaches to prescribe and monitor training that is more representative of competition and aid match-day tactical decisions.
Despite tri-axial accelerometers being embedded within GPS devices, their use for quantifying intense periods of team sport movement in research and practice is limited. Study one (Chapter 3) found that accelerometers outperformed GPS in quantifying positional and match-half peak intensity differences during rugby competition, identified using rolling epoch analysis. Accelerometers provided meaningful additional information to GPS technology that may aid practitioners in physically preparing and monitoring rugby players. Study two (Chapter 4) assessed the sensitivity, reliability and convergent validity of GPS and accelerometer measures for quantifying peak intensities of rugby. The poor sensitivity and low reliability of GPS and accelerometer measures implied that rugby players need to be monitored across many matches to obtain adequate precision for assessing individuals. Study three (Chapter 5) examined factors that may influence peak intensities of rugby competition, such as exercise duration, positional group, match-half, level of competition, within-season trends and time spent on field. Findings provide professional rugby coaches with duration- and position-specific intensities to aid prescription and monitoring of match-specific training, whilst improving broader understanding of factors that influence player movement intensity. Study four (Chapter 6) sequentially tracked the time-course of exercise intensity declines post the most intense periods of rugby competition using novel analysis. Exercise intensity declined sharply post the most intense periods of competition, falling below the match average intensity and rarely returning shortly thereafter. Findings may inform tactical match decisions and match representative training prescription and monitoring. Finally, study five (Chapter 7) established that professional rugby peak intensities of competition can be accurately predicted from exercise duration using power law statistical modelling, irrespective of playing position, match-half, level of competition or measure of exercise intensity. Novel insights on model prediction error as well as the patterns of error as a function of time may assist coaches to accurately interpret and use power law to prescribe and monitor match-specific training.
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Gill, Allison Lorraine. "Coupling of belowground biogeochemical cycles and plant carbon allocation strategies highlight global patterns in resource limitation and ecosystem-level responses to global change." Thesis, 2017. https://hdl.handle.net/2144/27079.
Повний текст джерелаАнотація:
Soils contain the largest terrestrial pool of carbon (C), but the magnitude and distribution of the soil C sink may be sensitive to climate change. My dissertation aims to identify key processes that mediate patterns of belowground carbon storage across the globe and quantify the effect of environmental perturbations associated with global change on existing soil carbon stocks in peatland ecosystems. Using meta-analysis, I show that the relationship between plant growth, C allocation, and soil nutrient availability varies on a global scale and high-latitude ecosystems allocate >60% of fixed C to belowground structures. As high latitude ecosystems are warming faster than the global mean, the future of this belowground C store is potentially sensitive to climate change. In high latitude ecosystems in particular, I further show that belowground warming increases the rate of peatland carbon dioxide (CO2) and methane (CH4) losses, although CH4 emissions are more sensitive to warming than CO2 emissions, which is likely to shift the nature of greenhouse gas emissions and increase the importance of CH4 as a radiative forcing agent in the near-term. I also use a natural peatland water table gradient to identify the effect of water table reduction on peatland C and N cycling and find that microbial community shifts in C and N demand may attenuate production of C-degrading enzymes and C mineralization in the presence of plant roots and in areas with low water tables. Together, my dissertation work highlights the important role of belowground plant and microbial processes in high latitude ecosystems, and identifies the potential influence of factors associated with global change on belowground C and nutrient cycling.
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DI, FINA DARIO. "Multi-Target Tracking and Facial Attribute Estimation in Smart Environments." Doctoral thesis, 2016. http://hdl.handle.net/2158/1029030.
Повний текст джерелаАнотація:
This dissertation presents a study on three different computer vision topics that have applications to smart environments. We first propose a solution to improve multi-target data association based on l1-regularized sparse basis expansions. The method aims to improve the data association process by addressing problems like occlusion and change of appearance. Experimental results show that, for the pure data association problem, our proposed approach achieves state-of-the-art results on standard benchmark datasets.
Next, we extend our new data association approach with a novel technique based on a weighted version of sparse reconstruction that enforces long-term consistency in multi-target tracking. We introduce a two-phase approach that first performs local data association, and then periodically uses accumulated usage statistics in order to merge tracklets and enforce long-term, global consistency in tracks. The result is a complete, end-to-end tracking system that is able to reduce tracklet fragmentation and ID switches, and to improve the overall quality of tracking.
Finally, we propose a method to jointly estimate face characteristics such as Gender, Age, Ethnicity and head pose. We develop a random forest based method based around a new splitting criterion for multi-objective estimation. Our system achieves results comparable to the state-of-the-art, and has the additional advantage of simultaneously estimating multiple facial characteristics using a single pool of image features rather than characteristic-specific ones.