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京都大学 / 新制・課程博士 / 博士(工学) / 甲第23502号 / 工博第4914号 / 新制||工||1768(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 平方 寛之, 教授 北條 正樹, 教授 嶋田 隆広, 教授 井上 康博 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Chemical enhanced oil recovery has regained its attention because of high oil price and the depletion of conventional oil reservoirs. This process is more complex than the primary and secondary recovery flooding and requires detailed engineering design for a successful field-scale application. An effective alkaline/co-solvent/polymer (ACP) formulation was developed and corefloods were performed for a cost efficient alternative to alkaline/surfactant/polymer floods by the research team at the department of Petroleum and Geosystems Engineering at The University of Texas at Austin. The alkali agent reacts with the acidic components of heavy oil (i.e. 170 cp in-situ viscosities) to form in-situ natural soap to significantly reduce the interfacial tension, which allows producing residual oil not contacted by waterflood or polymer flood alone. Polymer provides mobility control to drive chemical slug and oil bank. The cosolvent added to the chemical slug helps to improve the compatibility between in-situ soap and polymer and to reduce microemulsion viscosity. An impressive recovery of 70% of the waterflood residual oil saturation was achieved where the remaining oil saturation after the ACP flood was reduced to only 13.5%. The results were promising with very low chemical usage for injection. The UTCHEM chemical flooding reservoir simulator was used to model the coreflood experiments to obtain parameters for pilot scale simulations. Geological model was based on unconsolidated reservoir sand with multiple seven spot well patterns. However, facility capacity and field logistics, reservoir heterogeneity as well as mixing and dispersion effects might prevent coreflood design at laboratory from large scale implementation. Field-scale sensitivity studies were conducted to optimize the design under uncertainties. The influences of chemical mass, polymer pre-flush, well constraints, and well spacing on ultimate oil recovery were closely investigated. This research emphasized the importance of good mobility control on project economics. The in-situ soap generated from alkali-naphthenic acid reaction not only mobilizes residual oil to increase oil recovery, but also enhances water relative permeability and increases injectivity. It was also demonstrated that a closer well spacing significantly increases the oil recovery because of greater volumetric sweep efficiency. This thesis presents the simulation and modeling results of an ACP process for a viscous oil in high permeability sandstone reservoir at both coreflood and pilot scales. / text

abstract: In sub transmission systems, many more raptor deaths have been recorded near metal poles rather than wood poles. The metal pole, which is reliable in structure but also grounded, may increase the risk of electrocution when raptors perch on the insulator. This thesis focuses on evaluating the effectiveness of the raptor guard to prevent both debilitating and lethal electrocutions to local wildlife in 69 kV sub transmission systems. First, the two-dimensional (2D) finite difference methods (FDM) were proposed to solve the Poisson and Laplace equations, which describe the electric field. Second, the verification of the FDM algorithm was made based on a parallel-plate capacitor model. Then, the potential and the electric field were simulated by the raptor-insulator model to evaluate the possibility of flashover and leakage current under various conceivable scenarios. Third, several dielectric performance experiments were implemented to gain insight into the physical property of the raptor guard developed by the Salt River Project (SRP) as an example. The proposed initial-tracking-voltage and time-to-track experiments tested the ability of the guard, which is designed to prevent the tracking phenomenon under a contaminated situation such as rain, fog, and snow. A data acquisition also collected the leakage current data for the comparison of maximum raptor tolerance. Furthermore, the puncture voltage of this guard material was performed by the dielectric breakdown voltage experiment in an oil-covered container. With the combination of the model simulation and the experiments in this research, the raptor guard was proven to be practical and beneficial in sub transmission system. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016

Presented diploma thesis deals with development of the autonomous electric energy source for Health and Usage Monitoring Systems placed at the rear part of a helicopter. Firstly, the HUMS systems were described briefly and the research of available energy sources was made after that. After that, the magnetic properties of the materials were described with the special focus on the permanent magnets. The draft also includes the creation of model of the magnetic field using the final element method. Prototype was assembled and the other design solutions were evaluated. The evaluation of various designs passed in the use of SOMA optimization algorithms. The generator is followed by the draft of the electronics, which streamlines and regulates a voltage supplied by the generator. At the end of the thesis, the complete source prototype was assembled and tested with two different regulators

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24890号 / 工博第5170号 / 新制||工||1987(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 嶋田 隆広, 教授 平方 寛之, 教授 井上 康博 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

<p>Rapid solidification is a well established method to produce novel materials with improved mechanical or electrical properties. The sharp-interface kinetics of rapid solidification for a binary alloy is summarized. A Phase Field model mapping to this sharp interface model is summarized and solved by a new adaptive mesh refinement algorithm. Simulation results are consistent with experiments: The solidification velocity increases in power-law like fashion at low undercooling and approximately linearly at high undercooling; The solid/liquid interface undergoes a transition from four-fold dendritic to circular crystal structures; Solute trapping emerges and the solute partitioning approaches unity as the solidification velocity increases. Our Phase Field simulations are the first self -consistent predictions of velocity selection and morphological selection at both low and high undercoolings and also the first independent check of the solute trapping model in two dimensions.</p> / Thesis / Master of Applied Science (MASc)

The limiting current technique has widely been used to study liquid-solid mass transfer in various reactor configurations. In the present contribution several underlying physical aspects have been investigated in order to improve the design of mass transfer experiments. Experimentally, the significant influence of electrolyte composition and hydrodynamic conditions have been studied and quantified to ensure conditions of high reproducibility. In the course of single phase COMSOL simulations, different electrode configurations have been examined with emphasis on concentration fields and electric current distribution showing a large sensitivity of the experimental configuration on the absolute current values.

The limiting current technique has widely been used to study liquid-solid mass transfer in various reactor configurations. In the present contribution several underlying physical aspects have been investigated in order to improve the design of mass transfer experiments. Experimentally, the significant influence of electrolyte composition and hydrodynamic conditions have been studied and quantified to ensure conditions of high reproducibility. In the course of single phase COMSOL simulations, different electrode configurations have been examined with emphasis on concentration fields and electric current distribution showing a large sensitivity of the experimental configuration on the absolute current values.

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