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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.
1

A monument to the flaws

Larsdotter Persson, Moa January 2019 (has links)
My work is a tribute to the disintegration of built environments, and the chaos and disturbance that it brings into the idea of what a city should look like. An ode to the ruins that are witnesses to destructive social and economic systems and that tell the stories of the life that once inhabited them. A comment and critique on humanities way of ruining everything: world that we live in and our self; a destructive behaviour that we refuse to admit we have, and desperately try to hide. We polish the façades and fake our appearance in order to keep the illusion. I am discussing the concept of ruin romanticism, comparing the garden ruins of the eighteenth century to the urban exploration of abandoned places of modern society, the fascination for what once was, but are no more and the different feelings these places might arouse. I describe how I through experiments with dying, deconstructed screen printing and distressing, manipulate fabrics to create an illusion of brick walls. And how I through experiments with display, sound and light explore solutions for creating the dystopic atmosphere of abandoned places in a textile installation. My biggest inspiration is the inevitable downfallof the urban landscape and I am romanticising the imperfections and the flaws. I take what is understood as ugly by the rules of aesthetics, make it beautiful, and put it on a pedestal.
2

A Plastic-Based Thick-Film Li-Ion Microbattery for Autonomous Microsensors

Lin, Qian 17 February 2006 (has links) (PDF)
This dissertation describes the development of a high-power, plastic-based, thick-film lithium-ion microbattery for use in a hybrid micropower system for autonomous microsensors. A composite porous electrode structure and a liquid state electrolyte were implemented in the microbatteries to achieve the high power capability and energy density. The use of single-walled carbon nanotubes (SWNTs) was found to significantly reduce the measured resistance of the cathodes that use LiAl0.14Mn1.86O4 as active materials, increase active material accessibility, and improve the cycling and power performance without the need of compression. Optimized uncompressed macro cathodes were capable of delivering power densities greater than 50 mW/cm2, adequate to meet the peak power needs of the targeted microsystems. The anodes used mesocarbon microbeads (MCMB) with multi-walled carbon nanotubes (MWNTs) and had significantly better power performance than the cathodes. The thick-film microbattery was successfully fabricated using techniques compatible with microelectronic fabrication processes. A Cyclic Olefin Copolymer (COC)-film was used as both the substrate and primary sealing materials, and patterned metal foils were used as the current collectors. A liquid-state electrolyte and Celgard separator films were used in the microbatteries. These microbatteries had electrode areas of c.a. 2 mm x 2 mm, and nominal capacities of 0.025-0.04 mAh/cell (0.63-1.0 mAh/cm2, corresponding to an energy density of ~6.3-10.1 J/cm2). These COC-based batteries were able to deliver constant currents up to 20 mA/cm2 (100% depth of discharge, corresponding to a power density of 56 mW/cm2 at 2.8 V) and pulse currents up to 40 mA/cm2 (corresponding to a power density of 110 mW/cm2). The high power capability, small size, and high energy density of these batteries should make them suitable for the hybrid micropower systems; and the flexible plastic substrate is also likely to afford some unique integration possibilities for autonomous microsystems. The mechanism by which the SWNTs improved the rate performance of composite cathodes was studied both experimentally and theoretically. It was concluded that the use of SWNT improved cathode performance by improving the electronic contacts to active material particles, which consequently improved the accessibility of these particles and improved the rate capability of the composite cathodes.
3

A Layered Whole

Sturniolo, Rebecca Lynn 28 August 2019 (has links)
a series of sectional graphics are created to represent the architectural whole. this thesis is about how a three dimensional architecture is seen and perceived through use of two dimensional graphics. it is about understanding a finished work [the whole] by viewing its individual sectional layers [the parts]. a whole does not exist without its parts, just as architecture would not exist without section. in this case, the section is raised above all other things in order to see the potential of the whole. / Master of Architecture
4

Screen and stencil print technologies for industrial N-type silicon solar cells

Edwards, Matthew Bruce, ARC Centre of Excellence in Advanced Silicon Photovoltaics & Photonics, Faculty of Engineering, UNSW January 2008 (has links)
To ensure that photovoltaics contributes significantly to future world energy production, the cost per watt of producing solar cells needs to be drastically reduced. The use of n-type silicon wafers in conjunction with industrial print technology has the potential to lower the cost per watt of solar cells. The use of n-type silicon is expected to allow the use of cheaper Cz substrates, without a corresponding loss in device efficiency. Printed metallisation is well utilised by the PV industry due to its low cost, yet there are few examples of its application to n-type solar cells. This thesis explores the use of n-type Cz silicon with printed metallisation and diffusion from printed sources in creating industrially applicable solar cell structures. The thesis begins with an overview of existing n-type solar cell structures, previous printed thick film metallisation research and previous research into printed dopant sources. A study of printed thick-film metallisation for n-type solar cells is then presented, which details the fabrication of boron doped p-type emitters followed by a survey of thick film Ag, Al, and Ag/Al inks for making contact to a p-emitter layer. Drawbacks of the various inks include high contact resistance, low metal conductivity or both. A cofire regime for front and rear contacts is established and an optimal emitter selected. A study of printed dopant pastes is presented, with an objective to achieve selective, heavily doped regions under metal contacts without significantly compromising minority carrier lifetime in solar cells. It is found that heavily doped regions are achievable with both boron and phosphorus, but that only phosphorus paste was capable of post-processing lifetime compatible with good efficiencies. The effect of belt furnace processing on n-type silicon wafers is explored, with large losses in implied voltage observed due to contamination of Si wafers from transition metals present in the belt furnace. Due to exposure to chromium in the belt furnace, no significant advantage in using n-type wafers instead of p-type is observed during the belt furnace processing step. Finally, working solar cells with efficiencies up to 16.1% are fabricated utilising knowledge acquired in the earlier chapters. The solar cells are characterised using several new photoluminescence techniques, including photoluminescence with current extraction to measure the quality of metal contacts. The work in this thesis indicates that n-type printed silicon solar cell technology shows potential for good performance at low cost.
5

Screen and stencil print technologies for industrial N-type silicon solar cells

Edwards, Matthew Bruce, ARC Centre of Excellence in Advanced Silicon Photovoltaics & Photonics, Faculty of Engineering, UNSW January 2008 (has links)
To ensure that photovoltaics contributes significantly to future world energy production, the cost per watt of producing solar cells needs to be drastically reduced. The use of n-type silicon wafers in conjunction with industrial print technology has the potential to lower the cost per watt of solar cells. The use of n-type silicon is expected to allow the use of cheaper Cz substrates, without a corresponding loss in device efficiency. Printed metallisation is well utilised by the PV industry due to its low cost, yet there are few examples of its application to n-type solar cells. This thesis explores the use of n-type Cz silicon with printed metallisation and diffusion from printed sources in creating industrially applicable solar cell structures. The thesis begins with an overview of existing n-type solar cell structures, previous printed thick film metallisation research and previous research into printed dopant sources. A study of printed thick-film metallisation for n-type solar cells is then presented, which details the fabrication of boron doped p-type emitters followed by a survey of thick film Ag, Al, and Ag/Al inks for making contact to a p-emitter layer. Drawbacks of the various inks include high contact resistance, low metal conductivity or both. A cofire regime for front and rear contacts is established and an optimal emitter selected. A study of printed dopant pastes is presented, with an objective to achieve selective, heavily doped regions under metal contacts without significantly compromising minority carrier lifetime in solar cells. It is found that heavily doped regions are achievable with both boron and phosphorus, but that only phosphorus paste was capable of post-processing lifetime compatible with good efficiencies. The effect of belt furnace processing on n-type silicon wafers is explored, with large losses in implied voltage observed due to contamination of Si wafers from transition metals present in the belt furnace. Due to exposure to chromium in the belt furnace, no significant advantage in using n-type wafers instead of p-type is observed during the belt furnace processing step. Finally, working solar cells with efficiencies up to 16.1% are fabricated utilising knowledge acquired in the earlier chapters. The solar cells are characterised using several new photoluminescence techniques, including photoluminescence with current extraction to measure the quality of metal contacts. The work in this thesis indicates that n-type printed silicon solar cell technology shows potential for good performance at low cost.
6

Plain Print : a surface pattern collection screen printed with natural dye

Hüls, Lisa January 2021 (has links)
The interest for natural dye has increased together with the concern in sustainability and environmental awareness within the textile industry. Natural dye is one of the oldest techniques when it comes to textile production, but when synthetic dyestuffs were discovered, the usage of the technique decreased. Today, the technique is slowly coming back together with the awareness in sustainability. However, regarding surface patterns, the expression is quite limited, and patterns are created by dyeing techniques, muted colors and nature as an obvious inspiration. This degree work explores natural dye print by designing a screen printed surface pattern collection, and the project advocates for and is an addition to the field of natural dye print. The methods used were drawing, digital sketching and screen printing. The methods of designing were done through practical workshops, both for sketching patterns and to explore techniques within natural dye print. The female body is a design theme in the work and the intention is simply to portray the body as it is. The motive has not been chosen to provoke, to address a political issue or to evoke discussion. The result is three surface patterns printed with different printing techniques on different fibers. A significant part of the result is the reference library containing all the printed samples and can be used for further research within the field. Choice of fabric and scale of design was done with fashion fabric in mind, however, to focus on the design and technique the designs are not presented on any kind of product. Tests were done to try out the light fastness of the different colorants on different fibers. This project has expanded the field of natural dye print by adding a screen printed surface pattern collection with thematic patterns and an expression that does not reveal the use of natural dye. The project also resulted in a steppingstone for further work within the field.
7

A comparison of catalyst application techniques for membrane electrode assemblies in SO2 depolarized electrolysers / Dreyer H.M.E.

Dreyer, Herbert Morgan Evans January 2011 (has links)
Hydrogen production via the electrolysis of water has gained a lot of attention in the last couple of years. Research related to electrolysers is mostly aimed towards decreasing the noble–metal catalyst content. In this study the presently used catalyst application techniques were reviewed and critically examined to find commercially applicable and effective methods. Selected methods were then practically applied to determine their feasibility and to gain “know–how” related to the practical application of these techniques. The selected techniques were the hand paint, inkjet print, screen print and spray paint techniques. Meaningful comparisons were made between the methods in terms of parameters such as practicality, waste of catalyst and microstructure. The results point out that the hand paint and spray paint methods are feasible methods although there are improvements to be made. The hand paint method was improved by applying a carbon micro porous layer to the gas diffusion layer before the painting is carried out. The addition of the carbon layer reduced the soaking of the catalyst–containing ink through the gas diffusion layer. A method not initially investigated was identified an evaluated and showed promising results in lowering the mass of catalyst applied. This method comprised of sputtering a layer of catalyst material onto a prepared gas diffusion layer. It also came to light from the results that electrodes, and therefore membrane electrode assemblies, can be produced at a much lower cost than the commercial available membrane electrode assemblies. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.
8

A comparison of catalyst application techniques for membrane electrode assemblies in SO2 depolarized electrolysers / Dreyer H.M.E.

Dreyer, Herbert Morgan Evans January 2011 (has links)
Hydrogen production via the electrolysis of water has gained a lot of attention in the last couple of years. Research related to electrolysers is mostly aimed towards decreasing the noble–metal catalyst content. In this study the presently used catalyst application techniques were reviewed and critically examined to find commercially applicable and effective methods. Selected methods were then practically applied to determine their feasibility and to gain “know–how” related to the practical application of these techniques. The selected techniques were the hand paint, inkjet print, screen print and spray paint techniques. Meaningful comparisons were made between the methods in terms of parameters such as practicality, waste of catalyst and microstructure. The results point out that the hand paint and spray paint methods are feasible methods although there are improvements to be made. The hand paint method was improved by applying a carbon micro porous layer to the gas diffusion layer before the painting is carried out. The addition of the carbon layer reduced the soaking of the catalyst–containing ink through the gas diffusion layer. A method not initially investigated was identified an evaluated and showed promising results in lowering the mass of catalyst applied. This method comprised of sputtering a layer of catalyst material onto a prepared gas diffusion layer. It also came to light from the results that electrodes, and therefore membrane electrode assemblies, can be produced at a much lower cost than the commercial available membrane electrode assemblies. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.

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