The Cartesian Cubic lattice is known to be sub optimal when consideringband-limited signals but is still used as standard in three-dimensional medical magneticresonance imaging. The optimal sampling lattices are the body-centered cubic latticeand the face-centered cubic lattice. This report discusses the possible use of thesesampling lattices in MRI and presents verification of the non standard Fouriertransform method that is required for MR image creation for these sampling lattices.The results show that the Fourier transform is consistent with analytical models.

Made available in DSpace on 2014-06-12T23:15:10Z (GMT). No. of bitstreams: 2 arquivo9024_1.pdf: 7861997 bytes, checksum: d7323a07176d46d4c8bc477873ebf17d (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / O comportamento fluidodinâmico do riser de um modelo a frio tipo FCC foi investigado por meio das medidas da distribuição da concentração do catalisador com atenuação gama e simulação com modelo matemático. No riser do modelo a frio, MEF, com 0,032 m de diâmetro 2,3 m de comprimento circula o leito fluidizado cujos componentes são ar e catalisador de FCC. A unidade MEF opera com controle automático e instrumentos de medidas das variáveis fluidodinâmicas. A distribuição axial da concentração do catalisador foi medida utilizando-se uma fonte de Am-241 e detector de NaI(Tl) associado a multicanal com software de aquisição e avaliação de dados. O MEF foi adaptado para a validação de modelo fluidodinâmico que descreve o escoamento no riser, como por exemplo, a introdução de injetor para controle do fluxo de sólidos em circulação. Modelos matemáticos foram selecionados na literatura, analisados e testados para simular a fluidodinâmica do riser. Foi estudada e implementada uma metodologia para validar modelos fluidodinâmicos. As etapas do trabalhos foram desenvolvidas de acordo com a metodologia de validação, como planejamento de dados experimentais, estudo das equações que descrevem a fluidodinâmica, aplicação de solvers computacionais e avaliação da simulação em comparação com os dados experimentais. Corridas foram realizadas com as condições do MEF definidas para medir a concentração do catalisador e sendo medidas simultaneamente as variáveis fluidodinâmicas, velocidade dos componentes e variação da pressão no riser. Em seguida foram comparados valores simulados e valores experimentais, com o tratamento estatístico dos dados, visando a precisão requerida para validar o modelo fluidodinâmico. Os testes de comparação entre dados experimentais e simulados foram realizados sob os critérios de validação. O comportamento fluidodinâmico do riser foi analisado, os resultados e a concordância com a literatura foram discutidos. O modelo adotado foi validado nas condições de operação do riser do MEF, para uma faixa de vazão do gás de 3 a 6 m/s e o valor da razão de escorregamento entre 1 e 2

The Farmington Canyon Complex, situated along the Wasatch front in northern Utah, has been the target for many studies. The FCC has been interpreted to be a passive margin sedimentary wedge. Previous studies have yielded isotopic ages that broadly support an Archean age of formation, and a prominent mid-proterozoic amphibolite grade metamorphic event. Based on this study, a new interpretation for the FCC is presented. Field relations and whole-rock geochemistry as well as recent advances in understanding Archean crustal processes have resulted in the FCC to be considered as an accretionary complex that formed along the SW margin of the Wyoming province in the early Archean. Rock assemblages such as mafic and ultramafic metavolcanics have chemistries that resemble oceanic crust and arc related volcanics. The extensive quartzo-felspathic gneiss and schist units have compositions that reflect greywacke, and are presented here as a melange matrix. The quartzites have chemistries, which may represent cherts or silicified microbial mats. The field relations and timing of these rocks indicate that the FCC may represent a continental arc synchronous with the closing of an ocean basin, forming an accretionary wedge. This culminated with the mid-proterozoic metamorphic event as this continental arc collided with the Santaquin arc, as well as the SW margin of Laurentia. This amphibolite grade metamorphic event has subsequently reset or overprinted isotopic evidence and obscured any textures that may have existed. Although much has yet to be learned about Archean processes, comparison to other recognized Archean accretionary complexes has yielded striking similarities, and it is presented here that the FCC represents an active margin, and is likely an accretionary melange.

Due to the migration of scientists towards green chemistry, landfilling and incineration will no longer be acceptable options for plastics waste disposal in the future. Consequently new methods for recycling plastics and plastic products such as carpets are being researched. This study serves as a preliminary effort to study the catalytic feedstock recycling of polyolefins, specifically PP and PE, as source for gasoline range fuels, as well as an alternative for plastic waste disposal. Several studies have been conducted on the pyrolysis of waste polyolefins using commercial cracking catalysts (FCC), however, the effect of catalyst size and mode of catalyst dispersion have been studied sparsely. This thesis proposes to study these effects in the catalytic pyrolysis of polypropylene (PP), a component of carpets, using both fresh and used FCC catalysts. The same study will be applied to polyethylene (PE), which accounts for an enormous amount of municipal solid waste in the US today. Furthermore, the catalytic impact of calcium carbonate, a filler component of tufted carpet, will be investigated. Using thermogravimetric analysis, the global kinetics of the PP pyrolysis using various FCC catalysts will be derived and applied in the modeling of the pyrolysis reaction in a twin screw extruder. Furthermore, an economic analysis on the catalytic pyrolysis of PP is presented.

This thesis summarizes a series of studies of how image quality is affected by the choice of sampling pattern in 3D. Our comparison includes the Cartesian cubic (CC) lattice, the body-centered cubic (BCC) lattice, and the face-centered cubic (FCC) lattice. Our studies of the lattice Brillouin zones of lattices of equal density show that, while the CC lattice is suitable for functions with elongated spectra, the FCC lattice offers the least variation in resolution with respect to direction. The BCC lattice, however, offers the highest global cutoff frequency. The difference in behavior between the BCC and FCC lattices is negligible for a natural spectrum. We also present a study of pre-aliasing errors on anisotropic versions of the CC, BCC, and FCC sampling lattices, revealing that the optimal choice of sampling lattice is highly dependent on lattice orientation and anisotropy. We suggest a new reference function for studies of aliasing errors on alternative sampling lattices. This function has a spherical spectrum, and a frequency content proportional to the distance from the origin, facilitating studies of pre-aliasing in spatial domain. The accuracy of anti-aliased Euclidean distance transform is improved by application of more sofisticated methods for computing the sub-spel precision term. We find that both accuracy and precision are higher on the BCC and FCC lattices than on the CC lattice. We compare the performance of several intensity-weighted distance transforms on MRI data, and find that the derived segmentation result, with respect to relative error in segmented volume, depends neither on the sampling lattice, nor on the sampling density. Lastly, we present LatticeLibrary, a open source C++ library for processing of sampled data, supporting a number of common image processing methods for CC, BCC, and FCC lattices. We also introduce BccFccRaycaster, a tool for visualizing data sampled on CC, BCC, and FCC lattices. We believe that the work summarized in this thesis provide both the motivation and the tools for continuing research on application of the BCC and FCC lattices in image processing and analysis.

Ce travail de recherche est basé sur la technologie Ultra Large Bande (ULB), en particulier pour des applications bas débit (standard IEEE 802.15.4) tels que les réseaux de capteurs, les transmissions WPAN ou encore WBAN. La modélisation et la conception d’un récepteur non cohérent ULB pour les communications radio impulsionnelles ont été réalisées. Un des facteurs les plus importants dans les communications ULB est la sensibilité du récepteur, qui détermine la portée de transmission maximale. Un autre facteur aussi important est la consommation d’énergie qui influence directement la durée de vie de la source d’alimentation (batterie). Dans ce contexte, nous présentons dans le chapitre I une introduction sur la technologie ULB et ses diverses applications. Le chapitre II présente la modélisation au niveau système ainsi que d’une étude comparative des récepteurs non cohérents basés sur la détection d’énergie et la pseudo-Détection d’énergie. Dans le chapitre III sont présentés la méthode de conception et de réalisation d’un récepteur non cohérent ULB dans la bande de 3-5 GHz, ainsi que les résultats de mesure et ses performances en termes de sensibilité et de consommation d’énergie. Finalement, le chapitre IV présente une étude théorique sur les différents modes de fonctionnement du transistor MOS afin de mieux comprendre le fonctionnement de chaque bloc du récepteur. Cela permet de proposer de nouvelles architectures pour la détection d’énergie. Enfin, à partir de ces études nous réalisons l’optimisation du récepteur en termes de sensibilité et de consommation d’énergie. / This research is based on Ultra Wide Band (UWB) technology, in particularly for low-Rate applications such as sensor network, WPAN and WBAN (for the standard IEEE 802.15.4). The model and design of a non coherent receiver for UWB impulse radio communications has been completed. One of the most important factors in the UWB communications is the receiver sensitivity which determines the maximum transmission range. Another important factor is the energy consumption that determines the lifetime of the power source (battery). In this context, we present in Chapter I an introduction to UWB technology and its different applications. Chapter II deals with a modeling at the system level of non-Coherent receivers as well as a comparative study based on the energy detection and pseudo energy detection. In Chapter III is presented the method of design and implementation of a non-Coherent UWB receiver in the band of 3-5 GHz, as well as measurement results and performance in terms of sensitivity and power consumption. Finally, Chapter IV presents a theoretical study on the different modes of operation of the MOS transistor to understand the operation of each block of the receiver. This allows us to show the new architectures for energy detection and perform the optimization of receiver in terms of sensitivity and power consumption.

This dissertation includes two accounts of rigorous modeling of petroleum refinery modeling using rigorous reaction and fractionation units. The models consider various process phenomena and have been extensively used during a course of a six-month study to understand and predict behavior. This work also includes extensive guides to allow users to develop similar models using commercial software tools. (1) Predictive Modeling of Large-Scale Integrated Refinery Reaction and Fractionation Systems from Plant Data: Fluid Catalytic Cracking (FCC) Process with Planning Applications: This work presents the methodology to develop, validate and apply a predictive model for an integrated fluid catalytic cracking (FCC) process. We demonstrate the methodology by using data from a commercial FCC plant in the Asia Pacific with a feed capacity of 800,000 tons per year. Our model accounts for the complex cracking kinetics in the riser-regenerator and associated gas plant phenomena. We implement the methodology with Microsoft Excel spreadsheets and a commercial software tool, Aspen HYSYS/Petroleum Refining from Aspen Technology, Inc. The methodology is equally applicable to other commercial software tools. This model gives accurate predictions of key product yields and properties given feed qualities and operating conditions. This work differentiates itself from previous work in this area through the following contributions: (1) detailed models of the entire FCC plant, including the overhead gas compressor, main fractionator, primary and sponge oil absorber, primary stripper and debutanizer columns; (2) process to infer molecular composition required for the kinetic model using routinely collected bulk properties of feedstock; (3) predictions of key liquid product properties not published alongside previous related work (density, D-86 distillation curve and flash point); (4) case studies showing industrially useful applications of the model; and (5) application of the model with an existing LP-based planning tool. (2) Predictive Modeling of Large-Scale Integrated Refinery Reaction and Fractionation Systems from Plant Data: Continuous Catalyst Regeneration (CCR) Reforming Process: This work presents a model for the rating and optimization of an integrated catalytic reforming process with UOP-style continuous catalyst regeneration (CCR). We validate this model using plant data from a commercial CCR reforming process handling a feed capacity of 1.4 million tons per year in the Asia Pacific. The model relies on routinely monitored data such ASTM distillation curves, paraffin-napthene- aromatic (PNA) analysis and operating conditions. We account for dehydrogenation, dehydrocyclization, isomerization and hydrocracking reactions that typically occur with petroleum feedstock. In addition, this work accounts for the coke deposited on the catalyst and product recontacting sections. This work differentiates itself from the reported studies in the literature through the following contributions: (1) detailed kinetic model that accounts for coke generation and catalyst deactivation; (2) complete implementation of a recontactor and primary product fractionation; (3) feed lumping from limited feed information; (4) detailed procedure for kinetic model calibration; (5) industrially relevant case studies that highlight the effects of changes in key process variables; and (6) application of the model to refinery-wide production planning. / Ph. D.

Yes / The Riser of a Fluid Catalytic Cracking (FCC) unit cracks gas oil to make fuels such as gasoline and diesel. However, changes in quality, nature of crude oil blends feedstocks, environmental changes and the desire to obtain higher profitability, lead to many alternative operating conditions of the FCC riser. The production objective of the riser is usually the maximization of gasoline and diesel. Here, an optimisation framework is developed in gPROMS to maximise the gasoline in the riser of an industrial FCC unit (reported in the literature) while optimising mass flowrates of catalyst and gas oil. A detailed mathematical model of the process developed is incorporated in the optimisation framework. It was found that, concurrent use of the optimal values of mass flowrates of catalyst (310.8 kg/s) and gas oil (44.8 kg/s) gives the lowest yield of gases, but when these optimum mass flowrates are used one at time, they produced the same and better yield of gasoline (0.554 kg lump/ kg feed). / Petroleum Technology Development Fund, Nigeria, financially sponsored the study.

Yes / The FCC riser cracks gas oil into useful fuels such as gasoline, diesel and some lighter products such as ethylene and propylene, which are major building blocks for the polyethylene and polypropylene production. The production objective of the riser is usually the maximization of gasoline and diesel, but it can also be to maximize propylene. The optimization and parameter estimation of a six-lumped catalytic cracking reaction of gas oil in FCC is carried out to maximize the yield of propylene using an optimisation framework developed in gPROMS software 5.0 by optimizing mass flow rates and temperatures of catalyst and gas oil. The optimal values of 290.8 kg/s mass flow rate of catalyst and 53.4 kg/s mass flow rate of gas oil were obtained as propylene yield is maximized to give 8.95 wt%. When compared with the base case simulation value of 4.59 wt% propylene yield, the maximized propylene yield is increased by 95%.

Yes / Fluid Catalytic Cracking (FCC) unit is an important unit of modern refineries and any improvement in the unit’s operations and design to increase yield and meet the ever increasing demand for fuel brings about the overall profitability of the FCC. In this work, simulation of an FCC riser of varied diameter was carried out to improve the unit’s operations and design, and the results are compared with risers of different diameters. The riser with varied diameter produces 53.4 wt%, a 3.18% increased yield of gasoline at low catalyst to oil (C/O) ratio of 1.27 compared to 51.7 wt% from a 1 m diameter riser. At increased C/O ratio, more gases and coke are produced in the varied diameter riser. Larger diameter demands more catalyst but yields more gases. Process variables can be directly correlated with yield of gasoline, which can aid process design.