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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.
41

Projeto conceitual de órtese estabilizadora para o ombro / Concept and development of shoulder stabilizer orthose

Danielle Aline Barata Assad 26 March 2018 (has links)
A subluxação do ombro é a complicação musculoesquelética mais comum das afecções do Sistema Nervoso Central e Periférico, que leva a diminuição do movimento, da função e aumento de dor. Um dos recursos auxiliares utilizados é a órtese que visa corrigir a deformidade, diminuir a dor e proporcionar a função. Este trabalho objetiva projetar e desenvolver o conceito de uma órtese personalizada estabilizadora de ombro. A metodologia de desenvolvimento de projeto de produto esta dividida em três fases: informacional, conceitual e projeto preliminar. Na fase informacional foi realizada pesquisa bibliográfica, de patentes e de mercado e foram entrevistados 30 prováveis usuários; coletados os dados antropométricos, força muscular manual e goniometria. Na fase conceitual, baseado na fase informacional e a partir da Metodologia TRIZ (Teoria da Resolução de Problemas Inventivos) foi proposto um desenho original de órtese híbrida, personalizada e manufaturada em tridimensional, usando estruturas rígidas e faixas de tração, que estabilizem o ombro, diminua a dor e permita a função. A fase do projeto preliminar foi composta por escaneamento tridimensional e uso de softwares que transformam uma imagem digitalizada em formato STL®. Foram realizadas sucessivas evoluções do projeto com geração de desenhos e peças prototipadas que foi avaliada por um usuário. Na fase informacional, a pesquisa de patentes e de mercado mostrou que há uma predominância dos modelos de órtese estabilizadora de ombro com material flexível onde o principal meio de tração é dado por faixas na diagonal e transversal ao tronco, tendendo a posicionar o ombro em rotação interna. Enquanto os usuários relataram expectativa de uma órtese que corrija o posicionamento, tenha melhor conforto térmico e tátil, menos cheiro e de fácil limpeza. O conceito desenvolvido foi: órtese personalizada, fácil de higienizar e de por/tirar, resistente, articulada, leve, em plástico ABS (acrilonitrila, butadieno e estireno) impressão tridimensional, com veste nos dois braços, com faixas de tração rígidas fixadas à cintura, visando à correção da subluxação do ombro com conforto, menor dor além de permitir função. O teste com usuário corroborou com o conceito, pois o protótipo preliminar apresentou bom acoplamento ao tronco, tração satisfatória e possibilidade de realizar um maior número de atividades diárias com menos dor e sensação de cansaço. / The shoulder subluxation is the most common musculoskeletal complication of Central and Peripheral Nervous System disorders, which leads to a decrease in movement, function and increase in pain. One of the resources used to help with this issue is the orthosis that aims to correct the deformity, decrease the pain and provide function. This work aims to design and develop the concept of a personalized shoulder stabilizing orthosis. The methodology used on the product design is divided into three phases: informational, conceptual and preliminary design. In the informational phase, bibliographic, patent and market research were carried out and 30 potential users were interviewed; anthropometric data, manual muscle strength and goniometry were collected. In the conceptual phase, based on the informational data and using TRIZ Methodology (Theory of Inventive Problem Solving), an original concept design of a hybrid orthosis, personalized and manufactured three-dimensional, using rigid structures and traction bands, was proposed to stabilize the shoulder, reduce pain and allow function. The preliminary design phase consisted of tridimensional scanning and the use of software that transformed a scanned image into STL®. Successive evaluations of the project were carried out with generation of designs and prototyped parts - which the user has evaluated. During the informational phase, the patent and market research demonstrated a predominance of the stabilizing orthosis models using flexible material where the main form of traction was given by diagonal and transverse bands to the trunk, tending to position the shoulder in internal rotation. Users have reported the expectation that this orthosis could correct the shoulder positioning and that it has a better thermal and tactile comfort, less smell and easier to clean. The concept developed was: a personalized orthosis, easy to sanitize and to put on/take off, resistant, articulated, lightweight, in ABS (Acrylonitrile butadiene styrene), three-dimensional printing, with a vest in both arms, rigid traction bands fixed to the waist, aiming to correct the shoulder subluxation with comfort, less pain while allowing function. The user test corroborated with the concept, as the preliminary prototype presented good trunk coupling, satisfactory traction and the possibility to perform a greater number of daily activities with less pain and less fatigue caused by limb weight.
42

Aluminum foams composite : elaboration and thermal properties for energy storage / Mousses d’aluminium composites : élaboration et propriétés thermiques pour le stockage d’énergie

Zhang, Chuan 07 July 2017 (has links)
L'objectif de cette thèse est d'étudier et d'optimiser le processus de fabrication des mousses métalliques et le comportement thermique du matériau de la mousse d'aluminium/matériau de changement de phase (MCP) par des méthodes expérimentales et numériques. Le processus d’élaboration de la mousse d’aluminium à pore ouvert est développé et optimisé pour contrôler précisément les paramètres de fabrication. Deux modèles de mousse d'aluminium à haute porosité (MAHP)/MCP composite et à faible porosité (MALP)/MCP composite sont établis pour la simulation numérique. En simulant le processus de fusion d'un système de stockage d'énergie, les composites MAHP/MCP et MALP/MCP sont comparés numériquement afin d'évaluer la performance de stockage d'énergie thermique. Les résultats montrent que la mousse d'aluminium améliore nettement le processus de transfert de chaleur dans MCP en raison de sa haute conductivité thermique. La porosité des mousses d'aluminium influence non seulement le processus de fusion du composite mais aussi la performance de stockage d'énergie thermique. Grâce à la collaboration avec EPF, une nouvelle méthode d’élaboration des mousses périodiques d'aluminium à pore ouvert est développée dans cette thèse sur la base d’impression 3D. Le comportement thermique des mousses d'aluminium périodiques à pore ouvert/MCP est analysé expérimentalement et numériquement / The objective of this thesis is to study and optimize the manufacturing process of metal foams and the thermal behavior of the aluminum foam/phase change material (PCM) composite by experimental and numerical methods. The manufacturing process of open-cell aluminum foam is developed and optimized to precisely control the parameters of mufacturing. Two pore-scale models of high porosity aluminum foams (HPAF)/PCM composite and low porosity aluminum foams (LPAF)/PCM composite are established for numerical simulation. By simulating the melting process of a layer energy storage system, the HPAF/PCM and LPAFS/PCM composite are compared numerically in order to evaluate the energy storage performance. The results show that aluminum foam improves greatly the heat transfer process in PCM due to its high thermal conductivity. The porosity of aluminum foams could not only influence the melting process of composite but also the energy storage performance. Thanks to the collaboration with EPF, a new manufacturing method of periodic open-cell aluminum foams is developed based on 3D rapid tooling. The thermal behavior of the periodic open-cell aluminum foams/PCM composite is experimentally and numerically analyzed
43

Development of an additive manufacturing re-coater monitoring system for powder bed fusion systems

Du Rand, Francois 05 1900 (has links)
M.Tech (Department of Electronic Engineering, Faculty of Engineering and Technology), Vaal University of Technology / In the world of research and development, the ability to rapidly manufacture a prototype or part has become a significant part of the manufacturing process. This requirement has given rise to some unique manufacturing technologies. One of these technologies is Additive Manufacturing (AM), or also more commonly known as 3D printing. There are several AM technologies available and can be divided into three major AM categories namely: liquid, powder and solid sheet based. For this research study, the primary focus will be on powder-based technologies. Powder-based technologies make use of materials in powder form and use different fusion techniques to fuse the powder particles together. All the powder bed fusion technologies consist of the same basic components, namely a powder chamber, build chamber, re-coater and a powder fusion system. For each layer of the build, the re-coater applies a new layer of powder from the powder chamber to the build chamber, and then the specific type of powder fusion system will fuse the powder particles together. This process will then be repeated until the entire build has completed. Currently, powder bed fusion AM platforms do not have re-coating quality feedback into the printing system. Thus, when errors or defects occur on the powder bed surface during the re-coating process, they can affect the structural integrity of the parts. Parts must then be reprinted, which becomes costly due to wasted raw materials, electricity and time. Raw material and sundry wastage was some of the key factors that reduces the overall efficiency of the identified AM technology. Due to the increased problem with wasted materials, the need arose to develop a re-coater monitoring system, which could be used to increase the overall efficiency of a powder-based system. For the development of a re-coater monitoring system, a review of three different types of monitoring technologies such as computer vision, laser scanning and a time-offlight camera was conducted. Based upon the relatively low cost, low computer resource requirements and high accuracy, computer vision was considered as the best suited technology for development of the monitoring system. To select the correct camera to capture images of the powder bed, the required specifications for the camera, lens and mounting position were determined mathematically. A software program was then developed to autonomously detect re-coating errors on the captured image after each re-coating cycle using image processing techniques. Each of the captured powder bed images were divided into 16 equal sized quadrants, where each quadrant was processed individually. Each of the quadrants was examined using an edge detection algorithm to detect any changes in contrast that would indicate a defect or re-coating error. The probability of a possible re-coating error or defect was calculated for each quadrant and displayed as a percentage value. The active re-coater monitoring system was also integrated into the Voxeljet VX500 to validate the system’s operation. The system was used to monitor a total of seven build jobs on the Voxeljet VX500. However, the first three build jobs could not be successfully monitored as some parameters of the system had to be re-adjusted to ensure proper operation. The last four build jobs were monitored successfully and recorded results that proved that the active re-coater monitoring system could indeed detect defects and re-coating errors when they occurred.
44

Developing equivalent solid model for lattice cell structure using numerical approaches

Al-wattar, Tahseen Abdulridha Ali January 2020 (has links)
No description available.
45

3D Printing of a Multi-Layered Polypill Containing Six Drugs Using a Novel Stereolithographic Method

Robles-Martinez, P., Xu, X., Trenfield, S.J., Awad, A., Goyanes, A., Telford, Richard, Basit, A.W., Gaisford, S. 15 October 2019 (has links)
Yes / Three-dimensional printing (3DP) has demonstrated great potential for multi-material fabrication because of its capability for printing bespoke and spatially separated material conformations. Such a concept could revolutionise the pharmaceutical industry, enabling the production of personalised, multi-layered drug products on demand. Here, we developed a novel stereolithographic (SLA) 3D printing method that, for the first time, can be used to fabricate multi-layer constructs (polypills) with variable drug content and/or shape. Using this technique, six drugs, including paracetamol, cffeine, naproxen, chloramphenicol, prednisolone and aspirin, were printed with dfferent geometries and material compositions. Drug distribution was visualised using Raman microscopy, which showed that whilst separate layers were successfully printed, several of the drugs diffused across the layers depending on their amorphous or crystalline phase. The printed constructs demonstrated excellent physical properties and the different material inclusions enabled distinct drug release profiles of the six actives within dissolution tests. For the first time, this paper demonstrates the feasibility of SLA printing as an innovative platform for multi-drug therapy production, facilitating a new era of personalised polypills.
46

Use of Digital Fabrication Tools and Curriculum with Gifted Students in Rural Middle Schools

Moore, Vince 12 1900 (has links)
This study focuses on the use of American Invention Kits from the Smithsonian Institute in conjunction with a 3D printer. In conjunction with a large dataset from a study funded by the National Science Foundation (NSF), this innovative research focuses on the effect the digital fabrication curriculum unit has on gifted and talented students' knowledge and affinity toward the fields of science, technology, engineering, and mathematics (STEM). Students from two rural middle schools in north-central Texas (N = 190) took part in this quantitative study; the students were divided among four subgroups: gifted-contrast (n = 12), gifted-treatment (n = 8), nongifted-contrast (n = 76), and nongifted-treatment (n = 94). The surveys utilized include the STEM Semantics Survey, TIMSS-Limited, and a knowledge assessment for the specific curriculum unit focused on the solenoid. The STEM Semantics Survey is divided into five subsets. Thirty-two separate one-way repeated measures ANOVAs were performed across the surveys and subgroups. Statistically significant results were found on four comparisons. This research holds implications in the areas of advocating for gifted education, collecting field data, utilizing large datasets, and understanding rural schools.
47

Transmedia STEM Intervention Book in Middle School for Educational Change

Stansell, Alicia 05 1900 (has links)
The world is becoming a global place in which science, technology, engineering and mathematics hold a key to a successful future. To help secure this future it is important to engage students early with relevant curriculum that sparks interest and success in STEM fields. However, education reform occurs slowly, so this paper looked at a potential paradigm that can help to bring about change in a middle school environment that harnesses the long standing strengths of learning and education with the integration of technology to create changes in the pedagogy of learners and teachers. The study implemented a transmedia STEM book and evaluated the impact it had on student perceptions of STEM, school attitude, academic achievement, and preferred activity types, providing an example vehicle for change that can be adopted over time. The main findings showed that students who used a 3-Dimensional printer had higher math achievement and a more positive perception of math.
48

Fatigue Testing of Human Flexor Tendons Using a Customized 3D-Printed Clamping System

Scholze, Mario, Safavi, Sarah, Ramezani, Maziar, Ondruschka, Benjamin, Hammer, Niels 06 December 2023 (has links)
Improved surgical procedures and implant developments for ligament or tendon repair require an in-depth understanding of tissue load-deformation and fatigue properties. Cyclic testing will provide crucial information on the behavior of these materials under reoccurring loads and on fatigue strength. Sparse data are available describing soft tissue behavior under cyclic loading. To examine fatigue strength, a new technology was trialed deploying 3D-printing to facilitate and standardize cyclic tests aiming to determine tendon fatigue behavior. Cadaveric flexor digitorum tendons were harvested and mounted for tensile testing with no tapering being made, using 3Dprinted clamps and holder arms, while ensuring a consistent testing length. Loads ranging between 200 to 510 N were applied at a frequency of 4 Hz, and cycles to failure ranged between 8 and >260,000. S–N curves (Woehler curves) were generated based on the peak stresses and cycles to failure. Power regression yielded a combined coefficient of determination of stress and cycles to failure of R 2 = 0.65, while the individual coefficients for tissues of single donors ranged between R 2 = 0.54 and R 2 = 0.88. The here-presented results demonstrate that S–N curves of human tendons can be obtained using a standardized setting deploying 3D-printing technology
49

Development of a Mechatronics Instrument Assisted Soft Tissue Mobilization (IASTM) Device to Quantify Force and Orientation Angles

Alotaibi, Ahmed Mohammed 05 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Instrument assisted soft tissue mobilization (IASTM) is a form of massage using rigid manufactured or cast devices. The delivered force, which is a critical parameter in massage during IASTM, has not been measured or standardized for most clinical practices. In addition to the force, the angle of treatment and frequency play an important role during IASTM. As a result, there is a strong need to characterize the delivered force to a patient, angle of treatment, and stroke frequency. This thesis proposes two novel mechatronic designs for a specific instrument from Graston Technique(Model GT3), which is a frequently used tool to clinically deliver localize pressure to the soft tissue. The first design is based on compression load cells, where 4-load cells are used to measure the force components in three-dimensional space. The second design uses a 3D load cell, which can measure all three force components force simultaneously. Both designs are implemented with IMUduino microcontroller chips which can also measure tool orientation angles and provide computed stroke frequency. Both designs, which were created using Creo CAD platform, were also analyzed thorough strength and integrity using the finite element analysis package ANSYS. Once the static analysis was completed, a dynamic model was created for the first design to simulate IASTM practice using the GT-3 tool. The deformation and stress on skin were measured after applying force with the GT-3 tool. Additionally, the relationship between skin stress and the load cell measurements has been investigated. The second design of the mechatronic IASTM tool was validated for force measurements using an electronic plate scale that provided the baseline force values to compare with the applied force values measured by the tool. The load cell measurements and the scale readings were found to be in agreement within the expected degree of accuracy. The stroke frequency was computed using the force data and determining the peaks during force application. The orientation angles were obtained from the built-in sensors in the microchip.
50

Resolution-aware Slicing of CAD Data for 3D Printing

Onyeako, Isidore January 2016 (has links)
3D printing applications have achieved increased success as an additive manufacturing (AM) process. Micro-structure of mechanical/biological materials present design challenges owing to the resolution of 3D printers and material properties/composition. Biological materials are complex in structure and composition. Efforts have been made by 3D printer manufacturers to provide materials with varying physical, mechanical and chemical properties, to handle simple to complex applications. As 3D printing is finding more medical applications, we expect future uses in areas such as hip replacement - where smoothness of the femoral head is important to reduce friction that can cause a lot of pain to a patient. The issue of print resolution plays a vital role due to staircase effect. In some practical applications where 3D printing is intended to produce replacement parts with joints with movable parts, low resolution printing results in fused joints when the joint clearance is intended to be very small. Various 3D printers are capable of print resolutions of up to 600dpi (dots per inch) as quoted in their datasheets. Although the above quoted level of detail can satisfy the micro-structure needs of a large set of biological/mechanical models under investigation, it is important to include the ability of a 3D slicing application to check that the printer can properly produce the feature with the smallest detail in a model. A way to perform this check would be the physical measurement of printed parts and comparison to expected results. Our work includes a method for using ray casting to detect features in the 3D CAD models whose sizes are below the minimum allowed by the printer resolution. The resolution validation method is tested using a few simple and complex 3D models. Our proposed method serves two purposes: (a) to assist CAD model designers in developing models whose printability is assured. This is achieved by warning or preventing the designer when they are about to perform shape operations that will lead to regions/features with sizes lower than that of the printer resolution; (b) to validate slicing outputs before generation of G-Codes to identify regions/features with sizes lower than the printer resolution.

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