The focus of this thesis was conducting experiments which would help in understanding mechanisms and in design of surfactant enhanced oil recovery (EOR) processes in various scenarios close to reservoir conditions such as heterogeneity, effects of crude oil, wettability, etc. Foam generated in situ by surfactant alternating gas injection was demonstrated as a substitute for polymer drive in a 1-D FOR process. It was effective in a similar process for a 266 cp crude oil even though the system did not have favorable mobility control. Foam enhanced sweep efficiency in a layered sandpack with a 19:1 permeability ratio. Foam diverted surfactant from the high- to the low-permeability layer. Ahead of the foam front, liquid in the low-permeability layer crossflowed into the high-permeability layer. Foam completely swept the system in 1.3 TPV (total pore volume) fluid injection while waterflood required 8 TPV. When the same 2-D system was oil-wet, the recovery by watertlood was only 49.1% of original oil-in-place (OOIP) due to injected water flowing through high-permeability zone leaving low-permeability zone unswept. To improve recovery, an anionic surfactant blend (NI) was injected that altered the wettability and lowered the interfacial tension (IFT) and consequently enabled gravity and capillary pressure driven vertical counter-current flow to occur and exchange fluids between layers during a 42-day system shut-in. Cumulative recovery after a subsequent foamflood was 94.6% OOIP. The addition of lauryl betaine to NI at a weight ratio of 2:1 made the new NIB a good IFT-reducing and foaming agent with crude oil present. It showed effectiveness in water-wet homogeneous and oil-wet heterogeneous sandpacks. The unique attribute of foam with higher apparent viscosity in high- than in low-permeability regions makes it a better mobility control agent than polymer in heterogeneous systems. One single surfactant formulation such as NIB in this study that can simultaneously reduce IFT and generate foam will improve the microscopic displacement and sweep efficiency from the beginning of a chemical flooding process. Foam generation mechanisms, alkaline/surfactant processes, and foam stability in presence of crude oil were investigated in a glass micro model. Total acid number measurement with spiking method was discussed.

No description available.

Drift tube ion mobility spectrometry (IMS) is a powerful, post-ionization separation that yields structural information of ions through an ion-neutral collision cross section. The ion-neutral collision cross section is governed by the collision frequency of the ion with the neutral drift gas. Consequently, ions of different size will have different collision frequencies with the gas and be separated in the drift cell. A significant challenge for IMS, however, is to separate ions with very similar collision cross sections, requiring higher resolution ion mobility spectrometers. Resolution in IMS is of utmost importance for the separation of complex mixtures, e.g. crude oil samples, proteolytic digests, positional isomers, and ion conformers. However, most methods employed to increase mobility resolution significantly decrease ion transmission through the mobility device. Herein, a periodic-focusing DC ion guide drift cell (PDC IG) is presented to display its potential capabilities for higher mobility resolution with increased ion transmission. The PDC IG utilizes unique electrode geometry compared to the conventional uniform field electrode design. Electrode geometry can be defined by the electrode inner diameter (d), thickness (t), and spacing (s). Specifically, the ratio of d : t : s is equal to, or very near, 1:1:1. The PDC IG electrode design creates a non-uniform (fringing) electric field-especially near the electrode walls. The design also causes variations in the radial electric field which provides an effective RF as ions move through the device and a radially confining effective potential that improves ion transmission through the device. In this dissertation the analytical utility of the PDC IG drift cell for ion mobility separations will be explored. The radial focusing properties of the device will be presented along with studies of electrode geometry and its effect on ion mobility resolution and ion transmission through the drift cell. PDC IG drift cell length is also examined to determine its effect on mobility resolution and ion transmission. Finally, the PDC IG drift cell device is coupled to an orthogonal-acceleration time-of-flight mass spectrometer as well as a modular, PDC IG drift cell being adapted to a commercial qTOF mass spectrometer for IM-MS experiments.

This dissertation contains three essays. The first and second essays examine intergenerational mobility in earnings in Brazil using a data set spanning three generations. I use data from PNAD{a nationally representative household survey in Brazil. I build a three-generations data set consisting of 5,125 grandfather-father- son triplets by restricting the sample to households with adult sons. The first essay estimates some relationships between a child's earnings and family background implied by the Becker-Tomes model. I find that the estimates contradict some of its predictions, like the negative relationship between child's earnings and grandparent's earnings when controlling for parent's earnings. I propose a modified version of the Becker-Tomes model and find that the estimates are consistent with its predictions. I find that family background explains 34.9% of the variation in earnings among young males who live with their parents. If it were possible to eliminate the differences in investment in the children's human capital, the variation in earnings would fall by no more than 21.1%. Additionally, if there were no differences in endowments among children, the variation in earnings would fall by no less than 26%. The second essay examines the evolution of the intergenerational elasticity across generations and im- plications of marriage, education and fertility on mobility. I find that the estimate of the intergenerational elasticity in earnings is 0.847. The elasticity of earnings between son-in-law and father-in-law, 0.89, is approximately the same as the elasticity between son and father, 0.9. Additionally, controlling for fathers' percentile in the earnings distribution, each additional sibling decreases the sons' percentile by 1.77 percentiles. The third essay estimates an indicator of the optimal investment in electricity generation in Texas, and the associated efficiency gains. The essay presents a method to estimate the optimal investment in each technology available to generate electricity. The estimation considers the expected entry and exit of generation plants, future fuel prices, different demand elasticities and a potential carbon allowance mar- kets. Considering a carbon allowance price equal to two times the level in Europe, the optimal investment in electricity generation in Texas is zero.

Drift time ion mobility spectrometry (DTIMS) is a rapid post ionization gas-phase separation technique that distinguishes between compounds based on their differences in reduced mass, charge and collisional cross-section while under a weak, time-invariant electric field. Standalone DTIMS is currently employed throughout the world for the detection of explosives, drugs and chemical-warfare agents. The coupling of IMS to MS (IM-MS) has enabled the performance of time-nested multidimensional separations with high sample throughput and enhanced peak capacity, allowing for the separation of ions not only based on their mass/charge (m/z) ratios, but also their shape. This allows for the elucidation of valuable structural information that can be utilized for determining gas phase ion conformation and differentiation between closely related ionic species. Over the past decade, these advances have transformed IM-MS applications and instrumental designs into one of the most rapidly growing areas of mass spectrometry. The work presented in this thesis is aimed at the development and subsequent characterization of a novel high-resolution resistive-glass atmospheric pressure DTIMS, and the application of this prototype DTIMS to the detection of environmentally relevant compounds. A review of the different types of ion mobility spectrometers, their principles of operation, and the advantages and disadvantages of each type are presented in Chapter 1. Chapter 2 describes the design and development of our prototype resistive glass DTIMS. A detailed description of the IMS hardware, including the ion sources, custom-built control computer, pulsing electronics, data acquisition system, and the timing schemes developed to operate the instrument in standalone DTIMS, multiplexed DTIMS, and IM-MS mode, are presented. Chapter 3 presents an initial characterization of the performance of a prototype resistive glass DTIMS under a wide range of instrumental parameters and also characterizes the radial ion distribution of the ions in the drift region of the spectrometer. Chapter 4 addresses the lack of sensitivity in DTIMS and explores ion trapping and multiplexing methods, introduces the principles of multiplexing and describes an extended multiplexing approach that encompasses arbitrary binary ion injection waveforms with variable duty cycles. Chapter 5 presents a detailed theoretical and experimental study of the separation power of our DTIMS and presents an evaluation of the field homogeneity and the performance of the ion gate.

In this thesis, we study the physical properties of doped organic semiconductors. We first demonstrate the impact of doping on C60 films. In contrast to previous reports for organic thin films, the n-doped C60 films show a decrease of mobility with increasing doping levels; i.e., they follow the well-known Matthiessen rule which is generally observed in inorganic semiconductors. Using further strong organic donors and acceptors, we realize p-i-n homojunctions of several organic matrices: zinc-phthalocyanine, pentacene, and an iridium-complex TER004. We observe stable and reproducible diode characteristics, which can be described by the standard Shockley theory with an exception concerning the temperature dependence of the diode parameters. The current-voltage characteristics of the pentacene homojunctions under illuminated conditions indicate that the thermodynamic limitation of the open-circuit voltage is determined by the built-in voltage of 1.65 V, and that the recombination process is influenced by the distinct charge transport properties of electrons and holes. The very high built-in voltage of 2.2 V in the TER004 homojunction allows a red phosphorescent homo-OLED, which shows visible emission around 650 nm with low operation voltage. We examine the charge balance status in the homojunction structure, revealing that TER004 has superior electron transport properties.

Thèse (Ph. D.)--Université Laval, 2000. / Comprend des réf. bibliogr.

Thesis (M. Soc. Sc.)--University of Hong Kong, 1982.

Electric mobility scooters are increasing in popularity and are used extensively by individuals with mobility impairments to conduct activities of daily living. Scientific literature on the safety and efficacy of scooters in winter conditions is sparse and the current technical standards for scooters do not mandate testing in these conditions. This study paves the way for more rigorous standard testing by: 1) Describing a novel, motion-capture based method to quantify the tractive performance of scooters; 2) Describing methods to create a wide variety of simulated winter conditions; 3) Presenting pilot-test results of a scooter driven in these winter conditions. The outcomes of this study are significant because it is the first study to evaluate the performance of a scooter in winter conditions. Furthermore, it constitutes the first phase of a broader initiative to develop a rigorous, new winter test method for scooters and drive improvements in safety, performance and design.

Electric mobility scooters are increasing in popularity and are used extensively by individuals with mobility impairments to conduct activities of daily living. Scientific literature on the safety and efficacy of scooters in winter conditions is sparse and the current technical standards for scooters do not mandate testing in these conditions. This study paves the way for more rigorous standard testing by: 1) Describing a novel, motion-capture based method to quantify the tractive performance of scooters; 2) Describing methods to create a wide variety of simulated winter conditions; 3) Presenting pilot-test results of a scooter driven in these winter conditions. The outcomes of this study are significant because it is the first study to evaluate the performance of a scooter in winter conditions. Furthermore, it constitutes the first phase of a broader initiative to develop a rigorous, new winter test method for scooters and drive improvements in safety, performance and design.