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Matsuura, Yuto*; Hayano, Akira; Itakura, Kenichi*; Suzuki, Yukinori*
Applied Soft Computing, 84, p.105737_1 - 105737_9, 2019/11
Times Cited Count：2 Percentile：14.82(Computer Science, Artificial Intelligence)LiDAR (laser imaging detection and ranging) has been developed to obtain a high-resolution point cloud data indicating the detailed 3D shapes of an object. To identify discontinuities in a rock mass of a tunnel gallery wall, it is necessary to approximate the rock mass surface with small planes. Normal vectors of the planes are important to identify discontinuities. We developed an algorithm for estimation of planes based on multi-dimensional particle swarm optimization (MD PSO) from point cloud data. Point cloud data were segmented into bounding boxes and grouped into clusters by MD PSO. Planes were estimated using the least squares method for point cloud data in the respective clusters. The newly developed MD PSO algorithm was evaluated using point cloud data obtained from a gallery wall. Evaluation was carried out in comparison with the previous developed variable-box segmentation (VBS) algorithm. The MD PSO-based algorithm showed a 7% higher accuracy than that of the VBS algorithm.
Matsukawa, Shun*; Itakura, Kenichi*; Hayano, Akira; Suzuki, Yukinori*
Journal of MMIJ, 133(11), p.256 - 263, 2017/11
LIDAR detects a rock mass surface configurations as a point cloud. DiAna (Discontinuity Analysis) is a Matlab tool which was developed for geo-structural analysis of rock mass discontinuities. DiAna segments a point cloud into bounding boxes to estimate the surface of a rock mass. However, an expert's skills necessary to determine the appropriate size of the bounding boxes for DiAna. We developed the VBS (Variable-Box Segmentation) algorithm to determine the appropriate box size depending on the location of the point cloud and to estimate the surface of a rock mass. The performance of the VBS algorithms was evaluated by comparison with the DiAna algorithm. The results of comparison showed that the VBS algorithm estimated planes more accurately for the reference planes than the DiAna algorithm. Therefore, the VBS algorithm determines appropriate box sizes automatically depending on the location of the point cloud and estimates the surface appropriately.
Hayano, Akira; Itakura, Kenichi*
Journal of MMIJ, 133(4), p.76 - 86, 2017/04
no abstracts in English
Xu, Z.*; Yamachi, Hiroshi*; Sato, Toshinori; Matsui, Hiroya; Itakura, Kenichi*
Doboku Gakkai Rombunshu, F3 (Doboku Johogaku) (Internet), 71(1), p.43 - 55, 2015/10
In the process of underground space development, enormous information is collected in each developing stage, such as investigation, plan, design and construction. It is important to properly feed back these information to design and construction in order to realize rational design and construction of an underground space. And more, these information also become basic data in a plane of structure management. However, it is almost impossible that it is controlled in the individual ability, since collected information quantity is too enormous. For the purpose of intuitively controlling and processing these enormous information, we devised the system for the data management by freely moving in virtual reality space. In this paper, the basic structure of the system constructed by adopting WEB3D and RDBMS, is described, and the practicability is verified.
Nozawa, Takashi; Ozawa, Kazumi; Asakura, Yuki*; Koyama, Akira*; Tanigawa, Hiroyasu
Journal of Nuclear Materials, 455(1-3), p.549 - 553, 2014/12
Times Cited Count：15 Percentile：74.71(Materials Science, Multidisciplinary)SiC/SiC composite is a promising candidate material of fusion DEMO reactor. This paper aims to identify its damage tolerance and strength anisotropy by various characterization techniques such as acoustic emission (AE) monitoring, electrical resistivity (ER) measurement, and digital image correlation (DIC). The AE results identified that damage accumulation initiated prior to the proportional limit stress (PLS) by both tensile and compressive loadings for 2D composites. The preliminary AE waveform analysis implied that this AE detect strength corresponds to initiation of micro-cracking but the stress-strain curve shows further linearity due to the strong interfacial friction. Then fiber sliding occurred near the PLS, followed by the non-linearlity of the curve. The preliminary tensile test results using a notched specimen also suggest notch insensitivity of the composites in any loading directions. The detailed failure mechanism will eventually be discussed with ER and DIC results.
Xu, Z.*; Itakura, Kenichi*; Yamachi, Hiroshi*; Otsu, Shinichi*; Hayano, Akira; Matsui, Hiroya; Sato, Toshinori
Heisei-24 Nendo (2012 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.63 - 66, 2012/09
no abstracts in English
Nozawa, Takashi; Ozawa, Kazumi; Choi, Y.-B.*; Koyama, Akira*; Tanigawa, Hiroyasu
Fusion Engineering and Design, 87(5-6), p.803 - 807, 2012/08
Times Cited Count：29 Percentile：88.98(Nuclear Science & Technology)A SiC/SiC composite is a candidate material for a demonstration fusion power reactor. Considering the inherent anisotropy of composites with variety of fabric architecture is required to precisely predict axial and off-axial mechanical properties by various failure modes. This study evaluated crack propagation behavior by the various modes to provide a strength anisotropy map and we discussed a methodology to analytically predict this trend. The strength anisotropy maps identified for various fabric orientations clearly indicate that the composites failed by the mixed modes. Specifically, due to the axial anisotropy, five individual modes such as tensile/compressive strengths in the axial/transverse directions, respectively, as well as the in-plane shear strength, are identified to be essential. In this study, with the analytical criterion based on the Tsai-Wu model, the strength anisotropy could satisfactorily be described.
Nishitani, Takeo; Yamanishi, Toshihiko; Tanigawa, Hiroyasu; Nozawa, Takashi; Nakamichi, Masaru; Hoshino, Tsuyoshi; Koyama, Akira*; Kimura, Akihiko*; Hinoki, Tatsuya*; Shikama, Tatsuo*
Fusion Engineering and Design, 86(12), p.2924 - 2927, 2011/12
Times Cited Count：7 Percentile：48.91(Nuclear Science & Technology)Several technical R&D activities related to the blanket materials are newly launched as a part of the Broader Approach (BA) activities, which was initiated by the EU and Japan. According to the common interests of these parties for DEMO, R&Ds on reduced activation ferritic/martensitic (RAFM) steels as structural material, SiCf/SiC composites as a flow channel insert material and/or alternative structural material, advanced tritium breeders and neutron multipliers, and tritium technology are carried out through the BA DEMO R&D program, in order to establish the technical bases on the blanket materials and the tritium technology required for DEMO design. This paper describes overall schedule of those R&D activities and recent progress in Japan carried out by JAEA as the domestic implementing agency on BA, collaborating with Japanese universities and other research institutes.
Nozawa, Takashi; Ogiwara, Hiroyuki*; Kannari, Jun*; Kishimoto, Hirotatsu*; Tanigawa, Hiroyasu
Fusion Engineering and Design, 86(9-11), p.2512 - 2516, 2011/10
Times Cited Count：14 Percentile：71.96(Nuclear Science & Technology)A hot isostatic press (HIP) process is a key technology to fabricate a first wall of the blanket system utilizing a reduced-activation ferritic/martensitic (RAFM) steel such as F82H. A primary objective of this study is to characterize interfacial properties of HIPed F82H joints by torsion to identify the feasibility of this test method. It is apparent that the absorption energies of the HIP joints varied by the processing conditions, although the maximum shear strength was not much different. According to the fracture surfaces, it is indicated that the reduction of the absorption energy was due to the oxide formed on the interface of the HIP joint and this was consistent with the results of charpy impact tests. In conclusion, the torsion test method enables to precisely evaluate the shear properties of the HIPed joint interface and becomes one of promising powerful techniques for inspection of the HIP joints.
Nozawa, Takashi; Choi, Y.-B.*; Hinoki, Tatsuya*; Kishimoto, Hirotatsu*; Koyama, Akira*; Tanigawa, Hiroyasu
IOP Conference Series; Materials Science and Engineering, 18, p.162011_1 - 162011_4, 2011/09
Times Cited Count：10 Percentile：96.47(Materials Science, Ceramics)A SiC/SiC composite is one of attractive candidates for fission and nuclear fusion due to the proven irradiation tolerance coupled with the excellent baseline properties as refractory ceramics. Considering the inherent anisotropy of composites due to the variety of fabric architecture, it is required to identify the crack propagation behavior of SiC/SiC composites by various failure modes. This study aims to evaluate crack propagation behavior by the axial and off-axial tensile/compressive tests, Iosipescu test for in-plane shear, double-notch-shear test for inter-laminar shear and diametral compression test for inter-laminar detachment. Preliminary test results identified strength anisotropy maps, implying that the composites failed by the mixed modes. Specifically, it was found that the in-plane/inter-laminar shear modes had significant impacts on the results.
Nakata, Toshiya; Komazaki, Shinichi*; Kono, Yutaka*; Tanigawa, Hiroyasu
Metallurgical Journal, LXIII(Sp.), p.146 - 150, 2010/08
The small punch (SP) test is one method of small specimen test technology. We constructed a model for finite element analysis (FEA) using the Ramberg-Osgood equation to try to estimate tensile properties from the SP test. The results showed that the SP curve obtained from previous experiments could be reproduced by FEA to the point where the necking behavior of SP specimens became prominent. It was found that the relationship between the Mises equivalent stress at the point giving the largest equivalent plastic strain, and the total strain based on the Ramberg-Osgood equation, in the SP specimens, agreed well with the true stress-true strain curve plotted from tensile test measurements, and could thus be used to evaluate the 0.2% proof stress, tensile strength and uniform elongation.
Tanigawa, Hiroyasu; Nozawa, Takashi; Ando, Masami
JAEA-Review 2009-053, 89 Pages, 2010/03
JAEA-Review-2009-053.pdf:22.39MB
R&D on DEMO engineering was started from 2007 as the main activity of a DEMO design and R&D coordination center activity which was one of the international nuclear fusion energy research center (IFERC) activity of "Broader Approach" (BA) activity. In the DEMO engineering R&D activity, five "generic" R&D items were selected, which attract both Japan and EU interest and not specific to a DEMO design, i.e., (1) R&D on SiC/SiC Composites: (2) R&D on Tritium Technology: (3) R&D on Materials Engineering for DEMO Blanket: (R&D on reduced activation ferritic/martensitic steel: RAFM) (4) R&D on Advanced Neutron Multiplier for DEMO Blanket: (5) R&D on Advanced Tritium Breeders for DEMO Blanket. In first phase (2007 -2009), some part of preliminary R&D, which was defined in procurement arrangement (PA) between Japan and EU, is conducted by JAEA university collaboration. This report summarized the results from joint research activities about R&D on SiC/SiC composite and RAFM in 2008.
Tanigawa, Hiroyasu; Hirose, Takanori; Shiba, Kiyoyuki; Kasada, Ryuta*; Wakai, Eiichi; Serizawa, Hisashi*; Kawahito, Yosuke*; Jitsukawa, Shiro; Kimura, Akihiko*; Kono, Yutaka*; et al.
Fusion Engineering and Design, 83(10-12), p.1471 - 1476, 2008/12
Times Cited Count：78 Percentile：97.72(Nuclear Science & Technology)Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems. F82H, which were developed and studied in Japan, was designed with an emphasis on high temperature properties and weldability. The database on F82H properties is currently the most extensive available among the existing RAFMs. The objective of this paper is to review the R&D status of F82H and to identify the key technical issues for the fabrication of an ITER Test Blanket Module (TBM) suggested by recent achievements in Japan.
Xu, Z.*; Matsui, Hiroya; Sato, Toshinori*; Itakura, Kenichi*; Yamachi, Hiroshi*
Dai-12-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.647 - 652, 2008/09
Various data, such as investigation data, design data and/or field measured data arising during a course of the large-scale underground development are possible and important information, which can contribute to not only design and/or construction work but also maintenance of facilities. However, it is difficult to control and properly operate such enormous data throughout a long term included by an operation period of facilities. Authors developed management system for large-scale underground development system which adopted virtual reality technology and RDBMS as one answer for such problem. In addition, this system was applied experimentally to the Mizunami Underground Research Laboratory construction. This paper asks the validity of proposing technique, while the practice of design and mounting of the system is shown.
Nakata, Toshiya; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Komazaki, Shinichi*; Fujiwara, Mikio*; Kono, Yutaka*; Koyama, Akira*
Nihon Kinzoku Gakkai-Shi, 71(2), p.239 - 243, 2007/02
Times Cited Count：4 Percentile：33.26(Metallurgy & Metallurgical Engineering)no abstracts in English
Nakata, Toshiya; Komazaki, Shinichi*; Nakajima, Motoki*; Kono, Yutaka*; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Koyama, Akira*
Nihon Kinzoku Gakkai-Shi, 70(8), p.642 - 645, 2006/08
Times Cited Count：4 Percentile：34.16(Metallurgy & Metallurgical Engineering)no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Komazaki, Shinichi*; Kono, Yutaka*
no journal, ,
no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Shiba, Kiyoyuki; Komazaki, Shinichi*; Kono, Yutaka*; Koyama, Akira*
no journal, ,
no abstracts in English
Nakata, Toshiya; Tanigawa, Hiroyasu; Ando, Masami; Komazaki, Shinichi*; Kono, Yutaka*
no journal, ,
Reduced activation ferritic/martensitic steels are the first candidate material for fusion reactor, and will be used as the structural materials of ITER test blanket modules (TBM). TBM will be assembled by welding various parts, it is important to be clearly mechanical properties of weldments to qualify TBM structure. In this paper, unirradiated mechanical properties of weldments, which is consisted of weld metal, heat affected zone (HAZ) and base metal region, obtained from TIG and EB welded F82H IEA-heat were evaluated by charpy impact and creep test. The creep tests were carried out at temperatures of 773-873 K and at stress levels of 150-260 MPa, with the specimens which include weld metal and HAZ region in the gage section. In these conditions, rupture time of weldments yield to about 100-1000 hours. The mechanism of these properties deterioration will be discussed based on the detailed analyses on microstructure changes.
Tanigawa, Hiroyasu; Nakata, Toshiya*; Kim, D.-H.*; Ando, Masami; Shiba, Kiyoyuki; Hirose, Takanori; Komazaki, Shinichi*; Kono, Yutaka*; Koyama, Akira*
no journal, ,
Reduced activation ferritic/martensitic steels (RAFMs) are recognized as the primary candidate structural materials for fusion blanket systems, as they have been developed based on massive industrial experience of ferritic/martensitic steel replacing Mo and Nb of high chromium heat resistant martensitic steels (such as modified 9Cr-1Mo) with W and Ta, respectively. F82H (Fe-8Cr-2W-V, Ta) is the RAFM which is designed with emphasis on high temperature property and weldablility. Fusion blanket system will be suffer from high temperature/high pressure of its coolant, heat flux of fusion plasma etc., which cause creep and fatigue load on blanket system. On the other hand, the current blanket system design have complicated structure to achieve its function, and require long weld to fabricate its structure. In this paper, unirradiated creep and fatigue properties of base metal and weldments of F82H will be reviewed, and critical issues for design will be discussed.
