Application of Active Contours on Metallurgical Microstructures

Employing computer algorithms for finding and outlining the boundaries between phases or grain boundaries (referred to as edge detection) is a widely used technique employed as an intermediate step in microstructure analysis. Having an outlined region of interest enables the user to extract data about the region or use it in the reconstruction of three-dimensional models. Because traditional edge detection relies on a user-selected threshold value, the results often are subjective. Furthermore, traditional edge detection frequently results in outlines that are incomplete, requiring additional processing steps, such as edge linking and spur removal. Active contouring is an edge-detection-based technique that typically yields results superior to that of a traditional edge detector. High noise tolerance and built-in flexibilities of active contours make the technique desirable to use across a broad range of applications. Although initially used for meteorological applications, several uses of active contours are presented for metallurgical microstructural data obtained using optical and electron microscopies to demonstrate robustness and the range of applications that can employ active contours.     

Comparison of Fatigue Strengths of Bulk Metallic Glasses Produced by Tilt Casting and High-Pressure Casting

High fatigue strength is one of the important factors that facilitates the industrial usage of bulk metallic glasses (BMGs). Fatigue data were analyzed using the Weibull probability models for BMGs produced with different casting processes in order to study the reliability of fatigue strengths of cast glassy alloys. The fatigue data of tilt-cast and high-pressure-cast BMGs can be explained by a three-parameter Weibull cumulative distribution function (cdf) and a mixture model of two-parameter Weibull cdfs, respectively. We conclude that the cast defects, which reduce fatigue strength, should be eliminated in order to realize a high reliability of fatigue strengths.     

Comparison of Biological and Chemical Predictors of Dermal Carcinogenicity of Petroleum Oils

Various methods have been proposed as a basis for cancer hazard labelling of petroleum products. The Institute of Petroleum analytical method termed IP 346/80 was recently recommended to the European Union as the preferred method for this purpose. In this report we compare IP 346/80 with several other predictors of dermal carcinogenicity, including the Mobil PAC Method, the Modified Ames Test (ASTM Method E 1687-95), and the ^32P-postlabelling assay for DNA adducts. Oils for assay were selected from a repository of samples previously subjected to mouse skin-painting bioassay. 120 oils were tested in the Modified Ames Assay, 57 by the Mobil PAC Method, 50 by Method IP 346/80, and 48 by the postlabelling procedure. The ability of each assay to distinguish between carcinogenic and noncarcinogenic oils was examined at various suggested discriminators, e.g. Mutagenicity Indices (MI) of 1.0 and 2.0, 3-7 ring PAC contents of 1% and 2% (w/w), and IP 346/80 DMSO-extractables of 2% and 3% (w/w). Various adduct levels were tested for maximum discrimination between carcinogenic and noncarcinogenic oils. The accuracy of each method is reported.     

The Use of Lewis Acids During Rapid Steam Hydrolysis

Mixed hardwood chips were treated with various concentrations of aluminum chloride hexahydrate, aluminum sulfate hydrate, and ferric chloride and were subjected to rapid steam hydrolysis pretreatment (RASH). The three levels included 0.01, 0.03, and 0.05 moles of catalyst per 1000 grams of wood. Rapid steam hydrolysis (RASH) was done from 180° to 260°C at 20°C intervals for one minute. The Lewis acid catalyst affected the overall recovery yield of solids, the recovery values of the individual components, the enzymatic rates, and the methanol and water solubility. Overall recovery of pretreated solids generally decreased with the increase in levels of the catalyst. The one exception was AlCl₃ ·6H₂O where the minimum recovery levels were reached at 0.03 moles per 1000 grams of wood and increased at the higher level of catalyst. Cellulose degradation occurred in the temperature range of 250° to 260°C for the control and at the two lower concentrations of the catalyst. At the higher levels of catalyst, appreciable amounts of cellulose degradation occurred at lower temperatures. Hemicellulose solubilization and degradation were extremely sensitive to the RASH temperature and to the levels of catalyst. Almost all hemicellulose was lost at high temperatures or at high levels of catalyst. Losses of lignin appeared to be affected mainly by the RASH temperature and not by the changes in the levels of catalyst.

In contrast, both the temperature and the level of catalyst strongly affected the rates of enzymatic hydrolysis. Generally, the intermediate level of catalyst seemed to give the highest rates of enzymatic hydrolysis at the lowest temperature. Methanol and water solubles increased in the presence of the catalyst and reached a maximum at levels of 0.03 moles between 230° to 250°C.     

Perceptions of Antarctic tourism: A question of tolerance

Perceptions of tourism held by a sample of New Zealand's Antarctic community are explored, and the small, mixed group of scientists and support workers that populate Scott Base (New Zealand's research base in the Ross Dependency, Antarctica) are treated as proxy for a ‘host’ community. This exploration is part of a wider study that set out to investigate the nature and meanings of Antarctic heritage. Although the research did not explicitly set out to survey perceptions of tourism, approximately one-half of those interviewed in the wider study gave an insight into this topic. The qualitative data reported were gathered during two visits to Scott Base in 1999. From the responses a three-fold classification was derived, indicating degrees of tolerance toward tourism: cautious, complex and comfortable tolerance.     

The Future of Economic Inequality and the Planning of Urban Services

This paper rejects the Utopian assumption that characterizes the American future as one of universal affluence. It is suggested that material abundance and leisure creates new forms of scarcity. Assuming therefore, that urban economic inequality will be both persistent and considerable, the author explores possible choices for future action, using a four sector model of economic distribution and a threefold urban system model. Caution in his analysis leads him to conclude that certain aspects of policy are really life-style analysis. Inequality analysis remains an unmet political priority.