Refractory materials must, in their everyday environment, withstand high stress levels which are a result of mechanical and thermal loadings. Any failure which results from these applied stresses can have serious financial and human consequences and therefore should be avoided. One key aspect to understanding the thermal shock behaviour of refractories is the mechanical behaviour at low temperatures. In this thesis the mechanical behaviour of a small range of multiphase refractories is explored. In particular the stress-strain response and its influence on the fracture behaviour is investigated. Experiments, performed on magnesia and magnesia spinel composites, indicate that non-linear stress-strain behaviour accompanied by permanent deformation upon unloading is a result of the release of microscale residual stresses by microcracking. A micromechanical constitutive model combining these features was developed using linear elastic composite theory and isotropic continuum damage mechanics. This non-linear stress-strain behaviour also gives rise to increasing toughness as crack propagation occurs. This increase in toughness results from an expansion which occurs when microscale residual stresses in front of the crack tip are relaxed by microcracking. A micromechanical model has been developed based upon the specifically developed constitutive model and previous work on transformation toughening. These models are capable not only of simulating experimental results, but can also indicate the microstructures which are most likely to exhibit extensive non-linear stress-strain behaviour and strongly rising toughness curves.

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Continuous anionic polymerisation of catalysed E -caprolactam has been undertaken on an intermeshing co-rotating twin-screw extruder for the preparation of polyamide 6. An optimised extruder screw and barrel configuration was used during reactive extrusion process to permit necessary feeding, mixing, devolatilising and pumping requirements. Various screw speeds and barrel temperature profiles were also employed to influence the thermal and shear history of the reaction mixture. Differential scanning calorimetry and wide angle X-ray diffraction techniques were used to characterise the thermal properties and crystalline order of the polymerisation product. It was observed that the extent and form of the crystalline structure can be greatly influenced by the material composition, method of preparation and annealing procedures during and after the polymerisation stage. Molecular weight, molecular weight distribution and residual monomer content of the reactive polymerised PA6 samples as determined by solution viscometry, gel permeation chromatography and gas chromatography analysis revealed that these properties could be influenced by polymerisation conditions in the extruder, yielding values of Mw up to 100 kg.mol-1 and polydispersity index as high as 6 with monomer residue contents of 4-6%. Selected mechanical properties of the PA6 samples as measured using standard test procedures exhibited superior impact and elongational properties under tensile deformation but showed a slightly reduced tensile strength compared to commercial polymer. A reactive polymerised blend of PA6 with 10 wt% EPR copolymer has been successfully synthesised in a similar manner using the twin-screw extruder at a screw speed of 150 rpm. This elastomer modified blend material exhibits superior tensile and impact strength compared to the pure PA6. Enhancement of the mechanical properties is postulated to be attributed to the formation of a PA6-gPE graft copolymer which can possibly functioned as an emulsifying agent to lower the interfacial tension between the two phases thereby compatibilising the blend. Experimental evidence from FTIR and phase solubility studies have supported the formation of this graft copolymer. Characterisation studies by DSC, DMA and W AXD suggested structural modification of the EPR copolymer has occurred as a result of chain scission during the polymerisation/ blending process leading to the formation of a crystalline PP phase and an amorphous PE component. Macroradicals formed from this mechano-degradation reaction by chain scission of the reacting polymers are postulated to be responsible for the formation of this graft copolymer. Blends of reactive polymerised PA6 and a commercial grade isotactic PP homopolymer of compositions 10%, 30%, 50% and 70% PP were also prepared with and without the presence of another commercial grade functionalised PP compatibiliser. Results obtained from structural, morphological and mechanical studies obtained for the non-functionalised blend of 10% PP showed apparent "miscibility" of the phase components which is an unexpected observation since PA6 and PP are well known to be incompatible. It is postulated that a branched PP and a PA6-g-PP graft copolymer has been formed, as a result of mechano-degradation reaction during the extrusion/blending process. Reaction blends with higher PP compositions however, sbowed incompatibility behaviour with coarse blend morphology and poorer mechanical properties. Phase inversion phenomena for this reaction blend is observed at PA6 composition of 30% with evidence of interpenetrating polymer network structure in the blend mophology. The functionalised reaction PA6/PP blends with 5% compatibiliser showed phase separation of the polymer components in all compositions as evidenced from DSC, W AXD, DMA and SEM studies. No improvement of mechanical properties was observed as compared to the blends without compatibiliser. A PA6-g-PP-g-MA graft copolymer has postulated to have formed between the PA6 and the compatibiliser but this compatibisation effect is not efficient enough to enhance the mechanical behaviour of the blends.

I investigate the way in which Australian managers issue their earnings forecasts, and the impact this has on the reaction of equity investors and security analysts. Using a sample of 233 management earnings forecasts issued from 1994 to 2001, I find that managers are more likely to issue earnings forecasts when they have bad earnings news than good earnings news. I find that a vast majority of forecasts are ???framed??? by the use of an accompanying earnings benchmark. Forecasts are issued with varying degrees of specificity (or precision) and also with variation in additional accompanying disclosures. Forecasts issued with negative framing (forecast earnings less than benchmark earnings) are more likely to be accompanied by statements about factors external to the firm in explaining performance, while forecasts issued with positive framing (forecast earnings greater than benchmark earnings) are more likely to be accompanied by additional verifiable forecasts of components of earnings. I find the market reaction to earnings forecasts released with positive framing is higher than for forecasts released with negative framing, after controlling for forecast news and other forecast properties. I also examine security analysts??? forecasts around the release of management earnings forecasts and find that after the release of a management earnings forecast, analyst activity increases, but that analysts??? forecasts become less accurate and more biased. Neither the extent of analyst activity nor changes in analysts??? forecast accuracy or bias is related to forecast framing.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 102-103). Also available via the Internet.

Thesis (Ph. D.)--Columbia University, 1922. / Vita. "Reprinted from the American journal of mathematics, vol. XLIV, no. 1. Jan., 1922." Also issued in print.

Thesis (Ph. D.)--Columbia University, 1922. / Vita. "Reprinted from the American journal of mathematics, vol. XLIV, no. 1. Jan., 1922." eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--Oregon State University, 2004. / Typescript (photocopy). Includes bibliographical references (leaves 77-79). Also available on the World Wide Web.

Thesis (Ph.D.)--Bowling Green State University, 2009. / Document formatted into pages; contains vi, 119 p. Includes bibliographical references.