論文 - 森田 千尋
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Temperature deformation characteristics of acrylic windows used for tide embankments 査読あり
Yasui K., Shiokawa A., Watanabe M., Kinoshita H., Morita C.
AIMS Materials Science 8 ( 6 ) 932 - 951 2021年12月
担当区分：最終著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：AIMS Materials Science
Tide-embankment walls protecting coastal roads frequently contain numerous windows so that pedestrians and drivers can view the scenery without experiencing reduced sunlight. Tide-embankment windows must withstand extreme climatic conditions. However, the effects of temperature extremes on acrylic boards have rarely been studied. This paper proposes a simple method for constructing a high-temperature environment and a method for measuring strain on an acrylic plate. The deformation and strain of a 40-mm-thick acrylic tide-embankment window were determined experimentally and numerically in this study in a high-temperature environment, obtaining similar results; additionally, the numerical method was subsequently used to simulate a low-temperature environment. Because thermal conductivity was low, the internal temperature of the thick acrylic board did not immediately change with the temperature of the surface, and thermal expansion and contraction of the board were restrained. Temperature-induced deformation effects were low across the entire range of temperatures and heating rates recorded in coastal Japan.
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Al系溶射皮膜の長期大気暴露試験における耐候性評価 査読あり
中野敦，白井敬大，森田千尋，押川渡，米沢昇
鋼構造年次論文報告集 29 526 - 537 2021年11月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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Pan H., Zhao C., Xing J., Zhang R., Morita C.
IOP Conference Series: Earth and Environmental Science 861 ( 7 ) 2021年10月
担当区分：最終著者 記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IOP Conference Series: Earth and Environmental Science
The discrete element method is widely used in rock mechanics, but its computational efficiency limits its development. To improve the accuracy of a discrete element model, the particle size of the entire model needs to be decreased according to the current theory. However, only the range of interest (ROI) is usually concentrated, and the background (BG) refinement is a waste of computing power. The paper proposes a gradient particle size specimen modeling scheme. The resolution of ROI is increased while the resolution of BG is retained. The probability of particle generation is derived from the statistical point of view that the porosity should be consistent. The computational performance is analyzed from the perspective of time complexity. With the edge particle size being 2.0 times the central particle size, only about 26% of the computing time is required. A series of unconfined compression experiments are subsequently carried out to verify the modeling scheme. The characteristics of the gradient particle specimen modeling scheme and the uniform particle size specimen modeling scheme are highly consistent, including the load-deform curves, crack progress curves, crack initiation patterns, and failure patterns. Finally, the deficiencies of the modeling scheme are discussed, including the unconfined compressive strength (UCS) reduction, which is probably due to the reduction of the coordination number. Further research will be conducted.
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Qian Y., Zhao C., Xing J., Zhou Y., Morita C.
IOP Conference Series: Earth and Environmental Science 861 ( 7 ) 2021年10月
担当区分：最終著者 記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IOP Conference Series: Earth and Environmental Science
Damage and fracture of rocks is a comprehensive result of strain energy dissipation and release. In order to study the energy evolution mechanism of hard brittle rock masses during failure process, uniaxial compression tests on the granite specimens with a single pre-existing flaw are carried out with digital image correlation method (DIC). The results indicate that: (1) The stress fluctuation before structural failure corresponds to the sudden increase of the dissipated energy, the essence is that rock masses occur obviously damage and cracking. (2) For medium flaw dip angles, the stress fluctuation occurs repeatedly in stages, whose strain energy is dissipated gradually; for large or small dip angles, the stress fluctuation is almost not appeared, and the energy dissipation is insignificant. (3) With the increase of flaw dip angles, the dissipated energy ratio at the peak stress first increases and then decreases showing an inverted U-shaped, resulting in a similar law of rock damage but a contrary law of strength; the corresponding elastic energy ratio is U-shaped of decreasing first and then increasing, causing the structural failure changes from dynamic to static and then to dynamic again. The results can provide theoretical references for the formation mechanism and prevention method of dynamic disasters of rock underground engineering.
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複数の CNN 識別器を用いた複数のパッチ画像からの耐候性鋼材のさびの外観評価
有村 和也, 重井 徳貴, 森田 千尋, 石塚 洋一, 宮島 廣美
日本知能情報ファジィ学会 ファジィ システム シンポジウム 講演論文集 37 ( 0 ) 694 - 698 2021年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本知能情報ファジィ学会
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UAVとSfM技術を利用したコンクリート構造物のひび割れ幅計測の道路橋への適用 査読あり
本多雅匠, 森田千尋, 安井賢太郎, 出水享, 中野敦
実験力学 21 ( 3 ) 232 - 239 2021年9月
担当区分：責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本実験力学会
Aging road bridges have become a problem in Japan, and regular inspections are carried out once every five years by proximity visual inspection. However, the shortage of inspection technicians and budget is a problem, and there is a need for inspection technology that is efficient and can perform diagnosis equivalent to proximity visual inspection. In this study, we focused on the image processing technology of the 3D data generation software SfM, generated a 3D model from the crack image of the concrete member taken by UAV, and compared the actual crack width with the crack width obtained from the 3D model. As a result of the verification, it was suggested that by using UAV and SfM, the crack width of 0.2 mm or more can be judged with relatively high accuracy by photographing the area around the actual crack from a short distance.
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Al-5mass%Mg合金溶射皮膜の耐食性に関する研究
白井敬大，中野敦，森田千尋，押川渡，米沢昇
九州橋梁・構造工学研究会シンポジウム論文集 8 35 - 40 2020年12月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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複数のパッチ画像を用いたCNNによる耐候性鋼材のさびの外観評価
有村和也、重井徳貴、森田千尋、石塚洋一、宮島廣美
日本知能情報ファジィ学会九州支部学術講演会予稿集 22 21 - 25 2020年11月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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腐食促進環境下におけるAl系擬合金及び合金溶射皮膜の防食特性 査読あり
中野敦，白井敬大，森田千尋，押川渡，米沢昇
鋼構造年次論文報告集 28 19 - 25 2020年11月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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Atmospheric Corrosion Behavior of Arc Thermal Spray Zn-Al Coatings Using Accelerated Atmospheric Field Test for Ten-Year
A. Nakano, W. Oshikawa, N. Yonezawa, C. Morita and Y. Shirai
ECSarXiv Preptints 2020年10月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
DOI： 10.1149/osf.io/59ykt
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Weatherability of Arc Thermal Spray Al-Mg Coating in a Simulated Marine Environment
A. Nakano, W. Oshikawa, N. Yonezawa, C. Morita and Y. Shirai
ECSarXiv Preptints 2020年10月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
DOI： 10.1149/osf.io/zq9x2
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Mechanical Characteristics of the Butterfly Bridge Using the Finite Element Method
Asri saputra HENDRA, Chihiro MORITA, Shunsuke FUKAMI, Motohiro OSHIKATA
Memorirs of Faculty of Engineering University of Miyazaki 49 1 - 6 2020年9月
記述言語：英語 掲載種別：研究論文（大学，研究機関等紀要）
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人工海水を用いた腐食環境下におけるZn-30mass%Al溶射皮膜の大気暴露特性 査読あり
中野敦, 押川渡, 米沢昇, 森田千尋, 白井敬大
鋼構造論文集 27 ( 106 ) 106_51 - 106_60 2020年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：社団法人 日本鋼構造協会
A nine-year atmospheric exposure test was performed on Zn-30mass%Al thermal spray coating under the corrosion environment using the artificial sea water. A similar corrosion test carried out to compare the properties with Hot-dip-Zinc coating. Atmospheric corrosion properties of thermal spray coating were evaluated by surface observation, X-ray diffraction, film thickness measurement and element analyses using EPMA. From these analysis results, the thickness of thermal spray coating was not impacted greatly under corrosion environment using the artificial sea water. In addition, corrosion resistance of Zn-30mass%Al thermal spray coating is much higher than that of Hot-dip-Zinc coating.
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Zhao Y., Huang M., Ouyang X., Tang J., Morita C.
Engineering Analysis with Boundary Elements 113 26 - 39 2020年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Engineering Analysis with Boundary Elements
© 2019 Convection-diffusion equation is widely used in many fields of science, technology and engineering. The calculation is usually difficult and time-consuming. In this paper, a highly efficient meshless boundary type method called the half boundary method (HBM) is applied to solve convection diffusion equation. The main idea of HBM is to reduce the order of the convection–diffusion equations by introducing new variables and construct the relations of the variables between the nodes inside the area and the nodes on half of the boundaries by using integration, inverse matrix and reasonable transformation. Using the relations, the temperature and heat flux at any point can be calculated simultaneously after obtaining the variables on half of the boundaries according to the boundary conditions. Given that unknown variables exist only on half of the boundaries, the internal storage in the HBM is less than that required in the finite volume method when the division number is large. And it doesn't need shape functions in the finite element method or a fundamental solution in the boundary element method. HBM can obtain very precise results when solving the convection dominated problems. The validity and accuracy of the proposed method are authenticated by the numerical examples.
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A new procedure for solving neutron transfer problems 査読あり
Tang J., Huang M., Zhao Y., Ouyang X., Morita C.
Annals of Nuclear Energy 138 2020年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Annals of Nuclear Energy
© 2019 Elsevier Ltd In this paper, we propose an accurate and efficient procedure named half boundary method (HBM) to solve one-dimensional neutron transfer problems. In the process of solving the Boltzmann transfer equation, the relationships between every two neighboring nodes are solved first. Then, starting from a vacuum boundary, the neighboring relationships are iteratively applied to solve the neutron distribution. In two reflective boundaries problems, the reflective boundaries are applied to solve the neutron flux at the boundaries first, then the neutron distribution is solved similar to the vacuum boundary problems. Different from the traditional method, no matter how many segments are dispersed, at most two-order matrixes are involved in HBM calculations. So, HBM shows great potential in saving computational memory, particularly for problems with huge girds. In this paper, we introduce the fundamental theory and investigate the applicability, accuracy, and efficiency of HBM by solving five examples with different situations and boundaries.
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SfMを用いた構造物の３次元モデル化について
小川裕棋、森田千尋、松川尚史、塩竃柚貴、白井敬大
「歴史的構造物の非破壊検査」ミニシンポジウム論文集 3 41 - 46 2020年3月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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Zhao C., Niu J., Zhang Q., Yu S., Morita C.
Journal of Materials in Civil Engineering 31 ( 12 ) 2019年12月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Materials in Civil Engineering
© 2019 American Society of Civil Engineers. The expanded distinct element method based on a strain strength criterion was applied herein with the aim of analyzing and comparing the cracking behaviors of rock-like specimens with single flaws under uniaxial and biaxial compressions. The cracking characteristics in uniaxial and biaxial compressions were compared and the effects of confining pressure on the tensile/shear behaviors were analyzed. The confining pressure obviously changed the boundary condition and the cracking behaviors in biaxial compression. The initiation stress, the peak strength, and the number of shear cracks in biaxial compression were obviously larger than in uniaxial compression. The confining pressure affected the initiation and propagation of the secondary cracks, the failure mechanisms, and the distribution of horizontal displacement fields in a large extent. The initiation and propagation of the tensile cracks were inhibited by the confining pressure. An increase in confining pressure had no obvious effects on the initiation time and the propagation rates of the shear cracks but mainly affected the numbers of shear cracks.
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人工海水腐食環境下におけるZn-Al溶射皮膜の腐食性評価 査読あり
森田千尋，中野敦，白井敬大，押川渡，米沢昇
鋼構造年次論文報告集 27 374 - 383 2019年11月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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A HBM approach for temperature and heat flux convection–diffusion equations and nonlinear problems 査読あり
Zhao Y., Huang M., Tang J., Ouyang X., Morita C.
Nuclear Engineering and Design 342 115 - 127 2019年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Nuclear Engineering and Design
© 2018 Elsevier B.V. Solving convection diffusion equation is widely required in many fields of science, technology and engineering. The calculation is usually difficult and time-consuming. In this paper, a highly efficient method, the half boundary method (HBM), is proposed to solve the convection diffusion equation. The main idea of HBM is to reduce the order of the convection–diffusion equations by introducing a new variable and constructing the relations of the variables between the nodes inside the area and the nodes on half of the boundaries. Using the relations, the temperature and heat flux at any point can be calculated simultaneously, after obtaining the variables on the half of the boundaries. Because the unknown variables exist on only half of the boundaries, the computing matrix is reduced to only second order regardless of the number of nodes, the internal storage in the HBM is even less than that required in the finite volume method, making the HBM extremely fast and efficient. The validity and accuracy of the proposed method are investigated. Numerical studies for steady and unsteady, as well as nonlinear convection–diffusion equations, were carried out. The results show that HBM is more accurate than the finite volume method under identical grids conditions.
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中島和俊, 加納勇, 安波博道, 森田千尋
鋼構造論文集 25 ( 98 ) 35 - 43 2018年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：社団法人 日本鋼構造協会
The soundness evaluation of weathering steel bridges is generally based on external visual inspection and is not quantitative, it is known that it greatly influences the experience and subjectivity of the evaluator. In this study, patch type exposure tests were conducted on 7 bridges of weathering steel bridges managed by Nagasaki prefecture, and the soundness was evaluated based on corrosion prediction. Also, the corrosion behaviors of each part such as flange and web were analyzed and evaluated.