Das Stranggießen von Stahl ist mit 96 % Marktanteil das weltweit wichtigste Verfahren zur Stahlherstellung. Im Gießprozess beeinflusst das Strömungsprofil in der Kokille entscheidend die Qualität des erstarrten Stahls. Um eine möglichst optimale Kokillenströmung einzustellen, werden Aktuatoren eingesetzt, die die sich bewegende Schmelze kontaktlos mithilfe der Lorentzkraft beeinflussen. Diese Aktuatoren würden auch eine Strömungsregelung ermöglichen, wenn eine geeignete Messtechnik für heiße Schmelzen vorhanden wäre. Allerdings lösen bislang verfügbare Messverfahren vor allem die Strömung im Randgebiet der Kokille auf und sind häufig in ihrer zeitlichen Auflösung limitiert. Eine neue infrage kommende Messtechnik ist die berührungslose induktive Strömungstomographie (contactless inductive flow tomography, CIFT), die aus der gemessenen strömungsinduzierten Verzerrung eines angelegten Magnetfeldes die dreidimensionale Strömung rekonstruieren kann. In dieser Arbeit wird anhand eines 1:8-Labormodells einer Stranggusskokille und numerischen Simulationen untersucht, ob CIFT bei Anlagen mit elektromagnetischen Bremsen eingesetzt werden kann. Besondere Herausforderungen entstehen aufgrund der Verzerrung des CIFT-Anregungsmagnetfeldes durch die ferromagnetische Bremse, der großen Dynamik von 6 Größenordnungen zwischen dem Magnetfeld der Bremse und dem strömungsinduzierten Magnetfeld sowie intrinsischen Strömungsoszillationen mit einer charakteristischen Frequenz im Bereich der üblicherweise verwendeten CIFT-Anregungsfrequenzen. Es wird dargelegt, dass sich CIFT in derartigen Aufbauten einsetzen lässt, wenn (a) eine geeignete Anregungsmagnetfeldstruktur erzeugt werden kann, (b) gradiometrische Induktionsspulen als Magnetfeldsensoren eingesetzt werden und (c) die Anregungsfrequenz in einem optimalen, schmalen Bereich gewählt wird. Diese Messungen werden erst durch in dieser Arbeit dargelegte theoretische und experimentell validierte Analysen der Induktionsspulen möglich, wofür Schwerpunkte auf deren Modellierung, Design und Messunsicherheit gelegt wurden. Außerdem werden für dieses Stranggussmodell erstmals experimentelle Ergebnisse mit horizontal anstatt vertikal orientierten Anregungsmagnetfeldern präsentiert. Um die Skalierbarkeit von CIFT in Richtung industrieller Anlagen zu demonstrieren, werden zum einen CIFT-Strömungsrekonstruktionen in einem heißen 1:2-Labormodell einer Kokille vorgestellt. Eine weitere Herausforderung für CIFT ist die in industriellen Kokillen typischerweise aufgebrachte ferromagnetische Nickelschicht, die eine verzerrende und abschirmende Wirkung auf umgebende Magnetfelder hat. Diese Beschichtung stellt aufgrund ihrer zeitlich und räumlich schwankenden Permeabilität eines der größten Hindernisse für die Anwendung von CIFT im industriellen Stahlguss dar. Die Auswirkung dieser Beschichtung auf CIFT wird mit numerischen Simulationen quantifiziert. Dabei werden neue, im Rahmen dieser Arbeit patentierte Anregungsgeometrien untersucht und erste Strömungsrekonstruktionen gezeigt. / Continuous casting of steel is the most relevant steel casting method worldwide, with a 96 % market share. During the casting process, the flow profile in the mold has a decisive impact on the quality of the solidified steel. In order to obtain an optimal flow, electromagnetic actuators are employed to influence the melt by Lorentz forces in a contactless manner. Yet, tailored flow control is difficult, since conventional flow measurement techniques provide information with limited temporal or spatial resolution when applied to hot melts. One novel measurement technique that comes into question is contactless inductive flow tomography (CIFT), which relies on measuring the flow-induced perturbations to an applied magnetic field, and subsequent reconstructions of the three-dimensional flow. Using a 1:8 lab model of a casting mold and numerical simulations, this thesis examines if CIFT can be applied to continuous casters with electromagnetic brakes. Specific challenges arise from the distortion of the CIFT excitation field by the ferromagnetic brake, the dynamic range of 6 orders of magnitude between the magnetic field of the brake and the flow-induced magnetic field, as well as intrinsic flow oscillations with a characteristic frequency close to the CIFT excitation frequency. It is demonstrated that CIFT can be applied to these kind of setups, if (a) a proper structure of the excitation field can be achieved, (b) gradiometric induction coil sensors are employed and (c) the excitation frequency is chosen within an optimum narrow range. These measurements were enabled by novel theoretical analyses of the induction coils with corresponding experimental validation. Furthermore, for the first time, experimental results using a horizontally applied magnetic field are presented, in contrast to older experiments relying on a vertical magnetic excitation field. Additionally, this thesis presents CIFT flow reconstructions for a hot 1:2 model of a continuous casting mold, in order to demonstrate the scalability of CIFT towards industrial facilities. Moreover, the effects of ferromagnetic nickel coatings on CIFT, which are typically found in industrial casting molds, are quantified using numerical simulations. These coatings pose one of the most challenging obstacles for the industrial application of CIFT, since their temperature-dependent permeability shows temporal and spatial variations. For this scenario, new excitation geometries—developed and patented within the scope of this thesis—are investigated and first flow reconstructions are presented.

A partir de la fin de l’Antiquité, les grands bronzessont peu à peu délaissés puis abandonnés. Il faudra attendre laseconde moitié du XVIème siècle pour voir réapparaître dans lepaysage artistique français, sous François Ier, de grandsensembles statuaires en bronze. Au coeur de ce phénomène, latechnique tient un rôle majeur et suscite plusieursinterrogations. D’abord, se pose pour cette période la questionde l’existence ou non d’une identité technique des bronzesfrançais. L’exécution d’une statue en bronze implique denombreuses étapes qui conduisent du modèle à saretranscription dans le métal. Peut-on reconnaître dans cesétapes et dans les manières de les aborder une certaine unitétechnique qui marquerait la seconde moitié du XVIème siècle,voire le début du XVIIème en France ? Inversement, remarqueton dès cette période de réintroduction différentes écolesregroupant certains sculpteurs, fondeurs, ateliers, voire liées àcertains chantiers particuliers ? Par ailleurs, la réapparition dessavoir-faire associés à la statuaire en bronze pose la questiondes origines. D’où viennent ces techniques soi-disant oubliées :d’autres centres européens, de pratiques de fonderie concernantd’autres types de production ?Dans ce travail de thèse, nous nous sommes attachés à apporterdes éléments de réponse à ces différentes interrogations. Pource faire, des études technologiques ont été menées sur troisgrands ensembles marquant cette période de renouveau dansl’art du bronze : les copies en bronze de marbres antiques parPrimatice, les Vertus du monument funéraire d’Henri II et deCatherine de Médicis, les Allégories du monument de coeurd’Anne de Montmorency.Pour compléter ce corpus, des éléments isolés ont été étudiés :la Diane chasseresse de Barthélémy Prieur, l’Apollon duBelvédère, le Gladiateur Borghèse et la Vénus Médicisattribués à Hubert le Sueur. L’objectif a été de tenter de révélerprocédés, matériaux et savoir-faire engagés, complétant ainsiles données fournies par les documents d’archives quiaccompagnent ces commandes prestigieuses. La stratégied’étude employée a bénéficié de l’expérience des travauxentrepris ces trente dernières années. Des développementsméthodologiques ont néanmoins été nécessaires pour compléterles possibilités offertes par l’étude technologique de la statuaireen bronze. Ces développements ont en particulier concerné lesnoyaux de fonderie, ces matériaux employés pour réaliser desstatues creuses. Les résultats obtenus montrent que lespremières décennies de réappropriation de la grande statuaireen bronze sont marquées par l’emploi d’un même procédé àl’épargné qui trouve racine dans les procédés employés auMoyen-âge pour la fonte de cloches ou de canons par exemple.Mais dés le XVIIème siècle, le monopole de ce procédé sembleêtre mis à mal, preuve sans doute d’une émancipation desfondeurs et d’une innovation constante. Parallèlement à cesphénomènes dont les conséquences marquent la fonte statuaireen général, les sculpteurs, les fondeurs, développent dans leursateliers des savoir-faire personnels et innovent au cas par cas,selon la nature des commandes qu’ils reçoivent. / At the end of Antiquity, the manufacture of largebronzes is progressively abandoned. It reappears during the16th century in France, under the reign of Francis I, after morethan a millennium of quasi absence. At the heart of thisphenomenon, casting techniques play a major role and raisesseveral questions. First, the technical identity of large bronzescasted during this period must be investigated. Indeed, castinga statue involves numerous steps, from the model to the finalform in bronze: are those technical steps identifiable throughthe bronze statues characteristics? Are those featurescharacteristic of the craftsmanship of 16th century? Second,can we identify particular ways of bronze crafting associatedwith different schools, composed by sculptors and, or, foundrymen? The origins of technical skills are also to be questioned,especially the provenance of forgotten techniques: Europeanneighborhood or influence of metallurgical techniquesassociated to other kind of objects?In order to answer those questions, technical studies have beencarried out. A representative body of statues has beeninvestigated: the bronze copies of antique marble statues byPrimaticcio at the Fontainebleau palace, the Virtues and theroyal praying statues from the funerary monument of Henry IIand Catherine de’ Medici and the three Personifications thatdecorate the hearth monument of Constable Anne deMontmorency. Several isolated statues have also been studiedin order to complete the body of statues: Diana the huntress byBarthélémy Prieur, Borghese Gladiator and Apollo Belvedereattributed to Hubert le Sueur.This work aims at revealing the processes, materials andknowhow involved for each steps of bronze statuesmanufacture, in order to complete the data extracted fromarchive documents associated to those prestigious royalcommissions. The employed methodology is based on theexperience on this field of research acquired since threedecades by researchers all over the world. New developmentshave also been made to improve technological studies, such asan innovative approach for the characterization of castingcores. . Data obtained from the investigated body of statuesreveal that during the first decades of the 16th century, aspecific casting technique has been used: a spare process. Thisprocess has been strongly influenced by techniques steamingfrom the late Middle-age and the early modern period. Indeed,it exhibits technical similarities with bell and canon casting.However, the uniqueness of this process is challenged by theemergence, during the 17th century, of a second technique,namely the slush process. Emancipation of foundry-men fromthe main stream technique, and will of innovation mightexplain this change of process. Simultaneously to thosetechnical evolutions, sculptors and foundry-men developspecific skills and knowhow that influence the characteristicsof their bronze statues. Moreover, case to case adaptation alsoappears to influence the bronze statues characteristicsaccording to the kind of commission charged by the craftsmen

The thesis deals with optimization of the continuous slab casting process. The thesis summarizes the basic analytical and empirical findings concerning to the solidification process, the numerical modeling and the selected optimization techniques. Physical conditions and factors that affect the quality of steel including their relationships are also described. The basis of the solution strategy is the original numerical model of the temperature field in its off-line version. The numerical model was verified by the real historical data. The optimization part is based on the fuzzy logic implemented above the numerical model. The optimization algorithm is used for the optimal control of the casting process. The universal usage of the optimization model is demonstrated on several cases, e.g. the finding of optimal casting parameters that ensure the high quality of products, the optimal reactions on breakdown situations, the determination of an optimal relationship between casting parameters, etc. Based on optimization results, the suitable caster modification to increase the surface temperature at the unbending point was proposed. The whole concept of the numerical and optimization model is general and it can be applied to arbitrary slab or billet continuous casting.

This thesis deals with accelerated 3D rendering of medical data, e.g. computed tomography, using a graphics processor and OpenGL library. Raw data slices are send to graphic memory and rendered by a ray-casting algorithm. The goal of this project is high quality visual output and full user interaction at the same time. Multiple rendering modes are avaiable to the user: MIP, X-Ray simulation and realistic shading.

The purpose of this project was to observe and analyze Takis Muzenidis' methods of casting, rehearsal procedures and philosophy of directing as illustrated.in his production of The Libation Bearers at North Texas State University. Chapter I is an introduction to Muzenidis' background, qualifications and purpose for being at North Texas. Chapter II is a subjective description of Muzenidis' methods of casting, style of directing and relationship with the cast and crew. Chapter III discusses problems that occurred in the production. Chapter IV examines the production results through an audience analysis and interviews with the cast and crew. Chapter V is a summary of the thesis with a personal evaluation of the production and the director.

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No description available.

Companies strive to optimize their processes to increase productivity, efficiency, and quality in the production system. The complexity of different operations in a production system can vary, the level of complexity impacts the automation approach. The requirements of an automated solution increases with the level of complexity. A vision system is a type of automation solution which can improve the quality inspection process in many companies where the inspection process is performed manually. A challenge with implementing a vision system in different industries is that there are no general solutions. Depending on the requirements of an industry, the implementation of a vision system needs to be tailored to suit that industry. In this thesis, a case study is conducted in a foundry setting where empirical data is gathered through observations and interviews conducted with several departments. Nine parameters are identified which can affect the performance of a vision system in a metal casting environment. The identified parameters are analysed using relevant literature to find possible solutions. The result of the analysis is a set of guidelines which can be used when implementing vision systems in the metal casting industry and aims to mitigate possible negative effects of each parameter. A conceptual layout of a vision cell used to inspect cylinder heads based on the guidelines is also presented.

Byggandet av dagens sjukhus har blivit allt mer komplext. När det kommer till uppbyggnaden av stomkonstruktionen har kraven för vibrationer ökat. För att säkerställa kraven för stomvibrationer måste pågjutningens tjocklek öka med ca 90 mm från standarden som är ca 40 mm. Att utföra denna extra pågjutning är inte ett problem i sig, utan den extra torktiden som tillkommer. Den extra torktiden är inte det enda problemet. De beräkningsprogram som finns ute på marknaden idag kan inte behandla alla typer av konstruktioner och simuleringar, dock skulle det kunna gå att dela upp simuleringsprocessen för uttorkningen emellan beräkningsprogrammen. I denna studie så kommer två olika simulering/beräknings program att tillämpas. Beräkningsprogrammen som kommer att användas är TORKA S och WUFI. Torktiderna kommer att räknas fram genom att kombinera dessa program samt titta på tidigare studier gällande detta projekt. I denna studie har vi valt att ta en närmare titt på hur foggjutningen mellan håldäcken påverkar torktiden för hela delområdet, dvs. foggjutningen och pågjutningen. Resultaten visar att vct för foggjutningen måste vara betydligt lägre än vct för pågjutningen och att torktiderna varierar beroende på vct. Torktiderna för pågjutningen varierar om mätningar görs över fog eller mitt på håldäcken. / Constructions of hospitals today have become more complex than before. As for the construction of the frame structure, the requirements for vibration in the body have increased. To fulfill the requirements for frame vibrations the top coating thickness must be increased with 90 mm ​​from the standard thickness, which is around 40 mm. To perform this extra topping is not the biggest issue. The major problem is the extra drying time that is added in the process. Another large problem is the calculation programs that are available on the market today cannot deal with all types of designs and simulations; however it would be possible to divide the simulation process for the dehydration between different calculation programs. In this study, two different simulation/calculation programs will be used. The programs that will be applied are TorkaS 3.2 and WUFI Pro. Drying times will be generated by combining these programs and look at previous studies similar to this project. In this study we have chosen to take a closer look at how joint cast between the slabs affects the drying time for the entire sub-area, which is the joint cast and topping cast. The results of the w/c-ratio for joint cast must be significantly lower than w/c-ratio for topping and that drying times will vary depending on the w/c-ratio. Drying times for topping will also vary if measurements are made over the joint or middle of the slab.

The fluid flow in the mold during up-hill teeming is of great importance for the quality of the cast ingot and therefore the quality of the final steel products. At the early stage of the filling of an up-hill teeming mold, liquid steel enters, with high velocity, from the runner into the mold and the turbulence on the meniscus could lead to entrainment of mold flux. The entrained mold flux might subsequently end up as defects in the final product. It is therefore very important to get a mild and stable inlet flow in the entrance region of the mold. It has been acknowledged recently that swirling motion induced using a helix shaped swirl blade, in the submerged entry nozzle is remarkably effective to control the fluid flow pattern in both the slab and billet type continuous casting molds. This result in increased productivity and quality of the produced steel. Due to the result with continuous casting there is reason to investigate the swirling effect for up-hill teeming, a casting method with similar problem with turbulence. With this thesis we will study the effect of swirling flow generated through a swirl blade inserted into the entry nozzle, as a new method of reducing the deformation of the rising surface and the unevenness of the flow during filling of the up-hill teeming mold. The swirling blade has two features: (1) to generate a swirling flow in the entrance nozzle and (2) to suppress the uneven flow, generated/developed after flowing through the elbow. The effect of the use of a helix shaped swirl blade was studied using both numerical calculations and physical modelling. Water modelling was used to assert the effect of the swirling blade on rectifying of tangential and axial velocities in the filling tube for the up-hill teeming and also to verify the results from the numerical calculations. The effect of swirl in combination with diverged nozzle was also investigated in a similar way, i. e. with water model trials and numerical calculations. / QC 20101115