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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.
1

Multi-dimensional modelling of biomass energy flows

Hemstock, Sarah Louise January 1999 (has links)
No description available.
2

Vehicle activity data for emissions modelling in urban areas of the Canadian Prairie Region

Patmore, Keenan Scott 12 January 2012 (has links)
This research develops and applies a methodology to calculate vehicle activity inputs for modelling of emissions from on-road vehicles using traffic count data. The thesis: (1) provides an understanding of emissions modelling in Canada and the U.S. and discusses the traffic activity data inputs required by vehicle emissions modelling software; (2) develops a methodology to collect and prepare vehicle activity data for an urban centre and applies this methodology by estimating vehicle activity for Winnipeg and Saskatoon; and (3) estimates vehicle emissions and then compares the sensitivity of estimating emissions using locally developed vehicle activity to estimating emissions using default vehicle activity. The methodology this research develops and applies to Winnipeg and Saskatoon is applicable to any jurisdiction in need of developing their own vehicle activity inputs for emissions modelling. The emissions estimates calculated using these different inputs emphasizes the importance of obtaining jurisdiction-specific input values for emissions modelling.
3

Vehicle activity data for emissions modelling in urban areas of the Canadian Prairie Region

Patmore, Keenan Scott 12 January 2012 (has links)
This research develops and applies a methodology to calculate vehicle activity inputs for modelling of emissions from on-road vehicles using traffic count data. The thesis: (1) provides an understanding of emissions modelling in Canada and the U.S. and discusses the traffic activity data inputs required by vehicle emissions modelling software; (2) develops a methodology to collect and prepare vehicle activity data for an urban centre and applies this methodology by estimating vehicle activity for Winnipeg and Saskatoon; and (3) estimates vehicle emissions and then compares the sensitivity of estimating emissions using locally developed vehicle activity to estimating emissions using default vehicle activity. The methodology this research develops and applies to Winnipeg and Saskatoon is applicable to any jurisdiction in need of developing their own vehicle activity inputs for emissions modelling. The emissions estimates calculated using these different inputs emphasizes the importance of obtaining jurisdiction-specific input values for emissions modelling.
4

An Integrated Multi-model Approach for Predicting the Impact of Household Travel on Urban Air Quality and Simulating Population Exposure

Hatzopoulou, Marianne 19 January 2009 (has links)
The population and economic growth experienced by Canadian metropolitan areas in the past twenty years, has been associated with increased levels of car ownership and vehicle kilometres travelled leading to a deterioration of air quality and public health and an increase in greenhouse gas emissions. The need to modify urban growth patterns has motivated planning agencies in Canada to develop a broad range of policies aiming at achieving a more sustainable transportation sector. The challenge however, remains in the ability to test the effectiveness of proposed policy measures. This situation has led to a renewed interest in integrated land-use and transport models to support transport policy appraisal. This research is motivated by the need to improve transport policy appraisal through the use of integrated land-use and transport models linked with a range of sub-models that can reflect transport externalities. This research starts with an exploration of the transport policy environment in Canada through a questionnaire-based survey conducted with planners and policy-makers. The survey results highlight the need for tools reflecting the sustainability impacts of proposed policies. While the second part of this research explores sustainability indicators and recommends a set of social, economic, and environmental measures, linked with integrated land-use and transport models; effort is dedicated to estimate the environmental indicators as part of this thesis. As such, the third part of this research involves the development of an emission-dispersion-exposure modelling framework. The framework includes a suite of sub-models including an activity-based travel demand model (TASHA), an emission factor model (Mobile6.2C), a meteorological model (CALMET), and a dispersion model (CALPUFF). The framework is used to estimate link-based emissions of light-duty vehicles in the Greater Toronto Area under a base scenario for 2001. Dispersion of emissions is then conducted and linked with population in order to estimate exposure to air pollution.
5

An Integrated Multi-model Approach for Predicting the Impact of Household Travel on Urban Air Quality and Simulating Population Exposure

Hatzopoulou, Marianne 19 January 2009 (has links)
The population and economic growth experienced by Canadian metropolitan areas in the past twenty years, has been associated with increased levels of car ownership and vehicle kilometres travelled leading to a deterioration of air quality and public health and an increase in greenhouse gas emissions. The need to modify urban growth patterns has motivated planning agencies in Canada to develop a broad range of policies aiming at achieving a more sustainable transportation sector. The challenge however, remains in the ability to test the effectiveness of proposed policy measures. This situation has led to a renewed interest in integrated land-use and transport models to support transport policy appraisal. This research is motivated by the need to improve transport policy appraisal through the use of integrated land-use and transport models linked with a range of sub-models that can reflect transport externalities. This research starts with an exploration of the transport policy environment in Canada through a questionnaire-based survey conducted with planners and policy-makers. The survey results highlight the need for tools reflecting the sustainability impacts of proposed policies. While the second part of this research explores sustainability indicators and recommends a set of social, economic, and environmental measures, linked with integrated land-use and transport models; effort is dedicated to estimate the environmental indicators as part of this thesis. As such, the third part of this research involves the development of an emission-dispersion-exposure modelling framework. The framework includes a suite of sub-models including an activity-based travel demand model (TASHA), an emission factor model (Mobile6.2C), a meteorological model (CALMET), and a dispersion model (CALPUFF). The framework is used to estimate link-based emissions of light-duty vehicles in the Greater Toronto Area under a base scenario for 2001. Dispersion of emissions is then conducted and linked with population in order to estimate exposure to air pollution.
6

Hybrid Dynamic Modelling of Engine Emissions on Multi-Physics Simulation Platform. A Framework Combining Dynamic and Statistical Modelling to Develop Surrogate Models of System of Internal Combustion Engine for Emission Modelling

Pant, Gaurav January 2018 (has links)
The data-driven models used for the design of powertrain controllers are typically based on the data obtained from steady-state experiments. However, they are only valid under stable conditions and do not provide any information on the dynamic behaviour of the system. In order to capture this behaviour, dynamic modelling techniques are intensively studied to generate alternative solutions for engine mapping and calibration problem, aiming to address the need to increase productivity (reduce development time) and to develop better models for the actual behaviour of the engine under real-world conditions. In this thesis, a dynamic modelling approach is presented undertaken for the prediction of NOx emissions for a 2.0 litre Diesel engine, based on a coupled pre-validated virtual Diesel engine model (GT- Suite ® 1-D air path model) and in-cylinder combustion model (CMCL ® Stochastic Reactor Model Engine Suite). In the context of the considered Engine Simulation Framework, GT Suite + Stochastic Reactor Model (SRM), one fundamental problem is to establish a real time stochastic simulation capability. This problem can be addressed by replacing the slow combustion chemistry solver (SRM) with an appropriate NOx surrogate model. The approach taken in this research for the development of this surrogate model was based on a combination of design of dynamic experiments run on the virtual diesel engine model (GT- Suite), with a dynamic model fitted for the parameters required as input to the SRM, with a zonal design of experiments (DoEs), using Optimal Latin Hypercubes (OLH), run on the SRM model. A response surface model was fitted on the predicted NOx from the SRM OLH DoE data. This surrogate NOx model was then used to replace the computationally expensive SRM simulation, enabling real-time simulations of transient drive cycles to be executed. The performance of the approach was validated on a simulated NEDC drive cycle, against experimental data collected for the engine case study. The capability of methodology to capture the transient trends of the system shows promising results and will be used for the development of global surrogate prediction models for engine-out emissions.
7

Analysis on copper, lead and tin removal in steel scrap sorting : Technologies involved, environmental considerations and economic aspects

Cavaliere, Giada January 2023 (has links)
With the urgency of cutting down CO2 emissions to reach climate neutrality by 2050, decarbonization of the steel industry is on the European Commission's agenda. Steelmaking accounts for 10 % of anthropogenic CO2 emissions and it is one of the most challenging sectors to decarbonize. A solution that could support this progressive shift is to put more trust into the electric arc furnace (EAF) process, which relies on steel scrap as the main feedstock, but currently it is only responsible for 40% of the EU steelmaking. The almost remaining percentage is taken by the blast furnace route. Multiple European blast furnaces are currently closing due to low demands, high competition on imports and extremely high energy prices for production due to the Russian invasion of Ukraine situation. This particular moment could the proper time for increasing the employment of the EAF process. Moreover, the latter could help to improve resource efficiency and circularity of steel scrap thanks to the usage of higher shares of it, creating a “closed loop” for the steel industry. The reality of using more steel scrap is not actually very far from where we are, however, this will not be easy to reach. In fact, to ensure that the steel scrap is recycled "infinite" times it must contain very low quantities of impurities, such as copper (Cu}, tin (Sn) and lead (Pb}. Most of the times, this does not happen. Thus scrap is diluted with virgin iron to disperse those unwanted elements. This practice leads to a gradual decline of steel scrap quality, which is not in accordance with what it has just stated above. To worsen this situation even more, forecast is predicting increasing quantities of Cu that will accumulate into the steel scrap streams, due to the expected rising electric vehicles production. The aim of the following thesis work is to set a model to design a potential sorting solution to provide a higher copper (the most annoying cause of concern) removal rate in steel scrap, considering the economic and environmental implications of its implementation in the industry. Nonetheless, the presence of even lead and tin will also be taken into account. Results showcases that it is possible to get better impurities removal compared to what it has been done in many EU steel scrapyards, with ballistic separation as an additional refining separation step. Moreover, it is also an economically convenient and easy implementable solution that would assure higher quality steel scrap downstream of the process and that would also bring substantial economic and environmental benefits. / Med det brådskande att minska CO2-utsläppen för att nå klimatneutralitet till 2050, står avkarbonisering av stålindustrin på EU-kommissionens agenda. Ståltillverkning står för 10 % av antropogena koldioxidutsläpp och det är en av de mest utmanande sektorerna att ta bort koldioxid. En lösning som skulle kunna stödja denna progressiva förändring är att sätta mer förtroende till den elektriska ljusbågsugnsprocessen (EAF), som är beroende av stålskrot som huvudråvara, men för närvarande är den bara ansvarig för 40 % av ståltillverkningen i EU. Den nästan återstående andelen tas av masugnsvägen. Flera europeiska masugnar stängs för närvarande på grund av låga krav, hög konkurrens på import och extremt höga energipriser för produktion på grund av den ryska invasionen av Ukraina. Just detta ögonblickkan vara fördelaktigt för att öka sysselsättningen av EAF-processen. Dessutom skulle det senare kunna bidra till att förbättra resurseffektiviteten och cirkulariteten för stålskrot tack vare användningen av högre andelar av det, vilket skapar en "sluten slinga" för stålindustrin. Verkligheten med att använda mer stålskrot är faktiskt inte särskilt långt ifrån där vi är, men detta kommer inte att vara lätt att nå. Faktum är att för att säkerställa att stålskrotet återvinns "oändliga" gånger måste det innehålla mycket små mängder föroreningar, såsom koppar (Cu), tenn (Sn) och bly (Pb). Oftast händer detta inte. Således späds skrot med jungfruligt järn för att skingra dessa oönskade element. Denna praxis leder till en gradvis försämring av stålskrotskvaliteten, vilket inte är i enlighet med vad den nyss har angett ovan. För att förvärra denna situation ännu mer, förutspår prognosen ökande mängder Cu som kommer att ackumuleras i stålskrotströmmarna, på grund av den förväntade ökande produktionen av elfordon. Syftet med följande examensarbete är att sätta en modell för att designa en potentiell sorteringslösning för att ge en högre kopparavskiljningshastighet (den mest irriterande orsaken till oro) i stålskrot, med tanke på de ekonomiska och miljömässiga konsekvenserna av dess implementering i industrin. Icke desto mindre kommer förekomsten av jämnt bly och tenn också att beaktas. Resultaten visar att det är möjligt att få bättre bortförsel av föroreningar jämfört med vad man har gjort på många stålskrotvarv i EU, med ballistisk separering som ett extra raffineringssteg. Dessutom är det också en ekonomiskt bekväm och lätt implementerbar lösning som skulle säkerställa högre kvalitet stålskrot nedströms om processen och som också skulle ge betydande ekonomiska och miljömässiga fördelar.
8

Sustainability Assessment of Key European Dairy Cattle Production Systems: System Identification, Analysis, and Greenhouse Gas and Nitrogen Emission Mitigation

Díaz de Otalora Aguirre, Xabier 07 September 2023 (has links)
[ES] Durante las últimas décadas, múltiples retos han puesto en riesgo la sostenibilidad medioambiental, económica y social de los sistemas de producción de vacuno lechero (SPL). Esta Tesis Doctoral aborda algunos de los principales retos del sector en materia de sostenibilidad mediante el desarrollo de conceptos, metodologías y estrategias adaptadas a las necesidades particulares de un amplio abanico de SPL en Europa. Las investigaciones se centran en la evaluación de las herramientas de análisis de la sostenibilidad, el análisis de la diversidad de sistemas de producción existentes, así como en la mitigación adaptada de las emisiones de gases de efecto invernadero (GEI) y pérdidas de nitrógeno (N) a escala de granja. Esta Tesis Doctoral presenta un marco cuantitativo que permite un análisis exhaustivo de las herramientas existentes para la determinación de la sostenibilidad a escala de granja. Los resultados muestran como las herramientas evaluadas presentan un mayor número de indicadores asociados con el pilar medioambiental que con el pilar económico y social. En adición, se facilita la identificación de vías para el desarrollo futuro de los modelos, permitiendo una más completa y detallada evaluación de la sostenibilidad. Asimismo, los resultados obtenidos en materia de análisis de la diversidad de SPL, permiten la identificación, descripción y agrupación de las regiones europeas de acuerdo con diferentes tipologías de sistemas productivos. Las 16 tipologías representativas identificadas, combinan las características estructurales, productivas, socioeconómicas y medioambientales de los SPL con la distribución de cultivos forrajeros más relevantes para la producción láctea a escala NUTS2. Al analizar y agrupar la diversidad de sistemas productivos y evaluar su nivel de integración, esta Tesis Doctoral facilita la toma de decisiones basadas en el conocimiento, el diseño y la aplicación de medidas de mitigación de emisiones específicas y adaptadas, así como la promoción de sinergias económicas y sociales positivas. En adición, esta Tesis Doctoral pone de manifiesto la gran influencia de las condiciones climáticas, las características estructurales y las prácticas de manejo sobre las emisiones de N y GEI asociadas a la fermentación entérica, los cultivos, así como a toda la cadena de gestión del estiércol. Al identificar la magnitud y fuentes de emisión de los SPL, se facilita la aplicación de medidas específicas a cada contexto. En términos de mitigación de las emisiones, la reducción de la proteína bruta en la fracción comprada de la dieta es una estrategia eficaz a la hora de mitigar tanto las emisiones de GEI como las pérdidas de N. Además, la implantación de una planta de digestión anaerobia es efectiva a la hora de reducir la intensidad de GEI en todos los SPL evaluados, aumentando únicamente las pérdidas de N en el sistema mediterráneo intensivo. El impacto del incremento de la productividad a través de un mayor uso piensos sobre las pérdidas de N y las emisiones de GEI es variable entre los sistemas examinados. A este respecto, el sistema semi-extensivo centroeuropeo muestra un mayor potencial de reducción de GEI, mientras que el semi-extensivo atlántico obtiene mejores resultados en la reducción de las pérdidas de N. Del mismo modo, el uso de la inyección de purines reduce las pérdidas de N en campo, incrementando las emisiones de GEI en el sistema mediterráneo. La sustitución de urea por nitrato amónico tiene diferentes efectos sobre los GEI y la intensidad de N, observándose un mayor potencial de mitigación en el sistema semi-extensivo atlántico. Por último, las cubiertas rígidas de purines mitigan eficazmente las pérdidas de N durante el almacenamiento, con un impacto mínimo en las emisiones totales de GEI. Así mismo, a lo largo de esta Tesis Doctoral se demuestra como la aplicación cumulativa de medidas de mitigación, deriva en sinergias positivas a la hora de reducir las emisiones globales de la explotación. / [CA] Durant les últimes dècades, múltiples reptes n'han posat en risc la sostenibilitat mediambiental, econòmica i social dels sistemes de producció de boví de llet (SPL). Aquesta Tesi Doctoral aborda alguns dels principals reptes del sector en termes de sostenibilitat mitjançant el desenvolupament de conceptes, metodologies i estratègies adaptades a les necessitats particulars d'un ampli ventall de SPL a Europa. Les investigacions se centren en l'avaluació de les eines per a la seua quantificació, l'anàlisi de la diversitat de sistemes de producció existents, així com en la mitigació adaptada de les emissions de gasos d'efecte d'hivernacle (GEH) i pèrdues de nitrogen (N) a escala de granja. Aquesta Tesi Doctoral presenta un marc quantitatiu que permet una anàlisi exhaustiu de les eines existents per a la determinació de la sostenibilitat a escala de granja. Els resultats obtinguts mostren com les eines avaluades presenten un major nombre d'indicadors associats amb el pilar mediambiental que amb el pilar econòmic i social. A més, aquest treball facilita la identificació de vies per al desenvolupament futur dels models i facilita una avaluació de la sostenibilitat més completa i detallada. Els resultats obtinguts en matèria d'anàlisi de la diversitat de SPL permeten la identificació, descripció i agrupació de les regions europees d'acord amb diferents tipologies de sistemes productius. Les 16 tipologies representatives identificades combinen les característiques estructurals, productives, socioeconòmiques i mediambientals dels SPL amb la distribució de conreus farratgers més rellevants per a la producció làctia a escala NUTS2. En addició, en analitzar i agrupar la diversitat de sistemes productius i avaluar el seu nivell d'integració, aquesta Tesi Doctoral facilita la presa de decisions basada en el coneixement, el disseny i l'aplicació de mesures de mitigació d'emissions específiques i adaptades, així com la promoció de sinergies econòmiques i socials positives. Així mateix, aquesta Tesi Doctoral indica la gran influència de les condicions climàtiques, les característiques estructurals i les pràctiques de maneig sobre les emissions de N i GEH associades a la fermentació entèrica, els conreus, així com tota la cadena de gestió del fem. A més, en identificar la magnitud i fonts d'emissió dels SPL, es facilita l'aplicació de mesures específiques a cada context. En aquest sentit, la reducció de la proteina bruta en la porció comprada de la dieta és una estratègia eficaç per a mitigar tant les emissions de GEH com les de N. A més, la implantació d'una planta de digestió anaeròbia va reduir la intensitat de GEH en totes les SPL avaluades, augmentant únicament les emissions de N en el sistema mediterrani intensiu. L'impacte de l'increment de la productivitat a través d'un major use pinsos sobre les pèrdues de N i les emissions de GEH va variar entre els sistemes d'explotació examinats. Referent a això, el sistema semi-extensiu centreeuropeu va mostrar un major potencial de reducció de GEH, mentre que el semi-extensiu atlàntic va obtindre millors resultats en la reducció de les pèrdues de N. De la mateixa manera, l'ús de la injecció de purins va reduir les emissions de N a nivell de camp, incrementant les emissions de GEH en el sistema mediterrani. La substitució d'urea per nitrat d'amoni va tindre diferents efectes sobre els GEH i la intensitat de N, observant-se un major potencial de mitigació en el sistema semi-extensiu atlàntic. Finalment, les cobertes rígides de purins van reduir eficaçment les pèrdues de N durant l'emmagatzematge amb un impacte mínim en les emissions totals de GEH. Així mateix, al llarg d'aquesta Tesi Doctoral es demostra com l'aplicació cumulativa de mesures de mitigació deriva en sinergies positives a l'hora de reduir les emissions globals de l'explotació. / [EN] During the last decades, multiple challenges have put the environmental, economic, and social sustainability of dairy cattle production systems (DPS) at risk. This Ph.D. Thesis tackles some of the sector's main challenges in terms of sustainability by developing concepts, methodologies, and strategies adapted to the particular needs of a wide range of European DPS. In particular, special emphasis is placed on evaluating the tools for sustainability assessments, the analysis and clustering of the diversity of existing production systems, and the adapted mitigation of greenhouse gas (GHG) emissions and nitrogen (N) losses at the farm scale. This Ph.D. Thesis presents a quantitative framework that comprehensively evaluates whole-farm tools and models. The obtained results show how the models considered incorporate more indicators from the environmental pillar than those related to the economic or social sphere. In addition, this work facilitates the identification of avenues for future model developments, allowing for a more complete and detailed assessment of sustainability. Furthermore, the results obtained allow for the identification, description, and clustering of European regions according to different typologies of production systems. The 16 representative typologies identified combine DPS's structural, productive, socio-economic, and environmental characteristics with the level of overlap with the most relevant fodder crops for dairy production at the NUTS2 scale. Furthermore, by analyzing and clustering the diversity of production systems and assessing their level of integration, this Ph.D. Thesis facilitates knowledge-based decision-making, the design and implementation of targeted and adapted emission mitigation measures, as well as the promotion of positive economic and social synergies. Moreover, this Ph.D. Thesis highlights the strong influence of climatic conditions, structural characteristics, and management practices on N and GHG emissions associated with enteric fermentation, fields, and manure management. In terms of emission mitigation, reducing the amount of crude protein in the purchased fraction of the diet is an effective strategy to mitigate both GHG and N emissions. Additionally, implementing an anaerobic digestion plant reduces GHG emissions in all assessed DPS but increases N losses only in the intensive Mediterranean DPS. The impact of increased productivity through larger use of concentrates on N losses and GHG emissions varied depending on the farming systems examined. In this sense, the Central European semi-extensive system shows a higher potential for GHG reduction, while the Atlantic semi-extensive system accounts for better results when lowering the N losses. Similarly, shallow slurry injection effectively decreases N losses at the field level, although it increases GHG emissions in the Mediterranean DPS. Substituting urea with ammonium nitrate has different effects on GHG and N emission intensity, with greater potential for mitigation in the Atlantic semi-extensive system. Lastly, rigid slurry covers effectively reduces N losses during storage with minimal impact on GHG emissions. Furthermore, this Ph.D. Thesis shows how the cumulative application of mitigation measures leads to positive synergies in reducing the overall emissions of the farm. / All studies conducted in the course of this Ph.D. Thesis were funded by the German Federal Ministry of Food and Agriculture (BMEL) through the Federal Office for Agriculture and Food (BLE) within the framework of the project "MilKey" (grant number 2819ERA08A), funded by the joint call 2018 ERA-GAS (grant no. 696356), SusAn (grant no. 696231) and ICT-AGRI 2 (grant no. 618123) on "New technologies, solutions, and systems to reduce greenhouse gas emissions in animal production systems". BC3-Research is supported by the Spanish Government through María de Maeztu excellence accreditation 2018–2022 (Ref. MDM-2017-0714) and María de Maeztu excellence accreditation 2023-2026 (Ref. CEX2021-001201-M, funded by MCIN/AEI/10.13039/501100011033) and by the Basque Government through the BERC 2018–2021 program. Agustin del Prado is financed through the Ramon y Cajal program by the Spanish Ministry of Economy, Industry, and Competitiveness (RYC-2017-22143). / Díaz De Otalora Aguirre, X. (2023). Sustainability Assessment of Key European Dairy Cattle Production Systems: System Identification, Analysis, and Greenhouse Gas and Nitrogen Emission Mitigation [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196465

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