Дисертації з теми "Injection system modeling"

Frontend and backend wearout mechanisms are major reliability concerns for modern microprocessors. In this research, a framework which contains modules for negative bias temperature instability (NBTI), positive bias temperature instability (PBTI), hot carrier injection (HCI), gate-oxide breakdown (GOBD), backend time-dependent dielectric breakdown (BTDDB), electromigration (EM), and stress-induced voiding (SIV) is proposed to analyze the impact of each wearout mechanism on state-of-art microprocessors and to accurately estimate microprocessor lifetimes due to each wearout mechanism. Taking into account the detailed thermal profiles, electrical stress profiles and a variety of use scenarios, composed of a fraction of time in operation, a fraction of time in standby, and a fraction of time when the system is off, this work provides insight into lifetime-limiting wearout mechanisms, along with the reliability-critical microprocessor functional units for a system. This enables circuit designers to know if their designs will achieve an adequate lifetime and further make any updates in the designs to enhance reliability prior to committing the designs to manufacture.

Thesis (Ph. D. )--University of Cincinnati, 2007.
Advisor: Dr. Tim C Keener. Title from electronic thesis title page (viewed Nov. 23, 2007). Includes abstract. Keywords: SO 2, trona, conversion, NaHCO 3, Na 2CO 3, Modeling, Kinetics Includes bibliographical references.

La législation sur les émissions de polluants des Moteurs à Combustion Interne (ICEs) est de plus en plus contraignante et représente un gros défi pour les constructeurs automobiles. De nouvelles stratégies de combustion telles que la Combustion à Allumage par Compression Homogène (HCCI) et l’exploitation de stratégies d’injections multiples sont des voies prometteuses qui permettent de respecter les normes sur les émissions de NOx et de suies, du fait que la combustion a lieu dans un mélange très dilué et par conséquent à basse température. Ces aspects demandent la création d’outils numériques adaptés à ces nouveaux défis. Cette thèse présente le développement d’un nouveau modèle 0D de combustion Diesel HCCI : le dual Combustion Model (dual - CM). Le modèle dual-CM a été basé sur l’approche PCM-FPI utilisée en Mécanique des Fluides Numérique (CFD) 3D, qui permet de prédire les caractéristiques de l’auto-allumage et du dégagement de chaleur de tous les modes de combustion Diesel. Afin d’adapter l’approche PCM-FPI à un formalisme 0D, il est fondamental de décrire précisément le mélange à l’intérieur du cylindre. Par consequent, des modèles d’évaporation du carburant liquide, de formation de la zone de mélange et de variance de la fraction de mélange, qui permettent d’avoir une description détaillée des proprietés thermochimiques locales du mélange y compris pour des configurations adoptant des stratégies d’injections multiples, sont proposés. Dans une première phase, les résultats du modèle ont été comparés aux résultats du modèle 3D. Ensuite, le modèle dual-CM a été validé sur une grande base de données expérimentales; compte tenu du bon accord avec l’expérience et du temps de calcul réduit, l’approche présentée s’est montrée prometteuse pour des applications de type simulation système. Pour conclure, les limites des hypothèses utilisées dans dual-CM ont été investiguées et des perspectives pour les dévélopements futurs ont été proposées
More and more stringent restrictions concerning the pollutant emissions of Internal Combustion Engines (ICEs) constitute a major challenge for the automotive industry. New combustion strategies such as Homogeneous Charge Compression Ignition (HCCI) and the implementation of complex injection strategies are promising solutions for achieving the imposed emission standards as they permit low NOx and soot emissions, via lean and highly diluted combustions, thus assuring low combustion temperatures. This requires the creation of numerical tools adapted to these new challenges. This Ph.D presents the development of a new 0D Diesel HCCI combustion model : the dual Combustion Model (dual−CM ). The dual-CM is based on the PCM-FPI approach used in 3D CFD, which allows to predict the characteristics of Auto-Ignition and Heat Release for all Diesel combustion modes. In order to adapt the PCM-FPI approach to a 0D formalism, a good description of the in-cylinder mixture is fundamental. Consequently, adapted models for liquid fuel evaporation, mixing zone formation and mixture fraction variance, which allow to have a detailed description of the local thermochemical properties of the mixture even in configurations adopting multiple injection strategies, are proposed. The results of the 0D model are compared in an initial step to the 3D CFD results. Then, the dual-CM is validated against a large experimental database; considering the good agreement with the experiments and low CPU costs, the presented approach is shown to be promising for global engine system simulations. Finally, the limits of the hypotheses made in the dual-CM are investigated and perspectives for future developments are proposed

To make a High Voltage Direct Current (HVDC) transmission more energy efficient, the voltage of the system has to be increased. To allow for that the components of the system must be constructed to handle the increases AC and DC stresses that this leads to. One key component in such a transmission is the HVDC converter transformer. The insulation system of the transformer usually consists of oil and oil-impregnated pressboard. Modeling of the electric DC field in the insulation system is currently done with the ion drift diffusion model, which takes into account the transport and generation of charges in the oil and the pressboard. The model is however lacking a description of how charges are being injected from the electrodes and the oil-pressboard interfaces. The task of this thesis work was to develop and implement a model for this which improves the result of the ion drift diffusion model. A theoretical study of ion injection was first carried out and proceeding from this, a model for the ion injection was formulated. By using experimental data from 5 different test geometries, the injection model could be validated and appropriate parameter values of the model could be determined. By using COMSOL Multiphysics®, the ion drift diffusion model with the injection model could be simulated for the different test geometries. The ion injection gave a substantial improvement of the ion drift diffusion model. The positive injection from electrodes into oil was found to be in the range 0.3-0.6 while the negative injection was 0.3 lower. Determination of the parameters for the injection from oil-pressboard interfaces proved to be difficult, but setting the parameters in the range 0.01-1 allowed for a good agreement with the experimental data. Here, a fit could be obtained for multiple assumptions about the set of active injection parameters. Finally it is recommended that the investigation of the ion injection continues in order to further improve the model and more accurately determine the parameters of it. Suggestions on how this work could be carried out are given in the end.

The fuel pressure is one of the central control variables of a modern common-rail injection system. It influences the generation of nitrous oxide and particulate matter emissions, the brake specific fuel consumption of the engine and the power consumption of the fuel pump. Accurate control of the fuel pressure and reliable diagnostics of the fuel system are therefore crucial components of the engine management system. In order to develop for example control or diagnostics algorithms and aid in the understanding of how hardware changes affect the system, a simulation model of the system is desirable.  A Simulink model of the XPI (Xtra high Pressure Injection) system developed by Scania and Cummins is developed. Unlike the previous models of the system available, the new model is geared towards fast simulations by modelling only the mean flow and pressure characteristics of the system, instead of the momentary flow and pressure variations as the engine rotates. The model is built using a modular approach where each module represents a physical component of the system. The modules themselves are based to a large extent on the physical properties of the components involved, making the model of the system adaptable to different hardware configurations whilst also being easy to understand and modify.
Bränsletrycket är en av de centrala styrvariablerna i ett modernt common-rail insprutningssystem. Det påverkar utsläppen av kväveoxider och partiklar, motorns specifika bränsleförbrukning och bränslepumpens effektförbrukning. Nogrann reglering och tillförlitliga diagnoser av bränslesystemet är därför mycket viktiga funktioner i motorstyrsystemet. Som ett hjälpmedel vid utveckling av dessa algoritmer samt för att öka förståelsen för hur hårdvaruförändringar påverkar systemet är det önskvärt med en simuleringsmodel av bränslesystemet.  En Simulink modell av XPI (Xtra high Pressure Injection) systemet som utvecklats av Scania och Cummins har utvecklats. Till skillnad från de redan tillgängliga modellerna av systemet fokuserar denna modell på snabba simuleringsförlopp genom att enbart modellera medeltryck och medelflöden istället för de momentana trycken och flödena i systemet när motorn roterar. Modellen är uppbyggd av moduler som var och en representerar en fysisk komponent i systemet. Modulerna är mestadels uppbyggda kring de fysikaliska egenskaperna hos komponenten de försöker modellera vilket gör modellen av systemet anpassningsbar till olika hårdvarukonfigurationer och samtidigt lätt att förstå.

In this thesis, CO2 injection in matrix/fracture systems has been studied using a finely-gridded compositional simulator representing a single matrix block. Three laboratory experiments were modeled to investigate whether CO2 injection in a fracture-matrix system could be simulated using commercial simulators that include basic fluid flow physics, phase behavior, and molecular diffusion. The first experiment was performed by Karimaie (2007) using an equilibrium, saturated gas-oil fluid system (C1-n-C7) at 220 bar and 85 oC. Because no recovery was expected from non-equilibrium thermodynamic mass transfer, reported recovery stemmed only from Darcy displacement driven by gravity and capillary forces. When the oil production stopped from the equilibrium gas displacement, a second injection period with pure CO2 followed. The numerical modeling was conducted using a compositional reservoir simulator (SENSOR) without diffusion. The 2-dimensional r-z model used fine grids for the core matrix and surrounding fracture. Automated history matching was used to determine parameters which were not accurately known (fracture permeability, fracture and matrix porosity, and separator conditions), using surface volumetric oil production rates reported experimentally. The final model match was relatively unique with a high degree of confidence in final model parameters. The oil recovery improved significantly with CO2 injection. Our model indicated that the recovery mechanism in the Karimaie experiment was dominated, for both equilibrium gas and CO2 injection, by top-to-bottom Darcy displacement caused by low conductivity in the artificial fracture; little impact of capillary-gravity displacement was found. Changes in CO2 injection rate had a significant impact on recovery performance. This experiment was also modeled using ECL300, with the same production performance as SENSOR for the set of history-match parameters determined without diffusion. When molecular diffusion was used in ECL300, results were nearly identical with those found without diffusion. Two other experiments were performed by Darvish (2007) at a higher temperature and pressure (130 oC and 300 bara) using a similar chalk and live reservoir oil. A similar modeling approach to that described above was also used for these experiments. In both experiments, the matching process based on reported oil production data gave a high degree of confidence in the model. The reported experimental mass fractions of produced-stream components were also matched well. Our modeling study indicates that gravity drainage affects the displacement process, but that mass transfer – including vaporization, condensation and molecular diffusion – also impact the recovery performance of CO2 injection in the Darvish experiments. The CO2 injection rate and initial water saturation were investigated by comparing the two Darvish experiments. Our studies from all of the Karimaie and Darvish experiments show a strong influence of the surface separator temperature on surface oil production, and this is an important consideration in designing and interpreting laboratory production data consistently. Once the laboratory recovery mechanisms had been successfully modeled, predictive numerical simulation studies were conducted on field-scale matrix/fractured systems, albeit mostly for single matrix blocks surrounded by a fracture. The effects of several key parameters on recovery production performance were studied in detail for field-scale systems: matrix permeability, matrix block size, matrix-matrix capillary continuity (stacked blocks), and the use of mixtures containing CO2 and hydrocarbon gas. The field-scale results were affected by gridding, so grid was refined to the degree necessary to achieve a more-or-less converged solution – i.e. recovery production performance didn’t change with further refinement. We studied the effect of molecular diffusion on oil recovery by CO2 injection in laboratory experiments and field-scale systems. Because the fluid systems considered had complex phase behavior and a wide range of conditions from strongly immiscible to near-miscible, the diffusion driving potential used was total component potential including chemical and gravity effects; concentrationdriven diffusion did not represent the more-complex non-equilibrium CO2 injection processes observed in the laboratory tests. A key result of this study was that diffusion can have an important effect on oil recovery, and that this effect varies with matrix block size and CO2 injection rate. We have shown that diffusion has a dominant effect on the recovery mechanism in experimental tests, except at very low rates of CO2 injection (and equilibrium hydrocarbon gas injection). For the field-scale matrix/fracture systems, diffusion can have a significant effect on the rate of recovery, with the effect becoming noticeable for low reservoir pressures and/or matrix block sizes less than ~40 ft.

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Salant, Richard F.; Committee Member: Bair, Scott; Committee Member: Cowan, Richard S; Committee Member: Danyluk, Steven; Committee Member: Scott, Waymond R. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Bibliography: p. 215-231. This thesis investigates the behaviour of semiconductor lasers under large amplitude sinusoidal current modulations. It focuses directly on the behaviour of Faby-Perot lasers under direct modulation of the injection current.

Electromagnetic launchers are currently being developed for their use as military weapons. These devices launch a projectile to extremely high speeds using very large electric currents. One obstacle facing the development of electromagnetic launchers is damage to the rails and armature during launch. The damage occurs due to current arcing in the armature-rail interface and is denoted as a transition. One solution is to use a lubricant injection system contained inside the armature to provide a conductive lubricant to the interface. The lubricant will ensure good electrical contact, prevent solid-solid contact, and cool the interface to prevent a launch from transitioning. Various different armature designs are currently under development. Each design must be analyzed through armature-rail interface modeling in order to predict the physical behavior and identify causes of transitions. There have been many studies on the physical behavior of sliding contacts. Some of which are directly applied to electromagnetic launch. In particular the magneto-elastothermohydrodynamic model is the most comprehensive model found for use in simulating electromagnetic launch. It includes calculation of the electromagnetic field, elastic deformation of the armature, calculation of the armature temperature history, and a hydrodynamic study of the lubricant both in the injection system and the armature-rail interface. The magneto-elastothermohydrodynamic model has been applied to only one armature design with limited success due to the assumptions used. The magneto-elastothermohydrodynamic model is applied to six different armature designs each requiring modifications to be made in order to predict the distinct behavior of each launcher. Modifications to the model include consideration of turbulent flow in the injection conduit, unique injection configurations, dry-out of the armature-rail interface, two dimensional pressure fields, and analyses of cylindrical bore launcher designs. The results show the model is effective in predicting when a transition will occur and what physical event leads to a transition when compared to experimental launch data. Additionally, experimental observations are used to affirm the simulation of other physical characteristics. It is found by the simulation that the base case armature is successful in preventing a transition of the shot, which is consistent with the experimental results. The simulation of NRL shot 223 reveals that such a small amount of lubricant is supplied by the reservoirs that the armature-rail interface partially dries out making a transition likely at a time of 4.7 ms; agreeing with the experimentally observed transition at a time of 4.5 ms. It is determined that the transition of NRL shot 406 is not due to a lack of lubricant inside the interface and that the amount of lubricant which leaks from the joint is negligible. IAP shot 7 did not transition in the experiment, however, after a time of about 3.5 ms the muzzle voltage began to rise. The simulation presents a possible explanation, showing that the armature-rail interface is beginning to empty out after 4.2 ms. The simulation of the GTL-2-4C armature shows that the experimentally observed transition is caused by the reservoirs emptying out at about 2.1 ms. The exploratory simulation of a modified GTL-2-4C armature determines that the absence of the slit in the armature trailing edges will not prevent the transition nor extend the successful portion of the shot.

This thesis concerns applications of learning-based testing (LBT) in the automotive domain. In this domain, LBT is an attractive testing solution, since it offers a highly automated technology to conduct safety critical requirements testing based on machine learning. Furthermore, as a black-box testing technique, LBT can manage the complexity of modern automotive software applications such as advanced driver assistance systems. Within the automotive domain, three relevant software testing questions for LBT are studied namely: effectiveness of requirements modeling, learning efficiency and error discovery capabilities. Besides traditional requirements testing, this thesis also considers fault injection testing starting from the perspective of automotive safety standards, such as ISO26262. For fault injection testing, a new methodology is developed based on the integration of LBT technologies with virtualized hardware emulation to implement both test case generation and fault injection. This represents a novel application of machine learning to fault injection testing. Our approach is flexible, non-intrusive and highly automated. It can therefore provide a complement to traditional fault injection methodologies such as hardware-based fault injection.

QC 20190325

This master thesis treats the modelling of a common-rail direct fuel injection system where pressure generation is decoupled from the injection process. It has been shown that the fuel pressure plays a vital role for the general performance of the engine, affecting both emissions and efficiency, and it is carefully regulated to achieve optimal performance at different operating points. In an attempt to facilitate the development of the responsible control algorithms, a simulation framework has been requested. A model describing the complete work cycle of the high-pressure fuel system is developed and implemented in a Simulink environment. It is to a large extent based on the underlying physics and constructed in a modular manner, which allows for different engine configurations to be simulated. The modelled pressure signal is compared to experimental data at different operating points with promising results in capturing the transient behaviour from a low-level perspective. Additionally, it manages to replicate some of the pressure oscillations which has been observed in the real system and it shows good response to changes in the input signals. However, there are some areas which are subject to improvement since capturing the static pressure levels over longer drive cycles has proved to be a difficult task. Overall, the developed model serves as a starting point for future development and validation of control algorithms.

Les normes sur les émissions de polluants des automobiles sont de plus en plus sévères. Les moteurs à injection directe à rampe commune permettent d'atteindre ces exigences notamment grâce à l'injection du carburant à très haute pression. Cette pression varie de 200 à 1600 bar selon le point de fonctionnement du véhicule. L'objectif des travaux de thèse est de réaliser le contrôle de la pression du carburant avec deux contraintes principales : proposer une méthodologie de calibration du contrôleur à partir des caractéristiques techniques du système d'injection et améliorer à la fois la performance et la robustesse du contrôle. Les travaux réalisés se décomposent comme suit : étude du système d'injection et développement d'un modèle de connaissance ; développement des stratégies et des lois de commande ; mise en application sur véhicule. Les essais réalisés sur véhicule ont montré une amélioration des performances et de la robustesse du contrôle de la pression du carburant obtenue par la proposition d'une nouvelle méthodologie de calibration. Celle-ci est basée par l'obtention du contrôleur à partir des caractéristiques techniques du système d'injection et par l'utilisation de lois de commande avancées (commande H8 pour les systèmes Linéaires à Paramètres Variants (LPV)). En particulier l'approche basée sur l'utilisation des Transformations Linéaires Fractionnelles (LFT) a été considérée
Vehicle exhaust emissions are today more and more restrictive. Common Rail engines allow to reach these requirements thanks to the high pressure injection. This pressure can vary from 200 up to 1600 bar according to the engine torque and speed. The goal of this work is to define the rail pressure controller based on the Common Rail features and to improve performance and robustness. Works have been done as follows: study of the Common Rail system and development of the physical model ; development of strategies and command laws ; real tests on vehicle. Vehicle tests showed a high improvement on performance and robustness thanks to the new methodology based on the Common Rail features and the advanced command laws (H8 control for Linear Parameter Varying systems). In particular the Linear Fractional Transformation (LFT) approach has been considered

Over the last decade, an increase in earthquake occurrence in Oklahoma and Kansas has been linked to oilfield wastewater injection disposal, particularly into the regionally underpressured Arbuckle Group. The Arbuckle is hydraulically connected to Precambrian basement through an extensive fracture system, which transmits pressure perturbations from wastewater injections to seismogenic depths. Previous studies have convincingly attributed induced seismicity to pore pressure diffusion and solid elastic stressing, both resulting from fluid waste injection. Recent work adds to the physical understanding of injection-induced seismicity by demonstrating that the density differential between injection fluids and formation brines may also drive fluid pressure into the seismogenic basement. In this thesis, variable density groundwater flow is modeled in a numerical simulation comprising parts of the Anadarko Basin, the Anadarko Shelf, the Cherokee Platform, and the Nemaha Fault Zone as well as injection data from 2006-2018. Results show buoyancy forces interacting with regional stratigraphic dip to force density-driven pressure transients into the deep Anadarko Basin, aligning with previously unexplained earthquakes in that region.
Master of Science
Increased earthquake activity in Oklahoma and Kansas over the last decade is linked waste disposal related to hydrofracking. Oil and gas produced in the fracking process is often mixed with large amounts of water that is too salty to be used for public or industrial purposes, thus this water is disposed of via injection into deep rock layers in the upper portion of the Earth's interior, or crust. This injection disturbs the crust to trigger earthquakes where none have been historically observed. Previous studies examining this phenomenon assume that the rock layers of the crust lie flat and level; simplify the nature of major faults, or cracks, in the crust; and do not consider differences in water chemistry between injected water and water that already occupies the crust. The study developed in this thesis considers the effect of these three factors with regard to how they influence the extent of the linkage between waste water injection and earthquakes in Oklahoma and Kansas.

A computational study of sonic light-gas jet injection into a supersonic cross flow was conducted. The scope of the numerical analysis encompassed many studies that affect how the flow-field is numerically modeled and the behavior, specifically mixing, of the flow-field itself. A single, round injector was used for the Baseline design. Simulated conditions involved sonic injection of helium heated to 313 K into a Mach 4 air cross-stream with average Reynolds number 5.77 e+7 per meter and a freestream momentum flux ratio of 2.1. Experiments at these conditions were available for comparison. The primary numerical flow solver employed was GASP v. 4.2. The Menter Shear Stress Transport (SST) turbulence model was used, since the algorithm has good capability of solving both wall-bounded and free-shear flows. The SST model was able to capture the mixing behavior of the complex flow-field. Important numerical parameters that affect the capabilities of the numerical solver were studied for the Baseline injector. These sensitivity studies varied the choice of turbulent Prandtl number, Schmidt number, freestream turbulence intensity, boundary layer size, steady and unsteady approaches and computational software packages. A decrease in the turbulent Prandtl number resulted in better mixing behavior of the prediction and better agreement with the experiment. An increase in the turbulent Schmidt number had a small adverse effect on the predictions. The mixing characteristics remained constant with an increase in freestream turbulence intensity. The best Baseline prediction was then compared to three different injector configurations: an aerodynamic ramp consisting of four injectors in an array, a diamond injector both aligned and yawed 15° to the oncoming flow. The Computational Fluid Dynamics (CFD) tools were more accurate compared to experiment in the prediction of the aeroramp injector than the diamond-shaped injectors. The aeroramp injector slightly improved mixing efficiency over the Baseline injector at these conditions. Both of the diamond-shaped injectors had similar mixing as the Baseline injector but did not predict significant improvement in penetration for the analyzed conditions. Additional studies involving the interaction of transverse injection with impinging oblique shock waves were performed. The impingement of a shock upon light gas jet injection increased mixing. The closer the shock is to the injection point, the larger the effect on mixing and vorticity. The last analyses involved a numerical comparison of a non-reacting model to a reacting hydrogen-air model. The reacting analysis prediction had an improved spreading rate and larger counter-rotating vortex pair with downstream distance over the non-reacting analysis. The mixing was not significantly altered by the addition of hydrogen-air reactions to the numerical equations. The numerical tools used are capable of reasonable accuracy in predicting the complex flow-field of jet injection into a supersonic freestream with proper choice of models and parameters. Numerical modeling offers a way to study the entire flow-field thoroughly in a cost and time efficient manner.
Ph. D.

Thesis (Ph. D.)--Boise State University, 2006.
Includes abstract and vita. Includes bibliographical references (leaves 319-331). Also available online via the ProQuest Digital Dissertations database.

Thermoacoustic instabilities in modern high-performance, low-emission gas turbine engines are often observable as large amplitude pressure oscillations and can result in serious performance and structural degradations. These acoustic oscillations can cause oscillations in combustor through-flows and given the right phase conditions, can also drive unsteady heat release. This coupling has the potential to enhance the amplitude of pressure oscillations. To curb the potential harms caused by the existence of thermoacoustic instabilities, recent efforts have focused on the active suppression and even complete control of these instabilities. Intuitively, development of effective active combustion control methodologies is strongly dependent on the knowledge of the onset and sustenance of thermoacoustic instabilities. Specially, non-premixed spray combustion environment pose additional challenges due to the inherent unstable dynamics of sprays. The understanding of the manner in which the combustor acoustics affect the spray characteristics, which in turn result in heat release oscillation, is therefore, of paramount importance. The experimental investigations and the modeling studies conducted towards achieving this knowledge have been presented in this dissertation. Experimental efforts comprise both reacting and non-reacting flow studies. Reacting flow experiments were conducted on a overall lean direct injection, swirl-stabilized combustor rig. The investigations spanned combustor characterization and stability mapping over the operating regime. All experiments were performed under atmospheric pressure condition, which is considered as an obvious first step towards providing valuable insights into more intense processes in actual gas turbine combustors. The onset of thermoacoustic instability and the transition of the combustor to two unstable regimes were investigated via phase-locked chemiluminescence imaging and measurement and phase-locked acoustic characterization. It was found that the onset of the thermoacoustic instability is a function of the energy gain of the system, while the sustenance of instability is due to the in-phase relationship between combustor acoustics and unsteady heat release driven by acoustic oscillations. The presence of non-linearities in the system between combustor acoustic and heat release and also between combustor acoustics and air through-flow were found to exist. The impact of high amplitude limit-cycle pressure on droplet breakdown under very low mean airflow and the localized effects of forced primary fuel modulations on heat release were also investigated. The non-reacting flow experiments were conducted to study the spray behavior under the presence of an acoustic field. An isothermal acoustic rig was specially fabricated, where the pressure oscillations were generated using an acoustic driver. Phase Doppler Anemometry was used to measure the droplet velocities and sizes under varying acoustic forcing conditions and spray feed pressures. Measurements made at different locations in the spray were related to these variations in mean and unsteady inputs. The droplet velocities were found to show a second order response to acoustic forcing with the cut-off frequency equal to the relaxation time corresponding to mean droplet size. It was also found that under acoustic forcing the droplets migrate radially away from the spray centerline and show oscillatory excursions in their movement. Non-reacting flow experiments were also performed using Time-Resolved Digital Particle Image Velocimetry to characterize modulated sprays. Frequency response of droplet diameters were analyzed in the pulsed spray. These pilot experiments were conducted to assess the capability of the system to measure dynamic data. Modeling efforts were undertaken to gain physical insights of spray dynamics under the influence of acoustic forcing and to explain the experimental findings. The radial migration of droplets and their oscillatory movement were validated. The flame characteristics in the two unstable regimes and the transition between them were explained. It was found that under certain acoustic and mean air-flow condition, bands of high droplet densities were formed which resulted in diffusion type group burning of droplets. It was also shown that very high acoustic amplitudes cause secondary breakup of droplets.
Ph. D.

Aquifer storage and recovery (ASR) is a strategy in which water is injected into an aquifer when it is plentiful and pumped from the aquifer when water is scarce. An impediment to ASR in Florida is leaching of naturally-occurring arsenic from limestone of the Upper Floridan Aquifer System (UFAS) into stored water. The concentration of arsenic in surface water, which serves as the recharge water for many ASR systems, and native groundwater is usually much less than 3.0 µ/L. However, data from ASR wells in Florida show that arsenic in recovered water frequently exceeded the 10 µg/L maximum contaminant level (MCL) established by the Environmental Protection Agency and were as high as 130.0 µg/L. The cause of elevated arsenic concentrations is displacement of reduced native groundwater with oxygenated surface water that dissolves arsenic-bearing pyrite in limestone. Although arsenic can be removed from recovered water during final treatment, mobilization of arsenic in the aquifer at levels that exceed the MCL is problematic under federal regulations.

This dissertation investigated a number of aspects of the ASR/arsenic problem to provide additional insights into the mechanisms of arsenic mobilization and measures that could be taken to avoid or reduce the release of arsenic during ASR operations.

Chapter 2, involved development of a geochemical model to simulate an ASR system’s injection of oxygenated surface water into reduced groundwater to determine whether aquifer redox conditions could be altered to the degree of pyrite instability. Increasing amounts of injection water were added to the storage-zone in a series of steps and resulting reaction paths were plotted on pyrite stability diagrams. Unmixed storage-zone water in wells plotted within the pyrite stability field indicating that redox conditions were sufficiently reducing to allow for pyrite stability. Thus arsenic is immobilized in pyrite and its concentration in groundwater should be low. During simulation, as the injection/storage-zone water ratio increased, redox conditions became less reducing and pyrite became unstable. The result would be release of arsenic from limestone into storage-zone water.

Chapter 3 examined the importance of maintaining a substantial volume of stored water around an ASR well to prevent recovery of reduced native groundwater to the vicinity of the well. Depleting the stored water and recovering reduced native groundwater would result in dissolution of arsenic-bearing hydrous ferric oxide (HFO) and release of arsenic into water recovered from the ASR well. Injection/recovery volumes for each cycle for each well were tracked to determine if a substantial volume of stored water was maintained for each cycle or if it was depleted so that reduced native groundwater was brought back to the well. Each well was assigned to either the “storage zone maintained group” where a zone of stored water was established in early cycles and largely maintained through the period of investigation, or the “storage-zone depleted group” where a zone of stored water was either established in later cycles and/or was depleted during the period of investigation. Graphical and statistical analyses verified that maximum arsenic concentrations for storage-zone maintained wells were nearly always lower in each cycle and declined below the MCL after fewer cycles than those of storage-zone depleted wells.

Chapter 4 was a mineralogical investigation of cores located at 20 m (ASR core 1), 152 m (ASR core 2), and 452 m (ASR core 3) from operating ASR wells to determine where mobilized arsenic in limestone is precipitated during ASR. If arsenic is precipitated distally, reduced concentrations of elements in pyrite, (iron, sulfur, arsenic, etc.) would be expected in ASR core 1 relative to more distant cores and there would be noticeable changes in appearance of pyrite crystals due to enhanced oxidation. The results showed that mean concentrations of the elements were lowest in ASR core 2, which did not support distal precipitation. However, scanning electron microscopy identified well-defined pyrite framboids only in core 3 while framboids in ASR cores 1 and 2 were less clear and distinct, indicating pyrite oxidation in cores closest to ASR wells.

Statistical comparison of concentrations of iron, sulfur, and arsenic between the three ASR cores and 19 control cores not subject to ASR, showed that mean concentrations in ASR cores 1 and 2 were statistically similar to concentrations in control cores. This indicated that concentrations in ASR cores 1 and 2 had not been significantly reduced by ASR. The concentrations of elements were higher in ASR core 3 than in ASR cores 1 and 2 and control cores and statistically dissimilar to all but one control core. This indicated natural heterogeneity in core 3 rather than diminution of elements in ASR cores 1 and 2 due to ASR. The statistical analysis supported local precipitation. Once arsenic is mobilized from dissolved pyrite, it is rapidly complexed with precipitated HFO near the well. As long as all of the stored water is not removed during recovery so that reduced native groundwater is brought back to the well, HFO remains stable and complexed with arsenic. The concentration of elements would not have been lowest in ASR core 1 for this reason and because calculations showed that the mass of arsenic removed during recovery events prior to coring was minor compared to the total in limestone surrounding the well. The implications of this are that while large quantities of arsenic are present near the ASR well, only a small percentage may be available for dissolution. Most arsenic occurs with pyrite in limestone, which may insulate it from exposure to oxidized injection water. Water recovered from ASR wells may continue to have low concentrations of arsenic indefinitely because as limestone is dissolved, more pyrite becomes exposed and available for dissolution.

The primary contribution of this dissertation to understanding and overcoming the arsenic problem in ASR systems is the empirical data developed to support or challenge important ASR/arsenic hypotheses. These data were used to 1) establish that background concentrations of arsenic in groundwater of the Suwannee Limestone were less than 1µg/L, 2) demonstrate that redox conditions necessary for pyrite in limestone to become unstable and dissolve occur when oxygenated surface water is injected into the aquifer, 3) demonstrate that the concentration of pyrite in the Suwannee Limestone is spatially variable to a high degree, 4) support the hypothesis that following injection of oxygenated surface water, pyrite in limestone dissolves and releases arsenic into solution and HFO forms and complexes with the arsenic near the ASR well, 5) propose that only a small percentage of pyrite near an ASR well may be available for dissolution during each cycle because most occurs in the limestone matrix and is isolated from injection water, 6) propose that as a result of the previous conclusion, water recovered from ASR systems may continue to have low concentrations of arsenic indefinitely because as limestone that contains pyrite is dissolved with each cycle, additional pyrite is exposed and is available for dissolution, and 7) support the effectiveness of maintaining a zone of stored water in an ASR well as an effective means of minimizing arsenic in recovered water during ASR.

Ce mémoire présente le travail de recherche effectué pour la conception d'une stratégie de commande originale, destinée aux systèmes de puissance hybrides en sites isolés. Le système considéré, voué à l'alimentation électrique d'une habitation, comprend deux sources, un groupe de panneaux photovoltaïques et une petite éolienne, et deux types de stockage, un banc de batteries lithium-ion et un de supercondensateurs. Face au problème de gestion de l'énergie dans un système hybride, et aux enjeux de maximisation de sa puissance produite, nous proposons de développer une stratégie de commande basée sur les flux d'énergie. pour cela, nous présentons dans un premier temps les modélisations d'Euler-Lagrange et hamiltonienne du système. Ces modèles permettent d'utiliser la propriété de passivité de celui-ci, et ainsi de synthétiser des commandes par injection d'amortissement pour chaque source, afin de maximiser sa production, et pour les supercondensateurs, dans le but d'assurer une répartition cohérente des flux d'énergie entre eux et les batteries. Les commandes sont finalement mises en œuvre dans un simulateur, puis dans un banc d'essai expérimental, afin d'une part de comparer leurs performances à celles de solutions préexistantes, et d'autre part de valider le bon fonctionnement du système hybride complet les utilisant.

Background & Aims: Despite advances in surgical care and chemotherapeutic regimens, the five-year survival rate for Stage IV Hepatoblastoma (HB), the predominant pediatric liver tumor, remains at 27%. YAP1 and β-Catenin co-activation occurs in 80% of children’s HB; however, a lack of conditional genetic models precludes exploration of tumor maintenance and therapeutic targets. Thus, the clinical need for a targeted therapy remains unmet. Given the predominance of YAP1 and β-catenin activation in children’s tumors, I sought to evaluate YAP1 as a therapeutic target in HB. Approach & Results: Herein, I engineered the first conditional murine model of HB using hydrodynamic injection to deliver transposon plasmids encoding inducible YAP1S127A, constitutive β-CateninDelN90, and a luciferase reporter to murine liver. Tumor regression was evaluated using in vivo bioluminescent imaging, and tumor landscape characterized using RNA sequencing, ATAC sequencing and DNA foot-printing. Here I show that YAP1 withdrawal in mice mediates >90% tumor regression with survival for 230+ days. Mechanistically, YAP1 withdrawal promotes apoptosis in a subset of tumor cells and in remaining cells induces a cell fate switch driving therapeutic differentiation of HB tumors into Ki-67 negative “hbHep cells.” hbHep cells have hepatocyte-like morphology and partially restored mature hepatocyte gene expression. YAP1 withdrawal drives formation of hbHeps by modulating liver differentiation transcription factor (TF) occupancy. Indeed, tumor-derived hbHeps, consistent with their reprogrammed transcriptional landscape, regain partial hepatocyte function and can rescue liver damage in mice. Conclusions: YAP1 withdrawal, without modulation of oncogenic β-Catenin, significantly regresses hepatoblastoma, providing the first in vivo data to support YAP1 as a therapeutic target for HB. Modulating YAP1 expression alone is sufficient to drive long-term regression in hepatoblastoma because it promotes cell death in a subset of tumor cells and modulates transcription factor occupancy to reverse the fate of residual tumor cells to mimic functional hepatocytes.

End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the < cos2θ > for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting < cos2θ >. The breakage prediction improves if measured FLD of the extrudate is input into the model.

The process industries span multiple industrial sectors and constitute a substantial part of the entire manufacturing industry. Since companies belonging to this family of industries are often very asset intensive, their ability to respond to changes is often limited in the short term. The adaptation of the capabilities of existing processes, and conversely finding products and market segments to match the production system capabilities, are an important part of product- and market development activities in the process industry. The importance to companies in the process industry of having a well-articulated manufacturing strategy congruent with the business strategy is second to none. However, to facilitate manufacturing strategy developments, it is essential to start with an improved characterization and understanding of the material transformation system. To that end an extensive set of variables was developed and related measures and scales were defined. The resulting configuration model, focusing on company generic process capabilities in the process industries, is to be regarded as a conceptual taxonomy and as a proposition available for further testing. The usability of the model was subsequently assessed using “mini-cases” in the forestry industry, where the respondents confirmed that the company’s overall strategy could benefit from this kind of platform as a possible avenue to follow. The model was deployed as an instrument in the profiling of company material transformation systems to facilitate the further development of companies' functional and business strategies. The use of company-generic production capabilities was studied in three case companies representing the mineral, food and steel industries. The model was found by the respondents to be usable as a knowledge platform to develop production strategies. In the final analysis of the research results, a new concept emerged called “production capability configuration": A process-industrial company’s alignment of its generic production capabilities in the areas of raw materials, process technology and products to improve the consistency among the variable elements that define operations and improve the congruence between operations and its environment. From the perspective of value creation and capture, firms must be able to manufacture products in a competitive cost structure within the framework of a proper business model. By using the configuration model, the relationship between manufacturing and innovation activities has been studied in the previously mentioned three case studies. In many cases the gap in capability appears as a limitation in the production system, requiring development efforts and sometimes investments to overcome. This is illustrated with two examples from the steel industry, where development efforts of the production system capabilities are initiated to better match the market demands. One example is the increase the volume- and product flexibility of an existing stainless steel melt shop, resulting in a proposed oblong Argon Oxygen Decarburisation (AOD) converter configuration that was subsequently verified using water modelling. The second example is from a carbon steel mill, where the target was to increase the raw material- and volume flexibility of another melt shop, by modifying the capabilities of the Electric Arc Furnace (EAF). Enabling EAF technologies are further described and evaluated using operational data and engineering type of estimates.

QC 20170116

The World Health Organization (WHO) estimates that one billion people worldwide suffer from central nervous system (CNS) disorders [1]. One major issue in treating these disorders is inadequate drug penetration which can be attributed to an effective blood-brain-barrier that limits passage across blood vessels. Low diffusivity of large classes of drug compounds restricts transport across blood vessel walls and subsequent passage through surrounding brain tissues. Tissue transport is emerging as an increasingly important area of research in drug delivery since the vast majority of therapeutic agents must traverse this space before reaching their targets.

碩士
國立成功大學
高階管理碩士在職專班
92
Abstract In the late twentieth century, knowledge management has stepped in the spotlight to the world of business management. All trades and professionals are seeking to draw knowledge management and how to evaluate the effects of knowledge management. The writer is devoted to the injection molding industry now. But the injection molding industry gives people an impression of dirty mechanic worker. Most people believe workers in this industry are lowly educated; this impression in fact is not correct. In the making of module, massive amount of design drawings, industry designing, knowledge of mechanism processing, plastic and metallic natures are needed while applying physics, chemistry and mathematical concepts. Therefore, learning how to preserve duplicate and reuse this knowledge has become an issue to survival of the injection molding industry. The purpose of this research is to use the knowledge management theory as a basis and discuss when pragmatically carrying it out into the injection molding industry which steps and links be to watch out for. This research has discovered: 1. The injection molding industry relies on a master and apprentice system to pass on the necessary skills and knowledge. Although using different relationship, this serves the some function as modern high-tech industry that assigns senior personals to teach and lead fresh workers. 2. In the master/apprentice management mode, the organization culture and learning attitude can deeply affect the result of a case. This has to be taken special attention when carrying out knowledge management in the injection molding industry.

Geothermal energy is the energy naturally present inside the earth crust. When a large volume of hot water and steam is trapped in subsurface porous and permeable rock structure and a convective circulating current is set up, it forms a geothermal reservoir. A geothermal system can be defined as - convective water in the upper crust of earth, which transfers heat from a heat source (in the reservoir) to a heat sink, usually the free surface. A geothermal system is made up of three main elements: a heat source, a reservoir and a fluid, which is the carrier that transfers the heat. As an alternative source of energy geothermal energy has been under attention of the researchers for quite some time. The reason behind this is the existence of several benefits like clean and renewable source of energy which has considerable environmental advantage, with no chemical pollutants or wastes are generated due to geothermal emissions, and the reliability of the power resource. Hence research has been directed in several directions like exploration of geothermal resources, modeling the characteristics of different types of geothermal reservoirs and technologies to extract energy from them. The target of these models has been the prediction of the production of the hot water and steam and thus the estimation of the electricity generating potential of a geothermal reservoir in future years. In a geothermal power plant reinjection of the heat depleted water extracted from the geothermal reservoir has been a common practice for quite some time. This started for safe wastewater disposal and later on the technology was employed to obtain higher efficiency of heat and energy extraction. In most of the cases a very small fraction of the thermal energy present in the reservoir can be recovered without the reinjection of geothermal fluid. Also maintaining the reservoir pressure is essential which gradually reduces due to continuous extraction of reservoir fluid without reinjection, especially for reservoirs with low permeabilities. Although reinjection of cold-water has several benefits, the possibility of premature breakthrough of the cold-water front, from injection well zone to production well zone, reduces the efficiency of the reservoir operation drastically. Hence for maintaining the reservoir efficiency and longer life of the reservoir, the injectionproduction well scheme is to be properly designed and injection and extraction rates are to be properly fixed. Modeling of flow and heat transport in a geothermal reservoir due to reinjection of coldwater has been attempted by several researchers analytically, numerically and experimentally. The analytical models which exist in this field deal mostly with a single injection well model injecting cold-water into a confined homogeneous porous-fractured geothermal reservoir. Often the thermal conductivity is neglected in the analytical study considering it to be negligible which is not always so, as proved in this study. Moreover heterogeneity in the reservoir is also a major factor which has not been considered in any such analytical study. In the field of numerical modeling there also exists a need of a general coupled three-dimensional thermo-hydrogeological model including all the modes of heat transport (advection and conduction), the heat loss to the confining rocks, the regional groundwater flow and the geothermal gradient. No study existing so far reported such a numerical model including those mentioned above. The present study is concerned about modeling the non-isothermal flow and heat transport in a geothermal reservoir due to reinjection of heat depleted water into a geothermal reservoir. Analytical and numerical models are developed here for the transient temperature distributions and advancement of the thermal front in a geothermal reservoir which is generated due to the cold-water injection. First homogeneous geothermal aquifers are considered and later heterogeneities of different kinds are brought into picture. Threedimensional numerical models are developed using a software code DuMux which solves flow and heat transport problems in porous media and can handle both single and multiphase flows. The results derived by the numerical models have been validated using the results from the analytical models derived in this study. Chapter 1 of the thesis gives a brief introduction about different types of geothermal reservoirs, followed by discussion on the governing differential equations, the conceptual model of a geothermal reservoir system, the efficiency of geothermal reservoirs, the modeling and simulation concepts (models construction, boundary conditions, model calibration etc.). Some problems related with geothermal reservoirs and geothermal power is also discussed. The scenario of India in the context having a huge geothermal power potential is described and different potential geothermal sites have been pointed out. In Chapter 2, the concept of reinjection of the heat depleted (cold) water into the geothermal reservoir is introduced. Starting with a brief history of the geothermal reinjection, the chapter describes the purpose and the need of reinjection of geothermal fluid giving examples of different geothermal fields over the world where reinjection has been in practice and benefitted by that. The chapter further discusses on the problems and obstacles faced by the geothermal projects resulting from the geothermal reinjection, most important of which is the thermal-breakthrough and cooling of production wells. Lastly the problem of this thesis is discussed which is to model the transient temperature distribution and the movement of the cold-water thermal front generated due to the reinjection. The need of this modeling is elaborated which represents the motivation of taking up the problem of the thesis. Chapter 3 describes an analytical model developed for the transient temperature in a porous geothermal reservoir due to injection of cold-water. The reservoir is composed of a confined aquifer, sandwiched between rocks of different thermo-geological properties. The heat transport processes considered are advection, longitudinal conduction in the geothermal aquifer, and the conductive heat transfer to the underlying and overlying rocks of different geological properties. The one-dimensional heat transfer equation has been solved using the Laplace transform with the assumption of constant density and thermal properties of both rock and fluid. Two simple solutions are derived afterwards, first neglecting the longitudinal conductive heat transport and then heat transport to confining rocks. The analytical solutions represent the transient temperature distribution in the geothermal aquifer and the confining rocks and model the movement of the cold-water thermal front in them. The results show that the heat transport to the confining rocks plays an influential role in the transient heat transport here. The influence of some parameters, e.g. the volumetric injection rate, the longitudinal thermal conductivity and the porosity of the porous media, on the transient heat transport phenomenon is judged by observing the variation of the transient temperature distribution with different values of the parameters. The effects of injection rate and thermal conductivity have been found to be high on the results. Chapter 4 represents another analytical model for transient temperature distribution in a heterogeneous geothermal reservoir underlain and overlain by impermeable rocks due to injection of cold-water. The heterogeneity of the porous medium is expressed by the spatial variation of the flow velocity and the longitudinal effective thermal conductivity of the medium. Simpler solutions are also derived afterwards first neglecting the longitudinal conduction, then the heat loss to the confining rocks depending on the situation where the contribution of them to the transient heat transport phenomenon in the porous media is negligible. Solution for a homogeneous aquifer with constant values of the rock and fluid parameters is also derived with an aim to compare the results with that of the heterogeneous one. The effect of heat loss to the confining rocks in this case is also determined and the influence of some of the parameters involved, on the transient heat transport phenomenon is assessed by observing the variation of the results with different magnitudes of those parameters. Results show that the heterogeneity plays a major role in controlling the cold-water thermal front movement. The transient temperature distribution in the geothermal reservoir depends on the type of heterogeneity. The heat loss to the confining rocks of the geothermal aquifer also has influence on the heat transport phenomenon. In Chapter 5 another analytical model is derived for a heterogeneous reservoir where the heterogeneous geothermal aquifer considered is a confined aquifer consisted of homogeneous layers of finite length and overlain and underlain by impermeable rock media. All the different layers in the aquifer and the overlying and underlying rocks are of different thermo-hydrogeological properties. Results show that the advancement of the cold-water thermal front is highly influenced by the layered heterogeneity of the aquifer. As the cold-water thermal front encounters layers of different thermo-hydrogeological properties the movement of it changes accordingly. The analytical solution derived here has been compared with a numerical model developed by the multiphysics software code COMSOL which shows excellent agreement with each other. Lastly it is shown that approximation of the properties of a geothermal aquifer by taking mean of the properties of all the layers present will lead to erroneous estimation of the temperature distribution. Chapter 6 represents a coupled three-dimensional thermo-hydrogeological numerical model for transient temperature distribution in a confined porous geothermal aquifer due to cold-water injection. This 3D numerical model is developed for solving more practical problems which eliminate the assumptions taken into account in analytical models. The numerical modeling is performed using a software code DuMux as mentioned before. Besides modeling the three-dimensional transient temperature distribution in the model domain, the chapter investigates the regional groundwater flow has been found to be a very important parameter to consider. The movement of the thermal front accelerates or decelerates depending on the direction of the flow. Influence of a few parameters involved in the study on the transient heat transport phenomenon in the geothermal reservoir domain, namely the injection rate, the permeability of the confining rocks and the thermal conductivity of the geothermal aquifer is also evaluated in this chapter. The models have been validated using analytical solutions derived in this thesis. The results are in very good agreement with each other. In Chapter 7 the main conclusions drawn from the study have been enlisted and the scope of further research is also pointed out.

碩士
國立中央大學
機械工程學系
102
Metal–Organic Chemical Vapor Deposition, MOCVD, is one of the most important technologies to manufacture the LED. By introducing MO source and group V gas into the reactor, then deposits the thin film on the high temperature susceptor. The key components, a gas injection system and the reactor design, play a crucial role in the epitaxial growth rate and uniformity of thin film. In this study, we report a new method to predict the growth rate for Aixtron reactor. The prediction growth rate is in agreement with the previous reported result. In this paper, we also found that the radiation effect has a significant on the growth rate. Finally, we do the parameter analysis to realize the chamber characteristic for Aixtron reactor. Then, we design a new injection system that combines the barrier and purge design to enhance the growth rate and improve the uniformity without wafer spin. Additionally, the new design of MOCVD reactor could be used to epitaxy thin film at atmospheric pressure.

Pore scale interaction between matrix and fracture during miscible and immiscible CO2 injection was studied experimentally using visual models. Initially, visualization experiments were conducted on 2-D glass bead packed models by injecting n-heptane (solvent) displacing different kinds of processed oil. The focus was on the displacement patterns and solvent breakthrough controlled by matrix-fracture interaction and the pore scale behaviour of solvent-oil interaction for different fracture and injection conditions (rate, vertical vs. horizontal injection) as well as oil viscosity. Besides the visual investigation, effluent was also analyzed to calculate the solvent cut and oil recovery. Next, the process was modeled numerically using a commercial compositional simulator and the saturation distribution in the matrix was matched to the experimental data. The key parameters in the matching process were the effective diffusion coefficients and the longitudinal and transverse dispersivities. The diffusion coefficients were specified for each fluid and dispersivities were assigned into grid blocks separately for the fracture and the matrix. Finally, glass etched microfluidic models were used to investigate pore scale interaction between the matrix and the fracture. The models were prepared by etching homogeneous and heterogeneous micro scale pore patterns on glass sheets bonded together and then saturated with colored n-decane as the oleic phase. CO2 was injected at miscible and immiscible conditions. The focus was on visual pore scale analysis of miscibility, breakthrough of CO2 and oil/CO2 transfer between the matrix and the fracture under different miscibility, injection rate and wettability conditions.
Petroleum Engineering

Thesis (M. Sc.)--University of Alberta, 2009.
Title from pdf file main screen (viewed on July 27, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Petroleum Engineering, Department of Civil and Environmental Engineering, University of Alberta." Includes bibliographical references.

Dissertação de mestrado integrado em Engenharia Mecânica
Os modelos de ensino dentários são uma réplica à escala real da dentição e mandíbulas humanas, que são fundamentais para a formação de indivíduos na área da medicina dentária. A utilização de modelos dentários é portanto indispensável para os estudantes aprenderem a fazer um correto diagnóstico e para a determinação do plano de tratamento ortodôntico mais adequado a cada paciente. Tendo em conta o processo moroso de extração das réplicas dos dentes, foi pensado criar um sistema de fixação que garantisse a mesma fixação mas que não implicasse o usso de ferramentas adicionais para a sua remoção. Através dos ficheiros fornecidos pela empresa “Denteduco”, foram recriados os novos modelos de ensino dentário com recurso ao programa SolidWorks, elaborando assim, algumas versões do modelo final, ficando sempre a empresa responsável pela aceitação dos modelos elaborados. Com o decorrer do processo de criação 3D, os modelos dentários foram evoluindo na maneira como foram pensados e criados, quer a nível de detalhe quer a nível da forma final, havendo significativas diferenças entre as etapas do projeto. A solução final surge depois de várias etapas onde se definiu qual o sistema de fixação adequado e sua validação, qual o processo de fabrico e os materiais a usar para o novo projeto.
The dental teaching models are a real replica of human jaws and teeth which are crucial for training individuals in the field of dentistry. The using of a dental model is therefore essential to students learn how to do a correct diagnose and determination of a treatment plan for each patient. Regarding the long process of the teeth replicas extraction, was designed to create a new fastening system that guarantees de same fixture but do not involve the use of additional tools for their removal. Through the files provided by “Denteduco” company, were re-created the new teaching dental models by using Solid Works program, making some versions of final idea, always getting the company responsible for the acceptance of the models developed. In the course of the process of creating 3D dental models have evolved in the way they were designed and created, whether the level of detail both in terms of the final form, with significant differences between the stages of the project. The final solution comes after several steps which set on the proper attachment system and its validation, where the manufacturing process and the materials to use for the new project.

The thermal control of a die is crucial for the development of high efficiency injection moulds. For successful thermal management, this research provides an effective control strategy to find sensor locations, identify thermal dynamic models, and design controllers. By applying a clustering method and sensitivity analysis, sensor locations are identified. The neural network and finite element analysis techniques enable the modeling to deal with various cycle-times for the moulding process and uncertain dynamics of a die. A combination of off-line training through finite element analysis and training using on-line learning algorithms and experimental data is used for the system identification. Based on the system identification which is experimentally validated using a real system, controllers are designed using fuzzy-logic and self-adaptive PID methods with backpropagation (BP) and radial basis function (RBF) neural networks to tune control parameters. Direct adaptive inverse control and additive feedforward control by adding direct adaptive inverse control to self-adaptive PID controllers are also provided. Through a comparative study, each controller’s performance is verified in terms of response time and tracking accuracy under different moulding processes with multiple cycle-times. Additionally, the improved cooling effectiveness of the conformal cooling channel designed in this study is presented by comparing with a conventional straight channel.

Tese de Doutoramento em Engenharia Química e Biológica
The main objectives of this thesis were the development of model-based strategies for improving the performance of a high-cell density recombinant Escherichia coli fed-batch fermentation. The construction of a mathematical model framework as well as the derivation of optimal and adaptive control laws were used to accomplish these tasks. An on-line data acquisition system was also developed for an accurate characterization of the process and for the implementation of the control algorithms. The mathematical model of the process is composed of mass balance equations to the most relevant state variables of the process. Kinetic equations are based on the three possible metabolic pathways of the microorganism: glucose oxidation, fermentation of glucose and acetate oxidation. A genetic algorithm was used to derive the kinetic structure and to estimate both yield and kinetic coefficients of the model, minimizing the normalized quadratic differences between simulated and real values of the state variables. After parameter estimation, a sensitivity function analysis was applied to evaluate the influence of the various parameters on model behavior. Sensitivity functions revealed the sensitivity of the state variables to variations in each model parameter. Thus, essential parameters were selected and the model could be re-written in a simplified version that could also describe accurately experimental data. A system for the on-line monitoring of the major state variables was also developed. Glucose and acetate concentrations were measured with a developed Flow Injection Analysis system, while the carbon dioxide and oxygen transfer rates were calculated from data obtained with exhaust gas analysis. The fermentation culture weight was also continuously assessed with a balance, allowing the use of more precise mass-based concentrations, while environmental variables like pH, dissolved oxygen and temperatures were controlled and assessed via a Digital Control Unit. The graphical programming environment LabVIEW was used to acquire and integrate these variables in a supervisory computer, allowing the performance of integrated monitoring and control of the process. A model-based adaptive linearizing control law was derived for the regulation of acetate concentration during fermentations. The non-linear model was subjected to transformations in order to obtain a linear behavior for the control loop when a non-linear control is applied. The implementation of the control law was performed through a C script embedded in the supervisory LabVIEW program. Finally, two optimization techniques for the maximization of biomass concentration were compared: a first order gradient method and a stochastic method based on the biological principle of natural evolution, using a genetic algorithm. The former method revealed less efficient concerning to the computed maximum, and dependence on good initial values.
A presente tese teve como principais objectivos o desenvolvimento de estratégias baseadas em modelos para melhorar o desempenho da fermentação em modo semi-continuo em altas densidades celulares de Escherichia coil recombinada. Para o efeito, foi construído um modelo matemático representativo do processo e a partir deste foram desenvolvidos algoritmos de controlo óptimo e adaptativo. De forma a possibilitar a implementação de leis de controlo em linha e a caracterização do processo fermentativo, foi desenvolvido um sistema informático de aquisição e envio de dados. O modelo matemático representativo do processo em estudo foi elaborado tendo por base as equações dinâmicas de balanço mássico para as variáveis de estado mais relevantes, contemplando as três possíveis vias metabólicas do microrganismo. A estrutura cinética, bem como os parâmetros do modelo foram determinados por recurso a uma abordagem sistemática tendo por base a minimização das diferenças quadráticas entra dados reais e dados simulados, com recurso a uma ferramenta de optimização estocástica denominada de Algoritmos Genéticos. Após a etapa de identificação do modelo matemático, foram calculadas as sensibilidades relativas ao longo do tempo das variáveis de estado do modelo relativamente aos vários parâmetros determinados. Os resultados desta análise de sensibilidade possibilitaram avaliar a relevância de cada um dos parâmetros em causa, permitindo propor uma estrutura de modelo menos complexa, por exclusão dos parâmetros menos importantes. O sistema elaborado para a aquisição e envio em linha de dados da fermentação inclui um sistema de FIA (Flow Injection Analysis) desenvolvido para a medição das concentrações de acetato e glucose, uma unidade de controlo digital que controla as variáveis físicas mais relevantes para o processo, e um equipamento de Espectrometria de Massas para analisar as correntes gasosas de entrada e saída do fermentador. O sistema dispõe ainda de duas balanças, uma das quais para a aferição em linha do peso do caldo de fermentação, permitindo o use de concentrações mássicas que proporcionam resultados mais exactos. A aquisição e integração destas variáveis medidas são, efectuadas através de um software de supervisão elaborado no ambiente de programação gráfico LabVIEW. Adicionalmente, foi elaborada uma lei de controlo adaptativo linearizante para a regulação da concentração de acetato no meio de fermentação. A síntese da lei de controlo não linear foi efectuada por técnicas de geometria diferencial com linearização do sistema por retroacção de estado. A adaptação foi feita tendo por base a estimação de parâmetros variáveis no tempo, nos quais se concentram as incertezas do modelo. A implementação ao processo real da referida lei de controlo foi efectuada por recurso a um programa elaborado em C incluindo no programa supervisor elaborado em LabVIEW. Finalmente, para a optimização da quantidade de biomassa formada no final da fermentação por manipulação do caudal de alimentação, foram estudadas duas ferramentas de optimização: um método de gradiente e uma ferramenta baseada em Algoritmos Genéticos. Esta última revelou-se mais eficaz tanto na convergência para o valor óptimo, como na estimativa inicial fornecida.
Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI/16961/98.
União Europeia - Fundo Social Europeu (FSE) – III Quadro Comunitário de Apoio (QCA III).
Fundação Calouste Gulbenkian (FCQ) - Educação e Bolsas.
Agência de Inovação (ADI) - PROTEXPRESS.