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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

[en] FIBER SOIL CONSTRUCTION: A CASE STUDY CONCERNING THE RECOVERY OF MUD WALL TECHNIQUES AND THEIR EFFECTS ON HUMID TROPICAL CLIMATE ENVIRONMENTS / [pt] CONSTRUÇÃO COM FIBROSOLO: UM ESTUDO DE CASO SOBRE O RESGATE DA TÉCNICA DE TAIPA, E SEUS EFEITOS NO AMBIENTE DE CLIMA TROPICAL ÚMIDO COM ESTAÇÃO SECA E CHUVAS DE VERÃO

FERNANDO BETIM PAES LEME 03 December 2003 (has links)
[pt] A busca de modelos de desenvolvimento que minimizem ao máximo o impacto sobre o ambiente em que vivemos é o ideal a ser alcançado. Os benefícios proporcionados através dos objetos construídos pelo homem neste ambiente são reflexos de uma interferência adequada ao espaço habitado. Neste trabalho esta interferência é produzida pelas construções habitacionais. No bairro do Monteiro, área rural do município de Itamonte-MG, notou-se um processo de deterioração e empobrecimento dos conhecimentos construtivos tradicionais, inclusive a taipa. Apesar da eficiência destas construções, observou-se a gradativa degradação de alguns modos construtivos tradicionais no local. Os conhecimentos originais, de manejo de materiais adequado ao clima e local, foram abandonados e esquecidos. O trabalho de pesquisa que se apresenta aqui tem como objetivo fazer das técnicas construtivas consagradas, e que se utilizam de solo cru, um objeto de estudo a fim de resgatar conhecimentos e procedimentos, aperfeiçoá-los, adaptá-los a determinado local e mantê-los em desenvolvimento. A aplicação da metodologia do Laboratório de Investigação em Living Design ( LILD), será a base de sustentação dos experimentos que se realizarão ao longo do trabalho. Resumidamente esta metodologia propõe primeiramente após um estudo das características do contexto local, experimentos iniciais e empíricos, em campo e em laboratório, tendo sempre a participação e atuação dos membros da comunidade. A investigação tem prosseguimento com ensaios científicos, que permitem o controle e o aperfeiçoamento nos procedimentos utilizados em tais técnicas. Posteriormente a estas etapas aplicam-se novamente outros experimentos práticos no campo e novamente com participação da comunidade. Do compartilhamento das atividades do pesquisador e dos obreiros locais, resultou uma troca de informações que permitiu a aplicação do aprendizado da produção e da pesquisa num mesmo objeto. Aparecem com destaque no percurso do trabalho, experimentos que demonstraram a importância da utilização das fibras, não somente como agente estabilizador do solo, mas permitindo sim, novas possibilidades de vedações leves, principalmente como elemento definidor de compósitos em forma de lâminas e cascas. / [en] Our goal is the search for development models that minimize environment impact. The benefits deriving from mans constructed objects on these environments reflect an adequate interference to the inhabited space. The resulting interference from habitation constructions is described. A process of deterioration and impoverishment of traditional constructive knowledge, including mud wall, was detected in the rural area of Monteiro, district of Itamonte in Minas Gerais, Brazil. In spite of the efficiency of these types of construction, the gradual degradation of some of the traditional constructive modes was verified. The original knowledge concerning the adequacy of materials to the climate and locality was abandoned and forgotten. The present research aims at studying the known constructive techniques, which use raw soil in order to recover their knowledge and procedures, to improve and adapt them to a certain place, and keep their development. The methodology of the Laboratory of Investigation in Living Design - LILD supports the experiments done along the work. In a few words, the methodology proposes a context study of local characteristics performing initial empiric experiments. This work is carried out at Monteiro and in the laboratory, always counting on the participation of community members. The investigation follows with scientific tests that allow for the control and improvement of procedures adopted in the studied techniques. The next step is to go back to the rural area and make other practical experiments, again, with the participation of community members. The result of shared activities between the researcher and local workers was the exchange of information concerning the production and the research itself, which allowed for the application of learned knowledge in the same object. Experiments along the way demonstrate the importance of utilizing fibers, not only as agents to stabilize soil, but also allowing for new light sealing possibilities, especially as main elements of composites in the form of plates and barks.
2

Use of raw Martian and Lunar soils for surface-based reactor shielding

Christian, Jose L. 1963- 13 October 2014 (has links)
For several decades, the idea of flying and landing a less-than-man-rated nuclear reactor for planetary surface applications has been considered. This approach promises significant mass savings and therefore reduction in launch cost. To compensate for the lack of shielding, it has been suggested the use of in-situ materials for providing radiation protection. This would take the form of either raw dirt walls or processed soil materials into blocks or tile elements. As a first step in determining the suitability of this approach, it is necessary to understand the neutron activation characteristics of these soils. A simple assessment of these activation characteristics was conducted for both Martian and Lunar soils using ORIGEN2.2. An average composition for these soils was assumed. As a baseline material, commonly used NBS-03 concrete was compared against the soils. Preliminary results indicate that over 2.5 times more gamma-radiation production of these soils vs. concrete took place during the irradiation phase (a baseline of 2.4 x 1011 neutrons/sec-cm2 was assumed). This was due primarily to radiative capture on Na23 and Mn55 and subsequent decay of their activation products. This is does not necessarily disqualify these materials as potential shielding material since the -radiation output was only in the order of 4.2 x 108 photons/cm3-sec. Furthermore, these soils did not show any significant activity after shutdown of the neutron source (the reactor), since all activation products had very short half lives. Their performance in this area was comparable to that of NBS-03 concrete. / text

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