Low Pressure Die Casting (LPDC) process is one the most common casting process to produce structural automotive components, such as alloy wheels and suspension components. It has been identified that cavity filling and solidification process are two most critical aspects to produce premium quality casting components.During the solidification process of casting alloy, it is a well known phenomenon that metal experiences volumetric shrinkage due to its density difference between liquid and solid phase. When this volumetric shrinkage is not properly compensated, then a casting defect commonly known as solidification shrinkage occurs. The solidification shrinkage has very detrimental effects on structural integrity required for premium quality casting such as aluminium alloy wheels.Literature and practical experiences of foundry men show that it is critical to achieve unidirectional solidification pattern by avoiding an isolated hot spot in order to minimise the solidification shrinkage. However, it is found that the geometry of industrial casting applications is often constrained by other design factors that would not naturally avoid these isolated hot spots. The subject of this research, aluminium alloy wheels, is not excluded from this constraint.In aluminium alloy wheels, an isolated hot spot is commonly observed in an area known as rim and spoke junction due to its geometry constraints. Consequently, the solidification shrinkage is commonly experienced, which is undesirable due to its detrimental effects for the structural integrity of alloy wheels. In order to minimise the solidification shrinkage, forced cooling method is applied to avoid an isolated hot spot. The control of this forced cooling is achieved by cooling media, flow rate of cooling media and duration cooling circuit. Foundry experiments in industrial environment were conducted producing aluminium alloy wheels using commercially treated A356 (Al-Si) alloy, where different durations of cooling circuit were used to understand the sensitivity of solidification shrinkage formation to the duration of cooling circuit. This was followed by metallurgical structure analysis and numerical modelling to suggest the sensitivity of cooling circuit duration in controlling solidification shrinkage.The major finding conclusion of this research is that control of the shrinkage formation is not very sensitive to the duration cooling circuit. It is suggested that as casting solidifies initially from the mould wall, it retracts away from the cast-mould interface due to thermal contraction. Consequently, air gap is formed between casting and mould interface, creating an effective thermal resistance layer. Thereafter, heat transfer across the cast-mould interface is not sensitive to the change in the cooling channel which is a distance to the cast-mould interface.Some limitations of numerical modelling and metallurgical analysis were also identified during this research and recommendations were made to improve the accuracy of local hot spot prediction in production of aluminium alloy wheels. More specifically, numerical modelling of the effect of grain refinement and use of non homogeneous material property (particularly fraction of solid) for rapidly chilled area. Fraction of eutectic rather than secondary dendrites arm spacing is a proper microstructure parameter that can be used to locate the hot spot.

This thesis presents the results of research into the use of factor models for stationary economic time series. Two basic scenarios are considered. The first is a situation where a large number of observations are available on a relatively small number variables, and a dynamic factor model is specified. It is shown that a dynamic factor model may be derived as a representation of a VARMA model of reduced spectral rank observed subject to measurement error. In some cases the resulting factor model corresponds to a minimal state-space representation of the VARMA plus noise model. Identification is discussed and proved for a fairly general class of dynamic factor model, and a frequency domain estimation procedure is proposed which has the advantage of generalising easily to models with rich dynamic structures. The second scenario is one where both the number of variables and the number of observations jointly diverge to infinity. The principal components estimator is considered in this case, and consistency is proved under assumptions which allow for much more error cross-correlation than the previously published theorems. Ancillary results include finite sample/variables bounds linking population principal components to population factors, and consistency results for principal components in a dual limit framework under a `gap' condition on the eigenvalues. A new factor model, named the Grouped Variable Approximate Factor Model, is introduced. This factor model allows for arbitrarily strong correlation between some of the errors, provided that the variables corresponding to the strongly correlated errors may be arranged into groups. An approximate instrumental variables estimator is proposed for the model and consistency is proved.

This project was the very beginning of research into the chemistry of eastern Australian banksia flowers. Using dynamic headspace sampling (DHS) analysis, differences in volatile components, consistent with detection of differences in odour, were detected among three different species and one commercial cultivar. Infraspecific variation was also observed between two known subspecies of Banksia ericifolia and between differently coloured forms of Banksia spinulosa var. collina. The cultivar, Banksia 'Giant Candles', was shown to have some of the chemical components of each of its supposed ancestors. The absence of known wound-response chemicals indicated that this DHS method was successful in leaving the inflorescences undamaged throughout the sampling procedure. The Likens-Nickerson modification of classical hydrodistillation methods was useful. The static headspace method (SHS) was easily automated and was shown to be chemically robust and sufficiently sensitive to detect volatile compounds from only a few flowers. The milder DHS method, which minimised mechanical and heat damage to the plant tissue, produced a different set of results. From the results of this project, a suite of volatile compounds has been proposed that may be useful in future behavioural studies to help determine whether animals are attracted to components of banksia odours. These candidates include some compounds that have been reported in animal secretions, wound-response chemicals that may be produced by the plant to aid its communication with other organisms, and a compound (suggested to be sulfanylmethyl acetate) not previously reported from natural sources. The mildest of the three analytical methods used, dynamic headspace sampling, was shown to be suitable for the potential chemotaxonomic evaluation of some members of the Banksia genus. / Doctor of Philosophy (PhD)

In this dissertation, application of multi-way analysis is extended into new areas of environmental chemistry, microbiology, electrochemistry and organometallic chemistry. Additionally new practical aspects of some of the multi-way analysis methods are discussed. Parallel Factor Analysis Two (PARAFAC2) is used to classify a wide range of weathered petroleum oils using GC-MS data. Various chemical and data analysis issues exist in the current methods of oil spill analysis are discussed and the proposed method is demonstrated to have potential to be employed in identification of source of oil spills. Two important practical aspects of PARAFAC2 are exploited to deal with chromatographic shifts and non-diagnostic peaks.GEneralized Multiplicative ANalysis Of VAriance (GEMANOVA) is applied to assess the bactericidal activity of new natural antibacterial extracts on three species of bacteria in different structure and oxidation forms and different concentrations. In this work while the applicability of traditional ANOVA is restricted due to the high interaction amongst the factors, GEMANOVA is shown to return robust and easily interpretable models which conform to the actual structure of the data. Peptide-modified electrochemical sensors are used to determine three metal cations of Cu2+, Cd2+ and Pb2+ simultaneously. Two sets of experiments are performed using a four-electrode system returning a three-way array of size (sample ?? current ?? electrode) and a single electrode resulting in a two-way data set of size (sample ?? current). The data of former is modeled by N-PLS and that latter using PLS. Despite the presence of highly overlapped voltammograms and several sources of non-linearity N-PLS returns reasonable models while PLS fails. An intramolecular hydroamination reaction is catalyzed by several organometallic catalysts to identify the most effective catalysts. The reaction of starting material in the presence of 72 different catalysts is monitored by UV-Vis at two time points, before and after heating the mixtures in an oven. PARAFAC is applied to the three-way data set of (sample ?? wavelength ?? time) to resolve the overlapped UV-Vis peaks and to identify the effective catalysts using the estimated relative concentration of product (loadings plot of the sample mode).

L'intérêt et le développement des microsystèmes aujourd'hui sont basés sur les mêmes principes qui ont fait le succès des circuits intégrés. Comme dans la microéléctronique, le silicium est le matériau le plus utilisé parmi les microsystèmes. Malgré cette hégémonie, il existe d'autres alternatives pour les applications où le silicium n'est pas très performant. L'arséniure de gallium (AsGa) se montre prometteur car des effets comme la piézo­électricité, la piézo­resistivité et l'émission de rayonnement lumineux peuvent efficacement être exploités. <br />La fabrication des microstructures suspendues (mécaniques) compatibles avec des <br />technologies standards des circuits intégrés en AsGa est présentée dans cette thèse. Ces <br />microstructures sont obtenues à travers le micro­usinage en volume par la face avant et ne demandent <br />aucune modification du procédé si ce n'est une étape post­process de gravure destinée à libérer les <br />structures devant être suspendues. Ce principe permet la fabrication collective en grandes quantités et <br />à bas coût puisque s'insérant dans une filière industrielle stabilisée. <br />Dans ce travail, plusieurs solutions de gravure ont été étudiées et caractérisées. Les vitesses de <br />gravure et les éventuels dégâts dans les couches diélectriques et de métallisation des plots ont été <br />vérifiés. A partir de ces résultats, deux applications potentielles pour les microsystèmes en AsGa ont <br />été considérées : les composants thermiques qui tirent parti du coefficient Seebeck de l'AsGa et de <br />l'isolation thermique des structures suspendues, et les composants électroniques passifs micro­usinés <br />pour les circuits micro­ondes, comme les lignes micro­rubans et les inductances planaires. <br />Finalement, un ensemble d'outils de CAO pour les microsystèmes a été développé. Des modules <br />spécifiques ont été assemblés à l'environnement Mentor Graphics, comme par exemple la vérification <br />des règles de dessins pour les microsystèmes, des outils pour la visualisation du layout en coupe et en <br />trois dimensions, et des simulateurs de gravure. <br />Mots clés microsystèmes, arséniure de gallium, micro­usinage, thermocouple, inductance <br />planaire, outils de CAO.

<p>The goal of this project was to implement and compare Invere Discrete Cosine Transform using three methods i.e. by bit parallel, digit serial and bit serial. This application describes a one dimensional Discrete Cosine Transform by bit prallel method and has been implemented by 0.35 ìm technology. When implementing a design, there are several considerations like word length etc. were taken into account. The code was implemented using WHDL and some of the calculations were done in MATLAB. The VHDL code was the synthesized using Design Analyzer of Synopsis; power was calculated and the results were compared.</p>

<p>Background: The fast growing tourism industry increases the need for new destinations to meet the markets demand. Because of this, destination development becomes a part of tourism development and it can therefore be interesting and relevant to study this phenomenon. It requires consciousness about the destination’s conditions and to what extent tourism can be developed. The study of these conditions can be useful as they are fundamental for future tourism development at a destination.</p><p>Purpose: The purpose of this study is to describe and analyze which conditions and characteristics a place should have to become an attractive destination.</p><p>Methodology: This study has been executed from a positivistic point of view and a quantitative approach. The collection of data has been carried out through five semi-structured interviews.</p><p>Conclusions: This study has reached the conclusion that developing tourism at a destination requires a number of specific characteristics, but that these may vary depending on the type of destination. There are several characteristics but the most emphasized are attractions and activities, accessibility and infrastructure, amenities, political stability and safety.</p> / <p>Bakgrund: Den snabbt växande turismnäringen ökar behovet av fler destinationer för att möta den ökade efterfrågan på marknaden. Destinationsutveckling blir därför en grundläggande del i arbetet med turismutveckling och det kan därför vara intressant och relevant att studera detta. Det krävs en medvetenhet om vilka förutsättningar som finns och i vilken utsträckning turism kan utvecklas utifrån dessa. Vilka dessa förutsättningar är kan vara intressant att undersöka då de ligger till grund för framtida turismutveckling på en destination.</p><p>Syfte: Syftet med undersökningen är att beskriva och analysera vilka förutsättningar och attribut en plats bör ha för att bli en attraktiv destination.</p><p>Metod: Denna studie har utgångspunkt i ett positivistiskt synsätt och en kvantitativ ansats. Vid datainsamlingen har fem semi-strukturerade intervjuer genomförts.</p><p>Slutsatser: Slutsatsen av studien är att det krävs vissa specifika förutsättningar för att utveckla turism på en destination, men att dessa kan variera beroende på typ av destination. Det finns ett antal sådana förutsättningar, men de som tydligast framkommer är attraktioner och aktiviteter, tillgänglighet och infrastruktur, ett grundläggande serviceutbud samt någon form av politisk stabilitet och trygghet.</p>

<p>Bacillus anthracis is one of the most feared agents of biological warfare and causes the</p><p>deadly disease called anthrax. SVA (statens veterinärmedicinska anstalt) is working on a</p><p>project together with SLV (statens livsmedelsverk) where the target is to find rapid and</p><p>effective detection methods for Bacillus anthracis in animal feed and food samples. Bacillus</p><p>subtilis, which is harmless, was used in this study as a model organism to Bacillus anthracis.</p><p>A known concentration of vegetative Bacillus subtilis was spiked in animal feed and food</p><p>samples. The genomic work flow was based on automated DNA isolation and real time PCR.</p><p>The aim of the study was to screen for inhibitory components in the animal feed and food</p><p>samples using two different DNA isolation robots; Magnatrix 8000 and Biorobot EZ1. The</p><p>results showed that DNA of high quality was extracted from the samples with both robots.</p><p>However, the CT-value generated by the real time PCR showed considerable variation</p><p>depending on the sample matrix. Some samples, for instance egg and liver, were problematic</p><p>and gave low concentrations and high CT-values probably due to inhibitory components in the</p><p>samples. Further studies will be needed to solve these problems and optimize the methods that</p><p>were used in this study.</p>

Dolphinfish (Coryphaena hippurus) is a pelagic species that is ecologically and commercially important in the western Atlantic region. This species has been linked to dominant oceanographic features such as sea surface temperature (SST) frontal regions. This work first explored the linkages between the catch rates of dolphinfish and the oceanography (satellite-derived SST, distance to front calculations, bottom depth and hook depth) using Principal Components Analysis (PCA). It was demonstrated that higher catch rates are found in relation to warmer SST and nearer to frontal regions. This environmental information was then included in standardizations of catch-per-unit-effort (CPUE) indices. It was found that including the satellite-derived SST and distance to front increases the confidence in the index. The second part of this work focused on addressing spatial variability in the catch rate data for a subsection of the sampling area: the Gulf of Mexico region. This study used geostatistical techniques to model and predict spatial abundances of two pelagic species with different habitat utilization patterns: dolphinfish (Coryphaena hippurus) and swordfish (Xiphias gladius). We partitioned catch rates into two components, the probability of encounter, and the abundance, given a positive encounter. We obtained separate variograms and kriged predictions for each component and combined them to give a single density estimate with corresponding variance. By using this two stage approach we were able to detect patterns of spatial autocorrelation that had distinct differences between the two species, likely due to differences in vertical habitat utilization. The patchy distribution of many living resources necessitates a two-stage variogram modeling and prediction process where the probability of encounter and the positive observations are modeled and predicted separately. Such a "geostatistical delta-lognormal" approach to modeling spatial autocorrelation has distinct advantages in allowing the probability of encounter and the abundance, given an encounter to possess separate patterns of autocorrelation and in modeling of severely non-normally distributed data that is plagued by zeros.

Fuel inventory and generation of carbon and metal dust in a tokamak are perceived to be serious safety and economy issues for the steady-state operation of a fusion reactor, e.g. ITER. These topics have been explored in this thesis in order to contribute to a better understanding and the development of methods for controlling and curtailing fuel accumulation and dust formation in controlled fusion devices. The work was carried out with material facing fusion plasmas in three tokamaks: TEXTOR in Forschungszentrum Jülich (Germany), Tore Supra in the Nuclear Research Center Cadarache (France) and JET in Culham Centre for Fusion Energy (United Kingdom). Following issues were addressed: (a) properties of material migration products, i.e. co-deposited layers and dust particles; (b) impact of fuel removal methods on dust generation and on modification of plasma-facing components; (c) efficiency of fuel and deposit removal techniques; (d) degradation mechanism of diagnostic components - mirrors - and methods of their regeneration. / <p>QC 20121116</p>