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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.
191

A digitalização do design de mobiliário no Brasil: panorama e tendências / The digitization of furniture design in Brazil : trends and outlook

Paulo Henrique Gomes Magri 08 April 2015 (has links)
O objetivo desta pesquisa é confrontar os impactos da chamada \"revolução digital\" sobre o design de mobiliário no Brasil, em comparação com a produção e design tradicionais. Pretende-se verificar como estas tecnologias podem auxiliar no desenvolvimento de produtos mais adequados no que diz respeito à sua utilização e à sua significação, ao mesmo tempo em que se procura reconhecer se nossa cultura material está preparada para estas mudanças. Para tanto, optou-se realizar entrevistas com designers de gerações diferentes. O primeiro com raízes modernistas e carreira estabelecida no pós-modernismo e o segundo com raízes contemporâneas e atuante no campo do Open Design e fabricação digital. Verificou-se a necessidade de um trabalho sinérgico entre o artesanal e o digital para a criação de produtos diferenciados e adequados à sua contemporaneidade. / The purpose of this research is to confront the impacts of the so-called \"digital revolution\" on furniture design in Brazil, comparing it with the production and traditional design. The aim is verify if these technologies can assist the development of products with more suitable use and meaning, at the same time seeking to recognize if our material culture is ready for these changes. To do so, we conduct interviews with different generations of designers, one with modernist roots and established career in postmodernism and the second with contemporary and active roots in the field of Open Design and digital fabrication. It was found the need for synergistic efforts between the craft and digital aspects to create differentiated products and that are fitted for contemporaneity.
192

A modular multi electrode array system for electrogenic cell characterisation and cardiotoxicity applications

Flaherty, Olivia M. January 2012 (has links)
Multi electrode array (MEA) systems have evolved from custom-made experimental tools, exploited for neural research, into commercially available systems that are used throughout non-invasive electrophysiological study. MEA systems are used in conjunction with cells and tissues from a number of differing organisms (e.g. mice, monkeys, chickens, plants). The development of MEA systems has been incremental over the past 30 years due to constantly changing specific bioscientific requirements in research. As the application of MEA systems continues to diversify contemporary commercial systems are requiring increased levels of sophistication and greater throughput capabilities.
193

Fabrication of ultrasound transducers and arrays integrated within needles for imaging guidance and diagnosis

McPhillips, Rachael January 2017 (has links)
As opposed to current Intraoperative Ultrasound (IOUS) systems and their relatively large probes and limited superficial high frequency imaging, the use of a biopsy needle with an integrated transducer that is capable of minimally invasive and high-resolution ultrasound imaging is proposed. Such a design would overcome the compromise between resolution and penetration depth which is associated with the use of a probe on the skins surface. It is proposed that during interventional procedures, a transducer array positioned at the tip of a biopsy needle could provide real-time image guidance to the clinician with regards to the needle position within the tissue, and aid in the safe navigation of needles towards a particular target such as a tumour in tissues such as the breast, brain or liver, at which point decisions surrounding diagnosis or treatment via in vivo tissue characterisation could be made. With this objective, challenges exist in the manufacturing these miniature scale devices and theirincorporation into needle packages. The reliable realisation of miniature ultrasound transducer arrays on fine-scale piezoelectric composites, and establishing interconnects to these devices which also fit into suitably sized biopsy needles are two such hurdles. In this thesis, the fabrication of miniature 15 MHz ultrasound transducers is presented. The first stage of development involved the production of single element transducers in needles ~2 mm inner diameter, using various piezoelectric materials as the active material. These devices were tested andcharacterised, and the expertise developed during their fabrication was used as the foundation upon which to design a wafer-scale fabrication process for the production of multiple 15 MHz transducer arrays. This process resulted in a 16 element 15 MHz array connected to a flexible printed circuit board and integrated into a breast biopsy needle. Characterisation tests demonstrated functionality of each of the 16 elements, both individually and combined as an array. To explore potential applications for these devices, the single element transducers were tested in fresh and Thiel embalmed cadaveric brain tissue. Plasticine targets were embedded in these brain models and the needle transducers were tested as navigational real-time imaging tools to detect these targets within the brain tissue. The results demonstrated feasibility of such devices to determine the location of the target as the needle devices were advanced or withdrawn from the tissue, showing promise for future devices enabling neurosurgical guidance of interventional tools in the brain. The application of breast imaging was also considered. Firstly, Thiel embalmed cadaveric breasts were assessed as viable breast models for ultrasound imaging. Following this, anatomical features, with diagnostic significance in relation to breast cancer i.e. axillary lymph nodes and milk ducts, were imaged using a range of ultrasound frequencies (6 – 40 MHz). This was carried out to determinepotential design parameters (i.e. operational frequency) of an interventional transducer in a biopsy needle probe which would best visualise these features and aid current breast imaging and diagnosis procedures.
194

Optimisation du calcul des dispersions angulaires tridimensionnelles.

Mezghani, Aïda 05 November 2010 (has links) (PDF)
Ce travail de recherche traite un problème qui joue un rôle très important pour le succès desprogrammes de fabrication : le tolérancement tridimensionnel, essentiel pour définir la géométried'une pièce mécanique assurant sa meilleure fonctionnalité dans un assemblage avec uneprécision optimale.Une méthode des chaînes de cotes angulaires tridimensionnelles a été développée. Cette méthodepermet d'une part l'optimisation du calcul des dispersions angulaires tridimensionnelles etd'autre part de valider la gamme de fabrication par la vérification du respect des tolérancesimposées par le bureau d'études en tenant compte des précisions des procédés utilisés.Cette étude est basée sur l'analyse de deux fonctions paramétrées qui sont étudiées pourdéterminer le défaut fabriqué : le défaut angulaire et la longueur projetée. Le défaut angulairereprésente le cumul des défauts angulaires générés par le processus de fabrication de la pièce. Lesdéfauts angulaires sont déterminés en fonction de la précision des machines outils. La longueurprojetée de la surface tolérancée est une caractéristique qui dépend uniquement de la forme de lasurface.Ensuite, à partir de ces deux fonctions paramétrées, le défaut fabriqué est déterminé puiscomparé avec la condition fonctionnelle afin de vérifier si la gamme choisie permet en fin duprocessus de fabrication de donner une pièce conforme.
195

Allocation flexible des capacités pour la fabrication de semi-conducteurs : Modélisation et optimisation

Johnzén, Carl 06 April 2009 (has links) (PDF)
Ces travaux de recherche ont été menés au sein d'une usine de fabrication de semi-conducteurs (appelée fab). L'allocation des capacités a été modélisée à l'aide de mesures et de méthodes permettant d'optimiser la flexibilité de répartition des capacités dans les ateliers. Ces travaux permettent de gérer efficacement les qualifications des produits sur les équipements dans la fab en donnant la possibilité aux ingénieurs de rendre plus flexible le travail des opérateurs. Les opérateurs ont besoin de flexibilité pour décider de la façon dont la charge de travail devra être allouée pour utiliser la capacité des équipements de manière optimale. De plus, l'intégration de l'évolution dynamique des en-cours, l'étude de l'optimisation de plusieurs qualifications sur plusieurs outils ainsi que de nombreux tests numériques sont présentés. Pour finir, des conclusions sont tirées et des perspectives de cette étude sont présentées.
196

Recent Progress in Droplet-Based Manufacturing Research

Kim, H.-Y., Cherng, J.-P., Chun, Jung-Hoon 01 1900 (has links)
This article reports the recent progress of re-search made in the Droplet-Based Manufacturing Laboratory at MIT. The study has been focused on obtaining a fundamental understanding of microdroplet deposition and applying the technology to various practical applications. Specific scientific contributions include the development of an analytical model for droplet splashing/recoiling, an in situ droplet size control methodology, and a study of microstructure design for spray forming. The research per-formed in the lab provides both fundamental knowledge base and practical process developments for a range of manufacturing applications, including electronics packaging, spray forming and freeform fabrication. / Singapore-MIT Alliance (SMA)
197

Preliminary Characterisation of Low-Temperature Bonded Copper Interconnects for 3-D Integrated Circuits

Leong, Hoi Liong, Gan, C.L., Pey, Kin Leong, Tsang, Chi-fo, Thompson, Carl V., Hongyu, Li 01 1900 (has links)
Three dimensional (3-D) integrated circuits can be fabricated by bonding previously processed device layers using metal-metal bonds that also serve as layer-to-layer interconnects. Bonded copper interconnects test structures were created by thermocompression bonding and the bond toughness was measured using the four-point test. The effects of bonding temperature, physical bonding and failure mechanisms were investigated. The surface effects on copper surface due to pre-bond clean (with glacial acetic acid) were also looked into. A maximum average bond toughness of approximately 35 J/m² was obtained bonding temperature 300 C. / Singapore-MIT Alliance (SMA)
198

Den fabricerande människan : Om bedrägeri som vardaglig interaktionsform / The Fabricating Human Being : Deception as an Everyday Form of Interaction

Arvidson, Markus January 2007 (has links)
The present dissertation takes the multi-faceted phenomenon of deception as its point of departure. The aim is to make a case for deception as a social phenomenon, and to frame theoretically and define the skills and abilities that make deception possible. A theoretical model based on a number of ideal types is constructed. The purpose of the model is to differentiate particular aspects of deception, and the model is illustrated with examples of actions of more or less well-known impostors. The examples were collected from a variety of sources, such as autobiographies and television programs. As a first step, the legal definition of deception, i.e. fraud, and statistics on crimes of deception in Sweden are presented. Different theoretical approaches are also discussed; deception as a personality trait, and deception as communication and interaction. In order to illuminate the social dimensions, it is emphasized that deception constitutes a particular type of relationship between deceiver and deceivee. This particular form of interaction exploits elementary forms, and it is also asymmetrical in terms of the intentions of the parties involved. The concept of social competence is used to describe the skills and abilities required for successful acts of deception. It is argued that the social competence of deceivers consists of three types: strategic, normative, and dramaturgic competencies. The strategic competency involves being goal-rational and strategic, for example, the ability to predict the actions of the potential addressee. In the normative competency, norms and reference to norms are used strategically. The dramaturgic competency represents an operationalization and enactment of the two other competencies, and resembles the preparation and performance of an actor. The different contexts in which deception can occur are also discussed. A preliminary typology is presented, with the aim of demonstrating the difficulties in drawing clear lines between various types of deception. The extended approach to deception also means that it can be viewed as a part of everyday social interaction. Finally, some thoughts on deception in the light of societal changes are presented. It is argued that the increasing demands on people to promote themselves in various ways in today’s society can be perceived as an invitation to deception and fabrication. These demands can generate feelings of inferiority and a fear of eventually being unmasked as an impostor, or a phony.
199

A Novel Buried-Emitter Photovoltaic Cell for High Efficiency Energy Conversion

Samadzadeh Tarighat, Roohollah January 2013 (has links)
To address the commonly poor short wavelength response of the conventional solar cell structure which consists of a highly doped thin emitter layer on top of a thicker and less doped base, the novel concept of the Buried-Windowed-Emitter is introduced. This new solar cell structure makes use of a high quality semiconductor layer on top of the traditionally made highly doped emitter and greatly enhances the spectral response of the solar cell by giving the superficially generated carriers a higher chance of collection at the junction. In the proposed BWE structure the emitter is windowed in order to electrically connect the top layer to the base for current collection. The efficacy of the proposed novel device is proven by computer aided device simulations using the available device simulation tools such as MEDICI. The results of simulation show that the proposed novel Buried-Windowed-Emitter solar cell will not only improve the short wavelength spectral response of the overall cell as expected, but also will boost the spectral efficiency for all the wavelengths. Another exciting conclusion from the results of the computer simulation of the BWE solar cell is that the minority carrier lifetime in the top layer does not need to be very high for a superb performance and values as low as 1µs can still boost the short circuit current of the cell to values close to the theoretical limit of the photo-current collectable by a silicon solar cell. This is indeed a good news for manufacturability of this device as it should be practically feasible to achieve epitaxial films with minority carrier lifetime in this range. In order to increase the understanding about the rather complex structure of the proposed Buried-Windowed-Emitter solar cell, an analytical circuit level model, similar to the case of the standard solar cell, is developed for the proposed device. The developed analytical model helps to understand the importance of the main design parameters such as the dimensions of the pattern of the windowed emitter. On the path to fabricate the proposed BWE solar cell, great deal of work is done on the development of a low temperature (<300°C) epitaxial silicon technology using the benefits of Plasma Enhanced Chemical Vapor Deposition (PECVD). Highly doped epitaxial silicon layers of up to around 1µm thickness are achieved with sheet resistivity as low as 7Ω/sq which is much lower than what is reposted in the literature in similar deposition conditions. Intrinsic, phosphorous doped n-type and boron doped p-type epitaxial films have been developed on silicon substrates. Measurement of reflection spectra of the deposited epitaxial films is proposed as a fast, non destructive and process-integrate-able method to assess the crystalline quality of the epitaxial films. Effects of higher temperature post deposition annealing have been studied on the develop epitaxial films A full technology is developed for the fabrication of the proposed novel solar cells. Photo-masks are designed to create 10 different architectures for the design of the windowed emitter in the BWE cell. All the steps taken in the successful fabrication of the novel BWE cells are presented in detail and the relevant findings are discussed and proposed as future research topics. Three kinds of cells are fabricated using the developed technology to separately study the effects of partial coverage of the windowed emitter, the optical performance of the developed epitaxial silicon films and the performance and manufacturability of the novel BWE solar cell The results show that the concept of windowed-emitter by itself (even without the top layer) is capable of enhancing the performance of the solar cell when compared to a standard design. It also promises high conversion efficiency for the BWE solar cell in case a high quality top layer can be deposited on top of the windowed emitter. The results further reveal the lower than expected quality of the low temperature epitaxial films despite the indication of their full crystallinity through other analyses. Use of the epitaxial films as the emitter of the solar cell is proposed as a direct and effective method of studying the photovoltaic performance of the low temperature epitaxial films. Further development of the epitaxial technology will lead to feasibility of a BWE solar cell with very high photovoltaic performance.
200

Development of a Novel Porogen Insertion System Used in Solid Freeform Fabrication of Porous Biodegradable Scaffolds with Heterogeneous Internal Architectures

Sharif, Hajar January 2010 (has links)
This thesis is concerned with the design of a novel system for inserting porogen particles within internal structure of the bone scaffold. The proposed system would be integrated with a 3D printing machine to create macro-pores based on the conventional porogen leaching method. The system is capable of inserting porogens on pre-designed locations within the scaffold structure to realize the generation of macro-porosity within scaffolds. Several alternatives for such a porogen insertion mechanism are proposed based on employing a mechanical actuator for opening and closing the path of porogen particles from a porogen reservoir to the build chamber. Another possible design that offers significant advantages over its actuator-based alternatives is a pneumatic-based mechanism that picks up porogens from a porogen reservoir and places them at pre-designed locations. Among all the presented alternatives, the pneumatic-based system is selected by utilizing the value matrix method, and detail design of the different parts of this system is presented. The required pilot test setups for performing the feasibility study of the proposed method have been designed and successfully developed, and the practicality of the designed porogen insertion mechanism is proven through experiment.

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