ED Entreprise Economie Société
Three essays on biodiversity conservation tools
by Céline HUBER (BSE - Bordeaux sciences économiques)
The defense will take place at 14h00 - Salle des thèses Université de Bordeaux, 16 avenue Léon Duguit, 33600 Pessac
in front of the jury composed of
- Sylvie FERRARI - Professeure des universités - Université de Bordeaux - Directeur de these
- Pascale COMBES-MOTEL - Professeure des universités - Université Clermont Auvergne - Rapporteur
- Tina RAMBONILAZA - Directrice de recherche - INRAE - Rapporteur
- Marc LEANDRI - Maître de conférences - Université Versailles Saint-Quentin-En-Yvelines - Examinateur
- Sébastien ROUILLON - Professeur des universités - Université de Bordeaux - Examinateur
- Luc DOYEN - Directeur de recherche - CNRS - CoDirecteur de these
Controversies surrounding land use change and biodiversity conservation reflect growing tensions between environmental and economic priorities. While there is broad agreement on the paradox that human societies depend on nature to thrive, they must also adapt their infrastructure to meet basic needs. In practice, however, human development often proceeds at the expense of natural areas and biodiversity. Land use change and habitat loss are among the primary drivers of global biodiversity decline (IPBES, 2019). Here, we choose to address three instruments aimed at addressing biodiversity loss and promoting sustainability, namely Biodiversity Offsets (BOs) (economic instruments), conservation reserves or protected areas, and voluntary approaches. Other instruments include regulations (command-and-control approaches) and education and awareness measures (Darbi, 2020; Earl et al., 2010). The key contributions of these works are both practical through modeling approaches and theoretical through field exploration. Three case studies illustrate our approach, including two located in mangroves on the western coast of Madagascar, and one in Brussels, Belgium, derived from a development project that sparked controversy over the sharing of land use in recent years. We first focused on the definition of a model that aims to reconcile economic development and the necessary recovery time gap of biodiversity to propose an Offset Sustainable Price (OSP) per unit of developed land. The concept of Biodiversity Offsets was born around the 1970's in the United States of America (USA) and became popular since the 2010's. Much debated, it is perceived as the main solution to reconcile economic development and biodiversity conservation. We developed a multicriteria, dynamic, and spatiallyexplicit model aimed at reconciling economic and ecological objectives. The application to mangroves and aquaculture in Mahajamba bay, Madagascar, illustrates the analytical findings and, in particular, that the current price of BOs is too low. Secondly, through field exploration and a more institutional approach, we applied the Ostromian framework to identify the fairness of a delegated management of a mangrove ecosystem to local communities, located in the Menabe region, Madagascar. We examined the various dimensions of environmental justice to assess management practices and issue recommendations. Third, we produced a common framework combining the acCA and the acVT to produce a multi-criteria - including aspects of well-being, a dynamic approach and consistent with a strong sustainability perspective and the United Nations (UN) . It emphasises the collective aspect of sustainable land sharing decisions.
ED Sciences Physiques et de l'Ingénieur
Functionalisation of laminated composites in a cryogenic environment for the control of long-term hydrogen permeation
by Timothée KLEIN (I2M - Institut de Mécanique et d'Ingénierie de Bordeaux)
The defense will take place at 10h30 - Salle de conférence de l'ISM Université de Bordeaux, 3°étage du bâtiment A12 (campus Peixotto) 33405 Talence
in front of the jury composed of
- Christophe BOIS - Professeur des universités - Université de Bordeaux - Directeur de these
- Philippe OLIVIER - Professeur des universités - Université Paul Sabatier - Rapporteur
- Frédéric LAURIN - Directeur de recherche - ONERA - Rapporteur
- Federica DAGHIA - Maîtresse de conférences - ENS Paris-Saclay - Examinateur
- Pedro CAMANHO - Professeure des universités - Université de Porto - Examinateur
- Caroline PETIOT - Docteure - Airbus SAS - Examinateur
In the context of the aviation sector's decarbonisation efforts, Airbus has the ambition to bring a hydrogen-powered commercial aircraft to market. The development of linerless cryogenic composite tanks is a major challenge in enhancing the performance and cost-effectiveness of future commercial aircraft. This implies that tightness must be ensured by the composite itself at very low temperatures, which is a major challenge. This CIFRE thesis therefore focuses on understanding the mechanisms of transverse cracking in two candidate composite materials, and its repercussions on their permeability. These are unidirectional carbon fibre composites in a thin ply configuration (70µm), one with a thermoset matrix and the other with a thermoplastic matrix. A first experimental campaign on flat specimens was carried out to identify the thermomechanical properties of the unit ply, and to study its transverse cracking behaviour in several types of stacking sequences and configurations. Various functionalisation strategies, such as the addition of a thermoplastic polymer film and variation in the cross-link density of the thermoset matrix, as well as the influence of water absorption on the materials' transverse cracking behaviour, were evaluated at cryogenic temperatures. A second experimental campaign on tubular specimens built upon these initial results. The tubular geometry making it possible to combine thermomechanical loading with measurements of the resulting permeability due to damage. The results showed a significant influence of the polymer matrix type and ply thickness on the crack network architecture. This led to complementary tests being carried out on neat thermoplastic resin samples, to feed the analysis with multi-scale modelling. Two types of numerical approach were used in this work. The first is based on explicit modelling of cracks at the scale of the ply, using Finite Fracture Mechanics (FFM). The model successfully reproduces the trends observed in experiments, but it was necessary to make the additional assumption that damage follows a crack resistance curve, or R curve. A second numerical model, this time on the scale of individual constituents (micromechanics), was then developed. This enables the influence of the intrinsic properties of the constituents to be assessed, particularly that of the thermoplastic matrix. The configurations tested experimentally were reproduced numerically using a 2D cell, embedded within homogenised plies. Finally, based on the properties identified experimentally, this model was used to assess the crack resistance curve using a cell representative of the configuration under consideration.
ED Sociétés, Politique, Santé Publique
Word Imageability and lexico-semantic processes : Individual and lexical determinants
by Sandra AKA (Laboratoire de Psychologie)
The defense will take place at 14h00 - Amphi Leyteire (Amphi E) 3ter Place de la Victoire, Bâtiment E, 33000, Bordeaux
in front of the jury composed of
- Stéphanie MATHEY - Professeure des universités - Université de Bordeaux - Directeur de these
- Nathalie HUET - Professeure des universités - Université Toulouse 2 - Rapporteur
- Arielle SYSSAU-VACARELLA - Professeure des universités - Université Montpellier 3 - Rapporteur
- Boris NEW - Professeur des universités - Université Savoie Mont-Blanc - Examinateur
- Christelle ROBERT - Professeure des universités - Université de Bordeaux - Examinateur
Words differ in the ease with which they can evoke sensory mental images in a reader's mind. Imageability is thought to reflect the richness of semantic information—particularly sensory—associated with words in memory. Numerous studies have shown that highly imageable words (e.g., strawberry) are easier to read and remember than low-imageability words (e.g., entity), highlighting the central role of imageability in written word processing. Research on this factor has been instrumental in developing theories of language processing and the format in which word meaning is represented in memory. However, recent work has questioned the validity of the imageability construct due to variability in its effects, while failing to identify the underlying causes. The main objective of this thesis was to clarify the cognitive processes underlying imageability effects in written word processing, and their sources of variability in adulthood. More specifically, we aimed to 1) identify predictors of perceived word imageability; 2) specify the lexico-semantic determinants of variability in imageability effects in tasks involving written word identification and 3) determine the role of individual differences in vocabulary and mental imagery in the imageability effect of young and older adults. To this end, we combined analyses of lexico-semantic norms, megastudies, and experimental studies including individual difference measures. We first analysed imageability norms (Study 1) and examined the lexical and semantic predictors of imageability effects using a previously published mega-study (Study 2). We then validated an assessment of multisensory mental imagery for French-speaking adults (Study 3) in order to explore the roles of mental imagery and vocabulary in imageability ratings (Study 4). Finally, we experimentally investigated how word and participant characteristics modulated the imageability effects: in young adults, using progressive demasking (Study 5) and recognition memory tasks (Study 6); and in a lexical decision task comparing young and older adults (Study 7). Our results show that imageability ratings emerge from an interaction between word-level properties and individual characteristics, such as imagery abilities (Studies 1 and 4). A facilitatory imageability effect was found in visual word recognition (Studies 2, 5, and 7) and recognition memory (Study 6). Moreover, the imageability effect was modulated by semantic ambiguity (Study 5) and word emotionality (Study 6). In young adults, the imageability effect was not influenced by vocabulary or imagery abilities (Studies 5–7). Comparatively, older adults showed a larger benefit from imageability, an effect which was further accentuated for individuals with a lower vocabulary (Study 7). Altogether, our findings provide evidence of robust imageability effects in adulthood, supporting the validity of the imageability construct and its measurement as well as the semantic locus of its effects. This original investigation of the links between imageability ratings, imageability effects and individual differences provides new insights, which we discuss in terms of mental representations and cognitive processes. We propose that imageability be situated at the interface between interactive activation models and embodied accounts of language and cognition.