1,721,017 research outputs found
Reliability and environmental impact assessment of wind farms
No full textLe développement croissant des parcs éoliens sur le territoire français est l'un des leviers majeurs en faveur de l'intégration des énergies renouvelables dans le mixte énergétique national. Cependant, ce dernier se heurte à des problématiques de maintenabilité et des incertitudes sur la durée de vie, d’autant plus que la gestion de fin de vie de ces parcs n’est qu’à ses débuts. Actuellement, peu de travaux traitent de l'évaluation de la performance globale (dont performance technologique et environnementale) de ces systèmes.Ce projet de thèse se propose d'améliorer et de développer des méthodes d'évaluation de la performance technologique (sûreté de fonctionnement) et d’évaluer le gisement de fin de vie de l’éolien dans la région Champagne-Ardenne. Il s'agit, d'une part, de réaliser une étude de sûreté de fonctionnement du système éolien avec un focus sur la fiabilité et la maintenabilité du système en prenant en compte l'interdépendance de ses composants. En effet, cette dernière constitue un levier d'amélioration. D'autre part, l'évaluation de l'impact environnemental de ces installations est nécessaire afin de déterminer des critères de choix technologique et de topologie. Dans ce travail, la MFA et l'ACV comme support à l'écoconception, ont permis de quantifier le gisement en fin de vie, de réduire les impacts environnementaux durant toutes les phases de vie du système et améliorer la durabilité de ce dernier. De plus, des données de la région sont utilisées pour illustrer les résultats et développer des modèles économiques.World society now is concerned more than ever about environmental impacts that power plants generate in their lifetime cycles. This last concern provides an opportunity for wind energy to be more attractive than conventional power plants. However, literature shows that there is no consideration or only few works on assessing the global performance of these power plants. Besides, these performances are still assessed independently from each other’s. It is thus necessary to consider assessing reliability, availability and their influence on environmental impacts.To do so, we will improve and develop reliability and dependability methods and combine them to an environmental impact assessment protocol in this thesis. Indeed, a reliability assessment of systems with multiple components was made considering the combination of multiple dependencies in this system. This model was then injected in a maintenance policy with the consideration of components degradations. Then, an environmental based analysis considering the results of the reliability assessment was performed. This second step was based on MFA and LCA studies as tools of design for sustainability. It will thus help to reduce environmental impacts of wind turbine over its lifetime. The objective of these assessment methods is to enhance the sustainability of wind turbines. Results were illustrated using data from the Champagne-Ardenne region
Evaluation de la disponibilité et de l’Impact Environnemental des Parcs Eoliens (EDIPEO)
No full textWorld society now is concerned more than ever about environmental impacts that power plants generate in their lifetime cycles. This last concern provides an opportunity for wind energy to be more attractive than conventional power plants. However, literature shows that there is no consideration or only few works on assessing the global performance of these power plants. Besides, these performances are still assessed independently from each other’s. It is thus necessary to consider assessing reliability, availability and their influence on environmental impacts.To do so, we will improve and develop reliability and dependability methods and combine them to an environmental impact assessment protocol in this thesis. Indeed, a reliability assessment of systems with multiple components was made considering the combination of multiple dependencies in this system. This model was then injected in a maintenance policy with the consideration of components degradations. Then, an environmental based analysis considering the results of the reliability assessment was performed. This second step was based on MFA and LCA studies as tools of design for sustainability. It will thus help to reduce environmental impacts of wind turbine over its lifetime. The objective of these assessment methods is to enhance the sustainability of wind turbines. Results were illustrated using data from the Champagne-Ardenne region.Le développement croissant des parcs éoliens sur le territoire français est l'un des leviers majeurs en faveur de l'intégration des énergies renouvelables dans le mixte énergétique national. Cependant, ce dernier se heurte à des problématiques de maintenabilité et des incertitudes sur la durée de vie, d’autant plus que la gestion de fin de vie de ces parcs n’est qu’à ses débuts. Actuellement, peu de travaux traitent de l'évaluation de la performance globale (dont performance technologique et environnementale) de ces systèmes.Ce projet de thèse se propose d'améliorer et de développer des méthodes d'évaluation de la performance technologique (sûreté de fonctionnement) et d’évaluer le gisement de fin de vie de l’éolien dans la région Champagne-Ardenne. Il s'agit, d'une part, de réaliser une étude de sûreté de fonctionnement du système éolien avec un focus sur la fiabilité et la maintenabilité du système en prenant en compte l'interdépendance de ses composants. En effet, cette dernière constitue un levier d'amélioration. D'autre part, l'évaluation de l'impact environnemental de ces installations est nécessaire afin de déterminer des critères de choix technologique et de topologie. Dans ce travail, la MFA et l'ACV comme support à l'écoconception, ont permis de quantifier le gisement en fin de vie, de réduire les impacts environnementaux durant toutes les phases de vie du système et améliorer la durabilité de ce dernier. De plus, des données de la région sont utilisées pour illustrer les résultats et développer des modèles économiques
Evaluation de la disponibilité et de l’Impact Environnemental des Parcs Eoliens (EDIPEO)
No full textWorld society now is concerned more than ever about environmental impacts that power plants generate in their lifetime cycles. This last concern provides an opportunity for wind energy to be more attractive than conventional power plants. However, literature shows that there is no consideration or only few works on assessing the global performance of these power plants. Besides, these performances are still assessed independently from each other’s. It is thus necessary to consider assessing reliability, availability and their influence on environmental impacts.To do so, we will improve and develop reliability and dependability methods and combine them to an environmental impact assessment protocol in this thesis. Indeed, a reliability assessment of systems with multiple components was made considering the combination of multiple dependencies in this system. This model was then injected in a maintenance policy with the consideration of components degradations. Then, an environmental based analysis considering the results of the reliability assessment was performed. This second step was based on MFA and LCA studies as tools of design for sustainability. It will thus help to reduce environmental impacts of wind turbine over its lifetime. The objective of these assessment methods is to enhance the sustainability of wind turbines. Results were illustrated using data from the Champagne-Ardenne region.Le développement croissant des parcs éoliens sur le territoire français est l'un des leviers majeurs en faveur de l'intégration des énergies renouvelables dans le mixte énergétique national. Cependant, ce dernier se heurte à des problématiques de maintenabilité et des incertitudes sur la durée de vie, d’autant plus que la gestion de fin de vie de ces parcs n’est qu’à ses débuts. Actuellement, peu de travaux traitent de l'évaluation de la performance globale (dont performance technologique et environnementale) de ces systèmes.Ce projet de thèse se propose d'améliorer et de développer des méthodes d'évaluation de la performance technologique (sûreté de fonctionnement) et d’évaluer le gisement de fin de vie de l’éolien dans la région Champagne-Ardenne. Il s'agit, d'une part, de réaliser une étude de sûreté de fonctionnement du système éolien avec un focus sur la fiabilité et la maintenabilité du système en prenant en compte l'interdépendance de ses composants. En effet, cette dernière constitue un levier d'amélioration. D'autre part, l'évaluation de l'impact environnemental de ces installations est nécessaire afin de déterminer des critères de choix technologique et de topologie. Dans ce travail, la MFA et l'ACV comme support à l'écoconception, ont permis de quantifier le gisement en fin de vie, de réduire les impacts environnementaux durant toutes les phases de vie du système et améliorer la durabilité de ce dernier. De plus, des données de la région sont utilisées pour illustrer les résultats et développer des modèles économiques
Recyclability of Wind Turbines: Overview of Current Situation and Challenges
No full textInternational audienceThe European energy system is increasingly incorporating renewable energies as a result of the wind power market's exponential rise. However, from a life cycle standpoint, there still exists certain issues with wind turbines, especially in end-of-life management. In this study, an overview of the current state of a wind turbine's end-of-life management is provided. Turbines’ end-of-life management practices are a difficult endeavor for completing materials loops. The current state of play demonstrates that some materials used in wind turbines are still diverted towards energy recovery or landfills rather than more virtuous management such as recycling, remanufacturing or reuse, which hinder the recyclability and thus circularity of wind turbines. Blades, rare earth elements used in permanent magnets, and critical raw materials used in alloyed components are preventing wind turbines from achieving high recyclability. The remaining difficulties to improve recycling and close the material loop for wind turbines are then highlighted
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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