[pt] O fenômeno de retorno de chama em tubos é conhecido e estudado há várias décadas. Sua análise clássica é baseada na determinação do gradiente de velocidade crítico, Gc, que o delimita como função das propriedades das misturas combustíveis. Entretanto, não é conhecido o efeito da diluição por CO2, importante para a previsão da segurança das instalações do pré-sal. Por isto, são aqui desenvolvidos estudos específicos do retorno de chamas pré-misturadas em escoamentos laminares. O objetivo geral deste trabalho é determinar experimentalmente a influência da diluição por CO2 sobre o retorno de chamas (flashback) em misturas de hidrocarbonetos (CH4 ou propano) e de ar. O levantamento do estado da arte permitiu especificar as características da instalação experimental para o estudo deste fenômeno e, também, identificar as principais questões a serem abordadas. Foi projetado e construído um aparato experimental para o estudo do flashback em escoamentos laminares. Os resultados originais obtidos mostram como a propensão ao retorno de chama é influenciada pela natureza do combustível, pela estequiometria da mistura e pela diluição. Misturas de propano possuem maior propensão ao flashback e maiores valores de Gc do que as de metano. Também foi mostrado que há uma redução da propensão ao flashback com o aumento da diluição. Esta propensão foi relacionada aos números adimensionais que caracterizam a combustão, isto é, os números de Lewis, Péclet, Karlovitz e Zel dovich. Para este último, uma proposta original visando sua determinação é apresentada, que envolve uma expressão da taxa de liberação de calor da reação química global controlada por uma variável de progresso. Esta formulação permite resolver o problema da singularidade na região da estequiometria. / [en] The flashback phenomenon in tubes has been known and studied for several decades. Its classical analysis is based on the determination of the critical velocity gradient, Gc, which delimits it as a function of the fuel mixture properties. However, the effect of the CO2 dilution is not known, which is important for predicting the safety of pre-salt facilities. For this reason, specific studies of premixed flame flashback in laminar flows are developed here. The general objective of this work is to experimentally determine the influence of CO2 dilution on flame flashback in mixtures of hydrocarbons (CH4 and propane) and air. The state of the art research made it possible to specify the characteristics of the experimental installation for this phenomenon study and, also, to identify the main issues to be addressed. An experimental apparatus was designed and built to study the flame flashback in laminar flows. The original results obtained show how the propensity of the flame flashback is influenced by the nature of the fuel, the stoichiometry of the mixture, and the dilution. Propane mixtures have a greater propensity for flashback and higher values of Gc than those of methane. It has also been shown that there is a reduction in the propensity of flashback with increasing dilution. This propensity was related to the dimensionless numbers that characterize combustion, that is, the Lewis, Péclet, Karlovitz, and Zel dovich numbers. For the latter, an original proposal aimed at its determination is presented, which involves an expression of the heat release rate from the global chemical reaction controlled by a progress variable.

This dissertation critically appraises some ofChauke's literary works within a semiotic approach especially in terms of colours of the spectrwn. In this study the spectrum is reganled as a replica or symbol of man's various filcets of Jife. Analyses of the representations of "Life is a Spectrum" have been made in tenns of psychological and symbolic &.cets. Cbauke's narrative s1yle in delineating characters and milieus sketching received attention in the discussion. The cunent scenario in education and politics as well as socio-economic issues have also been dealt with. This study has revealed that Chauke is an author who dmws readers very close to his works that serve as mirrors of their lives. It bas been established that Chauke is an outstanding writer who uses real situations and events that are relevant to people•s life in this contempotaty situation. / African Languages / M.A. (African Languages)

This is a study ofD.RZ. Ntuli's radio trilogy: Isivumelwano, IsivumelwanoEsisha and Ngenxa Yesivumelwano. Since the term trilogy is not a familiar concept in Zulu literary studies, this is an attempt to fill that void. This thesis provides some new insight into this concept, while also devising a practical method for the analysis of the radio trilogy. Chapter one outlines the aim of the study, scope of the study and the definition of some terms. This is followed by explaining the method of research and theories on radio serial dramas. There is also a discussion of the historical background in the development of Zulu radio serial drama and Ntuli's position and contribution to it. Finally, there is a review of previous research studies in Aincan Languages on radio drama. In chapter two plot structure of a radio trilogy is discussed. Theories of drama trilogy by trilogists like Hitchcock, Bakhtin, Asimov and Norris are discussed in detail. This is followed by an in-depth analysis of the plot structures of Isivumelwano, Jsivumelwano Esisha and Ngenxa Yesivumelwano. Chapter three deals with the characterization of radio trilogy. It distinguishes between the actors and characters. Different methods of character portrayal are investigated. Chapter four deals with perspectives on the theme of the radio trilogy. Types of themes are dealt with. Chapter five discusses the dialogue in radio trilogy. It deals with the differences between a dialogue, duologue and monologue, and explains the functions fulfilled by dramatic utterances and dialogue. Lastly a nature of dialogue as a characteristic of the dramatic action is discussed. Chapter six concentrates on the style of radio trilogy. Elements and different types of styles are discussed. Kinds of images, figurative language, proverbs, idioms, biblical allusions and various influences are discussed in detail. Chapter seven concludes by summarizing the main finding ofthis study, and giving observations about the quality ofNtuli's contribution to radio drama trilogy. lt also explores some possibilities regarding future studies on Ntuli's radio trilogy. / African Languages / D. Lit. et Phil. (African Languages)

This dissertation critically appraises some ofChauke's literary works within a semiotic approach especially in terms of colours of the spectrwn. In this study the spectrum is reganled as a replica or symbol of man's various filcets of Jife. Analyses of the representations of "Life is a Spectrum" have been made in tenns of psychological and symbolic &.cets. Cbauke's narrative s1yle in delineating characters and milieus sketching received attention in the discussion. The cunent scenario in education and politics as well as socio-economic issues have also been dealt with. This study has revealed that Chauke is an author who dmws readers very close to his works that serve as mirrors of their lives. It bas been established that Chauke is an outstanding writer who uses real situations and events that are relevant to people•s life in this contempotaty situation. / African Languages / M.A. (African Languages)

This is a study ofD.RZ. Ntuli's radio trilogy: Isivumelwano, IsivumelwanoEsisha and Ngenxa Yesivumelwano. Since the term trilogy is not a familiar concept in Zulu literary studies, this is an attempt to fill that void. This thesis provides some new insight into this concept, while also devising a practical method for the analysis of the radio trilogy. Chapter one outlines the aim of the study, scope of the study and the definition of some terms. This is followed by explaining the method of research and theories on radio serial dramas. There is also a discussion of the historical background in the development of Zulu radio serial drama and Ntuli's position and contribution to it. Finally, there is a review of previous research studies in Aincan Languages on radio drama. In chapter two plot structure of a radio trilogy is discussed. Theories of drama trilogy by trilogists like Hitchcock, Bakhtin, Asimov and Norris are discussed in detail. This is followed by an in-depth analysis of the plot structures of Isivumelwano, Jsivumelwano Esisha and Ngenxa Yesivumelwano. Chapter three deals with the characterization of radio trilogy. It distinguishes between the actors and characters. Different methods of character portrayal are investigated. Chapter four deals with perspectives on the theme of the radio trilogy. Types of themes are dealt with. Chapter five discusses the dialogue in radio trilogy. It deals with the differences between a dialogue, duologue and monologue, and explains the functions fulfilled by dramatic utterances and dialogue. Lastly a nature of dialogue as a characteristic of the dramatic action is discussed. Chapter six concentrates on the style of radio trilogy. Elements and different types of styles are discussed. Kinds of images, figurative language, proverbs, idioms, biblical allusions and various influences are discussed in detail. Chapter seven concludes by summarizing the main finding ofthis study, and giving observations about the quality ofNtuli's contribution to radio drama trilogy. lt also explores some possibilities regarding future studies on Ntuli's radio trilogy. / African Languages / D. Lit. et Phil. (African Languages)

Länge har det funnits en föreställning om att den rasism som riktas mot öst- och sydostasiater är en ”positiv” sådan, eller så har asiater helt enkelt varit frånvarande i anti-rasistiska diskurser. I samband med covid-19 eskalerade hatbrott mot asiater, vilket synliggjorde anti-asiatisk rasism som ett aktuellt samhällsproblem som alltid funnits. I denna uppsats undersöks hur öst- och sydostasiater representeras diskursivt i det svenska internetforumet Flashback i syfte att öka medvetenhet om rasism mot asiater och vidare bidra till att motarbeta de kvarstående ojämlikheterna mellan olika etniska grupper. Studien tar avstamp i ett konstruktivistiskt perspektiv på språk och diskriminering och den kritiska diskursanalysen (CDA) som övergripande analysramverk. Sammanlagt 22 diskussionstrådar som behandlar ämnen som Asien, asiat och de östasiatiska nationerna har analyserats med hjälp av Membership Categorization Analysis (MCA) och den diskurshistoriska analysen (DHA).   Undersökningen utgörs av tre delstudier som ska belysa tre olika aspekter av diskriminering av asiater: 1) kategorisering av asiater; 2) de diskursiva strategier som används av skribenterna för att förneka och rättfärdiga nedsättande kommentarer; 3) diskussioner om den så kallade ”guling-humorn”, det vill säga de rasstereotypiska framställningarna av asiater som präglas av humor och komik. Resultatet visar bland annat hur kategorin asiat tillskrivs högst motsägelsefulla egenskaper och förväntningar, och att kontexten spelar en avgörande roll för att interaktionsdeltagarna ska kunna välja ut de mest relevanta föreställningarna om asiater. Detta påvisar att diskrimineringen av asiater inte enbart är ”positiv” utan kategorin kan ofta förknippas med tydligt negativa värderingar i olika sammanhang. Den andra delstudien har sedan belyst att olika diskursiva strategier kan användas beroende på två sammanhang: när rasism som sådan förnekas och när de enskilda nedvärderande kommentarerna riktade mot asiater rättfärdigas. Förnekandet av rasism förekommer främst i de diskussionsämne som har direkt koppling till det svenska samhället såsom mångkulturalism och invandring, medan nedsättande kommentarer om östasiater framträder mer frekvent i de trådar där de enskilda östasiatiska nationerna står i fokus. I den sista delstudien identifieras de olika diskursiva strategier som skribenterna använder för att förneka den kränkande aspekten hos ”humoristiska” karikatyrer av östasiater, vilket bidrar till att bevara Sveriges positiva självbild som världens mest toleranta och antirasistiska samhälle.