Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 205-213).

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography; leaves 382-394.

Thesis (Ph. D.)--Oregon Graduate Center, 1985.

Image noise in Positron Emission Tomography (PET) is the result of statistical fluctuation in projection data. The variance properties of images obtained with the UBC/TRIUMF PETT VI tomograph are studied by analytical methods, computer simulations, and phantom experiments. The PETT VI image reconstruction algorithm is described and analyzed for noise propagation properties. Procedures for estimating both point-wise (pixel) and region of interest (ROI) variances are developed: these include the effects of corrections for non-uniform sampling, detector efficiency variation, object self-attenuation and random coincidences. The analytical expression for image-plane variance is used in computer simulations to isolate the effects of the various data corrections: It is shown that the image precision is degraded due to non-uniform sampling of the projections. The RMS noise is found to be increased by 9% due to the wobble motion employed in PETT VI. Analytical predictions for both pixel and ROI variances are verified with phantom experiments. The average error between measured and predicted ROI variances due to noise in emission data for a set of seven regions placed on a 20 cm cylindrical phantom is 9.5%. Images showing variance distributions due to noise in emission data and due to noise in transmission data are produced from human subject brain scan data collected by the UBC/TRIUMF PET group. The maximum ratio of image variance due to noise in transmission data to that due to noise in emission data is calculated as 2.6 for a typical FDG study, and 0.082 for a typical fluorodopa study. Total RMS noise varies between 0.4% and 11.6% for a typical set of ROI's placed on mid-brain slices reconstructed from these data sets. Procedures are suggested for improving the statistical accuracy of quantitative PET measurements. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Thesis (Ph. D.)--University of Chicago, August 1999. / Includes bibliographical references. Also available on the Internet.

Fung Yun Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 134-140). / Abstracts in English and Chinese. / Abstract --- p.I / Acknowledgement --- p.III / Contents --- p.IV / List of Figure captions --- p.VIII / List of Table captions --- p.XIII / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Theory and Applications / Chapter 2.1 --- Principle of field emission / Chapter 2.1.1 --- The Fowler-Nordheim Theory --- p.3 / Chapter 2.1.2 --- Field emission from metals --- p.6 / Chapter 2.1.3 --- Field emission from semiconductors --- p.8 / Chapter 2.1.3.1 --- Advantages and limitations of silicon --- p.9 / Chapter 2.1.4 --- Application of the Fowler-Nordheim theory --- p.10 / Chapter 2.1.5 --- Factors influencing field emission efficiency --- p.11 / Chapter 2.2 --- Applications --- p.11 / Chapter 2.2.1 --- Operation of a Field Emission Displays --- p.11 / Chapter 2.2.2 --- Basic structure of a Field Emission Displays --- p.13 / Chapter 2.2.3 --- Parameters relevant to applications --- p.15 / Chapter 2.3 --- The fabrication processes --- p.17 / Chapter 2.3.1 --- The anisotropic wet etching method --- p.18 / Chapter 2.3.2 --- The isotropic wet etching method --- p.19 / Chapter 2.3.3 --- Field emission from coating materials --- p.20 / Chapter 2.3.3.1 --- Coating enhancement --- p.20 / Chapter 2.3.3.2 --- Diamond and diamond-like films --- p.21 / Chapter 2.3.3.3 --- Metallic coatings --- p.22 / Chapter 2.3.3.4 --- Porous silicon coatings --- p.22 / Chapter 2.3.3.5 --- Silicon carbide coatings --- p.22 / Chapter 2.3.4 --- Fabrication of field emitters with gate --- p.23 / Chapter Chapter 3 --- Sample Preparation and Characterization Methods / Chapter 3.1 --- Sample preparation --- p.25 / Chapter 3.2 --- The fabrication process / Chapter 3.2.1 --- Isotropic etching of silicon / Chapter 3.2.1.1 --- The anodization process --- p.25 / Chapter 3.2.1.2 --- Porous silicon formation --- p.26 / Chapter 3.2.2 --- Anistropic etching of silicon --- p.27 / Chapter 3.2.3 --- The sputtering system --- p.28 / Chapter 3.2.4 --- The MEVVA Ion Source Implanter --- p.30 / Chapter 3.3 --- Characterization Methods / Chapter 3.3.1 --- Atomic Force Microscopy (AFM) --- p.32 / Chapter 3.3.2 --- Scanning Electron Microscopy (SEM) --- p.34 / Chapter 3.3.3 --- Field emission measurement / Chapter 3.3.3.1 --- Vacuum requirements --- p.35 / Chapter 3.3.3.2 --- Testing system / Chapter 3.3.3.3 --- Fluctuation of field emission --- p.38 / Chapter Chapter 4 --- Fabrication of Silicon Tips and their field emission charateristics / Chapter 4.1 --- The anodization etching process / Chapter 4.1.1 --- Introduction --- p.40 / Chapter 4.1.2 --- Experimental details --- p.42 / Chapter 4.1.3 --- Results and Discussions / Chapter 4.1.3.1 --- N type (100) sample --- p.45 / Chapter 4.1.3.2 --- Ntype(lll) sample --- p.60 / Chapter 4.1.3.3 --- Fluctuations of the emission current --- p.64 / Chapter 4.1.3.4 --- The effect of Concentration of HF solution on First Step Anodization --- p.68 / Chapter 4.1.3.5 --- The effect of the Concentration of HF solution on Second Step Anodization --- p.70 / Chapter 4.1.3.6 --- Gated silicon field emitter --- p.70 / Chapter 4.1.4 --- Conclusions --- p.73 / Chapter 4.2 --- Anisotropic texturing process / Chapter 4.2.1 --- Introduction --- p.74 / Chapter 4.2.2 --- Experimental details --- p.76 / Chapter 4.2.3 --- Results and Discussions --- p.78 / Chapter 4.2.4 --- Conclusion --- p.92 / Chapter 4.3 --- Formation of Porous Silicon Layer on silicon / Chapter 4.3.1 --- Introduction --- p.93 / Chapter 4.3.2 --- Experimental details --- p.94 / Chapter 4.3.3 --- Results and Discussions --- p.95 / Chapter 4.3.4 --- Conclusion --- p.100 / Chapter 4.4 --- Chapter Summary --- p.101 / Chapter Chapter 5 --- Improvement in the field emission characteristics of the silicon tips upon coating with low work function materials / Chapter 5.1 --- Amorphous carbon coating / Chapter 5.1.1 --- Introduction --- p.102 / Chapter 5.1.2 --- Experimental details --- p.103 / Chapter 5.1.3 --- Results and Discussions --- p.104 / Chapter 5.1.4 --- Conclusion --- p.118 / Chapter 5.2 --- Silicon carbide coated Silicon emitter by MEWA / Chapter 5.2.1 --- Introduction --- p.119 / Chapter 5.2.2 --- Experimental details --- p.120 / Chapter 5.2.3 --- Results and Discussions --- p.121 / Chapter 5.2.4 --- Conclusion --- p.125 / Chapter 5.3 --- Chapter Summary --- p.126 / Chapter Chapter 6 --- Conclusions --- p.127 / Reference --- p.134 / List of publications --- p.140

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This thesis is part of a bigger project, ORTO - roughly translated to optimized resource efficient manufacturing of orthoses. During the manufacturing of orthopedic aids many different methods are used to manufacture individually adjusted products. Processes, methods and material may vary depending on what end product is going to be produced. The knowledge of how the manufacturing affects the employees long term is not complete from a health-oriented perspective. The purpose of this thesis is to map out the manufacturing processes for rigid and hinged molded ankle-foot orthoses made primarily from carbon fibre composite. This will then be used to identify the potential sources of exposure of hazardous materials that can lead to health issues. To answer the problem statements theory about process mapping has been gathered and observations in the shape of video recordings have been done at Borås Orthotics to map out the current situation, in addition to interviews. The purpose of the process mapping was also to identify potential sources of emission where exposure to hazardous materials was evident. Theory and research about these materials has been gathered about the potential health issues. The exposure times from the sources of emissions has been compiled from the video recordings, where it was deemed to be four possible sources, in the form of dry carbon fibre bands, casting with poly methyl methacrylate, sanding and gluing. The exposure times and the sources of emission has been analyzed and compared with theory and research to investigate if there was any possible health hazards. The discussion has most importantly been about how the manufacturing of hazardous materials can affect the employees in terms of health and how the exposure times can be reduced. The conclusion is that certain sources of emissions run a greater risk to affect the employees negatively and certain measures might be in order to in terms of changing how the work is performed. It might be worth some reconstruction to make the work place safer in addition to reviewing certain methods. In general the regulations are a good idea to abide by since they are intended to prevent exposure for employees that work materials such as carbon fibers. Other practical suggestions of how to reduce the exposure to hazardous materials are included. An example of this could be to install a mirror solution in the fume cupboard at the casting process or to look at the routines and the work methods applied at the sanding process. The regulations should also be compared to how the work is currently performed and applied according to the work environment regulations. / Examensarbetet är en del i ett större projekt, ORTO - Optimerad Resurseffektiv Tillverkning av Ortoser. Vid tillverkning av ortopedtekniska hjälpmedel används idag många olika metoder för att tillverka individanpassade produkter. Processer, metoder och material kan variera beroende på vilken slutprodukt det är som ska tillverkas. Det finns ingen fullständig kunskap om hur detta påverkar personalen som tillverkar hjälpmedlen och användare på lång sikt ur ett hälsomässigt perspektiv. Syftet med arbetet var att kartlägga tillverkningsprocesserna för ledade och oledade gjutna ankel-fot-ortoser som är gjorda framförallt av kolfiberkompositmaterial, för att identifiera exponeringen av farliga material och ämnen som kan leda till eventuella hälsoproblem. För att besvara frågeställningarna har teori om processkartläggning samlats in och observationer i form av videoinspelningar och intervjuer har utförts på Borås Ortopedteknik för att kartlägga nuläget. Processkartläggningen syfte var också att identifiera potentiella emissionskällor där exponering för farligt material förekom. Teori och forskning om dessa material har samlats in om dess potentiella hälsopåverkan. Exponeringstiderna vid emissionskällorna har sammanställts genom videoinspelningarna, där det i nuläget bedömdes finnas fyra stycken emissionskällor i form av torra kolfiberband, gjutning med polymetylmetakrylat, slipning och limning. Exponeringstiderna och emissionskällorna har analyserats och jämförts med teori och forskning för att granska om det var någon hälsorisk. Diskussionen har framförallt handlat om hur bearbetningen av farliga material kan komma att påverka personalen som tillverkar hjälpmedlen hälsomässigt och hur exponeringstiderna kan reduceras. Slutsatsen är att vissa emissionskällor löper större risk att påverka personalen negativt och åtgärder i form av nya arbetssätt och metoder eller ombyggnationer kan vara av värde att analysera vidare. Även förebyggande åtgärder som att följa föreskrifter skulle vara aktuellt för att minska exponeringen av farliga material. Praktiska förslag ges på vad som skulle kunna förändras. Exempel på detta kan vara att installera en spegellösning i dragskåpet vid gjutningen eller att se över rutiner och arbetssätt vid slipningen och att följa föreskrifterna från arbetsmiljöverket.