Postgraduate Diploma
Permanent link for this collectionhttp://hdl.handle.net/10292/20523
The Postgraduate Diploma collection contains digital copies of AUT University PGDip. theses/ dissertations recommended by the relevant faculty for deposit with the Library. The AUT Postgraduate Diploma collection contains digital copies of theses/ dissertations from AUT's PGDip. students.
For theses/ dissertations submitted prior to 2007, open access was not mandatory, so only those theses for which the author has given consent are available in Tuwhera Open Theses & Dissertations. Where consent for open access has not been provided, the thesis is usually recorded in the AUT Library catalogue where the full text, if available, may be accessed with an AUT password. Other people should request an Interlibrary Loan through their library.
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Item Using RGB-D Cameras in Live Action Visual Effects(Auckland University of Technology, 2016) Kruse, JanFilm production greatly depends on digital visual effects to combine live action images and computer generated elements. The introduction of Deep Compositing streamlines the integration workflow of rendered computer images. This new technique relies on depth information, which is the distance between any objects in the scene and the camera itself. While depth data is available as a byproduct in computer generated images, live action camera files lack this kind of information. Only the recent arrival of a new generation of devices called RGB-D cameras, has enabled researchers and filmmakers to conduct first experiments with depth data in conjunction with live action images. The consistent acquisition of distance information and color pictures might allow for workflow improvements in live action visual effects similar to what has been demonstrated with Deep Compositing in conjunction with rendered computer images. This research is investigating the impact of RGB-D devices on established live action visual effects workflows. RGB-D images are used for effective CG placement, and a proof of concept workflow has been implemented. Findings related to quality, resolution and range of acquired images have been documented and discussed, and suggestions for future improvements of devices and workflows have been made.Item A Generic Platform for the Evolution of Hardware(Auckland University of Technology, 2009) Bedi, AbhishekEvolvable Hardware is a technique derived from evolutionary computation applied to a hardware design. The term evolutionary computation involves similar steps as involved in the human evolution. It has been given names in accordance with the electronic technology like, Genetic Algorithm (GA), Evolutionary Strategy (ES) and Genetic Programming (GP). In evolutionary computing, a configured bit is considered as a human chromosome for a genetic algorithm, which has to be downloaded into hardware. Early evolvable hardware experiments were conducted in simulation and the only elite chromosome was downloaded to the hardware, which was labelled as Extrinsic Hardware. With the invent of Field Programmable Gate Arrays (FPGAs) and Reconfigurable Processing Units (RPUs), it is now possible for the implementation solutions to be fast enough to evaluate a real hardware circuit within an evolutionary computation framework; this is called an Intrinsic Evolvable Hardware. This research has been taken in continuation with project 'Evolvable Hardware' done at Manukau Institute of Technology (MIT). The project was able to manually evolve two simple electronic circuits of NAND and NOR gates in simulation. In relation to the project done at MIT this research focuses on the following: To automate the simulation by using In Circuit Debugging Emulators (IDEs), and to develop a strategy of configuring hardware like an FPGA without the use of their company supplied in circuit debugging emulators, so that the evolution of an intrinsic evolvable hardware could be controlled, and is hardware independent. As mentioned, the research conducted here was able to develop an evolvable hardware friendly Generic Structure which could be used for the development of evolvable hardware. The structure developed was hardware independent and was able to run on various FPGA hardware’s for the purpose of intrinsic evolution. The structure developed used few configuration bits as compared to current evolvable hardware designs.Item Effect of Cyclodextrins on the Flavour of Goat Milk and Its Yoghurt(Auckland University of Technology, 2004) Gupta, RajniA previous study showed that addition of β-cyclodextrin to goat milk made a difference to its flavour, but in an undescribed way. Cyclodextrins (CDs, comprising α- β- and γ-CD) may be able to bind the free branched chain fatty acids in goat milk responsible for the largely undesirable ‘goaty’ flavour. The primary aim was to test the effect of CDs on this flavour in goat milk and its products with a view to marketing goat milk products with reduced flavour intensity. A secondary aim was to test the effect of β-CD on skatole flavour, a characteristic flavour of milk from pasturefed ruminants. Study design and methods: The present study evaluates addition of mainly β-CD to goat milk, cow milk and their products to reduce undesirable flavours. The methods applied were mainly ranking and hedonic assessment in sensory experiments. The tests done were with CDs added to buffers and milks, some of which were flavour-enhanced with 4-methyloctanoic acid as a representative goaty fatty acid, or with skatole. Goat milk yoghurts were also tested. Free fatty acid concentrations, which may be affected by CD binding, were measured after separating cream and skim milk. The methods applied were standard dairy procedures: titration of free fatty acids in milk fat and the copper-salt method for measuring fatty acids in skim milk. A fungal lipase was added to milks to accelerate fat hydrolysis (lipolysis). This was done to increase the concentration of free fatty acids for several experimental purposes. Some minor experiments studies were also done, for example the comparative effect of lipases on goat milk and cow milk, and the lipolytic activity at different temperatures over different times. Results: The results of skatole experiments were inconclusive. The odour of 4-methyloctanoic acid was reduced in acidic buffers by addition of α- and β-CD, particularly the former. Alpha and β-CD were both effective in goaty flavour reduction in goat milk. γ-CD was not effective. In all this work differences were statistically significant to varying levels. Goaty flavour was reduced by addition of β-CD to goat milk yoghurt, but only when added before fermentation (P < 0.001), not after (P = 0.09). The liking scores for goat milk yoghurts for both plain and flavoured yoghurts increased with β-CD treatment (both P < 0.001 for 59 panellists). The chemistry experiments revealed a reduction of free fatty acid concentration in the fat phase when β-CD treatment was added to full cream cow milk. However, analysis of skim milk did not show a corresponding increase in concentration. Further experiments are required to reveal the fate of the ‘missing’ fatty acids. Conclusion: Overall it was shown that under certain conditions, CDs were effective in reducing goaty flavour in milk and yoghurts. Whereas CDs are approved for addition to foods in many countries – including the bellwether U.S.A. – formal approval by Food Standards Australia New Zealand has not yet been finalized. When it is, the way should be clear to market a range of more consumer-acceptable goat milk products in New Zealand as a primary market. In short, this research has significant commercial relevance.Item The Effect of Heat Treatment Atmosphere on Hardening of Surface Region of H13 Tool Steel(Auckland University of Technology, 2007) Au, DominiqueThe cost of an aluminium extrusion die accounts for 35-50% of the total extrusion cost, hence it is important to understand the kinetics of extrusion die heat treatment. The main objective of die heat treatment is to increase the surface hardness so the surface wear property can be enhanced, which extends the die service life. Before the die material is case hardened by processes such as nitriding, the material is first heat treated to certain hardness. Thus the aim of this investigation is to understand the kinetics of carbon diffusion during steel austenitzation because it is significant to steel hardness property. H13 hot work tool steel, a well known material used as a die material for its superior mechanical and hardening properties, was used for the analysis of carbon diffusion during austenization. Samples made of H13 steel were subjected to four different atmospheric conditions: heat treatment without atmospheric control, heat treatment with stainless steel foil wrapping, pack carburization heat treatment and vacuum heat treatment. Three treatment time ranges were also applied for the carbon diffusion modelling. Some samples were further treated by gas nitriding to establish the effect of carbon content on the gas nitriding performance. It was found that decarburization occurred when atmospheric control did not take place during the heat treatment process. Through the carbon diffusion analysis, at austenitizing temperature of 1020ºC, the equilibrium surface carbon content at 1020ºC was 0.157wt%, with activation energy of carbon in H13 steel of 20,200cal/mol, and carbon diffusivity at 1020ºC was 1.97x10-8cm2/s. This study also proved that proper stainless steel foil wrapping on the heat treating material could restrict decarburization process, resulting in a constant hardness profile as vacuum heat treatment does. However the tempering characteristic between this two heat treatment methods are different to each other. For the pack carburization heat treatment, it was noted that the samples suffered from decarburization at early stage of heat treatment as carbon monoxide level was not adequate for carburization process. Results from the gas nitrided samples showed that the thickness and the hardness of the nitrided layer was independent to the carbon content in H13 steel. After 2 rounds of gas nitriding process, further nitriding seemed to have no significant effect on the hardness and thickness of the nitrided layer. Furthermore, the white layer was not observed in the nitrided samples which were heat treated without atmospheric control.Item Fate of Vitamin C in Commercial Fruit Juices(Auckland University of Technology, 2007) Nagra, SurinderVitamin C occurs in relatively high concentrations in fresh and processed fruits and vegetables but is found to a lesser extent in animal tissues and animal-derived products. Nearly 90 % of vitamin C in the human diet is obtained from fruits and vegetables but this can be indirect by way of commercially prepared fruit juices. These juices are often enriched with vitamin C which has been synthetically prepared. There is a wide range of such juices on the New Zealand market, and they are a significant source of dietary vitamin C for many in the population. The focus of this research is on the Keri range of juice products.The present study monitors the fate of vitamin C during storage of Keri juices up to the best-before date, and under a range of other storage and consumption situations. Two methods were adopted for determining ascorbic acid (AA, the chemical identity of vitamin C). These were the titrimetric method, which is based upon the reduction of the dye 2,6-dichlorophenolindophenol by AA in acidic solution, and liquid chromatography, which is used to separate AA from its immediate oxidation product dehydroascorbic acid. In the latter method these two analytes can be measured independently. The liquid chromatography was less successful than the simpler titrimetric method, so most of the work was done by titration. However, the concentration of dehydroascorbic acid, which has vitamin C activity in vivo, remained uncertain. Moreover, the titrimetric method could not be applied to juices with high purple anthocyanin concentrations, like blackcurrant, because the colour change at the titration end point could not be detected. pH adjustment to change colour was ineffective, and decolourisation with charcoal led to the rapid and complete destruction of AA. The concentration of AA in Keri juices at the time of manufacture were always much higher than claimed on the labels. Storage for up to nine months at room temperature resulted in a loss in AA of between 37 and 68 %, depending on the juice and exposure to fluorescent light. However, the time of storage was a much more dominant factor than light exposure. The kinetics of loss, straight lines, were most easily explained by an aerobic model of AA degradation from oxygen diffusing across the polyethylene tetraphthalate bottle wall. Overall, the label claims made were defensible in terms of the best-before date, because it took at least 100 days of storage before the AA concentration in the most susceptible juices fell below the claimed value. This is because these drinks are fast moving consumer goods and storage beyond 100 days is unlikely. (Nonetheless, the supplier (Keri Juice Company) has since adopted its new unitised method of formulating juice. This has resulted in an initially higher concentration of vitamin C as compared to the juices under investigation.) In the nine months storage experiment there was some evidence for the presence of dehydroascorbic acid in blackcurrant drinks, but not in another three juices. Pasteurisation during preparation of these drinks resulted in up to 7 % loss of AA, probably due to oxygen dissolved in water, and accelerated by heat of pasteurisation. Higher temperatures in later storage also accelerated losses. Progressive exposure of juice to air during simulated consumption of 3 L bottles over a week also accelerated losses. Finally, exposure to sunlight in a diurnal temperature environment accelerated losses five-fold higher than in total darkness. Filtration of ultraviolet light approximately halved the loss due to sunlight. Overall however, it can be concluded that AA in the Keri range of juices is very resistant to degradation of AA.