This PhD thesis addresses the development of novel computational methods for designing modular structures i.e. structures composed of the assembly of identical components called modules. Current methodologies tackle this challenge by implementing topology optimization of the module but their efficiency is limited by the performance deterioration when numerous modules are used in the structure. In this work, the design of lightweight modular structures is addressed by simultaneously optimizing the topology of the modules and their respective position in the structure. This contribution also includes a novel strategy that reconciles lightness, structural performance, and constructability (i.e. fabrication and erection phases) by incorporating module rotations as additional design variables. To ensure the practical applicability of the proposed approach, stability is included to provide meaningful solutions that are globally stable and resist local buckling. For this purpose, global stability constraints using linear prebuckling are adopted, while local stability is formulated based on Euler buckling and properties of standard profiles obtained from commercial catalogues. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-08-25T18:15:44Z No. of bitstreams: 0 / Made available in DSpace on 2016-08-25T18:15:44Z (GMT). No. of bitstreams: 0 / Com o escopo de fornecer subsídios para compreender como o processo de colaboração científica ocorre e se desenvolve em uma instituição de pesquisas, particularmente o IPEN, o trabalho utilizou duas abordagens metodológicas. A primeira utilizou a técnica de análise de redes sociais (ARS) para mapear as redes de colaboração científica em P&D do IPEN. Os dados utilizados na ARS foram extraídos da base de dados digitais de publicações técnico-científicas do IPEN, com o auxílio de um programa computacional, e basearam-se em coautoria compreendendo o período de 2001 a 2010. Esses dados foram agrupados em intervalos consecutivos de dois anos gerando cinco redes bienais. Essa primeira abordagem revelou várias características estruturais relacionadas às redes de colaboração, destacando-se os autores mais proeminentes, distribuição dos componentes, densidade, boundary spanners e aspectos relacionados à distância e agrupamento para definir um estado de redes mundo pequeno (small world). A segunda utilizou o método dos mínimos quadrados parciais, uma variante da técnica de modelagem por equações estruturais, para avaliar e testar um modelo conceitual, apoiado em fatores pessoais, sociais, culturais e circunstanciais, para identificar aqueles que melhor explicam a propensão de um autor do IPEN em estabelecer vínculos de colaboração em ambientes de P&D. A partir do modelo consolidado, avaliou-se o quanto ele explica a posição estrutural que um autor ocupa na rede com base em indicadores de ARS. Nesta segunda parte, os dados foram coletados por meio de uma pesquisa de levantamento com a utilização de um questionário. Os resultados mostraram que o modelo explica aproximadamente 41% da propensão de um autor do IPEN em colaborar com outros autores e em relação à posição estrutural de um autor na rede o poder de explicação variou entre 3% e 3,6%. Outros resultados mostraram que a colaboração entre autores do IPEN tem uma correlação positiva com intensidade moderada com a produtividade, da mesma forma que, os autores mais centrais na rede tendem a ampliar a sua visibilidade. Por fim, vários outros indicadores estatísticos bibliométricos referentes à rede de colaboração em P&D do IPEN foram determinados e revelados, como, a média de autores por publicação, média de publicações por autores do IPEN, total de publicações, total de autores e não autores do IPEN, entre outros. Com isso, esse trabalho fornece uma contribuição teórica e empírica aos estudos relacionados à colaboração científica e ao processo de transferência e preservação de conhecimento, assim como, vários subsídios que contribuem para o contexto de tomada de decisão em ambientes de P&D. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

This research attempts to evaluate temporary urban regeneration potential by integrating two systems that make up an interim intervention which addresses an observed problem. The research proposes a systematic approach for a multi-system life cycle assessment model which lays out the process of working with two separate systems to provide a pathway for temporary urban development strategies. To achieve this, the research starts with identifying parameters of temporary urban regeneration through a systematic review of the literature. Key parameters are categorized based on objectives, indicators, as well as, physical characteristics of the literature explored case studies. Then, the findings are utilized to guide the proposed model of connecting two given systems to assess their joint impacts on a temporary urban regeneration system. The proposed MSLCA framework utilizes a holistic modeling structure with a process to integrate and analyze separate systems and quantify results for overall sustainability performance. Finally, the model is used to evaluate a case study involving two systems that address observed problems and provide urban services. The results explore the environmental impacts of the proposed intervention and highlight the effects of individual components on both systems. Through the implementation of the model, decisions on temporary urban intervention are guided by hotspots in the results. The findings reveal an opportunity for future research to expand the model's application to other processes and further its scope beyond environmental indicators. Subsequent studies can investigate opportunities for a holistic approach that includes economic and social aspects. / Doctor of Philosophy / The way we live in cities is heavily influenced by how they are planned. Improvident city planning could deny residents opportunities to enjoy some basic urban amenities. These problems could be self-induced as they are often a result of planning, policies, or personal habits and choice. Planners, urban designers, and regulators are constantly experimenting with different tools of urban regeneration to rediscover genuine urban experiences. This research sets out to investigate opportunities for temporary urban interventions on vacant lands in the city of Riyadh through repurposing idle shipping containers as a tool. This is to address the issues of a lack of urban services within residential subdivisions in the city, the high prevalence of vacant lands, and a wide availability of decommissioned shipping containers. The use of shipping containers for non-cargo purposes has seen an increased interest among architects and designers for their versatility and accessibility. Empty container accumulation is often a result of an unbalanced trading system which is mainly an issue of import-based countries. Therefore, the upcycling potential of intermodal containers can extend their life cycles and take advantage of their structure. It also maximizes the environmental returns of their raw materials. Through such processes of circular economy, potential waste objects can be repurposed as resources into usable structures and thus avoids the use and extraction of new raw materials. It is generally thought that the repurposing of shipping containers into building structures introduces environmental advantages when compared to traditional construction. Similarly, vacant lands are a valuable and well-established resource that can provide the setting for temporary urban interventions. Finding a joint productive use of these systems is at the center of this research as it attempts to assess the urban regeneration value of their merged utility during their idle stage. This helps address a key challenge that most urban area suffers from which is the lack of easily accessible and timely deployable temporary urban intervention to serve a particular use. This research aims to create a model that evaluates the lifecycles of temporary uses based on the joint intersection of contributing systems. The proposed Multi-System Life Cycle Assessment (MSLCA) model is to be applied to assess temporary urban regeneration interventions and help make decisions regarding appropriate approaches. The goal of the model is to propose a value-based approach based on characteristics from two systems. The resulting MSLCA model answers questions on how to apply LCA processes to a transitional intervention with new processes. In doing so, it highlights parameters for systems integration and processes for planning appropriate scenarios for urban interventions. It also highlights the need for unique system boundaries and specifies approaches for system assessment and interpretation. Finally, it provides broader impact categories beyond environmental impacts to consider specific economic and social indicators.