A code tagging approach to software product line development

Software product line engineering seeks to systematise reuse when developing families of similar software systems so as to minimise development time, cost and defects. To realise variability at the code level, product line methods classically advocate usage of inheritance, components, frameworks, aspects or generative techniques. However, these might require unaffordable paradigm shifts for developers if the software was not thought at the outset as a product line. Furthermore, these techniques can be conflicting with a company’s coding practices or external regulations. These concerns were the motivation for the industry–university collaboration described in this paper in which we developed a minimally intrusive coding technique based on tags. The approach was complemented with traceability from code to feature diagrams which were exploited for automated configuration. It is supported by a toolchain and is now in use in the partner company for the development of flight-grade satellite communication software libraries.     

Effect of precipitate type and morphology on high-temperature creep and internal stress in Al-Li based alloys

The tensile creep of a series of aluminium-lithium-based alloys, two binary alloys containing precipitate, and the 2090 alloy containing and T₁ precipitate, has been studied over a range of stresses at 150°C. In some cases the internal stress developed during creep has been determined using the strain transient dip test. The results have been compared with similar data previously obtained for the 8090 alloy containing and S precipitates. The solid solution alloy and the binary alloy containing shearable particles exhibited normal Class II behaviour, with the development of sub-grains and a stress dependence of the creep rate given by a single stress exponent,n, between 4 and 5 at all applied stresses. The alloys containing particles not easily sheared by dislocations, coarse , S and T₁, exhibited similar stress dependencies of the creep rate at low stresses but exhibited large values ofn, between 18 and 35 at high stresses. The internal stress, _i, in these alloys was found to be approximately constant at high stresses possibly due to partial shearing of the coarse , T₁, and the S on sub-boundaries. The stress dependence of the minimum creep rate, , could be represented at all applied stresses, _a, by , where (_a–_i) is the effective stress driving dislocations during creep, andn is a single stress exponent of between 5 and 6 for all applied stresses. The internal stress, which increases with applied stress, at least at a low applied stress, arises from inhomogeneity of plastic deformation, due to hard sub-boundaries or hard particles which are Orowan looped. These two types of contribution to the internal stress are of similar magnitude in the alloys containing coarse and T₁ but the majority of the internal stress in the 8090 alloy may arise as a result of the hardening of sub-boundaries by the S precipitate.     

Fabrication and microstructure-mechanical property relationships in Ce-TZPs

Ceria-stabilized tetragonal zirconia polycrystals(Ce-TZPs) have been fabricated via conventional sintering of commercially available electrofused and electrorefined CeO₂-doped ZrO₂ powder at 1550°C for various periods from 0.5–30 h. The resultant grain sizes of the sintered materials were in the range 2–15 m. The sintering of such electrorefined powder appears to occur by a liquid state sintering process, evinced in terms of the grain-size dependence on sintering time at 1550°C and by direct TEM observation. The mechanical properties of the sintered materials have been characterized, including single-edge notch bend fracture toughness and three-point bend fracture strength. The grain-size dependence of these properties in the CeO₂-stabilized tetragonal polycrystals is very much different from that in Y₂O₃ stabilized tetragonal zirconia polycrystals (Y-TZPs). The transformation plasticity, which is represented by the yield stress behaviour and the total strain to fracture, plays an important role in the microstructure-property interrelationship in the Ce-TZPs.     

Hafnia and hafnia-toughened ceramics

Hafnia (HfO₂) and hafnium-based materials are traditionally regarded as technologically important materials in the nuclear industry, a consequence of their exceptionally high neutron absorption coefficient. Following the discovery of transformation toughening in the mid 1970s, a considerable research effort has been devoted to zirconia (ZrO₂)-toughened ceramics (ZTCs). They are considered to be potentially useful materials for structural applications at low and intermediate temperatures (T<1000 °C). Their unsuitability for high-temperature structural applications (T>1000 °C) is related to the low temperature of the tetragonal to monoclinic transformation in ZrO₂. On the basis that HfO₂ exhibits a similar crystal structure and in particular that its tetragonal to monoclinic transformation temperature (1700 °C) is approximately 700 °C higher than that for ZrO₂, it has been suggested that high-temperature transformation toughening could be possible in HfO₂-toughened ceramics (HTCs). Although the concepts behind this suggestion are universally appreciated, only a limited success has been made of the fabrication and the microstructural and mechanical property evaluation of these materials. The fracture toughness values obtained so far in HfO₂ toughened ceramics are, in fact, considerably lower than those obtained in their ZrO₂ counterparts. A great deal of further research work is therefore required in order to understand fully and to exploit toughened ceramics in the HfO₂-based and HfO₂-containing systems. This review covers the science and technology of HfO₂ and HfO₂-toughened ceramics in terms of processing, phase transformation, microstructure, and mechanical properties.     

Polyphenol Supplementation Reverses Age-Related Changes in Microglial Signaling Cascades

Microglial activity in the aging neuroimmune system is a central player in aging-related dysfunction. Aging alters microglial function via shifts in protein signaling cascades. These shifts can propagate neurodegenerative pathology. Therapeutics require a multifaceted approach to understand and address the stochastic nature of this process. Polyphenols offer one such means of rectifying age-related decline. Our group used mass spectrometry (MS) analysis to explicate the complex nature of these aging microglial pathways. In our first experiment, we compared primary microglia isolated from young and aged rats and identified 197 significantly differentially expressed proteins between these groups. Then, we performed bioinformatic analysis to explore differences in canonical signaling cascades related to microglial homeostasis and function with age. In a second experiment, we investigated changes to these pathways in aged animals after 30-day dietary supplementation with NT-020, which is a blend of polyphenols. We identified 144 differentially expressed proteins between the NT-020 group and the control diet group via MS analysis. Bioinformatic analysis predicted an NT-020 driven reversal in the upregulation of age-related canonical pathways that control inflammation, cellular metabolism, and proteostasis. Our results highlight salient aspects of microglial aging at the level of protein interactions and demonstrate a potential role of polyphenols as therapeutics for age-associated dysfunction.     

The multivariable model-based control of the non-alumina electrolyte variables in aluminum smelting cells

This paper investigates the application of multivariable model-based control to improve the regulatory control of electrolyte temperature, aluminum fluoride concentration, liquidus temperature, superheat, and electrolyte height. Also examined are therappropriateness of different control structures and the possible inclusion of recently developed sensors for alumina concentration and individual cell duct flowrate, temperature, and heat loss. For the smelter in this study, the maximum improvement possible with a multivariable model-based controller is predicted to be 30–40% reduction in standard deviation in electrolyte temperature, aluminum fluoride concentration, liquidus temperature, and superheat, and around half this for electrolyte height. Three control structures were found to be appropriate; all are different than the existing control structure, which was found to be suboptimal. Linear Quadratic Gaussian controllers were designed for each control structure and their predicted performance compared. Comalco Research.     

Allelopathic polyacetylenes fromCentaurea repens (Russian knapweed)

The allelopathic weed Russian knapweed (Centaurea repens) was found to contain polyacetylenes VIII–XIV in the roots. Dose vs. response of the root length elongation against lettuce, alfalfa, barnyard grass, and red millet showed IX to be active. Closely related isomers were not active. Examination of the soil surrounding the Russian knapweed roots revealed the presence of IX in sufficient concentration to have an appreciable effect on the surrounding plant community.     

Dewatering behaviour of water treatment sludges associated with contaminated site remediation in Antarctica

Sludge reduction and dewatering is an important aspect of water and waste water treatment. This is especially true in the case of Australia's Antarctic contaminated site remediation program, where the reduction in volume of wastes to be returned to Australia can lead to significant transport and handling cost savings. The dewatering characterisation of water treatment sludges from an Antarctic contaminated site was conducted using a theory of suspension dewatering developed by Buscall, Landman and White. This theory uses fundamental material properties of compressibility and permeability to determine the diffusivity of a suspension. Diffusivity is a useful property that can be used to directly compare the dewaterability of various sludges. In this investigation, several water treatment sludges were collected and characterised in the field to determine the impact of temperature and additives on compressibility, permeability and diffusivity. The Antarctic sludges were found to be less compressible and less permeable than materials such as mineral suspensions and alum water treatment sludges. Compressibility was found to decrease with the addition of powdered coagulation aids such as bentonite and chitosan.     

Some Observations on the Effect of Urea on the Dyeing Behaviour of Wool at Low Temperatures

The effect of adding urea to the dyebath on the rate of absorption of reactive and acid dyes by wool, and of acid dyes by other protein bres, has been studied. Possible modesof action of aqueous solutions of urea on wool are discussed. The observed increase in the ite of dyeing in the presence of urea is due to disaggregation of the dye in solution and reduction in dye-protein hydrophobic interactions. The action of urea in promoting fibre swelling is also likely to be a contributory factor.