Necking and failure at low strains in a coarse-grained wrought Mg alloy

Tensile testing of rolled AZ31 alloy with a mean grain size of 80 μm reveals localization and failure prior to diffuse necking. Optical microscopy reveals that failure is caused by voids that have formed within twins. A simple localization criterion is proposed that captures the role of grain size in the effect. Such early failure is only predicted for coarse grain sizes, in line with observation.

Association of reduced riparian vegetation cover in agricultural landscapes with coarse detritus dynamics in lowland streams

Studies were conducted on streams flowing through agricultural floodplains in south-eastern Australia to quantify whether reductions in riparian canopy cover were associated with alterations to the input and benthic standing stocks of coarse allochthonous detritus. Comparisons were made among three farmland reaches and three reaches within reserves with intact cover of remnant overstorey trees. Detritus inputs to these reaches were measured monthly over 2 years using litter traps. Direct inputs to streams within the reserves were relatively high (550–617 g ash free dry weight (AFDW) m^–2 year^–1), but were lower at farmland reaches with the lowest canopy covers (83–117 gAFDW m^–2 year^–1). Only a minor fraction of the total allochthonous input (<10%) entered any of the study reaches laterally. The mean amounts of benthic detritus were lowest in the most open farmland reaches. Standing stocks of benthic detritus were found to be highly patchy across a large number of agricultural streams, but were consistently very low where the streamside canopy cover was below ~35%. Canopy cover should be restored along cleared agricultural streams because allochthonous detritus is a major source of food and habitat for aquatic ecosystems. Given the absence of pristine lowland streams in south-eastern Australia, those reaches with the most intact remnant overstorey canopies should be used to guide restoration.

A coarse-grained parallel genetic algorithm employing cluster analysis for multi-modal numerical optimisation

This paper describes a technique for improving the performance of parallel genetic algorithms on multi-modal numerical optimisation problems. It employs a cluster analysis algorithm to identify regions of the search space in which more than one sub-population is sampling. Overlapping clusters are merged in one sub-population whilst a simple derating function is applied to samples in all other sub-populations to discourage them from further sampling in that region. This approach leads to a better distribution of the search effort across multiple subpopulations and helps to prevent premature convergence. On the test problems used, significant performance improvements over the traditional island model implementation are realised.

Acceleration of the super bainite transformation through a coarse austenite grain size

The effect of austenite grain size on the kinetics of the isothermal bainitic transformation in a high-carbon super-bainitic steel was investigated. Experimental results showed that the transformation of super bainite was accelerated by a coarse austenite grain size. This is because while coarse austenite grains provide less nucleation sites, it is beneficial for bainite sheaf growth. Meanwhile, there is a critical austenite grain size below which there is a distinct grain size effect and above which it is not evident. © 2014 Elsevier B.V.

Debris

Debris captures a moment of collision between the natural and built environment. Digital simulations conjure a strange version of gravity within the frame. This technique creates a surreal unease, breaking our expectations of figure and ground in traditional landscape photography. This unease mirrors the new landscape of natural disaster zones; where sea has blended with land and the built environment has been forced back into chaos.

Testing the transferability of a coarse-grained model to intrinsically disordered proteins

The intermediate-resolution coarse-grained protein model PLUM [T. Bereau and M. Deserno, J. Chem. Phys., 2009, 130, 235106] is used to simulate small systems of intrinsically disordered proteins involved in biomineralisation. With minor adjustments to reduce bias toward stable secondary structure, the model generates conformational ensembles conforming to structural predictions from atomistic simulation. Without additional structural information as input, the model distinguishes regions of the chain by predicted degree of disorder, manifestation of structure, and involvement in chain dimerisation. The model is also able to distinguish dimerisation behaviour between one intrinsically disordered peptide and a closely related mutant. We contrast this against the poor ability of PLUM to model the S1 quartz-binding peptide.