52 research outputs found

    CO2 Capture and Renewable Energy

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    The urgently needed carbon neutral economy requires a portfolio of strategies, among which, CO2 capture and renewable energy will need to play a decisive role. Dispatchable renewables, such as bioenergy, will play an increasing role in maintaining electricity security, in producing heat in the industry and residential sectors, and in reducing the emissions from the transport sector. Biomethane, also known as a renewable natural gas, can be directly blended with or fully replace natural gas in existing pipelines and end-user equipment, with the added advantage of being carbon neutral. CO2 capture and storage (CCS) will also be of paramount importance in abating CO2 emissions from existing infrastructure in the power and industrial sectors. There are many industries that will be difficult or impossible to decarbonize in the short term, such as the cement sector, in which CO2 emissions are intrinsic to the production process. In such cases, CCS will be mandatory to achieve the goal of net zero emissions. Permanent CO2 removal technologies, such as bioenergy with carbon capture and storage (BECCS) and direct air capture and storage (DACS), will also be necessary in the medium term to compensate for emissions from the hard-to-abate sectors, and in the long term, even to remove atmospheric CO2 from past emissions. This book consists of six peer-reviewed scientific articles that cover a range of high-interest subjects related to the aforementioned hot topics

    Accountability and narratives in historical settings

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    The critical and interpretative accounting studies on accountability constitute the basis for the development of the three papers of this Ph.D. thesis. Connected from a thematic and a methodological perspective, these three archival based researches explore different aspects of accountability. The attention moves progressively from exploring a retrospective storytelling as an informal media of accountability; to comparing this informal narrative with those contained in the formal media; to finally study different forms through which accountability can be practiced. While the first and the second papers focuses on the role played by stories and narratives in the provision of accountability, the third paper enlarges the focus to explore the relation between narratives and accounting in the provision of accountability. In this thesis accounting is conceived as a discourse where specific rules are applied, a social practice and a technique, that may be used in the accountability discourse

    Interacção 2010: actas da 4ª Conferência Nacional em Interacção Humano-Computador

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    Prefácio: Encontramo-nos perante mais uma edição do congresso nacional sobre Interacção, o “Interacção 2010”, um evento científico cuja regularidade tem permitido consolidar a sua natureza profundamente transdisciplinar. A referência do congresso continua a ser a área científica internacional de “Human-Computer Interaction”, uma área que tem ganhado relevância e valor no progresso sócio-económico desta última década, onde o ser humano e a coisa social assumem a prioridade que lhes é devida. O “Interacção” tem assumido sempre a condição da debater um vasto leque de temas, mas sempre em contextos de mediação tecnológica e onde o objectivo final é servir a condição humana. Esta edição continua a confirmar esta atitude que se reflecte nas grandes áreas temáticas que anunciou para submissão de trabalhos: Concepção, Desenvolvimento e Estudo da Interacção, Tecnologias e Aplicações de Suporte à Interacção, Aspectos Humanos, Sociais e Organizacionais, e Contextos de Interacção diversos. A resposta da comunidade científica nacional ao apelo de participação foi de extrema eficiência e riqueza. Foram submetidos um total de 64 artigos longos, artigos curtos e posters e/ou demos. O resultado da avaliação (“double-blind”) pelos revisores, e as conversões de formato sugeridas a alguns autores, conduziram a que o leitor venha a encontrar nestas actas 21 artigos longos, 20 artigos curtos e 15 posters. Por insuficiência de propostas de demos esta possibilidade de exposição não foi considerada. Esta quantidade crescente de trabalho em relação a edições anteriores do “Interacção”, e os três oradores convidados (2 internacionais e 1 nacional), originaram um programa de trabalho que incontornavelmente se estendeu a três dias de trabalho contrariando os tradicionais dois dias de congresso. O programa decorreu de 13 a 15 de Outubro de 2010 na Universidade de Aveiro e as 8 sessões que o caracterizaram foram organizadas respeitando os temas: i) Interfaces Multi-toque; ii) Interacção com Dispositivos Móveis; iii) Concepção e Desenvolvimento da Interacção; iv) Realidade Virtual e Aumentada; v) Visualização de Informação; vi) Videojogos e Interacção; vii) Acessibilidade e viii) Interacção em Contextos Diversos. Por fim, e porque um evento desta natureza não se consegue organizar sem a mobilização, o trabalho de grande qualidade e a dedicação de várias pessoas, importa agradecer a todos os elementos da Comissão Organizadora, e aos estudantes voluntários que ajudaram em toda a logística, bem como a todos os elementos da Comissão de Programa e aos revisores externos que também aceitaram analisar trabalhos submetidos. Aos nossos convidados, Francisco Providência, Jennifer Preece e Shahram Izadi, pela disponibilidade de estarem e partilharem connosco o seu conhecimento e experiência na área, o nosso sincero obrigado. Pelo papel fundamental de um secretariado profissional e eficiente fica ainda o nosso agradecimento à Anabela Viegas. Terminamos com o especial agradecimento a todos os autores e conferencistas que acreditaram na competência e rigor de toda esta equipa para acolher o seu trabalho e expô-lo publicamente. Despedimo-nos acreditando que o "Interacção" continuará por terras lusas, quiçá numa toada cada vez mais internacionalizada, e deixando votos para que a edição de 2012 seja pautada por igual sucesso e entusiasmo; a área da Interacção assim o exige e merece. Bem hajam. Aveiro, Outubro de 2010. Óscar Mealha, Daniel Tércio, Beatriz Sousa Santos, Joaquim Madeira.publishe

    The ecology of the Great Bay Estuary, New Hampshire and Maine: An Estuarine Profile and Bibliography

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    Industrial Energy Management and Sustainability

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    Growing environmental concerns caused by increasing consumption of naturalresources and pollution need to be addressed. Manufacturing dictates the efficiencywith which resource inputs are transformed into economically valuableoutputs in the form of products and services. Consequently, it is also responsiblefor the resulting waste and pollution generated from this transformation process.As a matter of fact, about one-third of the global total energy consumption isassociated withmanufacturing activities; thus, achieving higher energy efficiencyin this sector has been the focus of research as well as of policy and industrialprogrammes in recent years. In particular, being able to effectively manageenergy and energy-related activities has proved to be a fundamental capabilityfor companies willing to improve their sustainability, as it constitutes the first,critical step to understanding their processes and to identifying and correctlyevaluating improvement opportunities.This Special Issue focuses on energy management and sustainability of bothmanufacturing processes and systems, including methods, practices, tools, applicationsand experiences

    Axisymmetric simulation codes for hall effect thrusters and plasma plumes

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    Mención Internacional en el título de doctorThe development of reliable and versatile plasma discharges simulation codes is becoming of central importance, given the rapidly evolving electric propulsion landscape. These tools are essential for facilitating and complementing the design of new prototypes, signiffcantly reducing development time and costs. Moreover, they can provide a deeper insight on already proven technologies, revealing optimization opportunities so as to improve the thruster performance and lifetime, and predicting the operational parameters at different regimes of interest. This Thesis is devoted to the numerical study of different plasma discharges and, in particular, the Hall effect thruster (HET) discharge. With special focus on particle-based modeling, two simulation codes have been developed. The first one, named HYPHEN, is a new two-dimensional axisymmetric hybrid, particle-in-cell (PIC)/fluid multi-thruster simulation platform. Its versatile PIC-based module for heavy species supports the simulation of inner active surfaces, mixed specular-diffuse neutral-wall reflection, and chargeexchange (CEX) collisions, thus extending the code capabilities and enabling the simulation of axisymmetric plasma plumes. Moreover, it features a new population control which monitors independently every heavy species and limits the statistical noise at a low computational cost. Furthermore, an improved version of the HET electron fluid module for the isotropic electron pressure case is presented. Three major studies have been carried out with this code. First, the simulation of an ion thruster plasma plume has permitted to benchmark HYPHEN against the 3D plasma plume code EP2PLUS. Second, an investigation on the neutral-wall interaction effects on an unmagnetized plasma discharge in a surface-dominated cylindrical channel with isothermal electrons has been performed. The discharge ignition requires different propellant injection mass ows in the diffuse and specular neutral-wall reflection cases. Third, preliminary simulations of a SPT-100 HET have been carried out to demonstrate the code capabilities and reveal its limitations. Consistent results have been obtained for different cathode locations in the near plume region and various electron turbulent transport parameter profiles. The second code corresponds to a new version of the one-dimensional radial particle model of a HET discharge, originally developed by F. Taccogna. The major improvements are an ionization controlled discharge algorithm, which enables sustaining a steady-state discharge, and an extended volumetric weighting algorithm which provides a more accurate macroscopic description of the low populated species, such as the wall-emitted secondary electrons. The radial dynamics of both the primary and secondary electron populations have been analyzed in detail, assessing the temperature anisotropy ratio of their velocity distribution functions and the asymmetries introduced by cylindrical geometry effects in the macroscopic laws of interest, thus aiming at a future improvement of the plasma-wall interaction module implemented in HYPHEN.El desarrollo de códigos fiables y versátiles para la simulación de descargas de plasma es cada vez más importante dada la rápida evolución de la propulsión espacial eléctrica. Estas herramientas son esenciales para facilitar y complementar el diseño de nuevos prototipos, reduciendo significativamente los tiempos y costes de desarrollo. Además, pueden ampliar la comprensión de las tecnologías ya establecidas, revelar vías de optimización del propulsor que permitan mejorar su rendimiento y vida útil, y predecir los parámetros de operación del mismo en diferentes regímenes de interés. Esta Tesis está dedicada al estudio numérico de diferentes descargas de plasma y, en particular, de descargas HET. Se han desarrollado dos códigos de simulación, con especial énfasis en los modelos de partículas. El primero de ellos, llamado HYPHEN, es una nueva plataforma de simulación multi-propulsor, híbrida PIC/fluida y axisimétrica. Su módulo PIC para especies pesadas permite la simulación de superficies activas inmersas en el plasma, procesos de reflexión especular-difuso de neutros en pared y colisiones CEX, extendiendo por tanto las capacidades del código y permitiendo la simulación de plumas de plasma axisimétricas. Además, incluye un nuevo control de población que monitoriza a cada especie pesada por separado limitando el ruido estadístico y el coste computacional. Por otra parte, se presenta una versión mejorada del modelo fluido de electrones isótropos para HET. Tres estudios principales se han llevado a cabo con este código. En primer lugar, la simulación de la pluma de plasma de un motor iónico ha permitido validar HYPHEN con el código de plumas 3D EP2PLUS. Por otro lado, se ha investigado el efecto de la interacción del gas neutro con la pared en una descarga no magnetizada con electrones isotermos en un canal cilíndrico esbelto. La ignición de la descarga requiere inyectar diferentes gastos másicos de propulsante en los casos de reflexión difusa y especular. En tercer lugar, se han realizado simulaciones preliminares de un motor HET de tipo SPT- 100 con el objeto de demostrar las capacidades del código y revelar sus limitaciones, obteniendo resultados consistentes para diferentes posiciones del cátodo en la región de la pluma cercana, y perfies del parámetro de turbulencia de electrones. El segundo código representa una nueva versión del modelo radial de partículas de una descarga HET desarrollado originalmente por F. Taccogna. Las principales mejoras consisten en un algoritmo de control de la descarga a través de la ionización, que permite obtener una descarga estacionaria, y un algoritmo de pesado volumétrico extendido, que proporciona una descripción macroscópica más precisa de las especies poco pobladas, como los electrones secundarios emitidos desde las paredes del motor. Para posibilitar una futura mejora del módulo de HYPHEN de interacción plasma-pared, se han analizado en detalle la dinámica radial de los electrones primarios y secundarios, la anisotropía de temperatura de sus funciones de distribución de velocidad, y las asimetrías cilíndricas en las leyes macroscópicas de interés.Programa Oficial de Doctorado en Mecánica de Fluidos por la Universidad Carlos III de Madrid; la Universidad de Jaén; la Universidad de Zaragoza; la Universidad Nacional de Educación a Distancia; la Universidad Politécnica de Madrid y la Universidad Rovira i Virgili.Presidente: Iván Calvo Rubio.- Secretario: Gonzalo Sánchez Arriaga.- Vocal: Daniela Pedrin

    Clean. Reliable. Affordable. The role of nuclear technology in meeting the challenge of low greenhouse gas electricity supply in the 21st century

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    Climate change is broadly acknowledged as one of the greatest challenges facing humankind this century. The emission of greenhouse gases from human activity is driving warming of the atmosphere. The extent of the forecast warming has the potential to seriously and irreversibly alter global environments, with consequently serious impacts for humankind in our occupation of this planet. The energy sector is one of the largest sources of anthropogenic greenhouse gas emissions, being based nearly entirely on the combustion of fossil-carbon fuels, including for the generation of electricity. This energy consumption raises standards of living and is central to the development processes that alleviate poverty and reduce population growth rates. Non-fossil options for the generation of electricity include renewable energy sources (covering hydro, wind, solar, geothermal, wave, ocean, tidal and biomass) and nuclear fission in power-generating nuclear reactors. While nuclear power, along with hydroelectricity, has historically proven to be an effective and scalable replacement for fossil fuels in electricity generation, this technology lacks broad support, is actively opposed by the great majority of environmental groups and has grown little in recent decades. The exclusive use of non-hydro renewable technologies to generate electricity lacks historic evidence of scalability and cost-effectiveness, however these technologies enjoy popular support and the amount of electricity they supply is growing rapidly. This thesis examines how to provide electricity supply that is free from fossil carbon fuels at relevant global scale in the 21st century by examining the benefits and drawbacks of both nuclear and renewable technologies and considering their potential role in forming workable, cost-effective portfolios of solutions. I examine in detail the rapid transition towards wind and solar power in South Australia (Chapter 1), and critically review literature purporting to provide evidence that only renewable technologies are required for reliable, cost effective, clean electricity supply (Chapter 2). I undertake modelling of Australia’s National Electricity Market using varying combinations of nuclear and renewable technologies to identify cost-optimal supply combinations at varying carbon prices (Chapter 3), and re-model the potential for nuclear to meet a supply gap that is greatly modified by the uptake of variable renewable generation (Chapter 4). The potential role of advanced nuclear technologies is examined in a business case for storing used nuclear fuel and re-investing revenue in the development of fuel recycling facilities and advanced reactors (Chapter 5). I demonstrate that nuclear technology is an essential solution for the challenge of displacing fossil fuels from electricity supply, and that this role is robust against a range of assumptions and projections relating to greater use of renewable technologies. I conclude with a brief consideration of the little-studied challenge of providing industrial heat including to manufacture chemical feedstocks, a segment of energy consumption where advanced, high-temperature nuclear reactors may have a nearly unfettered role in the displacement of fossil fuels.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Biological Sciences, 201

    When Can Oil Economies Be Deemed Sustainable?

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    This open access book questions the stereotype depicting all Gulf (GCC) economies as not sustainable, and starts a critical discussion of what these economies and polities should do to guarantee themselves a relatively stable future. Volatile international oil markets and the acceleration of the energy transition has challenged the notion that oil revenues are sufficient to sustain oil economies in the near to medium term. But what is the meaning of economic sustainability? The book discusses the multiple dimensions of the concept: economic diversification, continuing value of resources, taxation and fiscal development, labor market sustainability, sustainable income distribution, environmental sustainability, political order (democracy or authoritarianism) and sustainability, regional integration. The overarching message in this book is that we should move on from the simplistic branding of the Gulf economies as unsustainable and tackle the details of which adaptations they might need to undertake
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