Navegando por Data de Publicação, começando com "2011-03-21"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 2 de 2

Análise das propriedades mecânicas de juntas sobrepostas na liga Al 6181-T4 soldadas por fricção por ponto
(Universidade Federal de São Carlos, 2011-03-21) Parra, Bruno Serafim; Alcântara, Nelson Guedes de; https://lattes.cnpq.br/3123107570992184; https://lattes.cnpq.br/4026294524581312
Lightweight alloys, originally developed for aeronautic applications, have also shown increasing use in the automotive sector, aiming fuel consumption and reduction of production costs. In addition to this there is the increasing environmental concern that makes lightweight alloys even more attractive, due to recycling capabilities. It is important notice that parts produced with lightweight alloys may need, at some point of the production process, be joined to others parts. In the aeronautic industry the joining is made primarily by riveting while in the automotive industry RSW - Resistance Spot Welding is usually employed. These processes present some problems such as those related to metallurgical defects and the low weldability for some lightweight alloys. Within this context the FSpW - Friction Spot Welding, that is a solid state joining process, was developed at GKSS Research Centre in Germany. This process has shown great potential for applications where the already established RSW (automotive) and riveting (aircraft), present some disadvantages. In this work the applicability of this new process for the production of overlapping joints of the alloy 6181-T4, which is already used in the automotive industry, was studied. Joints were produced with different welding parameters (welding time and rotational speed) and will be submitted to mechanical characterization, by means of microhardness measurements and mechanical tests for assessment of the performance of the welds. Microstructural characterizations will be performed using optical and electron microscopy to determine the effect of the welding parameters on the final microstructure of the welds, as well as eventual defects. It will be also done a study of failure analysis, aiming the understanding of the mechanisms of fracture, correlating them with the process parameters. Sound joints with high mechanical strength and good repeatability were obtained, with better results associated to low welding time and high toll rotational speed.
Refugiados no contexto das mudanças ambientais
(Universidade Federal de São Carlos, 2011-03-21) Costa, Claudia Silvana da; Valêncio, Norma Felicidade Lopes da Silva; https://lattes.cnpq.br/7161606146208875; https://lattes.cnpq.br/3742019059668505
This thesis aims to focus on the construction of a subject called environmental refugee, new social group s formation that came from an adverse context, caused by the damaging effects of climate changes at its land which became inhabitable and inhospitable. Like that, unlike other refugees who leaved their countries for political, ethnic-religious, economical or social reasons, environmental refugees unwittingly has to leave their countries once in their lands has no way of survival because of the deleterious effects caused by climate change that are in the process, making certain territorial bases in social production and identity of peoples. Accordingly to the United Nations (UN) data, the number of environmental refugees on the planet will increase significantly over the next few years, mostly will come from Africa and from its other small Islands, which are those with greater vulnerability to the impacts of climate changes because of their geographical location, becoming like that, the potential environmental refugees. This way, trying to contribute to build a larger problematic for this matter inside a context that shows how necessary is to designate a definition that fits ruight this kind of refugees and to build a new legal framework guaranteeing to this group human being conditions, taking by example the case of São Tomé e Príncipe, small African s Island considered as States, with the clipping sample of Ilha de São Tomé, which is already under the risks of climate effects on its territory and with potential environmental refugees, providing like that, a reflection about the challenges of the environmental refugees, placing them on the spot of the legal Constitution.