882 resultados para Low-carbon operations
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With an increasingly growing demand for natural resources, the Arctic region has become an attractive area, holding about 15% of world oil. Ice shrinkage caused by global warming encourages the development of offshore and ship-building sectors. Russia, as one of the leading oil and gas production countries is participating actively in cold resistant materials research, since half of its territory belongs to the Arctic environment, which held considerable stores of oil. Nowadays most Russian offshore platforms are located in the Sakhalin Island area, which geographically does not belong to the Arctic, but has com-parable environmental conditions. Russia recently has manufactured several offshore platforms. It became clear that further development of the Arctic off-shore structures with necessary reliability is highly depending on the materials employed. This work pursues the following objectives: to provide a comprehensive review on Russian metals used for Arctic offshore structures on the base of standards, books, journal articles and companies reports to overview various Arctic offshore structures and its structural characteristics briefly discuss materials testing methods for low temperatures Master`s thesis focuses on specifications and description of Russian metals which are already in use and can be used for Arctic offshore structures. Work overviews several groups of steel, such as low carbon, low alloy, chromium containing steels, stainless steels, aluminium and nanostructured steels. Materials under discussion are grouped based on the standards, for instance the work covers shipbuilding and structural steels at the different sections. This paper provides an overview of important Russian Arctic offshore projects built for use in Russia and ordered by foreign countries. Future trends in development of the Arctic materials are discussed. Based on the information provided in this Master`s thesis it is possible to learn about Russian metals used for ships and offshore platforms operated in the Arctic region. Paper can be used as the comprehensive review of current materials, such as various steels, aluminium and nanomaterials.
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Wind power is a low-carbon energy production form that reduces the dependence of society on fossil fuels. Finland has adopted wind energy production into its climate change mitigation policy, and that has lead to changes in legislation, guidelines, regional wind power areas allocation and establishing a feed-in tariff. Wind power production has indeed boosted in Finland after two decades of relatively slow growth, for instance from 2010 to 2011 wind energy production increased with 64 %, but there is still a long way to the national goal of 6 TWh by 2020. This thesis introduces a GIS-based decision-support methodology for the preliminary identification of suitable areas for wind energy production including estimation of their level of risk. The goal of this study was to define the least risky places for wind energy development within Kemiönsaari municipality in Southwest Finland. Spatial multicriteria decision analysis (SMCDA) has been used for searching suitable wind power areas along with many other location-allocation problems. SMCDA scrutinizes complex ill-structured decision problems in GIS environment using constraints and evaluation criteria, which are aggregated using weighted linear combination (WLC). Weights for the evaluation criteria were acquired using analytic hierarchy process (AHP) with nine expert interviews. Subsequently, feasible alternatives were ranked in order to provide a recommendation and finally, a sensitivity analysis was conducted for the determination of recommendation robustness. The first study aim was to scrutinize the suitability and necessity of existing data for this SMCDA study. Most of the available data sets were of sufficient resolution and quality. Input data necessity was evaluated qualitatively for each data set based on e.g. constraint coverage and attribute weights. Attribute quality was estimated mainly qualitatively by attribute comprehensiveness, operationality, measurability, completeness, decomposability, minimality and redundancy. The most significant quality issue was redundancy as interdependencies are not tolerated by WLC and AHP does not include measures to detect them. The third aim was to define the least risky areas for wind power development within the study area. The two highest ranking areas were Nordanå-Lövböle and Påvalsby followed by Helgeboda, Degerdal, Pungböle, Björkboda, and Östanå-Labböle. The fourth aim was to assess the recommendation reliability, and the top-ranking two areas proved robust whereas the other ones were more sensitive.
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In recent decades, business intelligence (BI) has gained momentum in real-world practice. At the same time, business intelligence has evolved as an important research subject of Information Systems (IS) within the decision support domain. Today’s growing competitive pressure in business has led to increased needs for real-time analytics, i.e., so called real-time BI or operational BI. This is especially true with respect to the electricity production, transmission, distribution, and retail business since the law of physics determines that electricity as a commodity is nearly impossible to be stored economically, and therefore demand-supply needs to be constantly in balance. The current power sector is subject to complex changes, innovation opportunities, and technical and regulatory constraints. These range from low carbon transition, renewable energy sources (RES) development, market design to new technologies (e.g., smart metering, smart grids, electric vehicles, etc.), and new independent power producers (e.g., commercial buildings or households with rooftop solar panel installments, a.k.a. Distributed Generation). Among them, the ongoing deployment of Advanced Metering Infrastructure (AMI) has profound impacts on the electricity retail market. From the view point of BI research, the AMI is enabling real-time or near real-time analytics in the electricity retail business. Following Design Science Research (DSR) paradigm in the IS field, this research presents four aspects of BI for efficient pricing in a competitive electricity retail market: (i) visual data-mining based descriptive analytics, namely electricity consumption profiling, for pricing decision-making support; (ii) real-time BI enterprise architecture for enhancing management’s capacity on real-time decision-making; (iii) prescriptive analytics through agent-based modeling for price-responsive demand simulation; (iv) visual data-mining application for electricity distribution benchmarking. Even though this study is from the perspective of the European electricity industry, particularly focused on Finland and Estonia, the BI approaches investigated can: (i) provide managerial implications to support the utility’s pricing decision-making; (ii) add empirical knowledge to the landscape of BI research; (iii) be transferred to a wide body of practice in the power sector and BI research community.
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Currently widely accepted consensus is that greenhouse gas emissions produced by the mankind have to be reduced in order to avoid further global warming. The European Union has set a variety of CO2 reduction and renewable generation targets for its member states. The current energy system in the Nordic countries is one of the most carbon free in the world, but the aim is to achieve a fully carbon neutral energy system. The objective of this thesis is to consider the role of nuclear power in the future energy system. Nuclear power is a low carbon energy technology because it produces virtually no air pollutants during operation. In this respect, nuclear power is suitable for a carbon free energy system. In this master's thesis, the basic characteristics of nuclear power are presented and compared to fossil fuelled and renewable generation. Nordic energy systems and different scenarios in 2050 are modelled. Using models and information about the basic characteristics of nuclear power, an opinion is formed about its role in the future energy system in Nordic countries. The model shows that it is possible to form a carbon free Nordic energy system. Nordic countries benefit from large hydropower capacity which helps to offset fluctuating nature of wind power. Biomass fuelled generation and nuclear power provide stable and predictable electricity throughout the year. Nuclear power offers better energy security and security of supply than fossil fuelled generation and it is competitive with other low carbon technologies.
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The construction of offshore structures, equipment and devices requires a high level of mechanical reliability in terms of strength, toughness and ductility. One major site for mechanical failure, the weld joint region, needs particularly careful examination, and weld joint quality has become a major focus of research in recent times. Underwater welding carried out offshore faces specific challenges affecting the mechanical reliability of constructions completed underwater. The focus of this thesis is on improvement of weld quality of underwater welding using control theory. This research work identifies ways of optimizing the welding process parameters of flux cored arc welding (FCAW) during underwater welding so as to achieve desired weld bead geometry when welding in a water environment. The weld bead geometry has no known linear relationship with the welding process parameters, which makes it difficult to determine a satisfactory weld quality. However, good weld bead geometry is achievable by controlling the welding process parameters. The doctoral dissertation comprises two sections. The first part introduces the topic of the research, discusses the mechanisms of underwater welding and examines the effect of the water environment on the weld quality of wet welding. The second part comprises four research papers examining different aspects of underwater wet welding and its control and optimization. Issues considered include the effects of welding process parameters on weld bead geometry, optimization of FCAW process parameters, and design of a control system for the purpose of achieving a desired bead geometry that can ensure a high level of mechanical reliability in welded joints of offshore structures. Artificial neural network systems and a fuzzy logic controller, which are incorporated in the control system design, and a hybrid of fuzzy and PID controllers are the major control dynamics used. This study contributes to knowledge of possible solutions for achieving similar high weld quality in underwater wet welding as found with welding in air. The study shows that carefully selected steels with very low carbon equivalent and proper control of the welding process parameters are essential in achieving good weld quality. The study provides a platform for further research in underwater welding. It promotes increased awareness of the need to improve the quality of underwater welding for offshore industries and thus minimize the risk of structural defects resulting from poor weld quality.
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Strenx® 960 MC is a direct quenched type of Ultra High Strength Steel (UHSS) with low carbon content. Although this material combines high strength and good ductility, it is highly sensitive towards fabrication processes. The presence of stress concentration due to structural discontinuity or notch will highlight the role of these fabrication effects on the deformation capacity of the material. Due to this, a series of tensile tests are done on both pure base material (BM) and when it has been subjected to Heat Input (HI) and Cold Forming (CF). The surface of the material was dressed by laser beam with a certain speed to study the effect of HI while the CF is done by bending the specimen to a certain angle prior to tensile test. The generated results illustrate the impact of these processes on the deformation capacity of the material, specially, when the material has HI experience due to welding or similar processes. In order to compare the results with those of numerical simulation, LS-DYNA explicit commercial package has been utilized. The generated results show an acceptable agreement between experimental and numerical simulation outcomes.
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The increasing emphasis on energy efficiency is starting to yield results in the reduction in greenhouse gas emissions; however, the effort is still far from sufficient. Therefore, new technical solutions that will enhance the efficiency of power generation systems are required to maintain the sustainable growth rate, without spoiling the environment. A reduction in greenhouse gas emissions is only possible with new low-carbon technologies, which enable high efficiencies. The role of the rotating electrical machine development is significant in the reduction of global emissions. A high proportion of the produced and consumed electrical energy is related to electrical machines. One of the technical solutions that enables high system efficiency on both the energy production and consumption sides is high-speed electrical machines. This type of electrical machines has a high system overall efficiency, a small footprint, and a high power density compared with conventional machines. Therefore, high-speed electrical machines are favoured by the manufacturers producing, for example, microturbines, compressors, gas compression applications, and air blowers. High-speed machine technology is challenging from the design point of view, and a lot of research is in progress both in academia and industry regarding the solution development. The solid technical basis is of importance in order to make an impact in the industry considering the climate change. This work describes the multidisciplinary design principles and material development in high-speed electrical machines. First, high-speed permanent magnet synchronous machines with six slots, two poles, and tooth-coil windings are discussed in this doctoral dissertation. These machines have unique features, which help in solving rotordynamic problems and reducing the manufacturing costs. Second, the materials for the high-speed machines are discussed in this work. The materials are among the key limiting factors in electrical machines, and to overcome this limit, an in-depth analysis of the material properties and behavior is required. Moreover, high-speed machines are sometimes operating in a harsh environment because they need to be as close as possible to the rotating tool and fully exploit their advantages. This sets extra requirements for the materials applied.
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L’observation de l’exécution d’applications JavaScript est habituellement réalisée en instrumentant une machine virtuelle (MV) industrielle ou en effectuant une traduction source-à-source ad hoc et complexe. Ce mémoire présente une alternative basée sur la superposition de machines virtuelles. Notre approche consiste à faire une traduction source-à-source d’un programme pendant son exécution pour exposer ses opérations de bas niveau au travers d’un modèle objet flexible. Ces opérations de bas niveau peuvent ensuite être redéfinies pendant l’exécution pour pouvoir en faire l’observation. Pour limiter la pénalité en performance introduite, notre approche exploite les opérations rapides originales de la MV sous-jacente, lorsque cela est possible, et applique les techniques de compilation à-la-volée dans la MV superposée. Notre implémentation, Photon, est en moyenne 19% plus rapide qu’un interprète moderne, et entre 19× et 56× plus lente en moyenne que les compilateurs à-la-volée utilisés dans les navigateurs web populaires. Ce mémoire montre donc que la superposition de machines virtuelles est une technique alternative compétitive à la modification d’un interprète moderne pour JavaScript lorsqu’appliqué à l’observation à l’exécution des opérations sur les objets et des appels de fonction.
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Note d'analyse
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Cette note présente des résultats de deux importants sondages menés en parallèle dans les deux pays. Au Canada, nos données sont tirées du plus récent Canadian Survey on Energy and the Environment (CSEE, Lachapelle et al. 2015) et aux États-Unis, nous rapportons les résultats du National Survey on Energy and the Environment (NSEE). Réalisés au mois de septembre 2015, ces deux sondages ont soumis les mêmes questions à des échantillons représentatifs des populations du Canada et des États-Unis.
Resumo:
Objetivo: Determinar el nivel de riesgo de la exposición por fracción respirable a polvo de carbón y sílice cristalina y la prevalencia de neumoconiosis en trabajadores de minas de socavón del departamento de Cundinamarca. Métodos: estudio de corte transversal, en grupos de exposición similar (GES) en las minas seleccionadas, el tamaño muestral fue constituido por 11 empresas y 215 trabajadores en donde se realizó un muestreo ambiental para medir los niveles de polvo de carbón y sílice cristalina. Resultados: La edad promedio del grupo fue de 46±9,5 años y género masculino (97,2%), se encontró una asociación significativa entre polvo de carbón y neumoconiosis (p =0,050) y no fue significativa con exposición a sílice cristalina (p = 0,537). El modelo de regresión logística mostró asociación significativa con la escala de nivel de riesgo de carbón medio (OR=10.4, IC 95%:1.50, 71.41, p=0,02), ajustando con variables significativas como: tamaño de la empresa mediana (OR = 2,67, IC 95%:1.07, 6.66, p=0,04), antigüedad mayor o igual a 30 años (OR = 7,186, IC 95%:2.98, 17.29, p=0,001) y habito tabáquico por más de un año (OR = 4,437, IC 95%:2.06, 9.55, p=0,001) para sílice cristalina no hubo asociación en el modelo multivariado. Conclusión: El riesgo de exposición a carbón de nivel medio está relacionado con la prevalencia de neumoconiosis y otros factores adicionales como tamaño de la empresa mediana, antigüedad mayor o igual a 30 años y habito tabáquico por más de un año para los trabajadores de minería de socavón en Cundinamarca. Para los niveles de sílice cristalina no se encontró asociación significativa.
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La presente investigación tiene como objetivo principal determinar el papel de la estrategia colombiana de desarrollo bajo en carbono en el mercado de bonos de carbono en Colombia. Esto con el fin de demostrar que las acciones nacionalmente apropiadas de mitigación NAMAS son un mecanismo de mitigación y puede no tener una incidencia en la oferta ni tampoco en la demanda del mercado de bonos de carbono en Colombia. Esta investigación se llevará a cabo por medio de un estudio de caso con un enfoque institucionalista. Se utilizará el método de investigación cualitativo, ya que se intenta medir las cualidades de la estrategia colombiana de desarrollo bajo en carbono mediante un análisis documental, teniendo como referencia las fuentes primarias; el Conpes 3700 de 2011, entrevistas a expertos del Ministerio de Ambiente y Desarrollo Sostenible, Fundación Natura, ConTREEbute, Área Metropolitana del Valle de Aburra, y fuentes secundarias, entre otras.
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El presente estudio de caso, busca explicar cuáles son las posibles implicaciones e influencia de la construcción del Proyecto del Canal de Nicaragua en la geografía, la economía y la política exterior del Caribe Occidental. Esta investigación defiende que la construcción de este canal influirá en el largo plazo en la geopolítica de esta región, debido a la posibilidad de una competencia hasta hoy inexistente en la región entre dos canales interoceánicos, que puede llegar a afectar la disponibilidad de recursos naturales de la subregión, y asimismo, fortalecer la presencia asiática en América Latina; sin embargo, las consecuencias de este canal no pueden determinarse de manera específica. Para sustentar lo anterior, se realizará una revisión del proceso de construcción del canal de Panamá y del proyecto del de Nicaragua, para establecer un estudio de prospectiva de los escenarios posibles para la región del Caribe Occidental.
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The thermal performance of a horizontal-coupled ground-source heat pump system has been assessed both experimentally and numerically in a UK climate. A numerical simulation of thermal behaviour of the horizontal-coupled heat exchanger for combinations of different ambient air temperatures, wind speeds, refrigerant temperature and soil thermal properties was studied using a validated 2D transient model. The specific heat extraction by the heat exchanger increased with ambient temperature and soil thermal conductivity, however it decreased with increasing refrigerant temperature. The effect of wind speed was negligible.