Search

Owing to the inescapability of using foams in industry, technology, and engineering, researches that delve into their rheological behaviour are utterly significant, and the fact that foams share many rheological properties with granular materials, colloidal systems, and emulsions; has further enhanced this significance. Hence exploring the rheology of foams would cast light on a range of problems related to the rheology of the systems mentioned above. In this study, computer simulations are conducted to predict the behaviour of foams that flow in vessels of various geometries utilizing a modified version of the "Bubble model" on wet liquid foams, taking into consideration the inertial effects, the attractive interactions between bubbles and the shear in the thin intervening fluid layer between bubbles that are a small distance apart, in contrast to other previous similar studies. Notwithstanding disparities, the application of periodic boundary conditions instead of non-periodic boundary conditions has been gaining traction amongst the computational rheology community, due to less computational efforts and complexity that employing the former conditions requires. Perceiving the need to rectify this implementation of periodic boundary conditions on an ad hoc basis, a non-periodic boundary conditions ab initio imposition, a technique hitherto computational rheology studies have been void of its utilization; at the entrance and the exit of rectangular vessels is contrived to be introduced. Since one of the advantages of adopting this model is its flexibility in dealing with any shapes, it is adopted to simulate foam flow around square objects, without resorting to rounding their sharp corners, as it has been noted in all numerical experiments that address foams flow around obstacles with angular shapes; thus further perspectives on the behaviour of liquid foams flowing around other angular shapes would be highlighted. Moreover, noting the lack of numerical studies that investigate the interplay between a liquid and foam bubbles, a subject of significance in computer graphics, the flow of bidimensional foams partially filling a vertically positioned rotary drum, the lower half of which is filled with a liquid; is presented. Simulations of the foam flow around circular and square objects in rectangular channel and rotary drums, through two-sided rectangular and semicircular constrictions, in half-filled rotary drums are explored by virtue of velocity profiles, velocity field, topological rearrangements, interface deformation analysis, bubbles trajectories, texture tensor, drag force exerted by the flowing foam on the obstacles, and varying the strength of the attractive forces relative to the repulsive forces between bubbles. In this work, the parameters have been selected such that results from more detailed foam flow models are well reproduced. Accordingly, it is expected that, compared with previous similar works, investigating the influence of the chosen set of parameters on the resulting simulations would show that the present simulations are better. The author realizes that the parameter values used in computations conducted in this work are often different than those adopted in the studies that are referred to in this thesis that make it difficult to formulate direct conclusions. However, similar effect/s that can be observed in the aforesaid studies, even though the values of the parameters utilized are dissimilar to those used in these studies; are discussed and compared to the results acquired in this work. It is clear that more analysis should be done in the future to justify/verify this first glance impression.

The signalling arising from tissue factor (TF) has been associated with cellular homeostasis as well as haemostasis and, is particularly pertinent in carcinogenesis and cancer progression. The formation of the TF-FVIIa complex is known to activate protease activated receptor 2 (PAR2) and initiates multiple signalling pathways which can determine the fate of the cell. Among these mechanisms PI3K-Akt is known as a major promoter of cell survival and proliferation. The regulation of Akt is mediated by PTEN, a tumour suppressor that negatively regulates the PI3K-Akt pathway resulting in the loss of downstream proliferative and pro-survival signalling. In this study, seven tumour cell lines from different tissues were activated with PAR 2-activating peptide (SLIGKV), or incubated with a range of concentrations of rec-TF (65- 1300 pg/ml). The outcome on the phosphorylation state and the lipid-phosphatase activity of PTEN, and also Akt activity was assessed. Incubation of cells with rec-TF (65 pg/ml) resulted in de-phosphorylation of PTEN in all the cell lines tested which was concurrent with increased PTEN activity and reduced Akt activity. Moreover, activation of PAR2 reduced PTEN phosphorylation and Akt activity in the majority, but not all of the cell lines tested. However, prolonged exposure of cells to rec-TF over 5 days, resulted in decreased PTEN antigen levels together with enhanced Akt activity and increased cell proliferation in the cell lines tested. To explore the mechanism of regulation of PTEN by PAR2, the association of membrane- associated guanylate kinase-with inverted configuration (MAGI)1-3 proteins with PTEN was assessed by the proximity ligation assay (PLA) and co-IP. The interaction of PTEN with all three MAGI proteins was reduced following PAR2 activation and explains the alterations in PTEN activity and stability. The structure of MAGI proteins contains a guanylate kinase-like (GK) domain, two WW domains and six PDZ domains. This structure allows MAGI to restrain proteins at the cell junction, regulating the activity of the proteins and stabilising cell-cell contacts. In the second part of the study, analysis of a motif within the cytoplasmic domain of TF (ENSPL) indicated the possible interaction with MAGI proteins. PLA and co-IP studies showed that TF may be restrained at the tight junctions through interaction with MAGI-1. Interestingly the activation of PAR2 transiently dissociated TF from MAGI-1. By expressing the individual PDZ domains as tagged-hybrid proteins, the first PDZ domain was identified to be capable of binding TF and competing with MAGI-1. The expression of this hybrid protein also resulted in augmented TF activity, similar to that following PAR2 activation. Analysis of the interactions of the N-terminal region of MAGI-1 with or without PDZ1 further confirmed the role of PDZ1 in the constrainment of TF and regulation of its procoagulant activity. In conclusion, this study has demonstrated that PAR2 activation promotes increased PTEN activity in the short term, allowing for the elimination of severely injured cells. However, prolonged exposure TF reduces the cellular PTEN antigen levels allowing aberrant cell survival and proliferation, through increased Akt activity. This study also demonstrated the interaction of TF with the PDZ1 domain of MAGI-1, suggesting a mechanism for restraining cell-surface TF from contact with the surrounding fluid, and may explain the regulation of both coagulation and signalling mechanisms.

Global business trends have led the oil and gas industry to seek better solutions to overcome the emerging challenges and critical issues, such as the need for procurement strategies based on new values and contextual factors including multi cultural complexity. One way to overcome some of these critical issues is perhaps to adopt new innovative approaches to suit different locations, countries or regions while trying to incorporate the differences in business philosophy, culture or values within the oil and gas organisation themselves into these approaches. New innovative approaches to procurement strategies are also required to meet the contextual needs found in different locations and countries around the world. These approaches also need to accommodate specific project needs and different values either in the business philosophy or culture within the oil and gas organization themselves or in the local practices. Oil and gas exploration and production is a highly risky business in a very complicated industry. It links government, owners of the natural resources with operators, investors of private capital, technology and equipment necessary for resource development, in a single industry where the stakes and risks, as well as the possible profit margins, can be very high. The aim of this research study is to improve the understanding of procurement strategies of players and stakeholders (hereafter referred to as "decision makers") in an industry that has gone beyond regions and boundaries. The objectives of the research study included: to explore current procurement practices and trends; to identify the different values adopted by players; and highlight the possible impact of multi cultural complexity on global procurement process and strategies. This research study included an in-depth analysis on these issues using data from literatures and collective responses from the decision makers within the industry. Among the key conclusions and recommendations that can be derived from the research study includes the need to improve the current procurement process in the industry to achieve a more conducive, sustainable and fair working environment between clients and contractors. In the procurement process, decision makers must assess and link their company's type, resources, stakeholders and capabilities before any decision on procurement can be made. Conventional procurement methods, although very much in used by the industry, must be looked upon seriously and studied on its needs and relevance to avoid serious problems or failures in this complicated and complex industry. Finally, a comprehensive procurement strategy guideline on selection processes to be used by decision makers in the industry was developed and produced comprising a set of phases and critical steps that needs to be followed and performed during the selection process. Major issues and associated elements identified in the research study were also incorporated into the guideline on the selection process. This will hopefully assist decision makers to make better analysis and assessment on the appropriate procurement strategy to be adopted in future oil and gas projects throughout the World.

This thesis is concerned primarily with the testing and analysis of design variations of the Lynch motor, which is an axial gap permanent magnet dc machine. These variants include: a standard production motor, a motor with low iron volume, a motor with bigger area of magnets and a motor using powder iron instead of laminations. The powder iron motor was constructed by the author, while all the other motors were provided by the Lynch Motor Company. Tests were conducted to evaluate motor circuit parameters, losses and efficiency using a purpose built test rig which was built in the first stage of the project. Finite element analysis (FEA) was used to determine the levels of the magnetic saturation in the different motors and calculate torque, inductance and EMF. The FEA was also used as bases for comparison with analytical electromagnetic calculations. A dynamic circuit model, whose parametric were derived from FEA and analytical calculations validated by test, was also constructed to study the effect of brush thickness on circulating current and torque production. The results of the work revealed that the larger magnet motor has a high level of saturation resulting in a higher slope of the torque-speed curve. The lower iron volume motor and the powder iron cored motor produced less torque and have less flux density than the standard Lynch motor. The test results proved that the selected powder iron material is usable in the Lynch rotated armature but it still needs improvements to close the performance gap with laminations. The powder iron motor has back emf that is 10% lower than the standard motor, and consequently a lower efficiency. The results show that performance of the Lynch motor can be improved by optimising the size of the saturated parts of the motor, which are the stator discs and the armature teeth. In addition, careful selection of brush number, geometry and type can improve the motor performance. An alternative single gap motor was also studied. The test results show that it has more armature reaction than the dual gap motor and therefore it produced less torque with less efficiency.

Magnetic Resonance Imaging (MRI) is a common medical imaging technique that has been used for measuring the shape of the vocal tract for use in speech research. A significant drawback of using MRI in speech studies is the long scanning time. In this project, a new method was developed for increasing the temporal resolution of MR images needed for dynamic speech studies. This method works by post-processing the collected MR images, with total control of the reconstruction procedure. The subject does not need to be phonetically trained and is not involved in the measurement procedure, which provides a more natural speech environment. By reconstructing the collected images, multi-planar sequential frames are generated that represent the changing shape of the vocal tract during a short utterance. These frames provide much-needed information about the dynamics of articulatory motion and demonstrate the usage of MRI for dynamic speech studies. Qualitative observation of three-dimensional articulatory motion is possible using Virtual Reality and grey-scale representation of vocal tract cavity. Quantitative data were drawn from the frames generating measurements of articulatory motion for the tongue, velum and jaw. This makes Southampton Dynamic MRI (SDMRI) method capable of producing results comparable to the data collected using a variety of other measurement techniques. The quantitative multi-planar data produced by SDMRI method can be used to achieve a better model of the speech production system.

Dust storms are one of the significant phenomena in the desert areas of the world. It is internationally agreed that days with visibility below 1000 metres due to dust present in the air are a result of strong winds. As Kuwait is part of the Arabian desert, which is identified as one of the major dust sources, so dust storm occurrence is more frequent especially during summer. Dust storms in Kuwait are mainly associated with north and north westerly winds, which are locally known `Shamal'. That is because this wind crosses the Iraqi and Arabian deserts before reaching Kuwait carrying a huge amount of dust and sand. There are local dust sources within Kuwait which supply these winds with dust. Dust occurs in Kuwait in four main types: 1) Sand/dust storm 2) Rising dust 3) Suspended dust 4) Haze There are many factors which play an important role in the occurrence of dust in Kuwait, they include the following: 1) Kuwait's location within the great desert belt. 2) Lack of rainfall. 3) Lack of vegetation cover. 4) Surface air turbulence due to huge amounts of radiation. 5) Human activities such as over-grazing, off-road driving. Dust and sand storms have a bad effect on environment in Kuwait. The main aspects of the environmental impact of dust which have been focussed on in this thesis, are: 1) Dust effects on vehicle body parts and the role of dust storms in road accidents due to poor visibility. 2) Dust effect on house parts and buildings. 3) Dust effects on human health from inhaling the fine dust particles which contain many organic and non-organic material. These materials, which are carried by dust, cause various types of allergies especially with respiratory system. There are many methods which have been used to reduce the amount of dust which is raised up in the air by strong winds. But it seems the most suitable method is tree planting which has many positive effects other than stabilising sand.

STATEMENT OF THE PROBLEM: There is no international standardized guidance to quantify translucency in dentistry. Numerous non-standardized terms are being used to describe the degree of translucency by the manufacturers. This makes it hard for the dental community to find definite and compare easy information. PURPOSE: To attempt exploring the standardization of the quantification of translucency in dental ceramics by comparing various optical property measurements including Contrast Ratio (CR), Translucency Parameter (TP) and transmission, gloss and surface roughness and by investigating the relationship between thickness, polish grade and translucency. MATERIAL AND METHODS: Four monolithic zirconia materials were used in this study; VITA-YZ Translucent, High Translucent, Super Translucent and Extra Translucent. IPS e.max CAD HT was used as a control. Specimens for each of these materials were prepared in 125 µm, 70 µm, 15 µm, and 0.5 µm polished surface in the following thicknesses: 1.00 mm, 0.75 mm, 0.50 mm and 0.35 mm thickness. Each group contained 10 specimens and the following tests were completed: transmission, CR and TP using a X-rite Ci6700 spectrophotometer, surface roughness by profilometer and gloss index by a glossmeter. Data was analyzed by using two-way ANOVA for different groups and Tukey’s for paired groups. Coefficient of absorption and loss of reflectance ratio were calculated. RESULTS: Reducing thickness and increasing polishing grade increase translucency. Material type, thickness and polishing grade significantly affected the translucency. A strong positive (r=0.99) linear correlation between transmission and TP was determined and these have a strong negative (r=-0.99) linear correlation with CR. CONCLUSION: Thickness, polishing grade and material type are major contributing factors to the translucency of ceramics. E.max HT is significantly more translucent than zirconia. Transmission is viable to be used as a standardized measurement of translucency with standardized material settings of 1mm thickness and optical polishing (polishing grade of 0.5 µm or its equivalent).

Abstract: Electron beam lithography (EBL) is the leading technology for versatile two dimensional patterning at the deep (10-100 nm) nanoscale. In addition to its reputation as an enabling technology for next generation advances in industry, its ease of use, accuracy, and cost has made it the technology of choice for rapid sub-micron prototyping in academia and research institutes worldwide. Advances in EBL processing have enabled sub-10 nm fabrication using a variety of materials under limited conditions. Repeatable processing at the deep nanoscale, particularly for dense nanostructure fabrication, requires a systematic quantitative study of all processing steps and their intricate interdependencies. In addition, developing future nanofabrication strategies with features approaching molecular length scales, requires a thorough examination of the molecular interactions taking place in EBL processing. This research project investigates EBL processing using PMMA and ZEP resists through an in-depth quantitative study and analysis of process windows for dense grating fabrication. The effect of processing parameters from each EBL stage on process windows is thoroughly investigated. Through the study of process windows and contrast curves, EBL processing strategies are developed and high resolution processing limits in PMMA and ZEP resists are explored. Furthermore, the EBL development stage involving resist-solvent interactions is studied using molecular dynamics simulations in Accelrys Materials Studio software package, and analyzed using the Flory-Huggins polymer physics theory. Finally, optimized processing strategies for dense grating fabrication are demonstrated and techniques are employed for the fabrication of record ultra-narrow (8 nm) suspended SiCN cantilever structures and high aspect ratio polymer fabrication using novel SML resist.

Australia is one of the most culturally diverse and prosperous societies in the world, and such heterogeneity or pluralism has both advantages and challenges. The Australian government must provide support to and for the integration of migrants, especially among those with a non-English-speaking background (NESB). Investments in information systems (IS) have resulted in the use of information and communication technology (ICT) to raise public awareness of the country’s policies, programmes and services. However, communication issues have recently emerged between the government’s online IS and the NESB migrants and their communities. Based on their increasing significance in Australia’s socio-economic and political landscape, it is necessary not only to identify and understand the needs of NESB migrants, but also to determine the barriers (both perceived and actual) that NESB migrants experience with regard to government online services (otherwise termed ‘e-government’). The key findings of this study are as follows: There were three primary needs mentioned most often by the Arabic community members that participated in this study. These primary needs are: 1) greater usability of all online services; 2) simplified design of website, including basic instructions; and 3) provide online services in Arabic rather than just in English. Specific barriers to accessing the government online services have been identified by means of this research, including: the perceived complexity of the language (English) used for the online services, language use (services need to be provided in Arabic), age of users (older users tend to be less likely to use online services) and lack of trust in the online services (fear of others obtaining private information). The issue of usability was critical in the context of this study, as the assumption is that the government is not currently providing online services that are sufficiently usable by a majority of the non-English-speaking Arabic community. The respondents were clear that the barriers preventing them from successfully accessing the local government online services made it difficult to gain full benefits from those services. By developing a new theoretical framework directed at eliminating the barriers for online government service usage by NESB community members, an NESB model that emphasises user-centricity is proposed. The framework combines several key themes: barriers to access, fit, usability, needs and computer/Internet skills. Interview findings involving several Arab migrants revealed that language and low computer skills are among the reasons why many NESB immigrants are discouraged or do not initially use government online services. The study recommends that heterogeneous countries such as Australia need to implement ICT-based or e-government policies, programmes and services that reflect culture and language sensitivity in order to effect meaningful and effective migrant integration. Further research implications are also cited.