• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 83
  • 4
  • Tagged with
  • 87
  • 79
  • 79
  • 78
  • 77
  • 77
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Influence of coal ash and process conditions on coal/char reactivity for PCI into BF

Al-Omari, Yaser, Materials Science & Engineering, Faculty of Science, UNSW January 2004 (has links)
The combustion efficiency of pulverised coal injection PCI is an important factor influencing stability and productivity of the blast furnace. It is affected by coal properties and the process conditions employed for combustion. Economic considerations have driven blast furnace operators to commission a wide range of coals, which differ in type and rank. The main objective of the current project is to study the influence of different operating conditions on combustion performance of coal and to examine the role of coal minerals and their transformations on low and high temperature reactivity. The combustion performance of three PCI coals was investigated under a range of combustion conditions including three combustion temperatures of 900??C, 1200??C and 1500??C, and a range of oxygen concentrations in the gas phase at 1200??C in a drop tube furnace (DTF). The low temperature oxygen reactivity of pyrolysed chars was also measured by observing weight loss in a thermogravimetric (TGA) furnace at 600??C. Physical and chemical properties of pyrolysed and partially combusted chars were characterised using a range of analytical tools including X-ray diffraction, scanning electron microscopy, BET N2 surface area and Hg porosity. The correlation between char properties and char reactivity at low and high temperatures was also investigated. All three coal samples experienced deactivation during progressive combustion at 1200??C and 23%v O2 i.e. there was a decrease in the reaction rate with proceeding combustion. The carbon structure of the chars became increasingly ordered as quantified by an increase in crystallite height and a decrease in the amorphous carbon proportion in char. Partially combusted char had much higher surface area than a pyrolysed one, which can be attributed to the opening of enormous number of closed pores as combustion proceeds. However, this increase in surface area did not show a direct correlation with char reactivity. Average particle size of ash increased with increasing degree of combustion due to fusion and agglomeration of coal minerals. Under these conditions, carbon structural ordering of char was found to be one of the key factors primarily responsible for loss of char reactivity during combustion. Increasing oxygen content in the gas stream from 23% to 35% at 1200??C resulted in a significant improvement in the combustion performance of three coals, with burnout increasing from ~65% to up more than ~95%. However, increasing oxygen level beyond 35% did not lead to any further significant improvements. Coal burnout was also enhanced by increasing temperature in the range 900??C to 1500??C, such that the improvement was much more rapid in the higher temperature range of 1200??C to 1500??C. This could be related to increased reaction rates at higher temperatures. Pyrolysed char reactivity was measured at low temperature 600??C and 10%v O2 using TGA. The results indicated that the presence of iron and calcium minerals could result in enhanced char reactivity. Coal minerals underwent increased fusion and melting as the combustion temperature was increased. At 1500??C, most ash particles were molten. The level of basic oxides in ash as well as the extent of association between aluminosilicates and basic oxides enhanced the proportion of molten phases. Fusing and melting behaviour of ash particles was found to influence char combustion reactivity at high temperatures. Ash melting on the char surface may hinder gas accessibility to the reactive surface of char, thereby decreasing char burnout. The molten ash particles may coalesce and cover char surface or these molten particles may partially/completely block char pores. The amount of slag phases in ash and the distribution of minerals in char are expected to have a significant influence on ash-char interactions at high temperatures. In summary, the study shows that inorganic matter present in coal can affect coal combustion in a number of ways. Inorganic minerals, such as iron and calcium catalyse char oxidation at low temperatures. On the other hand, these minerals may act as fluxing agents at high temperatures, which could lower the melting point of aluminosilicates minerals in char. The molten phases of ash may restrict the accessibility of oxygen to carbon in char through physical obstruction, thereby, retard char oxidation.
42

The molecular characterisation of sol-gel biocatalysts

Rodgers, Lisa Elizabeth, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW January 2006 (has links)
Sol-gel matrices may be used to immobilise enzymes, facilitating retention of the catalyst while allowing a flow of substrates and products through the matrix. Candida antarctica lipase B (CALB), a commonly used industrial enzyme, has been shown to have a prolonged catalytic life and enhanced activity when encapsulated in these sol-gel materials. However, the molecular basis for this effect had yet to be elucidated. This study investigated the effect of encapsulating CALB in sol-gel matrices by comparison of CALB in solution with its encapsulated form. Use of complementary techniques revealed the presence of complex interactions between the enzyme and the evolving sol-gel material. 29Si Nuclear Magnetic Resonance (NMR) measurements demonstrated that CALB influenced sol-gel structure by altering silica speciation. Inclusion of CALB also altered the mesoporosity of the matrices as determined using nitrogen sorption and electron microscopy. Correlation of activity assays with 29Si speciation changes indicated that the catalytic activity of the enzyme in solution was directly involved in sol-gel hydrolysis and condensation reactions. Increased specific activity of CALB in the sol-gel aqueous precursor solution resulted in measurable changes in the gel structure of matrices containing 3.1mg of CALB/ml of gel. Small angle neutron scattering (SANS) was used to examine the structure of CALB in solution. The influence of the sol-gel reactants glycerol, sodium fluoride and isopropanol upon the radius of gyration of CALB in solution was determined. SANS was also employed in an investigation of encapsulated CALB molecules which utilised contrast matching of the sol-gel matrix. However, contrast variation studies found that the match point for the silica matrix, both with and without enzyme present, was lower than predicted (~35% vol% D2O). Consequently, the contrast match point of the protein was close to that of the encapsulating material. Scattering from the encapsulated protein at this point was therefore minimal; it is clear that the contrast match point of the protein should be moved through in vivo deuteration in future experiments of this type. These investigations advance the understanding of interactions between the matrix and the encapsulated enzyme in sol-gel biomaterials.
43

The molecular characterisation of sol-gel biocatalysts

Rodgers, Lisa Elizabeth, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW January 2006 (has links)
Sol-gel matrices may be used to immobilise enzymes, facilitating retention of the catalyst while allowing a flow of substrates and products through the matrix. Candida antarctica lipase B (CALB), a commonly used industrial enzyme, has been shown to have a prolonged catalytic life and enhanced activity when encapsulated in these sol-gel materials. However, the molecular basis for this effect had yet to be elucidated. This study investigated the effect of encapsulating CALB in sol-gel matrices by comparison of CALB in solution with its encapsulated form. Use of complementary techniques revealed the presence of complex interactions between the enzyme and the evolving sol-gel material. 29Si Nuclear Magnetic Resonance (NMR) measurements demonstrated that CALB influenced sol-gel structure by altering silica speciation. Inclusion of CALB also altered the mesoporosity of the matrices as determined using nitrogen sorption and electron microscopy. Correlation of activity assays with 29Si speciation changes indicated that the catalytic activity of the enzyme in solution was directly involved in sol-gel hydrolysis and condensation reactions. Increased specific activity of CALB in the sol-gel aqueous precursor solution resulted in measurable changes in the gel structure of matrices containing 3.1mg of CALB/ml of gel. Small angle neutron scattering (SANS) was used to examine the structure of CALB in solution. The influence of the sol-gel reactants glycerol, sodium fluoride and isopropanol upon the radius of gyration of CALB in solution was determined. SANS was also employed in an investigation of encapsulated CALB molecules which utilised contrast matching of the sol-gel matrix. However, contrast variation studies found that the match point for the silica matrix, both with and without enzyme present, was lower than predicted (~35% vol% D2O). Consequently, the contrast match point of the protein was close to that of the encapsulating material. Scattering from the encapsulated protein at this point was therefore minimal; it is clear that the contrast match point of the protein should be moved through in vivo deuteration in future experiments of this type. These investigations advance the understanding of interactions between the matrix and the encapsulated enzyme in sol-gel biomaterials.
44

Consenting adults in private: in search of the sexual subject

Gleeson, Kate, School of Politics & International Relations, UNSW January 2006 (has links)
In this thesis I examine the ways in which the modern state addresses sex. I want to ascertain by what considerations the state is informed in its relationship to sex. What is behind the state???s regulation of sexual practices? What is its interest in regard to sex? To answer these questions I examine fundamental artefacts of the modern state, especially the law (but also the bureaucracy), as directed by the 1993 English court case of Brown. Brown involves the search for the sexual subject; The Lords in Brown were at a loss for how to conceptualise the subject before them. Their search is my own: who is the sexual subject? What is his relationship to the state? To answer these questions, Brown directs me for authority to two widely separated moments of supposed classic ???discontinuity???: the 1957 Wolfenden Report, and the late-Victorian Queen???s Bench. These two moments in government - the 1960s and the 1880s - are usually depicted as ideologically different, indicating discontinuity, difference, change and perhaps even revolution between the relative approaches of the state to sex. And yet, in Brown, both are upheld as appropriate contemporary authorities on sex, the individual and the state. Here I take my cue from the Lords and interrogate the artefacts of these two periods in government to ascertain the story of the 20th century state???s relationship to sex. My thesis is a political analysis that incorporates genealogy in its focus on law as indicative of the state. It incorporates a detailed study of primary artefacts of the state: detailed analyses of seemingly discontinuous moments including individual court cases, individual Committees, individual treatises and opinions and political memoirs. I conclude by drawing together my overall argument, that during the 20th century there has been no radical change of the modern state in regard to sex, and that the success of the permissive mythology has generally blinded us to this fact. Not only have we mistaken the nature of the permissive state as concerned with evolution, we have erroneously been persuaded of the blanket repression of the Victorian state. The big break, the discontinuity of the 1960s, that often is described as ???revolutionary??? (and inevitable in the teleology of progress), is a re-configuration of the same object as the Victorian state. The permissive state enacts the latest stage in the great Victorian project of embodying the sexual subject ??? a subject at once embodied and created as an object of control.
45

In vivo bone formation using Adipose Derived Stromal Stem Cells. The histomorphometry of the ovine defect model

Niechoda, Beata, School of Surgery, UNSW January 2006 (has links)
The use of stem cells to augment the healing of bone defects represents an exciting new frontier in many surgical disciplines. This thesis verified the in vitro osteogenic capability of ovine Adipose Derived Stromal Stem Cells (ADSCs) and Bone Marrow Derived Stem Cells (BMSCs), examined the in vivo osteogenic potential of the ovine ADSCs population and compared it to the in vivo osteogenic potential of ovine BMSCs. The pilot study used both cell populations, expanded and osteogenically stimulated ex vivo and mixed with resorbable porous hydroxyapatite-calcium carbonate bone graft substitute (ProOsteon 200R, Interpore Cross International, Irvine, CA). This study demonstrated the preferred length of time in ex vivo osteogenic stimulation of the ADSCs and BMSCs populations to promote the bone formation in vivo to be 7 days. In the main ovine study which employed 48 wethers, ADSCs and BMSCs were expanded, stimulated osteogenically for 7 days, mixed with ProOsteon 200R and deposited in an autologous manner into a bilateral medial femoral condyle confined cancellous defect. In vivo performance of 7 treatment groups was examined: 1. ???Bone autograft/ADSCs???, 2. ???Bone autograft/BMSCs???, 3. ???ProOsteon 200R/ADSCs???, 4. ???ProOsteon 200R/BMSCs???, 5. ???Bone autograft???, 6. ???ProOsteon 200R??? and 7. ???Empty defect???. The time-points were: 2, 4, 8 and 12 weeks. The analysis of the harvested specimens used the following methods: computerized tomography, histological assessment, histomorphometry and immunohistochemistry. There was a progressive and time dependant increase in woven bone in the defects treated with ADSCs and BMSCs across all time points. The amount of woven bone in the defects treated with the combination of ADSCs and ProOsteon 200R was comparable with the defects treated with the combination of BMSCs and ProOsteon 200R. In addition, the combination of ADSCs or BMSCs and ProOsteon 200R demonstrated no more bone than ProOsteon 200R alone. However, the ???Autograft/BMSCs??? and ???Autograft/ADSCs??? groups demonstrated a remarkable increase in the amount of woven bone formed in the defects across all time points when compared with all other groups. In addition, the amounts of bone formed in the ???Autograft/BMSCs??? and the ???Autograft/ADSCs??? group were comparable across all timepoints. The results of these studies support the hypothesis that ovine ADSCs and BMSCs populations in combination with the bone autograft can increase the formation of woven bone in the autologous orthotopic environment in a comparable manner.
46

Influence of coal ash and process conditions on coal/char reactivity for PCI into BF

Al-Omari, Yaser, Materials Science & Engineering, Faculty of Science, UNSW January 2004 (has links)
The combustion efficiency of pulverised coal injection PCI is an important factor influencing stability and productivity of the blast furnace. It is affected by coal properties and the process conditions employed for combustion. Economic considerations have driven blast furnace operators to commission a wide range of coals, which differ in type and rank. The main objective of the current project is to study the influence of different operating conditions on combustion performance of coal and to examine the role of coal minerals and their transformations on low and high temperature reactivity. The combustion performance of three PCI coals was investigated under a range of combustion conditions including three combustion temperatures of 900??C, 1200??C and 1500??C, and a range of oxygen concentrations in the gas phase at 1200??C in a drop tube furnace (DTF). The low temperature oxygen reactivity of pyrolysed chars was also measured by observing weight loss in a thermogravimetric (TGA) furnace at 600??C. Physical and chemical properties of pyrolysed and partially combusted chars were characterised using a range of analytical tools including X-ray diffraction, scanning electron microscopy, BET N2 surface area and Hg porosity. The correlation between char properties and char reactivity at low and high temperatures was also investigated. All three coal samples experienced deactivation during progressive combustion at 1200??C and 23%v O2 i.e. there was a decrease in the reaction rate with proceeding combustion. The carbon structure of the chars became increasingly ordered as quantified by an increase in crystallite height and a decrease in the amorphous carbon proportion in char. Partially combusted char had much higher surface area than a pyrolysed one, which can be attributed to the opening of enormous number of closed pores as combustion proceeds. However, this increase in surface area did not show a direct correlation with char reactivity. Average particle size of ash increased with increasing degree of combustion due to fusion and agglomeration of coal minerals. Under these conditions, carbon structural ordering of char was found to be one of the key factors primarily responsible for loss of char reactivity during combustion. Increasing oxygen content in the gas stream from 23% to 35% at 1200??C resulted in a significant improvement in the combustion performance of three coals, with burnout increasing from ~65% to up more than ~95%. However, increasing oxygen level beyond 35% did not lead to any further significant improvements. Coal burnout was also enhanced by increasing temperature in the range 900??C to 1500??C, such that the improvement was much more rapid in the higher temperature range of 1200??C to 1500??C. This could be related to increased reaction rates at higher temperatures. Pyrolysed char reactivity was measured at low temperature 600??C and 10%v O2 using TGA. The results indicated that the presence of iron and calcium minerals could result in enhanced char reactivity. Coal minerals underwent increased fusion and melting as the combustion temperature was increased. At 1500??C, most ash particles were molten. The level of basic oxides in ash as well as the extent of association between aluminosilicates and basic oxides enhanced the proportion of molten phases. Fusing and melting behaviour of ash particles was found to influence char combustion reactivity at high temperatures. Ash melting on the char surface may hinder gas accessibility to the reactive surface of char, thereby decreasing char burnout. The molten ash particles may coalesce and cover char surface or these molten particles may partially/completely block char pores. The amount of slag phases in ash and the distribution of minerals in char are expected to have a significant influence on ash-char interactions at high temperatures. In summary, the study shows that inorganic matter present in coal can affect coal combustion in a number of ways. Inorganic minerals, such as iron and calcium catalyse char oxidation at low temperatures. On the other hand, these minerals may act as fluxing agents at high temperatures, which could lower the melting point of aluminosilicates minerals in char. The molten phases of ash may restrict the accessibility of oxygen to carbon in char through physical obstruction, thereby, retard char oxidation.
47

Origins and destinations: representation in the theatre of Romeo Castellucci

Lyandvert, Max, School of Theatre, Film & Media, UNSW January 2006 (has links)
This thesis: Origins and Destinations: Representation in the theatre of Romeo Castellucci, investigates the working methodology of the Italian theatre director, Romeo Castellucci and his company, Societas Raffaello Sanzio. It provides an account of Societas Raffaello Sanzio???s history, working methods, a detailed reading of the thematic and philosophical landscape in their works especially Genesi: from the museum of sleep, and the cycle: Tragedia Endogonidia, and a discussion on the company???s artistic process towards the formation of its compositions and performances. This research and investigation is based on numerous viewings of most of the company???s theatre works created in the last six years, interviews with Romeo Castellucci as well as other participating artists, two privileged periods of observation (residencies) in Italy of the rehearsal and creation processes of three shows, and the analysis and discussion of some of the key critical and intellectual responses to the work of Romeo Castellucci. The thematic focus of the thesis is the notion of Origins and Destinations, and its relationship with the language of representation in Romeo Castellucci???s theatre. The theoretical discussion in the thesis is organised around Giorgio Agamben???s notion of Potentiality within the composition and content of Castellucci???s theatre. This concept provides a link between the key ideas of Origins, Destinations and Representation. Castellucci???s application of Agamben???s Potentiality deconstructs dramatic structure, narrative and action down to the fundamentals of the act itself, separated from its meaningful context. It is the conclusion of this thesis, that in the instant of this singular act, Romeo Castellucci manages to represent a point where origin and destination meet, or a point where they both are, for an instant, one and the same thing.
48

The Flinders current and upwelling in submarine canyons

Arthur, William Craig, School of Mathematics, UNSW January 2006 (has links)
The continental shelf off South Australia is incised by some of the largest known submarine canyons. Extensive observations of submarine canyons in other parts of the world have shown submarine canyons can result in locally persistent upwelling regions. Along the southern coastline, westward slope currents including anticyclonic eddies and the Flinders Current (FC) can result in favourable conditions for upwelling in the vicinity of these canyons. Little data is available to describe the FC and so we review three global ocean circulation models and their representation of the FC. Though there are considerable differences between the outputs of these three models, this analysis provides a range of potential scales for the structure and transport of the FC. The reasons for the differences between the output of the three models are extensive, but to a first approximation, climatological surface wind stress products are compared. Dynamical descriptions of the flow past submarine canyons are reviewed and in part extended, in particular the vertical scale of the induced motion is estimated as the Rossby height RH. A description of upwelling and downwelling flow incorporating vorticity stretching is also presented. An idealised model of the southern Australian continental shelf and the submarine canyons reveals the circulation is heavily modified by the presence of the canyons, inducing persistent upwelling of dense water onto the downstream shelf. In addition, one prominent feature of the induced circulation ??? a coastal jet ??? is found to be peculiar to flat inner shelf topographies. More realistic topography including a sloped inner shelf results in reduced shoreward transport within the canyon and hence reduced upwelling.
49

Long term housing prices in Australia and some economic perspectives

Stapledon, Nigel David, Economics, Australian School of Business, UNSW January 2007 (has links)
This thesis constructs, principally from primary sources, a long term time series for house and land prices for Sydney and Melbourne, and house price and rental yield series for Australia. These new series span the period 1880-1965 and give an historical perspective beyond the period from 1970 for which existing house price time series begin for Australia and for most of the world. The price series indicates that the modern experience (i.e. since the 1970s) of a significant upward trend in real prices differs markedly from the experience in the first half of the 20th century when house prices moved very little. The thesis then takes several approaches to explaining the apparent shift in direction in the mid 20th century. The first approach examines house prices in terms of demand and supply variables. Urban theory says that demographic and income factors are critical. However, assessed over this long time span, these demand factors do not offer a satisfactory explanation. Additionally, it is found that there is no cointegrating relationship between prices and income. Rather, it appears that supply factors have probably been the pivotal influence in explaining the shift in direction, consistent with a growing literature which focuses on the role of regulation and other constraints on supply. In Australia???s case, government policies imposing capital contributions on the cost of land appear to be a major factor. The second approach taken is to view housing in terms of asset pricing as more typically applied to the equity market by Campbell and Shiller (1988) and others. A central debate is whether or not there has been a structural fall in the equity yield and given the parallel fall in the house yield, this question is posed for housing. The thesis finds that tax and other factors can explain a structural decline in the housing yield. The house rental yield appears to be a better predictor of future rental growth and a negative predictor of future returns.
50

Relationship between students??? approaches to learning and the development of clinical reasoning ability

Tetik, Cihat, Public Health & Community Medicine, Faculty of Medicine, UNSW January 2006 (has links)
This study investigates the relationship between learning approaches and the development of clinical reasoning ability. The main questions for the study were: Is there a statistically significant relationship between students??? learning approaches and development of clinical reasoning ability? If there is a relationship between approaches to learning and development of clinical reasoning ability, which students develop this ability faster? And How does learning approach change relate to the development of reasoning ability? The Revised Two-Factor Study Process Questionnaire (R-SPQ-2F) was used in order to evaluate participants??? learning approaches and Diagnostic Thinking Inventory (DTI) to measure participants??? diagnostic thinking ability. In order to determine changes of learning approaches, the same students were invited to fill out the same questionnaires one year later. This quantitative study was followed by a qualitative inquiry including in-depth interviews aimed at exploring the association of a change in learning approach score with the development of clinical reasoning ability. These interviews also explored the factors influencing learning approaches of these students. Those students with the greatest change in R-SPQ-2F scores between the two surveys were selected for interview. Analysis of the findings of both the quantitative and qualitative phases of this research leads the researcher to conclude that; - there is a correlation between ongoing learning approaches and the development of clinical reasoning ability; this correlation is positive if the approach is deep and it is negative if the approach is surface, - progress towards either end of the learning approach continuum is associated with observation of experts, reasoning practice and/or feedback from experts, and - progress towards either end of the learning approach continuum seems an earlier and better indicator of developing reasoning ability than categorization of learning approach because both learning approach change and the factor causing this change were associated with the development of clinical reasoning ability. This study contributes to understanding of the importance of ongoing learning approaches and the development of clinical reasoning ability by encouraging deep learning approach characteristics. Factors affecting learning approaches are also associated with the development of clinical reasoning ability. Their effect is more than expected.

Page generated in 0.0175 seconds