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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Difusão da construção em madeira no Brasil: agentes, ações e produtos / Diffusion of timber construction in Brazil: stakeholders, actions and products.

Erich Kazuo Shigue 20 June 2018 (has links)
Na última década em diversos países do mundo vem crescendo o debate para o aumento do uso da madeira, em especial para o setor da construção civil, incentivado por dois motivos principais: pela capacidade de absorção de CO2 e consequente contribuição para a economia de baixo carbono e o desenvolvimento de novas tecnologias industrializadas, predominantemente aquelas conhecidas como mass timber. Apesar de 60% do território brasileiro ser coberto por florestas e do potencial madeireiro do país, o uso da madeira como material construtivo é pouco expressivo. No entanto, em consonância com o debate mundial, o Brasil também dá indícios de desenvolvimento do setor da construção civil em madeira. Este trabalho teve como objetivo caracterizar a tendência de aumento do uso da madeira através do levantamento dos agentes envolvidos nesse processo; das ações para a promoção do uso do material e dos produtos disponíveis no mercado. Também foram identificados os obstáculos enfrentados, as motivações e as perspectivas futuras. Cabe ressaltar que a pesquisa foi realizada com foco no setor privado e com o uso da madeira predominantemente em edificações na forma de estrutura e/ou vedação. Foram utilizadas duas abordagens metodológicas: mapeamento sistêmico e estudo de caso. O mapeamento sistêmico foi composto pelo levantamento bibliográfico e pesquisa documental, que num primeiro momento identificou quem são os principais agentes envolvidos e posteriormente, levantou dados sobre sua atuação e produção. Como resultado, foram identificadas 42 instituições e 66 empresas, além de 24 produtos entre sistemas, subsistemas e componentes construtivos e 20 ações de promoção da madeira, entre eventos, programas e mídia. Posteriormente foram selecionados 22 agentes, com base na expressividade em sua área de atuação, entre empresas e instituições, para a aplicação de entrevistas semi-estruturadas visando levantar as motivações e entraves do setor. Com isso foi possível verificar o aumento do número de empresas atuantes com tecnologias construtivas em madeira, e da variedade de produtos disponíveis no mercado, com destaque para as tecnologias industrializadas, assim como de ações para a promoção da madeira, particularmente no ano de 2017. Constatou-se ainda que o fenômeno trata-se não do aumento do uso da madeira em si, mas das tecnologias em produtos industrializados e que existe uma aproximação entre o setor florestal e da construção civil, o que é fundamental para o pleno desenvolvimento da cadeia produtiva. E por fim, apesar de haverem diversos entraves a serem sobrepostos, a expectativa é de que os produtos industrializados em madeira tenham uma participação cada vez maior na construção civil brasileira nos próximos anos. / Over the last decade the debate about the rise of use of wood, specially in the construction sector, is growing because of two main reasons: the potential to stock CO2 and consequently to contribute to a low carbon economy and the development of industrialized technologies, predominantly those known as mass timber. Even though roughly 60% of the Brazilian territory is covered by forests and the potential of the forestry sector the use of wood as a construction material is incipient. Nevertheless in consonance with a global trend, there are evidences indicating the development of the timber construction industry in Brazil. This research aimed to characterise this trend through the identification of the main stakeholders, the initiatives to promote wood and the available products on the market. Also, matters related to obstacles, motivations and future perspectives were also analysed. It is important to highlight that the research focused on the private sector with the use of wood predominantly on buildings as structure and/or sealing. To accomplish it two methods were used: systemic mapping and study case. The systemic mapping consisted on both the research through the scientific literature and documents (i. e. catalogs, data available on websites) which identified 42 institutions, 66 companies, 24 different products among construction systems and components, and also 20 wood promotion actions (i. e. conferences, programs, media). Afterwards 22 stakeholders among companies and institutions were selected based on the relevance of their activities. Then semi-structured interviews were conducted to collect data about the difficulties, motivations and perspectives of the timber construction sector. As a result it was identified a rise on the quantity of companies, variety of products available on the market (specially engineered wood products) and wood promotions initiatives, particularly on the year of 2017. The study revealed that the development is not about the use of wood itself, but instead highly industrialized products. There is also the approximation between the forest and civil construction sector, which is essential for the full development of the production chain. Besides, despite the many obstacles found, it is expected for the next years a consistent growth of engineered wood products in Brazilian civil construction sector.
92

Techno-economic assessment of flexible demand

Good, Nicholas Paul January 2015 (has links)
Over recent years, political, technological, environmental and economic factors have combined to increase interest in distributed energy resources (DER), and flexibility in the power system. As a resource which is both distributed and flexible, flexible demand (FD) can be considered to be particularly of interest. However, due to many facets of its nature, understanding the available flexibility, and potential value of that flexibility, is difficult. Further, understanding the effects of FD exploitation on other multi-energy system actors, given the complex nature of modern liberalised energy systems, complicates the picture further. These factors form material obstructions to the assessment of FD, for example, for the construction of business cases. To address these gaps this thesis first assesses the nature and value of various applicable current and potential markets and charging/incentive regimes, before detailing a novel multi-energy domestic demand simulation model, capable of modelling, in detail, domestic FD resources. Subsequently, a multi-commodity stochastic energy/reserve optimisation model, capable of modelling various DERs and taking into account price signals related to various energy-related commodities and services (including user utility) is specified. The separation of price components for application at different aggregation levels, which is applied in the optimisation model, also informs the described value mapping methodology, which illustrates the impacts of any, particularly demand-side, intervention on the wider multi-energy system. The power of the above detailed contributions are demonstrated through various studies, which show the physical and economic impact of various demand side interventions and of greater market participation by FD resources.
93

Low carbon technologies in low voltage distribution networks : probabilistic assessment of impacts and solutions

Navarro Espinosa, Alejandro January 2015 (has links)
The main outcome of this research is the development of a Probabilistic Impact Assessment methodology to comprehensively understand the effects of low carbon technologies (LCTs) in low voltage (LV) distribution networks and the potential solutions available to increase their adoption. The adoption of LCTs by domestic customers is an alternative to decreasing carbon emissions. Given that these customers are connected to LV distribution networks, these assets are likely to face the first impacts of LCTs. Thus, to quantify these problems a Monte Carlo-based Probabilistic Impact Assessment methodology is proposed in this Thesis. This methodology embeds the uncertainties related to four LCTs (PV, EHPs, µCHP and EVs). Penetration levels as a percentage of houses with a particular LCT, ranging from 0 to 100% in steps of 10%, are investigated. Five minute time-series profiles and three-phase four-wire LV networks are adopted. Performance metrics related to voltage and congestion are computed for each of the 100 simulations per penetration level. Given the probabilistic nature of the approach, results can be used by decision makers to determine the occurrence of problems according to an acceptable probability of technical issues. To implement the proposed methodology, electrical models of real LV networks and high resolution profiles for loads and LCTs are also developed. Due to the historic passive nature of LV circuits, many Distribution Network Operators (DNOs) have no model for them. In most cases, the information is limited to Geographic Information Systems (GIS) typically produced for asset management purposes and sometimes with connectivity issues. Hence, this Thesis develops a methodology to transform GIS data into suitable computer-based models. In addition, thousands of residential load, PV, µCHP, EHP and EV profiles are created. These daily profiles have a resolution of five minutes. To understand the average behaviour of LCTs and their relationship with load profiles, the average peak demand is calculated for different numbers of loads with and without each LCT.The Probabilistic Impact Assessment methodology is applied over 25 UK LV networks (i.e., 128 feeders) for the four LCTs under analysis. Findings show that about half of the studied feeders are capable of having 100% of the houses with a given LCT. A regression analysis is carried out per LCT, to identify the relationships between the first occurrence of problems and key feeder parameters (length, number of customers, etc.). These results can be translated into lookup tables that can help DNOs produce preliminary and quick estimates of the LCT impacts on a particular feeder without performing detailed studies. To increase the adoption of LCTs in the feeders with problems, four solutions are investigated: feeder reinforcement, three-phase connection of LCTs, loop connection of LV feeders and implementation of OLTCs (on-load tap changers) in LV networks. All these solutions are embedded in the Probabilistic Impact Assessment. The technical and economic benefits of each of the solutions are quantified for the 25 networks implemented.
94

Vliv aktivity kyslíku, během tavby a odlévání, na metalurgickou jakost slitin železa / Influence of Oxygen Activity, during Melt and Casting, on Metallurgical Quality of Ferrous Alloys

Pecina, Vladimír January 2010 (has links)
Casting of test castings from low – carbon steel with different deoxidation degrees. Oxygen activity measurement in castings – from the temperatures over liquidus to solidification of metal. Analysis of chemical composition of inclusions. Calculation of thermodynamic equilibrium between oxygen activity and aluminium, silicon and manganese activities in unalloyed steel. Estimation of conditions for the course of carbon reactions in studied casting.
95

Hydrophobicity of Magnetite Coating on Low Carbon Steel

Akhtar, Mst Alpona 08 1900 (has links)
Superhydrophobic coatings (SHC) with excellent self-cleaning and corrosion resistance property is developed on magnetite coated AISI SAE 1020 steel by using a simple immersion method. Roughness measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), contact angle measurement (CAM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), and qualitative characterization of self-cleaning behavior, antifouling property and durability of the coatings are assessed. A water contact angle as high as 152o on the coated surface with excellent self-cleaning and resistivity to corrosion and good longevity in atmospheric air is obtained. Self-cleaning test results prove that these surfaces can find applications in large scale production of engineering materials. Potentiodynamic polarization tests and EIS tests confirm that the superhydrophobic low carbon steel surfaces have better resistance to corrosion compared to bare steel and magnetite coated steel in 3.5% NaCl solution. But the longevity of the coated steel surfaces in 3.5% salt solution is limited, which is revealed by the immersion durability test. However, hydrophobic coatings (HC) have better stability in normal tap water, and it can stay unharmed up to 15 days. Finally, hydrophobic coatings on low carbon steel surface retains hydrophobic in open atmosphere for more than two months. Results of this investigation show surface roughness is a critical factor in manufacturing hydrophobic steel surfaces. Higher contact angles are obtained for rougher and more uniform surfaces. A linear mathematical relationship (y =6x+104; R2 = 0.93) is obtained between contact angle (y) and surface roughness (x).
96

Analysis of the effects from the Mobility Orientation Law on geographical inequalities of mobility and low-carbon mobility in French low-density inter-municipalities / Analys av effekterna av lagen om mobilitetsorientering på geografiska ojämlikheter i fråga om rörlighet och rörlighet med låga koldioxidutsläpp i franska mellankommuner med låg befolkningstäthet

Pasquesoone, Martin January 2022 (has links)
The historical concentration of French mobility policies in urban areas has resulted into a high dependence of the private-car system in low density territories. Therefore, and especially in these areas, mobility is now threatened by a double constraint of carbon. This double constraint is due to the need to curb down green-house gases emissions as well as the expected decrease of oil production from European suppliers in the next decades. In order to face these issues, the Mobility Orientation Law (MOL) was promulgated in 2019 in France. Through a case study of Hauts-de-France low-density inter-municipalities,  this master thesis aims to analyse the effects of this law on geographical inequalities of mobility and on low-carbon mobility in low-density territories.  First, this study explores  the different levers brought by the MOL to these areas. From governance, planning, cooperation and financial evolutions to an analysis of the impulsion of mobility concerns in French low density inter-municipalities, this master thesis sheds light on first key elements raised by the law. Then, this study digs into the possible evolutions of the mobility policies in Hauts-de-France low-density inter-municipalities, based on the current situation in experienced territories. Depending on the polarity of the inter-municipalities, different scenarios of mobility policies evolutions are defined. This enables a better comprehension of the estimated effects from the law on geographical inequalities on mobility and on low-carbon mobility in low-density territories. In fact, the MOL brings necessary but insufficient conditions to the reduction of geographical inequalities and Green House Gazes emissions. / Rörligheten hotas i dag av en dubbel begränsning av karbon. Klimatförändringarna och oljetoppen tvingar oss att förändra våra mobilitetsvanor i grunden. Detta gäller särskilt i områden med låg befolkningstäthet där människor huvudsakligen använder privatbilar. I Frankrike infördes lagen om mobilitetsorientering 2019. Det är en bred lag som tar upp behovet av att utveckla mobilitetsalternativ i dessa områden. Ett viktigt inslag i denna lag är möjligheten att överföra kompetens om rörlighet till mellankommunal nivå.  Denna masteruppsats syftar till att undersöka om och hur lagen om mobilitetsorientering bidrar till att lösa geografiska ojämlikheter i fråga om rörlighet och främja utövandet av koldioxidsnål rörlighet i franska mellankommuner med låg befolkningstäthet. Den bygger huvudsakligen på en studie i Hauts-de-France. Vissa av resultaten kan dock överföras till andra regioner.   Ett frågeformulär skickades ut till 49 nya lokala aktörer inom mobilitet i Hauts-de-France-regionen. Dessa nya lokala aktörer är mellankommuner med låg befolkningstäthet. Vi fick 41 svar från dem. Vi intervjuade också 6 intressanta erfarna  mellankommuner från ett urval av 19 erfarna mellankommuner med låg befolkningstäthet som redan hade kompetens om rörlighet. Dessutom samlade vi in information om dessa mellankommuner med låg befolkningstäthet genom tillgänglig information på Internet och interna källor. Därefter byggde vi upp ett panorama över dessa områden.  Med utgångspunkt i detta panorama analyserade vi de olika åtgärder som lagen medför. Det finns fem huvudsakliga åtgärder som handlar om styrning, planering, samarbete, finansiering och medvetenhet. Lagen ger nya lokala intressenter i områden med låg befolkningstäthet större inflytande. Den ger nya planerings- och samverkansverktyg. Den ger otillräckliga finansiella verktyg men ökar definitivt medvetenheten om rörlighet.   Därefter föreslår vi perspektiv för utvecklingen av rörlighetspolitiken i mellankommuner med låg befolkningstäthet för att mer ingående analysera lagens möjliga effekter på geografiska ojämlikheter i fråga om rörlighet och rörlighet med låga koldioxidutsläpp. Vi definierar tre scenarier baserade på mellankommunens polaritet och på vår panorama.   På det hela taget skapar denna lag nödvändiga men otillräckliga förutsättningar för att möta det dubbla begränsning av karbon och de geografiska ojämlikheterna. Det är dock viktigt att understryka att det inte verkar vara möjligt att utveckla en hållbar rörlighet och samtidigt behålla samma samhälle. Rörlighet kan ses som en konsekvens av hur mänsklig verksamhet utvecklas i vårt samhälle. Eftersom miljöhänsyn kommer att tvinga mänsklig verksamhet att förändras kommer även den resulterande rörligheten att förandras. Denna lag är därför ett första bra steg mot en systemisk förändring.
97

Performance Evaluation of CBN Tools in High-Speed Dry Turning of AISI 1018 Low Carbon Steel

Zhang, Kan January 2019 (has links)
Increasing productivity is a constant demand for the manufacturing industry. Low-carbon-steel is one of the most commonly used ferrous materials in the part manufacturing market. Improving productivity as well as making the process eco-friendly by implementing a dry machining condition is the essential goal of this study. Built-up-edge (BUE) is often formed in the low-carbon-steel machining process, which, results in poor surface finish and short tool life. The high-speed-machining technique can be used to reduce the BUE formation and realize an increase in productivity. Cubic boron nitride (CBN) tools are most commonly used in hard turning and cast-iron machining at high cutting speeds. There are a limited number of studies regarding low-carbon-steel machining with CBN under a high-speed and with a dry machining condition. In this study, the investigation shows the preferable type of CBN tool and the wear mechanisms involved during finish turning operations of AISI 1018 under high speed and dry machining conditions. Test results show that a low CBN content with a TiCN binder and smaller grain size offers the best tool life and surface integrity of the final part. Currently manufacturers use coated carbide tools with a recommended cutting speed of 200-300m/min with coolant to complete the finishing process for turning low carbon steel parts. In this study, by implementing CBN tools under the dry condition at 500 m/min cutting speed (speed was selected from the preliminary test performed using the uncoated CBN from 500 to 1200 m/min), the buildup edge formation has been reduced, tool life was measured to increase by 307% compared to the benchmark tool (Coated Carbide), and surface finish was measured in the range of 0.8-1.6μm Ra. / Thesis / Master of Applied Science (MASc)
98

Contributions towards closing the intention-behavior gap in residential low-carbon technology adoption decisions

Vogt, Emily Christine 29 July 2024 (has links)
Against the background of an aspired zero emission economy, residential decision making concerning low-carbon technologies (LCTs) has been researched widely to develop appropriate policy measures to foster adoption levels, however, adoption levels remain unexpectedly low. First, prevalent knowledge gaps are caused by the lacking accumulation of knowledge in the research domain, and second, the lacking common understanding of the decision process itself. Third, previous research has not sufficiently accounted for heterogeneity in the population, instead assuming similar drivers and barriers for adoption across consumer segments. Based on an extended Theory of Planned Behavior and previous research findings, a holistic decision framework for residential decision-making concerning LCTs is proposed in this doctoral thesis. A reduced framework could be confirmed for the example technology rooftop PV with a high-quality sample (n=1,800) using Partial Least Squares Structural Equation Modelling. It could be shown, that adoption intention and strength and influence of predictors vary across consumer segments, even between segments with the same broad social status and/or comparable values. Matching survey data with real-world data revealed, that stated adoption intentions of consumer segments are consistent with adoption behavior in Saxonian zip-codes only for two of five consumer segments. Moreover, it could be demonstrated that common variables used to explain adoption intentions (environmental concern and novelty seeking) are not related with adoption levels in Saxonian zip-codes. Similarly, common variables to explain adoption levels in zip-codes (city-type, share of (semi-) detached houses, population density, previous PV installations) are not related with adoption intentions among consumer segments. These results show that taking consumer heterogeneity into account is crucial to understanding drivers and barriers of residential adoption decisions, and that variables relating to intentions and actual behavior are not necessarily equivalent, providing initial insights into why political measures might not have been sufficiently successful yet.:Abstract iii Zusammenfassung v Publications ix Acknowledgments xi 1 Introductory Remarks 1 2 Residential low-carbon technology decision-making 23 3 Residential PV adoption intention 37 4 The decision towards a residential PV system 63 5 Heterogeneity in PV adoption intentions across consumer segments 83 6 Spatial and household characteristics relating to PV saturation 103 7 Spatial and household characteristics relating to PV adoption intention 121 Statement of Contribution xv Curriculum Vitae xvii Declaration of Authorship xix Bibliographic Description xxi
99

Integrated high-resolution modelling of domestic electricity demand and low voltage electricity distribution networks

Richardson, Ian January 2011 (has links)
Assessing the impact of domestic low-carbon technologies on the electricity distribution network requires a detailed insight into the operation of networks and the power demands of consumers. When used on a wide-scale, low-carbon technologies, including domestic scale micro-generation, heat pumps, electric vehicles and flexible demand, will change the nature of domestic electricity use. In providing a basis for the quantification of the impact upon distribution networks, this thesis details the construction and use of a high-resolution integrated model that simulates both existing domestic electricity use and low voltage distribution networks. Electricity demand is modelled at the level of individual household appliances and is based upon surveyed occupant time-use data. This approach results in a simulation that exhibits realistic time-variant demand characteristics, in both individual dwellings, as well as, groups of dwellings together. Validation is performed against real domestic electricity use data, measured for this purpose, from dwellings in Loughborough in the East Midlands, UK. The low voltage distribution network is modelled using real network data, and the output of its simulation is validated against measured network voltages and power demands. The integrated model provides a highly detailed insight into the operation of networks at a one-minute resolution. This integrated model is the main output of this research, alongside published articles and a freely downloadable software implementation of the demand model.
100

A framework for modelling embodied product energy to support energy efficient manufacturing

Seow, Yingying January 2011 (has links)
This thesis reports on the research undertaken to minimise energy consumption within the production phase of a product lifecycle through modelling, monitoring and improved control of energy use within manufacturing facilities. The principle objective of this research is to develop a framework which integrates energy data at plant and process levels within a manufacturing system so as to establish how much energy is required to manufacture a unit product. The research contributions are divided into four major parts. The first reviews relevant literature in energy trends, related governmental policies, and energy tools and software. The second introduces an Embodied Product Energy framework which categorises energy consumption within a production facility into direct and indirect energy required to manufacture a product. The third describes the design and implementation of a simulation model based on this framework to support manufacturing and design decisions for improved energy efficiency through the use of what-if scenario planning. The final part outlines the utilisation of this energy simulation model to support a Design for Energy Minimisation methodology which incorporates energy considerations within the design process. The applicability of the research concepts have been demonstrated via two case studies. The detailed analysis of energy consumption from a product viewpoint provides greater insight into inefficiencies of processes and associated supporting activities, thereby highlighting opportunities for optimisation of energy consumption via operational or design improvements. Although the research domain for this thesis is limited to the production phase, the flexibility offered by the energy modelling framework and associated simulation tool allow for their employment other product lifecycle phases. In summary, the research has concluded that investment in green sources of power generation alone is insufficient to deal with the rapid rise in energy demand, and has highlighted the paramount importance of energy rationalisation and optimisation within the manufacturing industry.

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