Effets des sollicitations aérodynamiques sur la croissance et le développement du Pin maritime (Pinus pinaster Aït.) - Influence sur la morphogénèse aérienne et racinaire, et sur la formation du bois de coeur.

Le but de cette thèse est de soulever l'importance de la stimulation des plantes par le vent quotidien dans leur croissance et leur développement, en utilisant le pin maritime (Pinus pinaster Aït.) comme espèce modèle. Une analyse biomécanique préliminaire détermine les facteurs physiques et biologiques à mettre en relation pour rendre compte qualitativement de la réponse d'un arbre au vent. Une étude expérimentale exploratoire en plein champ et sur 3 ans, basée sur un mécanisme de ventilation inédit et spécifiquement intermittent, est ensuite proposée en complément de cet état de l'art. Elle aboutit à plusieurs résultats très inattendus. Le premier est le rôle prépondérant de la direction et de la fréquence des stimulations aérodynamiques lorsque celles-ci sont modérées, dans la morphogenèse des tiges et des racines du semis. La répétition et l'abrasion par érosion confèrent un caractère sélectif à l'exposition proposée, au stade précoce. Mais les semis développent par la suite une meilleure croissance ainsi qu'un héliotropisme et une réponse gravitropique au basculement nettement exacerbés par rapport aux conditions naturelles de croissance. L'importance relative des contraintes mécaniques et des transferts de masse dans les mécanismes de croissance doit être prise en compte. Une investigation dendrométrique de la structure interne du tronc est abordée pour finir chez l'arbre adulte, en relation avec son exposition aux vents dominants d'ouest. L'hypothèse d'une contribution des sollicitations mécaniques de l'aubier à la formation irrégulière du duramen chez le pin maritime, notamment celles induites par le vent quotidien (fatigue) ou les tempêtes (rupture) est alors proposée. Mais en dépit de nombreux indices favorables à cette théorie strictement mécanique, d'autres facteurs physiques et physiologiques sont également explicatifs, comme ceux concernant l'activité hydraulique de l'aubier.The aim of this thesis was to study the importance of everyday wind loading on the growth of Maritime pine (Pinus pinaster Aït.). A preliminary biomechanical analysis determined the mechanical and biological factors to be analysed in order to evaluate tree response to wind stress. Experimental studies were carried out in a novel artificial wind device set up in the field. Results were highly surprising in that not only low wind speeds modified root and shoot morphogenesis in young seedlings, but that the frequency and direction of loading also play an important role. Phototropism was particularly pronounced and abrasion of windblown soil particles on the shoot would increase the selective character of the repeated mechanical stress. Growth in these seedlings was also significantly greater compared to control plants and may be due to changes in mass transfer at the air-leaf boundary. In artificially inclined saplings exposed to wind stress, straightening up of stems was greater compared to the control plants. Cross sections of these stems were also highly eccentric with reaction wood. In mature trees, a dendrometrical analysis of the trunk was carried out, with regards to the prevailing wind direction. Several hypotheses are proposed to explain the irregular transformation of sapwood into heartwood, with particular reference to the influence of mechanical stress. In spite of numerous indications favourable to this hypothesis, other physical and physiological factors appear to be determinant, in particular concerning the hydraulic activity of sap wood

Le développement expérimental en situation de projet

L’activité de recherche et développement (R&D) regroupe les travaux de la recherche fondamentale, de la recherche appliquée et du développement expérimental. Ce dernier concerne les travaux d’expérimentation pratique obtenus à partir d’installations pilotes ou de prototypes. Cet article vise à explorer cette notion de développement expérimental appliquée à l’architecture grâce à l’analyse détaillée de trois projets de l’agence Lipsky+Rollet : les logements étudiants du campus de Troyes, la Maison de l’Inde à la Cité universitaire de Paris et le concours « Habitat positif » à Boulogne. Chacun de ces trois projets repose sur des modes constructifs en bois innovants qui expérimentent les qualités techniques, physiques et écologiques du matériau. Le travail des architectes porte sur la recherche de compatibilités possibles entre des dispositifs constructifs initialement développés dans l’isolement de leurs secteurs industriels réciproques. Ces sous-ensembles techniques préfabriqués doivent alors trouver leurs places dans la complexité du projet d’architecture qui les assemble selon ses propres règles et ses objectifs multiples. Cette étape de prototypage en situation de projet est cruciale car, selon la formule d’Edgar Morin, « une société qui n’expérimente plus n’innove plus, elle doit alors importer des modèles ». Cette activité expérimentale fait du projet architectural un outil de connaissance. L’édifice ne doit plus être compris comme un simple domaine d’application de solutions techniques élaborées en amont, mais comme un milieu d’expérimentation nécessaire à leur développement. Son objet porte sur les synergies architecturales et techniques possibles entre des systèmes et des modes constructifs d’origines diverses qui n’ont jamais été pensés ensemble au préalable dans les domaines des recherches fondamentale et appliquée. L’exemple du travail de l’agence de Lipsky+Rollet nous montre ce que pourrait être une forme de R&D spécifique à l’architecture pour autant qu’elle parvienne à réformer un cadre professionnel inadapté, et à rendre explicites ses méthodes.Research and development (R&D) activity helps to consolidate the work of fundamental research, applied research, and experimental development - the latter dealing with experimental work practice obtained at pilot installations or prototypes. This article seeks to explore this notion of applied experimental development within architecture through the examination of three detailed projects from Lipsky + Rollet’s agency which are: Student housing on Troyes campus, the Indian House at La Cité Universitaire de Paris, and the “Positive Habitat” competition in Bologne. Each of these projects explore different means of innovative construction, all of which use wood as their primary building material and experiment with its technical, physical and ecological qualities. The work of these architects poses research enquiries about the compatibility between construction materials that were initially developed in isolation from their reciprocal industrial sectors. These prefab technical sub-assemblies must find their place within the complexities of architectural projects which are assembled based on their own rules and objectives. According to Edgar Morin’s formula, a company that no longer experiments is no longer innovative and must therefore import other models externally, making this step in situational prototyping of projects crucial. This experimental activity creates a tool for knowledge out of architectural projects and thus the edifice should no longer be understood as a simple domain for applying upstream elaborated technical solutions, rather as an experimental milieu which is necessary for its development. Its purpose is to bring diverse systems and original constructive means to architectural synergies as well as possible techniques that have yet to be seen together in fundamental and applied research domains. The example of Lipsky + Rollet’s work shows us what could be a form of R&D particular to architecture for those who have managed to reform unsuitable professional frameworks and to explicitly render its methods accordingly

Arcueil – 10 rue Paul-Vaillant-Couturier

Un diagnostic archéologique a eu lieu à l’emplacement des laboratoires de la société lnnothera du 18 mai au 7 juin 1998. Implanté à une soixantaine de mètres de la rive droite de la Bièvre canalisée, le site a été sondé en trois tranchées dont la localisation fut imposée par l’existence d’un bâtiment encore en élévation. Les trois tranchées ont révélé un mobilier céramique Bas-Empire et haut Moyen Âge, au sein de niveaux qui ne semblent pas perturbés. Parmi les structures découvertes, signalo..

Pseudoentropic Isometries: A New Framework for Fuzzy Extractor Reusability

Fuzzy extractors (Dodis \textit{et al.}, Eurocrypt 2004) turn a noisy secret into a stable, uniformly distributed key. \textit{Reusable} fuzzy extractors remain secure when multiple keys are produced from a single noisy secret (Boyen, CCS 2004). Boyen proved that any information-theoretically secure reusable fuzzy extractor is subject to strong limitations. Simoens \textit{et al.} (IEEE S\&P, 2009) then showed deployed constructions suffer severe security breaks when reused. Canetti \textit{et al.} (Eurocrypt 2016) proposed using computational security to sidestep this problem. They constructed a computationally secure reusable fuzzy extractor for the Hamming metric that corrects a \emph{sublinear} fraction of errors. We introduce a generic approach to constructing reusable fuzzy extractors. We define a new primitive called a \emph{reusable pseudoentropic isometry} that projects an input metric space to an output metric space. This projection preserves distance and entropy even if the same input is mapped to multiple output metric spaces. A reusable pseudoentropy isometry yields a reusable fuzzy extractor by 1) randomizing the noisy secret using the isometry and 2) applying a traditional fuzzy extractor to derive a secret key. We propose reusable pseudoentropic isometries for the set difference and Hamming metrics. The set difference construction is built from composable digital lockers (Canetti and Dakdouk, Eurocrypt 2008) yielding the first reusable fuzzy extractor that corrects a {\it linear} fraction of errors. For the Hamming metric, we show that the second construction of Canetti \textit{et al.} (Eurocrypt 2016) can be seen as an instantiation of our framework. In both cases, the pseudoentropic isometry\u27s reusability requires noisy secrets distributions to have entropy in each symbol of the alphabet. Lastly, we implement our set difference solution and describe two use cases

Physical Properties of (2) Pallas

We acquired and analyzed adaptive-optics imaging observations of asteroid (2) Pallas from Keck II and the Very Large Telescope taken during four Pallas oppositions between 2003 and 2007, with spatial resolution spanning 32-88 km (image scales 13-20 km/pix). We improve our determination of the size, shape, and pole by a novel method that combines our AO data with 51 visual light-curves spanning 34 years of observations as well as occultation data. The shape model of Pallas derived here reproduces well both the projected shape of Pallas on the sky and light-curve behavior at all the epochs considered. We resolved the pole ambiguity and found the spin-vector coordinates to be within 5 deg. of [long, lat] = [30 deg., -16 deg.] in the ECJ2000.0 reference frame, indicating a high obliquity of ~84 deg., leading to high seasonal contrast. The best triaxial-ellipsoid fit returns radii of a=275 km, b= 258 km, and c= 238 km. From the mass of Pallas determined by gravitational perturbation on other minor bodies [(1.2 +/- 0.3) x 10-10 Solar Masses], we derive a density of 3.4 +/- 0.9 g.cm-3 significantly different from the density of C-type (1) Ceres of 2.2 +/- 0.1 g.cm-3. Considering the spectral similarities of Pallas and Ceres at visible and near-infrared wavelengths, this may point to fundamental differences in the interior composition or structure of these two bodies. We define a planetocentric longitude system for Pallas, following IAU guidelines. We also present the first albedo maps of Pallas covering ~80% of the surface in K-band. These maps reveal features with diameters in the 70-180 km range and an albedo contrast of about 6% wrt the mean surface albedo.Comment: 16 pages, 8 figures, 6 table

Création architecturale et industrialisation de la filière bois : l'architecture comme milieu d'expérimentation des innovations techniques

This research questions the notion of experimentation in technical innovations in architecture. It aims at elucidating the methods, stakes, and limits concerning both the profession of architect and the theory of architecture. It suggests that architecture is not a domain where construction techniques, seen as instrumental means resulting from an upstream work, are put in application, but a field of experimentation for these techniques, an essential step in their development and adjustment in more complex situations. Architecture is also an area of critical reflections on our ways of behaving and building, for which techniques are in planning.The field of research is that of timber architecture in France, from its industrial resurgence in the second half of the 20th century to the present. This field condenses, in a relatively short period of time, the building experimentations with a material that was first considered archaic after the war, then raised to the status of a modern material from the 1960s, to be acknowledged as the leading material for ecological construction. It allows us to examine the transition from arts and crafts to industry, the evolution of the methods, of the tools of production, from hand-operated to mechanical to digital, and their influence on architecture. Simultaneously, it enables us to delve into, based on a single raw material, the attitude of cultural acceptance from our industrial technologies – depending on whether architecture showcases timber as a modern and processed material or as a raw and natural resource – between the fascination for technical progress and a criticism of the industrial society.The chosen format is that of a thesis based on regularly published articles during the research phase. Each of the seven articles consists of a case study on a specific innovation during the selected time period, cross-referencing architectural and building analyses. The composition as a whole converges to establish a survey of the different forms taken by technical innovations in architecture and highlights some consistencies in the experimental process, the main consistency being the transfer of innovation.This research seeks to clarify this process of creative and rational experimentation which has its own methods, tools, temporalities, modes of evaluation and of capitalization of knowledge, distinct from the canons of scientific experimentation. The findings of this thesis prompt a new approach to teaching techniques in architecture schools, through reviving their links with architectural creation.Cette recherche interroge la notion d’expérimentation des innovations techniques en architecture. Elle vise à en expliciter les modalités, les enjeux et les limites pour le métier d’architecte et pour la théorie de l’architecture. Elle montre que l’architecture n’est pas un domaine d’application des techniques de construction, pensées comme des moyens instrumentaux élaborés en amont, mais qu’elle est un milieu d’expérimentation des techniques, essentiel à leur développement et à leur adaptation en situation complexe. L’architecture est aussi un champ de réflexions critiques sur nos manières d’agir et de construire, dans lequel la technique est en projet.Le terrain de recherche est celui de l’architecture de bois en France depuis son renouveau industriel dans la seconde moitié du XXe jusqu’à aujourd’hui. Il condense sur une période relativement courte les expérimentations constructives d’un matériau d’abord perçu comme archaïque après-guerre, puis élevé au rang de matériau moderne à partir des années 1960 et enfin reconnu comme le matériau phare de la construction écologique. Il offre la possibilité d’observer le passage de l’artisanat à l’industrie, l’évolution des méthodes et outils de production manuels, mécaniques puis numériques et leurs influences sur l’architecture. Il offre en même temps l’occasion d’étudier, à partir d’une unique matière première, l’état d’acceptabilité culturelle de nos technologies industrielles, selon que l’architecture met en avant le bois en tant que matériau moderne et transformé, ou en tant que matériau brut et naturel, entre fascination pour le progrès technique et critique de la société industrielle.Le format choisi est celui d’une thèse sur articles régulièrement publiés durant la recherche. Chacun des sept articles constitue l’étude de cas d’une situation d’innovation particulière dans la période considérée, en croisant les analyses architecturales et constructives. L’ensemble converge pour établir un relevé des différentes formes de l’expérimentation des innovations techniques en architecture et met en évidence certaines régularités de la démarche expérimentale dont la principale est le transfert d’innovation.Cette recherche tente de rendre explicite ce processus d’expérimentation créatif et réflexif, qui dispose de ses propres modalités, outils, temporalités, modes d’évaluation et de capitalisation de connaissances, distincts des canons de l’expérimentation scientifique. Les connaissances que cette thèse élabore invitent à renouveler l’enseignement des techniques dans les écoles d’architecture, en renouant leurs liens avec la création architecturale

Architectural design and the industrialization of the timber construction architecture as a field of experimentation of technical innovation

Cette recherche interroge la notion d’expérimentation des innovations techniques en architecture. Elle vise à en expliciter les modalités, les enjeux et les limites pour le métier d’architecte et pour la théorie de l’architecture. Elle montre que l’architecture n’est pas un domaine d’application des techniques de construction, pensées comme des moyens instrumentaux élaborés en amont, mais qu’elle est un milieu d’expérimentation des techniques, essentiel à leur développement et à leur adaptation en situation complexe. L’architecture est aussi un champ de réflexions critiques sur nos manières d’agir et de construire, dans lequel la technique est en projet.Le terrain de recherche est celui de l’architecture de bois en France depuis son renouveau industriel dans la seconde moitié du XXe jusqu’à aujourd’hui. Il condense sur une période relativement courte les expérimentations constructives d’un matériau d’abord perçu comme archaïque après-guerre, puis élevé au rang de matériau moderne à partir des années 1960 et enfin reconnu comme le matériau phare de la construction écologique. Il offre la possibilité d’observer le passage de l’artisanat à l’industrie, l’évolution des méthodes et outils de production manuels, mécaniques puis numériques et leurs influences sur l’architecture. Il offre en même temps l’occasion d’étudier, à partir d’une unique matière première, l’état d’acceptabilité culturelle de nos technologies industrielles, selon que l’architecture met en avant le bois en tant que matériau moderne et transformé, ou en tant que matériau brut et naturel, entre fascination pour le progrès technique et critique de la société industrielle.Le format choisi est celui d’une thèse sur articles régulièrement publiés durant la recherche. Chacun des sept articles constitue l’étude de cas d’une situation d’innovation particulière dans la période considérée, en croisant les analyses architecturales et constructives. L’ensemble converge pour établir un relevé des différentes formes de l’expérimentation des innovations techniques en architecture et met en évidence certaines régularités de la démarche expérimentale dont la principale est le transfert d’innovation.Cette recherche tente de rendre explicite ce processus d’expérimentation créatif et réflexif, qui dispose de ses propres modalités, outils, temporalités, modes d’évaluation et de capitalisation de connaissances, distincts des canons de l’expérimentation scientifique. Les connaissances que cette thèse élabore invitent à renouveler l’enseignement des techniques dans les écoles d’architecture, en renouant leurs liens avec la création architecturale.This research questions the notion of experimentation in technical innovations in architecture. It aims at elucidating the methods, stakes, and limits concerning both the profession of architect and the theory of architecture. It suggests that architecture is not a domain where construction techniques, seen as instrumental means resulting from an upstream work, are put in application, but a field of experimentation for these techniques, an essential step in their development and adjustment in more complex situations. Architecture is also an area of critical reflections on our ways of behaving and building, for which techniques are in planning.The field of research is that of timber architecture in France, from its industrial resurgence in the second half of the 20th century to the present. This field condenses, in a relatively short period of time, the building experimentations with a material that was first considered archaic after the war, then raised to the status of a modern material from the 1960s, to be acknowledged as the leading material for ecological construction. It allows us to examine the transition from arts and crafts to industry, the evolution of the methods, of the tools of production, from hand-operated to mechanical to digital, and their influence on architecture. Simultaneously, it enables us to delve into, based on a single raw material, the attitude of cultural acceptance from our industrial technologies – depending on whether architecture showcases timber as a modern and processed material or as a raw and natural resource – between the fascination for technical progress and a criticism of the industrial society.The chosen format is that of a thesis based on regularly published articles during the research phase. Each of the seven articles consists of a case study on a specific innovation during the selected time period, cross-referencing architectural and building analyses. The composition as a whole converges to establish a survey of the different forms taken by technical innovations in architecture and highlights some consistencies in the experimental process, the main consistency being the transfer of innovation.This research seeks to clarify this process of creative and rational experimentation which has its own methods, tools, temporalities, modes of evaluation and of capitalization of knowledge, distinct from the canons of scientific experimentation. The findings of this thesis prompt a new approach to teaching techniques in architecture schools, through reviving their links with architectural creation

Le développement expérimental en situation de projet

Research and development (R&D) activity helps to consolidate the work of fundamental research, applied research, and experimental development - the latter dealing with experimental work practice obtained at pilot installations or prototypes. This article seeks to explore this notion of applied experimental development within architecture through the examination of three detailed projects from Lipsky + Rollet’s agency which are: Student housing on Troyes campus, the Indian House at La Cité Universitaire de Paris, and the “Positive Habitat” competition in Bologne. Each of these projects explore different means of innovative construction, all of which use wood as their primary building material and experiment with its technical, physical and ecological qualities. The work of these architects poses research enquiries about the compatibility between construction materials that were initially developed in isolation from their reciprocal industrial sectors. These prefab technical sub-assemblies must find their place within the complexities of architectural projects which are assembled based on their own rules and objectives. According to Edgar Morin’s formula, a company that no longer experiments is no longer innovative and must therefore import other models externally, making this step in situational prototyping of projects crucial. This experimental activity creates a tool for knowledge out of architectural projects and thus the edifice should no longer be understood as a simple domain for applying upstream elaborated technical solutions, rather as an experimental milieu which is necessary for its development. Its purpose is to bring diverse systems and original constructive means to architectural synergies as well as possible techniques that have yet to be seen together in fundamental and applied research domains. The example of Lipsky + Rollet’s work shows us what could be a form of R&D particular to architecture for those who have managed to reform unsuitable professional frameworks and to explicitly render its methods accordingly

Righting response of artificially inclined maritime pine (Pinus pinaster) saplings to wind loading

International audienceTo determine if trees respond to dynamic and static loading in the same manner, 2-year-old maritime pine (Pinus pinaster Ait.) trees were subjected to different types of mechanical loading in the field. One block of trees (the control) were kept in pots and planted in the field at an angle of 0 or 45 degrees to the vertical. A similar block of leaning potted trees was planted nearby and Subjected to frequent, unilateral wind loading for a period of 1 s every 2 min. Half the leaning trees were oriented toward the direction of wind loading and half were oriented along the axis of wind loading. The stem profile was measured three times during the growing season to quantify the rate of stem straightening. Compression wood formation and stem shape were measured in all plants. No differences in mean height or diameter were observed between blocks and all leaning trees straightened, but not at the same rate. Although no difference in the rate of apical straightening occurred between control and wind-treated trees, the righting response of the basal part of the stem of leaning trees subjected to wind was four times greater than that of leaning trees without wind