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Metagenomics, the study of all microbial species cohabitants in an environment, often produces large amount of sequence data varying from several GBs to a few TBs. Analyzing metagenomics data includes both data-intensive and compute-intensive steps, making the entire process hard to scale. Here we aim to optimize a metagenomics application that partitions the shortgun metagenomics sequences based on their species of origin. Our solution combines MapReduce-based BioPig analytic toolkit with MPI to provide scalability in respective to both data and compute. We also made some improvements to the existing BioPig toolkit by using simplified data types and compressed k-mer storage. These optimizations leads up to 193× speedup for the computing-intensive step and 9.6× speedup over the entire pipeline. Our optimized application is also capable of processing datasets that are 16 times larger on the same hardware platform. These results suggest integrating heterogeneous technologies such as Hadoop and MPI is quite efficient to solve large genomics problems that are both data-intensive and compute-intensive.

The chief function of sub-nozzle of impact sprinkler is to increase the near precipitation depth, thereby improving the uniformity of sprinkler irrigation. In this study, flow field simulation combined with experimental validation method was applied to optimize the key structural parameters (elevation angle and position) of impact sprinkler. Nine kinds of elevation angles and positions of sub-nozzle combinations were designed with the established three-dimensional structures of the impact sprinkler by Pro/E software. The three-dimensional inner flow channel model of impact sprinkler with nine kinds of sub-nozzle structure was established. The inner flow channel simulations of all kinds of impact sprinkler were performed by FLUENT of Computational Fluid Dynamics (CFD) software. Considering structural feature, the precision requirement, the procession quality, and the cost of product, the SLA RPT (Stereo lithography Apparatus Rapid Prototyping Technology) was selected to prototype the impact sprinkler with nine kinds of sub-nozzle. The nine kinds of models were processed into samples for experimental verification. Under the rectangular combinations, four interpolation methods (distance interpolation method, linear interpolation method, cubic interpolation method and cubic spline interpolation method) were used to calculate the Christiansen uniformity coefficient and nine kinds of water pressure distribution models were established by Sprinkler 3D software in two-dimensional interpolation method. The result showed that the impact sprinklers with sixth sub-nozzle (position parameter of 19.8 mm, the elevation angle parameter of 18°) performed more reliable. The study about sub-nozzle of impact sprinkler's structural parameters improved the nozzle near water distribution effectively. Its flow rate of simulation was biggest. The yield of water distribution in 2-12 m could maintain good uniformity. And the sprinkler range of the sixth sub-nozzle was more than 14 m, better than before and increased by more than 2 m. The sprinkler irrigation uniformity was calculated with the four different interpolation methods and results were increased obviously. Under the pressure of 250 and 300 kPa (especially the pressure of 300 kPa), the Christiansen uniformity coefficient both was more than 80%, which was an increase of 4% and 5% above than before. With the increase of the pressure, Christiansen uniformity coefficient was still consistent generally. The structural parameters of sub-nozzle (position parameter of 19.8 mm and the elevation angle parameter of 18°) of impact sprinklers were more reasonable. This study provides valuable information for structural design of sub-nozzle, impact sprinkler and sprinkler system optimization. [ABSTRACT FROM AUTHOR]