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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

Influência da redução do tempo de tratamento térmico de homogeneização contínua na microestrutura e qualidade metalúrgica de tarugos de alumínio, liga 6063 e diâmetro de 6” / Effect of time reduction in a continuous homogenizing heat treatment on the microstructure and metallurgical quality of 6063 6 inch diameter aluminium alloy

Corrêa, Renan David 28 July 2014 (has links)
Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-21T14:11:42Z No. of bitstreams: 1 DissRDC.pdf: 7324446 bytes, checksum: 5e04b539c5f14da2f1e2fb0184498eb9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-21T18:26:41Z (GMT) No. of bitstreams: 1 DissRDC.pdf: 7324446 bytes, checksum: 5e04b539c5f14da2f1e2fb0184498eb9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-21T18:26:47Z (GMT) No. of bitstreams: 1 DissRDC.pdf: 7324446 bytes, checksum: 5e04b539c5f14da2f1e2fb0184498eb9 (MD5) / Made available in DSpace on 2016-09-21T18:26:54Z (GMT). No. of bitstreams: 1 DissRDC.pdf: 7324446 bytes, checksum: 5e04b539c5f14da2f1e2fb0184498eb9 (MD5) Previous issue date: 2014-07-28 / Não recebi financiamento / The homogenizing heat treatment of aluminium billets has direct influence on extrusion process productivity, surface quality and mechanical properties of extruded shapes. The homogenizing process parameters that impacts on metallurgical properties of 6063 alloys are: temperature, time and cooling rate. The maximum recommended homogenizing temperature for 6063 alloy is 590ºC. The minimum homogenizing time is 2,25h. The minimum cooling rate recommended is 400ºC/h. As for extrusion logs homogenizing process of 6063 6” diameter at Sapa Aluminium Brasil the furnace is a process bottleneck for logs production, this work has investigated about the possibility of time reducing without negative impacts on billet metallurgical properties and without detrimental impacts on productivity of extrusion process and quality of its products. This investigation was done by billet metallographic analysis, cold and hot mechanical tests and extrusion/anodizing trials for different homogenizing time conditions. The results have shown that the time reducing did not cause negative impacts for metallurgical neither for mechanical properties and because of that no detrimental effects for extrusion performance and surface finish and anodized quality was observed. Hence, was possible to decrease 20 minutes on homogenizing time and gain 14,5% of productivity on heat treatment process. / O tratamento térmico de homogeneização de tarugos de alumínio tem influência direta na produtividade do processo de extrusão, na qualidade superficial e nas propriedades mecânicas dos perfis extrudados. As variáveis do tratamento térmico da liga 6063 que influem na qualidade metalúrgica são: temperatura, tempo e taxa de resfriamento. Para liga 6063, a máxima temperatura recomendada de homogeneização é de 590ºC. O tempo mínimo para a homogeneização é de 2,25h. A taxa de resfriamento mínima recomendada é 400ºC/h. Como para o tratamento térmico de tarugos de 6” há um gargalo no forno de homogeneização da Sapa Aluminium Brasil, investigouse neste trabalho possibilidades de redução de tempo no processo de homogeneização evitando impactos negativos na qualidade metalúrgica dos tarugos e/ou na performance dos tarugos no processo de extrusão. Tal investigação foi feita através de análises metalográficas, ensaios mecânicos a frio (dureza e tração) e a quente (torção) e testes práticos no processo de extrusão/anodização para amostras retiradas de tarugos homogeneizados em diferentes condições de tempo de homogeneização. Os resultados obtidos mostraram que a redução no tempo de homogeneização não impactou negativamente na qualidade metalúrgica dos tarugos e nem em suas propriedades mecânicas a frio e que as pequenas variações ocorridas mantiveram-se dentro dos limites de especificação e não reduziram a performance do processo de extrusão bem como as propriedades mecânicas e qualidade superficial dos perfis extrudados. Com isso, foi possível reduzir 20 minutos no tempo de tratamento térmico de homogeneização e gerar um ganho de produtividade de 14,5% no processo.
2

En nyanserad eller homogen judendom? : Hur fem religionsläroböcker för gymnasiet framställer judendomen / A diverse or homogeneous Judaism? : How five schoolbooks portrays Judaism

Härkänen, Maria January 2015 (has links)
This essay aims to examine if five high school textbooks represent Judaism as homogeneous or diverse. The purpose is to see if textbooks add a diverse or homogeneous view on Judaism. The methods for this essay are a qualitative content analysis and an image analysis. The results tells us that both homogeneous and heterogeneous tendencies can be found in the textbooks to a certain extent. The homogeneous tendencies can be explained as an aftereffect of the textbooks’ authors becoming limited by their schedule, amount of pages and so on. This results in a second-rate construction of how Judaism is represented and how it affects a person’s life. This homogeneity can also be explained as that the reader has to be able to get an understandable view of Judaism’s importance and uniqueness. These heterogeneous tendencies can be explained as an aftereffect of the ongoing debate on textbooks and a careful usage of the language in the books. The author has to be more thoughtful regarding where to compromise. In the end, it is the teacher that creates the diversity and it is up to him/her to evaluate the material to see what it actually says and how it affects the pupil’s view on religion. / Denna uppsats undersöker om fem läroböcker för gymnasiet porträtterar judendomen som homogen eller nyanserad. Syftet är för att se om läromedel bidrar till en nyanserad alternativt homogen syn på religionen. Vald metod för undersökningen är kvalitativ textanalys samt en bildanalys. Resultatet visar på såväl heterogena som homogena tendenser i alla läromedel, dock i mer eller mindre utsträckning. De homogena tendenserna kan bero på läroboksförfattarens begränsningar i skrivandet av ett läromedel, i form av tidsbegränsning, sidbegränsning med mera. Detta skapar en begränsad andrahandskonstruktion av hur judendomen representeras och påverkar en persons liv. Homogeniteten kan även bero på att läsaren måste få en greppbar syn på vad som ger religionen dess betydelse och särart. De heterogena tendenserna kan bero på exempelvis den pågående debatten kring läromedel samt ett mer eftertänksamt språkbruk. Författaren måste vara eftertänksam i sina kompromisser kring valet av text. Dock är det i slutändan alltid läraren som skapar nyansering och det är upp till denne att se till sitt material, hur det påverkar synen på religion hos eleven och vad materialet verkligen säger.

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