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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.
11

Theoretische Betrachtung des Glasschmelzprozesses in Glasschmelzöfen

Wiltzsch, Sven 10 February 2014 (has links)
Die vorliegende Arbeit beinhaltet die theoretische Betrachtung des Glasschmelzprozesses in Glasschmelzöfen und die Darstellung von fünf Bewertungsprinzipien zur qualitativen Bewertung von Glasschmelztechnologien für die Abschmelz-, Restquarz- und Läuterzone. Es konnte gezeigt werden, dass zum verbesserten Einschmelzen des Gemenges nicht nur der Energieeintrag, sondern auch der Abtransport der neu entstehenden Schmelze intensiviert werden muss. Bei der qualitativen Bewertung und der Auswahl von Schmelztechnologien zur Beschleunigung der Restquarzlösung wurde dargestellt, dass der Einfluss der Schmelztechnologie auf das Verweilzeitverhalten und damit rückwirkend auf die Effizienz der Restquarzlösezone bei der Vorauswahl von Schmelztechnologien berücksichtigt werden muss. Für die Läuterzone wurde nachgewiesen, dass zwei teils in der Literatur diskutierte Bewertungsprinzipien zur Läuterung von Glasschmelzen abzulehnen sind bzw. zu überschätzten Aussagen zur Effizienz von Läutertechnologien führen. Weiterhin konnte gezeigt werden, dass für den theoretischen Fall einer Läuterbank ohne Konvektionsströmungen die Blasenwachstumsgeschwindigkeiten für Konstruktionen mit minimalen Kosten im Bereich von 4-12*10-7 m/s mit möglichen Ausreißern zu 5*10-6 m/s bei Massengläsern liegen sollten.
12

”Klappa igen, håll käften och idrotta, så kommer det lösa sig” : En kvalitativ studie om elitidrottskultur och dess betydelse för mäns upplevda psykiska hälsa / "Stay quiet, shut up, keep doing sports and it will all work out" : A qualitative study of elite sports culture and its meaning for men's perceived mental health

Andersson, Julia, Andersson, Ronja January 2024 (has links)
Syftet med studien var att öka förståelsen för svensk elitidrottskultur och dess betydelse för elitidrottarnas upplevda psykiska hälsa. Detta genom frågeställningen "Hur ser elitidrottskulturer ut i olika lagmiljöer och vilken betydelse har den för mäns upplevda psykiska hälsa?". Teorier som använts var maskuliniteter av Connells, Bourdieus handlingsteori och sociala band av Scheff. Vi har använt en kvalitativ metod med hermeneutiken som metodansats följt av kvalitativa intervjuer med åtta elitidrottsutövande män. Resultatet visade att elitidrottskultur präglas av maskulina normer. Spelarna blir socialiserade in i kulturen där bötessystem, hierarkier och sociala positioner anses vara djuptrotade och påverkar spelarna både positivt och negativt. Analysen visar hur elitidrottskulturer kan förstås som ett fält av konkurrens som präglas av hegemonisk maskulinitet och hierarkier, vilket påverkar spelarna. Socialisering formar beteenden utan djupare reflektion och att bryta mot normer kan leda till skam. Analysen visar också att starka sociala band kan fungera som en skyddsfaktor för spelarnas psykiska hälsa. / The purpose of this study was to increase understanding of Swedish elite sports culture and its meaning for elite athletes perceived mental health. This was done through the research question "What does elite sports culture look like in different team environments and what meaning does it have for men's perceived mental health?". Theories used include Connell's theory of masculinities, Bourdieu's theory of practice, and Scheff's theory of social bonds. We employed a qualitative method with hermeneutics as a methodological approach, followed by qualitative interviews with eight elite male athletes. The results showed that elite sports culture is characterized by masculine norms. Players are socialized into the culture where fining systems, hierarchies and social positions are considered deeply rooted and affect players both positively and negatively. The analysis demonstrates how elite sports cultures can be understood as a field of competition characterized by hegemonic masculinity and hierarchies, which affects the players. Socialization shapes behaviors without deeper reflection and not following norms can lead to shame. The analysis also shows that strong social bonds can serve as a protective factor for players' mental health.
13

Clarificação de suco de laranja "core wash" por processo de flotação auxiliado por enzimas pectinolíticas e agentes clarificantes /

Albuquerque, Carolina Maria. January 2009 (has links)
Orientador: Roger Darros-Barbosa / Banca: Maria Aparecida Mauro / Banca: José Fernando Durigan / Resumo: A recuperação dos sólidos solúveis presentes na membrana central da laranja, separada durante a etapa de extração industrial do suco, normalmente produz um suco contendo de 5 a 6ºBrix e uma série de outros compostos insolúveis (cerca de 9%), muitos dos quais contribuem para a baixa qualidade do suco, sendo responsáveis pelo amargor e adstringência. O presente trabalho propôs-se a clarificar esse suco contendo sólidos recuperados, empregando um pré-tratamento com enzimas pectinolíticas seguido por tratamento por flotação por injeção de ar comprimido auxiliada por agentes clarificantes: bentonita, sílica sol e colágeno hidrolisado. Constituíram-se os objetivos: (i) a determinação das melhores condições (tipo de enzima pectinolítica, duas hidrolases e duas pectinases, e tempo de incubação) para a degradação enzimática da pectina presente; (ii) a determinação da melhor combinação dos agentes clarificantes visando obter um subproduto clarificado através do monitoramento de parâmetros físico-químicos (capacidade floculante e transmitância) e (iii) a avaliação do processo de flotação com diferentes concentrações de bentonita (500, 1.000 e 1.500 mg L-suco-1 e pressões (490, 680 e 880 kPa) pela determinação do grau de clarificação através de monitoramento da transmitância do clarificado, pela determinação da velocidade de flotação/separação das fases, através da verificação das frações volumétricas das fases separadas (clarificado, sedimentado e flotado), em intervalos de tempos regulares durante o processo de flotação e pela análise do produto final clarificado. Os produtos clarificados foram analisados com relação ao conteúdo de sólidos solúveis e insolúveis, pH, acidez titulável, polpa, transmitância, cor (parâmetros L*, a*, b*) proteína, pectina total, sódio, hesperidina, polifenóis e bioflavonóides. Para o tratamento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Core membrane of the orange fruit separated during the juice extraction step in the citrus processing industrial plant, is currently submitted to a soluble solids recovery process, normally producing a by product (secondary) juice containing about 5 to 6º Brix and other insoluble components (about 9%), which contribute to the juice's low quality, since many are responsible for the bitterness and adstringency. This research aimed to clarify this by-product juice containing recovered solids, by enzyme pre-treatment with pectic enzymes, followed by a flotation treatment with compressed air injection using fining agents: bentonite, silica sol and hydrolyzed collagen. The objectives were (i) to determine the best conditions (enzyme type, two hydrolyses and two pectin-liases and incubation time) for the enzyme treatment for pectin degradation; (ii) to determine the best combination of the fining agents to obtain a clarified by-product through monitoring physical chemical parameters (flocculating ability and product transmittance); and (iii) to evaluate the flotation process and the effects of bentonite concentration (500, 1.000 and 1.500 mg L-juice-1) and saturation pressure (490, 680 and 880 kPa) by determining the degree of clarification through monitoring the product transmittance and by determining the flotation rate (and phase separation) through measurements of volumetric fractions of the separated phases (clarified, floated and sediment) over time during the flotation and phase separation processes. Both untreated and clarified juices were analyzed for soluble and insoluble solid contents, pH, total titratable acidity, pulp content, transmittance, color (parameters L*, a* and b*), protein and pectin contents, sodium, hesperidine, poliphenols and bioflavonoids. The results indicates a purified poligalacturonase as the adequate for the enzyme treatment in 1 hour, 45ºC, with 0,05 mL... (Complete abstract click electronic access below) / Mestre

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