Massively Parallel Computing: A Sandia Perspective

The computing power available to scientists and engineers has increased dramatically in the past decade, due in part to progress in making massively parallel computing practical and available. The expectation for these machines has been great. The reality is that progress has been slower than expected. Nevertheless, massively parallel computing is beginning to realize its potential for enabling significant break-throughs in science and engineering. This paper provides a perspective on the state of the field, colored by the authors' experiences using large scale parallel machines at Sandia National Laboratories. We address trends in hardware, system software and algorithms, and we also offer our view of the forces shaping the parallel computing industry

Hardening Effects of Precipitates with Different Shapes on the Twinning in Magnesium Alloys

Molecular dynamics (MD) simulations were performed to quantify the effect of the precipitate shape on the interactions with extension twin boundaries in magnesium alloys. Three precipitate shapes, including plate-, cube- and rod-like, were studied. The simulation results indicate that the blocking effect of plate-like precipitate is weakly affected by the precipitate aspect ratio (plate width/plate thickness; so, cube-like precipitate is at aspect ratio of 1), while the rod-like precipitate has a hardening effect decreasing with the increasing aspect ratio (rod length/rod width). This suggests that the plate-like precipitate has an identical hardening effect as the cube-like precipitate and a higher effect than the rod-like precipitate. © 2019, The Minerals, Metals Materials Society

Marking out the pitch: a historiography and taxonomy of football fiction

Football, or soccer as it is more commonly referred to in Australia and the US, is arguably the world’s most popular sport. It generates a proportionate volume of related writing. Within this landscape, works of novel-length fiction are seemingly rare. This paper establishes and maps a substantial body of football fiction works, explores elements and qualities exhibited individually and collectively. In bringing together current, limited surveys of the field, it presents the first rigorous definition of football fiction and captures the first historiography of the corpus. Drawing on distant reading methods developed in conjunction with closer textual analyses, the historiography and subsequent taxonomy represent the first articulation of relationships across the body of work, identify growth areas and establish a number of movements and trends. In advancing the understanding of football fiction as a collective body, the paper lays foundations for further research and consideration of the works in generic terms

A mechanistic Individual-based Model of microbial communities

Accurate predictive modelling of the growth of microbial communities requires the credible representation of the interactions of biological, chemical and mechanical processes. How-ever, although biological and chemical processes are represented in a number of Individual-based Models (IbMs) the interaction of growth and mechanics is limited. Conversely, there are mechanically sophisticated IbMs with only elementary biology and chemistry. This study focuses on addressing these limitations by developing a flexible IbM that can robustly com-bine the biological, chemical and physical processes that dictate the emergent properties of a wide range of bacterial communities. This IbM is developed by creating a microbiological adaptation of the open source Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). This innovation should provide the basis for " bottom up " prediction of the emer-gent behaviour of entire microbial systems. In the model presented here, bacterial growth, division, decay, mechanical contact among bacterial cells, and adhesion between the bacte-ria and extracellular polymeric substances are incorporated. In addition, fluid-bacteria inter-action is implemented to simulate biofilm deformation and erosion. The model predicts that the surface morphology of biofilms becomes smoother with increased nutrient concentra-tion, which agrees well with previous literature. In addition, the results show that increased shear rate results in smoother and more compact biofilms. The model can also predict shear rate dependent biofilm deformation, erosion, streamer formation and breakup