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Stephenson, Anna Louise. "The sustainability of first- and second-generation biofuels using life cycle analysis." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608636.
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Atubi, Phylander Omosigho. "Novel synthesis of silica-supported Fischer-Tropsch catalysts for second generation biofuels." Thesis, University of Huddersfield, 2015. http://eprints.hud.ac.uk/id/eprint/26187/.
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The objective of this study is to improve the catalytic performance of silica-supported Fischer-Tropsch cobalt based catalyst. Iron and nickel catalyst were also briefly studied. Initial work focused on synthesis of porous silica via oxidative thermal decomposition of polydimethylsiloxane (PDMS) and its characterisation. It was shown that PDMS undergoes at least two thermal degradation steps to form silica powder. It was also demonstrated that increase in isothermal time at constant temperature and increase in temperature at constant time could be used to tune the surface area and pore volume of the synthesized silica powder. Subsequently, a novel one pot technique called the swelling in method (SIM) was developed, and employed to synthesize silica-supported cobalt, iron and nickel based Fischer-Tropsch catalyst. The results of silica-supported cobalt based catalyst prepared by the swelling in method were compared with those synthesized by incipient wet impregnation method. The colloidal method was also combined with the swelling in method to prepare silica-supported cobalt nanoparticles catalyst. Characterisation of cobalt, iron and nickel based catalyst prepared by the swelling in method showed that PDMS as the initial catalyst support converted to silica powder after oxidative calcination. Physicochemical properties of silica-supported cobalt, iron and nickel catalyst prepared by the swelling in method suggest that the oxides of each metal were present inside the silica pores while cobalt based catalyst prepared by the same method had better surface area and pore volume compared to the catalyst synthesized by the incipient wetness impregnation technique. Catalytic performance of the catalyst synthesized by the swelling in and incipient wetness methods were studied in High Temperature Fischer-Tropsch synthesis reaction condition. The results showed that silica-supported cobalt based catalyst prepared by the swelling in method was overall more active, generated less methane and less susceptible to deactivation by sintering and carbon deposition when compared to the catalyst prepared by the impregnation technique. Silica-supported cobalt nanoparticles catalyst had the best catalytic activity in comparison to all the catalyst studied in this work. Silica-supported cobalt based catalyst prepared by the swelling in method using cobalt nitrate exhibited the best catalytic activity while the catalyst synthesized from cobalt acetate had the least activity. The addition of ruthenium to silica-supported cobalt catalyst contributed in minimising the formation of methane when compared to the catalyst without ruthenium. Silica-supported iron and nickel based catalyst showed reasonable catalytic activity, and as expected the amount of methane generated by nickel catalyst was relatively very high compared to all the catalyst studied in this thesis.
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Dimitriou, Ioanna. "Techno-economic assessment and uncertainty analysis of thermochemical processes for second generation biofuels." Thesis, Aston University, 2013. http://publications.aston.ac.uk/19315/.
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Biomass-To-Liquid (BTL) is one of the most promising low carbon processes available to support the expanding transportation sector. This multi-step process produces hydrocarbon fuels from biomass, the so-called “second generation biofuels” that, unlike first generation biofuels, have the ability to make use of a wider range of biomass feedstock than just plant oils and sugar/starch components. A BTL process based on gasification has yet to be commercialized. This work focuses on the techno-economic feasibility of nine BTL plants. The scope was limited to hydrocarbon products as these can be readily incorporated and integrated into conventional markets and supply chains. The evaluated BTL systems were based on pressurised oxygen gasification of wood biomass or bio-oil and they were characterised by different fuel synthesis processes including: Fischer-Tropsch synthesis, the Methanol to Gasoline (MTG) process and the Topsoe Integrated Gasoline (TIGAS) synthesis. This was the first time that these three fuel synthesis technologies were compared in a single, consistent evaluation. The selected process concepts were modelled using the process simulation software IPSEpro to determine mass balances, energy balances and product distributions. For each BTL concept, a cost model was developed in MS Excel to estimate capital, operating and production costs. An uncertainty analysis based on the Monte Carlo statistical method, was also carried out to examine how the uncertainty in the input parameters of the cost model could affect the output (i.e. production cost) of the model. This was the first time that an uncertainty analysis was included in a published techno-economic assessment study of BTL systems. It was found that bio-oil gasification cannot currently compete with solid biomass gasification due to the lower efficiencies and higher costs associated with the additional thermal conversion step of fast pyrolysis. Fischer-Tropsch synthesis was the most promising fuel synthesis technology for commercial production of liquid hydrocarbon fuels since it achieved higher efficiencies and lower costs than TIGAS and MTG. None of the BTL systems were competitive with conventional fossil fuel plants. However, if government tax take was reduced by approximately 33% or a subsidy of £55/t dry biomass was available, transport biofuels could be competitive with conventional fuels. Large scale biofuel production may be possible in the long term through subsidies, fuels price rises and legislation.
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Pryor, Owen. "Ignition Studies of Diisopropyl Ketone, A Second-Generation Biofuel." Honors in the Major Thesis, University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1637.
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This thesis focuses on ignition of diisopropyl ketone (DIPK), a new biofuel candidate that is produced by endophytic conversion. The ignition delay times behind reflected shockwaves were modeled in a high-pressure shock tube. The ignition delay times were compared to other biofuels and gasoline surrogates. Parametric studies of the ignition delay experiments were performed between 1-10 atm and 900 -1200K. An OH optical sensor was developed in conjunction for the ignition delay experiments. The OH optical sensor uses a microwave discharge lamp to generate light at 308 nm that will then be shined through the combustion reaction. Using Beer-Lambert law the concentration of OH can be obtained during ignition and oxidation of hydrocarbon fuels in a shock tube. DIPK ignition delay time experiments are planned in two shock tubes (located at UCF and UF) to provide ignition and OH time-histories data for model validation.B.S.A.E.
Bachelors
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering
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Magnusson, Mimmi. "Energy systems studied of biogas : Generation aspects of renewable vehicle fuels in the transport system." Doctoral thesis, KTH, Energiprocesser, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105120.
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The transport sector is seen as particularly problematic when concerns about climate change and dependency on fossil energy are discussed. Because of this, bioenergy is strongly promoted for use in the transport sector, both on a European level and nationally in Sweden. Even though bioenergy is considered one of the key solutions, it is generally agreed that both supply- and demand-side measures will be needed to achieve a change to a more sustainable transport system. One of the reasons for this is the limited availability of biomass, especially agricultural feedstocks competing with food or feed production. Woody biomass, however more abundant, is also exposed to tough competition from other sectors. In this thesis, the role of biogas as a vehicle fuel in a future sustainable transport system is discussed together with the prerequisites needed to realise such a transport system. Biogas is a biofuel that could be produced in several different ways: by anaerobic digestion, which is a first-generation production route, by gasification, which is a second-generation process, and by catalytic reduction of carbon dioxide, a third-generation technology. The main focus in this thesis is on biogas produced by anaerobic digestion and the results show that there is a significant potential for an increase compared to today’s production. Biogas from anaerobic digestion, however, will only be able to cover a minor part of the demand in the Swedish transport sector. Considering biogas of the second and third generations, the potential for production is more uncertain in a mid-term future, mainly due to competition for feedstock, the possibility to produce other fuels by these processes, and the present immaturity of the technology. The limited potential for replacing fossil vehicle fuels, either by biogas or other renewable fuels, clearly shows the need for demand-side measures in the transport system as well. This thesis shows the importance of technical and non-technical means to decrease the demand for transport and to make the transport as efficient as possible. The results show that both energy-efficient vehicles and behavioural and infrastructural changes will be required. Policies and economic incentives set by governments and decision-making bodies have a prominent role to play, in order to bring about a shift to a more sustainable transport system, however, measures taken on individual level will also have a great impact to contribute to a more sustainable transport system.QC 20121116
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Wu, Yi. "Experimental investigation of laminar flame speeds of kerosene fuel and second generation biofuels in elevated conditions of pressure and preheat temperature." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0011/document.
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La vitesse de flamme laminaire représente une grandeur physique clé à mesurer car elle permet d'obtenir des données fondamentales sur la réactivité, la diffusivité et l'exothermicité du carburant. Elle est également un des paramètres utilisés pour le développement et la validation des mécanismes réactionnels détaillés ainsi que pour la modélisation de la combustion turbulente. Bien que cette grandeur physique ait fait l'objet de nombreuses études expérimentales depuis plusieurs décennies, sa méconnaissance sur des carburants multi-composant dans des conditions haute-pression et haute-température similaires à celles existantes dans les chambres de combustion reste un sujet d'actualité pour les industriels des secteurs automobile et aéronautique. Au cours de cette thèse, un brûleur de configuration bec Bunsen fonctionnant avec un prémélange gazeux combustible/air a été conçu pour produire une flamme laminaire à pression élevée tout en permettant la mesure par voie optique de la vitesse de flamme laminaire de carburants multi-composant (kérosène, biocarburants de seconde génération...). La mesure est basée sur la détection du contour de flamme par diverses diagnostics optiques comme la chimiluminescence OH*, la PLIF-OH et la PLIF-acétone/aromatique. En premier lieu, les mélanges de carburants purs gazeux (CH4) ou liquide (acétone) avec de l'air ont été étudiés pour valider le brûleur expérimental et la méthodologie de mesure de la vitesse de flamme laminaire par voie optique. Les évolutions de la vitesse de flamme laminaire pour des carburants de type kérosène (composants purs, surrogate LUCHE et Jet A-1) en fonction de la pression, température de préchauffage et richesse ont été ensuite étudiées et comparées avec des simulations numériques utilisant un mécanisme réactionnel détaillé. La dernière partie de la thèse est consacrée à l'étude de l'influence des composés oxygénés présents dans un biocarburant de seconde génération de type d'essence sur la vitesse de flamme laminaire. Après avoir mesuré la vitesse de flamme laminaire de différentes molécules oxygénées, les effets d'addition de ces composés oxygénés dans le carburant ont été quantifiésLaminar flame speed is one of the key parameters for understanding reactivity, diffusivity and exothermicity of fuels. It is also useful to validate both the kinetic chemical mechanisms as well as turbulent models. Although laminar flame speeds of many types of fuels have been investigated over many decades using various combustion methodologies, accurate measurements of laminar flame speeds of multicomponent liquid fuels in high-pressure and high-temperature conditions similar to the operating conditions encountered in aircraft/automobile combustion engines are still required. In this current study, a high-pressure combustion chamber was specifically developed to measure the laminar flame speed of multicomponent liquid fuels such as kerosene and second generation of biofuels. The architecture of the burner is based on a preheated premixed Bunsen flame burner operated in elevated pressure and temperature conditions. The optical diagnostics used to measure the laminar flame speed are based on the detection of the flame contour by using OH* chemiluminescence, OH- and acetone/aromatic- Planar laser induced fluorescence (PLIF). The laminar flame speed of gaseous CH4/air and acetone/air premixed laminar flames were first measured for validating the experimental setup and the measurement methodologies. Then, the laminar flame speeds of kerosene or surrogate fuels (neat kerosene compounds, LUCHE surrogate kerosene and Jet A-1) were investigated and compared with simulation results using detailed kinetic mechanisms over a large range of conditions including pressure, temperature and equivalence ratio. The last part of the thesis was devoted to study the effect of oxygenated compounds contained in the second generation of biofuels on the laminar flame speeds. After measuring the laminar flame speeds of various oxygenated components present in partially hydro-processed lignocellulosic biomass pyrolysis oils, the effect of these oxygenates on the flame speeds of these fuels were quantitatively investigated
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Wetterlund, Elisabeth. "System studies of forest-based biomass gasification." Doctoral thesis, Linköpings universitet, Energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-74576.
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Bioenergy will play an important role in reaching the EU targets for renewable energy. Sweden, with abundant forest resources and a well-established forest industry, has a key position regarding modern biomass use. Biomass gasification (BMG) offers several advantages compared to biomass combustion-based processes, the most prominent being the possibility for downstream conversion to motor fuels (biofuels), and the potential for higher electrical efficiency if used for electricity generation in a biomass integrated gasification combined cycle (BIGCC). BMG-based processes in general have a considerable surplus of heat, which facilitates integration with district heating or industrial processes. In this thesis integration of large-scale BMG, for biofuel or electricity production, with other parts of the energy system is analysed. Focus is on forest-based biomass, with the analysis including techno-economic aspects as well as considerations regarding effects on global fossil CO2 emissions. The analysis has been done using two approaches – bottom-up with detailed case studies of BMG integrated with local systems, and top-down with BMG studied on a European scale. The results show that BMG-based biofuel or electricity production can constitute economically interesting alternatives for integration with district heating or pulp and paper production. However, due to uncertainties concerning future energy market conditions and due to the large capital commitment of investment in BMG technology, forceful economic support policies will be needed if BMG is a desired route for the future energy system, unless oil and electricity prices are high enough to provide sufficient incentives for BMG-based biofuel or electricity production. While BMG-based biofuel production could make integration with either district heating or pulp and paper production economically attractive, BIGCC shows considerably more promise if integrated with pulp and paper production than with district heating. Bioenergy use is often considered CO2-neutral, because uptake in growing plants is assumed to fully balance the CO2 released when the biomass is combusted. As one of the alternatives in this thesis, biomass is viewed as limited. This means that increased use of bioenergy in one part of the energy system limits the amount of biomass available for other applications, thus increasing the CO2 emissions for those applications. The results show that when such marginal effects of increased biomass use are acknowledged, the CO2 mitigation potential for BMG-based biofuel production becomes highly uncertain. In fact, most of the BMG-based biofuel cases studied in this thesis would lead to an increase rather than the desired decrease of global CO2 emissions, when considering biomass as limited.Bioenergi spelar en viktig roll för att nå EU:s mål för förnybar energi. Sverige har med sina goda skogstillgångar och sin väletablerade skogsindustri en nyckelposition vad gäller modern bioenergianvändning. Förgasning av biomassa har flera fördelar jämfört med förbränningsbaserade processer - i synnerhet möjligheten att konvertera lågvärdiga råvaror till exempelvis fordonsdrivmedel. Används gasen istället för elproduktion kan en högre verkningsgrad nås om gasen används i en kombicykel, jämfört med i en konventionell ångturbincykel. De förgasningsbaserade processerna har i allmänhet ett betydande överskott av värme, vilket möjliggör integrering med fjärrvärmesystem eller industriella processer. I denna avhandling analyseras integrering av storskalig biomassaförgasning för drivmedelseller elproduktion, med andra delar av energisystemet. Skogsbaserad biomassa är i fokus och analysen behandlar såväl teknoekonomiska aspekter, som effekter på globala fossila CO2-utsläpp. Forskningen har gjorts på två olika systemnivåer - dels i form av detaljerade fallstudier av biomassaförgasning integrerat med lokala svenska system, dels i form av systemstudier på europeisk nivå. Resultaten visar att förgasningsbaserad biodrivmedels- eller elproduktion kan komma att utgöra ekonomiskt intressanta alternativ för integrering med fjärrvärme eller massa- och papperstillverkning. På grund av osäkerheter i fråga om framtida energimarknadsförhållanden och på grund av de höga kapitalkostnaderna som investering i förgasningsanläggningar innebär, kommer kraftfulla ekonomiska styrmedel krävas om biomassaförgasning är en önskad utvecklingsväg för framtidens energisystem, såvida inte olje- och elpriserna är höga nog att i sig skapa tillräckliga incitament. Medan förgasningsbaserad drivmedelsproduktion kan vara ekonomiskt attraktivt att integrera med såväl fjärrvärme som med massa- och papperstillverkning, framstår förgasningsbaserad elproduktion som betydligt mer lovande vid integrering med massa- och papperstillverkning. Användning av bioenergi anses ofta vara CO2-neutralt, eftersom upptaget av CO2 i växande biomassa antas balansera den CO2 som frigörs när biomassan förbränns. Som ett av alternativen i denna avhandling ses biomassa som begränsad, vilket innebär att ökad användning av bioenergi i en del av energisystemet begränsar den tillgängliga mängden biomassa för andra användare, vilket leder till ökade CO2-utsläpp för dessa. Resultaten visar att när hänsyn tas till denna typ av marginella effekter av ökad biomassaanvändning, blir potentialen för minskade globala CO2-utsläpp med hjälp av förgasningsbaserade tillämpningar mycket osäker. I själva verket skulle de flesta av de förgasningsbaserade drivmedel som studerats i denna avhandling leda till en utsläppsökning, snarare än den önskade minskningen.
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Skalický, Michal. "Druhá generace biopaliv v reálném světě." Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-15649.
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The diploma thesis deals with the problematics of biofuels as a renewable source of energy in transportation, which has recently gotten under social spotlight. The theoretical part is focused on an explanation of basic terminology, historical development and especially reasons for the need to replace current fosil fuels with respect to an increasing volume of CO2 and shortening oil reserves. The practical part compares characteristics, use, pros and cons of the biofuels of the first and second generation and tries to estimate benefits of the biofuels of the second generation in both economic and environmental area.
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Gibon, Thomas. "Environmental Input-Output Assessment of Integrated Second Generation Biofuel Production in Fenno-Scandinavia." Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9066.
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The goal of this study is to investigate the potential implementation of integrated dimethyl ether (DME) production from by-products of the pulp and paper industry in Fenno-Scandinavia (Finland, Norway and Sweden) and to quantify the consequences of several use scenarios in which fossil fuels were gradually substituted by DME. To that end, two analytical frameworks were jointly used, life cycle assessment (LCA) and environmentally-extended input-output analysis (EEIOA). The first framework was utilised to make an exhaustive inventory of the Chemrec process and its integration in the Finnish, Norwegian and Swedish contexts. The latter framework was employed in order to incorporate this production system into a multi-regional input-output model that has been created for the purpose of the study. For data availability reasons, the stressors that have been examined are anthropogenic carbon dioxide, methane and dinitrogen monoxide, widely regarded as the elements which are responsible for the most serious environmental impacts. Three different story lines (plus a baseline scenario) were taken into account: a resource assessment scenario, in which a total implementation is assumed; a policy-independent approach setting a constant increase in the use of biofuels and a policy-compliance approach, aiming at satisfying European directive goals. It results that 5.21 to 20.6 Mt of DME can be produced, while the range of greenhouse gases emissions that can be saved thanks to a black liquor-based DME production scheme goes from 46.7 (scenario 3) to 70.5 (scenario 2) Mt in 2050, that is, 8.1512.8% out of the otherwise total emissions in Fenno-Scandinavia. This LCA/IO analysis emphasises that the amount of greenhouse gases emissions embodied in every kg of DME highly depends on each country's background economy and evolves considerably along the decade, unit-level analysis show drastic reductions (-15% to -57% between 2000 and 2050) in DME embodied emissions. A nationwide analysis highlights a very important potential from the Finnish pulp and paper industry. All in all, it shows that such a biofuel production scheme should be implemented in countries that have an remarkable environmental profile to obtain very significant environmental performances. Only a joint effort of all the key sectors (energy, transportation, households) can lead to climate change mitigation and energy security.
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Samuel, Victor. "Environmental and socioeconomic assessment of rice straw conversion to ethanol in Indonesia : The case of Bali." Thesis, KTH, Energi och klimatstudier, ECS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127807.
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The vast rice production in some developing Asian countries like Indonesia raises expectation on poverty alleviation and energy diversification through second generation biofuel production from rice residues, specifically rice straw. This work attempts to estimate the potential environmental and socioeconomic benefits of rice straw-to-ethanol project in Indonesia. Literature research and interviews are performed to quantify several environmental and socioeconomic indicators that are considered as the major concerns inimplementing an energy project. Assuming all the technically available rice straw in Bali is used (~244-415 kilotonne/year), ethanol production may yield gasoline replacement, lifecycle GHG savings, GDP contribution, foreign exchange savings, and employment beneficiaries of 55-93 ML/year, 140-240 millionUSD/year, 19-32 kilotonne of CO2-equivalent/year, 100-180 million USD/year, and 2,200-3,700 persons, respectively. Sensitivity analyses are done for some parameters, showing that ethanol yield, total capital cost, feed-in-tariff for electricity, and imported crude oil price are the major factors affecting the viability of rice straw-to-ethanol project in Indonesia.Harnessing agricultural feedstock and residues for bioethanol production - towards a sustainable biofuel strategy in Indonesia
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Duarte, Aires. "Dimensionamento de plantas Biomass-to-Liquids para produção de óleo diesel sintético no Brasil." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-26022014-101501/.
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Há uma demanda global pelo abastecimento de combustíveis veiculares menos poluentes, tanto por questões energéticas quanto sócio-ambientais. Uma potencial alternativa, que traduz a possibilidade de um biocombustível sem as limitações da Primeira Geração, é a rota tecnológica conhecida como Biomass-to-Liquids (BTL) que, através da gaseificação e da síntese Fischer-Tropsch, possibilita a obtenção de biocombustíveis líquidos, como o óleo diesel sintético, provenientes da biomassa moderna, nesse estudo, a biomassa lignocelulósica. Para a produção em escala comercial de um biocombustível da Segunda Geração, um complexo planejamento e altos investimentos são demandados dado seu pioneirismo e ausência de histórico de mercado ou modelos precisos. Uma metodologia desenvolvida em 2006 pelo pesquisador Harold Boerrigter propõe o dimensionamento ideal de uma planta BTL a partir de uma planta Gas-to-Liquids (GTL); são aqui propostas correções e atualizações para esta metodologia, sugerindo-se uma curva capaz de apontar a influência da economia de escala em plantas BTL e uma fórmula para o cálculo estimado do Total Capital Investment (TCI) destas plantas até o momento o Brasil não dispõe de nenhuma planta que opere pela rota BTL. Segue-se com considerações sobre a oferta de resíduos florestais no território brasileiro e a constatação de que a mesma seria insuficiente como matéria-prima para sustentar grandes plantas BTL, fazendo-se necessário o emprego de culturas planejadas na forma de florestas energéticas. Uma vez feita tal análise, apresenta-se o histórico, desde sua concepção até o seu fechamento, da primeira planta a operar pela rota BTL e a produzir o designer fuel batizado de SunDiesel®: construída na Alemanha, a CHOREN Industritechnik contribui com sua experiência de anos e também com a tecnologia de gaseificação Carbo-V® para as pesquisas com os biocombustíveis sintéticos. Seu exemplo pode sinalizar um alerta com relação ao dispêndio de esforços em projetos desta natureza dadas as incertezas econômicas que circundam as fronteiras tecnológicas dos combustíveis da Segunda Geração.There is a global demand for the supply of less polluting vehicular fuels as much by energy issues as socio-environmental. A potential alternative meaning the possibility of a biofuel without the limitations from the First Generation is the technological route known as Biomass-to-Liquids (BTL) which via gasification and the Fischer-Tropsch synthesis turns possible to obtain liquid biofuels such synthetic diesel oil from modern biomass, in this study, the lignocellulosic biomass. For commercial-scale production of a Second Generation biofuel, a complex planning and high investments are required given its pioneering and absence of market history or precise models. A methodology developed in 2006 by researcher Harold Boerrigter proposes the ideal sizing for a BTL plant assuming a Gas-to-Liquids (GTL) plant; here are proposed corrections and updates for this methodology, suggesting a curve able to point the influence of economy of scale in BTL plants and a formula for the calculation of an estimated Total Capital Investment (TCI) of these plants by the present time Brazil has no plant operating by BTL route. The research follows up with issues regarding forest residues provision in the Brazilian territory and conlcuding that the same would be insufficient as a raw material to sustain large BTL plants, making necessary the use of planned crops in the form of energy forests. Once made such analysis, it is presented the history since its beginning until its closing for the first plant to operate by the BTL route and to produce the designer fuel called SunDiesel®: built in Germany, the CHOREN Industritechnik contributes with its experience of years and also with the gasification technology Carbo-V® for researches with synthetic biofuels. Such example may indicates an alert regarding the expenditure of efforts on projects of this nature, given the economic uncertainties that surround the Second Generation fuels technological frontiers.
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Omran, Abdelnasir. "Sustainable biofuels for electricity generation in Sudan." Thesis, Aston University, 2018. http://publications.aston.ac.uk/33430/.
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Sudan was separated into two countries in July 2011. Before this Sudan was the most significant country in Africa with a total area of around one million square miles. Due to the separation, Sudan lost about 75% of the fossil fuels resources and currently facing a very severe economic crisis. As a result of this, the government had to abolish the fossil fuels subsidies which used to cost about 15% of the total expenditure of the country. Only about 30% peoples connected to grid electricity. Sourcing fossil fuels alternatives are crucial to meet the growing energy demand, political stability, and growth of the country. This study aims to investigate the feasibility of using locally available renewable biofuels for small-scale electricity generation and implementation in Sudan. A combined qualitative and quantitative methodological approach was used to study the potential of seed based small or community-scale energy production in Sudan to resolve the severe fuel shortage after secession. Estimation of various types of available biofuels was carried out. There is around two million ton of Jatropha biofuel that will be available in 2019; around four thousands ton of cottonseed biofuel and two thousands ton of castor biofuels available annually. In this investigation, 23 types of neat biofuels and blends were prepared using ethanol, butanol, and fossil diesel. Physicochemical properties of all neat biofuels and blends were measured and compared with standard fossil diesel. Heating values of Jatropha, Cottonseed, and Castor biofuels were 39.18, 39.74 and 37.71 MJ/Kg respectively. Neat biofuels and blends were tested in an unmodified 2-cylinder diesel engine. Engine performance and emission characteristics were conducted and compared with standard fossil diesel results. Jatropha, Cottonseed, Castor biofuels were blended separately with 20% butanol and 20% fossil diesel. The neat biofuels and blends were tested successfully in a 7.4 kW indirect injection two-cylinder engine. Jatropha biofuel and its blends showed 7% higher brake thermal efficiency than fossil diesel at maximum load. For Cottonseed biofuel and its blends, Castor biofuel and its blends were 6.7%, 8% higher, respectively. Jatropha biofuel blends with 20% fossil diesel and neat Jatropha oil showed 53%, and 18% high CO and CO2, respectively; while both samples showed a smoke reduction of 96%. NOX emission for neat Jatropha and its blends showed a decrease in the range 5 – 13%. Cottonseed oil and its blends showed NOX emission decrease in the range 5 – 7%. Castor oil blends have demonstrated the highest NOX emission reduction among all tested samples with 24%. Smoke production reduction of Cottonseed oil and its blends were in the range 62 – 91%. Castor oil blends with 20% butanol showed 24% NOX emission reduction, while its blends with 20% fossil diesel showed 10% reduction. Both samples of Castor oil blends showed smoke production cuts; blends with 20% butanol showed a decrease in the range 59 – 62%, while blends with 20% fossil diesel showed 61% reduction. The study concludes by this short-term engine testing that this Compression Ignition engine type can be efficiently operated with 20% butanol blend with any of the three non-edible biofuels, Jatropha, Cottonseed and Castor, without any modification. Sudan has the potential of increasing the production of biofuels from these three plant and butanol can be produced locally to minimise the cost of fossil diesel import. The reduction of NOX emission and smoke production could help Sudan reach its Green House Gas reduction target.
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Zhang, Jihong. "Second generation imidazotetrazinones." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546604.
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Nee, Phillip Tsefung. "Generation of squeezed light via second harmonic generation." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34050.
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Rust, A. N. "A second generation SUNSAT RAMDISK." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51620.
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Thesis (MEng)--Stellenbosch University, 2000.ENGLISH ABSTRACT: The SUNSAT RAMDISK was studied, and tests performed to assess its flight readiness. Errors were detected, and modifications had to be made to ensure proper operation. SUNSAT was subsequently launched, and to date the RAMDISK is still functioning correctly. The flight readiness testing of the RAMDISK was considered a pre-study to designing a second generation RAMDISK. A conceptual mass memory storage device support structure was designed. This second generation RAMDISK, or memory drive is intended to be used on a second generation SUNSAT, or SUNSAT 2. The design is targeted for implementation in fields programmable gate arrays (FPGA's) and was realised using VHDL. This hardware description language is an accepted standard, and can be implemented in a number of different programmable logic devices; both SRAM and fuse-link based. Simulations were performed to verity the functionality of the design, and to determine whether the data transfer specifications could be met using programmable logic devices. A modular design methodology was followed. The memory drive was designed so that any type and amount of memory can be added to the drive without a major design change. The simulations indicated that a data capturing speed of 130 Mbits/s could be maintained.
AFRIKAANSE OPSOMMING: Die SUNSAT massa geheue module is bestudeer, en toetse is daarop uigevoer om die vlug gereedheid te bepaal. Foute is gevind, en veranderinge moes aangebring word om korrekte werking te verseker. SUNSAT is gelanseer en die geheue module werk tot op datum nog korrek. Die geheue module se vlug gereedheid toetse is beskou as In voor studie vir die ontwerp van In tweede generasie geheue module. In Konseptueie massa stoor toestel struktuur is ontwerp. Hierdie tweede generasie geheue module, of geheue skyf is bedoel om op In tweede generasie SUNSAT, of SUNSAT 2 gebruik te word. FPGA's is die teiken tegnologie vir hierdie ontwerp en VHDL is gebruik om die ontwerp te realiseer. Hierdie hardeware beskrywingstaal word as In standaard aanvaar en kan in verskillende herprogrammeerbare tegnologieë gebruik word. Sirnulasies is gedoen om die funksionaliteit van die ontwerp te verifieer, en om te bepaal of die nodige data oordragstempo gehandhaaf kan word met herprogrammeerbare tegnologie. In Modulêre ontwerpsfilosofie is gevolg. Die geheue skyf is ontwerp sodat dit enige tipe en hoeveelheid geheue kan ondersteun sonder om groot veranderinge aan die ontwerp te doen. Die sirnulasies toon dat In data oordragstempo van 130 Mbits/s gehandhaafkan word.
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Pityana, Sisa Lesley. "Second harmonic generation in waveguides." Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239511.
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Do, Phi Minh. "Metabolic engineering of microbial biocatalysts for fermentative production of next generation biofuels." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024891.
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Calvo, D., and Bert-Wolfgang Schulze. "Edge symbolic structures of second generation." Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2009/2994/.
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Operators on a manifold with (geometric) singularities are degenerate in a natural way. They have a principal symbolic structure with contributions from the
different strata of the configuration. We study the calculus of such operators on the level of edge symbols of second generation, based on specific quantizations of the corner-degenerate interior symbols, and show that this structure is preserved under compositions.
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Trull, Silvestre José Francisco. "Second Harmonic Generation in Photonic Crystals." Doctoral thesis, Universitat Politècnica de Catalunya, 1999. http://hdl.handle.net/10803/6618.
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Photonic crystals emerged at the end of the last decade as a new frame to control the interaction between radiation and matter. The potential advances that such structures could report in photonics technology has lead to an increasing research focused on the implementation of photonic crystals possessing full photonic band gaps, hindering the fact that more simple structures, possessing band gaps in selected directions of space, may also provide strong control of the electromagnetic radiation leading to the observation of many new interesting phenomena. In fact, the scope of this control is not limited to a linear interaction and can be extended to nonlinear interactions of any order. In this work we present a study of the second order nonlinear interaction from nonlinear organic molecules placed within two different types of photonic crystals. First, we will discuss the enhancement and inhibition of the radiation at the second-harmonic frequency of a sheet of dipoles embedded in a 1D photonic crystal. The experimentally observed reflected second-harmonic intensity as a function of the angle of incidence shows sharp resonances corresponding to the excitation of the SH field in a local mode within the forbidden band in the structure, which position depends on the size of the defect, and additional resonance at the high angular band edge, which position is independent of the size of the defect. Comparison among these results and the SH intensity reflected by the same monolayer in free space (which presents a bell shaped radiation pattern as a function of the angle of incidence), shows an enhancement of the radiation at the resonances, and strong inhibition of the radiation at other angles within the gap. Theoretical simulation of the experiment shows a good agreement with the experimental results.
A detailed analysis of the enhancement and inhibition phenomena occurring in these structures shows a clear dependence of the resulting intensity with the position of the monolayer within the defect and with the dipole orientation. The change in phase difference between the oscillating dipoles and the field at the SH frequency at the monolayer as it is moved within the defect is found to play a determining role in the final energy transfer to the second-harmonic field. The resulting enhancement and inhibition of the radiation may be studied in terms of a nonsymmetric contribution of the different components of the field to the energy transfer process.
The second configuration studied in the present work consider the experimental demonstration of second-harmonic generation in a 3-dimensional macroscopically centrosymmetric lattice formed by spherical particles of optical dimensions. In such photonic crystals, the local breaking of the inversion symmetry at the surface of each sphere, allows for the existence of a nonvanishing second order interaction. The growth of the SH radiation is provided by the phase-matching mechanism caused by the bending of the photon dispersion curve near the Bragg reflection bands of this photonic crystal. Experimental evidence of this phase-matching mechanism, inherent of such crystals, is reported in this work. By measuring the SH intensity radiated from several crystals with different concentrations, we obtained the angular dependence of this type of emission and confirmed the surface character of the nonlinear interaction. A simplified theoretical model shows very good agreement with the experimental results. It is important to notice that in this mechanism of SHG, the nonlinearity of the molecule is independent of the phase-matching mechanism, that is inherent to the periodicity of the crystal.
In conclusion, the results obtained show a clear influence of the photonic crystals in the radiated SH intensity, resulting in enhancement and inhibition of the dipoles radiation.
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Trzeciecki, Mikołaj. "Second harmonic generation from antiferromagnetic interfaces." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=96147792X.
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Fairweather, Diane Bree. "Human psychopharmacology of second generation antidepressants." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320968.
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Crawford, Michael John. "Second harmonic generation from liquid interfaces." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261532.
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Trowbridge, Lynne. "Aligned composites for second harmonic generation." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283005.
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Harding, Sarah Louise. "Azadirachtin : towards a second generation synthesis." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610111.
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Holst, David. "DICOM Second Generation RT : An Analysis of New Radiation Concepts by way of First-Second Generation Conversion." Thesis, Uppsala universitet, Avdelningen för visuell information och interaktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-381978.
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The current DICOM communication standard for radiotherapy is outdated and has serious design issues. A new version of the standard, known as DICOM 2nd generation for Radiotherapy, has been introduced and this thesis examines new concepts relating to radiation delivery. Firstly, some background into the practice of radiotherapy is given, as well as a description of the DICOM standard. Secondly, the thesis describes the design issues of the current standard and how the 2nd generation aims to solve these. Thirdly, the thesis explores the conversion of a first generation C-Arm Photon/Electron treatment plan to the second generation RT Radiation and RT Radiation Set IODs. A converter is implemented based on a model proposed in a previous work. With some simplifications, the conversion of Basic Static and Arc treatment plans is shown to be successful. Conversion of further dynamic plan types is judged to be fairly simple to implement following the same methodology. The conversion model’s efficacy and testability are discussed and while the model is flexible and facilitates extension to further modalities some areas of improvement are suggested. Lastly, a GUI for the converter is demonstrated and the possibilities of user interaction during conversion are discussed.
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Onabanjo, Tosin. "Techno-economic and environmental assessment of gas turbines utilizing biofuels." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9280.
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The continued global reliance on fossil fuels with impact on resource depletion, human health, atmospheric pollution and environmental degradation has necessitated a global drive to integrate renewable fuels such as biodiesels. Biodiesels are described as “fuels composed of fatty acid methyl or ethyl esters and obtained from vegetable oils or animal fats”. Their use in energy generation could diversify the world’s energy mix, reduce fossil fuel dependence, reduce emissions and energy cost to bring about other economic benefits, especially for developing economies and rural communities with lack of adequate access to modern energy. A techno-economic and environmental life cycle assessment is however required to ensure that these fuels are fit for use in engines and meet any regulatory standard and sustainability criteria. This thesis has evaluated the use of Jatropha- and microalgae-biodiesel for power generation in two industrial gas turbines with open and combined cycle configuration. This was achieved using a techno-economic and environmental life cycle impact assessment framework. Comparative fuel assessments have been carried out between biodiesels and fossil fuels. Furthermore, the concept of microbial fuel degradation was examined in gas turbines. The thesis have identified Jatropha biodiesel as a worthwhile substitute for conventional diesel fuel, because it has close performance and emission characteristics to conventional diesel fuel with added advantage of being renewable. The consequent displacement of conventional diesel fuel with Jatropha biodiesel has significant environmental benefits. For economic viability and sustainability of gas turbine operated power plants, energy producers require a minimum monetary amount to recover the added cost of operating 100% Jatropha biodiesel. Other integration mechanisms are also available for utilizing the fuel in engines without compromising on plant’s economic performance. In worst case scenarios, where there are no government incentives, local conditions such as high life cycle cost of electricity, open opportunities for distributed and independent power generation from renewable fuels like Jatropha-biodiesel. Furthermore, this thesis has identified salient energy conversion processes that occur in gas turbine fuels, especially with biodiesels and developed a bio-mathematical model, Bio-fAEG to simulate these processes in gas turbines. This platform is a first step in quantifiable assessment and could enable a better understanding of microbial initiated processes.
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Okwo, Adaora. "Next-generation biofuels: the supply chain approach to estimating potential land-use change." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47603.
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Biofuels, including ethanol and biodiesel, are important components of energy policy in the U.S. and abroad. There is a long history of ethanol production from corn (maize) in the United States and from sugarcane in Brazil. However, there has been a push for greater use of next-generation biofuels (including those derived from cellulosic feedstocks) to mitigate many of the environmental and potential food system impacts of large scale biofuel production.
Farmer willingness to grow biomass crops and ensuring adequate feedstock supply are two important challenges impeding large scale commercialization of next-generation biofuels. The costs of transporting bulky, low density biomass will be substantial. Consequently, in the near term, the economic success of next-generation biofuels will hinge on the supply of locally available biomass. As such, agricultural contracts are expected to be an important tool in overcoming the feedstock acquisition challenge. The broad objective of this study is to understand the effect of contracting for non-food energy crops (cellulosic feedstocks) on the agricultural landscape via the displacement of commodity (food) crops on productive cropland.
We develop an analytical framework for evaluating the design and use of two different contract structures for securing cellulosic feedstock in a representative supply chain with a biorefinery and farmer. We study the dynamics of scarce land and indirect competition from commodity market production on a biorefinery's equilibrium pricing strategy and the resultant supply of cellulosic biomass. And we consider its sensitivity to various production characteristics and market conditions.
We develop a method for quantifying the biorefinery's tradeoff between profit margins and competing for land in order to secure the requisite feedstock for biofuel production. And we characterize the loss of efficiency in the decentralized system, relative to a vertically integrated system, that can be attributed to the need to compete for the farmer's scarce land resource versus that which results from the biorefinery's desire to make a profit.
Then we extend our framework to consider multi-year contracts for biomass production and evaluate the importance of land quality, yield variability and contract structure on a farmer's willingness to accept a contract to produce cellulosic feedstock as well as the resulting impact on the agricultural landscape through the displacement of commodity crops. Using switchgrass production in Tennessee as a case study, we develop feedstock supply curves for each contract structure considered and evaluate the conditions and contract prices at which land devoted to various field crops would be displaced by switchgrass based on field trials of switchgrass production in Tennessee and recent USDA data on crop prices and production.
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Martinov, Sonja. "Multi-Actor Multi-Criteria Decision Analysis of EU Policies for First Generation Biofuels." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-254952.
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In this paper multi-actor multi-criteria decision aid methodology are developed to examine the impacts of EU policies related to first generation biofuels on identified key stakeholders. The thesis focuses on the integration of relevant qualitative and quantitative criteria defined by key stakeholders into one comprehensive evaluation process, to serve as a decision support tool for decision makers. Weight allocation of the defined criteria will be assessed by using the Analytic Hierarchy Process (AHP) framework, where the multi-criteria decision-aid method PROMETHEE II is used to rank relevant policy alternatives based on the information provided. In the end, results will help the decision makers to identify the impacts of different EU policy alternatives on each stakeholder group.
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Mikhail, Anne. "Career development of second-generation immigrant women." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95106.
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Second-generation immigrants represent a significant subgroup of the Canadian population and workforce; however, the career development of adult second-generation immigrant women has not been examined. In order to understand the career development of second-generation women, an integration of Gottfredson and the feminist-multicultural career development theories was used. According to this integrated framework, it was important to understand: 1) sex-roles and gender and occupational stereotypes; 2) the effect of culture (i.e., familial, social class, and societal); 3) the effect of socio-cultural factors and systemic institutions (e.g., occupational stereotypes and discrimination); and 4) the effect that immigrant mothers had on the career development of second-generation immigrant women. A phenomenological approach was used to examine the career development experiences of second-generation immigrant women. Participants were 21 second-generation immigrant women between the ages of 24 and 39 years old, who had been working for at least 2 years. The women participated in an individual interview and co-created two pictorial representations of their own and their family's career development experiences. Participants were asked to describe their career aspirations, interests, values, and decision-making process as well as the influence of gender, family, culture and other societal factors on their career development. Results showed that the career development of second-generation immigrant women was very similar to that of North American women, indicating that the struggles that North American women faced seemed to be a cross-cultural phenomenon that transcended cultural and immigration status boundaries. Additionally, findings suggested that participants were influenced by their family and culture to pursue post-secondary education and culturally acceptable careers. It was also found that school programs (e.g., co-operative education program) were influential becausLes immigrants de deuxième génération constituent un sous-groupe important de la population Canadienne et des travailleurs canadiens; toutefois, le développement de carrière des immigrantes de deuxième génération d'âge adulte n'a jamais été examiné. Afin de comprendre le développement de carrière des immigrantes de deuxième génération, une synthèse de la théorie de Gottfredson et du développement de carrière féministe multiculturelle ont été utilisés. Selon ce cadre de travail, il était important de comprendre ce qui suit : 1) les rôles sexuels et les stéréotypes; 2) les influences culturelles (p. ex. famille, classe sociale et société); 3) les incidences des facteurs socioculturels et des institutions systémiques (p. ex. stéréotypes et discrimination professionnels); et 4) l'influence des mères immigrantes sur le développement de carrière des immigrantes de deuxièmes génération. Une approche phénoménologique a été utilisée pour étudier le développement de carrière des immigrantes de deuxième génération. Le groupe de participantes était constitué de 21 immigrantes de deuxièmes génération âgées entre 24 et 39 ans, et qui travaillaient depuis au moins deux ans. Les femmes ont passé une entrevue individuelle et elles ont créé en collaboration deux représentations graphiques, l'une de leur propre développement de carrière et l'autre du développement de carrière de leur famille. Les participantes ont décrit leurs aspirations professionnelles, leurs intérêts, leurs valeurs et leur processus décisionnel ainsi que l'influence du sexe, de la famille, de la culture et d'autres facteurs sociaux sur leur développement de carrière. Les résultats ont démontré que le développement de carrière des immigrantes de deuxième génération était très semblable à celui des femmes nord américaines, ce qui indique que les obstacles auxquels ces dernières font face semblent constituer un phénomène interc
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Galletto, Paolo. "Second harmonic generation of electrified metal surfaces /." [S.l.] : [s.n.], 2000. http://library.epfl.ch/theses/?nr=2262.
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Meyer, Folker. "GENDB a second generation genome annotation system /." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964442671.
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Patrick, Brian Olivier. "Second-harmonic generation studies of organic salts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25133.pdf.
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Travers, Paul James. "Langmuir-blodgett films for second harmonic generation." Thesis, Coventry University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254209.
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Wijeratne, I. "Second harmonic generation in novel optical waveguides." Thesis, City University London, 2013. http://openaccess.city.ac.uk/3015/.
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Second Harmonic Generation has traditionally been restricted to crystals; however, due to the development of highly sophisticated fabrication technology, poling and phase matching techniques, it has now become feasible in glass fibres and waveguides which are widely used in nonlinear optics. For instance, silica glass based Photonic Crystal Fibres (PCF) exhibit long coherence lengths and controllable optical properties such as chromatic dispersion despite low second order nonlinearity. Given such benefits, the numerical modelling and analysis of optical waveguides accurately and efficiently has become vital for the advancement of nonlinear optics. Hence, this thesis focuses on enhancing the Second Harmonic Generation in optical waveguides through the use of different structures and different materials, and demonstrating the same by numerical simulations. In this thesis, the accurate and numerically efficient Finite Element based Beam Propagation Method has been employed to investigate the evolution of Second Harmonic Generation in highly nonlinear SF57 soft glass Equiangular Spiral PCFs. Further, the H-field based Finite Element Method has been employed for the stationary analysis of Photonic Crystal Fibres. It is shown here that the second harmonic output power in highly nonlinear
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Haslam, Steven. "Second harmonic generation from liquid-liquid interfaces." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266382.
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Fordyce, Adam James Graham. "Second-harmonic generation at liquid/air interface." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297873.
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Leeson, Paul. "Langmuir-Blodgett films for second harmonic generation." Thesis, Cranfield University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323931.
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Elfar, Yassmeen. "Ethnic Identity in Second-Generation Arab Americans." Thesis, The Chicago School of Professional Psychology, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10006605.
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The purpose of this study was to observe the correlation between ethnic identity and gender as well as the relationship between ethnic identity and one’s country of origin. The study participants (n=335) were recruited through the social media sites Facebook, Twitter, Linked In, and Reddit. Participants completed the 15-question Multigroup Ethnic Inventory Measure (MEIM) and a Demographic Questionnaire, all done completely online. It was hypothesized that participants’ level of ethnic identity as measured by MEIM scores would differ significantly between the genders. Furthermore, it was posited that participant’s level of ethnic identity would differ significantly between countries of origin. Both hypotheses were supported. Implications of the study findings and recommendations for future research are discussed.
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Cartaxo, Justino Carvalho. "Heat release analysis for second generation biodiesels." Universidade Federal do CearÃ, 2016. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16984.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorSecond generation biodiesel fuels extracted from sources such as beef tallow and castor bean oil have gone through an increase in production, as they are being gradually added to soybean biodiesel which constitutes the primary biofuel in the country. These alternative materials have potential do increase the fuelâs oxidation stability and, specifically in the case of beef tallow, reduce the cost of producing biodiesel. However, these sources also contribute to making the properties of the biodiesel/diesel blend more distant from those of conventional diesel fuel. Beef tallow biodiesel, for example, has a cetane number of 64.70, compared to 46.44 the soybean and 48 for mineral diesel fuel. In the case of castor bean biodiesel, its viscosity is 14.5 cSt, while soybeanâs is 4.2 cSt and mineral dieselâs is 2.5. It is expected that these unique characteristics should have noteworthy consequences in the injection, tomization and combustion processes of the fuel. This work intends to determine the extent of these consequences by characterizing each second generation biodiesel fuelâs impact on the apparent heat release rate. To this end, experimental data on cylinder pressure and a heat release â or energy - analysis model on a combustion zone were utilized. The data were obtained from a medium sized turbo diesel engine operating at steady state for three different load levels. Biodiesel and diesel blends were prepared at concentration levels B10, representative of current commercial use, and B20, corresponding to a greater biofuel adoption in a future scenario. Second generation sources were also compared to data from soybean biodiesel, which forms around 75% of Brazilâs biodiesel production. At B20 concentrations, it was found that beef tallow biodiesel, due to its higher cetane number, hastened combustion by about 1◦ compared to soybean and 3◦ compared to mineral diesel. This anticipation in ignition also caused a reduction in the amount of fuel consumed as a premixed flame. Combustion of castor bean biodiesel was mostly unchanged for high and medium loads compared to mineral diesel fuel. However, on the low load configuration (BMEP = 250kPa) and at B20 concentration, it caused a significant delay in combustion, likely from the collision of the fuel jet against the cylinder wall.
Os biodieseis de segunda geraÃÃo oriundos de fontes, tais como o sebo bovino e a mamona, vÃm experimentando uma expansÃo em sua produÃÃo, sendo adicionados gradualmente ao biodiesel de soja, que constitui a matÃria-prima predominante no paÃs. Essas matÃrias-primas alternativas podem aumentar a estabilidade à oxidaÃÃo do combustÃvel e, no caso do sebo, diminuir o custo de produÃÃo do biodiesel. Contudo, elas tambÃm contribuem para um maior distanciamento entre as propriedades das misturas diesel/biodiesel e o Ãleo diesel convencional. O biodiesel proveniente do sebo bovino, por exemplo, possui um nÃmero de cetano de 68,77 frente aos 52,10 do de soja e 48 do Ãleo diesel mineral. Jà o biodiesel de mamona possui viscosidade de 14,5 cSt, frente aos 4,16 do de soja e 2,5 do Ãleo diesel mineral. Espera-se que essas caracterÃsticas singulares tenham consequÃncias importantes nos processos de injeÃÃo, atomizaÃÃo e queima do combustÃvel. O objetivo deste trabalho à determinar a extensÃo dessas consequÃncias, caracterizando-se o impacto de cada um desses biodieseis de segunda geraÃÃo sobre a taxa aparente de liberaÃÃo de energia. Empregou-se, para tanto, dados experimentais de pressÃo no cilindro e um modelo de anÃlise de liberaÃÃo de calor, ou de energia, com uma zona de combustÃo. Os dados foram obtidos com um motor diesel turbo de mÃdio porte operando em condiÃÃes de regime permanente e a trÃs nÃveis de carga. Preparou-se misturas entre diesel e biodiesel nas concentraÃÃes B10, representativas do patamar atual de adiÃÃo de biodiesel ao diesel mineral, e B20, que corresponderiam à maior adoÃÃo de biocombustÃveis em um cenÃrio futuro. As matÃrias-primas de segunda geraÃÃo, sebo bovino e mamona, tambÃm foram comparadas a dados obtidos com o biodiesel de Ãleo de soja, que corresponde a cerca de 75% a atual produÃÃo brasileira de biodiesel. Para as misturas B20, constatou-se que o biodiesel de sebo bovino, por ter maior nÃmero de cetano, adianta a combustÃo em cerca de 1◦ com relaÃÃo ao de soja e 3◦ com relaÃÃo ao diesel mineral. Devido a este adiantamento da igniÃÃo, o biodiesel de sebo bovino tambÃm reduziu a quantidade de combustÃvel consumido pelo modo prÃ-misturado. A combustÃo das misturas contendo biodiesel de mamona ficou praticamente inalterada para as condiÃÃes de alta e mÃdia carga com relaÃÃo ao Ãleo diesel mineral. Contudo, em baixa carga (bmep=250 kPa) e na concentraÃÃo correspondente a B10 e B20, o biodiesel de mamona provocou um atraso expressivo na combustÃo, provavelmente devido à colisÃo do jato combustÃvel com as paredes do pistÃo.
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Niemelä, J. (Jaakko). "Linux enriched design in second generation WARP." Master's thesis, University of Oulu, 2013. http://urn.fi/URN:NBN:fi:oulu-201305131222.
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In this thesis, it is shown how the Linux system was ported to the second generation wireless open access research platform (WARPv2) board. The purpose of the port was to extend the features of the WARPv2 board by producing a versatile standalone system that allows to run custom software on it. The Linux enriched design in WARPv2 also offers a controllable communication system by implementing all layers of the network architecture. Linux was chosen for the operating system for this work, because it is open source, which means it is easy to modify for different purposes. Moreover, Linux is well documented and it has wide software support. The Linux system was combined with the radio communication system provided by Rice University, USA. The field-programmable gate array (FPGA) hardware design was created for this combination and needed software of the system was defined and implemented. The developed system consisted of the Linux side and the MAC side. These sides implemented all layers of the network architecture. Both sides employed a dedicated processor core of the FPGA. Interprocessor communication between Linux and MAC sides was implemented to allow Linux to control the whole system. Two Linux kernel drivers were written to use interprocessor communication hardware. The setup process of the developed system was mitigated by writing several scripts. The developed system was tested, verified and analyzed to confirm that the implementation is valid and consistent. Several test cases were created for this purpose. Test cases were divided into two parts: hardware tests and performance tests. Hardware tests verified that the FPGA hardware design of the system was workable and fulfilled the requirements. Performance tests confirmed that the performance of the system was sufficientTässä työssä sovitettiin Linux-järjestelmä langattomalle kehitysalustalle (WARPv2). Sovitus tehtiin, jotta kehitysalustasta saataisiin monipuolinen ja itsenäinen. Lisäksi sovitus mahdollisti omien ohjelmien ajon alustalla sekä verkkoarkkitehtuurin kaikkien kerrosten hallittavuuden. Linux valittiin tämän työn käyttöjärjestelmäksi, sillä sen lähdekoodi on avoimesti saatavilla ja täten helposti muokattavissa eri tarkoituksiin sopivaksi. Linux on myös hyvin dokumentoitu ja sille on saatavilla runsaasti sovelluksia. Linux-järjestelmä yhdistettiin yhdysvaltalaisen Ricen yliopiston kehittämään langattomaan tiedonsiirtototeutukseen. Kehitysalustan FPGA-piirille suunniteltiin tälle yhdistelmälle sopiva laitteistototeutus ja tarvittavat ohjelmistot määriteltiin ja liitettiin mukaan järjestelmään. Kehitetty järjestelmä koostui Linuxosasta ja MAC-osasta. Nämä osat toteuttivat verkkoarkkitehtuurin kaikki kerrokset. Molemmille osille oli osoitettu oma suoritin FPGA-piiriltä. Linux- ja MAC-osan välille toteutettiin tiedonvälitysmekanismi, jotta Linux kykenisi hallitsemaan koko järjestelmää. Lisäksi Linuxille kirjoitettiin kaksi laitteistoajuria Linux- ja MAC-osien välisen tiedonvälityksen mahdollistamiseksi. Järjestelmän käyttöönoton helpottamiseksi kirjoitettiin useita komentosarjoja. Kehitetty järjestelmä testattiin, todennettiin ja analysoitiin järjestelmän toimivuuden varmistamiseksi. Testausta varten kehitettiin useita testitapauksia. Testaus koostui kahdesta osasta: laitteistotestauksesta ja suorituskykytestauksesta. Laitteistotestauksessa todennettiin laitteiston vaatimusten mukainen toiminta, kun taas suorituskykytestaussa varmistettiin suorituskykyvaatimusten täyttyminen
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Vecchi, Chiara. "Second harmonic generation in engineered silicon waveguides." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/298556.
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In the last years, Silicon becomes one of the most important technological platform for integrated photonics technologies. Nonlinear silicon photonics is a desired upgrade of this thecnology as it gives the opportunity to directly process the signal on the chip by using the wide spectrum of nonlinear phenomena. To have access to high order nonlinearities a large optical pump power is needed. Second order nonlinear effects are desirable due to the reduction of the used power with respect to third order nonlinearities. Moreover, it allows to achieve interesting efforts, such as wavelength conversion and generation of quantum states. Here the problem is that silicon has a diamond crystalline structure. Therefore, silicon is a centrosymmetric material. For a geometrical point of view, this property is reflected in a symmetry of the polarization vector P(E) = -P(-E) . The polarization vector is related to the electric field by: P = P^0 + P^(2) + P^(3) +... From equation 2, it is possible to see that, in order to respect the centrosymmetry, chi^(2) =0. So, in the dipole approximation, second order nonlinearities are inhibited in Silicon. Many efforts have been spent to induce second order nonlinearities in Silicon. At first, strained silicon, in which the centrosymmetry of Silicon crystalline structure is broken by an inhomogeneous strain, seemed to be the most viable solution. In strained silicon waveguides, the inhomogeneous strain is applied by a stressing layer of different materials with a different lattice constant deposited on top of the waveguide [4]. The first experiment based on Silicon waveguides was performed in 2006 by Jacobsen et al. that measured a nonlinear coefficient chi^(2) = 15 pm/V with a SiN stressing layer via DC electro-optic effect. This work was followed by many others, reaching values for the strain-induced second order nonlinear coefficient chi^(2) up to 340 pm/V. Few works gave a different interpretation of the chi^(2). It was demonstrated that during the deposition of the stressing layer there is the formation of
dangling bonds at the interface between the deposited layer and the silicon waveguide. These dandling bonds act as positive fix ions. The formation of this charges, indeed, determined an abundance of free-carriers in the core of the waveguide that, because of the free carrier dispersion, can affect the value of the effective measured nonlinear coefficient in the DC electro-optic effect. Azadeh et al. demonstrated for the firs time the crucial role of this phenomenon which overtakes the strain effect, also confirmed by Olivares et al. An upper limit of chi^(2) = 8 pm/V due to a strain effect was experimentally fixed. Other works investigated second order nonlinearities in Silicon looking at the Second Harmonic Generation (SHG). Cazzanelli et al. measured a value of chi^(2) = 40 pm 30 pm/V by SHG in multimodal waveguides using a pump wavelength above 2 um, without any phase matching mechanism. It was also demonstrated that stressing layers that induced the same value of strain but realized with different materials yield different SHG, making clear that not only strain but also charged defects play an important role in the generation of the SH signal. Indeed, it was demonstrated that charged defects can induce an electric DC field that interacts with the large chi^(3) of bulk silicon to give a dressed (effective) second order nonlinear coefficient chi^(2)_EFISH = 3 chi^(3) E_DC via electric-field-induced second harmonic (EFISH) generation. So in 2017 the effect of the strain on silicon waveguides was not clear. The aim of my PhD work is try to understand the origin of the dressed chi^(2) in silicon waveguide and propose a way to engineer and control it.
In order to understand the origin of second order nonlinearities in silicon, an experiment that can separate the role of the strain and the role of the trapped charged defects at the interface between the silicon waveguide and the stressing layer in an unambiguously way was performed. The sample used was composed by a set of strip silicon waveguides 243 nm thick with a SiN stressing layer of 140 nm deposited on the top of the waveguide. The waveguides were engineered in order to have intermodal phase matching condition between the TM1 mode for the pump wavelength and TE3 mode for the generated SH wavelength. Different widths of the waveguide have been used in order to tune the phase-matching condition wavelength. To investigate the role of the strain, the sample was mounted on a sample holder equipped with a screw to deformed the waveguide. Rotating the screw, a vertical displacement Delta_H is induced in the center of the sample orthogonal to its main plain. This displacement acts as an external load that increase the strain in the silicon waveguide. SHG was measured for different values of the Delta_H displacement. Increasing the load in the sample there is a red-shift of peak. Indeed, increasing the strain in the sample a change in the effective index is induced, and a change in the phasematching condition is obtained. However, SH power is always the same, revealing that the value of chi^(2) is not increasing with the strain. To investigate the role of the trapped defect at the Si/SiN interface, following the idea of Piccoli et al., the sample was exposed to UV irradiation to induce a passivation (i.e. neutralization) of the defects. Then, SHG was measured and no generation can be detected. These results clarify that the main causes of the SH in silicon waveguide is not given by the strain but by the charge defect and an upper limit of chi^(2) at 0,05 pm/V for the strain induced second order nonlinear coefficient was experimentally fixed. This result is also supported by an earlier theoretical estimation given by Khurgin et al. in 2015.
From these observations, the use of an applied electric field emerges as a way to induce a controlled effective chi^(2) in silicon waveguide suitable for technological application. The idea is based on the use of a controlled external E_DC field in order to obtain the desired value of chi^(2) where the electric field can be generated by placing lateral p-i-n junctions across the waveguide that can be reverse biased using metallic pads. In this way, chi^(2) can be enhanced increasing the applied bias and the only limitation is the breakdown field of silicon, that is known to be around V = 24 V. Timurdogan et al. demonstrated that it is also possible to use the periodicity of the p-i-n junctions to absorb the mismatch between the pump and the SH modes in order to obtain a quasi-phase matching condition. The sample used was a set of rib waveguides with different widths. Along the propagation direction of the waveguide p-i-n junctions have been grown. Since in the generation efficiency what matters is not the overall chi^(2) but the amplitude of its oscillations along the length of the waveguide, an interdigitated poling configuration was studied. In this configuration, regions of p-i-n junctions and regions of n-i-p junctions are periodically alternated. Second harmonic generation was observed in this poled waveguide and the
SH signal increased quadratically with both the pump power and the applied bias, according with the theory. It was also demonstrated that a larger conversion efficiency is obtained using this poling configuration instead of the poling configuration proposed by Timurdogan in 2017.
Also a modeling of the effect of the fabrication defects has been done. The pump P_p and the generated P_SH powers are related by P_SH = P_p^2|gamma^(2)|^2 L^2 S where S is the poling therm which describes what is happening along the length of the waveguide. S is a function of the geometry of the waveguide and of the periodicity of the p-i-n junctions: S=1/L^2 |int_0^L s(z) exp(i Delta beta z) dz|^2. During the fabrication, an unwanted variation of the geometrical parameters can be induced along the length of the waveguide both in the waveguide cross section and in the
poling period. The effect of this two kind of variations has been studied. Moreover, the coherence length of the process has been also studied, in order to have a clear understanding of the EFISH process. the developed model was compared with the experimental data. It is possible to extract the effective Delta chi^(2) of the EFISH process with an interdigitated poling configuration, when 24 V are applied to the junctions: Delta chi^(2)_eff=78 pm 3 pm/V.
Finally it was perform a study of microrings that can accomodate geometrical defects. Using a 4-bar symmetry of the chi^(2) tensor, a study of the conversion efficiency as a function of the different parameters of the microring has been performed. It was demonstrated that the most critical parameter is the thickness of the waveguide in the ring and it was shown a method to find a geometry that allows to have efficient conversion efficiency in a range of thickness of 16 nm around the nominal value. Moreover, this method is more general, since it is based only on the symmetry of the nonlinear tensor. Therefore, it can be easily applied to other materials.
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AlMasarweh, Luma Issa. "Transnational Projects of Second-Generation Arab Americans." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1627052108291722.
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O'Donoghue, Leslie. "Holocaust, Memory, Second-Generation, and Conflict Resolution." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3785.
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Ten Jewish second-generation men and women from metro Portland, Oregon were interviewed regarding growing up in the aftermath of the Holocaust. The American-born participants ranged in age from fifty-one to sixty-four years of age at the time of the interviews. Though the parents were deceased at the time of this study the working definition of a Holocaust survivor parent included those individuals who had been refugees or interned in a ghetto, labor camp, concentration camp, or extermination camp as a direct result of the Nazi Regime in Europe from 1933 to 1945.
A descriptive phenomenological approach was utilized. Eight open-ended questions yielded ten unique perspectives. Most second-generation do not habitually inform others of their second-generation status. This is significant to conflict resolution as the effects of the Holocaust are trans-generational. The second-generation embody resilience and their combined emphasis was for all people to become as educated as possible.
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Baldwin, Ian Alan. "EROBOT : a second-generation NDE inspection robot." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5550.
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Fox, Roderick Charles. "Successful implementation of succession planning: second generation." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1012445.
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Family businesses are prevalent in South Africa and throughout the world. Succession is one of the largest challenges facing family businesses. It has been estimated that only one third of family businesses survive to the second generation. This study attempts to determine what the main features are to promote successful family business succession and continuity. The family chosen for this research is the Venter family. The research has scaled the various influencing variables from the literature review into the following focus areas: relationships, conflict, vision, effective succession characteristics and continuity. The findings reflect many instances found in the literature, some are: individuals can manage themselves and have relationships with others; have the ability to resolve conflicts; have mutual support and trust; there is respect between the founder and successor; the business vision is clear; communication is open and clear and decisions are based on expertise and knowledge. Many other aspects are highlighted in the research that follows. In addition, the study attempts to identify the generational effects, the major characteristics of the family owned succession process and the views of the predecessors on the succession process and the post succession period.
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Shen, Mengzhe. "Investigating second harmonic generation in collagen tissues." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54452.
Full textAbstract:
Collagen is the most abundant structural protein in the human body. When it is excited by femtosecond near infrared laser, second harmonic generation (SHG) signal at half the wavelength of the excitation wave is excited. For imaging thick tissues, the SHG signal is collected in the backward direction. The objective of this work is to elaborate the origin of the backward SHG in collagen at the fibril level and investigate some of its optic characteristics. The optic characteristics investigated include the wavelength dependence of SHG intensity, which is useful to analyze SHG in collagen tissues. However, the current published results are inconsistent. We study the microscopy system factors affecting the wavelength dependence and calibrate them by measuring the wavelength dependence of SHG intensity in a BaB₂O₄ crystal. With the proper calibration, typical wavelength dependence SHG spectra from mouse tail and Achilles tendon are investigated. The backward-collected SHG signal includes the backward generated SHG, and the forward generated but backward scattered SHG. Those two sources of the total backward SHG have different properties due to the difference in phase mismatch in the forward and backward directions. Here a non-invasive method is developed to separate them by using pinholes. By varying the pinhole size in a confocal multiphoton microscopy, the proportion of the backward scattered SHG to the total backward SHG can be obtained. Our results indicate that backward scattered SHG may not be the major source of backward SHG in the mouse tail tendon, which means significant SHG is purely generated in the backward direction. A large phase mismatch exists in generating backward SHG. Nevertheless, significant backward generated SHG has been observed in collagen tissues. We hypothesize that the periodic lattice structure of fibrillar collagen can provide a virtual momentum to assist the backward phase matching. Here the backward SHG phase matching is investigated in theory, simulation, and experiments, which are consistent and support the hypothesis. The various properties investigated in this thesis can provide a better understanding about SHG in collagen tissues and lead to new applications of SHG microscopy in diagnosing collagen related diseases in the future.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Wang, Jing-Yi. "Nonlinear processes in intracavity second harmonic generation." Doctoral thesis, Universite Libre de Bruxelles, 1996. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212351.
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Swana, Jeffrey Ross. "Construction and Analysis of a Modified Yeast Strain for Next Generation Biofuel Production." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/52.
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Current research efforts are focused on 'second generation biofuels', which includes biofuels produced from lignocellulosic material. Lignocellulosic material is primarily composed of cellulose, a glucose polymer, xylose rich hemicellulose and non-fermentable lignin. Saccharomyces cerevisiae is widely used on an industrial scale for the production of ethanol from glucose; however, native S. cerevisiae does not contain the genes required for fermentation of xylose into ethanol. Others have sequentially expressed trans-genes from xylose fermenting organisms to engineer strains of S. cerevisiae capable of fermenting this pentose. The goal of this thesis was to generate a single cassette of 9 genes which have been shown to ferment xylose and arabinose. The 17 kb DNA fragment harboring all the genes necessary was introduced into the yeast genome using one-step homologous recombination based transformation. Expression of this cassette was verified by demonstrating that the first and last genes on this cassette were transcribed. The modified strain exhibited xylose utilization under microaerobic fermentation conditions. Further genetic and process engineering methods may be employed to improve the yield. The experiments described here demonstrate that generating a functional cassette of pentose fermenting genes is still achievable.
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Calica, Reuel M. "Effective ministry to second generation Filipinos an ethnographic study of adult second generation Filipinos at Faith Bible Church of Vallejo /." Theological Research Exchange Network (TREN), 2008. http://www.tren.com/search.cfm?p002-0825.
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Ahn, Hyewon [Verfasser]. "Second Generation Patents in Pharmaceutical Innovation / Hyewon Ahn." Baden-Baden : Nomos Verlagsgesellschaft mbH & Co. KG, 2014. http://d-nb.info/1107613574/34.
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