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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

Avaliação da influência do tamanho de partícula sobre as propriedades de carvões coqueificáveis e de coques produzidos em escala de laboratório

Flores, Ismael Vemdrame January 2014 (has links)
Atualmente a decrescente disponibilidade de carvões de excelente qualidade e seus preços elevados levam as coquerias a utilizarem carvões mais baratos e consequentemente com propriedades inferiores. Ao mesmo tempo, ocorre à necessidade de se manter as elevadas especificações de qualidade exigidas para o coque pelos altos-fornos. Nesse contexto, independente da escolha dos carvões a serem utilizados, o controle granulométrico dos carvões e misturas, realizado durante a britagem, pode manter ou até melhorar a qualidade do coque a ser produzido. O presente estudo teve como objetivo geral avaliar de que forma as propriedades dos carvões variam em relação a suas principais frações granulométricas após a cominuição, e estudar qual o efeito de diferentes distribuições de tamanhos de partículas sobre as propriedades de coques produzidos em escala de laboratório. Para isso, dois carvões coqueificáveis individuais e uma mistura foram amostrados, separados em frações granulométricas e caracterizados. Após a caracterização das matérias-primas, foram confeccionados coques em escala de laboratório, a partir de diferentes misturas de granulometrias para os carvões individuais amostrados. A caracterização dos coques foi realizada segundo análise imediata, textura, reatividade ao CO2 em termobalança, resistência a frio em tambor tipo I e microresistência. Os resultados obtidos da caracterização das matérias-primas mostraram que a cominuição dos carvões leva a concentrações de cinzas, matéria volátil e composição maceral em diferentes frações granulométricas produzindo alterações nas propriedades coqueificantes das frações granulométricas. O resultado da caracterização dos coques mostrou que cada carvão apresenta uma distribuição de tamanhos de partículas mais adequada, que irá gerar um coque de boa qualidade. Em termos de reatividade ao CO2, uma grande quantidade de partículas finas nas misturas levou a um aumento da reatividade dos coques produzidos. Além disso, a resistência mecânica foi mínima para as misturas grosseiras, enquanto uma mistura mais fina tendeu a produzir coques de resistência mecânica superior. / Nowadays, the decreasing availability of excellent quality coals and their high prices lead cokemakers to use cheaper coals, consequently with inferior properties. At the same time, there is the need to maintain the high coke quality specifications required for the blast furnace. In this context, independent of the choice of coal to be used, the particle size control of coals and blends, created during crushing, can maintain or even improve the quality of coke to be produced. The present study had as main objective to assess how the properties of coals vary in relation to its particle size fractions after crushing, and study what effect different particle size distributions can cause on the properties of coke produced in laboratory scale. Thus, two individual coking coals and a blend were sampled, separated into particle size fractions and characterized. After the characterization of raw materials, cokes were made on a laboratory scale, from blends of different particle sizes for an individual coals. The characterizations of cokes were done by proximate analysis, texture, thermobalance CO2 reactivity, cold strength in a CSR drum, and microstrength. The results of the characterization of raw materials showed that the comminution of coal leads to concentrations of ash, volatile matter and macerals on different size fractions, causing changes in coking properties of size fractions. The results of the characterization of the cokes showed that each coal used has a more suitable particle size distribution which will generate a good quality coke. In terms of CO2 reactivity, a large amount of small particles in the blend led to an increase of coke reactivity. Furthermore, the mechanical strength of cokes was sharply affected by coarse particle, while a blend with high fine proportion produced a coke with high mechanical strength.
2

Avaliação da influência do tamanho de partícula sobre as propriedades de carvões coqueificáveis e de coques produzidos em escala de laboratório

Flores, Ismael Vemdrame January 2014 (has links)
Atualmente a decrescente disponibilidade de carvões de excelente qualidade e seus preços elevados levam as coquerias a utilizarem carvões mais baratos e consequentemente com propriedades inferiores. Ao mesmo tempo, ocorre à necessidade de se manter as elevadas especificações de qualidade exigidas para o coque pelos altos-fornos. Nesse contexto, independente da escolha dos carvões a serem utilizados, o controle granulométrico dos carvões e misturas, realizado durante a britagem, pode manter ou até melhorar a qualidade do coque a ser produzido. O presente estudo teve como objetivo geral avaliar de que forma as propriedades dos carvões variam em relação a suas principais frações granulométricas após a cominuição, e estudar qual o efeito de diferentes distribuições de tamanhos de partículas sobre as propriedades de coques produzidos em escala de laboratório. Para isso, dois carvões coqueificáveis individuais e uma mistura foram amostrados, separados em frações granulométricas e caracterizados. Após a caracterização das matérias-primas, foram confeccionados coques em escala de laboratório, a partir de diferentes misturas de granulometrias para os carvões individuais amostrados. A caracterização dos coques foi realizada segundo análise imediata, textura, reatividade ao CO2 em termobalança, resistência a frio em tambor tipo I e microresistência. Os resultados obtidos da caracterização das matérias-primas mostraram que a cominuição dos carvões leva a concentrações de cinzas, matéria volátil e composição maceral em diferentes frações granulométricas produzindo alterações nas propriedades coqueificantes das frações granulométricas. O resultado da caracterização dos coques mostrou que cada carvão apresenta uma distribuição de tamanhos de partículas mais adequada, que irá gerar um coque de boa qualidade. Em termos de reatividade ao CO2, uma grande quantidade de partículas finas nas misturas levou a um aumento da reatividade dos coques produzidos. Além disso, a resistência mecânica foi mínima para as misturas grosseiras, enquanto uma mistura mais fina tendeu a produzir coques de resistência mecânica superior. / Nowadays, the decreasing availability of excellent quality coals and their high prices lead cokemakers to use cheaper coals, consequently with inferior properties. At the same time, there is the need to maintain the high coke quality specifications required for the blast furnace. In this context, independent of the choice of coal to be used, the particle size control of coals and blends, created during crushing, can maintain or even improve the quality of coke to be produced. The present study had as main objective to assess how the properties of coals vary in relation to its particle size fractions after crushing, and study what effect different particle size distributions can cause on the properties of coke produced in laboratory scale. Thus, two individual coking coals and a blend were sampled, separated into particle size fractions and characterized. After the characterization of raw materials, cokes were made on a laboratory scale, from blends of different particle sizes for an individual coals. The characterizations of cokes were done by proximate analysis, texture, thermobalance CO2 reactivity, cold strength in a CSR drum, and microstrength. The results of the characterization of raw materials showed that the comminution of coal leads to concentrations of ash, volatile matter and macerals on different size fractions, causing changes in coking properties of size fractions. The results of the characterization of the cokes showed that each coal used has a more suitable particle size distribution which will generate a good quality coke. In terms of CO2 reactivity, a large amount of small particles in the blend led to an increase of coke reactivity. Furthermore, the mechanical strength of cokes was sharply affected by coarse particle, while a blend with high fine proportion produced a coke with high mechanical strength.
3

Avaliação da influência do tamanho de partícula sobre as propriedades de carvões coqueificáveis e de coques produzidos em escala de laboratório

Flores, Ismael Vemdrame January 2014 (has links)
Atualmente a decrescente disponibilidade de carvões de excelente qualidade e seus preços elevados levam as coquerias a utilizarem carvões mais baratos e consequentemente com propriedades inferiores. Ao mesmo tempo, ocorre à necessidade de se manter as elevadas especificações de qualidade exigidas para o coque pelos altos-fornos. Nesse contexto, independente da escolha dos carvões a serem utilizados, o controle granulométrico dos carvões e misturas, realizado durante a britagem, pode manter ou até melhorar a qualidade do coque a ser produzido. O presente estudo teve como objetivo geral avaliar de que forma as propriedades dos carvões variam em relação a suas principais frações granulométricas após a cominuição, e estudar qual o efeito de diferentes distribuições de tamanhos de partículas sobre as propriedades de coques produzidos em escala de laboratório. Para isso, dois carvões coqueificáveis individuais e uma mistura foram amostrados, separados em frações granulométricas e caracterizados. Após a caracterização das matérias-primas, foram confeccionados coques em escala de laboratório, a partir de diferentes misturas de granulometrias para os carvões individuais amostrados. A caracterização dos coques foi realizada segundo análise imediata, textura, reatividade ao CO2 em termobalança, resistência a frio em tambor tipo I e microresistência. Os resultados obtidos da caracterização das matérias-primas mostraram que a cominuição dos carvões leva a concentrações de cinzas, matéria volátil e composição maceral em diferentes frações granulométricas produzindo alterações nas propriedades coqueificantes das frações granulométricas. O resultado da caracterização dos coques mostrou que cada carvão apresenta uma distribuição de tamanhos de partículas mais adequada, que irá gerar um coque de boa qualidade. Em termos de reatividade ao CO2, uma grande quantidade de partículas finas nas misturas levou a um aumento da reatividade dos coques produzidos. Além disso, a resistência mecânica foi mínima para as misturas grosseiras, enquanto uma mistura mais fina tendeu a produzir coques de resistência mecânica superior. / Nowadays, the decreasing availability of excellent quality coals and their high prices lead cokemakers to use cheaper coals, consequently with inferior properties. At the same time, there is the need to maintain the high coke quality specifications required for the blast furnace. In this context, independent of the choice of coal to be used, the particle size control of coals and blends, created during crushing, can maintain or even improve the quality of coke to be produced. The present study had as main objective to assess how the properties of coals vary in relation to its particle size fractions after crushing, and study what effect different particle size distributions can cause on the properties of coke produced in laboratory scale. Thus, two individual coking coals and a blend were sampled, separated into particle size fractions and characterized. After the characterization of raw materials, cokes were made on a laboratory scale, from blends of different particle sizes for an individual coals. The characterizations of cokes were done by proximate analysis, texture, thermobalance CO2 reactivity, cold strength in a CSR drum, and microstrength. The results of the characterization of raw materials showed that the comminution of coal leads to concentrations of ash, volatile matter and macerals on different size fractions, causing changes in coking properties of size fractions. The results of the characterization of the cokes showed that each coal used has a more suitable particle size distribution which will generate a good quality coke. In terms of CO2 reactivity, a large amount of small particles in the blend led to an increase of coke reactivity. Furthermore, the mechanical strength of cokes was sharply affected by coarse particle, while a blend with high fine proportion produced a coke with high mechanical strength.
4

Kroppspositivism : provdockor och modeller som visuellt kommunikationsverktyg för större storlekar / Body Positivism : Mannequins and models as visual communication tool for larger sizes

Gustafsson, Lisa, Carlström, Ellinor January 2019 (has links)
Syftet med denna studie är att undersöka hur två svenska modeföretag, Modefabriken och Klädverket, som båda påstår sig vara kroppspositiva visar detta i praktiken. Studien är genomförd inom ämnet textilt management. Studien är ur ett företagsperspektiv, men har även genererat inblickar från ett konsumentperspektiv. Data har samlats in genom primär- och sekundärdata. Studiens sekundära data har genererat ett teoretiskt ramverk som återfinns inom studier av ett västerländskt smalhetsideal och massmedias påverkan, modeindustrin och storlekar, vardagliga modeller och retuscherade modeller, kroppsideal och kroppspositivism. Studiens primära data har samlats in genom semistrukturerade intervjuer, strukturerade observationer i butik samt analys av fyra produktkategorier online. Studiens insamlade data har resulterat i en modifierad kommunikationsmodell för att undersöka hur företagen använder sig av provdockor i butik och modeller online för att visa sitt storleksspann. Judith Butlers Queerteori appliceras för att se om företagen har brutit sig loss från smalhetsidealet. Studiens resultat visar att både Modefabriken och Klädverket använder sig av provdockor i två storlekar, en normativ och en över norm. Båda dessa visar plagg med ett storleksspann från den minsta till den största storleken som företagen har. Slutsatsen av studien är att Klädverket visar sin kroppspositiva inställning i större utsträckning än Modefabriken, detta främst genom att använda sig av fler större modeller online, men även större provdockor i butik. Förslag till vidare forskning är att göra en liknande studie men ur ett konsumentperspektiv. Detta för att komplettera studiens resultat med hur konsumenter uppfattar användandet av större provdockor och modeller. / The purpose of this study is to investigate how two Swedish fashion companies, Modefabriken and Klädverket, who claims to be body positive shows that in practice. The study is conducted within the subject Textile Management. The study is from a corporate perspective but has also generated some insights from a customer perspective. The data has been collected through primary and secondary data. The studies secondary data has generated a theoretical framework which includes a western society ideal of being skinny and the impact of media, the fashion industry and sizes, everyday models and edited models, body ideals and body activism. The primary data of the study has been collected through semi structured interviews, structured observations in store as well as analysis of four different product categories online. The collected data of the study has resulted in a modified communications model to investigate how companies uses mannequins in store and models online to show their range of sizes. Judith Butlers Queer theory is applied to see if companies have broken away from the skinny ideal. The result of the study shows that both Modefabriken and Klädverket use mannequins in two sizes. In their stores and online, they use one normative size and one size above the norm. Both shows garments with a size range from the smallest to the biggest size that the companies offer. The conclusion of the study is that Klädverket shows their body positive approach in greater extent than Modefabriken, mainly by using more plus sized models online but also bigger mannequins in store.
5

Characterization of non-metallic inclusions according to morphology and composition : A comparison of two different steels before and after turning

Gram, Tove, Vickerfält, Amanda January 2015 (has links)
Investigation of non metallic inclusions in two different steels from Sandvik was made before and after turning. After dissolving the non-metallic inclusions by electrolytic extraction the particles were analysed manually or by INCA feature. This was referred to as 3D analysis. INCA feature analysis without extraction of particles was also performed, this was referred to as 2D analysis. The aim of the report was to a make a characterization of non-metallic inclusions with respect to chemical composition, aspect ratio, size and shape. The aim was also to compare different investigation methods. Samples were prepared and investigated. It was obtained that inclusions with sulphur content was elongated and crushed during the turning process. Broken sulphides were detected in one of the steels, and broken oxysulphides in the other steel in the electrolytically extracted chips created by turning. The first steel, steel 1, mainly contained sulphide and oxysulphide inclusions, and steel 2 mainly contained oxysulphides. The aspect ratio obtained by 2D analysis of the sulphide inclusions in steel 1 before turning showed similar results to the electrolytic extracted inclusions measured by hand. The aspect ratio increased with the length of the inclusion. However the deviation of data obtained by the 2D analysis was larger than deviation from the extracted particles measured by hand. The reason for this was assumed to be that the 2D method was not able to analyse the true shape of the inclusions e.g. if inclusions were partly concealed by metal matrix. In analysis of steel 2 the average aspect ratio decreased for oxides and increased for oxysulphides after turning. The chemical composition of inclusions did not change after the turning process for neither of the steels. Copper was detected in the electrolytic extracted inclusions, however not in the 2D investigation by SEM. This is an interesting topic for future research.
6

Kroppspositivismens påverkan på modeföretags storleksutbud : En kvalitativ studie om hur företag implementerar nya arbetssätt utifrån etiska strömningar på sociala medier / The impact of the body positivity movement on fashion companies' size range : A qualitative study of how companies implement new work processes based on ethical currents on social media

Hiort, Elin, Alcenius, Clara, Andersson, Tea January 2021 (has links)
Syfte: Syftet med denna studien är att se hur de etiska strömningarna påverkan modeföretags beslut om att utöka storlekarna och implementera större storlekar. Forskningsfrågorna är 1.  Av vilka anledningar väljer svenska modeföretag att utöka sitt storleksutbud med större storlekar? och 2. Vad har sociala medier och etiska strömningar för inverkan på legitimitetsskapande affärsbeslut?   Teoretiskt ramverk: Denna studie använder sociala medier, den kroppspositivistiska rörelsen och konsekvenser av negativ publicitet som teoretisk bakgrund. Studien är även baserad på viktiga begrepp från institutionell teori; legitimitet, decoupling och mimetic isomorphism. Metod: Denna studie är baserad på en kvalitativ forskningsmetod  med hjälp av intervjuer hos två svenska modeföretag. De anställda som blev intervjuade hade alla roller som antingen varit involverade i beslutet om att utöka storlekar eller som har påverkats av det.   Resultat: Resultaten av studien visar att den kroppspositivistiska rörelsen har haft en inverkan på de studerade företagens beslut att utvidga deras storlek. Andra orsaker som hittades var att undvika negativ publicitet samt skapa legitimitet. / Purpose: The purpose of this study is to see how ethical currents affect fashion companies' decisions to widen their size range and implement bigger sizes. The research questions are 1. For what reasons do Swedish fashion companies decide to widen their size range with bigger sizes? and 2. What influence does social media and ethical currents have on legitimacy based business decisions? Theoretical foundation: This study uses theoretical background on social media, the body positivity movement and consequences of negative publicity. The study is also based on important concepts taken from the institutional theory; legitimacy, decoupling and mimetic isomorphism. Design/methodology/approach: The study is based on a qualitative research method involving two Swedish fashion companies. The employees who were interviewed all have roles that are either involved in the decision to widen the size range or have been affected by it. Findings: The results of the study shows that the body positivity movement has had an impact on the companies' of this study’s decision to widen their size range. Other reasons found were to avoid negative publicity and create legitimacy.
7

On the Manufacturing of SFF Based Tooling and Development of SLS Steel Material

Boivie, Klas January 2004 (has links)
No description available.
8

On the Manufacturing of SFF Based Tooling and Development of SLS Steel Material

Boivie, Klas January 2004 (has links)
No description available.

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