Dynamic fields generated by rapid crack growth

Stresses and strains near a rapidly propagating crack tip are affected by the mass density of the material. This paper starts with a brief summary of analytical results for near-tip dynamic fields as predicted by linear elastic fracture mechanics. Next, exact expressions are derived for dynamic crack-line strains, for mode-III crack propagation in a nonlinear elastic material and in an elastic perfectly-plastic material. These expressions are valid on the crack line from the moving crack tip to the moving boundary with the region of linearly elastic deformation. For steady-state crack growth, a critical strain criterion is used to compute the relation between external load and crack tip speed. The required external load increases with crack-tip speed.     

A new approach to aid urban water management decision making using trade-off sacrifice modelled by fuzzy logic.

An approach to aid decision making for urban water management is presented that is based on the concept of trade-off sacrifice level in pairwise comparisons between criteria, modelled using fuzzy logic. This approach is illustrated by a case study - selection of alternative water supplies for a Sydney household. Four key decision making criteria covering health, economic, environment and technical aspects are selected: annual probability of infection, life cycle energy use, life cycle cost and reliability. The decision making problem is to select between cases with different volume and application of recycled greywater and rainwater in light of the four criteria. Decision maker's preference is expressed by five levels of trade-off sacrifice between pairs of criteria. The decision makers can assign their preferences for sacrifice level by linguistic assessment and the output trade-off weight (TOW). Measures of decision makers' perceived trade-off level are modelled by a rule-based fuzzy logic control system. The final analysis shows the performance for each sacrifice class for each case, to aid overall decision making with stakeholders.     

Error-correcting code for optical-fibre transmission systems

A simple error-correcting code for optical-fibre transmission systems is proposed, and its correcting principle is explained. This code offers the same advantages as the CMI code, which is widely used in optical-fibre transmission systems. Moreover it has the ability to correct a single error in a block. Owing to this ability, the maximum repeater space can be increased.     

Free amino acids by high performance liquid chromatography and peptides by gel electrophoresis in Mahon cheese during ripening

The free amino acids and peptides contents of Mahon cheese during four months of ripening were studied using high performance liquid chromatography and gel electrophoresis, respectively. The total content of free amino acids generally increased throughout the ripening period, except in one batch. Phenylalanine, valine, proline, glutamic acid and isoleucine were the most abundant free amino acids in all the tests throughout the four month period. They accounted for between 67 and 80% of the free amino acids. No difference was found between the pattern of traditionally made and industrially made Mahon cheeses. Electrophoresis of soluble nitrogen showed the main whey proteins as well as other bands corresponding to peptides.     

Interfacial stress singularities in a bimaterial wedge

In this paper methods of computing stress singularity factors for strain-hardening materials are reviewed. The methods are applied to calculation of these factors for a bimaterial wedge comprising two power-law hardening materials of arbitrary external and internal angles.     

Oxidation resistance and relative stability of some inter-4f alloys

Ten samarium-structure alloys have been oxidation tested in air to estimate the thermal oxidation parameter, T _p, and hence the ratio T _p/T_Sm, where T _Sm is the temperature of decomposition of the appropriate structure and the ratio is a measure of the strength and type of bonding. The ratio decreases with (a) increasing distance apart in the 4f series of the components, and (b) increasing average Group number.     

Role of electron traps in the radiation hardness of thermallynitrided silicon dioxide

A number of samples of thermally nitrided SiO₂ with varying concentrations of electron traps were studied in an attempt to correlate the radiation-induced oxide charge with the number of electron traps. Also studied were the detrapping characteristics of irradiated devices. Etch-back experiments were performed to locate the centroid of the trapped charge. The results show that electron trapping does play a role in the improved radiation hardness of nitrided SiO₂, but is not the sole cause of it