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Horio S.,University of Electro - Communications | Horio S.,Japan Research Institute Ltd | Takeuchi K.,University of Electro - Communications | Kawabata T.,University of Electro - Communications
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | Year: 2015

For low-density parity-check codes, spatial coupling was proved to boost the performance of iterative decoding up to the optimal performance. As an application of spatial coupling, in this paper, bit-interleaved coded modulation (BICM) with spatially coupled (SC) interleaving - called SC-BICM - is considered to improve the performance of iterative channel estimation and decoding for block-fading channels. In the iterative receiver, feedback from the soft-in soft-out decoder is utilized to refine the initial channel estimates in linear minimum mean-squared error (LMMSE) channel estimation. Density evolution in the infinite-code-length limit implies that the SC-BICM allows the receiver to attain accurate channel estimates even when the pilot overhead for training is negligibly small. Furthermore, numerical simulations show that the SC-BICM can provide a steeper reduction in bit error rate than conventional BICM, as well as a significant improvement in the so-called waterfall performance for high rate systems. Copyright © 2015 The Institute of Electronics, Information and Communication Engineers.

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.

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.

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.

Yamamoto T.,MItsubishi Electric | Takano T.,MItsubishi Electric | Takuma Y.,MItsubishi Electric | Inoue M.,Japan Research Institute Ltd | Arao G.,Japan Research Institute Ltd
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) | Year: 2010

Dispersed generators such as wind power systems, photovoltaic systems, and cogeneration systems are expected to mitigate the environmental burden of energy consumption, and their installation has been promoted recently. Micro-Grid is focused on as a method to solve some problems in a commercial electric power line when installing a large number of dispersed generators, and some demonstrative research on Micro-Grid for large-scale systems is being carried out now. Also, small cogeneration systems for houses, such as gas engines and fuel cells, are expected to improve CO2 emissions. However, if the power and heat demand of a family are relatively small or are unbalanced, the cogeneration system does not operate effectively. The authors have studied the application of Micro-Grid for home energy supply, and have developed a control system to solve this problem. The system achieves a reduction of CO2 emissions and energy costs by sharing electric power and heat among some houses with cogeneration systems. This paper presents an outline of the newly developed system, and in particular describes the effect of the reduction in CO2 emissions compared with a conventional energy supply method, and the case in which dispersed generators are installed in some houses and operate independently. © 2009 Wiley Periodicals, Inc.

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.

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.

Kashima T.,The Fuel Team | Suyama K.,The Fuel Team | Mochizuki H.,Japan Research Institute Ltd
Energy Procedia | Year: 2015

This paper provides validation results of SWAT4, the revised version of SWAT3.1, by the analysis of PIE data of MOX fuel irradiated in a pressurized water reactor. SWAT4 is a system that combines the point burnup system ORIGEN2 and neutron transport calculation solvers, the continuous energy Monte Carlo code MVP or MCNP5, and the deterministic neutronics calculation code SRAC2006. The calculation results of SWAT4 have generally same trends with the case of UO2 fuel analyses. For major uranium and plutonium isotopes, deviations less than 5% were obtained. This means that SWAT4 has the same accuracy to predict isotopic compositions of irradiated MOX fuel with the case of UO2 fuel. The radial distribution of isotopes in a pellet was also analyzed, whose results were compared with that measured by SIMS. SWAT4 predicted well the isotope and burnup distributions in an irradiated MOX pellet. © 2014 The Authors.

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