DSpace Community:http://hdl.handle.net/2440/147592014-09-28T21:36:21Z2014-09-28T21:36:21ZExact solution for non-self-similar wave-interaction problem during two-phase four-component flow in porous mediaBorazjani, S.Bedrikovetski, P.Farajzadeh, R.http://hdl.handle.net/2440/855312014-09-26T00:03:33Z2013-12-31T13:30:00ZTitle: Exact solution for non-self-similar wave-interaction problem during two-phase four-component flow in porous media
Author: Borazjani, S.; Bedrikovetski, P.; Farajzadeh, R.
Abstract: Analytical solutions for one-dimensional two-phase multicomponent flows in porous media describe processes of enhanced oil recovery, environmental flows of waste disposal, and contaminant propagation in subterranean reservoirs and water management in aquifers. We derive the exact solution for 3 x 3 hyperbolic system of conservation laws that corresponds to two-phase four-component flow in porous media where sorption of the third component depends on its own concentration in water and also on the fourth component concentration. Using the potential function as an independent variable instead of time allows splitting the initial system to 2 x 2 system for concentrations and one scalar hyperbolic equation for phase saturation, which allows for full integration of non-self-similar problem with wave interactions.2013-12-31T13:30:00ZHydrothermal studies on mineral replacement reactions in the gold-silver-tellurium and copper-iron-sulfur systems.Zhao, Jinghttp://hdl.handle.net/2440/855102014-09-25T23:53:39Z2013-12-31T13:30:00ZTitle: Hydrothermal studies on mineral replacement reactions in the gold-silver-tellurium and copper-iron-sulfur systems.
Author: Zhao, Jing
Abstract: Over the past decades, a number of hydrothermal studies were undertaken on the mineral replacement reactions using hydrothermal method, which mostly proceeded via a coupled dissolution-reprecipitation (CDR) mechanism. However, most of experimental studies have been focused on mineral replacement reactions at relative low pressures and at low to medium temperatures. For hydrothermal mineral deposits set at higher temperature, such as porphyry copper systems or intrusion-related gold deposits, solid-state diffusion may be significant due to the high mobility of the metal ions, and solid-state reactions may compete kinetically with the CDR mechanism. Thus, to investigate the possible interaction between CDR reactions and solid state reactions, we designed a set of hydrothermal studies into the mineral replacement reactions in both Au-Ag-Te and Cu-Fe-S systems. The mineral replacement of sylvanite was studied under hydrothermal conditions, exploring the effects of temperature (160-220 °C), pH (2-10), and redox conditions on the sample textures and reaction kinetics. Sylvanite transformed to Au-Ag alloy and a range of other gold-(silver)-telluride phases as intermediate products, including petzite (Ag₃AuTe₂), hessite (Ag₂Te), an Ag-rich-Te-depleted calaverite-I (Au₀.₇₈Ag₀.₂₂Te₁.₇₄) and a normal calaverite-II (Au₀.₉₃Ag₀.₀₇)Te₂. The textures of products are very complex due to the interplay between solution-driven interfaces coupled dissolution-reprecipitation (ICDR) reactions and solid-state diffusion driven processes. The complex interaction among solid-state diffusion and ICDR reactions under hydrothermal conditions is due to the high solid-state mobility of Ag ion in the Au-Ag-Te system. The hydrothermal synthesis of chalcopyrite was performed via the sulfidation of hematite in solutions containing Cu(I) (as a chloride complex) and hydrosulfide, at pH near the pKa of H2S(aq) under hydrothermal conditions. Due to the large positive volume increase, the sulfidation of hematite by chalcopyrite follows a dissolution reprecipitation mechanism progressing via both direct replacement and also overgrowth. Distinct from other solution mediated ICDR reactions (e.g. the transformation from pentlandite to violarite) (Xia et al. 2009), no distinct porosity structures were observed in the quenched product grains. This is probably due, at least in part to the large volume increase during the reactions. This work investigated the nature of CDR reaction with large volume increase at relative high temperatures and high pressures, and improved our understanding of the physical chemistry of chalcopyrite formation in nature. To explain the transformation mechanism of chalcopyrite and bornite intergrowths, we reported the replacement of chalcopyrite by bornite in solutions containing Cu(I) (as a chloride complex) and hydrosulfide over the temperature range 200-300 °C. Results show that chalcopyrite was replaced by bornite under all studied conditions. The reaction proceeds via a CDR reaction mechanism and with some additional overgrowth of bornite. The bornite product formed at 300 °C for 24 hrs is Cu-rich corresponding to compositions in the bornite-digenite solid solution (bdss) Bn₉₀Dg₁₀, which can exsolve into digenite lamella in a bornite host during the further annealing in the original solution at 150 ˚C and 200 ˚C for 24 to 120 hrs. The exsolution of bdss is another example of solid-state diffusion under hydrothermal conditions.2013-12-31T13:30:00ZClinical analysis of liver function: development of a novel method for the detection of portosystemic shunts.Matthews, Todd Jameshttp://hdl.handle.net/2440/855092014-09-25T23:50:20Z2013-12-31T13:30:00ZTitle: Clinical analysis of liver function: development of a novel method for the detection of portosystemic shunts.
Author: Matthews, Todd James
Abstract: A portosystemic shunt (PSS) is defined as a congenital or acquired abnormal blood vessel that redirects blood around the liver without being filtered through hepatic parenchyma. PSS are thought to contribute to the distribution of isolated secondary metastases beyond the liver in 1.7 - 7.2% of all colorectal cancer patients without cirrhosis of the liver. No standardised clinical test for PSS yet exists and subsequently, the majority of PSS cases are detected incidentally through radiological means. To better identify PSS, a simple standardised clinical test for its detection is needed. The aim of this thesis was to develop a cost effective, non-invasive technique that can detect and measure PSS in a healthy liver model. Methods An artificial 8mm diameter PSS was created between the portal vein and the inferior vena in a pig model with a catheter inserted in the confluence of the hepatic veins for sample collection. A spectrum of compounds including indocyanine green (ICG), ¹³C-methacetin, sorbitol and lignocaine, were injected into the portal system. To analyse the pharmacokinetic nature of the shunt and liver, Evans blue dye and ¹⁴C-sucrose were also administered. ICG was measured via a LiMON® spectrometer attached to the pig’s snout, while levels of the other indicators were measured by serial blood and breath sample collection over a 40 minute period. The process was repeated with the PSS clamped as the control. Results Of the administered compounds, only ICG had the potential to clearly identify and quantify the shunt due to the rapid serial sampling via the LiMON®. Further simulations using ICG demonstrated that the shunted fraction can be calculated using the transit times, including mean residence time, lag time and pharmacokinetic modelling. Conclusion Although this study has not yet provided a concise method for PSS detection available for immediate clinical use, it does provide a large foundation for further exploration into a quantitative technique. A future PSS test would allow an added risk assessment for secondary cancer, and consequently individual cancer therapy may be better targeted for individual patient care.2013-12-31T13:30:00ZThe wave function of the nucleon and its excited states.Roberts, Dale Stevenhttp://hdl.handle.net/2440/855082014-09-25T23:43:28Z2013-12-31T13:30:00ZTitle: The wave function of the nucleon and its excited states.
Author: Roberts, Dale Steven
Abstract: In this thesis, we detail the techniques required to perform general lattice QCD calculations. Specifically, we introduce the method by which the continuum theory of quarks and gluons, Quantum Chromo-dynamics is discretised in order to be solved numerically. We describe the distinct methods by which the discrete actions for the gauge and fermion fields given by naively applying a finite-difference approximation to the continuum theory can be improved, going some way to remove the systematic errors of discretisation. The background field method for placing electromagnetic fields onto a discrete lattice is also introduced. Techniques required for the calculation of wave functions are then introduced, beginning with the two-point function, which is fundamental in extracting properties of hadrons from the lattice. The variational method, which allows access to the excited states of particles is then introduced. The wave function is then constructed from the two-point function, which forms the basis of the most significant results of this thesis. We also introduce gauge fixing, made necessary by the gauge dependent nature of wave function operators. The smeared operators used in the construction of these two-point functions are evaluated, by way of two measures designed to measure the coupling strength of these operators to states with a variety of momenta. Of particular interest is the extent to which strong overlap can be obtained with individual high-momentum states. This is vital to exploring hadronic structure at high momentum transfers on the lattice and addressing interesting phenomena observed experimentally. We consider a novel idea of altering the shape of the smeared operator to match the Lorentz contraction of the probability distribution of the high-momentum state, and show a reduction in the relative error of the two-point function by employing this technique. Our most important finding is that the overlap of the states becomes very sharp in the smearing parameters at high momenta and fine tuning is required to ensure strong overlap with these states. Making use of the background field methods and the wave functions constructed from the two-point functions, we calculate the probability distributions of quarks in the ground state of the proton, and how they are affected in the presence of a constant background magnetic field. We focus on wave functions in the Landau and Coulomb gauges using the quenched approximation of QCD. We observe the formation of a scalar u - d diquark clustering. The overall distortion of the quark probability distribution under a very large magnetic field, as demanded by the quantisation conditions on the field, is quite small. The effect is to elongate the distributions along the external field axis while localizing the remainder of the distribution. Using optimised smearing parameters calculated from the methods detailed in this thesis, we construct wave functions of high-momentum states, and are able to qualitatively observe high momentum states. We find that, at very high momenta, artefacts are present caused by the poor overlap of these states to the interpolating operators. Careful tuning of the smearing parameters is shown to reduce these artefacts, reinforcing results presented earlier in the thesis. The culmination of the techniques introduced and the results obtained in this thesis is the application of the eigenvectors from a variational analysis to successfully extract the wave functions of even-parity excited states of the nucleon, including the Roper, in full QCD. We explore the first four states in the spectrum excited by the standard nucleon interpolating field. We find that the states exhibit a structure qualitatively consistent with a constituent quark model, where the ground, first-, second- and third-excited states have 0, 1, 2, and 3 nodes in the radial wave function of the d-quark about two u quarks at the origin. Moreover the radial amplitude of the probability distribution is similar to that predicted by constituent quark models. We present a detailed examination of the quark-mass dependence of the probability distributions for these states, searching for a nontrivial role for the multi-particle components mixed in the finite-volume QCD eigenstates. Finally we examine the dependence of the d-quark probability distribution on the positions of the two u quarks. The results are fascinating, with the underlying S-wave orbitals governing the distributions even at rather large u-quark separations.2013-12-31T13:30:00Z