Thesis (Ph.D.)--University of California, Berkeley, 2009. / Text document in PDF format. Title from PDF title page (viewed on April 3, 2010). "Fall, 2009." Includes bibliographical references (p. 84-90).

Thesis (Ph. D.)--Cornell University, 1928. / The first article is from the University of the Philippines Natural and applied science bulletin, v. 1, no. 3, July, 1931 and the second ("Experiment station contribution no. 742") from the Philippine agriculturist, v. 20.

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 380-[414]).

Thesis (M. Sc.)--University of Hong Kong, 1997. / Includes bibliographical references.

General aviation in the United States has been an important part of the economy and American life. General aviation is defined as all flying excluding military and scheduled airline operations, and is utilized in many areas of our society. The majority of aircraft operations and airports in the United States are categorized as general aviation, and general aviation contributes more than one percent to the United States gross domestic product each year. Despite the many benefits of general aviation, the lead emissions from aviation gasoline consumption are of great concern. General aviation emits over half the lead emissions in the United States or over 630 tons in 2005. The other significant negative externality attributed to general aviation usage is aircraft accidents. General aviation accidents have caused over 8000 fatalities over the period 1994 - 2006. A recent Federal Aviation Administration proposed increase in the aviation gasoline tax from 19.4 to 70.1 cents per gallon has renewed interest in better understanding the implications of such a tax increase as well as the possible optimal rate of taxation. Few studies have examined aviation fuel elasticities and all have failed to study general aviation fuel elasticities. Chapter one fills that gap and examines the elasticity of aviation gasoline consumption in United States general aviation. Utilizing aggregate time series and dynamic panel data, the price and income elasticities of demand are estimated. The price elasticity of demand for aviation gasoline is estimated to range from -0.093 to -0.185 in the short-run and from -0.132 to -0.303 in the long-run. These results prove to be similar in magnitude to automobile gasoline elasticities and therefore tax policies could more closely mirror those of automobile tax policies. The second chapter examines the costs associated with general aviation accidents. Given the large number of general aviation operations as well as the large number of fatalities and injuries attributed to general aviation accidents in the United States, understanding the costs to society is of great importance. This chapter estimates the direct and indirect costs associated with general aviation accidents in the United States. The indirect costs are estimated via the human capital approach in addition to the willingness-to-pay approach. The average annual accident costs attributed to general aviation are found to be $2.32 billion and $3.81 billion (2006 US$) utilizing the human capital approach and willingness-to-pay approach, respectively. These values appear to be fairly robust when subjected to a sensitivity analysis. These costs highlight the large societal benefits from accident and fatality reduction. The final chapter derives a second-best optimal aviation gasoline tax developed from previous general equilibrium frameworks. This optimal tax reflects both the lead pollution and accident externalities, as well as the balance between excise taxes and labor taxes to finance government spending. The calculated optimal tax rate is $4.07 per gallon, which is over 20 times greater than the current tax rate and 5 times greater than the Federal Aviation Administration proposed tax rate. The calculated optimal tax rate is also over 3 times greater than automobile gasoline optimal tax rates calculated by previous studies. The Pigovian component is $1.36, and we observe that the accident externality is taxed more severely than the pollution externality. The largest component of the optimal tax rate is the Ramsey component. At $2.70, the Ramsey component reflects the ability of the government to raise revenue aviation gasoline which is price inelastic. The calculated optimal tax is estimated to reduce lead emissions by over 10 percent and reduce accidents by 20 percent. Although unlikely to be adopted by policy makers, the optimal tax benefits are apparent and it sheds light on the need to reduce these negative externalities via policy changes.

In response to the global concerns towards oil scarcity and climate change, the automotive industry is currently focusing on improving fuel economy and reducing exhaust emissions. Modern downsized gasoline engines that come with a package that includes a boosting system, variable valve train and direct fuel injection system is effective for fuel economy improvement and emission reduction. However, the knocking issue becomes severe at high load operations as a result of the high intake boosting pressure. In regard to the part load conditions, the gas exchange process requires extra work to draw in air into the cylinder due to a lower amount of pressure in the intake manifold caused by the restriction of the throttle plate. The Miller cycle is regarded as a potential strategy of knock control for downsized gasoline engines. Extensive works have sought to examine the performance improvement via the Miller cycle, yet only limited research has been conducted on the manner in which it can influence knock suppression. The focus of this thesis is to investigate early and late intake valve closing timings in terms of how they affect the compression process, the ability to suppress engine knock and meet the power output required at high loads for spark-ignited gasoline engines. Apart from that, this research also demonstrates the Miller cycle potential by utilising fully variable valve timing in controlling the load at the part load condition without using a throttle. The early intake valve closing with different valve lifts was tested in order to investigate the impact during the gas exchange process, particularly the pumping losses and the potential to improve fuel economy. This study includes both experimental and simulation studies. A Lotus single-cylinder research engine referred to as SCORE was mainly used for the experimental component of the study. The simulation work was conducted using a one-dimensional spark ignition engine model built in the Ricardo WAVE software for naturally-aspirated and downsized engines. The engine model values are validated against the experimental values from the Lotus SCORE and Lotus SABRE engines. The combustion model with a reduced kinetics mechanism was validated using a Rover K-series engine. A broad matrix of the engine operations has been investigated combining a variety of engine speeds and engine loads. The Miller cycle effects on knock suppression in a downsized engine environment have been investigated in three parts, namely the Miller cycle at different speed-load, knock suppression with extreme Miller cycle, and knock analysis with combustion kinetics. Through the works, the Miller cycle has demonstrated its capability to suppress engine knocking in a more efficient manner as opposed to the standard engine operation. This is contributed by the fact that early and late intake valve closings could affect the end gas condition at the end of the compression stroke, thus making it possible to suppress the engine knocking. The experimental study for controlling load without using throttle under the naturally-aspirated condition found that the Miller cycle with an early intake calve closing strategy able to improve fuel consumption by reducing pumping losses. The downsized engine condition, which has been evaluated via modelling work, also showed an improved performance trend using the unthrottled Miller cycle strategy. The open cycle and close cycle efficiencies have improved through the Miller cycle implementation. The contribution of this work is made in order to establish the comparison of the Miller cycle strategy in suppressing knocking between the early intake valve closing and late intake valve closing under a boosted environment. For the part load condition of the downsized engine, the research contributes to the existing body of knowledge by comparing the throttle-less Miller cycle and the standard throttled operation as a load control strategy.

>Magister Scientiae - MSc / This thesis focuses on the electroanalysis of some dienes (2-methyl-1.3-butadiene (MBD), tran-1.3-pentadiene (PD), 1.3-cyclohexadiene (CHD) and 3-cyclooctadiene (COD)) found in gasoline and the development of simple electrochemical diene sensors. The detection of dienes in fuels is important as they readily polymerise and form gum in fuel tanks. The electroctivity of the dienes was studied with glassy carbon electrode (GCE) and Pt electrode in tetrabutylammonium perchlorate (TBAP)/acetonitrile solution. Polyaniline-polystyrene sulfonic acid (PANi-PSSA) composite films were electro-deposited or drop-coated on GCE, with and without gold nanoparticles (AuNPs) and characterized by cyclic voltammetry (CV), high resolution transmission electron microscopy (HRTEM) and ultraviolet-visible (UV-vis) spectroscopy. Both composite polymers were found to be of nanofibral structure, and the spherical gold nanoparticles were dispersed uniformly within the polymer. The dienes exhibited no redox peaks on GCE/PANi-PSSA and GCE/PANi-PSSA/AuNPs electrode systems from -1.0 V to +1.5 V, beyond which PANi would overoxidize and lose its electroactivity. Therefore, cyclic voltammetry and steady state amperometry of the four dienes (MBD, PD, CHD and COD) were studied with unmodified Pt and GCE electrodes. Subtractively normalised interfacial-fourier transform infra-red (SNIFTIR) spectroscopic studies of the dienes were performed with Pt electrode. SNIFTIR data showed that there was a definite electro-oxidation of 1.3-cyclohexadiene as electrode potential was changed from E = 770 mV to E = 1638 mV. Severe electrode fouling was observed when steady state amperometric detection of CHD, as a representative diene, was performed on Pt electrode. Randel-Sevčik analysis of the CVs of the dienes on Pt electrode gave diffusion coefficient (Dox) values of 10.65 cm²/s, 9.55 cm²/s, 3.20 cm²/s and 3.96 cm²/s for CHD, COD, PD, and MBD, respectively. The corresponding detection limits (3σn-1) were 0.0106 M, 0.0111 M, 0.0109 M, and 0.0107 M.

The GDI engine has a number of practical advantages over the more traditional port-fuel injection strategy, however a number of challenges remain the subject of continued research in an attempt to fully exploit the advantages of the GDI engine. These include complex in-cylinder flow fields and fuel-air mixing strategies, and significant temporal variation, both through an engine cycle and on a cycle-by-cycle basis. Despite advances in experimental techniques, the relative difficulty and cost of taking detailed measurements remains high, thus computational techniques are an integral part of research activities. The research work presented in this thesis has focused on the use of detailed 3D-CFD techniques for investigating physical phenomena of the in-cylinder flow field and fuel injection process in a single cylinder GDI engine with early injection event. A detailed validation of the numerical predictions of the in-cylinder flow field using both the RANS RNG k-ε turbulence model and the Smagorinsky LES SGS turbulence model was completed with both models showing good agreement against available experimental results. A detailed validation of the numerical predictions of the fuel injection process using a Lagrangian DDM and both RANS RNG k-ε turbulence model and Smagorinsky LES SGS turbulence model was completed with both models showing excellent agreement against experimental data. The model was then used to investigate the in-cylinder flow field and fuel injection process including research into: the three dimensional nature of the flow field; intake valve jet flapping, characterisation, causality and CCV, and whether it could account for CCV of the mixture field at spark timing; the anisotropic characteristics of the flow field using both the fluctuating velocity and turbulence intensity, including the increase in anisotropy due to the fuel injection event; the use of POD for quantitatively analysing the in-cylinder flow field; investigations into the intake valve, cylinder liner and piston crown spray plume impingement processes, including the use of a multi-component fuel surrogate and CCV of the formed liquid film; characterisation and CCV of the mixture field though the intake and compression strokes up to spark timing. Finally, the predicted turbulence characteristics were used to evaluate the resultant premixed turbulent combustion event using combustion regime diagrams.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O tÃxon genÃrico Burkholderia apresenta grande diversidade metabÃlica, possibilitando que estas proteobactÃrias vivam numa variedade de habitats, dentre os quais destacamos o solo, Ãgua (incluindo Ãgua do mar), plantas, fungos, animais e atà mesmo seres humanos. Uma das aplicaÃÃes biotecnolÃgicas mais marcantes à a capacidade de promover a biodegradaÃÃo de poluentes. Assim, este estudo visou a identificaÃÃo do isolado de Burkholderia SMF 090, bem como a avaliaÃÃo do potencial na utilizaÃÃo da gasolina como fonte de carbono e a identificaÃÃo de vias metabÃlicas possivelmente envolvidas na degradaÃÃo dos componentes da gasolina atravÃs da realizaÃÃo de anÃlises proteÃmicas. A identificaÃÃo do isolado SMF 090 e anÃlise da filogenia molecular foi realizada pelo sequenciamento do gene 16S rRNA. Posteriormente, foram realizadas anÃlises de filogenia molecular e reconstruÃÃo de Ãrvores filogenÃticas com outras bactÃrias do gÃnero. Para a caracterizaÃÃo do perfil de crescimento do isolado SMF 090 foram realizadas curvas de crescimento em meio nutritivo (TY), meio sem fonte de carbono (BH), BH suplementado com gasolina comercial e BH suplementado com D-glicose. O estudo das proteÃnas diferencialmente expressas ocorreu atravÃs de eletroforese bidimensional, de espectrometria de massa e anÃlises de bioinfomÃtica. AtravÃs da anÃlise do 16S rDNA, sugeriu-se que SMF 090 està relacionada à Burkholderia sabiae Br3407 e ambos descendem de um ancestral comum recente. A bactÃria estudada foi capaz de crescer em meio mineral contendo gasolina como Ãnica fonte de carbono. Foi possÃvel observar proteÃnas diferencialmente expressas entre os grupos testados, as quais podem estar associadas ao metabolismo de degradaÃÃo de hidrocarbonetos. As anÃlises dos gÃis de 2DE e os dados de espectrometria de massas permitiram a identificaÃÃo de vÃrias proteÃnas das vias de catabolismo dos hidrocarbonetos aromÃticos monocÃclios e policÃclicos. Portanto, o estudo apresentou informaÃÃes relevantes sobre o metabolismo de Burkholdeiras como potenciais biodegradadoras de gasolina. / The generic taxon Burkholderia presents a high metabolic diversity that allows these protobacteria live in a wide range of habitats, among these are the soil, water (including sea water), plants, fungi, animals and even humans. A remarkable biotechnological application is the capacity to promote the pollutants biodegradation. Thus, this study aimed the identification of Burkhoderia SMF 090 isolate, as well the evaluation of its potential on the utilization of gasoline as a carbon source and the identification of metabolic pathways possibly involved in the degradation of gasoline on its components through realization of proteomic analysis. The identification of the SMF 090 isolate and the analysis of molecular phylogeny were carried out by 16S rRNA gene sequencing. In addition, the molecular phylogeny was analyzed and phylogenetic trees were reconstructed using other bacteria from the same genus. In order to characterize the growth pattern of SMF 090, bacterial growth curves were assessed using the media TY (a nutritive media), BH (a medium without carbon), BH plus commercial gasoline and BH plus D-glucose. The study of differentially expressed proteins was performed using bidimensional electrophoresis, mass spectrometry and bioinformatics analysis. After the 16S rRNA analysis was suggested that SMF 090 is related to Burkholderia sabiae Br3407 and both descended from a recent common ancestral. The strain grown in mineral media containing gasoline as the unique carbon source. Differentially expressed proteins were observed between the tested groups and these proteins may be associated to the metabolic degradation of hydrocarbons. The analysis of data provided by 2DE electrophoresis and mass spectrometry allowed the identification of various proteins related to the monocyclic and polycyclic aromatic hydrocarbons catabolism pathway. Therefore, this study showed relevant results about the growth of Burkholderia as a potential gasoline biodegradant.

Dados da CETESB revelam que a comercialização de derivados do petróleo na Cidade de São Paulo, em especial a gasolina, tem gerado um número significativo de casos de vazamento de combustíveis, causados pela falta de manutenção de equipamentos, deterioração de tanques e tubulações, e falhas operacionais decorrentes do despreparo dos profissionais que atuam nesses estabelecimentos. A área urbana da Cidade de São Paulo está, em grande parte, edificada sobre os depósitos sedimentares de idade cenozóica da Bacia de São Paulo, onde a Formação Resende apresenta distribuição generalizada e compreende mais de 80% do preenchimento sedimentar. Argilominerais esmectíticos predominam na fração fina dos sedimentos da Formação Resende e a possível interação deles com hidrocarbonetos foi o objeto de investigação dessa dissertação. Nesse sentido, o presente trabalho teve por objetivo o estudo laboratorial da interação, por meio de sorção e desorção, de hidrocarbonetos encontrados comumente, como gasolina comercial, benzeno, tolueno e xilenos, com argilominerais esmectíticos da Formação Resende, no contexto da zona vadosa, na Bacia de São Paulo. Para tanto, três amostras argilosas da Formação Resende foram coletadas na zona leste da Cidade de São Paulo, tendo sido efetuada sua caracterização granulométrica, mineralógica (via DRX) e química (análise de CNH). Em testes de inchamento com gasolina e orgânicos puros, nenhuma das amostras apresentou absorção dos compostos. Os testes de adsorção e desorção procuraram caracterizar a interação dos hidrocarbonetos com a rocha total, fração silte e fração argila dos sedimentos, variandose o tempo de exposição (30 minutos a 32 dias) das amostras aos contaminantes. Os resultados obtidos permitiram reconhecer que a adsorção é o mecanismo de sorbância predominante. A variação das concentrações ao longo do tempo evidenciou que a interação amostra/contaminante é dinâmica ao longo do tempo de contato, havendo momentos distintos de sorbância, com variação significativa e bem representada dos teores adsorvidos, e que essas fases ocorrem independentemente da granulometria ou mineralogia das amostras, sendo: os sedimentos argilosos adsorvem, na média, as mesmas ordens de grandeza de cada contaminante, o que é devido a sua homogeneidade granulométrica e mineralógica em pequena escala; dentro da ordem de grandeza de adsorção de cada contaminante, as diferenças composicionais (granulométricas e mineralógicas) entre as amostras de sedimentos argilosos alteram os teores dos compostos em função da proporção de argila na rocha total, de forma que quanto mais contaminante será adsorvido, e do tipo de argilomineral predominante na fração argila, sendo a maior proporção de esmectita um fator favorável. / Data from the Environmental Agency of São Paulo State (Company of Environmental Sanitation Technology CETESB) reveal that the commercialization of petroleum products in the city, especially gasoline, has generated a high number of fuel leakages and contaminated areas. The urban area of São Paulo city is underlain by the Cenozoic sedimentary deposits of the São Paulo Basin. In this basin, smectiterich mudstone of the Resende Formation is widely distributed and comprises over 80% of the sedimentary filling. The aim of this study was to investigate the interaction of smectiterich mudstone of the Resende Formation with hydrocarbons in the São Paulo Basin. The sorption and desorption of common hydrocarbons, such as gasoline, benzene, toluene and xylene, by the smectitic clay minerals, in the context of vadose zone, were investigated in laboratory. Three representative subsurface samples of mudstone were collected in the east part of São Paulo city and characterized by granulometry, Xray analysis and CHN determination. Swelling test with gasoline and pure organic compounds does not promote absorption in the three studied samples. Adsorption and desorption tests were employed to characterize the interaction between the hydrocarbons and the wholerock, silt and clayfractions of the mudstone in different time intervals of contact (30 minutes to 32 days). The results revealed the adsorption as the main interaction mechanism. Variations in concentration of contaminants in different time intervals of contact indicated a dynamic interaction between sample and hydrocarbons, existing phases with distinct amounts of organics adsorbed (or retained after desorption). Theses phases are controlled by the time of contact and are independent of samples granulometry and mineralogy, and contaminant type. The three mudstone samples adsorb about the same amount of each contaminant, which is due to their overall granulometric and mineralogic homogeneity. Nevertheless, minor and local changes in sample composition (granulometry and mineralogy) cause a small scale variation in the amounts of each contaminant adsorbed as a result either of clay proportion in the whole-rock and of the predominant clay mineral in the clay fraction.