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Koga, Jun*; Takada, Shusuke*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Niinomi, Yudai*; Okudaira, Takuya*; et al.
Physical Review C, 105(5), p.054615_1 - 054615_5, 2022/05
Times Cited Count:3 Percentile:66.85(Physics, Nuclear)no abstracts in English
Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count:6 Percentile:51.19(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Okudaira, Takuya*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Niinomi, Yudai*; Sakai, Kenji; et al.
Physical Review C, 104(1), p.014601_1 - 014601_6, 2021/07
Times Cited Count:4 Percentile:57.13(Physics, Nuclear)Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count:43 Percentile:96.93(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Yamamoto, Tomoki*; Okudaira, Takuya; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.
Physical Review C, 101(6), p.064624_1 - 064624_8, 2020/06
Times Cited Count:9 Percentile:73.66(Physics, Nuclear)Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
Times Cited Count:259 Percentile:99.73(Multidisciplinary Sciences)The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Oshikawa, Takumi*; Funakoshi, Yoshihiko*; Imaoka, Hiroshi*; Yoshikawa, Kohei*; Maari, Yasutaka*; Iguchi, Masahide; Sakurai, Takeru; Nakahira, Masataka; Koizumi, Norikiyo; Nakajima, Hideo
Proceedings of 19th International Forgemasters Meeting (IFM 2014), p.254 - 259, 2014/09
ITER is a large-scale experiment that aims to demonstrate that it is possible to produce commercial energy from fusion. ITER Toroidal Field Coil Case (hereinafter referred to as "ITER TFCC") is one of the important components of ITER. The ITER TFCC materials are made of high nitrogen austenitic stainless steel and having various configurations. The ITER TFCC material which manufactured by JCFC has a complex configuration with heaver thickness than other materials. It is difficult to form near net shape to delivery configuration by ordinary open die forging method such as upset and stretching, because the ITER TFCC materials manufactured by JCFC have a complex configuration. Therefore ingot weight and lead time of machining increase when ITER TFCC materials are forged by ordinary open die forging method. Moreover, in order to get good attenuation at Ultrasonic examination, it is necessarily to make fine and uniform grain of the material. However, it is impossible to control grain size of austenitic stainless steel by heat treatment. The grain becomes fine and uniform by only forging process with suitable condition. Therefore, JCFC has studied suitable forging method to become near net shape to delivery configuration and also to get fine grain of center of the material. Based on these result, ITER TFCC materials were manufactured. This innovative forging process led to reduce the weight of ingot compared with general forging. And it had good Ultrasonic attenuation. It was confirmed that the results of material test and nondestructive examination satisfied the requirements of Japan domestic agency (hereinafter referred to as "JADA"). Moreover, the test coupons were taken from center of thick part of product and used for various tests. As the result of tests, it was confirmed that results of material test satisfied the requirements of JADA. It is clear that this innovative forging method is very suitable process for manufacturing of ITER TFCC materials.
Masuda, Takuya*; Fukumitsu, Hitoshi*; Fugane, Keisuke*; Togasaki, Hirotaka*; Matsumura, Daiju; Tamura, Kazuhisa; Nishihata, Yasuo; Yoshikawa, Hideki*; Kobayashi, Keisuke*; Mori, Toshiyuki*; et al.
Journal of Physical Chemistry C, 116(18), p.10098 - 10102, 2012/05
Times Cited Count:118 Percentile:93.76(Chemistry, Physical)In situ electrochemical X-ray absorption fine structure (XAFS) measurements were performed at the Pt L and Ce L edges of the Pt-CeO/C catalyst, which was prepared by a combined process of precipitation and coimpregnation methods, as well as at the Pt L edge of the conventional Pt/C catalyst in oxygen-saturated HSO solution to clarify the role of CeO in the reduction of the overpotential for the oxygen reduction reaction (ORR) at the Pt-CeO nanocomposite compared with the conventional Pt/C catalyst. XAFS measurements clearly show that the enhancement of ORR activity is attributed to the inhibition of Pt oxide formation by the CeO layer, of which Ce was oxidized to Ce instead of Pt at the Pt oxide formation potential.
Nabara, Yoshihiro; Nunoya, Yoshihiko; Isono, Takaaki; Hamada, Kazuya; Uno, Yasuhiro; Takahashi, Yoshikazu; Nakajima, Hideo; Tsuzuku, Seiji*; Tagawa, Kohei*; Miyashita, Katsumi*; et al.
Teion Kogaku, 47(3), p.140 - 146, 2012/03
no abstracts in English
Yoshikawa, Takamichi*; Iwasaki, Tomohiko*; Endo, Hideki*; Suyama, Kenya; Shikoda, Keiji*; Yamada, Kohei*; Hamahata, Yoshiki*; Oeda, Shin*
no journal, ,
In order to develop a fuel design system of BWR based on opened calculation codes, a burnup code system SWAT2 using continuous energy Mote Carlo code was revised to include a function of branch calculation. A tool to evaluate lattice constants used in calculation code adopting modern nodal method was also developed and validated by comparison with CASMO.
Fugane, Keisuke*; Mori, Toshiyuki*; Wu, Y. Y.*; Yamamoto, Shunya; Maekawa, Yasunari; Yoshikawa, Hideki*; Yamashita, Yoshiyuki*; Ueda, Shigenori*; Vladimir, M.*; Suzuki, Akira*; et al.
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Endo, Shunsuke; Abe, Ryota*; Ishizaki, Kohei*; Oku, Takayuki; Okudaira, Takuya*; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; Sakai, Kenji; Shima, Tatsushi*; et al.
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Okudaira, Takuya*; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; Sakai, Kenji; et al.
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Yoshikawa, Hiromoto*; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Okudaira, Takuya*; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; et al.
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Kameda, Kento*; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Okudaira, Takuya*; Kitaguchi, Masaaki*; Kimura, Atsushi; Sakai, Kenji; et al.
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Fujiie, Takuhiro*; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Okudaira, Takuya*; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; et al.
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Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Okudaira, Takuya*; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; Sakai, Kenji; et al.
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Kitaguchi, Masaaki*; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Okudaira, Takuya*; Kameda, Kento*; Kimura, Atsushi; Sakai, Kenji; et al.
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Endo, Shunsuke; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Oku, Takayuki; Okudaira, Takuya*; Omer, M.; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; et al.
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Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Endo, Shunsuke; Oku, Takayuki; Okudaira, Takuya*; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; Sakai, Kenji; et al.
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