Air sparging is a technique used to remediate gasoline contamination. In sparging, air is injected below the target zone and removes contamination via two separate mechanisms; volatilization and biodegradation. In volatilization, the air contacts the contamination as it moves upward. The contaminant will partition to the vapor phase based on its volatility and will be removed as the air reaches the atmosphere. For biodegradation, the oxygen in the airstream is used for microbial activity. Pulsed air sparging, otherwise known as pulsed biosparging, has been found to be more effective than continuous air sparging. Pulsed biosparging enhances treatment because it induces groundwater movement and mixing. The general mechanisms for treatment of gasoline sources using air sparging are relatively well characterized. However, air flow through the subsurface and the total hydrocarbon mass lost are difficult to predict and quantify. This project was intended to quantify the mass lost through volatilization and through biodegradation at the E10 gasoline source using pulsed biosparging, and to determine the effect of the source zone removal on downgradient dissolved BTEX concentrations. The remedial system consisted of two major components: the air sparging system, with three injection points; and a soil gas collection system. The soil gas collection system was comprised of an airtight box that covered the source area and the monitoring wells upgradient and downgradient of the source. Off-gas from the soil gas collection system was monitored continuously using a PID. The off-gas was also sampled frequently for BTEX, pentane, and hexane to determine the hydrocarbon mass removed; and for O2 and CO2 to determine biodegradation rates. The remedial system ran for approximately 280 hours over 33 days. Of the estimated 22.3 kg of gasoline residual in the source zone, 4.6 kg or 21% of the residual was removed via volatilization and 4.9 kg or 22% of the residual was removed via biodegradation. Leakage outside the system was estimated at less than 0.1% of the total mass. Groundwater samples were collected when the last sparged air was calculated to arrive at the row 2 downgradient fence. The average BTEX groundwater concentration after sparging was 40% of the pre-sparging concentration. The benzene mass discharge decreased 27%, the ethylbenzene mass discharge decreased 65%, the p/m-xylene mass discharge decreased 6%, and the o-xylene mass discharge decreased 5%. The mass discharge for naphthalene and TMB isomers increased 19%. However, these values fit in with long-term groundwater concentration trends. Additional sampling is recommended to determine if the sparging made a significant impact on mass discharge leaving the source.

This study aims to evaluate the ability of high-frequency (450 and 900 MHz) ground-penetrating radar (GPR) to monitor the effects of an ethanol release over an existing gasoline-contaminated zone. In September 2009, 184L of denatured ethanol mixture (E95) was released into an unconfined sand aquifer directly over gasoline residuals (E10) released the previous year. GPR profiling prior to the ethanol release indicated that the residual gasoline-contaminated zone was largely confined to its initial release point. The GPR profiling performed post ethanol release observed strong shallow reflection events which propagated laterally away from the trench over a one-month period, at which point the maximum extent was established. The effects of the ethanol were also observed with the 450MHz frequency, in the form of an apparent “velocity pull-up” of a stratigraphic reflector. After the initial expansion, reduction in reflection amplitude and increasing traveltimes within the trench, were observed until the onset of winter conditions and the development of frozen soil. Over the winter the presence of ethanol inhibited the freezing process of the pore water in the contaminated zone, thus resulting in a difference in the dielectric properties of the unfrozen verse frozen zone. The unfrozen zone was significantly greater than the spatial extent of the strong reflection events that were monitored through GPR prior to winter. The spatial extent and depth of the unfrozen zone imaged by the GPR profiling was confirmed by a physical impedance depth survey. After thaw, evidence of the ethanol or gasoline was absent until mid-summer, when the water table dropped to approximately 80cm. At this point strong reflection events were again observed throughout the contaminated zone.

This dissertation consists of three essays. Chapter II examines the possible asymmetric response of gasoline prices to crude oil price changes using an error correction model with GARCH errors. Recent papers have looked at this issue. Some of these papers estimate a form of error correction model, but none of them accounts for autoregressive heteroskedasticity in estimation and testing for asymmetry and none of them takes the response of crude oil price into consideration. We find that time-varying volatility of gasoline price disturbances is an important feature of the data, and when we allow for asymmetric GARCH errors and investigate the system wide impulse response function, we find evidence of asymmetric adjustment to crude oil price changes in weekly retail gasoline prices Chapter III discusses the relationship between fiscal deficit and exchange rate. Economic theory predicts that fiscal deficits can significantly affect real exchange rate movements, but existing empirical evidence reports only a weak impact of fiscal deficits on exchange rates. Based on US dollar-based real exchange rates in G5 countries and a flexible varying coefficient model, we show that the previously documented weak relationship between fiscal deficits and exchange rates may be the result of additive specifications, and that the relationship is stronger if we allow fiscal deficits to impact real exchange rates non-additively as well as nonlinearly. We find that the speed of exchange rate adjustment toward equilibrium depends on the state of the fiscal deficit; a fiscal contraction in the US can lead to less persistence in the deviation of exchange rates from fundamentals, and faster mean reversion to the equilibrium. Chapter IV proposes a kernel method to deal with the nonparametric regression model with only discrete covariates as regressors. This new approach is based on recently developed least squares cross-validation kernel smoothing method. It can not only automatically smooth the irrelevant variables out of the nonparametric regression model, but also avoid the problem of loss of efficiency related to the traditional nonparametric frequency-based method and the problem of misspecification based on parametric model.

Abstract After the ban against private-owned gas service stations was lifted in 1987, some domestic trading firms took advantage of the special feature of gasoline products as well as Taiwan¡¦s unique oil price structure to import low-quality oil products for blending into gasoline-equivalent products, which would then be sold to independent service station owners mushrooming in accordance with the oil market deregulation. According to the statistics of import/export at Taiwan customs and the comparison between supply and demand of relative industries, it is agreed that an annual total of approximate 400,000 kiloliters of various imported oil products would be blended into gasoline or diesels for sale. Moreover, as Taiwan government has been continuously providing a 14% oil price subsidy against a sluggish fishing industry caused by depleting fishing resources, the fishing fuels in glut, at an estimate of 410, 000 kiloliters a year, would be illegally sold as diesel in domestic gas service stations for higher profits. These practices have not only directly affected tax revenues of local governments, but also infringed upon the legal rights of petroleum refineries, putting the orderliness of petroleum production and sale in jeopardy. In addition, as such illicit practices are usually carried out near makeshift storage tanks with ineligible filling facilities, they have posed great threats to public safety and environment. As it is difficult to detect and thereby root out the underground transactions of such inferior gasoline and diesels, the police that was authorized insufficiently on legal aspects would carry out inspections at key roads and intersections only passively, which has posed but limited intimidation over illegal transactions of unqualified gasoline products. Realizing the facts, this survey takes the historical data on relative factors and market survey figures as basis for calculation and analysis, which is used then to assume the normal demand of gasoline and diesel markets and to establish a conclusive alarming model for flow direction. Besides, it obtains affecting variables such as market segmentation, channel characteristics, customer behaviors, price gap and business environments through interviews and questionnaires, to determine limits on the alarming model and the alarming value. Comparing with the actual consumption of gasoline and diesels, we can then judge if there remains any abnormality concerning the sales volume of gasoline and diesels. If any abnormal sign shown, we can check the alarming model item by item for timely management and control, so as to supervise and check the underground transactions of inferior gasoline and diesels. We also hope that the survey report on ¡§the Alarming Model over the Flow of Inferior Gasoline and Diesels and Its Application¡¨ could provide practical references for the detection and elimination of inferior gasoline and diesels so that the illicit and unsafe practice could be inhibited once and for all.

Anticipating changes to public transportation ridership demand is important to planning for and meeting service goals and maintaining system viability. These changes may occur in the short- or long-term; extensive academic work has focused on bettering long-term forecasting procedures while improvements to short-term forecasting techniques have not received significant academic attention. This dissertation combines traditional forecasting approaches with multivariate regression to develop a transferable short-term public transportation ridership forecasting model that incorporates fuel price as a prediction parameter. The research herein addresses 254 US transit systems from bus, light rail, heavy rail, and commuter rail modes, and uses complementary methods to account for seasonal and non-seasonal ridership fluctuations. Models were built and calibrated using monthly data from 2002 to 2007 and validated using a six-month dataset from early 2008. Using variable transformations, classical data decomposition techniques, multivariate regression, and a variety of forecasting model validation measures, this work establishes a benchmark for future research into transferable transit ridership forecasting model improvements that may aid public transportation system planners in an era when, due to fuel price concerns, global warming and green initiatives, and other impetuses, transit use is seeing a resurgence in popularity. / text

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Membrane technology is a potential method for upgrading gasoline quality, with respect to its tendency to promote fouling of engine inlet-systems. This thesis investigates the transport and separation mechanisms of dense polydimethylsiloxane (PDMS) membranes in nanofiltration applications relating to the filtration of gasoline fuels. Simulated fuels were created which comprised representative organic solvents with organometallic and poly-nuclear aromatic solutes. The flux and separation behaviour of the solvent-solute systems were studied using several apparatus and a range of operating regimes. Tests were performed with real fuels and refinery components to verify the mechanisms observed with the model solvent-solute systems, and several strategies were developed by which the process could be optimised or improved. Parallel to this work, a project was undertaken to assess the suitability of the technology on an industrial scale and to identify any scale-up issues. The key factors influencing flux were found to be the viscosity and swelling-effect of the solvent or solvent mixture. The dense membrane was shown to exhibit many characteristics of a porous structure when swollen with solvents, with the separation of low-polarity solutes governed principally by size-exclusion. It is postulated that swelling causes expansion of the polymer network such that convective and diffusive flow can take place between polymer chains. In general terms, a higher degree of swelling resulted in a higher flux and lower solute rejection. The separation potential of the membrane could be partly controlled by changing the swelling-effect of the solvent and the degree of membrane crosslinking. The transport of polar/non-polar solvent mixtures through PDMS was influenced by swelling equilibria, with separations occurring upon swelling the membrane. Separation of the more polar solvent occurred in this manner, and the solute rejection in multicomponent polar/non-polar mixtures deviated significantly from the behaviour in binary mixtures. The results obtained from a pilot-plant scale apparatus were largely consistent with those from laboratory-scale equipment, and engine tests showed that fuel filtration with PDMS is a technically-viable means of upgrading gasoline quality.

This study aims to evaluate the ability of high-frequency (450 and 900 MHz) ground-penetrating radar (GPR) to monitor the effects of an ethanol release over an existing gasoline-contaminated zone. In September 2009, 184L of denatured ethanol mixture (E95) was released into an unconfined sand aquifer directly over gasoline residuals (E10) released the previous year. GPR profiling prior to the ethanol release indicated that the residual gasoline-contaminated zone was largely confined to its initial release point. The GPR profiling performed post ethanol release observed strong shallow reflection events which propagated laterally away from the trench over a one-month period, at which point the maximum extent was established. The effects of the ethanol were also observed with the 450MHz frequency, in the form of an apparent “velocity pull-up” of a stratigraphic reflector. After the initial expansion, reduction in reflection amplitude and increasing traveltimes within the trench, were observed until the onset of winter conditions and the development of frozen soil. Over the winter the presence of ethanol inhibited the freezing process of the pore water in the contaminated zone, thus resulting in a difference in the dielectric properties of the unfrozen verse frozen zone. The unfrozen zone was significantly greater than the spatial extent of the strong reflection events that were monitored through GPR prior to winter. The spatial extent and depth of the unfrozen zone imaged by the GPR profiling was confirmed by a physical impedance depth survey. After thaw, evidence of the ethanol or gasoline was absent until mid-summer, when the water table dropped to approximately 80cm. At this point strong reflection events were again observed throughout the contaminated zone.

In this dissertation, three related issues concerning empirical time series models for energy financial markets and the stock market were investigated. The purpose of this dissertation was to analyze the interdependence of price movements, focusing on the forecasting models for crude oil prices and the hedging models for gasoline prices, and to study the change in the contemporaneous causal relationship between investors' activities and stock price movements in the Korean stock market. In the first essay, the nature of forecasting crude oil prices based on financial data for the oil and oil product market is examined. As crack spread and oil-related Exchange-Traded Funds (ETFs) have enabled more consumers and investors to gain access to the crude oil and petroleum products markets, I investigated whether crack spread and oil ETFs were good predictors of oil prices and attempted to determine whether crack spread or oil ETFs were better at explaining oil price movements. In the second essay, the effectiveness of diverse hedging models for the unleaded gasoline price is examined using futures and ETFs. I calculated the optimal hedge ratios for gasoline futures and gasoline ETF utilizing several advanced econometric models and then compared their hedging performances. In the third essay, the contemporaneous causal relationship between multiple players' activities and stock price movements in the Korean stock market was investigated using the framework of a DAG model. The causal impacts of three players' activities in regard to stock return and stock price volatility are examined, concentrating on foreign investor activities. Within this framework, two Korean stock markets, the KSE and KOSDAQ markets, are analyzed and compared. Recognizing the global financial crisis of 2008, the change in casual relationships was examined in terms of pre- and post-break periods. In conclusion, when a multivariate econometric model is developed for multi-markets and multi-players, it is necessary to consider a number of attributes on data relations, including cointegration, causal relationship, time-varying correlation and variance, and multivariate non-normality. This dissertation employs several econometric models to specify these characteristics. This approach will be useful in further studies of the information transmission mechanism among multi-markets or multi-players.

Diss. (sammanfattning) Umeå : Umeå universitet, 2008. / Härtill 4 uppsatser.