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Maeda R.,Ritsumeikan University | Maeda R.,Japan Research Institute Ltd | Ohta N.,Ritsumeikan University | Kuwabara K.,Ritsumeikan University
Studies in Computational Intelligence | Year: 2014

As information and communication technologies advance, large amounts of data are created everyday. The demands for processing such big data are also increasing. To meet them, the MapReduce framework has been proposed and is now widely used. On the other hand, a rule-based system is used to implement such an intelligent system as an expert system. For applying a rule-based system to process large amounts of data, we propose a method that implements a rule system based on the MapReduce framework. We constructed a simple rule system using Hadoop, which is an open source implementation of the MapReduce framework, and compared several methods of executing a rule system. Our experimental results indicate the potential of a rule system implemented using the MapReduce framework. © Springer International Publishing Switzerland 2014. Source


Kugai J.,Osaka University | Kugai J.,Japan Research Institute Ltd | Kitagawa R.,Osaka University | Seino S.,Osaka University | And 6 more authors.
Applied Catalysis A: General | Year: 2011

Pt-Cu bimetallic nanoparticles immobilized on γ-Fe2O 3 support were synthesized by a unique radiolytic process and their physical properties and catalytic activity for CO preferential oxidation were investigated for various Pt/Cu atomic ratios. The chemical composition of the catalysts measured by inductively coupled plasma revealed most of the platinum and copper aqueous precursors were deposited on to the γ-Fe 2O3 support after irradiation with electron beam. Crystallographic analysis of the catalysts by X-ray diffraction showed Pt-Cu alloy is formed for wide range of Pt/Cu ratio. From the lattice parameter of this Pt-Cu alloy, it was found that Cu can be incorporated into Pt lattice up to 30 at% with the present irradiation condition. The rest of Cu for high-Cu (low-Pt) samples was identified as divalent oxide with poor crystallinity by XANES spectrum. Detailed STEM-EDX analyses further confirmed that Pt-Cu alloy exists as nanoparticles with a few nanometers in diameter and CuO with low crystallinity distributes on entire surface of the γ-Fe2O 3 support. The PROX activity showed different trends between high-Pt and high-Cu samples. The CO conversion decreased as the Pt loading was decreased to 50 at%, and it monotonically decreased with increasing temperature. However, as the Pt loading was further decreased, the activity increased with temperature by contraries, and reached the maximum conversion at 100 °C. Regardless of the low Pt loading, the sample with 10 at% Pt and 90 at% Cu exhibited the highest activity at 100 °C, which is preferable for low temperature fuel cell applications. This enhanced activity was attributed to oxygen supply via the copper of low crystallinity from the O2-poor atmosphere to Pt-Cu alloy particles that chemisorbs CO molecules. © 2011 Elsevier B.V. Source


Osada S.,Okayama University | Osada S.,Japan Research Institute Ltd | Kajita K.,Okayama University | Fukushima Y.,Okayama University | Yokohira T.,Okayama University
2013 19th Asia-Pacific Conference on Communications, APCC 2013 | Year: 2013

In distributed file systems, a well-known congestion collapse called TCP Incast occurs because many servers send data to the same client and then many packets overflow the port buffer of the client link. Incast leads to throughput degradation in the network. In this paper, we propose two methods to avoid Incast based on the fact that only one connection can almost fully use the network bandwidth because the bandwidth-delay product is not so large in current data center networks. The first method is a method which completely serializes connection establishments. By the serialization, the number of packets in the port buffer becomes very small, which leads to Incast avoidance. The second method is a method which overlaps the slow start period of the next connection to the current established connection to improve throughput in the first method. Numerical results from extensive simulation runs show the effectiveness of our two proposed methods. © 2013 IEEE. Source


Kajita K.,Okayama University | Osada S.,Okayama University | Osada S.,Japan Research Institute Ltd | Fukushima Y.,Okayama University | Yokohira T.,Okayama University
International Conference on ICT Convergence | Year: 2013

In distributed file systems, a well-known congestion collapse called TCP Incast occurs because many servers send data to the same client and then many packets overflow the port buffer of the client link. Incast leads to throughput degradation in the network. In our previous work, we have proposed a method to avoid Incast. In the method, we limit the maximum number of simultaneously existing connections to a predetermined constant value. However, we cannot use the method when the data size is small, and because we have not investigated how to optimize the maximum value, Incast may occur if the maximum value is not appropriate. In this paper, we improve the method so that it is applicable regardless of the data size and the maximum value is optimized. Numerical results show the effectiveness of our proposed method. © 2013 IEEE. Source


Tsukitani T.,Osaka University | Takashima K.,Osaka University | Itoh Y.,Osaka University | Asahi M.,Japan Research Institute Ltd | And 2 more authors.
Computer Software | Year: 2011

We proposed the Birdlime Icon to facilitate pointing tasks by dynamically stretching its shape as it catches the overshooting cursor on GUI. Unlike existing techniques, this technique can reduce pointing time even in such realistic situation as there are many objects on a display. We conducted three experiments to examine the Birdlime Icon's performance. The comparison technique are Expansion which expands target size when the cursor approaches it and Sticky icons which reduces cursor velocity while the cursor is on the target. The first experiment was conducted in a single target situation, the second was conducted with multiple targets selection task, and the third was in the situation that the cursor must go through some distracters to reach the target. The experiment results show that the Birdlime Icon is the practical technique that can always maintain positive performance even in multiple target situations while the compared techniques drop their performance in some conditions. Source

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