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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.
221

Marknadsundersökning kring additiv tillverkning i Sverige / Market research on Additive Manufacturing in Sweden

Tavajoh, Sara, Michael, Huynh January 2018 (has links)
Användningen och intresset för additiv tillverkning (AM) har ökat markant de senaste åren och det finns en teori kring att tillverkningsmetoden kan vara det nästa steget i den industriella revolutionen. Eftersom AM fortfarande befinner sig i utvecklingsstatidet går det att anta att tekniken ännu inte uppnått sin fulla potential och att det kan komma att finnas möjligheter att implementera tekniken i fler branscher och företag. Detta skulle innebära en bredare marknad för AM. Syftet med examensarbetet var att undersöka vilka möjligheter och hinder som finns för ökad användning av AM i Sverige. Studien genomfördes genom kvalitativa intervjuer med åtta olika verksamheter tillhörande den svenska industrin och en litteraturgenomgång för att presentera nuläget för AM i svensk industriell marknad. Resultatet av datainsamlingen analyserades med modellerna PEST, 4P och slutligen SWOT. De fördelar som har setts med användningen av AM har varit minskade ledtider, minskade kostnader för tillverkning av produkter och verktyg, minskat materialspill och en optimal designprocess med ökad kreativitet. De begränsningar som finns i tekniken i dagsläget är att priset för material och maskiner är dyrt. Vidare anses även kvalitet på slutdetalj, begränsad byggvolym och opålitliga processer vara problematiska. De möjligheter som finns beror huvudsakligen på den forskning som görs. Förutsättningarna för AM i svensk industri kommer att bero på hur tekniken kommer att utvecklas. De hinder som finns är kopplat till kompetensbrist och att det inte finns befintliga standarder för material eller process inom AM. / Within the industrial sector, an increased interest and usage of Additive Manufacturing (AM) throughout the decade has been formed. The layer-upon-layer building technology has been seen and recognized as one of the next industrial revolutionizing methods of production. As the technology is still in the trending and uprising phase it should be considered that its full potential has not yet been achieved, as large opportunities for implementation of AM exist and that new companies and markets have a growing interest in this technology. Through this study a market research was conducted to identify and present what opportunities and obstacles there are for an increased usage of AM in Sweden. A literature study on the Swedish market has been made to present the market as of today. Eight qualitative interviews have also been conducted with companies within the industrial sector to identify the areas of use within AM for production. The concepts and models used to analyze these questions was PEST, Marketing Mix and SWOT. The concluded results for advantages in using AM are shortened lead times, reduced costs of production of components and tools, reduced material waste and optimization of design processes with increased creativity. The concluded challenges are expensive materials and machine, the quality of finished components, limited printing volume due to the 3D-printers and reliability of printing processes. The finalized opportunities that are presented in this work are that AM is dependent on how much research on the subject and factors around it is done. How AM will be applied in the coming future revolves around the advancement in the technology. The obstacles that are found in this study are lack of competence and lack of standard for materials and processes within AM.
222

Corrosion and Sensitized Microstructure Evolution of 3D Printed Stainless Steel 316 and Inconel 718 Dissolvable Supports

January 2018 (has links)
abstract: Additive manufacturing (AM) describes an array of methods used to create a 3D object layer by layer. The increasing popularity of AM in the past decade has been due to its demonstrated potential to increase design flexibility, produce rapid prototypes, and decrease material waste. Temporary supports are an inconvenient necessity in many metal AM parts. These sacrificial structures are used to fabricate large overhangs, anchor the part to the build substrate, and provide a heat pathway to avoid warping. Polymers AM has addressed this issue by using support material that is soluble in an electrolyte that the base material is not. In contrast, metals AM has traditionally approached support removal using time consuming, costly methods such as electrical discharge machining or a dremel. This work introduces dissolvable supports to single- and multi-material metals AM. The multi-material approach uses material choice to design a functionally graded material where corrosion is the functionality being varied. The single-material approach is the primary focus of this thesis, leveraging already common post-print heat treatments to locally alter the microstructure near the surface. By including a sensitizing agent in the ageing heat treatment, carbon is diffused into the part decreasing the corrosion resistance to a depth equal to at least half the support thickness. In a properly chosen electrolyte, this layer is easily chemically, or electrochemically removed. Stainless steel 316 (SS316) and Inconel 718 are both investigated to study this process using two popular alloys. The microstructure evolution and corrosion properties are investigated for both. For SS316, the effect of applied electrochemical potential is investigated to describe the varying corrosion phenomena induced, and the effect of potential choice on resultant roughness. In summary, a new approach to remove supports from metal AM parts is introduced to decrease costs and further the field of metals AM by expanding the design space. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2018
223

Design virtual na reconstrução auricular com material autógeno

Pinheiro, Rogélio Carpes January 2015 (has links)
As cirurgias de reconstrução parcial ou total de orelha são um desafio na medicina, exigindo técnicas complexas e qualificadas, sendo as mais utilizadas àquelas que fazem uso de material autógeno (cartilagem da costela do próprio paciente). Trata-se de um processo artesanal em que o cirurgião deve esculpir manualmente a cartilagem para formar o modelo tridimensional da orelha, denominado framework, dessa forma, o resultado final depende, principalmente, da habilidade do cirurgião plástico. Tendo isso em vista, busca-se, neste trabalho, empregar as tecnologias computacionais utilizadas no Design Virtual para auxiliar o planejamento cirúrgico, utilizando digitalização tridimensional e fabricação digital para aprimorar o resultado da técnica de reconstrução auricular. A metodologia proposta sugere a digitalização tridimensional do paciente e, a partir disso, são projetados templates cirúrgicos para auxiliar a modelagem e o posicionamento do framework. A aplicação cirúrgica valida alguns pontos e possibilita o estudo de melhorias em determinados templates, utilizados então em outras duas reconstruções, obtendo-se resultados positivos. Assim, o uso do Design Virtual mostra-se confiável e útil na cirurgia de reconstrução auricular, levando à melhoria no planejamento e, assim, diminuição do tempo cirúrgico, sem riscos ou complicações ao paciente e com melhores resultados anatômicos. / The partial or total reconstruction of ear is a challenge in plastic surgery, requiring complex and skilled techniques. The most successful reconstructions use autogenous material (cartilage from the patient's own rib). It is a handmade process in which the surgeon must manually sculpt the cartilages to form the three-dimensional model of the ear, usually called as framework. Considering this, the final result depends mainly on the plastic surgeon's skill. In this scenario, the aim of this research is employ computer technologies used in Virtual Design to aid surgical planning, using three-dimensional scanning and digital manufacturing to improve the result of ear reconstruction technique. The proposed methodology suggests surgical templates, based on 3D patient scan, designed to assist the modeling and positioning of the framework. The surgical application validates some points and allows the study of improvements in certain templates, then used in other two surgeries, with positive results. Thus, the use of Virtual Design proves to be reliable and useful in ear reconstruction surgery, leading to improved planning and decreasing surgical time, without any risks or complications for the patient and with better anatomical results.
224

"Manufatura rápida - avaliação das tecnologias de impressão 3D e FDM na fabricação de moldes rápidos" / Rapid Manufactory – Comparative evaluations of 3D printing system against FDM system for Rapid Tooling

José Roberto Martins 16 May 2006 (has links)
Este trabalho avaliou a aplicação das tecnologias de prototipagem rápida por Impressão 3D e FDM (Fused Deposition Modeling) na produção de moldes rápidos. Esta avaliação foi feita com base nas qualidades das peças obtidas por vazamento nos moldes produzidos, bem como nas limitações encontradas em suas utilizações. Foram estabelecidas as principais diferenças do ponto de vista de qualidade, custos, tempos gastos e praticidade. Foram construídos moldes para peças que contemplando vários graus de dificuldades. Para cada ferramental foram obtidos lotes de peças, através dos quais foram analisadas e comparadas as qualidades dos protótipos. / This work evaluated the application of the Rapid Prototyping technologies 3D printer and FDM (Fused Deposition Modeling) in the rapid manufacturing of molds. This evaluation is based on the quality of the parts molded, as well as in the limitations found in the molds applications. As result the main differences related to quality, and usability was established. The molds produced parts with different degrees of geometric difficulties. For each mold, a few prototypes were produced and their qualities compared.
225

A Study of Direct Digital Manufactured RF/Microwave Packaging

Stratton, John W.i. 28 October 2015 (has links)
Various facets of direct digital manufactured (DDM) microwave packages are studied. The rippled surface inherent in fused deposition modeling (FDM) fabricated geometries is modeled in Ansoft HFSS, and its effect on the performance of microstrip transmission lines is assessed via simulation and measurement. The thermal response of DDM microstrip transmission lines is analyzed over a range of RF input powers, and linearity is confirmed over that range. Two IC packages are embedded into DDM printed circuit boards, and their performance is analyzed. The first is a low power RF switch, and the second is an RF front end device that includes a low noise amplifier (LNA) and a power amplifier (PA). The RF switch is shown to perform well, as compared to a layout designed for a Rogers 4003C microwave laminate substrate. The LNA performs within datasheet specifications. The power amplifier generates substantial heat, so a thermal management attempt is described. Finally, a capacitively loaded 6dB Wilkinson power divider is designed and fabricated using DDM techniques and materials. Its performance is analyzed and compared to simulation. The device is shown to compare favorably to a similar device fabricated on a Rogers 4003C microwave laminate using traditional printed circuit board techniques.
226

Live Software for RepRap Assembly Workshops / Live programvara för RepRap monteringskurser

Ludvigsen, Torbjørn January 2016 (has links)
A key step when initiating robot powered production is setting up the control software.This can be a threshold for operators, especially if the software is fragmented and system requirements are extensive.One way to address this is to pre-configure all the control programs and bundle them with a system that fulfills all the requirements. In this work a live operating system (OS) is loaded with control software and configured to  meet the needs of those who have just assembled their first 3D printer.The problem of downloading, configuring and installing various 3D printer controlling programs  is reduced to the problem of distributing and booting the live OS. The solution of loading it onto bootable USB drives is tested and evaluated in the context of a commercial RepRap Assembly Workshop (RAW),  an event where people pay for RepRap 3D printer parts as well as assembly and usage supervision.The RAW is unusually short, so the bootable USB drives' potential to help  RAW hosts with particularly tight time schemes is tested. The results show a limited success.The USB drive is documented not to work for 3 participant groups out of a total of 11 groups.As a solution to fragmented software and diverse system requirements, the live OS is found to work well once booted.Several routes to make the live OS more easily bootable are discussed. Usage examples beyond drop-in replacing existing RAW software setup procedures are discussed. / Alla som startar upp robotiserad produktion måste få igång och börja använda styrprogramvaran.Detta kan inebära en hög tröskel för operatörer, specielt om programen är många och har olika gränssnitt och systemkrav.Ett sätt att hjälpa operatörerna komma igång är att konfigurera alla styrprogram på förhand  och bunta ihop dem med ett system som uppfyller alla krav. I detta arbetet laddas ett live operativsystem med styrprogramvara och konfigureras för att lätt kunna  användas av någon som precis har satt ihop sin första 3D-skrivare.Problemen med hemladdning, konfigurering och installation av en rad olika styrprogram  reduceras till problemet att distribuera och boota live operativsystemet. Lösningen att lasta live-systemet på startbara (eng. bootable) USB-minnen testas och utvärderas  som en del av en kommersiell RepRap monteringskurs (eng. RepRap Assembly Workshop),  ett event där deltagare betalar för RepRap 3D-skrivardelar,  hjälp med att montera ihop dem och med att använda de färdiga 3D-skrivarna.Den undersökta monteringskursen är ovanligt kort, så startbara USB-minnens potential att  underlätta för tidsprässade kursvärdar testas. Resultaten visar en begränsad framgång.Vi visar hur 3 av 11 deltagargrupper inte lyckas använda de startbara USB-minnena.Som en lösning på fragmenterad mjukvara med stora systemkrav fungerar live operativsystemet bra när det väl har startats.Olika sätt att göra live-systemet lättare att starta diskuteras. Tillämpningsområden utöver att ersätta existerande programuppsättslösningar för RepRap monteringskurser diskuteras.
227

參數式一體化之可動關節模型的生成- 以FDM 3D列印為例 / Generation of Parametric Non-Assembly Joint Model: A Case Study for FDM 3D Printers

陳科豫, Chen, Ko Yu Unknown Date (has links)
3D列印的普及讓民眾可利用簡易的建模軟體建立3D模型,但是如何建立可動模型對一般使用者而言卻是一道難題,因為必須考驗建模者對於模型設計與結構的熟悉程度,以及受到目前3D印表機的可印程度等因素限制。目前市面上的3D列印成型技術,以FDM最為普遍,優點是便宜、無毒等,而缺點則為精細度低及需印出支撐材,與其他3D列印技術相比限制較多,且失敗率相對較高。本論文的目標主要是將3D靜態(不可動)的肢體動物模型,以FDM印表機為輸出目標,產生出一體化關節可動模型。根據使用者輸入的模型與骨架,本系統會自動找出關節位置,利用關節點與模型頂點的距離計算各部位關節的半徑大小,並利用外積與旋轉矩陣將可動關節與肢體方向對齊,並調整模型至可動關節可嵌入的大小。使用者可藉由本系統所提供的直覺式操作介面,進行參數化調整,以印出不需組裝之可動模型,我們邀請了10位受試者,透過系統操作教學及任務,讓受試者學習如何使用此系統,並透過問卷的方式探討系統的優缺點。問卷的評分方式是採5分量表,從實驗結果顯示,系統整體有用性平均分數為4.5分,表示本系統能有效的幫助使用者建立可動關節模型;而易用性的平均分數是3.9分,代表本研究在介面設計上雖非重點,但仍有改進的空間;易學性方面的平均分數為4.5 分,表示本系統的操作對使用者是容易學習的。整體而言,實驗結果顯示,本研究所建立的可動關節模型系統已達到輔助使用者建立可動模型的目標,並證實了本研究的發展價值。 / The popularity of 3D printing has allowed people to design 3D models through common 3D modeling software. However, it is still difficult for a regular user to build a model with movable joints because most users are not familiar with mechanical design and it is a great challenge to design such a model that is printable with current 3D printing technology. FDM is the most popular type with the advantages of being cheap. However, its disadvantage is low precision, which make its failure rate higher than others. In this thesis, we aim to design a system that can take a static articulated model and convert it into a non-assemble model with movable joints that is printable on a FDM 3D printer. Our system can automatically find the positions of the joints according to the input mesh and skeleton and compute the radius of the maximal enclosing circle for each joint model. After aligning the joint model with the limb, the system can automatically adjust the size of the whole model such that the joint model can be embedded in the body model. A user can also tune system parameters through an intuitive interface to determine the orientation and limits of each joint. In order to evaluate our system, we invited ten persons to test user our system by completing assigned tasks and filling a usability survey. The survey is a questionnaire consisting of typical five-point Likert-scale items. The survey reveals that the usefulness of our system is 4.5, which means that our system can effectively help the users construct movable joint models. The score of ease-of-use is 3.9, which means that our user interface still have room for improvement although it is the current focus of our system. The score of ease-of-learning is 4.5, which means that our system is easy for the users to learn. In short, from the experimental results, we believe that our system has achieved the goal of providing a 3D modeling system that can assist users in building non-assemble moveable joint models that are printable on FDM 3D printers.
228

Analýza využití 3D tisku v domácnostech / The Analysis of 3D printing use in households

Ureš, Miloslav January 2017 (has links)
The diploma thesis called The Analysis of 3D printing use in households is dealing with the current topic of 3D printers and examines the ways of their use in households in the Czech Republic. The main objective is to analyze the use of 3D printing in households. This means to find out why and how often the owners of 3D printers use them in their households. Also, to find out the whole range of other factors related to the ownership of 3D printers such as frequency usage, machine satisfaction, number of owned printers, etc. Based on the analysis for which the data was collected by the questionnaire survey method and later evaluated using hypotheses and comparisons with another similar survey, criteria for 3D printer selection are compiled. These recommendations serve to those who are interested in acquiring this technology. Research conducted in this thesis may be beneficial for future analyzes of this market, or for inventors of 3D printers who are considering to launch their 3D printers on the Czech market.
229

Évaluation de technologies organiques faibles pertes et d’impression plastique 3D afin de contribuer au développement de solutions antennaires innovantes dans la bande 60 GHz – 140GHz. / Evaluation of low loss organic technologies and 3D-printing plastic technologies in order to develop innovative antenna solutions in the 60 GHz - 140 GHz frequency band.

Bisognin, Aimeric 10 December 2015 (has links)
L’émergence des applications mobiles accessibles depuis un smartphone provoque une très forte augmentation du trafic de données transitant sur les réseaux mobiles. L’augmentation de la capacité du réseau et de la rapidité des connexions sont autant de points cruciaux que les nouvelles générations de réseau mobile devront adresser afin de répondre à la demande des utilisateurs. L’une des solutions viables pour augmenter la capacité du réseau mobile consiste à le densifier afin de permettre la réutilisation des fréquences en déployant des stations de base consommant une faible puissance et couvrant de petites surfaces (les "small cells"). Ce mode de déploiement massif en "small cells" constitue un défi majeur pour le réseau de backhaul afin de reconnecter chacune de ces "small cell" au cœur de réseau. De plus, avec l’évolution du réseau de backhaul vers une architecture de type Centralized Radio Access Network (CRAN), des technologies sans fil pouvant supporter des débits supérieurs à 10Gbit/s seront requises. Étant donné la maturité des technologies silicium au-delà de 100GHz, la bande 116-142GHz semble être un candidat idéal pour établir des communications point à point supérieures à 10Gbit/s et très faible consommation DC. Dans cette thèse, plusieurs solutions d’antennes-lentilles et réflecteurs fonctionnant à 60, 80 et 120GHz sont explorées pour des systèmes WLAN/WPAN et backhaul. Afin de minimiser le coût de la solution antennaire, nous évaluons des technologies d’impression 3D pour la fabrication des lentilles et des réflecteurs, ainsi que des technologies utilisant des matériaux organiques à faibles pertes pour la fabrication des antennes-sources planaires. / The improvement of the capabilities of wireless communication devices (smartphone, tablets …) which require higher and higher data rate, leads to a significant increase of the data traffic needed by each end user. This strong consumer demand for higher data-rate and coverage is stressing a lot the capacity of existing cellular networks. In order to cope with this challenge, one of the most promising solution consists in a network densification based on the deployment of low-power and short-range-radio-coverage base stations (small cells). The development of high data-rate and low power wireless fronthaul and backhaul technologies is a key requirement to enable the deployment of those future small cells (since associated civil works costs generally prevent the use of optical fiber solutions). So far, the wireless industry has been investigating the use of 60 and 80 GHz frequency bands in order to develop low-cost higher than 1Gbit/s backhaul solutions. It is expected that higher data-rate > 10 Gbit/s will be required for fronthaul communications. The broad bandwidth available around 120GHz (116-142GHz) would enable to reach such data rates while lowering the DC power consumption. In this thesis, we develop several lens and reflector antennas operating at 60, 80 and 120GHz for WLAN/WPAN and fronthaul/backhaul networks. In order to minimize the cost of those solutions, we evaluate 3D-printing technologies for the fabrication of the lenses and the reflectors as well as industrial low loss organic packaging technologies for the fabrication of planar antenna-source.
230

Resíduos sólidos industriais do setor cerâmico: uma proposta para redução do impacto ambiental a partir do design e da tecnologia de impressão tridimensional / Industrial solid wastes from the ceramic industry: A proposal to reduce the environmental impact using design and 3D printing technology.

Marcelo Ambrósio 06 November 2015 (has links)
A indústria de cerâmica branca de objetos decorativos e utilitários, produz diariamente um contingente significativo de resíduo de gesso, oriundo do descarte dos moldes, cuja vida útil é extremamente curta. A deposição desse material via de regra é feita em aterros sanitários, sem qualquer tipo de isolamento em células e sem observar as recomendações da Lei da Política Nacional de Resíduos Sólidos. De acordo com a hierarquia estabelecida pela lei, a supressão da geração dos resíduos sólidos aparece como alternativa prioritária do ponto de vista das boas práticas ambientais. É nessa perspectiva que a tecnologia de produção industrial computadorizada de objetos tridimensionais por deposição de matéria prima, surge como alternativa. A intenção desse trabalho é apresentar conceitos de produtos que potencializem o uso dessa tecnologia através de configurações formais inovadoras para o setor, eliminando a utilização do gesso em seu processo de fabricação além de avaliar os resultados obtidos através da análise dos protótipos fabricados. / White ceramic industry of decorative and utilitarian objects, produces daily a significant contingent of waste gypsum, originated from the disposal of moulds, whose lifespan is extremely short. Deposition of this material usually is made in landfills without any type of isolation cells and without observing the recommendations of the Law of the Brazilian solid waste Policy. According to the ranking established by law, the elimination of solid waste generation appears as a priority alternative in terms of good environmental practices. In this perspective, the technology of computerized industrial production of three-dimensional objects by deposition of raw material, is an alternative. The aim of this paper is to present product concepts that enhance the use of this technology through innovative formal settings for the sector and make an analysis about the results.

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