Abstract-In this paper, we study the problem of constructing full-coverage three dimensional networks with multiple connectivity. We design a set of patterns for full coverage and two representative connectivity requirements, i.e. 14-and 6-connectivity. We prove their optimality under any ratio of the communication range over the sensing range among regular lattice deployment patterns. We also conduct a study on the proposed patterns under practical settings. To our knowledge, our work is the first one that provides deployment patterns with proven optimality that achieve both coverage and connectivity in three dimensional networks.

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Abstract. We describe the design and implementation of climate fast input/output (CFIO), a fast input/output (I/O) library for high-resolution climate models. CFIO provides a simple method for modelers to overlap the I/O phase with the computing phase automatically, so as to shorten the running time of numerical simulations. To minimize the code modifications required for porting, CFIO provides similar interfaces and features to parallel Network Common Data Form (PnetCDF), which is one of the most widely used I/O libraries in climate models. We deployed CFIO in three highresolution climate models, including two ocean models (POP and LICOM) and one sea ice model (CICE). The experimental results show that CFIO improves the performance of climate models significantly versus the original serial I/O approach. When running with CFIO at 0.1 • resolution with about 1000 CPU cores, we managed to reduce the running time by factors of 7.9, 4.6 and 2.0 for POP, CICE, and LI-COM, respectively. We also compared the performance of CFIO against two existing libraries, PnetCDF and parallel I/O (PIO), in different scenarios. For scenarios with both data output and computations, CFIO decreases the I/O overhead compared to PnetCDF and PIO.

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9% Cr martensitic heat resistant steels such as P91 steel have been considered as the primary candidate structural materials for advanced fossil fired power plants and generation IV nuclear power plants. Due to long-term exposures to high temperatures, the high temperature creep resistance and high temperature oxidation resistance of P91 steel should be simultaneously improved. A Cr content of around 9 wt% in martensitic heat resistant steels is required for the optimization in creep properties, and creep resistances of 9Cr heat resistant steels could be further improved by the control of precipitation behaviors 1,2 . It is reported that increasing the Cr content in excess of about 12 wt% is effective in inhibiting the growth of oxide scale for martensitic heat resistant steels 3 . Some researchers even suggest Cr-enriched (Fe,Cr) 2 O 3 protective scale could form on surface layer of the heat resistant steels with Cr content in excess of 17 wt% 4,5 . With increasing Cr content, the oxidation resistance would be improved obviously in heat resistant steels. However, the Cr content in excess of 12 wt% will induce the formation of δ ferrite, which is detrimental to mechanical properties, Therefore, traditional techniques and methods such as improving Cr content hardly resolve the contradictions of the component requirement between creep resistance and oxidation resistance in martensitic heat resistant steels. Grain refinement is an advantageous approach, to increase the oxidation resistance of heat resistant steels in steam without the necessity of increasing the alloy Cr content 6 . Fortunately, if only the microstrcture in the surface layer is refined at the nanometer scale by mean of a surface mechanical attrition treatment (SMAT),which may increase the oxidation resistance of heat resistant steels, the negative effect of the nanocrystalline surface layer on mechanical properties can been neglected 7 .The nanocrystalline structure with a large number of grain boundaries, which can act as fast atomic diffusion channels 8,9 . Compared to diffusions in materials with conventional grain sizes, greatly enhanced atomic diffusivities have been reported in nanocrystalline materials 10,11 . Hence, it is expected that SMAT, which can produce nanocrystalline layer on the surface of steels, can significantly improve oxdiation resistance. In the present work, the high temperature oxidation behavior of nanocrystallined P91 steal is studied, and effect of nano-grain boundary on the formation of oxide scale is illustrated, all of which can