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Publisher's copyright statement:Preprint of an article published in Parallel Processing Letters, 24, 3, 2014, 1441006, 10.1142/S0129626414410060 c World Scientic Publishing Company http://www.worldscientic.com/worldscinet/ppl Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Communicated by Guest Editors ABSTRACT Spacetrees are a popular formalism to describe dynamically adaptive Cartesian grids. Even though they directly yield a mesh, it is often computationally reasonable to embed regular Cartesian blocks into their leaves. This promotes stencils working on homogeneous data chunks. The choice of a proper block size is sensitive. While large block sizes foster loop parallelism and vectorisation, they restrict the adaptivity's granularity and hence increase the memory footprint and lower the numerical accuracy per byte. In the present paper, we therefore use a multiscale spacetree-block coupling admitting blocks on all spacetree nodes. We propose to find sets of blocks on the finest scale throughout the simulation and to replace them by fused big blocks. Such a replacement strategy can pick up hardware characteristics, i.e. which block size yields the highest throughput, while the dynamic adaptivity of the fine grid mesh is not constrained-applications can work with fine granular blocks. We study the fusion with a state-of-the-art shallow water solver at hands of an Intel Sandy Bridge and a Xeon Phi processor where we anticipate their reaction to selected block optimisation and vectorisation.

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The mechanical properties of single-quasicrystals of decagonal AlCoCuSi have been studied for the first time by applying the Vickers indentation method. The hardness has been determined as H ~ 9.6 MPa. Estimates for the modulus of elasticity and the fracture toughness are given. The quasicrystals are highly strained internally. Scratching experiments show slight anisotropies in the abrasive friction coefficient. The dominant abrasive mechanism is microplowing.

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The solidification behavior of Al62Cu20Co15Si3 and Al61Cu19.5Co14.5Si5 alloys was studied by means of optical metallography, scanning and transmission electron microscopy, energy-dispersive x-ray analysis, powder x-ray diffraction, and differential thermal analysis. Slowly as well as rapidly cooled ingots of both alloys contained a decagonal quasicrystalline phase as the dominant phase with, additionally, several minor crystalline phases. The structure of the rapidly solidified Si-containing alloys was similar to that of the ternary Al65Cu20Co15 alloy. In the slowly solidified alloys the substitution of 3 at. % Al by Si did not change the basic phase constitution. Si was only partially incorporated in the decagonal phase and a significant quantity of Si was found in elemental form. The increase of Si concentration to 5 at. % resulted in the appearance of new minor phases.

The transformation behavior of high-Co decagonal Al-Co-Ni is studied. Starting from stability considerations based on a number of annealing treatments we check theoretical predictions of the stabilization mechanism and transformation mechanism by phason strain analysis and tiling analysis. The quasicrystal transforms in the first stages into nanodomain structures and finally decomposes into a quasicrystal and a normal crystalline phase. Before decomposition, the material is locked in a disordered state exceeding the periodic order allowed for a one-dimensional quasicrystal. This is interpreted as the maximum periodic order achievable without diffusion. From considering different reasons for phason strain we conclude that disorder in tilings related to phase transformations can wrongly be associated with that suggested by the random tiling hypothesis.