Yusuke Tanimura

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As the Earth’s ecosystem is a spatially and temporally complex system by nature, it is not sufficient to observe such events and phenomena locally; problems must be solved on a global scale. Therefore, the accumulation of knowledge about the earth in various forms and a scientifically correct understanding of the earth are necessary. The authors have been(More)
In order to effectively handle the growing amount of available RDF data, a scalable and flexible RDF data processing framework is needed. We previously proposed a Hadoop-based framework, which takes advantages of scalable and fault-tolerant distributed processing technologies, originally proposed as Google's distributed file system and MapReduce parallel(More)
This practices and experience paper describes the coordination, design, implementation, availability, and performance of the Pacific Rim Applications and Grid Middleware Assembly (PRAGMA) grid testbed. Applications in high-energy physics, genome annotation, quantum computational chemistry, wildfire simulation, and protein sequence alignment have driven the(More)
A task parallel application is implemented with Ninf-G, a GridRPC system. A series of experiments are conducted on the Grid testbed in Asia Pacific for three months. Through tens of long executions, typical fault patterns were collected, and instability of the network throughput was determined to be a major reason of the faults. Several important points are(More)
M. Riedel∗,†, E. Laure, Th. Soddemann, L. Field, J. P. Navarro, J. Casey,M. Litmaath, J. Ph. Baud, B. Koblitz, C. Catlett, D. Skow,C. Zheng, P. M. Papadopoulos,M. Katz, N. Sharma, O. Smirnova, B. Kónya, P. Arzberger, F. Würthwein, A. S. Rana, T. Martin,M. Wan,V. Welch, T. Rimovsky, S. Newhouse, A. Vanni, Y. Tanaka, Y. Tanimura, T. Ikegami, D. Abramson, C.(More)
Performance assurance has become an important aspect in grid and cloud computing which provide services over the Internet, and Service Level Agreements (SLA) are frequently contracted between users and the service providers. However, the I/O performance of the storage or data access service is still provided on a best effort basis. Some distributed storage(More)
MapReduce has become a popular method for data processing, in particular for large scale datasets, due to its accessibility as a scalable yet convenient programming paradigm. Data processing tasks often involve joins, and the repartition and fragment-replicate joins are two widely-used join algorithms utilised within the MapReduce framework. This paper(More)
In this paper, the characteristics of the typical two models of parallel genetic algorithms are compared. Those models are the coarse grained model and the micro grained model. Especially, the parallel efficiency and the total calculation time on PC clusters that are build with commodity hardware are examined. The characteristics are examined through the(More)
A virtual cluster is a promising technology for reducing management costs and improving capacity utilization in datacenters and computer centers. However, recent cluster virtualization systems do not have the maximum scalability and flexibility required, due to limited hardware resources at one site. Therefore, we are now developing an advanced cluster(More)