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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Influência da inclinação do garfo de mordida do arco facial na montagem do modelo superior em articulador semi-ajustável do tipo arcon e não-arcon / Influence of the inclination of the face-bow\'s bite fork on mounting of maxillary cast in arcon and nonarcon semiadjustable articulators

Bellodi, Daniele Manfrim 15 August 2008 (has links)
Durante o processo ensino/aprendizagem em Odontologia, é comum a ocorrência de inclinações do garfo de mordida em relação ao plano oclusal maxilar dos pacientes durante a tomada do arco facial realizada por alunos. Este trabalho avaliou a influência das inclinações do garfo de mordida para anterior e para posterior em relação ao plano oclusal na montagem do modelo maxilar em articuladores semi-ajustáveis do tipo arcon e não-arcon. Foram obtidos vinte modelos do arco maxilar de vinte pacientes, nos quais dois pontos foram marcados: um na aresta vestibular do canino direito e outro na aresta vestibular da cúspide mésio-vestibular do primeiro molar direito. Os registros no garfo de mordida foram realizados em três posições: garfo de mordida paralelo ao plano oclusal dos modelos, inclinado para anterior e para posterior (ambas 5º). Cada posição foi repetida cinco vezes, sendo o conjunto articulador/arco facial fixado em suporte especial para registro fotográfico. Cada fotografia foi levada ao programa Auto CAD, obtendo-se linhas de referências para a coleta de cinco medidas (uma angular e quatro lineares). Os dados obtidos foram submetidos à análise estatística paramétrica (Análise de Variância). Os resultados indicaram não haver diferença estatisticamente significante para inclinações do garfo de mordida tanto para anterior como para posterior em relação ao plano oclusal do modelo tanto para o articulador semi-ajustável do tipo arcon como para o não-arcon. O trabalho sugere que pequenas inclinações do garfo de mordida não comprometem a tomada do arco facial e sua transferência para articuladores semi-ajustáveis. / During the process teaching/learning in Dentistry, the occurrence of adverse inclinations of the bite fork concerned to maxillary occlusal plane of patients are current during the face-bow taking performed by students. This study evaluated the influence of the inclinations of bite fork to anterior and posterior related to oclusal plane on mounting of the maxillary cast in arcon and nonarcon semiadjustable articulators. Twenty casts of the maxillary arch from twenty patients were obtained, on which two points were marked: one on the vestibular edge of the right canine and another on the vestibular edge of mesiovestibular cusp of the right first molar. The records in the bite fork were made in three positions: the bite fork parallel to the castss plane occlusal, inclined to anterior and to posterior (both 5°). Each position was repeated five times, being the articulator/face-bow set fixed in special support for photographic register. Each photograph was introduced in Auto CAD program, resulting in lines of references for the collection of five measures (one angular and four linear). The data were subjected to statistical analysis parametric (Analysis of Variance). The results showed no significant statistical difference for inclinations of the bite fork to both anterior and to posterior related to the castss occlusal plane for the arcon and nonarcon semiadjustable articulators. The work suggests that small inclinations of bite fork do not compromise the face-bow taking and its transfer for the semiadjustable articulators.
32

Estudo comparativo da reprodutibilidade do arco facial e de um novo dispositivo com nível de bolha para montagem de modelos maxilares em articulador semi-ajustável / Comparative study of the reproducibility of the face bow and a new bubble level device for mounting maxillary casts semi-adjustable articulator

Cintra, Marina de Godoy Almeida 28 April 2015 (has links)
O arco facial tem seu uso descrito na literatura desde o início do século 20, e atualmente sua eficácia e precisão são controversas. Publicações recentes mostram que a sua reprodutibilidade é passível de erros. Este estudo teve como objetivo comparar a reprodutibilidade do arco facial com a de um novo dispositivo desenvolvido com nível de bolha para a montagem de modelos de gesso em articuladores semi-ajustáveis, por meio da análise de medidas realizadas com a Mesa de Erickson. Os modelos de gesso foram obtidos com moldes de alginato e montados em articulador semi-ajustável marca Bio-art, modelo a7 Plus. A avaliação da reprodutibilidade foi realizada em 10 participantes, com a obtenção de três montagens de seus modelos maxilares, sendo a primeira com o arco facial, a segunda com o dispositivo com nível de bolha estando o participante sentado e a terceira com o dispositivo com nível de bolha estando o participante em pé, cada método foi aferido 3 vezes, por 3 examinadores diferentes. Para cada montagem foram realizadas cinco medidas a saber: a) nas cúspides dos primeiros molares superiores de cada lado (dentes 16 e 26), b) cúspides dos caninos superiores de cada lado (dentes 13 e 23) e c) ponto interincisivo, localizado na linha média. Os valores obtidos foram submetidos ao Cálculo do Erro Técnico da Medida e ao Coeficiente de Variação interexaminador. O presente trabalho concluiu que o arco facial tem uma margem de erro em medidas repetidas maior do que o novo dispositivo desenvolvido. O novo dispositivo mostrou-se mais confortável para os participantes, mas necessita mais testes para avaliarmos sua eficiência. / The face bow has been described in the literature since the early 20th century, and currently its effectiveness and accuracy are controversial. Recent publications show that the reproducibility is error-prone. This study aimed to compare the reproducibility of the face bow with a new device developed with bubble level for the assembly of plaster models in semi-adjustable articulators, through the analysis of measurements performed with Erickson table. The plaster models were obtained with alginate molds and mounted on semi-adjustable articulator brand Bio-art, a7 Plus model. Evaluation of reproducibility was conducted in 10 participants, obtaining three assemblies of their maxillary casts, the first one with the face bow, the second with the bubble level device with the participant being seated and the third level with the device bubble being the participant standing, each method was measured 3 times by 3 different examiners. For each assembly five measurements were performed as follows: a) in the cusps of the upper first molars on each side (teeth 16:26), b) cusps of upper canines on each side (teeth 13:23) and c) interincisal point, located in midline. The values obtained were subjected to measurement of the Technical Error Calculation and inter Coefficient of Variation. This study concluded that the face bow has a margin of error in repeated measurements greater than the newly developed device. The new device was more comfortable for the participants, but it needs more testing to evaluate their efficiency.
33

Metodologia dinâmica de suporte à decisão: estudo de caso da aplicação da metodologia Bow-Tie na análise de risco de um FPSO na fase de operação

Ugulino, Kátia Lúcia da Costa Araújo 03 December 2015 (has links)
Submitted by Joana Azevedo (joanad@id.uff.br) on 2017-07-03T17:09:22Z No. of bitstreams: 1 Dissert Katia Lucia da C A Ugulino.pdf: 5832202 bytes, checksum: 80dc87973043e14d4b57ed7af931bfba (MD5) / Approved for entry into archive by Biblioteca da Escola de Engenharia (bee@ndc.uff.br) on 2017-07-06T15:11:02Z (GMT) No. of bitstreams: 1 Dissert Katia Lucia da C A Ugulino.pdf: 5832202 bytes, checksum: 80dc87973043e14d4b57ed7af931bfba (MD5) / Made available in DSpace on 2017-07-06T15:11:02Z (GMT). No. of bitstreams: 1 Dissert Katia Lucia da C A Ugulino.pdf: 5832202 bytes, checksum: 80dc87973043e14d4b57ed7af931bfba (MD5) Previous issue date: 2015-12-03 / Durante o ciclo de vida de uma instalação de produção de petróleo, estão presentes riscos relacionados à segurança operacional. Na fase de operação, devido à presença de substâncias perigosas (inflamáveis, tóxicas e ou asfixiantes) submetidas a severas condições de processo, os cenários de risco são mais críticos do que nas demais fases. Nesta etapa do ciclo de vida, a gestão inadequada dos riscos de processos favorece a ocorrência de acidentes com alto potencial de danos: elevado número de fatalidades, custos com indenizações, investimentos para a recuperação de áreas contaminadas, pagamentos de multas a órgãos reguladores, perdas de continuidade operacional e consequentemente elevação do custo de produção. Estes eventos, de forma individual ou coletiva, impactam fortemente a sustentabilidade do negócio. Sendo assim, a identificação, análise e gestão destes riscos representam um grande desafio para os gestores do setor de petroquímico. Neste contexto uma das maiores dificuldades é gerenciar os riscos de processo de forma dinâmica. A abordagem proposta neste trabalho baseia-se em um sistema dinâmico de suporte a decisão que adota conceitos da Metodologia Bow Tie e do Método de Análise Hierárquica de Processo (AHP). O modelo proposto foi aplicado na forma de estudo de caso para uma única plataforma e os resultados deste piloto serão analisados a fim de ajustar os limites para alcançar o melhor desempenho em segurança de processo das instalações. / There are many process risks during the lifecycle of an oil production facility. In the operating phase due to the presence of hazardous substances (flammable, toxic and / or asphyxiating) subjected to severe process conditions, the risk scenery are more critical than in other phases. On this phase of lifecycle the inadequate process risk management favors the occurrence of accidents with high potential for damage: high number of fatalities, severance costs, investment for the rehabilitation of contaminated sites, payment of fines to regulatory agent, loss of operational continuity and consequently increase the cost of production. These events, individually or collectively, have a strong impact on business´s sustainability. Thus, the identification, analysis and process risk management in oil and gas production represents a big challenge for the managers of the petrochemical industry. In this context, one of the biggest difficulties is to manage process risks dynamically. The approach proposed in this work based on a dynamic decision support system that adopts concepts of the Bow Tie Methodology and the Hierarchical Process Analysis Method (AHP). The proposed model has been applied in a case study in a single platform and the results of this pilot will be analyze to adjust the limits to achieve the best performance of the facility process safety.
34

Influência da inclinação do garfo de mordida do arco facial na montagem do modelo superior em articulador semi-ajustável do tipo arcon e não-arcon / Influence of the inclination of the face-bow\'s bite fork on mounting of maxillary cast in arcon and nonarcon semiadjustable articulators

Daniele Manfrim Bellodi 15 August 2008 (has links)
Durante o processo ensino/aprendizagem em Odontologia, é comum a ocorrência de inclinações do garfo de mordida em relação ao plano oclusal maxilar dos pacientes durante a tomada do arco facial realizada por alunos. Este trabalho avaliou a influência das inclinações do garfo de mordida para anterior e para posterior em relação ao plano oclusal na montagem do modelo maxilar em articuladores semi-ajustáveis do tipo arcon e não-arcon. Foram obtidos vinte modelos do arco maxilar de vinte pacientes, nos quais dois pontos foram marcados: um na aresta vestibular do canino direito e outro na aresta vestibular da cúspide mésio-vestibular do primeiro molar direito. Os registros no garfo de mordida foram realizados em três posições: garfo de mordida paralelo ao plano oclusal dos modelos, inclinado para anterior e para posterior (ambas 5º). Cada posição foi repetida cinco vezes, sendo o conjunto articulador/arco facial fixado em suporte especial para registro fotográfico. Cada fotografia foi levada ao programa Auto CAD, obtendo-se linhas de referências para a coleta de cinco medidas (uma angular e quatro lineares). Os dados obtidos foram submetidos à análise estatística paramétrica (Análise de Variância). Os resultados indicaram não haver diferença estatisticamente significante para inclinações do garfo de mordida tanto para anterior como para posterior em relação ao plano oclusal do modelo tanto para o articulador semi-ajustável do tipo arcon como para o não-arcon. O trabalho sugere que pequenas inclinações do garfo de mordida não comprometem a tomada do arco facial e sua transferência para articuladores semi-ajustáveis. / During the process teaching/learning in Dentistry, the occurrence of adverse inclinations of the bite fork concerned to maxillary occlusal plane of patients are current during the face-bow taking performed by students. This study evaluated the influence of the inclinations of bite fork to anterior and posterior related to oclusal plane on mounting of the maxillary cast in arcon and nonarcon semiadjustable articulators. Twenty casts of the maxillary arch from twenty patients were obtained, on which two points were marked: one on the vestibular edge of the right canine and another on the vestibular edge of mesiovestibular cusp of the right first molar. The records in the bite fork were made in three positions: the bite fork parallel to the castss plane occlusal, inclined to anterior and to posterior (both 5°). Each position was repeated five times, being the articulator/face-bow set fixed in special support for photographic register. Each photograph was introduced in Auto CAD program, resulting in lines of references for the collection of five measures (one angular and four linear). The data were subjected to statistical analysis parametric (Analysis of Variance). The results showed no significant statistical difference for inclinations of the bite fork to both anterior and to posterior related to the castss occlusal plane for the arcon and nonarcon semiadjustable articulators. The work suggests that small inclinations of bite fork do not compromise the face-bow taking and its transfer for the semiadjustable articulators.
35

Dynamiques et enjeux au sein d'un village de montagne : l'espace Grand Arc - Lauzière, aux portes de la Maurienne (mi XIXe - début XXI e s.) / Dynamics and stakes in a village of mountain : Grand Arc and Lauzière, border of Maurienne (XIXe - XXIe c.)

Villermet, Jean-Marc 26 November 2016 (has links)
Etudier les dynamiques et enjeux au sein d’un village de montagne, en Savoie, engendre une réflexion plus générale sur des questionnements importants de l’époque contemporaine. Jean-Marc Villermet a choisi d’aborder ce sujet pour plusieurs raisons : son attachement à cette région, la proximité des archives, le désir de réactiver le chantier de l’aménagement du territoire en altitude.Il s’intéressa à une région désertée, bien que située dans un espace montagnard réputé pour la qualité de ses sites dans une dimension internationale. Jamais la transformation et les mutations économiques et sociales des zones montagnardes en difficulté, souvent qualifiées d’immobiles, n’ont véritablement été étudiées pour elles-mêmes sous cet angle. Cela semblait donc une piste à la fois nouvelle et tout à fait digne d’intérêt ; d’autant que, situé en Maurienne, le territoire sur lequel se pencha l’auteur demeure aujourd’hui marginal, à l’écart des grands flux touristiques.Ainsi, à partir des années 1860, période où la Savoie devint française jusqu’aux mutations du XXIe siècle, Jean-Marc Villermet a voulu montrer toute la relativité des concepts classiques, voire datés, d’immobilisme ou d’archaïsme, y compris pour un espace montagnard « en souffrance ». Il en étudia les métamorphoses dans toute leur complexité.Cette analyse fine vise à comprendre comment les processus économiques et sociaux ont été portés, vécus et perçus par les individus et comment ils se sont manifestés dans l’espace. Le terrain choisi, l’espace Grand Arc - Lauzière, identifié par le village de Montsapey, dans le canton d’Aiguebelle, sur la rive droite de l’Arc, répond aux critères recherchés : ceux d’une région d’altitude traversée par la déprise rurale depuis un siècle, relativement isolée, bordée en amont et en aval par d’autres territoires beaucoup plus dynamiques.La démarche adoptée se situe au carrefour de plusieurs écoles historiques. Se référant au changement dans sa globalité, ce travail se nourrit des enseignements des grandes thèses classiques d’histoire relatives aux mutations économiques et sociales. Par ailleurs, se réclamant de la micro histoire, l’auteur en utilise les apports et les éclairages.Les sources exploitées proviennent du dépôt des archives départementales de la Savoie et des archives communales sur le territoire étudié. Celles-ci sont confrontées aux documents émanant de différents centres d’archives à Paris. La presse nationale et régionale apporte des éclairages intéressants. Un important travail de collecte d’archives privées a également été effectué, complété par la réalisation de nombreux entretiens et d’un abondant recours à l’iconographie.Proposée dans la première partie de la thèse, l’analyse d’un territoire montagnard a priori fermé, mais en réalité ouvert sur le monde, s’avère riche d’enseignements. Jean-Marc Villermet s’est attaché à démontrer l’importance des mouvements de population en montagne dans une dimension nationale et internationale ; la circulation des hommes et des idées. Il s’agit d’évaluer les conséquences des mouvements migratoires sur l’aménagement du territoire. Les permanences et les « archaïsmes » qui perdurèrent furent accompagnés de regards neufs portés sur la montagne lorsque les hommes explorent les formes, franchissent les reliefs par la voie aérienne et souterraine ou extraient des richesses minérales.La deuxième partie est consacrée aux inéluctables tensions qui perdurèrent pour aménager le territoire : entre offre et demande de montagne. Après la Seconde Guerre mondiale, à l’heure de l’essor des stations de sports d’hiver dans les Alpes, soixante-dix ans de projections permirent d’élaborer des stratégies variées pour dynamiser la pente aux portes de la Maurienne. Des activités économiques pérennes furent envisagées même si elles laissèrent peu de traces durablement. La montagne constitue-t-elle alors un espace de conquête ou d’abandon ? Il y a peut-être de nouveaux concepts à imaginer. / Analysing spatial dynamics and major issues in a mountain village needs to carry out a general review. Jean-Marc Villermet has chosen to study this subject for many reasons : his attachment to the area, public records going back to centuries, and a desire to promote land-use planning at high altitude.His interrest to an abandoned area, even though part of a famous wild space, is consistent with an international focus. All economic, technical and societal developments forcing mentalities and practices to change, have not yet been studied or evaluated from this perspective in moutain areas in trouble, often qualified as unmovable. This clearly is an interesting new lead to follow up on, in at much this area studied by the author remains marginal, out of the major tourism flows.In this way, from the 1860s, date of the french Savoy period, to the beginning of the XXIst century, Jean-Marc Villermet wishes to demonstrate a significant impact on relativity of conventional concepts challenging the status quo, absolute inaction, archaic procedures concerning this remaining action mountain area. The transformation must be assessed with a thorough understanding of this complexity.The narrow consideration of territories also aims to discover the economic and social process implemented, experienced and seen by different groups in society and how they occupied the territorial space. This area, Grand-Arc-Lauziere mountain, identified by Montsapey, a balcony nestled on the Arc river valley, meets the search criteria : a high-altitude isolated land subjected to an over century-long rural decline, impacted upstream and downstream by much more dynamic territories.The approach adopted is at the crossroads of historical trends. Refering to a global change, this study capitalizes on the experience and knowledge that has been accumulated under many PhDs in economic and social history. Availling himself of the micro-history, the author uses its benefits shedding light on the matter.Sources come from records filed with the local and departmental archives, faced with national archives in Paris. The national and regional daily newspapers bring a different approach. A substancial data collection was performed, supplemented with additional interviews and images.As suggested in the first part of the study, analysing major issues in a mountain village, both a closed territory and a land opened up to the World, offers a detailed and insightful account of history. Jean-Marc Villermet is committed to show the huge population swift towards cities with a national and international perspective, movements of people and flows of information. This study evaluates how migratory flows affect land-use planning. Archaic conditions and outdated practices were accompagnied by new perspectives, when people explored the mountains from the air or tunnels and underpasses, to extract mineral resources.The second part is dedicated to the ineluctable tensions that continued : the balance of supply and demand and changes in patterns of mountain request. After World War II, at a time where ski resorts were built in the French Alps, during seventy years, many essential coordinated strategies were prepared to stimulate sustainable, long-term and effective activities on the slope of the mountains around Montsapey. Today, does it reflect the values of a community on a conquered territory or a derelicted place ? An original creative effective concept has to be imagined for the future.
36

Caractérisation de la génération et de la propagation de bulles autour de la carène des navires scientifiques / Characterization of the generation and propagation of bubbles around the hull of scientific vessels

Delacroix, Sylvain 11 March 2015 (has links)
L'une des principales missions de l'Ifremer consiste à étudier les ressources sous-marines et les fonds marins via une flotte océanographique importante, employée à travers le globe. Pour ce faire, les navires sont équipés d'équipements acoustiques de type SONAR afin d'obtenir les informations recherchées dans la colonne d'eau. Dans certaines conditions de navigation, la houle et les mouvements du navire génèrent un entraînement d'air conséquent sous la surface. Des nuages de bulles sont ainsi formés et entraînés sous la carène par l'écoulement. L'interaction entre ces bulles et les ondes acoustiques peuvent entraîner des pertes de données, et par conséquent une diminution importante de la productivité du navire. Les outils permettant l'étude du phénomène sont actuellement limités. Les modèles numériques ne sont pas suffisamment performants, pour simuler conjointement les mécanismes d'entraînement d'air à l'étrave puis l'écoulement dysphasique autour de la carène, et les essais classiques en bassin de traction ne donnent pas entière satisfaction. Dans le cadre de cette thèse, une méthode d'essai spécifique, pour l'étude de ce phénomène, a été développée et mise en place au bassin à houle et courant de l'Ifremer. Cette méthode nécessite la synchronisation entre un générateur de houle et un générateur de mouvement (hexapode), permettant d'imposer les mouvements calculés au préalable par simulation numérique à la maquette. Cette configuration permet d'étudier indépendamment les effets de la houle et des mouvements sur la génération des bulles. L'instrumentation employée permet de filmer et de caractériser l'entraînement d'air à l'étrave de la maquette. Deux mécanismes distincts ont été observés : la génération de bulles par entraînement tourbillonnaire ou par le déferlement de la vague d'étrave. Une méthode de traitement d'image a été élaborée pour analyser ces mécanismes pour de nombreuses configurations d'essais. Une étude paramétrique a été réalisée afin de calculer la fréquence de génération de bulles en fonction de chaque paramètre d'essai. Des mesures PIV de l'écoulement permettent de corréler la dynamique des nuages de bulles et de l'écoulement. L'ensemble des résultats obtenus permet d'apporter des éléments nouveaux pour la compréhension et l'étude du phénomène, avec la perspective d'obtenir un outil fiable facilitant la conception des navires océanographiques. / One of the main assignments of Ifremer is to study the seabed and the resources undersea, through a large oceanographic fleet used across the globe. For that purpose, ships are equipped with different kinds of SONAR (SOund Navigation And Ranging) to obtain the information sought in the water column. In some sea conditions, waves and ship motions generate significant air entrainment below the surface. Bubble clouds are then carried under the hull by the flow. The interaction between these bubbles and the acoustic waves may result in data loss, and therefore in a considerable reduction of the vessel’s productivity. The tools used to study this phenomenon are currently limited : the numerical models are not efficient enough to simulate at a time air entrainment at the bow and the two phase flow around the hull. On the other hand conventional towing tank tests are not entirely satisfactory. During this PhD research work, a specific test method to study this phenomenon has been developed and implemented at the Ifremer wave and current tank. This method requires the synchronization between a wave generator and a movement generator (hexapod) that enables to force the model motions, calculated in advance by numerical simulations. With this configuration, the effects of waves or motions characteristics on the bubbles generation can be studied independently. A complete instrumentation allowed to acquire images sequences to characterize the air entrainment at the bow of the model. Two distinct mechanisms have been observed : the generation of bubbles by vortex shedding or by the breaking bow wave. A post-processing method has been developed to analyse these mechanisms, for many test configurations. A parametric study was performed to calculate the frequency of bubbles generation for each test parameter. PIV measurements allowed to correlate the dynamic of bubbles clouds with the own flow dynamic. The overall results provide new elements for the understanding and the study of the phenomenon, with the final objective of obtaining a reliable tool that facilitates the design of research vessels.
37

A Numerical and Experimental Investigation of High-Speed Liquid Jets - Their Characteristics and Dynamics.

Zakrzewski, Sam, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW January 2002 (has links)
A comprehensive understanding of high-speed liquid jets is required for their introduction into engine and combustion applications. Their transient nature, short lifetime, unique characteristics and the inability to take many experimental readings, has inhibited this need. This study investigates the outflow of a high-speed liquid jet into quiescent atmospheric air. The key characteristics present are, a bow shock wave preceding the jet head, an enhanced mixing layer and the transient deformation of the liquid jet core. The outflow regime is studied in an experimental and numerical manner. In the experimental investigation, a high-speed liquid water jet is generated using the momentum exchange by impact method. The jet velocity is supersonic with respect to the impinged gaseous medium. The resulting jet speed is Mach 1.8. The jet is visualised with the use of shadowgraph apparatus. Visualisation takes place over a variety of time steps in the liquid jet???s life span and illustrates the four major development stages. The stages progress from initial rapid core jet expansion to jet stabilisation and characteristic uniform gradient formation. The visualisation shows that at all stages of the jet???s life it is axi-symmetric. One dimensional nozzle analysis and a clean bow shock wave indicate that the pulsing jet phenomenon can be ignored. In the numerical investigation, a time marching finite volume scheme is employed. The bow shock wave characteristics are studied with the use of a blunt body analogy. The jet at a specific time frame is considered a solid body. The jet shape is found to have an important influence on the shock position and shape. Analysis of the results indicates a shock stand-off similar to that seen in experimental observations and the prediction of shock data. The jet life span is modelled using a species dependent density model. The transient calculations reproduce the key jet shape characteristics shown in experimental visualisation. The mushrooming effect and large mixing layer are shown to develop. These effects are strongest when the shock wave transience has yet to stabilise. Quantitative analysis of the mixing layer at varying time steps is presented.
38

Effect of Wafer Bow and Etch Patterns in Direct Wafer Bonding

Spearing, S. Mark, Turner, K.T. 01 1900 (has links)
Direct wafer bonding has been identified as an en-abling technology for microelectromechanical systems (MEMS). As the complexity of devices increase and the bonding of multiple patterned wafers is required, there is a need to understand the factors that lead to bonding failure. Bonding relies on short-ranged surface forces, thus flatness deviations of the wafers may prevent bonding. Bonding success is determined by whether or not the surface forces are sufficient to overcome the flatness deviations and deform the wafers to a common shape. A general bonding criterion based on this fact is developed by comparing the strain energy required to deform the wafers to the surface energy that is dissipated as the bond is formed. The bonding criterion is used to examine the case of bonding bowed wafers with etch patterns on the bonding surface. An analytical expression for the bonding criterion is developed using plate theory for the case of bowed wafers. Then, the criterion is implemented using finite element analysis, to demonstrate its use and to validate the analytical model. The results indicate that wafer thickness and curvature are important in determining bonding success and that the bonding criterion is independent of wafer diameter. Results also demonstrate that shallow etched patterns can make bonding more difficult while deep features, which penetrate through an appreciable thickness of the wafer, may facilitate bonding. Design implications of the model results are discussed in detail. Preliminary results from experiments designed to validate the model, agree with the trends seen in the model, but further work is required to achieve quantitative correlation. / Singapore-MIT Alliance (SMA)
39

Development of an Ultra Wide-Band(UWB) Synthetic Aperture Radar (SAR)System for Imaging of Near Field Object

Fayazi, Seyedeh shaghayegh January 2012 (has links)
Ultra-wideband (UWB) technology and its use in imaging and sensing have drawnsignicant interest in the last two decades. Extensive studies have contributed toutilize UWB transient scattering for automated target recognition and imagingpurposes. In this thesis a near-eld UWB synthetic aperture radar (SAR) imagingalgorithm is presented.It is shown with measurements and simulation, that it is possible to reconstruct an imageof an object in the near eld region using UWB technology and SAR imaging algorithm.However the nal SAR image is highly aected by unwanted scattered elds at each pixelusually observed as an image artifact in the nal image. In this study these artifactsare seen as a smile around the main object. Two methods are suggested in this thesiswork to suppress this artifact. The rst method combines the scattered eld informationreceived from both rear and front of the object to reconstruct two separate images, onefrom rear view and one from front view of the object respectively. Since the scatteredelds from behind the object are mirrored, the pixel by pixel multiplication of thesetwo images for objects with simple geometry will cancel the artifact. This method isvery simple and fast applicable to objects with simple geometry. However this methodcannot be used for objects with rather complex geometry and boundaries. Thereforethe Range Point Migration (RPM) method is used along with the global characteristicsof the observed range map to introduce a new artifact rejection method based on thedirectional of arrival (DOA) of scattered elds at each pixel. DOA information can beused to calculate an optimum theta for each antenna. This optimum angle along withthe real physical direction of arrival at each position can produce a weighting factor thatlater can be used to suppress the eect of undesired scattered elds producing the smileshaped artifact. Final results of this study clearly show that the UWB SAR accompaniedwith DOA can produce an image of an object free of undesired artifact from scatteredeld of adjacent antennas.
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Terminal transitions : an analysis of projectile points from the terminal middle period on the northern plains

2013 June 1900 (has links)
The Terminal Middle Period (3000 to 2000 B.P.) and the Transitional Late Period (2000 B.P. to 1500 B.P.) contain a number of diverse projectile point styles belonging to several cultural complexes. The cultural complexes studied here include: Pelican Lake, Besant, Outlook, Bracken, Sonota and Sandy Creek. The point styles associated with these complexes have been in the past separated on largely visual or subjective bases. Clarifying the projectile point morphologies during this period will allow for better interpretations of archaeological sites on the Northern Plains. To aid in this clarification, twelve projectile point assemblages from nine previously excavated sites on the Saskatchewan and Alberta Plains were studied. These assemblages were subjected to geometric morphometric and discriminate function analysis. Beyond these two avenues of analysis, the assemblages were also subjected to metric testing to determine if the point styles were more consistent with arrow or dart projectiles. During this time period, the technological transition from the atlatl and dart to bow and arrow appears to have occurred. As a result of the arrow/dart testing, a pattern of robustness was seen in the kill site assemblages as compared to the habitation site assemblages. This resulted in larger points being found in communal kill sites in the study suggesting a link between game size and hunting methods. The result from this analysis recommends a reduction in the independent point styles suggested by other researchers. The data trends towards the finding that two major cultural complexes existed in the Terminal Middle / Transitional Late periods in the studied region of Northern Plains, Pelican Lake and Besant. A third minor group morphologicaly between the two major groups.

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