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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.
261

Návrh duální tiskové hlavy pro FDM 3D tiskárnu / Design of dual hot-end for FDM 3D printer

Prouza, Tomáš January 2016 (has links)
This master thesis is focused on a research in the field of 3D printing technology. During the research a particular technology, being regularly applied by the RepRap printers, is described. Mentioned technology is tested on a Rebel II printer model. The findings are applied to the dual 3D extruder design project. This dual 3D extruder is designed and made in two basic options, where the first option discovers the shortcomings and the second option is modified and tested. In the following step, assessment of applicability, functionality, as well as economic analysis of production of this dual 3D extruder is made.
262

Návrh vyhřívaného atypického stolu pro 3D tiskárnu / Design of atypical heated bed for 3D printer

Strnad, Jan January 2016 (has links)
This diploma thesis deals with an atypical heated bed for FDM 3D printer. It presents the most commonly used ways of heating and the chosen variant of the heated beds are realized by powerful resistors. There are also discussed three ways of placement of resistors on the desktop motherboards that are modeled in Autodesk Inventor Professional 2016 and exported to Autodesk Fusion 360, where FEM calculations are made. Optimal alternative is made and tested. The test results are compared with the results of thermal simulations in Autodesk Fusion 360.
263

Využití mobilního telefonu k analýze tekutých vzorků / Use of cell phone in liquids analysis

Křístek, Tomáš January 2016 (has links)
Technological development, broad availability and ubiquity of mobile phones made it possible in recent years to start a progression leading to the integration of mobile phones into biomedical analytical methods, the development of telemedicine and mobile personal health applications. This paper deals with the literature review of the mobile phone usage in biomedicine, with emphasis on the methods of optical analysis and technical solutions using 3D printing technology. It provides a draft and practical implementation of salivary cortiol level measuring system using a mobile phone, ELISA analytical methods, 3D printing technology and a set of custom Matlab functions connected with Matlab Mobile application and Mathworks Cloud. Also provides critical evaluation of results and method possibilities, and presents set of proposals and findings for quality of measurment optimization.
264

Náhrada části lidských kostí umělými materiály s využitím 3D tisku / Replacement of human bones by synthetic materials using 3D printing

Svoboda, Štěpán January 2017 (has links)
The thesis is divided into three main parts. The first section summarizes the theory of the issue. Here we are unified theoretical information about the various possibilities of different approaches. The result of this part is therefore a general summary of theoretical possible procedures of creation bone implant, where each are listed the advantages and disadvantages. The theoretical part also contains information that ultimately, in practice, the author did not use. But his idea was to create a comprehensive look at the issue from several angles. The second part uses theoretical knowledge from the previous set of information as a basis for defining the steps required to successfully manage the issues of bone 3D printing. The third part will follow the guidelines of both previous and focuses on practical making bones and subsequent evaluation method chosen. There are discussed various steps that led to the final conclusion, making bones and work is then focused on the evaluation of the success of selected procedures and recommendations for future action.
265

Sample Delivery Enabled by 3D Printing for Reduced Sample Consumption and Mix-and-Inject Serial Crystallography at X-ray Free Electron Lasers

January 2019 (has links)
abstract: Serial femtosecond crystallography (SFX) with X-ray free electron lasers (XFELs) has enabled the determination of damage-free protein structures at ambient temperatures and of reaction intermediate species with time resolution on the order of hundreds of femtoseconds. However, currently available XFEL facility X-ray pulse structures waste the majority of continuously injected crystal sample, requiring a large quantity (up to grams) of crystal sample to solve a protein structure. Furthermore, mix-and-inject serial crystallography (MISC) at XFEL facilities requires fast mixing for short (millisecond) reaction time points (𝑡"), and current sample delivery methods have complex fabrication and assembly requirements. To reduce sample consumption during SFX, a 3D printed T-junction for generating segmented aqueous-in-oil droplets was developed. The device surface properties were characterized both with and without a surface coating for improved droplet generation stability. Additionally, the droplet generation frequency was characterized. The 3D printed device interfaced with gas dynamic virtual nozzles (GDVNs) at the Linac Coherent Light Source (LCLS), and a relationship between the aqueous phase volume and the resulting crystal hit rate was developed. Furthermore, at the European XFEL (EuXFEL) a similar quantity and quality of diffraction data was collected for segmented sample delivery using ~60% less sample volume than continuous injection, and a structure of 3-deoxy-D-manno- octulosonate 8-phosphate synthase (KDO8PS) delivered by segmented injection was solved that revealed new structural details to a resolution of 2.8 Å. For MISC, a 3D printed hydrodynamic focusing mixer for fast mixing by diffusion was developed to automate device fabrication and simplify device assembly. The mixer was characterized with numerical models and fluorescence microscopy. A variety of devices were developed to reach reaction intermediate time points, 𝑡", on the order of 100 – 103 ms. These devices include 3D printed mixers coupled to glass or 3D printed GDVNs and two designs of mixers with GDVNs integrated into the one device. A 3D printed mixer coupled to a glass GDVN was utilized at LCLS to study the oxidation of cytochrome c oxidase (CcO), and a structure of the CcO Pr intermediate was determined at 𝑡" = 8 s. / Dissertation/Thesis / Supplementary Video D.1 - Droplet formation in a 3D printed droplet generator / Doctoral Dissertation Chemistry 2019
266

Conception d'antennes à base de métal liquide pour applications multiples / Antennas using liquid metal for multiple applications

Cosker, Mathieu 20 June 2017 (has links)
Aujourd’hui l’électronique fait partie intégrante de nos vies. En effet, de plus en plus d’objets intègrent de l’électronique permettant de les connecter, on appelle cela l’internet des objets (IoT). Tous ces dispositifs disposent d’une connectivité sans fil, rendant ainsi indispensable l’intégration d’une ou plusieurs antennes. De plus, l’électronique devant s’adapter à des objets de plus en plus petits et flexibles embarquant de plus en plus de capteurs tout en consommant de moins en moins d’énergie, il est intéressant de se pencher sur l’étude de nouveaux matériaux pour la réalisation d’antennes devant s’adapter à ces nouvelles contraintes. Dans ce cadre, nous nous sommes attachés dans ce travail de recherche, à la conception de structures antennaires à base de métaux liquides à température ambiante dans le but de réaliser des antennes conformables de formes complexes associant l’impression 3D, des antennes reconfigurables et des structures rayonnantes ayant la capacité de capteur. Dans ce manuscrit des prototypes d’antenne comportant ces caractéristiques ont été simulés, réalisés et mesurés. / Today, electronic is an integral part of our lives. Indeed, more and more objects integrate electronics to connect each other, this is the Internet of Things (IoT). All of these wireless devices need one or more antennas. Furthermore, It’s useful to develop new materials to realize new antennas that fit with new constraints: smaller and flexible objects, more and more sensors and less and less consuming.In this context, we have focused this research on antenna structures based on metals which are liquid at room temperature to realize conformable antennas of complex shapes combining 3D printing, reconfigurable antennas and radiant structures with the ability to sensor. In this manuscript, antenna prototypes with these characteristics have been simulated, realized and measured.
267

3D PRINTED FLEXIBLE MATERIALS FOR ELECTROACTIVE POLYMER STRUCTURES, SOFT ACTUATORS, AND FLEXIBLE SENSORS

David F Gonzalez Rodrigez (9192755) 31 July 2020 (has links)
<p>Soft actuators and sensors are currently used in many industrial applications due to their capability to produce an accurate response. Researchers have studied dielectric electroactive polymers (DEAPs) because these types of structures can be utilized as actuators and as sensors being able to convert electrical energy into mechanical and vice versa. However, production of this kind of structures is complex and in general involve several steps that are time consuming. Customization of these types of structures will be ideal to enhance the performance of the devices based on the specific application. 3D printing technologies have emerged as innovative manufacturing processes that could improve fabrication speed, accuracy, and consistency with low cost. This additive manufacturing technique allows for the possibility of increased device complexity with high versatility. </p> <p>This research studied the potential of 3D printing technologies to produce DEAPs, soft actuators, and flexible sensors. The study presents novel designs of these composite flexible structures, utilizing the most flexible conductive and nonconductive materials available for fused deposition modeling, achieving versatility and high performance in the produced devices. <a>Produced DEAP actuators showed an actuation and electric resistivity higher than other electroactive structures like shape memory alloys and ferroelectric polymers.</a> In addition, this research describes the electromechanical characterization of a flexible thermoplastic polyurethane, (TPU), produced by additive manufacturing, including measurement of the dielectric constant, percentage radial elongation, tensile proprieties, pre-strain effects on actuation, surface topography, and measured actuation under high voltage. DEAP actuators were produced with two different printing paths, concentric circles and lines, showed an area expansion of 4.73% and 5.71% respectively. These structures showed high resistance to electric fields having a voltage breakdown of 4.67 kV and 5.73 kV respectively. <a>Those results are similar to the resistant of the most used dielectric material “VHB 4910”. </a></p> <p>The produced soft pneumatic actuators were successfully 3D printed in one continuous process without support material. The structures were totally sealed without the use of any sealing material or post process. Computational simulations were made to predict the response of the designed structures under different conditions. These results were compared with experimental results finding that the theoretical model is able to predict the response of the printed actuators with an error of less than 7%. This error is satisfactorily small for modeling 3D printed structures and can be further minimized by characterization of the elastomeric material. Besides that, two different grippers were designed based on the opening and closing movements of single bellows actuators. The functionality of both designs was simulated and tested, finding that both designs are capable lifting a heavier rigid structure. </p> <p>Finally, this study presents a computational simulation of a 3D printed flexible sensor, capable of producing an output signal based on the deformation caused by external forces. Two different sensors were designed and tested, working based on a capacitance and resistance change produced by structural deformation. Computational analysis indicate the capacitance sensor should undergo change of capacitance from 3 to 8.5 pF when is exposed to 30 kPa; and the resistance sensor should experience an increase from 101.8 to 103 kΩ when is exposed to 30 kPa. </p>
268

The impact of additive manufacturing on sustainability of inbound transportation

Carlek, Johan, de Jonge, Lennart January 2020 (has links)
Background: Emerging technologies enables manufacturing companies the opportunity to stay competitive and at the same time focus on increasing their sustainability impact. One such technology is additive manufacturing which has the potential to change the way manufacturing is performed and impact entire supply chains of manufacturing companies. Multiple studies have been done in the twenty-first century regarding additive manufacturing’s sustainability impact on logistics, although there is little research that focus on impact of additive manufacturing on transportation from a sustainable perspective. Purpose: The purpose of this study is to explore the impact additive manufacturing has on the sustainability of inbound transportation. Method: A qualitative research strategy was used to explore the field of study through a multiple case study method. Through two cases, raw material providers and manufacturers within the additive manufacturing industry, data was gathered using semi-structed interviews. Conclusion: Findings from this study shows that additive manufacturing may have a sustainable impact on inbound transportation from an environmental, societal, and economic perspective. Additive manufacturing is more environmentally sustainable than conventional manufacturing for the inbound transportation leg from the raw material supplier to the manufacturing company since the technology requires lower volume of raw material to be transported, it leads to a higher transport efficiency, less frequent transportation need, and requires no return transportation. In economic impact it leads to fuel savings, less frequent transportation with less material, and a reduced inventory holding. Access to remote areas together with easier and safer material handling is the societal impact from using additive manufacturing instead of conventional manufacturing.
269

High Resolution 3D Printing with Cellulose Acetate

Heyman, Nils January 2020 (has links)
In this project, an additive manufacturing technique called Direct Ink Writing has been used to 3D print structures from polymer solutions containing cellulose acetate. Cellulose acetate is a synthetic compound derived from plants. The intended application involves protein separation filters for medical purposes. The printing has been performed in a lab environment with focus on high resolution, with less than 10 micrometers in fibre size. Glass capillaries with an inner diameter of 3-10 micrometers were used as nozzles. Three-dimensional structures with a height of 100 micrometers and a fibre thickness of 2 micrometers were made. The results indicates that cellulose acetate is a promising polymer for Direct Ink Writing in high resolution. Improvements are needed in the ink design and/or the technical construction of the printer to avoid clogging of the nozzle.
270

Exploration of Rapid Prototyping with Wood Fiber

Ange, Brayden 25 May 2022 (has links)
No description available.

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