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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.
121

Multifunctional Testing Artifacts for Evaluation of 3D Printed Components by Fused Deposition Modeling

Pooladvand, Koohyar 08 December 2019 (has links)
The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.
122

Neuroinformatika: metody kalibrace v multicentrické MR studii / Neuroinformatics: calibration methods in multicentric MR studies

Kovalčík, Tomáš January 2010 (has links)
Work deals with methods of calibration of multi-center study of magnetic resonance imaging. Magnetic resonance is the phenomenon of the substance in a magnetic field of induction B0 delivers energy in the form of RF pulse with the Larmor frequency and thus to excite particles to higher energy levels. Calibration can be performed using the distinctive and homogeneous RF phantoms. Furthermore, we can perform calibration using image registration. To calibrate the images by registering the work described in the classical linear (affine) and nonlinear. Listed below are the simulators, which are also useful for modeling various artifacts.
123

Multifunctional Testing Artifacts for Evaluation of 3D Printed Components by Fused Deposition Modeling

Pooladvand, Koohyar 19 November 2019 (has links)
The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.
124

Ontology and Law: Bioprospecting in Antarctica

Prasad, Rakesh January 2022 (has links)
Could it be that even though no international treaty or regulation regulates bioprospecting in Antarctica, some features of the techno-science of bioprospecting already lie embedded in the deep texts of the potentially most relevant treaties and regulations? If so, international law already to that extent comprehends the phenomenon, making for sustainable governance and thereby sustainable development. To find out, first an ontology of bioprospecting was synthesized, by an activity theory based conceptual system modeling (CSM). Treating bioprospecting as an activity of search for and research of naturally occurring biota, a set of Conceptual Graphs and associated Tables were drawn up as its ontology-synthesis. Features of this conceptualization were then searched for by an ontological-analysis of the deep texts of selected twenty-five legal instruments, through an ontological legal research (OLR). Search results did unearth several features dispersed and intriguingly embedded in several of the treaties and regulations, quite richly in some of the more recent ones. The cross-application of CSM followed by the hybridized OLR, is a methodological innovation and the generated empirical results of each are resources for further research. The language of international law is revealed as possessing a surprisingly better-than-expected techno-scientific literacy of bioprospecting.
125

Digital Garbology - Untersuchung digitaler Rituale des Verschwindens

Ritzmann, Susanne 30 June 2022 (has links)
aus dem INhalt: 'Das Konzept Nachhaltigkeit hält Einzug in alle Lebensbereiche und wird zur Bedingung von Zukunftsszenarien aller Art. Am eindrücklichsten lässt sich das Thema im Design am Phänomen Müll vermitteln. Die gemeinsame Auseinandersetzung mit dem Entwerfen und Wegwerfen von Artefakten ist wegweisend für ein Nachhaltiges Design. Müll ist dabei ein gesellschaftliches und organisationales Konzept, und eine physische Erscheinung, welche ich nutze, um Nachhaltigkeit im Design zu vermitteln. Müll wird bisher im Design vornehmlich als ein technologisches Problem behandelt.
126

Optimization of Fast MR Imaging Technologies using the Case-PDM to Quantitatively Assess Image Quality

Miao, Jun 08 March 2013 (has links)
No description available.
127

Real Time Ballistocardiogram Artifact Removal in EEG-fMRI Using Dilated Discrete Hermite Transform

Mahadevan, Anandi January 2008 (has links)
No description available.
128

Measuring Pulse Rate Variability During Motion Artifact with a Non-Contact, Multi-Imager Photoplethysmography System

Kiehl, Zachary Adam 11 May 2015 (has links)
No description available.
129

System Optimization and Patient Translational Motion Correction for Reduction of Artifacts in a Fan-Beam CT Scanner

Wise, Zachary Gordon Lee 19 September 2012 (has links)
No description available.
130

Wetnerk: an invitation to engage with local computer networks through sound

Carlsson, Nicole January 2017 (has links)
This paper presents Wetnerk, a Research through Design portable local computer network sonification artifact designed with a Reflective Design approach. Wetnerk explores how we might sonically engage with local computer network characteristics. The aim is to reveal hidden qualities of a local computer network, normally undetectable by human senses. Specifically Wetnerk attempts to invite people to engage in novel ways with their local area network. It does so by probing the network ports, analyzing the result from an information security perspective and subsequently sonifying the results. A preliminary pilot study indicates that people are so unaware of local computer network characteristics that they have trouble perceiving any of its qualities beyond its mere existence. Wetnerk shows promise in supporting people to critically reflect on and question this low awareness. In some cases curiosity is ignited sparking a desire to further engage with qualities of a local network in more novel ways than the current norm.

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