Les bâtiments actuels faits de pièces en béton préfabriqué utilisent généralement des assemblages qui n’offrent que peu ou pas de continuité à la structure. Il en résulte une sous utilisation importante des matériaux par rapport à une même structure se comportant de façon monolithique. Plusieurs études portant sur des assemblages rigides, soudés ou assemblés par post-tension, ont déjà été réalisées. Bien que structuralement viable, aucun de ces modèles ne s'est avéré capable de répondre pleinement aux besoins de l'industrie. Les tolérances de construction trop serrées et la complexité de réalisation ont souvent posé problème. Les travaux présentés ici portent donc sur le développement d'un assemblage rigide boulonné, utilisable à grande échelle, destiné à l'industrie du bâtiment multiétagé en béton préfabriqué. L'étude entreprise comporte deux phases, soit la conception du système structural et la détermination de la rigidité des assemblages. Les résultats obtenus sont utilisés afin de comparer le nouveau concept aux charpentes actuelles. La démarche d’analyse s’appuie sur le logiciel VisualDesign pour élaborer la structure du bâtiment, et sur le logiciel d’analyse par éléments finis ANSYS pour la caractérisation du comportement des assemblages. Les efforts de recherche ont été orientés de manière à établir la faisabilité du modèle, afin de permettre le développement futur de projets de recherche en partenariat avec l’industrie. / To this day, the connections of precast concrete buildings offer little or no continuity to the structure. Consequently, when compared to monolithic structures, the material is clearly not used to its full capacity. Studies on rigid connections, welded or assembled by post tension, have been carried out by a few investigators. Although structurally valid, none of the proposed connections proved able to meet the needs of the construction industry, due to stringent erection tolerances and complexity of assembly. The work presented here concerns the development of a bolted rigid connection system likely to be used on a large scale by the precast concrete construction industry. The study is separated in two parts. The first is concerned with the development and tuning of the new structural system while the second one deals with the determination of the rigidity of the proposed connection. The connection behaviour is then used to compare the amount of material used in the new system and the actual precast system. The software Visual Design was used to analyse the building structure, and the finite element software ANSYS to determine the characteristic behaviour of the new connection. The intent of the research is to establish the feasibility of the proposed model, so that future research and development efforts can be carried out in partnership with the precast industry.

Dans ce mémoire de thèse, nous proposons une contribution à la modélisation des assemblages avec une prise en compte des défauts de forme. Ce travail par la proposition d'une modélisation et d'une expérimentation essayera de répondre aux deux questions suivantes : comment obtenir une modélisation réaliste de la pièce ou du produit? Comment valider un modèle dans le cadre de la prise en compte des états de surface dans un assemblage de plusieurs pièces ? / PhD in Mechanics of solids

Thèse (Ph. D.)--Université Laval, 2007. / Titre de l'écran-titre (visionné le 5 mai 2008). Bibliogr.

Thèses (M.Sc.A.)--Université de Sherbrooke (Canada), 2002. / Titre de l'écran-titre (visionné le 13 juillet 2006). Publié aussi en version papier.

Thirteen oxbow lakes, 7 deep (>3.0 m) and 6 shallow (< 1.5m), were studied in the Yazoo River basin (YRB) to identify if divergent water quality characteristics and fish communities were common occurrences. Shallow lakes repeatedly experienced wide diel fluctuations in temperature and oxygen, reduced Secchi depth, and greater levels of suspended solids, turbidity, and chlorophyll-a. Fish communities were mostly comprised of orangespotted sunfish, juvenile crappies, gars, and various backwater fishes. Deep lakes exhibited improved conditions among all water quality variables and harbored fish communities comprised mostly of large-bodied and long-lived individuals, and piscivorous species. Furthermore, effects of smallmouth buffalo on water quality were examined at three different biomass levels in experimental ponds. Ponds with biomasses at 220 and 65 kg ha-1 responded with reduced visibility, elevated turbidity and suspended solids, and lower oxygen levels. These two studies combined provide valuable insight into shallow lake management in the YRB.

The numerous studies on the effects of patch size on bird assemblages have produced varied results. I studied the effects of patch size and surrounding matrix on bird assemblages within central Florida cypress domes. My null hypothesis was that bird assemblages within cypress domes are unaffected by dome size or development in the matrix around the dome. My alternative hypothesis was that differences in bird assemblages are correlated with size and the degree of development within the matrix. I classified a pool of over a thousand domes according to three size categories and four matrix types. Three representatives for each combination of size and matrix were spot mapped for birds from May through August 2005. I examined the relationship of species richness and bird guilds to patch size and surrounding matrix. I also measured a series of potential covariates for each dome to account for variation among the three size-matrix representatives for each combination. Richness and abundance counts were divided by the number of listening points to standardize the data by effort. I found that the standardized species richness of bird assemblages significantly increased with the patch size of cypress domes; however, matrix and the interaction effect of size and matrix on overall standardized species richness were not significant. Significant covariates included percent of the buffer undeveloped, percent herbaceous cover, and the number of listening points per unit area. A linear regression tested for significant effects of log area and matrix on standardized species richness. Matrix was not significant, but log area did have a significant effect on standardized species richness. The MANOVA tests for guild richness data indicated no significant effects of dome size, matrix, or their interaction effect on diet, foraging, or location guilds. There were no significant main or interaction effects on any individual guilds in the ANOVA output. Individual backward linear regressions done on each guild indicated that matrix did not have significant effects on any guild, but log area had significant effects on ground foragers, lower-canopy foragers, omnivores, herbivores, and edge species. I then investigated the effects of size and matrix on standardized guild abundance. Dome size and matrix significantly effected diet guild abundance, but the size-matrix interaction did not. Dome size significantly affected insectivores, omnivores, and carnivores. Matrix had a significant effect on omnivores, herbivores, and carnivores. The size and matrix interaction had a significant effect on carnivores. Dome size and matrix significantly affected foraging guild abundance, but the size-matrix interaction did not. Dome size significantly affected ground, lower- and upper-canopy foragers. Matrix had a significant effect on ground, water, and upper-canopy foragers. The size and matrix interaction was not significant for any foraging guild. Dome size and matrix significantly effected location guild abundance, but the size-matrix interaction did not. Dome size significantly affected edge and interior species. Matrix had a significant effect on edge and interior species. The size and matrix interaction was not significant for any location guild. The relationship between species richness and habitat area is well-documented, and the results of this study were consistent with the expectation of higher species richness in larger areas. If maintaining high species richness is the sole goal of conservationists, then large habitat fragments would be preferable regardless of surrounding matrix. Nevertheless, species richness alone is not informative of the potential effects of patch size and matrix on the composition of an avian assemblage. Guild analysis gives insight into community structure and should be considered in addition to simple measures of species richness. Patch size and matrix type significantly affected a number of guilds, and several factors could contribute to the observed differences in guilds across patch size categories and matrix types. Different habitats are available to birds in domes of each size class and matrix type. The potential for diverse foraging opportunities increases as domes increase in size and change in relation to their surrounding matrix. A more detailed analysis is needed to determine how differences in vegetation of domes and surrounding matrix affect guilds, members of which may use habitats both within domes and the matrix. Cypress domes in the central Florida area face severe alteration or destruction due to rapid development. Long-term research that focuses on domes before and after development is needed to understand how changes in the matrix or size of the domes affect all resident flora and fauna. A variety of taxa and biogeochemical processes should be researched. Domes are naturally highly variable in size, shape, and structure, and development changes all of these characteristics. Conservation biologists and managers urgently need to determine how development affects cypress domes and what can be done to maintain their characteristic biodiversity.

Cette étude porte sur l'intégration de l'aluminium et de matériaux composites de type Polymère Renforcé de Fibre de Verre (PRFV) dans les ponts transportables ferroviaires. Ces matériaux ont un intérêt particulier en raison de leur résistance aux conditions environnementales rudes et leur légèreté. Cependant, la combinaison de ces matériaux légers avec les matériaux traditionnels dont l'acier est peu fréquente dans les structures de génie civil. De plus les références de conception fournissent très peu d'informations pour le dimensionnement de ce type d'assemblage. Il existe néanmoins des références de conception des assemblages simplement en aluminium ou simplement en PRFV. Cependant, en comparaison avec l'acier, les recommandations proposées pour l'aluminium et les PRFV sont basées sur un nombre restreint d'essais et le dimensionnement optimal d'un assemblage boulonné entre des pièces d'acier et d'aluminium ou de PRFV peut s'avérer difficile. Aussi, l'objectif principal de la thèse est d'identifier les paramètres géométriques optimum des assemblages boulonnés aluminium-acier et PRFV-acier et d'effectuer une analyse critique des recommandations de conception existantes et si nécessaire les améliorer et enfin, d'évaluer la contribution de la colle dans les assemblages boulonnés/collés. Sur la base de l'état des connaissances disponibles, des études expérimentales et/ou numériques des assemblages boulonnés, collés, et boulonnés/collés des plaques aluminium-acier et PRFV-acier ont été menées. Pour les assemblages boulonnés, des configurations à un boulon et deux boulons ont été expérimentalement et analytiquement analysées. Les résultats obtenus ont permis d'évaluer l'effet des paramètres géométriques tels que l'épaisseur des plaques, les pinces longitudinale et transversale, et les pas longitudinal et transversal sur la résistance de l'assemblage. Par la suite, les paramètres géométriques optimums des assemblages boulonnés en PRFV-acier et aluminium-acier ont été identifiés et l'analyse critique des équations de dimensionnement des assemblages en aluminium et en PRFV recommandés dans les références de conception a été effectuée. Dans le cas des assemblages aluminium-acier, une amélioration des équations de résistance à la pression diamétrale et de résistance en traction et cisaillement combinés ont été proposées. Pour les assemblages en PRFV-acier, une étude semi-empirique a permis de proposer une équation de résistance en section nette adaptée aux PRFV pultrudés. Pour les assemblages collés et boulonnés/collés, seules les configurations à un boulon ont été testées. Des adhésifs méthacrylate et époxyde ont été utilisés et l'effet de ces derniers sur les assemblages multi-matériaux a été évalué. Il est apparu que le type d'adhésif a un effet important tant sur la résistance de l'assemblage que sur son mode de rupture. En outre la rigidité des plaques a un grand impact dans la capacité portante de l'assemblage collé. La contribution de la colle dans un assemblage boulonné a été trouvée avantageuse seulement dans le cas de l'assemblage PRFV-acier. Dans le cas de l'assemblages aluminium-acier, pas d'accroissement significatif n'a été observé.

Enterprise Systems (ESs) are more than a collection of people, technology, processes, and capabilities. The responsibilities of post implementation management of ES lie in the unit called the Competency Center (CC). The CC has a bidirectional relationship with ESs wherein the CC influences the shaping of ESs, and the CC is affected by the dynamic interaction between people, technology, process, and capabilities within the ES. These dynamic interactions keep the CC, fluid and always in-process. The general-use definition of the term “process” as used in the Enterprise Systems literature treats the notion as “repeatable processes” or "replicable processes". However, arising from comparative case studies in four large organizations, I found that decision making, managing, and governing in the ES are not “replicable processes”, not reifications of structural variations over time when examined through the lens of the Assemblage Theory. Assemblage Theory incorporates the dynamic interplay of two continua: the first, territorialization, deterritorialization, and reterritorialization, and the second, material vs. expression. Although the notion of the terms formation, deformation, and reformation are suitable for understanding the processes these CCs encounter in a broad and general manner, they do not sufficiently describe the not-so-solid, never-quite-finished, always in-process or structuring referred to by Hopper (1996) as "emergent regularities". In contrast to the notion of stable structures, this dissertation research adopts the language of Deleuzian assemblage of Territorialization, deterritorialization, and Reterritorialization. Although the four study organizations planned and intended to develop clearly defined competency centers, which would create formalized processes and procedures to manage the post implementation phase, none of the study organizations ever achieved the anticipated stability. Instead, the CCs exhibited the signs of being ‘in-process’ and ‘structuring’. The contribution of this research to the IS field is an understanding of the CCs as processes as opposed to structures and how CCs structuring impact the ESs in organizations.

Oleta River State Park (ORSP), located in North Miami-Dade County is known as the most highly urbanized State Park in all of Florida. The present study was conducted as part of an ongoing seasonally-resolved survey of fish utilization of the mangrove shorelines of Biscayne Bay. Previous Unit Management Plans published by the Division of Recreation and Parks have lacked information concerning the park?s prominent mangrove forests along with its icthyofauna. The main purpose of this thesis was to provide a baseline characterization of the mangrove-fish assemblages and microhabitat trends of ORSP, against which future changes in and around the Park can be gauged. Fish assemblages inhabiting the mangrove shorelines were examined using a visual ?belt-transect? census method over 11 consecutive seasons. Microhabitat variables including salinity, water temperature, water depth, water clarity and distance from Baker?s Haulover Inlet were examined for possible correlations with fish metrics. Several significant differences were evident in the taxonomic richness (number of taxa per unit area) and densities of the five most abundant taxa within the shoreline habitats in terms of seasonal variation and microhabitat variable distribution along the river. Taxonomic richness was typically greater in survey sites located closer to Baker?s Haulover Inlet. Oleta River?s mangrove shoreline fish assemblages appear to reflect (1) proximity of the mangroves that they occupy to Baker?s Haulover Inlet; (2) temperature regime along the shoreline; and (3) the salinity gradient found within the river. Fish assemblage and microhabitat information collected here could serve as a ?baseline? in future investigations of the effects of further urbanization or the effects of other anthropogenic changes to Oleta River and its mangrove habitat, including possible changes to freshwater flow associated with the Comprehensive Everglades Restoration Plan.

Thèse de doctorat : Sciences physiques et de l'Ingénieur. Electronique : Bordeaux 1 : 2008. / Titre provenant de l'écran-titre.