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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.
1

The Metabolic Morphology of Chora: A Building Is An Organism On A Threshold

MacKenzie, Rebecca 25 November 2011 (has links)
Expanding on the fields of bio-mimicry, morpho-ecologies, and dynamics and fluidity in architecture, this thesis proposes architecture as organism. It suggests that as organism, architecture is inherently responsive to the thresholds it exists on and within, thresholds which are composed not just of the physical but of the ephemeral; of time and of space. The existence, metabolism and morphology of an architectural organism becomes a function of the dynamic world into which it is born, inextricable from the ecology of the space it will inhabit. This thesis explores the architectural organism in the context of a visibly and significantly changing threshold, how connections are made between it and the world around it, and how it might engage those who are its inhabitants. The thesis is located in Nova Scotia’s Bay of Fundy, at the mouth of the Gaspereau River.
2

Ecosystems as Models for Plant Selection on Extensive Green Roofs in Southern Ontario

Natvik, Mathis 11 May 2012 (has links)
Research on green roofs has shown their potential to moderate stormwater runoff and excessive heat in large cities. This has supported the implementation of a bylaw in Toronto, Canada which mandates large scale green roof construction. However, designers lack knowledge on appropriate plant selection for local green roofs. European research has demonstrated that healthy plant cover can significantly improve stormwater capture and cooling on green roofs. This thesis employed two methodologies to select native plants suitable for green roofs. Plants species were first identified from Ontario ecosystems with conditions similar to extensive green roofs including alvars, rock barrens, talus and cliffs. Secondly, plant surveys of existing extensive green roofs in Toronto and other southern Ontario locations to discover plant species already in use. Formal testing of the plant species generated from both methodologies can eventually provide designers with knowledge of dependable plant assemblages for extensive green roofs in Toronto.
3

Optimisation des éoliennes à axe horizontal par l'utilisation de pales flexibles. / Horizontal-axis wind turbines optimization by the use of flexible blades

Cognet, Vincent 27 October 2017 (has links)
L’éolien est un secteur industriel en pleine expansion, qui joue un rôle fondamental dans le développement des énergies renouvelables. Cependant ces machines sont performantes sur une plage de fonctionnement étroite. Afin d’adapter l’éolienne aux changements de vent, une solution actuellement mise en place sur certaines éoliennes commerciales consiste à faire varier l’angle de calage (ie l’inclinaison) des pales au cours de son fonctionnement. Cette méthode de contrôle actif élargit la plage de hauts rendements ainsi que la plage de fonctionnement global, et améliore le démarrage de l’éolienne, mais elle n’augmente pas le rendement maximal atteint par une éolienne à angle de calage optimal fixé. Cependant la complexité́ de cette méthode ainsi que ses coûts de conception, de construction et de maintenance la rende inaccessible pour beaucoup d’éoliennes, en particulier celles de petite taille. Récemment des recherches se sont orientées vers un contrôle passif de l’angle de calage. Dans cette thèse nous examinons expérimentalement et théoriquement l’intérêt d’utiliser des pales flexibles suivant la corde sur une éolienne à axe horizontal. L’étude se concentre sur deux questions : - comprendre le mécanisme de reconfiguration de la pale flexible bio-inspirée : la déformation de la pale est due à la compétition entre les forces aérodynamiques, qui augmentent l’angle de calage moyen, et la force centrifuge qui le diminue. Ces effets sont gouvernés par deux nombres adimensionnés, respectivement le nombre de Cauchy et le nombre centrifuge. - qualifier et quantifier le gain en performances de l’éolienne : une flexibilité́ de pale modérée élargit la plage de fonctionnement, et augmente significativement le rendement de l’éolienne, expérimentalement jusqu’à 35% sur la plage de hauts rendements. Une procédure d’optimisation visant à déterminer le matériau optimal de la pale flexible est présentée. Ces gains obtenus en régime stationnaire sont conservés expérimentalement en moyenne en régime instationnaire. Deux temps caractéristiques sont identifiés : le temps de reconfiguration de la pale flexible et le temps de variation de la fréquence de rotation de l’éolienne / Wind energy is a rapidly growing branch of industry, playing a significant role in the development of renewable energies. However these machines are efficient only on a narrow working range. In order to adapt wind turbines to wind changes, some commercial machines are pitch controlled during rotation. This active control method extends the high-efficiency range and the total working range, and improves the starting phase, but it does not increase the maximum efficiency reached by a wind turbine with the fixed optimal pitch angle. However this method is complex and costly (design, construction, maintenance). Thus it becomes cost-effective only for large wind turbines. Research recently focused on passive pitch control. In this thesis, the contribution of chord wise flexible blades is studied both experimentally and theoretically. The thesis concentrates on: - the reconfiguration mechanism of the bio-inspired flexible blade : the deformation is the result of the competition between aerodynamic forces, which increase the pitch angle, and the centrifugal force, which reduces it. These two effects are governed by two dimensionless numbers, respectively the Cauchy number and the centrifugal number. - how to qualify and quantify the efficiency gains : a moderate flexibility extends the working range, and significantly increases wind turbine efficiency, up to 35% on the high-efficiency working range. An optimization procedure is presented, which aims at determining the optimal material to construct the blade. These improvements measured in steady regime are maintained on average when rotational speed is unsteady. Two characteristic times are identified: the reconfiguration time of the flexible blade and the time of variation of the rotational speed of the wind turbine
4

Textil halksula / Textile Antislip Outdoor Sole

Johansson, Jens, Sjöström, Hedvig January 2011 (has links)
De senaste årens långa och kalla vintrar har lett till ett ökat antal halkolyckor. Genom att undersöka halkolyckors utsträckning samt halkskydd som fanns tillgängliga konstaterades det att ett behov av nya halkskydd fanns. Enkäter för att ge svar på användning av halkskydd togs fram och svar från personer i åldrarna 20-65 visade att man överlag inte använde halkskydd. I stor utsträckning berodde det på halkskyddens dåliga kvalité och den negativa stämpeln som fanns på dem . Textila material undersöktes för att finna lämpliga egenskaper. Parametrarna som ett textilt material skulle uppfylla var att inneha högfriktion, slitstyrka, häftande och samtidigt vara miljövänligt. Av bakgrundsmaterialet togs en kravspecifikation fram och koncept som utvärderades. Det koncept som fick högst omdöme kan vara svaret på ett nytt mer användarvänligt, funktionellt och attraktivt halkskydd.The recent long, cold winters have led to an increasing number of slipping accidents. By examining the slipping accidents extent and anti skid available, it was found that there was need for new anti-skid products.Surveys to reveal facts about the usage of anti skid devices were generated and responses from people aged 20-65 showed that people did not use anti-skid. To a large extent it was because of anti-skid products poor quality and the negative stigma placed upon them.Textile materials were examined to find suitable properties. The parameters of the textile material would meet was to hold high friction, wear resistance, adhesive while being environmentally friendly. Background material was presented and a set of requirements and concepts that were evaluated. The concept that received the highest rating may be the answer to a new more user-friendly, functional and attractive non-slip. / Program: Textil produktutveckling med entreprenörs- och affärsinriktning
5

Layer-by-layer assembly of strong bio-inspired nanocomposites / Assemblage couche-par-couche de nano-composites bio-inspirés

Merindol, Rémi 22 September 2014 (has links)
Les performances exceptionnelles des composites naturels comme la nacre ou le bois émergent de l’arrangement précis d’éléments souples et rigides à l’échelle nanométrique. L’assemblage couche-par-couche permet la fabrication de films avec un contrôle nanométrique de l’organisation et de la composition. Ce travail décrit l’assemblage et les propriétés de nouveaux nano-composites contenant des nano-renforts 1-D (fibrilles de cellulose) et 2-D (plaquettes d’argile). Nous avons combiné les argiles avec une matrice extrêmement souple de poly(diméthylsiloxane) dans une architecture lamellaire imitant celle de la nacre. Nous avons étudié des composites à base de fibrilles de cellulose aléatoirement orientées dans le plan, puis alignées dans une direction pour mieux imiter les parois cellulaires du bois. Les propriétés mécaniques de ces composites bio-inspirés égalent ou surpassent celles de leurs homologues naturels, tout en étant transparents et dans certains cas auto-réparants. / Natural materials such as nacre or wood gain their exceptional mechanical performances from the precise organisation of rigid and soft components at the nano-scale. Layer-by-layer assembly allows the preparation of films with a nano-scale control over their organisation and composition. This work describes the assembly and properties of new nano-composites containing 1-D (cellulose nano-fibrils) and 2-D (clay nano-platelets) reinforcing elements. The clay platelets were combined with an extremely soft matrix (poly(dimethylsiloxane)) to mimic the lamellar architecture of nacre. Cellulose based composites with a random in plane orientation of the fibrils were studied first, later we aligned the fibrils in a single direction to mimic further the cell wall of wood. The mechanical properties of these bio-inspired composites match or surpass those of their natural counterparts, while being transparent and in one case self-repairing.

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