Les composites à matrice céramique (CMC) sont destinés à remplacer les superalliages comme constituants de l'architecture des chambres de combustion des moteurs aéronautiques. Dans ces conditions, la durée de vie de ces matériaux diminue fortement du fait de leurs dégradations par oxydation. Pour pallier à ce problème, des CMC à matrice autocicatrisante sont élaborés. Ils possèdent la particularité de s'auto-protéger vis-à-vis de l'oxydation par la formation d'oxyde passivant limitant la diffusion des espèces oxydantes au sein des fissures matricielles. Dans le cadre de ces travaux de thèse, la durabilité d'un composite SiC/[Si-B-C] est évaluée. Son comportement en oxydation/corrosion est alors étudié entre 450 et 1000°C sous air à des pressions partielles d'humidité variables. Une approche multi-échelle (échelle constituants et composite) est envisagée pour comprendre les différents mécanismes mis en jeu lors de la non-cicatrisation/cicatrisation du matériau.

In the present work, the processes of steady combustion and autoignition of hydrogen are investigated using the Conditional Moment Closure (CMC) model with a Reynolds Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) code. A study of the effects on the flowfield of changing turbulence model constants, specifically the turbulent Schmidt number, Sct, and C epsilon 1 of the k − epsilon model, are investigated. The effects of two different mixing models are explored: the AMC model, which is commonly used in CMC implementations, and a model based on the assumption of inhomogeneous turbulence. The background equations required for implementation of the CMC model are presented, and all relevant closures are discussed. The numerical implementation of the CMC model, in addition to other techniques aimed at reducing computational expense of the CMC calculations, are provided. The CMC equation is discretised using finite volume (FV) method. The CFD and CMC calculations are fully coupled, allowing for simulations of steady flames or flame development after the occurrence of autoignition. Through testing of a steady jet flame, it is observed that the flowfield calculations follow typical k − epsilon model trends, with an overprediction of spreading and an underprediction of penetration. The CMC calculations are observed to perform well, providing good agreement with experimental measurements. Autoignition simulations are conducted for 3 different cases of turbulence constants and 7 different coflow temperatures to determine the final effect on the steady flowfield. In comparison to the standard constants, reduction of Sct results in a reduction of the centreline mixing intensity within the flowfield and a corresponding reduction of ignition length, while reducing C 1 results in an increase of centreline mixing intensity and an increase in the ignition length. All scenarios tested result in an underprediction of ignition length in comparison to experimental results; however, good agreement with the experimental trends is achieved. At low coflow temperatures, the effects of mixing intensity within the flowfield are seen to have the largest influence on ignition length, while at high coflow temperatures, the chemical source term in the CMC equation increases in magnitude, resulting in very little difference between predictions for different sets of turbulence constants. The inhomogeneous mixing model is compared using the standard turbulence constants. A reduction of ignition lengths in comparison to the AMC model is observed. In steady state simulation of the autoigniting flow, the inhomogeneous model is observed to predict both lifted flames and fully anchored flames, depending on coflow temperature.

Orientador: Edison Bittencourt / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-10T17:30:36Z (GMT). No. of bitstreams: 1 Morenval_PatriciaPadilhaNunes_M.pdf: 1652893 bytes, checksum: 02a23a8bf415a9489bdf5d12239fabcd (MD5) Previous issue date: 2007 / Resumo: Padrões de cores Munsell são muito utilizados como referência de cor em diversos campos da ciência. O presente estudo partiu da dificuldade do ajuste de cores na indústria de tintas, o que constitui um problema técnico, pois os profissionais que se relacionam com os clientes e os próprios clientes desconhecem as dificuldades de reproduzir as cores. Neste estudo, analisaram-se as diferenças de cores Munsell de mesma notação, mas adquiridas em diferentes datas. Entre os exemplares Munsell analisados estão: dois livros do The Munsell Book of Colors, o primeiro adquirido em janeiro de 2005, e o segundo, em dezembro de 2006, folhas Munsell adquiridas em setembro de 2004 e duas cartelas Munsell Neutral Value Scale, ambas adquiridas em dezembro de 2006. Todos os padrões analisados apresentavam o acabamento brilhante e foram adquiridos do mesmo fornecedor. Foi medida a diferença de cor através do espectrofotômetro Datacolor, em vinte cores e a análise visual foi realizada na cabine de luz BYK Gardner. Para aproximadamente 70% das amostras de cores Munsell analisadas, existe uma diferença de cor perceptível entre aquelas de mesma especificação. Os valores encontrados não tiveram constância de resultados, pois amostras mais antigas apresentaram valores de diferença de cor menores que amostras mais novas. Recomenda-se aos usuários de cores Munsell façam uma avaliação da cor de suas amostras para controlar o estado do seu exemplar. Concluiu-se que o Munsell têm variação entre as amostras de cores produzidas, e que essa variação pode interferir na análise do controle de qualidade de cor na indústria. As causas destas variações nos atributos da cor Munsell são desconhecidas, mas sabemos que o impacto no cliente que recebe a cor é grande, pois não se sabe se a cor que está sendo utilizada confere com as especificações, podendo até gerar conflitos se as partes interessadas não entrarem em acordo / Abstract: Munsell color charts are widely used as color reference in many science fields. This study was motivated by the difficult to match colors in the industry of paints, what constitute a technical problem, due to the fact that professionals that work with customers and customers don¿t know the difficulties of reproducing colors. In this work, we measured Munsell color differences with the same notation, but bought in different dates. Among them are; two ¿The Munsell Book of Colors¿, the first one was bought in January 2005, the second one in December 2006, Munsell sheets bought in September 2004 and two ¿Munsell Neutral Value Scale¿ charts, which were bought in December 2006. All colors analyzed were in glossy finish and were bought from the same supplier. The color difference was measured by a Datacolor spectrophotometer in twenty colors and the visual analyze was done in a BYK Gardner light booth. As a result we found that for more than 70% of Munsell colors samples, there are a perceptive color difference among the ones which has the same specification. The obtained values show no constancy in the results, due to the fact that old samples had smaller results than the new ones. Is recommended to users of Munsell to do a color analyze in their samples, in order to estipulate the tolerance and to control the color. This work concludes that Munsell have colors variations which can interfere in the quality color control of industries. The causes of color variations are unknown, but the impact in customers who receives the color is high, which can cause conflict if both parts do not find a compromise / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

I denna komparativa analys av den interpersonella nivån jämförs Polisens och Arbetsmiljöverkets kommunikation med allmänheten på Facebook. Analysen har som syfte att undersöka hur de två myndigheterna försöker förlika sig med Facebookanvändarna och skapa relationer genom språket. Utgångsunkten för analysen och jämförelsen är att myndigheter verkar ha svårt att anpassa sitt språk på Facebook eftersom myndigheter är en offentlig verksamhet medan Facebook är en verksamhet som främst är privat. Resultatet visar att Polisen och Arbetsmiljöverket har olika strategier för att kommunicera på Facebook och att Arbetsmiljöverket har kommit längre i sin anpassning till idén om webb 2.0. Polisen utövar mer kontroll på vilket sätt Facebookanvändare kan interagera med dem. Bland annat genom att inaktivera inläggsfunktionen och styra vilket ämne dialogen handlar om i kommentarsfältet. Arbetsmiljöverket tillåter användare att göra egna inlägg och ställa frågor men har ett inkonsekvent tilltal i sina egna inlägg och i dialogen.

Abstract This study aimed at investigating some of the possible effects of the computer on adolescents’ language development. As a base for the study Sundqvist’s (2009) study on extramural English (EE) was used. The work of David Crystal provided a substantial background on the English language, which was complemented by the work of Halliday among others.          In the study ten national writing tests were examined and analyzed, and a small survey of the ten students’ Internet habits was performed. The mistakes and errors made by the students in the tests were compared to their value of exposure to Internet English (EIE) in order to establish possible links between their Internet habits and their writing mistakes. The study found that the five boys that took part spent more time online and engaging in activities where English was used than the girls of the study. It was also found that the students who spend the most time online made substantially more errors and mistakes regarding the apostrophe, mainly in contractions. It was also found that the students who spent little time online and had a low value of EIE were more likely to make mistakes and errors regarding verbs and agreement.                       Although the study was too limited for any generalizations to be made, it hinted at some possible links between Internet habits of adolescents and their performance on the national test and their general language proficiency.

The aim of this essay is to determine where on a continuum between speech and writingwritten computer-mediated communication (chat language) would be placed. The essay makes use of a methodology based on Biber (1988). This was done using a quantitative research methodology based on counting and comparing specific linguistic features in different texts. The data for chat language came from the NPS Chat Corpus. Other data used were transcripts of spoken discourse as well as a popular scientific text as material for comparison. This essay is mainly focused on four features: the use of pronouns, passives, ellipsis and the type/token ration of each individual text. Despite the limited size of the material sampled, the results showed that chat language had more in common overall with speech than with writing.

Människor tillskriver varandra egenskaper. Detta sker omedvetet och systematiskt och syftar till att underlätta förståelsen av omvärlden. Syftet med detta arbete har varit att undersöka i vilken utsträckning det är möjligt att utifrån vald språkstil i ett e-postmeddelande bedöma en persons egenskaper, vilket i denna rapport benämnts en persons sociala styrka. En engelskspråkig undersökning har legat till grund för arbetet och tanken har - förutom ovanstående - varit att utröna hur väl ett experimentellt engelskspråkigt undersökningsresultat står sig under förhållandevis naturalistiska svenska förhållanden. Resultatet visar inte entydigt att språkstilen styr de egenskaper som författaren tillskrivs. Framräknade medelvärden ger en indikation på att kraftfullt formulerade meddelanden i större utsträckning bedömts som författade av personer besittande en hög social styrka, men endast ett fåtal av resultaten var statistiskt signifikanta. Bl.a. kan en viss skillnad i mäns och kvinnors bedömning skönjas, en skillnad som dock kan vara ett utslag av att grupperna storleksmässigt varit olika.

Abstract This essay deals with the creation and usage of nicknames in synchronous CMC. Nicknames from four different IRC chat conversations related to three different topic groups have been examined. The method draws on Bechar-Israeli’s (1996) categorisation of nicknames, which has been adapted to suit the type of data sampled. Three research questions have been posed, which, in view of other studies related to this field of research (e.g. Ellison et al. 2006, Scheidt 2001, Chester & Gwynne 1998, etc.) have been examined to obtain information about the degree of anonymity and the topic-relatedness of nicknames used in chatrooms. The results show that users participating in synchronous CMC indeed follow topic-related rules for self-presentation and that anonymity has varying importance in different chatrooms.

The issue of sexism is arguably an important topic in modern society in several aspects of life. With the introduction of the Internet and communication over the Internet, additional potential sources of sexism have emerged. While there appears to have been a significant number of studies regarding sexism in cyberspace, Twitch.tv is a relatively new platform and seems yet to be properly explored. Therefore, while being limited in size, the present study aims to provide an introduction to Twitch.tv by performing a limited investigation of the extent of sexist behaviour and ideas expressed by users on the site, particularly against female streamers. To accomplish this, 30,000 lines of chat messages from six different chatrooms, three belonging to women and the remaining three to men, were examined for sexist behaviour, based on a variety of parameters such as differences in language complexity and instances of sexist remarks. The results suggested that several varieties of sexism existed on Twitch, and was directed at both men and women, where women seemed to be more heavily affected than men. The conclusion of the study is that Twitch does not seem to be a breath of fresh air in cyberspace as it appears to embody numerous sexist ideas. However, the author notes that Twitch could serve as a potentially useful source of data for future gender studies online.

Syftet med arbetet var att analysera på vilket sätt företag kommunicerar gentemot bloggare i marknadsföringssyfte, i de fall där kommunikationen misslyckats eller uppfattats som negativ av bloggarna. Genom att med hjälp av metoder för brukstextanalys titta på retoriken och argumentationen i åtta mail som skickats från företag till bloggare, drogs slutsatsen att många av mailen saknade tyngd, både retoriskt och argumentatoriskt. Många av mailen saknade tematisk koppling till den adresserade bloggens nisch och i vissa fall stred även meddelandet mot marknadsföringslagen. Fyra bloggare har varit med och bidragit med material, och dessa har även fått fylla i ett frågeformulär, för att ge sin subjektiva åsikt kring mailen de mottagit. Bloggbyrån, en PR-byrå specialiserad på kommunikation företag och bloggare emellan, utgör också en del av arbetet i form av en intervju med byråns VD (Mats Lindborg), som berättar om Bloggbyråns arbetssätt och hur de anser att kommunikationen bör se ut när företag ska kontakta och samarbeta med bloggare i ett marknadsföringssyfte.