354 research outputs found
Effect of low level contamination on TiAl alloys studied by SIMS
Titanium aluminides are a valuable alternative to superalloys in applications where the ratio resistance/density is important. Since the ordinary production routes lead to high final costs, an alternative might be the use of traditional casting techniques by induction melting of the alloy in a ceramic crucible and pouring into ceramic moulds, made by the investment casting process. However, due to the high reactivity of Ti alloys, traditional ceramic materials cannot be used, as they lead to oxide formation and oxygen pick up from both the crucible and the moulding materials.
In this work, the effect of low level contaminations was studied by SIMS. Special attention was given to the oxygen concentration of samples obtained with different mould materials. The comparison of SIMS in-depth profiles with hardness profiles, give insight concerning the significance of the oxygen concentration in the properties of the alloy and regarding the choice of the most suitable materials for TiAl production
Characterization of TiAl alloys by secondary Ion mass spectrometry
Titanium aluminides are arising as a valuable alternative to superalloys in applications where the
ratio resistance/density is important. Together with excellent mechanical and corrosion properties
at high temperatures, such characteristics are very attractive for applications in the aeronautical,
aerospace and automotive industries. However, the current high selling price, due to high costs of
production and raw materials and the need of very specific equipment, are limitative factors for
further applications. With the end of the cold war, and the decrease of traditional markets of TiAl,
the strategy to develop other applications, strongly depends on the decrease of production costs.
An alternative to the present production routes might be the use of traditional casting techniques,
by induction melting of the alloy in a ceramic crucible and pouring into ceramic moulds, made by
the investment casting process. However, due to the high reactivity of Ti alloys, the use of
traditional ceramic materials cannot be used, as they lead to oxide formation and oxygen pick up
both from the crucible and the moulding materials. In this work, the relative oxygen concentration
of Ti-48Al castings was measured by SIMS — Secondary Ion Mass Spectrometry. This technique
provides a direct measurement of the isotopic composition with high sensitivity. The cylindrical
samples were specially prepared to allow the analysis of the area close to the border. Oxygen
profiles were acquired for samples obtained by with different mould materials. The comparison of
such profiles with hardness profiles, give insight in the significance of the oxygen concentration in
the properties of the alloy and in the choice of the most suitable materials for TiAl production(undefined
Termómetros ClÃnicos
Na prática clÃnica, várias decisões relacionadas com o diagnóstico e tratamento resultam da análise
dos valores da temperatura corporal, sendo a medição deste parâmetro habitualmente realizada
com instrumentos de medição, designados por termómetros clÃnicos.
A correta medição da temperatura corporal assume relevância na prática diária dos cuidados de
saúde, sendo um parâmetro regularmente avaliado no diagnóstico e monitorização do estado de
saúde de um indivÃduo.info:eu-repo/semantics/publishedVersio
Instrumentos de Medição da Pressão Arterial
No setor da saúde, as medições e os instrumentos de medição desempenham um papel fundamental
no quotidiano dos cidadãos. VariadÃssimas decisões clÃnicas são fundamentadas por resultados de
medições, e suportadas na evidência dos mesmos. Por razões de diversa Ãndole, os resultados
obtidos a partir de sistemas de medição podem apresentar variabilidade que conduzem a erros de
diagnóstico e de tratamento, comprometendo o rigor da medição e os recursos disponÃveis.
Neste contexto, o presente trabalho tem como finalidade divulgar conceitos gerais e especÃficos,
aplicados a instrumentos e sistemas de medição, apresentando-se como um documento de consulta
e um guia para a implementação de boas práticas no âmbito da Metrologia na Saúde.info:eu-repo/semantics/publishedVersio
Rendimento de tecidos não componentes da carcaça de cordeiros alimentados com glicerina bruta.
Objetivou-se neste trabalho avaliar os efeitos dos nÃveis de inclusão de glicerina bruta (GB) na dieta cordeiros em terminação sobre o rendimento dos não componentes da carcaça
Predicting the Future of AI with AI: High-quality link prediction in an exponentially growing knowledge network
A tool that could suggest new personalized research directions and ideas by taking insights from the scientific literature could significantly accelerate the progress of science. A field that might benefit from such an approach is artificial intelligence (AI) research, where the number of scientific publications has been growing exponentially over the last years, making it challenging for human researchers to keep track of the progress. Here, we use AI techniques to predict the future research directions of AI itself. We develop a new graph-based benchmark based on real-world data -- the Science4Cast benchmark, which aims to predict the future state of an evolving semantic network of AI. For that, we use more than 100,000 research papers and build up a knowledge network with more than 64,000 concept nodes. We then present ten diverse methods to tackle this task, ranging from pure statistical to pure learning methods. Surprisingly, the most powerful methods use a carefully curated set of network features, rather than an end-to-end AI approach. It indicates a great potential that can be unleashed for purely ML approaches without human knowledge. Ultimately, better predictions of new future research directions will be a crucial component of more advanced research suggestion tools
Degradabilidade "in situ" da matéria seca (MS) e proteÃna bruta (PB) de gramÃneas nativas de várzea do baixo Amazonas, Pará: Paspalum fasciculatum (capim-mori) e Hymenachne amplexicaulis (rabo-de-rato).
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