Espirais concentradoras têm sido largamente empregadas no beneficiamento de finos de carvão no Brasil. O objetivo geral deste trabalho foi estudar do beneficiamento de carvão em uma espiral, avaliando a eficiência do beneficiamento do carvão da Camada Barro Branco e caracterizando seus produtos. Ênfase foi dada ao rejeito, avaliando as possibilidades de aproveitamento do material e o seu potencial de geração de acidez. A metodologia do trabalho incluiu a caracterização da alimentação e dos produtos de uma espiral em termos de análise imediata e enxofre; estudo da lavabilidade do carvão de alimentação; avaliação da eficiência do beneficiamento e a caracterização do rejeito em termos ambientais. Em valores médios, a alimentação das espirais apresenta um teor de cinzas de 67,5%, um teor de enxofre de 5,2% e um poder calorífico superior de 2377 cal/g. O concentrado apresentou um teor de cinzas de 50,5%, um teor de enxofre de 1,7% e um poder calorífico superior de 3978 cal/g; enquanto que o rejeito um teor de cinzas 78,2%, um teor de enxofre de 7,5% e um poder calorífico superior de 1364 cal/g. A recuperação mássica de concentrado é de aproximadamente 40%. O concentrado atende as especificações da termoelétrica em relação ao teor de enxofre e matéria volátil, mas não atende as especificações de cinzas e poder calorífico. O concentrado das espirais consegue destinação uma vez que é misturado a carvões de melhor qualidade produzidos pela mesma ou outras mineradoras. Quanto a lavabilidade, na densidade de corte de 2,0, o valor do NGM foi de 15%, caracterizando o material como moderadamente difícil ou de difícil separação. A eficiência do beneficiamento na espiral é baixa. O valor do Desvio Provável Médio (EPM), Imperfeição (I) e a Área de Erro foram, respectivamente, de 0,30, 0,30 e 178,13 cm2. Esses parâmetros apontam que o equipamento não apresenta uma boa precisão de separação. O rejeito de carvão descartado da espiral apresenta um NNP de – 209 kg CaCO3/t, indicando um alto potencial de geração de drenagem ácida. Deve-se somar a isso a baixa granulometria (entre 0,1 e 2,0 mm) e a alta área superficial (41 m2/g) do material, que propiciará taxas mais altas de geração de acidez que o rejeito grosso. Analisando os dados, as espirais, mesmo com a baixa precisão, estão exercendo sua função de forma satisfatória para a empresa no sentido de produção de um carvão energético com teor de S aceitável. / Spiral concentrators have been widely used to process coal fines in Brazil. The aim of this work was to study coal beneficiation in a spiral, evaluating its performance for the “Barro Branco” seam. Emphasis was given to the waste material, evaluating a potential use and the acid generation. The methodology of this project included the characterization of the feed and the products of the spiral in terms of immediate analysis, washability curve of coal, and the equipment efficiency in terms of Tromp Curve. The feed material has an ash content of 67.5%, a sulfur content of 5.2%, and a gross calorific value of 2377 cal/g. The concentrate showed an ash content of 50.5%, a sulfur content of 1.7% and gross calorific value of 3978 cal/g; while the reject one had an ash content of 78.2%, a sulfur content of 7.5%, and a gross calorific value of 1364 cal/g. The recovery of the concentrated weight is approximately 40%. The concentrated meets the thermal specifications related to sulfur content and volatile matter, but it does not meet the specifications of ashes and calorific values. So, it is mixed with coals of better quality to attend the thermoelectric standards. Concerning the wash ability, in the cut density of 2.0, the NGM was 15%, characterizing the material as moderately difficult or difficult to separate. Analyzing the Tromp Curve, the value of the deviation probable medium (EPM), Imperfection (I) and the Error Area were, respectively, 0.30, 0.30 and 178.13 cm2. These parameters indicate that the equipment does not show a good precision of separation. The rejected material on the spiral showed a NNP of - 209 kg CaCO3/t, indicating a high potential for acid drainage generation. It should be considered that the material presented a fine particle size (0.1 to 2.0 mm) and a high surface area (41 m2/g), which certainly will provide high pyrite oxidations rates. Analyzing the data as a whole, spirals, even with the low precision, is exercising their function to provide an energetic coal with an acceptable sulphur content, leaving no doubt about its applicability.

Spiral waves occur in several natural phenomena, including reaction fronts in two-dimension excitable media. In this thesis we attempt to characterize the motion of the spiral tip of a rigidly rotating wave and a linearly travelling wave in the context of a lattice perturbation. This system can be reduced to its center manifold, which allows us to describe the system as ordinary differential equations. This in turn means dynamical systems methods are appropriate to describe the motion of the tip. It is in such a context that we work on spiral waves. We study perturbed rotating waves and travelling waves using standard techniques from dynamical systems theory.

A triaxialidade dos halos das galáxias espirais foi estudada através das funções de distribuição de razões axiais aparentes dos seus discos. Utilizou-se uma amostra de galáxias limitada por magnitude (g<16). Foram selecionadas ~1600 galáxias espirais do SDSS (Sloan Digital Sky Survey), que foram classificadas morfologicamente por inspeção visual. Para evitar contaminações espúrias, removeram-se da amostra galáxias em interação, com companheiras próximas ou aproximadamente alinhadas com estrelas da Galáxia. As razões axiais das galáxias foram medidas individualmente e com critérios uniformes, ajustando-se isofotas elípticas a cada imagem no filtro r. Um algoritmo de Monte Carlo foi empregado para inferir a distribuição de razões axiais intrínsecas. O modelo de disco oblato é incapaz de reproduzir a observada falta de galáxias aparentemente circulares. A fração reduzida de galáxias aparentemente circulares, que se observa sistematicamente nas espirais de todos os sub-tipos morfológicos, é uma forte indicação de que os discos destas galáxias sejam intrinsecamente elípticos. O modelo triaxial mostrou-se mais estatisticamente significativo, além de ser capaz de prever a fração correta de galáxias quase circulares. Concluímos, portanto, que o modelo de disco não-circular descreve melhor as observações e que a razão dos eixos no plano do disco deve ser de p = 0,849 +/- 0,063. Empregando uma abordagem analítica simplificada, nós propusemos uma descrição da formação de halos escuros triaxiais no contexto de colisões de protogaláxias. Aproximando as protogaláxias por elipsóides homogêneos de Jacobi, notamos que a triaxialidade do objeto resultante de uma fusão depende da velocidade de colisão e calculamos a época em que estes encontros devem ter ocorrido, para gerar elipsóides com a triaxialidade em questão. Estimamos que neste cenário os discos das galáxias espirais tenham sido construídos a partir de aproximadamente z = 0,69 +/- 0,32. / The triaxiality of the halos of spiral galaxies was studied through the distribution function of the apparent axial ratios of their disks. We used a magnitude-limited sample of galaxies (g<16). We selected ~1600 spiral galaxies from the SDSS (Sloan Digital Sky Survey), which were morphologically classified by visual inspection. In order to avoid spurious contaminations, interacting galaxies were removed from the sample, as well as those with nearby companions or with foreground stars. The axial ratios of the galaxies were measured individually and with uniform criteria, by fitting elliptical isophotes to each r-filter image. A Monte Carlo algorithm was used to infer the distribution of intrinsic axial ratios. The oblate disk model is unable to account for the observed lack of apparently circular galaxies. The small fraction of apparently circular galaxies, which is systematically observed in spirals of all morphological subtypes, is as strong indication that the disks are indeed intrinsically elliptical. The triaxial model is more statistically significant and also, it is able to predict the correct fraction of nearly circular galaxies. We find, therefore, that the non-circular disk model provides a better description of the observations and that the axes on the plane of the disk should be in the ratio p = 0.849 +/- 0.063. By adopting a simplified analytical approach, we propose a description of the formation of triaxial dark halos in the context of collisions of protogalaxies. Assuming that the protogalaxies might be represented by homogeneous Jacobi ellipsoids, we noted that the triaxiality of the resulting object depends on the collision velocity. We also find the epoch at which such encounters would yield the required triaxiality. We estimate that in this scenario the disks of spiral galaxies would have been assembled at z = 0.69 +/- 0.32.

No description available.

No description available.

No description available.

myth (n.) A traditional story which embodies a belief regarding some fact or phenomenon of experience, and in which often the forces of nature and of the soul are personified; a sacred narrative regarding a god, a hero, the origin of the world or of a people.2 A parable; An allegory. From the French word mythe (1818) and directly from Modern Latin mythus, which originated from ancient Greek mŷthos : "speech, thought, discourse, word, humour, conversation, story, saga, tale, anything delivered by word of mouth". Attested in English since 1830. Ever since I was a child, I have been fascinated with the fictional world of stories and the act of of storytelling. Always wide-eyed and excited, I remember the countless times that I have lost myself in the mythical worlds in stories. It is moments of sadness or of anxiety, but also of wonder, of ecstasy even, the experience of the beautiful under one or the other of its innumerable forms, the joy of love, of discovery, of happiness in that sense, that are most likely to remind us of our humanity. Hence, when I started my thesis about wanting to explore the design of a built space through the context of storytelling, I was confused. There were these three questions that hounded me at every turn : 1. What is a "place for storytelling"? Does the act of storytelling really exist within the confines of a particular "place"? 2. And if yes, do stories emerge from places? Or do places emerge from stories? What is the nature of the relationship between both? 3. And if places truly are born out of stories, is it possible to craft a journey through a built space akin to our journey through the mythical worlds of a storyteller? / Master of Architecture / What is a "place for storytelling"? Do stories emerge out of built spaces? Or do built spaces emerge out of stories? I had questions on the relevance of architecture in something as raw and primal as the act of storytelling. But what I did not anticipate was that, of all the many different things that I was exploring, the path that I was to actually take would lie in a children's book that I had never heard about before. It was pure serendipity that I chanced upon it, and later it changed my whole thesis in ways that I could not imagine. I realized that I needed not to find "answers" to questions; but rather enjoy this beautiful journey that I was on. The magic of storytelling cannot be shut within walls, but needs to grow outwards. Storytelling is as much about excitement as it is about contemplation. It is about remembering the child within us, and about taking a moment to stop and watch sunsets. It is about rituals and thresholds and gazing at stars. It is about shattering the layers and layers of "grown-up" ideas that we tightly wrap ourselves with. It was when I stopped looking for answers, that I could truly understand what is the nature of the built space that I was dreaming of. Rather than being a single elusive construct - it was an eclectic mix of many different experiences tied together into a journey, guided by a little boy with golden hair.

No / At the University of Bradford, the midwifery team have developed an innovative approach to the delivery of their midwifery programme. This includes the use of a spiral curriculum that is underpinned by problem based learning. A spiral curriculum is one that facilitates an iterative revisiting of topics, subjects or themes throughout the programme. The approach is not simply one of repetition but one that enables the student to achieve deeper knowledge with each turn of the spiral.

Ziel: Minimalinvasive Techniken, wie die videoassistierte Thoraxchirurgie (VATS), sind heutzutage zur Resektion vor allem peripher gelegener Rundherde Methode der Wahl. Um eine schnelle und sichere intraoperative Lokalisation zu gewährleisten, haben sich diverse Markierungstechniken etabliert. Wir berichten über die Erfahrungen bei 184 Markierungen mittels eines speziellen Lungenmarkierungsdrahts, der CT-gestützt präoperativ an den Herd gebracht wird. Material und Methoden: Bei 184 Patienten (97 m, 87w, mittleres Alter: 58,1 ± 13,7 Jahre) wurde unmittelbar vor der VATS eine CT-gesteuerte Markierung des Rundherds mithilfe eines Spiraldrahts vorgenommen. Evaluiert wurden anschließend die Erfolgsrate, die Sicherheit der Intervention, die Notwendigkeit eines Umstiegs zur Thorakotomie sowie die Histologie der Patienten. Ergebnisse: Der Markierungsdraht konnte in 181 Fällen (98,4 %) erfolgreich platziert werden. Eine Markierung musste aufgrund eines nicht beherrschbaren Pneumothorax abgebrochen werden. Geringgradige, methodisch nicht vermeidbare Komplikationen wie Mantelpneumothoraces (53,3 %) oder perifokale Blutungen (30,4 %) bedurften keiner Therapie. Die makroskopisch vollständige Entfernung der markierten Herde gelang bei 98,4 % der Patienten. Aufgrund intraoperativer Komplikationen (Adhäsionen, Blutungen, Drahtdislokationen) war in 29 Fällen (15,9 %) die Konversion zur Thorakotomie erforderlich. Die Histologie ergab in 96 Fällen (52,5 %) einen benignen Befund, in 87 Fällen (47,5 %) einen malignen, wobei insgesamt lediglich 21 Herde (11,5 %) einem primären Lungenkarzinom entsprachen. Schlussfolgerung: Die Kombination aus CT-gesteuerter Herdfixierung mittels Spiraldraht und die anschließende thorakoskopische Entfernung ist eine effiziente und sichere Methode zur Diagnostik von unklaren intrapulmonalen Rundherden, insbesondere für periphere, subpleural gelegene Herde.

This thesis presents an analysis of the behavior of an equiangular spiral antenna using a mixture of numerical and measurement techniques. The antenna is studied as an isolated element and as a part of a spiral-based ground-penetrating radar (GPR) detection system. The numerical modeling was based on the parallelized finite-difference time-domain method and the model was validated by comparison with a prototype antenna and detection system. The intention is to isolate the effect of varying different geometrical parameters that define the spiral element or the spiral GPR system. With some notion of each parameter's effect, systems that use the spiral antenna can be designed more easily. The analysis of the spiral antenna in isolation provides a set of design graphs for the antenna. A set of design graphs are constructed that allow one to better understand the effect of the chosen dielectric substrate on the characteristic impedance of the antennas. A second set of design graphs give very specific data about the lower cut-off frequency possible for the antennas given a requirement on its minimum boresight gain, axial ratio, or voltage standing-wave ratio when matched with an appropriate transmission line. The analysis of the spiral antenna in the context of a detection system provides information on the effect of the ground on the GPR system and to what extent the circular polarization properties of the spiral antenna play a role in GPR. It is shown that a spiral antenna used in a monostatic radar configuration will reject a symmetric scatterer well into the near-field. The importance of a resistive loading to the spiral arms is demonstrated for this rejection to be optimal. In addition, it is shown that increasing the dielectric constant of the ground narrows the pattern and polarization properties, making the antenna more directive towards boresight when the spiral antennas radiate into a flat ground. In addition to this work, a method for reducing the truncation error when calculating the planewave spectrum of an antenna is described.