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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
601

Effect of Size and Shape Parameters on Microstructure of Additively Manufactured Inconel 718

Ahsan, Showmik 08 June 2023 (has links)
No description available.
602

AMBIENT ELECTROSTATICS OF IONS AND CHARGED MICRODROPLETS PRODUCED VIA NANOELECTROSPRAY IONIZATION

Saquib Rahman (12030023) 25 July 2023 (has links)
<p>Mass spectrometry, the science and technology of ions, owes much of its current popularity to the development of electrospray ionization. The development of electrospray ionization, along with its low flow-rate analog nanoelectrospray ionization, has increased the chemical space that can be investigated using mass spectrometers by orders of magnitude. While the interfacial chemistry of charged microdroplets that are generated by nanoelectrospray has been studied in detail, the physics of their motion, particularly in the presence of an applied field at ambient pressures, remains relatively unexplored. In this dissertation, an increase in ion currents detected by a commercial triple quadrupole mass spectrometer is used to demonstrate that: (i) the orthogonal injection of counterions into an electrode assembly can compensate for space charge effects and enhance the sampling of charged microdroplets from a nanoelectrospray focused electrostatically under ambient conditions into the mass spectrometer; and (ii) the ease of ion evaporation from charged microdroplets may be elucidated for small molecules based on their relative transmission through an electrode assembly for the simultaneous ambient electrostatic focusing of two nanoelectrosprays. In each case, the development is characterized by using ion trajectory calculations in conjunction with experiments, using homebuilt devices designed and fabricated in-house as rapid prototypes via 3D printing. In the open air, charged microdroplets have low kinetic energies with a narrow energy spread. Despite these limitations, this dissertation demonstrates, through the electrostatic manipulation of charged microdroplets produced via nanoelectrospray ionization, that a better understanding of the physics of moving charges in the open air can be used to increase the sensitivity of atmospheric pressure ionization.</p>
603

Vision vs. produktion : - En designers frustrerande arbetsprocess från start till mål / Vision vs. production : - A designer's frustrating work process from start to finish

Fältström, Sebastian January 2023 (has links)
Additiv tillverkning eller 3D-utskrift som det även kallas är en produktionsprocess som kan erbjuda snabba prototyper med spännande och komplexa geometriska former. Under de senaste åren har expansionen för additiv tillverkning verkligen tagit fart och tekniken, kombinerat med nya progressiva material, blir alltmer efterfrågat. Jag har i detta examensarbete, tillsammans med Akademiska Hus och Stora Enso, undersökt potentiella produktionsmetoder för additiv tillverkning av storskaliga produkter i biokomposit. Det här samarbetet startade i mars 2022 och produkten som jag framställas är en ljudstol som jag valt att kalla Bönan. Den första versionen vi arbetade med visade sig vara för svår att producera med den additiva tekniken. Det är här mitt examensarbete tagit vid. I arbetet har jag undersökt hur mycket avkall jag som designer behöver göra för att produkten ska kunna produceras mer än bara en gång samt vilka moment som är essentiella för att ta en produkt från vision till produktion. Under examensarbetet har jag även fördjupat mina kunskaper inom additiv tillverkning genom att själv skriva ut småskaliga prototyper för att få en större inblick i produktionsprocessen och vilka tekniska aspekter som är fundamentala för att nå ett önskvärt slutresultat. Jag har även parallellt med detta haft kontinuerlig kontakt med Stora Enso och Akademiska hus och överlagt kring kommande steg i processen. Förhoppningsvis har mina fördjupade kunskaper inom additiv tillverkning och en mer holistiskt fokuserad utgångspunkt kunnat påverka verkshöjden på slutprodukten.
604

Engineering of Elastomeric Biomaterials and Biomimicry of Extracellular Matrix for Soft Tissue Regeneration

Wade, Mary E. January 2016 (has links)
No description available.
605

[en] INNOVATION IN PACKAGING DESIGN, THROUGH BIOMIMETIC AND NEW DIGITAL TECHNOLOGIES / [pt] INOVAÇÃO EM DESIGN DE EMBALAGEM, POR MEIO DA BIOMIMÉTICA E DAS NOVAS TECNOLOGIAS DIGITAIS

CLAUDIA HABIB KAYAT 02 July 2020 (has links)
[pt] A embalagem está no centro de questões de sobrevivência alimentar para mais de sete bilhões de pessoas no mundo. A presente pesquisa tem uma característica exploratória, voltada a investigar se as novas tecnologias digitais (especialmente microtomografia e impressão 3D) potencializam as abordagens de pensar e projetar embalagem por meio de analogias entre biologia e design (Biomimética). Tem também, uma característica experimental, objetivando estimular a criação e prototipação de conceitos inovadores biomiméticos para embalagem de alimentos. Os métodos utilizados foram: pesquisa bibliográfica, documental e de campo; entrevistas com especialistas (biólogos); coleta de materiais biológicos (especialmente frutos) e experimentação - que foi realizada em dois momentos: Experimento A, onde aplicou-se o pensamento biomimético baseado na abordagem Biologia para Projetar (Biomimicry 3.8, 2007), sem uso de novas tecnologias e Experimento B, onde aplicou-se o mesmo pensamento, porém com uso de novas tecnologias (microtomografia e impressão 3D). Graças ao processo de design exploratório e experimental, chegou-se a um conceito de design, que foi resultado de um desdobramento das analogias geradas entre biologia (vagem do amendoim) e design (embalagem). Ele propõe um sistema biomimético inovador para embalagem de alimentos que: aumenta a proteção e conservação, reduzindo o desperdício, permite adaptação a diferentes formatos e dimensões do conteúdo a ser embalado e otimiza o uso de materiais e processos. O resultado final alcançado faz-nos vislumbrar uma série de desdobramentos dessa pesquisa, principalmente ao que se refere à viabilidade técnica e implementação industrial do sistema criado, a fim de que seu uso possa ser generalizado em larga escala e, desta forma, contribuir para gerar impacto positivo nas questões contemporâneas de acesso e preservação de alimentos. / [en] The packaging is at the heart of food survival issues for more than seven billion people in the world. This research has an exploratory characteristic, aimed to investigate whether the new digital technologies (specially microtomography and 3D printing) potentializes the approaches of thinking and designing packaging through analogies between biology and design (Biomimicry). It also has an experimental feature, aiming to stimulate the creation and prototyping of biomimetic concepts for innovative food packaging. The methods used were: bibliographical research, documentary and field; interviews with experts (biologists); collection of biological materials (especially fruit) and trial - which was held in two stages: Experiment A, which applied the biomimetic based thinking approach Biology to Design (Biomimicry 3.8, 2007), without the use of new technologies and Experiment B, where we applied the same thought, but with the use of new technologies (microtomography and 3D printing). Thanks to the exploratory process of and experimental feature, this research came to a design concept, which was the result of a breakdown of analogies generated between biology (pod peanuts) and design (packaging). He proposes an innovative system for Biomimetic package for foods which: increase the protection and conservation, reducing waste, allows adaptation to different shapes and dimensions of the content and optimizes the use of materials and processes. The end result achieved makes us glimpse a number of developments of this research, especially when it comes to the technical feasibility and industrial implementation of the system introduced in order to allow its use to be widespread on a large scale and thus help to generate positive impact on contemporary issues of access and preservation of food.
606

[pt] RENASCENDO DAS CINZAS: EXPERIMENTAÇÃO COM RESÍDUOS DO INCÊNDIO NO MUSEU NACIONAL NA RECRIAÇÃO DE PEÇAS DO ACERVO ATRAVÉS DE MANUFATURA ADITIVA / [en] RISING FROM THE ASHES: EXPERIMENTING WITH FIRE RESIDUES AT THE NATIONAL MUSEUM TO RECREATE PIECES FROM THE COLLECTION THROUGH ADDITIVE MANUFACTURING

BRUNO DA CRUZ TRINDADE 14 January 2021 (has links)
[pt] Esta pesquisa se propõe a uma investigação exploratória na utilização de resíduos carbonizados, como matéria prima para reconstrução de peças perdidas no incêndio que, em setembro de 2018, destruiu parte do acervo do Museu Nacional (MN) da Universidade Federal do Rio de Janeiro (UFRJ), através de tecnologias de Manufatura Aditiva. O que tornou este trabalho possível foi a existência de arquivos digitais obtidos em pesquisas anteriores através de processos não invasivos e não destrutivos de obtenção de superfícies tridimensionais de diversas peças do acervo do museu. A principal contribuição se caracteriza pela possibilidade de recriar peças do acervo do museu, bem como agregar diferentes valores simbólicos aos objetos reproduzidos com resíduos provenientes do próprio MN, através de experimentos realizados com pesquisadores do Laboratório de Processamento de Imagem Digital do Museu Nacional, do Núcleo de Experimentação Tridimensional – NEXT da PUC Rio e do Instituto Nacional de Tecnologia. A pesquisa apresenta uma análise por Microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS) de amostras desse material, com a identificação de sua composição, e segue três linhas de trabalho focadas em processos diferentes de Manufatura Aditiva, o que resultou no desenvolvimento de um filamento termoplástico extrudado, uma massa argilosa em pó e uma linha que combina processos de fabricação digitais e analógicos. As peças produzidas foram exibidas em exposições relacionadas ao Museu Nacional. / [en] This research proposes an exploratory investigation on the use of carbonized residues, as feedstock in Additive Manufacture technologies, for the reconstruction of pieces lost in the fire that destroyed part of Federal University of Rio de Janeiro National Museum(MN) s collection, in September 2018. This work was possible due to the existence of digital files, from previous researches, which were generated through non-invasive and non-destructive processes for obtaining threedimensional surfaces of several pieces from the museum s collection. The main contribution of this work is characterized by the possibility of recreating pieces which incorporate symbolic and imagetic affective aspects to objects reproduced with MN s fire accident residues, through experiments carried out by researchers both from Digital Image Processing Laboratory, of the National Museum, and the National Institute of Technology. This research presents an analysis by scanning electron microscopy (SEM) and dispersive energy spectroscopy (EDS) of samples of this material, identifying its composition, and it follows three guidelines focused on different Additive Manufacturing processes, which resulted in the development of an extruded thermoplastic filament, a clay powder and a line that combines digital and analog manufacturing processes. All used in the recreation of pieces shown in exhibitions related to the National Museum.
607

[pt] DESENVOLVIMENTO E CARACTERIZAÇÃO DE COMPÓSITOS VERDES PARA HABITAÇÕES SOCIAIS / [en] DEVELOPMENT AND CHARACTERIZATION OF GREEN COMPOSITES FOR SOCIAL HOUSING

NATALIA VICTORIA DOS SANTOS 14 September 2021 (has links)
[pt] Os profissionais da construção civil vêm se tornando mais conscientes sobre seu papel no agravamento dos problemas ambientais, levando estes à procura de métodos e materiais que apresentem menos impacto ambiental. O uso de fibras vegetais como reforço vem sendo feito ao longo dos anos de forma a melhorar as propriedades mecânicas de compósitos, sendo estas de caráter renovável e biodegradáveis. A presente pesquisa visa a caracterização de biocompósitos para fabricação de habitações sociais de baixo impacto ambiental através do processo de moldagem por compressão das placas de vedação de tecido de fibra de juta e matriz de poliuretano vegetal e de impressão 3D de perfis e ligações de PLA e fibra vegetal de juta, sisal e rami. Para as placas moldadas por compressão foi feito um estudo da influência da direção da fibra nas propriedades mecânicas, constatando, através de ensaio de flexão monotônica, que a direção principal da fibra (urdume do tecido) apresenta a melhor resistência e maior rigidez, alcançando 37,2 mais ou menos 0,9MPa e 10,4 mais ou menos 1,1GPa, respectivamente. Analisando os efeitos à longo prazo, foi estudado o efeito da radiação ultravioleta nas placas, onde foram feitos ensaios em corpos de prova nas direções 0 graus e 90 graus expostos a uma lâmpada ultravioleta de 365nm por 3 (três) meses. Além disso, com os resultados dos ensaios foi possível aplicar a regra das misturas de forma inversa na determinação das propriedades da fibra e da matriz. Para os compósitos impressos 3D foi analisada a influência do tipo de fibra na resistência à tração e rigidez do material. Pelo ensaio à tração foram constatados aumentos significativos na resistência com o uso de fibras de rami (61,8 por cento) e sisal (110,8 por cento), chegando à resistência de 45,5 mais ou menos 6,1MPa e 59,3 mais ou menos 4,1MPa, respectivamente. / [en] Civil construction professionals have become more aware of their role in aggravating environmental problems, leading them to search for methods and materials that have less environmental impact. Vegetable fibers have been used as reinforcement over the years to improve the mechanical properties of composites, which are renewable and biodegradable. This research aims at the characterization of biocomposites for social housing manufacture with low environmental impact through the sealing plates compression molded process of jute fiber fabric and vegetable polyurethane matrix and 3D printing of PLA profiles and connections of jute, sisal, and ramie vegetable fiber. For the compression molded plates, a study was made to determine the influence of fiber direction on mechanical properties, noting, through a monotonic bending test, that the main fiber direction (warp of the fabric) has the highest resistance and stiffness, with 37.2 plus or minus 0.9MPa and 10.4 plus or minus 1.1GPa, respectively. Analyzing long term effects, the plates were exposed to ultraviolet radiation. In these tests, the specimens were exposed to a 365nm ultraviolet lamp during three months before being submitted to directional resistance trials in 0 degrees and 90 degrees. Furthermore, with the test results, it was possible to apply the mixing rule inversely to determine the fiber and matrix properties. For 3D printed composites, the influence of fiber type on the material s tensile strength and stiffness was analyzed. The tensile test found significant increases in strength with the use of ramie (61.83 percent) and sisal (110.80 percent) fibers, reaching a strength of 45.5 plus or minus 6.1MPa and 59.3 plus or minus 4.1MPa, respectively.
608

Utveckling av betong för additiv tillverkning

Liljestrand, Mathias, Ljungberg, Kirill January 2018 (has links)
Additiv tillverkning har stor potential för framtida betongkonstruktion. Inom industrier såsom fordonsindustrin, läkemedelsindustrin och flygplansindustrin existerar redan additiva tillverkningsmetoder i kommersiellt syfte men kompatibilitet med utvecklade byggstandarder samt svårigheter att balansera nödvändiga materialegenskaper har gjort att utvecklingen inom byggindustrin går resulterat i att utvecklingen efterfrågade egenskaperna. Vid additiv tillverkning skapas objekt genom att material placeras i lager skiktvis. Objekten skapas först digitalt som ett 3D-objekt där det sedan delas upp i horisontella skikt. Sedan följer en 3D-skrivare en förprogrammerad bana där den placerar materian tills objektet nått sin slutgiltiga form. Trots de stora utmaningarna så för additiva tillverkningsmetoder i byggindustrin med sig potentiella fördelar som överväger svårigheterna; komplexa designer till låg kostnad, inget materialspill, snabb byggtid, mindre arbetskraft, mindre miljöpålastningar m.m. Konventionell betong är oanvändbar då betong för additiva tillverkningsmetoder kräver egenskaper som inte har efterfrågats tidigare. Det ska vara flytande nog för pumpning men samtidigt fast nog för stapling. Betongens öppethållandetid krävs vara konstant för att undvika att betongen börjar hårdna innan den skrivs ut. Rapporten avser att bidra till utvecklingen av betongblandningar anpassade för de additiva tillverkningsmetoderna i byggindustrin. Detta åstadkoms genom framtagning och analys av nya typer av betong. Det saknas standardiserade och beprövade metoder för bedömning av betong anpassat för additiva tillverkningsmetoder. Hur tillverkningsmetoden påverkar miljön undersöks med målet att sänka miljöpålastningarna. En god betongblandning för additiva tillverkningsmetoder grundar sig inte endast på dess konstruktionsmässiga syfte, utan också på vilken typ av munstycke som används. På grund av detta är det i dagsläget omöjligt att skapa en universell blandning som är anpassad för samtliga munstycken och skrivarsystem. Betongen kräver en hög cementandel som leder till högre koldioxidutsläpp, andelen betong som krävs är dock lägre på grund av inget materialspill. Tillsatsmaterial används för att sänka cementandelen och nå en mer sammanhållen betongblandning. De slutgiltiga betongblandningarna har utrymme för förbättringar. Vidare justering av vct, tillsatsmaterial, armering och tillsatsmedel bör göras för utveckling av betong för additiva tillverkningsmetoder. / 3D writing of concrete has great potential for future building engeneering. Other industries such as the automotive industry, pharmaceutical industry, aerospace industry, etc. have already additive manufacturing methods for commercial purposes. The reason for this is the high standards set in the construction industry as well as difficulties to balance the demanded properties. At the additive manufacturing creates objects through that the matter be placed in the warehouse incrementally. The objects are first created digitally as a 3D object, which is then divided into horizontal layers. Then a 3D printer follows a pre-programmed path where it places the material until the object has reached its final form. . Despite the major challenges so for additive manufacturing methods in the construction industry, with potential benefits that outweigh the difficulties; complex designs for low cost, no material waste, fast build time, less labor, , less environmental degradation, etc. Conventional concrete is unusable when the concrete for additive manufacturing methods require properties that have not previously been demanded. It should be fluid enough for pumping but at the same time rigid enough for stacking. The concrete opening time is required to be constant in order to avoid that the concrete starts to harden before it is printing. The report intends to contribute to the development of concrete adapted for additive manufacturing methods in the construction industry. This is accomplished through the development and analysis of new types of concrete. There are no standard and proven methods for assessing concrete adapted for additive manufacturing methods. How the manufacturing method affects the environment is examined with the aim of reducing environmental impacts. A good concrete mix for additive manufacturing methods is based not only on its structural purpose, but also on the type of nozzle used. Because of this, it is currently impossible to create a universal mix that is adapted for all of the nozzles and the printer system. The concrete requires a high cement share which leads to higher carbon dioxide emissions, but the percentage of concrete required is lower due to no material play. Additives are used to lower the cement share and achieve a more cohesive concrete mixture. The final concrete mixtures have room for improvement. Further adjustments of vct, additives, reinforcement and chemical admixtures should be made for the development of concrete for additive manufacturing methods.
609

Immunoaffinity Monoliths for Multiplexed Extraction of Preterm Birth Biomarkers from Human Blood Serum in 3D Printed Microfluidic Devices

Almughamsi, Haifa Mohammad 06 August 2021 (has links)
Preterm birth (PTB) results in over 15 million early births annually and is the leading cause of neonatal deaths. There are no clinical methods currently available to evaluate risk of PTB at early stages in pregnancy; thus, a rapid diagnostic to analyze PTB risk would be beneficial. Microfluidic immunoaffinity extraction is a promising platform for preparing complex samples, such as maternal serum with PTB risk biomarkers. 3D printed microfluidic devices have advantages over conventional microfluidic systems including simple fabrication and potential for iterative optimization to improve designs. In this work, I developed immunoaffinity monoliths in 3D printed microfluidic devices modified with antibodies to enrich PTB biomarkers from human blood serum. I retained and eluted a peptide PTB biomarker in both buffer and blood serum using an immunoaffinity column. An additional three PTB biomarkers were also successfully extracted either from buffer or blood serum on single-antibody columns. Both polyclonal and monoclonal antibodies to PTB biomarkers were characterized by dot blots, biolayer interferometry, and surface plasmon resonance to determine their specificity and dissociation constants. I created multiplexed immunoaffinity columns to simultaneously enrich three PTB biomarkers from depleted human blood serum in a single extraction. This is the first demonstration of multiplexed immunoaffinity columns for PTB biomarkers in a 3D printed microfluidic device. My work is a key step towards the future development of 3D printed microfluidic devices for rapid PTB testing.
610

FABRICATION AND CHARACTERIZATION OF LITHIUM-ION BATTERY ELECTRODE FILAMENTS USED FOR FUSED DEPOSITION MODELING 3D PRINTING

Eli Munyala Kindomba (13133817) 08 September 2022 (has links)
<p>Lithium-Ion Batteries (Li-ion batteries or LIBs) have been extensively used in a wide variety of industrial applications and consumer electronics. Additive Manufacturing (AM) or 3D printing (3DP) techniques have evolved to allow the fabrication of complex structures of various compositions in a wide range of applications. </p> <p><br></p> <p>The objective of the thesis is to investigate the application of 3DP to fabricate a LIB, using a modified process from the literature [1]. The ultimate goal is to improve the electrochemical performances of LIBs while maintaining design flexibility with a 3D printed 3D architecture. </p> <p><br></p> <p>In this research, both the cathode and anode in the form of specifically formulated slurry were extruded into filaments using a high-temperature pellet-based extruder. Specifically, filament composites made of graphite and Polylactic Acid (PLA) were fabricated and tested to produce anodes. Investigations on two other types of PLA-based filament composites respectively made of Lithium Manganese Oxide (LMO) and Lithium Nickel Manganese Cobalt Oxide (NMC) were also conducted to produce cathodes. Several filaments with various materials ratios were formulated in order to optimize printability and battery capacities. Finally, flat battery electrode disks similar to conventional electrodes were fabricated using the fused deposition modeling (FDM) process and assembled in half-cells and full cells. Finally, the electrochemical properties of half cells and full cells were characterized. Additionally, in parallel to the experiment, a 1-D finite element (FE) model was developed to understand the electrochemical performance of the anode half-cells made of graphite. Moreover, a simplified machine learning (ML) model through the Gaussian Process Regression was used to predict the voltage of a certain half-cell based on input parameters such as charge and discharge capacity. </p> <p><br></p> <p>The results of this research showed that 3D printing technology is capable to fabricate LIBs. For the 3D printed LIB, cells have improved electrochemical properties by increasing the material content of active materials (i.e., graphite, LMO, and NMC) within the PLA matrix, along with incorporating a plasticizer material. The FE model of graphite anode showed a similar trend of discharge curve as the experiment. Finally, the ML model demonstrated a reasonably good prediction of charge and discharge voltages. </p>

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