An investigation of austenite grain growth of two bearing steel grades; 100Cr6 and100CrMnMoSi8-4-6 is performed. Austenitization treatments were performed between 860°C and 1200 °C for 5 minutes to 5 hours and the grain size was determined for each sample.Grain boundary etching was carried out using a water based, picric-acid etchant. Generally,100CrMnMoSi8-4-6 was harder to etch than 100Cr6. Therefore, a precipitation heattreatment was performed in order to facilitate etching of prior austenite grain boundaries in100CrMnMoSi8-4-6. The precipitation treatment was found to be effective. However, theprecipitation heat treatment was not suitable for 100Cr6 as the grain size increased duringthe precipitation heat treatment.Light optical microscope equipped with a camera was utilized to take micrographs for grainsize evaluation. Jeffries' standard procedure according to ASTM E112-96 was used tomeasure the grain size. The results shows that the austenite grain size increases withtemperature and time as expected. The experimental data was fitted to a well-known graingrowth model. The model only worked for the temperatures investigated and could not bemade to fit different temperatures.Local grain size variation was studied and its influence on fatigue properties was evaluated.The result showed that variation in local grain size can significantly alter the fatigueproperties. The findings are only theoretical and have not been tested practically.Two different spheroidization heat treatments and one homogenization heat treatmentwere performed. Both spheroidization heat treatments investigated exhibited similar grainsize. The homogenization heat treatment reduced the local grain size variation.Homogenization treatment prior to the spheroidization treatments did not increase ordecrease the grain size. The long heating, holding and cooling times in the secondspheroidization heat treatment is probably the reason for the lack of grain refinementcompared to the first spheroidization heat treatment. The grains had time to grow to theinitial austenite grain size during each cycle.

No description available.

The specific surface area, determined by the BET method, is a parameter often used to scale results of mineral studies of surface reactions in terms of rate and capacity to the field scale. Such extrapolations of results from small-scale laboratory experiments to the field-scale are important within many environmental applications. An example of this is for the prediction of radionuclide retention in the bedrock surrounding a deep repository for radioactive waste, following failure of the engineered barriers, where radionuclides may sorb onto minerals constituting the geological environment. As a first step, the approach used in this work is to study the relationship between specific surface area and the particle size (0.075-8 mm) and to approach the field scale via measurements on large, centimetre-sized pieces, for seven natural minerals commonly found in granite: apatite, biotite, chlorite, K-feldspar, hornblende, labradorite and magnetite. The underlying assumption is that sorption of radionuclides can be related to specific surface area of a particular mineral in a continuation of this project.The results show that the phyllosilicates biotite and chlorite have a specific surface area that is about 10 times larger than the other minerals. Over the range of particle size fractions studied, the specific surface area varies between 0.1 and 1.2 m2g-1 for biotite and chlorite. The other studied minerals have specific surface areas varying between 0.01 m2g-1 for the largest fraction and up to 0.06 - 0.12 m2g-1 for the smallest. Results show linear relationships between the specific surface area and the inverse of the particle size for all studied minerals for small particle sizes, as expected. For some minerals, however, the data seemingly can be divided in two linear trends, where a change in internal surface area, surface roughness and/or particle geometry as the particle size decreases may explain this behaviour. Interestingly, for larger particles, there is a deviation from the linearity observed for small particles. Tentatively, this behaviour is attributed to a disturbed zone, created by the mechanical treatment of the material during particle size reduction, extending throughout small particles, but not altering an undisturbed core of the larger particles. In agreement with this, measurements on large pieces show a surface area 5 to 150 times lower than expected from the linear trends observed for the crushed material, implying an overestimation of the surface area and possibly also of the sorption capacities of the rock material from simple extrapolations of experimental results employing finely crushed material to the field situation. / QC 20110929 / Äspö Radionuclide sorption

In this dissertation the effects of different types of Pulverized Fuel Ash (PF A)-types on the workability of cementitious pastes containing relative large amounts of PF A were investigated. The different types of PF A were produced at the same source thus they were chemically similar but differed in terms of average particle size and size distribution (grading). By using a two-point measurement technique based on flow through a J-shaped tube it was possible to detect relative small differences in workability between pastes. It was found and concluded that the different types of PFA had a significant effect on the workability of pastes containing cement and PFA as well as PF A alone. The physical differences between the PF A-types were quantified and their effects on workability investigated. It was concluded that PF A with a broader particle size distribution range produced pastes with higher workability at constant water content. It was found that compressive strength as measured after 28 days were solely a function of the water/cementitious ratio for the curing regime employed. It was concluded that for curing conditions used the type of PF A used could have a significant effect on compressive strength when constant workability is required. / Dissertation (MSc (Transportation))--University of Pretoria, 2006. / Civil Engineering / unrestricted

This research investigated whether earnings management of listed companies, have increased or decreased since the implementation of King II in 2003. This study assessed the extent of earnings management for certain sectors and for large and mid cap companies. The discretionary component of total accruals was used as proxy for earnings management – calculated by using the Modified Jones Model. The top-100 JSE-listed firms by market capitalisation were assessed, excluding the Financial, Mining and Resource Sectors. It was found that discretionary accruals has increased since 1996 and peaked in 2005 (see graph Figure 13). It was concluded with 89% certainty that discretionary accruals during “2003-2009” were higher than during “1996-2002”. Hence, the research suggests that accrual based earnings management is likely to have increased since 2003. However, the results were not statistically significant. Also, the cause of this increase could be due to many factors (not necessarily due to King II). Discretionary accruals were found to be higher for mid cap companies and for the retail sector. However, the analysis was not statistically significant. Discretionary accruals have fluctuated significantly over time and amongst companies. In order to identify which companies and sectors manage earnings the most, a more detailed micro-level investigation, using multiple detection models, is required. Copyright / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

Since phages use the host resources to replicate themselves after infection, the different sizes of the phage genome should influence the replication rate. We, therefore, hypothesized that the smaller genomes should burst the cell faster than the larger ones. As well, the shorter genomes would have greater burst sizes because they should replicate faster. Here, we obtained 16 phages of various genome length. All phages were isolated on Streptomyces griseus and available in our phage bank at the University of North Texas. We performed one-step growth studies for the 16 phages, as well as determined the host doubling time from its growth curve. The results show that S. griseus grown in nutrient broth has a doubling time of 5 hours and 22 minutes. This doubling time is used as a guideline for the phage growth studies. Because the filamentous nature of the host caused several difficulties during the experiment, we isolated single cells by sonication and centrifugation. After the cell number was determined by viable cell count, the cells were infected with each type of phage using a multiplicity of infection (MOI) of 0.5. The results show that phages' burst times range between 45 (±0, standard error) and 420 (±30) minutes and burst sizes from 12 (±0) to 1500 (±60) The statistical analyses show that there is no correlation between either genome size and burst time (R= -0.01800, P=0.97894) or genome size and burst size (R= -0.32678, P=0.21670). We further performed the comparative genomics studies to investigate whether the phages with similar burst times and burst sizes show similar genome structures. The studies show that Eddasa and Lorelei have similar burst times of 45 to 60 minutes and share 52 homologs. For burst size, only Tribute and Blueeyedbeauty that have similar burst sizes of 21-30, and they are genetically related because of the 48 shared homologs. Although this study did not find any correlation between genome size and burst time/burst size, it provides a foundation for further studies to determine what regulates these two traits.

Clothes are not only for body protection and covering, but they also have social and emotional aspects attached to them. For them to be appealing, they need to have a proper fit while remaining fashionable and aesthetically pleasing to the eye (Anderson, Brannon, Ulrich, Presley&Woronka, Grasso&Gray,2000; Yoo, 2003). Swaziland has a large population of plus-size women who are working in different departments and need to dress for the job on a daily basis. Their apparel sizing and fit preferences and problems are not known. This research investigates apparel sizing and fit preferences and problems of the plus-size Swazi working women. It concentrates specifically on the functional, aesthetic and economic fit preferences, as well as on determining size labelling preferences, knowledge and clothing styles preferences and problems. This was a descriptive study using a quantitative approach. Purposive sampling was used. This design was chosen as it focused on studying plus-size working women who were experiencing fit problems with the apparel they bought from local apparel retail shops. A survey using a questionnaire to collect data was done in exploring apparel sizing and fit problems and preferences of plus-size working women of Swaziland. A sample of plus-size Swazi working female teachers (n = 249) between the ages of 25 and 60 years who had indicated that they wore clothes of size 16 to 28+ or size 40 to 52+ participated in the study. A self-administered questionnaire was used to answer set objectives. The results of the study indicated that the plus-size Swazi working women preferred clothes that were functionally comfortable, fitted well and were made in comfortable fabric. They also indicated that they preferred clothes that were well sized, had a fit that was functional, sensually and emotionally pleasing in respect of style, the fabric used and comfort. The study also reflected that plus-size Swazi working women experienced sizing and fit problems in most of the apparel they bought from local retail outlets. A high number of the plus-size women consumers reported experiencing difficulty in finding clothes that were aesthetically pleasing. They could not find clothes that were fashionable in their size nor clothes that could satisfy their emotional and symbolic egos. A high number of respondents also indicated that they experienced a lot of fit problems on several areas of their bodies. The waist, hips, buttocks, abdomen and upper arms seemed to be the most problematic body areas respondents reported to be having fit problems. The lengths were also a challenge as most had problems with sleeve and pants length. Findings in this study also reflected that sizing in clothes was still a major problem for most of the plus-size consumers. Many of the respondents had problems understanding information on the size tags. The sizing systems were most probably confusing for the consumer as some came in varying numbers and letters. This study may contribute to a better understanding of sizing and fit preferences and problems experienced by the plussize Swazi working women with regard to work apparel. Consumers come in different shapes and sizes. The clothing producer has a task of ensuring that clothes are made to fit most of the prevailing figure types, rather than the common ideal figure. / Dissertation (MConsumer Science)--University of Pretoria, 2010. / Consumer Science / unrestricted

A second nearly complete skeleton of the fossil ailurid Pristinailurus bristoli was recently recovered from the Hemphillian (late Miocene) Gray Fossil Site of northeast Tennessee. It appears to be significantly larger than the previously known skeleton of P. bristoli, which was surprising as the living red panda Ailurus fulgens is thought to be generally monomorphic, including between sexes. Here the presence of significant size difference in the geometric means of cranial and postcranial measurements and canine area in the two specimens of P. bristoli is tested relative to the distribution of size differences in intersex and intrasex pairs of A. fulgens. The presence of sexual dimorphism in these dimensions is also assessed in A. fulgens using t-tests. We report the first evidence of sexual dimorphism in both upper and lower canine area in A. fulgens. We also found evidence of significantly greater body size difference in the two specimens of P. bristoli than that present in A. fulgens. This could reflect a variety of causes, including the presence of multiple species or subspecies, a greater range of ecologically driven variability, or the presence of sexual dimorphism. We argue tentatively for sexual dimorphism as the most plausible explanation for the apparent size range of P. bristoli.

Thesis: M.S., Massachusetts Institute of Technology, Department of Political Science, 1977 / Bibliography : leaves 239-252. / M.S. / M.S. Massachusetts Institute of Technology, Department of Political Science

The mean absolute deviation is a simple and informative measure of variability. Approximate confidence intervals for mean absolute deviations in one-group and two-group designs are derived and are shown to have excellent small-sample properties under moderate nonnormality. Sample size planning formulas are derived.