Zugl.: Hannover, Universiẗat, Diss., 2009.

Thesis (Ph. D.)--School of Pharmacy and Dept. of Chemistry. University of Missouri--Kansas City, 2005. / "A dissertation in pharmaceutical sciences and chemistry." Advisor: Simon H. Friedman. Typescript. Vita. Description based on contents viewed June 23, 2006; title from "catalog record" of the print edition. Includes bibliographical references (leaves 327-353). Online version of the print edition.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Reverse engineering of geometric models is the process of creating a computer aided model from an existing physical part so that subsequent manufacturing processes may be implemented. Applications of reverse engineering can range from the production of molds and dies from wood or clay models to the creation of replacement parts from worn existing machinery. In reverse engineering, both contact and non-contact measurement probes are used to gather measured surface points. However, due to the nature of these instruments, both the direction of the probe during measurement and the conversion of the gathered data to the appropriate computer aided models are currently very difficult. This thesis addresses some of these problems. A stereo vision system employing neural network based image segmentation is implemented to automatically generate probe paths for either a touch trigger probe or an optical laser scanner. A fuzzy logic based iterative geometry fitting algorithm is used to fit geometric primitives to measured surface data. As modern computer aided drafting programs utilise parametric modelling methods and topology information, regarding the association of neighbouring surface patches is determined from the fitted geometric entities. Finally, utilising the extracted geometric and topology information, specific surface features, such as comers, slots and steps are detected using a feed-forward neural network. The computational tools in this thesis provide methods that reduce the time and effort required to geometrically reverse engineer an existing physical object. / Graduate

Indiana University-Purdue University Indianapolis (IUPUI) / Close range, image based photogrammetry and LIDAR laser scanning technique are commonly utilized methodologies to snap real objects.3D models of already existing model or parts can be reconstructed by laser scanning and photogrammetry. These 3D models can be useful in applications like quality inspection, reverse engineering. With these techniques, they have their merits and limitations. Though laser scanners have higher accuracy, they require higher initial investment. Close-range photogrammetry is known for its simplicity, versatility and e ective detection of complex surfaces and 3D measurement of parts. But photogrammetry techniques can be initiated with comparatively much lower initial cost with acceptable accuracy. Currently, many industries are using photogrammetry for reverse engineering, quality inspection purposes. But, for photogrammetric object reconstruction, they are using di erent softwares. Industrial researchers are using commercial/open source codes for reconstruction and another stand-alone software for reverse engineering and mesh deviation analysis. So the problem statement here for this thesis is to integrate Photogrammetry, reverse engineering and deviation analysis to make one state-of-the-art work ow. xx The objectives of this thesis are as follows: 1. Comparative study between available source codes and identify suitable and stable code for integration; understand the photogrammetry methodology of that particular code. 2. To create a taskpane add-in using API for Integration of selected photogrammetry methodology and facilitate methodology with parameters. 3. To demonstrate the photogrammetric work ow followed by a reverse engineering case studies to showcase the potential of integration. 4. Parametric study for number of images vs accuracy 5. Comparison of Scan results, photogrammetry results with actual CAD data

Sulfonated poly(arylene ether sulfone)s are a class of engineering thermoplastics well-known for their mechanical properties and chemical/oxidative stability. The research in this dissertation focuses on modifying the structure of sulfonated poly(arylene ether sulfone)s to improve membrane performance. Blends of a 20% disulfonated poly(arylene ether sulfone) (BPS20) with poly(ethylene glycol) (PEG) were investigated with the objective of promoting water flux across a reverse osmosis membrane. It was considered desirable to investigate poly(arylene ether sulfone)s with a hydroquinone unit that could be controllably post-sulfonated without degradation, providing a polymer with controlled sulfonation through controlling hydroquinone content. It also avoided the disadvantages noted previously in polymers with post-sulfonated biphenol units. Initial experiments focused on determining sulfonation conditions to confirm quantitative sulfonation of the hydroquinone without side reactions or degradation. A polymer with 29 mole % hydroquinone-containing units was used to study the rate of sulfonation. Successful post-sulfonation was confirmed and reaction conditions were applied to a series of polymers with varying hydroquinone comonomer contents. These polymers were sulfonated, characterized and evaluated for transport properties. Of interest was the high sodium rejection in the presence of calcium, which in the directly copolymerized disulfonated materials is compromised. The post-sulfonated poly(arylene ether sulfone)s showed no compromise in sodium rejection in a mixed-feed of sodium chloride and calcium chloride. In the membrane electrolysis of water, Nafion's high permeability to hydrogen, particularly above about 80 C, results in back-diffusion of hydrogen across the membrane. This reduces efficiency, product purity, and long-term electrode stability. Hydrophilic-hydrophobic multiblock copolymers based on disulfonated and non-sulfonated poly(arylene ether sulfone) oligomers feature a lower gas permeability. Various multiblock compositions and casting conditions were investigated and transport properties were characterized. A multiblock poly(arylene ether sulfone) showed a significant improvement in performance over Nafion at 95°C. Multiblock hydrophilic-hydrophobic poly(arylene ether sulfone)s have been extensively investigated as alternatives for proton exchange membrane fuel cells. One concern with these materials is the complicated multi-step synthesis and processing of oligomers, followed by coupling to produce a multiblock copolymer. An streamlined synthetic process was successful for synthesizing membranes with comparable morphologies and performance to a multiblock synthesized via the traditional method. / Ph. D.

Clean water is critical to the safety, security and survivability of humankind. Nearly 41% of the Earth's population lives in water-stressed areas, and water scarcity will be exacerbated by an increasing population. Over 96% of the total water is saline and only 0.8% is accessible fresh water. Thus, saltwater desalination has emerged as the key to tackle the problem of water scarcity. Our current work deals with the membrane process of reverse osmosis. Sulfonated polysulfones are a potential alternative to state-of-the-art thin film polyamides. Synthesized by step growth polymerization, polysulfone membranes have smooth surfaces and they are more chemically resistant relative to polyamides. Previously studied sulfonated polysulfone membranes were synthesized by direct copolymerization of pre-disulfonated comonomer and the sulfonate ions were placed on adjacent rings of bisphenol moiety. This study focuses on placing the sulfonate ions differently along the polysulfone backbone on isolated rings of hydroquinone moiety, and on adjacent rings of biphenol moiety- and its effect on the transport and hydrated mechanical properties of the membranes. Selective post sulfonation of poly(arylene ether sulfone) in mild conditions was also found to be an effective way to strategically place the sulfonate ions along the backbone of the polymer chain without the need to synthesize a new monomer. Hydroquinone based, amine terminated oligomers were synthesized with block molecular weights of 5000 and 10,000 g/mol. They were post-sulfonated and crosslinked at their termini with epoxy reagents. Such crosslinked and linear membranes had sulfonate ions on isolated rings of hydroquinone moiety. Synthesis and kinetics of controlled post-sulfonation of poly(arylene ether sulfones) that contained biphenol units were also reported. The sulfonation reaction proceeded only on the biphenol rings. The linear membranes had sulfonate ions on adjacent rings of biphenol moieties. The tensile measurements were performed on the membranes under fully hydrated conditions. All membranes remained glassy at values of water uptake. It was found that elastic moduli and yield strengths in the hydroquinone- based linear and crosslinked membranes increased with decrease in water uptakes in the membranes. The effect of plasticization of water superseded the effect of block length and degree of sulfonation in the membranes. The highest elastic modulus of 1420 MPa at lowest water uptake of 18% was observed in cross linked membrane with 50% repeat units being sulfonated (50% repeat units contain hydroquinone)and target molecular weight of 5000 g/mol. However, the hydroquinone membranes broke at low strains of < 20%. The hydrated mechanical properties could be improved by replacing the hydroquinone with biphenol moieties. The biphenol based post-sulfonated membrane showed high elastic modulus that was comparable to the hydroquinone-based counterparts at similar values of water uptake. The biphenol based membrane broke at higher strains of >80%. The post-sulfonated membranes- hydroquinone-based linear and crosslinked membranes and biphenol-based linear membranes had better transport properties than the previously studied sulfonated polysulfones that were synthesized by disulfonated comonomers.The post sulfonated hydroquinone-based membranes did not show a compromise in the rejection of monovalent ions in the presence of divalent ions in mixed feed water. The superior properties of the post-sulfonated membranes can potentially be attributed to the kinked backbone that potentially increased the free volume in the membranes and the sulfonate ions were spaced apart to potentially reduce their chelation with calcium (divalent) ions in mixed feed water. Interestingly, the biphenol based post-sulfonated membranes also did not have any compromise in the rejection of monovalent ions in the presence of divalent ions. This was potentially because the sulfonate ions were spaced far apart on the non-planar biphenol rings. / PHD / According to the World Economic Forum, the water crisis has remained one of the top five global risks that has had a huge impact on the society. The world population has tripled in the twentieth century. Close to 2 billion people live in water scarce regions, 1.2 billion people lack access to safe drinking water, 2.6 billion have little or no access to sanitation and countless die due to diseases transmitted through unsafe water. Industrialization and climate change have worsened the water crisis. Furthermore, in today’s economies food, energy and water are inherently linked. Thus, a water crisis can have a cascading effect on availability of food and energy. To obtain an adequate and sustainable supply of water, it is important to improve already existing methods and develop new and inexpensive technologies for water purification. According to the U.S. geological survey over 96% of the earth’s water is saline. Thus, salt water desalination has emerged as the key to tackle the problem of scarcity of potable water. Reverse osmosis is a membrane-based process for water desalination wherein the membrane allows water to pass through while rejecting salts. The membranes are composed of long chain molecules called polymers. The current state of the art polymeric membrane made of polyamides show high rejection of salts with fast permeation of water. However, these membranes can be degraded by the chlorinated disinfectants added to the feed water. An alternative polymeric material, sulfonated polysulfone, can potentially be applied for reverse osmosis as these polymers are resistant to the chlorinated species. These membranes are composed of a polysulfone with sulfonate ions present randomly on the chain. This study investigates the effect of the position of the ions on the polymer chain. It is found that the membranes ability to reject salt from water can be improved by strategically placing the charged species on the polymer chain.

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Die Skelettextraktion ist besonders in der Formanalyse ein wichtiges Werkzeug. Im Rahmen des Forschungsprojektes ’Extraktion fertigungsrelevanter Merkmale aus 3D-Daten umformtechnischer Bauteile zur featurebasierten Fertigungsprozessgestaltung’ als Kooperationsprojekt zwischen der Professur Graphische Datenverarbeitung und Visualisierung an der Technischen Universität Chemnitz und des Fraunhofer-Institut für Werkzeugmaschinen und Umformtechnik Chemnitz wurde diese zur Featureerkennung umgesetzt. Dieses Dokument gibt zunächst Einblick in grundlegende Verfahren und Problemstellungen einer solchen Extraktion. Die Ergebnisse mehrerer Forschungsschwerpunkte, die sich aus den zu untersuchenden Massivumformteilen ergaben, werden vorgestellt. Hierbei besonders interessant ist die robuste Extraktion von Kurvenskeletten bei Bauteilen mit nicht-zylindrischer Hauptform, sowie bei Bauteilen mit Nebenformelementen. Desweiteren werden Nachverarbeitung und Auswertung des Kurvenskeletts, sowie verwandte Forschungsarbeiten und -ergebnisse diskutiert.

Many people still confused and misunderstand the differences between auction types: In fact, we have only two major types of auctions which are the forward auction and Reverse auction[22]. In a forward auction a single seller offers an item for sale with many competitive buyers driving the price upward: In a Reverse Auction, a single buyer wants to purchase a service or an item from many sellers, they drive the price downward: There are many differences between these type of auction: Including the progress of the auctions; winner selection criterion and other factors: The Reverse Auction nowadays is one of the most preferred types of online auctions: It gains popularity rapidly because of representing the buyers' side and helps him to drive prices down in contrary with the forward auction or traditional auction. The aim of this study is to identify the most common types of the Reverse auctions and compare them to one another to determine when should be used by a buyer and propose the most efficient implementation model for some types: The results of this study are: achieve a written report and a small demonstrator model on how to implement English Auction and Second-Sealed bid Auction.