It is well established that acquiring large amounts of range data with vision sensors can quickly lead to important data management challenges where processing capabilities become saturated and pre-empt full usage of the information available for autonomous systems to make educated decisions. While sub-sampling offers a naïve solution for reducing dataset dimension after acquisition, it does not capitalize on the knowledge available in already acquired data to selectively and dynamically drive the acquisition process over the most significant regions in a scene, the latter being generally characterized by variations in depth and surface shape in the context of 3D imaging. This thesis discusses the development of two formal improvement measures, the first based upon surface meshes and Ordinary Kriging that focuses on improving scene accuracy, and the second based upon probabilistic occupancy grids that focuses on improving scene coverage. Furthermore, three selection processes to automatically choose which locations within the field of view of a range sensor to acquire next are proposed based upon the two formal improvement measures. The first two selection processes each use only one of the proposed improvement measures. The third selection process combines both improvement measures in order to counterbalance the parameters of the accuracy of knowledge about the scene and the coverage of the scene. The proposed algorithms mainly target applications using random access range sensors, defined as sensors that can acquire depth measurements at a specified location within their field of view. Additionally, the algorithms are applicable to the case of estimating the improvement and point selection from within a single point of view, with the purpose of guiding the random access sensor to locations it can acquire. However, the framework is developed to be independent of the range sensing technology used, and is validated with range data of several scenes acquired from many different sensors employing various sensing technologies and configurations. Furthermore, the experimental results of the proposed selection processes are compared against those produced by a random sampling process, as well as a neural gas selective sensing algorithm.

A study of thermal, structural, electrical and optical characteristics of molybdenum black surface coatings on various substrates has been made. The suitability of these coatings for use as selective absorbers for solar collector applications has been assessed. Molybdenum black (Mo black) coatings were prepared by electrodeposition (on aluminium) and a chemcial conversion method (on zinc and electroplated cobalt on nickel plated copper substrates). The solar absorptancer (αs) and thermal emittances (εth) of the coatings were determined from room temperature spectral reflectance measurements in the solar (0.3 to 2.5μm) and infrared regions (2.5 to 50 μm) respectively. The effect of different preparation parameters and substrate pretreatments on the spectral selectivity has been investigated in order to optimize the thermal performance. The spectral selectivity is related to the Mo-black coating thickness and surface roughness together with the microstructure, of the substrate and the intermediate layer. Dip coatings on polished zinc have significant selectivity (αs/ εth = 8.4 when αs = 0.76). The absorptance of the dip coatings is increased to 0.87 with εth = 0.13 by chemical etching of zinc prior to coating deposition. For coatings on electroplated cobalt on nickel plated copper (cobalt (NC) substrate), an absorptance as high as 0.94 has been obtained with an emittance value 0.3. By using an addition agent in the plating solution of cobalt the high emittance can be reduced to 0.1 with αs = 0.91 giving a coating with a relatively high efficiency (82.5%) for photo-thermal energy conversion. A study of the surface composition and microstructure of the coatings has been made using scanning and transmission electron microscopy together with electron diffraction, X-ray diffraction and X-ray photoelectron spectroscopy. The structural investigations indicate that Mo-black coatings contain polycrystals of orthorhombic Mo4O11 with a small proportion of Ni(OH)2. Presence of water and also Mo4O11 in the coatings are evident from IR spectroscopy study. The bandgap of the coating has been determined from optical transmission spectra (1.66 eV) and also from reflectance spectra (0.85 eV). The discrepancy between these two values has been discussed. The refractive indices of the coatings have also been estimated. The band gaps and refractive indices are found to be related to the spectral selectivity of the coatings. The durability test of the coatings shows that the coatings on etched zinc are more resistant to heat treatment than the coatings on unetched zinc. The coatings on cobalt (NC) substrates also show good stability for relatively short periods at temperatures ~400ºC. A study of the electrical properties of Mo-black coatings suggests that at electrical field strengths (greater than 106v/m the dominant conduction process is of the Poole-Frenkel type. The activation energy of the conduction process has been estimated to be -0.56 eV at higher temperatures. The effect of heat treatment on the electrical properties of the coatings has been examined. The dielectric constant of Mo-black has been estimated from A. C. measurements. At high frequency (20 kHz) the value of the dielectric constant is about 4.0.

Das Spurengas Lachgas (N₂O) trägt zur Klimaerwärmung und Zerstörung der Ozonschicht in der Atmosphäre bei. Mit einem Anteil von ca. 70% sind landwirtschaftliche Böden weltweit Hauptverursacher der hohen anthropogenenN₂O Emissionen. N₂O entsteht in Böden durch verschiedene mikrobiologische Prozesse, bei denen N₂O unter anderem aus düngerbürtigem N gebildet wird. Die Entwicklung effektiver Minderungsmaßnahmen wird erst möglich, wenn ein Verständnis der N₂O Quellprozesse und ihrer Dynamik in Böden vorhanden ist. In dieser Studie wurde die Denitrifikation als ein Quellprozess untersucht, der zusammen mit Nitrifikation und Nitrifizierer-Denitrifikation hauptsächlich für die N₂O Emissionen aus Böden verantwortlich ist. Die Denitrifikation beschreibt die Reduktion von Nitrat (NO₃^-) zu N2, wobei Nitrit (NO₂^-), Stickstoffmonoxid (NO) und N₂O Zwischenprodukte dieses Reaktionsweges sind. Lange Zeit galten heterotrophe Bakterien als alleinige Verursacher von N₂O Emissionen aus der Denitrifikation. Im Jahr 1972 wurde allerdings in Versuchen mit Pilzreinkulturen nachgewiesen, dass auch Pilze in der Lage sind, N₂O über die Denitrifikation zu bilden. Zwei Jahrzehnte später wurde gezeigt, dass den meisten Pilzen das Enzym N₂O-Reduktase fehlt. Somit ist nicht N₂, sondern N₂O das hauptsächliche Endprodukt der pilzlichen Denitrifikation. Dies lässt vermuten, dass die Bildung von N₂O durch pilzliche Denitrifikation noch unterschätzt wird, vorausgesetzt Pilze und Bakterien haben ähnliche Prozessraten. Bisher wurde jedoch nicht ausgiebig erforscht, welchen Anteil die einzelnen mikrobiellen Gemeinschaften an der N₂O Bildung tatsächlich haben. Zur Unterscheidung der N₂O Bildungsprozesse in Bezug auf die beteiligten Mikroorganismen stellt die Isotopenanalyse von N₂O eine vielversprechende Anwendung dar. Vor allem die ¹⁵N-Positionspräferenz im N₂O (SP = site preference, d.h. die Differenz zwischen den δ¹⁵N-Werten der außenständigen und zentralen N-Atome im linearen N₂O-Molekül) aus der Denitrifikation zeigte starke Unterschiede zwischen Reinkulturen einiger Bakterien (SP = -11 bis 0 ‰) und zwei untersuchten Pilzen (SP ~ 37 ‰). Jedoch wurden Bakterienreinkulturen bisher ausgiebiger untersucht als Pilzreinkulturen, auch wenn bekannt ist, dass sich die beteiligten Enzyme bei der Denitrifikation, bis auf die NO-Reduktase, zwischen Bakterien und Pilzen nicht unterscheiden. Die verschiedenen NO-Reduktasen sind vermutlich die Ursache für die unterschiedlichen SP-Werte des von Pilzen und Bakterien produzierten N₂O. Des Weiteren wurde bei Bakterien ein Austausch der Sauerstoffatome von Zwischenprodukten der Denitrifikation und dem umgebenden Wasser gefunden, der zwischen 4 und 100% beträgt. Ob es einen solchen Sauerstoffaustausch auch bei Pilzen gibt, ist bisher jedoch unerforscht. Würde der Sauerstoffaustausch bei pilzlicher Denitrifikation nicht erfolgen, ermöglichte dies neben der unterschiedlichen SP eine weitere Unterscheidung der Herkunft des N₂O. Der Sauerstoffaustausch würde signifikante Unterschiede in der O Isotopensignatur im N₂O pilzlicher bzw. bakterieller Herkunft verursachen. In der vorliegenden Studie, die Aufschluss über die pilzliche N₂O Produktion aus der Denitrifikation geben soll, wurden drei Hauptthemen behandelt. In einem Isotopen-Tracerexperiment mit <up>18</sup>O-angereichertem Wasser wurde untersucht, ob bei sechs Pilzreinkulturen ein Sauerstoffaustausch zwischen Wasser und Zwischenprodukten der Denitrifikation stattfindet. Die Pilzreinkulturen zeigten tatsächlich durch Inkorporation von ¹⁸O aus Wasser in N₂O einen Sauerstoffaustausch. Auch Pilze können bis zu 100% des O während der Denitrifikation austauschen. Eine Unterscheidung zwischen der Denitrifikation durch Bakterien und Pilze anhand der Sauerstoffsignatur ist somit nicht möglich. Das zweite Thema sollte Auskunft darüber geben, ob hohe SP-Werte des N₂O aus der Denitrifikation bei Pilzreinkulturen allgemeingültig sind. Neben den zwei bisher untersuchten wurden vier weitere Pilzreinkulturen inkubiert. Diese Studie zeigte für die getesteten Pilzarten ebenfalls höhere SP-Werte (SP = 19.7 bis 32.6 ‰) im Vergleich zum Wertebereich von Bakterienreinkulturen. Basierend auf den Ergebnissen zum Sauerstoffaustausch aus dem Isotopen-Tracerexperiment wurde für die jeweiligen sechs Pilze, anhand der im Rahmen dieses Versuchs ermittelten natürlichen Sauerstoffisotopensignaturen, Mechanismen zur O Isotopenfraktionierung untersucht. Dafür wurden, neben den Werten des Sauerstoffaustausches und der natürlichen O Isotopensignatur der Pilzreinkulturen, Werte für Fraktionierungseffekte aus der Literatur in einem Isotopenfraktionierungsmodell angewendet, um die Beteiligung der verschiedenen Enzyme, die während der Denitrifikation an dem Sauerstoffaustausch beteiligt sind, abzuschätzen. Im Vergleich zu den NO₃^-- und NO-Reduktasen wies die N₂O^--Reduktase einen maßgeblich höheren Sauerstoffaustausch auf. Die Erkenntnisse aus den Experimenten mit den Pilzereinkulturen sollten im Rahmen des dritten Themas auf Ihre Übertragbarkeit auf die mikrobiellen Gemeinschaften in Böden untersucht werden, indem Bodeninkubationsversuche mit selektiver Hemmung der Organismengruppen (Pilze und Bakterien) durchgeführt wurden. Bei dieser Modifizierung der Methode zur Substrat-induzierten Respiration mit selektiver Hemmung (SIRIN) sollte untersucht werden, ob sich die spezifischen SP-Werte für Bakterien und Pilze nach selektiver Wachstumshemmung von Bodengemeinschaften durch spezifische Antibiotika nachweisen lassen. Die Ausprägung des Hemmungseffekts auf SP-Werte in den drei getesteten Böden entsprach nicht den Erwartungswerten, die sich aus den SP-Werten der Pilz- und Bakterienreinkulturen ergaben. Die ermittelten SP-Werte lagen in den meisten Fällen im Bereich jener bakterieller Reinkulturen und eine Hemmung der Bakterien führte in keinem Fall zu der erwarteten Veränderungen der SP-Werte. Folglich konnten die SP-Werte dieser Versuche nicht dazu dienen, die N₂O Bildung in den gehemmten Varianten den verschiedenen Organismengruppen zu zuordnen. Ungeklärt blieb, ob dies durch fehlende Eignung der modifizierten SIRIN-Methode zu erklären ist, oder ob die an Reinkulturen beobachteten SP-Unterschiede zwischen Pilzen und Bakterien nicht auf mikrobielle Gemeinschaften der Versuchsböden übertragbar sind. Im Hinblick auf nach wie vor bestehende methodische Defizite bei der Untersuchung der Pilzdenitrifikation im Boden sollte dies in weitergehenden Studien geklärt werden.

The purpose of this study is to analyze how university students, who are not members of a political party, experiencing existing selective and collective incentives for involvement in a political party. Furthermore, the study will highlight incentives which could help the political parties to increase their membership. The study is based on seven interviews and the respondents were selected after conducting a survey of students’ political involvement. The interviews were analyzed through the theory of selective and collective incentives.  The study shows that the incentives, both selective and collective, for involvement in a political party in general are weak and that the costs in terms of time, money and education are seen as too high. The respondents have a range of suggestions to increase party involvement, including increased party information, better education, increased financial incentives and a more active membership recruitment. The respondents also highlight some collective incentives such as an increased ideological focus and a greater focus on the political party´s own politics. The collective incentives are harder to achieve though they might be most vital for increased involvement. A common feeling amongst the respondents is that they are inclined to become involved in politics if they feel a change is vital for society.

The potential application of a hydrogel-based strong anion-exchange (Q) membrane to purify plasmid DNAs was evaluated. The maximum binding capacity of plasmid DNA was estimated to be 12.4 mg/ml of membrane volume with a plasmid DNA recovery of ~ 90%, which is superior to other commercially available anion-exchange resins and membranes. The membrane was able to retain its structural integrity and performance after multiple cycles of usage (> 30 cycles). The inherent properties of plasmid DNA, membrane adsorbent, and the ionic environment on membrane performance were identified as the factors affecting membrane performance and their effects were systematically investigated. Plasmid DNAs with smaller tertiary structure have shorter dynamic radius and/or lowersurface charge densities, which tended to have a better adsorption and recovery than those with larger tertiary structure. Environmental Scanning Electron Microscopy (ESEM) revealed that the hydrogel structure is more porous on one side of membrane than the other, and higher plasmid DNA adsorption and recovery capacities were observed if the more porous side of the membrane was installed upward of flow in the chromatographic unit. ESEM also revealed improved pore distribution and increased membrane porosity if membrane was pre-equilibrated in the buffer solution for 16 hours. The development of better flow through channel in the hydrogel membrane upon extensive soaking further improved plasmid DNA adsorption and recovery capacities. The ionic environment affects the tertiary size of plasmid DNA; and the optimal operating pH of membrane chromatography was different for the plasmid DNAs investigated in this study. The relative contribution of these factors to improve membrane chromatography of plasmid DNAs was analyzed using statistical modeling. It was found that the adsorption of plasmid DNA was mainly affected by the available adsorptive area associated with membrane porosity, whereas the recovery of plasmid DNAs was mainly affected by the environmental pH. A novel, RNase-free, and potentially scalable bioprocess was synthesized using the hydrogel membrane as the technology platform for the manufacturing of pharmaceutical-grade plasmid DNA. High bioprocess recovery and product quality were primarily associated with the optimal integration of impurity removal by calcium chloride precipitation and anion-exchange membrane chromatography and the implementation of isopropanol precipitation as a coupling step between the two impurity-removing steps. Complete removal of total cellular RNA impurity was demonstrated without the use of animal-derived RNase. High-molecular-weight (HMW) RNA and genomic DNA (gDNA) were removed by selective precipitation using calcium chloride at an optimal concentration. Complete removal of the remaining low-molecular-weight (LMW) RNA was achieved by membrane chromatography using the high-capacity and high-productive hydrogel membrane. The simultaneous achievement of desalting, concentrating and buffer exchange by the coupling step of isopropanol precipitation and the high efficiency and resolution of DNA-RNA separation by anion-exchange membrane chromatography significantly reduced the operating complexity of the overall bioprocess, increased the overall recovery of plasmid DNA, and enhanced product quality by removing trace amounts of impurities of major concern for biomedical applications, such as gDNA, proteins, and endotoxin.

The diesel engine is growing in popularity due to its energy efficiency and solving the emissions issues associated with diesel engine exhaust would clear the way for further growth. The key pollutants are NOx, particulate matter and unburned hydrocarbons. Selective catalytic reduction (SCR) catalysis is likely the best choice for NOx control. In SCR, NH3 selectively reacts with NOx to form N2 – the selectivity refers to NH3 reacting with NOx instead of the abundant O2. Urea is used as the NH3 source, being injected into the exhaust as an aqueous solution where the urea decomposes and NH3 is generated. Spatial resolution characterization techniques have been gaining attention in the catalysis field because of the higher level of information provided. In this thesis, a new spatial resolution technique, called SpaciFTIR (spatially-resolved, capillary-inlet Fourier transform infra-red spectroscopy), was developed, which overcomes the interference of water in the detection of NH3 in an earlier developed technique, SpaciMS (spatially-resolved, capillary-inlet mass spectrometry). With the new test method, three SCR topics were addressed. First, the three key SCR reactions were spatially resolved. These are the standard SCR reaction (2NO + 2NH3 + 1/2O2 = 2N2 + 3H2O), the fast SCR reaction (NO + NO2 + 2NH3 = 2N2 + 3H2O), and NO2-SCR, (6NO2 + 8NH3 = 7N2 + 12H2O). Results show that in the presence of NO2, but at a NO2/NOx ratio < 0.5, the fast SCR reaction proceeds followed by the standard SCR reaction, i.e. in series. If the NO2/NOx ratio exceeds 0.5, the NO2-SCR and fast SCR reactions occur in parallel. Compared to the standard integral test method, this spatial resolution technique clearly showed such trends. Secondly, the spatial resolution technique was used to characterize the effects of thermal aging on catalyst performance. It was found that for a highly aged catalyst, there was a radial activity profile due to an inhomogeneous temperature distribution in the process of aging. Aging effects on various key SCR reactions, i.e. NO oxidation, NH3 oxidation, and the reduction reactions, were studied. Last but not least, for the purpose of passive SCR system development, transient NH3 storage profiles along the monolith channel were measured with SpaciFTIR. Passive SCR is a system where the NH3 is generated on an upstream catalyst, such as a three-way catalyst or lean-NOx trap, instead of via urea injection. In such a system, NH3 is therefore not constantly being fed to the SCR catalyst, but “arrives” in pulses. Factors such temperature, NH3 concentration, pulsing time, flow rate and thermal aging were investigated. For the first time, NH3 migration was observed and its effect on SCR reactions along the length of catalyst was studied.

The reaction mechanism for the Selective Catalytic Reduction (SCR) of NO by NH3 on V2O5 surface was simulated by means of density functional theory (DFT) calculations performed at B3LYP/6-31G** level. As the initiation reaction, ammonia activation on V2O5 was investigated. Coordinate driving calculations showed that ammonia is adsorbed on Br&oslash / nsted acidic V-OH site as NH4 + species by a nonactivated process with a relative energy of -23.6kcal/mol. Vibration frequencies were calculated as 1421, 1650, 2857 and 2900cm-1 for the optimized geometry, in agreement with the experimental literature. Transition state with a relative energy of -17.1kcal/mol was also obtained. At the end of the Lewis acidic ammonia interaction calculations, it was observed that ammonia is hardly adsorbed on the surface. Therefore, it is concluded that the SCR reaction is initiated more favorably by the Br&oslash / nsted acidic ammonia adsorption. As the second step of the SCR reaction, NO interaction with the preadsorbed NH4 + species was investigated. Accordingly, NO interaction results in the formation of gas phase NH2NO molecule with a relative energy difference of 6.4kcal/mol. For the rest of the reaction sequence, gas phase decomposition of NH2NO was considered. Firstly, one of the hydrogen atoms of NH2NO migrates to oxygen. It then isomerizes in the second step. After that, the reaction proceeds with the isomerization of the other hydrogen. Finally, a second hydrogen atom migration to the oxygen leads to the formation of N2 and H2O. Total relative energy for this reaction series was obtained as -60.12kcal/mol, in agreement with the literature.

Selective laser sintering (SLS) is a rapid prototyping method in which three-dimensional objects are constructed by sintering thin layers of a variety of powdered materials via laser beam. In SLS, as in most other Rapid Prototyping methods, the produced parts exhibit varying degrees of intrinsic porosity due to the discrete nature of layer-by-layer production. Selective scanning and discrete bonding of individual particles or clusters of particles impart local porosity, which is mostly an undesired trait as the part integrity decreases with increased porosity. However, there are a number of emerging or potential applications as in tissue engineering and composite/functionally graded materials, in which part porosity and its control during production are needed. In this study, the manufacturing capabilities of selective laser sintering are investigated towards producing predesigned porous structures using a polymeric powder. The porous structures are characterized in two main categories: regular porous structures, which involve geometries such as predesigned holes and lattice structures that have orderly porous architecture, and irregular porous structures, which exhibit random pore architecture that is intrinsic in all SLS parts. The limitations of producing regular porous structures are investigated, identified and quantified, based on hole size and dimensional accuracy. An experimental analysis based on design of experiments is employed to investigate the effects of processing parameters on the resulting macroscopic pore properties of irregular porous structures. A mathematical relation is developed to quantify and predict the relations between the SLS process parameters: Laser power, hatching distance, laser scan spacing, and the resulting apparent mass density (as a measure of porosity). The subsequent tests verify accuracy of the developed empirical model.

In this study, we consider the disassembly problem of end-of-life (EOL) products for recovering valuable parts or assemblies. All parts obtained by disassembly processes of an EOL product may not be profitable due to their high recovery costs. Our problem is to select the parts to be released and determine the associated disassembly tasks so as to maximize the total profit. We first tackle the simple part selection problem, and then introduce a time constraint for the tasks to be performed for selected parts and search for incomplete time constrained sequences. We formulate our first problem as a Mixed Integer Problem and show that the constraint set of this formulation is totally unimodular. We also provide the dual formulation of our problem and its interpretation. For time-constrained part selection problem we propose a branch-and-bound algorithm. We first develop some reduction mechanism to reduce the size of the problem. Our solution procedure is capable of solving problems with up to 94 parts and tasks.

Willfully controlling the focus of an extracellular stimulus remains a significant challenge in the development of neural prosthetics and therapeutic devices. In part, this challenge is due to the vast set of complex interactions between the electric fields induced by the microelectrodes and the complex morphologies and dynamics of the neural tissue. Overcoming such issues to produce methodologies for targeted neural stimulation requires a system that is capable of (1) delivering precise, localized stimuli a function of the stimulating electrodes and (2) recording the locations and magnitudes of the resulting evoked responses a function of the cell geometry and membrane dynamics. In order to improve stimulus delivery, we developed microfabrication technologies that could specify the electrode geometry and electrical properties. Specifically, we developed a closed-loop electroplating strategy to monitor and control the morphology of surface coatings during deposition, and we implemented pulse-plating techniques as a means to produce robust, resilient microelectrodes that could withstand rigorous handling and harsh environments. In order to evaluate the responses evoked by these stimulating electrodes, we developed microscopy techniques and signal processing algorithms that could automatically identify and evaluate the electrical response of each individual neuron. Finally, by applying this simultaneous stimulation and optical recording system to the study of dissociated cortical cultures in multielectode arrays, we could evaluate the efficacy of excitatory and inhibitory waveforms. Although we found that the proximity of the electrode is a poor predictor of individual neural excitation thresholds, we have shown that it is possible to use inhibitory waveforms to globally reduce excitability in the vicinity of the electrode. Thus, the developed system was able to provide very high resolution insight into the complex set of interactions between the stimulating electrodes and populations of individual neurons.