Dissertations / Theses: 'Additive technique'

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Ristovski, Nikola. "Melt electrospinning as an additive manufacturing technique." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/118057/1/Nikola_Ristovski_Thesis.pdf.

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This thesis was a study into the effect of charge buildup and subsequent modifications on a direct writing melt electrospinning device. It examined the effect of distributing the application of charge in a melt electrospinning system and studying the effect this had on order in scaffolds produced. The distribution of charge led to an increase in deposition accuracy in layers 10 times higher than previously achievable.

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Gullapalli, Vikranth. "Study of Metal Whiskers Growth and Mitigation Technique Using Additive Manufacturing." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804972/.

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For years, the alloy of choice for electroplating electronic components has been tin-lead (Sn-Pb) alloy. However, the legislation established in Europe on July 1, 2006, required significant lead (Pb) content reductions from electronic hardware due to its toxic nature. A popular alternative for coating electronic components is pure tin (Sn). However, pure tin has the tendency to spontaneously grow electrically conductive Sn whisker during storage. Sn whisker is usually a pure single crystal tin with filament or hair-like structures grown directly from the electroplated surfaces. Sn whisker is highly conductive, and can cause short circuits in electronic components, which is a very significant reliability problem. The damages caused by Sn whisker growth are reported in very critical applications such as aircraft, spacecraft, satellites, and military weapons systems. They are also naturally very strong and are believed to grow from compressive stresses developed in the Sn coating during deposition or over time. The new directive, even though environmentally friendly, has placed all lead-free electronic devices at risk because of whisker growth in pure tin. Additionally, interest has occurred about studying the nature of other metal whiskers such as zinc (Zn) whiskers and comparing their behavior to that of Sn whiskers. Zn whiskers can be found in flooring of data centers which can get inside electronic systems during equipment reorganization and movement and can also cause systems failure.Even though the topic of metal whiskers as reliability failure has been around for several decades to date, there is no successful method that can eliminate their growth. This thesis will give further insights towards the nature and behavior of Sn and Zn whiskers growth, and recommend a novel manufacturing technique that has potential to mitigate metal whiskers growth and extend life of many electronic devices.

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Denis, Corentin. "Variations dimensionnelles d'une céramique dentaire alumineuse mise en forme par technique additive." Electronic Thesis or Diss., Université de Lille (2022-....), 2024. http://www.theses.fr/2024ULILS050.

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Une méthode de mise en forme additive de céramique dentaire a été développée au sein du Ceramaths de l’Université de polytechnique Hauts-de-France. Les travaux précédents ont montré qu’à partir de suspensions de céramique alumineuse à 80% de taux de matière sèche en poids, la photopolymérisation en cuve permet la mise en forme de céramiques d’infrastructure avec des propriétés mécaniques en adéquation avec les exigences dentaires en vigueur. En effet, les armatures en céramique doivent répondre à un cahier des charges exigeant concernant leur précision d’adaptation à la préparation dentaire et leurs propriétés mécaniques. Les pièces en céramiques mises en forme par techniques additives présentent un retrait anisotrope (diminution différente selon les trois dimensions du volume d’une pièce frittée par rapport à son volume initial) à la suite du traitement thermique de déliantage et de densification. La pièce prothétique doit impérativement être surdimensionnée pour assurer une adaptation de la restauration à la préparation dentaire après traitement thermique et limiter le risque l’échec de la restauration. Pour ce faire, l’étude des taux de retrait et les déformations de pièces à la géométrie variable et de plus en plus complexe a été réalisée. Ces différentes morphologies de pièces ont été numérisées à l’aide de la microtomographie puis les fichiers ont été analysés à l’aide d’un logiciel d’inspection et de contrôle. Par l’étude de morphologie simple parallélépipédique, la variation de la largeur de couches et la variation du nombre de couches ont montré des taux de retraits anisotropes, équivalents dans le sens perpendiculaire de mise en forme mais supérieurs dans le sens de la mise en forme. Les variations de forme des modèles simplifiés n'influencent pas les différents taux de retrait. La viscosité maximale acceptable dépend de la surface de la couche mais aussi de la distance entre deux surfaces qui impactent les déformations dues à la mise en forme et au traitement thermique. L’étude dimensionnelle des pièces cylindriques creuses a montré que plus la surface de couche augmente, plus le risque de défaut augmente ; de même que l’orientation de la pièce influence les déformations lors du traitement thermique. L’orientation optimale doit donc être un compromis entre temps de fabrication, limitation des déformations par la plus petite surface de couche possible et garantie des propriétés mécaniques optimales. Suite à l’étude des déformations d’une armature de couronne clinique, les résultats en terme fidélité de mise en forme ont montré que la fabrication combinant l’imprimante CryoPrinter® (CryoCeram®), la résine CryoCeram® et l’alumine CT 1200SG®, (Almatis®) est reproductible quelle que soit l’orientation de mise en forme. Les valeurs de justesse des restaurations imprimées se trouvent sous le seuil de 120 μm hormis pour la zone marginale lorsque l’orientation mésio-distale est choisie. L’orientation occluso-cervicale permet d’obtenir les restaurations les plus conformes au modèle numérique au niveau marginal. Enfin, les valeurs de hiatus occlusaux sont significativement plus faibles pour l’orientation occluso-cervicale par rapport à celle vestibulo-palatine, cette dernière étant la seule à présenter également une valeur moyenne des hiatus marginaux sous les 120 μm. Ainsi, pour la mise en forme avec le procédé développé par CryoCeram®, l’orientation occluso-cervicale semble à privilégier pour la réalisation d’infrastructures de couronnes cliniquement acceptables. Enfin, une évaluation de la non-cytotoxicité des pièces mises en forme à l’aide de ce nouveau procédé a été réalisée afin d’envisager une utilisation clinique
An additive manufacturing method for dental ceramics was developed at Ceramaths, part of the Polytechnic University of Hauts-de-France. Previous work has shown that using alumina ceramic suspensions with 80% solid content by weight, vat photopolymerization enables the shaping of infrastructure ceramics with mechanical properties that meet current dental requirements. Indeed, ceramic frameworks must adhere to strict specifications regarding their fit precision to the dental preparation and their mechanical properties.Ceramic parts fabricated using additive techniques exhibit anisotropic shrinkage (different shrinkage rates along the three dimensions of a sintered part compared to its initial volume) following thermal debinding and densification treatment. The prosthetic part must be oversized to ensure the restoration adapts to the dental preparation after thermal treatment and to minimize the risk of restoration failure. A study on shrinkage rates and deformations of parts with increasingly complex geometries was conducted. These different part morphologies were digitized using microtomography, and the files were analyzed using inspection and control software.In the study of simple parallelepiped morphologies, variations in layer width and the number of layers showed anisotropic shrinkage rates, equivalent in the direction perpendicular to the forming process but higher in the forming direction. Shape variations of the simplified models do not influence the different shrinkage rates. The maximum acceptable viscosity depends on the layer surface area as well as the distance between two surfaces, which impacts the deformations due to the forming process and thermal treatment.The dimensional study of hollow cylindrical parts showed that the larger the layer surface area, the greater the risk of defects, and the orientation of the part also influences deformations during thermal treatment. The optimal orientation must therefore be a compromise between manufacturing time, limiting deformations with the smallest possible layer surface area, and ensuring optimal mechanical properties.Following the study of deformations in a clinical crown framework, the results in terms of forming accuracy showed that the manufacturing process combining the CryoPrinter® (Cryoceram®) printer, CryoCeram® resin, and CT 1200SG® alumina (Almatis®) is reproducible regardless of the forming orientation. The accuracy values of the printed restorations were below the 120 μm threshold except for the marginal zone when the mesio-distal orientation was chosen. The occluso-cervical orientation produced the most accurate restorations relative to the digital model at the marginal level. Lastly, the occlusal gap values were significantly lower for the occluso-cervical orientation compared to the vestibulo-palatal orientation, with the latter being the only one also presenting a mean marginal gap value below 120 μm. Thus, for shaping using the process developed by CryoCeram®, the occluso-cervical orientation seems preferable for producing clinically acceptable crown frameworks.Finally, an evaluation of the non-cytotoxicity of the parts formed using this new process was conducted to consider potential clinical use

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Hasting, William. "Geometric Effects of Free-Floating Technique on Alloy 718 Parts Produced via Laser-Powder Bed Fusion." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613751580039925.

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Falck, Rielson [Verfasser]. "A new additive manufacturing technique for layered metal-composite hybrid structures / Rielson Miler Moreira Falck." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2020. http://d-nb.info/1224270835/34.

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Yosofi, Mazyar. "Méthodologie de caractérisation prédictive des procédés de fabrication additive avec une approche technique, économique et environnementale." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0034/document.

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L'Organisation des Nations Unies vise à moderniser les industries afin de les rendre durables et plus respectueuse de l'environnement d'ici 2030. Afin de répondre à ces attentes, il faut mettre en place des voies d'améliorations des procédés de fabrication d'un point de vue environnemental. Cette démarche nécessite une connaissance fine des flux entrants et sortants lors de la fabrication d'un produit. Néanmoins, ce n'est pas le cas pour les procédés de fabrication additives ou les impacts environnementaux générés lors de la fabrication d'un produit sont encore méconnus. Par conséquent, il est primordial de bien "compter" les différentes sources de consommations et de rejets. Pour cela, une évaluation quantitative des flux intervenants pendant la fabrication de pièces est nécessaire pour améliorer la connaissance de la performance environnementale d'un procédé. Les travaux de cette thèse portent sur la proposition d'une méthodologie d'évaluation multicritère pour les procédés de fabrication additive afin de pouvoir prédire, dès l'étape de conception d'un produit, des informations sur les aspects techniques, économiques et environnementaux du couple pièce/procédé. Afin de proposer aux concepteurs la possibilité d'évaluer un produit dès son étape de conception, des modèles de consommation fins traduisant le comportement du procédé ont été mis en place. La méthodologie développée s’intéresse à l'ensemble des sources de consommation et de rejets ainsi qu'à l'ensemble des étapes nécessaires à la fabrication d'une pièce mécanique.Ce manuscrit est divisé en six chapitres qui permettent de présenter le contexte général de l'étude, l'état de l'art, la méthodologie d'évaluation multicritère, l'application sur les procédés de fabrication additive et l'exploitation sur un cas industriel. Le dernier chapitre se consacre à la conclusion sur les apports de ces travaux et propose des perspectives de recherche
The United Nations aims to modernize industries in order to make them sustainable and more environmentally friendly by 2030. In order to meet these expectation, it is necessary to put in place ways of improving production processes from an environmental point of view. This approach requires a detailed knowledge of the incoming and outgoing flows during the manufacturing of a product. However, this is not the case for additive manufacturing processes where the environmental impacts generated during this stage are still unknown. For that, a quantitative evaluation of the flows involved during the manufaturing of parts is necessary in order to improve the knowledge of the environmental performance of a process. The work of this thesis focuses on the development of methodology for additive manufacturing processes in order to predict information on the technical, economic, and environmental aspects of a product during the design stage of a part. The methodology developped is increasingly interested in all the sources of consumption as well as all the stages necessary for the manufacturing of a mechanical part.This manuscript is divided into six chapters that can present the general context of the study, the state of the art, the methodology developped, a application of the methodology to additive manufacturing processes and the computer tool developed during this thesis. The last chapter is devoted to the conclusion on the contributions of this work and provides research perspectives

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Asadollahiyazdi, Elnaz. "Integrated Design of Additive Manufacturing Based on Design for Manufacturing and Skin-skeleton Models." Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0026.

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Aujourd'hui, la fabrication additive (FA) fait évoluer le monde de la fabrication grâce à ses capacités de production de formes complexes couche par couche. L'approche de conception pour la fabrication (DFM) aide à considérer les contraintes de FA et à maîtriser les caractéristiques du produit dans la gestion de son cycle de vie. Plusieurs études sont consacrées à l'approche de conception intégrée pour la FA, mais aucune approche ne prend en compte toutes les étapes du cycle de vie du produit dans le niveau d'optimisation de sa conception et de sa fabrication. Ainsi, cette thèse fournit une approche DFM pour la FA afin d'étudier simultanément différents attributs, contraintes et critères de conception et de fabrication dès la définition du produit. L'approche Peau-Squelette modélise la première définition du produit. Il contient une analyse fonctionnelle, un modèle d'usage et un modèle de fabrication. Dans ce travail, un nouveau moteur de résolution, qui agit à l’interface du modèle de produit et du modèle de fabrication, est proposé grâce à l'analyse des technologies FA et de leurs paramètres et critères. Ce moteur repose sur un problème d'optimisation bi-objectif pour minimiser le temps de production et la masse du matériau en proposant les solutions optimales pour les propriétés mécaniques et la rugosité du produit. Cette méthodologie permet de définir le modèle de produit. L'approche est mise en œuvre à travers une première technologie de dépôt par fil fondu (FDM) pour la production de deux études de cas
Nowadays, Additive Manufacturing (AM) evolves the manufacturing world by its capabilities for production of the complex shapes layer by layer. Design For Manufacturing (DFM) approach helps to overcome the AM constraints and mastering product features in product lifecycle. Several studies are devoted to integrated design approach for AM, but there is no approach that considers all product life cycle steps in optimization level for product and manufacturing process. So, this thesis provides a DFM approach for AM to investigate simultaneously different attributes, constraints, and criteria of design and manufacturing in product definition. Skin-Skeleton approach models the first definition of product and AM. It contains functional analysis, usage model, and manufacturing model. In this work, a novel interface processing engine as an interface between product and manufacturing model is developed through analysis of AM technologies and their parameters and criteria. This engine relies on a bi-objective optimization problem to minimize production time and material mass under limitation of mechanical properties and roughness of the product to obtain the optimal manufacturing parameters. This methodology permits to define the product model. The approach is implemented into Fused Deposition Modeling to verify the methodology through two case studies

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Zaman, Uzair khaleeq uz. "Intégration Produit-Process appliquée à la sélection de procédés de Fabrication Additive." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0006/document.

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Cette recherche vise à proposer une approche intégrée permettant la prise en compte simultanée des paramètres Produits / process dans le cadre d’une fabrication par ajout de matière. Le développement produit est en profonde mutation, prenant en compte les contraintes de personnalisation, de temps de mise sur le marché de plus en plus court, la volonté d’une approche eco-responsable etc. Ce changement de paradigme conduit à s’intéresser au choix du couple matériau /process dès la phase de conception afin de prendre en compte les contraintes liées au procédé identifié. Cette approche multi critère s’intéresse à la fois au couple matériau procédé mais prend en compte les aspect fonctionnels de la pièce. Ainsi ce travail de thèse présente une méthodologie de décision générique, basée sur des outils de prise de décision multicritères, qui peut non seulement proposer une solution satisfaisant les contraintes liées aux matériaux, processus et processus par addition de matière, mais propose également de servir de guide aux concepteurs permettant un choix raisonné basé sur des combinaisons matériau-machine orientées conception et obtenu à partir d’une base de données de 38 fournisseurs internationaux de machine de fabrication par ajout de matière
The doctoral research focuses to build an integrated approach that can simultaneously handle the product and process parameters related to additive manufacturing (AM). Since, market dynamics of today are constantly evolving, drivers such as mass customization strategies, shorter product development cycles, a large pool of materials to choose from, abundant manufacturing processes, etc., have made it essential to choose the right compromise of materials, manufacturing processes and associated machines in early stages of design considering the Design for AM guidelines. As several criteria, material attributes and process functionality requirements are involved for decision making in the industries, the thesis introduces a generic decision methodology, based on multi-criteria decision-making tools, that can not only provide a set of compromised AM materials, processes and machines but will also act as a guideline for designers to achieve a strong foothold in the AM industry by providing practical solutions containing design oriented and feasible material-machine combinations from a database of 38 renowned AM vendors in the world today

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Johansson, Ingrid. "Post-processing for roughness reduction of additive manufactured polyamide 12 using a fully automated chemical vapor technique - The effect on micro and macrolevel." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279316.

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Additive manufacturing has increased in popularity in recent years partly due to the possibilities of producing complex geometries in a rapid manner. Selective laser sintering (SLS) is a type of additive manufacturing technique that utilizes polymer powder and a layer-by-layer technique to build up the desired geometry. The main drawbacks with this technique are related to the reproducibility, mechanical performance and the poor surface finish of printed parts. Surface roughness increase the risk of bacterial adhesion and biofilm formation, which is unbeneficial for parts to be used in the healthcare industry. This thesis investigated the possibility in reducing the surface roughness of SLS printed polyamide 12 with the fully automated post-processing technology PostPro3D. The postprocessing relies on chemical post-processing for smoothening of the parts’ surface. PostPro3D utilizes vaporized solvent which condenses on the printed parts causing the surface to reflow. By this roughness, in terms of unmolten particles, is dissolved and surface pores are sealed. The influence of alternating post-processing parameters; pressure, temperature, time and solvent volume was evaluated with a Design of Experiments (DoE). The roughness reduction was quantified with monitoring the arithmetic mean average roughness (Ra), the ten-point height roughness (Rz) and the average waviness (Wa) using a stylus profilometer and confocal laser scanning microscope (CLSM). The effect of post-processing on mechanical properties was evaluated with tensile testing and the effect on microstructure by scanning electron microscopy (SEM). A comparison was made between post-processed samples and a non-postprocessed reference, as well as between samples post-processed with different degree of aggressivity, with regards to the roughness values, mechanical properties and the microstructure. Results indicated that solvent volume and time had the largest effect in reducing the roughness parameters Ra and Rz, while time had the largest influence in increasing the elongation at break, tensile strength at break and toughness. The post-processing’s effect on waviness and Young’s modulus was less evident. SEM established that complete dissolution of powder particles was not achieved for the tested parameter ranges, but a clear improvement of the surface was observed for all different post-processing conditions, as compared to a non-post-processed specimen. The reduction in roughness by increased solvent volume and time was thought to be due to increased condensation of solvent droplets on the SLS-parts. The increase in mechanical properties was likely related to elimination of crack initiation points at the surface. In general, the mechanical properties experienced a wide spread in the results, this was concluded to be related to differences in intrinsic properties of the printed parts, and highlighted the problems with reproducibility related to the SLS. An optimal roughness of Ra less than 1 µm was not obtained for the tested post-processing conditions, and further parameter optimization is required.
Möjligheten att tillverka komplexa geometrier på ett snabbt sätt, har fått additiv tillverkning att öka i popularitet. Selective laser sintering (SLS) är en typ av additiv tillverkning där polymer pulver sintras samman succesivt lager för lager. Dessa lager bygger tillsammans upp den önskade geometrin. De största nackdelarna med SLS är att de tillverkade delarna har bristande mekaniska egenskaper, har brister i reproducerbarheten samt att ytan har en dålig kvalitet, den är ojämn. Ytojämnheten ökar risken för att bakterier fastnar och ett en biofilm bildas. Då produkten ska användas inom sjukvården, är det viktigt att biofilm bildning undviks. Den här uppsatsen har undersökt möjligheterna att reducera ytojämnheten av SLS-printad polyamid 12 med hjälp av kemisk efterbehandling i PostPro3D. Denna maskin är helt automatisk och åstadkommer ytbehandling genom att förånga lösningsmedel som sedan kondenserar på det SLS-printade materialet. Ytan på materialet löses upp vilket minskar ytojämnheter i form av pulver partiklar samt sluter porer på ytan. Genom att ändra på parametrarna för efterbehandlingen kan graden av aggressivitet påverkas, detta gäller tryck, temperatur, tid och lösningsmedels volym. De optimala parametrarna för att åstadkomma en jämn yta utvärderades med en Design of Experiments (DoE). Reducering av ytojämnhet mättes med hjälp av aritmetisk genomsnittlig ojämnhet (Ra), tio-punkts höjd ojämnhet (Rz) och medel-vågighet (Wa), med nålprofilometer och konfokal mikroskop. Efterbehandlingens påverkan på de mekaniska egenskaperna utvärderades i ett dragprov, medan mikrostrukturen undersöktes med svepelektronmikroskop (SEM). Ytjämnheten, de mekaniska egenskaperna och mikrostrukturen jämfördes mellan icke behandlade prover och ytbehandlade prover, med varierad grad av aggressivitet. Resultaten indikerade att tid och volym hade störst effekt på Ra och Rz, medan tid hade störst positiv inverkan på töjning, styrka och seghet. Effekten på styvheten (E-modulen) och vågigheten (Wa) var mindre uppenbar, och någon tydlig påverkan kunde inte observeras. SEM-analys visade att fullständig upplösning av partiklar på ytan inte sker för de testade behandlingarna, men en tydlig förbättring kunde ses vid jämförelse av ett obehandlat prov och ett behandlat prov. Den ökade ytjämnheten för längre tid och högre volym tros bero på en ökad kondensering av lösningsmedel på ytan under efterbehandlingen. Ökningen i mekaniska egenskaperna är troligtvis relaterade till eliminering av kritiska defekter på ytan. Generellt visade de mekaniska egenskaper en stor spridning i resultaten, detta tros bero på inneboende egenskaper i provstavarna. Denna slutsats understryker den bristande reproducerbarheten för SLS-printning. En optimal ytjämnhet antas vara ett Ra värde under 1 µm, denna ytjämnhet har inte uppnåtts med de testade efterbehandlingsparameter värdena, därför krävs ytterligare parameter optimering för att nå optimal efterbehandling.

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Cormier, Yannick. "Performance, Manufacturability and Mechanical Properties of Near-Net Shaped Pyramidal Fin Arrays for Compact Heat Exchangers Produced Using Cold Spray as an Additive Manufacturing Technique." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34981.

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Significant efforts have been made in the last decades to decrease the world’s dependency to fossil fuels. One of the fronts which has shown major improvement is gas turbine efficiency. To this end, components such as recuperators have been developed to recover heat that is usually trapped and wasted in the exhaust gases of combustion processes. Brayton Energy Canada has recently developed a promising compact heat exchanger that could be used as a recuperator in gas turbines. Nevertheless, this novel type of wire mesh heat exchanger still has room for improvement, especially regarding the way that its fin arrays are manufactured due to the fact that the technique presently used is time consuming and consequently costly. The present research aims to manufacture near-net shaped pin fin arrays using cold gas dynamic spray as an additive manufacturing technique by selectively covering the substrate by the means of a mask. Moreover, this research work studies the feasibility of using CGDS as an additive manufacturing technique to produce pin fin arrays, the thermal and hydrodynamic performances of this new type of pin fin created, the effect of geometric parameters such as fin density and height on the performances, the viability of the sprayed pin fins in a real environment by means of finding mechanical properties such as adhesion strength, the possibility of producing a streamwise material anisotropic fin arrays, and finally the different adhesion mechanisms by means of numerical modeling of the relevant impact physics.

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Barbosa, Talita Villa. "Fabricação de scaffolds de polímero reforçado para aplicação na bioengenharia tecidual." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-14022019-084241/.

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No presente trabalho, suportes tridimensionais (scaffolds) de polímero reforçado foram gerados por meio da técnica aditiva por extrusão utilizando duas estratégias de deposição e, posteriormente, foram avaliados morfologicamente, mecanicamente e por meio de ensaios in vitro. Como matriz polimérica do compósito utilizou-se a poli(ε-caprolactona) e como reforço, o Biovidro® 45S5. De forma a melhorar a interação interfacial entre a matriz polimérica e a cerâmica, avaliou-se a incorporação de nanofibra de celulose ao biovidro. Os scaffolds foram fabricados seguindo dois métodos diferentes. O primeiro consistiu no pré-processamento do material em extrusora monorrosca, seguida de extrusão direta na impressora 3D experimental Fab@CTI. O segundo consistiu em um único processo de extrusão diretamente no cabeçote de extrusão. A caracterização química do biovidro por espectroscopia de fluorescência de raios-x mostrou eficiência na preparação da biocerâmica e a caracterização da distribuição do tamanho de partícula por espalhamento de luz dinâmica mostrou a obtenção de partículas submicrométricas. Os scaffolds foram caracterizados morfologicamente pela técnica de microscopia eletrônica de varredura, e, pôde-se notar a eficiência na fabricação de geometrias com arquitetura 00/900 e tamanho de poros adequado para a aplicação na engenharia tecidual. Os ensaios mecânicos de compressão evidenciaram melhoras na rigidez com o aumento do teor de biovidro, no caso dos materiais pré-processados por extrusão, além da influência da nanofibra de celulose na melhoria das propriedades mecânicas. Os ensaios biológicos in vitro mostraram que os scaffolds suportam proliferação celular e que o biovidro é responsável pela maior deposição de sais de cálcio extracelular, facilitando a interação do material sintetizado com o tecido ósseo.
In the present work, scaffolds of reinforced polymer were generated by means of the extrusion additive technique using two strategies of deposition and, later, were evaluated morphologically, mechanically and by means of in vitro tests. Poly (ε-caprolactone) was used as the polymer matrix of the composite and as a booster, Bioglass® 45S5. In order to improve the interfacial interaction between the polymer matrix and the ceramic, the incorporation of cellulose nanofiber to the bioglass was evaluated. The scaffolds were manufactured following two different methods. The first consisted of the pre-processing of the extruded extruder material followed by direct extrusion into the experimental Fab@CTI 3D printer. The second consisted of a single extrusion process directly on the extrusion head. The chemical characterization of the bioglass by x-ray fluorescence spectroscopy showed efficiency in the preparation of the bioceramics and the characterization of the particle size distribution by dynamic light scattering showed the submicrometric particles. The scaffolds were characterized morphologically by the scanning electron microscopy technique, and it was noted the efficiency in the manufacture of geometries with architecture 00/900 and pore size suitable for application in tissue engineering. The mechanical compression tests showed improvements in stiffness with increasing bioglass content in the case of pre-processed materials by extrusion, as well as the influence of cellulose nanofiber in improving mechanical properties. Biological assays have shown that scaffolds support cell proliferation and that bioglass is responsible for the increased deposition of extracellular calcium salts, facilitating the interaction of the synthesized material with the bone tissue.

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Dufaud, Thomas. "Contribution to the development of Aitken Restricted Additive Schwarz preconditioning and application to linear systems arising from automatic differentiation of compressible Navier-Stokes solutions with respect to the simulation’s parameters." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10230/document.

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Un préconditionneur à deux niveaux, reposant sur la technique d’accélération d’Aitken d’une suite de q vecteurs solutions de l’interface d’un pro- cessus itératif de Schwarz Additif Restreint, est conçu. Cette nouvelle technique, dénomée ARAS(q), utilise une approximation grossière de la solution sur l’interface. Diﬀérentes méthodes sont proposées, aboutissant au développement d’une tech- nique d’approximation par Décomposition en Valeures Singulières de la suite de vecteurs. Des implémentations parallèles des méthodes d’Aitken-Schwarz sont pro- posées et l’étude conduit à l’implémentation d’un code totalement algébrique, sur un ou deux niveaux de parallélisation MPI, écrit dans l’environnement de la biblio- thèque PETSc. Cette implémentation pleinement parallèle et algébrique procure un outil flexible pour la résolution de systèmes linéaires tels que ceux issus de la dif- férentiation automatique des solutions de Navier-Stokes dépendant des paramètres de la simulation
A two level preconditioner, based on the Aitken acceleration technique of a sequence of q interface’s solution vectors of the Restricted Additive Schwarz iterative process, is designed. This new technique, called ARAS(q), uses a coarse approximation of the solution on the interface. Diﬀerent methods are discussed, leading to the development of an approximation technique by Singular Value De- composition of the sequence of vectors. Parallel implementations of Aitken-Schwarz methods are proposed, and the study leads to a fully algebraic one-level and two- level MPI implementation of ARAS(q) written into the PETSc library framework. This fully parallel and algebraic code gives an adaptive tool to solve linear systems such as those arising from automatic diﬀerentiation of compressible Navier-Stokes solution with respect to the simulation’s parameters

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Xiao, Jinhua. "Towards a STEP-compliant data model for process information management in additive manufacturing : application to fused deposition modelling." Electronic Thesis or Diss., Compiègne, 2019. http://www.theses.fr/2019COMP2483.

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Avec le développement de la fabrication additive (FA), l'intégration de la chaîne numérique et des normes d'échange de données deviennent un enjeu majeur. La chaîne numérique comporte différentes propres phases, dont notamment l’industrialisation et la fabrication. L'échange de données FA peut exploiter divers formats d'impression, tels que STL, AMF, 3MF et STEP. Par conséquent, la standardisation de la chaîne numérique et des formats de données devient un sujet de recherche majeur. Pour développer une approche permettant une meilleure intégration de la chaîne numérique, en particulier pour l’industrialisation et la fabrication une standardisation des formats de données est nécessaire pour améliorer l'interopérabilité entre les différentes applications informatiques (CAO / IPAO / FAO / MOCN). Deux types de problèmes doivent être surmontés : le premier est lié à l'intégration des processus clés, le second est lié au format de données. La contribution de la thèse s’appuie sur les normes STEP / STEP-NC pour les phases d’industrialisation et de fabrication. La première contribution propose la procédure de spécification de la chaîne numérique de FA, mobilisant des concepts, des normes, une représentation de modèle, des langages modélisation et une évaluation de modèle relatifs à cette technologie. La deuxième contribution, le modèle de données de processus FA, est proposée pour traiter les problèmes d'interopérabilité des données dans les phases d’industrialisation et de fabrication qui définissent les objets et entités de l'application, et créent des modèles de données du processus. La troisième contribution porte sur l'analyse de la conformité du modèle de données proposé, qui fournit la méthode d'analyse spécifique pour les opérations de fabrication par couche ou le trajet de la tête d’impression. Enfin, les propositions sont ensuite mises en œuvre dans une architecture globale exploitant la plateforme CatalystEX. Cette architecture assure une démonstration de l’interopérabilité du modèle de données proposé et met en œuvre une étude de cas à partir d’une pièce test NIST. Pour intégrer toutes les informations relatives à la planification et à la fabrication, un fichier physique étendu basé sur STEP / STEP-NC a été créé par STEP Partie-21 pour illustrer la planification de l'impression et les opérations spécifiques
Regarding the rapid development of additive manufacturing (AM) technology, the integration of digital thread and the standard of data exchange are becoming a huge trend. Digital thread has its own several stages, including production engineering and manufacturing operations. AM data exchange mainly focuses on various print formats, such as STL, AMF, 3MF, and STEP. Therefore, digital thread and information standard become increasing significant. In order to achieve a better integration of digital thread, data standard is needed further to enhance the interoperability among various computer-aided X systems (CAD/CAPP/CAM/CNC). Two kinds of problems must be overcome. The first problem is linked to process-related integration while the second is related to data standard. The contribution of the thesis is based on STEP/STEP-NC standards to integrated production engineering and manufacturing operations. The first contribution proposes the fundamental guideline for specifying AM digital thread, including concepts, standards, model representation, descriptive languages, and model assessment. The second contribution, AM process data model, is proposed to address the issues of data interoperability on production engineering and manufacturing operations that defines application objects and entities, and definitions process of data models. The third contribution focuses on the conformance assessment for proposed data model. It provides the specific analysis way for manufacturing layer and head path, respectively. Finally, the propositions are then implemented by a global architecture based on CatalystEX Platform. Such an architecture makes a demonstration on the interoperability of the developed data model and presents the use of a case study for NIST testing part. In order to integrate all the related information on production planning and manufacturing operations, extended STEP/STEP-NC physical file has been accomplished by STEP Part-21 to demonstrate the print planning and AM operations

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Fréchard, Victor. "Contribution à l’étude de l’utilisation de la Stratoconception® pour la conception et la fabrication de composants non-standards pour l’architecture en bois." Electronic Thesis or Diss., Université de Lorraine, 2024. http://www.theses.fr/2024LORR0006.

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L’architecture non-standard en bois explore l’étendue des possibilités techniques et esthétiques pour de nouveaux usages répondant à des exigences fonctionnelles cohérentes avec les enjeux environnementaux, sociétaux et économiques contemporains. Récemment introduite dans le secteur de la construction, mais absente des pratiques de la construction en bois, la fabrication additive, qui regroupe un ensemble de procédés, étend les limites des moyens de fabrication conventionnels par la liberté formelle accrue et la multifonctionnalisation des composants architecturaux qu’elle permet. Le procédé de Stratoconception® présente un fort potentiel d’application pour le développement d’architectures et de composants non-standards en bois, présentant une forte capacité d’adaptation aux moyens techniques et matériels de la construction en bois. Le procédé de Stratoconception®, en architecture, se limite à la réalisation de maquettes et de prototypes de petites dimensions et ne s’applique pas, jusqu’à présent, à la conception et à la fabrication de composants fonctionnels à usage structurel de petites comme de grandes dimensions. L’utilisation de ce procédé pour la réalisation de prototypes ou d’outillages pour l’industrie implique que la conception du processus de fabrication par Stratoconception® est indépendante de la conception des objets eux-mêmes, destinés à être réalisés par d’autres procédés de fabrication, alors que l’architecture non-standard privilégie un renforcement du lien entre la conception architecturale et les techniques de fabrication. Ce travail présente les résultats d’expériences de « conception-fabrication » par Stratoconception® de composants architecturaux menées, qui forment, avec l’étude bibliographique menée, une base de connaissance, orientée vers des enjeux identifiés, des mécanismes, des problématiques et des limites de l’utilisation de la Stratoconception® dans les pratiques de l’architecture et la construction en bois. Ces expériences ont mis en évidence le manque de flexibilité et d’outils d’évaluation du processus de production de composants architecturaux par Stratoconception® ainsi que l’interdépendance entre la conception et la fabrication. Nous avons également identifier des opportunités d’applications du procédé pour la conception et la production de composants architecturaux non-standards, particulièrement les nœuds d’assemblages en bois de treillis tridimensionnels et les parois. Afin d’obtenir un processus de conception applicable dans les pratiques de l’architecture et de la construction en bois, nous introduisons une méthode de conception pour la fabrication additive par Stratoconception® intégrant les contraintes et les opportunités du procédé dès l’étape de conception de la géométrie de la pièce en favorisant une évolution itérative de cette conception, orientée par les résultats de moteurs d’évaluation accompagnant le concepteur vers des prises de décision cohérentes avec des critères définis. La méthode proposée, implémentée dans des outils d’aide à la conception, permet la mise en place d’une continuité informationnelle numérique liant une conception paramétrique à une fabrication numérique en orientant le concepteur vers des solutions respectant des critères de faisabilité et de rationalisation de la production dès la phase amont de la conception de la géométrie du composant architectural
Non-standard timber architecture explores the scope of technical and aesthetic opportunities for new uses that correspond to functional requirements consistent with contemporary environmental, social and economic issues. Recently adopted by the construction industry, but absent from the timber construction practices, additive manufacturing, which brings a range of processes, extends the existing limitations of the subtractive and formatting manufacturing methods in the ability to produce complex shapes and multi-functionalized architectural components. The Stratoconception® process shares the technical and material means of the timber construction industry and presents a great potential to be implemented in the common practices to develop non-standard timber architecture and components. In architecture, the Stratoconception® process is limited to the production of small-scale models and prototypes and has not yet been applied to the design and the manufacturing of functional components, used for structural purposes, in either small or large dimensions. The use of this process to produce prototypes or tooling for the industry implies that the Stratoconception® manufacturing process design is independent of the design of the objects themselves, which are intended to be produced by other manufacturing processes, whereas non-standard architecture tends to strengthen the link between the architectural design and the manufacturing techniques. This work presents the results of Stratoconception® “design to manufacturing” experiences carried out on architectural components. These experiences, combined with the bibliographical study, constitute a knowledge base, oriented towards the issues, the mechanisms, the problems and the limits identified of the use of Stratoconception® in architecture and timber construction practices. These experiences have highlighted the lack of flexibility and development of evaluation tools of the Stratoconception® production process of architectural components, as well as the interdependence between design and manufacturing. We have also identified the opportunities to apply the process to the design and the production of non-standard architectural components, especially the timber assembly of the gridshell or lattice structures and the walls. To achieve a design process that can be applied in the timber architecture and construction practices, we introduce a design for additive manufacturing by Stratoconception® method, that integrates the constraints and the opportunities of the process right from the part geometry design stage and fosters the iterative evolution of the design, guided by the results of evaluation engines that support the designer in his decision-making. The proposed method, implemented in design support tools, creates a digital information continuum that connects parametric design to digital manufacturing, guiding the designer towards solutions that meet feasibility and production rationalization criteria right from the early design phase of the architectural component’s geometry

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Jeunehomme, Eric J. S. "Design of low cost biomimetic flexible robots using additive manufacturing techniques." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122313.

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Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 109-112).
In this thesis, I designed and fabricated robots leveraging additive manufacturing. This had two overarching purpose. One to make a testing apparatus that would allow the measurements of the influence of a flexible flapping foil onto a subsequent, in-line, foil with the optic of researching optimized propulsion solutions for under water vehicles. The second was to show that filament deposition modeling has advanced enough to produce bio-mimetic flexible robots of academic relevance that would allow, for a low price, the making of a number of experimental setup with specific measurements in mind. In order to reach those goals, two versions of a bio-mimetic archer fish of the genus Toxotes were modeled using various software. The models were modified to accept actuator assemblies and interface to the electronics and built using a modified hobby grade 3D printer.
by Eric J.S. Jeunehomme.
S.M. in Naval Architecture and Marine Engineering
S.M.
S.M.inNavalArchitectureandMarineEngineering Massachusetts Institute of Technology, Department of Mechanical Engineering
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering

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MASSACCESI, ANDREA. "Dielectric Transmitarray Antennas: from Design to Realization using Additive Manufacturing Techniques." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2755755.

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Maku, Lebogang Jennifer. "Identification and characterization of additives in colourants by advanced analytical techniques." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/98084.

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Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Various types of anionic, non-ionic, cationic and zwitterionic additives are used in the coatings industry for the production of paints and colourants. These additives are added to enhance properties such as stabilization of pigment dispersions, wetting of pigments and improvement of open time and freeze/thaw stability. Very often the exact chemistry of these commercial additives is unknown and this is a limitation for new product developments. The identification and characterization of these multi-component polymeric materials continues to be a challenging task. This research presents the use of various advanced analytical techniques to identify and characterize commercial additives that are used in a multi-component colourant formulation. The focus of the present study is on additives that are based on poly(ethylene glycol) (PEG). The molar mass distribution of PEG-based additives was determined with liquid chromatography coupled to mass spectrometry (LC-MS) using solvent gradient elution and at critical conditions of adsorption (LCCC) of PEG. Using the combination of LC-MS, proton nuclear magnetic resonance spectroscopy (1H NMR), pyrolysis gas chromatography (py-GC-MS) and Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), different additives were identified in terms of the number and type of polymer end groups. The efficiency of the extraction and identification protocol was demonstrated for a blend of additives in a colourant formulation.
AFRIKAANSE OPSOMMING: Verskeie tipes anioniese, nie-ioniese, kationiese en zwitterioniese bymiddels word gebruik in die bedekking nywerheid vir die vervaardiging van verwe en kleurmiddels. Hierdie bymiddels word bygevoeg om sekere eienskappe, soos die stabilisering van pigment dispersie, benatting van pigmente en die verbetering van ope tyd en vries/dooi stabiliteit te versterk. Dikwels is die presiese chemie van hierdie kommersiële bymiddels onbekend en het dit ŉ beperking vir nuwe produk ontwikkeling tot gevolg. Die identifisering en karakterisering van hierdie meer-komponent polimeriese materiaal duur voort om ŉ uitdagings te wees. Hierdie navorsingstudie stel voor die gebruik van verskeie tegnieke om kommersiële bymiddels te identifiseer en karakteriseer wat in meer-komponent kleurmiddel formulasies gebruik word. Die fokus is geplaas op bymiddels wat gebaseer is op poli(etileen glikol) (PEG). The molêre massa verdeling van PEG-gebaseerde bymiddels was bepaal met vloeistofchromatografie gekoppel tot massaspektrometrie (VC-MS) met die gebruik van oplosmiddel gradient eluasie en by kritiese toestande van adsorpsie (VCKT) van PEG. Deur die kombinasie van VC-MS, proton kern magnetiese resonansie spektroskopie (1H KMR), pirolisegaschromatografie (pir-GC-MS) en Fourier-transformasie infrarooi spektroskopie in verswakking totale refleksie modus (FTIR-VTR), is verskillende bymiddels geïdentifiseer in terme van die hoeveelheid en tipe polimeer eindgroep teenwoordig. Die doeltreffendheid van die ekstrahering en identifisering protokol is gedemonstreer vir ŉ mengel van bymiddels in ŉ kleurmiddel formulering.

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De, Wet Pierre. "Powered addition as modelling technique for flow processes." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4166.

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Thesis (MSc (Applied Mathematics))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The interpretation – and compilation of predictive equations to represent the general trend – of collected data is aided immensely by its graphical representation. Whilst, by and large, predictive equations are more accurate and convenient for use in applications than graphs, the latter is often preferable since it visually illustrates deviations in the data, thereby giving an indication of reliability and the range of validity of the equation. Combination of these two tools – a graph for demonstration and an equation for use – is desirable to ensure optimal understanding. Often, however, the functional dependencies of the dependent variable are only known for large and small values of the independent variable; solutions for intermediate quantities being obscure for various reasons (e.g. narrow band within which the transition from one regime to the other occurs, inadequate knowledge of the physics in this area, etc.). The limiting solutions may be regarded as asymptotic and the powered addition to a power, s, of such asymptotes, f0 and f¥ , leads to a single correlating equation that is applicable over the entire domain of the dependent variable. This procedure circumvents the introduction of ad hoc curve fitting measures for the different regions and subsequent, unwanted jumps in piecewise fitted correlative equations for the dependent variable(s). Approaches to successfully implement the technique for different combinations of asymptotic conditions are discussed. The aforementioned method of powered addition is applied to experimental data and the semblances and discrepancies with literature and analytical models are discussed; the underlying motivation being the aspiration towards establishing a sound modelling framework for analytical and computational predictive measures. The purported procedure is revealed to be highly useful in the summarising and interpretation of experimental data in an elegant and simplistic manner.
AFRIKAANSE OPSOMMING: Die interpretasie – en samestelling van vergelykings om die algemene tendens voor te stel – van versamelde data word onoorsienbaar bygestaan deur die grafiese voorstelling daarvan. Ten spyte daarvan dat vergelykings meer akkuraat en geskik is vir die gebruik in toepassings as grafieke, is laasgenoemde dikwels verskieslik aangesien dit afwykings in die data visueel illustreer en sodoende ’n aanduiding van die betroubaarheid en omvang van geldigheid van die vergelyking bied. ’n Kombinasie van hierdie twee instrumente – ’n grafiek vir demonstrasie en ’n vergelyking vir aanwending – is wenslik om optimale begrip te verseker. Die funksionele afhanklikheid van die afhanklike veranderlike is egter dikwels slegs bekend vir groot en klein waardes van die onafhanklike veranderlike; die oplossings by intermediêre hoeveelhede onduidelik as gevolg van verskeie redes (waaronder, bv. ’n smal band van waardes waarbinne die oorgang tussen prosesse plaasvind, onvoldoende kennis van die fisika in hierdie area, ens.). Beperkende oplossings / vergelykings kan as asimptote beskou word en magsaddisie tot ’n mag, s, van sodanige asimptote, f0 en f¥, lei tot ’n enkel, saamgestelde oplossing wat toepaslik is oor die algehele domein van die onafhanklike veranderlike. Dié prosedure voorkom die instelling van ad hoc passingstegnieke vir die verskillende gebiede en die gevolglike ongewensde spronge in stuksgewyspassende vergelykings van die afhankilke veranderlike(s). Na aanleiding van die moontlike kombinasies van asimptotiese toestande word verskillende benaderings vir die suksesvolle toepassing van hierdie tegniek bespreek. Die bogemelde metode van magsaddisie word toegepas op eksperimentele data en die ooreenkomste en verskille met literatuur en analitiese modelle bespreek; die onderliggend motivering ’n strewe na die daarstelling van ’n modellerings-raamwerk vir analitiese- en rekenaarvoorspellingsmaatreëls. Die voorgestelde prosedure word aangetoon om, op ’n elegante en eenvoudige wyse, hoogs bruikbaar te wees vir die lesing en interpretasie van eksperimentele data.

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Nehme, Bilal. "Techniques non-additives d'estimation de la densité de probabilité." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2010. http://tel.archives-ouvertes.fr/tel-00576957.

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Dans cette thèse, nous proposons une nouvelle méthode d'estimation non-paramétrique de la densité de probabilité. Cette méthode d'estimation imprécise combine la théorie de distribution de Schwartz et la théorie de possibilité. La méthode d'estimation que nous proposons est une extension de la méthode d'estimation à noyau. Cette extension est basée sur une nouvelle méthode de représentation de la notion de voisinage sur laquelle s'appuie l'estimation à noyau. Cette représentation porte le nom de noyau maxitif. L'estimation produite est de nature intervalliste. Elle est une enveloppe convexe d'un ensemble d'estimation de Parzen-Rosenblatt obtenus avec un ensemble de noyaux contenus dans une famille particulière. Nous étudions un certain nombre des propriétés théoriques liées à cette nouvelle méthode d'estimation. Parmi ces propriétés, nous montrons un certain type de convergence de cet estimateur. Nous montrons aussi une aptitude particulière de ce type d'estimation à quantifier l'erreur d'estimation liée à l'aspect aléatoire de la distribution des observations. Nous proposons un certain nombre d'algorithmes de faible complexité permettant de programmer facilement les mathodes que nous proposons.

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Luo, Ming. "Development of high-performance polymeric composites by using novel 3D printing techniques." Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/24670.

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Polymers and their composites have been widely used in tribological applications as alternatives to metallic materials, owing to their excellent strength, high efficiency and low cost. Recently, additive manufacturing technology, also known as 3D printing, has attracted considerable attention due to its outstanding flexibility and low cost for rapid prototyping. The production of polymeric parts has become the focus in the field, owing to the tremendous versatility and easy processability of polymeric materials. In particular, there are significant research interests in the use of 3D printing technology to develop high-performance fibre reinforced polymeric composites. In the view of the above-mentioned facts, the present research focuses on the mechanical and tribological behaviours of fibre reinforced polymer composites fabricated using 3D printed technologies. Further, different surface textures were created on printed samples to improve their tribological behaviour. The results showed that FDM printed short carbon fibre reinforced nylon composites provided both better mechanical and tribological performance than pure nylon. Surface textures could further reduce the wear rate of fibre reinforced composite materials under the dry sliding condition by collecting hard wear debris and thus avoiding the severe three-body abrasive wear. It was also noticed that the FDM printed nylon and short carbon fibre reinforced nylon composites provided continuous and uniform transfer film layers under both dry and water-lubricated conditions. The work has demonstrated that 3D printing technology has great potential for developing new wear-resistant engineering materials by controlling and creating desirable compositions and geometric structures/textures simultaneously, which can be subjected to various tribological applications.

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Aydinlilar, Melike. "Implicit modeling for additive manufacturing." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0336.

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Les surfaces implicites offrent de nombreuses solutions utiles pour les tâches d'infographie, telles que des requêtes simples d'intérieur/extérieur, une représentation indépendante de la résolution et une définition compacte. Cependant, les visualiser de manière robuste et efficace représente un défi, en particulier pour les surfaces définies avec des fonctions complexes. Dans la partie I, nous présentons une méthode de rendu en temps réel pour les surfaces intégrales définies par squelettes. Elle s'appuie sur l'utilisation d'un A-Buffer construits dynamiquement sur le GPU pour éviter le traitement des espaces vides et réduire le nombre de primitives de squelettes à traiter localement. La recherche des racines est effectuée à l'aide d'une interpolation quadratique rationnelle pour limiter le nombre d'évaluations de potentiel. La partie II introduit une arithmétique d'intervalle basé sur les primitives pour le traitement efficace des surfaces intégrales pour le rendu et le tranchage en temps réel. Enfin, dans la partie III, nous présentons une famille de méthodes d'inclusion robustes pour le rendu d'une large famille de représentation implicites. Les intersections rayon-surface sont calculées de manière fiable et efficace à l'aide de fonctions d'inclusion linéaires et quadratiques calculées soit en bornant les dérivées de premier et de second ordre, soit en construisant les bornes à partir des opérations algébriques de base définissant la fonction de potentiel. Le problème de la génération de bornes infinies ou non valides est éliminé en réduisant dynamiquement la taille des intervalles. Des exemples pour le rendu en temps réel et le tranchage pour la fabrication additive sont donnés pour des surfaces implicites à squelette, des surfaces de convolution et des fonctions de bases radial
Implicit surfaces provide many useful solutions for computer graphics tasks such as simple in/out queries, resolution independent representation and compact definition. However, rendering them robustly and efficiently provides a challenge especially for surfaces defined with complex field functions. In Part I, we introduce a real-time rendering method for skeleton-based integral surfaces. It relies on dynamically built A-buffers on GPU to discard empty spaces and reduce the number of skeleton primitives evaluation. The root finding is performed using rational quadratic interpolation to limit the number of field evaluations. Part II introduces a per-primitive interval arithmetic for skeleton-based integral surfaces for real-time rendering and slicing, and finally in Part III we introduce a family of robust forward inclusion methods for rendering a wide family of implicits. Using linear and quadratic inclusion functions calculated either by bounding the first and second order derivatives, or building the bounds up from the basic algebraic operations that constitute the field function definitions, ray-surface intersections are calculated reliably and efficiently. The problem of creating infinite or invalid bounds are eliminated by reducing the interval sizes and bounding piece-wise defined functions. Example surfaces are given with skeleton-based implicits, convolution surfaces, Hermite radial basis implicits for real-time rendering and slicing for additive manufacturing

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Zejfart, Martin. "Comparison between a Polyaspartate based additive and conventional techniques for tartaric stabilisation." Master's thesis, ISA/UL, 2018. http://hdl.handle.net/10400.5/17934.

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Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de Agronomia
Among the various enological products authorized by the European legislation, metatartaric acid (MTA) and carboxymethyl cellulose (CMC) are the most widely used to prevent tartrate salts instability, although showing some drawbacks concerning long-term efficacy the former, and colour instability the latter. Recently, an additive based on potassium polyaspartate (KPA) has been evaluated with regards to tartaric stabilisation, to obtain the admission of its use by the European Commission in 2017. The following thesis project developed at the Research Centre of Laimburg (Italy) aims to test the stabilisation effectiveness of potassium polyaspartates (KPA) on local red and white wines, in comparison with the two most widely used additive agents (MTA and CMC) and a subtractive technique (cold stabilisation). Analysis of stability were carried out over a period of six months, as well as chemical-physical parameters (turbidity, tartaric acid, chromatic characteristics) and sensory evaluations of each treatment. Statistical analysis between all trials’ results confirmed the importance of time in recognising the different performances of the used additives aimed to inhibit the crystallisation process of tartaric acid salts, whose behaviour produced different responses with regard to tartrate stability, turbidity and sensory profile. Best results were observed in wines treated with potassium polyaspartate (KPA) and cold stabilisation, although the latter is considered to bring some drawbacks related to operating costs, thus sustainability. Storage temperature effect (35°C) on the different treatments was also evaluated, obtaining again good responses from the polyaspartate based product, although depending on the dose applied. Sensory evaluation confirmed that the debate is still current, expressing greater preference towards cold stabilisation rather than any additive treatment
N/A

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Boehme, Lindsay Erin. "Additives Screening Techniques and Process Characterization for Electroplating of Semiconductor Interconnects." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1402058542.

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Woods, Adam Xavier. "Exploring Combinatorial Libraries for Material Screening Techniques via Additive Manufacturing: Design, Fabrication, & Applications." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1594772957272505.

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Hamad, Aamir Hamed. "Additive Manufacturing Techniques to Enhance the Performance of Electronics Created on Flexible andRigid Substrates." Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1598253714624332.

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Hatchett, Susan Elizabeth. "Development of techniques for the analysis of additives in aviation turbine fuel." Thesis, University of Portsmouth, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292302.

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Kamat, Ashish V. "AN INVESTIGATION OF IMAGE PROCESSING TECHNIQUES FOR PAINT DEFECT DETECTION USING A MACHINE VISION SYSTEM." UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_theses/332.

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Detection and inspection of metal surface corrosion in the ballast tanks of U.S. Navy ships has been a long time problem. The adverse climatic conditions to which the ballast tanks are exposed and the uneven geometry of ballast tanks makes the visual inspection process of surface coatings a difficult job. Thousands of tanks are inspected yearly, with the average cost of an individual tank inspection at approximately $8-15 thousand/each. To aid the visual inspection process, this research is conducted to develop a new technique to automate the visual task of metal surface inspection by image acquisition and post processing. The best results of image processing are achieved by the enhanced contrast between the paint defect and the background using a newly developed optically active additive (OAA) used in paints. Thorough investigation of image processing algorithms has been carried out and a background of imaging theory and experiments is illustrated in this work.

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Elahpour, Nafise. "Organic-Inorganic Hybrid Bioactive Biomaterials for Tissue Engineering via Additive Manufacturing Techniques : Doping, Development, and Characterization." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2024. http://www.theses.fr/2024UCFA0062.

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Presque toutes les disciplines médicales peuvent nécessiter des biomatériaux, y compris la dentisterie, l'orthopédie et divers types de chirurgie. Les spécifications de ces biomatériaux varient en fonction du domaine et de l'application, ce qui conduit à un catalogue très diversifié. Cela inclut les greffes dérivées d'animaux et d'humains, ainsi que des catégories de matériaux significatives comme les métaux, les céramiques et les polymères, y compris des formes comme les hydrogels, les nanogels et les composites. Lors de la création d'un nouveau matériau, il est essentiel de considérer l'utilisation prévue pour déterminer les caractéristiques requises et l'approche de développement. Cette thèse se concentre sur la greffe osseuse.Les matériaux dérivés des animaux soulèvent des préoccupations concernant la compatibilité tissulaire, la pathogénicité et le rejet. Par conséquent, la recherche se concentre sur l'avancement des biomatériaux artificiels capables de promouvoir la régénération osseuse. Les principales alternatives actuelles à l'os naturel sont les "céramiques bioactives" qui présentent une biocompatibilité, une liaison spontanée à l'os, une promotion de l'adhésion des cellules ostéoblastiques et une biodégradabilité. Cependant, la fragilité de ces matériaux limite leurs utilisations potentielles malgré leurs caractéristiques biologiques désirables.La structure unique du tissu osseux inspire des solutions à ces limitations. Elle se compose d'une phase inorganique de cristaux de phosphate de calcium résorbables et d'une phase organique de collagène. Les matériaux innovants peuvent imiter cette structure à double phase, en combinant la dureté de la phase inorganique avec la robustesse des fibres de collagène. En combinant des céramiques bioactives avec de la matière organique, des implants peuvent être créés avec des caractéristiques mécaniques semblables à celles de l'os naturel.L'équipe de biomatériaux a développé et breveté une structure tridimensionnelle novatrice combinant du verre et un polymère dans un hybride organique-inorganique. Le développement d'une nouvelle solution de greffe osseuse nécessite de relever plusieurs défis cruciaux. Premièrement, une solution pour le prototypage rapide et reproductible de scaffolds est impérative, avec une attention significative portée à la fabrication additive, notamment l'impression 3D. Deuxièmement, les scaffolds doivent présenter des caractéristiques initiales de bioactivité et de liaison osseuse. Étant donné les préoccupations liées à la résistance antibactérienne et aux nouvelles souches bactériennes, les substituts osseux doivent créer un environnement inhospitalier pour les microorganismes. Explorer les alternatives antimicrobiennes dérivées de la nature est un axe de recherche important. Enfin, la viabilité cellulaire est fondamentale. Ces principes fondamentaux forment la pierre angulaire de cette thèse.La première section comprend des généralités, en commençant par une présentation détaillée des substituts osseux, en particulier ceux à base de verre bioactif. Elle décrit le protocole de synthèse des hybrides organique-inorganique précédemment développés et introduit la porosité via l'impression 3D. Cette section détaille également toutes les méthodes de caractérisation employées pour évaluer le comportement physico-chimique et les caractéristiques biologiques des matériaux.La deuxième partie retrace le développement et l'optimisation des matériaux hybrides dopés aux ions métalliques. Elle implique l'optimisation du processus de dopage, l'évaluation des précurseurs possibles et la fabrication de scaffolds à partir des hybrides dopés aux métaux synthétisés. Chaque section se termine par des caractérisations in vitro des propriétés physico-chimiques et biologiques du matériau final.La troisième section explore les phytochemicals d'origine végétale, en particulier ceux qui contribuent au développement de matériaux antibactériens incorporés dans l'hybride
Almost all medical disciplines can require biomaterials, including dentistry, orthopedics, and various types of surgery. The specifications of these biomaterials vary depending on the field and application, leading to a highly diverse catalog. This includes grafts derived from animals and humans, and significant material categories like metals, ceramics, and polymers, including forms like hydrogels, nanogels, and composites. When creating a novel material, it's essential to consider the intended use to determine the required characteristics and development approach. This thesis focuses on bone grafting.The rise in life expectancy is accompanied by a decline in the general health of older individuals and a resurgence of chronic diseases. Musculoskeletal system impairment is particularly devastating, accelerating the onset of dependency. Younger individuals experiencing traumatic or pathological circumstances also face similar challenges. (...) These facts highlight a significant challenge.Animal-derived materials raise concerns about tissue compatibility, pathogenicity, and rejection. Consequently, research focuses on advancing artificial biomaterials that can promote bone regeneration. Current primary alternatives to natural bone are "bioactive ceramics" that exhibit biocompatibility, spontaneous bonding to bone, promotion of osteoblast cell adhesion, and biodegradability. However, the fragility of these materials limits their potential uses despite their desirable biological characteristics.Bone tissue's unique structure inspires solutions to these limitations. It consists of an inorganic phase of resorbable calcium phosphate crystals and an organic collagen phase. Innovative materials can mimic this dual-phase structure, combining the hardness of the inorganic phase with the toughness of collagen fibers. By combining bioactive ceramics with organic matter, implants can be created with mechanical characteristics resembling natural bone.The Biomaterials team has developed and patented a novel three-dimensional structure combining glass and polymer in an organic-inorganic hybrid. Developing a new bone grafting solution requires addressing several crucial issues. Firstly, a solution for rapid, reproducible prototyping of scaffolds is imperative, with significant attention towards additive manufacturing i.e. 3D printing. Secondly, scaffolds must exhibit initial bioactivity and bone-bonding features. Given concerns related to antibacterial resistance and new bacterial strains, bone substitutes must create an inhospitable environment for microorganisms. Exploring antimicrobial alternatives derived from nature is a significant research focus. Finally, cell viability is fundamental. These fundamentals form the cornerstone of this thesis.The first section comprises generalities, starting with a detailed presentation of bone substitutes, particularly those based on bioactive glass. It outlines the synthesis protocol for previously developed organic-inorganic hybrids and introduces porosity via 3D printing. This section also details all characterization methods employed to assess the materials' physicochemical behavior and biological features.The second part retraces the development and optimization of metal ion-doped hybrid materials. It involves optimizing the doping process, evaluating possible precursors, and manufacturing scaffolds from synthesized metal-doped hybrids. Each section concludes with in vitro characterizations of the final material's physicochemical and biological properties. The third section explores the plant-based phytochemicals, particularly those contributing to developing antibacterial materials incorporated into hybrid

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Liberti, Joseph Charles. "Evaluation of several techniques for enhancing speech degraded by additive noise in mobile radio environments /." This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10102009-020029/.

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Liberti, Joseph C. "Evaluation of several techniques for enhancing speech degraded by additive noise in mobile radio environments." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/45099.

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This thesis presents a study of several algorithms for enhancing speech degraded by additive noise in mobile cellular communications. The primary goal of this multi-stage study was to examine adaptive noise cancellation techniques in which one microphone is used to measure the speech plus noise signal and another microphone is used to form an estimate of the interfering background noise.

The first stage of this research project involved the design and operation of a measurement system to gather dual channel audio samples in mobile radio environments for use in testing adaptive noise cancellation algorithms developed at Northeastern University. In the second phase of this research, several adaptive algorithms were used to implement noise cancellation systems which were applied to the measured speech signals. In the third phase of this research, several of the adaptive noise cancellation algorithms are compared and additional speech enhancement techniques are investigated.

Master of Science

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Lenner, Lukas. "Engine Redesign Utilizing 3D Sand Printing Techniques Resulting in Weight and Fuel Savings." Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1472734710.

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Huang, Ching-Yao. "Measurement and Comparison of Progressive Addition Lenses by Three Techniques." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306849853.

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DeRieux, David A. "Investigation of spectral-based techniques for classification of wideband transient signals in additive white Gaussian noise." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA282954.

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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, March 1994.
Thesis advisor(s): Ralph Hippenstiel, Monique P. Fargues. "March 1994." Includes bibliographical references. Also available online.

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Henprasert, Pantip. "Comparison of the accuracy of implant position using surgical guides fabricated by additive and subtractive techniques." Thesis, University of Iowa, 2019. https://ir.uiowa.edu/etd/6956.

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Objective: The purpose of this study was to evaluate the accuracy of surgical guides for dental implant placement fabricated by additive and subtractive techniques. Methods: A standardized mandible model (BoneModels, Castellón, Spain) was duplicated and the proposed implant position was performed from a diagnostic wax-up. An implant was placed in the printed model as a reference. Cone beam computed tomography (CBCT) was made with the radiographic surgical guide to design a surgical guide on BlueSky Plan 4 software. The .stl file of the surgical guide was exported and fabricated by two different techniques: additive (3D printing) and subtractive (milling). Fifteen surgical guides per group were used to place implants in the printed models. The angular deviations, differences in depth, coronal and apical deviations were measured using GeoMagic Control X software. Results were analyzed by Wilcoxon-Mann-Whitney (Wilcoxon Rank Sum) test and PERMANOVA (Permutational Multivariate Analysis of Variance). Intraclass correlation was used to analyze the reproducibility. A 0.05 level of significance was used, with Bonferroni multiple adjustment as needed. Results: There were no significant differences in accuracy of implant placement using additive technique vs subtractive techniques. The mean angular deviations between planned and actual position of implant in mesio-distal cross-section were 0.780±0.803 degrees for printed group and 0.772±0.724 degrees for the milled group. The analogous results in bucco-lingual cross-section were 1.601±1.223 degrees in in printed group and 1.767±0.762 degrees in the milled group. The differences in depth (mm) were measured in four aspects including mesial, distal, buccal and lingual. The mean differences in depth in the group that using printed surgical guides were 0.373±0.285 mm, 0.325±0.230 mm, 0.240±0.228 mm, and 0.247±0.168 mm in those 4 aspects, respectively. The mean differences in depth in the group that using milled surgical guides were 0.511±0.326 mm, 0.396±0.316 mm, 0.215±0.230 mm, and 0.230±0.122 mm in those four aspects, respectively. The mean coronal deviation showed 0.32 mm in the printed group and 0.27 mm in the milled group. For the apical deviation, the results of this study showed mean apical deviation 0.84 mm in the printed group and 0.80 mm in the milled group. Conclusions: No statistically significant difference was identified between the position of implant placed using surgical guide fabricated by the additive technique (3D printing) vs surgical guides fabricated by subtractive technique (milling). The 3D-printed surgical guide could be an alternative for guided-implant surgery with the benefits of high accuracy, ease of fabrication and reduction of laboratory time and materials, thereby increasing cost-effectiveness.

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McQuire, N. L. "An investigation into the additive effects of two behavioural techniques in the modification of tobacco-smoking behaviour." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375354.

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Norris, Eleanor. "Surface modification of additively manufactured Ti-6Al-4V using an abrasive vibratory finishing technique." Thesis, University of Bath, 2019. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767608.

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Additive Manufacturing (AM) enables greater geometrical flexibility in engineering design than conventional manufacturing methods, allowing parts to be customized for individual needs, as well as producing less waste material. However, partially bonded powder particles attached to the surfaces limit the usefulness of parts for a range of engineering applications. In order to enable more widespread use of AM, surface modification techniques are required which allow parts to be suitably finished for the requirements of different applications. Additive Manufacturing (AM) enables greater geometrical flexibility in engineering design than conventional manufacturing methods, allowing parts to be customized for individual needs, as well as producing less waste material. However, partially bonded powder particles attached to the surfaces limit the usefulness of parts for a range of engineering applications. In order to enable more widespread use of AM, surface modification techniques are required which allow parts to be suitably finished for the requirements of different applications. A range of surface modification techniques exist which have been proven capable of improving the surface quality of AM parts. Each technique has its own set of benefits and limitations in terms of surface quality, geometrical flexibility, and the impact of the technique on the material properties. For this reason, there is no one-size-fits-all solution to surface modification for AM. Instead, it has been proposed that these techniques should be treated as a surface modification toolkit, from which techniques can be selected for the individual requirements of a component and its application. This research aims to develop and test a surface modification technique which could address some of the limitations of existing techniques. In this research, a set of candidate techniques are tested during preliminary experimentation, and from these, the Abrasive Vibratory Finishing (AVF) technique is selected for further testing. Experimental and computational techniques are employed to determine the surface modification capability of the technique on AM Ti-6Al-4V. An image processing tool is developed to allow quantification of the removal of partially bonded powder particles from the surfaces. Computational Fluid Dynamics (CFD) is used to gain further knowledge of the process mechanisms, and to understand the impact of different parameters on the technique. The research shows that the AVF technique is capable of removing partially bonded particles from AM components, particularly from surfaces perpendicular to vibratory motion. The surface modification capability can be improved by increasing abrasive grit size. CFD modelling suggests that the process could be further improved by separately varying frequency and velocity of the vibrations. The research has also highlighted the fundamental difference between processing of AM surfaces and non-AM surfaces due to the variation between specimens, and the stress concentration created at the attachment points of individual particles and agglomerates.

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Doan, Van Tu. "Modèles réduits pour des analyses paramètriques du flambement de structures : application à la fabrication additive." Thesis, Valenciennes, 2018. http://www.theses.fr/2018VALE0017/document.

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Le développement de la fabrication additive permet d'élaborer des pièces de forme extrêmement complexes, en particulier des structures alvéolaires ou "lattices", où l'allégement est recherché. Toutefois, cette technologie, en très forte croissance dans de nombreux secteurs d'activités, n'est pas encore totalement mature, ce qui ne facilite pas les corrélations entre les mesures expérimentales et les simulations déterministes. Afin de prendre en compte les variations de comportement, les approches multiparamétriques sont, de nos jours, des solutions pour tendre vers des conceptions fiables et robustes. L'objectif de cette thèse est d'intégrer des incertitudes matérielles et géométriques, quantifiées expérimentalement, dans des analyses de flambement. Pour y parvenir, nous avons, dans un premier temps, évalué différentes méthodes de substitution, basées sur des régressions et corrélations, et différentes réductions de modèles afin de réduire les temps de calcul prohibitifs. Les projections utilisent des modes issus soit de la décomposition orthogonale aux valeurs propres, soit de développements homotopiques ou encore des développements de Taylor. Dans un second temps, le modèle mathématique, ainsi créé, est exploité dans des analyses ensemblistes et probabilistes pour estimer les évolutions de la charge critique de flambement de structures lattices
The development of additive manufacturing allows structures with highly complex shapes to be produced. Complex lattice shapes are particularly interesting in the context of lightweight structures. However, although the use of this technology is growing in numerous engineering domains, this one is not enough matured and the correlations between the experimental data and deterministic simulations are not obvious. To take into account observed variations of behavior, multiparametric approaches are nowadays efficient solutions to tend to robust and reliable designs. The aim of this thesis is to integrate material and geometric uncertainty, experimentally quantified, in buckling analyses. To achieve this objective, different surrogate models, based on regression and correlation techniques as well as different reduced order models have been first evaluated to reduce the prohibitive computational time. The selected projections rely on modes calculated either from Proper Orthogonal Decomposition, from homotopy developments or from Taylor series expansion. Second, the proposed mathematical model is integrated in fuzzy and probabilistic analyses to estimate the evolution of the critical buckling load for lattice structures

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Lerebours, Augustin. "Use of additive manufacturing techniques for the production of customized implants with complex geometry : application to reparative hand surgery." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2531.

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L’arthrose est une pathologie entraînant la dégénération des surfaces articulaires. Dans le cas particulier de l’articulation trapézo-métacarpienne, l’arthrose déforme de façon irréversible l’os trapèze entraînant perte de la mobilité et amoindrissement de la force de préhension couplé à des douleurs à la base du pouce. Les solutions thérapeutiques ne sont cependant pas satisfaisantes avec des reprises fonctionnelles limitées entraînant une perte de qualité de vie du patient. Dans le cas de la main, la personnalisation des implants semble être pertinente du fait de la grande variabilité des caractéristiques mécaniques articulaires et des spécificités musculo-squelettiques. Ce travail de thèse porte sur la méthodologie de réalisation d’implant trapézo-métacarpien patient-spécifique, basé sur les potentialités des technologies de fabrication additive métal. Il s’agit plus globalement de développer, analyser et valider les étapes de réalisation d’un implant à géométrie complexe quelconque depuis l’imagerie médicale jusqu’à l’implantation. Les travaux se concentrent dans un premier temps sur l’identification de paramètres spécifiques du patient afin de « rajeunir » numériquement son os déformé à son stade pré-pathologique pour concevoir l’implant idéal et l’adaptation du modèle à la fabrication d'additive (DfAM). La fabrication de l’implant et les post-traitements sont également étudiés d’un point de vue biologique (cytocompatibilité, réaction du système immunitaire), mécanique (microstructure, propriété de frottement) et morphologique (quantification des déviations géométriques). L’approche d’implantation chirurgicale est abordée au travers de divers tests sur des cadavres permettant de mieux intégrer les bénéfices/risques pour le patient. Une étude sur la psychologie du patient souffrant de la rhizarthrose et de ses attentes clôture ce manuscrit. Les résultats ont donné lieu aux dépôts de 2 brevets et à la rédaction de 6 articles scientifiques
Osteoarthritis is a pathology that causes the degeneration of joint surfaces. In the particular case of the trapezo-metacarpal joint, osteoarthritis irreversibly deforms the trapezium bone, causing loss of mobility and reduced grip strength coupled with pain at the base of the thumb. However, therapeutic solutions are not satisfactory with limited functional recovery resulting in a loss of quality of life for the patient. In the case of the hand, the personalization of implants seems to be relevant because of the great variability of the joint mechanical characteristics and the musculoskeletal specificities. This thesis work focuses on the methodology for creating a trapezio-metacarpal implant patient-matched, based on the potentialities of additive metal manufacturing technologies. More generally, it involves developing, analyzing and validating the steps involved in the manufacture of any complex geometric implant from medical imaging to implantation. The work initially focuses on identifying specific patient parameters in order to numerically "rejuvenate" the deformed bone in its pre-pathological stage to design the ideal implant and adapt the model to additive manufacturing (DfAM). Implant manufacturing and post-treatment are also studied from a biological (cytocompatibility, immune system response), mechanical (microstructure, friction property) and morphological (quantification of geometric deviations) point of view. The surgical implantation approach is addressed through various tests on cadavers to better integrate the benefits / risks for the patient. A study on the psychology of the patient suffering from rhizarthrosis and his expectations for a therapeutic solution concludes this manuscript. The results have led to 2 patents and the writing of 6 scientific articles

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Schunemann, Esteban. "Paste deposition modelling : deconstructing the additive manufacturing process : development of novel multi-material tools and techniques for craft practitioners." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/13803.

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A novel paste deposition process was developed to widen the range of possible materials and applications. This experimental process developed an increasingly complex series of additive manufacturing machines, resulting in new combinations of novel materials and deposition paths without sacrificing many of the design freedoms inherit in the craft process. The investigation made use of open-source software together with an approach to programming user originated infill geometries to form structural parts, differing from the somewhat automated processing by 'closed' commercial RP systems. A series of experimental trials were conducted to test a range of candidate materials and machines which might be suitable for the PDM process. The combination of process and materials were trailed and validated using a series of themed case studies including medical, food industry and jewellery. Some of the object created great interest and even, in the case of the jewellery items, won awards. Further evidence of the commercial validity was evidenced through a collaborative partnership resulting in the development of a commercial version of the experimental system called Newton3D. A number of exciting potential future directions having been opened up by this project including silicone fabrics, bio material deposition and inclusive software development for user originated infills and structures.

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Beaumesnil, Mathieu. "L'identification et quantification d'additifs dans les carburants et les lubrifiants par HPTLC-MS et techniques de dérivatisation." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR061.

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Les compagnies pétrolières améliorent les propriétés de leurs produits et en particulier des carburants par l’ajout d’additifs. Un large choix de familles d’additifs est disponible, tels que les antioxydants ou les agents antidétonants. Dans ce travail, la chromatographie sur couche mince haute performance (HPTLC) a été utilisée pour quantifier certains additifs dans le gazole sans aucune préparation d’échantillon. L’HPTLC est une technique d’analyse qui est couramment utilisée afin d’analyser et quantifier des composés en mélange. Pour améliorer la détection des polymères et la qualité du signal, des méthodes de dérivatisation ont été utilisées. Afin de confirmer l’identification des composés et obtenir des informations structurales, un couplage direct entre l’HPTLC et la spectrométrie de masse a été développé. Les sources d’ionisation, comme la source DESI(Desorption Electrospray Ionization), la source DART (Direct Analysis in Real Time) et la source MALDI (Matrix Assisted Laser Desorption Ionization) ont été évaluées. Il est apparu que la source MALDI était la plus adaptée pour la désorption des additifs sur plaque HPTLC. Après des essais et optimisations sur différentes phases stationnaires, une méthode HPTLC-MALDI sur phase cellulose a été développée et a permis de détecter les détergents aux teneurs réelles dans le gazole. Parallèlement, l’HPTLC a été couplé pour la première fois à la source ASAP (Atmospheric Solids Analysis Probe)
Oil companies increase the quality of their products such as fuels by using additives. A large variety of additives can be used, such as antioxidants or antiknock agents. In this study, high performance thin layer chromatography (HPTLC) was used to quantify some additive in diesel fuel without sample preparation. HPTLC is an analytical technique used to characterize and quantify compounds in mixtures. To increase polymer detection and signal quality, derivatization methods were used.In order to confirm the analyte identification and to provide structural information, a method based on the direct coupling of HPTLC to mass spectrometry (MS) was developed. Ionization sources such as DESI (desorption electrospray ionization), DART (direct analysis in real time) and MALDI (matrix assisted laser desorption ionization) were evaluated. It appeared that MALDI was the most suitable source to efficiently desorb the additives on HPTLC plate. After several tests and optimizations on different stationary phases and ionization sources, a HPTLC-MALDI method was developed on cellulose and allowed to detect surfactant in diesel fuel at real concentration. At the same time, ASAP (atmospheric solids analysis probe) was coupled for the first time to HPTLC

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Behmanesh, Javad. "Étude de la durabilité d'un sédiment, traité au ciment et additifs." Caen, 2008. http://www.theses.fr/2008CAEN2015.

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Un axe de développement durable se décline dans le recyclage et la valorisation de la majorité des déchets. En effet, en France, on estime à environ 50 millions de m³ le volume moyen de sédiments dragués annuellement. Dans les travaux de recherche présentés dans cette thèse, une valorisation d’un sédiment dragué au port autonome du Havre est proposée. Quatre liants: chaux, cendre volante, ciment et fumée de silice ont été utilisés dans cet objectif. Après une introduction générale sur le traitement des sédiments dragués, une étude bibliographique est présentée au chapitre II. Le chapitre III est consacré aux caractéristiques d’un sédiment traité. Une méthodologie de préparation des échantillons est ensuite donnée au chapitre IV. Le chapitre V présente alors l’analyse et l’interprétation des résultats des essais. Finalement des conclusions et des perspectives sont proposées au chapitre VI. Au terme de ces travaux, l’utilisation des sédiments dragués en tant que matériau possible dans le domaine routier apparaît tout à fait envisageable. Un procédé de traitement de sédiments fins, pollués par une huile de vidange est présenté. Les performances mécaniques et la durabilité du sédiment traité avec de la fumée de silice et du ciment sont améliorées
An axis of sustainable development deals with recycling and valorization of the majority of waste. In France, the average volume of sediments annually dredged is estimated to be 50 millions cubic meters. In the research presented in this dissertation, the valorization of dredged sediment at the autonomous port of Le Havre is proposed. Four binders, namely, lime, fly ash, cement and silica fume were used in this study. After a general introduction on the treatment of dredged sediments, a review of literature is presented in chapter II. Chapter III is devoted to the study of the characteristics of the treated sediment. A method of sample preparation is given in chapter IV. Chapter V present the analysis and interpretation of the results of the experiments. Finally the conclusion and perspectives are proposed in Chapter VI. Upon completion of this work, the use of the dredged sediments as a possible material in the domain of road appears quite conceivable. A technique for treating fine sediments, polluted by an engine oil is presented. On the other hand, the mechanical performance and durability of sediments treated with silica fume are improved

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Le, Van-Thao. "Proposition d'une stratégie soutenable pour donner une nouvelle vie à une pièce en s’appuyant sur les techniques de fabrication additive." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI038/document.

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Actuellement, les matériaux collectés à partir de produits en fin de vie sont recyclés en matière première pour être réutilisés dans un nouveau cycle de production. Cependant, la consommation énergétique des filières de recyclage reste importante. Le processus du recyclage fait aussi perdre la valeur ajoutée et l’énergie utilisée durant la fabrication de pièces originales. Aujourd’hui, les techniques de fabrication additive sont suffisamment performantes et permettent une fabrication de produits avec un matériau compatible avec l’usage. La prise en compte des performances de ces nouvelles techniques dans une stratégie soutenable peut ouvrir des pistes pour modifier les pièces et les réutiliser directement sans retourner au niveau de matière première. Cette thèse a pour objectif de développer une stratégie soutenable, qui permet de donner une nouvelle vie à une pièce en fin de vie (ou une pièce existante) en la transformant directement en une nouvelle pièce destinée à un autre produit. Afin de développer une telle stratégie, les travaux menés de la thèse visent à résoudre les verrous scientifiques suivants :Le premier verrou scientifique est lié à la faisabilité technologique : est-il possible de déposer de la matière sur une pièce existante en utilisant les techniques de fabrication additive pour obtenir la nouvelle pièce avec une bonne santé de matière ? Cette question a été résolue en réalisant une étude expérimentale sur l’observation de microstructures et de propriétés mécaniques des éprouvettes, qui sont fabriquées par ajout de nouvelles entités sur une pièce existante en EBM. Le deuxième verrou scientifique est lié à l’étude de la chaîne complète de fabrication d’un point de vue technologique. Comment concevoir des gammes de fabrication en combinant intelligemment des opérations additives et soustractives pour obtenir la pièce attendue à partir de la pièce existante ? Une méthode de conception des gammes de fabrication combinant les procédés additifs et soustractifs a été proposée en s’appuyant sur le concept d’entités de fabrication additive et soustractive. Le troisième verrou scientifique est lié à la soutenabilité et la stratégie présente-t-elle des avantages par rapport à la stratégie conventionnelle en termes de soutenabilité ? Une approche s’appuyant sur la méthode d’Analyse du Cycle de Vie (ACV) a aussi été développée pour évaluer des impacts environnementaux. Des critères permettant de qualifier le domaine de la stratégie proposée vis-à-vis de la stratégie conventionnelle ont été identifiés
Currently, materials collected from end-of-life (EoL) products are recycled into raw material for reusing in a new production cycle. However, energy consumptions of recycling sectors remain important. The added values and energy used in the manufacture of original parts are also lost during the material recycling process. Nowadays, additive manufacturing techniques are sufficiently efficient and allow the manufacture of products with a material compatible with the use. Taking into account the performances of these techniques in a sustainable strategy can open the ways to modify parts and reuse them directly without returning to the raw material level. This thesis aims to develop a sustainable strategy, which allows giving a new life to an EoL part (or an existing part) by transforming it directly into a new part intended for another product. In order to develop such a strategy, the works of the thesis aims to solve the following scientific issues : the first scientific issue is related to the technological feasibility : is it possible to deposit material on an existing part using additive manufacturing technologies to obtain the new part with good material health ? This question is solved by carrying out an experimental study on the observation of microstructures and mechanical properties of the samples, which are manufactured by adding new features into an existing part in EBM. The second scientific issue is related to the study of the complete manufacturing chain from a technological point of view. How to design the process planning for additive and subtractive manufacturing combination to manufacture the expected part from the existing part ? To solve this question, a methodology to design the process planning for combining these manufacturing processes has been proposed based on the concept of additive manufacturing and machining features.The third scientific issue is linked to the sustainability and does the new strategy have advantages in comparison to the conventional strategy in terms of sustainability ? An approach based on the Life Cycle Assessment (LCA) method has also been developed to assess environmental impacts. The criteria for qualifying the domain of the proposed strategy vis-a-vis the conventional strategy were also identified

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VENTOLA, LUIGI. "High-efficiency heat transfer devices by innovative manufacturing techniques." Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2644177.

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In the present thesis, novel methods devoted to develop high heat transfer efficiency devices have been presented. These methods rely on both novel manufacturing techniques, belonging to the class of additive manufacturing (AM), and thermal and fluid-dynamics studies and optimization procedures. As a first result, optimization of a traditional heat exchanger from a real application, i.e. million of units produced per year, is presented; That is manufactured by extrusion. A thermal fluid-dynamic model is experimentally validated (from an industrial experimental test rig) and used for optimization purposes. Results demonstrate there is room for efficiency optimization even in well established heat transfer devices configurations based on traditional manufacturing techniques. Then, an experimental rig for ''in house'' thermal characterization is designed. It guarantees high precision measurement of small convective heat fluxes (forced air) on enhanced solutions investigated hereinafter, namely micro-structured surfaces and small heat transfer devices. To deal with that challenge, an innovative convective heat flux sensor is developed. That exploits the concept of thermal guard to avoid any spurious perturbation between the flow field and investigated surfaces, while it allows to cancel out terms due to spreading conduction phenomenon. Results demonstrate remarkable accuracy in direct measurement of convective heat fluxes through this novel concept. Relying on the proposed experimental rig, various methods for enhanced convective heat transfer are experimentally investigated. Firstly, regular patterns of micro-protrusions are studied. Effect of fluid-dynamics and geometrical length on heat transfer performances are discussed. More important, they have been applied to develop an optimization procedure tailored to deal with AM techniques. Results from both experimental investigation and optimization procedure suggest the existence of an optimal value of protrusion height, that maximize performance-to-cost ratio for patterns made by AM. Then, surface roughness of components built by DMLS has been investigated as an augmentation heat transfer technique. Surface roughness is controlled varying DMLS process parameters and its effect on convective heat transfer is measured. The results demonstrate a remarkable enhancement in convective heat transfer due to DMLS artificial roughness, in the investigated configurations. That preliminary study unveils the potential of AM artificial roughness as an heat transfer enhancement techniques. It has been considered, by academic and industrial institutions, as an important step towards development of next generation gas turbine components and electronic cooling devices. Finally, extreme flexibility in shape of parts built by DMLS is exploited to design and fabricate in one step an unconventional heat transfer device, called Pitot heat exchanger. Enhanced heat transfer efficiency is achieved, with regard to standard heat exchangers. Nevertheless, the most important achievement has been to highlight unusual morphologies allowed by AM can pave the way to revolutionary changes in conceiving and designing heat transfer components.

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Richter, Frank. "Development of the Solution-Spray Flash-Vacuum-Pyrolysis Technique in the Synthesis of Allenyl Isothiocyanates and Synthesis of Complex 2-Amino-1,3-thiazole Derivatives." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-175339.

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Gas-phase thermolysis is a long-known and well established method for the preparation of reactive species. It is, however, limited to relatively volatile substances, which are easily vaporised. In the present work, the solution-spray technique for preparative scale was developed. With this technique, it is possible to subject low-volatile substances, which hardly vaporise even under high-vacuum conditions, to gas-phase thermolysis. By utilising oil nozzles used in heating and burner systems, it was possible to integrate a stable solution-spray into the existing flash-vacuum-pyrolysis system. The influence of several variables, such as flow-rate, pressure, temperature and solvent was determined. The solution-spray technique was applied in [3,3]-sigmatropic rearrangements of certain propargyl thiocyanates to the corresponding allenyl isothiocyanates. Furthermore, the parent compound propa-1,2-dienyl isothiocyanate was reacted with various sterically demanding primary and secondary amines to form 2-amino-1,3-thiazoles in moderate to excellent yields. Based on this, a catalyst-free four-center three-component reaction was developed. 2-Amino-1,3-thiazoles with complex substituents in 5-position at the heterocyclic ring are formed. Reaction mechanisms are discussed to explain the occurance of a highly substituted 1,3-thiazine structure. The influence of reaction temperature, concentrations and solvent were determined and are also discussed. It was shown that 2-amino-5-methyl-1,3-thiazoles are the apparently first aromatic substance class, that readily undergoes Prins-type 1,3-dioxane ring-formation
Die Gasphasenthermolyse ist eine lang bekannte und etablierte Methodik zur Synthese reaktiver Spezies. Sie ist allerdings auf flüchtige Substanzen mit einer guten Verdampfbarkeit beschränkt. Für schwerflüchtige Verbindungen, welche sich selbst im Hochvakuum nur mäßig oder gar nicht in die Gasphase bringen lassen, wurde in der vorliegenden Arbeit die Solution-Spray-Technik für die Anwendung im präparativen Maßstab entwickelt. Unter Verwendung von Ölzerstäuberdüsen, wie sie in der Heizungs- und Brennertechnik Anwendung finden, wurde die Erzeugung eines stabilen Lösungs-Sprays in die vorhandene Blitzvakuumpyrolyse-Technik integriert. Der Einfluss verschiedener Variablen, wie Flussrate, Druck, Temperatur und Lösungsmittel wurde untersucht. Die Solution-Spray-Technik wurde für die [3,3]-sigmatrope Umlagerung bestimmter Propargylthiocyanate zu Allenyl-isothiocyanaten angewendet. Des Weiteren wurde Propa-1,2-dienylisothiocyanat – das einfachste Allenylisothiocyanat – mit diversen sterisch anspruchsvollen primären und sekundären Aminen in mäßigen bis exzellenten Ausbeuten zu 2-Amino-1,3-thiazolen umgesetzt. Darauf aufbauend konnte eine Vier-Zentren-drei-Komponenten-Reaktion entwickelt werden. Es entstehen in hohen Ausbeuten 2-Amino-1,3-thiazole mit komplexen Substituenten an der 5-Position des Heterocyclus. Reaktionsmechanismen werden diskutiert um die alternative Bildung einer hochsubstituierten 1,3-Thiazinstruktur zu erklären. Der Einfluss von Reaktionstemperatur, Konzentration und Lösungsmittel auf das Produktverhältnis wurde ebenfalls untersucht und wird diskutiert. Es konnte gezeigt werden, dass 2-Amino-5-methyl-1,3-thiazole als offenbar erste aromatische Substanzklasse sehr gute Substrate für die Bildung von 1,3-Dioxanen nach Prins darstellen

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Kühn, Carol. "Digital sculpture : conceptually motivated sculptural models through the application of three-dimensional computer-aided design and additive fabrication technologies." Thesis, [Bloemfontein] : Central University of Technology, Free State, 2009. http://hdl.handle.net/11462/50.

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Kowalski, Kazimierz. "Étude de la ségrégation et de la diffusion dans le monoxyde de cobalt pur et dope et des propriétés électriques de cet oxyde." Nancy 1, 1994. http://www.theses.fr/1994NAN10413.

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La diffusion du cobalt, du nickel, du calcium et du chrome, aux joints de grains du monoxyde de cobalt coO, est étudiée à l'aide de traceurs radioactifs. Il est montré que le chrome et le calcium manifestent une importante ségrégation aux joints de grains avec un facteur de ségrégation supérieur à 10. Les coefficients de diffusion aux joints de grains des 4 éléments ont été estimés. Le facteur d'accélération entre la diffusion en volume et la diffusion aux joints de grains est de l'ordre de 10#5 - 10#6. Les propriétés électriques (conductivité, pouvoir thermoélectrique) de films minces de coO déposés sur un support inerte de beO ont été étudiées. Il est montre qu'en ce qui concerne la structure de défauts de la couche frontière de coO, il faut prendre en compte, à la fois, la formation de donneurs tels que les ions cobalt en position interstitielle et des interactions plus fortes entre les défauts que celles existantes dans le volume, entrainant la formation de défauts complexes sous forme d'amas de type 4:1. L'étude du rôle du chrome sur les propriétés électriques de coO a mis en évidence la modification de la mobilité des porteurs. Il est établi l'existence de deux domaines distincts de la pression partielle d'oxygène pour la structure des défauts: au-dessous de 1 pa les défauts majoritaires sont des lacunes de cobalt isolées. Aux pressions d'oxygène plus élevées, l'interaction entre les défauts entraine la formation d'amas de type 4:1

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Hachem, Walid. "Déconvolution autodidacte au second ordre de signaux vectoriels en présence de bruit additif." Marne-la-Vallée, 2000. http://www.theses.fr/2000MARN0088.

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Cette these traite d'identification dite autodidacte de canaux de transmission lineaires a temps discret. On s'interesse plus particulierement aux techniques d'identification basees sur les statistiques du second ordre du signal recu representees par sa fonction de covariance. La premiere partie de cette these concerne l'identification d'une fonction de transfert rationnelle multi-entree multi-sortie a partir de la fonction de covariance associee a cette fonction privee du coefficient de covariance central. Ce probleme se rencontre dans les situations concretes ou le bruit additif est spatialement colore. Deux approches independantes qui reclament des conditions peu restrictives sur la fonction de transfert a estimer sont proposees. Ces deux methodes exploitent une fonction matricielle qui ne depend explicitement que des coefficients de covariance connus. - la premiere approche estime le coefficient central a l'aide d'une technique de type sous-espace appliquee a cette fonction matricielle. Une fois ce coefficient estime, l'estimation de la fonction de transfert elle-meme est un probleme du second ordre classique. - la deuxieme approche est basee sur la factorisation de wiener-hopf de cette fonction matricielle par rapport au cercle-unite. Elle debouche sur l'estimation directe de la fonction de transfert. La deuxieme partie de la these concerne l'estimation de canaux cdma en liaison montante. Les conditions d'identifiabilite requises par les algorithmes sous-espace connus ne sont pas claires. Un algorithme qui requiert une condition d'identifiabilite claire et non restrictive est propose. Une analyse des performances theoriques de cet algorithme dans les conditions asymptotiques est egalement proposee

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Jaufurally, Abdus Samad. "Oligomérisation enzymatique d'alcools p-hydroxycinnamiques : production de synthons et additifs pour la chimie des polymères." Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2016. http://www.theses.fr/2016IAVF0013/document.

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Le but des travaux de cette thèse a été de mettre en place des protocoles de synthèse et de polymérisation de composés phénoliques. Le premier objectif a été de développer et optimiser des modes opératoires robustes et reproductibles permettant de polymériser de manière contrôlée ces derniers en présence d’oxydases, et particulièrement de laccase. Les études mécanistiques menées dans le cadre de ces nouveaux procédés ont mené à une meilleure compréhension de la réactivité des phénols (oxydation, dismutation) et à de nouveaux modes de valorisation de ces composés. Ainsi, ces procédés nous ont permis d’accéder sélectivement à des composés phénoliques de complexité structurale et fonctionnalité variées (dimères, trimères ou oligomères peu polydisperses) pouvant être utilisés en tant qu’antioxydants ou encore monomères/synthons pour la chimie des polymères. Pour illustrer le potentiel de ces composés phénoliques dans le domaine des polymères, ils ont été mis en jeu dans des réactions de polymérisation par métathèse (ADMET) et polymérisation radicalaire (thiol-ène)
The purpose of this thesis was to develop experimental protocols for the polymerization of phenoliccompounds.The first objective was to develop and optimize robust and reproducible procedures to control thepolymerization of phenolic compounds in the presence of oxidases, such as laccase. Mechanisticstudies were conducted during these new processes in order to have a better understanding of thereactivity of phenols (oxidation, dismutation) and find new ways of valorization of such compounds.Thus, these methods have enabled us to selectively access phenolic compounds of structuralcomplexity and variable functionalities (dimers, trimers or oligomers) that can be used asantioxidants or monomers for the polymer chemistry. To illustrate the potential of these phenoliccompounds in the field of polymers, they have been involved in polymerization reactions such asADMET and radical polymerizations (thiol-ene)

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Trivedi, Yash Nipun. "Investigation of Mechanical Properties of Bulk and Additively Manufactured Ni-Mn-Ga Shape Memory Alloy using Nanoindentation and Microhardness Techniques." Youngstown State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1558656191440726.

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Norrie, Christian. "Explainable AI techniques for sepsis diagnosis : Evaluating LIME and SHAP through a user study." Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-19845.

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Articial intelligence has had a large impact on many industries and transformed some domains quite radically. There is tremendous potential in applying AI to the eld of medical diagnostics. A major issue with applying these techniques to some domains is an inability for AI models to provide an explanation or justication for their predictions. This creates a problem wherein a user may not trust an AI prediction, or there are legal requirements for justifying decisions that are not met. This thesis overviews how two explainable AI techniques (Shapley Additive Explanations and Local Interpretable Model-Agnostic Explanations) can establish a degree of trust for the user in the medical diagnostics eld. These techniques are evaluated through a user study. User study results suggest that supplementing classications or predictions with a post-hoc visualization increases interpretability by a small margin. Further investigation and research utilizing a user study surveyor interview is suggested to increase interpretability and explainability of machine learning results.

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Dissertations / Theses on the topic 'Additive technique'

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