Zugl.: Stuttgart, Univ., Diss., 2006.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Com o desenvolvimento da tecnologia sem fio, muitos dispositivos eletrÃnicos exigem alta integraÃÃo e que possuam propriedades multifuncionais. Em tal caso, compÃsitos magneto-dielÃtricos tÃm atraÃdo muita atenÃÃo devido as suas propriedades. Nesse sentido, a pesquisa sobre compÃsitos à empregada para a busca de novos materiais. O titanato de cÃlcio (CaTiO3 - CTO) e a granada de Ãtrio e ferro (Y3Fe5O12 - YIG) possuem excelentes propriedades dielÃtricas e ferrimagnÃticas, respectivamente. Este trabalho apresenta a obtenÃÃo do compÃsito ferrimagnÃtico, constituÃdo pelas fases YIG e CTO, atravÃs da rota sintÃtica no estado sÃlido com a utilizaÃÃo de moagem mecÃnica de alta energia. As fases das cerÃmicas foram sinterizadas a 1200ÂC/5h. A DifraÃÃo de Raios-X, a Espectroscopia Raman e MÃssbauer foram essenciais para caracterizaÃÃo estrutural dos compÃsitos. A morfologia das amostras foi elucidada pela Microscopia EletrÃnica de Varredura e auxiliada pela Picnometria a fim de avaliar a densificaÃÃo do material. Adicionalmente, foram realizados experimentos para se avaliar o comportamento elÃtrico e magnÃtico dos compÃsitos na faixa de radiofrequÃncia e de micro-ondas, para depois sugerir uma aplicaÃÃo tecnolÃgica cabÃvel. Os resultados obtidos pela DifraÃÃo de Raio X e da Espectroscopia Raman confirmaram que a sÃntese das fases foi realizada de forma satisfatÃria. As anÃlises qualitativas dos espectros MÃssbauer mostraram boa concordÃncia com os resultados apresentados pela DifraÃÃo de raios-x. Os compÃsitos apresentaram permissividade dielÃtrica praticamente constante na faixa de 50 MHz a 1,5 GHz. Ao analisar o aumento e a diminuiÃÃo da concentraÃÃo em massa de CTO e YIG, respectivamente, foi percebido que os valores de εr aumentaram. A partir dos valores obtidos, pode-se sugerir que o compÃsito sintetizado possui potencial para ser utilizado em dispositivos de micro-ondas, tais como para antenas monopolo. / With the development of wireless technology, many electronic devices require high integration and materials with multifunctional properties. In such a case, magneto-dielectric composites have attracted much attention because they have both magnetic and dielectric properties. In this sense, research on composites is employed to search for new materials. The calcium titanate and yttrium iron garnet possess excellent dielectric properties and ferrimagnetic, respectively. This paper presents the preparation of ferrimagnetic composite, comprising the steps Y3Fe5O12 (YIG) and CaTiO3 (CTO) by the solid state synthetic route with the use of high energy mechanical grinding. The phases of the ceramics were sintered at 1200  C for 5 h. The X-ray diffraction, Raman and MÃssbauer Spectroscopy were used to elucidade structural properties of the composites. The morphological characteristics of the samples were elucidated by Scanning Electron Microscopy and supported by Pycnometry to analyze the densification of the material. Furthermore, experiments to evaluate the electrical and magnetic behavior of composites in the range of radiofrequency and microwave were performed and finally an appropriate technological application was suggested. The results obtained by X-Ray Diffraction and Raman spectroscopy confirm that the synthesis of YIG was successfully obtained. The structural characterization of pure and composite samples was performed successfully and the formation of ionic phase in composites YIG-CTO was found, being in the same family of oxide in which the CTO is inserted. Qualitative analysis of the MÃssbauer spectra showed good agreement with the results reported by x-ray diffraction. The dielectric permittivity composites showed almost constant in the range of 50 MHz to 1.5 GHz. Evaluating the increasing and decreasing in mass concentration of CTO and YIG, respectively and it was realized that the values of εr increased. Two profiles was noticed in the compositional series, it can be inferred that the possibility of the reaction of YIG and CTO products may be interfering with the proper measurements.

This thesis presents a framework for a virtual laboratory for material testing, called Virlab. A virtual laboratory is an open and flexible environment that is used to simulate a set of experiments using a computer. It is beneficial and valuable for researcher and educators to simulate real problems and to conquer some challenges such as a weightless body. The virtual laboratory for material testing contributes both to the field of mechanics of materials and the field of software engineering. In the field of material mechanics Virlab can be used for material testing education and research. Students can rapidly investigate many experiments for materials and the difference between kinematics quantities and stress measures. Virlab also offers a convenient platform for researchers to investigate and test new constitutive equation and implement their new algorithms. Virlab also encourages unambiguous definitions of mechanics terms and principles. In the field of software engineering the contribution is to provide an example of the application of software engineering approaches to an important scientific computing problem. By showing the successful application of software engineer­ing methodologies for a virtual laboratory, it is hoped that software engineering ideas will spread to other scientific applications. In terms of software engineering methodologies, this thesis presents a component-based design for the virtual laboratory for material testing. In this thesis we conduct a commonality analysis for material testing, decompose the system into modules with the information hiding principle, provide an easy way to identify components from the module decompo­sition, and build the component-based system architecture. In this procedure we apply the concept of design through documentation at each stage. / Thesis / Master of Applied Science (MASc)

In semiconductor manufacturing, automated material handling systems (AMHSs) transport wafers through a complex re-entrant manufacturing process. In some systems, Overhead Hoist Transport (OHT) vehicles move throughout the facility on a ceiling-mounted track system, delivering wafers to machines and storage locations. To improve efficiency in such systems, this thesis proposes an adaptive dynamic routing approach that allows the system to self-regulate, reducing steady-state travel times by 4-6% and avoiding excessive congestion and deadlock. Our approach allows vehicles to be rerouted while in progress in response to changes in the location and severity of congestion as measured by edge traversal time estimates updated via exponential smoothing. Our proposed method is efficient enough to be used in a large system where several routing decisions are made each second. We also consider how the effectiveness of a AMHS layout differs between static and dynamic routing. We demonstrate that dynamic routing significantly reduces sensitivity to shortcut placement and allows an eight-fold increase in the number of shortcuts along the center loop. This reduces travel times by an additional 24%. To demonstrate the effectiveness of our proposed routing approach, we use a high-fidelity simulation of vehicle movement. To test the impact of routing methods on layout effectiveness, we developed an associated Excel-based automated layout generation tool that allows the efficient generation of thousands of candidate layouts. The user selects from among a set of modular templates to create a design and all simulation files are generated with the click of a button.

Studiens syfte är att undersöka sju lärares val av undervisningsmaterial vid introduktionen av subtraktion. Utgångspunkten i studien är taget ur livsvärldsfenomenologin, och data har samlats in genom semistrukturerade intervjuer där det kvalitativa datamaterialet sedan analyserats genom olika teman. Resultatet visar att samtliga lärare var överens om att konkret och laborativt material var att föredra vid introduktionen av subtraktion. Läroböckerna användes istället vid ett senare stadium för att hjälpa eleverna att befästa kunskaperna på en mer abstrakt nivå. / The aim of this study is to look into what teaching material seven teachers choose to use during the introduction of subtraction.The study has been inspired by life-world phenomenology, and has been conducted through semi-structured interviews, where the qualitative datasets later have been analyzed through different themes. The results show that all of the teachers agreed that concrete and laboratory materials where to prefer when introducing subtraction. The textbooks were used at a later stage to help the pupils consolidate their knowledge at a more abstract level.

Sammanfattning Syftet med uppsatsen har varit att söka reda på huruvida keramiklera används som material för undervisningen i formgivning i högstadie- och gymnasieskolan, varför eller varför inte materialet används samt att se på lärares inställningar till materialet. Metoden har varit en enkätundersökning bestående av frågor till högstadie- och gymnasielärare rörande olika aspekter vad gäller materialet keramiklera och lärarnas inställning till materialet. De svar enkätundersökningen gett visar på att keramiklera inte är vanligt förekommande i undervisningen för formgivning. Resultaten visar även att lärarna i brist på passande lokal, brännugn och tid väljer in andra material i sin undervisning som skulle kunna ersätta keramikleran.

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