Creep of HfB2-based UHTCs up to 2000oC

Ultra-high temperature ceramics (UHTCs) are promising candidates for hypersonic applications as a consequence of their high melting points, in excess of 3000 ºC for ZrB2 and HfB2 UHTCs. The UHTCs community has traditionally focused on development of more oxidation-resistant UHTC composites as a consequence of poor oxidation resistance of monolithic UHTCs, which has led to the choice of SiC-reinforced MeB2 (where Me is Zr or Hf) as the baseline material for extreme environments. An overview of current understanding of high temperature creep of MeB2–based UHTCs will be described, discussing the following points: • Poor creep resistance of SiC-reinforced HfB2 and their structural instabilities. • Plastic behavior of HfB2 which deforms like an hcp-metal. • Plastic behavior of HfB2/2 wt.% La2O3 or how to maintain the creep resistance while improving the oxidation resistance. • New approaches to increase the creep resistance of HfB

Automatic Analytical Modeling for the Estimation of Cache Misses

Caches play a very important role in the performance of modern computer systems due to the gap between the memory and the processor speed. Among the methods for studying their behavior, the most widely used by now has been trace-driven simulation. Nevertheless, analytical modeling gives more information and requires smaller computation times that allow it to be used in the compilation step to drive automatic optimizations on the code. The traditional drawback of analytical modeling has been its limited precision and the lack of techniques to apply it systematically without user intervention. In this work we present a methodology to build analytical models for codes with regular access patterns. These models can be applied to caches with an arbitrary size, line size and associativity. Their validation through simulations using typical scientific code fragments has proved a good degree of accuracy. 1 Introduction Nowadays the performance gap between processors and main memory makes an ..