The thesis treats roll pass design in wire rod rolling of stainless steel for sequences and series built up by two-symmetrical grooves. It is focused on predicting rolling flexibility, also called working range, as well as product quality. For analysing the flexibility a computer program has been developed. The minimum and maximum roll gap and corresponding bar areas for series of grooves including "oval", "round", "false round", "square" and "diamond" shapes are calculated. Six pass designs used in Swedish mills are analysed. Full-scale rolling is compared with laboratory experiments for the square-oval and false round (round)-oval series. The false round-oval series offers the largest working range and that the flexibility is smaller for pass sequences designed for high reductions. The false round-oval series are also acknowledged as a series for high quality steels and are usually better than the square-oval series having a tendency for defect formation. The thesis also includes high-speed rolling of wire rod in blocks. Here interstand tensions are utilised in order to keep the process stable. For obtaining the required dimensional tolerances of the product they are kept as low as possible. However interstand tensions could be used in order to increase the working range and move the product range towards smaller wire cross sections. For analysing this possibility, a narrow spread technology is utilised. At present time a practical problem is referred to the fixed gearings in the common blocks, which require a certain and given level of interstand tensions and corresponding reductions. This problem can however be solved by means of new block design and modern process control technology. Roll stands can be separately driven and controlled at very high speeds. Thus the eight stand blocks can be subdivided into four plus four passes blocks with a cooling line between enabling also higher productivity without violating the product quality because defect formations caused by a too high rolling temperature. The true working range of a series for a specific steel grade is however not only dependent on the possible spectrum of wire dimensions that can be obtained but might also depend on its ability to decrease or eliminate defects such as surface cracks. Thus, the behaviour of artificial V-shaped cracks in the longitudinal direction has been investigated and compared for the square-oval and false round (round)-oval series mentioned above. In agreement with other research works it was established that efficient rolling conditions for reducing the cracks are obtained when the cracks open up at the same time as their depth is reduced. If the V-shaped crack is closed by contact between its oxidized side surfaces the rolling schedule is not optimal for getting a high quality product. A deeper understanding of the experimental results was obtained by means of an FE-analysis

No description available.

<p>The thesis treats roll pass design in wire rod rolling of stainless steel for sequences and series built up by two-symmetrical grooves. It is focused on predicting rolling flexibility, also called working range, as well as product quality. For analysing the flexibility a computer program has been developed. The minimum and maximum roll gap and corresponding bar areas for series of grooves including "oval", "round", "false round", "square" and "diamond" shapes are calculated. Six pass designs used in Swedish mills are analysed. Full-scale rolling is compared with laboratory experiments for the square-oval and false round (round)-oval series. The false round-oval series offers the largest working range and that the flexibility is smaller for pass sequences designed for high reductions. The false round-oval series are also acknowledged as a series for high quality steels and are usually better than the square-oval series having a tendency for defect formation. The thesis also includes high-speed rolling of wire rod in blocks. Here interstand tensions are utilised in order to keep the process stable. For obtaining the required dimensional tolerances of the product they are kept as low as possible. However interstand tensions could be used in order to increase the working range and move the product range towards smaller wire cross sections. For analysing this possibility, a narrow spread technology is utilised. At present time a practical problem is referred to the fixed gearings in the common blocks, which require a certain and given level of interstand tensions and corresponding reductions. This problem can however be solved by means of new block design and modern process control technology. Roll stands can be separately driven and controlled at very high speeds. Thus the eight stand blocks can be subdivided into four plus four passes blocks with a cooling line between enabling also higher productivity without violating the product quality because defect formations caused by a too high rolling temperature. The true working range of a series for a specific steel grade is however not only dependent on the possible spectrum of wire dimensions that can be obtained but might also depend on its ability to decrease or eliminate defects such as surface cracks. Thus, the behaviour of artificial V-shaped cracks in the longitudinal direction has been investigated and compared for the square-oval and false round (round)-oval series mentioned above. In agreement with other research works it was established that efficient rolling conditions for reducing the cracks are obtained when the cracks open up at the same time as their depth is reduced. If the V-shaped crack is closed by contact between its oxidized side surfaces the rolling schedule is not optimal for getting a high quality product. A deeper understanding of the experimental results was obtained by means of an FE-analysis</p>

Cette thèse est constituée de deux contributions scientifiques qui ont donné lieu à deux séries d'articles. On construit dans la première une symétrie vectorielle dans les théories cohomologiques via une généralisation de l'équation de Baulieu-Singer, qui définit avec l'opérateur BRST topologique un sous ensemble de générateurs de supersymétrie admettant une représentation qui détermine l'action de la théorie de manière unique.<br /><br />La seconde série propose une méthode pour renormaliser les théories supersymétriques de Yang-Mills en l'absence de schéma de régularisation préservant à la fois l'invariance de jauge et la supersymétrie. La prescription de renormalisation est obtenue en définissant deux opérateurs de Slavnov-Taylor compatibles respectivement pour l'invariance de jauge et la supersymétrie. La construction de ces derniers nécessite l'introduction de champs additionnels que nous avons appelés les champs d'ombre. Nous avons ainsi été en mesure de démontrer la renormalisabilité des théories de Yang-Mills supersymétriques et l'annulation de la fonction beta dans le cas de la supersymétrie maximale. <br /><br />Après une brève introduction, le second chapitre propose une revue de la théorie de Yang-Mills de type cohomologique en huit dimensions. Le chapitre suivant examine les réductions dimensionnelles en sept et six dimensions de cette théorie. Le dernier chapitre propose quand à lui des résultats indépendants, sur une interprétation géométrique des champs d'ombre, ainsi que des travaux non publiés sur la gravité topologique en quatre dimensions, des considérations sur la symétrie superconforme et enfin la solution des contraintes dans le super-espace twisté.

In Part I we are dealing with effective description of Yang-Mills theories based on gauge-invarint variables. For pure Yang-Mills we study the spin-charge separation varibles. The dynamics in these variables resembles the Skyrme-Faddeev model. Thus the spin-charge separation is an important intermediate step between the fundamental Yang-Mills theory and the low-energy effective models, used to model the low-energy dynamics of gluons. Similar methods may be useful for describing the Electroweak sector of the Standard Model in terms of gauge-invariant field variables called supercurrents. We study the geometric structure of spin-charge separation in 4D Euclidean space (paper III) and elaborate onconnection with gravity toy model. Such reinterpretation gives a way to see how effective flat background metric is created in toy gravity model by studying the appearance of dimension-2 condensate in the Yang-Mills (paper IV). For Electroweak theory we derive the effective gauge-invariant Lagrangian by doing the Kaluza-Klein reduction of higher-dimensional gravity with 3-brane, thus making explicit the geometric interpretation for gauge-invariant supercurrents. The analogy is then made more precise in the framework of exact supergravity solutions. Thus, we interpret the Higgs effect as spontaneous breaking of Kaluza-Klein gauge symmetry and this leads to interpretation of Higgs field as a dilaton (papers I and II). In Part II of the thesis we study rather simple field theories, called “geometric” or “instantonic”. Their defining property is exact localization on finite-dimensional spaces – the moduli spaces of instantons. These theories allow to account exactly for non-linearity of space of fields, in this respect they go beyond the standard Gaussian perturbation theory. In paper V we show how to construct a geometric theory of chiral boson by embedding it into the geometric field theory. In Paper VI we elaborate on the simplest geometric field theory – the supersymmetric Quantum Mechanics and construct new non-perturbative topological observables that have a transparent meaning both in geometric and in the Hamiltonian formalisms. In Paper VII we are motivated by making perturbations away from the simple instantonic limit. For that we need to carefully define the observables that are quadratic in momenta and develop the way to compute them in geometric framework. These correspond geometrically to bivector fields (or, in general, the polyvector fields). We investigate the local limit of polyvector fields and compare the geometric calculation with free-field approach.

Made available in DSpace on 2016-01-13T13:27:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-06. Added 1 bitstream(s) on 2016-01-13T13:31:35Z : No. of bitstreams: 1 000677106.pdf: 2599098 bytes, checksum: d9013a92ac254365852ffbd2bc1b8ced (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / In this thesis, we are dedicated to study the time evolution generated by the hamiltonian of a classical Yang-Mills-Higgs theory with gauge symmetry SU(2) on a spatial lattice. In particular, we study energy transfer and equilibration processes among the gauge and Higgs sectors, calculate the maximal Liapunov exponents regarding to random initial conditions in the regime of weak coupling, where one expects them to be related to the high-temperature static plasmon damping rate, and investigate their energy and Higgs self-coupling parameter dependence. We further examine finite-time and finite-size errors, value the impact of the Higgs fields on the instabilty of constant non-abelian magnetic fields and comment on the implications of our obtained results for the thermalization properties of gauge fields at finite temperature in the presence of matter.

Este estudo tem por objetivo analisar o impacto das variáveis tamanho e localização na eficiência operacional de usinas de cana-de-açúcar no Brasil. Para isso, foram utilizados os dados referentes à moagem e produção de açúcar e de etanol das usinas brasileiras listadas no anuário da cana-de-açúcar na safra 2008/2009. Desta forma, realizou-se um estudo de eficiência operacional, por meio da aplicação da Análise Envoltória de Dados (DEA), na qual foi possível identificar as usinas mais eficientes dentre um universo de 355 usinas e classifica-las por tamanho, localização e eficiência operacional. A análise quantitativa sugere que existe uma maior concentração de usinas classificadas como eficientes e de tamanho grande, localizadas no estado de São Paulo. Objetivando uma análise em profundidade foi realizado um estudo de múltiplos casos em um grupo de usinas. Ademais, foi feita uma entrevista com especialistas do setor sucroalcooleiro. Dessa forma, conclui-se que a eficiência operacional de usinas de cana-de-açúcar depende da variável tamanho, na medida em que as usinas de maior porte tendem a investir mais em tecnologias que proporcionam um maior ganho de eficiência operacional. A eficiência também depende da variável localização, na medida em que o estado de São Paulo apresenta condições edafoclimáticas mais favoráveis à extração de uma cana-de-açúcar com maior teor de sacarose, que, consequentemente, pode influenciar na eficiência operacional de usinas de cana-de-açúcar. O presente estudo, portanto, fornece subsídios para que gestores destas empresas possam alcançar maior eficiência operacional, bem como fornecer suporte a decisões de investimento nesse setor, uma vez que a escolha da localização e da tecnologia pode influenciar na eficiência. / This research aims to analyze the impact of the variables size and location over the operational efficiency of sugarcane mills producing sugar and ethanol in Brazil. Thus, data concerning total milling and total production of sugar and ethanol plants, was collected regarding Brazilian sugarcane mills listed in the 2008/2009 sugarcane yearbook. A ranking of operational efficiency was developed, applying Data Envelopment Analysis (DEA) technique, through which was possible to verify which were the most efficient among 355 sugarcane mills and, therefore, compare the variables size, location and operational efficiency among the Brazilian mills. The quantitative analysis suggests that among the efficient groups, there is a major concentration of larger mills, located in the state of São Paulo. Aiming an in-depth analysis, a multiple-case study was conducted in a group of sugarcane mills, and interviews with experts in the sugarcane industry were developed. Therefore, the conclusion is that operational efficiency of sugarcane mills depends on the variable location, as larger mills tend to invest more in technologies that provide major gain in operational efficiency. The operational efficiency depends also on the location of the sugarcane mill, as the state of São Paulo provides favorable edaphoclimatic conditions for the juice extraction of sugarcane with a higher level of sucrose content, hence possibly having influence over the operational efficiency. This study, therefore, provides subsidies so that managers may obtain higher levels of operational efficiency, as well as support decisions of investments in the sugarcane industry, as the decisions concerning location and size may influence the sugarcane mill efficiency.

Orientador: José Tomaz Vieira Pereira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T10:41:26Z (GMT). No. of bitstreams: 1 Dalbem_JoseAntonio_M.pdf: 4137996 bytes, checksum: d9ffaa0145fff06b3a4f264c94e03244 (MD5) Previous issue date: 2007 / Resumo: O sucesso atual da cadeia sucro-alcooleira no Brasil, como largamente divulgado, tem como principal motivador o esforço tecnológico decorrente da implantação do pró-álcool na década de 70, com expressivo desenvolvimento das atividades agrícolas e industriais. Mas, considerando que as centenas de empresas do ramo sucro-alcooleiro nacionais buscam conhecimentos, equipamentos e insumos praticamente nas mesmas fontes, necessário se faz entender as razões pelas quais há uma ampla diferença de resultados em termos de eficiências de produção, tanto nas atividades agrícolas como nas industriais. As diferenças de solo, clima e cultura regionais, mesmo considerando as diferentes idades das usinas, não seriam suficientes para explicar tal variação de eficiências. Neste trabalho, pela experiência do autor como gestor em atividades de refino de petróleo, e por analogia com o observado nas atividades de refino no Brasil e no mundo, considera que diferentes práticas de gestão devem contribuir bastante para tais diferenças de resultados. Este trabalho, visando à confirmação dessa consideração, apresenta a análise de correlação comparativa entre práticas de gestão e resultados energéticos de usinas de açúcar e álcool. A análise foi aplicada em quatro usinas pré-selecionadas. A avaliação das práticas de gestão, para determinação da pontuação das usinas, seguiu os critérios da Fundação Nacional da Qualidade, mais especificamente a do Rumo a Excelência - 500 pontos, de 2006, de modo simplificado. Os resultados energéticos de eficiência de conversão de sacarose da cana-de-açúcar em produtos finais, medido pela eficiência industrial relativa Copersucar, e de eficiência de consumo de energia nos processos de produção de açúcar e álcool, medido pela sobra de bagaço, foram recebidos diretamente das usinas ou calculados a partir de dados fornecidos por elas. A pontuação obtida na avaliação simplificada pelos critérios da FNQ mostrou que as usinas pesquisadas têm bons sistemas de gestão. A análise comparativa entre as pontuações de gestão e as eficiências industriais, de conversão de açúcares e de consumo energético dos processos, mostrou que há relação direta entre elas. A eficiência de consumo dos processos aparenta ser bastante dependente da adoção ou não de estratégia de geração e venda de energia elétrica. Entretanto, considerando a pequena amostra de apenas quatro usinas, essas afirmações não podem ser generalizadas. Para assegurar confiabilidade nas conclusões das análises ela deve ser aplicada em uma amostragem maior de usinas / Abstract: The current success of sugar and alcohol plants in Brazil, as widely diffused, was primarily encouraged by the technological effort secondary to the establishment of pro-alcohol in the 1970s, with remarkable development of agricultural and industrial activities. However, considering that the hundreds of national companies dealing with sugar and alcohol production search for knowledge, equipments and supplies nearly in the same sources, there is the need to understand the reason why there is a wide difference in production efficiency results, both in agricultural and industrial activities. Even considering the different periods of establishment of plants, the differences in regional soil, weather and culture would not be enough to explain these variable efficiencies. Considering the experience of the author as manager of petroleum refinement activities, and by comparison with performance observed in refinement activities in Brazil and in the world, the present study considers that different management practices should have appreciate contributions for such differences in results. This study presents a comparative correlation analysis between management practices and energy results of sugar and alcohol plants, with a view to confirm this consideration. The analysis was applied to four pre-selected plants. Evaluation of the management practices to determine the score of plants followed the criteria of the National Quality Foundation (FNQ), more specifically of Aiming at Excellence - 500 points, in 2006, in simplified manner. The energy results of efficiency of converting the sucrose from sugar cane in final products, evaluated in Copersucar relative industrial efficiency, and of relative energy consumption in the processes of sugar and alcohol production, evaluated in surplus bagasse, were directly supplied by the plants or calculated from data provided by them. The score achieved in the simplified evaluation by the FNQ criteria demonstrated that the plants investigated have good management systems. Comparative analysis of management scores with efficiency of sucrose conversion and surplus bagasse demonstrated a direct correlation among them. The relative energy consumption in industrial process seems to be quite a lot dependent of strategies for to generate and sell electric energy. However, considering the small sample of only four plants, these statements cannot be generalized. The analysis should be applied to a larger sample of plants in order to assure its reliability in the conclusions achieved / Mestrado / Mestre em Planejamento de Sistemas Energéticos

Abstract The results of the comparison of various dissolution methods for sulphur showed, that HNO3 together with H2O2 gave more complete decomposition of organic components than HNO3 alone. The acid procedure with a mixture of HNO3+H2O2 slightly underestimated the S concentrations of plant material. The losses of sulphur were the highest in the dry ashing digestion procedure (HF(DAC)). The Leco combustion technique with infrared (IR) detection gave good precision and accuracy for sulphur. For the determination of heavy metals in plant materials, both the HNO3 and HNO3+H2O2 procedures were especially effective for determining Cr. However, the HNO3+HClO4 procedure gave lower results, and HF and HF(DAC) procedures greater values for Cr. Sulphur accumulation in pine needles around the pulp and paper mills was clearly higher than other points in the Kemi area. For example, within a radius of about 1-1.5 km around the mills of Oy Metsä-Botnia Ab Kemi Mills, the sulphur concentrations for (C) and (C+1) needles were 28 % and 26 % higher than those in the corresponding background samples collected in Kuivaniemi at a distance about 25 km from Kemi. Pine needles do not appeared to be appropriate a method for monitoring the accumulation of Fe, Zn, V and Pb emitted from pulp and paper mills. However, the Ca concentrations in (C+1) needles in the vicinity of the Oy Metsä-Botnia Ab Kemi Mills was 48 % higher than the average Ca concentration calculated from all (C+1) needles; thus it is likely that part of the Ca in the needles is derived from the mills. The regional distribution pattern of Cr and Ni in mosses in the Kemi-Tornio area in 2000 showed clearly that the most polluted area (Cr > 200 μg/g and Ni > 20 μg/g) appeared to lie within a few kilometres of the ferrochrome and stainless steel works of AvestaPolarit Stainless Oy. Within this area, the Cr concentrations in mosses were 4-13 times higher than those outside the urban area of Tornio. The area most polluted by the opencast chromium mining complex (Cr > 200 μg/g and Ni &lt; 20 μg/g) appeared to be in the immediate vicinity of complex. All the 95th percentile values for TSP (total suspended particles) in the mine area of AvestaPolarit Chrome Oy Kemi Mine were below the current Finnish air quality limit value of 300 μg/m3. However, the 98th percentile value exceeded the Finnish air quality guideline value of 120 μg/m3 at one monitoring site. According to leaching studies, the sum of calculated annual airborne pollution impact of water-soluble fraction (H2O) and environmentally mobile (CH3COONH4) fraction from the AvestaPolarit Chrome Oy Kemi Mine was Cr 1.2 kg, Fe 29 kg, Cu 63 kg, Ni 2.5 kg and Cd &lt; 100 mg. According to the homogeneity studies of heavy metal deposition on TSP filters, Cr, Ni, Cu and Fe were non-uniformly distributed over the glass fibre filters. The rsd values varied between 5.4-33.9 % for Cr, between 7.5-35.0 % for Ni, between 3.6-25.9 % for Cu, and between 6.6-19.9 % for Fe.

No description available.