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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.
21

Modelling and evaluating the aquatic fate of detergents

Schulze, Carsten 08 May 2001 (has links)
Modelling and evaluating the aquatic fate of detergents - Abstract Within this thesis an environmental assessment and evaluation method for analysing aquatic ecotoxicological impacts of household laundry is developed. The methodology allows comparative assessments of different product alternatives, washing habits, and wastewater treatment techniques in order to identify their relevance with respect to waterborne discharges. Elements from both analytical tools Life Cycle Assessment (LCA) and Environmental Risk Assessment of chemicals (ERA) are combined in this methodology. The core consists of the Geography-referenced Regional Exposure Assessment Tool for European Rivers (GREAT-ER), which calculates concentrations of `down-the-drain' chemicals in surface waters due to point releases. In order to simulate the aquatic fate of detergents, a new GREAT-ER emission model is developed, called GREAT-ER product mode, which calculates calculates concentration increases of detergent ingredients in surface waters based on product formulations and assumptions concerning washing habits. Two evaluation methods, the Critical Length (CL) and the Product Risk Ratio (PRRx), are defined for evaluating the results. CL is the sum of mean concentration increases, divided by substance-specific no effect concentrations (NECs), over all river stretches and all ingredients weighted by the lengths of the stretches. PRRx is the (percentual) number of river stretches in a region, in which the x-percentiles of the predicted concentration increases of at least one ingredient exceed a substance-specific NEC. The emission model requires input data that can be derived from the functional unit of an LCA, which allows an assessment of other impact categories by using any existing LCA method. The methodology is applied to a case study which is based on scenarios given in the comprehensive product assessment `Washing and washing agents' (`Produktlinienanalyse', PLA). In order to apply the GREAT-ER product mode, the Rur river basin in Western North-Rhine Westphalia is chosen as study area. The catchment integration includes the development of a simple hydrological model that combines a nonlinear regression analysis with a local refinement procedure. The quality of the integration of the Rur catchment data is analysed by a comparison of monitoring data and predicted concentrations of detergent and cleaning agent ingredients using actual consumption data of the two years 1993 and 2000. The product mode results show that use habits have a larger influence on the results than product formulations. However, the largest influence is caused by varying wastewater treatment techniques. Boron and the surfactants are the most relevant detergent ingredients. Furthermore, using different detergents for white and coloured laundry lowers the predicted emissions significantly. Based on this methodology, sustainable development indicators (SDIs) for describing the aquatic aspects of household laundry are defined. CL is proposed as pressure indicator and PRRx as state indicator for describing aquatic aspects of the sustainability of household laundry in a region. Different regions can be compared by normalising the CL by the region's population and expressing the PRRx as a percentage of stretches in a region. Annually evaluating regional CLs and PRRxs allows the assessment whether a region is moving towards a more sustainable state. Concluding, the new method analyses and evaluates the environmental fate of detergents discharged after use via the wastewater pathway. It provides information not obtainable by other existing methods, which has been made possible due to the focussing on a specific application, for which the method is developed. Its application in the context of sustainable development offers a means to evaluate environmental implications of this important human activity.
22

Life-cycle sustainability design of post-tensioned box-girder bridge obtained by metamodel-assisted optimization and decision-making under uncertainty

Penadés Plà, Vicent 12 March 2021 (has links)
Tesis por compendio / [EN] Currently, there is a trend towards sustainability, especially in developed countries, where the concerns of society about environmental degradation and social problems have increased. Following this trend, the construction sector is one of the most influential sectors due to its high economic, environmental, and social impacts. At the same time, there is an increase in the demand for transport, which drives a need to develop and maintain the necessary infrastructure for this purpose. Taking all these factors into account, bridges become a key structure and therefore assessment of sustainability throughout their whole life-cycle is essential. The main objective of this thesis is to propose a methodology that allows assessment of the sustainability of a bridge under uncertain initial conditions (subjectivity of the decision-maker or variability of initial parameters) and optimization of the design to obtain a robust optimal bridge. To this end, an extensive bibliographic review of all the works that perform assessments of the sustainability of bridges through the valuation of criteria related to their main pillars (economic, environmental, or social) has been carried out. In this review, it has been observed that the most comprehensive way to evaluate the environmental and social pillars is through the use of life-cycle impact assessment methods. These methods allow sustainability assessment to be performed for the whole life-cycle of the bridge. This process provides valuable information to decision-makers for the assessment and selection of the most sustainable bridge. However, the decision-makers' subjective assessments of the relative importance of the criteria influence the final assessment of sustainability. For this reason, it is necessary to create a methodology that reduces the associated uncertainty and seeks robust solutions according to the opinion of decision-makers. In addition, for bridges, the design and decision-making are conditioned by the initially defined parameters. This leads to solutions that may be sensitive to small changes in these initial conditions. A robust optimal design makes it possible to obtain optimal solutions and structurally stable designs under variations of the initial conditions as well as sustainable designs that are not influenced by the preferences of the stakeholders who are part of the decision-making process. Thus, obtaining a robust optimal design becomes a probabilistic optimization process that has a high computational cost. For this reason, the use of metamodels has been integrated into the proposed methodology. Specifically, Latin hypercube sampling is used for the definition of the initial sample and a kriging model is used for the definition of the mathematical approximation. In this way, kriging-based heuristic optimization reduces the computational cost by more than 90% with respect to conventional heuristic optimization while obtaining very similar results. This thesis provides, first of all, an extensive bibliographic review of both the criteria used for the assessment of sustainability of bridges and the different methods of life-cycle impact assessment to obtain a complete profile of the environmental and social pillars. Subsequently, a methodology is defined for the full assessment of sustainability, using life-cycle impact assessment methods. Likewise, an approach is proposed that makes it possible to obtain structures with little influence from the structural parameters, as well as from the preferences of the different decision-makers regarding the sustainability criteria. The methodology provided in this thesis is applicable to any other type of structure. / [ES] Actualmente existe una tendencia hacia la sostenibilidad, especialmente en los países desarrollados donde la preocupación de la sociedad por el deterioro ambiental y los problemas sociales ha aumentado. Siguiendo esta tendencia, el sector de la construcción es uno de los sectores que mayor influencia tiene debido a su alto impacto económico, ambiental y social. Al mismo tiempo, existe un incremento en la demanda de transporte que provoca la necesidad de desarrollo y mantenimiento de las infraestructuras necesarias para tal fin. Con todo esto, los puentes se convierten en una estructura clave, y por tanto, la valoración de la sostenibilidad a lo largo de toda su vida es esencial. El objetivo principal de esta tesis es proponer una metodología que permita valorar la sostenibilidad de un puente bajo condiciones iniciales inciertas (subjetividad del decisor o variabilidad de parámetros iniciales) y optimizar el diseño para obtener puentes óptimos robustos. Para ello, se ha realizado una extensa revisión bibliográfica de todos los trabajos en los que se realiza un análisis de la sostenibilidad mediante la valoración de criterios relacionados con sus pilares principales (económico, medio ambiental o social). En esta revisión, se ha observado que la forma más completa de valorar los pilares medioambientales y sociales es mediante el uso de métodos de análisis de ciclo de vida. Estos métodos permiten llevar a cabo la valoración de la sostenibilidad durante todas las etapas de la vida de los puentes. Todo este procedimiento proporciona información muy valiosa a los decisores para la valoración y selección del puente más sostenible. No obstante, las valoraciones subjetivas de los decisores sobre la importancia de los criterios influyen en la evaluación final de la sostenibilidad. Por esta razón, es necesario crear una metodología que reduzca la incertidumbre asociada y busque soluciones robustas frente a las opiniones de los agentes implicados en la toma de decisiones. Además, el diseño y toma de decisiones en puentes está condicionado por los parámetros inicialmente definidos. Esto conduce a soluciones que pueden ser sensibles frente a pequeños cambios en dichas condiciones iniciales. El diseño óptimo robusto permite obtener diseños óptimos y estructuralmente estables frente a variaciones de las condiciones iniciales, y también diseños sostenibles y poco influenciables por las preferencias de los decisores que forman parte del proceso de toma de decisión. Así pues, el diseño óptimo robusto se convierte en un proceso de optimización probabilística que requiere un gran coste computacional. Por este motivo, el uso de metamodelos se ha integrado en la metodología propuesta. En concreto, se ha utilizado hipercubo latino para la definición de la muestra inicial y los modelos kriging para la definción de la aproximación matemática. De esta forma, la optimización heurística basada en kriging ha permitido reducir más de un 90% el coste computacional respecto a la optimización heurística conveniconal obteniendo resultados muy similares. Esta tesis proporciona en primer lugar, una amplia revisión bibliográfica, tanto de los criterios utilizados para la valoración de la sostenibilidad en puentes como de los diferentes métodos de análisis de ciclo de vida para obtener un perfil completo de los pilares ambientales y sociales. Posteriormente, se define una metodología para la valoración completa de la sostenibilidad, usando métodos de análisis de ciclo de vida. Asimismo, se propone un enfoque que permite obtener estructuras poco influenciables por los parámetros estructurales, así como por las preferencias de los diferentes decisores frente a los criterios sostenibles. La metodología proporcionada en esta tesis es aplicable a cualquier otro tipo de estructura. / [CA] Actualment existeix una tendència cap a la sostenibilitat, especialment en els països desenrotllats on la preocupació de la societat pel deteriori ambiental i els problemes socials ha augmentat. Seguint aquesta tendència, el sector de la construcció és un dels sectors que major influència té a causa del seu alt impacte econòmic, ambiental i social. Al mateix temps, existeix un increment en la demanda de transport que provoca la necessitat de desenrotll i manteniment de les infraestructures necessàries per a tal fi. En tot açò, els ponts es converteixen en una estructura clau, i per tant, la valoració de la sostenibilitat al llarg de tota la seua vida és essencial. L'objectiu principal d'aquesta tesi doctoral és proposar una metodologia que permeta valorar la sostenibilitat d'un pont baix condicions inicials incertes (subjectivitat del decisor o variabilitat dels paràmetres inicials) i optimitzar el disseny per a obtenir ponts òptims robusts. Per a això, s'ha realitzat una extensa revisió bibliogràfica de tots els treballs en els quals es realitza un anàlisis de la sostenibilitat mitjançant la valoració de criteris relacionats amb els seus pilars principals (econòmic, ambiental o social). En aquesta revisió s'ha observat que la forma més completa de valorar els pilars ambientals i socials és mitjançant l'ús de mètodes d'anàlisis de cicle de vida. Aquests mètodes permeten realitzar la valoració de la sostenibilitat al llarg de totes les etapes de la vida dels ponts. Tot aquest procediment proporciona informació molt valuosa als decisors per a la valoració i selecció del pont més sostenible. No obstant això, les valoracions subjectives dels decisors sobre la importància dels criteris influeixen en l'avaluació final de la sostenibilitat. Per aquesta raó, és necessari crear una metodologia que reduïsca la incertesa associada i busque solucions robustes enfront de les opinions dels agents implicats en la presa de decisions. A més, el disseny i la presa de decisions en ponts està condicionat pels paràmetres inicialment definits. Açò condueix a solucions que poden ser sensibles front a menuts canvis en les dites condicions inicials. El disseny òptim robust permet obtenir dissenys òptims i estructuralment estables front a variacions de les condicions inicials, i també dissenys sostenibles i poc influenciables per les preferències dels decisors que formen part del procés de presa de decisió. D'aquesta manera, el disseny òptim robust es converteix en un procés d'optimització probabilística que requereix un gran cost computacional. Per aquest motiu, l'ús de metamodels s'ha integrat en la metodologia proposta. En concret, s'ha utilitzat l'hipercub llatí per a la definició de la mostra inicial i els models kriging per a la definició de l'aproximació matemàtica. D'aquesta forma, l'optimització heurística basada en kriging ha permés reduir més d'un 90% el cost computacional respecte a l'optimització heurística convencional obtenint resultats molt similars. Aquesta tesi doctoral proporciona en primer lloc, una ampla revisió bibliogràfica, tant dels criteris utilitzats per a la valoració de la sostenibilitat en ponts com dels diferents mètodes d'anàlisis de cicle de vida per a obtenir un perfil complet dels pilars ambientals i socials. Posteriorment, es defineix una metodologia per a la valoració completa de la sostenibilitat, utilitzant mètodes d'anàlisis de cicle de vida. Així mateix, es proposa un enfocament que permet obtenir estructures poc influenciables pels paràmetres estructurals, així com per les preferències dels diferents decisors enfront dels criteris sostenibles. La metodologia proporcionada en aquesta tesi doctoral és aplicable a qualsevol altre tipus d'estructura. Nº de páginas: / I would like to acknowledge the economic support of the Spanish Ministry of Economy and Competitiveness, formerly called Spanish Ministry of Science and Innovation. This thesis has been possible thanks to the FPI fellowship and the financially support of BRIDLIFE (Research Project BIA2014-56574-R) and DIMALIFE (Project BIA2017-85098-R). / Penadés Plà, V. (2020). Life-cycle sustainability design of post-tensioned box-girder bridge obtained by metamodel-assisted optimization and decision-making under uncertainty [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/147480 / Compendio
23

Dynamic environmental indicators for smart homes:assessing the role of home energy management systems in achieving decarbonisation goals in the residential sector

Louis, J.-N. (Jean-Nicolas) 22 November 2016 (has links)
Abstract Achieving the objective of a decarbonised economy by 2050 will require massive efforts in the energy sector. Emissions from residential houses will have to be almost completely cut, by around 90% by 2050. Home automation is a potential tool for achieving this goal. However, the environmental and economic benefits of automation technologies first need to be assessed. This thesis evaluates the impact of home automation for electricity management in the residential sector using environmental and economic indicators. To this end, a life cycle assessment was performed to evaluate the impacts of the manufacturing, use and disposal phases. The influences of end-user behaviour, household size and multiple levels of technological deployment were also investigated. A Markov chain simulation tool, built on the MatLab platform, was developed to assess all possible combinations of impacting factors. Dynamic environmental indicators were developed based on the ReCiPe method for aggregating the impacts of processes. All these indicators were then combined to form a single index based on multi-criteria acceptability analysis. The results suggest that home automation can decrease peak load, but that overall electricity consumption may increase due to electricity use by the actual automation system. The effect of home automation was more noticeable in larger households than in one-person households. In addition, use of dynamic environmental indicators proved more relevant than fixed indicators to represent the environmental impact of home automation. Within the life cycle of automation technology, the manufacturing phase had the highest impact, but most of the CO2 emissions originated from the use phase. In conclusion, the most important environmental benefit of home automation is reducing CO2 emissions during peak time by load shifting. / Tiivistelmä Vähähiilisen talouden saavuttaminen vuoteen 2050 mennessä edellyttää valtavia ponnisteluja energia-alalla. Rakennuksista aiheutuvia päästöjä on vähennettävä radikaalisti, jopa 90 % vuoteen 2050 mennessä. Rakennusten energiatehokkuutta edistävä automaatiotekniikka on yksi keino tämän päämäärän saavuttamiseen. Kotiautomaation kautta voidaan sekä vähentää energian kokonaiskulutusta että tasoittaa energiankäyttöprofiilia. On kuitenkin tutkittava myös, mitkä ovat automaatiotekniikan ympäristö- ja taloudelliset vaikutukset. Tässä työssä käsitellään kotiautomaation vaikutusta sähkön kulutuksen hallintaan asuinrakennuksissa käyttämällä ympäristö- ja talousindikaattoreita. Tätä varten suoritettiin kotiautomaation elinkaariarviointi selvittämällä laitteiden valmistus-, käyttö- ja hävittämisvaiheiden ympäristövaikutukset. Työssä tarkasteltiin myös asukkaiden käyttäytymisen, kotitalouden koon ja eri teknologiavaihtoehtojen vaikutuksia ympäristö- ja talousvaikutuksiin. Arviointi suoritettiin Markovin ketjun simulointityökalulla, joka rakennettiin Matlab-alustalle. Dynaamisia ympäristömittareita kehitettiin ReCiPe-menetelmää käyttäen. Indikaattorit on edelleen yhdistetty yhdeksi indeksiksi käyttäen monikriteeriarviointia. Tulokset viittaavat siihen, että huippukuormitusta voidaan vähentää käyttämällä kotiautomaatiota, mutta sähkön kokonaiskulutus voi kasvaa automaatiojärjestelmän sähkönkulutuksen takia. Kotiautomaation vaikutukset ovat eniten havaittavissa suurissa kotitalouksissa. Lisäksi, dynaamiset indikaattorit edustavat paremmin kotiautomaation vaikutusta ympäristöön kuin staattiset indikaattorit. Automaatioteknologian elinkaaressa suurimmat ympäristövaikutukset ovat valmistusvaiheessa, mutta CO2-päästöjä syntyy eniten käyttövaiheessa. Lopuksi voidaan todeta, että kotiautomaation merkittävin ympäristöhyöty on CO2-päästöjen vähentäminen huippukulutuksen aikana siirtämällä kuormitusta toiseen ajankohtaan.
24

Cycle de vie de systèmes photovoltaïques organiques 3ème génération : élaboration d'un cadre pour étudier les avantages et les risques des technologies émergentes / Life-cycle assessment of 3rd-generation organic photovoltaic systems : developing a framework for studying the benefits and risks of emerging technologies

Tsang, Michael 07 December 2016 (has links)
Les systèmes photovoltaïques organiques sont des technologies émergentes présentant de forts potentiels d’économie de ressources et de réduction des impacts sur l'environnement et la santé humaine par rapport aux dispositifs photovoltaïques conventionnels. La méthode de l’analyse du cycle de vie est appliquée afin d'évaluer la façon dont les différents procédés de fabrication, les caractéristiques des dispositifs, la phase d’utilisation et les scénarios de fin de vie des cellules photovoltaïques organiques influent sur ces avantages potentiels. Les impacts de cette technologie émergente sont comparés aux technologies conventionnelles à base de silicium pour établir un référentiel de performance des technologies photovoltaïques.En outre, les effets potentiels sur la santé humaine de l'utilisation de nanomatériaux dans les cellules photovoltaïques organiques ont été spécifiquement étudiés ; et la pertinence de l’analyse du cycle de vie pour évaluer cette catégorie d’impact a été examinée. Ainsi, un nouveau modèle d'évaluation de l'impact sur le cycle de vie est présenté afin de quantifier les dangers potentiels posés par les nanomatériaux. Enfin,ces impacts potentiels sont comparés aux avantages des cellules photovoltaïques organiques sur les cellules à base de silicium. / Organic photovoltaics present an emerging technology with significant potential for increasing the resource efficiencies and reducing the environmental and human health hazards of photovoltaic devices. The discipline of life-cycle assessment is applied to assess how various prospective manufacturing routes, device characteristics, uses and disposal options of organic photovoltaics influences these potential advantages. The results of this assessment are further compared to silicon based photovoltaics as a benchmark for performance. A deeper look is given to the potential human health impacts of the use of engineered nanomaterials in organic photovoltaics and the appropriateness of life-cycle assessment to evaluate this impact criteria. A newly developed life-cycle impact assessment model is presented to demonstrate whether the use of and potential hazards posed by engineered nanomaterials outweighs any of the resource efficiencies and advantages organic photovoltaics possess over silicon photovoltaics.

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