This thesis presents the research on direct-fuel-injection (DFI) performance analyses of the two-stroke engine using computational fluid dynamics (CFD). The aims of this research are: (1) to generate a finite volume mesh that can be used to simulate the moving of the piston and opening and closing the ports of the cylinder, (2) to achieve an numerical flow pattern of the scavenging process and (3) to study the DFI process using the mesh and the flow pattern obtained from the first two parts. The three parts in the analyses, therefore, are the engine geometry modelling, scavenging process modelling and DFI modelling. CFD software STAR-CD was used to write the programme and perform the analysis. The geometry model used a moving mesh mechanism with variable openings to simulate the piston motion and port area changes. The scavenging model was constructed to calculate 3D, compressible, turbulent, transient flow with heat transfer and changing volume. Results of the calculation provided a large number of data, including flow patterns, pressure and temperature distributions and fresh-charge concentrations. The DFI process was simulated as a gasliquid two-phase flow. Fuel droplets dispersed in the continuous gas phase were calculated using the Lagrangian model. Four DFI cases that differ in position and number of injectors were simulated. Fuel droplet distribution, including droplet size, velocity, temperature and position, and fuel-vapour concentration were obtained. The result of the geometry modelling shows that the finite volume programme performed well for this particular task. Because of the limitation of the computer hardware used, this programme was restricted to be used for the simulation of the engine process before the ignition, i. e., cold running condition, therefore, combustion process was not included. The findings from the analyses, with very limited resources, would help improve the engine design. The results of all four cases indicate that, even only for the period of engine process before the ignition, the DFI two-stroke engine can significantly reduce hydrocarbon emissions compared with the conventional carburettor engine.

No description available.

Key petrophysical properties of reservoir sequences are determined by their individual mineral compositions, and are routinely evaluated through the analysis of cores and geophysical well logs. However, mineralogical studies are seldom incorporated in reservoir assessment. The objectives of the study were to investigate the influence of mineralogy on petrophysical properties of petroleum reservoir beds and the application of mineralogical studies in reservoir evaluation. Mineralogical analyses were performed on core samples from the Plover Formation, the principal reservoir sequence in the Northwest Shelf area of Australia, intersected in two separate wells in the Laminaria petroleum field. The techniques used included X-ray powder and oriented-aggregate analysis, optical microscopy and whole rock geochemistry. Quantification of each mineral phase based on whole-rock powder data was performed using the Rietveld-based Siroquant technique. Results from the Siroquant assay were used as an indicator of mineralogy for the individual samples and were compared with core plug and geophysical log data. X-ray micro-tomography analysis of selected samples was also performed. The reservoir sequences in both wells were sand-dominated, consisted mostly of quartz, clay mineral matrix and cement of silica, pyrite or calcite. The abundance of clay minerals increased in the shale and shaly sandstone intervals. Comparison of mineralogical and core plug analyses of samples from the same depths showed that the down-hole variations in porosity, permeability, grain density and radioactivity were accompanied by changes in mineralogy. Higher proportion of clay minerals in shales was indicated by higher gamma log signals. The gamma log may be taken as an indicator of shaliness only in intervals where kaolinite is proportional to the quantity of illitic clays. Sonic log and neutron log porosity values are comparable with core plug porosity data in sandstone intervals. However, clay minerals increase the sonic log response, thereby increasing porosity in shaly intervals. Clay minerals tend to decrease the neutron log response causing higher porosity indication in shales, similar to that expected in sandstones. Routine density log analysis underestimated porosity values because of the contribution of dense minerals to the bulk density of the formation. Use of laboratory determined grain and fluid densities resulted in improved density log porosity compared to core porosity. X-ray tomography analysis revealed an overall positive correlation between mineralogy and porosity data. Routine geophysical log evaluation revealed inconsistent results when compared to core analysis data because of the influence of minerals on various logs. It is essential that mineralogical studies be included in reservoir assessment. X-ray tomography may provide an alternative approach in evaluating porosity and mineralogy.

Thesis (Ph. D.)--University of Missouri--Columbia, 2000. / "August 2000." Typescript. Vita. Includes bibliographical references (leaves 113-122). Also available on the Internet.

Surface mining in the Athabasca oil sands region of Northern Alberta, Canada, results in the disturbance of significant areas of boreal forest landscape. The Aurora Soil Capping Study is a reclamation research project that aims to find the optimal soil capping (cover) material and thickness to re-establish a boreal forest ecosystem above a lean oil sands (LOS) disposal area at Syncrude's Aurora North mine. The objectives of this laboratory and field-based study are to (1) characterize the in-situ hydrocarbon composition of the LOS material, (2) determine the effect of temperature on rates of gas flux and the biodegradation potential of petroleum hydrocarbons (PHC) as a result of microbial activity and (3) determine the potential for PHC to leach into the groundwater system. The results of the laboratory-study show that temperature has a significant effect on the rate of PHC degradation as indicated by the linear relationship observed between temperature and CO2 gas flux rates. The respiratory results from the laboratory-based study were consistent and relatively comparable with data from the field study, which indicates that the column study could be useful in estimating in situ PHC degradation.

Rate measurements for the reactions of a series of polyfluoro - and polychloro - pyridines with aniline and ammonia in 60/40 dioxan/water at 25ºC has shown that chlorine, when ortho and para to the position of attack, is activating with respect to fluorine, but at the position meta to the point of attack, chlorine and fluorine are virtually equivalent in their effect on reaction rate. The trifluoromethyl and nitrile groups were found to be activating relative to fluorine when ortho and para to the position of substitution and the nitrile group was thus found to be ortho/para directing. The ortho/para orienting effect of ring nitrogen was shown to be dominant in heterocyclic systems. It has been demonstrated for several different nucleophiles that nucleophilic attack in polyfluorinated heterocycles occurs so as to maximise the number of ortho and meta fluorines with fluorine being of little significance. Of the nucleophiles examined aniline and ammonia were found to be similar in their behaviour. Benzylamine however showed some propensity for substitution at positions ortho to ring nitrogen whilst N-methylaniline showed strong steric effects due to the N-methyl group, most notably when the heterocylic ring substituents were chlorine, trifluoromethyl and nitrile. Sodium was shown to have a 'salt effect' in the reactions of methoxide and phenoxide, and, a catalytic effect on the reactions of aniline affecting both the rate and position of substitution. The use of transition state, and molecular orbitals to explain the patterns of substitution is discussed. The trifluoromethylsilyl group was found to undergo nucleophilic attack at silicon and the series of mono, di and tri-fluoromethyl-pentafluorobenzenes were used to examine the concept of negative ion hyperconjugation.

No description available.

Chapter 1 is a general and historical introduction to the field of atomic nitrogen research. Specific mention is made of the methods by which atomic nitrogen has been generated and detected, and examples of its reactions with (predominantly organic) substrates are included. The overall aim of the thesis, the generation of atomic nitrogen in solution by mild thermolysis or photolysis, is stated. This concerns bond breaking, mainly in nitrogen heterocycles. In Chapter 2, 1,2,4-dioxazolidines are investigated and discussed according to the overall aim. Competing 0-0 and N-X (X = nitrogen substituent) scissions are compared by selective derivatisation. The thermal and photochemical fragmentation of these dioxazolidines is described, and evidence for atomic nitrogen and nitrene formation is adduced. Chapter 3 considers the use of heteroaromatic <i>N</i>-imines as a means to the proposed goal. Attention is centred on benzo[c]cinnoline <i>N</i>-imine, and its selective derivatisation. Radicals produced during photochemical decomposition of benzo[c]cinnoline <i>N</i>-imine derivatives are detected both directly and indirectly by e.s.r. spectroscopy, and evidence for the spin-trapping of atomic nitrogen is presented. In Chapter 4, the <i>in situ</i> oxidation of urazoles is investigated by e.s.r. spectroscopy, and <i>in situ</i> cycloadditions of these oxidised species are performed. 7-Azabenzonorbornadienes and 7-azanorbornadienes are applied as potential sources of atomic nitrogen in Chapter 5. The generation of the corresponding radicals is investigated by e.s.r. spectroscopy.

No description available.

Nearly thirty C20, C25, and C30 highly branched isoprenoid (HBI) hydrocarbons have been detected, sometimes in high concentrations, in recent freshwater, estuarine, coastal and hypersaline sediments, and water column particulate matter from numerous locations worldwide. The parent structures have been proved but only a few of the double bond positions have been established. The assignment of C21, C22 and C26 homologues and other C20 and C25 isomers, remains tentative. A wide body of evidence suggests that the compounds are biogenic in origin, with algae and possibly bacteria the most likely source organisms. A few of the compounds have been identified in field samples of algae but none have been reported in laboratory cultured biota. The alkenes with more than two double bonds appear to be rapidly removed from the hydrocarbon fraction in most sediments, whereas the alkanes and monoenes seem to be more resistant to biodegradation and hence occur in some more ancient sediments and oils. There is evidence that some of the alkenes react rapidly with sulphur to form either S-containing HBI heterocycles or become bound within macromolecular aggregates both found in sediments and some oils. The compounds, both as hydrocarbons and S-containing analogues, may prove useful environmental indicators once the sources and exact structures of more of them have been established. In the literature the structural elucidation of C25 and C30 alkenes has been based mainly on the analysis of their hydrogenation products. However, some authors concluded that the alkenes are cyclic since some could not be fully hydrogenated. The structure of a C25 HBI diene was proven to be a cyclic by hydrogenation studies and GC and GCMS analyses which showed the HBI compound to be fully saturated. The isolation and characterisation of synthetic alkenes resulted in the assignment, or partial assignment, of structures to four C20, six C25 and four C30 monoenes. The formation of novel monoenes via isomerisation reactions has also been achieved. The compounds form a valuable database of chromatographic and spectroscopic information for the assignment of sedimentary alkenes but the importance of isolation and micro-ozonolysis has been emphasised. Synthetic HBI alkenes were used to assign structures and partial structures to naturally occurring HBI hydrocarbons in three sediments. Other monoenes (both with methylene double bonds) were isolated from the sediments and characterised using spectroscopic and micro-ozonolysis data. The widespread occurrence of C20 and C23 HBI hydrocarbons in Tamar sediments and associated algae (macrophytes and diatoms), the large variation in isotopic composition evident for the C20 monoene, and the seasonal sedimentary distribution all suggest two possible sources for the HBI hydrocarbons; microalgae and/or heterotrophic bacteria. Investigation of the distribution of hydrocarbons from the Peru upwelling area confirmed the rapid decrease in concentration of C25 HBI alkenes with depth. A mixture of HBI monoenes was successfully incorporated into melanoidins but not detected in the humic acid pyrolysate which implied that incorporation of HBI alkenes into accreting humic substances was not a major mechanism of diagenesis of HBI alkenes. This study has extended present knowledge of the structures of HBI monoenes and has suggested two possible biological sources. There is still much to be learned about HBI polyenes and the subject is proving to be a fruitful area for further research into biomarker potential. Some possible future approaches are suggested.