分类： 计算机科学 >> 计算机科学技术其他学科 分类： 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间： 2022-08-15
摘要： 随着高性能计算体系结构的发展，软件与硬件都具有了多层的并行结构。当不同纵向层级与横向分组的计算任务被划分到不同节点的不同处理器时，具有非常多的分配对应方式。用户越来越难以获取最佳的计算并行参数与硬件资源使用量。我们研究了一种优化方法，可以帮助用户自动化的确定最佳的应用并行参数与硬件使用量，使其可以高效率地扩展到大规模计算。此外，我们提出了一种将该优化方法与作业调度系统深度融合的方案，并获得了很好的应用效果。
分类： 材料科学 >> 材料科学（综合） 提交时间： 2022-06-20
摘要：
The behavior of nano-voids composed of vacancies (Vs) at grain boundaries (GBs) is fundamental to the design of the radiation tolerance of poly-crystalline metals (PCs) via GB engineering. In this study, based on differential evolution, a framework for determining the stable structure of GB nano-voids is developed. Combining the framework with multiscale simulations, we elucidate the vacancy-accumulation and GB void
formation mechanism under irradiation. A GB-structure dependent picture is revealed. At special coincidence-site-lattice (CSL) GBs of Ʃ5(310) and Ʃ5(210) with a medium V-GB binding energy, the V could be reemitted from the GB and also has driving force to be clustered at the GB, developing particularly stable V-clusters from a linear configuration to a platelet and finally to three-dimensional void that has large strain fields in iron with small bulk modulus and a bulk-void alike structure in the GB with large bulk modulus. A group of vacancies reconstruct their positions during the growth. The ripening is also mediated by the mobility of small V-clusters in addition to free Vs. General high-angle and low-angle GBs trap Vs efficiently, where V-clusters only align one-dimensionally or hardly nucleate. Based on the bonding among the vacancies and their neighboring atoms of a nano-void, we propose a high-accuracy predictive linear energetic model applied to the nano-void both at the iron/molybdenum/tungsten GBs and in the grain interior. The model captures the anisotropic feature of a nano-void and reproduces the oscillated vacancy energy level near a nano-void, showing distinct advantages over conventional continuum model and Wulff construction based energy model. Finally, the collective behavior of multiple GBs plays a role in the GB void formation. The present work offers fundamental mechanistic insights to GB nano-void formation and growth and sets a key step towards GB-void prevention in PCs by reducing the fraction of special CSL-GBs.
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