著者

Yoshinori IIZUKA(飯塚芳徳) Sumito MATOBA(的場澄人) Masahiro MINOWA(箕輪昌紘) Tetsuhide YAMASAKI(山崎哲秀) Kaoru KAWAKAMI(川上薫) Ayako KAKUGO(角五綾子) Morihiro MIYAHARA(宮原盛厚) Akihiro HASHIMOTO(橋本明弘) Masashi NIWANO(庭野匡思) Tomonori TANIKAWA(谷川朋範) Koji FUJITA(藤田耕史) Teruo AOKI(青木輝夫)

出版者

THE JAPANESE SOCIETY OF SNOW AND ICE

雑誌

Bulletin of Glaciological Research (ISSN:13453807)

巻号頁・発行日

vol.39, pp.1-12, 2021 (Released:2021-10-13)

参考文献数

18

被引用文献数

2

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In order to construct reliable deposited-aerosol database on the Anthropocene (from 1850 to 2020), we obtained a 250-meter-long ice core from the Southeastern Greenland Dome on May and June 2021, where is one of the highest accumulation domes in Greenland. The age of the ice core at a depth of 250 m was roughly estimated to be AD 1827 based on the timescale from a previously analyzed shallower ice core. The age of the sampled ice core satisfied the prerequisite conditions for constructing aerosol deposition database for Anthropocene. In addition, surface elevation, borehole temperatures, and internal stratigraphy of the ice sheet were performed, and meteorological and snow-pit observations were also conducted. Furthermore, we sampled aerosol and snow from the ice sheet for chemical and physical analyses.

著者

Masahiro KANAZAKI Kai TOMISAWA Koji FUJITA Akira OYAMA Hiroki NAGAI

出版者

The Japan Society of Mechanical Engineers

雑誌

Journal of Fluid Science and Technology (ISSN:18805558)

巻号頁・発行日

vol.14, no.3, pp.JFST0017, 2019 (Released:2019-12-19)

参考文献数

11

被引用文献数

2

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We redesigned the Mars Airplane Balloon Experiment Two (MABE-2) based on MABE-1 to improve the vehicle’s stability and controllability. Following the redesign, the MABE-2 vehicle had a larger horizontal tail volume than that of MABE-1 for improved stability performance. In addition, to further improve the stability and control characteristics, a rectangular planform was employed for the horizontal tail wing; in contrast, MABE-1 had a tapered planform. The vertical tail position of MABE-2 was moved to the end of the horizontal tail wing, because the vertical tail of MABE-1, which was positioned at the mid span of the horizontal tail wing, showed aerodynamic interaction with the horizontal tail wing. In this paper, we discussed the aerodynamic performance of a control surface based on computational fluid dynamics with variation in the deflection angle between the control surface and the horizontal tail (elevator), and we examined the effects of this redesign on longitudinal control characteristics. Numerical investigations confirmed the linear variation in the pitching moment and the aerodynamic force with the changing elevator deflection angle in MABE-2. Surface pressure observations indicated that MABE-2 shows a smooth variation in the pressure distribution with changing elevator deflection angle, while MABE-1 does not. These results demonstrate that the aerodynamic control characteristics of MABE-2 were improved in comparison to those of MABE-1.

著者

Shunsuke MURAI Tomohiko MATOBA Christopher T. NELSON Takuya KOMINE Koji FUJITA Xiaoqing PAN Katsuhisa TANAKA

出版者

公益社団法人 日本セラミックス協会

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.121, no.1416, pp.710-713, 2013-08-01 (Released:2013-08-01)

参考文献数

21

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We have prepared composites with anisotropic microstructure consisting of silver nanoparticles and zinc oxide pillars using an oblique angle deposition technique, and examined the optical response originating from their anisotropic morphology. The sample was obtained in three steps. First, the assembly of silver nanoparticles was prepared on a silica glass substrate by electron-beam deposition of the silver thin film and subsequent heat treatment. Next, zinc oxide was obliquely grown by using a pulsed laser deposition. Finally the zinc oxide was crystallized by the post annealing to make an array of inclined pillars grown on the top of the silver nanoparticles. The structure and morphology of the composites were elucidated by a combination of X-ray diffraction analysis and transmission electron microscopy. Optical rotation spectroscopy clarifies that the composite shows optical birefringence due to its inclined pillar morphology. The optical rotation spectrum exhibits two peaks, one being associated to the localized surface plasmon resonance of the silver nanoparticles and the other the excitons in the zinc oxide pillars. The present fabrication method is simple and can be applied to obtain anisotropic composites with relatively large dimensions.

著者

Masato YAMAGISHI Yusuke YAHAGI Masanori OTA Yusuke HIROSE Shinsuke UDAGAWA Tatsuro INAGE Shigeya KUBOTA Koji FUJITA Kiyonobu OHTANI Hiroki NAGAI

出版者

The Japan Society of Mechanical Engineers

雑誌

Journal of Fluid Science and Technology (ISSN:18805558)

巻号頁・発行日

vol.16, no.3, pp.JFST0021, 2021 (Released:2021-10-01)

参考文献数

16

被引用文献数

4

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Three-dimensional density measurement of unsteady flow field around a projectile (φ = 8mm) is carried out in the ballistic range at Institute of Fluid Science, Tohoku University. The purpose of this study is to obtain the density distribution including its wake region in non-axisymmetric unsteady flow. The projectile’s Mach number in the experiment is 1.35. Simultaneous multi-angle BOS measurement system using twelve digital cameras and pulsed LEDs is installed in the test chamber of the ballistic range. The Color-Grid Background Oriented Schlieren (CGBOS) technique is used in the measurement system to obtain the projection data of density gradient. Algebraic Reconstruction Technique (ART) method and Successive Over Relaxation (SOR) method are used to obtain the density distribution from projection data. To improve the accuracy of 3D reconstruction, we evaluate the view-angle of the measurement system in the present study. The result shows that the bow shock, expansion wave and recirculation zone can be confirmed by the proposed method. However, bow shock in each method are thicker than the schlieren image due to the blur of the CGBOS images. Even then, the 3D shape of density distribution reconstructed by proposed method can be reliable, and the relative error of obtained density between the theoretical value for normal shock relation is about 5% at the bow shock.

著者

Koji FUJITA Remi LUONG Hiroki NAGAI Keisuke ASAI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.10, no.ists28, pp.Te_5-Te_10, 2012 (Released:2012-08-30)

被引用文献数

1 7

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The presence of an atmosphere on Mars signifies that an aircraft could travel in its atmosphere using the aerodynamic forces of flight. A reconnaissance aircraft offers the possibility to obtain high resolution data on a regional scale of several hundreds to thousands of kilometers, which cannot be achieved with rovers or satellites. However, conventional aircraft design cannot be applied for a Mars Airplane because of the nature of the Martian atmosphere and the constraints from transportation from Earth to Mars. This paper presents the conceptual design of a fixed-wing airplane for Mars, and the design rationale undertaken following the constraints set by the Martian environment. As a result, the main wing area was calculated to be 1.2 m2. It was folded using two hinges to be packed into an aeroshell. The proposed Mars Airplane has four notches on its main wing. They make packing easier to keep the wing area maximized, making the Mars Airplane more compact.

著者

Roseline KF YONG Koji FUJITA Patsy YK CHAU Hisanaga SASAKI

出版者

Japanese Society of Public Health

雑誌

日本公衆衛生雑誌 (ISSN:05461766)

巻号頁・発行日

vol.67, no.4, pp.237-246, 2020-04-15 (Released:2020-05-08)

参考文献数

32

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Objectives This study aimed to assess the relevance of hikikomori to a variety of socio-demographic characteristics and socio-psychological conditions and examined these relationships by gender.Methods The study employed a cross-sectional design. A questionnaire survey was conducted among 2,459 participants aged 15-64 years and living in Happo-cho, Akita. The outcome variable, hikikomori, was characterized by “not having participated in any social events nor interacted with others besides family members for more than six months.” Exposure variables included sex, age, marital status, occupational status, outdoor frequencies, health, socio-psychological well-being, and availability of social support. Using Chi-square test of independence and multiple logistic regression, the results indicated the impact of the individual factors and the combined impact of all potential variables on the likelihood of being hikikomori in both participant groups: men and women.Results The effective response rate was 54.5%. Those who socially withdrew for six months or more (n=164 (6.7%); 53.7% men, 46.2% women) were classified as being hikikomori; of these, 45.7% had been withdrawn for more than 10 years. Hikikomori men were more likely to have severe symptoms of mental illness, poorer overall self-rated health, feelings of distress, and passive suicidal ideation than non-hikikomori men, but not hikikomori women. Furthermore, after adjusting for all tested variables as possible confounding factors, being jobless and having fewer outdoor frequencies were associated with being a hikikomori man, and being a homemaker and having no social support were associated with being a hikikomori woman.Conclusion Occupational status and outdoor frequencies are relevant factors for assessing the likelihood of being a hikikomori. Characteristics of hikikomori manifest differently in men and women. Having social support may help women avoid transitioning into a hikikomori. Incorporating emotional and mental health management into intervention programs may help better target potential beneficiaries among Japanese men.