Published Papers - AKIYAMA Hiroaki

和歌山県における公開天文台の現状と諸課題をめぐる一考察 : 紀美野町みさと天文台とかわべ天文公園を事例に—Exploring the current issues of public astronomical observatories in Wakayama Prefecture : A case study of Kimino Town Misato Astronomical Observatory and Kawabe Astronomical Observatory

澤田 幸輝, 米澤 樹, 秋山 演亮, 富田 晃彦, 佐藤 祐介, 林 美由貴

観光学 ( 和歌山大学観光学会 )  31   15 - 31   2024.09

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In recent years, museums in Japan have been required to operate in two aspects: as public facilities, with an education especially for local residents and tourism attraction. In this paper, a qualitative study using interviews and secondary data research was conducted using Misato Astronomical Observatory and Kawabe Cosmic Park as case studies. Misato Astronomical Observatory and Kawabe Astronomy Park are both public astronomical observatories in Wakayama Prefecture and have many similarities in terms of the characteristics of their facilities. However, Misato Astronomical Observatory is still in operation, whereas Kawabe Astronomy Park was closed in 2014. The purpose of this paper is to explore the direction of sustained operation of public astronomical observatories by identifying changes in the social environment surrounding the facilities over time, and to provide a preliminary examination of the role that public astronomical observatories should play.

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Removing Sunlight Damage Patterns in Shatter-Less Bolometer Images by Utilizing Deepspace Observations.

Toru Kouyama, Soushi Kato, Tetsuya Fukuhara, Hiroaki Akiyama, Ryosuke Nakamura

2018 IEEE International Geoscience and Remote Sensing Symposium(IGARSS) ( IEEE )    3315 - 3318   2018

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UNIFORM-1 is a small satellite that helps in the prevention of severe fire hazards by detecting the wildfire at an early stage. UNIFORM-1 is equipped with an un-cooled bolometer imager (BOL), which observes temperature distributions of the earth surface. Uniquely, BOL is not equipped with any shutter mechanism to reduce the risk associated with the shutter that impacts the ability to conduct any observation in space. As a trade-off of shutter exclusion, BOL saw the Sun in its field of view (FOV) many times and the sunlight damage caused large brightness temperature error (60 K) in BOL images. To reduce the error, we have proposed a new calibration procedure utilizing deepspace observations, which enables the measurement of the increase in digital count offset due to the sunlight in a BOL image. After the correction, we successfully reduced the damage, and the relative accuracy of brightness temperature improved to more than 2 K, which is enough to detect a wildfire with a size smaller than one-pixel scale.

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Development of a Candy Hybrid Rocket Motor for Undergraduate Space Education

Yutaka WADA, Yo KAWABATA, Kenji OGIMOTO, Hiroaki AKIYAMA, Takao YANAGI, Seiichi SAKAMOTO

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( Japan Society for Aeronautical and Space Sciences )  16 ( 6 ) 506 - 510   2018

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Detection of Small Wildfire by Thermal Infrared Camera With the Uncooled Microbolometer Array for 50-kg Class Satellite.

Tetsuya Fukuhara, Toru Kouyama, Soushi Kato, Ryosuke Nakamura, Yukihiro Takahashi, Hiroaki Akiyama

IEEE Transactions on Geoscience and Remote Sensing ( IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC )  55 ( 8 ) 4314 - 4324   2017

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The thermal infrared camera with the uncooled microbolometer array based on commercial products has been developed in a laboratory of a Japanese university and mounted to a 50-kg class small satellite specialized for discovering wildfire. It has been launched in 2014 and successfully detected considerable hotspots not only wildfire but also volcanoes. Brightness temperature derived from observation has been verified, and the scale of observed wildfire has been provisionally presumed; the smallest wildfire ever detected has a flame zone less than similar to 300 m(2) and the fire radiative power = similar to 35.4 mW. It is 1/30th the size of the initial requirement estimated in the design process. Our thermal infrared camera developed in a short time with low cost has attained enough ability to discover small wildfire which is suppressive at initial attack.

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A co-operation with Serbia on Space and Astronomy Education: A report of activities in 2013

Akihiko Tomita, Dušan Radosavljević, Hiroaki Akiyama, Masachika A. Kijima, Masami Okyudo, Chiaki Yoshizumi, Naoko Sato, Tomomi Otani

Bulletin of Institute for Education on Space ( 和歌山大学宇宙教育研究所 )  ( 3 ) 79 - 84   2014.03  [Refereed]

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The global distribution of pure anorthosite on the Moon

Makiko Ohtake, Tsuneo Matsunaga, Junichi Haruyama, Yasuhiro Yokota, Tomokatsu Morota, Chikatoshi Honda, Yoshiko Ogawa, Masaya Torii, Hideaki Miyamoto, Tomoko Arai, Naru Hirata, Akira Iwasaki, Ryosuke Nakamura, Takahiro Hiroi, Takamitsu Sugihara, Hiroshi Takeda, Hisashi Otake, Carle M. Pieters, Kazuto Saiki, Kohei Kitazato, Masanao Abe, Noriaki Asada, Hirohide Demura, Yasushi Yamaguchi, Sho Sasaki, Shinsuke Kodama, Junya Terazono, Motomaro Shirao, Atsushi Yamaji, Shigeyuki Minami, Hiroaki Akiyama, Jean-Luc Josset

NATURE ( NATURE PUBLISHING GROUP )  461 ( 7261 ) 236 - U110   2009.09

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It has been thought that the lunar highland crust was formed by the crystallization and floatation of plagioclase from a global magma ocean(1,2), although the actual generation mechanisms are still debated(2,3). The composition of the lunar highland crust is therefore important for understanding the formation of such a magma ocean and the subsequent evolution of the Moon. The Multiband Imager(4) on the Selenological and Engineering Explorer (SELENE)(5) has a high spatial resolution of optimized spectral coverage, which should allow a clear view of the composition of the lunar crust. Here we report the global distribution of rocks of high plagioclase abundance ( approaching 100 vol.%), using an unambiguous plagioclase absorption band recorded by the SELENE Multiband Imager. If the upper crust indeed consists of nearly 100 vol.% plagioclase, this is significantly higher than previous estimates of 82-92 vol.% (refs 2, 6, 7), providing a valuable constraint on models of lunar magma ocean evolution.

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Quantitative evaluation of the impact fracture surfaces of SS400 steel by the three-dimensional geometrical analysis

Manabu Tanaka, Michihiro Tagami, Ryuichi Kato, Hiroaki Akiyama, Naohide Oyama, Junji Ono

ISIJ INTERNATIONAL ( IRON STEEL INST JAPAN KEIDANREN KAIKAN )  47 ( 1 ) 178 - 186   2007

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The fractal dimension and the surface roughness of the fracture surface was estimated using the height data generated by the stereo matching method on Charpy V-notch specimens of the SS400 steel impact-fractured in the temperature range from 194 K (-79 degrees C) to 273 K (0 degrees C). The representative fracture surfaces were quasi-cleavage fracture surface with river patterns and steps between facets at 194 K and ductile fracture surface with dimples and shear steps at 273 K. On the region close to the notch root (fracture initiation site), a definite correlation was not found between the absorbed energy and the fractal dimension of the fracture surface, but both absorbed energy and surface roughness increased with temperature because of increased proportion of ductile fracture surface with the larger surface roughness. There was essentially no difference in the fractal dimension between quasi-cleavage fracture surface and ductile fracture surface. Fracture process including fracture initiation, local crack growth or finally fractured part could be examined by the detection of characteristic fracture patterns using the fractal dimension map (FDM) and the surface roughness map (SRM). Detected steps of various sizes were associated with river patterns or fracture at ferrite grain boundaries on the quasi-cleavage fracture surface, and were associated with dimple walls or shear steps on the ductile fracture surface. Steps on both fracture surfaces were formed by common mechanism, namely, by plastic deformation (shear deformation). The density of steps was larger on the quasi-cleavage fracture surface than on the ductile fracture surface. These steps led to a large fractal dimension of the quasi-cleavage fracture surface comparable with the ductile fracture surface with dimples.

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Multi-band imaging camera and its sciences for the Japanese near-earth asteroid mission MUSES-C

Tsuko Nakamura, Akiko M. Nakamura, Jun Saito, Sho Sasaki, Ryosuke Nakamura, Hirohide Demura, Hiroaki Akiyama, David Tholen

Earth, Planets and Space   53 ( 11 ) 1047 - 1063   2001  [Refereed]

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In this paper we present current development status of our Asteroid Multi-band Imaging CAmera (AMICA) for the Japan-US joint asteroid sample return mission MUSES-C. The launch of the spacecraft is planned around the end of 2002 and the whole mission period till sample retrieval on Earth will be approximately five years. The nominal target is the asteroid 1998SF36, one of the Amor-type asteroids. The AMICA specifications for the mission are shown here along with its ground-based and inflight calibration methods. We also describe the observational scenario at the asteroid, in relation to scientific goals. © 2001, The Seismological Society of Japan, Society of Geomagnetism and Earth, Planetary and Space Sciences, The Volcanological Society of Japan, The Geodetic Society of Japan, The Japanese Society for Planetary Sciences. All rights reserved.

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