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This dissertation explores the education of foster care children through the perspectives of classroom teachers. Numerous studies have found that foster youth experience depressed educational outcomes relative to their peers. A meta-analysis of such studies reported depressed educational outcomes in terms of standardized test scores, grade averages, retention rates, and suspension and expulsion rates (Scherr, 2007). Foster care is most often associated with maltreatment, which in turn has been linked to depressed educational outcomes (Runyan, 1985) and to insecure attachment (Howe, 1999). Attachment theory, which emphasizes the impact of relationships in early childhood on future relationships, informed this study. Purposeful sampling was used to identify classroom teachers in a rural Vermont high school that serves a large number of foster youth relative to its size. Participants were selected based on their high degree of experience with and perceived success in supporting students in foster care. In interviews, teachers were asked to describe distinguishing characteristics of foster youth as well as their relationships with peers and adults while at school. Teachers described several characteristics of foster youth, including the perceived impact of trauma on foster youth‟s ability to attend to school and school related tasks. Teachers also characterized intense relationships between foster youth and their peers, and between foster youth and adults at school. Participants also identified several strategies they believed to be effective in supporting this population, each of which emphasized the development of caring relationships between teachers and foster youth. Teachers shared concerns about the impact of frequent placement changes on the educational experiences of foster youth. Interviewees also noted that their support of foster youth was hampered by insufficient information about changes in students‟ status. Intersections between the characteristics of foster youth and selected literature on attachment theory and traumatic stress are explored in the interpretation of the findings. Finally, this study utilizes a feminist ethic of care to contextualize relationships between foster youth in schools and effective teacher strategies.

Properties of cast aluminum components can be improved by strategically placing ferrous inserts to locally improve properties such as wear resistance and stiffness. A cost-effective production method is to cast-in the insert using the solidification of the molten aluminum as a joining method. Metallurgically bonding between the metals could potentially improve both load and heat transfer across the interface. The metallurgical bond between the steel and the aluminum has to be strong enough to withstand stresses related to solidification, residual stresses, thermal expansion stresses, and all other stresses coupled with the use of the component. Formation of a continuous defect free bond is inhibited by the wetting behavior of aluminum and is governed by a diffusion process which requires both energy and time. Due to the diffusional nature of the bond growth in combination with post manufacturing heat treatments defects such as Kirkendall voids can form. The effect of aluminum alloying elements during liquid-solid bond formation in regards to microstructural changes and growth kinetics has been described. A timeframe for defect formation during heat treatments as well as microstructural changes has been established. The effect of low melting point coatings (zinc and tin) on the nucleation of the metallurgical bond has been studied as well the use of a titanium coating for microstructural modification. A set of guidelines for successful metallurgical bonding during multi- material metal casting has also been constructed.

"Theoretical issues relating to the aerospace sand casting simulation are laid out, identifying parameters used in the model. A sensitivity analysis is performed to examine the mold-metal heat transfer coefficient, mold thermal conductivity, wall friction factor, pouring basin pour temperature, and pouring basin head pressure through doing coupled flow simulations on thin-walled castings using the commercial casting simulation software, MAGMASOFT. A verification exercise is done to match simulation with reality with the knowledge that mold-metal heat transfer coefficient and mold thermal conductivity are the most influential parameters of the five. Validation on a real production casting is performed using the tuned parameters from the verification exercise."

Ray tracing acceleration methods are usually applied to scenes defined by triangle meshes.These scenes contain a large number of triangles. In contrast, CSG scenes contain orders of magnitude less more complex primitives primitives. In this thesis we will present the Operation KD-tree. This acceleration method applies the KD-tree --- modern acceleration method developed for triangle meshes --- directly to the CSG scene. This is done on the premise, that the huge reduction in primitive count will yield enhanced performance, when rendering a scene using CSG instead of triangle meshes.

An elasto-visco-plastic deformation model predicts stresses and distortions in a low-carbon steel casting. Features of the model include rate and hardening effects, temperature-dependent properties, and pressure-dependent deformation in the mushy zone. A volume-averaging technique considers the multiple phases during solidification and is used to formulate the conservation equations, which (due to a weak link between temperatures and deformations) are decoupled and solved sequentially using commercial software. Temperature fields are calculated first using MAGMAsoft (MAGMAsoft, MAGMA GmbH, Kackerstrasse 11, 52072 Aachen, Germany) and then exported to a finite element software package, ABAQUS (Abaqus/Standard, Abaqus, Inc., Providence, RI, 2006), which predicts stresses and distortions. In order to simulate the conditions encountered in an industrial casting process, predicted temperatures and distortions are matched with experimental data from in situ casting trials. Preliminary simulations do not agree with the experimental distortions, which suggest that stress-strain data from mechanical tests (from which the mechanical properties were estimated) does not accurately characterize the material behavior of a casting during solidification and cooling. The adjustments needed to match measured and predicted distortions provide valuable insight to the effect a solidified microstructure has on its mechanical properties.

Master of Science in Dentistry / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

This paper documents the investigation into injection molding, or die casting, a bulk metallic glass (BMG). A BMG is an amorphous metal of a thickness greater than 25 ��m, according to leading researchers in the field. This critical thickness differentiates a normal metallic glass from a "bulk" metallic glass. The impetus for studying the ability to process lies in the material properties of the BMG, which has twice the strength of steel and the ability to be formed much like a thermoplastic. An initial discussion of processing options and history precedes a detailed description of the machine concept and design, including the governing parameters placed on the design. An account of methods and materials used has been included, along with problems encountered and resultant remedies. The initial results consist of the verification of the machine concept and the ability to replicate nanometer-sized surface features from a mold. Design issues are addressed and the corresponding revisions described. The final machine revision shows an increase in process repeatability. A presentation of photographs, which show results of forming the BMG against both copper and stainless steel, is offered as a qualitative assessment of the processing capability. A discussion of considerations and paths forward has been included for future research using the machine that was developed, but these processing theories could also be carried over to other experiments. In the end, this study proves the ability to form extremely small surface features in cast BMG parts and makes suggestions on research avenues that may give a better understanding of the variables involved in processing BMG from the molten state. / Graduation date: 2003

A direct historical approach is used in this thesis to document the lost wax casting technique as currently practiced by indigenous metallurgists in northeastern Thailand. The smiths observed at Ban Pba Ao, Ubon Ratchathani Province are the last practicing members of a bronze working tradition that has been in continuous operation at the village for two centuries. An account of the processes used to create bronze bells is provided. Of particular significance is the fact that the yard in which casting activities are performed did not receive clean up operations following the bells production. As a result, hearths, bowl furnaces, crucibles and fragments of clay moulds are left scattered about the yard. These materials accumulating in one location would eventually create a mound of cultural debris. The discarded materials from the lost wax casting process as practiced at Ban Pba Ao provide considerable insight into what might be found in the stratigraphy of Peninsular Southeast Asian prehistoric sites that were involved in the production of bronze objects. The study concludes that attention needs to be paid to the stratigraphic sequences from which bronze artifacts are extracted, rather than relying on the artifacts to determine the type of process used in their manufacture.

Detta examensarbete utförs i sammarbete med ett företag som tillverkar produkter i polyuretan. Syftet med en av dessa produkter är att skydda kablar mot böjande samt axiella krafter. Företaget tillverkar idag denna produkt genom att tillföra gjutmassan underifrån, vilket leder till att gjutmassan trycks upp i konstruktionen. Detta är för att luftbubblor inte ska uppstå. Företaget har dock problem när det gäller tillverkning av produkten då den innehåller mer än tre ton gjutmassa. Företagets process blir begränsad till gjutmassans brukstid och komponentblandarens materialflöde, därför krävs en ny metod för att tillverka produkter med större volym. Detta arbete ska undersöka olika möjligheter att tillverka produkter som väger upp till sex ton och är upp till åtta meter långa genom att tillföra gjutmassan ovanifrån. Metoden får inte ge upphov till defekter så som rullningar, sprickor eller att luftbubblor uppstår hos produkten. Metoden ska även vara pålitlig då tillverkning av produkter med större dimensioner är kostsamt. Först görs en litteraturstudie för att undersöka på vilka olika sätt som gjutformen kan fyllas. Detta ger att gjutningen sker med Open Casting. När gjutmetoden är bestämd så genomförs en brainstorming där olika metoder för att tillverka produkten tas fram. Beräkningar på hållfastheten och volymen hos gjutformen samt arbetstrycket i slangarna som transporterar gjutmassan utförs på den metod som väljs till fortsatt arbete. Beräkningarna ger att slangarna som gjutmassan ska transporteras i 10 meter upp till gjutformen inte kan ha en större diameter än 25 mm för att trycket i slangen inte ska bli för lågt eller att ytnivån hos gjutmassan inte ska höjas för snabbt mot slutet av gjutprocessen. Hållfasthetsberäkningarna visar att gjutformen måste förstärkas då det vätsketryck som uppstår från gjutmassan ger upphov till plasticering. Ytterligare undersökningar görs på de yttre komponenter som krävs för att utföra den framtagna metoden. En av dessa är olika lösningar på hur styrningen av munstyckets position i förhållande till gjutmassans yta kan ske. Det görs även en undersökning på hur slangarna som gjutmassan transporteras i ska matas upp ur gjutformen. Då det kommer vara få produkter som tillverkas varje år på företaget så dras slutssatsen att ingen motordriven samt positioneringsutrustning är ekonomiskt försvarsbara att införskaffa, utan det ska istället utföras med beräkning av gjutnivån samt handarbete vid matning av slangen. / This bachelor thesis is made in cooperation with a company that manufactures polyurethane products. The purpose with one of these products is to protect cables from bending and axial forces. Today the company produces this product by adding the resin blend from beneath, which leads to the resin blend being pushed up in the construction. This prevents air entrapments from appearing. The company has problems with manufacturing products that are larger than three tonnes. The company’s process gets limited by the resin blend’s potlife and the dispensing equipment’s material flow; that is why a new manufacturing method for products with larger volumes is needed. This thesis is going to study the possible ways to manufacture products that are up to six tonnes and eight meters high by adding the resin blend from above. The process should not cause defects such as flow marks, cracks or air entrapments in the product. The process should also be reliable since manufacturing of products with large volume is expensive. First a literature study is made to examine different ways to fill the cast. The study shows that the filling of the cast should be made by Open Casting. When the cast method is determined a brainstorming is implemented where different methods to manufacture products are developed. On the method that is selected for continued work calculations on strength and volume of the cast and the working pressure in the hoses that transports the resin blend is made. These calculations show that the hoses that transport the resin blend 10 meters up to the cast cannot have a larger diameter than 25 mm, since the working pressure in the hoses should not be too low or that the surface of the resin blend should not rise to fast at the end of the casting process. The strength calculation of the cast shows that it must be reinforced since the pressure from the resin blend cause stresses larger than the yield strength. Additional studies are made on the outer components that are needed to perform the chosen method. One of these was different solutions on how the steering of the nozzles position in relation to the surface of the resin blend could work. A study on how the hoses that transports the resin blend should be moved up to the cast is also made. Since few products will be manufactured by the company each year it is determined that no engine or equipment for positioning the nozzle is economically viable to procure, this should instead be made by calculations of the resin blend surface and manual labor by the operator to move the hoses.