Rapporten behandlar Kandidatarbete i maskinteknik som utfördes mot Outokumpu Stainless AB, Avesta. Syftet med arbetet var att optimera placeringen för kalkinjektionen som inte sitter optimalt placerat ur ett processoptimeringsperspektiv. Målet var att utveckla placeringen och nyttjandet av kalktillsatsen i ungen, det genom att ändra designen av valvstrukturen och kylpanelen där injektionen satt ursprungligen. Positionen för kalkinjektionen i ljusbågsugnar är normalt sett placerad i hotspotten, området i ugnen där elektronerna är närmst väggen och ger mest slitage på tegelinfodringen. För att hitta en mer optimal placering och lösning studerades befintliga placeringar hos Best in Practice, Tornios och Calverts designs anläggningar, men även ett flertal besök på Outokumpu genomfördes för att skapa en tydligare bild av processen och valvkonstruktionen. En viktig del för den här typen av projekt är konstruera lösningar och att applicera dessa på valvet med hjälp av simuleringar och 3D-modeller. På det sättet går det snabbt att testa lösningar och ge en indikation om det är något som är genomförbart eller inte. Lösningar som togs fram presenterades för Outokumpu som tog beslut om att beställa de nya kylpanelerna med den utformningen som togs fram under projektet. / This report will process a master’s thesis in mechanical engineering in cooperation with Outokumpu Stainless AB, Avesta. The purpose with this work was to optimize the position for the chalk injection which, today, is not optimized from a process position view.  The goal was to develop a position and utilize the chalk supplies and this by changing the design in the vault structure and the cooling panel where the injection originally was placed.  The position of the chalk injection in the arc furnace is normally placed in the hotspots, this is the area in the furnace where the electrodes is closest to the wall and affects the most in terms of wear of the brick lining. To be able to find a more optimal position other chalk injection designs were studied that is already in use, for example in Best in Practice, Tornios and Calverts. There were also visits at Outokumpu in Avesta to create a clearer picture of the process and the vault construction.  One important part for this project was to construct a solution and then apply this on the vault with help from a simulation and 3D-models. To be able to do this Inventor was used, the same program that Outokumpu uses. By using Inventor you can easily try out different solutions and it will give an indication if it is possible to move on with this idea or not. The solutions that were established were presented to Outokumpu who then took the decision to move on with the idea and order the new cooling panel in the design that was created throughout the project.

The Tonga-Kermadec arc in the SW Pacific comprises a chain of more than 90 volcanic complexes. A continuous 400-km long chain of volcanic activity along the central portion of the Tonga arc has become the focus of intensive research, extending previous studies that have focused on the southern Kermadec chain. Earlier interpretations of the Tonga arc have focused on a perceived lack of volcanism between ~21°S and ~27°S, adjacent to a bend in the trench caused by the collision of the subducting Louisville Seamount Chain (LSC). During swath mapping in 2002, it was revealed that this portion of the arc, including the Louisville and Monowai segments, is in fact one of the most volcanically active parts of the Tonga-Kermadec system. At this location, a combination of oblique convergence of the Pacific Plate and southward compression due to the collision of the LSC has resulted in left-lateral strike-slip faulting and rifting of the arc crust. This has produced a series of left-stepping arc transverse graben and horst structures that localize the voluminous volcanic activity. For this study, a new 1:250,000 scale geological map of the Louisville and Monowai segments has been constructed as a framework for a quantitative analysis of arc volcanism and the eruptive history of these segments. Two types of volcanoes dominate the arc front: deep caldera systems (collapse structures formed due to the evacuation of magma) within the arc rifts, and smaller volcanic cones between the rifts. The cone volcanoes tend to have small summit craters (<10 km3) whereas the large caldera volcanoes have major depressions of up to 50 km3. The cones are relatively undeformed, whereas the larger calderas are affected by multiple stages of collapse, asymmetric subsidence, and distortion caused by regional stresses. Surveys of the crater walls of the cone volcanoes show a predominance of volcaniclastic deposits, whereas the caldera volcanoes contain a high proportion of coherent lava flows. The caldera volcanoes also show a prevalence of basaltic melts compared to the more andesitic and dacitic cones. The largest caldera volcano is the Monowai volcanic complex (25°53’S) occupying a deep depression (Monowai Rift Graben) that crosses the arc front. The volcanic complex consists of a large caldera (12 km wide, 1600 m deep) and an adjacent stratovolcano (Monowai Cone) rising nearly to sea level. We suggest that the different types of volcanoes along the Louisville and Monowai segments reflect the influence of deep structures within the arc crust that have localized strikeslip and normal faulting.

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The reaction between carbon and iron oxide-containing slag is crucial to efficient electric arc furnace steelmaking. The reaction occurs via gaseous intermediates, and the rate of gas generation by carbon gasification is limited by the chemical reactions at the slag-gas and carbon-gas interfaces. The aim of the present study was to obtain an understanding of the gasification rate limiting factors and slag foaming behaviour that could be readily applied to industrial electric arc furnace situations. The rate of carbon gasification was measured in experimental simulations of an electric arc furnace heat with slags containing between 21.6 and 48.2 wt% 'FeO'. It was found that rate control was dominated by the carbon-gas chemical reaction. A model was developed which describes the carbon gasification rate, amount of residual carbon in the slag, gas composition, slag-gas interfacial area and bubble diameter during carbon injection into slag. The model predicts rate control by the carbon-gas chemical reaction, in agreement with experimental observations. The slag foaming behaviour was investigated, and it was found that the foaming index is a useful parameter in quantifying foam height only if void fraction is constant with respect to gas flow rate. The average bubble size was observed to be an important factor in determining foam stability, with smaller bubble size resulting in greater foam height. / Thesis / Master of Applied Science (MASc)

Yes / The activity-regulated cytoskeleton-associated (Arc) protein control synaptic strength by facilitating AMPA receptor (AMPAR) endocytosis. Here we demonstrate that Arc targets AMPAR to be internalized through a direct interaction with the clathrin-adaptor protein 2 (AP-2). We show that Arc overexpression overexpression in dissociated hippocampal neurons obtained from C57BL/6 mouse reduces the density of AMPAR GluA1 subunits at the cell surface and reduces the amplitude and rectification of AMPAR-mediated miniature-excitatory postsynaptic currents (mEPSC). Mutations of Arc, that prevent the AP-2 interaction reduce Arc-mediated endocytosis of GluA1 and abolish the reduction in AMPAR-mediated mEPSC amplitude and rectification. Depletion of the AP-2 subunit µ2 blocks the Arc-mediated reduction in mEPSC amplitude, effect that is restored by re-introducing µ2. The Arc/AP-2 interaction plays an important role in homeostatic synaptic scaling as the Arc-dependent decrease in mEPSC amplitude, induced by a chronic increase in neuronal activity, is inhibited by AP-2 depletion. This data provides a mechanism to explain how activity-dependent expression of Arc decisively controls the fate of AMPAR at the cell surface and modulates synaptic strength, via the direct interaction with the endocytic clathrin adaptor AP-2. / This work was supported by the BBSRC_FAPPA BB/J02127X/1 and BBSRC-BB/H018344/1 to SALC and by the FAPESP_RCUK_FAPPA 2012/50147-5 and FAPESP_Young Investigator’s grant 2009/50650-6 to LLdS. SCW was a PhD Student supported be the BBSRC/GSK PhD-CASE Studentship, LPdA is a postdoc fellow supported by FAPESP, YCJ was supported by a FAPESP scientific initiation scholarship.

This study investigated the delivery of electron arc treatment with a trapezoidal aperture. The aim of the investigation is to reduce the nonuniformity of the dose distribution, which is caused by the variation of the patient contour from superior to inferior. The characteristics of static electron beam were first investigated. Then a measurement-based algorithm was developed and implemented as a computer program called EarcMU to calculate the monitor units required for delivering the prescribed dose with a trapezoidal aperture. The central axis percentage depth dose was found to be independent of source-to-surface distance (SSD) and the width of the aperture. The inplane profiles of a trapezoidal aperture show that the dose decreases longitudinally from the wide to the narrow end of the trapezoidal aperture. The EarcMU program was verified using two cylindrical water phantoms. The measured dose and the dose calculated by the program agreed within 2.1% in the typical clinical conditions. A simple method was also proposed for determining the trapezoidal aperture for an individual patient. Under the same conditions, the trapezoidal apertures calculated by this method along with the open aperture were used to deliver treatments to several conical phantoms. Significant improvement in the uniformity of dose distribution was observed. On average, the flatness index of the longitudinal dose distribution from superior to inferior decreases dramatically from 8% for open aperture down to 0.58% for trapezoidal aperture. The results are clinically significant, indicating that delivering the electron arc treatment using a trapezoidal aperture can bring more uniform dose to the patient regardless of the change of patient contour from superior to inferior.

L’étude présentée ici entre dans la problématique générale des arcs électriques intervenant dans des applications industrielles telles que le soudage, le découpage, le traitement des déchets. Ce travail constitue une première phase de modélisation de cette étude générale. Le plasma est décrit par un ensemble d'équations de conservation de fluide et de l’électromagnétisme, complétés par des propriétés thermodynamiques et des coefficients de transport appropriés, en formant un système d’équations non linéaires fortement couplées. Ces équations sont écrites en supposant l’équilibre thermodynamique local, une symétrie cylindrique et un écoulement laminaire stationnaire. Ce système d’équations est résolu à l’aide du logiciel commercial FLUENT de type CFD fondé sur l’approche des volumes finis. Pour pouvoir utiliser la partie solveur nous avons résolu notre modèle en utilisant les routines UDF Users-Defined-Function. Dans une première partie, nous présentons la validation du modèle à deux dimensions et à 100 A dans l’argon par des résultats de la littérature. Cette comparaison laisse apparaître un accord satisfaisant sur les profils de température dans la colonne de plasma et des différences dans les zones proches des électrodes dues aux conditions aux limites. Dans une deuxième partie, nous présentons une étude expérimentale, à l’issue de laquelle on constate que les profils de température expérimentaux sont en accord avec ceux du modèle dans la zone de colonne positive. / The study presented here enters the general problem of electric arc involved in industrial applications such as welding, cutting, waste treatment. This work constitutes the first numerical phase of modeling of this general study. The plasma is described by a set of fluid conservation equations, electromagnetic equations complemented by suitable thermodynamic and transport properties, forming a strongly coupled non-linear system. These equations are written assuming local thermodynamic equilibrium, a cylindrical symmetry and steady laminar flow. This system of equations is solved using commercial software FLUENT CFD-type based on finite volume algorithm. To use the solver part we solved our model using UDF macro Users-Defined-Function. In the first part, we present the validation of the two dimensional model in and 100 A in argon with the literature results. A detailed analysis of various characteristic quantities is presented. This comparison reveals a good agreement of the temperature profiles in the column plasma and differences in electrode areas due to boundary conditions. In a second part, we present an experimental study, the experimental temperature profiles are consistent with the model in the column area which means that the model is validated in the column of plasma.